A hyperbranched polysiloxane toughening agent, a preparation method thereof and application of the hyperbranched polysiloxane toughening agent in preparing an epoxy resin matrix of a glass steel pipe

Abstract

The application belongs to the technical field of epoxy resin, and particularly relates to a hyperbranched polysiloxane toughening agent, a preparation method thereof and application of the toughening agent in preparation of an epoxy resin matrix of a glass steel pipeline. The hyperbranched polysiloxane toughening agent containing amino groups is prepared by addition reaction of hydroxyl-terminated polyether modified silicone oil and toluene diisocyanate to prepare an intermediate, and then reaction of the intermediate with a chain extender diethanolamine. The toughening agent provided by the application has a hyperbranched three-dimensional structure, has Si-O-Si flexible chain segments in the molecule, and contains amino groups in the molecular chain. The toughening agent has excellent compatibility with the epoxy resin, can effectively improve the brittleness of the crosslinked network of the epoxy resin, and can improve the impact resistance of the resin while having little influence on the tensile strength and heat resistance of the resin. The epoxy resin containing the toughening agent can be used in the manufacture of glass steel pipelines for oil fields, and can effectively improve the toughness of the existing glass steel pipelines.

Description

Technical Field

[0001] This invention belongs to the field of epoxy resin technology, specifically relating to a hyperbranched polysiloxane toughening agent, its preparation method, and its application in preparing epoxy resin matrix for fiberglass pipes. Background Technology

[0002] Epoxy fiberglass reinforced plastic (GFRP) pipes are composite material pipes made by winding and curing continuous glass fiber as the reinforcing material and epoxy resin as the matrix. Due to their high pressure resistance (up to 30 MPa), corrosion resistance, light weight, resistance to scaling, and ease of molding, epoxy GFRP pipes are widely used in surface gathering and transportation systems in domestic oilfields, mainly for oil and gas mixed transportation, water injection and transportation, oil gathering and transportation, and gas gathering and transportation. High-pressure GFRP pipes used in oilfields generally use bisphenol A type epoxy resin (E54) as the matrix material and methyltetrahydrophthalic anhydride as the curing agent, prepared by high-temperature curing. The cured product of this epoxy resin is relatively brittle and has poor impact resistance. Therefore, when used in oilfields, GFRP pipes are prone to cracking when exposed to external mechanical impacts, terrain undulations, and settlement, leading to frequent leakage incidents. To ensure the safe service of epoxy GFRP pipes, it is necessary to improve the toughness of the epoxy resin matrix used in the pipes and enhance its impact resistance.

[0003] Currently, commonly used methods for toughening epoxy resins include: rubber elastomer toughening, rigid nanoparticle toughening, block copolymer toughening, and thermoplastic toughening. However, rubber elastomer toughening significantly reduces the mechanical strength and heat resistance of the epoxy resin. Rigid nanoparticle toughening is prone to agglomeration, affecting the toughening effect. Block copolymer toughening introduces impurities, and thermoplastic toughening leads to increased resin viscosity and decreased processability. Therefore, it is necessary to find a resin matrix toughening agent suitable for epoxy fiberglass pipes that improves the toughness of the epoxy resin without significantly reducing its mechanical strength and heat resistance (glass transition temperature Tg), and provides a moderate viscosity and good processability after toughening.

[0004] Hyperbranched polysiloxanes (HBPSi) have highly branched molecules with flexible, three-dimensional molecular chains that can effectively absorb and disperse external impact energy, thus improving the impact toughness of epoxy resins. Furthermore, they exhibit low molecular chain entanglement, low viscosity, good compatibility with epoxy resins, and good thermal stability, which are beneficial for improving the mechanical strength and heat resistance of epoxy resins, resulting in a good overall toughening effect. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a hyperbranched polysiloxane toughening agent, its preparation method, and its application in preparing epoxy resin matrices for fiberglass pipes. This invention provides an amino-containing hyperbranched polysiloxane toughening agent, which, when added to epoxy resin, can improve the impact resistance of the epoxy resin with minimal impact on tensile strength and heat resistance, thus achieving effective toughening of the epoxy resin.

[0006] The technical solution provided by this invention is as follows:

[0007] A method for preparing a hyperbranched polysiloxane toughening agent includes the following steps:

[0008] 1) Mix the two raw materials, hydroxyl-terminated polyether modified silicone oil and toluene diisocyanate, evenly and then heat to react;

[0009] 2) After the partial reaction in step 1), the catalyst dibutyltin dilaurate is added to the reactants to continue the reaction. Finally, the chain extender diolamine is added to the reactants to catalyze the reaction. After the reaction is completed, the mixture is cooled to room temperature to obtain a pale yellow liquid product, which is the amino-containing hyperbranched polysiloxane toughening agent (HBPSi). The diolamine is diethanolamine, dipropanolamine or dibutanolamine, preferably diethanolamine.

[0010] The structural formula of the hydroxyl-terminated polyether modified silicone oil is as follows:

[0011]

[0012] Hydroxyl-terminated polyether modified silicone oils can be selected from existing technologies, such as Dow Corning's SF-8427 product with a molecular weight of 2000 g / mol.

[0013] The principle of the above preparation method is as follows:

[0014]

[0015] The above technical solution uses hydroxyl-terminated polyether modified silicone oil and toluene diisocyanate to prepare an intermediate, which is then reacted with the chain extender diethanolamine to obtain an amino-containing hyperbranched polysiloxane toughening agent.

[0016] The obtained toughening agent has a hyperbranched three-dimensional structure with Si-O-Si flexible segments in the molecule and amino groups in the molecular chain. It has excellent compatibility with epoxy resin, can effectively improve the brittleness of the epoxy resin crosslinking network, enhance the impact resistance of the resin, and has little effect on the tensile strength and heat resistance of the resin.

[0017] Specifically, the preparation method of the hyperbranched polysiloxane toughening agent includes the following steps: Hydroxyl-terminated polyether modified silicone oil and toluene diisocyanate (DBTDL) are added to a container, with a molar ratio of hydroxyl-terminated polyether modified silicone oil to TDI of 1:(1.8–2.2). After the reactants are mixed evenly, heating begins, with the reaction temperature controlled at 65–95℃ and the reaction time 40–90 min. Then, dibutyltin dilaurate (DBTDL) is added to the reactants, with a molar ratio of hydroxyl-terminated polyether modified silicone oil to DBTDL of 1:(0.0008–0.003), and the catalytic reaction continues for 40–80 min. Finally, diethanolamine (DEA) is added to the reactants, with a molar ratio of hydroxyl-terminated polyether modified silicone oil to DEA of 1:(1–2), and the catalytic reaction continues for 40–80 min. After the reaction is completed and cooled to room temperature, a pale yellow liquid product is obtained, which is the amino-containing hyperbranched polysiloxane (HBPSi).

[0018] Specifically, the reaction temperature in step 2) is the same as the reaction temperature in step 1).

[0019] The two-step reaction can be carried out at the same temperature, which simplifies the preparation process.

[0020] The present invention also provides a hyperbranched polysiloxane toughening agent prepared according to the above method. This hyperbranched polysiloxane toughening agent has the following structure:

[0021]

[0022] This invention also provides the application of hyperbranched polysiloxane toughening agents for preparing epoxy resin matrices for fiberglass pipes.

[0023] The hyperbranched polysiloxane toughening agent provided by this invention has excellent compatibility with epoxy resin, effectively improving the brittleness of the epoxy resin crosslinking network and enhancing the resin's impact resistance, while having minimal impact on the resin's tensile strength and heat resistance. Epoxy resins using this toughening agent can be used in the manufacture of fiberglass pipes for oil fields, effectively improving the toughness of existing fiberglass pipes.

[0024] The specific method for preparing the epoxy resin matrix for fiberglass pipes includes the following steps: adding the hyperbranched polysiloxane toughening agent to E54 epoxy resin and mixing it evenly, then adding the curing agent methyltetrahydrophthalic anhydride and the curing accelerator benzyltriethylammonium chloride, reacting and curing to obtain the epoxy resin matrix for fiberglass pipes.

[0025] Specifically, the amount of hyperbranched polysiloxane toughening agent added is 4% to 11% of the epoxy resin mass;

[0026] Specifically, the mass ratio of epoxy resin, curing agent, and accelerator is 1:(0.7~0.9):(0.01~0.03).

[0027] Specifically, cure at 70–90℃ for 9–10 min, at 120–140℃ for 14–146 min, and at 160–190℃ for 28–32 min.

[0028] Beneficial effects:

[0029] This invention provides a method for preparing a hyperbranched polysiloxane toughening agent for epoxy resin matrices in fiberglass pipes. The method involves preparing an intermediate through an addition reaction between hydroxyl-terminated polyether-modified silicone oil and toluene diisocyanate, followed by reaction with the chain extender diethanolamine to obtain an amino-containing hyperbranched polysiloxane toughening agent. The toughening agent provided by this invention has a hyperbranched three-dimensional structure with Si-O-Si flexible segments in its molecule and amino groups in the molecular chain. It exhibits excellent compatibility with epoxy resin, effectively improving the brittleness of the epoxy resin crosslinking network and enhancing the resin's impact resistance, while having minimal impact on the resin's tensile strength and heat resistance. The epoxy resin containing the toughening agent can be used in the manufacture of fiberglass pipes for oil fields, effectively improving the toughness of existing fiberglass pipes. Attached Figure Description

[0030] Figure 1 This is the infrared spectrum of the hyperbranched polysiloxane toughening agent prepared in Example 1.

[0031] Figure 2 This is a scanning electron microscope (SEM) image of the cross-section of the sample of the hyperbranched polysiloxane-toughened epoxy resin cured product prepared in Example 1 after impact damage.

[0032] Figure 3 This is a scanning electron microscope image of the cross-section of the sample after impact damage to the original resin system. Detailed Implementation

[0033] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0034] Example 1

[0035] (1) 200 g (0.1 mol) of hydroxyl-terminated polyether modified silicone oil (molecular weight 2000 g / mol) and 34.83 g (0.2 mol) of toluene diisocyanate were added to a 500 mL three-necked flask. The raw materials were mixed evenly with a stirrer, and the temperature was raised to 80 °C. The reaction was carried out at this temperature for 60 min. Then, 0.11 g (0.0002 mol) of dibutyltin dilaurate catalyst was added to continue the catalytic reaction for 60 min. Finally, 15.77 g (0.15 mol) of diethanolamine chain extender was added, and the reaction was carried out for 60 min. After the reaction was completed, the temperature was lowered to room temperature to obtain a hyperbranched polysiloxane containing amino groups. The molecular weight was approximately 7200 g / mol.

[0036] (2) Take 100g of E54 epoxy resin and add 8g of the prepared hyperbranched polysiloxane to the resin and stir evenly. The viscosity of the resin did not change significantly during stirring. Then add 80g of curing agent methyltetrahydrophthalic anhydride and 2g of curing accelerator benzyltriethylammonium chloride. Pour the mixed resin mixture into a polytetrafluoroethylene mold for preparing impact and tensile specimens, and cure at 80℃ for 10min, 130℃ for 15min, and 170℃ for 30min. Test the impact strength, tensile strength, and glass transition temperature of the prepared specimens.

[0037] Example 2

[0038] (1) 300 g (0.05 mol) of hydroxyl-terminated polyether modified silicone oil (molecular weight 6000 g / mol) and 18.29 g (0.105 mol) of toluene diisocyanate were added to a 500 mL three-necked flask. The raw materials were mixed evenly with a stirrer, and the temperature was raised to 90 °C. The reaction was carried out at this temperature for 40 min. Then, 0.08 g (0.0001 mol) of dibutyltin dilaurate catalyst was added to continue the catalytic reaction for 40 min. Finally, 9.46 g (0.09 mol) of diethanolamine chain extender was added, and the reaction was carried out for 50 min. After the reaction was completed, the temperature was lowered to room temperature to obtain a yellow liquid with a molecular weight of approximately 6500 g / mol.

[0039] (2) Take 100g of E54 epoxy resin, add 6g of the prepared hyperbranched polysiloxane to the resin and stir evenly. The resin viscosity did not change significantly during stirring. Then add 75g of curing agent methyltetrahydrophthalic anhydride and 2.5g of curing accelerator benzyltriethylammonium chloride. Pour the mixed resin mixture into a polytetrafluoroethylene mold for preparing impact and tensile specimens, and cure at 75℃ for 10min, 140℃ for 15min, and 180℃ for 30min. Perform corresponding tests on the prepared specimens.

[0040] Hyperbranched polysiloxanes contain amino functional groups, which can improve their compatibility with epoxy resins. The Si-O-Si flexible segments in the molecular structure and the cavities formed by the hyperbranched three-dimensional structure can effectively toughen epoxy resins, improving their impact strength, while having minimal impact on the tensile strength and heat resistance (glass transition temperature Tg). Through the above specific embodiments, epoxy resins toughened with hyperbranched polysiloxanes were obtained, and the test data for their impact strength, tensile strength, and glass transition temperature are shown in Table 1. It can be seen that the impact strength of the toughened epoxy resins in Examples 1 and 2 increased by 61.59% and 49.84% respectively compared to the original resin, while the tensile strength decreased by only 4.9% and 6.15%, and the glass transition temperature remained essentially unchanged.

[0041] Table 1. Test data of impact strength, tensile strength, and glass transition temperature of toughened epoxy resin.

[0042] Test Project Original resin system Example 1: Toughened Resin Example 2: Toughened Resin <![CDATA[Impact strength (KJ / m 2 )]]> 9.71 15.69 14.55 Tensile strength (MPa) 67.52 64.21 63.37 Glass transition temperature (°C) 120.32 119.27 120.14

[0043] As can be seen from the table above, the appropriate addition of hyperbranched polysiloxane toughening agent can significantly improve the impact strength and toughness of epoxy resin without significantly affecting the tensile strength and glass transition temperature.

[0044] like Figure 1 As shown in the infrared spectrum of the hyperbranched polysiloxane toughening agent prepared in Example 1, it can be seen that at 800 cm⁻¹... -1 and 1017cm -1 The peak at 1100 cm⁻¹ represents the stretching vibration peak of the Si-O-Si bond in hyperbranched polysiloxanes. -1 The peak value for the stretching vibration of COC is 1475 cm⁻¹. -1 1530cm-1 and 1600cm -1 The peak at 3350 cm⁻¹ represents the stretching vibration of the benzene ring. -1 The peak at this point represents the stretching vibration of -OH, indicating that the raw materials reacted to form hyperbranched polysiloxanes.

[0045] like Figure 2 As shown in the scanning electron microscope image of the fracture surface of the sample after impact damage of the hyperbranched polysiloxane-toughened epoxy resin cured product, it can be clearly seen that the fracture surface is rough and has a ductile fracture morphology, which is caused by the hyperbranched polysiloxane-toughened epoxy resin.

[0046] like Figure 3 As shown, the scanning electron microscope image of the sample fracture surface after impact damage of the original resin system shows a smooth fracture surface, which is a brittle fracture morphology, because the original resin system is relatively brittle.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An application of a hyperbranched polysiloxane toughening agent, characterized in that: The specific steps for preparing the hyperbranched polysiloxane toughening agent used in the preparation of the epoxy resin matrix for fiberglass pipes are as follows: 1) Mix the two raw materials, hydroxyl-terminated polyether modified silicone oil and toluene diisocyanate, evenly and then heat to react; 2) After the partial reaction in step 1), the catalyst dibutyltin dilaurate is added to the reactants to catalyze the reaction. Finally, the chain extender diolamine is added to the reactants to continue the reaction. After the reaction is completed, the mixture is cooled to room temperature to obtain a pale yellow liquid product, which is the amino-containing hyperbranched polysiloxane toughening agent. The structural formula of the hydroxyl-terminated polyether modified silicone oil is as follows: 。 2. The application according to claim 1, characterized in that, Includes the following steps: The hyperbranched polysiloxane toughening agent is added to E54 epoxy resin and mixed evenly. Then, the curing agent methyltetrahydrophthalic anhydride and the curing accelerator benzyltriethylammonium chloride are added and the mixture is reacted and cured to obtain the epoxy resin matrix of fiberglass pipe.

3. The application according to claim 2, characterized in that: The amount of hyperbranched polysiloxane toughening agent added is 4% to 11% of the epoxy resin mass; The mass ratio of epoxy resin, curing agent, and curing accelerator is 1:(0.7~0.9):(0.01~0.03).

4. The application according to claim 2, characterized in that: The reaction curing process includes the following stages: curing at 70~90℃ for 9-10 min, curing at 120~140℃ for 14-146 min, and curing at 160~190℃ for 28-32 min.

5. The application according to claim 1, characterized in that, In step 1): Hydroxyl-terminated polyether modified silicone oil and toluene diisocyanate were mixed at a molar ratio of 1:(1.8~2.2); The reaction temperature is controlled at 65~95℃; The reaction time is 40-90 minutes.

6. The application according to claim 1, characterized in that, In step 2), the molar ratio of hydroxyl-terminated polyether modified silicone oil to catalyst is 1:(0.0008~0.003).

7. The application according to claim 1, characterized in that, In step 2): The molar ratio of hydroxyl-terminated polyether modified silicone oil to diolamine is 1:(1~2); The diolamine is diethanolamine, dipropanolamine, or dibutanolamine; The reaction temperatures were controlled between 65 and 95°C. Each reaction time is 40-80 minutes.

8. The application according to claim 1, characterized in that: The reaction temperature in step 2) is the same as that in step 1).

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