Fluorine-containing polyphenyl ether with low molecular weight and preparation method thereof

Abstract

The invention discloses low-molecular-weight fluorine-containing polyphenyl ether and a preparation method thereof.The fluorine-containing polyphenyl ether has the following structure, polyhydroxy benzene rings are connected to polyphenyl ether, the reaction activity of a material in the fluorination process is improved, the multi-benzene-ring structure can improve the strength of the material, decafluorobiphenyl serves as a fluorination reagent, catalysis is combined with a basic catalyst, and the low-molecular-weight fluorine-containing polyphenyl ether is obtained. Efficient hydroxyl substitution and efficient fluorination are realized, and the product is high in fluorine content and uniform in structure. The product has the advantages of lower molecular weight, narrow molecular weight distribution and excellent dielectric property, and is suitable for the fields of high-frequency communication materials, high-temperature-resistant coatings and the like. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the technical field of fluorine-containing materials, and in particular to a low-molecular-weight fluorine-containing polyphenylene ether and a preparation method thereof. Background Art

[0002] As a high-performance engineering plastic, polyphenylene ether (PPO) is widely used in high-frequency communication substrates, integrated circuit packaging, aerospace composite materials and other fields due to its excellent high-temperature resistance, low dielectric constant, high dimensional stability and mechanical strength. However, traditional high-molecular-weight polyphenylene ether (Mn>10,000) has problems such as high melt viscosity and difficulty in processing and molding. It is usually necessary to reduce the processing temperature through blending or chemical modification, but this may lead to loss of material properties. Therefore, the development of low-molecular-weight polyphenylene ether (Mn<10,000) has become an important direction to solve the processing problem. However, the synthesis of low-molecular-weight polyphenylene ether in existing technologies often faces problems such as difficult to control molecular weight and poor structural controllability, which affects its application in the field of precision electronics.

[0003] On the other hand, the introduction of fluorinated polymers can significantly improve the dielectric properties (low dielectric constant and loss), chemical corrosion resistance and thermal stability of the material, and is especially suitable for 5G high-frequency and high-speed communication scenarios. In the existing technology, the preparation of fluorinated polyphenylene ether mostly adopts direct fluorination or fluorinated monomer copolymerization. However, the direct fluorination method has low reaction efficiency and easily leads to uneven fluorine distribution; and the fluorinated monomer copolymerization method is difficult to achieve precise control of the molecular chain structure due to the large difference in the activity of fluorinated monomers. In addition, the fluorination reaction in the existing method often requires the use of precious metal catalysts or harsh reaction conditions (such as high temperature and high pressure), resulting in high costs, many by-products, and it is difficult to avoid the formation of cross-linked structures, affecting the purity and performance of the product.

[0004] For the synthesis of low molecular weight polyphenylene ether, the prior art usually controls the degree of polymerization by adjusting the monomer feed ratio, the type of oxidative coupling catalyst or the reaction time. CN 110746594 A discloses a low molecular weight fluorinated polyphenylene ether with a number average molecular weight below 5000 and a molecular weight distribution index below 3. The preparation method of the low molecular weight fluorinated polyphenylene ether is as follows: polyphenylene ether with a number average molecular weight above 10000, a fluorinated polyphenol compound and a free radical initiator are redistributed in an organic solvent for reaction. After the reaction is completed, the low molecular weight fluorinated polyphenylene ether is obtained by post-processing. The obtained low molecular weight fluorinated polyphenylene ether is co-cured with an epoxy resin. The obtained composite material has a lower dielectric constant, dielectric loss factor and water absorption rate than similar materials without fluorine, and is more suitable for the application of high-frequency and high-speed copper-clad laminates, but its fluorine content is still to be improved. The traditional method lacks high efficiency and selectivity for the post-modification (such as fluorination) of the intermediate hydroxyl functional group, resulting in insufficient fluorine content or structural inhomogeneity in the final product.

[0005] CN 115160516 A discloses a thermosetting polyphenylene ether material containing trifluoromethyl groups, its preparation method, and its application. The thermosetting polyphenylene ether material comprises a reactive polyphenylene ether and an initiator; the reactive polyphenylene ether contains both a trifluoromethyl group and an alkenyl group, where x ≥ 0 and y ≥ 0. Phenol and its derivatives are used as linking groups, and trifluoromethyl groups and alkenyl groups containing carbon-carbon double bonds are simultaneously introduced onto the pendant methyl groups of the polyphenylene ether chain segments. The phenoxy groups in the phenol and its derivatives are grafted onto the pendant methyl groups of the polyphenylene ether via a nucleophilic reaction, thereby maintaining a low dielectric constant and avoiding the use of Grignard reagents during the preparation process, resulting in mild preparation conditions. However, the resulting polyphenylene ether has a high molecular weight.

[0006] In summary, there is an urgent need in the prior art for a method for preparing fluorinated low-molecular-weight polyphenylene ether with simple process, controllable molecular weight, high fluorination efficiency and narrow product distribution to meet the urgent demand for high-performance polymers in high-frequency electronic materials. Summary of the Invention

[0007] The present invention provides a low molecular weight fluorinated polyphenylene ether, which has a low molecular weight and a narrow molecular weight distribution, and a high fluorination efficiency during the preparation process and a low dielectric constant, and is suitable for high-frequency communication materials, high-temperature resistant coatings and other fields.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A low molecular weight fluorinated polyphenylene ether having the structural formula shown in formula (I):

[0010]

[0011]

[0012] The structure of AR is * indicates the connection site, m>0, n>0;

[0013] The molecular weight of the fluorinated polyphenylene ether is 3000-6000, and the molecular weight distribution is ≤2.

[0014] The dielectric constant of the fluorinated polyphenylene ether is 2.3-2.5.

[0015] The present invention also provides a method for preparing the low molecular weight fluorinated polyphenylene ether, comprising the steps of:

[0016] Step 1: catalytically polymerize 2,6-dimethylphenol and 1,1,1-tris(4-hydroxyphenyl)ethane in a solvent under an oxygen atmosphere to obtain an intermediate trihydroxypolyphenylene ether as shown in formula (II);

[0017]

[0018] Step 2: dissolving the trihydroxy polyphenylene ether and decafluorobiphenyl in a solvent, and reacting them in the presence of an alkaline catalyst to obtain the fluorinated polyphenylene ether.

[0019] In this invention, polyhydroxybenzene rings are attached to polyphenylene ether to enhance the material's reactivity during fluorination. The polyphenyl ring structure also improves the material's strength. Using decafluorobiphenyl as the fluorination agent, combined with an alkaline catalyst, this method achieves efficient hydroxyl substitution and fluorination, resulting in a product with a high fluorine content and a uniform structure. The product has a low molecular weight and a narrow molecular weight distribution, and exhibits excellent dielectric properties, making it suitable for applications such as high-frequency communication materials and high-temperature-resistant coatings.

[0020] In step 1, the molar ratio of 2,6-dimethylphenol to 1,1,1-tris(4-hydroxyphenyl)ethane is 10-20:1.

[0021] In step 1, the reaction temperature is 20-40° C. and the reaction time is 2-30 h.

[0022] The catalyst in step 1 comprises a combination catalyst of any one of ketone bromide, cupric bromide, cuprous iodide and any one of di-n-butylamine, n-propylamine, isopropylamine, n-butylamine, and sec-butylamine;

[0023] In step 1, the molar amount of the copper salt in the catalyst is 0.1-5% of the molar amount of the reactants, and the molar amount of the amine compound is 1-4 times the molar amount of the copper salt.

[0024] The solvent in step 1 includes a mixed solvent of one or more of toluene, methanol, xylene and ethylbenzene;

[0025] The product purification process in step 1 includes: precipitation of the reaction liquid in methanol after polymerization, washing, and drying to obtain the trihydroxy polyphenylene ether.

[0026] In step 2, the molar ratio of trihydroxy polyphenylene ether to decafluorobiphenyl is 1:1-1.1;

[0027] In step 2, the reaction temperature is 100-140° C. and the reaction time is 10-30 h;

[0028] The alkaline catalyst includes sodium carbonate and / or potassium carbonate, more preferably sodium carbonate; the molar amount of the alkaline catalyst is 1-3 times the total molar amount of the reactants.

[0029] The solvent in step 2 includes a mixed solvent of one or more of N-methylpyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide;

[0030] The product purification process in step 2 includes: adding methanol to the reaction solution and filtering, precipitating the filtrate in deionized water, washing and drying to obtain the fluorinated polyphenylene ether.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The fluorinated polyphenylene ether provided by the present invention has a controllable molecular weight. By adjusting the catalyst ratio, oxygen introduction rate and reaction time, the molecular weight of the intermediate can be accurately controlled to avoid excessive polymerization.

[0033] (2) The preparation process of the fluorinated polyphenylene ether of the present invention uses decafluorobiphenyl as a fluorination reagent, combined with an alkaline catalyst to achieve efficient hydroxyl substitution and efficient fluorination, and the product has a high fluorine content and a uniform structure.

[0034] (3) The preparation of the fluorinated polyphenylene ether of the present invention adopts a two-step precipitation method of methanol-deionized water, which effectively removes by-products and unreacted monomers and improves the purity of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the GPC chart of trihydroxy polyphenylene ether prepared in Preparation Example 1.

[0036] Figure 2 This is the GPC chart of trihydroxy polyphenylene ether prepared in Preparation Example 2.

[0037] Figure 3 This is the nuclear magnetic resonance spectrum of trihydroxy polyphenylene ether prepared in Preparation Example 1.

[0038] Figure 4 The infrared images of the products of Preparation Example 1 and Example 1 are shown.

[0039] Figure 5 This is the GPC chart of the fluorinated polyphenylene ether prepared in Example 1.

[0040] Figure 6 This is the GPC chart of the fluorinated polyphenylene ether prepared in Example 2.

[0041] Figure 7 This is the GPC chart of the polyphenylene ether prepared in Comparative Example 1.

[0042] Figure 8 The dielectric constants of the polyphenylene ethers prepared in Examples 1-2 and Comparative Example 1 are shown.

[0043] Figure 9 The dielectric loss of the polyphenylene ether prepared in Examples 1-2 and Comparative Example 1. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art will make modifications or equivalent substitutions based on understanding the technical solution of the present invention, without departing from the spirit and scope of the technical solution of the present invention, and all should be encompassed within the protection scope of the present invention.

[0045] The raw materials used in the following specific embodiments were purchased from the market, and the test methods for the experimental results in the preparation examples, embodiments, and comparative examples are as follows:

[0046] The number average molecular weight and molecular weight distribution index were determined using a Waters 1525 / 2414 gel permeation chromatograph with tetrahydrofuran as solvent, polystyrene as standard, and a differential detector.

[0047] NMR spectra: 1H NMR was measured using an Agilent 600 MHz DD2 NMR spectrometer using deuterated chloroform as the solvent.

[0048] Dielectric properties: measured using a Tonghui TH2826A LCR digital bridge meter, sample size 25mm*25mm*2mm, test frequency 1MHz.

[0049] Preparation Example 1

[0050] Weigh 20g of 2,6-dimethylphenol (DMP) and 3.85g of 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) into a beaker, add 80g of toluene and 20g of methanol, and dissolve thoroughly. At room temperature, weigh 0.6g of CuBr, 1mL of di-n-butylamine, and 50g of toluene into a four-necked flask, introduce oxygen, and start mechanical stirring. The system is heated to 30°C and maintained for 20 minutes. The completely dissolved DMP toluene solution is then added to the flask, and oxygen is introduced at 30°C for 4 hours. After the reaction is complete, the reaction solution is poured into 900g of methanol for precipitation, washed three times with methanol, and dried to obtain the intermediate product, trihydroxypolyphenylene ether.

[0051] Preparation Example 2

[0052] Weigh 20g of 2,6-dimethylphenol (DMP) and 2.95g of 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) into a beaker, add 80g of toluene and 20g of methanol, and dissolve thoroughly. At room temperature, weigh 0.6g of CuBr, 1mL of di-n-butylamine, and 50g of toluene into a four-necked flask, introduce oxygen, and start mechanical stirring. The system is heated to 30°C and maintained for 20 minutes. The completely dissolved DMP toluene solution is then added to the flask, and oxygen is introduced at 30°C for 4 hours. After the reaction is complete, the reaction solution is poured into 900g of methanol for precipitation, washed three times with methanol, and dried to obtain the intermediate product, trihydroxypolyphenylene ether.

[0053] Figure 1 、 Figure 2 The GPC spectrum of the prepared trihydroxy polyphenylene ether is shown in Table 1. The NMR spectrum of the trihydroxy polyphenylene ether prepared in Preparation Example 1 is shown in Table 1. Figure 3 As shown, it can be seen that the target product is successfully obtained, and the molecular weight of the product is low and the molecular weight distribution is narrow.

[0054] Table 1 Molecular weight and molecular weight distribution of trihydroxy polyphenylene ether of Preparation Example 1 and Preparation Example 2

[0055] Preparation Example Mn Mw PDI Preparation Example 1 2052 4030 1.96 Preparation Example 2 2513 3977 1.58

[0056] Example 1

[0057] 10 g of trihydroxy polyphenylene ether (TPPE) prepared in Preparation Example 1 and 1.7 g of decafluorobiphenyl (DFBP) were placed in a three-necked flask equipped with a serpentine condenser and a mechanical stirrer. 100 mL of N-methylpyrrolidone was added to fully dissolve the mixture. After heating to 120°C, 3.7 g of KCO was added and stirred for 18 hours. After the reaction, 20 g of methanol was added and stirred until uniform. The precipitated polymer was filtered off, and the clarified mixture was added to deionized water. The precipitate was collected, washed repeatedly with water several times, and dried in a vacuum oven to obtain the fluorinated low-molecular-weight polyphenylene ether.

[0058] Example 2

[0059] Weigh 10 g of the trihydroxy polyphenylene ether prepared in Preparation Example 2 and 1.34 g of decafluorobiphenyl (DFBP) into a three-necked flask equipped with a serpentine condenser and a mechanical stirrer. Add 100 mL of N-methylpyrrolidone to fully dissolve the mixture. Heat to 120°C, then add 3.7 g of K₂CO₃ and stir for 18 hours. After the reaction is complete, add 20 g of methanol and stir until uniform. Filter out the precipitated polymer, add the clarified mixture to deionized water, collect the precipitate, wash it repeatedly with water several times, and dry it in a vacuum oven to obtain the fluorinated low-molecular-weight polyphenylene ether.

[0060] Comparative Example 1

[0061] Weigh 20g of 2,6-dimethylphenol (DMP) and 1.55g of tetramethylbisphenol A (TMBPA) into a beaker, add 80g of toluene and 20g of methanol, and dissolve thoroughly. At room temperature, weigh 0.6g of CuBr, 1mL of di-n-butylamine, and 50g of toluene into a four-necked flask, introduce oxygen, and start mechanical stirring. The system is heated to 30°C and maintained for 20 minutes. The completely dissolved DMP toluene solution is then added to the flask, and oxygen is introduced at 30°C for 4 hours. After the reaction is complete, the reaction solution is poured into 900g of methanol for precipitation, washed three times with methanol, and dried to obtain a low-molecular-weight polyphenylene ether.

[0062] from Figure 4 It can be seen that compared with Preparation Example 1, the infrared spectrum of Example 1 shows a characteristic peak of carbon-fluorine bond at 894-970 cm-1, indicating that the fluorine element has been successfully introduced into the example.

[0063] The molecular weight, dielectric properties and other data of the low molecular weight fluorinated polyphenylene ether and low molecular weight polyphenylene ether obtained in Example 1, Example 2 and Comparative Example 1 are shown in Tables 2 and Figure 5-Figure 9 shown.

[0064] Table 2 Data of polyphenylene ether or fluorinated polyphenylene ether prepared in Example 1, Example 2 and Comparative Example 1

[0065]

[0066] From Table 2 and Figure 8-Figure 9 It can be seen that the introduction of fluorine further reduces the dielectric constant and dielectric loss factor of fluorinated polyphenylene ether. For copper clad laminate applications, such performance changes are very effective.

Claims

1. A low molecular weight fluorinated polyphenylene ether, characterized in that: It has the structural formula shown in formula (I): The structure of AR is * indicates the connection site, m>0, n>0; The molecular weight of the fluorinated polyphenylene ether is 3000-6000, and the molecular weight distribution is ≤2.

2. The low molecular weight fluorinated polyphenylene ether according to claim 1, characterized in that The dielectric constant of the fluorinated polyphenylene ether is 2.3-2.

5.

3. A method for preparing the low molecular weight fluorinated polyphenylene ether according to claim 1 or 2, characterized in that: Including steps: Step 1: catalytically polymerize 2,6-dimethylphenol and 1,1,1-tris(4-hydroxyphenyl)ethane in a solvent under an oxygen atmosphere to obtain an intermediate trihydroxypolyphenylene ether as shown in formula (II); Step 2: dissolving the trihydroxy polyphenylene ether and decafluorobiphenyl in a solvent, and reacting them in the presence of an alkaline catalyst to obtain the fluorinated polyphenylene ether.

4. The method for preparing a low molecular weight fluorinated polyphenylene ether according to claim 3, wherein: In step 1, the molar ratio of 2,6-dimethylphenol to 1,1,1-tris(4-hydroxyphenyl)ethane is 10-20:

1.

5. The method for preparing a low molecular weight fluorinated polyphenylene ether according to claim 3, wherein: In step 1, the reaction temperature is 20-40° C. and the reaction time is 2-30 h.

6. The method for preparing a low molecular weight fluorinated polyphenylene ether according to claim 3, wherein: The catalyst in step 1 comprises a combination catalyst of any one of ketone bromide, cupric bromide, cuprous iodide and any one of di-n-butylamine, n-propylamine, isopropylamine, n-butylamine, and sec-butylamine; In step 1, the molar amount of the copper salt in the catalyst is 0.1-5% of the molar amount of the reactants, and the molar amount of the amine compound is 1-4 times the molar amount of the copper salt.

7. The method for preparing a low molecular weight fluorinated polyphenylene ether according to claim 3, wherein: The solvent in step 1 includes a mixed solvent of one or more of toluene, methanol, xylene, and ethylbenzene; The product purification process in step 1 includes: precipitation of the reaction liquid in methanol after polymerization, washing, and drying to obtain the trihydroxy polyphenylene ether.

8. The method for preparing a low molecular weight fluorinated polyphenylene ether according to claim 3, wherein: In step 2, the molar ratio of trihydroxy polyphenylene ether to decafluorobiphenyl is 1:1-1.

1. In step 2, the reaction temperature is 100-140° C. and the reaction time is 10-30 h; 9. The method for preparing a low molecular weight fluorinated polyphenylene ether according to claim 3, wherein: The alkaline catalyst includes sodium carbonate and / or potassium carbonate; the molar amount of the alkaline catalyst is 1-3 times the total molar amount of the reactants.

10. The method for preparing low molecular weight fluorinated polyphenylene ether according to claim 3, characterized in that: The solvent in step 2 includes a mixed solvent of one or more of N-methylpyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide; The product purification process in step 2 includes: adding methanol to the reaction solution and filtering, precipitating the filtrate in deionized water, washing and drying to obtain the fluorinated polyphenylene ether.

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