Medium-temperature cured modified cyanate ester resin system and preparation method thereof

Abstract

The invention belongs to the field of high polymer material preparation, and relates to a medium-temperature cured modified cyanate ester resin system and a preparation method thereof. The medium-temperature cured modified cyanate ester resin system comprises the following components in parts by weight: 90-100 parts of cyanate ester resin, 1-10 parts of a catalyst and 5-20 parts of an epoxy resin toughening agent, the epoxy resin toughening agent is epoxy resin generated by a ring-opening reaction or a double-bond epoxidation reaction of a phenolic hydroxyl group of a phenolic compound and an epoxy group of epoxy chloropropane. The preparation method of the medium-temperature cured cyanate ester resin is simple in process, stable and controllable in reaction system, simple to operate and suitable for large-scale production; the medium-temperature curing modified cyanate ester resin can be cured at a medium temperature, the residual stress of a cured product is small, no solvent is volatilized, and the medium-temperature curing modified cyanate ester resin has the advantages of being environmentally friendly, low in carbon and green.

Description

Technical Field

[0001] The invention belongs to the field of polymer material preparation, and in particular relates to a medium-temperature curing modified cyanate ester resin system and a preparation method thereof. Background Art

[0002] Cyanate resin (CE) is a phenol derivative containing two or more cyanate functional groups (-OCN). It undergoes a tricyclization reaction under the action of heat and catalyst to generate a high-performance resin with a high cross-linking density network structure containing triazine rings. The cured CE has a high glass transition temperature (240℃~280℃), a low dielectric constant (2.8~3.2) and dielectric loss (0.002~0.008), excellent mechanical properties and bonding properties, and can be applied to a variety of molding processes such as prepreg / autoclave, resin transfer molding and winding. It is an important development direction for functional wave-transmitting composite materials and high-toughness structural materials in the future. Without the addition of a catalyst, CE can only obtain a large degree of curing crosslinking by curing at a higher temperature (>220℃) for a longer time. However, long-term curing at high temperature often causes more residual stress inside the cured product, resulting in poor stability of the material's service performance, which seriously hinders the development and large-scale application of CE and its related materials. Therefore, the research on curing catalysis of CE shows important theoretical significance and great application value.

[0003] Adding a catalyst is an effective method for CE curing catalysis research, but the curing temperature of the current catalytic curing system is still very high, and the cured product has a large residual stress, which limits the scope of application of CE. Therefore, it is still necessary to develop a cyanate resin system that cures at a medium temperature (90-130°C). CN102040838A discloses a method for preparing a modified CE and a fiber-reinforced modified cyanate-based composite material. Although a high-performance composite material is prepared using CE, the curing temperature of CE is high and is not suitable for hot-melt prepreg process, and hot-melt prepreg cannot be prepared on hot-melt prepreg equipment. CN104177640A discloses a method for preparing a cyanate prepreg. Although a CE suitable for hot-melt prepreg is prepared, the resin is not suitable for winding process and the curing temperature is as high as 190°C, which belongs to a high-temperature curing CE system. Summary of the invention

[0004] The present invention aims to solve the technical problems of the existing cyanate resin system such as high curing temperature and large residual stress of products, and to provide a medium-temperature curing modified cyanate resin system and a preparation method.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A medium-temperature curing modified cyanate resin system comprises 90 to 100 parts by weight of a cyanate resin, 1 to 10 parts by weight of a catalyst and 5 to 20 parts by weight of an epoxy resin toughener; the epoxy resin toughener is an epoxy resin generated by a ring-opening reaction between a phenolic hydroxyl group of a phenolic compound and an epoxy group of epichlorohydrin or by a double bond epoxidation reaction.

[0007] Preferably, the cyanate resin is one or a mixture of at least two of bisphenol A cyanate resin, bisphenol E cyanate resin, bisphenol F cyanate resin, phenolic cyanate resin, dihydroxy diphenyl sulfide cyanate resin, dicyclopentadienol cyanate resin, bisphenol AF cyanate resin, and bisphenol M cyanate resin.

[0008] Preferably, the phenolic compound is any one of magnolol, resveratrol, coumarin, vanillin, allyl bisphenol A, divanillyl alcohol, eugenol, vanillin, catechol, resorcinol, biphenol, hydroquinone, and lignin, or a combination of at least two of them.

[0009] Preferably, the catalyst is any one or a combination of at least two of a compound containing active hydrogen, a transition metal organic compound or an aluminum salt. Further preferably, the compound containing active hydrogen accounts for 1 to 5 parts by weight, and the transition metal organic compound or the aluminum salt accounts for 0.01 to 0.05 parts by weight.

[0010] Preferably, the compound containing active hydrogen is a phenol catalyst, an amine catalyst or an imidazole catalyst.

[0011] Preferably, the phenol catalyst is one or a mixture of at least two of nonylphenol, phenol, hydroquinone, resorcinol, catechol, vanillin, lignin, magnolol, furanol, and 1-naphthol.

[0012] Preferably, the transition metal organic compound is an acetylacetonate catalyst or an alkanoate catalyst.

[0013] Preferably, the acetylacetonate catalyst is one of cobalt acetonate, copper acetonate, iron acetylacetonate, and zinc acetonate, or a mixture of at least two of them.

[0014] Preferably, the epoxy resin toughening agent is one or a mixture of at least two of eugenol-based epoxy resin, magnolol epoxy resin, allyl epoxy resin, resveratrol-based epoxy resin, resorcinol-based epoxy resin, hydroquinone-based epoxy resin, catechol-based epoxy resin, biphenyl-based epoxy resin, lignin and its derivatives-based epoxy resin, and epoxidized soybean oil-based epoxy resin.

[0015] The preparation method of the above-mentioned medium temperature curing cyanate ester resin comprises the following steps:

[0016] Step 1: Mix the phenolic compound, epichlorohydrin and sodium hydroxide, stir at room temperature for 15 to 60 minutes, then add tetramethylammonium bromide, heat to 60 to 80°C for reaction for 2 to 3 hours, wash with water, distill, and recrystallize to obtain an epoxy resin toughening agent; wherein the molar ratio of the phenolic compound, epichlorohydrin, sodium hydroxide and tetramethylammonium bromide is 1:4 to 15:1.5 to 5:0.01 to 0.3;

[0017] Step 2: adding the cyanate resin into the reaction device and gradually heating it to 60°C to 90°C, and heating and melting it at a stirring speed of 1000 to 2000 r / min;

[0018] Step 3: adding the epoxy resin toughening agent to the molten cyanate resin according to the ratio, stirring continuously for 1 to 3 hours at 60 to 90° C. and a stirring speed of 1000 to 3000 r / min to obtain a modified cyanate resin;

[0019] Step 4: Add the catalyst in batches according to the ratio, continue stirring at 50-80°C and a stirring speed of 1000-3000 r / min to fully mix the mixture, and a medium-temperature curing modified cyanate ester resin can be obtained.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The method for preparing the medium-temperature curing cyanate resin of the present invention has a simple process. By adding a trace amount of catalyst and adjusting the order and time of adding materials, the reaction system is stable and controllable, the operation is simple, and it is suitable for large-scale production;

[0022] 2. The medium-temperature curing modified cyanate resin of the present invention can be cured at medium temperature (90-130° C.), the residual stress of the cured product is small, and there is no solvent volatilization, which is environmentally friendly, low-carbon and green;

[0023] 3. The medium temperature curing cyanate resin of the present invention utilizes the mutual catalysis between the cyanate ester and the epoxy resin in the copolymerization reaction to achieve the purpose of reducing the curing temperature and toughening the cyanate ester resin;

[0024] 4. The medium-temperature curing modified cyanate ester resin of the present invention has moderate viscosity and good processability, and can be applied to the preparation of prepregs and can also be suitable for winding processes; the obtained composite material has high comprehensive mechanical properties, can meet the requirements of high-performance aerospace structural materials, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the infrared spectrum of the reaction product in the embodiment.

[0026] Figure 2 is the nuclear magnetic resonance spectrum of the reaction product in the example. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below. The following embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation schemes and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments. The technical solution of the present invention is not limited to the specific implementation methods listed below, but also includes any combination of the specific implementation methods.

[0028] Embodiment 1:

[0029] A medium-temperature curing modified cyanate ester resin system and a preparation method thereof, comprising the following steps:

[0030] 1. Mix magnolol, epichlorohydrin and sodium hydroxide, stir at room temperature for 30 minutes, then add tetramethylammonium bromide, heat to 75℃ for reaction for 3 hours, wash with water and distill, and recrystallize with methanol to obtain magnolol epoxy resin; wherein the molar ratio of magnolol, epichlorohydrin, sodium hydroxide and tetramethylammonium bromide is 1:4:1.5:0.01; the infrared spectrum and nuclear magnetic resonance spectrum of the reaction product are shown in FIG. Figure 1 and Figure 2 , indicating that magnolol epoxy resin (DGEM) was successfully synthesized. Figure 1 Medium 910cm -1 The peak near is the characteristic peak of epoxy group.

[0031] 2. Take 90g of cyanate resin and add it into a 1L reaction flask, gradually raise the temperature to 80℃ and continue stirring at a stirring speed of 1500r / min for 1.0h to heat and melt it;

[0032] 3. Add 10g of magnolol epoxy resin into the above mixed system according to the ratio, and stir continuously for 1.0h at 80°C and a stirring speed of 1500r / min to obtain a modified cyanate ester resin;

[0033] Fourth: 1.0g of phenol is added to the above molten modified cyanate ester resin system in batches according to the ratio, and stirring is continued at 60°C and a stirring speed of 1500r / min to make it fully mixed, so as to obtain a medium-temperature curing modified cyanate ester resin.

[0034] Embodiment 2:

[0035] A medium-temperature curing modified cyanate ester resin system and a preparation method thereof, comprising the following steps:

[0036] 1. Mix magnolol, epichlorohydrin and sodium hydroxide, stir at room temperature for 30 minutes, then add tetramethylammonium bromide, heat to 75℃ for reaction for 3 hours, wash with water and distill, and recrystallize with methanol to obtain magnolol epoxy resin; wherein the molar ratio of magnolol, epichlorohydrin, sodium hydroxide and tetramethylammonium bromide is 1:4:1.5:0.01; the infrared spectrum and nuclear magnetic resonance spectrum of the reaction product are shown in FIG. Figure 1 and Figure 2 , indicating that magnolol epoxy resin (DGEM) was successfully synthesized. Figure 1 Medium 910cm -1 The peak near is the characteristic peak of epoxy group.

[0037] 2. Take 90g of cyanate resin and add it into a 1L reaction flask, gradually raise the temperature to 80℃ and continue stirring at a stirring speed of 1500r / min for 1.0h to heat and melt it;

[0038] 3. Add 10g of magnolol epoxy resin into the above mixed system according to the ratio, and stir continuously for 1.0h at 80°C and a stirring speed of 1500r / min to obtain a modified cyanate ester resin;

[0039] Fourth: 1.0g of phenol and 0.05g of cobalt acetylacetonate are added in batches to the above molten modified cyanate ester resin system according to the ratio, and stirring is continued at 60°C and a stirring speed of 1500r / min to make it fully mixed, so as to obtain a medium-temperature curing modified cyanate ester resin.

[0040] Embodiment 3:

[0041] A medium-temperature curing modified cyanate ester resin system and a preparation method thereof, comprising the following steps:

[0042] 1. Mix magnolol, epichlorohydrin and sodium hydroxide, stir at room temperature for 30 minutes, then add tetramethylammonium bromide, heat to 75℃ for reaction for 3 hours, wash with water and distill, and recrystallize with methanol to obtain magnolol epoxy resin; wherein the molar ratio of magnolol, epichlorohydrin, sodium hydroxide and tetramethylammonium bromide is 1:4:1.5:0.01; the infrared spectrum and nuclear magnetic resonance spectrum of the reaction product are shown in FIG. Figure 1 and Figure 2 , indicating that magnolol epoxy resin (DGEM) was successfully synthesized. Figure 1 Medium 910cm -1 The vicinity is the characteristic peak of the epoxy group;

[0043] 2. Take 80g of cyanate resin and add it into a 1L reaction flask, gradually raise the temperature to 90℃ and continue stirring at a stirring speed of 2000r / min for 1.0h to heat and melt it;

[0044] 3. Add 20g of magnolol epoxy resin into the above mixed system according to the ratio, and stir for 1.5h at 80°C and a stirring speed of 2000r / min to obtain a modified cyanate ester resin;

[0045] Fourth: Add 1.0g of phenol to the above molten modified cyanate ester resin in batches according to the ratio, continue stirring at 60°C and a stirring speed of 1500r / min to fully mix them, and then you can get a medium-temperature curing modified cyanate ester resin.

[0046] The specific embodiments of the present invention disclosed above are intended to help understand the content of the present invention and implement it accordingly. It can be understood by those skilled in the art that various replacements, changes and modifications are possible without departing from the spirit and scope of the present invention. The present invention should not be limited to the contents disclosed in the embodiments of this specification, and the scope of protection of the present invention shall be subject to the scope defined in the claims.

Claims

1. A medium temperature curing modified cyanate ester resin system, characterized in that: The invention comprises 90 to 100 parts by weight of cyanate resin, 1 to 10 parts by weight of catalyst and 5 to 20 parts by weight of epoxy resin toughening agent; the epoxy resin toughening agent is an epoxy resin generated by a ring-opening reaction between the phenolic hydroxyl group of a phenolic compound and the epoxy group of epichlorohydrin or by a double bond epoxidation reaction.

2. The medium temperature curing modified cyanate ester resin system according to claim 1, characterized in that: The cyanate resin is one of bisphenol A cyanate resin, bisphenol E cyanate resin, bisphenol F cyanate resin, phenolic cyanate resin, dihydroxy diphenyl sulfide cyanate resin, dicyclopentadiene phenol cyanate resin, bisphenol AF cyanate resin, and bisphenol M cyanate resin, or a mixture of at least two of them.

3. The medium temperature curing modified cyanate ester resin system according to claim 1, characterized in that: The phenolic compound is any one of magnolol, resveratrol, coumarin, vanillin, allyl bisphenol A, divanillyl alcohol, eugenol, vanillin, catechol, resorcinol, biphenol, hydroquinone, and lignin, or a combination of at least two of them.

4. The medium temperature curing modified cyanate ester resin system according to claim 1, characterized in that: The catalyst is any one of a compound containing active hydrogen, a transition metal organic compound or an aluminum salt, or a combination of at least two of them.

5. The medium temperature curing modified cyanate ester resin system according to claim 4, characterized in that: The compound containing active hydrogen is a phenol catalyst, an amine catalyst or an imidazole catalyst.

6. The medium temperature curing modified cyanate ester resin system according to claim 5, characterized in that: The phenol catalyst is one or a mixture of nonylphenol, phenol, hydroquinone, resorcinol, catechol, vanillin, lignin, magnolol, furanol and 1-naphthol.

7. The medium temperature curing modified cyanate ester resin system according to claim 4, characterized in that: The transition metal organic compound is an acetylacetonate catalyst or an alkanoate catalyst.

8. The medium temperature curing modified cyanate ester resin system according to claim 7, characterized in that: The acetylacetonate catalyst is one of cobalt acetonate, copper acetonate, iron acetylacetonate, and zinc acetonate, or a mixture of at least two of them.

9. The medium temperature curing modified cyanate ester resin system according to claim 1, characterized in that: The epoxy resin toughening agent is one of eugenol-based epoxy resin, magnolol epoxy resin, allyl epoxy resin, resveratrol-based epoxy resin, resorcinol-based epoxy resin, hydroquinone-based epoxy resin, catechol-based epoxy resin, biphenyl-based epoxy resin, lignin and its derivatives-based epoxy resin, and epoxy soybean oil-based epoxy resin, or a mixture of at least two of them.

10. A method for preparing a medium temperature curing modified cyanate ester resin system, characterized in that: The following steps are involved: The phenolic compound, epichlorohydrin and sodium hydroxide are mixed, stirred at room temperature for 15 to 60 minutes, and then tetramethylammonium bromide is added, the temperature is raised to 60 to 80°C for reaction for 2 to 3 hours, washed with water, distilled, and recrystallized to obtain an epoxy resin toughening agent; wherein the molar ratio of the phenolic compound, epichlorohydrin, sodium hydroxide and tetramethylammonium bromide is 1:4 to 15:1.5 to 5:0.01 to 0.3; Add cyanate resin into the reaction device and gradually raise the temperature to 60°C to 90°C, and heat to melt at a stirring speed of 1000 to 2000 r / min; Adding the epoxy resin toughening agent to the molten cyanate resin, stirring continuously for 1 to 3 hours at 60 to 90° C. and a stirring speed of 1000 to 3000 r / min, to obtain a modified cyanate resin; Step 4: Add the catalyst to the modified cyanate ester resin in batches according to the ratio, continue stirring at 50-80°C and a stirring speed of 1000-3000 r / min to fully mix it, and obtain a medium-temperature curing modified cyanate ester resin system.

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