A low molecular weight polyphenylene ether and its preparation method

Abstract

The present invention relates to the field of polyphenylene ether preparation, and discloses a low-molecular-weight polyphenylene ether and a preparation method thereof. The preparation method of the low-molecular-weight polyphenylene ether comprises the following steps: loading an inorganic carrier-loaded metal ion-amine complex catalyst into a fixed-bed reactor, mixing 2,6-dimethylphenol and dihydric phenol in methanol in a certain proportion, and then mixing the mixture with oxygen through a mixer into the fixed-bed reactor for reaction, preferably at a reaction temperature of 30°C to 60°C and a space velocity of 0.1-1h / min. ‑1 Compared with the prior art, the preparation method of low molecular weight polyphenylene ether provided by the present invention can obtain low molecular weight polyphenylene ether with less copper content or no copper, thereby improving the processing performance and dielectric properties of polyphenylene ether; compared with the purification steps of repeated dissolution and reprecipitation in traditional synthesis methods, it is simplified, saving resources and protecting the environment.

Description

Technical Field

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

[0002] Polyphenylene ether is a type of engineering plastic with excellent performance. The polymer manufactured by oxidative coupling using 2,6-dimethylphenol as raw material is a representative one among them. The outstanding properties of polyphenylene ether include light specific gravity, with some polymers having a specific gravity of only 1.07g / cm3; excellent temperature resistance, and can operate for a long time between 120℃-170℃; good hydrolysis resistance, and the performance does not decrease in strong acids and alkalis; excellent insulation properties, and can maintain a constant dielectric constant when operating at high frequency voltage for a long time. Therefore, it is widely used in the fields of automobiles, electronic appliances, water treatment, cables and wires, PCB printed circuit boards, etc.

[0003] In recent years, with the rapid development of the information age, especially the advent of the 5G era, the transmission of high-throughput data has put forward higher requirements on the dielectric properties of electronic and electrical materials. The low dielectric constant and low dielectric loss performance of polyphenylene ether make it one of the ideal high-frequency and high-speed PCB substrates. However, the conventional molecular weight polyphenylene ether (intrinsic viscosity IV ≥ 0.25dL / g) used in the thermoplastic field has poor compatibility with thermosetting resins (such as epoxy resins and cyanate resins, etc.), which limits its application in the field of electronic and electrical appliances. In addition, since conventional molecular weight polyphenylene ether has a higher melt viscosity, it has poor processing performance during extrusion granulation and / or injection molding. In order to overcome the above-mentioned defects of conventional molecular weight polyphenylene ether in the application of electronic and electrical appliances, low molecular weight polyphenylene ether with double-terminal hydroxyl groups is considered to be one of the ideal materials. On the basis of inheriting the low dielectric constant and low dielectric loss performance of conventional molecular weight polyphenylene ether, due to the increase of double-terminal hydroxyl content, it can be used in the field of thermosetting type, overcoming the disadvantage of poor compatibility of conventional molecular weight polyphenylene ether with thermosetting resins, greatly improving processing and forming properties.

[0004] A related patent discloses a system and method for preparing dihydroxy polyphenylene ether (application number CN114605629A). The system comprises a first reactor consisting of a static mixing reactor and a second reactor consisting of a pressure-resistant reactor, which are interconnected. The preparation method comprises a reactor constant temperature step, a feeding step, a circulating reaction step, and a separation and purification step. CN107353401A also reports a method for preparing polyphenylene ether, which uses monomers prepared from monophenol, toluene, and carbonyl compounds and is obtained by oxidative polymerization under the catalysis of metal salts. However, CN107353401A and CN114605629A still have unsatisfactory control over molecular weight, and after the reaction is completed, the residual amount of copper ions in the catalyst is large, which increases the difficulty of post-processing.

[0005] Therefore, the purpose of this application is to provide a low molecular weight polyphenylene ether and a preparation method thereof to solve the above problems. Summary of the Invention

[0006] In order to overcome the above technical problems, the purpose of the present invention is to provide a low molecular weight polyphenylene ether and a preparation method thereof. Compared with the prior art, the present invention has a simple process, mild reaction conditions, easy molecular weight control, simple product post-processing, high production efficiency, and can meet the industrial production requirements of low molecular weight bishydroxy polyphenylene ether. The present invention effectively solves the problems of the prior art that pure oxygen is used as a coupling agent and is prone to flash explosion and the catalyst is difficult to separate, resulting in high environmental pressure in post-processing, as well as the problems of the prior art that the molecular weight is large and the distribution is wide. The purpose of the present invention can be achieved by the following technical solutions:

[0007] The present invention achieves the above-mentioned object through the following technical scheme, which is a method for preparing low-molecular-weight polyphenylene ether, comprising the following steps: after loading an inorganic carrier-loaded metal ion-amine complex catalyst into a fixed-bed reactor, mixing 2,6-dimethylphenol and dihydric phenol in methanol in a certain proportion, and then entering the fixed-bed reactor with oxygen through a mixer for reaction.

[0008] The above-mentioned method for preparing the double-terminated hydroxyl low molecular weight polyphenylene ether is a further feasible solution, wherein the monomers used include dihydric phenol (1) and 2,6-dimethylphenol (2), which are polymerized in the presence of a catalyst via the reaction of formula (3).

[0009]

[0010] Here, R and r are hydrogen atoms or methyl groups, and R1 to R3 and r1 to r3 are the same or different.

[0011] The above-mentioned method for preparing low molecular weight polyphenylene ether, as a further feasible scheme, uses a supported catalyst of a metal ion and an amine complex supported on an inorganic carrier, wherein the carrier in the inorganic carrier is at least one of silica, montmorillonite, and activated carbon; the metal ion is a copper ion, which is at least one of copper chloride, copper bromide, copper sulfate, and copper nitrate; and the amine is ethyleneamine, including at least one of triethylenetetramine, diethylenetriamine, and tetraethylenepentamine.

[0012] As a further feasible solution, the method for preparing the low molecular weight polyphenylene ether adopts a fixed bed reactor with a removal pipe provided inside and circulating water introduced therein for temperature control.

[0013] In a further feasible solution, the method for preparing the low molecular weight polyphenylene ether has a reaction temperature of 30 to 60°C.

[0014] The above-mentioned preparation method of low molecular weight polyphenylene ether, as a further feasible scheme, has a reaction space velocity of 0.1-1h -1 .

[0015] In the above-mentioned method for preparing low molecular weight polyphenylene ether, as a further feasible solution, the reaction solvent is methanol.

[0016] In summary, this application has the following beneficial technical effects:

[0017] The present invention features a simple process, mild reaction conditions, easy molecular weight control, simple product post-processing, and high production efficiency, meeting the requirements for industrialized production of low-molecular-weight bishydroxy polyphenylene ether. The present invention effectively addresses the prior art issues of using pure oxygen as a coupling agent, which is prone to flash explosions and difficult to separate the catalyst, resulting in significant environmental pressures for post-processing, as well as the high molecular weight and wide molecular weight distribution found in the prior art. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. 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.

[0019] Example 1

[0020] In a 500ml three-necked flask, add 300ml of methanol, 30.0g of silica, and 5.5g of triethylenetetramine, heat to 50°C, stir for 2 hours, then slowly add 20.0g of copper chloride aqueous solution (containing 5.0g of copper chloride) under stirring. After the addition is complete, heat to reflux, stir and react for 5 hours, evaporate the solvent, and then heat at 150°C under nitrogen protection for 3 hours to obtain catalyst A.

[0021] Example 2

[0022] 10.0 g of catalyst A was loaded into a fixed bed reactor, and the fixed bed was heated to 50° C. A pre-prepared mixed solution (containing 100.0 g of 2,6-dimethylphenol, 5.0 g of biphenyl diphenol, and 3000.0 g of methanol) was preheated to 50° C. and then pumped into the fixed bed at a flow rate of 0.1 ml / min. At the same time, oxygen was introduced at a gas rate of 5 ml / min. The methanol in the collected reaction solution was distilled off until powder precipitated. Hydrogen chloride was introduced until a large amount of solid matter precipitated. The mixture was filtered, washed with a methanol-water mixed solution, and dried to obtain a dihydroxy-terminated low molecular weight polyphenylene ether (molecular weight 2900).

[0023] Example 3

[0024] In a 500ml three-necked flask, add 300ml of methanol, 30.0g of silica, and 5.5g of triethylenetetramine, raise the temperature to 50°C, and stir for 2 hours. Then, slowly add 30.0g of copper bromide aqueous solution (containing 8.3g of copper bromide) under stirring. After the addition is complete, raise the temperature to reflux, stir and react for 5 hours, evaporate the solvent, and then heat at 150°C for 3 hours under nitrogen protection to obtain catalyst B.

[0025] Example 4

[0026] 10.0 g of catalyst B was loaded into a fixed bed reactor, and the fixed bed was heated to 50° C. A pre-prepared mixed solution (containing 100.0 g of 2,6-dimethylphenol, 5.0 g of biphenyl diphenol, and 3000.0 g of methanol) was preheated to 50° C. and then pumped into the fixed bed at a flow rate of 0.1 ml / min. At the same time, oxygen was introduced at a gas rate of 5 ml / min. The methanol in the collected reaction solution was distilled off until powder precipitated. Hydrogen chloride was introduced until a large amount of solid matter precipitated. The mixture was filtered, washed with a methanol-water mixed solution, and dried to obtain a dihydroxy-terminated low molecular weight polyphenylene ether (molecular weight 3500).

[0027] Example 5

[0028] 10.0 g of catalyst A was loaded into a fixed bed reactor, and the fixed bed was heated to 60° C. A pre-prepared mixed solution (containing 100.0 g of 2,6-dimethylphenol, 5.0 g of biphenyl diphenol, and 3000.0 g of methanol) was preheated to 60° C. and then pumped into the fixed bed at a flow rate of 0.1 ml / min. At the same time, oxygen was introduced at a gas rate of 5 ml / min. The methanol in the collected reaction solution was distilled off until powder precipitated. Hydrogen chloride was introduced until a large amount of solid matter precipitated. The mixture was filtered, washed with a methanol-water mixed solution, and dried to obtain a dihydroxy-terminated low molecular weight polyphenylene ether (molecular weight 4200).

[0029] Example 6

[0030] 10.0 g of catalyst A was loaded into a fixed bed reactor, and the fixed bed was heated to 50° C. A pre-prepared mixed solution (containing 100.0 g of 2,6-dimethylphenol, 5.0 g of biphenyl diphenol, and 3000.0 g of methanol) was preheated to 50° C. and then pumped into the fixed bed at a flow rate of 0.15 ml / min. At the same time, oxygen was introduced at a gas rate of 5 ml / min. The methanol in the collected reaction solution was distilled off until powder precipitated. Hydrogen chloride was introduced until a large amount of solid matter precipitated. The mixture was filtered, washed with a methanol-water mixed solution, and dried to obtain a dihydroxy-terminated low molecular weight polyphenylene ether (molecular weight 2100).

[0031] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing low molecular weight polyphenylene ether, characterized in that: The number average molecular weight of the low molecular weight polyphenylene ether is 1000 to 5000; the low molecular weight polyphenylene ether is polymerized by the dihydric phenol monomer of formula (1) and the 2,6-dimethylphenol monomer of formula (2) under the action of a catalyst through the reaction of formula (3); Formula (1) Formula (2) Formula (3) Wherein, R and r are hydrogen atoms, methyl groups, R1 to R3 and r1 to r3 are the same or different; The specific steps are as follows: after loading an inorganic carrier-loaded metal ion-amine complex catalyst into a fixed bed reactor, 2,6-dimethylphenol and diphenol are mixed in methanol in a certain proportion, and then enter the fixed bed reactor through a mixer with oxygen for reaction.

2. The method for preparing a low molecular weight polyphenylene ether according to claim 1, wherein: The catalyst is a supported catalyst, which is a complex of metal ions and amines supported on a grafted inorganic carrier.

3. The method for preparing a low molecular weight polyphenylene ether according to claim 2, wherein: The carrier in the grafted inorganic carrier is at least one of silicon dioxide, montmorillonite and activated carbon.

4. The method for preparing a low molecular weight polyphenylene ether according to claim 2, wherein: The metal ions are copper ions, which are at least one of copper chloride, copper bromide, copper sulfate and copper nitrate.

5. The method for preparing a low molecular weight polyphenylene ether according to claim 2, wherein: The amine is derived from ethyleneamine, including at least one of triethylenetetramine, diethylenetriamine and tetraethylenepentamine.

6. The method for preparing a low molecular weight polyphenylene ether according to claim 1, characterized in that: When preparing polyphenylene ether, a fixed bed reactor is used, in which a removal pipe is provided inside and circulating water is introduced to control the temperature.

7. The method for preparing a low molecular weight polyphenylene ether according to claim 1, characterized in that: The reaction temperature is 30-60°C.

8. The method for preparing a low molecular weight polyphenylene ether according to claim 1, characterized in that: Reaction space velocity is 0.1-1h -1 .

9. The method for preparing a low molecular weight polyphenylene ether according to claim 1, characterized in that: The reaction solvent is methanol.

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