A method for synthesizing a 2,4-dimethylphenol / 2,5-dimethylphenol novolac resin

Abstract

This invention belongs to the technical field of organic synthesis and separation, specifically relating to a method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol. The method provided by this invention utilizes the difference in reactivity between 2,5-xylenol, 2,4-xylenol, and aldehydes, using a portion of the inexpensive 2,4 / 2,5-xylenol to replace phenol in the production of phenolic resin. Simultaneously, it produces 99% 2,4-xylenol and p-cresol, etc. Since the prices of 2,4-xylenol and p-cresol are significantly higher than those of 2,4 / 2,5-xylenol, this method also offers good economic benefits and expands the application scope and market size of 2,4 / 2,5-xylenol.

Description

Technical Field

[0001] This invention belongs to the technical field of organic synthesis and separation, specifically relating to a method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol. Background Technology

[0002] Using raw materials such as coking crude phenol, medium- and low-temperature gasification crude phenol, and medium- and low-temperature pyrolysis coal tar extracted crude phenol, general distillation can yield products such as phenol (containing 99.5% superior grade, 99% first grade, 98% qualified grade, and 80% industrial phenol), mixed phenols (a mixture of phenol and o-cresol with a phenol content greater than 50%), o-cresol fraction (mainly a mixture of phenol and o-cresol), o-cresol, o-cresol / 2,6-cresol, m- and p-cresol, mixed xylenols (including industrial xylenol), and mixed tricresols. Further distillation of mixed xylenol yields cresol transition fractions (blended with 35% cresol), 2,4 / 2,5-xylenol, 2,3-xylenol / m-p-isopropylphenol / 3,5-xylenol, industrial xylenol, crude 2,4,6-trimethylphenol or 2,4 / 2,5-methylethylphenol, 3,4-xylenol / 2,3,6-trimethylphenol, etc.; 2,4 / 2,5-xylenol can also be derived from byproducts of m-p-cresol produced by the toluene sulfonation alkaline fusion method, m-p-cresol catalytic methylation reaction, etc.

[0004] Phenolic resin is a synthetic resin formed by the condensation polymerization of phenol and formaldehyde under the action of a catalyst. Due to its excellent high-temperature resistance, chemical resistance, and bonding strength, it has wide applications in refractory materials, friction materials, and packaging materials. However, the high price of raw material phenol keeps production costs high. Therefore, how to prepare phenolic resin using 2,4 / 2,5-xylenol has attracted increasing attention from those skilled in the art. Summary of the Invention

[0005] The present invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of the present invention provide a method for synthesizing phenolic resins from 2,4-xylenol / 2,5-xylenol.

[0006] The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol provided in this embodiment of the invention includes the following components:

[0007] (1) Add a portion of 2,4 / 2,5-xylenol, a portion of aldehydes and the first catalyst to the polymerization reactor, start stirring, heat to 60-105℃ and react for 0-6 hours, add the remaining aldehydes and the remaining 2,4 / 2,5-xylenol dropwise at 60-105℃ for 1-4 hours, and keep warm for 1-6 hours after addition and take a sample for analysis. The 2,5-xylenol content is ≤5% and qualified. (2) Control the temperature in the polymerization reactor to 60-80℃, perform vacuum dehydration, dehydration temperature is 80-85℃, dehydration time is 2-5 hours, final pressure is -0.075--0.08Mpa, and observe the water level in the receiver at the same time, specifically based on the water level being constant within 20 minutes; (3) Increase the vacuum in the polymerization reactor to -0.09 to -0.1 MPa within 1 to 2 hours, and at the same time further heat and dehydrate. When the temperature of the material in the reactor reaches 100 to 230°C and no liquid distills out, the dehydration time is 2 to 6 hours. Keep warm for 0.5 to 1 hour, stop dehydration, use nitrogen to release the vacuum, and discharge the material while it is hot under nitrogen protection. After cooling, phenolic resin is obtained.

[0008] The advantages and technical effects of the method for synthesizing phenolic resin using 2,4-xylenol / 2,5-xylenol in this invention are as follows: 1. The method of this invention utilizes the difference in reactivity between 2,5-xylenol and 2,4-xylenol with formaldehyde, using a portion of the inexpensive 2,4 / 2,5-xylenol to replace phenol in the production of phenolic resin. Simultaneously, it produces 99% 2,4-xylenol and p-cresol, etc. The prices of 2,4-xylenol and p-cresol are significantly higher than those of 2,4 / 2,5-xylenol, resulting in better economic benefits and expanding the application scope and market size of 2,4 / 2,5-xylenol. 2. The method of this invention, using 2,4 / 2,5-xylenol to replace phenol in the production of phenolic resin, can effectively solve the market problem of 2,4 / 2,5-xylenol generated from the refining of 100,000 to 200,000 tons of crude phenol produced in newly built coal gasification, coal pyrolysis, and coal liquefaction industries. This can contribute to the healthy and orderly development of the coal gasification, coal liquefaction, and coal pyrolysis industries.

[0009] In some embodiments, in step (1), a first phenolic component is added to the polymerization reactor. The first phenolic component includes at least one of m-cresol, m-ethylphenol, m-isopropylphenol, m-propylphenol, 3,5-xylenol, phenol, or 3-ethyl-5-cresol. The amount of the first phenolic component added is 0.1 to 200 wt% of 2,4 / 2,5-xylenol. And / or, in step (1), a portion of the 2,4 / 2,5-xylenol is 0 to 100 wt% of the total amount of 2,4 / 2,5-xylenol, and a portion of the aldehyde is 0 to 100 wt% of the aldehyde. When the portion of the aldehyde is 0 wt%, the reaction time at 60 to 105°C is 0. When the portion of the aldehyde is not 0 wt%, the reaction time at 60 to 105°C is not 0.

[0010] In some embodiments, in step (1), the 2,4 / 2,5-xylenol is obtained by distillation of crude phenol extracted from coal coking crude phenol, medium-low temperature coal gasification crude phenol, or phenol-containing coal tar extracted by coal pyrolysis; the 2,4 / 2,5-xylenol comprises 0-15 wt% m-p-cresol, 0-2 wt% o-ethylphenol, 70-100 wt% 2,4 / 2,5-xylenol, 0-10 wt% 2-ethyl-6-cresol, 0-5 wt% o-isopropylphenol, and 0-30 wt% 2,3-xylenol; And / or, in step (1), the aldehyde includes at least one of paraformaldehyde, formaldehyde or acetaldehyde, and the amount of the aldehyde is 1 to 2.5 times the total molar amount of phenol, m-cresol, 3,5-dimethylphenol, 2,3-dimethylphenol, 2,5-dimethylphenol, m-ethylphenol, m-isopropylphenol, m-propylphenol, and 3-ethyl-5-cresol.

[0011] In some embodiments, in step (1), the first catalyst includes at least one of oxalic acid, formic acid, phosphoric acid, hydrochloric acid, aminosulfonic acid, benzenesulfonic acid, ammonia or organic base; the amount of the first catalyst is 0.1 to 10 wt% of the total amount of phenolic raw materials.

[0012] In some embodiments, in step (1), the first catalyst includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, barium hydroxide, ammonia, or an organic base, and the amount of the first catalyst is 0.1 to 10 wt% of the total amount of phenolic raw materials. Step (2) involves adding glacial acetic acid or formic acid to neutralize the pH to 6-7 after the reaction is complete, gradually increasing the vacuum to -0.07 to -0.1 MPa over 0.5-1 hours to begin dehydration. When the dehydration rate slows down or the temperature drops to around 70-75°C, heating is used to continue dehydration, controlling the final liquid temperature at 70-90°C until the water level reaches the required value. A sample is then taken for analysis to determine the moisture content of the material to be ≤5%. Step (3) involves adding ethylene glycol to the polymerization reactor, stirring it evenly, taking samples to analyze the moisture and viscosity, stopping the vacuuming when the moisture content is 2-5%, and adding ethanol to adjust the viscosity to 10-30 Pa·s according to the requirements of different products. After the viscosity reaches the required level, the temperature is lowered to 50°C and the material is discharged. The amount of ethylene glycol used is 1-10% of the total mass of the phenolic raw materials.

[0013] In some embodiments, the method further includes step (4), adding a second catalyst to the distilled material, heating to 80-105°C and reacting for 1-3 hours, taking a sample for analysis and finding that 2,5-xylenol is ≤0.5%, adding a non-water-soluble solvent, stirring for 0.5-2 hours, letting stand for 0.5-1 hours, separating the layers, heating the lower water layer to 95-105°C to remove a small amount of solvent, and then cooling to 40-50°C to send it to the wastewater treatment section for treatment, and the upper oil layer being a solution containing unreacted 2,4-xylenol.

[0014] In some embodiments, the second catalyst is an acidic catalyst or an alkaline catalyst. The acidic catalyst includes at least one of oxalic acid, formic acid, phosphoric acid, or hydrochloric acid, and the alkaline catalyst includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, or ammonia water. The amount of the second catalyst is 0.01 to 0.5 wt% of the total amount of phenolic raw materials.

[0015] In some embodiments, the non-water-soluble solvent includes at least one of aromatic hydrocarbons, chloroalkanes, ethers, ketones, or esters; the mass of the non-water-soluble solvent is 0.5 to 2 times that of the phenolic material.

[0016] In some embodiments, the method further includes step (5), in which the oil layer is added to a distillation vessel with 5 to 30 trays, the temperature is raised first to atmospheric pressure and then to vacuum distillation to remove the solvent, and then the material in the distillation vessel is transferred to a high-efficiency distillation vessel with 50 to 250 trays to obtain 99% 2,4-xylenol or 2,4 / 2-ethyl-6-xylenol, and the residue in the vessel and 2,4 / 2,5-xylenol are fed into the polymerization reactor for recycling.

[0017] In some embodiments, the pressure of the vacuum distillation is -0.03 to -0.07 MPa, and the reflux ratio is (1 to 5):1; The distillation pressure is -0.07 to -0.1 MPa, and the reflux ratio is (5 to 25):1. Detailed Implementation

[0018] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol provided in this embodiment of the invention includes the following components: (1) Add a portion of 2,4 / 2,5-xylenol, a portion of aldehydes and the first catalyst to the polymerization reactor, start stirring, heat to 60-105℃ and react for 0-6 hours, add the remaining aldehydes and the remaining 2,4 / 2,5-xylenol dropwise at 60-105℃ for 1-4 hours, and keep warm for 1-6 hours after addition and take a sample for analysis. The 2,5-xylenol content is ≤5% and qualified. (2) Control the temperature in the polymerization reactor to 60-80℃, perform vacuum dehydration, dehydration temperature is 80-85℃, dehydration time is 2-5 hours, final pressure is -0.075--0.08Mpa, and observe the water level in the receiver at the same time, specifically based on the water level being constant within 20 minutes; (3) Increase the vacuum in the polymerization reactor to -0.09 to -0.1 MPa within 1 to 2 hours, and at the same time further heat and dehydrate. When the temperature of the material in the reactor reaches 100 to 230°C and no liquid distills out, the dehydration time is 2 to 6 hours. Keep warm for 0.5 to 1 hour, stop dehydration, use nitrogen to release the vacuum, and discharge the material while it is hot under nitrogen protection. After cooling, phenolic resin is obtained.

[0020] The method for synthesizing phenolic resin using 2,4-xylenol / 2,5-xylenol according to embodiments of the present invention offers advantages and technical effects. (1) Taking advantage of the difference in reactivity between 2,5-xylenol and 2,4-xylenol with formaldehyde, phenolic resin is produced by replacing phenol with some of the cheaper 2,4 / 2,5-xylenol. At the same time, 99% 2,4-xylenol and p-cresol are produced. The prices of 2,4-xylenol and p-cresol are significantly higher than those of 2,4 / 2,5-xylenol, which has better economic benefits. At the same time, it expands the application scope and market size of 2,4 / 2,5-xylenol. (2) Using 2,4 / 2,5-dimethylphenol to replace phenol in the production of phenolic resin can effectively solve the market problem of 2,4 / 2,5-dimethylphenol produced by the refining of 100,000 to 200,000 tons of crude phenol generated in newly built coal gasification, coal pyrolysis and coal liquefaction industries, and can contribute to the healthy and orderly development of coal gasification, coal liquefaction and coal pyrolysis industries.

[0021] In some embodiments, preferably, in step (1), a first phenolic component is added to the polymerization reactor. The first phenolic component includes at least one of m-cresol, m-ethylphenol, m-isopropylphenol, m-propylphenol, 3,5-xylenol, phenol, or 3-ethyl-5-cresol. The amount of the first phenolic component added is 0.1 to 200 wt% of 2,4 / 2,5-xylenol, for example, 0.1 wt%, 5 wt%, 10 wt%, 20 wt%, 40 wt%, 60 wt%, 80 wt%, 100 wt%, 120 wt%, 140 wt%, 160 wt%, 180 wt%, or 200 wt%. More preferably, the first phenolic component is coal-derived phenol. The functionality of the first phenolic component reacting with formaldehyde is 3.

[0022] The method of this invention involves adding highly reactive 3,5-xylenol, m-cresol, m-ethylphenol, m-isopropylphenol, and phenol as the first phenolic component. This component first reacts with a portion of formaldehyde to generate a prepolymer with an average functionality of not less than 2. Then, the remaining formaldehyde and 2,4 / 2,5-xylenol are added dropwise for further reaction. This prepolymer can then react with 2,4-xylenol to obtain another prepolymer with a functionality of not less than 2. The prepolymer can then continue to react with 2,5-xylenol to generate a product with high performance... Superior to ordinary phenolic resin (phenol as raw material); the small amount of 6-hydroxymethyl-2,4-dimethylphenol generated by the reaction of 2,4-xylenol and formaldehyde can easily react with 3,5-xylenol, m-cresol, m-ethylphenol, m-isopropylphenol, and phenol to generate an intermediate with a functionality of not less than 2. The intermediate can then react with 2,5-xylenol, 3,5-xylenol, m-cresol, m-ethylphenol, m-isopropylphenol, and phenol to obtain a phenolic resin with properties that meet the customer's requirements.

[0023] In some embodiments, preferably, in step (1), a portion of the 2,4 / 2,5-xylenol is 0-100 wt% of the total 2,4 / 2,5-xylenol, and a portion of the aldehyde is 0-100 wt% of the aldehyde. When the aldehyde portion is 0 wt%, the reaction time at 60-105°C is 0; when the aldehyde portion is not 0 wt%, the reaction time at 60-105°C is not 0. More preferably, a portion of the 2,4 / 2,5-xylenol is 30-100 wt% of the total 2,4 / 2,5-xylenol.

[0024] In some embodiments, preferably, in step (1), the 2,4 / 2,5-xylenol is obtained by distillation of crude phenol extracted from coal coking, crude phenol extracted from medium- and low-temperature coal gasification, or crude phenol extracted from phenol-containing coal tar by coal pyrolysis; the 2,4 / 2,5-xylenol comprises 0-15 wt% m-p-cresol, 0-2 wt% o-ethylphenol, 70-100 wt% 2,4 / 2,5-xylenol, 0-10 wt% 2-ethyl-6-cresol, 0-5 wt% o-isopropylphenol, and 0-30 wt% 2,3-xylenol. More preferably, the 2,4 / 2,5-xylenol is obtained by distillation of crude phenol extracted from medium- and low-temperature coal gasification or crude phenol extracted from phenol-containing coal tar by coal pyrolysis.

[0025] In some embodiments, preferably, in step (1), the aldehyde includes at least one of paraformaldehyde, formaldehyde, or acetaldehyde, and the amount of the aldehyde is 1 to 2.5 times the total molar amount of phenol, m-cresol, 3,5-xylenol, 2,3-xylenol, 2,5-xylenol, m-ethylphenol, m-isopropylphenol, m-propylphenol, and 3-ethyl-5-cresol. More preferably, the aldehyde is formaldehyde, and the amount of the aldehyde is 1.4 to 2.0 times the total molar amount of phenol, m-cresol, 3,5-xylenol, 2,3-xylenol, 2,5-xylenol, m-ethylphenol, m-isopropylphenol, m-propylphenol, and 3-ethyl-5-cresol.

[0026] In some embodiments, preferably, in step (1), the first catalyst includes at least one of oxalic acid, formic acid, phosphoric acid, hydrochloric acid, aminosulfonic acid, benzenesulfonic acid, ammonia, or organic base; the amount of the first catalyst is 0.1 to 10 wt% of the total amount of phenolic raw materials. More preferably, the first catalyst is at least one of oxalic acid or phosphoric acid.

[0027] In some embodiments, preferably, in step (1), the first catalyst includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, barium hydroxide, ammonia, or an organic base, and the amount of the first catalyst is 0.1 to 10 wt% of the total amount of phenolic raw materials; more preferably, the first catalyst is at least one of sodium hydroxide or ammonia. Step (2) involves adding glacial acetic acid or formic acid to neutralize the pH to 6-7 after the reaction is complete, gradually increasing the vacuum to -0.07 to -0.1 MPa over 0.5-1 hours to begin dehydration. When the dehydration rate slows down or the temperature drops to around 70-75°C, heating is used to continue dehydration, controlling the final liquid temperature at 70-90°C until the water level reaches the required value. A sample is then taken for analysis to determine the moisture content of the material to be ≤5%. Step (3) involves adding ethylene glycol to the polymerization reactor, stirring it evenly, taking samples to analyze the moisture and viscosity, stopping the vacuuming when the moisture content is 2-5%, and adding ethanol to adjust the viscosity to 10-30 Pa·s according to the requirements of different products. After the viscosity reaches the required level, the temperature is lowered to 50°C and the material is discharged. The amount of ethylene glycol used is 1-10% of the total mass of the phenolic raw materials.

[0028] In some embodiments, preferably, the process further includes step (4): adding a second catalyst to the distilled material, heating to 80-105°C and reacting for 1-3 hours, taking a sample for analysis to find that 2,5-xylenol is ≤0.5%, adding a non-water-soluble solvent, stirring for 0.5-2 hours, letting stand for 0.5-1 hours, separating the layers, heating the lower water layer to 95-105°C to remove a small amount of solvent, and then cooling to 40-50°C to send it to the wastewater treatment section for treatment, while the upper oil layer is a solution containing unreacted 2,4-xylenol.

[0029] This invention addresses the issue that the materials distilled during polymerization may contain small amounts of 2,5-xylenol, 2,3-xylenol, and formaldehyde. To ensure the quality of the 2,4-xylenol product, a second catalyst is added to the distilled materials for prepolymerization of phenolic materials. This allows unreacted free 2,5-xylenol to further react with the distilled formaldehyde to generate a prepolymer, thus removing excess formaldehyde and 2,5-xylenol. This facilitates the extraction of 99% high-quality 2,4-xylenol and other products, and also benefits the treatment of phenol-containing wastewater. The prepolymer is returned to the polymerization system, increasing resin production and reducing solid waste.

[0030] In some embodiments, preferably, the second catalyst is an acidic catalyst or a basic catalyst, wherein the acidic catalyst includes at least one of oxalic acid, formic acid, phosphoric acid, or hydrochloric acid, and the basic catalyst includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, or ammonia water; the amount of the second catalyst is 0.01 to 0.5 wt% of the total amount of the phenolic raw material. More preferably, the second catalyst includes at least one of hydrochloric acid or oxalic acid.

[0031] In some embodiments, preferably, the non-water-soluble solvent includes at least one of aromatic hydrocarbons, chloroalkanes, ethers, ketones, or esters; the mass of the non-water-soluble solvent is 0.5 to 2 times that of the phenolic material. More preferably, the non-water-soluble solvent includes at least one of toluene or methyl isobutyl ether.

[0032] In some embodiments, preferably, the process further includes step (5), in which the oil layer is added to a distillation vessel with 5 to 30 trays, the temperature is raised first to atmospheric pressure and then to reduced pressure to remove the solvent, and then the material in the distillation vessel is transferred to a high-efficiency distillation vessel with 50 to 250 trays to obtain 99% 2,4-xylenol or 2,4 / 2-ethyl-6-xylenol, and the residue in the vessel is fed into the polymerization reactor together with 2,4 / 2,5-xylenol for recycling.

[0033] In some embodiments, preferably, the pressure of the vacuum distillation is -0.03 to -0.07 MPa, and the reflux ratio is (1 to 5):1; The distillation pressure is -0.07 to -0.1 MPa, and the reflux ratio is (5 to 25):1.

[0034] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0035] Example 1 (1) In the reactor, start stirring and add 14.7 parts of the previous batch of prepolymer (residue after oil distillation) (all figures in the examples are by weight), 1000 parts of 99.2% coal phenol, and 10 parts of 36% hydrochloric acid (the total amount of hydrochloric acid is 1.0 wt% of the total amount of phenolic raw materials). After feeding, measure the pH of the reaction solution with pH paper to be 1.8. Adjust the reflux and venting devices, open the steam valve to raise the temperature. The steam pressure should not exceed 0.3 MPa. Add 1 part of 37% formaldehyde dropwise at a reactor temperature of 85-90℃. 263 parts (total formaldehyde usage is 1.36 times the total molar mass of phenol, m-cresol, 2,5-xylenol, and 2,3-xylenol), 1000 parts of 2,4 / 2,5-xylenol extracted by vaporized phenol (containing 13 parts of p-cresol, 22 parts of m-cresol, 36 parts of 2,3-xylenol, 549 parts of 2,4-xylenol, and 380 parts of 2,5-xylenol), added dropwise over 2 hours, with slow heating after addition, and 10 parts of 36% hydrochloric acid added to prevent excessive heating, which could cause the reaction solution to overflow and affect the resin quality.

[0036] The temperature was raised to 95℃, and the reaction was started by maintaining the temperature at 95-100℃. The temperature was stabilized at 98℃, and the sample was taken for analysis after 3 hours. The liquid chromatography analysis showed that 0.18% of 2,5-xylenol and 15.95% of free phenol were qualified. The temperature was then slightly lowered to 68℃.

[0037] (2) Adjust the vacuum device and start vacuum dehydration. The dehydration temperature is controlled at 80-85℃ for 3 hours and the final pressure is controlled at -0.075Mpa. At the same time, observe the water level of the receiver. Specifically, the water level should be kept constant within 20 minutes.

[0038] (3) Gradually increase the vacuum to -0.095 MPa for 1 hour, further increase the temperature to dehydrate, and when the temperature of the material in the kettle reaches 140℃ and no liquid distills out, the dehydration time is 2.5 hours. Continue to keep the temperature for 1 hour, stop dehydration, use nitrogen to release the vacuum, and under nitrogen protection, put the hot material into a stainless steel pan to cool, then crush and bag it to obtain 1709.8 parts of phenolic resin (softening point 94.2℃, free phenol 1.9%, residual carbon 73.6%), with a color of off-white to light yellow, and distillate is obtained at the same time.

[0039] (4) Add the distillate to the extraction vessel, add 2 parts of hydrochloric acid (0.1 wt% of the total amount of phenolic raw materials), heat to 100°C and react for 2 hours, then add 1500 parts of methyl isobutyl ketone (0.75 times the mass of phenolic materials), stir for 30 minutes and separate into layers. Wash the oil layer once with 100 parts of water, let it stand and separate into layers. The upper layer is 1960.9 parts of methyl isobutyl ketone solution of 2,4-dimethylphenol (containing 1.9 parts of p-cresol, 463.3 parts of 2,4-dimethylphenol, and 12.2 parts of prepolymer). Heat the water layer and reflux to obtain 2.9 parts of methyl isobutyl ketone for reuse. Cool the water layer to 50°C and send it to the waste treatment workshop for treatment.

[0040] (5) 1960.9 parts of 2,4-xylenol methyl isobutyl ketone solution were added to a distillation vessel with 10 trays. The temperature was raised first to atmospheric pressure and then to vacuum distillation (-0.05 MPa, reflux ratio 1:1) to remove 1459.7 parts of methyl isobutyl ketone (of which: 1.6 parts of p-cresol and 2.1 parts of 2,4-xylenol). Then the remaining material in the vessel was transferred to a high-efficiency distillation column (100 theoretical trays) and vacuum distilled (-0.085 MPa, reflux ratio 10:1) to obtain 434.1 parts of 99.82,4-xylenol. 14.8 parts of the vessel residue (including 12.2 parts of prepolymer) were returned to the first step polymerization reactor and used together with 2,4 / 2,5-xylenol raw materials for the next batch of phenolic resin synthesis.

[0041] Example 2 (1) In the reactor, start stirring and add 14.3 parts of the previous batch of prepolymer, 1000 parts of 2,4 / 2,5-xylenol extracted by gasification (containing 13 parts of p-cresol, 22 parts of m-cresol, 36 parts of 2,3-xylenol, 549 parts of 2,4-xylenol, and 380 parts of 2,5-xylenol), and 20 parts of 36% hydrochloric acid (the total amount of hydrochloric acid is 2.0 wt% of the total amount of phenolic raw materials). After feeding is complete, use p The pH of the reaction solution was determined to be 1.8 using H test paper. After adjusting the reflux and venting devices, the steam valve was opened to raise the temperature. The steam pressure should not exceed 0.3 MPa. The reactor temperature was 85-90℃. 400 parts of 37% formaldehyde were added dropwise (the total amount of formaldehyde was 1.36 times the total molar mass of m-cresol, 2,5-xylenol, and 2,3-xylenol). The dropwise addition took 2 hours. After the addition was completed, the temperature was raised slowly to avoid excessive heating, which could cause the reaction solution to overflow and affect the resin quality.

[0042] The temperature was raised to 95℃, and the reaction was started by maintaining the temperature at 95-100℃. The temperature was stabilized at 98℃, and the sample was taken for analysis after 3 hours. The liquid chromatography analysis showed that 2,5-xylenol was 0.42% and free phenol was 35.26%, which was acceptable. The temperature was then slightly lowered to 70℃.

[0043] (2) Adjust the vacuum device and start vacuum dehydration. The dehydration temperature is controlled at 80-85℃ for 2.5 hours. The final pressure is controlled at -0.075Mpa. At the same time, observe the water level of the receiver. Specifically, the water level should be kept constant within 20 minutes.

[0044] (3) Gradually increase the vacuum to -0.095 MPa for 1 hour, further increase the temperature to dehydrate, and when the temperature of the material in the kettle reaches 130°C and no liquid distills out, dehydrate for 3 hours, continue to keep warm for 1 hour, stop dehydration, use nitrogen to release the vacuum, and under nitrogen protection, put the hot material into a stainless steel pan to cool, then crush and bag it to obtain 610.5 parts of phenolic resin (softening point 91.3°C, free phenol 2.3%, residual carbon 75.1%), with a color of off-white to light yellow, and distillate is obtained at the same time.

[0045] (4) Add the distillate to the extraction vessel, add 2 parts of hydrochloric acid (0.2 wt% of the total amount of phenolic raw materials), heat to 100°C and react for 2 hours, then add 1500 parts of methyl isobutyl ketone (1.5 times the mass of phenolic materials), stir for 30 minutes and separate into layers. Wash the oil layer once with 70 parts of water, let it stand and separate into layers. The upper layer is 1951.2 parts of methyl isobutyl ketone solution of 2,4-dimethylphenol (containing 2.3 parts of p-cresol, 459.8 parts of 2,4-dimethylphenol, and 11.6 parts of prepolymer). Heat the water layer and reflux to obtain 2.1 parts of methyl isobutyl ketone for reuse. Cool the water layer to 50°C and send it to the waste treatment workshop for treatment.

[0046] (5) 1951.2 parts of 2,4-xylenol methyl isobutyl ketone solution were added to a distillation vessel with 10 trays. The temperature was raised first to atmospheric pressure and then to vacuum distillation (-0.05 MPa, reflux ratio 1:1) to remove 1466.1 parts of methyl isobutyl ketone (of which: 2.1 parts of p-cresol and 1.3 parts of 2,4-xylenol). Then the remaining material in the vessel was transferred to a high-efficiency distillation column (100 theoretical trays) and vacuum distilled (-0.085 MPa, reflux ratio 10:1) to obtain 446.9 parts of 99.6% 2,4-xylenol. 14.1 parts of the vessel residue (including 11.6 parts of prepolymer) were returned to the first step polymerization reactor and used together with 2,4 / 2,5-xylenol raw materials for the next batch of phenolic resin synthesis.

[0047] Example 3 (1) In the reactor, start stirring and add in sequence 118.6 parts of the previous batch of prepolymer, 500 parts of phenol, 200 parts of 99.1% m-cresol, 200 parts of 99.3% m-ethylphenol, 100 parts of 99% m-isopropylphenol / m-propylphenol, 1000 parts of 2,4 / 2,5-xylenol obtained from crude phenol extracted from tar (containing 48 parts of p-cresol, 53 parts of m-cresol, 94 parts of 2,3-xylenol, 86 parts of 2-ethyl-6-cresol, 428 parts of 2,4-xylenol, 281 parts of 2,5-xylenol, and 10 parts of o-isopropylphenol), and 800 parts of 37% formaldehyde (the total amount of formaldehyde used is phenol, m-cresol, m-ethylphenol, m-isopropylphenol, m-propylphenol, 2,5-xylenol, 2, The following ingredients are added: 1.6 times the total molar mass of 3-xylenol, 44 parts of oxalic acid (60 parts dissolved in hot water) (oxalic acid is 1.46 wt% of the total phenolic raw materials), and 75 parts of 85% phosphoric acid (phosphoric acid is 2.5 wt% of the total phenolic raw materials). After feeding, the pH of the reaction solution is measured to be 2.0 using pH test paper. The reflux and venting devices are adjusted, and the steam valve is opened to raise the temperature. The steam pressure should not exceed 0.3 MPa. The reaction is carried out at 80-85℃ for 1 hour. Then, the temperature is raised to 85-90℃ and 1367 parts of 37% formaldehyde and 1000 parts of 2,4 / 2,5-xylenol are added dropwise over 3 hours. After the addition is completed, the temperature is raised slowly to avoid the reaction solution overflowing due to excessive heating, which would affect the quality of the resin.

[0048] The temperature was raised to 95℃, and the reaction was started by maintaining the temperature at 95-100℃. The temperature was stabilized at 98℃, and the sample was taken for analysis after 3 hours. The liquid chromatography analysis showed that 0.79% of 2,5-xylenol and 15.75% of free phenol were within acceptable limits. The temperature was then slightly lowered to 70℃.

[0049] (2) Adjust the vacuum device and start vacuum dehydration. Control the dehydration temperature at 80-85℃, the time at 3 hours, and the final pressure at -0.08Mpa. At the same time, observe the water level in the receiver. Specifically, the water level should be constant within 20 minutes.

[0050] (3) Gradually increase the vacuum to -0.098 MPa for 1 hour, further increase the temperature to dehydrate, and when the temperature of the material in the kettle reaches 200℃ and no liquid distills out, dehydrate for 3 hours, continue to keep warm for 0.5 hours, stop dehydration, use nitrogen to release the vacuum, and under nitrogen protection, put the hot material into a stainless steel pan to cool, then crush and bag it to obtain 2586.3 parts of phenolic resin (softening point 108℃, free phenol 0.5%, residual carbon 77.4%), with a color of off-white to light yellow, and distillate is obtained at the same time.

[0051] (4) Add the distillate to the extraction vessel, add 4 parts hydrochloric acid (0.13 wt% of the total amount of phenolic raw materials) and 8 parts 37% formaldehyde, heat to 100℃ and react for 2 hours. After sampling and analysis to find 0.01% 2,5-xylenol, add 2000 parts ethyl acetate (0.67 times the mass of phenolic materials), stir for 30 minutes and separate into layers. Wash the oil layer once with 100 parts water, let it stand and separate into layers. The upper layer is p-cresol / 2,4- 3053.3 parts of an ethyl acetate solution of xylenol / 2-ethyl-6-cresol (containing 62.5 parts of p-cresol, 139.3 parts of 2-ethyl-6-cresol, 712 parts of 2,4-xylenol, 13.8 parts of o-isopropylphenol, 0.5 parts of other phenols, and 113.4 parts of prepolymer); 10.6 parts of ethyl acetate were obtained by reflux of the aqueous layer and reused, while 1831.1 parts of the aqueous layer were cooled to 40°C and sent to the waste treatment workshop for treatment.

[0052] (5) 3053.3 parts of the ethyl acetate solution of p-cresol / 2,4-xylenol / 2-ethyl-6-cresol were added to a distillation vessel with 30 trays. The temperature was raised first to atmospheric pressure and then to vacuum distillation (-0.05 MPa, reflux ratio 2:1) to remove 1967.6 parts of ethyl acetate (of which: p-cresol 6.3 parts, 2-ethyl-6-cresol 0.3 parts, 2,4-xylenol 0.8 parts). Then the remaining material in the vessel was transferred to a high-efficiency distillation column (theoretical trays 200), and vacuum distillation (-0.085 MPa, reflux ratio 20:1) was performed to obtain 99. 51.6 parts of 3% p-cresol, 748.1 parts of 99.97% 2,4-xylenol / 2-ethyl-6-cresol (132.7 parts of 2-ethyl-6-cresol, 615.2 parts of 2,4-xylenol, and 0.2 parts of other phenols), and 62 parts of 99.68% 2,4-xylenol / o-isopropylphenol (52.2 parts of 2,4-xylenol, 9.6 parts of o-isopropylphenol, and 0.2 parts of other phenols) were added. 118.3 parts of the reactor residue (including 113.4 parts of prepolymer) were returned to the first-step polymerization reactor to be used together with other phenolic substances for the next batch of phenolic resin synthesis.

[0053] 99.972,4-dimethylphenol / 2-ethyl-6-methylphenol can be easily separated by tert-butylation to obtain the highly efficient polymerization inhibitor 99% 6-tert-butyl-2,4-dimethylphenol and the pesticide intermediate 99% 2-ethyl-6-methylphenol; 2,4-dimethylphenol / o-isopropylphenol can be used to produce 99% 6-tert-butyl-2,4-dimethylphenol and o-isopropylphenol by tert-butylation.

[0054] Example 4 (1) In the polymerization reactor, start stirring and add 78.8 parts of prepolymer, 1000 parts of 99.2% coal-derived phenol, 130 parts of 31% liquid alkali (total alkali usage is 3wt% of the total phenol mass), and 664 parts of 37% formaldehyde in sequence. After feeding is complete, adjust the reflux and venting devices, open the steam valve to raise the temperature, start stirring, heat, and react at 75-80℃ for 4 hours. Then, start adding the remaining 1000 parts of 37% formaldehyde (total formaldehyde usage is 3wt% of the total phenol mass, m-cresol, 2,5-xylenol, 2,3-xylenol, m-cresol, 2,5-xylenol, 2,3-xylenol, 2,4-xylenol ... The reaction mixture consisted of 1.5 times the total molar mass of xylenol and 1000 parts of 2,4 / 2,5-xylenol extracted from coking crude phenol (containing 3.3 parts of p-cresol, 6.2 parts of m-cresol, 8.6 parts of 2,3-xylenol, 625 parts of 2,4-xylenol, and 356.9 parts of 2,5-xylenol). The mixture was added dropwise over 3 hours, followed by the addition of 64 parts of 31% liquid alkali to initiate the reaction. The temperature was raised to 90–95°C and maintained for 5 hours before sampling and analysis. Liquid chromatography analysis showed that 0.38% of 2,5-xylenol and 13.8% of free phenol were within acceptable limits.

[0055] (2) After the reaction is completed, add 90 parts of glacial acetic acid to neutralize to pH 7. Gradually open the vacuum to -0.085 MPa over 1 hour to dehydrate. First, separate the dehydrated water and phenol through the water separator on the reactor and return it to the reactor. Observe that the dehydration rate slows down. Continue to dehydrate by heating. After dehydration for 1.5 hours, transfer all the distilled material into the phenol water receiving tank and dehydrate for another 2.5 hours. The liquid temperature in the reactor is 82℃. Take a sample for analysis and the moisture content of the material is 3.9%, which is qualified. (3) Add 80 parts of ethylene glycol to the reactor, stir evenly, take samples to analyze moisture and viscosity. Stop vacuuming when the moisture content is 3.4%, and add 30 parts of ethanol to adjust the viscosity to 14 Pa.s. Cool down to 50℃ and discharge 2169.8 parts of material. Test the free phenol content of 8.8%, free aldehyde content of 0.96%, solid content of 78.3%, residual carbon content of 47.2%, moisture content of 3.3%, and viscosity to 15 Pa.s.

[0056] (4) Add 4 parts of hydrochloric acid to the distilled water (the amount is 0.2wt% of the total amount of phenolic raw materials), heat to 100℃ and react for 1.5 hours. Take a sample for analysis. 0.08% of 2,3-xylenol / 2,5-xylenol is qualified. After 1 hour, cool the material to 60℃ and add 2000 parts of ethyl acetate (1.0 times the mass of phenolic materials). Stir for 1 hour, let stand for 0.5 hours, and separate into layers. Heat the lower water layer to recover 9.5 parts of ethyl acetate and send it to the wastewater treatment workshop for treatment (1398 parts). Wash the upper oil layer once with 100 parts of water. The oil layer obtained by separation is 2491.2 parts of unreacted phenolic substance solution (0.4 parts of p-cresol, 447.3 parts of 2,4-xylenol, 0.5 parts of 2,5-xylenol, and 72.3 parts of prepolymer).

[0057] (5) 2490.9 parts of the water-washed layered oil were added to a distillation kettle with 30 trays. The temperature was raised first to normal pressure and then reduced pressure (-0.05MPa, reflux ratio 3:1) to distill off 1952 parts of solvent. The material in the distillation kettle was transferred to a high-efficiency distillation kettle with 150 trays and distilled (-0.085MPa, reflux ratio 15:1) to obtain 428.5 parts of 99.8% 2,4-xylenol. 79.1 parts of residue in the distillation kettle (6.8 parts of phenol and 72.3 parts of prepolymer) were left. The prepolymer was returned to the polymerization reactor for the next batch of phenolic resin synthesis.

[0058] Example 5 (1) In the polymerization reactor, start stirring and add 172.9 parts of prepolymer, 1000 parts of 2,4 / 2,5-xylenol (containing 48 parts of p-cresol, 53 parts of m-cresol, 94 parts of 2,3-xylenol, 86 parts of 2-ethyl-6-cresol, 428 parts of 2,4-xylenol, and 291 parts of 2,5-xylenol), 250 parts of 25% ammonia (3.1 wt% of the total phenol content), and 387 parts of 37% formaldehyde (the total formaldehyde content is m-cresol, 2,5-xylenol, ... After feeding (1.5 times the total molar mass of 2,3-xylenol), adjust the reflux and venting devices, open the steam valve to raise the temperature, start the stirrer, and heat slowly to 90-95℃. Maintain the temperature for 1.5 hours. Then, start adding 500 parts of the remaining 37% formaldehyde and simultaneously add 1000 parts of the remaining 2,4 / 2,5-xylenol. The addition is completed in 2 hours. Start maintaining the temperature for 6 hours and take samples for analysis. Liquid chromatography analysis shows that 0.64% of 2,5-xylenol and 33.22% of free phenol are within acceptable limits.

[0059] (2) After the reaction is completed, gradually open the vacuum to -0.08MPa over 1 hour to dehydrate. First, separate the dehydrated water and phenol through the water separator on the reactor and return it to the reactor. Observe the dehydration rate as it slows down or until the temperature drops to about 75℃. Then, continue heating to dehydrate. After dehydration for 1.5 hours, put all the distilled material into the phenol water receiving tank and dehydrate for another 2 hours. (3) Increase the dehydration vacuum to -0.95MPa and continue distilling until no liquid distills out at 130℃. Continue to keep warm for 0.5 hours, stop dehydration, remove the vacuum with nitrogen, and while hot, put the material into a stainless steel pan for cooling under nitrogen protection. Then crush and bag it to obtain 1234.2 parts of phenolic resin (softening point 89.6℃, free phenol 2.4%, carbon residue 75.7%), which is white in color. At the same time, distillate is obtained.

[0060] (4) Add 8 parts of 36% hydrochloric acid to the distilled water (the amount is 0.4wt% of the total amount of phenolic raw materials), heat to 100℃ and react for 1 hour. Take a sample for analysis. The 2,5-xylenol content is 0.04% and is qualified. After 0.5 hours, cool the material to 60℃, add 2000 parts of methyl isobutyl ketone (the mass is 1.0 times that of the phenolic materials), stir for 1 hour, let stand for 0.5 hours, separate into layers, and heat the lower water layer to recover 4.8 parts of methyl isobutyl ketone before sending it to the next step. The wastewater was treated in the wastewater treatment workshop (approximately 994.8 parts). The upper oil layer was washed once with 100 parts of water. The resulting oil layer was a methyl isobutyl ketone solution of p-cresol / 2,4-xylenol / 2-ethyl-6-cresol, consisting of 3005.7 parts (p-cresol 42.8 parts, 2-ethyl-6-cresol 124.1 parts, 2,3-xylenol 0.1 parts, 2,4-xylenol 693.5 parts, 2,5-xylenol 0.4 parts, and prepolymer 168.8 parts).

[0061] (5) 3005.7 parts of the water-washed layered oil were added to a distillation kettle with 10 trays. The temperature was raised first to atmospheric pressure and then reduced to vacuum (-0.05 MPa, reflux ratio 3:1) to distill off 1961.1 parts of solvent. The material in the distillation kettle was transferred to a high-efficiency distillation kettle with 200 trays and distilled (-0.085 MPa, reflux ratio 20:1) to obtain 37.9 parts of 99.8% p-cresol and 750 parts of 99.96% 2,4-xylenol / 2-ethyl-6-cresol (639.4 parts of 2,4-xylenol, 110.3 parts of 2-ethyl-6-cresol, and 0.3 parts of 2,5-xylenol). 175.1 parts of residue in the bottom of the distillation kettle (6.3 parts of phenol and 168.8 parts of prepolymer) were obtained. The prepolymer was returned to the polymerization reactor for the next batch of phenolic resin synthesis.

[0062] 99.96% 2,4-dimethylphenol / 2-ethyl-6-methylphenol is produced by tert-butylation reaction to produce 99.5% high-efficiency polymerization inhibitor 6-tert-butyl-2,4-dimethylphenol and pesticide intermediate 2-ethyl-6-methylphenol.

[0063] Example 6 (1) In the polymerization reactor, start stirring and add 68.3 parts of prepolymer, 1000 parts of 2,4 / 2,5-xylenol extracted from coking crude phenol (containing 3.3 parts of p-cresol, 6.2 parts of m-cresol, 8.6 parts of 2,3-xylenol, 625 parts of 2,4-xylenol, and 356.9 parts of 2,5-xylenol), and 130 parts of 31% liquid alkali (4% of the total mass of phenol). After feeding (wt%), adjust the reflux and venting devices, open the steam valve to raise the temperature, start stirring, and heat to 90-95℃. Then, start adding 370 parts of 37% formaldehyde (the total amount of formaldehyde is 1.5 times the total molar mass of m-cresol, 2,5-xylenol, and 2,3-xylenol). The addition is completed in 2 hours. Then, start the heat preservation reaction and keep it at the temperature for 4 hours. Take a sample for analysis. Liquid chromatography analysis shows that 2,5-xylenol is 1.17% and free phenol is 38.45%, which is qualified.

[0064] (2) After the reaction is completed, add 61 parts of glacial acetic acid to neutralize to pH 6.5. Gradually open the vacuum to -0.09MPa over 1 hour to dehydrate. First, separate the dehydrated water and phenol through the water separator on the reactor and return it to the reactor. Observe the dehydration rate slowing down or until the temperature drops to about 70-75℃. Then heat and continue dehydration. After dehydration for 1 hour, transfer all the distilled material into the receiving tank. Dehydrate for about 2 more hours. The liquid temperature in the reactor is 80℃. Take a sample for analysis. The moisture content of the material is 4.2%, which is qualified. (3) Add 30 parts of ethylene glycol to the reactor, stir evenly, take a sample to analyze the moisture and viscosity. Stop vacuuming when the moisture content is 3.8%, and add 10 parts of ethanol to adjust the viscosity to 12 Pa·s. Cool down to 50℃ and discharge 719.6 parts of material. Test the free phenol content of 8.2%, free aldehyde content of 0.93%, solid content of 80.1%, residual carbon content of 49.2%, moisture content of 3.7%, and viscosity to 13 Pa·s.

[0065] (4) Add 2 parts of hydrochloric acid to the distilled water (0.2 wt% of the total amount of phenolic raw materials), heat to 100℃ and react for 1 hour. Take a sample for analysis. 0.2% of 2,3 / 2,5-xylenol is qualified. After 0.5 hours, cool the material to 60℃ and add 2000 parts of ethyl acetate (2.0 times the mass of phenolic materials). Stir for 1 hour, let stand for 0.5 hours, and separate into layers. Heat the lower water layer to recover 3.1 parts of ethyl acetate and send it to the wastewater treatment workshop for treatment (385 parts). Wash the upper oil layer once with 100 parts of water. The oil layer obtained by separation is 2516.6 parts of unreacted phenolic substance solution (0.5 parts of p-cresol, 0.1 parts of 2,3-xylenol, 473.3 parts of 2,4-xylenol, 0.6 parts of 2,5-xylenol, and 64.1 parts of prepolymer).

[0066] (5) 2516.6 parts of the water-washed and separated oil layer were added to a distillation kettle with 10 trays. The temperature was raised first to normal pressure and then reduced pressure (-0.05MPa, reflux ratio 3:1) to distill off 1961 parts of solvent. The material in the distillation kettle was transferred to a high-efficiency distillation kettle with 150 trays and distilled (-0.085MPa, reflux ratio 15:1) to obtain 452.6 parts of 99.8% 2,4-xylenol. 68.7 parts of residue in the bottom of the distillation kettle (4.6 parts of phenol and 64.1 parts of prepolymer) were left. The prepolymer was returned to the polymerization reactor for the next batch of phenolic resin synthesis.

[0067] Example 7 (1) In the polymerization reactor, start stirring and add 56.2 parts of prepolymer, 500 parts of 2,4 / 2,5-xylenol (a byproduct of the toluene sulfonation alkaline solution method for producing p-cresol, including 41 parts of p-cresol, 3 parts of m-cresol, 377 parts of 2,4-xylenol, and 79 parts of 2,5-xylenol), and 160 parts of 25% ammonia (4wt% of the total phenol mass) in sequence. After feeding, adjust the reflux and venting devices, open the steam valve to raise the temperature, start stirring, heat to 95-105℃, and start adding 218 parts of 37% formaldehyde (the total amount of formaldehyde is 2.0 times the total molar mass of m-cresol and 2,5-xylenol), and the remaining 500 parts of 2,4 / 2,5-xylenol. The addition is completed in 3 hours. Start the heat preservation reaction and take samples for analysis after 3 hours. Liquid chromatography analysis shows that 0.34% of 2,5-xylenol and 54.61% of free phenol are qualified.

[0068] (2) After the reaction is completed, gradually open the vacuum to -0.08MPa over 1 hour to dehydrate. First, separate the dehydrated water and phenol through the water separator on the reactor and return it to the reactor. Observe the dehydration rate slowing down or until the temperature drops to about 70℃. Then heat and continue dehydration. After dehydration for 1 hour, put all the distilled material into the receiving tank and dehydrate for about 2 more hours. (3) Increase the dehydration vacuum to -0.95MPa and continue distilling until no liquid distills out at 190℃. Continue to keep warm for 0.5 hours, stop dehydration, remove the vacuum with nitrogen, and while hot, put the material into a stainless steel pan for cooling under nitrogen protection. Then crush and bag it to obtain 351.5 parts of phenolic resin (softening point 105℃, free phenol 0.8%, residual carbon 77.6%), which is white in color. At the same time, distillate is obtained.

[0069] (4) Add 2 parts of oxalic acid to the distilled water (the amount is 0.2wt% of the total amount of phenolic raw materials), heat to 100℃ and react for 1.5 hours. Take a sample for analysis. 0.01% of 2,5-xylenol is qualified. After 0.5 hours, cool the material to 60℃ and add 2000 parts of toluene (2.0 times the mass of phenolic materials). Stir for 1 hour, let stand for 0.5 hours, and separate into layers. Heat the lower water layer to recover 1.3 parts of toluene and send it to the wastewater treatment workshop for treatment (297 parts). Wash the upper oil layer with 100 parts of water once. The oil layer obtained by separation is a toluene solution of p-cresol / 2,4-xylenol with 2731.8 parts (43.8 parts of p-cresol, 659.7 parts of 2,4-xylenol, 0.1 parts of 2,5-xylenol, and 52.2 parts of prepolymer).

[0070] (5) 2516.6 parts of the water-washed and separated oil layer were added to a distillation kettle with 20 trays. The temperature was raised first to normal pressure and then reduced pressure (-0.05MPa, reflux ratio 2:1) to distill off 1962.2 parts of solvent. The material in the distillation kettle was transferred to a high-efficiency distillation kettle with 200 trays and distilled (-0.085MPa, reflux ratio 20:1) to obtain 39.5 parts of 99.7% p-cresol and 609.5 parts of 99.9% 2,4-xylenol. 56.1 parts of residue in the bottom of the distillation kettle (3.9 parts of phenol and 52.2 parts of prepolymer) were left. The prepolymer was returned to the polymerization reactor for the next batch of phenolic resin synthesis.

[0071] Comparative Example 1 (1) In the reactor, start stirring and add 4000 parts of 99.9% molten petrochemical grade phenol and 45 parts of oxalic acid (45 parts dissolved in hot water) in sequence. After feeding, use pH test paper to determine that the pH of the reaction solution is 3.5-4. Adjust the reflux and venting devices, and the liquid temperature is 51℃. Open the steam valve to raise the temperature. The steam pressure should not exceed 0.3Mpa. Gradually add 3070 parts of 37% formaldehyde (the amount of formaldehyde is 0.89 times the molar amount of phenol) at 90℃. The addition time is 2 hours. After adding, slowly raise the temperature. The heating rate should be strictly controlled within 1.5℃ / min. The set rate is 1.0℃ / min to avoid the temperature rising too fast, which would cause the reaction solution to overflow and affect the resin quality.

[0072] (2) Heat to 95℃ and start the reaction. The reaction temperature is controlled at 95-100℃ and stabilized at 98℃. After 4 hours of heat preservation, take a sample for analysis. Gel chromatography analysis shows phenol content of 13.6%. Open the valve of the condenser and separator system, reflux water vapor distillation to remove water, continuously separate the oil layer at the bottom of the separator, and return the upper water layer back into the kettle. After observing that there is no obvious oily substance in the condensate, heat to 120℃ to remove most of the water, and then cool down slightly.

[0073] (3) Cool the reactants to 80°C, adjust the vacuum device, start vacuum dehydration, control the dehydration temperature at 80-85°C, control the time at 3 hours, control the final pressure at -0.075--0.08 MPa, and observe the water level in the receiver at the same time. Specifically, the water level should be kept constant within 20 minutes.

[0074] (4) Divide the pre-dehydrated material into two portions and perform the following treatment: One batch of phenolic resin was gradually increased to -0.090 MPa for 2 hours, while the temperature was further increased for dehydration. When the temperature of the material in the reactor reached 120°C and no liquid distilled out, it was kept at this temperature for 1 hour, and then the dehydration was stopped. The vacuum was released with nitrogen, and the material was discharged while hot into a stainless steel pan under nitrogen protection. After cooling, it was crushed and bagged to obtain 2074 parts of phenolic resin (softening point 96.7, free phenol 2.3%, residual carbon 72.8%), with a color of off-white to pale yellow.

[0075] Another batch gradually increased the vacuum to -0.095 MPa for 1 to 2 hours, while further increasing the temperature for dehydration. When the temperature of the material in the reactor reached 210°C and no liquid distilled out, it was kept at this temperature for 1 hour, and dehydration was stopped. The vacuum was released with nitrogen, and the hot material was discharged into a stainless steel pan under nitrogen protection, cooled, crushed, and bagged to obtain 1975.8 parts of thermoplastic phenolic resin (softening point 109.1°C, free phenol 0.9%, residual carbon 75.9%), with a color ranging from off-white to pale yellow.

[0076] A total of 2,943 portions of liquid were extracted during the entire process.

[0077] Comparative Example 2 (1) In a 2000L enamel-lined reactor with a jacket, 800kg of 99.9% petrochemical phenol, 12kg of sodium hydroxide, and 1020kg of 36.5% formaldehyde are fed in sequence (sodium hydroxide is dissolved in 20kg of water). Steam is passed through the jacket to raise the temperature. When the temperature reaches about 40-45℃, the steam is turned off. When the temperature reaches about 50-55℃, the steam in the jacket is turned off again. The steam in the jacket is discharged. A suitable amount of cooling water is passed through, and the temperature is slowly raised to 80-85℃. The reaction is kept at this temperature for 2 hours. It is important to pay close attention to the temperature changes of the materials before and after turning on and off the steam and cooling water.

[0078] (2) After the reaction is complete, add 13.2 kg of glacial acetic acid to neutralize to pH 6.5. Maintain this for 10 minutes and take a sample to retest the pH. Start dehydration. Gradually control the vacuum to -0.075 MPa over 1 hour. Observe the dehydration speed slowing down and the temperature dropping to 70℃. Turn on the jacket steam heating. During dehydration, continuously adjust the steam switch according to the water output speed to ensure that dehydration is completed at the lowest possible temperature. Continue to pass steam in the later stage of dehydration and control the final liquid temperature at 80℃. When the water level reaches the required value (638 kg), take a sample to analyze the water content and viscosity. Stop vacuuming when the water content is 2.7%. Add 40 kg of ethylene glycol and stir for 0.5 hours. Take a sample with a viscosity of 28 Pa·s. Then use 10 kg of anhydrous ethanol to adjust the viscosity to 18 Pa·s.

[0079] (3) After the viscosity reaches the requirement, the temperature is reduced to 50℃ and the material is discharged, yielding 1100 kg of liquid material. The test results showed that the free phenol content was 8.8%, the free aldehyde content was 1.21%, the solid content was 75.8%, the residual carbon content was 45.6%, the moisture content was 2.6%, and the viscosity was 18 Pa·s.

[0080] Comparing the performance indicators of the various embodiments with those of Comparative Examples 1 and 2, the solid resin produced had approximately the same amount of free phenol, significantly higher carbon residue, and a slightly lower softening point (indicating an increase in the linearity of the resin chain, resulting in a slightly lower softening point and better processing performance). The liquid phenolic resin produced had a high solid content, high carbon residue, and lower free phenol and free aldehyde content, making it a better binder for resins.

[0081] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0082] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol, characterized in that, Includes the following components: (1) Add a portion of 2,4 / 2,5-xylenol, a portion of aldehydes and the first catalyst to the polymerization reactor, start stirring, heat to 60-105℃ and react for 0-6 hours, add the remaining aldehydes and the remaining 2,4 / 2,5-xylenol dropwise at 60-105℃ for 1-4 hours, and keep warm for 1-6 hours after addition and take a sample for analysis. The 2,5-xylenol content is ≤5% and qualified. (2) Control the temperature in the polymerization reactor to 60-80℃, perform vacuum dehydration, dehydration temperature is 80-85℃, dehydration time is 2-5 hours, final pressure is -0.075--0.08Mpa, and observe the water level in the receiver at the same time, specifically based on the water level being constant within 20 minutes; (3) Increase the vacuum in the polymerization reactor to -0.09 to -0.1 MPa within 1 to 2 hours, and at the same time further heat and dehydrate. When the temperature of the material in the reactor reaches 100 to 230°C and no liquid distills out, the dehydration time is 2 to 6 hours. Keep warm for 0.5 to 1 hour, stop dehydration, use nitrogen to release the vacuum, and discharge the material while it is hot under nitrogen protection. After cooling, phenolic resin is obtained.

2. The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol according to claim 1, characterized in that, In step (1), a first phenolic component is added to the polymerization reactor. The first phenolic component includes at least one of m-cresol, m-ethylphenol, m-isopropylphenol, m-propylphenol, 3,5-xylenol, phenol, or 3-ethyl-5-cresol. The amount of the first phenolic component added is 0.1 to 200 wt% of 2,4 / 2,5-xylenol. And / or, in step (1), a portion of the 2,4 / 2,5-xylenol is 0 to 100 wt% of the total amount of 2,4 / 2,5-xylenol, and a portion of the aldehyde is 0 to 100 wt% of the aldehyde. When the portion of the aldehyde is 0 wt%, the reaction time at 60 to 105°C is 0. When the portion of the aldehyde is not 0 wt%, the reaction time at 60 to 105°C is not 0.

3. The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol according to claim 2, characterized in that, In step (1), the 2,4 / 2,5-dimethylphenol is obtained by distillation of crude phenol extracted from coal coking crude phenol, medium-low temperature coal gasification crude phenol, or phenol-containing coal tar extracted by coal pyrolysis; the 2,4 / 2,5-dimethylphenol includes 0-15 wt% m-p-cresol, 0-2 wt% o-ethylphenol, 70-100 wt% 2,4 / 2,5-dimethylphenol, 0-10 wt% 2-ethyl-6-cresol, 0-5 wt% o-isopropylphenol, and 0-30 wt% 2,3-dimethylphenol; And / or, in step (1), the aldehyde includes at least one of paraformaldehyde, formaldehyde or acetaldehyde, and the amount of the aldehyde is 1 to 2.5 times the total molar amount of phenol, m-cresol, 3,5-dimethylphenol, 2,3-dimethylphenol, 2,5-dimethylphenol, m-ethylphenol, m-isopropylphenol, m-propylphenol, and 3-ethyl-5-cresol.

4. The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol according to claim 1, characterized in that, In step (1), the first catalyst includes at least one of oxalic acid, formic acid, phosphoric acid, hydrochloric acid, aminosulfonic acid, benzenesulfonic acid, ammonia or organic base; the amount of the first catalyst is 0.1 to 10 wt% of the total amount of phenolic raw materials.

5. The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol according to claim 1, characterized in that, In step (1), the first catalyst includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, barium hydroxide, ammonia, or an organic base, and the amount of the first catalyst is 0.1 to 10 wt% of the total amount of phenolic raw materials. Step (2) involves adding glacial acetic acid or formic acid to neutralize the pH to 6-7 after the reaction is complete, gradually increasing the vacuum to -0.07 to -0.1 MPa over 0.5-1 hours to begin dehydration. When the dehydration rate slows down or the temperature drops to around 70-75°C, heating is used to continue dehydration, controlling the final liquid temperature at 70-90°C until the water level reaches the required value. A sample is then taken for analysis to determine the moisture content of the material to be ≤5%. Step (3) involves adding ethylene glycol to the polymerization reactor, stirring it evenly, taking samples to analyze the moisture and viscosity, stopping the vacuuming when the moisture content is 2-5%, and adding ethanol to adjust the viscosity to 10-30 Pa·s according to the requirements of different products. After the viscosity reaches the required level, the temperature is lowered to 50°C and the material is discharged. The amount of ethylene glycol used is 1-10% of the total mass of the phenolic raw materials.

6. The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol according to claim 4 or 5, characterized in that, The process also includes step (4), adding a second catalyst to the distilled material, heating to 80-105℃ and reacting for 1-3 hours, taking a sample for analysis and finding that 2,5-xylenol is ≤0.5%, adding a non-water-soluble solvent, stirring for 0.5-2 hours, letting stand for 0.5-1 hours, separating the layers, heating the lower water layer to 95-105℃ to remove a small amount of solvent, and then cooling it to 40-50℃ to send it to the wastewater treatment section for treatment, and the upper oil layer being a solution containing unreacted 2,4-xylenol.

7. The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol according to claim 6, characterized in that, The second catalyst is an acidic catalyst or a basic catalyst. The acidic catalyst includes at least one of oxalic acid, formic acid, phosphoric acid or hydrochloric acid, and the basic catalyst includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate or ammonia water. The amount of the second catalyst is 0.01 to 0.5 wt% of the total amount of phenolic raw materials.

8. The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol according to claim 6, characterized in that, The non-water-soluble solvent includes at least one of aromatic hydrocarbons, chloroalkanes, ethers, ketones, or esters; the mass of the non-water-soluble solvent is 0.5 to 2 times that of the phenolic material.

9. The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol according to claim 6, characterized in that, The process also includes step (5), in which the oil layer is added to a distillation vessel with 5 to 30 trays, and the solvent is removed by distillation under normal pressure and then under reduced pressure. The material in the distillation vessel is then transferred to a high-efficiency distillation vessel with 50 to 250 trays to obtain 99% 2,4-xylenol or 2,4 / 2-ethyl-6-xylenol. The residue in the vessel is fed into the polymerization reactor along with 2,4 / 2,5-xylenol for recycling.

10. The method for synthesizing phenolic resin from 2,4-xylenol / 2,5-xylenol according to claim 9, characterized in that, The pressure of the vacuum distillation is -0.03 to -0.07 MPa, and the reflux ratio is (1 to 5):1; The distillation pressure is -0.07 to -0.1 MPa, and the reflux ratio is (5 to 25):1.