Cyanate ester resin system for solvent-free spraying as well as preparation method and application of cyanate ester resin system

Abstract

The invention discloses a cyanate ester resin system for solvent-free spraying as well as a preparation method and application of the cyanate ester resin system. The resin system is prepared from the following substances in parts by weight: 100 parts of bisphenol E type cyanate ester resin, 0.01-0.1 part of a catalyst and 0.1-1 part of an initiator. The prepared resin system is suitable for a spraying technology, no solvent needs to be added in the using process, and environmental pollution caused by the solvent is avoided; the resin can be gelled within 72 hours at room temperature and does not flow in the subsequent heating and curing process, so that the curing and forming quality is ensured; the cured resin has excellent mechanical and temperature-resistant properties; and the resin system is relatively short in preparation, construction and forming period, relatively simple and convenient to operate and suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of cyanate resins, and in particular relates to a cyanate resin system for solvent-free spraying, a preparation method and an application thereof. Background Art

[0002] Resin is a polymer material, mainly composed of high molecular compounds. With its excellent performance and processability, it has been widely used in the manufacture of spacecraft. There are many processes for using resin in the aerospace industry, including: impregnation, winding, injection molding, painting, spraying, etc. In these processes, the selection of resin is crucial, and they must meet the performance requirements in specific application scenarios.

[0003] Resins can be divided into thermosetting resins and thermoplastic resins according to their properties. Currently, the commonly used thermosetting resins in the aerospace industry include epoxy resins, cyanate resins, bismaleimide resins, phenolic resins, etc. Among them, cyanate resins have the characteristics of high mechanics, high temperature resistance, low vacuum volatility, low moisture absorption, high dimensional stability, low dielectric, etc. Its comprehensive performance is the best among the known thermosetting resins.

[0004] The resin spraying process is used for the surface profiling of resin-based fiber-reinforced composite materials. The construction viscosity of the resin is required to be in the range of 30 to 150 mPa·s. Too high a viscosity will make it difficult for the resin to be atomized, resulting in problems such as dry spraying, orange peel, and pinholes. Too low a viscosity will cause serious resin flow problems.

[0005] Currently, the cyanate ester resin system commonly used in the aerospace industry is generally modified from pure cyanate ester resin. It is usually semi-solid at room temperature and needs to be diluted with a large amount of solvent when used in the spraying process. However, the introduction of solvents will cause environmental pollution on the one hand, and on the other hand, the volatilization of solvents will cause bubbles to appear on the surface of the resin layer after curing, thereby affecting the molding quality.

[0006] Therefore, in order to give full play to the excellent performance of cyanate ester resin and make it suitable for spraying process, it is of great significance to study the cyanate ester resin system for solvent-free spraying.

[0007] Although patent document CN111732728B discloses a cyanate resin system for solvent-free winding, its preparation method and application, the viscosity of the resin at room temperature is 400-550mPa·s, which can be used for winding process to prepare composite components, and the resin has high mechanical and heat resistance after curing. However, the viscosity of the resin system of the invention is greater than the process viscosity required by the spraying process, and the resin cannot be well atomized, so it is not suitable for spraying; in addition, the patent document points out that adding too much modifier bisphenol E cyanate resin to the resin system will affect the performance of the resin after curing. Summary of the invention

[0008] In order to overcome the above problems, the present invention provides a cyanate resin system for solvent-free spraying, and a preparation method and application thereof.

[0009] The technical solution of the present invention is as follows:

[0010] <First aspect>

[0011] A cyanate resin system for solvent-free spraying, comprising, by weight:

[0012]

[0013] The room temperature viscosity of the bisphenol E cyanate ester resin is 50 to 100 mPa·s.

[0014] The catalyst includes one or more of zinc octoate, manganese octoate, cobalt acetylacetonate, copper acetylacetonate, cobalt naphthenate, and dibutyltin dilaurate.

[0015] The initiator is an amine compound, and the amine compound is a tertiary amine compound.

[0016] The amine compound includes any one of N,N-dimethylbenzylamine and 2,2',2"-trihydroxytriethylamine or a combination of several thereof.

[0017] <Second Aspect>

[0018] The present invention provides a method for preparing a cyanate ester resin system for solvent-free spraying, comprising the following steps:

[0019] S1, stirring and mixing bisphenol E cyanate resin and a catalyst;

[0020] S2, adding an initiator to the mixture of S1, stirring and mixing, and obtaining a cyanate resin system for solvent-free spraying.

[0021] In step S1, the stirring speed is 1500-2000 r / min, and the stirring time is 60-90 min.

[0022] In step S2, the stirring speed is 400-600 r / min, and the stirring time is 10-15 min.

[0023] When in use, the solvent-free spray cyanate resin system is loaded into a spray gun, sprayed onto the work surface, left to air at room temperature until the resin gels, and then cured at 180°C for 3 hours. The resin gel is the state of the resin gel specified in GJB1059.4-1990.

[0024] In the present invention, by adding a proper amount of initiator, bisphenol E cyanate can have appropriate reaction activity at room temperature, gel within 24 to 72 hours after mixing, do not flow in the subsequent heating and curing process, and the viscosity of the resin system does not change significantly in the initial mixing stage, providing a spray open period of ≥1 hour.

[0025] In the present invention, adding a trace amount of catalyst can reduce the curing temperature of the resin and shorten the curing time of the resin without almost affecting the room temperature viscosity of the bisphenol E cyanate resin.

[0026] The present invention is improved over the prior art in that a bisphenol E cyanate resin having a viscosity of 50 to 100 mPa·s at room temperature suitable for spraying is used as the main body of the resin system, and a good atomization effect is achieved during spraying. However, the curing reaction temperature of pure bisphenol E cyanate resin is as high as 200° C. or above, and the viscosity will drop to below 30 mPa·s during the heating process, resulting in severe flow of the resin. Therefore, the present invention adds an appropriate amount of initiator to the bisphenol E cyanate resin so that the mixture has moderate reactivity at room temperature. On the one hand, the mixture can gel within 24 to 72 hours at room temperature, thereby avoiding flow during the subsequent heating to the curing temperature (about 180° C.). On the other hand, the mixture has a spray open period of ≥1 hour after mixing.

[0027] Further research of the present invention found that by using amine compounds as initiators of cyanate esters, the mixed resin system can gel within 72 hours at room temperature, so that the resin system will not flow during the subsequent temperature rise and curing process. A small amount of amine compounds (mass fraction 0.1-1%) can react with cyanate esters to produce gelation, ensuring a certain viscosity. However, not all amine compounds can achieve the better technical effects of the present invention. The present invention has found that compared with tertiary amines, primary amines and secondary amines are prone to gelation during the preparation process.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The cyanate resin system obtained by the present invention has a room temperature viscosity of 50 to 120 mPa·s and can be directly sprayed at room temperature without adding a solvent, thereby simplifying the process and avoiding environmental pollution caused by the solvent. Furthermore, no bubbles are generated on the surface of the resin spray layer after curing.

[0030] (2) The cyanate resin system of the present invention has good processability, which is specifically reflected in the following four aspects:

[0031] ① The room temperature viscosity of the resin system is 50-120 mPa·s, and the atomization effect is good during spraying;

[0032] ② The spray open period of the resin system is ≥ 1h, which provides sufficient spraying time;

[0033] ③After spraying, the resin system can gel within 24 to 72 hours at room temperature, avoiding the flow of resin during the subsequent heating and curing process;

[0034] ④ The resin system preparation, construction and molding cycle is short, the operation is relatively simple, and it is suitable for large-scale industrial production.

[0035] (3) The cyanate resin system cured product of the present invention has excellent mechanical properties and heat resistance, with a tensile strength of ≥100 MPa, a tensile modulus of ≥3.5 GPa, and a glass transition temperature of ≥230°C; the spray coating is not prone to cracking after curing. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below through preferred embodiments. Through these descriptions, the characteristics and advantages of the present invention will become more clear and explicit.

[0037] Bisphenol E cyanate resin: SY-9; viscosity at 25°C is 80 mPa·s.

[0038] Example 1

[0039] A cyanate resin system for solvent-free spraying includes the following components in parts by weight:

[0040] Cyanate resin (bisphenol E type cyanate resin) 100 parts

[0041] Catalyst (cobalt acetylacetonate) 0.02 parts

[0042] Initiator (N,N-dimethylbenzylamine) 0.2 parts

[0043] The preparation method of the solvent-free spray cyanate resin system is as follows:

[0044] S1, stirring and mixing the cyanate resin and the catalyst at a stirring speed of 2000 r / min for 90 min to obtain a mixture;

[0045] S2, adding an initiator to the above mixture, stirring and mixing, the stirring speed is 400r / min, and the stirring time is 10min, to obtain a cyanate resin system for solvent-free spraying.

[0046] Example 2

[0047] A cyanate resin system for solvent-free spraying includes the following components in parts by weight:

[0048] Cyanate resin (bisphenol E type cyanate resin) 100 parts

[0049] Catalyst (cobalt acetylacetonate) 0.04 parts

[0050] Initiator (N,N-dimethylbenzylamine) 0.5 parts.

[0051] The preparation method of the solvent-free spray cyanate resin system is as follows:

[0052] S1, stirring and mixing the cyanate resin and the catalyst at a stirring speed of 2000 r / min for 90 min to obtain a mixture;

[0053] S2, adding an initiator to the above mixture, stirring and mixing, the stirring speed is 400r / min, and the stirring time is 10min, to obtain a cyanate resin system for solvent-free spraying.

[0054] Example 3

[0055] A cyanate resin system for solvent-free spraying includes the following components in parts by weight:

[0056] Cyanate resin (bisphenol E type cyanate resin) 100 parts

[0057] Catalyst (manganese octanoate) 0.03 parts

[0058] Initiator (N,N-dimethylbenzylamine) 0.3 parts.

[0059] The preparation method of the solvent-free spray cyanate resin system is as follows:

[0060] S1, stirring and mixing the cyanate resin and the catalyst at a stirring speed of 2000 r / min for 60 min to obtain a mixture;

[0061] S2, adding an initiator to the above mixture, stirring and mixing, the stirring speed is 600r / min, and the stirring time is 15min, to obtain a cyanate ester resin system for solvent-free spraying.

[0062] Comparative Example 1

[0063] This comparative example refers to the formula of CN111732728B:

[0064] A cyanate resin system for solvent-free winding, the cyanate resin system comprising the following components in parts by weight:

[0065] Cyanate resin (bisphenol A type cyanate resin with a polymerization degree of 300) 55 parts

[0066] Modifier (bisphenol E cyanate resin) 45 parts

[0067] Catalyst (zinc acetylacetonate) 3 parts

[0068] The preparation method of the cyanate resin system is:

[0069] S1, heating the cyanate resin at 60° C. for 30 min, and then stirring and mixing with the modifier at a stirring speed of 3000 r / min for 30 min to obtain a mixture;

[0070] S2, adding 3 g of zinc acetylacetonate to the mixture three times, stirring evenly, with an interval of 5 minutes between each two times, the stirring speed is 3000 r / min, and the stirring time is 30 minutes to obtain a cyanate resin system.

[0071] Comparative Example 2

[0072] This comparative example refers to the formula in "Research on the Performance of Cyanate Ester Resins" (Zhu Baolin. Science Press, 2016):

[0073] A cyanate resin system for composite material prepreg, the cyanate resin system comprising the following components in parts by weight:

[0074] Cyanate resin (bisphenol A type cyanate resin with a polymerization degree of 300) 90 parts

[0075] Modifier (bisphenol F epoxy resin) 10 parts

[0076] Catalyst (cobalt acetylacetonate) 0.02 parts

[0077] The preparation method of the cyanate resin system is:

[0078] S1, stirring and mixing the modifier and the catalyst at a stirring speed of 3000 r / min for 60 min to obtain a mixture;

[0079] S2, heating the cyanate resin at 60° C. for 30 min, and then stirring the mixture at a stirring speed of 500 r / min for 20 min to obtain a cyanate resin system.

[0080] Comparative Example 3

[0081] The difference between this comparative example and Example 1 is that the cyanate ester resin (bisphenol E type cyanate ester resin) is replaced by a cyanate ester resin (bisphenol A type cyanate ester resin having a polymerization degree of 300).

[0082] Comparative Example 4

[0083] A cyanate resin system for solvent-free spraying includes the following components in parts by weight:

[0084] Cyanate resin (bisphenol E type cyanate resin) 100 parts

[0085] Catalyst (cobalt acetylacetonate) 0.02 parts

[0086] The preparation method of the solvent-free spray cyanate resin system is as follows:

[0087] S1, stirring and mixing the cyanate resin and the catalyst at a stirring speed of 2000 r / min for 90 min to obtain a cyanate resin system for solvent-free spraying.

[0088] Comparative Example 5

[0089] A cyanate resin system for solvent-free spraying includes the following components in parts by weight:

[0090] Cyanate resin (bisphenol E type cyanate resin) 100 parts

[0091] Catalyst (cobalt acetylacetonate) 0.02 parts

[0092] Initiator (phthalic anhydride) 0.2 parts.

[0093] The preparation method of the solvent-free spray cyanate resin system is as follows:

[0094] S1, stirring and mixing the cyanate resin and the catalyst at a stirring speed of 2000 r / min for 90 min to obtain a mixture;

[0095] S2, adding an initiator to the above mixture, stirring and mixing, the stirring speed is 400r / min, and the stirring time is 10min, to obtain a cyanate resin system for solvent-free spraying.

[0096] Comparative Example 6

[0097] The difference between this comparative example and Example 1 is that the initiator (N,N-dimethylbenzylamine) is replaced by 4,4'-diaminodiphenylmethane.

[0098] Comparative Example 7

[0099] The difference between this comparative example and Example 1 is that the initiator (N,N-dimethylbenzylamine) is replaced by N,N-dimethylethanolamine.

[0100] Effect verification:

[0101] The performance of the cyanate resin system for solvent-free spraying prepared in Examples 1-3 and the cyanate resin system prepared in Comparative Examples 1-7 was tested:

[0102] 1. Viscosity test: The specific test method is as follows: According to GB / T 22314-2008, the viscosity of the resins of Examples 1-3 and Comparative Examples 1-7 was tested. The results are shown in Table 1.

[0103] 2. Gel time test: The specific test method is as follows: According to GJB 1059.4-1990, the gel time test is performed on the resins of Examples 1-3 and Comparative Examples 1-7. The results are shown in Table 1.

[0104] 3. Tensile strength and tensile modulus test. The specific test method is as follows: According to GB / T 2567-2008, the tensile strength and tensile modulus of the cured resins of Examples 1-3 and Comparative Examples 1-7 were tested. The results are shown in Table 1.

[0105] 4. Glass transition temperature test: The specific test method is as follows: According to GB / T 40396-2021, the glass transition temperature of the cured resins of Examples 1-3 and Comparative Examples 1-7 was tested. The results are shown in Table 1.

[0106] Table 1: Test results of resin system performance of Examples 1-3 and Comparative Examples 1-7

[0107]

[0108]

[0109] As can be seen from Table 1, the cyanate resin systems obtained in Examples 1-3 can be directly used in the spraying process, the cyanate resin systems obtained in Comparative Examples 1-3 need to be diluted with solvents before they can be used in the spraying process due to the excessive initial viscosity, and Comparative Examples 4-5 cannot gel within 72 hours at room temperature; Comparative Examples 6-7 gelled during the preparation process; the tensile strength of the cyanate resin system obtained in Example 1-3 is significantly higher than that of Comparative Examples 1-3, and the glass transition temperature of the cyanate resin system obtained in Example 1-3 is substantially equivalent to that of Comparative Examples 1-3.

[0110] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A cyanate resin system for solvent-free spraying, characterized in that: The resin system comprises, by weight: 100 parts of bisphenol E cyanate resin Catalyst 0.01~0.1 parts Initiator 0.1 to 1 part.

2. The cyanate resin system for solvent-free spraying according to claim 1, characterized in that: The room temperature viscosity of the bisphenol E cyanate ester resin is 50 to 100 mPa·s.

3. The cyanate resin system for solvent-free spraying according to claim 1, characterized in that: The catalyst includes one or more of zinc octoate, manganese octoate, cobalt acetylacetonate, copper acetylacetonate, cobalt naphthenate, and dibutyltin dilaurate.

4. The cyanate resin system for solvent-free spraying according to claim 1, characterized in that: The initiator is an amine compound, and the amine compound is a tertiary amine compound.

5. The cyanate resin system for solvent-free spraying according to claim 1, characterized in that: The amine compound includes any one of N,N-dimethylbenzylamine and 2,2',2"-trihydroxytriethylamine or a combination of several thereof.

6. The method for preparing a cyanate resin system for solvent-free spraying according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, stirring and mixing bisphenol E cyanate resin and a catalyst; An initiator is added to the mixture of S2 and S1, and the mixture is stirred and mixed to obtain a cyanate resin system for solvent-free spraying.

7. The preparation method according to claim 6, characterized in that: In step S1, the stirring speed is 1500-2000 r / min, and the stirring time is 60-90 min.

8. The preparation method according to claim 6, characterized in that: In step S2, the stirring speed is 400-600 r / min, and the stirring time is 10-15 min.

9. Use of the cyanate resin system for solvent-free spraying according to any one of claims 1 to 5 in aerospace.

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