阅读说明：本技术 一种酚醛树脂及其制备方法和应用 (Phenolic resin and preparation method and application thereof ) 是由 唐地源 李枝芳 马庆 王明吉 刘兆峰 于 2020-07-30 设计创作，主要内容包括：本发明公开一种酚醛树脂,其中,所述酚醛树脂以包含有1～45个带羟基的芳香环结构的共聚物为主要成分；所述酚醛树脂的pH值为5.0～7.5,优选5.5～6.5,更优选5.5～6.0；所述酚醛树脂的灰分含量不大于1.5％,优选不大于1.2％,更优选不大于1.0％。所述酚醛树脂可由包含酚类化合物、醛类化合物、酸性木质素、木质素溶液和成碳剂的反应原料在碱性催化剂作用下反应制得；所述酸性木质素的pH为3.0～5.5,灰分不大于0.8％。本发明还公开一种制备所述酚醛树脂的方法,及其在预焙阳极制备中的应用。(The invention discloses a phenolic resin, wherein the phenolic resin takes a copolymer containing 1-45 aromatic ring structures with hydroxyl groups as a main component; the pH value of the phenolic resin is 5.0-7.5, preferably 5.5-6.5, and more preferably 5.5-6.0; the ash content of the phenolic resin is not more than 1.5%, preferably not more than 1.2%, more preferably not more than 1.0%. The phenolic resin can be prepared by reacting reaction raw materials comprising a phenolic compound, an aldehyde compound, acidic lignin, a lignin solution and a carbon forming agent under the action of an alkaline catalyst; the pH value of the acidic lignin is 3.0-5.5, and the ash content is not more than 0.8%. The invention also discloses a method for preparing the phenolic resin and application thereof in the preparation of a prebaked anode.)

1. A phenolic resin, wherein,

the pH value of the phenolic resin is 5.0-7.5, preferably 5.5-6.5, and more preferably 5.5-6.0;

the ash content of the phenolic resin is not more than 1.5%, preferably not more than 1.2%, more preferably not more than 1.0%.

2. The phenolic resin of claim 1, wherein the phenolic resin has a elemental sulphur content of no more than 1.0%, preferably no more than 0.5%, more preferably no more than 0.25%.

3. The phenolic resin according to claim 1 or 2, comprising, based on the total weight of the phenolic resin: 45 to 70 wt% of a polymer having an aromatic ring structure with 1 to 6 hydroxyl groups, 15 to 30 wt% of a polymer having an aromatic ring structure with 7 to 18 hydroxyl groups, and 0 to 10 wt% of a polymer having an aromatic ring structure with 19 to 45 hydroxyl groups.

4. The phenolic resin of any of claims 1-3, comprising about 0.2 to 1.5 wt% of a carbon former based on the total weight of the phenolic resin, the carbon former being elemental boron, III_BGroup elements, IV_BGroup element, V_BGroup element, VI_BGroup elements, VII_BGroup element or VIII group element, and one or more compounds which are soluble in water or phenolic resin.

5. The phenolic resin according to any one of claims 1 to 4, wherein,

the phenolic resin is obtained by modifying acidic lignin;

the phenolic resin is preferably prepared by reacting reaction raw materials comprising a phenolic compound, an aldehyde compound, acidic lignin, a lignin solution and a carbon forming agent under the action of an alkaline catalyst;

preferably, the pH value of the acidic lignin is 3.0-5.5, the ash content is not more than 0.8%,

preferably, the acidic lignin is a copolymer with an aromatic ring structure and a weight-average molecular weight of 450-3500 g/mol.

6. The phenolic resin of claim 5, wherein the lignin solution is produced from a reaction feedstock comprising phenol, dioxane, acidic lignin, and a polyhydroxy compound,

preferably, the polyol is one selected from sucrose, glucose and maltose.

7. The phenolic resin according to any one of claims 1 to 6, wherein,

the phenolic compound is selected from any one of phenol, cresol, resorcinol and alkylphenol;

preferably, the aldehyde compound is selected from any one of formaldehyde, acetaldehyde, butyraldehyde and benzaldehyde.

8. A method for producing the phenol resin according to any one of claims 1 to 7,

preparing a lignin solution: heating phenol to melt, adding dioxane, acidic lignin and polyhydroxy compound into the melted phenol, heating to reflux, cooling, and adjusting pH value to neutrality to obtain lignin solution;

preparation of modified phenolic resin polymer: heating a container filled with a phenolic compound and a basic catalyst, adding an aldehyde compound, heating for reaction, adding a carbon forming agent, adding acidic lignin after the carbon forming agent is completely dissolved, continuing to react, cooling to room temperature, stopping the reaction, and distilling the obtained product under reduced pressure to obtain the modified phenolic resin polymer.

Preparing phenolic resin: and (3) heating the obtained modified phenolic resin polymer, adding the prepared lignin solution, reacting, and cooling to obtain the phenolic resin.

9. The method of claim 8, wherein the lignin solution comprises, based on the total weight of the lignin solution: 10 to 40 wt% of dioxane, 20 to 40 wt% of phenol, 30 to 60 wt% of lignin, and 0 to 6 wt% of polyhydroxy compound.

10. The method according to claim 8 or 9, wherein in the step of preparing the modified phenolic resin polymer, the mass ratio of the acidic lignin to the phenolic compound is 0.1-0.32: 1, preferably 0.15-0.25: 1, and the mass ratio of the carbon forming agent to the phenolic compound is 0.005-0.05: 1, preferably 0.01-0.02: 1;

preferably, the mass ratio of the lignin solution and the phenolic compound used in the step of preparing the phenolic resin is 0.2-0.50: 1, and preferably 0.22-0.32: 1.

Technical Field

The invention belongs to the technical field of macromolecules. In particular to phenolic resin and a preparation method and application thereof.

Background

The phenolic resin is a high-molecular polymer synthesized by taking phenol formaldehyde as a raw material under the condition of alkali or acid, and has the characteristics of good wettability with carbon materials and high-temperature carbon residue. At present, phenolic resin is widely applied to refractory materials and high-temperature resistant materials as a graphite impregnating compound. The prebaked anode is made up by using petroleum coke and asphalt coke as aggregate and coal asphalt as adhesive, and can be used as anode material of prebaked aluminium electrolytic cell. However, asphalt smoke is released during the roasting process, and 3, 4-benzopyrene contained in the asphalt and the asphalt smoke can cause diseases such as skin cancer, lung cancer, gastric cancer, esophagus cancer and the like.

Patent document 1 discloses a method for preparing an alkali lignin-modified phenolic resin, which comprises the following steps: adding phenol, a first formaldehyde solution, alkali lignin, metal oxides and dilution water to a reactor; adding a second batch of formaldehyde solution into the reactor; adding a third batch of formaldehyde solution and a first batch of alkaline solution, adding a formaldehyde trapping agent and a second batch of alkaline solution, cooling and discharging.

Patent document 2 discloses a transition metal compound lignin-modified phenolic resin and a method for producing the same. The technical scheme is as follows: diluting water-soluble lignin modified phenolic resin with water to prepare a wood modified phenolic resin aqueous solution; and adding the transition metal compound into the lignin modified phenolic resin aqueous solution, stirring at room temperature, and performing reduced pressure dehydration to obtain the transition metal compound composite lignin modified phenolic resin. The water-soluble lignin modified phenolic resin is prepared from phenol, formaldehyde and lignosulfonate.

Patent document 3 discloses a method for preparing a lignin phenolic resin prepolymer, which comprises the following steps: mixing a lignin compound, a phenolic compound and an acid catalyst, and heating to 180-350 ℃ for reaction to obtain a mixed reaction solution; and mixing the mixed reaction liquid with formaldehyde, and performing polycondensation reaction to obtain the lignin phenolic resin prepolymer. The lignin compound is alkali lignin, high-boiling alcohol lignin, enzymatic hydrolysis lignin or lignin derivatives.

Patent document 4 discloses a method for producing a water-soluble phenol resin composite material for casting, which comprises: adding an alkaline catalyst and water into phenol to obtain a mixed solution A; dripping a formaldehyde solution into the mixed solution A to obtain a solution B; heating the solution, and continuing to react; adding alkali lignin into the reaction system to obtain a solution C; and adding acetylacetone into the solution C to obtain the water-soluble phenolic resin composite material.

In the prior art, although phenolic resin has higher carbon residue and excellent wetting property and bonding property for carbon materials, the carbonized phenolic resin contains a large amount of hard carbon and is difficult to graphitize, so that the resistivity is higher; the addition of lignin into the phenolic resin can effectively reduce the resistivity of the carbonized resin, but the lignin modified phenolic resin contains more sulfur content or metal ions at present, and the application of the lignin modified phenolic resin to an aluminum anode can cause secondary pollution to the anode. Therefore, it is highly desirable to provide a phenol resin having a low sulfur content, a small amount of metal components, and a good low-temperature carbonization performance.

Documents of the prior art

Patent document 1 CN101492522B publication document

Patent document 2 CN103289034B publication document

Patent document 3 CN103030759B publication document

Patent document 4 CN108299787A publication

Disclosure of Invention

In order to solve the problems, the invention aims to provide the phenolic resin with low sulfur content, less metal components and good low-temperature carbonization performance, and the preparation method and the application thereof.

The specific technical scheme of the invention is as follows:

1. a phenolic resin, wherein,

the pH value of the phenolic resin is 5.0-7.5, preferably 5.5-6.5, and more preferably 5.5-6.0;

the ash content of the phenolic resin is not more than 1.5%, preferably not more than 1.2%, more preferably not more than 1.0%.

2. The phenolic resin of item 1, wherein the phenolic resin has a elemental sulfur content of no greater than 1.0%, preferably no greater than 0.5%, more preferably no greater than 0.25%.

3. The phenolic resin of item 1 or 2, wherein it comprises, based on the total weight of the phenolic resin: 45 to 70 wt% of a polymer having an aromatic ring structure with 1 to 6 hydroxyl groups, 15 to 30 wt% of a polymer having an aromatic ring structure with 7 to 18 hydroxyl groups, and 0 to 10 wt% of a polymer having an aromatic ring structure with 19 to 45 hydroxyl groups.

4. The phenolic resin of any of claims 1-3, wherein the phenolic resin comprises about 0.2-1.5 wt% of a carbon forming agent, wherein the carbon forming agent is boron element, III_BGroup elements, IV_BGroup element, V_BGroup element, VI_BGroup elements, VII_BGroup element or VIII group element, and one or more compounds which are soluble in water or phenolic resin.

5. The phenol resin according to any one of items 1 to 4, wherein,

the phenolic resin is obtained by modifying acidic lignin;

the phenolic resin is preferably prepared by reacting reaction raw materials comprising a phenolic compound, an aldehyde compound, acidic lignin, a lignin solution and a carbon forming agent under the action of an alkaline catalyst;

the pH value of the acidic lignin is 3.0-5.5, and the ash content is not more than 0.8%.

6. The phenolic resin of item 5, wherein the acidic lignin is a copolymer of aromatic ring structure having a weight average molecular weight of 450 to 3500 g/mol.

7. The phenolic resin of claim 5 or 6, wherein the lignin solution is prepared from a reaction feedstock comprising phenol, dioxane, acidic lignin, and a polyhydroxy compound.

8. The phenolic resin of item 7, wherein the polyol is one of sucrose, glucose, and maltose.

9. The phenolic resin of any one of items 1 to 8, wherein the phenolic compound is selected from any one of phenol, cresol, resorcinol, and alkylphenol; preferably, the aldehyde compound is selected from any one of formaldehyde, acetaldehyde, butyraldehyde and benzaldehyde.

10. A method for producing the phenol resin according to any one of items 1 to 9,

preparing a lignin solution: heating phenol to melt, adding dioxane, acidic lignin and polyhydroxy compound into the melted phenol, heating to reflux, cooling, and adjusting pH value to neutrality to obtain lignin solution;

preparation of modified phenolic resin polymer: heating a container filled with a phenolic compound and a basic catalyst, adding an aldehyde compound, heating for reaction, adding a carbon forming agent, adding acidic lignin after the carbon forming agent is completely dissolved, continuing the reaction, cooling to room temperature, stopping the reaction, and distilling the obtained product under reduced pressure to obtain the modified phenolic resin polymer.

Preparing phenolic resin: and (3) heating the obtained modified phenolic resin polymer, adding the prepared lignin solution, reacting, and cooling to obtain the phenolic resin.

11. The method of item 10, wherein the lignin solution comprises, based on the total weight of the lignin solution: 10 to 40 wt% of dioxane, 20 to 40 wt% of phenol, 30 to 60 wt% of lignin, and 0 to 6 wt% of polyhydroxy compound.

12. The method according to item 10 or 11, wherein, in the step of preparing a modified phenolic resin polymer, the acidic lignin and the phenolic compound are used in a mass ratio of 0.1 to 0.32:1, preferably 0.15 to 0.25:1, and the carbon forming agent and the phenolic compound are used in a mass ratio of 0.005 to 0.05:1, preferably 0.01 to 0.02: 1;

preferably, the mass ratio of the lignin solution and the phenolic compound used in the step of preparing the phenolic resin is 0.2-0.5: 1, and preferably 0.22-0.32: 1.

13. The method according to any one of claims 10 to 12, wherein in the step of preparing the modified phenolic resin polymer, phenol tar is added.

14. The method of claim 13, wherein the phenol tar comprises: alpha-methylstyrene, p-xylene, cumene, phenol and acetophenone, the content of alpha-methylstyrene being the greatest.

15. The method according to item 13 or 14, wherein, in the step of preparing the modified phenolic resin polymer, the mass ratio of the phenol tar to the phenolic compound is 0.02 to 0.1:1, preferably 0.03 to 0.06: 1.

16. Use of the phenolic resin according to any one of claims 1 to 9 in the preparation of a prebaked anode; preferably in the preparation of binders for prebaked anodes.

ADVANTAGEOUS EFFECTS OF INVENTION

The phenolic resin prepared by the method has lower sulfur content, ash content and metal components; the pH value of the phenolic resin is acidic, and the resistivity of a carbonized product can be effectively reduced in the carbonization process due to different structures of lignin and the phenolic resin, so that the comprehensive performance is excellent; the carbon forming agent can form a fused compound with carbon at high temperature, and carbon is separated out as graphite crystals through rearrangement of atoms in the compound, so that the conductivity of the anode carbon block can be improved to a certain extent.

By using the preparation method of the phenolic resin, the phenolic resin with the structure, ash content, pH value and sulfur element content can be obtained by controlling the proportion of the content of each component in the raw materials, particularly controlling the content of the acidic lignin used in each step, and controlling the preparation processes such as the addition sequence of the raw materials, temperature and the like in the preparation process, the acidic lignin and the lignin solution are used as partial raw materials, the compatibility of the lignin and the phenolic resin is improved, the lignin with lower activity is embedded into a phenolic resin system as much as possible under the condition of ensuring low free phenol and low free aldehyde in the phenolic resin, and the stability of the phenolic resin is improved.

The phenolic resin prepared by adding the phenol tar is easier to be combined with anode aggregate when used as an anode binder, and has good adhesion.

The powder obtained after the phenolic resin of the invention is carbonized has low resistivity.

The phenolic resin can be used as a binder to replace asphalt to be used on a prebaked anode, and can effectively reduce pollution generated in roasting. The anode carbon block made of the carbon block as the adhesive has the advantages of high strength, large apparent density, high true density, low sulfur ion content, low resistivity and the like.

Detailed Description

The present invention will be described in detail below. In the following description and in the claims, the terms "include," "include," or "include" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description which follows is a preferred embodiment of the invention, but is made for the purpose of illustrating the general principles of the invention and not for the purpose of limiting the scope of the invention. The scope of the present invention is defined by the appended claims.

The phenolic resin provided by the invention has a pH value of 5.0-7.5, and the ash content is not more than 1.5%. Wherein, the pH and ash are commonly defined as understood by those skilled in the art and can be determined based on methods known to those skilled in the art. In a specific embodiment, the pH may be determined according to GB/T32364-.

The phenolic resin has low ash content, acidic pH value, high purity, good stability and excellent comprehensive performance.

In one embodiment, the phenolic resin has a sulfur content of no greater than 1.0%. The low sulfur content can improve the performance of the anode for aluminum. The sulfur content is the mass percentage of sulfur in the whole phenolic resin, and can be detected by methods known to those skilled in the art. In one embodiment, the sulfur content can be determined using the following method: placing a sample to be detected in a digestion tank, adding trace metal-grade nitric acid, preheating by using a heating plate, digesting in a microwave digestion instrument, taking out and cooling after digestion, metering volume to a volumetric flask by using ultrapure water, and carrying out quantitative analysis on sulfur by using an inductively coupled plasma emission spectrometer (ICP-AES).

In a preferred embodiment, the pH value of the phenolic resin is 5.2-6.2, the ash content is not more than 1.2%, and the sulfur content is not more than 0.5%.

In a preferred embodiment, the pH value of the phenolic resin is 5.7-5.9, the ash content is not more than 1.15%, and the sulfur content is not more than 0.25%.

In one embodiment, the phenolic resin of the present invention comprises, based on the total weight of the phenolic resin: 45 to 70 wt% of a polymer having an aromatic ring structure with 1 to 6 hydroxyl groups, 15 to 30 wt% of a polymer having an aromatic ring structure with 7 to 18 hydroxyl groups, and 0 to 10 wt% of a polymer having an aromatic ring structure with 19 to 45 hydroxyl groups.

The phenolic resin formed in the method has a hydroxyl-containing aromatic ring structural unit, the hydroxyl-containing aromatic ring structural unit is mainly derived from a prepolymer formed by phenol and formaldehyde and lignin, and can be represented by the following formula (I) (wherein R is hydroxymethyl or propyl, and R' is methoxy or methylene), and the molecular weight range of a polymer with a certain structure can be calculated; and (2) determining the molecular weight and the molecular weight distribution of the obtained phenolic resin by adopting gel permeation chromatography, analyzing the molecular weight distribution area of the phenolic resin polymer in a certain molecular weight range, calculating the ratio of the area to the whole distribution area, namely the percentage of the polymer in the molecular weight range to the total weight of the phenolic resin, and further determining the weight percentage of the polymer containing a certain number of aromatic ring structures with hydroxyl groups.

In one embodiment, the phenolic resin of the present invention comprises about 0.2 to 1.5 wt% of a carbon forming agent, based on the total weight of the phenolic resin, wherein the carbon forming agent is one or more of boron or a compound of a transition element that is soluble in water or the phenolic resin, and the transition element does not include any element other than I_BAnd II_BThe transition element can be iron, manganese, cobalt, titanium, nickel, molybdenum and other elements. The carbon-forming agent may be, for example, ferric ammonium citrate, manganese nitrate, cobalt sulfate, ferric chloride, nickel perchlorate, ammonium molybdate, nickel acetate, or the like. In this context, the total amount of the carbon-forming agent in the phenolic resin may be calculated based on the amount of the added carbon-forming agent and the total amount of all the reaction components forming the phenolic resin, or the amount of the selected carbon-forming agent in the phenolic resin may be measured based on methods known to those skilled in the art. The addition of the carbon forming agent can form a fused compound with carbon at high temperature, and carbon is separated out as graphite crystals through rearrangement of atoms in the compound, so that the conductivity of the anode can be improved to a certain extent.

In one embodiment, the phenolic resin is modified from acidic lignin by methods known to those skilled in the art.

In one embodiment, the phenolic resin is prepared by reacting a phenolic compound, an aldehyde compound, acidic lignin, a lignin solution and a carbon forming agent under the action of a basic catalyst; wherein the pH value of the acidic lignin as one of the raw materials is 3.0-5.5, and the ash content is not more than 0.8%; the acidic lignin is a copolymer with an aromatic ring structure and the weight average molecular weight of 450-3500 g/mol.

In a preferred embodiment, the pH value of the acidic lignin is 3.5-5, and the ash content is not more than 0.5%.

In this context, acidic lignin can be used as long as it meets the above-mentioned pH conditions and ash, and weight average molecular weight, and for example, commercially available lignin sulfate, lignin hydrochloride, lignin periodate, lignin phenolate, and the like can be used. The phenol lignin is lignin obtained by dissolving lignin in a woody material with a phenol-containing solution and then refining and separating the dissolved lignin, and the lignin contains a certain amount of phenolized lignin.

In a preferred embodiment, the phenolic resin is prepared by reacting a phenolic compound, an aldehyde compound, acidic lignin, a lignin solution, phenol tar and a modifier under the action of an alkaline catalyst. Wherein the phenolic compound can be phenol, cresol, cardanol, resorcinol, alkylphenol, xylenol, octylphenol, nonylphenol, tert-butylphenol, cashew nut oil, bisphenol A and the like, and the aldehyde compound can be formaldehyde, trioxymethylene, paraformaldehyde, acetaldehyde, paraldehyde, butyraldehyde, furfural, benzaldehyde and the like. The carbon of phenol tar is similar to the aggregate of prebaked anode, so that the phenolic resin prepared by adding phenol tar can be more easily combined with the anode aggregate when used as the anode binder, and the binding property is good.

In one embodiment, the lignin solution is prepared from phenol, dioxane, acidic lignin, and a polyol.

In a specific embodiment, the lignin solution comprises, based on the total weight of the lignin solution: 10 to 40 wt% of dioxane, 20 to 40 wt% of phenol, 30 to 60 wt% of lignin, and 0 to 6 wt% of polyhydroxy compound.

In one embodiment, the present invention provides a method for preparing a phenolic resin, comprising the steps of:

step one, preparing a lignin solution: heating phenol to be molten, adding dioxane, acidic lignin and polyhydroxy compound into the molten phenol, heating to reflux, cooling, and adjusting the pH value to be neutral to obtain a lignin solution;

step two, preparing a modified phenolic resin polymer: heating a container filled with a phenolic compound and a basic catalyst, adding an aldehyde compound, heating for reaction, adding a carbon forming agent, adding acidic lignin after the carbon forming agent is completely dissolved, continuing the reaction, cooling to room temperature, stopping the reaction, and distilling the obtained product under reduced pressure to obtain the modified phenolic resin polymer.

Step three, preparing phenolic resin: and (3) heating the obtained modified phenolic resin polymer, adding the prepared lignin solution, reacting, and cooling to obtain the phenolic resin.

In a specific embodiment, in the step one, the phenol may be heated to 30 to 85 ℃ to melt, and then dioxane, acidic lignin and a polyhydroxy compound are put into the melted phenol, heated to reflux, for example, reflux may be performed for 0.5 to 9 hours, and then cooled, and the pH value is adjusted to be neutral, so as to obtain the lignin solution.

In a specific embodiment, in the second step, the temperature of a container filled with the phenolic compound and the basic catalyst is raised to 50-110 ℃, the aldehyde compound is added, the heating reaction is carried out for 0.5-10 h, the carbon forming agent is added, after the carbon forming agent is completely dissolved, the acidic lignin is added, the reaction is continued for 0.5-8 h, the temperature is reduced to room temperature, the reaction is stopped, and the obtained product is subjected to reduced pressure distillation to obtain the modified phenolic resin polymer.

In a specific embodiment, in the third step, the modified phenolic resin polymer obtained in the second step is heated, the lignin solution prepared in the first step is added, and the mixture is cooled after reacting for 0.5-8 hours, so that the phenolic resin is obtained.

In a preferred embodiment, in step two, a modified phenolic resin polymer is prepared: heating a container filled with a phenolic compound and an alkaline catalyst to 55-105 ℃, adding the aldehyde compound, heating for reaction for 0.5-9 h, adding a carbon forming agent, wherein the carbon forming agent can be ferric ammonium citrate, manganese nitrate, cobalt sulfate, ferric chloride, nickel perchlorate, ammonium molybdate, nickel acetate and the like, adding acidic lignin after the carbon forming agent is completely dissolved, continuing to react for 0.8-7.5 h, cooling to room temperature, stopping the reaction, distilling the obtained product under reduced pressure, and adding phenol tar to obtain the modified phenolic resin polymer.

In a preferred embodiment, in step two, a modified phenolic resin polymer is prepared: heating a container filled with the phenolic compound and the basic catalyst to 55-105 ℃, for example, raising the temperature, adding the aldehyde compound, heating to react for 0.5-9 h, for example, adding the carbon forming agent, adding the acidic lignin and the phenol tar after the carbon forming agent is completely dissolved, continuing to react for 0.8-7.5 h, then lowering the temperature to room temperature, stopping the reaction, and distilling the obtained product under reduced pressure to obtain the modified phenolic resin polymer.

In one embodiment, the mass ratio of the phenol tar to the phenolic compound is 0.04-0.09: 1.

In one embodiment, the method of the present invention for preparing a phenolic resin comprises the steps of:

step one, preparing a lignin solution: heating phenol to 40-75 ℃ for melting, adding dioxane, acidic lignin and polyhydroxy compound into the melted phenol, heating to reflux for 1-8 hours, cooling, and adding alkaline solution to adjust the pH value to be neutral to obtain lignin solution;

step two, preparing a modified phenolic resin polymer: heating a container filled with a phenolic compound and a basic catalyst to 60-100 ℃, adding an aldehyde compound, heating for reaction for 1-8 hours, adding a carbon forming agent, adding acidic lignin after the carbon forming agent is completely dissolved, continuing to react for 0.5-6 hours, cooling to room temperature, stopping reaction, and distilling the obtained product under reduced pressure to obtain the modified phenolic resin polymer.

Step three, preparing phenolic resin: and (3) heating the modified phenolic resin polymer obtained in the step two, adding the lignin solution obtained in the step one, reacting for 0.5-6 h, and cooling to obtain the phenolic resin.

In one embodiment, in the method for preparing a phenolic resin, in the first step, the mass ratio of the dioxane to the phenol is 0.7-1: 1, the mass ratio of the acidic lignin to the phenol is 1-2.5: 1, and the mass ratio of the polyhydroxy compound to the phenol is 0-0.1: 1; in the second step, the mass ratio of the acidic lignin to the phenolic compound is 0.15-0.32: 1, and the mass ratio of the carbon forming agent to the phenolic compound is 0.01-0.04: 1; the mass ratio of the lignin solution to the phenolic compound used in the third step is 0.3-0.5: 1.

In one embodiment, in the method for preparing phenolic resin, according to the invention, in the first step, the pH value is adjusted to be neutral by adding an alkaline solution, so as to obtain the lignin solution; the alkaline solution is one or more of ammonia water, triethylamine and triethanolamine solution.

By using the preparation method of the phenolic resin, the proportion of the content of each component in the raw materials is controlled in the preparation process, particularly the content of the acidic lignin used in each step is controlled, the preparation processes such as the addition sequence of the raw materials and the temperature are controlled, the phenolic resin with the structure, the ash content, the pH value and the sulfur element content can be obtained, the obtained phenolic resin has high purity and good stability, the resistivity of the powder obtained after carbonization is low, and the anode carbon block made by using the phenolic resin as the adhesive has the advantages of high strength, large apparent density, high true density, low sulfur ion content, low resistivity and the like.

The following detailed description illustrates and describes embodiments of the present invention with reference to specific examples, but the following should not be construed as limiting the invention in any way.

Examples

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments.

The materials and reagents used in the examples were all commercially available unless otherwise specified.

Example 1

The method comprises the following steps: heating 50g of phenol to 55-60 ℃ for melting, adding 40g of dioxane, heating to 80-82 ℃, adding 90g of acidic lignin, wherein the pH of the acidic lignin is 4.3, the ash content is 0.76%, adding 5g of cane sugar after the acidic lignin is completely dissolved, heating to reflux, refluxing for 2h, cooling to 35-40 ℃, adding triethylamine to adjust the pH to be neutral, and obtaining a lignin solution.

Step two: putting 375g of phenol and sodium hydroxide into a reaction bottle, heating to 78-82 ℃, dropwise adding 573g of 37% formaldehyde, keeping the temperature for 3 hours, adding 2g of nickel acetate and 2g of boric acid, completely dissolving, adding 80g of acidic lignin and 20g of phenol tar, cooling to 40-50 ℃, and performing reduced pressure dehydration until the water content is 4-6% to obtain the modified phenolic resin polymer.

Step three: and (3) heating the obtained modified phenolic resin polymer to 50-60 ℃, adding 80g of lignin solution prepared in the step one, continuing to react for 3 hours, and cooling to obtain the phenolic resin.

Example 2

The method comprises the following steps: heating 55g of phenol to 55-60 ℃, adding 80g of dioxane, heating to 80-82 ℃, adding 130g of acidic lignin, wherein the pH of the acidic lignin is 4.8, the ash content is 0.63%, adding 5g of cane sugar after the acidic lignin is completely dissolved, heating to reflux, refluxing for 2h, cooling to 35-40 ℃, adding triethylamine to adjust the pH to be neutral, and obtaining a lignin solution.

Step two: adding 500g of phenol and sodium hydroxide into a reaction bottle, heating to 78-82 ℃, dropwise adding 37% of formaldehyde 724.5g, keeping the temperature constant for 3 hours, adding 6g of nickel acetate and 2g of boric acid, completely dissolving, adding 90g of acidic lignin and 27g of phenol tar, cooling to 40-50 ℃, and performing reduced pressure dehydration until the water content is 4-6% to obtain the modified phenolic resin polymer.

Step three: and (3) heating the obtained modified phenolic resin polymer to 50-60 ℃, adding 250g of lignin solution prepared in the step one, continuing to react for 4 hours, and cooling to obtain the phenolic resin.

Example 3

The method comprises the following steps: heating 50g of phenol to 55-60 ℃, adding 45g of dioxane, heating to 80-82 ℃, adding 130g of acidic lignin, wherein the pH of the acidic lignin is 5.1, the ash content is 0.45%, adding 5g of cane sugar after the acidic lignin is completely dissolved, heating to reflux, refluxing for 2h, cooling to 35-40 ℃, adding triethylamine to adjust the pH to be neutral, and obtaining a lignin solution.

Step two: adding 500g of phenol and sodium hydroxide into a reaction bottle, heating to 78-82 ℃, dropwise adding 37% formaldehyde 724.5g, keeping the temperature constant for 3 hours, adding 6g of nickel acetate and 2g of ferric ammonium oxalate after completely dissolving, adding 90g of acidic lignin and 20g of phenol tar, cooling to 40-50 ℃, and performing reduced pressure dehydration until the water content is 4-6% to obtain the modified phenolic resin polymer.

Step three: and (3) heating the obtained modified phenolic resin polymer to 50-60 ℃, adding 210g of lignin solution prepared in the step one, continuing to react for 4 hours, and cooling to obtain the phenolic resin.

Example 4

The method comprises the following steps: heating 50g of phenol to 55-60 ℃, adding 40g of dioxane, heating to 82-85 ℃, adding 90g of acidic lignin, wherein the pH of the acidic lignin is 3.9, the ash content is 0.51%, adding 5g of cane sugar after the acidic lignin is completely dissolved, heating to reflux, refluxing for 2.5h, cooling to 35-40 ℃, adding triethylamine to adjust the pH to be neutral, and obtaining a lignin solution.

Step two: putting 400g of phenol and sodium hydroxide into a reaction bottle, heating to 78-82 ℃, dropwise adding 543g of 37% formaldehyde, keeping the temperature for 3 hours, adding 2g of nickel acetate and 2g of boric acid, completely dissolving, adding 90g of acidic lignin, continuously reacting for 1.5 hours, cooling to 40-50 ℃, performing reduced pressure dehydration until the water content is 4-6%, and adding 15g of phenol tar to obtain the modified phenolic resin polymer.

Step three: and (3) heating the obtained modified phenolic resin polymer to 60-70 ℃, adding 136g of lignin solution prepared in the step one, continuing to react for 3 hours, and cooling to room temperature to obtain the phenolic resin.

Example 5

The method comprises the following steps: heating 50g of phenol to 55-60 ℃, adding 30g of dioxane, heating to 82-85 ℃, adding 120g of acidic lignin, wherein the pH of the acidic lignin is 5.3, the ash content is 0.62%, adding 5g of cane sugar after the acidic lignin is completely dissolved, heating to reflux, refluxing for 2.5h, cooling to 35-40 ℃, adding triethylamine to adjust the pH to be neutral, and obtaining a lignin solution.

Step two: putting 500g of phenol and sodium hydroxide into a reaction bottle, heating to 78-82 ℃, dropwise adding 664g of 37% formaldehyde, keeping the temperature constant for 3 hours, adding 6g of nickel acetate and 2g of boric acid after the nickel acetate and the boric acid are completely dissolved, adding 90g of acidic lignin, continuously reacting for 1.5 hours, cooling to 40-50 ℃, performing reduced pressure dehydration until the water content is 4-6%, and adding 35g of phenol tar to obtain the modified phenolic resin polymer.

And step three: and (3) heating the obtained modified phenolic resin polymer to 60-70 ℃, adding 55g of lignin solution prepared in the step one, continuing to react for 3 hours, and cooling to room temperature to obtain the phenolic resin.

Example 6

The method comprises the following steps: heating 50g of phenol to 55-60 ℃, adding 45g of dioxane, heating to 85-90 ℃, adding 130g of acidic lignin, wherein the pH value of the acidic lignin is 4.4, the ash content is 0.52%, adding 5g of cane sugar after the acidic lignin is completely dissolved, heating to reflux, refluxing for 3 hours, cooling to 35-40 ℃, adding ammonia water, and adjusting the pH value to be neutral to obtain a lignin solution.

Step two: putting 500g of phenol and sodium hydroxide into a reaction bottle, heating to 78-82 ℃, dropwise adding 37% formaldehyde 724.5g, keeping the temperature constant for 3 hours, adding 6g of nickel acetate and 2g of ferric ammonium oxalate, completely dissolving, adding 100g of the acidic lignin, continuously reacting for 1 hour, cooling to 40-50 ℃, performing reduced pressure dehydration until the water content is 4-6%, and adding 20g of phenol tar to obtain the modified phenolic resin polymer.

Step three: and (3) heating the obtained modified phenolic resin polymer to 60-70 ℃, adding 150g of lignin solution prepared in the step one, continuing to react for 4 hours, and cooling to room temperature to obtain the phenolic resin.

Example 7

The method comprises the following steps: heating 50g of phenol to 55-60 ℃, adding 45g of dioxane, heating to 85-90 ℃, adding 130g of acidic lignin, wherein the pH of the acidic lignin is 4.5, the ash content is 0.59%, after the acidic lignin is completely dissolved, adding 5g of sucrose, heating to reflux, refluxing for 3 hours, cooling to 35-40 ℃, adding ammonia water, and adjusting the pH to be neutral to obtain a lignin solution.

Step two: putting 500g of phenol and sodium hydroxide into a reaction bottle, heating to 78-82 ℃, dropwise adding 37% formaldehyde 724.5g, keeping the temperature constant for 3 hours, adding 6g of nickel acetate and 2g of ferric ammonium oxalate, completely dissolving, adding 120g of the acidic lignin, continuously reacting for 1 hour, cooling to 40-50 ℃, performing reduced pressure dehydration until the water content is 4-6%, and adding 20g of phenol tar to obtain the modified phenolic resin polymer.

Step three: and (3) heating the obtained modified phenolic resin polymer to 60-70 ℃, adding 130g of lignin solution prepared in the first step, continuing to react for 4 hours, and cooling to room temperature to obtain the phenolic resin.

Example 8

The method comprises the following steps: heating 50g of phenol to 55-60 ℃, adding 15g of dioxane, heating to 82-85 ℃, adding 175g of acidic lignin, wherein the pH value of the acidic lignin is 4.0, the ash content is 0.48%, after the acidic lignin is completely dissolved, adding 12.5g of cane sugar, heating to reflux, refluxing for 2.5h, cooling to 35-40 ℃, adding triethylamine to adjust the pH value to be neutral, and obtaining a lignin solution.

Step two: putting 400g of phenol and sodium hydroxide into a reaction bottle, heating to 78-82 ℃, dropwise adding 552g of 37% formaldehyde, keeping the temperature constant for 3 hours, adding 0.8g of nickel acetate and 0.8g of boric acid into the reaction bottle after the nickel acetate and the boric acid are completely dissolved, adding 160g of the acidic lignin, continuously reacting for 1.5 hours, cooling to 40-50 ℃, performing reduced pressure dehydration until the moisture content is 4-6%, and adding 48g of phenol tar to obtain the modified phenolic resin polymer.

Step three: and (3) heating the obtained modified phenolic resin polymer to 60-70 ℃, adding 240g of lignin solution prepared in the step one, continuing to react for 3 hours, and cooling to room temperature to obtain the phenolic resin.

Example 9

The method comprises the following steps: heating 50g of phenol to 55-60 ℃, adding 15g of dioxane, heating to 82-85 ℃, adding 200g of acidic lignin, wherein the pH value of the acidic lignin is 4.7, the ash content is 0.75%, adding 5g of cane sugar after the acidic lignin is completely dissolved, heating to reflux, refluxing for 2.5h, cooling to 35-40 ℃, adding triethylamine to adjust the pH value to be neutral, and obtaining a lignin solution.

Step two: putting 400g of phenol and sodium hydroxide into a reaction bottle, heating to 78-82 ℃, dropwise adding 533g of 37% formaldehyde, keeping the temperature constant for 3 hours, adding 2g of nickel acetate and 2g of boric acid into the reaction bottle after the nickel acetate and the boric acid are completely dissolved, adding 160g of acidic lignin, continuously reacting for 1.5 hours, cooling to 40-50 ℃, performing reduced pressure dehydration until the water content is 4-6%, and adding 15g of phenol tar to obtain the modified phenolic resin polymer.

Step three: and (3) heating the obtained modified phenolic resin polymer to 60-70 ℃, adding 84g of lignin solution prepared in the step one, continuing to react for 3 hours, and cooling to room temperature to obtain the phenolic resin.

TABLE 1 preparation Process conditions

The pH, ash content, and sulfur content of the phenolic resins prepared in examples 1 to 9 were measured, and the results are shown in table 2 below. Wherein the content of the first and second substances,

the pH value determination method comprises the following steps: GB/T32364-2015 method.

The ash content determination method comprises the following steps: GB/T9345.1-2008.

The method for measuring the sulfur content comprises the following steps: putting 0.1535g of sample into a digestion tank, adding 9mL of trace metal-grade nitric acid, preheating by a heating plate for 30min, digesting for 5, 10 and 20 min respectively at 120, 160 and 180 ℃ in a microwave digestion instrument, taking out after digestion, cooling, metering volume to a 100mL volumetric flask by using ultrapure water, and carrying out quantitative analysis on sulfur element by using an inductively coupled plasma emission spectroscopy (ICP-AES) instrument.

The formed phenolic resin has a hydroxyl-containing aromatic ring structural unit, the hydroxyl-containing aromatic ring structural unit is mainly derived from a prepolymer formed by phenol and formaldehyde and lignin, and can be represented by a formula (I) (wherein R is hydroxymethyl or propyl, and R' is methoxy or methylene), and the molecular weight range of a polymer with a certain structure can be calculated; and (2) determining the molecular weight and the molecular weight distribution of the obtained phenolic resin by adopting gel permeation chromatography, analyzing the molecular weight distribution area of the phenolic resin polymer in a certain molecular weight range, calculating the ratio of the area to the whole distribution area, namely the percentage of the polymer in the molecular weight range to the total weight of the phenolic resin, and further determining the weight percentage of the polymer containing a certain number of aromatic ring structures with hydroxyl groups.

Gel permeation chromatography detection conditions: tetrahydrofuran is used as a mobile phase, and polystyrene microspheres are used as a stationary phase. The flow rate of the mobile phase at the time of the test was 10ml/min, the temperature was 35 ℃, the test was performed on a Waters 2487 gel permeation chromatograph, and the contents in table 3 below were calculated based on the peak area of each characteristic peak shown in the chromatographic results.

TABLE 2

	pH value	Ash content (%)	Elemental sulfur content (%)
				Example 1	6.13	1.08	0.27
Example 2	6.01	1.02	0.28
				Example 3	6.24	1.13	0.31
Example 4	6.33	1.11	0.28
				Example 5	6.41	1.08	0.49
Example 6	6.27	1.05	0.37
				Example 7	5.83	0.76	0.25
Example 8	5.24	1.35	0.92
				Example 9	5.38	1.16	0.86

TABLE 3

Examples of the experiments

Experimental example 1

Resistivity test of powder after carbonization

Taking 15g of the phenolic resin of each of examples 1-9, putting the phenolic resin into an aluminum foil box, and curing by adopting the curing process in the following table 4:

TABLE 4

The cured resin was put into an atmosphere furnace, and carbonized by the carbonization process shown in table 5 below using nitrogen as a protective gas.

TABLE 5

The powder resistivity of the carbonized phenolic resins of examples 1 to 9 is shown in Table 6 below.

TABLE 6

Numbering	Test results (m omega cm)
		Example 1	35
Example 2	28
		Example 3	25
Example 4	31
		Example 5	22
Example 6	20
		Example 7	18
Example 8	51
		Example 9	45

Experimental example 2

Phenolic resin was used as a binder to prepare an anode for aluminum.

Samples 1 to 9

The following operations were carried out on the phenolic resins of examples 1 to 9:

(1) weighing 20 parts of petroleum coke with the thickness of 0-1 mm, 35 parts of petroleum coke with the thickness of 1-4 mm, 20 parts of petroleum coke with the thickness of 4-8 mm, 25 parts of petroleum coke with fine powder of 180 meshes and 14 parts of phenolic resin, and putting the mixture into a mixer to be uniformly mixed. And (3) placing the kneaded material in a specific die, and forming on a friction press or a vibration press.

(2) And (3) putting the prepared anode carbon block into an oven at 250 ℃, and preserving heat for at least 72 hours.

(3) And (3) putting the cured anode carbon block into a carbonization kiln, carrying out carbon-embedding carbonization treatment, heating to 1100 ℃ at the speed of 5 ℃/h, preserving the heat for 96h at the temperature of 1100 ℃, slowly cooling to room temperature, and taking out a sample for performance test.

And respectively obtaining 1-9 samples of the anode carbon block according to the operation.

Comparative sample 1

Uses asphalt as a bonding agent to manufacture a common anode carbon block,

(1) weighing 20 parts of petroleum coke with the thickness of 0-1 mm, 35 parts of petroleum coke with the thickness of 1-4 mm, 20 parts of petroleum coke with the thickness of 4-8 mm and 25 parts of petroleum coke with fine powder with the size of 180 meshes, uniformly mixing in a mixer, heating to the temperature of 120-. And (3) placing the kneaded material in a specific die, and forming on a friction press or a vibration press, wherein the temperature is kept to be not lower than 100 ℃ in the forming process.

(2) And (3) putting the cured anode carbon block into a carbonization kiln, carrying out carbon-embedding carbonization treatment, heating to 1100 ℃ at the speed of 5 ℃/h, preserving the heat for 96h at the temperature of 1100 ℃, slowly cooling to room temperature, and taking out a sample for performance test.

The results of the performance tests of samples 1 to 9 and comparative sample 1 are shown in table 7 below.

TABLE 7

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.