Modified organic silicon resin as well as preparation method and application thereof

Abstract

The invention discloses modified organic silicon resin as well as a preparation method and application thereof. The preparation method comprises the following steps: carrying out a chain extension reaction on organic silicon resin and a chain extender, adding a cross-linking agent, carrying out a cross-linking reaction, carrying out the chain extension reaction on the organic silicon resin through amino silane in the first step, and introducing allophanate through the cross-linking reaction in the second step to prepare the modified organic silicon resin. The modified organic silicon resin provided by the invention is used for preparing a high-temperature-resistant coating, not only can meet the requirement of high-temperature-resistant protection performance, but also has excellent performances such as high drying speed, relatively high viscosity, good flexibility, good adhesive force and sagging resistance.

Description

Technical Field

[0001] The invention relates to the technical field of organosilicon high temperature resistant coatings, and in particular to a modified organosilicon resin and a preparation method and application thereof. Background Art

[0002] The main chain of silicone resin molecules contains a large amount of -Si-O-Si-inorganic structures. Compared with organic resins with carbon chains as skeletons (the bond energy of Si-O bonds is as high as 452 kJ / mol, much higher than C-C bonds (347 kJ / mol) and C-O bonds (351kJ / mol), the main chain of silicone resins is more stable. After the side groups are thermally oxidized and decomposed, the silicone resin forms a highly cross-linked and more stable spatial network structure, which can prevent further breakage of the main chain. Therefore, silicone resin has the characteristics of good thermal stability, high thermal decomposition temperature, and excellent weather resistance. It can be used as a high-temperature resistant coating film-forming material and is widely used in the protection of high-temperature furnace outer walls, turbine blades, automobile exhaust pipes, air heat exchanger surfaces, jet engine tail nozzles and other fields.

[0003] The side chains of silicone resin contain a large number of methyl and phenyl groups. The increase in the content of phenyl groups is conducive to the improvement of properties such as temperature resistance, mechanical properties, adhesion, and gloss. However, the electronegativity of methyl and phenyl groups is low, the intermolecular force is low, and the resin viscosity is low. The coating prepared with them dries slowly, is easy to settle, and sags. Low electronegativity can also lead to poor adhesion of the coating to the substrate and poor flexibility of the paint film.

[0004] Therefore, in recent years, researchers have carried out a lot of research and development work in the direction of silicone resin coatings. For example, the patent "Preparation and Use Method of a Silicone-Polyurea Self-Layering Coating" (CN107298930A) aims at the problem of poor interlayer adhesion and low construction efficiency caused by multi-layer construction of the protective coating on the exterior of concrete buildings. A two-component protective coating is prepared by using a silicone-modified polyurethane curing agent component and a silicone resin component. The silicone resin component and the polyurea matrix material form a gradual "transition layer" during the coating curing process to obtain a silicone-polyurea self-layering protective coating with excellent base adhesion and comprehensive weather resistance; the patent "A Composite Silicone Resin and High-Temperature Resistant Coating" (CN112358617A) adds an alkoxy coupling agent monomer containing epoxy, polyester, and acrylic groups to co-hydrolyze and condense with an alkoxysilane monomer during the synthesis of the silicone resin to form a high-temperature resistant composite silicone resin with Si-O-Si bonds as the main component and flexible segments as the auxiliary component. In the sol-gel process, an inorganic nanosol is also added for doping to form a honeycomb protective structure to improve the resin's high-temperature resistance. Performance; Patent "A Silicone Modified PAE Polyurea Coating" (CN113861816A), by introducing polysiloxane groups on the side chains of polyaspartic acid ester and isocyanate curing agent, a PAE polyurea coating with good leveling, high corrosion resistance, high temperature resistance and high coating strength is obtained; Patent "A Preparation Method of Silicone Modified Polyurea" (CN114276508A), by prepolymerizing polyaspartic acid ester and isocyanate monomer and then adding amino coupling agent to modify hydroxy silicone oil, the obtained The silicone-polyurea composite material effectively improves its adhesion to base surfaces such as cement mortar and concrete; the patent "A silicone-modified polyurea polyurethane antifouling coating and its preparation method and application" (CN118240463A) is composed of isocyanate-terminated polysiloxane reacted with 4,4'-dihydroxydiphenyl disulfide and diacetyl oxime in sequence and then added with tannic acid. The coating has excellent mechanical properties and static antifouling ability, and has high bonding strength, and has good application prospects in the field of marine antifouling.

[0005] It can be seen from the above-disclosed patents that the current polyurea-modified silicone resin is mainly a two-component coating system prepared with polyaspartic acid ester and hydroxy silicone oil as raw materials. The two-component coating needs to be proportioned when used, and the construction steps are complicated. In addition, the existing technology does not have a systematic solution to improve the comprehensive performance of silicone resins such as low viscosity, slow drying, poor flexibility, and poor adhesion. Summary of the invention

[0006] The main purpose of the present invention is to provide a modified silicone resin and a preparation method and application thereof, so as to overcome the deficiencies in the prior art.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes: One aspect of the present invention provides a method for preparing a modified silicone resin, which comprises: firstly subjecting the silicone resin to a chain extension reaction with a chain extender, and then adding a crosslinking agent to carry out a crosslinking reaction to obtain the modified silicone resin.

[0008] Another aspect of the present invention provides a modified silicone resin prepared by the above preparation method.

[0009] Another aspect of the present invention also provides the use of the aforementioned modified silicone resin in the field of coatings.

[0010] Compared with the prior art, the technical solution of the present invention has at least the following advantages: The preparation method provided by the present invention firstly carries out a chain extension reaction between aminosilane and silicone resin in the first step, and then introduces allophanate through a second step cross-linking reaction to obtain a modified silicone resin, which comprehensively solves the problems of poor construction performance of silicone resin in coatings, such as low viscosity, poor adhesion, poor flexibility, slow drying speed, easy sagging, etc.; and further reduces the activity of the amino group by adding an additive to react with the amino group, thereby effectively improving product quality and stability between batches. DETAILED DESCRIPTION

[0011] The present invention will be more fully understood by reading the following specific embodiments. However, it should be understood that the specific embodiments disclosed below are only exemplary of the present invention, and the present invention can be embodied in various forms. Therefore, the specific functional details disclosed herein should not be interpreted as limiting, but only as the basis for the claims and as a representative basis for teaching those skilled in the art to adopt the present invention in different ways in any appropriate detailed embodiment.

[0012] As one aspect of the technical solution of the present invention, a method for preparing a modified silicone resin involves: firstly subjecting the silicone resin to a chain extension reaction with a chain extender, and then adding a crosslinking agent to conduct a crosslinking reaction to obtain the modified silicone resin.

[0013] In some embodiments, the preparation method includes: first mixing the silicone resin with a first solvent, heating, adding a chain extender, performing a chain extension reaction, then adding a crosslinking agent and, optionally, adding or not adding a second solvent, performing a crosslinking reaction to obtain a modified silicone resin.

[0014] In some preferred embodiments, the mass ratio of the combination of the silicone resin, the chain extender, the crosslinking agent, the first solvent and the second solvent is (20-50): (1-25): (1-10): (30-80).

[0015] In some preferred embodiments, the silicone resin includes but is not limited to any one of methylphenyl silicone resin and polydimethylsiloxane resin or a combination of both.

[0016] In some more preferred embodiments, the methylphenyl silicone resin is prepared by mixing methylphenyldichlorosilane, dimethyldichlorosilane, diphenyldichlorosilane and water.

[0017] In some preferred embodiments, the first solvent includes but is not limited to any one of methanol, ethanol, isopropanol, n-butanol, propylene glycol methyl ether, ethylene glycol monobutyl ether, benzene, toluene, xylene, trimethylbenzene, tetramethylbenzene, acetone, butanone, cyclohexanone, methyl isobutyl ketone, ethyl acetate, butyl acetate, and propylene glycol methyl ether acetate, or a combination of two or more thereof.

[0018] In some preferred embodiments, the second solvent includes but is not limited to any one of methanol, ethanol, isopropanol, n-butanol, propylene glycol methyl ether, ethylene glycol monobutyl ether, benzene, toluene, xylene, trimethylbenzene, tetramethylbenzene, acetone, butanone, cyclohexanone, methyl isobutyl ketone, ethyl acetate, butyl acetate, and propylene glycol methyl ether acetate, or a combination of two or more thereof.

[0019] In some preferred embodiments, the chain extender includes but is not limited to any one of 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(piperazinylethyl)-3-aminopropylmethyldimethoxysilane, 3-diethylenetriaminopropylmethyldimethoxysilane, N-(piperazinylethyl)-3-aminopropylmethyldiethoxysilane, or a combination of two or more thereof.

[0020] In some preferred embodiments, the preparation method further comprises: while adding the chain extender, selectively adding or not adding a first additive, wherein the first additive includes but is not limited to benzoic acid, formic acid, acetic acid, propionic acid, butyric acid, lauric acid, tert-butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, butyl glycidyl ether, C12, C14 glycidyl ether, diethyl maleate, butyl maleate, acrylonitrile, any one or a combination of two or more thereof.

[0021] In some more preferred embodiments, the mass ratio of the first additive to the chain extender is 0.5-2:1.

[0022] In the preparation process of the present invention, since the amine group has a relatively high activity and is difficult to control the reaction with isocyanate, the activity of the amine group is reduced by adding a first additive to react with the amine group. For example, benzoic acid, formic acid, butyric acid, lauric acid, etc. react with the primary amine group in N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane or N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane to undergo an amidation reaction to reduce the trifunctional amine to a monofunctional amine, while reducing the reactivity of the amine group to avoid gelation; for example, tert-butyl carbonate, benzyl glycidyl ether, etc. reduce the functionality and activity of the amine group through a ring-opening polymerization reaction with the amine group; for another example, diethyl maleate, dibutyl maleate, acrylonitrile, etc. reduce the functionality and reactivity of the amine group through a Michael addition reaction.

[0023] In some preferred embodiments, the cross-linking agent includes but is not limited to any one of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate, or a combination of two or more thereof.

[0024] In some preferred embodiments, the preparation method further comprises: selectively adding or not adding a second additive while adding the crosslinking agent, wherein the second additive includes but is not limited to any one or a combination of two or more of bismuth neodecanoate, bismuth cyclohexanoate, and bismuth isooctanoate. The molecular weight of the resin is further increased through the complexation reaction between the amine group and bismuth, the drying speed of the coating is increased, and the flexibility of the coating is improved.

[0025] In some more preferred embodiments, the mass ratio of the second additive to the chain extender is 0.5-2:1.

[0026] In some preferred embodiments, the preparation method comprises: mixing the organic silicone resin with a first solvent, heating to 40-130° C. under stirring, adding a chain extender, and performing the chain extension reaction.

[0027] In some more preferred embodiments, the temperature of the chain extension reaction is 80-160° C., and the time of the chain extension reaction is 0.5-5 h.

[0028] In some preferred embodiments, the preparation method comprises: after the chain extension reaction is completed, cooling to 30-80° C., adding a second solvent and a crosslinking agent, and performing the crosslinking reaction to obtain the modified silicone resin.

[0029] In some more preferred embodiments, the temperature of the cross-linking reaction is 30-100° C., and the time of the cross-linking reaction is 0.5-5 h.

[0030] In some more preferred embodiments, the cross-linking agent is added dropwise; further, the cross-linking agent is added dropwise within 0.5 h to 5 h.

[0031] In some more specific embodiments, the preparation method of the modified silicone resin includes the following steps: adding the silicone resin and the first solvent into a reaction container, heating to 40-130°C while stirring, adding a chain extender after the temperature stabilizes and keeping warm at 80-160°C for 0.5-5 hours to carry out the chain extension reaction, cooling to 30-80°C after the chain extension reaction is completed, adding the second solvent, and starting to drip the crosslinking agent for 0.5-5 hours after the temperature stabilizes, and keeping warm at 30-100°C for 0.5-5 hours after the dripping is completed to carry out the crosslinking reaction to obtain the modified silicone resin.

[0032] As another aspect of the technical solution of the present invention, it relates to a modified silicone resin prepared by the aforementioned preparation method.

[0033] As another aspect of the technical solution of the present invention, it also involves the application of the aforementioned modified silicone resin in the field of coatings.

[0034] In some embodiments, the coating includes, but is not limited to, a high temperature resistant coating.

[0035] It should be noted that the preparation method of the modified silicone resin provided by the present invention is mainly based on a two-step reaction: the first step is the chain extension reaction of the silicone resin through aminosilane. The chain extension reaction of aminosilane can increase the molecular weight of the silicone resin, improve the drying speed and flexibility of the resin, and introduce amino functional groups on the other hand to provide raw materials for the subsequent formation of allophanate; the second step is to introduce allophanate to improve the adhesion and construction performance of the resin.

[0036] Furthermore, in some embodiments, because the amine group is multifunctional, there is a risk of gelation during the reaction with the crosslinking agent isocyanate, which affects the stability of product quality; and the multifunctional amine group and the multifunctional isocyanate crosslink in different ways, which is manifested in different viscosities and properties between product batches, affecting the stability between product batches. In order to ensure process controllability and product quality stability, the present invention adds a first additive to react with the amine group in the chain extender, such as the addition reaction of epoxy and amine group, the Michael addition reaction of vinyl and amine group, and the amidation reaction of carboxylic acid and amine group, thereby reducing the activity of the amine group and improving product quality and stability between batches.

[0037] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The reagents and raw materials used in the following examples are commercially available, and the experimental methods without specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturers.

[0038] Example 1 Weigh 20 parts of methylphenyl silicone resin and 78 parts of toluene by mass and add them into a reaction container. Heat to 40°C while stirring. After the temperature stabilizes, add 1 part of N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, keep warm at 80°C for 0.5 hour, cool to 30°C, and after the temperature stabilizes, start to drop 1 part of hexamethylene diisocyanate for 0.5 hour. After the addition is completed, keep warm at 30°C for 0.5 hour to obtain a modified silicone resin.

[0039] Example 2 Weigh 50 parts of methylphenyl silicone resin and 20 parts of xylene by mass and add them into a reaction container. Heat to 100°C while stirring. After the temperature stabilizes, add 10 parts of 3-aminopropylmethyldimethoxysilane and keep warm at 160°C for 5 hours. Cool to 80°C, add 10 parts of n-butanol as solvent, and after the temperature stabilizes, start to add 5 parts of toluene diisocyanate dropwise over 5 hours. After the addition is completed, keep warm at 100°C for 5 hours to obtain a modified silicone resin.

[0040] Example 3 Weigh 5 parts of methylphenyldichlorosilane, 10 parts of dimethyldichlorosilane, 15 parts of diphenyldichlorosilane, 10 parts of water and 20 parts of xylene by mass and add them into a reaction container. Heat to 100°C while stirring. After the temperature stabilizes, add 10 parts of 3-aminopropylmethyldiethoxysilane and 10 parts of tert-butyl carbonate. Keep the temperature at 130°C for 5 hours, cool to 80°C, add 10 parts of n-butanol as a solvent, and start to add 10 parts of hexamethylene diisocyanate dropwise after the temperature stabilizes. After the addition is completed, keep the temperature at 70°C for 2 hours to obtain a modified silicone resin.

[0041] Example 4 Weigh 5 parts of methylphenyldichlorosilane, 10 parts of dimethyldichlorosilane, 11 parts of diphenyldichlorosilane, 10 parts of water and 20 parts of propylene glycol methyl ether acetate by mass and add them into a reaction container. Heat to 100°C while stirring. After the temperature stabilizes, add 22 parts of N-(piperazineethyl)-3-aminopropylmethyldiethoxysilane and 11 parts of butyl glycidyl ether. Keep the temperature at 120°C for 5 hours, cool to 80°C, add 10 parts of trimethylbenzene as a solvent, and start to add 3 parts of hexamethylene diisocyanate and 11 parts of bismuth neodecanoate dropwise after the temperature stabilizes. The addition is completed within 5 hours. After the addition is completed, keep the temperature at 60°C for 3 hours to obtain a modified silicone resin.

[0042] Example 5 Weigh 30 parts of methylphenyl silicone resin and 47 parts of xylene by mass and add them into a reaction container. Heat to 130°C while stirring. After the temperature stabilizes, add 10 parts of N-(piperazineethyl)-3-aminopropylmethyldiethoxysilane. Keep warm at 120°C for 3 hours. Cool to 40°C, add 10 parts of trimethylolbenzene as solvent. After the temperature stabilizes, start to add 3 parts of diphenylmethane diisocyanate dropwise. The addition is completed in 1 hour. After the addition is completed, keep warm at 60°C for 1 hour to obtain a modified silicone resin.

[0043] Comparative Example 1 Compared with Example 1, the difference is that the cross-linking agent hexamethylene diisocyanate is not added.

[0044] Comparative Example 2 Compared with Example 1, the difference is that the chain extender N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane is not added.

[0045] Comparative Example 3 Compared with Example 1, the difference is that hexamethylene diisocyanate trimer (HDI trimer) is selected as the cross-linking agent.

[0046] Comparative Example 4 Compared with Example 1, the difference is that 3-glycidyloxypropylmethyldimethoxysilane is selected as the chain extender.

[0047] The modified silicone resin obtained in Examples 1-5, the silicone resin obtained in Comparative Examples 1-4 and a competing silicone resin on the market were used to prepare high temperature resistant coatings, respectively. The reference formula is shown in Table 1:

[0048] The high temperature resistant coatings prepared by the modified silicone resin obtained in Examples 1-5, the silicone resin obtained in Comparative Examples 1-4 and the silicone resistant resin competitor on the market were subjected to comparative tests under the same conditions. The test performance data are shown in Tables 2 and 3.

[0049]

[0050]

[0051] From the comparative data of Table 2 and Table 3, it can be seen that the high temperature resistant coatings prepared from the modified silicone resins of Examples 1-5 of the present invention can meet the requirements of 650°C*5 hours high temperature protection performance, and have excellent construction performance, fast drying speed, high viscosity, good flexibility, good adhesion, anti-sagging and other characteristics, and have obvious comprehensive performance advantages.

[0052] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0053] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a modified silicone resin, characterized in that: The method comprises: firstly making the organic silicon resin and the chain extender carry out chain extension reaction, then adding the cross-linking agent to carry out cross-linking reaction, and preparing the modified organic silicon resin.

2. The preparation method according to claim 1, characterized in that: The method comprises: firstly mixing the organic silicon resin with a first solvent, heating, adding a chain extender, carrying out a chain extension reaction, then adding a crosslinking agent and selectively adding or not adding a second solvent, carrying out a crosslinking reaction, and preparing the modified organic silicon resin.

3. The preparation method according to claim 2, characterized in that: The mass ratio of the combination of the silicone resin, the chain extender, the cross-linking agent, the first solvent and the second solvent is (20-50): (1-25): (1-10): (30-80).

4. The preparation method according to claim 2, characterized in that: The organic silicon resin includes any one of methylphenyl organic silicon resin and polydimethylsiloxane resin or a combination of the two; Preferably, the methylphenyl silicone resin is prepared by mixing methylphenyldichlorosilane, dimethyldichlorosilane, diphenyldichlorosilane and water; And / or, the first solvent includes any one of methanol, ethanol, isopropanol, n-butanol, propylene glycol methyl ether, ethylene glycol monobutyl ether, benzene, toluene, xylene, trimethylbenzene, tetramethylbenzene, acetone, butanone, cyclohexanone, methyl isobutyl ketone, ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, or a combination of two or more thereof; And / or, the second solvent includes any one or a combination of two or more of methanol, ethanol, isopropanol, n-butanol, propylene glycol methyl ether, ethylene glycol monobutyl ether, benzene, toluene, xylene, trimethylbenzene, tetramethylbenzene, acetone, butanone, cyclohexanone, methyl isobutyl ketone, ethyl acetate, butyl acetate, and propylene glycol methyl ether acetate.

5. The preparation method according to claim 2, characterized in that: The chain extender includes any one of 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(piperazinylethyl)-3-aminopropylmethyldimethoxysilane, 3-diethylenetriaminopropylmethyldimethoxysilane, N-(piperazinylethyl)-3-aminopropylmethyldiethoxysilane, and 3-diethylenetriaminopropylmethyldiethoxysilane, or a combination of two or more thereof; And / or, the preparation method further comprises: while adding the chain extender, selectively adding or not adding a first additive, wherein the first additive comprises any one or a combination of two or more of benzoic acid, formic acid, acetic acid, propionic acid, butyric acid, lauric acid, tert-butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, butyl glycidyl ether, C12, C14 glycidyl ether, diethyl maleate, butyl maleate, and acrylonitrile; Preferably, the mass ratio of the first additive to the chain extender is 0.5-2:

1.

6. The preparation method according to claim 2, characterized in that: The cross-linking agent includes any one or a combination of two or more of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate; And / or, the preparation method further comprises: while adding the cross-linking agent, selectively adding or not adding a second additive, wherein the second additive comprises any one or a combination of two or more of bismuth neodecanoate, bismuth cyclohexanoate, and bismuth isooctanoate; Preferably, the mass ratio of the second additive to the chain extender is 0.5-2:

1.

7. The preparation method according to claim 2, characterized in that: include: The organic silicone resin is mixed with the first solvent, heated to 40-130° C. under stirring, and a chain extender is added to carry out the chain extension reaction; Preferably, the temperature of the chain extension reaction is 80-160° C., and the time of the chain extension reaction is 0.5-5 h.

8. The preparation method according to claim 2, characterized in that: include: After the chain extension reaction is completed, the temperature is lowered to 30-80° C., a second solvent and a cross-linking agent are added, and the cross-linking reaction is carried out to obtain the modified silicone resin; Preferably, the temperature of the cross-linking reaction is 30-100°C, and the time of the cross-linking reaction is 0.5-5h; Preferably, the cross-linking agent is added dropwise, and preferably the addition of the cross-linking agent is completed within 0.5 h to 5 h.

9. The modified silicone resin prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the modified silicone resin according to claim 9 in the field of coatings; preferably, the coating comprises a high temperature resistant coating.

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