A tung oil-based polyurethane type epoxy toughening agent, a preparation method and application thereof

Abstract

A tung oil-based polyurethane epoxy toughening agent, its preparation method, and its application are disclosed. The chemical structure is shown below: R1 is a methyl tungate molecular chain, and R2 is a backbone molecule in diisocyanate. The preparation method involves reacting methyl tungate with diethanolamine to obtain diethanol tungamide; the diethanol tungamide is then reacted with diisocyanate and glycidyl ether to obtain an epoxy-terminated tung oil-based polyurethane epoxy toughening agent. This toughening agent can react with a curing agent, covalently integrating into the epoxy resin curing network, improving the compatibility between the toughening agent and the epoxy resin, and avoiding problems such as decreased material transparency due to phase separation. Furthermore, the structure contains amide, urethane, and conjugated triene structures, which can form sacrificial bonds such as hydrogen bonds and π-π interactions with the epoxy resin matrix. This can improve the toughness of the epoxy resin while mitigating the adverse effects of flexible long carbon chains on the strength and other properties of the epoxy resin.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin toughening, specifically to a tung oil-based polyurethane epoxy toughening agent, its preparation method, and its application. Background Technology

[0002] Epoxy resin (EP) refers to a general term for polymers containing two or more epoxy groups. EP possesses excellent adhesion and electrical insulation properties, chemical resistance, superior thermal stability, and low curing shrinkage, making it widely used in electronics, electrical engineering, chemical corrosion protection, civil engineering, aerospace, automotive machinery, and marine transportation. Uncured epoxy resins are typically viscous liquids (such as E51 and E44) or brittle solids (such as E03 and E06). They can only achieve their intended uses through curing and cross-linking to form a three-dimensional network structure. However, cured epoxy resins, due to their high cross-linking density, suffer from high internal stress, brittleness, and poor impact resistance, limiting their further application. Therefore, toughening modification is particularly important.

[0003] Currently, widely studied epoxy resin toughening agents, such as liquid rubber, thermoplastic resins, thermotropic liquid crystal polymers, and core-shell particles, can significantly improve the toughness of epoxy resins. However, most of these toughening agents are extracted from petroleum, making them non-renewable and expensive. With the construction of a "resource-saving and environmentally friendly society," replacing petroleum-based materials with bio-based materials is imperative. Plant oils and their derivatives contain C18 long chains, which can provide good flexibility to epoxy resins, making them excellent bio-based toughening agents. However, the addition of plant oils and their derivatives can significantly reduce the strength and other properties of epoxy resins. Summary of the Invention

[0004] Technical problem to be solved: In order to solve the problem that oil-based epoxy toughening agents will significantly reduce the strength and other properties of epoxy resin, the present invention provides a tung oil-based polyurethane epoxy toughening agent, its preparation method and application. The tung oil-based polyurethane epoxy toughening agent can significantly improve the toughness of epoxy resin through sacrificial bonds, and weaken the adverse effects of flexible long carbon chains on the strength of epoxy resin, and has good compatibility with epoxy resin.

[0005] Technical solution: A tung oil-based polyurethane epoxy toughening agent, the structure of which is shown below:

[0006]

[0007] R1 is:

[0008] R2 is any of the following groups:

[0009] The preferred structural formula is shown below:

[0010]

[0011] R is:

[0012] The preparation method of tung oil-based polyurethane epoxy toughening agent includes the following steps: (1) Methyl tung oil and diethanolamine are reacted at a molar ratio of 1:(1-2) under vacuum at 60-90℃ for 2-5 hours, with KOH as a catalyst; after the reaction is completed, the product is dissolved in ethyl acetate, excess diethanolamine is removed by washing with water, and ethyl acetate is removed by rotary evaporation to obtain brownish-red transparent liquid diethanol tungamide; (2) Diethanol tungamide is dissolved in ethyl acetate and heated to 40-55℃, and a molar ratio of (1-2) to diethanol tungamide is added dropwise. (2) A diisocyanate of 1:1 was added, and dibutyltin dilaurate was used as a catalyst. The reaction temperature was kept constant during the addition. After the addition was completed, the reaction was carried out for 2-5 hours to obtain an ethyl acetate solution of the intermediate. (3) The ethyl acetate solution of the intermediate was heated to 60-80℃, and glycidyl glycerol with a molar ratio of (1-2):1 with diethanolamine was added dropwise. The reaction temperature was kept constant. After the addition was completed, the reaction was carried out for 2-5 hours. After the reaction was completed, the ethyl acetate was removed by rotary evaporation to obtain a yellow viscous terminal epoxy tung oil-based polyurethane toughening agent.

[0013] In step (1) above, the molar ratio of methyl tungate to diethanolamine was 1:1.5, the reaction temperature was 70℃, and the reaction time was 4 hours.

[0014] The diisocyanate used in step (2) above is any one of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and lysine diisocyanate.

[0015] The molar ratio of diisocyanate to diethanolamide used in step (2) above is 2:1, the reaction temperature is 50℃, and the reaction time is 3 hours.

[0016] The molar ratio of glycidyl ether to diethanolamide used in step (3) above is 2:1, the reaction temperature is 65℃, and the reaction time is 4 hours.

[0017] The application of the tung oil-based polyurethane epoxy toughening agent in the preparation of epoxy resin.

[0018] The specific application method is as follows: the prepared tung oil-based polyurethane epoxy toughening agent is mixed and reacted with liquid epoxy resin, and then an epoxy resin curing agent is added for blending and curing to obtain tung oil-based polyurethane epoxy toughening agent modified epoxy resin material.

[0019] Beneficial effects: (1) The tung oil-based polyurethane epoxy toughening agent has good compatibility with epoxy resin and is easy to disperse.

[0020] (2) The tung oil-based polyurethane epoxy toughening agent contains amide bonds, urethane esters and conjugated trienes in its structure, which can form hydrogen bonds, π-π conjugated and other sacrificial bonds with epoxy resin. These sacrificial bonds break before the covalent bonds break, playing the role of energy dissipation, thereby greatly improving the toughness of epoxy resin.

[0021] (3) The tung oil-based polyurethane epoxy toughening agent contains amide bonds, urethane esters, and conjugated trienes in its structure, which can form sacrificial bonds such as hydrogen bonds and π-π conjugation with epoxy resin. When the material is subjected to external force, the sacrificial bonds can bear part of the force, reducing the adverse effect of flexible long carbon chains on the strength of epoxy resin.

[0022] (4) The tung oil-based polyurethane epoxy toughening agent can react with the curing agent and be connected to the epoxy resin curing network through covalent bonds. It has high stress transfer efficiency and can also reduce the adverse effects of flexible long carbon chains on the strength of epoxy resin.

[0023] (5) The tung oil-based polyurethane epoxy toughening agent uses tung oil as raw material, which reduces production costs and can replace petroleum-based products, thus alleviating the energy crisis. Attached Figure Description

[0024] Figure 1 The images show the infrared spectra of diethanol tung oil amide and terminal epoxy tung oil-based polyurethane. By comparing the infrared spectra of diethanol tung oil amide and terminal epoxy tung oil-based polyurethane, characteristic absorption peaks of the amide group were found in both, and the hydroxyl absorption peak (3377 cm⁻¹) in the infrared spectrum of diethanol tung oil amide was also observed. -1 The characteristic absorption peak of the urethane group (3333 cm⁻¹) appears in the infrared spectrum of the terminal epoxy group tung oil-based polyurethane after the reaction. -1 1702cm -1 1530cm -1 and 1237cm -1 ) and epoxy group absorption peak (910cm) -1 ).

[0025] Figure 2 The NMR spectra of diethanol tungsten amide and terminal epoxy tung oil-based polyurethanes are shown in 1H NMR spectrum. Detailed Implementation

[0026] The present invention will be described in detail below through examples. The embodiments provide detailed implementation methods and specific operating steps, which are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention.

[0027] Example 1

[0028] Methyl tungstate and diethanolamine were reacted at a molar ratio of 1:1.5 under vacuum at 70°C for 4 hours, with KOH as the catalyst at 0.5% of the mass of methyl tungstate. After the reaction was completed, the product was dissolved in ethyl acetate, and excess diethanolamine was removed by washing with water. The ethyl acetate was then removed by rotary evaporation to obtain a brownish-red transparent liquid, diethanol tungstateamide.

[0029] Diethanolamine was dissolved in ethyl acetate and heated to 50°C. Hexamethylene diisocyanate with a molar ratio of 2:1 to diethanolamine was added dropwise, and dibutyltin dilaurate (0.1% by mass of diethanolamine) was added as a catalyst. The reaction temperature was kept constant during the dropwise addition. After the dropwise addition was completed, the reaction was carried out for 3 hours to obtain an ethyl acetate solution of the intermediate.

[0030] The ethyl acetate solution of the intermediate was heated to 65°C, and glycidyl ether was added dropwise at a molar ratio of 2:1 to diethanolamine, while maintaining the reaction temperature constant. After the addition was complete, the reaction was continued for 4 hours. After the reaction was completed, the ethyl acetate was removed by rotary evaporation to obtain a yellow, viscous, terminally epoxy-terminated tung oil-based polyurethane toughening agent.

[0031] A modified epoxy resin with an end-epoxy tung oil-based polyurethane content of 10 wt.% was prepared, and a calculated amount of curing agent D230 was added. After mixing evenly and removing bubbles, the mixture was poured into a preheated mold and cured at 80°C for 3 hours to obtain the epoxy resin material.

[0032] Example 2

[0033] Methyl tungstate and diethanolamine were reacted at a molar ratio of 1:1.5 under vacuum at 70°C for 4 hours, with KOH as the catalyst at 0.5% of the mass of methyl tungstate. After the reaction was completed, the product was dissolved in ethyl acetate, and excess diethanolamine was removed by washing with water. The ethyl acetate was then removed by rotary evaporation to obtain a brownish-red transparent liquid, diethanol tungstateamide.

[0034] Diethanolamine was dissolved in ethyl acetate and heated to 50°C. Hexamethylene diisocyanate with a molar ratio of 2:1 to diethanolamine was added dropwise, and dibutyltin dilaurate (0.1% by mass of diethanolamine) was added as a catalyst. The reaction temperature was kept constant during the dropwise addition. After the dropwise addition was completed, the reaction was carried out for 3 hours to obtain an ethyl acetate solution of the intermediate.

[0035] The ethyl acetate solution of the intermediate was heated to 65°C, and glycidyl ether was added dropwise at a molar ratio of 2:1 to diethanolamine, while maintaining the reaction temperature constant. After the addition was complete, the reaction was continued for 4 hours. After the reaction was completed, the ethyl acetate was removed by rotary evaporation to obtain a yellow, viscous, terminally epoxy-terminated tung oil-based polyurethane toughening agent.

[0036] A modified epoxy resin with an end-epoxy tung oil-based polyurethane content of 20 wt.% was prepared, and a calculated amount of curing agent D230 was added. After mixing evenly and removing bubbles, the mixture was poured into a preheated mold and cured at 80°C for 3 hours to obtain the epoxy resin material.

[0037] Example 3

[0038] Methyl tungstate and diethanolamine were reacted at a molar ratio of 1:1.5 under vacuum at 70°C for 4 hours, with KOH as the catalyst at 0.5% of the mass of methyl tungstate. After the reaction was completed, the product was dissolved in ethyl acetate, and excess diethanolamine was removed by washing with water. The ethyl acetate was then removed by rotary evaporation to obtain a brownish-red transparent liquid, diethanol tungstateamide.

[0039] Diethanolamine was dissolved in ethyl acetate and heated to 50°C. Hexamethylene diisocyanate with a molar ratio of 2:1 to diethanolamine was added dropwise, and dibutyltin dilaurate (0.1% by mass of diethanolamine) was added as a catalyst. The reaction temperature was kept constant during the dropwise addition. After the dropwise addition was completed, the reaction was carried out for 3 hours to obtain an ethyl acetate solution of the intermediate.

[0040] The ethyl acetate solution of the intermediate was heated to 65°C, and glycidyl ether was added dropwise at a molar ratio of 2:1 to diethanolamine, while maintaining the reaction temperature constant. After the addition was complete, the reaction was continued for 4 hours. After the reaction was completed, the ethyl acetate was removed by rotary evaporation to obtain a yellow, viscous, terminally epoxy-terminated tung oil-based polyurethane toughening agent.

[0041] A modified epoxy resin with an end-epoxy tung oil-based polyurethane content of 30 wt.% was prepared, and a calculated amount of curing agent D230 was added. After mixing evenly and removing bubbles, the mixture was poured into a preheated mold and cured at 80°C for 3 hours to obtain the epoxy resin material.

[0042] Example 4

[0043] Methyl tungstate and diethanolamine were reacted at a molar ratio of 1:1.5 under vacuum at 70°C for 4 hours, with KOH as the catalyst at 0.5% of the mass of methyl tungstate. After the reaction was completed, the product was dissolved in ethyl acetate, and excess diethanolamine was removed by washing with water. The ethyl acetate was then removed by rotary evaporation to obtain a brownish-red transparent liquid, diethanol tungstateamide.

[0044] Diethanolamine was dissolved in ethyl acetate and heated to 50°C. Hexamethylene diisocyanate with a molar ratio of 2:1 to diethanolamine was added dropwise, and dibutyltin dilaurate (0.1% by mass of diethanolamine) was added as a catalyst. The reaction temperature was kept constant during the dropwise addition. After the dropwise addition was completed, the reaction was carried out for 3 hours to obtain an ethyl acetate solution of the intermediate.

[0045] The ethyl acetate solution of the intermediate was heated to 65°C, and glycidyl ether was added dropwise at a molar ratio of 2:1 to diethanolamine, while maintaining the reaction temperature constant. After the addition was complete, the reaction was continued for 4 hours. After the reaction was completed, the ethyl acetate was removed by rotary evaporation to obtain a yellow, viscous, terminally epoxy-terminated tung oil-based polyurethane toughening agent.

[0046] A modified epoxy resin with an end-epoxy tung oil-based polyurethane content of 40 wt.% was prepared, and a calculated amount of curing agent D230 was added. After mixing evenly and removing bubbles, the mixture was poured into a preheated mold and cured at 80°C for 3 hours to obtain the epoxy resin material.

[0047] Example 5

[0048] Methyl tungstate and diethanolamine were reacted at a molar ratio of 1:1.5 under vacuum at 70°C for 4 hours, with KOH as the catalyst at 0.5% of the mass of methyl tungstate. After the reaction was completed, the product was dissolved in ethyl acetate, and excess diethanolamine was removed by washing with water. The ethyl acetate was then removed by rotary evaporation to obtain a brownish-red transparent liquid, diethanol tungstateamide.

[0049] Diethanolamine was dissolved in ethyl acetate and heated to 50°C. Hexamethylene diisocyanate with a molar ratio of 2:1 to diethanolamine was added dropwise, and dibutyltin dilaurate (0.1% by mass of diethanolamine) was added as a catalyst. The reaction temperature was kept constant during the dropwise addition. After the dropwise addition was completed, the reaction was carried out for 3 hours to obtain an ethyl acetate solution of the intermediate.

[0050] The ethyl acetate solution of the intermediate was heated to 65°C, and glycidyl ether was added dropwise at a molar ratio of 2:1 to diethanolamine, while maintaining the reaction temperature constant. After the addition was complete, the reaction was continued for 4 hours. After the reaction was completed, the ethyl acetate was removed by rotary evaporation to obtain a yellow, viscous, terminally epoxy-terminated tung oil-based polyurethane toughening agent.

[0051] A modified epoxy resin with an end-epoxy tung oil-based polyurethane content of 50 wt.% was prepared, and a calculated amount of curing agent D230 was added. After mixing evenly and removing bubbles, the mixture was poured into a preheated mold and cured at 80°C for 3 hours to obtain the epoxy resin material.

[0052] Example 6

[0053] Methyl tungstate and diethanolamine were reacted at a molar ratio of 1:1 under vacuum at 70°C for 4 hours, with KOH as the catalyst at 0.5% of the mass of methyl tungstate. After the reaction was completed, the product was dissolved in ethyl acetate, and excess diethanolamine was removed by washing with water. The ethyl acetate was then removed by rotary evaporation to obtain a brownish-red transparent liquid, diethanol tungstateamide.

[0054] Diethanolamine was dissolved in ethyl acetate and heated to 50°C. Hexamethylene diisocyanate with a molar ratio of 2:1 to diethanolamine was added dropwise, and dibutyltin dilaurate (0.1% by mass of diethanolamine) was added as a catalyst. The reaction temperature was kept constant during the dropwise addition. After the dropwise addition was completed, the reaction was carried out for 3 hours to obtain an ethyl acetate solution of the intermediate.

[0055] The ethyl acetate solution of the intermediate was heated to 65°C, and glycidyl ether was added dropwise at a molar ratio of 2:1 to diethanolamine, while maintaining the reaction temperature constant. After the addition was complete, the reaction was continued for 4 hours. After the reaction was completed, the ethyl acetate was removed by rotary evaporation to obtain a yellow, viscous, terminally epoxy-terminated tung oil-based polyurethane toughening agent.

[0056] A modified epoxy resin with an end-epoxy tung oil-based polyurethane content of 10 wt.% was prepared, and a calculated amount of curing agent D230 was added. After mixing evenly and removing bubbles, the mixture was poured into a preheated mold and cured at 80°C for 3 hours to obtain the epoxy resin material.

[0057] Example 7

[0058] Methyl tungstate and diethanolamine were reacted at a molar ratio of 1:1.5 under vacuum at 70°C for 4 hours, with KOH as the catalyst at 0.5% of the mass of methyl tungstate. After the reaction was completed, the product was dissolved in ethyl acetate, and excess diethanolamine was removed by washing with water. The ethyl acetate was then removed by rotary evaporation to obtain a brownish-red transparent liquid, diethanol tungstateamide.

[0059] Diethanolamine was dissolved in ethyl acetate and heated to 40°C. Toluene diisocyanate with a molar ratio of 2:1 to diethanolamine was added dropwise, and dibutyltin dilaurate (0.1% by mass of diethanolamine) was added as a catalyst. The reaction temperature was kept constant during the dropwise addition. After the dropwise addition was completed, the reaction was carried out for 2 hours to obtain an ethyl acetate solution of the intermediate.

[0060] The ethyl acetate solution of the intermediate was heated to 60°C, and glycidyl ether was added dropwise at a molar ratio of 2:1 to diethanolamine, while maintaining the reaction temperature constant. After the addition was complete, the reaction was continued for 3 hours. After the reaction was completed, the ethyl acetate was removed by rotary evaporation to obtain a yellow, viscous, terminally epoxy-terminated tung oil-based polyurethane toughening agent.

[0061] A modified epoxy resin with an end-epoxy tung oil-based polyurethane content of 10 wt.% was prepared, and a calculated amount of curing agent D230 was added. After mixing evenly and removing bubbles, the mixture was poured into a preheated mold and cured at 80°C for 3 hours to obtain the epoxy resin material.

[0062] Example 8

[0063] Methyl tungstate and diethanolamine were reacted at a molar ratio of 1:1.5 under vacuum at 70°C for 4 hours, with KOH as the catalyst at 0.5% of the mass of methyl tungstate. After the reaction was completed, the product was dissolved in ethyl acetate, and excess diethanolamine was removed by washing with water. The ethyl acetate was then removed by rotary evaporation to obtain a brownish-red transparent liquid, diethanol tungstateamide.

[0064] Diethanolamine was dissolved in ethyl acetate and heated to 40°C. Diphenylmethane diisocyanate with a molar ratio of 2:1 to diethanolamine was added dropwise, and dibutyltin dilaurate (0.1% by mass of diethanolamine) was added as a catalyst. The reaction temperature was kept constant during the dropwise addition. After the dropwise addition was completed, the reaction was carried out for 2 hours to obtain an ethyl acetate solution of the intermediate.

[0065] The ethyl acetate solution of the intermediate was heated to 60°C, and glycidyl ether was added dropwise at a molar ratio of 2:1 to diethanolamine, while maintaining the reaction temperature constant. After the addition was complete, the reaction was continued for 3 hours. After the reaction was completed, the ethyl acetate was removed by rotary evaporation to obtain a yellow, viscous, terminally epoxy-terminated tung oil-based polyurethane toughening agent.

[0066] A modified epoxy resin with an end-epoxy tung oil-based polyurethane content of 10 wt.% was prepared, and a calculated amount of curing agent D230 was added. After mixing evenly and removing bubbles, the mixture was poured into a preheated mold and cured at 80°C for 3 hours to obtain the epoxy resin material.

[0067] Comparative Example 1

[0068] Epoxy resin and curing agent D230 are mixed at a mass ratio of 10:3, mechanically stirred until uniform, and after defoaming, poured into a preheated mold and cured at 80°C for 3 hours to obtain epoxy resin material.

[0069] Comparative Example 2

[0070] Epoxy resin and tung acid were mixed at a mass ratio of 9:1, heated to 120°C, and triphenylphosphine was used as a catalyst at a mass of 0.2% of the total mass of the reactants. The reaction was continued until the acid value was below 1 mg (KOH) / g. A calculated amount of curing agent D230 was added, and the mixture was cured at 80°C for 3 hours to obtain the epoxy resin material.

[0071] Table 1 Mechanical properties of modified epoxy resin cured products

[0072]

[0073]

Claims

1. Use of a tung oil based polyurethane type epoxy flexibilizer in the preparation of an epoxy resin, characterized in that, The prepared tung oil-based polyurethane epoxy toughening agent was mixed and reacted with liquid epoxy resin, and then an epoxy resin curing agent was added for blending and curing to obtain a tung oil-based polyurethane epoxy toughening agent modified epoxy resin material. The structure of the tung oil-based polyurethane epoxy toughening agent is shown below: ， R1 is: ; R2 is any of the following groups: , , , or .

2. The application according to claim 1, characterized in that, The tung oil-based polyurethane epoxy toughening agent is... R is: .

3. The application according to claim 1, characterized in that, The method for preparing the tung oil-based polyurethane epoxy toughening agent is characterized by the following steps: (1) Methyl tung oil and diethanolamine are reacted at a molar ratio of 1:(1-2) under vacuum at 60-90 °C for 2-5 hours, with KOH as a catalyst; after the reaction is completed, the product is dissolved in ethyl acetate, excess diethanolamine is removed by washing with water, and ethyl acetate is removed by rotary evaporation to obtain a brownish-red transparent liquid diethanol tungamide; (2) Diethanol tungamide is dissolved in ethyl acetate and heated to 40-55 °C, and diisocyanate with a molar ratio of 2:1 to diethanol tungamide is added dropwise, with dibutyltin dilaurate as a catalyst, and the reaction temperature is kept constant during the dropwise addition. After the dropwise addition is completed, the reaction is carried out for 2-5 hours to obtain an ethyl acetate solution of the intermediate; (3) The ethyl acetate solution of the intermediate is heated to 60-80 °C, and glycidyl ether with a molar ratio of 2:1 to diethanol tungamide is added dropwise, and the reaction temperature is kept constant. After the dropwise addition is completed, the reaction is continued for 2-5 hours to obtain an ethyl acetate solution of the intermediate; After 5 hours of reaction, ethyl acetate was removed by rotary evaporation to obtain a yellow, viscous, terminally epoxy-terminated tung oil-based polyurethane toughening agent.

4. The application according to claim 3, characterized in that, In step (1), the molar ratio of methyl tungate to diethanolamine is 1:1.5, the reaction temperature is 70℃, and the reaction time is 4 hours.

5. The application according to claim 3, characterized in that, The diisocyanate used in step (2) is any one of hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and lysine diisocyanate.

6. The application according to claim 3, characterized in that, The reaction temperature in step (2) is 50℃ and the reaction time is 3 hours.

7. The application according to claim 3, characterized in that, The reaction temperature in step (3) is 65℃ and the reaction time is 4 hours.

Images