A low viscosity, non-toxic, silane-terminated polyether resin and a method for its preparation

Abstract

The application discloses a kind of low viscosity non-toxic silane end-capped polyether resin and preparation method thereof, belong to sealant technical field.The preparation method of the silane end-capped polyether resin is with succinic anhydride and polyether polyol as raw material, polymer is prepared under the catalysis of acid catalyst;N-hydroxysuccinimide and carbodiimide catalyst are added to polymer and stirred to react, end-capping is carried out by dropping aminoalkoxy silane coupling agent to system, and the silane end-capped polyether resin is prepared.The application is reacted with polyether polyol by cheap succinic anhydride, the hydroxyl group at the end of polyether alcohol is changed into more active carboxyl group while chain extension, subsequent modification is facilitated, expensive and toxic isocyanate coupling agent or tin catalyst is not introduced, it is safe and non-toxic, the silane end-capped resin obtained only contains two amide bonds at the end, can effectively reduce the viscosity of product, and be beneficial to subsequent application of product.

Description

Technical Field

[0001] This invention relates to the field of sealant technology, specifically to a low-viscosity, non-toxic silane-terminated polyether resin and its preparation method. Background Technology

[0002] Silane-terminated resins are a crucial class of moisture-curable resins. Compared to other moisture-curable resins, silane-terminated resins exhibit broader adhesion to substrates due to the alkoxysilanes attached to the ends of their main chains. Therefore, they are widely used in various fields such as the automotive industry, electronics, civil engineering, new energy, and solar photovoltaics. Compared to polyurethane resins, silane-terminated resins do not generate bubbles during curing, thus not affecting the material's mechanical properties. Furthermore, the cured Si-O-Si molecular chains exhibit strong UV resistance and weather resistance. In addition, silane-modified polymer products do not contain free isocyanates or organic solvents, making them environmentally friendly and aligning with the current global trend towards green environmental protection and the development of new elastic sealing materials.

[0003] Specifically, silane-terminated resins can be further divided into two main categories based on their main chain: silane-modified polyethers (MS) and silane-modified polyurethanes (SPUs). MS resin was initially produced by KANEKA in Japan using the traditional dihalomethane chain extension method. This method first uses allyl polyether alcohol and hydroxyl-terminated polyether as raw materials, with dihalomethane as a chain extender and alkali metal hydroxide as a catalyst to increase the molecular weight. Then, allyl halides are used to end the hydroxyl groups, and after desalting and purification, dielyl-terminated polyether is obtained. Finally, the dielyl-terminated polyether undergoes a hydrosilylation reaction with alkoxysilane under the action of a platinum catalyst to obtain MS resin. Subsequently, AGC Corporation of Japan used an allyl chloride chain extension method to prepare MS resin. This method first uses small-molecule alcohols as initiators, reacting them with ethylene oxide or propylene oxide in a ring-opening addition polymerization reaction under the action of a bimetallic cyanide complex catalyst to prepare hydroxyl-terminated high-molecular-weight polyether polyols. Then, allyl chloride is used to double-end the polyether polyols with alkoxides such as sodium methoxide to prepare high-molecular-weight dielyl polyether polyols. Finally, methyl dimethoxysilane is used to react with the high-molecular-weight dielyl polyether polyols in a hydrosilylation reaction under a platinum catalyst to prepare MS resin. Both of these methods involve the allylation process of polyethers. This process is cumbersome, requiring multiple purification steps. High viscosity makes raw material mixing difficult, resulting in low synthesis efficiency. Therefore, these methods typically only yield low-molecular-weight dielyl-terminated polyethers with a wide distribution, while the conversion rate of high-molecular-weight dielyl polyethers is low. SPU resin was first developed by GE in the United States. It uses a tin-based catalyst to directly cap hydroxyl-terminated polyethers or polyester diols containing isocyanate groups (-NCO) with siloxanes, achieving a one-step process to obtain SPU resin. This method is simple, easy to operate, and allows for easy control of product viscosity, resulting in a relatively concentrated molecular weight distribution. However, alkoxysilanes containing -NCO groups are expensive, significantly increasing production costs, and the availability of such specialized alkoxysilanes on the market greatly limits the application of this method. Currently, the mainstream method for producing SPU resin is a two-step process. This process first reacts polyethers or polyester diols with diisocyanates to obtain a polyurethane prepolymer, and then uses functional siloxanes to cap the polyurethane prepolymer. Compared to the one-step method, this method reduces production costs to some extent, but the use of secondary amine silane coupling agents for capping introduces a large number of amide bonds (-CO-NH-) into the system, making it easy for hydrogen bonds to form between and within molecules, leading to a rapid increase in system viscosity, which is detrimental to later applications. Chinese patent CN107955571A uses thiol-alkoxysilanes to end-group the -NCO group or isothiocyanate-alkoxysilanes to end-group the -OH group, replacing the amide bond (-CO-NH-) with a thioamide (-CS-NH-), which can effectively reduce the viscosity of the system. However, thiol-alkoxysilanes and isothiocyanate-alkoxysilanes are very expensive and rare.

[0004] Therefore, it is essential to provide a simple, easy-to-operate, low-viscosity, non-toxic silane-terminated polyether resin and its preparation method. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing a low-viscosity, non-toxic silane-terminated polyether resin. The silane-terminated polyether resin prepared by this method contains only two amide bonds at the end, which can effectively reduce the viscosity of the product, which is beneficial to the application of the product, and does not introduce toxic coupling agents or catalysts, making it safe and non-toxic.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a low-viscosity, non-toxic silane-terminated polyether resin involves using succinic anhydride and polyether polyol as raw materials to obtain a polymer under the catalysis of an acid catalyst; adding N-hydroxysuccinimide and carbodiimide catalysts to the polymer and stirring the reaction; then adding an aminoalkoxysilane coupling agent dropwise to the system for end-capping to obtain the silane-terminated polyether resin.

[0008] As a preferred embodiment of the present invention, the preparation method specifically includes the following steps:

[0009] S1. Place the polyether polyol under vacuum at 110-120℃ for more than 1 hour to dehydrate it; add succinic anhydride and acid catalyst to the polyether polyol, stir and heat to 120-180℃ under nitrogen atmosphere, keep it at this temperature for 4-6 hours. During the reaction, wait until the system changes from turbid to homogeneous and transparent and the acid value remains basically unchanged, continue to keep it at this temperature for 0.5-1.5 hours, degas and cool to below 60℃, filter and discharge to obtain the polymer;

[0010] S2. Add N-hydroxysuccinimide and carbodiimide catalyst to the polymer obtained in step S1, stir and heat to 120-140°C under a nitrogen atmosphere, stabilize at the temperature for 0.5-1 h, cool down to 70-80°C, add aminoalkoxysilane coupling agent dropwise to the system, keep at the temperature for 1.5-2 h, cool down to below 60°C, filter, and obtain the silane-terminated polyether resin.

[0011] In a preferred embodiment of the present invention, the acid catalyst is one or more of phosphoric acid, phosphorous acid, p-toluenesulfonic acid, phosphotungstic acid, and a strong acid cation exchange resin. More preferably, a strong acid cation exchange resin is used, as it exhibits superior catalytic effect. Furthermore, compared to conventional acid catalysts such as p-toluenesulfonic acid, the strong acid cation exchange resin requires a lower dosage, can be easily removed from the system through simple filtration, and can be reused.

[0012] In a preferred embodiment of the present invention, the carbodiimide catalyst is one or more of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, and N-cyclohexyl-N′-(2-morpholinoethyl)carbodiimide methyl p-toluenesulfonate.

[0013] In a preferred embodiment of the present invention, the molecular weight of the polyether polyol is 2000-8000 g / mol.

[0014] More preferably, the polyether polyol is one of PPG, PEG, a mixture of PPG and PEG, or a copolymer of EG and PG.

[0015] In a preferred embodiment of the present invention, the molar ratio of the polyether polyol to succinic anhydride is 1:1.5 to 1.8.

[0016] In a preferred embodiment of the present invention, the amount of acid catalyst used is 0.5 to 1.5% of the total weight of all mixtures in step S1.

[0017] In a preferred embodiment of the present invention, the molar ratio of the carboxyl group in the polymer, the amino group in the aminoalkoxy coupling agent, the N-hydroxysuccinimide and the carbodiimide catalyst is 1:2:2:2 to 2.5.

[0018] The second objective of this invention is to provide a low-viscosity, non-toxic silane-terminated polyether resin, which is prepared by the method described above.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) This invention uses inexpensive succinic anhydride to react with polyether polyol. While extending the chain, the hydroxyl groups at the end of the polyether alcohol are converted into more active carboxyl groups, which facilitates subsequent modification. At the same time, the chain extension process of succinic anhydride on polyether and the subsequent alkoxysilane end-capping process of polyether do not introduce expensive and toxic isocyanate coupling agents or use toxic tin catalysts, so that the obtained silane-capped resin is safe and non-toxic.

[0021] (2) The silane-terminated resin prepared by the preparation method of the present invention contains only two amide bonds (-CO-NH-) at the end, which can effectively reduce the viscosity of the product and facilitate its subsequent application.

[0022] In summary, the preparation method of the present invention is simple and easy to operate. The preparation process does not introduce toxic dihaloalkanes, tin catalysts, isocyanates, or other substances into the system, making it safe and environmentally friendly. Furthermore, the silane-terminated resin product obtained has low viscosity and is easy to use in subsequent applications. Detailed Implementation

[0023] A method for preparing a low-viscosity, non-toxic silane-terminated polyether resin is disclosed. The method involves first preparing a polymer from succinic anhydride and polyether polyol under the catalysis of an acid catalyst; then adding N-hydroxysuccinimide (NHS) and a carbodiimide catalyst to the polymer and stirring the reaction; finally, adding an aminoalkoxysilane coupling agent dropwise to the system for end-capping, thus obtaining the silane-terminated polyether resin. The reaction process involved in this preparation method is as follows:

[0024]

[0025] In the above reaction equations, the molecular weight of the polyether polyol is 2000–8000 g / mol; the polyether polyol is one of PPG, PEG, a mixture of PPG and PEG, or a copolymer of EG and PG, wherein R1 is -CH3 or -H. The acid catalyst is at least one of phosphoric acid, phosphorous acid, p-toluenesulfonic acid, phosphotungstic acid, or a strongly acidic cation exchange resin. The carbodiimide catalyst is at least one of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC), N,N'-dicyclohexylcarbodiimide (DCC), N,N'-diisopropylcarbodiimide (DIC), or N-cyclohexyl-N′-(2-morpholinoethyl)carbodiimide methyl p-toluenesulfonate (CMC). Aminoalkoxy coupling agents are commercially available aminoalkoxy coupling agents, where R2 is -CH3, -CH2CH3, -OCH3, -OCH2CH3, etc., R3 is -OCH3, -OCH2CH3, etc., and R4 is -C3H6-, -C3H6-NH-C3H6-, etc.

[0026] The preparation method specifically includes the following steps:

[0027] S1. The polyether polyol is vacuum dehydrated at 110-120℃ for more than 1 hour; succinic anhydride and acid catalyst are added to the polyether polyol, and the mixture is stirred and heated to 120-180℃ under a nitrogen atmosphere, and kept at this temperature for 3-6 hours. During the reaction, the system changes from turbid to homogeneous and transparent and the acid value remains basically unchanged. The temperature is then maintained for another 0.5-1.5 hours, degassed, and cooled to below 60℃. The mixture is then filtered to obtain the polymer. The molar ratio of polyether polyol to succinic anhydride is 1:1.5-1.8, and the amount of acid catalyst is 0.5-1.5% of the total weight of all mixtures in step S1.

[0028] S2. Add N-hydroxysuccinimide and carbodiimide catalyst to the polymer obtained in step S1. Stir and heat to 120-140°C under a nitrogen atmosphere, stabilize at the temperature for 0.5-1 h, cool to 70-80°C, add aminoalkoxysilane coupling agent dropwise to the system, maintain the temperature for 1.5-2 h, cool to below 60°C, and filter to obtain the silane-terminated polyether resin. The molar ratio of carboxyl groups in the polymer, amino groups in the aminoalkoxy coupling agent, and N-hydroxysuccinimide to carbodiimide catalyst is 1:2:2:2-2.5.

[0029] Example 1

[0030] A method for preparing a low-viscosity, non-toxic silane-terminated polyether resin, comprising the following steps:

[0031] S1. Add 1000g of polypropylene glycol (molecular weight 2000g / mol) to the reactor and dehydrate under vacuum at 120℃ for 2h. Then add 75g of succinic anhydride and an appropriate amount of acid catalyst to the system, add nitrogen three times, and continue heating to 130±5℃ under a nitrogen atmosphere of 0.2Mpa. After holding at this temperature for 3h, the system becomes homogeneous and transparent, and the acid value of the system remains basically unchanged. Continue holding at this temperature for 0.5h, then start degassing and cooling, and filter to obtain high molecular weight polyester dicarboxylic acid.

[0032] Under the above process conditions, different acid catalysts were selected to prepare high molecular weight polyester dicarboxylic acid intermediates AD, and their number-average molecular weight and molecular weight distribution are shown in Table 1.

[0033] Table 1. Results of dynamic viscosity tests for polyester dicarboxylic acids of the same molecular weight prepared with different acid catalysts.

[0034] Polymer Number Catalyst types Dosage (%)* Number-average molecular weight (Mn) Molecular weight distribution (PDI) A Strong acid cation exchange resin 0.5 4012 1.013 B p-Toluenesulfonic acid 0.6 3986 1.025 C Phosphoric acid 0.8 3923 1.034 D phosphotungstic acid 0.6 4005 1.022

[0035] Note: "*" The percentage here is relative to the total weight of all mixtures in step S1.

[0036] S2. Take 500g of polymer A obtained in step S1 and add it to the reactor. Then add 24.75g of N-hydroxysuccinimide and 38.75g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide. Add nitrogen three times, stir and heat to 125℃ under nitrogen atmosphere, keep warm for 1h, and then cool down to 70-80℃. Add 44.75g of 3-aminopropyltrimethoxysilane dropwise to the system, add nitrogen at 0.2MPa, keep warm for 1.5h, cool down to below 60℃ and filter to obtain silane-terminated polyether.

[0037] Example 2

[0038] A method for preparing a low-viscosity, non-toxic silane-terminated polyether resin, comprising the following steps:

[0039] S1. Add 1000g of polypropylene glycol (molecular weight 5000g / mol) to the reactor and dehydrate under vacuum at 120℃ for 2h. Then add 32g of succinic anhydride and 8.26g of strong acid cation exchange resin to the system, expose to nitrogen three times, and continue heating to 135±5℃ under a nitrogen atmosphere of 0.2Mpa. After holding at this temperature for 4h, the system becomes homogeneous and transparent, and the acid value of the system remains basically unchanged. Continue holding at this temperature for 0.5h, then begin degassing and cooling, and filter to obtain high molecular weight polyester dicarboxylic acid.

[0040] S2. Take 500g of the polymer obtained in step S1 and add it to the reactor. Then add 9.9g of N-hydroxysuccinimide and 17.44g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide. Add nitrogen three times, stir and heat to 125℃ under nitrogen atmosphere, keep warm for 1h, and then cool down to 70-80℃. Add 17.9g of 3-aminopropyltrimethoxysilane dropwise to the system, add nitrogen at 0.2MPa, keep warm for 1.5h, cool down to below 60℃ and filter to obtain silane-terminated polyether.

[0041] Example 3

[0042] A method for preparing a low-viscosity, non-toxic silane-terminated polyether resin, comprising the following steps:

[0043] S1. Add 1000g of polypropylene glycol (molecular weight 8000g / mol) to the reactor and dehydrate under vacuum at 120℃ for 2h. Then add 21.87g of succinic anhydride and 11.24g of strong acid cation exchange resin to the system, expose to nitrogen three times, and continue heating to 150±5℃ under a nitrogen atmosphere of 0.2Mpa. After holding at this temperature for 5h, the system becomes homogeneous and transparent, and the acid value of the system remains basically unchanged. Continue holding at this temperature for 1h, then begin degassing and cooling, and filter to obtain high molecular weight polyester dicarboxylic acid.

[0044] S2. Take 500g of the polymer obtained in step S1 and add it to the reactor. Then add 6.2g of N-hydroxysuccinimide and 11.9g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide. Add nitrogen three times, stir and heat to 140℃ under nitrogen atmosphere, keep warm for 2h, then cool down to 70-80℃, add 11.2g of 3-aminopropyltrimethoxysilane dropwise to the system, add nitrogen 0.2Mpa, keep warm for 1.5h, cool down to below 60℃ and filter to obtain silane-terminated polyether.

[0045] Example 4

[0046] The only difference between this embodiment and Example 1 is that in step S1, 1000g of polyethylene glycol (molecular weight 8000g / mol) is added to the reaction vessel.

[0047] Comparative Example 1

[0048] This comparative example uses the existing conventional diisocyanate chain extension method to prepare silane-terminated polyether resin, and the preparation method is as follows:

[0049] 1000g of polyether polyol (molecular weight 16000g / mol, functionality 2) was added to a reactor and dehydrated under vacuum at 120℃ for 2-3 hours. The temperature was then lowered to below 50℃, and 21.75g ​​of toluene diisocyanate was added. The reaction was carried out at 80℃ for 3 hours to obtain a polyurethane prepolymer. Then, 26.85g of 3-aminopropyltrimethoxysilane was added to the polyurethane prepolymer, and the system was reacted at 80℃ under a nitrogen atmosphere for 2-3 hours to obtain a silane-terminated polyether resin.

[0050] Comparative Example 2

[0051] The only difference between this comparative example and Comparative Example 1 is that 25.2g of 1,6-hexamethylene diisocyanate was added during chain extension.

[0052] Comparative Example 3

[0053] In this comparative example, polyether polyols were carboxylated by alkyd esterification, and then silane-terminated polyether resins were prepared by glycidyl ether alkoxysilane end-capping. The preparation method is as follows:

[0054] 1000g of polypropylene glycol ether diol with a molecular weight of 10000g / mol (its structure is...) was added to a three-necked flask equipped with a stirrer and a thermometer. Where R is a straight-chain or branched C1-C10 alkoxy group, x is much larger than y, and all are integers) the temperature is raised to 100℃ and vacuumed for 2h, the temperature is further raised to 200℃, and 33.5g of terephthalic acid is added. After reacting for 1h, the temperature is vacuumed and the reaction continues for 5h to obtain carboxyl-terminated polyether.

[0055] The temperature of the above reactants was lowered to 110°C, and 47.2g of γ-glycidyl etheroxypropyltrimethoxysilane and 8.7g (total weight 0.8%) of triphenylphosphine catalyst were added and the reaction was continued for 2 hours. The temperature was then lowered to 50°C and the product was discharged to obtain silane-terminated polyether.

[0056] Comparative Example 4

[0057] This comparative example uses an anhydride ring-opening reaction to carboxylate the polyether polyol, and then prepares a silane-terminated polyether resin by glycidyl ether alkoxysilane end-capping. The preparation method is as follows:

[0058] Add 500g of polypropylene glycol ether diol with a molecular weight of 4000g / mol (its structure is...) to a three-necked flask equipped with a stirrer and a thermometer. Where R is a straight-chain or branched C1-C10 alkoxy group, x is much larger than y, and all are integers), the temperature is raised to 100℃ and vacuumed for 1 hour, the temperature is further raised to 130℃, and 37g of phthalic anhydride is added. The reaction is carried out for 2 hours to obtain carboxyl-terminated polyether.

[0059] The temperature of the above reactants was lowered to 120°C, and 59g of γ-glycidyl etheroxypropyltrimethoxysilane and 2.98g (total weight 0.5%) of secondary amine catalyst were added and the reaction was continued for 2 hours. The temperature was then lowered to 50°C and the product was discharged to obtain silane-terminated polyether.

[0060] I. Dynamic Viscosity Test

[0061] The dynamic viscosity of the silane-terminated polyether resins prepared in Examples 1-4 and Comparative Examples 1-4 was tested, and the results are shown in Table 2.

[0062] Table 2. Dynamic viscosity test results of the silane-terminated polyether resins prepared in Examples 1-4 and Comparative Examples 1-4.

[0063]

[0064] As shown in Table 2, for products with the same molecular weight, the product prepared by the method provided by the invention has a narrower molecular weight distribution (less than 1.1) and a lower dynamic viscosity. This indicates that the preparation method of the present invention can effectively reduce the viscosity of the product and make the molecular weight distribution of the product more concentrated.

[0065] II. Application Performance Testing

[0066] The silane-terminated polyether resins prepared in Examples 3 and 4, Comparative Examples 1 and 2 were used to prepare moisture-curing sealants according to the formulations shown in Table 2.

[0067] Table 2. Formulation of Moisture-Curing Sealants

[0068] name quality score Silane-terminated polyether resin 20.0％ plasticizer 17.0％ Dehydrating agent 2.0％ GCC 57.0％ PCC 1.5％ thixotropic agents 0.9％ Coupling agent 1.5％ catalyst 0.1％

[0069] Prepare the moisture-curing sealant according to the formula shown in Table 2, using the following specific method:

[0070] GCC, PCC, silane-terminated polyether resin, coupling agent, plasticizer, and thixotropic agent are added to the mixing tank and stirred evenly using a dual planetary mixer until there are no particles in the mixture in the tank. Then, the system is heated to 110-130℃ and vacuumed for 2-3 hours. Then, the temperature is lowered to below 60℃, the vacuuming is stopped, and dehydrating agent and catalyst are added. After stirring evenly, the adhesive is degassed and the sealant is obtained, resulting in a moisture-curing sealant.

[0071] The moisture-curing sealants prepared using the silane-terminated polyether resins of Examples 3 and 4, and Comparative Examples 1 and 2, respectively, were tested for relevant performance indicators such as extrudability, surface drying time, tensile strength, elongation at break, and hardness. Specific tests were conducted according to the following standards:

[0072] 1. Extrudability: Refer to GB16776-2005 "Silicone Structural Sealants for Buildings";

[0073] 2. Surface drying time: Refer to GB / T13477.5-2002 "Test methods for building sealant materials - Part 5: Determination of surface drying time";

[0074] 3. Tensile strength: Refer to GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber";

[0075] 4. Elongation at break: Refer to GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber";

[0076] 5. Hardness: Refer to GBT531.1-2008 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Part 1: Shore hardness test (Shore hardness)".

[0077] The results are shown in Table 3.

[0078] Table 3. Performance test results of moisture-curing sealant

[0079]

[0080] Combining the results shown in Tables 1 and 3, it can be seen that, under the same number-average molecular weight, the silane-terminated polyether resin of Example 3 has a lower dynamic viscosity, which makes the extrusion performance of the moisture-curing sealant made from it significantly better than that made from the moisture-curing sealant made from the silane-terminated polyether resin prepared by the conventional diisocyanate chain extension method. The tensile strength and elongation at break are even better than those of conventional products with aromatic ring reinforcement, which is of great significance for the preparation of sealing materials.

[0081] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a low-viscosity, non-toxic silane-terminated polyether resin, characterized in that: A polymer was prepared by using succinic anhydride and polyether polyols with a molecular weight of 2000~8000 g / mol as raw materials under the catalysis of an acid catalyst; N-hydroxysuccinimide and carbodiimide catalysts were added to the polymer and stirred to react; an aminoalkoxysilane coupling agent was added dropwise to the system for end capping, thus obtaining the silane-terminated polyether resin.

2. The method for preparing the low-viscosity, non-toxic silane-terminated polyether resin according to claim 1, characterized in that: Specifically, the following steps are included: S1. Place the polyether polyol under vacuum at 110~120℃ for more than 1 hour to dehydrate it; add succinic anhydride and acid catalyst to the polyether polyol, stir and heat to 120~180℃ under nitrogen atmosphere, keep it at this temperature for 4~6 hours. During the reaction, wait until the system changes from turbid to homogeneous and transparent and the acid value remains basically unchanged, continue to keep it at this temperature for 0.5~1.5 hours, degas and cool to below 60℃, filter and discharge to obtain the polymer; S2. Add N-hydroxysuccinimide and carbodiimide catalyst to the polymer obtained in step S1, stir and heat to 120~140℃ under nitrogen atmosphere, stabilize at the temperature for 0.5~1h, cool down to 70~80℃, add aminoalkoxysilane coupling agent dropwise to the system, keep at the temperature for 1.5~2h, cool down to below 60℃, filter, and obtain the silane-terminated polyether resin.

3. The method for preparing the low-viscosity, non-toxic silane-terminated polyether resin according to claim 1 or 2, characterized in that: The acid catalyst is one or more of phosphoric acid, phosphorous acid, p-toluenesulfonic acid, phosphotungstic acid, and strong acid cation exchange resin.

4. The method for preparing the low-viscosity, non-toxic silane-terminated polyether resin according to claim 1 or 2, characterized in that: The carbodiimide catalyst is one or more of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, and N-cyclohexyl-N′-(2-morpholinoethyl)carbodiimide methyl p-toluenesulfonate.

5. The method for preparing the low-viscosity, non-toxic silane-terminated polyether resin according to claim 1 or 2, characterized in that: The polyether polyol is one of PPG, PEG, a mixture of PPG and PEG, or a copolymer of EG and PG.

6. The method for preparing the low-viscosity, non-toxic silane-terminated polyether resin according to claim 1 or 2, characterized in that: The molar ratio of the polyether polyol to succinic anhydride is 1:1.5~1.

8.

7. The method for preparing the low-viscosity, non-toxic silane-terminated polyether resin according to claim 1 or 2, characterized in that: The amount of acid catalyst used is 0.5 to 1.5% of the total weight of all mixtures in step S1.

8. The method for preparing the low-viscosity, non-toxic silane-terminated polyether resin according to claim 1 or 2, characterized in that: The molar ratio of the carboxyl group in the polymer, the amino group in the aminoalkoxy coupling agent, the N-hydroxysuccinimide, and the carbodiimide catalyst is 1:2:2:2~2.

5.

9. A low-viscosity, non-toxic silane-terminated polyether resin, characterized in that: It is prepared by any one of the preparation methods described in claims 1 to 8.

Images