A transparent insect-proof self-repairing fire-retardant coating for ancient buildings and its preparation method

Abstract

The present invention discloses a transparent insect-proof self-repairing ancient building fire-retardant coating and a preparation method thereof, and relates to the technical field of wooden building protection. The present invention comprises an amino resin, isophorone diisocyanate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, phosphonitrile phosphate, guanidine phosphate, zirconium borate, pentaerythritol, phytic acid and a film-forming additive; the isophorone diisocyanate serves as a curing agent for the amino resin; the isophorone diisocyanate and the amino resin are connected via a hindered urea structure; the hindered urea structure is used for self-repair and forms hydrogen bonds with the phytic acid; so as to achieve the coating being able to self-repair fine scratches, and in the absence of an external ultraviolet absorber, being able to absorb ultraviolet rays and reduce the aging rate of wood, and a preparation method is provided to achieve the purpose of having hydrogen bonds for absorbing ultraviolet rays and for self-repairing the hindered urea structure in the prepared coating.

Description

Technical Field

[0001] The invention relates to the technical field of wooden building protection, in particular to a transparent insect-proof self-repairing fireproof coating for ancient buildings and a preparation method thereof. Background Art

[0002] Many of my country's ancient wooden structures hold inestimable historical and cultural value. However, their structural characteristics make them fire-hazardous, and once a fire occurs, it can easily cause irreparable damage. Therefore, it is necessary to strengthen fire protection for ancient buildings. Transparent fire-retardant coatings are a type of decorative fire-retardant coating that maintains the appearance of the substrate while also meeting fire protection requirements.

[0003] Transparent fire-retardant coatings protect the surfaces of ancient buildings without altering their appearance or color. When exposed to fire, they expand to form a uniform, dense, honeycomb-like or sponge-like carbon foam layer. This provides excellent protection against combustible ancient buildings, protecting them from fire damage and ensuring their fire safety. This prevents fire hazards before they occur, playing a crucial role in fire safety measures for ancient buildings. Consequently, there is a pressing demand for transparent fire-retardant coatings. Currently, only one or two officially certified transparent fire-retardant coatings exist in China, far from meeting societal needs. Furthermore, currently available transparent fire-retardant coatings on the market fail to meet the practical requirements for insect resistance, moisture resistance, and durability and weather resistance for ancient wooden structures. Therefore, further research into insect-resistant, durable, and weather-resistant transparent fire-retardant coatings is crucial to developing more and better products that meet the needs of society and are adaptable to developments. This is not only essential but also crucial for the preservation of ancient buildings.

[0004] Transparent fire-retardant coatings are a new fire protection technology developed in recent years. They are primarily used for fire protection of high-end wood decorative materials and historic buildings, without affecting their appearance or color. When used as exterior finishes on high-end wood decorative materials and historic buildings, transparent fire-retardant coatings offer decorative effects similar to other varnishes while also providing fire protection. Transparent fire-retardant coatings are generally based on synthetic organic polymer resins, which are sometimes modified with special groups to impart a certain amount of flame-retardant and foaming groups. A small amount of foaming agent, flame retardant, or carbon source is then added to create a fire protection system. To ensure the coating's fire resistance and other performance characteristics, a transparent topcoat is sometimes required.

[0005] The UN-C30 water-based transparent fireproof coating developed by Beijing Youansheng Fireproof Technology Co., Ltd. is composed of a modified amino resin as a base material, phosphoric acid and ammonium polyphosphate as dehydration catalysts, pentaerythritol as a carbonizing agent, melamine and urea as foaming agents, and water as a solvent. The L-1 transparent fireproof coating developed by Northeastern University is a water-soluble intumescent transparent fireproof coating. After drying, it forms a waterproof film, improving the coating's water resistance and eliminating the need for a topcoat, a distinct advantage over other transparent fireproof coatings. The borate ester fireproof coating synthesized by Chengde Petroleum College uses a high-polymer amino resin instead of an oligomer amino resin, ammonium polyborate instead of ammonium borate, and dipentaerythritol instead of pentaerythritol. This coating significantly enhances its fireproofing effectiveness and can meet the fire protection requirements of general materials. This is also a direction for future research. The intumescent transparent fire-retardant coating developed by the Henan Institute of Chemistry is based on isopropyl alcohol-modified melamine urea-formaldehyde resin and homemade chloroethyl phosphate as a flame retardant.

[0006] Chinese patent CN106634394B discloses a water-based transparent fire-retardant coating for ancient buildings and its preparation method, which improves the fire-retardant performance of the coating. The coating is transparent, can maintain the original appearance of the material, is not easy to crack, and has good weather resistance. The main component of the present invention is dry powder type, which effectively extends the shelf life of the coating.

[0007] Storage period; water-based wood stabilizer and phytic acid are added to the fire-retardant coating to effectively protect the wood from rot and deformation.

[0008] However, the existing technology has the problem of being difficult to prevent scratches, and in order to prevent the transparent coating from failing to completely block ultraviolet rays and causing rapid aging of the wood, it is necessary to add additional ultraviolet absorbers. Ultraviolet absorbers are one of the added fillers and have a certain impact on the film-forming effect of the coating. For the three-dimensional network structure formed by the curing of the resin, the more external fillers are added, the worse the density of the network structure is, thereby reducing the film-forming effect of the coating. Summary of the Invention

[0009] One of the purposes of the present invention is to provide a transparent insect-proof self-repairing fire-retardant coating for ancient buildings, so that the coating can self-repair fine scratches, and without adding ultraviolet absorbers, it can absorb ultraviolet rays and reduce the aging rate of wood.

[0010] In order to achieve the above object, the present invention adopts the following technical means:

[0011] A transparent insect-proof, self-repairing, fire-retardant coating for ancient buildings, comprising amino resin, isophorone diisocyanate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, phosphazene, guanidine phosphate, zirconium borate, pentaerythritol, phytic acid, and a film-forming additive;

[0012] The isophorone diisocyanate is used as a curing agent for the amino resin;

[0013] The isophorone diisocyanate and the amino resin are connected via a hindered urea structure;

[0014] The hindered urea structure is used for self-repair and hydrogen bonding with the phytic acid.

[0015] The isocyanate groups at both ends of isophorone diisocyanate react with the amino groups in the amino resin, with isophorone diisocyanate acting as a connecting segment, allowing the coating to form a three-dimensional network structure. Under a specific preparation method, a hindered urea structure is formed between the isophorone diisocyanate and the amino groups of the amino resin. When a minor scratch occurs on the coating surface, some of the segments in the coating break. Under the influence of ultraviolet light and the initiating factors in the coating, the hindered urea structure continuously relinks. At the same time, under the action of the initiating factors, the free amino groups and isocyanate groups in the coating system continuously combine to form new hindered urea structures, thereby achieving self-repair of minor scratches on the coating surface under sunlight, improving the durability and insect repellency of the coating.

[0016] The aforementioned triggering factor is the hydrogen bonds formed between the hindered urea structure and phytic acid. When ultraviolet light enters the coating, it is absorbed by the hydrogen bonds, breaking the bonds and releasing energy. This energy is then used to generate the hindered urea structure. This not only repairs minor scratches on the coating surface, but also, with increased use, the three-dimensional network structure within the coating becomes increasingly dense, further improving the coating's protective properties over time.

[0017] In addition, multiple hydrogen bonds can be formed between phytic acid and the hindered urea structure, thereby greatly increasing the coating's absorption of ultraviolet rays.

[0018] Furthermore, the film-forming additives include a thickening and leveling agent, a wetting and dispersing agent, a film-forming aid PPH, a defoaming agent, and a wood stabilizer MJB-TF.

[0019] Furthermore, the invention comprises, by weight, 30-40 parts of amino resin, 1-5 parts of isophorone diisocyanate, 1-5 parts of ethylene-vinyl acetate copolymer, 3-5 parts of polyvinyl alcohol, 5-10 parts of phosphanitrophosphonate, 5-10 parts of guanidine phosphate, 1-3 parts of zirconium borate, 5-10 parts of pentaerythritol, 3-6 parts of phytic acid, 0.5-1 part of thickening and leveling agent, 0.5-1 part of wetting and dispersing agent, 0.5-1 part of film-forming aid PPH, 0.5-1 part of defoaming agent and 0.5-1 part of wood stabilizer MJB-TF.

[0020] The ethylene-vinyl acetate copolymer and polyvinyl alcohol used in the present invention can increase the flexibility of the paint film; in the entire coating system, there is no need to add additional ultraviolet absorbers, and the normal preparation of the coating can ensure the coating performance while enabling it to absorb ultraviolet rays. Phytic acid, as a substance that prevents wood from rotting and oxidation, is also necessary for the protection of wooden buildings.

[0021] Furthermore, another object of the present invention is to provide a method for preparing the aforementioned transparent insect-proof self-repairing ancient building fire-retardant coating, so as to achieve the purpose of enabling the prepared coating to have hydrogen bonds for absorbing ultraviolet rays and for self-repairing hindered urea structures.

[0022] In order to achieve the above object, the present invention adopts the following technical means:

[0023] A method for preparing the aforementioned transparent insect-proof self-repairing fire-retardant coating for ancient buildings, comprising:

[0024] Initial mixing: adding amino resin, ethylene-vinyl acetate copolymer, polyvinyl alcohol, phosphazene, guanidine phosphate, zirconium borate, pentaerythritol, and phytic acid into acetone solvent, stirring and mixing to obtain mixture A;

[0025] Final mixing: add a film-forming additive to mixed material A, add triethanolamine to adjust the pH of the reaction step to alkaline, then add isophorone diisocyanate, stir in a dark room environment, stir evenly, and then perform high-temperature curing in a dark room environment for 1 to 2 days to obtain the fire retardant coating.

[0026] Preferably, in the final mixing step, the pH is 8-9.

[0027] Furthermore, in the final mixing step, the curing temperature is 70-80°C.

[0028] Among them, pH value and temperature are more stringent reaction conditions. If the pH value is low and the temperature is lower than 70°C, a hindered urea structure cannot be formed between isophorone diisocyanate and the amino resin. In this state, the curing is completely formed by the self-curing of the amino resin, and a three-dimensional network structure cannot be formed. The mechanical properties of the coating are poor, and a large number of hydrogen bonds cannot be formed inside it, which cannot absorb ultraviolet rays well. At the same time, the coating cannot self-repair after scratches.

[0029] When the pH value is greater than 9, although a three-dimensional network structure can be formed after curing and the mechanical properties of the coating are better, the purpose of self-repair cannot be achieved in practice. When the pH value is greater than 9, the hydrogen bonds formed in the system will be destroyed, resulting in the inability to effectively absorb ultraviolet rays under sunlight. Therefore, the aforementioned initiating factors cannot take effect and cannot promote the regeneration of the hindered urea structure.

[0030] Therefore, the method provided by the present invention is used to prepare the corresponding coating, which not only enables the coating to have the effects of self-repair and ultraviolet absorption, but also can be prepared in a dark room, thereby avoiding excessive cross-linking during the preparation process and rapid curing, which causes high internal stress in the coating and easily falls off from the surface of the wooden building. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0032] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0033] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other.

[0034] A transparent insect-proof, self-repairing, fire-retardant coating for ancient buildings, comprising amino resin, isophorone diisocyanate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, phosphazene, guanidine phosphate, zirconium borate, pentaerythritol, phytic acid, and a film-forming additive;

[0035] The isophorone diisocyanate is used as a curing agent for the amino resin;

[0036] The isophorone diisocyanate and the amino resin are connected via a hindered urea structure;

[0037] The hindered urea structure is used for self-repair and hydrogen bonding with the phytic acid.

[0038] The isocyanate groups at both ends of isophorone diisocyanate react with the amino groups in the amino resin, with isophorone diisocyanate acting as a connecting segment, allowing the coating to form a three-dimensional network structure. Under a specific preparation method, a hindered urea structure is formed between the isophorone diisocyanate and the amino groups of the amino resin. When a minor scratch occurs on the coating surface, some of the segments in the coating break. Under the influence of ultraviolet light and the initiating factors in the coating, the hindered urea structure continuously relinks. At the same time, under the action of the initiating factors, the free amino groups and isocyanate groups in the coating system continuously combine to form new hindered urea structures, thereby achieving self-repair of minor scratches on the coating surface under sunlight, improving the durability and insect repellency of the coating.

[0039] The aforementioned triggering factor is the hydrogen bonds formed between the hindered urea structure and phytic acid. When ultraviolet light enters the coating, it is absorbed by the hydrogen bonds, breaking the bonds and releasing energy. This energy is then used to generate the hindered urea structure. This not only repairs minor scratches on the coating surface, but also, with increased use, the three-dimensional network structure within the coating becomes increasingly dense, further improving the coating's protective properties over time.

[0040] In addition, multiple hydrogen bonds can be formed between phytic acid and the hindered urea structure, thereby greatly increasing the coating's absorption of ultraviolet rays.

[0041] Furthermore, the film-forming additives include a thickening and leveling agent, a wetting and dispersing agent, a film-forming aid PPH, a defoaming agent, and a wood stabilizer MJB-TF.

[0042] Furthermore, the invention comprises, by weight, 30-40 parts of amino resin, 1-5 parts of isophorone diisocyanate, 1-5 parts of ethylene-vinyl acetate copolymer, 3-5 parts of polyvinyl alcohol, 5-10 parts of phosphanitrophosphonate, 5-10 parts of guanidine phosphate, 1-3 parts of zirconium borate, 5-10 parts of pentaerythritol, 3-6 parts of phytic acid, 0.5-1 part of thickening and leveling agent, 0.5-1 part of wetting and dispersing agent, 0.5-1 part of film-forming aid PPH, 0.5-1 part of defoaming agent and 0.5-1 part of wood stabilizer MJB-TF.

[0043] The ethylene-vinyl acetate copolymer and polyvinyl alcohol used in the present invention can increase the flexibility of the paint film; in the entire coating system, there is no need to add additional ultraviolet absorbers, and the normal preparation of the coating can ensure the coating performance while enabling it to absorb ultraviolet rays. Phytic acid, as a substance that prevents wood from rotting and oxidation, is also necessary for the protection of wooden buildings.

[0044] Furthermore, another object of the present invention is to provide a method for preparing the aforementioned transparent insect-proof self-repairing ancient building fire-retardant coating, so as to achieve the purpose of enabling the prepared coating to have hydrogen bonds for absorbing ultraviolet rays and for self-repairing hindered urea structures.

[0045] In order to achieve the above object, the present invention adopts the following technical means:

[0046] A method for preparing the aforementioned transparent insect-proof self-repairing fire-retardant coating for ancient buildings, comprising:

[0047] Initial mixing: adding amino resin, ethylene-vinyl acetate copolymer, polyvinyl alcohol, phosphazene, guanidine phosphate, zirconium borate, pentaerythritol, and phytic acid into acetone solvent, stirring and mixing to obtain mixture A;

[0048] Final mixing: add a film-forming additive to mixed material A, add triethanolamine to adjust the pH of the reaction step to alkaline, then add isophorone diisocyanate, stir in a dark room environment, stir evenly, and then perform high-temperature curing in a dark room environment for 1 to 2 days to obtain the fire retardant coating.

[0049] Preferably, in the final mixing step, the pH is 8-9.

[0050] Furthermore, in the final mixing step, the curing temperature is 70-80°C.

[0051] Among them, pH value and temperature are more stringent reaction conditions. If the pH value is less than 8 and the temperature is lower than 70°C, a hindered urea structure cannot be formed between isophorone diisocyanate and the amino resin. In this state, the curing is completely formed by the self-curing of the amino resin, and a three-dimensional network structure cannot be formed. The mechanical properties of the coating are poor, and a large number of hydrogen bonds cannot be formed inside it, which cannot absorb ultraviolet rays well. At the same time, the coating cannot self-repair after scratches.

[0052] When the pH value is greater than 9, although a three-dimensional network structure can be formed after curing and the mechanical properties of the coating are better, the purpose of self-repair cannot be achieved in practice. When the pH value is greater than 9, the hydrogen bonds formed in the system will be destroyed, resulting in the inability to effectively absorb ultraviolet rays under sunlight. Therefore, the aforementioned initiating factors cannot take effect and cannot promote the regeneration of the hindered urea structure.

[0053] Therefore, the method provided by the present invention is used to prepare the corresponding coating, which not only enables the coating to have the effects of self-repair and ultraviolet absorption, but also can be prepared in a dark room, thereby avoiding excessive cross-linking during the preparation process and rapid curing, which causes high internal stress in the coating and easily falls off from the surface of the wooden building.

[0054] Example 1

[0055] The coating is prepared by adopting the formula and preparation method of the present invention.

[0056] Example 2

[0057] The reaction pH in Example 1 was adjusted to less than 8.

[0058] Example 3

[0059] The reaction pH in Example 1 was adjusted to greater than 9.

[0060] Example 4

[0061] The curing temperature in Example 1 was set to less than 70°C.

[0062] Example 5

[0063] The curing temperature in Example 1 was set to be greater than 80°C.

[0064] After comparing Examples 1 to 5, although the mechanical properties of the coatings in Examples 5 and 3 are improved, the problems they bring are that the coating curing time is too fast, the coating shrinks severely, the adhesion is greatly reduced, and the coating cannot self-repair, and the hydrogen bonds in the coating are greatly damaged.

[0065] In Example 2 and Example 4, although the coating can be cured, the mechanical properties of the coating are significantly reduced, and it is unable to perform self-repair and absorb a large amount of ultraviolet rays. This means that not only is there no hindered urea structure formed inside, but there are also no large amounts of hydrogen bonds to absorb ultraviolet rays. In this case, an external ultraviolet absorber is required to use the transparent coating to protect wooden buildings.

[0066] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A transparent insect-proof self-repairing fire-retardant coating for ancient buildings, characterized by: Including amino resin, isophorone diisocyanate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, phosphazene phosphate, guanidine phosphate, zirconium borate, pentaerythritol, phytic acid and film-forming additives; The isophorone diisocyanate is used as a curing agent for the amino resin; The isophorone diisocyanate and the amino resin are connected via a hindered urea structure; The hindered urea structure is used for self-repair and formation of hydrogen bonds with the phytic acid; The film-forming additives include a thickening and leveling agent, a wetting and dispersing agent, a film-forming aid PPH, a defoaming agent, and a wood stabilizer MJB-TF; The composition comprises, by weight, 30-40 parts of amino resin, 1-5 parts of isophorone diisocyanate, 1-5 parts of ethylene-vinyl acetate copolymer, 3-5 parts of polyvinyl alcohol, 5-10 parts of phosphanitrogen phosphonate, 5-10 parts of guanidine phosphate, 1-3 parts of zirconium borate, 5-10 parts of pentaerythritol, 3-6 parts of phytic acid, 0.5-1 part of thickening and leveling agent, 0.5-1 part of wetting and dispersing agent, 0.5-1 part of film-forming aid PPH, 0.5-1 part of defoaming agent and 0.5-1 part of wood stabilizer MJB-TF; The transparent insect-proof self-repairing ancient building fire-retardant coating is prepared in the following manner: Initial mixing: adding amino resin, ethylene-vinyl acetate copolymer, polyvinyl alcohol, phosphazene, guanidine phosphate, zirconium borate, pentaerythritol, and phytic acid into acetone solvent, stirring and mixing to obtain mixture A; Final mixing: adding a film-forming additive to the mixture A, adding triethanolamine to adjust the pH of the reaction step to alkaline, and then adding isophorone diisocyanate, stirring in a dark room environment, stirring evenly, and then performing high-temperature curing in a dark room environment for 1 to 2 days to obtain the fire retardant coating; Wherein, in the final mixing step, the pH is 8-9 and the curing temperature is 70-80°C.