Polyamide curing agent for curing end epoxy polyether silicone oil and preparation method thereof

Abstract

This invention discloses a polyamide curing agent and its preparation method for curing epoxy polyether silicone oil, relating to the field of curing agent technology. The curing agent is a polyamide oligomer with a specific structure consisting of alternating links of malonic acid and hexamethylenediamine in its main chain, with primary amine groups at the ends. The preparation method includes synthesizing malonic acid and hexamethylenediamine in an alcohol solvent via an amidation reaction under the action of a catalyst. The main chain structure of the curing agent of this invention is highly similar to that of the polyamide substrate, allowing it to form a homo-eutectic interpenetrating structure with the substrate during the finishing process. Furthermore, it constructs a dense and stable three-dimensional network through cross-linking reactions between the primary amines at both ends and the epoxy groups of the epoxy polyether silicone oil. This design fundamentally solves the problems of poor compatibility, easy migration, insufficient wash resistance, and hardening of the feel caused by traditional polyetheramine curing agents with polyamides, achieving a simultaneous and significant improvement in wash resistance, flexibility, and interfacial bonding strength during the finishing of polyamide materials.

Description

Technical Field

[0001] This invention relates to the field of curing agent technology, specifically to a polyamide curing agent for curing epoxy polyether silicone oil and its preparation method. Background Technology

[0002] End-terminated epoxy polyether silicone oil is an important polymer material with a polysiloxane backbone modified at both ends by polyether segments and active epoxy groups. This material can undergo ring-opening crosslinking reactions with amine curing agents at relatively low temperatures, thereby forming a functional finishing layer on the surface of polyamide fibers, films, and engineering plastics. This imparts a durable soft feel, hydrophilic properties, and excellent low-temperature tactile sensitivity to the substrate, thus showing broad application prospects in high-end textiles and specialty coatings.

[0003] In current industrial practice, polyetheramine compounds are commonly used as curing agents for epoxy-terminated polyether silicone oils. However, these curing agents, such as ED-600 and ED-900, have a molecular skeleton mainly composed of flexible polyether segments, which differ significantly from the crystalline regions of the polyamide substrate in chemical polarity and structure, leading to insufficient compatibility. The cured silicone oil film and the polyamide matrix are mainly bonded by weak van der Waals forces, resulting in low interfacial bonding strength. In actual use, especially under high temperature or repeated washing conditions, the silicone oil film is prone to migration, frosting, and even peeling, severely affecting the durability of its function. To improve wash resistance, existing technologies attempt to introduce rigid aromatic amine compounds or additional fiber-binding agents into the curing system. While these methods can improve the retention rate of silicone oil on the fiber surface to some extent, they often come at the cost of sacrificing material flexibility, resulting in a stiff feel and significantly increased bending stiffness in the treated polyamide fibers, losing their original softness. Furthermore, these improvement schemes are mostly designed for cellulose fibers such as cotton, and their mechanism of action depends on the interaction with the hydroxyl groups of the fibers. They are not applicable to polyamide substrates that lack active hydroxyl groups and cannot fundamentally solve the interfacial compatibility problem between the polyamide crystalline region and the silicone coating.

[0004] To address the aforementioned problems, this invention provides a polyamide curing agent for curing epoxy polyether silicone oil and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a polyamide curing agent and its preparation method for curing epoxy polyether silicone oil, so as to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A polyamide curing agent for curing epoxy polyether silicone oil, characterized in that: its chemical structural formula is: ; ; ; ; Any one of them.

[0007] A method for preparing a polyamide curing agent for curing epoxy polyether silicone oil, characterized by comprising the following steps: Step 1: Dissolve malonic acid in isopropanol, stir, add hexamethylenediamine and the remaining isopropanol, and replace with nitrogen; then heat and use isopropanol-water azeotropic reflux to remove water; Step 2: Turn off reflux, add tetraisopropyl titanate, heat and hold, evacuate, and evaporate isopropanol from the system; heat, depressurize, and hold again. Step 3: Purge with nitrogen and cool down, then cool and filter the material to obtain the polyamide curing agent.

[0008] Furthermore, in step one, the molar ratio of hexamethylenediamine to malonic acid is (1.5-5.5):1.

[0009] Furthermore, in step one, the temperature is raised to 80-85℃ and refluxed for 30-40 minutes.

[0010] Furthermore, in step two, the temperature is raised to 160-170℃, held for 1-2 hours, and a vacuum is drawn to evaporate the isopropanol from the system; the temperature is then raised again to 180-190℃, and the pressure is reduced while holding the temperature.

[0011] Furthermore, in step two, the specific parameters for vacuuming are to vacuum to 40-50 kPa, the specific parameters for pressure reduction are to reduce the pressure to 2 kPa, and to maintain the temperature for 50-70 minutes.

[0012] Furthermore, in step two, the mass of tetraisopropyl titanate added is 0.9-1.1% of the total mass of the reactants malonic acid and hexamethylenediamine.

[0013] Furthermore, in step three, the specific operation of nitrogen purging and cooling is as follows: nitrogen is purged to break the vacuum and cool down, and the material is cooled to 85-90℃.

[0014] Furthermore, in step three, a 100-150 mesh filter is used for filtration.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. Regarding interfacial compatibility, the main chain structure of the curing agent of this invention contains amide bonds and hexamethylene sequences. Its chemical composition and chain length are highly similar to those of the polyamide substrate. It can achieve dual anchoring through homo-penetrating and hydrogen bonding, which significantly improves the interfacial bonding force and effectively solves the problems of oil film migration caused by polarity differences in traditional polyetheramines.

[0016] 2. In terms of flexibility, after the primary amine groups at both ends of the curing agent react with the terminal epoxy polyether silicone oil, a β-hydroxy secondary amine structure with low steric hindrance and flexible chain segments is generated. At the same time, the short-chain structural units in the main chain keep the crosslinking network at a low glass transition temperature, thereby ensuring the excellent softness and resilience of the finished polyamide material while achieving effective crosslinking.

[0017] 3. Regarding wash resistance and durability, the highly reactive primary amine end groups ensure the formation of a dense three-dimensional cross-linked network at low temperatures, and the amide bonds in the main chain themselves possess excellent hydrolysis resistance. This dense and hydrolysis-resistant network structure effectively blocks the penetration of water molecules; moreover, it avoids the high-temperature melt polycondensation step required for traditional polyamide synthesis, effectively reducing the reaction temperature and significantly decreasing potential side reactions and raw material decomposition caused by high temperatures, making the synthesis process more controllable. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is the chemical structural formula of polyamide curing agent compound A obtained in Example 1 of the present invention.

[0019] Figure 2 This is the chemical structural formula of polyamide curing agent compound B obtained in Example 2 of the present invention.

[0020] Figure 3 This is the chemical structural formula of polyamide curing agent compound C obtained in Example 3 of the present invention.

[0021] Figure 4 This is the chemical structural formula of polyamide curing agent compound D obtained in Example 4 of the present invention.

[0022] Figure 5 This is the chemical structural formula of polyamide curing agent compound E obtained in Example 5 of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1:

[0025] Step 1: Dissolve 0.1 mol malonic acid in 100 g isopropanol, stir at room temperature for 30 min until clear, add 0.15 mol hexamethylenediamine and 100 g isopropanol, and purge with nitrogen for 15 min; then heat to 82 °C and reflux with isopropanol-water azeotropic solution for 30 min to remove moisture introduced by the raw materials. Step 2: Turn off reflux, add 0.3g tetraisopropyl titanate, heat to 160℃ and hold for 1.5h, gradually evacuate to 40kPa, evaporate isopropanol from the system; then heat to 180℃, reduce the vacuum to 2kPa, and hold for 60min. Step 3: Purge with nitrogen to break the vacuum and cool down, then cool the material to 90°C; after heat filtration through a 100-mesh filter, a pale yellow viscous liquid compound A is obtained, which is the polyamide curing agent used for curing epoxy polyether silicone oil; The chemical structural formula of compound A is: .

[0026] Example 2: Step 1: Dissolve 0.1 mol malonic acid in 100 g isopropanol, stir at room temperature for 30 min until clear, add 0.25 mol hexamethylenediamine and 100 g isopropanol, and purge with nitrogen for 15 min; then heat to 82 °C and reflux with isopropanol-water azeotropic solution for 30 min to remove moisture introduced by the raw materials. Step 2: Turn off reflux, add 0.4g tetraisopropyl titanate, heat to 160℃ and hold for 1.5h, gradually evacuate to 40kPa, evaporate isopropanol from the system; then heat to 180℃, reduce the vacuum to 2kPa, and hold for 60min. Step 3: Purge with nitrogen to break the vacuum and cool down, then cool the material to 90°C; after heat filtration through a 100-mesh filter, a pale yellow viscous liquid compound B is obtained, which is the polyamide curing agent used for curing epoxy polyether silicone oil. The chemical structural formula of compound B is: .

[0027] Example 3: Step 1: Dissolve 0.1 mol malonic acid in 100 g isopropanol, stir at room temperature for 30 min until clear, add 0.35 mol hexamethylenediamine and 100 g isopropanol, and purge with nitrogen for 15 min; then raise the temperature to 82 °C and use isopropanol-water azeotropic reflux for 30 min to remove the water brought in by the raw materials. Step 2: Turn off reflux, add 0.5g tetraisopropyl titanate, heat to 160℃ and hold for 1.5h, gradually evacuate to 40kPa, evaporate isopropanol from the system; then heat to 180℃, reduce the vacuum to 2kPa, and hold for 60min. Step 3: Purge with nitrogen to break the vacuum and cool down, then cool the material to 90°C; after heat filtration through a 100-mesh filter, a pale yellow viscous liquid compound C is obtained, which is the polyamide curing agent used for curing epoxy polyether silicone oil; The chemical structural formula of compound C is: .

[0028] Example 4: Step 1: Dissolve 0.1 mol malonic acid in 100 g isopropanol, stir at room temperature for 30 min until clear, add 0.45 mol hexamethylenediamine and 100 g isopropanol, and purge with nitrogen for 15 min; then raise the temperature to 82 °C and use isopropanol-water azeotropic reflux for 30 min to remove the water brought in by the raw materials. Step 2: Turn off reflux, add 0.6g tetraisopropyl titanate, heat to 160℃ and hold for 1.5h, gradually evacuate to 40kPa, evaporate isopropanol from the system, then heat to 180℃, reduce the vacuum to 2kPa, and hold for 60min. Step 3: Purge with nitrogen to break the vacuum and cool down, then cool the material to 90°C. After hot filtration through a 100-mesh filter, a pale yellow viscous liquid compound D is obtained, which is the polyamide curing agent used for curing epoxy polyether silicone oil. The chemical structural formula of compound D is: .

[0029] Example 5: Step 1: Dissolve 0.1 mol malonic acid in 100 g isopropanol, stir at room temperature for 30 min until clear, add 0.55 mol hexamethylenediamine and 100 g isopropanol, and purge with nitrogen for 15 min; then heat to 82 °C and reflux with isopropanol-water azeotropic solution for 30 min to remove moisture introduced by the raw materials. Step 2: Turn off reflux, add 0.7g tetraisopropyl titanate, heat to 160℃ and hold for 1.5h, gradually evacuate to 40kPa, evaporate isopropanol from the system; then heat to 180℃, reduce the vacuum to 2kPa, and hold for 60min. Step 3: Purge with nitrogen to break the vacuum and cool down, then cool the material to 90°C; after heat filtration through a 100-mesh filter, a pale yellow viscous liquid is obtained, which is compound E, the polyamide curing agent used for curing epoxy polyether silicone oil. The chemical structural formula of compound E is: .

[0030] Comparative Example 1: Synthesis test experiments were conducted using a conventional polyetheramine curing agent (purchase item number: P108073-2.5L; available from Aladdin Reagents).

[0031] Comparative Example 2: In the synthesis, the molar ratio of hexamethylenediamine to malonic acid was set to 1:1, and the rest was the same as in Example 1; specifically: Step 1: Dissolve 0.1 mol malonic acid in 100 g isopropanol, stir at room temperature for 30 min until clear, add 0.1 mol hexamethylenediamine and 100 g isopropanol, and purge with nitrogen for 15 min; then heat to 82 °C and reflux with isopropanol-water azeotropic solution for 30 min to remove moisture introduced by the raw materials. Step 2: Turn off reflux, add 0.3g tetraisopropyl titanate, heat to 160℃ and hold for 1.5h, gradually evacuate to 40kPa, evaporate isopropanol from the system; then heat to 180℃, reduce the vacuum to 2kPa, and hold for 60min. Step 3: Purge with nitrogen to break the vacuum and cool down, then cool the material to 90°C; pass it through a 100-mesh filter for heat filtration to obtain the curing agent.

[0032] Comparative Example 3: In the synthesis, the amount of tetraisopropyl titanate catalyst added was reduced to 0.1 g, while the rest was the same as in Example 1; specifically: Step 1: Dissolve 0.1 mol malonic acid in 100 g isopropanol, stir at room temperature for 30 min until clear, add 0.15 mol hexamethylenediamine and 100 g isopropanol, and purge with nitrogen for 15 min; then heat to 82 °C and reflux with isopropanol-water azeotropic solution for 30 min to remove moisture introduced by the raw materials. Step 2: Turn off reflux, gradually evacuate to 40 kPa, and evaporate the isopropanol in the system; then raise the temperature to 180℃, reduce the vacuum to 2 kPa, and hold for 60 min; Step 3: Purge with nitrogen to break the vacuum and cool down, then cool the material to 90°C; pass it through a 100-mesh filter for heat filtration to obtain the curing agent.

[0033] experiment: The products obtained in Examples 1-5 and Comparative Examples 1-3 of this invention were used as curing agents for synthesizing block polyether silicone oils, replacing the traditional polyether amine curing agents required in the original synthesis, to obtain novel block silicone oils. The process for producing the novel block silicone oil is as follows, including the following steps: Step 1: Add 1200g of epoxy polyether silicone oil, 25g of curing agent and 300g of monobutyl ether to a four-necked flask, and stir under nitrogen for 30 minutes at room temperature; Step 2: Heat the reaction mixture to 80℃ and maintain this temperature for 4 hours, keeping the entire reaction under reflux and nitrogen purging. Step 3: After 4 hours, cool the mixture to below 60℃, add 15g of glacial acetic acid, and stir until homogeneous to obtain the desired product. A novel block silicone oil; the performance of the obtained novel block silicone oil was tested under the same fabric substrate and the same finishing process. The specific process includes the following steps: Step 1: Emulsify the block silicone oils prepared in Examples 1-5 and Comparative Examples 1-3 into an emulsion. Specifically, mix 100g of block silicone oil with 5% monobutyl ether and 5% emulsifier, and slowly add 220g of pure water to form an emulsion. Step 2: Cut several pieces of nylon fabric of the same size, wash them with clean water, and then dehydrate them with a rolling mill for later use; Step 3: Take the emulsions from Examples 1-5 and Comparative Examples 1-3 respectively, add water to prepare an auxiliary agent of 10g / L, and pour them into the rolling mill in sequence to treat the nylon fabric by padding. Step 4: Place the treated fabric into a setting machine and dry it at 180℃ before conducting subsequent performance tests; (1) Compatibility 1. Melt torque reduction (Haake internal mixing method) Experimental apparatus: HaakePolylab QC internal mixer (Rheomix3000E mixing chamber, chamber volume 69cm³); Experimental consumables: nitrogen cylinder (≥99.9%, with pressure reducing valve), PTFE shovel, disposable copper brush, high-temperature resistant gloves; Experimental steps: Set the chamber temperature to 270℃ and the rotation speed to 0 rpm, purge with nitrogen for 5 minutes to remove oxygen; after the temperature stabilizes, zero the torque sensor; pour in 55.0g of dried slices at once, immediately press down the upper stopper and lock it; start the rotation speed at 50 rpm and record the torque-time curve; after 10 minutes, read the steady-state torque value T. sample T was measured using the same type of nylon fabric under the same conditions. blank As a blank control; Torque reduction (%) = (T blank -T sample )÷T blank×100%, and keep one decimal place; immediately after stopping the machine, clean the cavity with a copper brush, and then run it empty for 2 minutes with a small amount of nylon cleaning material to remove the residue.

[0034] 2. Filter pressure rise ΔP Experimental instrument: Dynisco LCR-7001 melt indexer; Experimental consumables: 15µm sintered stainless steel filter screen (Ø25mm, effective filtration area 3.8cm²), 0.5mm die, high-temperature grease, torque wrench 10N·m; Experimental steps: Use a torque wrench to insert the filter screen and die into the bottom of the barrel in sequence, ensuring that there is no resin residue on the sealing surface; Set the temperature to 270℃ and hold for 15 minutes, while simultaneously purging the barrel with nitrogen at 0.05MPa for 5 minutes. Pour in 15g of dried slices, manually compact, and preheat for 4 minutes. Control the piston speed at 0.05mm / s, extrude 3g of washing material first, and discard it. Add 20g of material again, maintain the piston speed at 0.05mm / s, and continuously extrude 2000g of melt. The PLC records the inlet pressure every 0.5s, and takes the average pressure P of the last 100g. final Meanwhile, P was measured using the same type of nylon at the same mesh and temperature. blank ; Calculate ΔP=P final –P blank The result is rounded to two decimal places; the die filter screen is removed while it is still hot, and the screen is heated in a muffle furnace at 550℃ for 30 minutes to remove carbon.

[0035] (2) Detailed steps for flexibility testing 1. Monofilament bending modulus (three-point bending method) Experimental instruments: Instron 3345 universal testing machine, 5N load cell; Experimental consumables: Three-point bending fixture: lower span 10mm, loading head radius R=0.1mm. Melt-spun monofilament: Ø25µm, length 50mm, quantity 20 strands; Experimental steps: Set the temperature and humidity to 23℃ and 50%RH and place it in a constant temperature and humidity chamber for 24 hours; place the monofilament at the center of the lower span, with the loading head just contacting the filament surface (preload 0.1cN); control the beam speed at 0.5mm / min, sampling frequency at 10Hz, and record the force-displacement curve until the maximum force reaches 20mN or the wire breaks; calculate the bending modulus E using the formula: E = (L³ × m) ÷ (4bd³); where L = 10mm (span), m = slope of the force-displacement linear segment (N / mm²). -1 b = equivalent width of the filament bundle (for a single filament, take d = 25µm, b = d), d = thickness 25µm; take the average value of 20 filaments, with a standard deviation of 1-5%, otherwise retest until n = 30.

[0036] 2. Knot strength retention rate Experimental instruments: Instron 3345 universal testing machine, 100N sensor; Experimental consumables: Knotting mold: PTFE column Ø2mm, ensuring knot diameter 1.0±0.1mm; Experimental steps: Take a 100mm long monofilament and attach 5mm wide tape to both ends to prevent slippage; pre-tie a single knot on the PTFE column, controlling the knot width to 0.5mm, tighten it, and then remove it; set the gauge length to 50mm, the speed to 20mm / min, and record the breaking strength F. knot When the monofilaments in the same batch are not knotted, the F value is measured. straight ; Calculate the retention rate using the formula: Retention Rate (%) = F kno t÷F straight ×100%, n=10, take the arithmetic mean.

[0037] (3) Washability test 1. Boiling water shrinkage rate Experimental apparatus: constant temperature water bath (accuracy ±0.5℃); Experimental consumables: Stainless steel wire frame: 500mm circumference, tension-free suspension; steel ruler (0.5mm resolution); tension clamp 0.1cN / dtex; Experimental steps: The stranded wire was placed at 23℃ for 2 minutes under a pretension of 0.1 cN / dtex, and the circumference L0 was measured (accurate to 0.5 mm). The stranded wire to be tested was quickly immersed in 100℃ distilled water for 30 minutes. After being removed, it was hung naturally at room temperature for 30 minutes, then transferred to a 60℃ oven to dry for 60 minutes, and then conditioned at 23℃ for 4 hours. The final length L1 was measured under a tension of 0.1 cN / dtex. The shrinkage rate was calculated using the formula: Shrinkage rate (%) = (L0 – L1) / L0 × 100%, n = 3, and the average value was taken.

[0038] 2. Color fastness to soap washing (AATCC61-2A) Experimental apparatus: SDL Atlas M228C wash resistance tester; Experimental consumables: 500mL stainless steel container, 90mm in diameter, containing 50 6mm stainless steel balls, 0.37% (w / v) WOB standard detergent, liquor ratio 1:50; Experimental steps: Take 5g of fiber sample and 5g of pure cotton wash cloth of the same weight, totaling 10g; add 150mL of washing liquid preheated to 40℃, and place a steel ball in; wash at 40℃ and 40rpm for 45min. Rinse with tap water at 40℃ for 2min, rinse with cold water for 2min, and then dehydrate for 1min; hang at room temperature, away from light, and air dry at 50-60℃. Compare the result with the ISO105-A03 gray scale and take the average value.

[0039] 3. Strong retention rate after 10 cycles Experimental equipment: Miele WMB120 drum washing machine, standard cotton program 40℃, spin speed 600rpm, spin dry for 5min; Experimental consumables: Washing cloth: pure cotton plain cloth of the same weight, total load 2kg; Detergent: IECA* standard laundry detergent 20g / time; Experimental steps: The tensile strength of 10 monofilaments was measured according to GB / T14337, yielding F0. The monofilaments were subjected to a complete cycle of washing, dehydration, and rotary drying (60℃) 10 times. After the 10th drying cycle, the filaments were conditioned at 23℃ and 50%RH for 24 hours. Ten more monofilaments were then tested according to the same standard, yielding F... 10 ; Calculated using the formula: Retention rate (%) = F 10 The result is calculated as F0 × 100%, rounded to one decimal place. All the data obtained are shown in Table 1 below.

[0040] Conclusion: The data above shows that when the polyamide curing agent provided by this invention is used to finish polyamide fabrics with epoxy polyether silicone oil, as the molar ratio of hexamethylenediamine to malonic acid increases from 1.5 to 5.5 (Examples 1-5), the density of terminal amine groups in the system increases, the degree of reaction with the PET terminal carboxyl groups improves, and the compatibility index shows a monotonically improving trend. The flexural modulus decreases and the knot strength retention rate increases, proving that the compliant segment, i.e., the long-chain polyamide salt, is successfully embedded in the PET molecular chain, significantly improving fiber flexibility. Simultaneously, the boiling water shrinkage rate decreases, and the washing fastness and cyclic strength retention rate increase, indicating that the crosslinking density between molecular chains increases, and the water wash resistance is simultaneously improved.

[0041] Comparative Example 1 uses a traditional polyetheramine curing agent. Compared with Example 1, its compatibility, flexibility and washability are significantly reduced, indicating that the main chain with a polyamide-like structure designed in this invention has excellent water resistance and flexibility.

[0042] In Comparative Example 2, the molar ratio of hexamethylenediamine to malonic acid was set to 1:1 during the synthesis of the curing agent. Compared with Example 1, the compatibility, flexibility, and washability of the resulting product were all deteriorated to varying degrees. This indicates that when an excess of hexamethylenediamine was not used, the reaction product should theoretically be a polyamide with both ends capped by carboxyl groups (-COOH) or a mixture of carboxyl and amine groups, rather than the terminal bisamine (-NH2) of the present invention, and therefore the effect was poor.

[0043] Comparative Example 3 did not use tetraisopropyl titanate catalyst during the synthesis of the curing agent. Compared with Example 1, the performance indicators of its product were significantly reduced, indicating that the amidation reaction rate is extremely slow without a catalyst, and the conversion rate is very low within the same reaction time. The product is a mixture of a large amount of unreacted raw materials, oligomers, and a very small amount of the target product, with a very low amine value, resulting in poor performance in all aspects.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A polyamide curing agent for curing epoxy polyether silicone oil, characterized in that: The chemical structural formula is: ； ； ； ； Any one of them.

2. A method for preparing a polyamide curing agent for curing epoxy polyether silicone oil, characterized in that: Includes the following steps: Step 1: Dissolve malonic acid in isopropanol, stir, add hexamethylenediamine and the remaining isopropanol, and replace with nitrogen; then heat and use isopropanol-water azeotropic reflux to remove water; Step 2: Turn off reflux, add tetraisopropyl titanate, heat and hold, evacuate, and evaporate isopropanol from the system; heat, depressurize, and hold again. Step 3: Purge with nitrogen and cool down, then cool and filter the material to obtain the polyamide curing agent.

3. The method for preparing the polyamide curing agent for curing terminal epoxy polyether silicone oil according to claim 2, characterized in that: In step one, the molar ratio of hexamethylenediamine to malonic acid is (1.5-5.5):

1.

4. The method for preparing the polyamide curing agent for curing epoxy polyether silicone oil according to claim 2, characterized in that: In step one, the temperature is raised to 80-85℃ and refluxed for 30-40 minutes.

5. The method for preparing the polyamide curing agent for curing epoxy polyether silicone oil according to claim 2, characterized in that: In step two, the temperature is raised to 160-170℃ and held for 1-2 hours. Vacuum is then applied to evaporate the isopropanol from the system. The temperature is then raised again to 180-190℃ and the pressure is reduced while holding the temperature.

6. The method for preparing the polyamide curing agent for curing epoxy polyether silicone oil according to claim 2, characterized in that: In step two, the specific parameters for vacuuming are to vacuum to 40-50 kPa, the specific parameters for depressurization are to depressurize to 2 kPa, and the temperature is maintained for 50-70 minutes.

7. The method for preparing the polyamide curing agent for curing terminal epoxy polyether silicone oil according to claim 2, characterized in that: In step two, the mass of tetraisopropyl titanate added is 0.9-1.1% of the total mass of the reactants malonic acid and hexamethylenediamine.

8. The method for preparing the polyamide curing agent for curing epoxy polyether silicone oil according to claim 2, characterized in that: In step three, the specific operation of nitrogen purging and cooling is as follows: nitrogen is purged to break the vacuum and cool down, and the material is cooled to 85-90℃.

9. The method for preparing the polyamide curing agent for curing terminal epoxy polyether silicone oil according to claim 2, characterized in that: In step three, a 100-150 mesh filter is used for filtration.

10. The application of the polyamide curing agent according to any one of claims 1-9 in the curing of end-epoxy polyether silicone oil.

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