Trapezoidal methyl silicone resin and preparation method thereof

Abstract

The invention relates to the technical field of organic silicon resin preparation, in particular to trapezoidal methyl silicon resin and a preparation method thereof.The trapezoidal methyl silicon resin is prepared by taking methyl trichlorosilane as a main raw material, introducing a trapezoidal control agent containing amido and alkoxy at the same time to inhibit the reaction activity of the methyl trichlorosilane and then carrying out hydrolysis reaction in a small amount of alcohol solvent and water; the generation of a cross-linked network structure insoluble substance during hydrolysis is avoided, and the resin gelation risk is effectively reduced. The hydrolysis rate is reduced, so that the use amount of the solvent is reduced, the proportion of alcohol in the water phase is greatly reduced, and the process and environmental protection cost is reduced. The trapezoidal methyl silicone resin prepared by the method is excellent in viscosity performance, high in yield, excellent in boiling resistance, short in curing time, high in resin softening point and short in gelation time.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of organic silicon resins, and in particular to a ladder-shaped methyl silicon resin and a preparation method thereof. Background Art

[0002] Methyltrichlorosilane can be used to prepare ladder methyl silicone resin, also called ladder polymethyl silsesquioxane, through hydrolysis-condensation. This resin is a thermosetting polymer material with Si-O-Si bond as the main chain and organic groups attached to Si atoms. Because there is only one methyl group attached to the Si atom of methyltrichlorosilane, it is the ladder silicone resin with the lowest carbon content. It has better heat resistance, electrical insulation, hydrophobicity, flame retardancy, etc., so it is widely used in defense, aerospace, electrical insulation and other fields as insulating paint, mica board adhesive, laminating coating, high temperature resistant coating, etc.

[0003] At present, there are three main preparation processes for trapezoidal methyl silicone resin:

[0004] (1) Using methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane or phenyltrimethoxysilane as raw materials, hydrolysis-condensation is carried out under acid or base catalysis to obtain trapezoidal methyl silicone resin. This process route has mild reaction conditions, controllable process, narrow resin molecular weight distribution, and less wastewater. However, alkoxy residues are prone to appear in the resin network, affecting the performance. In addition, the cost of raw materials is high, so it is rarely used in industrial production.

[0005] (2) It is prepared by hydrolysis reaction with methyltrichlorosilane as raw material and toluene, butanol and a large amount of water as solvent. Methyltrichlorosilane is very susceptible to attack by nucleophilic reagents and its hydrolysis is very violent. The chlorine atom of methyltrichlorosilane quickly combines with the hydrogen atom in water to form hydrogen chloride, while the oxygen atom and another hydrogen atom in water can combine with the silicon atom in methyltrichlorosilane to form silanol. At the same time, hydrogen chloride dissolves in water and releases a large amount of heat. The silanol further dehydrates under high temperature and strong acid environment, and the silanol will cross-link to form a network structure insoluble substance, which loses its use value.

[0006] This process produces dozens of times more wastewater per ton of methyl silicone resin, and the wastewater contains a large amount of butanol and a small amount of toluene, which is very polluting to the environment. Due to the introduction of too many butoxy groups, the volume of the resin shrinks greatly at high temperatures, which easily leads to problems such as brittle and peeling paint films.

[0007] In view of the above technical difficulties, people have conducted in-depth research from the perspective of formulation and process. For example, the U.S. Patent (publication number is US2398672) uses dimethyldichlorosilane, methyltrichlorosilane, and tetrachlorosilane to co-hydrolyze and condense in n-butanol and toluene solvent to obtain a glass fiber composite silicone resin. The use of a large amount of dimethyldichlorosilane reduces the functionality of the hydrolysis reaction and also reduces the risk of gelation in the synthesis process. However, the dimethyldichlorosilane is easily hydrolyzed into a ring, which affects the resin yield and also increases the difficulty of wastewater treatment.

[0008] For example, the US patent (publication number US 3435001) uses methyltrichlorosilane to hydrolyze in toluene solvent to obtain a trapezoidal methyl silicone resin. In the process, hydrophilic solid particles (such as fumed silica and diatomaceous earth) are used to make a paste to reduce the mass transfer efficiency, thereby reducing the risk of gelation during the synthesis process. After the reaction is completed, the solid particles are filtered and separated, which increases the process cost and the amount of solid hazardous waste.

[0009] For example, Xie Zujun, He Zhiqun and others from the Institute of Chemistry of the Chinese Academy of Sciences disclosed a high-temperature resistant trapezoidal polymethyl silicone resin coating, which uses methyltrichlorosilane as the main raw material and uses ethylenediamine to control the reactivity of the methyltrichlorosilane functional group, making it difficult to crosslink and difficult to form gel during condensation. However, acetone is introduced as the second solvent in this technical solution, and the amount of ethylenediamine used is too much, which affects the recovery of acid water.

[0010] (3) Using methyltrichlorosilane and dimethyldichlorosilane as raw materials, toluene and a large amount of water as solvents, the number of chlorosilane functional groups is reduced to achieve the purpose of reducing the risk of gelation. However, the D segment introduced by dimethyldichlorosilane will reduce the product performance, resulting in a lower softening point after the resin is cured, which is not conducive to the formation of a solid resin with good storage stability. In addition, this resin has a long gelation time and low curing activity. Summary of the invention

[0011] In order to overcome the above technical problems, the present invention provides a method for preparing a trapezoidal methyl silicone resin with low gel risk and low environmental cost. The trapezoidal methyl silicone resin prepared by the method has excellent viscosity performance, high yield, excellent water boiling resistance, short curing time, high resin softening point and short gelation time.

[0012] The technical solutions to the above technical problems are as follows:

[0013] A ladder-shaped methyl silicone resin is prepared by using a small molecule monomer containing both an amino group and an alkoxy group as a ladder control agent;

[0014] The trapezoidal methyl silicone resin comprises, by weight:

[0015] 15 parts of methyltrichlorosilane, 5-12 parts of ladder control agent, 25-75 parts of water, 60-100 parts of solvent A, 2-30 parts of solvent B, and 0.03-0.06 parts of catalyst;

[0016] The ladder control agent structure is NR X H 3-X , wherein R is any one of methoxy, ethoxy or butoxy; X is 1, 2 or 3;

[0017] Wherein solvent A is any one of toluene, xylene, methylcyclohexane, and ethylcyclohexane;

[0018] Solvent B is any one of methanol, ethanol, isopropanol, and n-butanol;

[0019] The catalyst is any one of zinc octoate and zinc naphthenate.

[0020] Furthermore, the ladder control agent is any one of ethanolamine, diethanolamine, triethanolamine, butanolamine, dibutanolamine, and tributanolamine.

[0021] Another object of the present invention is to provide a method for preparing the ladder-shaped methyl silicone resin, comprising the following steps:

[0022] S1: According to the formula, methyltrichlorosilane and part of solvent A are put into the first reaction container, the system temperature is controlled to be 5-10°C, and the mixture is evenly mixed. Then, a trapezoidal control agent is added dropwise to the first reaction container for 1-2 hours. During the addition, the reaction temperature is controlled to be 10-15°C. The amino groups contained in the trapezoidal control agent and part of the Si-Cl bonds in methyltrichlorosilane undergo an affinity substitution-elimination synergistic reaction in a non-polar solvent to obtain a compound shown in formula I. The synthetic reaction formula is as follows:

[0023]

[0024] S2: Add the remaining solvent A, water and solvent B into the second reaction container, control the system temperature to 10-15°C, mix well, and then dropwise add the compound of formula I obtained in step S1 into the second reaction container for 2 hours. During the dropwise addition, control the reaction temperature to 15-20°C. After the dropwise addition is completed, control the system temperature to 20±2°C, perform the hydrolysis reaction for 2 hours, and then let stand for stratification and take the supernatant as the compound of formula II.

[0025] The reduced activity methyltrichlorosilane undergoes hydrolysis and alcoholysis reaction with water and alcohol in a non-polar solvent and alcohol environment to generate small molecular silanol. The synthesis reaction formula is as follows:

[0026]

[0027] S3: washing the compound of formula II obtained in step S2 with water until it is neutral, then filtering it through anhydrous magnesium sulfate to remove water, concentrating the filtered oil layer to a solid content of 40-60%, adding a catalyst, heating and refluxing for polycondensation reaction for 4-5 hours, then cooling and filtering to obtain the polycondensation product, ladder-shaped methyl silicone resin;

[0028] Small molecular silanol undergoes self-condensation reaction under acidic conditions, and the silanol groups condense and dehydrate to form an organosilicon prepolymer, with an initial increase in molecular weight. The organosilicon prepolymer condenses at high temperature to form a trapezoidal methyl silicone resin; the synthesis reaction formula is as follows:

[0029]

[0030] The beneficial effects of the present invention are:

[0031] The present invention uses methyltrichlorosilane as the main raw material, and introduces a ladder control agent containing both an amine group and an alkoxy group to suppress the reactivity of methyltrichlorosilane, because the amine group in the ladder control agent and part of the Si-Cl bonds in the methyltrichlorosilane undergo an affinity substitution-elimination synergistic reaction in a non-polar solvent, which reduces the activity of methyltrichlorosilane, and then undergoes a hydrolysis reaction in a small amount of alcohol solvent and water, the hydrolysis rate is reduced, and the generation of cross-linked network structure insolubles during hydrolysis is avoided, so that the reaction becomes controllable. During the hydrolysis reaction, a small amount of small molecular alcohol in the water phase undergoes alcoholysis, which effectively reduces the risk of resin gelation.

[0032] Due to the reduced hydrolysis rate, the amount of alcohol co-solvents can be greatly reduced, which greatly reduces the organic matter in the water phase. The benefits of this are: it not only reduces the amount of solvent used, but also greatly reduces the proportion of alcohol in the water phase, reducing process and environmental costs.

[0033] In step S3 of the present invention, the hydroxyl groups of the compound shown in formula II are prone to polycondensation reaction, the crosslinking density of the resin is increased, the molecular weight of the resin is increased, and the water boiling performance of the resin is improved. The trapezoidal methyl silicone resin prepared by the present invention has excellent viscosity performance, high yield, excellent water boiling resistance, short curing time, high resin softening point, and short gelation time.

[0034] The present invention is further described in detail below in conjunction with specific implementation modes. DETAILED DESCRIPTION

[0035] Embodiment 1:

[0036] S1: 150 g of methyltrichlorosilane and 600 g of toluene are placed in a first reaction container, the system temperature is controlled to be 5-10° C., and the mixture is evenly mixed. Then 50 g of ethanolamine is added dropwise to the first reaction container for 1-2 hours. During the addition, the reaction temperature is controlled to be 10-15° C., and an affinity substitution-elimination synergistic reaction occurs between the amino group contained in the ladder control agent and part of the Si-Cl bonds in the methyltrichlorosilane in a non-polar solvent to obtain a compound shown in Formula I.

[0037] S2: Add 100g toluene, 750g water and 300g anhydrous ethanol into the second reaction container, control the system temperature to 10-15°C, mix evenly, and then drop the compound of formula I obtained in step S1 into the second reaction container for 2h. During the dropping process, control the reaction temperature to 15-20°C; after the dropping is completed, control the system temperature to 20±2°C, hydrolyze for 2h, and then let stand for stratification and take the supernatant as the compound of formula II.

[0038] S3: The compound of formula II obtained in step S2 is washed with water until it is neutral, and then filtered through anhydrous magnesium sulfate to remove water. The filtered oil layer is concentrated to a solid content of 50%, 0.45 g of zinc octoate is added, and the temperature is raised to reflux for polycondensation reaction for 4 to 5 hours, and then the temperature is lowered and filtered to obtain the polycondensation product, ladder-shaped methyl silicone resin.

[0039] Embodiment 2:

[0040] S1: Take 150g of methyltrichlorosilane and 600g of toluene and put them into the first reaction container, control the system temperature to 5-10°C, mix them evenly, and then add 75g of diethanolamine dropwise into the first reaction container for 1-2h. During the dropping process, control the reaction temperature to 10-15°C to obtain the compound shown in formula I.

[0041] S2: Add 200g toluene, 500g water and 260g anhydrous ethanol into the second reaction container, control the system temperature to 10-15°C, mix evenly, and then drop the compound of formula I obtained in step S1 into the second reaction container for 2h. During the dropping process, control the reaction temperature to 15-20°C; after the dropping is completed, control the system temperature to 20±2°C, hydrolyze for 2h, and then let stand for stratification and take the supernatant as the compound of formula II.

[0042] S3: The compound of formula II obtained in step S2 is washed with water until it is neutral, and then filtered through anhydrous magnesium sulfate to remove water, and the filtered oil layer is concentrated to a solid content of 60%, 0.5 g of zinc octoate is added, and the temperature is raised to reflux for condensation reaction for 4 to 5 hours, and then the temperature is lowered and filtered to obtain the condensation product, ladder-shaped methyl silicone resin.

[0043] Embodiment 3:

[0044] S1: Take 150g of methyltrichlorosilane and 600g of toluene and put them into the first reaction container, control the system temperature to 5-10°C, mix them evenly, and then add 100g of triethanolamine dropwise into the first reaction container for 1.5h. During the dropping process, control the reaction temperature to 10-15°C to obtain the compound shown in formula I.

[0045] S2: Add 200g toluene, 350g water and 200g anhydrous ethanol into the second reaction container, control the system temperature to 10-15°C, mix evenly, and then drop the compound of formula I obtained in step S1 into the second reaction container for 2h. During the dropping process, control the reaction temperature to 15-20°C; after the dropping is completed, control the system temperature to 20±2°C, hydrolyze for 2h, and then let stand for stratification and take the supernatant as the compound of formula II.

[0046] S3: The compound of formula II obtained in step S2 is washed with water until it is neutral, and then filtered through anhydrous magnesium sulfate to remove water. The filtered oil layer is concentrated to a solid content of 40%, 0.6 g of zinc octoate is added, and the temperature is raised to reflux for condensation reaction for 4 to 5 hours, and then the temperature is lowered and filtered to obtain the condensation product, ladder-shaped methyl silicone resin.

[0047] Embodiment 4:

[0048] S1: Take 150g of methyltrichlorosilane and 500g of ethylcyclohexane and put them into the first reaction container, control the system temperature to 5-10°C, mix them evenly, and then add 85g of butanolamine dropwise into the first reaction container for 1h. During the dropping process, control the reaction temperature to 10-15°C to obtain the compound shown in formula I.

[0049] S2: Add 200g of ethylcyclohexane, 600g of water and 120g of n-butanol into a second reaction container, control the system temperature to 10-15°C, mix evenly, and then drop the compound of formula I obtained in step S1 into the second reaction container for 2h. During the dropping process, control the reaction temperature to 15-20°C; after the dropping is completed, control the system temperature to 20±2°C, hydrolyze for 2h, and then let stand for stratification and take the supernatant as the compound of formula II.

[0050] S3: The compound of formula II obtained in step S2 is washed with water until it is neutral, and then filtered through anhydrous magnesium sulfate to remove water. The filtered oil layer is concentrated to a solid content of 40%, 0.45 g of zinc cyclohexaneate is added, and the temperature is raised to reflux for polycondensation reaction for 4 to 5 hours, and then the temperature is lowered and filtered to obtain the polycondensation product, ladder-shaped methyl silicone resin.

[0051] Embodiment 5:

[0052] S1: Take 150g of methyltrichlorosilane and 600g of methylcyclohexane and put them into the first reaction container, control the system temperature to 5-10°C, mix them evenly, and then add 120g of dibutanolamine dropwise into the first reaction container for 2h. During the dropping process, control the reaction temperature to 10-15°C to obtain the compound shown in formula I.

[0053] S2: Add 400g of methylcyclohexane, 400g of water and 90g of methanol into the second reaction container, control the system temperature to 10-15°C, mix evenly, and then drop the compound of formula I obtained in step S1 into the second reaction container for 2h. During the dropping process, control the reaction temperature to 15-20°C; after the dropping is completed, control the system temperature to 20±2°C, hydrolyze for 2h, and then let stand for stratification and take the supernatant as the compound of formula II.

[0054] S3: The compound of formula II obtained in step S2 is washed with water until it is neutral, and then filtered through anhydrous magnesium sulfate to remove water. The filtered oil layer is concentrated to a solid content of 50%, 0.35 g of zinc cyclohexaneate is added, and the temperature is raised to reflux for polycondensation reaction for 4 to 5 hours, and then the temperature is lowered and filtered to obtain the polycondensation product, ladder-shaped methyl silicone resin.

[0055] Embodiment 6:

[0056] S1: Take 150g of methyltrichlorosilane and 500g of xylene and put them into the first reaction container, control the system temperature to 5-10°C, mix them evenly, and then add 100g of tributanolamine dropwise into the first reaction container for 1h. During the dropping process, control the reaction temperature to 10-15°C to obtain the compound shown in formula I.

[0057] S2: Add 100g xylene, 250g water and 20g isopropanol into the second reaction container, control the system temperature to 10-15°C, mix evenly, and then drop the compound of formula I obtained in step S1 into the second reaction container for 2h. During the dropping process, control the reaction temperature to 15-20°C; after the dropping is completed, control the system temperature to 20±2°C, hydrolyze for 2h, and then let stand for stratification and take the supernatant as the compound of formula II.

[0058] S3: The compound of formula II obtained in step S2 is washed with water until it is neutral, and then filtered through anhydrous magnesium sulfate to remove water. The filtered oil layer is concentrated to a solid content of 60%, 0.3 g of zinc cyclohexaneate is added, and the temperature is raised to reflux for polycondensation reaction for 4 to 5 hours, and then the temperature is lowered and filtered to obtain the polycondensation product, ladder-shaped methyl silicone resin.

[0059] Comparative Example 1:

[0060] Take 150g of n-butanol, 200g of toluene and 1100g of water and put them into a reaction container, start stirring, control the system temperature to 5-10°C, mix evenly, then drop a mixture of 150g of methyltrichlorosilane and 500g of toluene into the reaction container, the dropping time is 2-3h, during the dropping process, control the reaction temperature to 15-20°C, keep the reaction at this temperature for 1h, then let it stand for stratification and take the upper clear liquid, wash the upper organic phase with water to neutrality, then filter it through anhydrous magnesium sulfate to remove water, concentrate the filtered oil layer to a solid content of 50%, add 0.3g of zinc cyclohexaneate, heat and reflux for condensation reaction for 4-5h, then cool and filter to obtain the condensation product ladder-shaped methyl silicone resin, whose molecular structure is as follows:

[0061]

[0062] The detection method is as follows:

[0063] 1. Viscosity: Dilute the sample with toluene to 50% solid content and measure it using a rotational viscometer at 25°C.

[0064] 2. Curing time: Add 10g of diluent and 0.05g of curing agent to 10g of 50% sample to prepare working solution. Apply working solution on a 10cm×10cm mica paper and soak it fully. Put the sample in a 230℃ oven to test its hardening time, which is determined as curing time.

[0065] 3. Boiling test: Boil the cured mica sheet in a 100°C water bath for 1 hour to observe whether it collapses or breaks apart.

[0066] 4. Synthesis yield: The ratio of the mass of trapezoidal methyl silicone resin obtained in each experiment to the theoretical resin yield is calculated as the yield.

[0067] 5. Acid water / resin finished product mass ratio: the ratio of the number of layered acid and water produced for every 1 part of resin produced.

[0068] 6. Softening point: Tested by water bath heating using the ring and ball method.

[0069] 7. Gel time: Take 0.25-0.5 g of resin sample, place it in a gel time meter at 200°C, stir and solidify, and test the time it takes for the sample to change from liquid to gel at 200°C.

[0070] The test results are shown in Table 1 below:

[0071] Table 1 Product performance test data of Examples 1 to 6 and Comparative Example 1

[0072]

[0073] It can be seen from the performance test data in Table 1 that under the same solvent type and solid content, the viscosity of the trapezoidal methyl silicone resin product prepared by the present invention is higher than that of the product prepared by the comparative method, indicating that the trapezoidal methyl silicone resin prepared by the method of the present invention has a larger molecular weight and a denser network structure. This is also consistent with the results of the water boiling test. The mica sheet obtained by impregnation and curing with the trapezoidal methyl silicone resin prepared in Comparative Example 1 has significantly weaker water boiling resistance than Examples 1 to 6. The present invention adopts a trapezoidal control agent to reduce the loss caused by weak gel, and the product yield can reach up to 98%, with obvious process economy.

[0074] The present invention adopts a ladder control agent containing both an amino group and an alkoxy group. The control agent has a stronger control effect on the activity of chlorosilane and does not require the use of other cosolvents such as acetone. When the methyl silicone resin is hydrolyzed, excessive silanol groups can be reacted. In addition, after the ladder control agent is added, the crosslinking density of the methyl silicone resin increases, which improves the water boiling resistance of the mica film. The curing reaction activity of the methyl silicone resin prepared by the ladder control agent with ethoxy groups in Examples 1 to 3 is higher than that of the methyl silicone resin prepared by the ladder control agent with butoxy groups in Examples 4 to 6. The resin has a larger molecular weight, a larger crosslinking density, a higher softening point, a shorter gelation time, and a better water boiling resistance. This is because the ladder control agent with butoxy groups has too strong an inhibitory effect of butoxy groups when chlorosilane is hydrolyzed, and the resin molecular weight is relatively small.

[0075] In contrast, the ladder-shaped methyl silicone resin prepared in Comparative Example 1 using a large amount of n-butanol has a low curing reaction activity due to the presence of a large amount of butoxy groups on the molecular network. It is difficult for the butoxy groups to react with the silanol groups during curing. Therefore, the obtained methyl silicone resin has a slow curing reaction, a long curing time, a small resin molecular weight, a low softening point, a low crosslinking density, a long gelation time, and poor water boiling resistance.

[0076] The trapezoidal methyl silicone resin prepared by the present invention does not contain butoxy groups on its molecular network. The addition of ethanol and the ethoxy groups on the trapezoidal control agent will cause the methyl silicone resin to carry some ethoxy groups, but its curing reaction activity is still higher than that of the butoxy groups. During curing, the ethoxy groups are more likely to react with the silanol groups. Therefore, the obtained methyl silicone resin has a faster curing reaction, a shorter curing time, a larger resin molecular weight, a higher softening point, a shorter gelation time, a larger crosslinking density, and better water boiling resistance.

[0077] More importantly, the acid water / resin finished product mass ratio of the trapezoidal methyl silicone resin prepared by the present invention is only 1 / 3 to 3 / 4 of that in comparative example 1. Therefore, the technical effect of the present invention is that the environmental pressure is small and the post-processing cost is also lower.

[0078] Therefore, the present invention uses methyltrichlorosilane as the main raw material, introduces a ladder control agent containing both an amine group and an alkoxy group to suppress the reactivity of methyltrichlorosilane, and then undergoes a hydrolysis reaction in a small amount of alcohol solvent and water, the hydrolysis rate is reduced, and the generation of cross-linked network structure insolubles during hydrolysis is avoided, making the reaction controllable. During the hydrolysis reaction, a small amount of small molecule alcohol in the water phase undergoes alcoholysis, which effectively reduces the risk of resin gelation. At the same time, the reduction in the amount of water reduces the total amount of acid water, and the pressure of environmental protection treatment is reduced. The small molecule alcohol is preferably ethanol, which is relatively easy to recycle and use compared to n-butanol with a higher boiling point.

[0079] In step S3 of the present invention, condensation polymerization easily occurs between the hydroxyl groups of the compound represented by formula II. During condensation polymerization, the crosslinking density of the resin increases, the molecular weight of the resin increases, and the water boiling performance of the resin is improved.

[0080] The trapezoidal methyl silicone resin prepared by the invention has excellent viscosity performance, high yield, excellent water boiling resistance, short curing time, high resin softening point and short gelation time.

[0081] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A trapezoidal methyl silicone resin, characterized in that: In parts by mass, including: 15 parts of methyltrichlorosilane, 5-12 parts of ladder control agent, 25-75 parts of water, 60-100 parts of solvent A, 2-30 parts of solvent B, and 0.03-0.06 parts of catalyst; The ladder control agent structure is NR X H 3-X , wherein R is any one of methoxy, ethoxy or butoxy; X is 1, 2 or 3; The solvent A is any one of toluene, xylene, methylcyclohexane and ethylcyclohexane; The solvent B is any one of methanol, ethanol, isopropanol and n-butanol; The catalyst is any one of zinc octoate and zinc naphthenate.

2. The ladder-shaped methyl silicone resin according to claim 1, characterized in that: The trapezoidal control agent is any one of ethanolamine, diethanolamine, triethanolamine, butanolamine, dibutanolamine and tributanolamine.

3. A method for preparing a ladder-shaped methyl silicone resin according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1: According to the formula, methyltrichlorosilane and part of solvent A are put into the first reaction container, the system temperature is controlled to be 5-10°C, and the mixture is evenly mixed. Then, a trapezoidal control agent is added dropwise to the first reaction container for 1-2 hours. During the addition, the reaction temperature is controlled to be 10-15°C. The amino groups contained in the trapezoidal control agent and part of the Si-Cl bonds in methyltrichlorosilane undergo an affinity substitution-elimination synergistic reaction in a non-polar solvent to obtain a compound shown in formula I. The synthetic reaction formula is as follows: S2: Add the remaining solvent A, water and solvent B into the second reaction container, control the system temperature to 10-15°C, mix evenly, then dropwise add the compound of formula I obtained in step S1 into the second reaction container, the dropping time is 2h, and during the dropping process, the reaction temperature is controlled to be 15-20°C; after the dropping is completed, control the system temperature to 20±2°C, hydrolyze for 2h, and then stand for stratification and take the supernatant as the compound of formula II; the synthetic reaction formula is as follows: S3: The compound represented by formula II obtained in step S2 is concentrated to a solid content of 40-60%, a catalyst is added, the temperature is raised and refluxed for polycondensation reaction for 4-5 hours, and then the temperature is lowered and filtered to obtain the polycondensation product, a trapezoidal methyl silicone resin; the synthetic reaction formula is as follows:

4. The method according to claim 3, characterized in that Before the concentration in step S3, the compound represented by formula II is washed with water until it is neutral, then filtered through anhydrous magnesium sulfate to remove water, and the filtered oil layer is concentrated.

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