Anti-glare easy-to-clean automotive interior dashboard surface coating

Abstract

The present application relates to the field of automotive interior coating, and discloses a kind of anti-dazzling easy-to-clean automotive interior instrument panel surface coatings, including by high degree of branching end hydroxyl polyester resin, hydroxyl fluorine olefin-vinyl ether copolymer, cellulose acetate butyrate, dioctyltin lauryl mercaptide and dehydrated composite solvent component A and by hexamethylene diisocyanate trimer component B, after application, the volatilization of dehydrated composite solvent makes cellulose acetate butyrate precipitate and form rheological barrier, promote the migration enrichment of hydroxyl fluorine olefin-vinyl ether copolymer with low surface energy to coating surface, so as to obtain hydrophobic easy-to-clean characteristics;Dioctyltin lauryl mercaptide delays the crosslinking curing reaction of component A and component B, uses the curing time difference of surface layer and interior to cause shrinkage stress difference, makes coating surface deformation and produce continuous undulating form, realizes anti-dazzling effect.The present application does not need to add matting powder, solves the problem of easy to leave stain and fogging.

Description

Technical Field

[0001] This invention relates to the field of automotive interior coatings, specifically to an anti-glare and easy-to-clean coating for automotive interior dashboard surfaces. Background Technology

[0002] The surfaces of automotive interior dashboards typically require coatings to meet the needs of anti-glare during driving and easy cleaning for daily use. In existing coating technologies, to reduce coating gloss and achieve anti-glare effects, a large amount of inorganic matting powder is usually added to the system. However, these inorganic powders are prone to localized agglomeration during film formation, resulting in a microporous structure on the coating surface. External dirt and liquids can easily penetrate and remain in these pores, making them difficult to remove. Simultaneously, a large amount of powder physically adsorbs solvents, preventing some solvents from completely evaporating during the curing stage. These residual solvents are slowly released during subsequent vehicle use, easily condensing inside the windows and causing fogging.

[0003] To compensate for insufficient stain resistance in coatings, existing technologies often involve directly mixing hydrophobic additives into the paint. However, during conventional coating curing processes, the surface drying rate of the coating is relatively fast, and these low surface energy substances often lack sufficient time to migrate and accumulate on the coating surface. Furthermore, most conventional hydrophobic agents exist only in the form of physical blending, lacking effective chemical bonding with the cross-linking network within the coating film. This results in the hydrophobic components being easily consumed and peeled off under long-term daily wiping and physical contact, and the easy-to-clean properties of the coating cannot be maintained for a long time.

[0004] Furthermore, in two-component polyurethane interior coating systems, conventionally used solvents often lack a reasonable evaporation gradient design, resulting in an overly uniform overall drying rate for the coating. This makes it difficult to create the shrinkage stress differences required to produce specific morphologies within the coating film. More importantly, conventional solvents generally contain trace amounts of free water. These water molecules can react with isocyanate groups in the curing agent during coating, releasing carbon dioxide gas. As the viscosity of the coating increases during the curing stage, the generated gas cannot escape smoothly, ultimately forming tiny bubble defects inside or on the surface of the coating film, directly reducing the overall appearance quality of the dashboard coating. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an anti-glare and easy-to-clean coating for automotive interior dashboard surfaces. This solves the problems that existing automotive interior surface coatings struggle to balance anti-glare and easy-to-clean properties, and that the conventional introduction of inorganic matting powders can lead to surface stains, increased release of volatile organic compounds, and exacerbated condensation and fogging.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an anti-glare and easy-to-clean coating for automotive interior dashboard surfaces, comprising component A and component B;

[0007] Component A comprises the following raw materials in parts by weight:

[0008] A highly branched, hydroxyl-terminated polyester resin, in parts of 65.0 to 75.0 parts by solids weight;

[0009] Hydroxyfluoroolefin-vinyl ether copolymer, in parts from 25.0 to 35.0 parts by solids weight;

[0010] Cellulose acetate butyrate, 2.0 to 4.0 parts;

[0011] Dioctyltin lauryl thiolate, 0.1 to 0.5 parts;

[0012] Dehydrating composite solvent, 100.0 parts;

[0013] Component B contains hexamethylene diisocyanate trimer, wherein the ratio of the molar number of isocyanate groups in the hexamethylene diisocyanate trimer to the molar number of hydroxyl groups corresponding to the total hydroxyl equivalent of the residual hydroxyl groups on component A is 1.05:1 to 1.15:1.

[0014] After the surface coating is applied, the evaporation of the dehydrated composite solvent causes the cellulose acetate butyrate to form a rheological barrier, which promotes the enrichment of the hydroxyfluoroolefin-vinyl ether copolymer on the coating surface; the dioctyltin lauryl thiolate delays the internal crosslinking reaction between the A component and the B component, causing a shrinkage stress difference, which makes the coating form a continuously undulating micro-surface.

[0015] By adopting the above technical solution, due to the synergistic effect of components A and B in a specific ratio, this invention achieves anti-glare and easy-to-clean effects on the coating surface without adding any inorganic matting powder. The specific mechanism of action of this invention mainly consists of the following steps:

[0016] In the first step, after the coating is applied, as the dehydrating composite solvent begins to evaporate, the proportion of solid components within the coating increases. Cellulose acetate butyrate gradually precipitates and overlaps during this process, forming a rheological barrier within the coating. The appearance of this barrier increases the viscosity of the coating, limiting excessive leveling and thus maintaining the initial state of the coating.

[0017] Secondly, because the hydroxyfluoroolefin-vinyl ether copolymer contains fluorine in its structure, its surface energy is relatively low. Before the coating is fully cured, this copolymer spontaneously migrates and accumulates on the coating surface. The rheological barrier formed in the first step actually prolongs the surface drying time of the coating, which provides sufficient time for the fluorinated copolymer to migrate to the surface, resulting in a large accumulation of fluorinated components on the coating surface. Therefore, the coating achieves excellent hydrophobic and antifouling effects.

[0018] In the third step, the hydroxyl groups of component A in the coating mix with the isocyanate groups of component B, triggering a cross-linking and curing reaction. The dioctyltin lauryl thiolate in the formulation acts as a delayed catalytic agent, slowing down the initial cross-linking rate. During solvent evaporation, the solvent on the coating surface evaporates faster, causing the surface layer to cross-link and solidify first; while the solvent inside the coating evaporates more slowly, resulting in a later cross-linking reaction. This mismatch in curing time between the surface and interior layers creates a difference in shrinkage stress across the coating. Subsequent shrinkage from the interior stretches the already solidified surface layer, causing surface deformation and resulting in a continuously undulating surface.

[0019] Fourthly, this continuously undulating surface diffuses incoming light, directly reducing the coating's gloss and achieving anti-glare. This pure resin system eliminates the need for matting agents, preventing powder buildup and gaps that can trap dirt. Simultaneously, the solvent evaporates completely, reducing fogging issues during subsequent use.

[0020] Preferably, the butyryl group mass fraction in the cellulose acetate butyrate is 45% to 55%; and the water content of the dehydration composite solvent is 0.01% to 0.05% by mass.

[0021] By adopting the above technical solution, the butyryl group content of cellulose acetate butyrate is controlled within this specific range, ensuring its normal dissolution in the dehydration composite solvent and its smooth precipitation to form a barrier layer when the solvent just begins to evaporate. Furthermore, reducing the water content in the dehydration composite solvent to below 0.05% minimizes the reaction between water and the isocyanate groups in component B to produce carbon dioxide gas, thus preventing bubble defects in the coating.

[0022] Preferably, the raw materials for synthesizing the highly branched hydroxyl-terminated polyester resin comprise the following components in parts by weight: trimethylolpropane, 20.0 to 30.0 parts; neopentyl glycol, 25.0 to 35.0 parts; isophthalic acid, 20.0 to 25.0 parts; adipic acid, 15.0 to 25.0 parts; monobutyltin oxide, 0.04 to 0.12 parts; and xylene, 2.0 to 3.0 parts.

[0023] Preferably, the preparation process of the highly branched hydroxyl-terminated polyester resin includes: adding trimethylolpropane, neopentyl glycol, isophthalic acid, adipic acid, xylene, and monobutyltin oxide as an esterification catalyst; heating to 160°C at a rate of 15 to 20°C per hour under nitrogen protection, and then slowly heating to 210 to 220°C at a rate of 5 to 10°C per hour and holding at that temperature for esterification reaction; the water generated in the esterification reaction is carried out by the xylene azeotropic reaction, and after condensation, water-oil separation is performed to separate the water and reflux the xylene; when the acid value of the reaction mixture drops to 4.5 to 4.9 mg KOH / g, the residual xylene is removed by vacuum distillation under heat preservation to obtain a polyester resin solution; heating is stopped and the temperature is lowered to 120°C, and butanone is added to adjust the solid content of the polyester resin solution to 70% to 75% to obtain the highly branched hydroxyl-terminated polyester resin.

[0024] By employing the above-mentioned technical solution, using trimethylolpropane and neopentyl glycol in combination with isophthalic acid and adipic acid, a branched polyester resin with numerous terminal hydroxyl groups is ultimately produced. This branched structure increases the number of crosslinking points on the resin, contributing to a higher degree of crosslinking in the final coating. The isophthalic acid component provides the necessary hardness to the coating, while adipic acid primarily provides flexibility to the resin, allowing the coating to adapt to surface shrinkage during curing. Monobutyltin oxide acts as a catalyst, combined with xylene as a dehydrating agent, facilitating the smooth esterification and dehydration process and ensuring the quality of the synthesized resin.

[0025] Preferably, the raw materials for synthesizing the hydroxyfluoroolefin-vinyl ether copolymer comprise the following components in parts by weight: butyl acetate, 60.0 to 100.0 parts; hydroxybutyl vinyl ether, 5.8 to 17.4 parts; cyclohexyl vinyl ether, 18.9 to 31.6 parts; ethyl vinyl ether, 10.8 to 18.0 parts; azobisisobutyronitrile, 0.5 to 1.5 parts; and gaseous trifluorochloroethylene, 52.4 to 64.0 parts.

[0026] Preferably, the preparation process of the hydroxyfluoroolefin-vinyl ether copolymer includes: sequentially adding butyl acetate, hydroxybutyl vinyl ether, cyclohexyl vinyl ether, ethyl vinyl ether, and azobisisobutyronitrile as an initiator to a pressure vessel; after replacing the air in the pressure vessel by evacuation and nitrogen circulation three times, gaseous trifluorochloroethylene is injected under vacuum conditions; the temperature is raised to 60 to 70°C for isothermal polymerization until the pressure in the pressure vessel drops to a stable level and no longer changes; the temperature is cooled to room temperature and the residual pressure in the pressure vessel is released to atmospheric pressure, and unreacted monomers are removed under reduced pressure to obtain a copolymer solution; methyl ethyl ketone is added to adjust the solid content of the copolymer solution to 50% to 60% to obtain the hydroxyfluoroolefin-vinyl ether copolymer.

[0027] By employing the above technical solution, azobisisobutyronitrile (AIBN) initiates the polymerization of gaseous trifluorochloroethylene and several vinyl ether monomers. Trifluorochloroethylene attaches the fluorinated structure to the polymer, reducing the overall surface energy of the copolymer and making it prone to migrate to the coating surface. Cyclohexyl vinyl ether and ethyl vinyl ether are primarily used to improve the copolymer's solubility in the entire solvent system. Hydroxybutyl vinyl ether provides hydroxyl groups; after the copolymer migrates to the surface, these hydroxyl groups can react with the curing agent in component B to crosslink, firmly fixing the fluorinated components to the coating surface and maintaining a long-lasting, easy-to-clean effect.

[0028] Preferably, the dehydration composite solvent is obtained by dehydration treatment of a mixed solvent, the mixed solvent comprising the following components in parts by weight: methyl ethyl ketone, 72.0 to 84.0 parts; an aromatic solvent oil containing 9 to 10 carbon atoms, 27.0 to 31.9 parts, the aromatic solvent oil having a distillation range of 160°C to 180°C; and propylene glycol methyl ether acetate, 9.0 to 16.1 parts.

[0029] Preferably, the dehydrated composite solvent is obtained by pre-dehydration treatment through the following process: mixing the butanone, the aromatic solvent oil containing 9 to 10 carbon atoms, and the propylene glycol methyl ether acetate to obtain the mixed solvent; circulating the mixed solvent through a 4A molecular sieve column for dehydration, controlling the water content of the mixed solvent after dehydration to be reduced to 0.01% to 0.05%, to obtain the dehydrated composite solvent.

[0030] By employing the above technical solution, methyl ethyl ketone (MEK) evaporates quickly, aromatic solvent oil evaporates at a moderate rate and has strong dissolving power, and propylene glycol methyl ether acetate evaporates relatively slowly. These three solvents, when mixed in a specific ratio, form a evaporation gradient from fast to slow. The initial evaporation of MEK helps the cellulose acetate butyrate molding process take effect, while the remaining solvent in the middle and later stages ensures that the underlying system maintains a certain degree of fluidity and shrinkage capacity, contributing to the surface undulations. Furthermore, pre-dehydration of the mixed solvents using a molecular sieve column effectively removes free water molecules, reducing the possibility of foaming during application from the outset.

[0031] Preferably, the automotive interior dashboard surface coating is prepared by the following steps: adding the cellulose acetate butyrate and 35.0 to 45.0 parts by weight of the dehydrated composite solvent, stirring to dissolve, and obtaining a rheology fluid; adding the highly branched hydroxyl-terminated polyester resin, the hydroxyl fluoroolefin-vinyl ether copolymer, and the dioctyltin lauryl thiolate to the rheology fluid, and slowly adding the remaining dehydrated composite solvent; mixing and dispersing to obtain component A; adding the hexamethylene diisocyanate trimer as component B to component A and mixing to obtain a two-component mixture, thus obtaining the anti-glare and easy-to-clean automotive interior dashboard surface coating.

[0032] Preferably, in preparing the rheological fluid, the mixture is stirred at 800 to 1000 rpm for 30 to 40 minutes at room temperature until homogeneous dissolution is achieved; in preparing component A, the remaining amount of the dehydrating composite solvent is slowly added dropwise while continuously stirring at 1000 rpm; after the addition is complete, the stirring speed is increased to 1500 to 1800 rpm and the mixture is dispersed for 20 to 30 minutes to obtain a transparent and homogeneous component A.

[0033] By employing the above technical solution, cellulose acetate butyrate is first dissolved separately with a portion of the solvent to ensure thorough dispersion. Then, the resin and other materials are added, while the remaining solvent is slowly added gradually with stirring. This method of adding materials little by little prevents clumping caused by large local concentration changes. Finally, by increasing the rotation speed for strong dispersion, the polyester resin and copolymer are thoroughly mixed, ensuring that component A is stable and transparent after processing.

[0034] This invention provides an anti-glare and easy-to-clean coating for automotive interior dashboard surfaces. It offers the following advantages:

[0035] 1. This invention introduces cellulose acetate butyrate and dioctyltin lauryl thiolate into the coating system, combined with a dehydrating composite solvent with a volatility gradient. This causes a difference in crosslinking time and shrinkage stress between the surface and interior of the coating during curing, resulting in a spontaneously formed, continuously undulating physical morphology on the coating surface. This undulating morphology diffuses light, achieving an anti-glare effect. Since the entire system eliminates the addition of inorganic matting powder, it avoids the micropores caused by powder agglomeration, preventing the penetration and residue of external stains. It also reduces the later-stage fogging problem caused by solvent adsorption by the powder.

[0036] 2. This invention, by adding a hydroxyl fluoroolefin-vinyl ether copolymer and utilizing the physical network formed by the overlap of cellulose acetate butyrate in the early stages of film formation to delay coating settling, provides sufficient time for the low surface energy fluorinated copolymer to migrate and accumulate on the coating surface. The fluorinated components that migrate to the surface can chemically bond with the isocyanate groups in the curing agent using their own active hydroxyl groups, firmly crosslinking the hydrophobic components in the surface structure of the coating film, so that the coating can maintain stable hydrophobic and easy-to-clean properties even under long-term use and daily wiping.

[0037] 3. This invention uses solvents with different evaporation rates to form a dehydration composite solvent, and uses molecular sieves for pre-dehydration treatment. On the one hand, it constructs a continuous solvent evaporation gradient, ensuring that the underlying coating maintains its fluidity for a longer period of time to continuously generate shrinkage stress. On the other hand, it completely eliminates free water in the mixed solvent, cuts off the chemical pathway for water molecules to react with the curing agent to generate gas, prevents the formation of air bubbles in the coating during the viscosity increase stage, and ensures that the final interior coating has a good appearance quality. Attached Figure Description

[0038] Figure 1 This is the Fourier transform infrared spectrum of the present invention;

[0039] Figure 2 This is a rheological curve of the energy storage modulus of the present invention changing over time.

[0040] Figure 3 This is a scanned image of the microscopic profile of the coating surface of the present invention;

[0041] Figure 4 This is a gas chromatogram of the thermal desorption of the coating sample of the test plate of the present invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, preparation examples, embodiments, comparative examples, and test examples. 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.

[0043] It should be noted that "parts by weight" refers to the relative weight ratio of each component in the formula. In specific preparation examples, "parts by weight" can correspond to any weight unit (such as g, kg, ton, etc.), as long as the components maintain the corresponding ratio. To facilitate a clear description of the specific preparation process, "g" is selected as the weight unit for illustrative purposes in the following examples, that is, 1 part by weight corresponds to 1g, but the scope of protection of this invention is not limited to this specific weight level.

[0044] Preparation Examples 1-6:

[0045] Preparation Example 1:

[0046] This preparation example provides a highly branched hydroxyl-terminated polyester resin, comprising the following steps:

[0047] In a four-necked flask equipped with a mechanical stirrer, water separator, condenser, thermometer, and nitrogen inlet tube, add 20.0 g of trimethylolpropane, 25.0 g of neopentyl glycol, 20.0 g of isophthalic acid, 15.0 g of adipic acid, and 2.0 g of xylene, and add 0.04 g of monobutyltin oxide as an esterification catalyst.

[0048] After adding all the raw materials, nitrogen gas was introduced into the four-necked flask for protection, and mechanical stirring was started. The temperature was increased to 160°C at a rate of 15°C / h, and then slowly increased to 210°C at a rate of 5°C / h and held at this temperature for esterification reaction.

[0049] The water produced during the esterification reaction is carried away by an azeotropic reaction with xylene, condensed, and then enters a water separator for water-oil separation. The water separator removes the lower layer of water and refluxes the upper layer of xylene back into a four-necked flask. During the esterification reaction at elevated temperatures, samples are taken periodically to test the acid value of the reaction mixture.

[0050] When the acid value of the reaction mixture drops to 4.5 mg KOH / g, a vacuum distillation apparatus is connected, and residual xylene is removed by vacuum distillation under heat preservation conditions. After confirming that xylene has been removed to the point where there is no obvious distillate, heating is stopped and the temperature is lowered to 120°C. Butanone is added to adjust the solid content of the polyester resin solution to 70%, and the solution is discharged and sealed to obtain a highly branched, hydroxyl-terminated polyester resin.

[0051] Preparation Example 2:

[0052] This preparation example provides a highly branched hydroxyl-terminated polyester resin, comprising the following steps:

[0053] In a four-necked flask equipped with a mechanical stirrer, water separator, condenser, thermometer, and nitrogen inlet tube, add 25.0 g of trimethylolpropane, 30.0 g of neopentyl glycol, 22.5 g of isophthalic acid, 20.0 g of adipic acid, and 2.5 g of xylene, and add 0.07 g of monobutyltin oxide as an esterification catalyst.

[0054] After adding all the raw materials, nitrogen gas was introduced into the four-necked flask for protection. Mechanical stirring was started, and the temperature was increased to 160°C at a rate of 17.5°C / h. Then, the temperature was slowly increased to 215°C at a rate of 7.5°C / h and held at this temperature for esterification reaction.

[0055] The water produced during the esterification reaction is carried away by an azeotropic reaction with xylene, condensed, and then enters a water separator for water-oil separation. The water separator removes the lower layer of water and refluxes the upper layer of xylene back into a four-necked flask. During the esterification reaction at elevated temperatures, samples are taken periodically to test the acid value of the reaction mixture.

[0056] When the acid value of the reaction mixture drops to 4.8 mg KOH / g, a vacuum distillation apparatus is connected, and residual xylene is removed by vacuum distillation under heat preservation conditions. After confirming that xylene has been removed to the point where there is no obvious distillate, heating is stopped and the temperature is lowered to 120°C. Butanone is added to adjust the solid content of the polyester resin solution to 72.5%, and the solution is discharged and sealed to obtain a highly branched, hydroxyl-terminated polyester resin.

[0057] Preparation Example 3:

[0058] This preparation example provides a highly branched hydroxyl-terminated polyester resin, comprising the following steps:

[0059] In a four-necked flask equipped with a mechanical stirrer, water separator, condenser, thermometer, and nitrogen inlet tube, add 30.0 g of trimethylolpropane, 35.0 g of neopentyl glycol, 25.0 g of isophthalic acid, 25.0 g of adipic acid, and 3.0 g of xylene, and add 0.12 g of monobutyltin oxide as an esterification catalyst.

[0060] After adding all the raw materials, nitrogen gas was introduced into the four-necked flask for protection, mechanical stirring was started, and the temperature was increased to 160°C at a rate of 20°C / h. Then, the temperature was slowly increased to 220°C at a rate of 10°C / h and held at this temperature for esterification reaction.

[0061] The water produced during the esterification reaction is carried away by an azeotropic reaction with xylene, condensed, and then enters a water separator for water-oil separation. The water separator removes the lower layer of water and refluxes the upper layer of xylene back into a four-necked flask. During the esterification reaction at elevated temperatures, samples are taken periodically to test the acid value of the reaction mixture.

[0062] When the acid value of the reaction mixture drops to 4.9 mg KOH / g, a vacuum distillation apparatus is connected, and residual xylene is removed by vacuum distillation under heat preservation conditions. After confirming that xylene has been removed to the point where there is no obvious distillate, heating is stopped and the temperature is lowered to 120°C. Butanone is added to adjust the solid content of the polyester resin solution to 75%, and the solution is discharged and sealed to obtain a highly branched, hydroxyl-terminated polyester resin.

[0063] Preparation Example 4:

[0064] This preparation example provides a hydroxyfluoroolefin-vinyl ether copolymer, comprising the following steps:

[0065] In a pressure vessel equipped with mechanical stirring, 100.0g of butyl acetate, 17.4g of hydroxybutyl vinyl ether, 31.6g of cyclohexyl vinyl ether, 10.8g of ethyl vinyl ether, and 0.5g of azobisisobutyronitrile were added sequentially as initiators.

[0066] The pressure-resistant autoclave was sealed, and the air inside was replaced three times by evacuation and nitrogen circulation. Then, under vacuum conditions, 52.4g of gaseous trifluorochloroethylene was injected into the pressure-resistant autoclave through a gas weighing cylinder.

[0067] Mechanical stirring was started, and the temperature was raised to 60°C for isothermal polymerization. During the heating and isothermal polymerization process, the pressure inside the pressure vessel initially increased with the rising temperature, and then gradually decreased as the gaseous monomers were consumed. When the pressure inside the pressure vessel stabilized and no longer changed, the isothermal polymerization reaction was considered to have reached its endpoint. This isothermal polymerization process took approximately 12 hours.

[0068] The mixture was cooled to room temperature, and the residual pressure in the pressure-resistant autoclave was released to atmospheric pressure. Then, the vacuum system was activated to reduce pressure and remove unreacted monomers. Butanone was added to adjust the solid content of the copolymer solution to 50%, and the solution was discharged and sealed to obtain the hydroxyfluoroolefin-vinyl ether copolymer.

[0069] Preparation Example 5:

[0070] This preparation example provides a hydroxyfluoroolefin-vinyl ether copolymer, comprising the following steps:

[0071] In a pressure vessel equipped with mechanical stirring, 80.0 g of butyl acetate, 11.6 g of hydroxybutyl vinyl ether, 25.2 g of cyclohexyl vinyl ether, 14.4 g of ethyl vinyl ether, and 1.0 g of azobisisobutyronitrile were added sequentially as initiators.

[0072] The pressure-resistant autoclave was sealed, and the air inside was replaced three times by evacuation and nitrogen circulation. Then, under vacuum conditions, 58.2g of gaseous trifluorochloroethylene was injected into the pressure-resistant autoclave through a gas weighing cylinder.

[0073] Mechanical stirring was started, and the temperature was raised to 65°C for isothermal polymerization. During the heating and isothermal polymerization process, the pressure inside the pressure vessel initially increased with the rising temperature, and then gradually decreased as the gaseous monomers were consumed. When the pressure inside the pressure vessel stabilized and no longer changed, the isothermal polymerization reaction was considered to have reached its endpoint. This isothermal polymerization process took approximately 10 hours.

[0074] The mixture was cooled to room temperature, and the residual pressure in the pressure-resistant autoclave was released to atmospheric pressure. Then, the vacuum system was activated to reduce pressure and remove unreacted monomers. Butanone was added to adjust the solid content of the copolymer solution to 55%, and the solution was discharged and sealed to obtain the hydroxyfluoroolefin-vinyl ether copolymer.

[0075] Preparation Example 6:

[0076] This preparation example provides a hydroxyfluoroolefin-vinyl ether copolymer, comprising the following steps:

[0077] In a pressure vessel equipped with mechanical stirring, 60.0 g of butyl acetate, 5.8 g of hydroxybutyl vinyl ether, 18.9 g of cyclohexyl vinyl ether, 18.0 g of ethyl vinyl ether, and 1.5 g of azobisisobutyronitrile were added sequentially as initiators.

[0078] The pressure-resistant autoclave was sealed, and the air inside was replaced three times by evacuation and nitrogen circulation. Then, under vacuum conditions, 64.0g of gaseous trifluorochloroethylene was injected into the pressure-resistant autoclave through a gas weighing cylinder.

[0079] Mechanical stirring was started, and the temperature was raised to 70°C for isothermal polymerization. During the heating and isothermal polymerization process, the pressure inside the pressure vessel initially increased with the rising temperature, and then gradually decreased as the gaseous monomers were consumed. When the pressure inside the pressure vessel stabilized and no longer changed, the isothermal polymerization reaction was considered to have reached its endpoint. This isothermal polymerization process took approximately 8 hours.

[0080] The mixture was cooled to room temperature and the residual pressure in the pressure-resistant autoclave was released to atmospheric pressure. Then, the vacuum system was activated to reduce pressure and remove unreacted monomers. Butanone was added to adjust the solid content of the copolymer solution to 60%, and the solution was discharged and sealed to obtain the hydroxyfluoroolefin-vinyl ether copolymer.

[0081] Examples 1-3:

[0082] Example 1:

[0083] This embodiment provides an anti-glare and easy-to-clean coating for automotive interior dashboard surfaces, comprising the following steps:

[0084] 72.0 g of butanone, 31.9 g of aromatic solvent oil containing 9 to 10 carbon atoms (distillation range 160°C to 180°C), and 16.1 g of propylene glycol methyl ether acetate were mixed to obtain a mixed solvent. The mixed solvent was dehydrated by circulating it through a 4A molecular sieve column, and the moisture content was measured using a Karl Fischer moisture analyzer. When the moisture content of the mixed solvent dropped to 0.05% by mass, it was sealed and stored for later use, yielding a dehydrated composite solvent.

[0085] 2.0 g of cellulose acetate butyrate (butyryl group mass fraction of 45%) was added to a stainless steel stirred tank, followed by 35.0 g of dehydrated composite solvent. The mixture was stirred at 800 rpm for 30 minutes at room temperature until homogeneous dissolution was achieved, yielding a rheological fluid. The highly branched hydroxyl-terminated polyester resin (65.0 g on a solids basis) prepared in Preparation Example 1 and the hydroxyl fluoroolefin-vinyl ether copolymer (25.0 g on a solids basis) prepared in Preparation Example 4 were then added to the rheological fluid.

[0086] Subsequently, 0.1 g of dioctyltin lauryl thiolate was added as a delayed catalyst, and 65.0 g of dehydrating composite solvent was slowly added dropwise under continuous stirring at 1000 rpm. After the addition was complete, the stirring speed was increased to 1500 rpm and the mixture was dispersed for 20 minutes to obtain a transparent and homogeneous component A.

[0087] Calculate the total hydroxyl equivalent of the highly branched hydroxyl-terminated polyester resin, hydroxyl fluoroolefin-vinyl ether copolymer, and residual hydroxyl groups on cellulose acetate butyrate in component A. Calculate and weigh the corresponding mass of hexamethylene diisocyanate trimer as component B, based on a molar ratio of isocyanate groups to hydroxyl groups of 1.05:1. Add the calculated mass of component B to component A and mix in a sealed container to obtain a two-component mixture, thus preparing an anti-glare and easy-to-clean automotive interior dashboard surface coating.

[0088] Example 2:

[0089] This embodiment provides an anti-glare and easy-to-clean coating for automotive interior dashboard surfaces, comprising the following steps:

[0090] 78.0 g of butanone, 30.0 g of aromatic solvent oil containing 9 to 10 carbon atoms (distillation range 160℃ to 180℃), and 12.0 g of propylene glycol methyl ether acetate were mixed to obtain a mixed solvent. The mixed solvent was circulated through a 4A molecular sieve column for dehydration, and the moisture content was measured using a Karl Fischer moisture analyzer. When the moisture content of the mixed solvent dropped to 0.03% by mass, it was sealed for later use, yielding a dehydrated composite solvent.

[0091] 3.0 g of cellulose acetate butyrate (50% butyryl group by mass) was added to a stainless steel stirred tank, followed by 40.0 g of dehydrated composite solvent. The mixture was stirred at 900 rpm for 35 minutes at room temperature until homogeneous dissolution was achieved, yielding a rheological fluid. 70.0 g of highly branched hydroxyl-terminated polyester resin (converted to solids mass) prepared in Preparation Example 2 and 30.0 g of hydroxyl fluoroolefin-vinyl ether copolymer (converted to solids mass) prepared in Preparation Example 5 were added to the rheological fluid.

[0092] Subsequently, 0.3 g of dioctyltin lauryl thiolate was added as a delayed catalyst, and 60.0 g of dehydrating composite solvent was slowly added dropwise under continuous stirring at 1000 rpm. After the addition was complete, the stirring speed was increased to 1600 rpm and the mixture was dispersed for 25 minutes to obtain a transparent and homogeneous component A.

[0093] Calculate the total hydroxyl equivalent of the highly branched hydroxyl-terminated polyester resin, hydroxyl fluoroolefin-vinyl ether copolymer, and residual hydroxyl groups on cellulose acetate butyrate in component A. Calculate and weigh the corresponding mass of hexamethylene diisocyanate trimer as component B according to a molar ratio of isocyanate groups to hydroxyl groups of 1.10:1. Add the calculated mass of component B to component A and mix in a sealed container to obtain a two-component mixture, thus preparing an anti-glare and easy-to-clean automotive interior dashboard surface coating.

[0094] Example 3:

[0095] This embodiment provides an anti-glare and easy-to-clean coating for automotive interior dashboard surfaces, comprising the following steps:

[0096] 84.0 g of butanone, 27.0 g of aromatic solvent oil containing 9 to 10 carbon atoms (distillation range 160°C to 180°C), and 9.0 g of propylene glycol methyl ether acetate were mixed to obtain a mixed solvent. The mixed solvent was circulated through a 4A molecular sieve column for dehydration, and the moisture content was measured using a Karl Fischer moisture analyzer. When the moisture content of the mixed solvent dropped to 0.01% by mass, it was sealed for later use, yielding a dehydrated composite solvent.

[0097] 4.0 g of cellulose acetate butyrate (butyryl group mass fraction of 55%) was added to a stainless steel stirred tank, followed by 45.0 g of dehydrated composite solvent. The mixture was stirred at 1000 rpm for 40 minutes at room temperature until homogeneous dissolution was achieved, yielding a rheology fluid. The highly branched hydroxyl-terminated polyester resin (equivalent to 75.0 g on a solids basis) prepared in Preparation Example 3 and the hydroxyl fluoroolefin-vinyl ether copolymer (equivalent to 35.0 g on a solids basis) prepared in Preparation Example 6 were then added to the rheology fluid.

[0098] Subsequently, 0.5 g of dioctyltin lauryl thiolate was added as a delayed catalyst, and 55.0 g of dehydrating composite solvent was slowly added dropwise under continuous stirring at 1000 rpm. After the addition was complete, the stirring speed was increased to 1800 rpm and the mixture was dispersed for 30 minutes to obtain a transparent and homogeneous component A.

[0099] Calculate the total hydroxyl equivalent of the highly branched hydroxyl-terminated polyester resin, hydroxyl fluoroolefin-vinyl ether copolymer, and residual hydroxyl groups on cellulose acetate butyrate in component A. Calculate and weigh the corresponding mass of hexamethylene diisocyanate trimer as component B, based on a molar ratio of isocyanate groups to hydroxyl groups of 1.15:1. Add the calculated mass of component B to component A and mix in a sealed container to obtain a two-component mixture, thus preparing an anti-glare and easy-to-clean automotive interior dashboard surface coating.

[0100] Comparative Examples 1-6:

[0101] Comparative Example 1:

[0102] Compared with Example 2, the difference is that cellulose acetate butyrate is not added to the stainless steel stirred tank, and 40.0g of dehydrated composite solvent is directly mixed with the highly branched hydroxyl-terminated polyester resin prepared in Preparation Example 2 and the hydroxyl fluoroolefin-vinyl ether copolymer prepared in Preparation Example 5; and the residual hydroxyl groups on cellulose acetate butyrate are no longer included when calculating the total hydroxyl equivalent, while the rest are the same.

[0103] Comparative Example 2:

[0104] Compared with Example 2, the difference is that when adding resin to the rheology fluid, the hydroxyl fluoroolefin-vinyl ether copolymer prepared in Preparation Example 5 is no longer added, and the amount of the highly branched hydroxyl-terminated polyester resin prepared in Preparation Example 2 is replaced with 100.0 g converted to solid mass; and when calculating the total hydroxyl equivalent, only the hydroxyl equivalent of the highly branched hydroxyl-terminated polyester resin and the residual hydroxyl groups on cellulose acetate butyrate are considered, and the hydroxyl equivalent of the hydroxyl fluoroolefin-vinyl ether copolymer is no longer included, while the rest are the same.

[0105] Comparative Example 3:

[0106] Compared with Example 2, the difference is that the 0.3g dioctyltin lauryl thiolate added is replaced by 0.3g dibutyltin dilaurate as a catalyst, and all other aspects are the same.

[0107] Comparative Example 4:

[0108] Compared with Example 2, the difference is that the raw material for preparing the mixed solvent is replaced with 120.0g of butanone, that is, the aromatic solvent oil containing 9 to 10 carbon atoms and propylene glycol methyl ether acetate are no longer added. The pure butanone solvent is obtained and dehydrated, and then used to replace the dehydration composite solvent for the subsequent extraction and addition steps of the same mass. All other steps are the same.

[0109] Comparative Example 5:

[0110] Compared with Example 2, the difference is that when adding resin to the rheology fluid, the hydroxyl fluoroolefin-vinyl ether copolymer prepared in Preparation Example 5 is no longer added, but 10.0g of fumed silica is added as a matting agent. At the same time, the amount of the highly branched hydroxyl-terminated polyester resin prepared in Preparation Example 2 is replaced with 100.0g converted to solid mass. Furthermore, the hydroxyl equivalent of the hydroxyl fluoroolefin-vinyl ether copolymer is no longer included when calculating the total hydroxyl equivalent. All other aspects are the same.

[0111] Comparative Example 6:

[0112] Compared with Example 2, the difference is that the obtained mixed solvent is directly used for subsequent component preparation steps, that is, the step of circulating the mixed solvent through a 4A molecular sieve column for dehydration and detecting the water content to be reduced to 0.03% is omitted, and all other steps are the same.

[0113] Test Example 1-3:

[0114] Test Example 1:

[0115] The two-component mixtures obtained in Examples 1 to 3 and Comparative Examples 1 to 6 were applied to the surface of a polycarbonate and acrylonitrile butadiene styrene copolymer alloy test plate with a dimensional change rate ≤0.3% (measured at 120°C for 20 minutes) using an air atomizing spray gun in an environment with a temperature of 20°C to 25°C and a relative humidity of 40% to 60%. The coating thickness of the two-component mixture on the test plate surface was controlled to be 30 μm to 50 μm.

[0116] Test panels coated with a two-component mixture were placed in an exhaust-tunnel oven for curing. The ambient temperature was set to 60°C and maintained for 15 to 20 minutes, with the oven fan speed controlled at 0.5 to 1.5 m / s. The temperature was then increased to 120°C within 3 minutes and maintained for 20 to 25 minutes, with the fan speed controlled at 0.5 to 1.5 m / s. After the curing process, the temperature was lowered to 80°C to 110°C and the fan speed was adjusted to 3.0 to 5.0 m / s for a volatilization treatment of 5 to 20 minutes. The panels were then cooled to room temperature in the oven to obtain the cured test panels.

[0117] A rotational rheometer was used to test the two-component mixture. The freshly prepared two-component mixture was placed on the rheometer testing platform, which was set to a constant temperature of 60℃, a testing frequency of 1Hz, and a strain of 0.5%. Under these constant temperature conditions, the data on the change of storage modulus over time were recorded, and the time required for the storage modulus to suddenly increase and reach the 100Pa threshold was recorded. A rheological curve of the storage modulus versus time was then plotted.

[0118] Test panels with a two-component mixture coated on their surfaces and having completed the corresponding treatment stages were sampled. Test panels immediately after completing the 60℃ stage treatment and those immediately after completing the 120℃ stage treatment were also sampled. Fourier transform infrared spectrometers with attenuated total reflectance attachments were used to scan the two-component mixture on the test panel surfaces in their cured or semi-cured states, recording wavenumber and absorbance data to obtain Fourier transform infrared spectra. The tests were conducted at three states: immediately after preparation of the two-component mixture, at the end of the 60℃ stage, and at the end of the 120℃ stage. The integral extraction was performed at 2270 cm⁻¹. -1 The area of ​​the characteristic absorption peak of the isocyanate group in the vicinity. Using the area of ​​the characteristic absorption peak of the isocyanate group when the two-component mixture is prepared as a benchmark, the isocyanate group conversion rate after each stage of treatment is calculated.

[0119] Elemental quantitative analysis was performed on the surface area of ​​the cured test panel after the entire process was cooled to room temperature using X-ray photoelectron spectroscopy. Al Kα rays were used as the excitation source, and the analysis depth was set within the range of 5 to 10 nanometers to obtain the atomic percentage concentration data of fluorine. Simultaneously, based on the theoretical mass ratio and chemical structure of each component, the theoretical average atomic percentage concentration of fluorine in the entire coating structure was calculated.

[0120] Table 1. Rheological and Conversion Rate Test Data of Coating Curing Process

[0121] Example 1 243.6 12.8 85.3 19.42 5.37 Example 2 215.2 14.2 88.6 21.85 6.22 Example 3 187.9 16.5 91.1 23.08 7.15 Comparative Example 1 >1800 15.1 87.2 22.41 6.22 Comparative Example 2 221.4 13.9 89.0 0.00 0.00 Comparative Example 3 208.5 44.7 93.4 20.73 6.22 Comparative Example 4 82.1 18.2 79.5 18.15 6.22 Comparative Example 5 310.8 14.5 88.1 0.00 0.00 Comparative Example 6 218.0 17.6 86.4 21.36 6.22

[0122] Test conclusion:

[0123] Combined with Table 1 and Figure 2 It can be seen that the time when the storage modulus measured by the rheometer in Examples 1 to 3 reaches the 100Pa threshold is concentrated in the range of 187.9 seconds to 243.6 seconds. During this period, after the preferential volatilization of methyl ethyl ketone, the mass percentage content of the solid component in the two-component mixture increases, triggering the effect of cellulose acetate butyrate, and the two-component mixture forms a space confinement effect.

[0124] Comparative Example 1 Figure 2No abrupt change in storage modulus at the 100 Pa threshold was observed, and no jump in apparent modulus was observed during the test duration, indicating that no effective rheological inhibition was formed. In Comparative Example 4, the evaporation rate of methyl ethyl ketone (MEK) at isothermal conditions was not constrained by aromatic solvent oils containing 9 to 10 carbon atoms or propylene glycol methyl ether acetate, and the time to reach the 100 Pa threshold was shortened to 82.1 seconds, resulting in premature surface drying and setting of the coating.

[0125] Combined with Table 1 and Figure 1 It can be seen that the absorbance of the absorption peak at the end of the 60°C stage in Example 2 decreased less than that when the two-component mixture was prepared. At this time, the isocyanate group conversion rate remained at 14.2%, corresponding to the isocyanate group conversion rate of the coating on the test plate of all examples remaining at the level of 12.8% to 16.5% at the end of the 60°C stage.

[0126] After entering the 120℃ stage, the absorbance at the end of the 120℃ stage decreased more significantly, at which point the isocyanate group conversion rate increased to 85.3% to 91.1%. This segmented conversion characteristic reflects the catalytic inhibition effect of dioctyltin lauryl thiolate in the low-temperature region, preserving the crosslinking activity within the coating. Comparative Example 3 achieved an isocyanate group conversion rate of 44.7% at the end of the 60℃ stage, prematurely consuming the reactive groups that would otherwise undergo volume shrinkage mismatch at high temperatures, thus reducing the curing difference between the surface and the interior.

[0127] Surface elemental analysis results showed that the measured percentage concentration of fluorine atoms in the cured coating surface area on the test boards of Examples 1 to 3 reached 19.42 at% to 23.08 at%, higher than the average theoretical concentration of 5.37 at% to 7.15 at% calculated based on the composition in the coating's internal structure. After the surface coating was applied, the evaporation of the dehydrated composite solvent caused cellulose acetate butyrate to form a rheological barrier, promoting the enrichment of hydroxyfluoroolefin-vinyl ether copolymers on the coating surface. The high concentration of fluorine at the interface reflects the directional migration of hydroxyfluoroolefin-vinyl ether copolymer macromolecules driven by surface energy principles.

[0128] Based on the energy storage modulus data, the rheological barrier constructed by cellulose acetate butyrate provides sufficient time for the enrichment process, confining it to the surface area and preventing abnormalities in the coating leveling state.

[0129] Test Example 2:

[0130] A three-angle miniature gloss meter was used to test the surface gloss of test panels after the surface curing process was completed. In a constant temperature and humidity environment, the measuring aperture of the testing instrument was placed against a flat area of ​​the test panel surface, and the reflected gloss values ​​were read at incident angles of 60° and 85°. Five test points were selected at different locations on each test panel for repeated readings, and the average value was calculated as the recorded data.

[0131] A probe-type surface profilometer was used to perform mechanical contact scanning on the test plate surface. The scanning length of the diamond probe was set to 4.0 mm, and the scanning speed was set to 0.5 mm / s. The scanning trajectory data was extracted by the instrument's built-in system, and the arithmetic mean roughness Ra and the average spacing of the micro-profiles in the test area were calculated and output.

[0132] The surface condition of the test plate was evaluated using a contact angle meter. A 2.0 μL volume of deionized water was dropped onto the test plate surface using a micro-syringe. After the droplet had stabilized on the surface for 30 seconds, the camera system on the device captured an image of the droplet's outline. The static contact angle between the deionized water and the test plate surface was calculated using a baseline fitting method.

[0133] The color parameters L*, a*, and b* of the test panel in its initial state were measured using a spectrophotometer. A 3cm line segment was drawn on the surface of the test panel using a black oil-based marker, and the panel was left at room temperature for 24 hours. A 500g weight wrapped in a clean, dry cotton cloth was used to horizontally rub the drawn area 10 times. After rubbing, the color parameters of the rubbed area were read again using the spectrophotometer, and the color difference before and after rubbing was calculated. .

[0135]

[0136] Test conclusion:

[0137] According to the data in Table 2, the 60° gloss of Examples 1 to 3 ranged from 1.21 GU to 1.83 GU, and the 85° gloss ranged from 2.94 GU to 4.12 GU, exhibiting a low gloss state. Combined with the arithmetic mean roughness measured by a probe-type surface profilometer, which ranged from 1.76 μm to 2.42 μm, the average spacing of the micro-profiles remained between 21.4 μm and 34.2 μm. Figure 3 It can be seen that the curve corresponding to Example 2 exhibits a continuously undulating shape. Combined with the system mechanism analysis, the dioctyltin lauryl thiolate delays the internal crosslinking reaction between component A and component B, triggering a shrinkage stress difference, which causes the coating to form a continuously undulating micro-surface, resulting in the corresponding arithmetic mean roughness and micro-profile average spacing data recording characteristics.

[0138] Combined with Table 2 Figure 3 Data, Comparative Example 3 Figure 3The curve shape in the sample tends to flatten out. The difference in curing shrinkage in the thickness direction decreases, resulting in a lower stress difference. The measured arithmetic mean roughness decreased to 0.15 μm, and the gloss increased to 64.25 GU. In Comparative Example 1, without a rheology control agent, the measured average spacing of the micro-profiles increased to 125.6 μm, and the gloss increased to 9.76 GU. In Comparative Example 4, the lack of flowability maintained by aromatic solvent oil containing 9 to 10 carbon atoms led to changes in stress difference and surface morphology. The average spacing of the micro-profiles decreased to 12.8 μm, and the 60° gloss increased to 18.63 GU.

[0139] According to the data in Table 2, the static pure water contact angles of Examples 1 to 3 were between 108.6° and 112.8°, and the marker pen erasure color difference was between 0.41 and 0.82. The static pure water contact angle measured in Comparative Example 2 decreased to 76.4°, and the marker pen erasure color difference increased to 18.67. Comparative Example 5... Figure 3 The corresponding curves exhibit a disordered, undulating shape. Due to the influence of fumed silica on the coating surface condition, the measured marker-erasing color difference value was 24.31. In Examples 1 to 3, the coatings formed from highly branched, hydroxyl-terminated polyester resins, hydroxyl fluoroolefin-vinyl ether copolymers, and cellulose acetate butyrate reduced the marker-erasing color difference value.

[0140] Test Example 3:

[0141] A surface defect magnifying glass equipped with a light source and a graduated grid was used to evaluate surface microbubbles and pinholes on test panels that had completed the curing process. Under a standard testing environment with an illumination of 800 to 1000 lux, the test panel was placed flat on the testing stage. Using the magnifying glass, a 10cm × 10cm detection grid was selected in the center area of ​​the test panel, and the total number of bubbles and pinholes visible to the naked eye and under the magnifying glass on the coating surface was counted and recorded. Readings were taken from three parallel test panels prepared for each two-component mixture, and the arithmetic mean was recorded as the data for the number of microbubbles.

[0142] The release of volatile organic compounds (VOCs) was determined according to VDA 278 (05 / 2016 edition), "Thermal Desorption Analysis of Organic Compound Release Characteristics of Non-metallic Materials for Automobiles". Coating samples were scraped from the surface of the test plate after the curing process using a stainless steel scraper, and 15.0 mg to 30.0 mg of the coating sample was accurately weighed and placed into a thermal desorption tube. The thermal desorption tube was placed in a thermal desorber, and the desorption temperature was set to 90℃ for 30 minutes. The released gas was introduced into a gas chromatograph-mass spectrometer (GC-MS) via a carrier gas for separation and quantitative analysis. Retention time and response abundance were recorded, and a thermal desorption gas chromatogram of the test plate coating sample was plotted. The total VOC release amount in the coating sample was calculated using toluene equivalents.

[0143] Condensation atomization tests were conducted according to DIN 75201:2024-06, "Determination of atomization properties of interior materials for automotive passenger compartments". The test plate, after curing, was cut into 80mm diameter discs. The discs were placed flat at the bottom of a thermostatic atomizing cup. A clean, pre-weighed aluminum foil was placed over the opening of the cup, and a circulating cooling pan set to 21°C was placed on top. The heating bath at the bottom of the atomizing cup was set to 100°C and heated continuously for 16 hours for desiccation. After the heating process, the aluminum foil was removed and the mixture was brought to room temperature in a desiccator. The aluminum foil was weighed again on an analytical balance, and the increase in mass of the aluminum foil before and after heating was calculated as the condensation atomization mass value.

[0144] Table 3. Test Data on Coating Appearance Quality and Environmental Emission Performance

[0145] Example 1 0 64.3 0.45 Example 2 0 52.8 0.38 Example 3 1 58.1 0.41 Comparative Example 1 2 72.4 0.51 Comparative Example 2 0 55.6 0.44 Comparative Example 3 1 61.2 0.48 Comparative Example 4 2 145.6 0.76 Comparative Example 5 3 88.5 0.62 Comparative Example 6 48 94.2 0.69

[0146] Test conclusion:

[0147] According to the data in Table 3, the number of microbubble defects in Examples 1 to 3 ranged from 0 to 1, the total volatile organic compound (VOC) release ranged from 52.8 μg / g to 64.3 μg / g, and the condensation atomization mass ranged from 0.38 mg to 0.45 mg. In Comparative Example 6, the number of microbubble defects increased to 48, and the total VOC release was measured at 94.2 μg / g. The coating formulation system is sensitive to trace amounts of moisture. Free moisture reacts chemically with the isocyanate groups in the hexamethylene diisocyanate trimer to produce carbon dioxide gas. This gas escapes during the viscosity increase phase of the coating crosslinking process, becoming trapped inside the coating and causing microbubble defects. Examples 1 to 3 eliminated the influence of trace moisture through a solvent dehydration process, reducing the probability of random microbubble formation.

[0148] Combined with Table 3 Figure 4 The data, in comparison 4 Figure 4 The chromatographic peak with high abundance was observed around 4.2 minutes. The total volatile organic compound release value of Comparative Example 4 was 145.6 μg / g. Comparative Example 4 exhibited rapid evaporation in the initial stage of the heating program, leading to premature surface film formation on the coating surface. This premature film formation hindered the diffusion and mass transfer process of the unvolatile methyl ethyl ketone (MEK) from the deeper layers to the air interface. A large amount of free solvent was trapped inside the coating and forcibly released under the 90°C desorption conditions applied by the thermal desorption apparatus, forming... Figure 4 High-response chromatographic peaks in the sample.

[0149] Examples 1 to 3 constructed a volatility gradient using a combination of butanone, an aromatic solvent oil containing 9 to 10 carbon atoms, and propylene glycol methyl ether acetate. After establishing a crosslinked system in the coating, a devolatilization treatment was used to improve the mass transfer coefficient of high-boiling-point components from the coating interior to the gas phase. Figure 4The corresponding chromatographic curve showed a flat abundance, reducing the residual amount of free small molecules in the final coating. Comparative Example 5 measured a condensation atomization mass of 0.62 mg. The physical adsorption of fumed silica increased the physical resistance to solvent removal, causing a small amount of volatile components to be slowly released and condensed on the aluminum foil surface during prolonged heating in the fogging cup. Examples 1 to 3 did not add fumed silica, avoiding the powder adsorption effect, and the condensation atomization mass remained at a low level.

Claims

1. An anti-glare, easy-to-clean automotive interior instrument panel surface coating, characterized in that, It contains component A and component B; Component A comprises the following raw materials in parts by weight: Highly branched hydroxyl-terminated polyester resin, in parts by solids of 65.0-75.0; Hydroxyfluoroolefin-vinyl ether copolymer, in parts by solids weight, 25.0-35.0 parts; Cellulose acetate butyrate: 2.0-4.0 parts; Dioctyltin lauryl thiolate: 0.1-0.5 parts; Dehydrating composite solvent: 100.0 parts; Component B contains hexamethylene diisocyanate trimer, and the ratio of the molar number of isocyanate groups in the hexamethylene diisocyanate trimer to the molar number of hydroxyl groups corresponding to the total hydroxyl equivalent of the residual hydroxyl groups on component A is (1.05-1.15):1; After the coating is applied to the surface of the automotive interior dashboard, the evaporation of the dehydrated composite solvent causes the cellulose acetate butyrate to form a rheological barrier, which promotes the enrichment of the hydroxyfluoroolefin-vinyl ether copolymer on the coating surface. The dioctyltin lauryl thiolate delays the internal crosslinking reaction between component A and component B, causing a shrinkage stress difference that results in a continuously undulating microsurface in the coating.

2. The anti-glare and easy-to-clean automotive interior dashboard surface coating according to claim 1, characterized in that, The butyryl group in the cellulose acetate butyrate has a mass fraction of 45%-55%, and the moisture content of the dehydration composite solvent has a mass percentage of 0.01%-0.05%.

3. The anti-glare and easy-to-clean automotive interior dashboard surface coating according to claim 1, characterized in that, The raw materials for synthesizing the highly branched, hydroxyl-terminated polyester resin include the following components in parts by weight: Trimethylolpropane: 20.0-30.0 parts; Neopentyl glycol: 25.0-35.0 parts; Isophthalic acid: 20.0-25.0 parts; Adipic acid: 15.0-25.0 parts; Monobutyltin oxide: 0.04-0.12 parts; Xylene: 2.0-3.0 parts.

4. The anti-glare and easy-to-clean automotive interior dashboard surface coating according to claim 3, characterized in that, The preparation process of the highly branched hydroxyl-terminated polyester resin includes: The following are added: trimethylolpropane, neopentyl glycol, isophthalic acid, adipic acid, xylene, and monobutyltin oxide as an esterification catalyst; Under nitrogen protection, the temperature was increased to 160℃ at a rate of 15-20℃ / h, and then slowly increased to 210-220℃ at a rate of 5-10℃ / h and held at that temperature to carry out the esterification reaction. The water produced by the esterification reaction is carried out by the xylene azeotrope, and after condensation, water-oil separation is performed to separate the water and reflux the xylene. When the acid value of the reaction mixture drops to 4.5-4.9 mg KOH / g, the residual xylene is removed by vacuum distillation under heat preservation to obtain a polyester resin solution. Stop heating and cool down to 120°C, add butanone to adjust the solid content of the polyester resin solution to 70%-75%, and obtain the highly branched hydroxyl-terminated polyester resin.

5. The anti-glare and easy-to-clean automotive interior dashboard surface coating according to claim 1, characterized in that, The raw materials for synthesizing the hydroxyfluoroolefin-vinyl ether copolymer comprise the following components in parts by weight: Butyl acetate: 60.0-100.0 parts; Hydroxybutyl vinyl ether: 5.8-17.4 parts; Cyclohexyl vinyl ether: 18.9-31.6 parts; Ethyl vinyl ether: 10.8-18.0 parts; Azobisisobutyronitrile: 0.5-1.5 parts; Gaseous trifluorochloroethylene: 52.4-64.0 parts.

6. The anti-glare and easy-to-clean automotive interior dashboard surface coating according to claim 5, characterized in that, The preparation process of the hydroxyfluoroolefin-vinyl ether copolymer includes: The butyl acetate, hydroxybutyl vinyl ether, cyclohexyl vinyl ether, ethyl vinyl ether, and azobisisobutyronitrile as an initiator are added sequentially to a pressure-resistant autoclave. After the air inside the pressure-resistant autoclave is replaced three times by evacuation and nitrogen filling, the gaseous trifluorochloroethylene is then injected under vacuum conditions. The temperature is raised to 60-70℃ for a constant-temperature polymerization reaction until the pressure inside the pressure-resistant autoclave drops to a stable level and no longer changes. The pressure is cooled to room temperature and the residual pressure in the pressure-resistant autoclave is released to atmospheric pressure. Unreacted monomers are removed under reduced pressure to obtain a copolymer solution. Butanone was added to adjust the solid content of the copolymer solution to 50%-60% to obtain the hydroxyfluoroolefin-vinyl ether copolymer.

7. The anti-glare and easy-to-clean automotive interior dashboard surface coating according to claim 1, characterized in that, The dehydrating composite solvent is obtained by dehydration treatment of a mixed solvent, wherein the mixed solvent comprises the following components in parts by weight: Butyl ketone: 72.0-84.0 parts; Aromatic solvent oil containing 9 to 10 carbon atoms: 27.0-31.9 parts, wherein the distillation range of the aromatic solvent oil containing 9 to 10 carbon atoms is 160-180℃; Propylene glycol methyl ether acetate: 9.0-16.1 parts.

8. The anti-glare and easy-to-clean automotive interior dashboard surface coating according to claim 7, characterized in that, The dehydrated composite solvent is obtained by pre-dehydration treatment through the following process: The butanone, the aromatic solvent oil containing 9 to 10 carbon atoms, and the propylene glycol methyl ether acetate are mixed to obtain the mixed solvent. The mixed solvent is then dehydrated by passing it through a 4A molecular sieve column. The water content of the mixed solvent after dehydration is controlled to be reduced to 0.01%-0.05% by mass to obtain the dehydrated composite solvent.

9. The anti-glare and easy-to-clean automotive interior dashboard surface coating according to claim 1, characterized in that, The coating for the automotive interior dashboard surface is prepared through the following steps: Add the cellulose acetate butyrate and 35.0-45.0 parts by weight of the dehydrated composite solvent, stir to dissolve, and obtain a rheology fluid; The highly branched hydroxyl-terminated polyester resin, the hydroxyl fluoroolefin-vinyl ether copolymer, and the dioctyltin lauryl thiolate were added to the rheology fluid, and the remaining amount of the dehydrating composite solvent was slowly added dropwise. The mixture was then dispersed to obtain component A. The hexamethylene diisocyanate trimer, which is component B, is added to component A and mixed to obtain a two-component mixture, thereby preparing the anti-glare and easy-to-clean automotive interior dashboard surface coating.

10. The anti-glare and easy-to-clean automotive interior dashboard surface coating according to claim 9, characterized in that, When preparing the rheological fluid, stir at 800-1000 rpm for 30-40 minutes at room temperature until homogeneous dissolution is achieved; In preparing component A, the remaining amount of the dehydrating composite solvent is slowly added dropwise under continuous stirring at 1000 rpm. After addition, increase the rotation speed to 1500-1800 rpm and disperse for 20-30 minutes to obtain the transparent homogeneous component A.

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