A kind of organosilicon modified polyester polyol and its preparation method and application

Abstract

The present invention belongs to the technical field of polymer materials, and discloses a silicone-modified polyester polyol and a preparation method and application thereof. The preparation method is: hydrolyzing a dialkoxysilane, a trialkoxysilane and an acid catalyst solution; then adding a capping agent 1,3-bis(3-carboxylpropyl)tetramethyldisiloxane and / or 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane for copolymerization equilibrium reaction to obtain a carboxyl- and / or hydroxy-terminated MDT silicone resin; heating the carboxyl- and / or hydroxy-terminated MDT silicone resin with a dibasic acid and a diol to 180-240° C. under nitrogen protection and titanate catalyst conditions to obtain a silicone-modified polyester polyol. The present invention uses a carboxyl- and / or hydroxy-terminated MDT silicone resin to modify a polyester polyol, and compared with conventional linear silicone resin-modified polyester polyols, its application effect in the preparation of polyurethane materials is more significant.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and specifically relates to an organosilicon-modified polyester polyol and a preparation method and application thereof. Background Art

[0002] Polyester polyols are usually products obtained by condensation polymerization of dicarboxylic acids and diols. They are widely used in the preparation of polyester polyurethane coatings and have the advantages of good heat resistance, chemical resistance and high mechanical strength. However, their weather resistance, flexibility, compatibility with components such as isocyanates and additives, and processing performance are slightly inferior to those of polyether polyols.

[0003] Silicone materials contain Si-O bonds with high bond energy (422.2 kJ / mol) and rotation barriers close to zero. In addition, the single molecule volume of polysiloxane is large and the cohesive energy density is low. Therefore, it has excellent properties such as high and low temperature resistance, weather aging resistance, good flexibility, and good processing fluidity. Therefore, it is an ideal material for polyester polyol modified products.

[0004] The main methods for modifying polyester polyols with silicone are physical blending and chemical modification. Due to the low surface tension of polysiloxane, its compatibility with polyester polyols is poor. Simple physical blending will produce phase separation, poor modification effect, and even weaken its original mechanical properties. The chemical modification method mainly uses polysiloxane containing active reactive groups to react with polyacids or polyols, or directly react with polyester polyols to obtain the corresponding modified products. The chemical modification method has the advantage of good modification effect, but the activity of polysiloxane containing active reactive groups in reacting with polyacids, polyols or polyester polyols is significantly affected by its structure, so the design of its modification reaction route is critical to the product performance.

[0005] Jing Xu disclosed in the paper "Preparation and Performance Research of Silicone-Modified Polyester Polyols and Wire Enamels" that two schemes were used to synthesize silicone-modified polyacids: octamethylcyclotetrasiloxane and phthalic anhydride and octamethylcyclotetrasiloxane and adipic acid; and the scheme of dimethyldichlorosiloxane and ethylene glycol was used to synthesize silicone-modified polyols. The results showed that the silicone-modified polyacid schemes all failed, but the silicone-modified polyol scheme was successful. However, the silicone-modified polyol obtained was Si-OC connected, and the Si-OC bond was hydrolyzed and unstable at high temperature, so its modification effect on polyester polyol products was limited. Xu Fu et al. disclosed in the paper "Research on Silicone-Modified Polyester Polyol Resins" that the methyl etherified silicone intermediate Z-6018 was used to react with the hydroxyl active groups on the polyester chain to improve flexibility and heat resistance. However, the organic silicon modifier used is a single silicon atom raw material without the introduction of long-chain polysiloxane, so the modification effect is limited; in addition, the modification is still connected by Si-OC bonds, which has the problems of hydrolysis and high-temperature instability. Summary of the invention

[0006] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing silicone-modified polyester polyol.

[0007] Another object of the present invention is to provide an organosilicon-modified polyester polyol prepared by the above method.

[0008] Another object of the present invention is to provide the use of the above-mentioned organosilicon-modified polyester polyol in the preparation of polyurethane coatings.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] A method for preparing a silicone-modified polyester polyol comprises the following preparation steps:

[0011] (1) Preparation of carboxyl and / or hydroxyl terminated MDT silicone resin:

[0012] Dialkoxysilane (D), trialkoxysilane (T) and acid catalyst solution were added to the reaction kettle, and the temperature was raised to 30-60°C for hydrolysis reaction; then the end-capping agent 1,3-bis(3-carboxypropyl)tetramethyldisiloxane (MM -COOH ) and / or 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane (MM -OH ), heating to 60-80° C. to carry out copolymerization equilibrium reaction to obtain carboxyl and / or hydroxyl terminated MDT silicone resin;

[0013] (2) Preparation of silicone-modified polyester polyols:

[0014] The carboxyl and / or hydroxyl terminated MDT silicone resin, dibasic acid and diol are added to a reaction kettle, heated and stirred to mix, titanate catalyst is added under nitrogen protection, the temperature is raised to 180-240° C. and the reaction is maintained to obtain silicone modified polyester polyol.

[0015] Preferably, in step (1), the dialkoxysilane is selected from dimethyldimethoxysilane or dimethyldiethoxysilane; the trialkoxysilane is selected from methyltrimethoxysilane or methyltriethoxysilane; and the mass ratio of the dialkoxysilane, trialkoxysilane and capping agent added is 100:10-30:10-40.

[0016] Preferably, the acid catalyst solution in step (1) is hydrochloric acid or sulfuric acid solution, and the hydrolysis reaction time is 1 to 4 hours.

[0017] Preferably, the copolymerization equilibrium reaction time in step (1) is 2 to 6 hours; after the copolymerization equilibrium reaction is completed, the mixture is allowed to stand for stratification, and the oil phase is vacuum dried at 100 to 140° C. to remove water and low-boiling impurities, thereby obtaining a carboxyl and / or hydroxyl terminated MDT silicone resin.

[0018] Preferably, the carboxyl and / or hydroxyl terminated MDT silicone resin in step (1) has a weight average molecular weight (Mw) of 3000 to 8000 g / mol, and an acid value and / or hydroxyl value of 25 to 120 mgKOH / g.

[0019] Preferably, the dibasic acid in step (2) is at least one of an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid; an aliphatic dicarboxylic acid such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc.; an aromatic dicarboxylic acid such as phthalic acid, isophthalic acid, terephthalic acid, etc.; the diol is at least one of a polyether diol having a molecular weight of 400 to 2000 and an aliphatic diol having a carbon number of 2 to 6; the polyether diol is such as polyoxypropylene diol, polytetrahydrofuran diol, etc.; the aliphatic diol having a carbon number of 2 to 6 is such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol or 1,6-hexanediol, etc.

[0020] Furthermore, the molar ratio of carboxyl to hydroxyl in the reaction raw materials in step (2) is 1:1.2-1.5; and the amount of the carboxyl and / or hydroxyl terminated MDT silicone resin added is 10%-60% of the total mass of the dibasic acid and diol.

[0021] Furthermore, the heat preservation reaction in step (2) refers to firstly heat preservation reaction under closed conditions until the acid value is less than 5 mgKOH / g, and then dehydration reaction by reduced pressure distillation until the acid value is less than 1 mgKOH / g and the hydroxyl value is 40 to 120 mgKOH / g, to obtain silicone-modified polyester polyol.

[0022] An organosilicon-modified polyester polyol is prepared by the method.

[0023] Application of the above silicone-modified polyester polyol in the preparation of polyurethane coatings.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention uses carboxyl and / or hydroxyl-terminated MDT silicone resin as a macromolecular polyacid and / or polyol to copolymerize with dibasic acid and diol to prepare polyester polyol, wherein the MDT silicone resin introduces long-chain and branched polysiloxanes, which significantly improves weather resistance and flexibility. The active groups of the carboxyl and / or hydroxyl-terminated MDT silicone resin of the present invention are connected by Si-C bonds, and the modification effect of using them to modify polyester polyol is better than that of Si-OC bonded silicone resin.

[0026] (2) The carboxyl and / or hydroxyl terminated MDT silicone resin of the present invention can greatly reduce the crystallinity of the product through the branching effect of the T-linked chain, thereby increasing the molecular weight of the polymer and improving its compatibility; at the same time, its branching effect makes the obtained MDT silicone resin contain a large number of terminal carboxyl groups and / or hydroxyl groups, which can improve the reaction activity with dibasic acids and diols while retaining a portion of unreacted terminal hydroxyl groups for further grafting reaction with raw materials such as isocyanate, thereby further improving the overall performance.

[0027] (3) The carboxyl and / or hydroxyl terminated MDT silicone resin of the present invention can be reacted with polyacids and polyols through conventional processes to prepare polyester polyols, and is suitable for the preparation of conventional polyurethane systems without the need to modify the existing industrial process routes. It has the advantages of easy application and low industrial cost. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0029] Example 1

[0030] A method for preparing a silicone-modified polyester polyol comprises the following preparation steps:

[0031] (1) Preparation of carboxyl and hydroxyl terminated MDT silicone resin:

[0032] 10 kg of dimethyldiethoxysilane, 2 kg of methyltriethoxysilane and 0.5 kg of 1 M sulfuric acid aqueous solution were added to the reactor, and the temperature was raised to 45 °C for hydrolysis reaction for 2 h; then 1.5 kg of end-capping agent 1,3-bis(3-carboxypropyl)tetramethyldisiloxane (MM -COOH ) and 1.5 kg of end-capping agent 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane (MM -OH), the temperature was raised to 75°C for copolymerization equilibrium reaction for 4 hours, and after the reaction was completed, the stratification was allowed to stand, and the oil phase was vacuum dried at 120°C to remove water and low-boiling impurities, thereby obtaining carboxyl- and hydroxyl-terminated MDT silicone resin. The acid value (potassium hydroxide titration method) of the MDT silicone resin was determined by sampling titration method to be 32.6 mgKOH / g, the hydroxyl value (acetic anhydride titration method) was 40.5 mgKOH / g, and the weight average molecular weight was determined by GPC to be 5280 g / mol.

[0033] (2) Preparation of silicone-modified polyester polyols:

[0034] Take 1kg of the carboxyl and hydroxyl terminated MDT silicone resin obtained in step (1), 1.46kg of adipic acid, 1.8kg of polyoxypropylene glycol PPG-600 and 0.76kg of 1,3-propylene glycol, add them to a high pressure reactor, heat and stir to dissolve and mix, add 0.1wt% n-butyl titanate catalyst under nitrogen protection, heat to 220℃, seal and keep warm for 4h, during the reaction, test the acid value of the mixture every half an hour until the acid value of the mixture is less than 5mgKOH / g. Then, dehydrate and react by vacuum distillation at 220-240℃ until the acid value is less than 1mgKOH / g, continue vacuum insulation reaction for 1h, sample and test the hydroxyl value of the product to be 78.2mgKOH / g, and obtain silicone modified polyester polyol.

[0035] Example 2

[0036] A method for preparing a silicone-modified polyester polyol comprises the following preparation steps:

[0037] (1) Preparation of carboxyl-terminated MDT silicone resin:

[0038] 10 kg of dimethyldiethoxysilane, 3 kg of methyltriethoxysilane and 0.5 kg of 1 M sulfuric acid aqueous solution were added to the reactor, and the temperature was raised to 55 °C for hydrolysis reaction for 2 h; then 4 kg of end-capping agent 1,3-bis(3-carboxypropyl)tetramethyldisiloxane (MM -COOH ), the temperature was raised to 80°C for copolymerization equilibrium reaction for 4 hours, and after the reaction was completed, the mixture was allowed to stand for stratification, and the oil phase was vacuum dried at 120°C to remove water and low-boiling impurities, thereby obtaining a carboxyl-terminated MDT silicone resin. The acid value of the MDT silicone resin was determined to be 80.5 mgKOH / g by sampling titration, and the weight average molecular weight was 3760 g / mol by GPC.

[0039] (2) Preparation of silicone-modified polyester polyols:

[0040] Take 2kg of the carboxyl-terminated MDT silicone resin obtained in step (1), 1kg of succinic acid, 1.6kg of polyoxypropylene glycol PPG-800 and 1.42kg of 1,6-hexanediol, add them to a high-pressure reactor, heat and stir to dissolve and mix, add 0.1wt% n-butyl titanate catalyst under nitrogen protection, heat to 220℃, seal and keep warm for 4h, during the reaction, test the acid value of the mixture every half an hour until the acid value of the mixture is less than 5mgKOH / g. Then, distill and dehydrate at 220-240℃ under reduced pressure until the acid value is less than 1mgKOH / g, continue vacuum insulation reaction for 1h, sample and test the hydroxyl value of the product to be 96.4mgKOH / g, and obtain silicone-modified polyester polyol.

[0041] Example 3

[0042] A method for preparing a silicone-modified polyester polyol comprises the following preparation steps:

[0043] (1) Preparation of hydroxyl-terminated MDT silicone resin:

[0044] 10 kg of dimethyldiethoxysilane, 1 kg of methyltriethoxysilane and 0.5 kg of 1M sulfuric acid aqueous solution were added to the reactor, and the temperature was raised to 45°C for hydrolysis reaction for 2 hours; then 1 kg of end-capping agent 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane (MM -OH ), the temperature was raised to 75°C for copolymerization equilibrium reaction for 3 hours, and after the reaction was completed, the mixture was allowed to stand for stratification, and the oil phase was vacuum dried at 120°C to remove water and low-boiling impurities, thereby obtaining a hydroxyl-terminated MDT silicone resin. The hydroxyl value of the MDT silicone resin was determined to be 35.8 mgKOH / g by sampling titration, and the weight average molecular weight was 6650 g / mol by GPC.

[0045] (2) Preparation of silicone-modified polyester polyols:

[0046] Take 1kg of the hydroxyl-terminated MDT silicone resin obtained in step (1), 2.36kg of succinic acid, 2kg of polyoxypropylene glycol PPG-400 and 2.36kg of 1,6-hexanediol, add them to a high-pressure reactor, heat, stir and dissolve, add 0.1wt% n-butyl titanate catalyst under nitrogen protection, heat to 220℃, seal and keep warm for 4h, during the reaction, test the acid value of the mixture every half an hour until the acid value of the mixture is less than 5mgKOH / g. Then, perform dehydration reaction under reduced pressure distillation at 220-240℃ until the acid value is less than 1mgKOH / g, continue vacuum insulation reaction for 1h, sample and test the hydroxyl value of the product to be 57.3mgKOH / g, and obtain silicone-modified polyester polyol.

[0047] Comparative Example 1

[0048] A method for preparing a polyester polyol, compared with Example 1, does not add carboxyl and hydroxyl terminated MDT silicone resin, comprising the following preparation steps:

[0049] 1.46kg adipic acid, 1.8kg polyoxypropylene glycol PPG-600 and 0.76kg 1,3-propylene glycol were added to a high-pressure reactor, heated, stirred and dissolved, and a 0.1wt% concentration of n-butyl titanate catalyst was added under nitrogen protection. The temperature was raised to 220°C and sealed for 4 hours. During the reaction, the acid value of the mixture was tested every half an hour until the acid value of the mixture was less than 5mgKOH / g. Then, the mixture was dehydrated by vacuum distillation at 220-240°C until the acid value was less than 1mgKOH / g. The vacuum insulation reaction was continued for 1 hour. The hydroxyl value of the product was 85.7mgKOH / g when the sample was tested to obtain a polyester polyol.

[0050] Comparative Example 2

[0051] A method for preparing a silicone-modified polyester polyol, compared with Example 3, uses the linear hydroxy silicone oil PDMS disclosed in the literature (Preparation of silicone-modified waterborne polyurethane coating and its antifouling performance [J], Journal of Functional Polymers, 2021, 34(4): 397-385) to replace the hydroxyl-terminated MDT silicone resin, comprising the following preparation steps:

[0052] Take 1kg of hydroxy silicone oil PDMS (weight average molecular weight determined by GPC is 6200g / mol), 2.36kg of succinic acid, 2kg of polyoxypropylene glycol PPG-400 and 2.36kg of 1,6-hexanediol, add them to a high-pressure reactor, heat, stir and dissolve, add 0.1wt% n-butyl titanate catalyst under nitrogen protection, heat to 220℃, seal and keep warm for 4h, during the reaction, test the acid value in the mixture every half an hour until the acid value in the mixture is less than 5mgKOH / g. Then, dehydrate and react under reduced pressure distillation at 220-240℃ until the acid value is less than 1mgKOH / g, continue vacuum insulation reaction for 1h, sample and test the hydroxyl value of the product to be 64.9mgKOH / g, and obtain silicone-modified polyester polyol.

[0053] Comparative Example 3

[0054] A method for preparing an organosilicon-modified polyester polyol, compared with Example 1, uses carboxyl- and hydroxyl-terminated linear silicone resins to replace carboxyl- and hydroxyl-terminated MDT silicone resins, comprising the following preparation steps:

[0055] (1) Preparation of carboxyl and hydroxyl terminated linear silicone resins:

[0056] 10 kg of dimethyldiethoxysilane and 0.5 kg of 1 M sulfuric acid aqueous solution were added to the reactor, and the temperature was raised to 45 °C for hydrolysis reaction for 2 h; then 1.5 kg of end-capping agent 1,3-bis(3-carboxypropyl)tetramethyldisiloxane (MM -COOH ) and 1.5 kg of end-capping agent 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane (MM -OH ), the temperature was raised to 75°C for copolymerization equilibrium reaction for 4 hours, and after the reaction was completed, the stratification was allowed to stand, and the oil phase was vacuum dried at 120°C to remove water and low-boiling impurities, thereby obtaining a carboxyl- and hydroxyl-terminated linear silicone resin. The acid value of the carboxyl- and hydroxyl-terminated linear silicone resin was determined by sampling titration to be 36.5 mgKOH / g, the hydroxyl value was 44.2 mgKOH / g, and the weight average molecular weight was 1750 g / mol by GPC.

[0057] (2) Preparation of silicone-modified polyester polyols:

[0058] Take 1kg of the carboxyl and hydroxyl terminated linear silicone resin obtained in step (1), 1.46kg of adipic acid, 1.8kg of polyoxypropylene glycol PPG-600 and 0.76kg of 1,3-propylene glycol, add them to a high-pressure reactor, heat, stir and dissolve, add 0.1wt% n-butyl titanate catalyst under nitrogen protection, heat to 220℃ and seal and keep warm for 4h. During the reaction, the acid value in the mixture is tested every half an hour until the acid value in the mixture is less than 5mgKOH / g. Then, dehydrate and react by vacuum distillation at 220-240℃ until the acid value is less than 1mgKOH / g, continue vacuum and keep warm for 1h, sample and test the hydroxyl value of the product to be 83.6mgKOH / g, and obtain silicone modified polyester polyol.

[0059] The polyester polyols obtained in the above Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to performance tests. The test method is as follows: the obtained polyester polyol is dissolved in toluene solvent to prepare a polyester polyol solution with a solid content of 42%, and then the solution is mixed evenly with an HDI trimer curing agent at a molar ratio of hydroxyl to isocyanate of 1:1 to obtain a coating. After the coated object is sizing, coating and curing, the corresponding coating properties are tested or a standard sample of the cured product is prepared to test the corresponding properties. Among them, the adhesion test refers to the standard GB / T 5210-2006, and the adhesion substrate uses a hard steel plate; the tensile strength and elongation at break test refer to the standard GB / T 528-2009; the low-temperature flexibility test refers to the standard GB / T 6742-2007, and the test is conditioned for 24 hours at a low temperature of (-30±2)℃ and a relative humidity of (50±5)% before the test; the weather resistance test refers to the standard GB / T 14522-2, and the light source is a UVA-340 fluorescent ultraviolet lamp with an irradiance of 0.89W / m 2 , the tensile strength retention rate and elongation at break retention rate after 600h artificial weathering were tested. The test results are shown in Table 1 below.

[0060] Table 1

[0061]

[0062] It can be seen from the comparison results of Examples 1 to 3 and Comparative Example 1 in Table 1 that the present invention can significantly improve the strength, adhesion, weather resistance and flexibility of the polyurethane material obtained after curing by adding carboxyl and / or hydroxyl-terminated MDT silicone resin to modify the polyester polyol. It can be seen from the comparison results of Example 3 and Comparative Example 2 that after the linear hydroxyl silicone oil PDMS is used to replace the hydroxyl-terminated MDT silicone resin, the corresponding strength improvement effect and the weather resistance and flexibility improvement effect are significantly reduced, and the adhesion of the coating film is significantly adversely affected. The reason is that the compatibility and reactivity of the linear hydroxyl silicone oil PDMS are relatively low, and the reaction generates a Si-OC connection structure with poor heat resistance and hydrolysis resistance and a branched structure without T chain segments, resulting in a reduction in the improvement effect. At the same time, the adhesion is reduced due to the low surface energy characteristics of PDMS and the reduced grafting modification effect. By comparing the results of Example 1 with Comparative Example 3, it can be seen that the molecular weight of the carboxyl- and hydroxyl-terminated linear silicone resin obtained without adding T-links is low, and the branched structure without introducing T-links leads to a significant reduction in the improvement effect of weather resistance and flexibility.

[0063] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a silicone-modified polyester polyol, characterized in that: The method comprises the following preparation steps: (1) Preparation of carboxyl and / or hydroxyl terminated MDT silicone resin: Adding dialkoxysilane, trialkoxysilane and an acid catalyst solution into a reaction kettle, heating to 30-60° C. for hydrolysis reaction; then adding a capping agent 1,3-bis(3-carboxypropyl)tetramethyldisiloxane and / or 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane, heating to 60-80° C. for copolymerization equilibrium reaction, and obtaining a carboxyl and / or hydroxyl-terminated MDT silicone resin; (2) Preparation of silicone-modified polyester polyols: Add carboxyl and / or hydroxyl terminated MDT silicone resin, dibasic acid and diol into a reaction kettle, heat and stir to mix, add titanate catalyst under nitrogen protection, heat to 180-240°C for reaction, and obtain organosilicon modified polyester polyol; In step (1), the dialkoxysilane is selected from dimethyldimethoxysilane or dimethyldiethoxysilane; the trialkoxysilane is selected from methyltrimethoxysilane or methyltriethoxysilane; the mass ratio of the dialkoxysilane, trialkoxysilane and the capping agent added is 100:10~30:10~40; The carboxyl and / or hydroxyl terminated MDT silicone resin in step (1) has a weight average molecular weight of 3000-8000 g / mol, and an acid value and / or hydroxyl value of 25-120 mgKOH / g; The molar ratio of carboxyl to hydroxyl in the reaction raw materials in step (2) is 1:1.2-1.5; the amount of the carboxyl and / or hydroxyl terminated MDT silicone resin added is 10%-60% of the total mass of the dibasic acid and the diol.

2. The method for preparing a silicone-modified polyester polyol according to claim 1, characterized in that: The acid catalyst solution in step (1) is hydrochloric acid or sulfuric acid solution, and the hydrolysis reaction time is 1 to 4 hours.

3. The method for preparing a silicone-modified polyester polyol according to claim 1, characterized in that: The copolymerization equilibrium reaction time in step (1) is 2 to 6 hours. After the copolymerization equilibrium reaction is completed, the reaction is allowed to stand and the layers are separated. The oil phase is vacuum dried at 100 to 140° C. to remove water and low-boiling impurities, thereby obtaining a carboxyl and / or hydroxyl terminated MDT silicone resin.

4. The method for preparing a silicone-modified polyester polyol according to claim 1, characterized in that: The dibasic acid in step (2) is at least one of an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid; the aliphatic dicarboxylic acid is oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid or sebacic acid; the aromatic dicarboxylic acid is phthalic acid, isophthalic acid or terephthalic acid; the diol is at least one of a polyether diol having a molecular weight of 400 to 2000 and an aliphatic diol having a carbon number of 2 to 6; the polyether diol is polyoxypropylene diol or polytetrahydrofuran diol; the aliphatic diol having a carbon number of 2 to 6 is ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol or 1,6-hexanediol.

5. The method for preparing a silicone-modified polyester polyol according to claim 1, characterized in that: The heat preservation reaction in step (2) refers to firstly heat preservation reaction under closed conditions until the acid value is less than 5 mgKOH / g, and then dehydration reaction by reduced pressure distillation until the acid value is less than 1 mgKOH / g and the hydroxyl value is 40-120 mgKOH / g, to obtain silicone-modified polyester polyol.

6. A silicone-modified polyester polyol, characterized in that: It is prepared by the method according to any one of claims 1 to 5.

7. Use of the organosilicon-modified polyester polyol according to claim 6 in the preparation of polyurethane coatings.

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