Low-dielectric cyanate ester resin-based composite material and preparation method thereof

Abstract

The invention relates to the technical field of wave-transparent composite materials, in particular to a fiber-reinforced resin-based wave-transparent composite material and a preparation method thereof. The cyanate ester resin matrix is modified by thermosetting polyphenyl ether, the dielectric property of the cyanate ester resin is remarkably improved, the glass-transition temperature of the cyanate ester resin is maintained, and the problems of high curing temperature, poor toughness of a cured product, poor manufacturability and the like of the cyanate ester resin are solved by compounding the catalyst and the flexibilizer. The obtained cyanate ester resin system has excellent dielectric properties and humidity and heat resistance, also has good mechanical properties and manufacturability, meets the requirements of hot melt method prepreg preparation and autoclave molding process, and prepares a wave-transparent composite material with low dielectric properties.

Description

Technical Field

[0001] The present invention relates to the technical field of wave-transmitting composite materials, and in particular to a fiber-reinforced resin-based wave-transmitting composite material and a preparation method thereof. Background Art

[0002] Wave-transparent materials for aerospace use must ensure efficient transmission of electromagnetic waves to achieve effective communication. The antenna system technology used in the aerospace field is becoming increasingly dense and precise, and the demand for resin-based wave-transparent composite materials with low dielectric constant and dielectric loss, high temperature resistance and excellent mechanical properties is becoming increasingly prominent.

[0003] Cyanate ester (CE) resin is a high-performance thermosetting resin. Through cyclization reaction, it can form a highly cross-linked triazine ring network structure with symmetry, which gives cyanate ester resin good mechanical properties, heat resistance and outstanding dielectric properties (dielectric constant 2.8-3.2, dielectric loss tangent 0.002-0.008). It can maintain low dielectric properties in a wide band range and under hot and humid conditions. However, cyanate ester resin has the problems of high curing reaction temperature, large brittleness of cured products, and poor prepreg coating process. The literature reported so far mainly reduces the curing temperature of cyanate ester resin by compounding and modifying the catalyst. Commonly used high-efficiency catalysts include transition metal compounds, phenols and amines containing active hydrogen; alkylphenols, bisphenols, alcohols, imidazoles, aromatic amines or hydroxyl-containing resins can also catalyze the high-efficiency conversion of cyanate esters. However, the curing temperature of the curing system currently studied is mainly concentrated above 155°C, and the introduced polar molecules will reduce the dielectric properties of the system.

[0004] Polyphenylene ether is a type of thermoplastic polymer commonly used for toughening cyanate ester resins. It has excellent dielectric properties and can significantly reduce the dielectric constant of cyanate ester resins. It can also catalyze the polymerization reaction of cyanate esters to a certain extent and reduce the curing reaction temperature. In current technical reports, the compatibility of polyphenylene ether and cyanate esters is improved by end group modification, molecular weight reduction, or the use of solvents, but this will reduce the glass transition temperature of the system and affect the heat resistance of the composite. Summary of the invention

[0005] The object of the present invention is to provide a cyanate resin composition with low dielectric and high glass transition temperature and a preparation method thereof, wherein the cyanate resin is modified by a thermosetting polyphenylene ether and a thermoplastic toughening agent, and the compatibility of the modifier and the cyanate ester is improved by in-situ polymerization of the modifier in the cyanate resin, and the formed cyanate resin composition has the characteristics of low dielectric constant / dielectric loss tangent value, high glass transition temperature, high toughness and excellent processability. Therefore, the present invention provides a low dielectric cyanate resin composition suitable for application environments such as structure-function integrated structural parts, solvent-resistant / moisture-resistant copper-clad laminates, etc.

[0006] Another object of the present invention is to provide a wave-transmitting composite material with low dielectric properties and a preparation method thereof. The wave-transmitting composite material is composed of the low dielectric cyanate resin composition and reinforcements such as PBO fibers and quartz fibers.

[0007] Specifically, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides a low dielectric cyanate ester resin composition, comprising the following main components: a cyanate ester resin, a polyphenylene ether, a thermoplastic toughening agent, a catalyst, and a defoaming agent.

[0009] Optionally, the cyanate ester resin is composed of at least one cyanate ester component, which may be commonly used bisphenol A cyanate ester, novolac cyanate ester, bisphenol M cyanate ester, or bisphenol E cyanate ester.

[0010] Optionally, the polyphenylene ether is a methacrylate-terminated thermosetting polyphenylene ether, or a thermosetting polyphenylene ether containing unsaturated double bonds with an allyl terminal group. This type of polyphenylene ether can be polymerized in situ during the cyanate ester curing process, reacting with itself or other compounds containing ethylenic unsaturation to form a network structure and maintain the glass transition temperature of the resin.

[0011] Optionally, the thermoplastic toughening agent is a styrene-based agent, but is not limited thereto, and may also be a compound containing unsaturated double bonds such as a multifunctional acrylate or a polybutadiene elastomer.

[0012] Optionally, the catalyst includes a cyanate catalyst, such as one or a combination of dibutyltin dilaurate, active hydrogen-containing phenols, amines and other compounds.

[0013] Optionally, the catalyst further comprises a free radical polymerization catalyst of polyphenylene ether and a thermoplastic toughening agent, such as one or a combination of di-tert-butyl peroxide, 2,5-dimethyl peroxide, tert-butyl peroxybenzoate, diisopropylbenzene peroxide, and the like.

[0014] Optionally, the defoaming agent is one of polysiloxane, modified organic silicone compound, polyurea and the like.

[0015] In a second aspect, the present invention provides a method for preparing the above-mentioned low dielectric cyanate ester resin composition, comprising the following steps:

[0016] Mixing 50 to 80 parts by weight of a cyanate resin, 10 to 30 parts by weight of a polyphenylene ether, 5 to 20 parts by weight of a thermoplastic toughening agent, and 0.1 to 1 part by weight of a free radical polymerization catalyst at a relatively high temperature to obtain a mixture A;

[0017] 0.2 to 1 parts by weight of a cyanate ester catalyst and 0.25 to 1.5 parts by weight of a defoamer are added to the mixture A, and the mixture is mixed at a suitable temperature to obtain a cyanate ester resin composition.

[0018] Furthermore, the mixing at a higher temperature to obtain the mixture A is performed at 110°C to 130°C to obtain the mixture A; the mixing at an appropriate temperature to obtain the cyanate ester resin composition is performed at 80°C to 90°C to obtain the cyanate ester resin composition.

[0019] Furthermore, the method further comprises: pouring the cyanate resin composition into a mold, evacuating the mold to remove air bubbles, and then preparing a cyanate resin cured product with low dielectric, high glass transition temperature and high toughness through a curing process. The cyanate resin cured product prepared in this step is mainly used for testing performance.

[0020] In a third aspect, the present invention provides a method for preparing a wave-transmitting composite material with low dielectric properties, comprising the following steps:

[0021] The obtained cyanate resin composition is used to prepare a prepreg by a hot melt method: the cyanate resin composition is coated at a suitable temperature, and then the film is compounded with a fluorinated modified PBO fiber fabric, or a low dielectric reinforcing fiber such as a quartz fiber under suitable conditions to form a prepreg;

[0022] The prepreg is used to obtain a wave-transmitting composite material laminate with low dielectric properties through a layering and autoclave molding process.

[0023] Optionally, the PBO fiber is a surface-fluorinated PBO fiber, and the CF bonds on the surface can participate in the triazine cyclization reaction of the cyanate resin to obtain a wave-transmitting composite material with good interface adhesion.

[0024] In a fourth aspect, the present invention provides a wave-transmitting composite material having low dielectric properties prepared by the above method.

[0025] Beneficial effects of the present invention:

[0026] (1) The present invention adopts thermosetting polyphenylene ether modified cyanate ester, which greatly reduces the dielectric constant and energy loss of cyanate ester resin, and obtains a cyanate ester composition with high dielectric properties;

[0027] (2) The present invention uses thermosetting polyphenylene ether and unsaturated thermoplastic toughening agent to perform in-situ polymerization during the curing process of cyanate ester resin, which greatly improves the compatibility of the modifier and cyanate ester resin;

[0028] (3) Thermosetting polyphenylene ether modifiers can be cross-linked with unsaturated thermoplastic toughening agents during the cyanate ester curing process to form an interpenetrating network, which maintains the cross-linking density of the resin and makes the resin system have a higher glass transition temperature and good solvent resistance.

[0029] (4) The thermoplastic toughening agent introduced into the system compensates for the brittleness of cyanate ester, and the resulting modified cyanate ester resin has higher toughness.

[0030] (5) The present invention uses a low-dielectric cyanate resin composition and a surface-fluorinated PBO fiber or a low-dielectric quartz fiber to prepare a prepreg by a hot melt method. The volatile matter of the formed prepreg is controllable and has the advantages of low dielectric constant, low energy loss, and excellent mechanical properties.

[0031] In summary, the present invention modifies the cyanate resin matrix by thermosetting polyphenylene ether, significantly improves the dielectric properties of the cyanate resin, maintains the glass transition temperature of the cyanate resin, and solves the problems of high curing temperature, poor toughness of the cured product, and poor processability of the cyanate resin by catalyst compounding and toughening agent. The obtained cyanate resin system has excellent dielectric properties and moisture and heat resistance, as well as good mechanical properties and processability, meets the requirements of hot melt prepreg preparation and autoclave molding process, and provides high-quality material selection for structure-function integrated wave-transparent composite materials. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below through specific embodiments. The embodiments of the present invention and the features in the embodiments can be combined with each other, and the described embodiments are only part of the embodiments of the present invention, but not all of the embodiments.

[0033] Example 1

[0034] 50 parts of cyanate resin (bisphenol A type cyanate resin), 30 parts of methacrylate-terminated polyphenylene ether, 19 parts of styrene, and 0.2 parts of a free radical polymerization catalyst (di-tert-butyl peroxide) are mixed at 130° C. to obtain a mixture A; then 0.3 parts of dibutyltin dilaurate and 0.5 parts of a defoaming agent are added to the mixture A, and the mixture is mixed evenly at 90° C. to obtain a low dielectric, high glass transition temperature cyanate resin composition.

[0035] The dielectric properties and mechanical properties of the cyanate resin composition prepared in this example are shown in Table 1.

[0036] Example 2

[0037] Take 40 parts of bisphenol A cyanate resin and mix it with 20 parts of bisphenol E cyanate resin, add 25 parts of methacrylate-terminated polyphenylene ether, 12 parts of polybutadiene, and 0.5 parts of free radical polymerization catalyst (diisopropylbenzene peroxide), and mix at 120°C to obtain a mixture A; then add 2 parts of diallyl bisphenol A and 0.5 parts of a defoamer to the mixture A, mix evenly at 90°C to obtain a low dielectric, high glass transition temperature cyanate resin composition.

[0038] The dielectric properties and mechanical properties of the cyanate resin composition prepared in this example are shown in Table 1.

[0039] Example 3

[0040] 55 parts of cyanate resin (bisphenol M type cyanate resin), 30 parts of methacrylate-terminated polyphenylene ether, 9 parts of styrene, and 0.3 parts of a radical polymerization catalyst (di-tert-butyl peroxide) are mixed at 120° C. to obtain a mixture A; then 5 parts of 4-maleimidophenol and 0.7 parts of a defoamer are added to the mixture A, and the mixture is mixed evenly at 90° C. to obtain a low dielectric, high glass transition temperature cyanate resin composition.

[0041] The dielectric properties and mechanical properties of the cyanate resin composition prepared in this example are shown in Table 1.

[0042] Example 4

[0043] 70 parts of cyanate resin (phenolic cyanate resin), 14 parts of methacrylate-terminated polyphenylene ether, 14 parts of styrene, and 0.3 parts of a radical polymerization catalyst (di-tert-butyl peroxide) are mixed at 110° C. to obtain a mixture A; then 1 part of dibutyltin dilaurate and 0.7 parts of a defoaming agent are added to the mixture A, and the mixture is mixed evenly at 80° C. to obtain a low dielectric, high glass transition temperature cyanate resin composition.

[0044] The dielectric properties and mechanical properties of the cyanate resin composition prepared in this example are shown in Table 1.

[0045] Example 5

[0046] The resin in Example 3 was compounded with B-type quartz fiber to prepare a prepreg (resin content 34%), and its composite laminate was prepared by autoclave molding process. The dielectric properties and main mechanical properties of the obtained composite material are shown in Table 1.

[0047] Table 1. Properties of quartz fiber reinforced low dielectric cyanate ester composite materials

[0048]

[0049] Comparative Example 1

[0050] To prepare a thermoplastic polyphenylene ether modified cyanate resin, 50 parts of cyanate resin (bisphenol A type cyanate resin), 30 parts of thermoplastic polyphenylene ether, 19 parts of styrene, and 0.2 parts of a free radical polymerization catalyst (di-tert-butyl peroxide) were mixed at 130° C. to obtain a mixture A; then 0.3 parts of dibutyltin dilaurate and 0.5 parts of a defoaming agent were added to the mixture A, and the mixture was mixed evenly at 90° C. to obtain a cyanate resin composition.

[0051] The dielectric properties and mechanical properties data of the cyanate resin compositions prepared in the above Examples 1-4 and Comparative Example 1 are shown in Table 2.

[0052] Table 2. Dielectric and mechanical properties of different resin systems

[0053]

[0054] As can be seen from Table 2, the addition of polyphenylene ether makes the cyanate ester have a lower dielectric constant and dielectric loss, showing better dielectric properties. Compared with thermoplastic polyphenylene ether, thermosetting polyphenylene ether can significantly increase the glass transition temperature of cyanate ester resin and maintain the high temperature resistance of the system. In addition, the addition of thermoplastic toughening agent can effectively improve the numerical toughness, significantly improve the bending strength and modulus of cyanate ester, and show excellent mechanical properties.

[0055] Finally, it should be noted that the above is only a preferred embodiment of the present invention, but it is not intended to limit the present invention. It should be pointed out that for ordinary technicians in this field, several modifications or equivalent substitutions can be made without departing from the principle of the present invention, which should all be regarded as the scope of protection of the present invention.

Claims

1. A low dielectric cyanate resin composition, characterized in that: It includes cyanate resin, polyphenylene ether, thermoplastic toughening agent, catalyst and defoaming agent.

2. The low dielectric cyanate resin composition according to claim 1, characterized in that: The cyanate resin comprises at least one cyanate component, wherein the cyanate component is bisphenol A cyanate, novolac cyanate, bisphenol M cyanate, or bisphenol E cyanate; the thermoplastic toughening agent is styrene, multifunctional acrylate, or polybutadiene elastomer; The defoamer is one of polysiloxane, modified organic silicone compound and polyurea.

3. The low dielectric cyanate ester resin composition according to claim 1, characterized in that: The polyphenylene ether is a thermosetting polyphenylene ether terminated with methacrylate, or a thermosetting polyphenylene ether containing unsaturated double bonds and having an allyl terminal group.

4. The low dielectric cyanate resin composition according to claim 1, characterized in that: The catalyst comprises a cyanate catalyst, and the cyanate catalyst is at least one of dibutyltin dilaurate, phenols containing active hydrogen, and amines.

5. The low dielectric cyanate resin composition according to claim 4, characterized in that: The catalyst also includes a free radical polymerization catalyst of polyphenylene ether and a thermoplastic toughening agent, and the free radical polymerization catalyst is at least one of di-tert-butyl peroxide, 2,5-dimethyl peroxide, tert-butyl peroxybenzoate, and diisopropylbenzene peroxide.

6. A method for preparing a low dielectric cyanate ester resin composition, characterized in that: The following steps are involved: Mixing 50 to 80 parts by weight of a cyanate resin, 10 to 30 parts by weight of a polyphenylene ether, 5 to 20 parts by weight of a thermoplastic toughening agent, and 0.1 to 1 part by weight of a free radical polymerization catalyst at a relatively high temperature to obtain a mixture A; 0.2 to 1 parts by weight of a cyanate ester catalyst and 0.25 to 1.5 parts by weight of a defoamer are added to the mixture A, and the mixture is mixed at a suitable temperature to obtain a cyanate ester resin composition.

7. The preparation method according to claim 6, characterized in that: The mixing at a relatively high temperature to obtain the mixture A is performed at 110°C to 130°C to obtain the mixture A; the mixing at a suitable temperature to obtain the cyanate ester resin composition is performed at 80°C to 90°C to obtain the cyanate ester resin composition.

8. A method for preparing a wave-transmitting composite material with low dielectric properties, characterized in that: The following steps are involved: Compounding the low dielectric cyanate ester resin composition according to any one of claims 1 to 5 with low dielectric reinforcing fibers to form a prepreg; The prepreg is used to obtain a wave-transmitting composite material laminate with low dielectric properties through a layering and autoclave molding process.

9. The preparation method according to claim 8, characterized in that: The low dielectric reinforcing fiber is fluorinated modified PBO fiber fabric or quartz fiber.

10. A wave-transmitting composite material with low dielectric properties prepared according to the method of claim 8 or 9.

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