A naphthalene ring liquid crystal epoxy resin monomer and a preparation method thereof, a naphthalene ring liquid crystal epoxy resin and a preparation method and application thereof

Abstract

The application provides a naphthalene ring liquid crystal epoxy resin monomer and a preparation method thereof, a naphthalene ring liquid crystal epoxy resin and a preparation method and application thereof, and belongs to the field of high polymer materials. The naphthalene ring liquid crystal epoxy resin monomer contains a naphthalene ring group with super-rigidity and strong symmetry, the intermolecular pi-pi stacking effect is strong, the liquid crystal texture formed after curing has higher order degree, and the average free path of phonons can be improved, so that the naphthalene ring liquid crystal epoxy resin has higher intrinsic lambda. In addition, the super-rigidity and strong symmetry structure of the naphthalene ring can effectively reduce the liquid crystal temperature range of the naphthalene ring liquid crystal epoxy resin monomer, and can endow the naphthalene ring liquid crystal epoxy resin with excellent thermal performance and mechanical performance, and is expected to widen the application in the fields of electronic packaging and thermal management. The results of examples show that the intrinsic lambda of the naphthalene ring liquid crystal epoxy resin provided by the application is increased by about 122% compared with the intrinsic lambda of general epoxy resin.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to a naphthalene ring liquid crystal epoxy resin monomer and its preparation method, a naphthalene ring liquid crystal epoxy resin and its preparation method and applications. Background Technology

[0002] With the development of thinner, lighter, smarter, and higher-power electronic devices and integrated circuits, the problem of heat accumulation during operation has become increasingly serious. There is an urgent need for high thermal conductivity materials to conduct heat to the surrounding environment in a timely and efficient manner, so as to avoid the impact of high temperature environment on the performance and life of electronic devices.

[0003] Epoxy resins possess strong adhesion, low shrinkage, and excellent chemical resistance, making them widely used in electronic device packaging and other fields. However, epoxy resins have a low intrinsic thermal conductivity (λ, approximately 0.2 W / (m·K)), which makes it difficult to meet the high thermal conductivity requirements of electronic devices and integrated circuits. Optimizing the molecular chain structure to obtain special physical structures (orientation, liquid crystal, and crystalline structures, etc.) can significantly improve the intrinsic λ of epoxy resins. A common method is to introduce benzene-ring-containing liquid crystal units (aromatic esters, aromatic ketones, and biphenyls, etc.) into the epoxy resin molecular structure to increase the orderliness of its molecular chains. This allows heat to be conducted rapidly along the ordered direction of the molecular chains, reducing phonon scattering and improving the intrinsic λ to varying degrees.

[0004] However, the liquid crystal temperature range for synthesizing benzene ring-containing liquid crystal epoxy monomers is generally high (>120℃), resulting in a fast curing rate. This makes it difficult to effectively remove air bubbles during processing, thus affecting the thermal and mechanical properties of the epoxy resin. Moreover, the curing temperature of epoxy resins used in electronic devices and integrated circuits is generally suitable between 60 and 80℃. Excessively high curing temperatures can affect their performance and reliability, and may even damage electronic devices.

[0005] Therefore, there is an urgent need to research and develop liquid crystal epoxy resins with excellent intrinsic λ, thermal properties, and mechanical properties in the low liquid crystal temperature range. Summary of the Invention

[0006] This invention provides a naphthalene ring liquid crystal epoxy resin monomer and its preparation method, a naphthalene ring liquid crystal epoxy resin and its preparation method and application. The naphthalene ring liquid crystal epoxy resin prepared using the naphthalene ring liquid crystal epoxy resin monomer of this invention has a low liquid crystal temperature range, excellent intrinsic λ, thermal properties and mechanical properties.

[0007] This invention provides a naphthalene ring liquid crystal epoxy resin monomer, characterized in that it has the structure shown in Formula I:

[0008]

[0009]

[0010] Where n≥1, m≥1.

[0011] Preferably, n is 1 to 20.

[0012] This invention also provides a method for preparing the naphthalene ring liquid crystal epoxy resin monomer described in the above technical solution, comprising the following steps:

[0013] A dehydrobromide reaction is carried out by mixing dihydroxynaphthalene, ethyl brominated saturated fatty acid, an inorganic basic catalyst, and a first organic solvent to obtain a first compound having the structure shown in Formula III or Formula IV; the structure of the dihydroxynaphthalene is a centrosymmetric structure.

[0014]

[0015]

[0016] The first compound was dissolved in a second organic solvent and then mixed with a strong alkali solution and an acid solution in sequence to carry out a hydrolysis reaction, thereby obtaining a second compound having the structure shown in formula V or formula VI.

[0017]

[0018]

[0019] The second compound, the epoxy alcohol compound, the catalyst, the dehydrating agent and the third organic solvent are mixed and subjected to an esterification reaction to obtain the naphthalene ring liquid crystal epoxy resin monomer;

[0020] The epoxy alcohol compound has the structure shown in Formula VII:

[0021]

[0022] Preferably, the bromofatty acid ethyl ester includes one of ethyl bromoethyl ester, ethyl 4-bromobutyrate, and ethyl 6-bromohexanoate.

[0023] Preferably, the dihydroxynaphthalene comprises 1,5-dihydroxynaphthalene.

[0024] Preferably, the molar ratio of the dihydroxynaphthalene to the ethyl bromide saturated fatty acid is 1:2 to 3.

[0025] Preferably, the inorganic alkaline catalyst includes one or more of potassium carbonate, potassium iodide, and sodium hydroxide;

[0026] The molar ratio of the dihydroxynaphthalene to the inorganic alkaline catalyst is 1:2 to 6.

[0027] The present invention also provides a method for preparing a naphthalene ring liquid crystal epoxy resin, comprising the following steps: mixing the naphthalene ring liquid crystal epoxy resin monomer described in the above technical solution or the naphthalene ring liquid crystal epoxy resin prepared by the preparation method described in the above technical solution with a curing agent and then curing it to obtain the naphthalene ring liquid crystal epoxy resin.

[0028] The present invention also provides a naphthalene ring liquid crystal epoxy resin prepared by the preparation method described in the above technical solution.

[0029] This invention also provides the application of the naphthalene ring liquid crystal epoxy resin described above in the fields of electronic packaging or thermal management.

[0030] The naphthalene ring liquid crystal epoxy resin monomer of the present invention contains naphthalene ring groups with ultra-rigid and strongly symmetrical structures. The strong π-π stacking interaction between its molecules results in a higher degree of ordered liquid crystal texture after curing, which is more conducive to increasing the mean free path of phonons and endowing the naphthalene ring liquid crystal epoxy resin with a higher intrinsic λ. Furthermore, the ultra-rigid and strongly symmetrical structure of the naphthalene ring can effectively reduce the liquid crystal temperature range of the naphthalene ring liquid crystal epoxy resin monomer, while also endowing the naphthalene ring liquid crystal epoxy resin with excellent thermal and mechanical properties, potentially broadening its applications in electronic packaging and thermal management. The results of the embodiments show that the intrinsic λ of the naphthalene ring liquid crystal epoxy resin provided by the present invention is 0.40 W / (m·K), which is approximately 122% higher than the intrinsic λ of general epoxy resins (0.18 W / (m·K)). Attached Figure Description

[0031] Figure 1 The 1H NMR spectra of the intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomers provided in Examples 1-3;

[0032] Figure 2 The carbon NMR spectra of the intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomers provided in Examples 1-3;

[0033] Figure 3 High-resolution mass spectra of intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomers provided in Examples 1-3;

[0034] Figure 4 Fourier transform infrared spectra of the intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomers provided in Examples 1-3;

[0035] Figure 5 Polarized microscope images of the naphthalene ring liquid crystal epoxy monomers provided in Examples 1-3. Detailed Implementation

[0036] This invention provides a naphthalene ring liquid crystal epoxy resin monomer having the structure shown in Formula I:

[0037]

[0038]

[0039] Where n≥1, m≥1.

[0040] In this invention, n is preferably 1 to 20. In specific embodiments of this invention, n can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0041] The preferred value of m is 1 to 20. In specific embodiments of the present invention, m can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0042] This invention also provides a method for preparing the naphthalene ring liquid crystal epoxy resin monomer described in the above technical solution, comprising the following steps:

[0043] Dihydroxynaphthalene, ethyl brominated saturated fatty acid, an inorganic basic catalyst, and a first organic solvent are mixed and subjected to a dehydrobromination reaction to obtain a first compound having the structure shown in Formula III or Formula IV.

[0044] The structure of the dihydroxynaphthalene is centrosymmetric.

[0045]

[0046]

[0047] The first compound was dissolved in a second organic solvent and then mixed with a strong alkali solution and an acid solution to carry out a hydrolysis reaction, thereby obtaining a second compound having the structure shown in formula V or formula VI.

[0048]

[0049]

[0050] The second compound, the epoxy alcohol compound, the catalyst, the dehydrating agent and the third organic solvent are mixed and subjected to an esterification reaction to obtain the naphthalene ring liquid crystal epoxy resin monomer;

[0051] The epoxy alcohol compound has the structure shown in Formula VII:

[0052]

[0053] All raw materials and / or reagents in the embodiments of the present invention were purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0054] In this invention, dihydroxynaphthalene, ethyl brominated saturated fatty acid, an inorganic alkaline catalyst, and a first organic solvent are mixed and subjected to a dehydrobromination reaction to obtain a first compound.

[0055] In this invention, the mixing preferably includes dissolving dihydroxynaphthalene in a first organic solvent, and then mixing the resulting solution sequentially with an inorganic alkaline catalyst and a brominated saturated fatty acid ethyl ester.

[0056] In this invention, the dissolution is preferably carried out under magnetic stirring conditions; there are no special limitations on the stirring rate and time in this invention, as long as the components are mixed evenly.

[0057] When the bromosaturated fatty acid ethyl ester is a liquid (e.g., ethyl bromoacetate, ethyl 4-bromobutyrate, ethyl 6-bromohexanoate), the preferred method of mixing with the bromosaturated fatty acid ethyl ester is dropwise addition; the present invention does not impose any special limitations on the dropwise addition rate and time, and dropwise addition rates and times known to those skilled in the art can be used.

[0058] In this invention, the molar ratio of dihydroxynaphthalene to ethyl brominated saturated fatty acid is preferably 1:2 to 3. In specific embodiments of this invention, the molar ratio of dihydroxynaphthalene to ethyl brominated saturated fatty acid can be 1:2 to 3, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, or 1:3.

[0059] In this invention, the dihydroxynaphthalene has a centrosymmetric structure; the dihydroxynaphthalene preferably includes 1,5-dihydroxynaphthalene; the raw materials for preparing the brominated saturated fatty acid ethyl ester preferably include brominated fatty acids and ethanol; the brominated fatty acid has 1 to 15 carbon atoms, and in specific embodiments of this invention, the brominated fatty acid can be one of ethyl bromoacetate, ethyl 4-bromobutyrate, and ethyl 6-bromohexanoate. When the molar ratio of dihydroxynaphthalene to brominated saturated fatty acid ethyl ester is less than 1:3, the dehydrobromination reaction is incomplete due to the excess of brominated saturated fatty acid ethyl ester, resulting in a large amount of brominated saturated fatty acid ethyl ester residue in the product; when the molar ratio of dihydroxynaphthalene to brominated saturated fatty acid ethyl ester is greater than 1:2, dihydroxynaphthalene is in excess, resulting in a large amount of dihydroxynaphthalene residue in the product; when the molar ratio of dihydroxynaphthalene to brominated saturated fatty acid ethyl ester is preferably 1:2.5, the dehydrobromination reaction is complete, with a small amount of brominated saturated fatty acid ethyl ester residue, which can be completely removed by subsequent washing.

[0060] In this invention, the molar ratio of dihydroxynaphthalene to the inorganic basic catalyst is preferably 1:2 to 6. In specific embodiments of this invention, the molar ratio of dihydroxynaphthalene to the inorganic basic catalyst can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, or 1:6. The inorganic basic catalyst includes one or more of potassium carbonate, potassium iodide, and sodium hydroxide. In specific embodiments of this invention, the inorganic basic catalyst can be potassium carbonate. When the molar ratio of dihydroxynaphthalene to the inorganic basic catalyst is less than 1:6, the inorganic basic catalyst is in excess, and the product contains residual inorganic basic catalyst. When the molar ratio of dihydroxynaphthalene to the inorganic basic catalyst is greater than 1:2, dihydroxynaphthalene is in excess, and the inorganic basic catalyst cannot completely react with the hydroxyl groups in dihydroxynaphthalene, resulting in incomplete dehydrobromide reaction and residual dihydroxynaphthalene in the product.

[0061] The reaction mechanism of inorganic basic catalysts involves the hydroxide ions in the catalyst acting as nucleophiles to attack the halogen atoms in organic halogen compounds, causing them to release halogen atoms and generate aromatic compounds through a dehydrobromide reaction. Inorganic basic catalysts can promote the removal of halogen atoms from halogen compounds, causing p-hydroxybiphenyl to lose one molecule of alcohol and gain one molecule of the first compound and hydrogen bromide.

[0062] In this invention, the molar ratio of the dihydroxynaphthalene to the first organic solvent is preferably 1:10 to 500. In specific embodiments of this invention, the molar ratio of the dihydroxynaphthalene to the first organic solvent can be 1:100, 1:200, 1:300, 1:400, 1:450, or 1:500. In specific embodiments of this invention, the solid-liquid ratio of the dihydroxynaphthalene to the first organic solvent can be 1.49 g:200 mL. The first organic solvent preferably includes acetone. Acetone has the advantage of good solubility for all reactants, which promotes the forward reaction.

[0063] In this invention, the temperature of the dehydrobromide removal reaction is preferably 60–100°C, and the time is preferably 6–72 h. In specific embodiments of this invention, the temperature of the dehydrobromide removal reaction can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C, and the time of the dehydrobromide removal reaction can be 6 h, 12 h, 18 h, 24 h, 30 h, 36 h, 42 h, 48 h, 54 h, 60 h, 66 h, or 72 h.

[0064] In this invention, the dehydrobromination reaction is preferably carried out under oil bath conditions.

[0065] After the dehydrobromination reaction is completed, the present invention preferably extracts and separates the product obtained from the dehydrobromination reaction in sequence, and then rotates and dries the separated organic phase to obtain the first compound.

[0066] In this invention, the solvent used for extraction preferably includes diethyl ether and dilute hydrochloric acid solution; the volume ratio of the diethyl ether and dilute hydrochloric acid solution is preferably 1:1 to 3; and the concentration of the dilute hydrochloric acid is preferably 0.5 to 2 mol / L.

[0067] The present invention does not specifically limit the parameters of the rotary evaporation, as long as the first organic solvent can be removed.

[0068] In this invention, the drying method is preferably vacuum drying; the vacuum drying is preferably carried out in a vacuum drying oven, the drying temperature is preferably 40-50°C, and the drying time is preferably 36-48 hours.

[0069] After obtaining the first compound, the present invention dissolves the first compound in a second organic solvent and then mixes it with a strong alkali solution and an acid solution to carry out a hydrolysis reaction to obtain the second compound.

[0070] In this invention, the mixing preferably includes adding a strong alkali solution and an acid solution dropwise to the solution obtained by dissolution. This invention does not have a special limitation on the dropping rate, and any dropping rate known to those skilled in the art can be used.

[0071] In this invention, the dissolution is preferably carried out under magnetic stirring conditions; there are no special limitations on the stirring rate and time in this invention, as long as the mixture is homogeneous.

[0072] In this invention, the molar ratio of the first compound to the second organic solvent is preferably 1:10 to 250. In specific embodiments of this invention, the molar ratio of the first compound to the second organic solvent can be 1:10, 1:40, 1:80, 1:120, 1:160, 1:200, or 1:250. The second organic solvent preferably includes tetrahydrofuran. Tetrahydrofuran has the advantage of good solubility for the first compound, which promotes the forward reaction.

[0073] In this invention, the molar ratio of the first compound to the strong base in the strong base solution is preferably 1:5 to 200. In specific embodiments of this invention, the molar ratio of the first compound to the strong base in the strong base solution can be 1:5, 1:10, 1:40, 1:80, 1:120, 1:160, or 1:200. The concentration of the strong base solution is preferably 0.5 to 1 mol / L. In specific embodiments of this invention, the concentration of the strong base solution can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, or 1 mol / L. The strong base solution preferably includes sodium hydroxide solution and / or potassium hydroxide solution.

[0074] In this invention, the interval between mixing with the strong alkali solution and mixing with the acid solution is preferably 12 to 24 hours. In specific embodiments of this invention, the interval between mixing with the strong alkali solution and mixing with the acid solution can be 12 hours, 15 hours, 18 hours, 21 hours, or 24 hours.

[0075] In this invention, the molar ratio of the first compound to the acid in the acid solution is preferably 1:10 to 200. In specific embodiments of this invention, the molar ratio of the first compound to the acid in the acid solution can be 1:10, 1:40, 1:80, 1:120, 1:160, or 1:200. The concentration of the acid solution is preferably 0.5 to 2 mol / L. In specific embodiments of this invention, the concentration of the acid solution can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, or 2 mol / L. The acid solution preferably includes hydrochloric acid.

[0076] In this invention, the preferred temperature for the hydrolysis reaction is 0–50°C, and the preferred time is 6–72 h. In specific embodiments of this invention, the temperature for the hydrolysis reaction can be 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, or 50°C, and the preferred time for the hydrolysis reaction can be 6 h, 12 h, 24 h, 48 h, 60 h, or 72 h. The preferred time for the hydrolysis reaction is calculated from the time the acid solution is added.

[0077] During hydrolysis, the first compound with the structure shown in formula III or IV breaks at the ends of the molecular chains under the action of a strong base, and then forms a second compound with the structure shown in formula V or VI under the action of an acid solution.

[0078] After the hydrolysis reaction is completed, the present invention preferably filters and dries the reaction product obtained from the hydrolysis reaction to obtain the second compound.

[0079] In this invention, the drying method preferably includes vacuum drying, which is preferably carried out in a vacuum drying oven; the drying temperature is preferably 40-50°C, and the drying time is preferably 36-48 hours.

[0080] After obtaining the second compound, the present invention mixes the second compound, the epoxy alcohol compound, the catalyst, the dehydrating agent and the third organic solvent to carry out an esterification reaction to obtain the naphthalene ring liquid crystal epoxy resin monomer.

[0081] In this invention, the mixing preferably includes dissolving the second compound in a third organic solvent, and then sequentially adding the epoxy alcohol compound, the catalyst, and the dehydrating agent to the solution obtained by dissolution.

[0082] In this invention, the dissolution is preferably carried out under magnetic stirring conditions; this invention does not have special limitations on the stirring rate and time, as long as the components are mixed evenly.

[0083] In this invention, the preferred method for adding the glycidol, catalyst, and dehydrating agent is to add them in small amounts multiple times. This invention does not impose any special limitations on the addition rate and time; any addition rate and time known to those skilled in the art can be used.

[0084] In this invention, the molar ratio of the second compound to the third organic solvent is preferably 1:10 to 200. In specific embodiments of this invention, the solid-liquid ratio of the second compound to the third organic solvent can be 1:10, 1:40, 1:80, 1:120, 1:160 or 1:200; the third organic solvent preferably includes tetrahydrofuran.

[0085] In this invention, the molar ratio of the second compound to the epoxy alcohol compound is preferably 1:2 to 3. In specific embodiments of this invention, the molar ratio of the second compound to the epoxy alcohol compound can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, or 1:3; the epoxy alcohol compound preferably includes glycidol. When the molar ratio of the second compound to the epoxy alcohol compound is less than 1:3, the epoxy alcohol compound is in excess, and there is epoxy alcohol compound residue in the product. When the molar ratio of the second compound to the epoxy alcohol compound is greater than 1:2, the second compound is in excess, and the epoxy alcohol compound cannot completely react with the carboxyl group in the second compound, resulting in incomplete esterification and residue of the second compound in the product. When the molar ratio of the second compound to the epoxy alcohol compound is 1:2 to 3, the esterification reaction proceeds completely, and even if a small amount of epoxy alcohol compound remains, it can be completely removed by subsequent washing.

[0086] In this invention, the molar ratio of the second compound to the catalyst is preferably 1:3; the catalyst preferably includes acid catalysts, base catalysts, and enzyme catalysts. In a specific embodiment of this invention, the catalyst is 4-dimethylaminopyridine. 4-Dimethylaminopyridine is a super-nucleophilic acylation catalyst. Its structure allows the electron-donating dimethylamino group to resonate with the parent ring (pyridine ring), which can strongly activate the nitrogen atom on the ring to undergo nucleophilic substitution, and significantly catalyze the esterification reaction of highly sterically hindered, low-reactivity alcohol hydroxyl and epoxy groups.

[0087] The preferred mass ratio of the catalyst to the dehydrating agent is 1:0.05 to 10. In specific embodiments of the present invention, the mass ratio of the catalyst to the dehydrating agent can be 1:0.05, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10. The dehydrating agent preferably includes 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride. 1-Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride can act as a dehydrating agent in the reaction between alcohol hydroxyl groups and epoxy groups, promoting the reaction between epoxy groups and alcohol hydroxyl groups to generate the corresponding esters.

[0088] In this invention, the preferred temperature for the esterification reaction is 0–50°C, and the preferred time is 6–72 h. In specific embodiments of this invention, the temperature for the esterification reaction can be 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, or 50°C, and the preferred time for the esterification reaction can be 6 h, 12 h, 24 h, 48 h, 60 h, or 72 h.

[0089] After the esterification reaction is completed, the present invention preferably performs rotary evaporation, washing and drying on the product obtained by the esterification reaction to obtain an intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomer.

[0090] In this invention, the preferred temperature for rotary evaporation is 30-40°C. The present invention does not specifically limit the time for rotary evaporation, as long as the third organic solvent can be removed.

[0091] In this invention, the washing liquid used for washing preferably includes deionized water, and the washing preferably includes repeatedly mixing the solid obtained by rotary evaporation with deionized water and then stirring and centrifuging to separate it;

[0092] The stirring time for each stirring is 12 to 24 hours, the number of repetitions is preferably 3 to 5, and the centrifugation rate is preferably 7000 to 9000 r / min.

[0093] In this invention, the drying method preferably includes freeze drying, and the drying time is preferably 36 to 48 hours.

[0094] The present invention also provides a method for preparing a naphthalene ring liquid crystal epoxy resin, wherein the naphthalene ring liquid crystal epoxy resin monomer described in the above technical solution or the naphthalene ring liquid crystal epoxy resin monomer prepared by the preparation method described in the above technical solution is mixed with a curing agent and then cured.

[0095] In this invention, the mixing is preferably carried out under magnetic stirring conditions.

[0096] In this invention, the molar ratio of the liquid crystal epoxy monomer to the curing agent is preferably 0.5 to 2:1. In specific embodiments of this invention, the molar ratio of the liquid crystal epoxy monomer to the curing agent can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, or 2:1. The curing agent preferably includes one or more of amine curing agents, acid anhydride curing agents, phenolic curing agents, alkaline curing agents, and latent curing agents. In specific embodiments of this invention, the curing agent can be 4,4'-diaminodicyclohexylmethane curing agent.

[0097] When the molar ratio of the liquid crystal epoxy monomer to 4,4'-diaminodicyclohexylmethane is less than 2:1, 4,4'-diaminodicyclohexylmethane is in excess, resulting in residual 4,4'-diaminodicyclohexylmethane in the product. When the molar ratio is greater than 3:1, the naphthalene-cyclic liquid crystal epoxy monomer is in excess, and 4,4'-diaminodicyclohexylmethane cannot completely cure the naphthalene-cyclic liquid crystal epoxy monomer, leading to incomplete curing and residual naphthalene-cyclic liquid crystal epoxy monomer in the product. When the molar ratio of the liquid crystal epoxy monomer to 4,4'-diaminodicyclohexylmethane is 2–3:1, the curing reaction can proceed completely.

[0098] In this invention, the curing temperature is preferably 50-120°C, and the curing time is preferably 4-72 hours. In specific embodiments of this invention, the curing temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C; and the curing time can be 4 hours, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, or 72 hours.

[0099] The present invention also provides a naphthalene ring liquid crystal epoxy resin prepared by the preparation method described in the above technical solution.

[0100] This invention also provides the application of the naphthalene ring liquid crystal epoxy resin described above in the fields of electronic packaging or thermal management.

[0101] The following detailed description, in conjunction with embodiments, illustrates the naphthalene ring liquid crystal epoxy resin monomer and its preparation method, the naphthalene ring liquid crystal epoxy resin and its preparation method, and its applications. However, these descriptions should not be construed as limiting the scope of protection of this invention.

[0102] Example 1

[0103] (1) Dissolve 1,5-dihydroxynaphthalene, ethyl bromoacetate, and potassium carbonate in a first organic solvent and carry out a dehydrobromination reaction to obtain the first compound:

[0104] 1,5-Dihydroxynaphthalene (9.3 mmol, 1.49 g) was dissolved in 200 mL of acetone and stirred until clear and transparent. Potassium carbonate (54 mmol, 7.46 g) was then added, followed by the slow addition of ethyl bromoacetate (23.1 mmol, 3.86 g). The resulting mixture was refluxed at 70 °C for 3 days. After the reaction was complete, the reaction solution was cooled to room temperature and extracted with diethyl ether and hydrochloric acid (volume ratio of diethyl ether to hydrochloric acid 1:1.5, concentration of hydrochloric acid 0.5 mol / L). The organic layer was collected, and then rotary evaporated and dried to obtain the first compound.

[0105] (2) The first compound and sodium hydroxide are dissolved in a second organic solvent and subjected to a hydrolysis reaction to obtain the second compound:

[0106] The first compound (10 mmol, 3.88 g) was dissolved in 150 mL of tetrahydrofuran and stirred until clear and transparent. Then, 100 mL of sodium hydroxide aqueous solution (0.5 mol / L) was slowly added, and the reaction was allowed to proceed at room temperature for 12 h. 100 mL of hydrochloric acid aqueous solution (1 mol / L) was then slowly added to the above reaction solution, and the reaction continued for 3 days. The second compound was obtained by filtration and drying.

[0107] (3) The second compound, glycidol, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 4-dimethylaminopyridine are dissolved in a third organic solvent and subjected to an esterification reaction to obtain an intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomer:

[0108] The second compound (10 mmol, 3.32 g), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (30 mmol, 5.75 g), and 4-dimethylaminopyridine (added in an amount equal to 1 / 10 of the amount of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.58 g) were dissolved in 100 mL of tetrahydrofuran. After stirring until homogeneous, glycidol (30 mmol, 2.22 g) was slowly added dropwise. The mixture was reacted at room temperature for 24 h. After the reaction was complete, the reaction solution was cooled to room temperature, and obtained by rotary evaporation, washing, centrifugation, and drying to obtain the intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomer (N-LCE). I ).

[0109] (4) The intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomer and 4,4'-diaminodicyclohexylmethane curing agent are mixed evenly at a molar ratio of 2:1 at a temperature of 50-90°C. After degassing under vacuum, the mixture is poured into a preheated mold and cured for 8 hours. After demolding, the intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy resin (N-LCER) is obtained. I Its intrinsic λ is 0.30 W / (m·K).

[0110] Example 2

[0111] Intrinsically high thermal conductivity N-LCER was prepared according to the method in Example 1. II The difference is that ethyl bromoethyl is replaced with ethyl 4-bromobutyrate; the rest of the synthesis process is the same. The resulting intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomer is denoted as N-LCE. II .

[0112] It should be noted that the intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy resin obtained is denoted as N-LCER. II This intrinsically high thermal conductivity N-LCER II The intrinsic λ is 0.40 W / (m·K).

[0113] Example 3

[0114] Intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy resin (N-LCER) was prepared according to the method in Example 1. III The difference is that ethyl bromoacetate is replaced with ethyl 6-bromohexanoate; the rest of the synthesis process is the same. The resulting intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomer is denoted as N-LCE. III .

[0115] It should be noted that the intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy resin obtained is denoted as N-LCER. III This intrinsically high thermal conductivity N-LCER III The intrinsic λ is 0.37 W / (m·K).

[0116] To verify the intrinsically high thermal conductivity N-LCER prepared in Examples 1-3 of this invention... I-III The intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomer (N-LCE) provided in the embodiments of the present invention... I-III Nuclear magnetic resonance (NMR) hydrogen and carbon spectra, high-resolution mass spectra, and Fourier transform infrared spectroscopy were performed, and the results are as follows: Figures 1-4 As shown.

[0117] in, Figure 1 The 1H NMR spectra of the naphthalene ring liquid crystal epoxy monomers provided in Examples 1-3;

[0118] Figure 2 The carbon NMR spectra of the naphthalene ring liquid crystal epoxy monomers provided in Examples 1-3;

[0119] Figure 3 High-resolution mass spectra of the naphthalene ring liquid crystal epoxy monomers provided in Examples 1-3;

[0120] Figure 4 Fourier transform infrared spectra of the naphthalene ring liquid crystal epoxy monomers provided in Examples 1-3.

[0121] from Figure 1As can be seen, all naphthalene ring liquid crystal epoxy monomers exhibit characteristic peaks for hydrogen atoms on the naphthalene ring near 7.71 ppm, 7.40 ppm, and 6.98 ppm. Furthermore, after the dehydrobromination reaction, the characteristic peak for hydrogen atoms on the hydroxyl group at 9.93 ppm disappears in 1,5-dihydroxynaphthalene, and the proton characteristic peak of the methylene group closest to the oxygen atom on the naphthalene ring shifts to a lower field. This is because the electronegativity of oxygen atoms is greater than that of bromine atoms, resulting in a stronger electron-withdrawing inductive effect, which reduces the electron cloud density around the hydrogen atoms on the carbon atoms connected to them, causing the hydrogen atoms to shift to a lower field. In addition, the characteristic peaks of all naphthalene ring liquid crystal epoxy monomers near 4.39 ppm, 3.82 ppm, 3.18 ppm, 2.78 ppm, and 2.62 ppm are all attributed to the proton characteristic peaks of the epoxy group, and the integral area ratio of each characteristic peak matches the expected ratio of hydrogen atoms in the molecular structure.

[0122] from Figure 2 As can be seen, all naphthalene ring liquid crystal epoxy monomers exhibit characteristic peaks of carbon atoms in five different chemical environments on the naphthalene ring near 154.23 ppm, 126.82 ppm, 125.63 ppm, 114.41 ppm, and 106.48 ppm. The characteristic peaks near 65.59 ppm, 49.26 ppm, and 43.74 ppm are attributed to carbon atoms on the epoxy group. Furthermore, N-LCER... I N-LCER II and N-LCER III Characteristic peaks of carbon atoms on the flexible alkyl carbon chain appeared at 168.88 ppm and 68.48 ppm; 172.93 ppm, 67.01 ppm, 30.77 ppm and 24.74 ppm; and 173.19 ppm, 68.00 ppm and 33.66–24.52 ppm, respectively, and the number of characteristic peaks of carbon atoms was consistent with the number of carbon atoms in the expected molecular structure.

[0123] from Figure 3 It can be seen that the mass-to-charge ratios (m / z) of the molecular ion peaks with the highest relative intensity among all naphthalene ring liquid crystal epoxy monomers are 271.10, 389.04, 443.17, and 499.23, respectively, which are consistent with (C 20 H 20 O8,388.12; C 24 H 28 O8,444.18 and C 28 H 36 The relative molecular masses of O8,500.24 are basically the same.

[0124] from Figure 4 It can be seen that all naphthalene ring liquid crystal epoxy monomers are at 1601 cm⁻¹ -1 and 1509cm -1A stretching vibration peak of the naphthalene ring appears nearby, ranging from 2863 to 3064 cm⁻¹. -1 The stretching vibration peak of the methylene group appears at 1730 cm⁻¹. -1 Stretching vibration peaks of the carbonyl groups on the flexible alkyl carbon chains appeared in the vicinity. After the dehydrobromination reaction, all naphthalene ring liquid crystal epoxy monomers showed peaks at 3249 cm⁻¹. -1 The stretching vibration peaks of the hydroxyl groups all disappeared, and after the esterification reaction, the peak at 910 cm⁻¹ disappeared. -1 Stretching vibration peaks of epoxy groups were observed in the vicinity.

[0125] To verify the liquid crystal properties of the naphthalene ring liquid crystal epoxy monomers prepared in Examples 1-3 of this invention, the intrinsically thermally conductive naphthalene ring liquid crystal epoxy monomers prepared in Examples 1-3 were characterized by polarized light microscopy. The results are as follows: Figure 5 As shown, (a1) to (a4) represent the naphthalene ring liquid crystal epoxy monomers prepared in Example 1, (b1) to (b4) represent the naphthalene ring liquid crystal epoxy monomers prepared in Example 2, and (c1) to (c4) represent the naphthalene ring liquid crystal epoxy monomers prepared in Example 3.

[0126] from Figure 5 It can be seen that all monomers exhibit solid crystalline properties at room temperature (a1-c1); when heated to near their respective melting points (85℃, 67℃, and 51℃), they transform into fluid, bright yellow liquid crystals (a2-c2); as the temperature further increases, the bright yellow region decreases (a3-c3), until they all transform into liquids when heated to near their respective clearing points (108℃, 84℃, and 66℃), the bright yellow region completely disappears, and the field of view becomes completely transparent (a4-c4).

[0127] Therefore, all intrinsically high thermal conductivity naphthalene ring liquid crystal epoxy monomers are thermotropic liquid crystals with liquid crystal temperature ranges of 85–108℃, 67–84℃, and 51–66℃, respectively.

[0128] The intrinsic high thermal conductivity N-LCER of this invention was tested using a Hot Disk TPS2200 thermal conductivity tester. I-III The intrinsic λ of N-LCER I The intrinsic λ is 0.30 W / (m·K), N-LCER II The intrinsic λ is 0.40 W / (m·K), N-LCER Ⅲ The intrinsic λ is 0.37 W / (m·K).

[0129] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A naphthalene ring liquid crystal epoxy resin monomer characterized by, having a structure shown in Formula I or Formula II: Formula I; Formula II; n = 1-5, m = 1.

2. The method for preparing the naphthalene ring liquid crystal epoxy resin monomer according to claim 1, characterized in that, The method comprises the following steps: mixing dihydroxynaphthalene, brominated saturated fatty acid ethyl ester, inorganic alkaline catalyst and first organic solvent to carry out dehydrobromination reaction to obtain a first compound having a structure shown in Formula III or Formula IV; the dihydroxynaphthalene has a central symmetrical structure; Formula III; Formula IV; n = 1-5; dissolving the first compound in a second organic solvent, and then mixing with a strong alkali solution and an acid solution to carry out hydrolysis reaction, to obtain a second compound having a structure shown in Formula V or Formula VI; Formula V; Formula VI; mixing the second compound, epoxy alcohol compound, catalyst, dehydrating agent and third organic solvent to carry out esterification reaction, to obtain the naphthalene ring liquid crystal epoxy resin monomer; the epoxy alcohol compound has a structure shown in Formula VII: Formula VII; m = 1.

3. The production method according to claim 2, characterized by, the brominated saturated fatty acid ethyl ester comprises one of ethyl bromoacetate, ethyl 4-bromobutyrate and ethyl 6-bromohexanoate.

4. The production method according to claim 2, characterized by, the dihydroxynaphthalene comprises 1,5-dihydroxynaphthalene.

5. The production method according to claim 2, 3 or 4, characterized in that, the molar ratio of the dihydroxynaphthalene and the brominated saturated fatty acid ethyl ester is 1:2-3.

6. The production method according to claim 2 or 4, characterized by, the inorganic alkaline catalyst comprises one or more of potassium carbonate, potassium iodide and sodium hydroxide; the molar ratio of the dihydroxynaphthalene and the inorganic alkaline catalyst is 1:2-6.

7. A method for preparing a naphthalene ring liquid crystal epoxy resin, characterized by, The method comprises the following steps: mixing the naphthalene ring liquid crystal epoxy resin monomer of claim 1 or the naphthalene ring liquid crystal epoxy resin prepared by the preparation method of any one of claims 2-6 with a curing agent, and then carrying out curing to obtain the naphthalene ring liquid crystal epoxy resin.

8. The naphthalene ring liquid crystal epoxy resin prepared by the preparation method of claim 7.

9. Application of the naphthalene ring liquid crystal epoxy resin of claim 8 in the field of electronic packaging or thermal management.

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