Preparation method of cyanate ester resin and cyanate ester resin

Abstract

The method comprises the following steps: adding CaCO3 whiskers into a diluent containing a silane coupling agent, carrying out ultrasonic dispersion, stirring at a first preset temperature, carrying out centrifugal separation on a product, washing with deionized water and absolute ethyl alcohol for multiple times, and drying to obtain modified CaCO3 whiskers; stirring and heating cyanate ester resin to a second preset temperature, adding cage type polysilsesquioxane particles and the modified CaCO3 whiskers, and stirring; adding a curing system, uniformly stirring, defoaming, pouring into a mold, and curing, so as to obtain the modified CaCO3 whisker and polyhedral oligomeric silsesquioxane particle synergistically reinforced and toughened cyanate resin casting body.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance resin preparation, and particularly relates to a preparation method of cyanate ester resin and the cyanate ester resin. Background Art

[0002] The traditional method for toughening resins is to add thermoplastic resins or rubber particles as fillers. This method can greatly improve the toughness of resins, but it also brings adverse effects such as an increase in resin viscosity, making it difficult to process; a decrease in resin strength and modulus. Calcium carbonate whiskers, as a kind of short-fiber inorganic material with a large aspect ratio grown in the form of single crystals, have a simple preparation process and low cost, and have excellent properties such as high strength, high modulus, good heat resistance and heat insulation. The introduction of CaCO3 can prevent cracks from further expanding, thereby increasing the toughness of the resin matrix. However, the small-size effect of the whiskers easily causes them to agglomerate, and they cannot be well dispersed with the matrix resin, which is likely to form local stress concentration and residual stress, ultimately resulting in a low tensile strength of the material and making it difficult to simultaneously improve strength and toughness.

[0003] CN118271792A discloses a toughening and strengthening nano core-shell particle toughening agent and its preparation method and application. This method transfers nano core-shell particles to the organic phase and then disperses them into the resin matrix to improve the dispersibility of the nano core-shell particles and achieve the toughening and strengthening effect of the resin. However, this method has complex operations, low production efficiency, relatively high costs, and limited improvement in the strength of the resin.

[0004] The above information disclosed in the background art section is only used to enhance the understanding of the background of the present invention, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] The present invention provides a preparation method of cyanate ester resin and the cyanate ester resin, which overcomes the problem that it is difficult to simultaneously have both strength and toughness during the toughening process of cyanate ester resin.

[0006] A preparation method of cyanate ester resin includes:

[0007] Step 1: Add calcium carbonate whiskers to a dilution containing a silane coupling agent, ultrasonically disperse, stir at a first predetermined temperature, centrifuge the product, and wash it multiple times with deionized water and absolute ethanol, and then dry to obtain modified calcium carbonate whiskers;

[0008] Step 2: Stir and heat the cyanate ester resin to a second predetermined temperature, add cage-shaped polyhedral oligomeric silsesquioxane particles and the modified calcium carbonate whiskers, and then stir;

[0009] Step 3: After adding the curing system and stirring evenly, defoam, pour into a mold for curing to obtain a cast body of cyanate ester resin synergistically reinforced and toughened by modified CaCO3 whiskers and cage-shaped polyhedral oligomeric silsesquioxane particles.

[0010] In the preparation method of the cyanate ester resin described above, the cage-shaped polyhedral oligomeric silsesquioxane particles include a cage structure composed of a silicon-oxygen backbone connected alternately by Si-O, and it has a bridging constraint effect between the cyanate ester resin matrix and the modified CaCO3 whiskers.

[0011] In the preparation method of the cyanate ester resin described above, the mass ratio of the cyanate ester resin, modified CaCO3 whiskers, cage-shaped polyhedral oligomeric silsesquioxane particles and the curing system is 100:(3 - 6):(2 - 4):(2 - 5).

[0012] In the preparation method of the cyanate ester resin described above, the first predetermined temperature is 85°C. After ultrasonic dispersion for 1 h, stir at 85°C for 4 h, and separate the product by a centrifuge.

[0013] In the preparation method of the cyanate ester resin described above, the second predetermined temperature is 90°C.

[0014] In the preparation method of the cyanate ester resin described above, dry at 80°C for 24 h to obtain modified CaCO3 whiskers.

[0015] In the preparation method of the cyanate ester resin described above, the cyanate ester resin is one or more of bisphenol A type cyanate ester prepolymer, bisphenol M type cyanate ester prepolymer and bisphenol F type cyanate ester prepolymer.

[0016] In the preparation method of the cyanate ester resin described above, the silane coupling agent diluent is prepared according to the mass ratio of silane coupling agent: absolute ethanol: deionized water of 0.2:10:90.

[0017] In the preparation method of the cyanate ester resin described above, the silane coupling agent includes γ-aminopropyltriethoxysilane or γ-glycidoxypropyltrimethoxysilane.

[0018] In the preparation method of the cyanate ester resin described above, the curing system includes a curing agent and a catalyst, where the curing agent is dicyandiamide and the catalyst is an organometallic complex.

[0019] A cyanate ester resin prepared by the method described above.

[0020] Compared with the prior art, the present invention has the following advantages: The present invention uses modified CaCO3 whiskers / cage-shaped polyhedral oligomeric silsesquioxane (POSS) particles to synergistically reinforce and toughen the resin. Among them, the POSS structure can have a bridging and restraining effect between the cyanate ester resin matrix and the modified CaCO3 whiskers, improve the dispersibility of the modified CaCO3 whiskers, and achieve a substantial improvement in the toughness of the resin. The cage-shaped polyhedral oligomeric silsesquioxane particles have a cage structure composed of a silicon-oxygen skeleton with alternating Si-O bonds, which can inhibit the movement of polymer molecular chains and endow them with good mechanical properties and thermal stability. At the same time, the POSS nanoparticles can terminate the development of the tip of microcracks, and the elasticity of the "cage" can play a toughening role. By modifying the R groups in the POSS structure and introducing reactive R groups, chemical bonding effects are generated, achieving good dispersion effects. The POSS nanoparticles can improve the strength of the resin and play a certain toughening effect, and synergistically with the modified CaCO3 whiskers to achieve simultaneous improvement in the strength and toughness of the resin. The synergistic reinforcement and toughening system resin in the present invention is simple to prepare, and this method can be directly adapted to various types of cyanate ester resins, realizing the high-efficiency and low-cost preparation of high-strength and high-toughness resins. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] By reading the following detailed description of the preferred specific embodiments, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0022] In the drawings:

[0023] Figure 1 is a schematic diagram of the mechanism of CaCO3 whiskers / POSS synergistic reinforcement and toughening resin of the present invention.

[0024] The following further explains the present invention in conjunction with the drawings and embodiments. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The specific embodiments of the present invention will be described in more detail below with reference to the drawings. Although the specific embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0026] It should be noted that in the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. The specification and claims do not distinguish components by the difference in nouns, but by the difference in the functions of the components. For example, the term "comprising" or "including" mentioned throughout the specification and claims is an open-ended term and should be interpreted as "including but not limited to". The subsequent description in the specification is the preferred embodiment for implementing the present invention, but the description is for the purpose of the general principles of the specification and is not used to limit the scope of the present invention. The protection scope of the present invention shall be subject to that defined by the appended claims.

[0027] For the convenience of understanding the embodiments of the present invention, the following will further explain with specific examples in conjunction with the drawings, and each drawing does not constitute a limitation on the embodiments of the present invention.

[0028] As Figure 1 shown, the preparation method of the cyanate ester resin comprises the following steps:

[0029] Step 1: Add CaCO3 whiskers into a diluent containing a silane coupling agent, stir after ultrasonic dispersion at a first predetermined temperature, centrifuge the product, and wash it repeatedly with deionized water and absolute ethanol, and then dry it to obtain modified CaCO3 whiskers;

[0030] Step 2: Stir and heat the cyanate ester resin to a second predetermined temperature, add cage-like polyhedral oligomeric silsesquioxane particles and the modified CaCO3 whiskers, and then stir;

[0031] Step 3: Add a curing system, stir evenly, defoam, pour it into a mold for curing, and obtain a cyanate ester resin casting body synergistically reinforced and toughened by the modified CaCO3 whiskers and the cage-like polyhedral oligomeric silsesquioxane particles.

[0032] The toughness of cyanate ester resin is significantly improved by initiating dimples with low-cost CaCO3 whiskers, and the tensile strength of the resin is enhanced by the cage-like polyhedral oligomeric silsesquioxane (POSS) nano-inorganic core structure. The three-dimensional structure of POSS can play a bridging and constraining role between the cyanate ester resin matrix and the modified CaCO3 whiskers. Typically, the cage-like polyhedral oligomeric silsesquioxane particles, i.e., POSS, include a cage structure composed of a silicon-oxygen backbone with alternating Si-O bonds, which bridge and constrain between the cyanate ester resin matrix and the modified CaCO3 whiskers. The cage-like polyhedral oligomeric silsesquioxane particles have a cage structure composed of a silicon-oxygen backbone with alternating Si-O bonds, which can inhibit the movement of polymer molecular chains and endow them with good mechanical properties and thermal stability. At the same time, POSS nanoparticles can terminate the development of the tip of microcracks, and the elasticity of the "cage" can play a toughening role. By modifying the R groups in the POSS structure and introducing reactive R groups, chemical bonding can be generated, achieving a good dispersion effect. POSS nanoparticles can improve the strength of the resin and play a certain toughening effect, and cooperate with the modified CaCO3 whiskers to simultaneously improve the strength and toughness of the resin. Thus, the present invention can achieve uniform dispersion of the toughening system and achieve the effect of enhancing and toughening the resin. The present invention solves the problem that traditional toughening methods are prone to reduce the strength of cyanate ester resin.

[0033] In the preferred embodiment of the preparation method of the cyanate ester resin described above, for the R groups in POSS, taking R as amino or epoxy group as an example, its three-dimensional structure of POSS realizes the bridging and constraining effect between the cyanate ester resin matrix and the modified CaCO3 whiskers through the following reaction mechanism:

[0034] (1) In the silane coupling agent dilution solution, the silane coupling agent will hydrolyze to generate silanol (taking KH550 as an example):

[0035]

[0036] (2) There are a large number of hydroxyl groups on the surface of calcium carbonate whiskers. Silanol will react with the hydroxyl groups, and active groups (amino group for KH550, epoxy group for KH560) will be grafted onto the surface of calcium carbonate whiskers:

[0037]

[0038] (3) The amino groups on the surface of POSS and calcium carbonate whiskers can react with the cyanate ester groups of the cyanate ester resin to produce urea structures and improve their binding properties:

[0039]

[0040] (4) The epoxy groups on the surface of POSS and calcium carbonate whiskers can react with the cyanate ester groups in the cyanate ester resin to generate oxazolidinone structures, and the rigid groups can improve the mechanical properties and thermal properties:

[0041]

[0042] In summary, the POSS particles themselves are nanoscale in size, and their cage-like structure can form nanoscale physical crosslinking points in the resin matrix. When the CaCO3 whiskers are dispersed in the resin, the POSS particles are adsorbed on the surface of the nanomaterials through chemical bonds or physical interactions, enabling the POSS particles to form a flexible transition layer in the interfacial region, alleviating the interfacial stress concentration between the resin and the nanomaterials, and at the same time restricting the free movement of the nanomaterials, playing a "constraining" role.

[0043] In a preferred embodiment of the preparation method of the cyanate ester resin described, the mass ratio of the cyanate ester resin, the modified CaCO3 whiskers, the cage-type polyhedral oligomeric silsesquioxane particles, and the curing system is 100:(3 - 6):(2 - 4):(2 - 5).

[0044] In a preferred embodiment of the preparation method of the cyanate ester resin described, the first predetermined temperature is 85 °C. This temperature is conducive to the hydrolysis of the silane coupling agent and the improvement of the surface grafting rate of the CaCO3 whiskers. After ultrasonic dispersion for 1 h, stirring is carried out at 85 °C for 4 h, and the product is separated by a centrifuge. The second predetermined temperature is 90 °C. At this temperature, the cyanate ester resin has a low viscosity, can be mixed evenly with the filler, and ensures a long processing process window after adding the curing agent.

[0045] In a preferred embodiment of the preparation method of the cyanate ester resin described, the modified CaCO3 whiskers are obtained by drying at 80 °C for 24 h.

[0046] In a preferred embodiment of the preparation method of the cyanate ester resin described, the cyanate ester resin is one or more of a bisphenol A type cyanate ester prepolymer, a bisphenol M type cyanate ester prepolymer, and a bisphenol F type cyanate ester prepolymer.

[0047] In a preferred embodiment of the preparation method of the cyanate ester resin described, the silane coupling agent diluent is prepared according to a mass ratio of silane coupling agent: absolute ethanol: deionized water of 0.2:10:90.

[0048] In a preferred embodiment of the preparation method of the cyanate ester resin described, the silane coupling agent includes γ-aminopropyltriethoxysilane or γ-glycidyletheroxypropyltrimethoxysilane.

[0049] In a preferred embodiment of the preparation method of the cyanate ester resin described, the curing system includes a curing agent and a catalyst. Among them, the curing agent is dicyandiamide, and the catalyst is an organometallic complex. More preferably, the catalyst is an organonickel catalyst, an organotin catalyst, etc.

[0050] A cyanate ester resin, with the improvement range of fracture toughness being 56% - 63% and ensuring the improvement range of tensile strength being 12% - 20%, is prepared by the described method.

[0051] In one embodiment, the cage-like polyhedral oligomeric silsesquioxane particles are selected from one or more of amino POSS and epoxy POSS.

[0052] In one embodiment, the curing agent is preferably nickel acetylacetonate, and the curing process is 140°C / 2h + 180°C / 2h.

[0053] In one embodiment, the method includes

[0054] (1) Add CaCO3 whiskers into a diluent containing a silane coupling agent, ultrasonically disperse for 1 h, then stir at 85°C for 4 h, separate the product using a centrifuge, wash it with deionized water and absolute ethanol multiple times, and dry it at 80°C for 24 h to obtain modified CaCO3 whiskers.

[0055] (2) Stir and heat the cyanate ester resin to 90°C, add POSS particles and modified CaCO3 whiskers, and stir for 1 h.

[0056] (3) Add an appropriate amount of curing agent and catalyst, stir evenly, defoam, pour it into a mold, and place it in an oven for curing to obtain a CaCO3 whisker / POSS synergistically reinforced and toughened cyanate ester resin casting.

[0057] In one embodiment, after the resin and the curing agent are uniformly mixed, put them into a vacuum oven, carry out vacuum defoaming at 95°C until there are no bubbles inside the resin, and then pour it into a mold.

[0058] Example 1

[0059] (1) Add 10 g of CaCO3 whiskers into a diluent containing KH560, ultrasonically disperse for 1 h, then stir at 85°C for 4 h, separate the product using a centrifuge, wash it with deionized water and absolute ethanol multiple times, and dry it at 80°C for 24 h to obtain modified CaCO3 whiskers.

[0060] (2) Weigh 100 g of bisphenol A cyanate ester resin, stir and heat it to 90 °C, add 2 g of POSS-NH2 particles and 5 g of modified CaCO3 whiskers, and stir for 1 h. Among them, the preparation technology of POSS-NH2 particles can be referred to the academic literature "Self-assembled proton conduction networks consisting of SPEEK, NH2-POSS, and IL with enhanced proton conduction and decreased IL loss", DOI: 10.1016 / j.polymer.2022.125011.

[0061] (3) Add 0.4 g of nickel acetylacetonate as the organic nickel catalyst and 2 g of dicyandiamide as the curing agent, stir evenly, defoam, pour into a mold, and place it in an oven for curing (140 °C / 2 h + 180 °C / 2 h) to obtain a CaCO3 whisker / POSS synergistically reinforced and toughened cyanate ester resin casting.

[0062] Example 2

[0063] (1) Add 10 g of CaCO3 whiskers to a diluent containing KH560, ultrasonically disperse for 1 h, stir at 85 °C for 4 h, separate the product by centrifuge, and wash it repeatedly with deionized water and absolute ethanol, and dry it at 80 °C for 24 h to obtain modified CaCO3 whiskers.

[0064] (2) Weigh 100 g of bisphenol A cyanate ester resin, stir and heat it to 90 °C, add 4 g of POSS-NH2 particles and 3 g of modified CaCO3 whiskers, and stir for 1 h.

[0065] (3) Add 0.4 g of nickel acetylacetonate as the organic nickel catalyst and 4.6 g of dicyandiamide as the curing agent, stir evenly, defoam, pour into a mold, and place it in an oven for curing (140 °C / 2 h + 180 °C / 2 h) to obtain a CaCO3 whisker / POSS synergistically reinforced and toughened cyanate ester resin casting.

[0066] Comparative Example 1

[0067] (1) Weigh 100 g of bisphenol A cyanate ester resin, stir and heat it to 90 °C, mix it evenly with 0.4 g of nickel acetylacetonate and 1.6 g of dicyandiamide, defoam, pour into a mold, and place it in an oven for curing (140 °C / 2 h + 180 °C / 2 h) to obtain a pure cyanate ester resin casting.

[0068] Comparative Example 2

[0069] (1) Add 10 g of CaCO3 whiskers to the dilution containing KH560. After ultrasonic dispersion for 1 h, stir at 85 °C for 4 h. Separate the product by a centrifuge, and wash it with deionized water and absolute ethanol for multiple times. Dry it at 80 °C for 24 h to obtain modified CaCO3 whiskers.

[0070] (2) Weigh 100 g of bisphenol A cyanate ester resin, stir and heat it to 90 °C, add 6 g of modified CaCO3 whiskers, and stir for 1 h.

[0071] (3) Add 0.4 g of nickel acetylacetonate as an organic nickel catalyst and 2 g of dicyandiamide as a curing agent. After stirring evenly, defoam, pour it into a mold, and place it in an oven for curing (140 °C / 2 h + 180 °C / 2 h) to obtain a CaCO3 whisker toughened cyanate ester resin casting.

[0072] Performance tests of examples and comparative examples

[0073] Perform performance tests on the resin castings prepared in the above examples and comparative examples. The tensile performance test standard is ASTM D638 - 10, and the test loading rate is 1 mm / min; the fracture toughness test standard is ASTM D5045 - 14S, the test loading rate is 10 mm / min, and the span is 40 mm.

[0074] Table 1 Performance test results

[0075]

[0076] Example 1 of the CaCO3 whisker / POSS synergistic reinforcement and toughening cyanate ester resin of the present invention has the best performance. The resin has a significant improvement in fracture toughness, and at the same time maintains the strength and modulus of the resin. This is because a small amount of POSS particles can improve the strength of the resin matrix and play a bridging role between the resin and the CaCO3 whiskers, making the CaCO3 whiskers evenly dispersed in the resin system. This method is applicable to a variety of resins and provides a new idea for realizing a resin design method with excellent comprehensive performance.

[0077] Although the embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields. The above specific embodiments are merely illustrative and guiding, rather than restrictive. Those of ordinary skill in the art can also make many forms under the inspiration of this specification and without departing from the scope protected by the claims of the present invention, and these all belong to the scope of protection of the present invention.

Claims

1. A preparation method of a cyanate ester resin, characterized in that, It includes the following steps: Step 1: Add CaCO3 whiskers into a diluent containing a silane coupling agent, ultrasonically disperse, stir at a first predetermined temperature, centrifuge the product, and wash it repeatedly with deionized water and absolute ethanol, then dry to obtain modified CaCO3 whiskers; Step 2: Stir and heat the cyanate ester resin to a second predetermined temperature, add cage-like polyhedral oligomeric silsesquioxane particles and the modified CaCO3 whiskers, and then stir; Step 3: Add a curing system, stir evenly, defoam, pour into a mold for curing to obtain a cyanate ester resin casting body synergistically reinforced and toughened by the modified CaCO3 whiskers and cage-like polyhedral oligomeric silsesquioxane particles.

2. The preparation method of a cyanate ester resin according to claim 1, characterized in that, The mass ratio of the cyanate ester resin, the modified CaCO3 whiskers, the cage-like polyhedral oligomeric silsesquioxane particles and the curing system is 100:(3 - 6):(2 - 4):(2 - 5).

3. The preparation method of a cyanate ester resin according to claim 1, characterized in that, The first predetermined temperature is 85 °C. After ultrasonic dispersion for 1 h, stir at 85 °C for 4 h, and separate the product by a centrifuge.

4. A method for preparing a cyanate ester resin according to claim 1, characterized in that, The second predetermined temperature is 90 °C.

5. The preparation method of a cyanate ester resin according to claim 1, characterized in that Dry at 80 °C for 24 h to obtain the modified CaCO3 whiskers.

6. The preparation method of a cyanate ester resin according to claim 1, characterized in that, The cyanate ester resin is one or more of bisphenol A type cyanate ester prepolymer, bisphenol M type cyanate ester prepolymer and bisphenol F type cyanate ester prepolymer.

7. A method for preparing a cyanate ester resin according to claim 1, characterized in that, The silane coupling agent diluent is prepared according to the mass ratio of silane coupling agent: absolute ethanol: deionized water of 0.2:10:

90.

8. The preparation method of a cyanate ester resin according to claim 7, characterized in that, The silane coupling agent includes γ-aminopropyltriethoxysilane or γ-glycidoxypropyltrimethoxysilane.

9. The preparation method of a cyanate ester resin according to claim 1, characterized in that, The curing system includes a curing agent and a catalyst, wherein the curing agent is dicyandiamide and the catalyst is an organometallic complex.

10. A cyanate ester resin, characterized in that, It is prepared by the preparation method described in any one of claims 1 - 9.

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