Low-chroma polyphenyl ether

Abstract

The invention relates to low-color-change polyphenyl ether, which is prepared by the following method: adopting 2, 6-dimethylphenol as a monomer, and carrying out oxidative coupling reaction with oxygen in an organic solvent in the presence of a first catalyst, a second catalyst, a third catalyst and a fourth catalyst to obtain the low-color-change polyphenyl ether. The low-color-change polyphenyl ether is free of obvious color change and impact strength reduction under the conditions of high-temperature extrusion and long-time illumination, and can be used for manufacturing light-color products and outdoor plastic products.

Description

Technical Field

[0001] This invention relates to a low-color-change polyphenylene ether, whose color does not increase significantly during melt extrusion processing. Background Technology

[0002] Polyphenylene oxide (PPE) is a general-purpose engineering plastic. It has excellent dielectric properties, temperature resistance, and water resistance. Products made from it have high tensile strength and impact strength, and it is also self-extinguishing.

[0003] Polyphenylene ether (PPE) is typically produced by reacting xylenol with oxygen in an organic solvent using metal salts and amines as catalysts in an oxidative coupling reaction. The reaction mixture is then subjected to precipitation, filtration, washing, and drying to obtain PPE powder, as described in patents US20170275434, CN107236124A, CN104136490B, CN103154086B, and CN103421181A.

[0004] Polyphenylene oxide (PPE) is prone to discoloration during melt processing, which limits its applications, such as its difficulty in being used in light-colored plastic products. Although various solutions have been disclosed to improve the discoloration of PPE during processing, such as JP2021-082346, US4665112, and CN1174853, the effects are not ideal or the long-term effects are poor, and some even lead to a decline in mechanical properties.

[0005] Therefore, there is a need for a low-color-change polyphenylene ether to improve the color-change resistance of polyphenylene ether under high temperature and light conditions, so as to apply it to light-colored products. Summary of the Invention

[0006] During the melt processing, polyphenylene ether (PPE) undergoes a noticeable color change at high temperatures. Plastic products containing PPE also change color over time, indicating that PPE has poor antioxidant and UV resistance. Under high temperature or prolonged light exposure, it decomposes, producing colored substances that affect the performance and appearance of the products.

[0007] Therefore, the purpose of this invention is to provide a low-color-change polyphenylene ether, characterized in that the degree of color change is very low after high temperature and there is no obvious color change after long-term light exposure.

[0008] Methods for solving problems The inventors conducted in-depth research on the above problems and found that the addition of the second, third, and fourth catalysts during the preparation of polyphenylene ether can greatly improve the color change problem of the obtained polyphenylene ether.

[0009] The present invention is as follows: [1] Polymerization. 2,6-Dimethylphenol is dissolved in an organic solvent, and a first catalyst, a second catalyst, a third catalyst and a fourth catalyst are added. Oxygen is introduced under stirring conditions, and the substituted phenol undergoes an oxidative coupling reaction to polymerize and obtain a mixture containing polyphenylene ether. The first catalyst is a mixture of copper salt and amine, the second catalyst is 3,4-dihydroxyphenylethanol, the third catalyst is 2,6-di-tert-butyl-p-methylphenol, and the fourth catalyst is molybdenum salt. [2] Filtration and washing process. The mixture containing polyphenylene ether obtained by polymerization is contacted with a poor solvent to obtain a solid-liquid mixture containing polyphenylene ether particles. The solid-liquid mixture is filtered, washed with a poor solvent, and dried to obtain polyphenylene ether powder with low color change characteristics; [3] The weight-average molecular weight of the low-color-change polyphenylene ether is 20,000-60,000; [4] The low-color-change polyphenylene ether, after being melt-extruded at 300°C, has a color value of less than 40 at 420nm.

[0010] The effects of the invention 1. The low-color polyphenylene ether provided by the present invention can effectively reduce the degree of color change of polyphenylene ether resin during thermoforming.

[0011] 2. The low-color polyphenylene ether provided by this invention does not undergo significant color change under prolonged exposure to sunlight.

[0012] 3. The low color change polyphenylene ether provided by the present invention does not show a significant decrease in mechanical strength under long-term sunlight exposure. Figure 1 These are sample images of polyphenylene ether after high-temperature extrusion (A - extruded polyphenylene ether obtained in Comparative Example 1; B - extruded sample from Comparative Example 4; C - extruded polyphenylene ether sample from Example 1; D - extruded polyphenylene ether sample from Example 2). Detailed Implementation

[0013] The following is a detailed description of the method for implementing the present invention (hereinafter referred to as "this embodiment"). This embodiment is an example used to illustrate the present invention; the present invention is not limited to this embodiment, and can be implemented with appropriate modifications within the scope of its key points.

[0014] [Polyphenylene ether polymerization] The low-color polyphenylene ether of this embodiment is obtained by polymerizing 2,6-xylenol monomer in an organic solvent. The first catalyst is a copper salt-amine, the second catalyst is 3,4-dihydroxyphenylethanol, the third catalyst is 2,6-di-tert-butyl-p-methylphenol, and the fourth catalyst is a molybdenum salt. In solution, xylenol undergoes an oxidative coupling reaction with oxygen in the presence of the catalyst. After the reaction, an organic acid is used as a terminator to treat the reaction solution.

[0015] Organic solvent, 2,6-dimethylphenol, first catalyst, second catalyst, third catalyst, and fourth catalyst are added to a stirred reactor in a certain proportion. After adjusting to the set temperature, oxygen is introduced from the bottom of the reactor under stirring conditions, and polymerization occurs. The temperature of the material in the reactor is maintained within a certain range. After the reaction endpoint is reached, oxygen is stopped to terminate the reaction. A certain amount of organic acid is added, and the polymerization ends, resulting in a mixed solution containing polyphenylene ether.

[0016] Organic solvents refer to good solvents for polyphenylene ethers, including small molecule compounds containing benzene rings, such as benzene, toluene, chlorobenzene, xylene, and trimethylbenzene, with toluene, chlorobenzene, and xylene being preferred.

[0017] The copper salt in this embodiment refers to one or more of the following: copper chloride, cuprous chloride, copper bromide, copper nitrate, copper sulfate, etc.

[0018] Amines are organic compounds containing nitrogen and carbon elements, such as triethylamine, trimethylamine, tributylamine, aniline, cyclohexylamine, ethylenediamine, morpholine, p-phenylenediamine, dibutylamine, diethylamine, etc., or a mixture of one or more of them.

[0019] The second catalyst is 3,4-dihydroxyphenylethanol, which contains 0.1-3% of the monomer based on the molar amount of 2,6-dimethylphenol monomer.

[0020] The third catalyst is 2,6-di-tert-butyl-p-methylphenol, containing 0.1-3% of the monomer based on the molar amount of 2,6-dimethylphenol. The fourth catalyst is a molybdenum salt, such as molybdenum nitrate or molybdenum chloride, containing 0.1-3% of the monomer amount based on the molar amount of 2,6-dimethylphenol monomer.

[0021] The oxygen used in this embodiment is oxygen with a purity greater than 95%, preferably greater than 97%.

[0022] Organic acids used to terminate reactions are compounds containing carboxyl groups, such as acetic acid, benzoic acid, EDTA, and sodium salts of EDTA.

[0023] [Precipitation and Sedimentation] In this embodiment, the polymerized mixture containing polyphenylene ether undergoes a precipitation process upon contact with a poor solvent. The good solvent is an aromatic solvent such as xylene, chlorobenzene, or toluene; the poor solvent is an alcohol solvent such as methanol, propylene glycol, ethanol, or butanol.

[0024] [Filtering and washing] In this embodiment, the filtration and washing process of polyphenylene ether particles first uses a filtration device to filter the polyphenylene ether particles to achieve liquid-solid separation. In order to further remove the residual impurities in the particles, the polyphenylene ether filter cake needs to be washed with a poor solvent.

[0025] [dry] In this embodiment, the wet filter cake is dried under nitrogen protection to remove solvent and moisture. Example

[0026] The following specific embodiments and comparative examples illustrate this implementation method in detail, but this implementation method is not limited to the following embodiments. Example

[0027] In a 3L double-walled glass reactor, 1000g of toluene was added. The first catalyst consisted of 6g of cyclohexylamine, 2g of diethylamine, and 0.23g of copper chloride. The second catalyst was 1.2g of 3,4-dihydroxyphenylethanol. The third catalyst was 0.6g of 2,6-di-tert-butyl-p-methylphenol. The fourth catalyst was 0.1g of molybdenum nitrate. After stirring and dissolving, 200g of 2,6-dimethylphenol was added, and the material temperature was adjusted to 30℃. Under stirring conditions, oxygen (98.5% purity) was introduced from the bottom of the reactor at a rate of 300mL / min to initiate polymerization. The material temperature was controlled between 40-43℃ by the reactor jacket. After 60 minutes of polymerization, the oxygen was stopped, and the polymerization was completed. 1.6g of EDTA-2Na was added to the reactor to obtain a mixed solution of polyphenylene ether.

[0028] After mixing the mixed solution with 3000g of methanol, polyphenylene ether particles precipitated. After filtration and drying, polyphenylene ether with low color change characteristics was obtained, and the Mw was determined to be 32800 by GPC. Example

[0029] In a 3L double-walled glass reactor, 1000g of toluene was added. The first catalyst consisted of 6g of triethylamine, 2g of ethylenediamine, and 0.23g of copper chloride; the second catalyst was 1.2g of 3,4-dihydroxyphenylethanol; the third catalyst was 0.6g of 2,6-di-tert-butyl-p-methylphenol; and the fourth catalyst was 0.1g of molybdenum nitrate. After stirring and dissolving, 200g of 2,6-dimethylphenol was added, and the material temperature was adjusted to 30℃. Under stirring conditions, oxygen (98.5% purity) was introduced from the bottom of the reactor at a rate of 300mL / min to initiate polymerization. The material temperature was controlled between 40-43℃ by the reactor jacket. After 60 minutes of polymerization, the oxygen was stopped, and the polymerization was completed. 1.6g of EDTA-2Na was added to the reactor to obtain a mixed solution of polyphenylene ether.

[0030] After mixing the mixed solution with 3000g of methanol, polyphenylene ether particles were precipitated. After filtration and drying, polyphenylene ether with low color change characteristics was obtained, and the Mw was determined to be 45500 by GPC. Example

[0031] In a 3L double-walled glass reactor, 1000g of toluene was added. The first catalyst consisted of 6g of triethylamine, 2g of ethylenediamine, and 0.23g of copper chloride; the second catalyst was 0.8g of 3,4-dihydroxyphenylethanol; the third catalyst was 1.2g of 2,6-di-tert-butyl-p-methylphenol; and the fourth catalyst was 0.2g of molybdenum nitrate. After stirring and dissolving, 200g of 2,6-dimethylphenol was added, and the material temperature was adjusted to 30℃. Under stirring conditions, oxygen (98.5% purity) was introduced from the bottom of the reactor at a rate of 300mL / min to initiate polymerization. The material temperature was controlled between 40-43℃ by the reactor jacket. After 60 minutes of polymerization, the oxygen was stopped, and the polymerization was completed. 1.6g of EDTA-2Na was added to the reactor to obtain a mixed solution of polyphenylene ether.

[0032] After mixing the mixed solution with 3000g of methanol, polyphenylene ether particles precipitated. After filtration and drying, polyphenylene ether with low color change characteristics was obtained, and the Mw was determined to be 42600 by GPC.

[0033] Comparative Example 1 In a 3L double-walled glass reactor, 1000g of toluene, 6g of triethylamine, 2g of ethylenediamine, and 0.23g of copper chloride were added as the first catalyst. After stirring and dissolving, 200g of 2,6-dimethylphenol was added, and the material temperature was adjusted to 30℃. Under stirring, oxygen (98.5% purity) was introduced from the bottom of the reactor at a rate of 300mL / min to initiate polymerization. The material temperature was controlled between 40-43℃ by the reactor jacket. After 60 minutes of polymerization, the oxygen was stopped, and the polymerization was completed. 1.6g of EDTA-2Na was added to the reactor to obtain a mixed solution of polyphenylene ether.

[0034] After mixing the mixed solution with 3000g of methanol, polyphenylene ether particles were precipitated. After filtration and drying, polyphenylene ether with low color change characteristics was obtained, and the Mw was determined to be 49100 by GPC.

[0035] Comparative Example 2 In a 3L double-walled glass reactor, 1000g of toluene was added. The first catalyst consisted of 6g of triethylamine, 2g of ethylenediamine, and 0.23g of copper chloride. The second catalyst was 1.2g of 3,4-dihydroxyphenylethanol, and the third catalyst was 0.6g of 2,6-di-tert-butyl-p-methylphenol. After stirring and dissolving, 200g of 2,6-dimethylphenol was added, and the material temperature was adjusted to 30℃. Under stirring conditions, oxygen (98.5% purity) was introduced from the bottom of the reactor at a rate of 300mL / min to initiate polymerization. The material temperature was controlled between 40-43℃ by the reactor jacket. After 60 minutes of polymerization, the oxygen was stopped, and the polymerization was completed. 1.6g of EDTA-2Na was added to the reactor to obtain a mixed solution of polyphenylene ether.

[0036] After mixing the mixed solution with 3000g of methanol, polyphenylene ether particles were precipitated. After filtration and drying, polyphenylene ether with low color change characteristics was obtained, and the Mw was determined to be 44300 by GPC.

[0037] Comparative Example 3 In a 3L double-walled glass reactor, 1000g of toluene was added. The first catalyst consisted of 6g of triethylamine, 2g of ethylenediamine, and 0.23g of copper chloride. The second catalyst was 1.2g of 3,4-dihydroxyphenylethanol, and the fourth catalyst was 0.1g of molybdenum nitrate. After stirring and dissolving, 200g of 2,6-dimethylphenol was added, and the material temperature was adjusted to 30℃. Under stirring conditions, oxygen (98.5% purity) was introduced from the bottom of the reactor at a rate of 300mL / min to initiate polymerization. The material temperature was controlled between 40-43℃ by the reactor jacket. After 60 minutes of polymerization, the oxygen was stopped, and the polymerization was completed. 1.6g of EDTA-2Na was added to the reactor to obtain a mixed solution of polyphenylene ether.

[0038] After mixing the mixed solution with 3000g of methanol, polyphenylene ether particles precipitated. After filtration and drying, polyphenylene ether with low color change characteristics was obtained, and the Mw was determined to be 46600 by GPC.

[0039] Comparative Example 4 In a 3L double-walled glass reactor, 1000g of toluene was added. The first catalyst consisted of 6g of triethylamine, 2g of ethylenediamine, and 0.23g of copper chloride. The third catalyst was 0.6g of 2,6-di-tert-butyl-p-methylphenol, and the fourth catalyst was 0.1g of molybdenum nitrate. After stirring and dissolving, 200g of 2,6-dimethylphenol was added, and the material temperature was adjusted to 30℃. Under stirring conditions, oxygen (98.5% purity) was introduced from the bottom of the reactor at a rate of 300mL / min to initiate polymerization. The material temperature was controlled between 40-43℃ by the reactor jacket. After 60 minutes of polymerization, the oxygen was stopped, and the polymerization was completed. 1.6g of EDTA-2Na was added to the reactor to obtain a mixed solution of polyphenylene ether.

[0040] After mixing the mixed solution with 3000g of methanol, polyphenylene ether particles were precipitated. After filtration and drying, polyphenylene ether with low color change characteristics was obtained, and the Mw was determined to be 45300 by GPC.

[0041] Comparative Example 5 200g of polyphenylene ether (Zhongmu Chemical, 040, Mw is 44600) was mixed with 0.2g of benzoin and then melt-extruded.

[0042] The obtained polyphenylene ether was extruded at 300°C with a residence time of about 10 minutes, and the color of the extruded filament was examined.

[0043] Colorimetric value test method: Dissolve 0.2g of the sample to be tested in 25ml of chloroform, and test the absorbance of the solution at 420nm. The sample cell size is 1cm. Colorimetric value = absorbance value × 100.

[0044] Simulated sunlight exposure: An LED sunlight simulator was used, with an irradiance of 700W / m². 2 , 50cm away from the spline.

[0045] Notched impact strength indicates the toughness of a material. The sample is hot-pressed into a test strip at 300 degrees Celsius using a flat vulcanizing machine. The test standard is ASTM D256.

[0046] Table 1 shows the changes in color and impact strength of polyphenylene ether prepared in the examples and comparative examples after high-temperature extrusion and after 300 hours of simulated sunlight exposure. Figure 1 shows the extruded samples after high-temperature extrusion (A - extruded polyphenylene ether obtained in Comparative Example 1; B - extruded sample from Comparative Example 4; C - extruded polyphenylene ether sample from Example 1; D - extruded polyphenylene ether sample from Example 2). The test results are shown in Table 1. The low-color-change polyphenylene ethers obtained in Examples 1, 2, and 3 showed no significant change in color after hot extrusion and prolonged simulated sunlight exposure, and their impact strength did not increase significantly. Comparative Examples 1, 2, 3, and 4 all showed significant color change after hot extrusion and 300 hours of simulated sunlight exposure, and their impact strength decreased significantly. In Comparative Example 5, the addition of benzoin improved the color change to some extent, but the effect was not significant, and the impact strength also decreased considerably after 300 hours of simulated sunlight exposure.

[0047] It should be understood that this embodiment is for illustrative purposes only and is not intended to limit the scope of the invention. Furthermore, it should be understood that after reading this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms are also within the scope defined by the appended claims.

[0048]

Claims

1. A low-color-change polyphenylene ether, characterized in that, The low-color-change polyphenylene ether is prepared by reacting 2,6-dimethylphenol with oxygen in an organic solvent in the presence of a first catalyst, a second catalyst, a third catalyst, and a fourth catalyst. The first catalyst is a copper salt and an organic amine compound; the second catalyst is 3,4-dihydroxyphenylethanol, containing 0.1-3% of the monomer by molar amount; the third catalyst is 2,6-di-tert-butyl-p-methylphenol; and the fourth catalyst is a molybdenum salt.

2. The low-color-change polyphenylene ether according to claim 1, characterized in that, The weight-average molecular weight of the polyphenylene ether is 20,000-60,000.

3. The low-color-change polyphenylene ether according to claim 1, characterized in that, The low-color-change polyphenylene ether, after being extruded at 300°C, has a color value of less than 40 at 420 nm.

4. The second catalyst according to claim 1, characterized in that, The second catalyst contains 0.1-3% of the monomer by mole.

5. The third catalyst according to claim 1, characterized in that, The third catalyst contains 0.1-3% of the monomer by mole number.

6. The fourth catalyst according to claim 1, characterized in that, The fourth catalyst is a molybdenum salt such as molybdenum nitrate or molybdenum chloride, and contains 0.1-3% of the monomer by mole number.

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