Ultralow-temperature-resistant organic silicon modified epoxy adhesive and preparation method thereof

Abstract

The invention discloses an ultralow-temperature-resistant organic silicon modified epoxy adhesive and a preparation method thereof. The preparation method of the adhesive comprises the following steps: firstly, preparing an organic silicon epoxy monomer by taking bis (aminopropyl)-terminated polydimethylsiloxane and epoxy chloropropane as raw materials; 2-amino-4-hydroxy-6-methylpyrimidine and 1, 1 '-carbonyldiimidazole are mixed to obtain a compound UPy-CDI, and the compound UPy-CDI reacts with polyether diamine to obtain a curing agent containing quadruple hydrogen bonds; and finally, mixing the curing agent containing quadruple hydrogen bonds and the organosilicon epoxy monomer in proportion, and heating and curing to obtain the organosilicon modified epoxy adhesive. The low-temperature toughness of the epoxy resin is improved through cooperation of organic silicon flexible chain segments and multiple hydrogen bonds, and the epoxy resin can keep high bonding performance in an ultralow-temperature working environment.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to an ultra-low temperature resistant organosilicon-modified epoxy adhesive and a preparation method thereof. Background Art

[0002] Epoxy resin adhesives have been widely used in the fields of electronics, machinery, construction, aerospace, etc. due to their excellent mechanical properties, electrical insulation properties, bonding properties and chemical corrosion resistance. With the rapid development of aerospace, superconducting technology, and national defense industry, the demand for adhesives used in ultra-low temperature environments continues to increase. Epoxy resins have the problems of poor toughness and high brittleness at room temperature. As the temperature decreases, the freezing of polymer chain segments will make the polymer more brittle, greatly affecting its bonding properties.

[0003] In order to enhance the low-temperature bonding performance of epoxy resin, one strategy is to introduce flexible segments into the cross-linked network of epoxy resin. Polysiloxane (PDMS) refers to a class of polymers with Si-O units as the main chain, which has excellent properties such as high and low temperature resistance, aging resistance, electrical insulation and hydrophobicity. Introducing PDMS as a flexible segment into the epoxy resin structure can effectively improve the toughness of epoxy resin. Another effective strategy is to develop supramolecular polymer adhesives, such as forming strong and dense interfacial interactions with various substrates through hydrogen bonds. Summary of the invention

[0004] The purpose of the present invention is to provide an ultra-low temperature resistant organosilicon modified epoxy adhesive and a preparation method thereof. The preparation method combines the two strategies described in the background art, introduces flexible organosilicon segments and multiple hydrogen bonds into the epoxy resin structure at the same time, and constructs an ultra-low temperature resistant organosilicon epoxy adhesive.

[0005] The adhesive utilizes a combination of flexible silicone segments and non-covalent interactions (multiple hydrogen bonds) to construct an ultra-low temperature resistant silicone epoxy adhesive.

[0006] To achieve the above object, the present invention adopts the following technical solution: An ultra-low temperature resistant organosilicon modified epoxy adhesive is prepared from the following raw materials in molar parts: 20 parts of organosilicon epoxy monomer (TEA-1000) and 12-28 parts of a curing agent containing quadruple hydrogen bonds (UPy-D400).

[0007] The preparation method of the ultra-low temperature resistant silicone epoxy adhesive comprises the following steps: 1) Preparation of silicone epoxy monomer (TEA-1000) Dissolve the bisaminopropyl-terminated polydimethylsiloxane in anhydrous ethanol, then drop epichlorohydrin, heat at 50-60°C for 5-6h, cool to 30-40°C, add sodium hydroxide solution, react for 1.8-2.2h, remove the precipitate by filtration, and then remove the solvent and excess epichlorohydrin by rotary evaporation. Wash the resulting mixture with hexane, remove the solvent by rotary evaporation, and dry the product at 50-60°C to obtain a light yellow liquid, i.e., silicone epoxy monomer (TEA-1000); 2) Preparation of a curing agent containing quadruple hydrogen bonds (UPy-D400) 2-1) 2-amino-4-hydroxy-6-methylpyrimidine and 1,1′-carbonyldiimidazole are mixed, dissolved with dimethyl sulfoxide at 70-90° C., and then reacted for 2-3 hours. The reaction mixture is cooled to room temperature and filtered, and washed with acetone 3-4 times to obtain white powder UPy-CDI; 2-2) UPy-CDI was dissolved in polyether diamine at 30-50°C, reacted at 30-50°C for 11.5-12.5h, the mixture was cooled to room temperature, added to 0°C n-hexane, stirred for 10-20 min, the insoluble liquid was separated, and dissolved in dichloromethane; repeated 3-5 times (adding 0°C n-hexane, stirring for 10-20 min, and dissolving in dichloromethane) to remove most of the unreacted polyether diamine; the obtained crude product was dissolved in dichloromethane, washed with brine 3-5 times, and then washed with water 1-2 times, the organic phase was collected, and precipitated with anhydrous Na 2 SO 4 The obtained crude product is dried, filtered and concentrated to obtain a curing agent containing quadruple hydrogen bonds; 3) Preparation of silicone-modified epoxy adhesive Add a curing agent containing quadruple hydrogen bonds and an organosilicon epoxy monomer into a single-mouth round-bottom flask and mix evenly, add tetrahydrofuran (THF), reflux and stir at 75-85°C for 8-10 h, degas in a vacuum drying oven at 75-85°C for 30-40 min, pour into a polytetrafluoroethylene mold and cure for 10-12 h, and cool to room temperature to obtain an active epoxy adhesive containing quadruple hydrogen bonds.

[0008] Furthermore, in step 1), the amount of raw materials used to prepare the organosilicon epoxy monomer is as follows: Bisaminopropyl-terminated polydimethylsiloxane 10-30mmol; Epichlorohydrin (ECH) 400-1200mmol; Anhydrous ethanol 100~300mL; Sodium hydroxide aqueous solution (mass fraction 50%) 2g~8g.

[0009] Furthermore, in step 2), the amount of raw materials used to prepare the curing agent containing quadruple hydrogen bonds is as follows: 2-amino-4-hydroxy-6-methylpyrimidine 10-11 g; 1,1′-Carbonyldiimidazole (CDI) 18~19g; Polyether diamine (Jeffamine D400) 267~275g; Dimethyl sulfoxide (DMSO) 300~500 mL; 300-400 mL of dichloromethane (DCM) was used to dissolve the crude product.

[0010] The present invention adopts the above technical scheme, and through the coordinated use of silicone flexible segments and multiple hydrogen bonds, effectively solves the low-temperature brittleness and reduced bonding performance problems of epoxy resin, breaking through the performance limit of traditional epoxy adhesives at ultra-low temperatures; the raw materials prepared by the present invention (PDMS, UPy derivatives) have a high degree of commercialization, are easy to mass produce, and have a high controllability of the synthesis process. They are suitable for ultra-low temperature environments such as aerospace (liquid hydrogen / liquid oxygen storage tank sealing), superconducting equipment, and polar scientific research, and can replace existing low-temperature adhesives, with excellent multi-scenario applicability and market potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the reaction equation for the ultra-low temperature resistant silicone modified epoxy adhesive.

[0012] Figure 2 The TEA-1000 prepared in Example 1 1 H NMR spectrum.

[0013] Figure 3 UPy-D400 prepared in Example 1 1 H NMR spectrum.

[0014] Figure 4 It is the room temperature lap shear strength of the adhesives prepared in Examples 1-5 and Comparative Examples 1-2.

[0015] Figure 5 It is the low temperature lap shear strength of the adhesives prepared in Examples 1-5 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0016] The present invention is described in detail below with reference to specific embodiments.

[0017] In the following examples, the brand of the bis-aminopropyl terminated polydimethylsiloxane is SILONG 8100, and the brand of the polyether diamine is Jeffamine D400. Example 1

[0018] A method for preparing an ultra-low temperature resistant organosilicon-modified epoxy adhesive comprises the following steps: (1) Preparation of TEA-1000: Dissolve bisaminopropyl-terminated polydimethylsiloxane (20 mmol) in ethanol, then add epichlorohydrin (800 mmol) dropwise, heat at 55°C for 5 h, cool to 30°C, and add 4 g of 50% sodium hydroxide solution. After reacting for 2 h, remove the precipitate by filtration, and then remove the solvent and excess epichlorohydrin by rotary evaporation. The resulting mixture is washed with n-hexane, and the solvent is removed by rotary evaporation. The product is dried in a vacuum oven at 60°C for 12 h to obtain a light yellow liquid, namely TEA-1000 (41 mmol).

[0019] (2) Preparation of UPy-D400: 2-Amino-4-hydroxy-6-methylpyrimidine (10 mmol) and 1,1′-carbonyldiimidazole (112 mmol) were dissolved in 400 ml of dimethyl sulfoxide at 80°C and stirred for 2 h. The reaction mixture was cooled to room temperature and filtered, and the filter cake was washed three times with acetone to obtain white UPy-CDI powder (60 mmol).

[0020] UPy-CDI powder (60 mmol) was dissolved in polyether diamine (594 mmol) at 40 °C and reacted for 12 h. The mixture was cooled to room temperature and added to n-hexane (500 mL) at 0 °C. After stirring for another 10 minutes, the insoluble liquid was separated and dissolved in 50 ml of dichloromethane; this was repeated 3-5 times (adding n-hexane at 0 °C, stirring for 10-20 min, and dissolving in dichloromethane) to remove most of the unreacted polyether diamine. The crude product was dissolved in 300 mL of dichloromethane and washed with brine (3×200 mL) and water (100 mL). The organic phase was collected and precipitated with anhydrous Na 2 SO 4 The crude product was filtered and concentrated to give UPy-D400 (33 mmol).

[0021] (3) Preparation of adhesive: UPy-D400 (12 mmol) and TEA-1000 (20 mmol) were added to a single-necked round-bottom flask and mixed evenly. 10 ml of tetrahydrofuran was added, and the mixture was refluxed and stirred at 80 ° C for 9 h. The mixture was degassed in a vacuum drying oven at 80 ° C for 30 min, poured into a polytetrafluoroethylene mold and cured for 10-12 h. The mixture was cooled to room temperature to obtain a silicone-modified epoxy adhesive containing quadruple hydrogen bonds.

[0022] Figure 2 This is the NMR image of TEA-1000, proving that TEA-1000 has been successfully synthesized.

[0023] Figure 3This is the NMR image of Upy-D400, proving the successful synthesis of UPy-D400. Example 2

[0024] A method for preparing an ultra-low temperature resistant organosilicon-modified epoxy adhesive comprises the following steps: In this example, 16 mmol of UPy-D400 was added, and the remaining steps were the same as in Example 1. Example 3

[0025] A method for preparing an ultra-low temperature resistant organosilicon-modified epoxy adhesive comprises the following steps: In this example, 20 mmol of UPy-D400 was added, and the remaining steps were the same as in Example 1. Example 4

[0026] A method for preparing an ultra-low temperature resistant organosilicon-modified epoxy adhesive comprises the following steps: In this example, 24 mmol of UPy-D400 was added, and the remaining steps were the same as in Example 1. Example 5

[0027] A method for preparing an ultra-low temperature resistant organosilicon-modified epoxy adhesive comprises the following steps: In this example, 28 mmol of UPy-D400 was added, and the remaining steps were the same as in Example 1. Comparative Example 1

[0028] In this comparative example, Upy-D400 was replaced by Jeffamine M600, and the remaining steps were the same as those in Example 4. Comparative Example 2

[0029] In this comparative example, TEA-1000 was replaced by E-44 (epoxy resin with an epoxy value of 0.44), and the remaining steps were the same as those in Example 4.

[0030] In order to evaluate the use effect of the product, according to the ASTM-D1002 standard, the adhesives of Examples 1-5 and Comparative Examples 1 and 2 were subjected to lap shear tests at room temperature and low temperature. The test results are as follows: Figure 4-5 shown. Figure 4 is the adhesion strength at room temperature, Figure 5 is the low temperature adhesion strength, given by Figure 4 , 5 It can be seen that the silicone-modified epoxy adhesive has excellent adhesion strength under low temperature conditions.

Claims

1. A method for preparing an ultra-low temperature resistant organosilicon-modified epoxy adhesive, characterized in that: It includes the following steps: 1) Preparation of silicone epoxy monomer Dissolve the bisaminopropyl-terminated polydimethylsiloxane in anhydrous ethanol, then drop epichlorohydrin, heat at 50-60°C for 5-6h, cool to 30-40°C, add sodium hydroxide solution, react for 1.8-2.2h, remove the precipitate by filtration, remove the solvent and excess epichlorohydrin by rotary evaporation, wash the resulting mixture with hexane, remove the solvent by rotary evaporation, and then dry to obtain an organosilicon epoxy monomer; 2) Preparation of curing agent containing quadruple hydrogen bonds 2-1) 2-amino-4-hydroxy-6-methylpyrimidine and 1,1′-carbonyldiimidazole are mixed, dissolved with dimethyl sulfoxide at 70-90° C., and then reacted for 2-3 hours. The reaction mixture is cooled to room temperature and filtered, and washed with acetone 3-4 times to obtain UPy-CDI; 2-2) UPy-CDI is dissolved in polyether diamine at 30-50°C, reacted at 30-50°C for 11.5-12.5h, the mixture is cooled to room temperature, added into n-hexane at 0°C, stirred for 10-20 min, the insoluble liquid is separated, and dissolved with dichloromethane; this is repeated 3-5 times to remove most of the unreacted polyether diamine; the obtained crude product is dissolved in dichloromethane, and then washed with brine and water in turn, the organic phase is collected, and dried with anhydrous Na2SO4, the obtained crude product is filtered and concentrated to obtain a curing agent containing quadruple hydrogen bonds; 3) Preparation of silicone-modified epoxy adhesive Add a curing agent containing quadruple hydrogen bonds and an organosilicon epoxy monomer into a single-mouth round-bottom flask and mix evenly, add tetrahydrofuran, reflux and stir at 75-85°C for 8-10 h, pour into a polytetrafluoroethylene mold for curing after drying and degassing, and cool to room temperature to obtain an organosilicon-modified epoxy adhesive containing quadruple hydrogen bonds.

2. The method for preparing a super low temperature resistant organosilicon modified epoxy adhesive according to claim 1, characterized in that: Step 1) The raw material ratios for preparing the organosilicon epoxy monomer are as follows: Bisaminopropyl-terminated polydimethylsiloxane 10-30mmol; Epichlorohydrin 400-1200mmol; Anhydrous ethanol 100~300mL; 2g~8g of 50% sodium hydroxide aqueous solution.

3. The method for preparing a super low temperature resistant organosilicon modified epoxy adhesive according to claim 1, characterized in that: Step 2) The raw material ratios for preparing a curing agent containing quadruple hydrogen bonds are as follows: 2-amino-4-hydroxy-6-methylpyrimidine 10-11 g; 1,1′-Carbonyldiimidazole 18-19 g; Polyether diamine 267~275g; Dimethyl sulfoxide 300~500 mL; 300-400 mL of dichloromethane was used to dissolve the crude product.

4. The method for preparing a super low temperature resistant organosilicon modified epoxy adhesive according to claim 1, characterized in that: Step 2-2) The obtained crude product is dissolved in dichloromethane, washed with brine 3-5 times, and then washed with water 1-2 times.

5. The method for preparing a super low temperature resistant organosilicon modified epoxy adhesive according to claim 1, characterized in that: Step 3) The molar ratio of the organosilicon epoxy monomer to the curing agent containing quadruple hydrogen bonds is 20:12-28.

6. The method for preparing a super low temperature resistant organosilicon modified epoxy adhesive according to claim 1, characterized in that: Step 3) The drying and degassing is carried out in a vacuum drying oven at 75-85°C for 30-40 minutes, and the curing time is 10-12 hours.

7. An ultra-low temperature resistant organosilicon-modified epoxy adhesive obtained according to the preparation method according to any one of claims 1 to 6.

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