Preparation method of rapidly-cured multi-silane-terminated silane modified polyether resin

Abstract

The invention provides a preparation method of fast-curing multi-silane-terminated silane modified polyether resin, which comprises the following steps: carrying out addition reaction on multi-silane-terminated alkoxy silane with a secondary amino structure and diisocyanate to obtain a silane intermediate containing an isocyanate group; and carrying out an end-capping reaction on the silane intermediate and hydroxyl-terminated polyether to obtain the silane modified polyether resin. Compared with the prior art, the invention has the following beneficial effects: 1, the environmental protection property is prominent; 2, the curing speed is high; 3, the mechanical property is excellent; 4, the viscosity adjustability is high; and 5, the application range is wide.

Description

Technical Field

[0001] This invention relates to the field of silane-modified polyether resin technology, and more particularly to a method for preparing a rapidly curing polysilane-terminated silane-modified polyether resin. Background Technology

[0002] Silane-modified polyethers (MS Polymers), as a class of high-performance polymer materials, have been widely used in building sealing, industrial bonding, and automotive assembly due to their characteristics such as not releasing isocyanates during curing, excellent weather resistance, and good compatibility with various substrates. Currently, the mainstream silane-modified polyether resin curing systems on the market rely on metal catalysts (such as tin, bismuth, and titanium) to promote the hydrolysis and condensation reaction of terminal silanes. Among them, tin catalysts are widely used due to their high catalytic activity, but these catalysts have problems such as high toxicity, significant environmental risks, and strict environmental regulations. Even with the use of alternative catalysts such as bismuth and titanium, it is still impossible to completely solve the problems of heavy metal residues and environmental hazards, which is inconsistent with the current trend of green chemical engineering. To address the issue of dependence on metal catalysts, some companies have developed curing systems based on silane technology, such as Wacker Chemie's α-silane structure resins. However, these resins suffer from limitations in molecular structure design, narrow viscosity adjustment range, and difficulty in flexibly controlling mechanical properties, severely restricting their application scenarios. Furthermore, existing silane-modified polyether resins are mostly monosilane end-group structures, resulting in insufficient curing reactivity and long surface drying times (typically several hours), failing to meet the demands of efficient construction. Therefore, developing a novel silane-modified polyether resin that requires no metal catalyst, exhibits high curing activity, adjustable viscosity, and excellent mechanical properties has become a pressing technical problem to be solved in this field. Summary of the Invention

[0003] The first objective of this invention is to disclose a method for preparing a rapidly curing polysilane-terminated silane-modified polyether resin, which is environmentally friendly: it completely eliminates dependence on metal catalysts, leaves no heavy metal residues during the curing process, complies with environmental regulations, and reduces environmental risks; it has a fast curing speed: the polysilane-terminated structure has high reactivity, and with only 1.0 wt% aminosilane accelerator added, the surface drying time can be shortened to 1-5 hours; if a composite system of "0.1 wt% DBTDL + 0.5 wt% KH792" is used, the surface drying time is further shortened to 2-10 minutes, meeting the requirements of efficient construction; it has excellent mechanical properties: the segmental structure brought by diisocyanate increases the crosslinking density, and the tensile strength of the cured resin reaches 0.65-0.9 MPa, and the Shore A hardness is 36-55, which is significantly better than conventional monosilane-terminated MS resin; it has strong viscosity adjustability: by changing the molecular weight (2000-8000) of the terminal hydroxyl polyether and the reaction ratio, a viscosity of 3,000-200,000 mPa·s can be achieved. With a wide range of viscosity control, it can adapt to the needs of different products such as medium and low viscosity sealants and high viscosity structural adhesives. Wide range of applications: It can be directly used to prepare environmentally friendly sealants, structural adhesives and elastomers, and can also be used as a core substrate in green building materials, automobile assembly, electronic packaging and other fields, with strong adaptability.

[0004] To achieve the above objectives, this invention discloses a method for preparing a rapidly curing polysilane-terminated silane-modified polyether resin, comprising the following steps: Step 1: A polysilane-terminated alkoxysilane with a secondary amino structure is added to a diisocyanate to obtain a silane intermediate containing an isocyanate group; Step 2: The silane intermediate is subjected to a capping reaction with the hydroxyl-terminated polyether to obtain the silane-modified polyether resin.

[0005] In some embodiments, the polysilane-terminated alkoxysilane having a secondary amino structure is a bis(trialkoxysilylpropyl)amine compound or a derivative thereof, with the general formula: , where R¹ is a low-carbon alkyl group.

[0006] In some embodiments, the bis(trialkoxysilylpropyl)amine compounds or their derivatives include, but are not limited to: bis(trimethoxysilylpropyl)amine, bis(triethoxysilylpropyl)amine, bis(dimethoxymethylsilylpropyl)amine, bis(triethoxysilylethyl)amine, secondary amino polysiloxanes containing silane side groups, and amino silane derivatives containing two or more silane groups.

[0007] In some embodiments, the diisocyanate is selected from one or more of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

[0008] In some embodiments, the reaction temperature in step two is 50–90°C, and the reaction is carried out using a catalyst, which is a tin salt, bismuth salt, or titanium salt catalyst, in an amount of 0.01%–0.03%.

[0009] In some embodiments, in step one, the molar ratio of the polysilane-terminated alkoxysilane with a secondary amino structure to the diisocyanate is 1.0:1 to 1.2:1 to ensure that the polysilane-terminated alkoxysilane is in excess.

[0010] In some embodiments, in step two, the molar ratio of the hydroxyl groups (-OH) in the terminal hydroxyl polyether to the isocyanate groups (-NCO) in the silane intermediate is 1.0:1 to 1.2:1.

[0011] In some embodiments, the number-average molecular weight (Mn) of the terminal hydroxyl polyether is 2000 to 8000.

[0012] In some embodiments, the viscosity of the silane-modified polyether resin is 3000–200000 mPa·s (25°C).

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. Outstanding environmental friendliness: Completely eliminates dependence on metal catalysts, leaves no heavy metal residues during the curing process, complies with environmental regulations, and reduces environmental risks; 2. Fast curing speed: The polysilane end-group structure has high reactivity. When only 1.0 wt% aminosilane accelerator is added, the surface drying time can be shortened to 1-5 h. If the "0.1 wt% DBTDL + 0.5 wt% KH792" composite system is used, the surface drying time can be further shortened to 2-10 min, meeting the requirements of efficient construction. 3. Excellent mechanical properties: The segmental structure brought by diisocyanate increases the crosslinking density, and the tensile strength of the cured resin reaches 0.65~0.9MPa, and the Shore A hardness is 36~55, which is significantly better than conventional monosilane-terminated MS resin. 4. High viscosity adjustability: By changing the molecular weight (2000-8000) of the terminal hydroxyl polyether and the reaction ratio, a wide range of viscosity control from 3,000 to 80,000 mPa·s can be achieved, which can meet the needs of different products such as medium and low viscosity sealants and high viscosity structural adhesives. 5. Wide range of applications: It can be directly used to prepare environmentally friendly sealants, structural adhesives and elastomers, and can also be used as a core substrate in green building materials, automobile assembly, electronic packaging and other fields, with strong adaptability. Attached Figure Description

[0014] Figure 1The data represent the performance test data of the modified polyether resins obtained in each embodiment and comparative example. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, it should be noted that these embodiments are not intended to limit the present invention. Any equivalent substitutions or replacements in function, method, or structure made by those skilled in the art based on these embodiments are within the scope of protection of the present invention.

[0016] Example 1

[0017] (IPDI / bis(trimethoxysilylpropyl)amine / Mn≈2000) Under nitrogen protection and anhydrous conditions, 222 g (1.0 mol) of isophorone diisocyanate (IPDI) was added to the reactor and stirred until homogeneous at room temperature (25°C). 278 g (1.1 mol) of bis(trimethoxysilylpropyl)amine was slowly added dropwise, and the dropping rate was controlled so that the system temperature did not exceed 30°C. After the addition was completed, the reaction was stirred for 3 h to obtain an alicyclic silane intermediate containing free -NCO. The system was heated to 70°C, and 2000g (1.0 mol) of hydroxyl-terminated polyether (polypropylene glycol) with a number-average molecular weight Mn≈2000 and 0.01% bismuth neodecanoate were added. The reaction was maintained at 70-80°C for 2 hours. After the free -NCO content was determined to be 0 by di-n-butylamine titration, the mixture was cooled to room temperature and discharged. The resulting silane-modified polyether resin was designated as P1. Example 2

[0018] (HDI / bis(trimethoxysilylpropyl)amine / Mn≈2000) Under nitrogen protection and anhydrous conditions, 168 g (1.0 mol) of hexamethylene diisocyanate (HDI) was added to the reactor and stirred at 25–30 °C; 252 g (1.0 mol) of bis(trimethoxysilylpropyl)amine was slowly added dropwise, and the reaction was carried out for 3 h after the addition was completed to obtain an aliphatic silane intermediate. Add 2000g (1.0 mol) of hydroxyl-terminated polyether with Mn≈2000 and 0.01% of bismuth neodecanoate, keep the reaction at 70℃ for 2h, and after the free -NCO is detected to be completely reacted, cool and discharge the material. The resulting silane-modified polyether resin is denoted as P2.

[0019] Example 3

[0020] (IPDI / bis(triethoxysilylpropyl)amine / Mn≈4000) Under nitrogen protection and anhydrous conditions, 222 g (1.0 mol) of IPDI was added to the reactor, and 306 g (1.0 mol) of bis(triethoxysilylpropyl)amine was slowly added dropwise with stirring. The reaction was carried out for 3 h to obtain an ethoxy silane intermediate. Add 4000g (1.0 mol) of hydroxyl-terminated polyether with Mn≈4000 and 0.01% of bismuth neodecanoate, and keep the reaction at 75-80℃ for 2.5h. After the free -NCO is completely reacted, cool and discharge the material. The resulting silane-modified polyether resin is designated as P3.

[0021] Example 4

[0022] (IPDI / HDI composite / bis(trimethoxysilylpropyl)amine / Mn≈4000) Under nitrogen protection and anhydrous conditions, a mixture of 111 g (0.5 mol) IPDI and 84 g (0.5 mol) HDI was added to the reactor and heated to 30 °C. 278 g (1.05 mol) bis(trimethoxysilylpropyl)amine was slowly added dropwise, and the reaction was carried out for 3 h to obtain a complex silane intermediate.

[0023] Add 4000g (1.0 mol) of hydroxyl-terminated polyether with Mn≈4000 and 0.01% of bismuth neodecanoate, and keep the reaction at 70-80℃ for 2.5h. After the free -NCO is completely reacted, cool and discharge the material. The resulting silane-modified polyether resin is designated as P4.

[0024] Example 5

[0025] (HDI / bis(triethoxysilylpropyl)amine / Mn≈8000) Under nitrogen protection and anhydrous conditions, 168 g (1.0 mol) of HDI was added to the reactor, and 336 g (1.1 mol) of bis(triethoxysilylpropyl)amine was slowly added dropwise with stirring. The reaction was carried out for 2.5 h to obtain an aliphatic ethoxy silane intermediate. Add 8000g (1.0 mol) of hydroxyl-terminated polyether with Mn≈8000 and 0.01% tetraisopropyl titanate, keep the mixture at 75℃ for 3h, and after the free -NCO is detected to be completely reacted, cool and discharge the material. The resulting silane-modified polyether resin is designated as P5.

[0026] Example 6

[0027] (Example of low viscosity modification) The silane intermediate was prepared according to the method of Example 3, with the difference that 4800g (1.2 mol) of terminal hydroxyl polyether with Mn≈4000 and 0.01% of bismuth neodecanoate were added to the end-capping reaction to make the molar ratio of -OH to -NCO 1.2:1. The resulting silane-modified polyether resin was designated as P6. Comparative Example 1 (Conventional monosilane-terminated MS resin) Commercially available conventional monosilane-terminated silane-modified polyether resins. The modified polyether resins obtained in the examples and comparative examples were tested under the following conditions: curing conditions: 23℃ / 50% RH; formulation: 100 parts of matrix resin; KH792: as an aminosilane accelerator; DBTDL: dibutyltin dilaurate; surface drying time: time until the surface is no longer tacky to the touch; mechanical properties: tested 7 days after complete curing.

[0028] Combination Figure 1 The test results are analyzed as follows: Compared to conventional MS resins with monosilane end groups, the silane-modified polyether resins prepared in Examples 1-6 of this invention can achieve surface drying within 1-5 hours with only 1.0 wt% KH792 added. Under the action of the composite accelerating system (0.1 wt% DBTDL + 0.5 wt% KH792), the surface drying time can be further shortened to 2-10 minutes, exhibiting significant rapid curing characteristics. Simultaneously, due to the introduction of polysilane groups at the ends, a three-dimensional network structure with higher crosslinking density can be formed during moisture curing. The tensile strength of the resin of this invention is increased to 0.65-0.9 MPa, and the Shore A hardness is increased to 36-55, significantly higher than the comparative Shore A 25. Correspondingly, the elongation at break is reduced to the range of 50-200%, indicating that the system is transforming from a flexible sealant to a medium-to-high modulus structural sealing / adhesive material.

[0029] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

[0030] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a rapidly curing polysilane-terminated silane-modified polyether resin, characterized in that, Includes the following steps: Step 1: A polysilane-terminated alkoxysilane with a secondary amino structure is added to a diisocyanate to obtain a silane intermediate containing an isocyanate group; Step 2: The silane intermediate is subjected to a capping reaction with the hydroxyl-terminated polyether to obtain the silane-modified polyether resin.

2. The method for preparing the rapidly curing polysilane-terminated silane-modified polyether resin according to claim 1, characterized in that, The polysilane-terminated alkoxysilane with a secondary amino structure is a bis(trialkoxysilylpropyl)amine compound or its derivative, with the general formula: , where R¹ is a low-carbon alkyl group.

3. The method for preparing the rapidly curing polysilane-terminated silane-modified polyether resin according to claim 2, characterized in that, The bis(trialkoxysilylpropyl)amine compounds or their derivatives include, but are not limited to: bis(trimethoxysilylpropyl)amine, bis(triethoxysilylpropyl)amine, bis(dimethoxymethylsilylpropyl)amine, bis(triethoxysilylethyl)amine, secondary amino polysiloxanes containing silane side groups, and amino silane derivatives containing two or more silane groups.

4. The method for preparing the rapidly curing polysilane-terminated silane-modified polyether resin according to claim 1, characterized in that, The diisocyanate is selected from one or more of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

5. The method for preparing the rapidly curing polysilane-terminated silane-modified polyether resin according to claim 1, characterized in that, The reaction temperature in step one is -10 to 50°C, and the reaction is carried out under anhydrous conditions; the reaction temperature in step two is 50 to 90°C, and a catalyst is used in the reaction. The catalyst is a tin salt, bismuth salt, or titanium salt catalyst, and the amount used is 0.01% to 0.03%.

6. The method for preparing the rapidly curing polysilane-terminated silane-modified polyether resin according to claim 1, characterized in that, In step one, the molar ratio of the polysilane-terminated alkoxysilane with a secondary amino structure to the diisocyanate is 1.0:1 to 1.2:1 to ensure that the polysilane-terminated alkoxysilane is in excess.

7. The method for preparing the rapidly curing polysilane-terminated silane-modified polyether resin according to claim 1, characterized in that, In step two, the molar ratio of the hydroxyl groups (-OH) in the terminal hydroxyl polyether to the isocyanate groups (-NCO) in the silane intermediate is 1.0:1 to 1.2:

1.

8. The method for preparing the rapidly curing polysilane-terminated silane-modified polyether resin according to claim 1, characterized in that, The number-average molecular weight (Mn) of the terminal hydroxyl polyether is 2000 to 8000.

9. The method for preparing the rapidly curing polysilane-terminated silane-modified polyether resin according to claim 1, characterized in that, The viscosity of the silane-modified polyether resin is 3000–200000 mPa·s (25°C).

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