Flame-retardant impact-resistant modified silicone oil polyurethane coating and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a flame-retardant impact-resistant modified silicone oil polyurethane coating and a preparation method thereof. The flame-retardant impact-resistant modified silicone oil polyurethane coating is prepared from the following components in parts by weight: 100 parts of polyurethane emulsion, 25 to 35 parts of modified polydimethylsiloxane, 0.5 to 1 part of dispersing agent and 5 to 15 parts of pigment filler. According to the invention, the self-healing polymer and triphenyl phosphate modified polydimethylsiloxane (PDMS) are combined and applied to the polyurethane coating through the cross-linking agent diethoxy isocyanate phosphonium ester, so that the flame retardance and impact resistance of the polyurethane coating are remarkably improved. Wherein the self-healing polymer endows the polyurethane coating with impact resistance and self-repairing ability, PDMS and triphenyl phosphate enhance the flame retardance, heat resistance and mechanical properties of the polyurethane coating, and diethoxy phosphonium isocyanate further consolidates the thermal stability, mechanical strength and wear resistance of the polyurethane coating through efficient crosslinking and flame retardance characteristics.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a flame retardant and impact resistant modified silicone oil polyurethane coating and a preparation method thereof. Background Art

[0002] Polyurethane coating is a kind of coating with excellent wear resistance, weather resistance and adhesion properties. It is widely used in the fields of construction, automobiles and furniture. Although polyurethane coatings used in the above fields have made certain progress in flame retardancy and impact resistance, there is still room for improvement. For example, existing polyurethane coatings still have problems such as insufficient flame retardancy under high temperature environments and unsatisfactory impact resistance under extreme conditions. Since the flame retardancy of current polyurethane coatings usually depends on the addition of inorganic flame retardants, such as aluminum hydroxide, it reduces the spread of flames through chemical reactions or physical shielding to achieve the flame retardant effect. However, the addition of such inorganic flame retardants will affect the transparency and mechanical properties of the coating, causing the polyurethane coating to crack or peel off when facing high-intensity impact, and the impact resistance will be weakened. Therefore, further in-depth research on polyurethane coatings is needed to provide more room for improving the flame retardancy and impact resistance of polyurethane coatings.

[0003] For example, the Chinese patent application with publication number CN107629672A discloses a waterproof polyurethane coating and its preparation method. The components and their weight ratios of the waterproof polyurethane coating are: 30-50 parts of dimethyl ether, 20-30 parts of polyvinylidene chloride, 35-50 parts of long-chain polyether substances, 35-50 parts of isocyanate, 40-50 parts of polyether polyol, 10-30 parts of light calcium carbonate powder, 10-15 parts of glass fiber powder, 12-18 parts of perlite powder, 5-10 parts of mica powder, 5-10 parts of inorganic flame retardant, 1-3 parts of film-forming aid, 0.2-0.5 parts of dispersant, 5-10 parts of fungicide, 0.3-1.5 parts of leveling agent, and 4-6 parts of deionized water. The inorganic flame retardant is a mixed flame retardant of aluminum hydroxide, magnesium hydroxide, and microencapsulated red phosphorus. Although the inorganic flame retardant provides a good flame retardant effect for the waterproof polyurethane coating, these inorganic substances usually have a large particle size and are unevenly distributed, which will cause the optical properties of the coating to decrease, thereby affecting the transparency; and the addition of inorganic flame retardants will also increase the brittleness of the coating, resulting in reduced flexibility and impact resistance of the waterproof polyurethane coating. Therefore, the present invention provides a flame retardant and impact-resistant modified silicone oil polyurethane coating and a preparation method thereof, in order to solve the above technical problems. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a flame retardant and impact resistant modified silicone oil polyurethane coating and a preparation method thereof. The present invention combines a self-healing polymer with triphenyl phosphate-modified polydimethylsiloxane (PDMS) through a cross-linking agent diethoxyisocyanate phosphonate and applies it to a polyurethane coating, which significantly improves the flame retardancy and impact resistance of the polyurethane coating. The self-healing polymer imparts the polyurethane coating with self-repairing ability, while PDMS and triphenyl phosphate enhance its flame retardancy, heat resistance and mechanical properties. Moreover, through the efficient cross-linking and flame retardant properties of diethoxyisocyanate phosphonate, the thermal stability, mechanical strength and wear resistance of the polyurethane coating are further effectively consolidated.

[0005] A flame retardant and impact resistant modified silicone oil polyurethane coating comprises the following components in parts by weight: 100 parts of polyurethane emulsion, 25-35 parts of modified polydimethylsiloxane, 0.5-1 part of dispersant, and 5-15 parts of pigments and fillers.

[0006] Furthermore, the preparation method of the modified polydimethylsiloxane includes: adding an organic solvent, polydimethylsiloxane and triphenyl phosphate to a reaction kettle under an inert gas atmosphere, stirring evenly, then adding an amino catalyst to the reaction system, heating the reaction system to 60-80°C, maintaining a constant temperature, continuously stirring, the reaction time is 2-3 hours, and the reaction is completed to obtain an initial modified polydimethylsiloxane; adding a self-healing polymer and a cross-linking agent diethoxyisocyanate phosphinate to the above-mentioned initial modified polydimethylsiloxane, stirring evenly, and continuing to maintain the system temperature at 60-80°C for reaction to obtain a modified polydimethylsiloxane; the self-healing polymer is a polymer prepared by Diels-Alder reaction using cis-1,3-butadiene and maleic anhydride as raw materials.

[0007] The present invention combines self-healing polymer, triphenyl phosphate-modified polydimethylsiloxane (PDMS) and diethoxyisocyanate phosphonate crosslinker for polyurethane coating, which significantly improves the flame retardancy and impact resistance of polyurethane coating. Among them, the self-healing polymer gives the polyurethane coating excellent self-healing ability, while the triphenyl phosphate-modified PDMS jointly enhances the flame retardancy, heat resistance and mechanical properties; secondly, diethoxyisocyanate phosphonate further enhances the overall performance of the polyurethane coating through its efficient crosslinking and flame retardant properties, and its phosphate group can effectively react with PDMS and self-healing polymer to form a stable crosslinked network structure, which not only improves the thermal stability of the polyurethane coating, but also improves the mechanical strength and wear resistance of the polyurethane coating.

[0008] The self-healing polymer prepared by the Diels-Alder reaction using cis-1,3-butadiene and maleic anhydride as raw materials has a high degree of reversibility. In particular, when subjected to physical damage, the Diels-Alder bond can be reformed at a specific temperature to repair microcracks and prevent crack expansion caused by impact, thereby achieving self-healing of the polyurethane material and extending the service life of the coating. Secondly, the present invention modifies PDMS by triphenyl phosphate (TPP), effectively improving the tolerance of the coating when encountering high temperature or flame, and the TPP molecule can release phosphorus at high temperature to form a phosphoric acid barrier to inhibit the combustion process; and it can also enhance the rigidity of the molecular chain, thereby improving the mechanical properties of the material, especially impact resistance; and PDMS itself is a hydrophobic material with excellent heat resistance and chemical corrosion resistance, which helps to prevent the penetration of moisture and other corrosive substances, and can further enhance the durability and aging resistance of the material. Furthermore, the cross-linking agent diethoxy phosphonoisocyanate of the present invention is an organic phosphine compound, and the phosphate group can react with PDMS and the self-healing polymer to effectively promote the formation of cross-linking points and form a stable cross-linking network structure without destroying the reversibility of the Diels-Alder reaction; furthermore, diethoxy phosphonoisocyanate as a phosphine compound can decompose at high temperature to produce non-flammable phosphoric acid substances to form a protective layer, which helps to prevent the spread of flames, and the phosphorus element therein can also inhibit the generation of pyrolysis gas, thereby reducing the flammability of the polyurethane coating.

[0009] Furthermore, in the preparation method of the modified polydimethylsiloxane, the mass ratio of polydimethylsiloxane to triphenyl phosphate is 20:(3-5); the amount of the amino catalyst is 0.4-0.8% of the total mass of the polydimethylsiloxane and triphenyl phosphate. The above ratio can ensure the main chain structure of the polydimethylsiloxane and effectively introduce sufficient flame retardant to improve the flame retardant performance of the material.

[0010] Furthermore, the mass ratio of the self-healing polymer to the primary modified polydimethylsiloxane is 2:(3-5); this ratio can provide sufficient self-healing polymer to ensure that the coating has good self-healing ability after being damaged, while maintaining the basic properties of the modified polydimethylsiloxane. The amount of cross-linking agent diethoxyphosphonic isocyanate is 5-10% of the total mass of the self-healing polymer and the primary modified polydimethylsiloxane. The above amount of cross-linking agent can effectively form a cross-linked network, enhance the mechanical properties and thermal stability of the material, while excessive cross-linking agent may cause the material to become brittle, thereby affecting toughness.

[0011] Furthermore, the amino catalyst is triethylamine.

[0012] Furthermore, the preparation method of the self-healing polymer comprises: under the protection of an inert gas, adding an organic solvent into a reactor, then adding cis-1,3-butadiene and maleic anhydride into the reactor, mixing evenly, then adding an amino catalyst, then heating the reactor to 65-80° C., stirring the reaction mixture with a stirrer, and continuing the reaction for 2-3 hours. After the reaction is completed, a self-healing polymer is obtained. The amino catalyst is preferably triethylamine.

[0013] The reverse reaction of the Diels-Alder reaction of the self-healing polymer generated by the reaction of cis-1,3-butadiene and maleic anhydride usually occurs between 80°C and 120°C. Below this temperature, the Diels-Alder bond is relatively stable and will not easily undergo a reverse reaction or dissociation; when it reaches or exceeds 80°C, the reverse reaction gradually begins, and the broken areas in the polymer network can reconnect and complete self-healing. This specific temperature window allows the material to remain stable at room temperature, while having the ability to self-heal when damaged or heated, which can effectively improve the impact resistance of polyurethane coatings.

[0014] Furthermore, the molar ratio of cis-1,3-butadiene to maleic anhydride is 1:1; and the amount of the catalyst used is 0.2-0.5% of the total mass of cis-1,3-butadiene and maleic anhydride.

[0015] Furthermore, the dispersant is potassium polyacrylate or sodium polyacrylate; and the pigment filler is at least one of quartz powder, titanium dioxide, talcum powder or calcium carbonate.

[0016] Moreover, the present invention also provides a method for preparing the flame retardant and impact resistant modified silicone oil polyurethane coating as described above, comprising: mixing polyurethane emulsion and modified polydimethylsiloxane, adding dispersant and pigment filler, mixing and degassing to obtain polyurethane coating.

[0017] Compared with the prior art, the flame retardant and impact resistant modified silicone oil polyurethane coating and the preparation method thereof provided by the present invention have the following advantages:

[0018] (1) The present invention combines a self-healing polymer and triphenyl phosphate-modified polydimethylsiloxane (PDMS) with a crosslinking agent, diethoxyisocyanate phosphinate, and applies it to polyurethane coatings, thereby significantly improving the flame retardancy and impact resistance of polyurethane coatings. The self-healing polymer is prepared by Diels-Alder reaction of cis-1,3-butadiene and maleic anhydride, and has high reversibility. When physically damaged, the Diels-Alder bond can be reformed at a specific temperature, thereby achieving self-repair of the material, that is, repairing microcracks and preventing crack expansion. This feature greatly extends the service life of the coating. At the same time, the modification of PDMS with triphenyl phosphate enhances the flame retardant, heat resistant and mechanical properties of the coating. Specifically, TPP molecules can release phosphorus at high temperatures to form a phosphoric acid barrier and inhibit the combustion process. In addition, the introduction of TPP also enhances the rigidity of the PDMS molecular chain and improves the impact resistance of the material. PDMS itself, as a hydrophobic material, has excellent heat resistance and chemical corrosion resistance, can effectively prevent the penetration of moisture and other corrosive substances, and further enhance the durability and aging resistance of the material.

[0019] (2) The cross-linking agent diethoxy phosphonoisocyanate in the present invention is an organic phosphine compound, and its phosphate group can effectively react with PDMS and self-healing polymers to promote the formation of a stable cross-linked network structure while maintaining the reversibility of the Diels-Alder reaction. This cross-linked network not only improves the thermal stability of the material, but also improves its mechanical strength and wear resistance. It is worth noting that diethoxy phosphonoisocyanate will also decompose at high temperatures to produce non-flammable phosphoric acid substances, forming a protective layer that helps to prevent flame propagation; in addition, the release of phosphorus can also inhibit the generation of pyrolysis gases, thereby reducing the flammability of the material.

[0020] In summary, the present invention significantly improves the performance of polyurethane coatings through the synergistic effect of the repair ability of self-healing polymers, the flame retardancy, heat resistance and mechanical properties of TPP-modified PDMS, and the crosslinking and flame retardancy of diethoxyisocyanate phosphonate, making it show stronger applicability and durability in high temperature and impact environments, providing broad prospects for related applications. DETAILED DESCRIPTION

[0021] The present invention is further illustrated below through the description of specific implementation methods, but this is not a limitation of the present invention. Those skilled in the art can make various modifications or improvements based on the basic idea of ​​the present invention, but as long as they do not deviate from the basic idea of ​​the present invention, they are all within the protection scope of the present invention.

[0022] In the following examples and comparative examples, the methods used are all prior art unless otherwise specified; the reagents not otherwise specified are conventional reagents and can be purchased from conventional reagent production and sales companies. The information of some raw material manufacturers or CAS numbers is as follows:

[0023] Polyurethane emulsion, purchased from Shenzhen Jitian Chemical Co., Ltd., model F0401;

[0024] Polydimethylsiloxane was purchased from Jinan Shanhai Chemical Technology Co., Ltd.;

[0025] Diethoxyphosphonic isocyanate, CAS number is 20039-33-2;

[0026] Triphenyl phosphate, CAS number is 26967-76-0;

[0027] Cis-1,3-butadiene, CAS number is 106-99-0;

[0028] Maleic anhydride, CAS number is 108-31-6;

[0029] Triethylamine, CAS number is 121-44-8.

[0030] Example 1

[0031] Preparation method of self-healing polymer:

[0032] Under the protection of inert gas, 300 mL of dichloromethane was added to the reactor, and then cis-1,3-butadiene and maleic anhydride in a molar ratio of 1:1 were added to the reactor and mixed evenly. Then, amino catalyst triethylamine was added, and the amount of triethylamine was 0.2% of the total mass of cis-1,3-butadiene and maleic anhydride. The reactor was then heated to 65°C and continuously stirred for 2 hours. After the reaction was completed, the solvent was removed to obtain a self-healing polymer.

[0033] Preparation method of modified polydimethylsiloxane:

[0034] Under an inert gas atmosphere, 500 mL of dichloromethane, 200 g of polydimethylsiloxane and 30 g of triphenyl phosphate were added to the reactor and stirred evenly. Subsequently, the amino catalyst triethylamine was added to the reaction system, and the amount of the amino catalyst was 0.4% of the total mass of polydimethylsiloxane and triphenyl phosphate. The reaction system was heated to 60°C, the temperature was kept constant, and stirring was continued. The reaction time was 2 hours. After the reaction was completed, the solvent was removed to obtain the initial modified polydimethylsiloxane; 200 g of the self-healing polymer and the cross-linking agent diethoxyisocyanate phosphinate were added to 300 g of the initial modified polydimethylsiloxane prepared by the above method, and the amount of the cross-linking agent was 5% of the total mass of the self-healing polymer and the initial modified polydimethylsiloxane. The mixture was stirred evenly, and the system temperature was continued to be maintained at 60°C for reaction to obtain modified polydimethylsiloxane.

[0035] The preparation method of flame retardant and impact resistant modified silicone oil polyurethane coating is as follows: 100 parts of polyurethane emulsion and 25 parts of modified polydimethylsiloxane are mixed, and then 0.5 parts of dispersant potassium polyacrylate and 5 parts of pigment filler quartz powder are added, mixed and degassed to obtain polyurethane coating.

[0036] Example 2

[0037] Preparation method of self-healing polymer:

[0038] Under the protection of inert gas, 300 mL of dichloromethane was added to the reactor, and then cis-1,3-butadiene and maleic anhydride in a molar ratio of 1:1 were added to the reactor and mixed evenly. Then, amino catalyst triethylamine was added, and the amount of triethylamine was 0.5% of the total mass of cis-1,3-butadiene and maleic anhydride. The reactor was then heated to 80°C and continuously stirred for 3 hours. After the reaction was completed, the solvent was removed to obtain a self-healing polymer.

[0039] Preparation method of modified polydimethylsiloxane:

[0040] Under an inert gas atmosphere, 500 mL of dichloromethane, 200 g of polydimethylsiloxane and 50 g of triphenyl phosphate were added to the reactor and stirred evenly. Subsequently, the amino catalyst triethylamine was added to the reaction system, and the amount of the amino catalyst was 0.8% of the total mass of polydimethylsiloxane and triphenyl phosphate. The reaction system was heated to 80°C, the temperature was kept constant, and stirring was continued. The reaction time was 3 hours. After the reaction was completed, the solvent was removed to obtain the initial modified polydimethylsiloxane; 200 g of the self-healing polymer and the cross-linking agent diethoxyisocyanate phosphinate were added to 500 g of the initial modified polydimethylsiloxane prepared by the above method, and the amount of the cross-linking agent was 10% of the total mass of the self-healing polymer and the initial modified polydimethylsiloxane. The mixture was stirred evenly, and the system temperature was continued to be maintained at 80°C for reaction to obtain modified polydimethylsiloxane.

[0041] The preparation method of flame retardant and impact resistant modified silicone oil polyurethane coating is as follows: 100 parts of polyurethane emulsion and 35 parts of modified polydimethylsiloxane are mixed, and then 1 part of dispersant polyacrylate sodium salt and 15 parts of color filler calcium carbonate are added, mixed and degassed to obtain polyurethane coating.

[0042] Example 3

[0043] Preparation method of self-healing polymer:

[0044] Under the protection of inert gas, 300 mL of dichloromethane was added to the reactor, and then cis-1,3-butadiene and maleic anhydride in a molar ratio of 1:1 were added to the reactor and mixed evenly. Then, amino catalyst triethylamine was added, and the amount of triethylamine was 0.3% of the total mass of cis-1,3-butadiene and maleic anhydride. The reactor was then heated to 70°C and continuously stirred for 3 hours. After the reaction was completed, the solvent was removed to obtain a self-healing polymer.

[0045] Preparation method of modified polydimethylsiloxane:

[0046] Under an inert gas atmosphere, 500 mL of dichloromethane, 200 g of polydimethylsiloxane and 40 g of triphenyl phosphate were added to the reactor and stirred evenly. Subsequently, the amino catalyst triethylamine was added to the reaction system, and the amount of the amino catalyst was 0.6% of the total mass of polydimethylsiloxane and triphenyl phosphate. The reaction system was heated to 70°C, the temperature was kept constant, and stirring was continued. The reaction time was 2.5 hours. After the reaction was completed, the solvent was removed to obtain the initial modified polydimethylsiloxane; 200 g of the self-healing polymer and the cross-linking agent diethoxyisocyanate phosphinate were added to 400 g of the initial modified polydimethylsiloxane prepared by the above method, and the amount of the cross-linking agent was 7% of the total mass of the self-healing polymer and the initial modified polydimethylsiloxane. The mixture was stirred evenly, and the system temperature was continued to be maintained at 70°C for reaction to obtain modified polydimethylsiloxane.

[0047] The preparation method of flame retardant and impact resistant modified silicone oil polyurethane coating is as follows: 100 parts of polyurethane emulsion and 30 parts of modified polydimethylsiloxane are mixed, and then 1 part of dispersant polyacrylate sodium salt and 10 parts of color filler talcum powder are added, mixed and degassed to obtain polyurethane coating.

[0048] Comparative Example 1

[0049] The difference from Example 3 is that no self-healing polymer is added during the preparation of the modified polydimethylsiloxane, and the other steps and preparation process are the same as those of Example 3.

[0050] Comparative Example 2

[0051] The difference from Example 3 is that no triphenyl phosphate is added during the preparation of the modified polydimethylsiloxane, and 8 parts of aluminum hydroxide are added during the preparation of the flame retardant and impact resistant modified silicone oil polyurethane coating; the other steps and preparation process are the same as Example 3.

[0052] Comparative Example 3

[0053] The difference from Example 3 is that diisocyanate (such as MDI) is used to replace diethoxyphosphonic isocyanate, and the other steps and preparation process are the same as those of Example 3.

[0054] Test example: performance test

[0055] 1. Test materials: flame retardant and impact resistant modified silicone oil polyurethane coatings prepared in the examples and comparative examples of the present invention.

[0056] 2. Test methods:

[0057] (1) Impact resistance is tested in accordance with GB / T 1732-1993.

[0058] (2) Droplet test

[0059] Sample preparation: Pour the prepared flame retardant and impact resistant modified silicone oil polyurethane coating into a polytetrafluoroethylene mold, control the thickness to 3mm, put it into a constant temperature and humidity box set at 23℃±0.5℃ and humidity 50%±5% for 48h to obtain a polyurethane film, then take it out and cut it into 110cm×10cm×3mm samples.

[0060] Parameters: Clamp about 5mm from the top so that the sample is vertically downward, place a rosin board at the lower end of the sample, and pad about 0.3g of absorbent cotton on the board, evenly place it on the board, adjust the gas flow rate to 105±5mL / min, make the flame height reach 20±1mm, and set the combustion time to 10s.

[0061] Droplet observation: During the combustion process, pay attention to whether the combustion produces droplets, and whether the droplets falling on the absorbent cotton below will cause secondary combustion, and record the observation results.

[0062] (3) Self-healing rate: The prepared flame-retardant and impact-resistant modified silicone oil polyurethane coating was poured into a polytetrafluoroethylene mold, and the thickness was controlled to be 1 mm. The coating was placed in a constant temperature and humidity chamber set at 23°C ± 0.5°C and 50% ± 5% humidity for 48 h to obtain a polyurethane film. The film was then taken out and cut into samples with a thickness of 1 mm, a length of 10 cm, and a width of 5 mm. A horizontal line was then cut in the middle of the polyurethane film sample with a blade, and the film was cut and baked at 80°C for 3 h. The uncut original specimen and the specimen after the self-healing test were subjected to tensile tests at a tensile rate of 50 mm / min. The comparison of the maximum strain ratio before and after the repair was the self-healing rate.

[0063] 3. The test results are shown in Table 1:

[0064] Table 1 Performance test results

[0065] Group Impact resistance Burning droplet phenomenon Self-repair rate / % Example 1 No cracks, wrinkles or peeling No melting and no dripping 85.1 Example 2 No cracks, wrinkles or peeling No melting and no dripping 86.7 Example 3 No cracks, wrinkles or peeling No melting and no dripping 88.3 Comparative Example 1 Wrinkles and fine cracks appear, but no peeling No melting and no dripping 0 Comparative Example 2 Cracks, wrinkles, and partial peeling A small amount of dripping, no secondary combustion 74.2 Comparative Example 3 Small cracks and a small amount of peeling A small amount of dripping may cause secondary combustion 46.5

[0066] As shown in Table 1, the flame retardant and impact resistant modified silicone oil polyurethane coating obtained in the embodiment of the present invention has good performance test results, excellent flame retardancy and impact resistance, and a self-repair rate of up to 88.3%; while the various properties of the comparative examples in each group are affected to varying degrees.

[0067] For example, since the introduction of self-healing polymer helps the material to relieve stress distribution when it is impacted and increase the overall toughness of the material, the comparative example 1 without adding the self-healing polymer shows a lower impact resistance, and also has fine cracks and wrinkles; secondly, the comparative example 1 does not add the self-healing polymer, so there is no effect of the self-healing mechanism. The comparative example 2 without adding triphenyl phosphate and adding 8 parts of aluminum hydroxide during the preparation process makes the material lack the plasticizing and heat-resistant stabilization effect of triphenyl phosphate, and the flexibility of the polymer will be reduced, so the impact resistance of comparative example 2 is poor, showing cracks, wrinkles, and local peeling; moreover, although aluminum hydroxide has a certain flame retardant effect and can decompose water at high temperature, this instead causes the material to produce a molten drop phenomenon when burning, but does not cause secondary combustion; secondly, it can be seen from the self-repair rate test results of comparative example 2 that triphenyl phosphate may have a certain promoting effect on the flexibility and self-healing performance of the material in the system, and the lack of this component will reduce the self-repair rate of the material to a certain extent. After comparative example 3 uses diisocyanate to replace diethoxyphosphinothioate, the impact resistance exhibited is poor. This is because the cross-linking density of diisocyanate is relatively high, which increases the hardness of the material, makes the material brittle, and reduces the toughness; secondly, diisocyanate has weak heat stability, which accelerates the degradation of the polymer during combustion and produces more low-molecular-weight substances, thereby causing molten droplets and secondary combustion; furthermore, since diisocyanate causes the cross-linking network to be denser, it limits the free movement and reaction of the self-healing polymer, which greatly reduces the self-repair rate of comparative example 3.

[0068] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A flame retardant and impact resistant modified silicone oil polyurethane coating, characterized in that: The invention comprises the following components in parts by weight: 100 parts of polyurethane emulsion, 25-35 parts of modified polydimethylsiloxane, 0.5-1 parts of dispersant and 5-15 parts of pigment and filler.

2. The flame retardant and impact resistant modified silicone oil polyurethane coating according to claim 1, characterized in that: The preparation method of the modified polydimethylsiloxane comprises: adding an organic solvent, polydimethylsiloxane and triphenyl phosphate into a reaction kettle under an inert gas atmosphere, stirring evenly, then adding an amino catalyst into the reaction system, heating the reaction system to 60-80°C, keeping the temperature constant, continuously stirring, the reaction time is 2-3 hours, and the reaction is completed to obtain the initial modified polydimethylsiloxane; adding a self-healing polymer and a cross-linking agent diethoxyisocyanate phosphinate into the initial modified polydimethylsiloxane, stirring evenly, and continuing to maintain the system temperature at 60-80°C for reaction to obtain the modified polydimethylsiloxane; the self-healing polymer is a polymer prepared by Diels-Alder reaction using cis-1,3-butadiene and maleic anhydride as raw materials.

3. The flame retardant and impact resistant modified silicone oil polyurethane coating according to claim 2, characterized in that: The mass ratio of the polydimethylsiloxane to triphenyl phosphate is 20:(3-5); the amount of the amino catalyst is 0.4-0.8% of the total mass of the polydimethylsiloxane and triphenyl phosphate.

4. The flame retardant and impact resistant modified silicone oil polyurethane coating according to claim 2, characterized in that: The mass ratio of the self-healing polymer to the primary modified polydimethylsiloxane is 2:(3-5); the amount of the cross-linking agent diethoxy phosphinothric isocyanate is 5-10% of the total mass of the self-healing polymer and the primary modified polydimethylsiloxane.

5. The flame retardant and impact resistant modified silicone oil polyurethane coating according to claim 2, characterized in that: The amino catalyst is triethylamine.

6. The flame retardant and impact resistant modified silicone oil polyurethane coating according to claim 2, characterized in that: The preparation method of the self-healing polymer comprises: under the protection of an inert gas, adding an organic solvent into a reaction kettle, then adding cis-1,3-butadiene and maleic anhydride into the reaction kettle, mixing evenly, then adding an amino catalyst, then heating the reaction kettle to 65-80° C., while continuously stirring, reacting for 2-3 hours, and obtaining a self-healing polymer after the reaction is completed.

7. The flame retardant and impact resistant modified silicone oil polyurethane coating according to claim 6, characterized in that: The molar ratio of cis-1,3-butadiene to maleic anhydride is 1:1; the amount of the catalyst used is 0.2-0.5% of the total mass of cis-1,3-butadiene and maleic anhydride.

8. The flame retardant and impact resistant modified silicone oil polyurethane coating according to claim 6, characterized in that: The amino catalyst is triethylamine.

9. The flame retardant and impact resistant modified silicone oil polyurethane coating according to claim 1, characterized in that: The dispersant is potassium polyacrylate or sodium polyacrylate; the pigment filler is at least one of quartz powder, titanium dioxide, talcum powder or calcium carbonate.

10. The method for preparing the flame retardant and impact resistant modified silicone oil polyurethane coating according to any one of claims 1 to 9, characterized in that: include: The polyurethane emulsion and modified polydimethylsiloxane are mixed, and then a dispersant and a pigment and filler are added, mixed, and then degassed to obtain a polyurethane coating.