阅读说明：本技术 一种低双酚类化合物含量的热塑性酚醛树脂及其制备方法和应用 (Thermoplastic phenolic resin with low content of bisphenol compounds, and preparation method and application thereof ) 是由 井新利 张萍 王淑娟 张晓婷 于 2019-10-11 设计创作，主要内容包括：本发明公开了一种低双酚类化合物含量的热塑性酚醛树脂及其制备方法和应用,包括：将热塑性酚醛树脂和萃取剂混合,获得混合物A；在惰性气氛下,于萃取剂回流温度下搅拌混合物A预设时间,并在预设温度以上将上清液倒出,获得萃取后的热塑性酚醛树脂；重复萃取若干次；减压蒸馏去除萃取剂,获得低双酚类化合物含量的热塑性酚醛树脂。本发明的制备方法,用于制备极低双酚类化合物含量的热塑性酚醛树脂,该制备方法得到的热塑性酚醛树脂兼具良好的工艺性和优异的热稳定性,采用少量固化剂交联该树脂就可以拥有较好的热稳定性和力学性能。(The invention discloses a thermoplastic phenolic resin with low content of bisphenol compounds, a preparation method and application thereof, comprising the following steps: mixing thermoplastic phenolic resin and an extracting agent to obtain a mixture A; stirring the mixture A for a preset time at the reflux temperature of the extracting agent in an inert atmosphere, and pouring out the supernatant above the preset temperature to obtain the extracted thermoplastic phenolic resin; extracting repeatedly for several times; and distilling under reduced pressure to remove the extractant, thereby obtaining the thermoplastic phenolic resin with low content of bisphenol compounds. The preparation method is used for preparing the thermoplastic phenolic resin with extremely low content of the bisphenol compounds, the thermoplastic phenolic resin obtained by the preparation method has good manufacturability and excellent thermal stability, and the resin can have better thermal stability and mechanical property by adopting a small amount of curing agent to crosslink.)

1. A preparation method of a thermoplastic phenolic resin with low content of bisphenol compounds is characterized by comprising the following steps:

step 1, mixing thermoplastic phenolic resin and an extracting agent to obtain a mixture A; wherein the mass ratio of the extracting agent to the thermoplastic phenolic resin in the mixture A is at least 1: 2;

step 2, stirring the mixture A obtained in the step 1 at the reflux temperature of the extracting agent in the step 1 for a preset time in an inert atmosphere, pouring out the supernatant above the preset temperature to obtain the extracted thermoplastic phenolic resin, and skipping to the step 3; pouring out the supernatant above a preset temperature to prevent bisphenol compounds from being separated out;

step 3, taking the extracted thermoplastic phenolic resin obtained in the step 2 as the thermoplastic phenolic resin in the step 1, and repeating the step 1 and the step 2 for a plurality of times; and distilling under reduced pressure to remove the extractant, thereby obtaining the thermoplastic phenolic resin with low content of bisphenol compounds.

2. The method for preparing the thermoplastic phenolic resin with low content of the bisphenol compounds as claimed in claim 1, wherein the preparation method adopted by the thermoplastic phenolic resin in the step 1 comprises the following steps:

step 1.1, dissolving a preset amount of phenolic compound, aldehyde compound and acid catalyst in water to obtain a mixture B; wherein the molar ratio of the phenolic compound to the aldehyde compound in the mixture B is 1: (0.85-1.3);

step 1.2, stirring, heating and refluxing the mixture B obtained in the step 1.1, cooling and standing, and taking out upper-layer water to obtain a mixture C;

step 1.3, distilling the mixture C in vacuum and heating; reacting for a preset time at the temperature of 110-130 ℃ under the pressure of 6-14 kPa to obtain a thermoplastic phenolic resin containing a bisphenol compound in a larger mass percentage and phenol in a certain mass percentage; wherein the mass percent of the bisphenol compounds in the obtained thermoplastic phenolic resin is 5-15%, and the mass percent of the phenol is 0.5-5%.

3. The method for preparing the thermoplastic phenolic resin with low content of the bisphenol compounds as claimed in claim 2, wherein in step 1.1, the amount of the acidic catalyst is 0.01-20 parts per 5-160 parts of the phenol compounds and the amount of water is 200-1000 mL.

4. The method for preparing the thermoplastic phenolic resin with low content of the bisphenol compounds in claim 2, wherein in step 1.1,

the phenolic compound is one or more of phenol, bisphenol A, bisphenol F, naphthol, p-hydroxymethyl phenol, o-hydroxymethyl phenol, tris-hydroxymethyl phenol, 2-hydroxybenzyl alcohol, catechol, resorcinol, hydroquinone, p-cresol, o-cresol, m-cresol, 1, 2-dihydroxybenzene, 1, 4-dihydroxybenzene, 1,3, 5-benzenetriol, cardanol, o-phenylphenol, 5-p-hydroxyphenyl-1-3 alcohol, propyl phenol, butyl phenol, amyl phenol, heptyl phenol, octyl phenol, nonyl phenol and decyl phenol;

the aldehyde compound is one or more of formaldehyde, paraformaldehyde, trioxymethylene, acetaldehyde and furfural;

the acidic catalyst is one or more of oxalic acid, sulfuric acid, p-toluenesulfonic acid or phosphoric acid.

5. The method for preparing the thermoplastic phenolic resin with low content of the bisphenol compounds in the claim 1, wherein in the step 3, the repetition times of the step 1 and the step 2 are 3-10 times.

6. The method for preparing the thermoplastic phenolic resin with low content of the bisphenol compounds as claimed in claim 1, wherein in the step 1, the mass ratio of the thermoplastic phenolic resin to the extracting agent is 1: (0.5 to 4).

7. The method for preparing the thermoplastic phenolic resin with low content of the bisphenol compounds as claimed in claim 1, wherein the mass percentage of the bisphenol compounds in the obtained thermoplastic phenolic resin with low content of the bisphenol compounds in the step 3 is less than 1%.

8. The method for preparing the thermoplastic phenolic resin with low content of the bisphenol compounds in the claim 1, wherein the extractant in the step 1 is toluene, xylene, acetonitrile-water, tetrahydrofuran-water, methanol-water, ethanol-water or isopropanol-water.

9. A thermoplastic phenol resin having a low content of bisphenols, which is prepared by the preparation method according to any one of claims 1 to 8;

the mass percent of the bisphenol compounds in the thermoplastic phenolic resin with low content of the bisphenol compounds is less than 1 percent, and the mass percent of the phenol is less than 0.5 percent.

10. Use of the low bisphenol content phenol-formaldehyde thermoplastic resin of claim 9 for the production of molding powders, phenolic glues, phenolic fibers, corrosion protection materials, thermal insulation materials, fire protection materials or ablation resistance materials.

Technical Field

The invention belongs to the technical field of new materials, and particularly relates to a thermoplastic phenolic resin with low content of bisphenol compounds, and a preparation method and application thereof.

Background

Phenolic Resin (PR) is the earliest synthetic polymer material for human beings, and compared with other polymer materials, PR has the characteristics of low raw material and production cost, excellent electrical property, good heat resistance and chemical corrosion resistance, good product dimensional stability and the like. Due to the characteristics of excellent ablation resistance, high quality retention rate and the like, PR and the composite material thereof play an important role in the application of instantaneous high temperature resistance and ablation resistance structural materials and are ablation-resistant composite material matrix resins which are used in large quantities at the earliest and at present. With the continuous and deep exploration of the universe by human beings, the work tasks carried by the spacecraft are more and more complex, the work environment of the spacecraft is more and more rigorous, and the performance of the material is more strictly required, but the existing PR has lower thermal decomposition temperature and lower quality retention rate after cracking and is difficult to meet the application requirements.

In order to improve the thermal stability of PR, modifying conventional PR to obtain a resin with good properties is a research hotspot in recent years. PR is modified by a plurality of methods, and can be divided into three types, namely organic modification, inorganic modification and nano material modification according to the characteristics of modified substances. These modification methods all achieve the object of improving heat resistance by introducing other compounds into PR, for example, introducing arylboronic acid into a phenol resin to obtain a thermoplastic resin having excellent heat properties; however, these methods do not pay attention to the influence of the composition of PR itself on its thermal stability, and greatly limit the improvement of PR heat resistance.

The present invention is directed to a phenolic resin synthesized under acidic and excessive phenolic compounds, generally having a linear structure, mainly consisting of phenol rings and methylene groups, and hardly containing benzylic hydroxyl groups, and requiring the addition of a curing agent such as paraformaldehyde or hexamethylenetetramine for curing, which is a main subject of the present invention, since phenol and formaldehyde polycondensation reaction has a gradual reaction characteristic, the molecular weight of the synthesized phenolic resin is widely distributed and contains a large amount of monophenol compounds (such as raw phenol) and bisphenol compounds, it has been long recognized that free monophenol in the industrially synthesized phenolic resin adversely affects the properties of the final product, while the influence of bisphenol compounds has been neglected.

In summary, although the thermal stability of the phenolic resin obtained by the conventional synthesis or modification method is improved to some extent, the influence of the bisphenol compound, which is the root cause of low thermal stability, is ignored, and a new thermoplastic phenolic resin with low content of the bisphenol compound and a preparation method thereof are needed.

Disclosure of Invention

The invention aims to provide a thermoplastic phenolic resin with low content of bisphenol compounds, a preparation method and application thereof, so as to solve one or more technical problems.

In order to achieve the purpose, the invention adopts the following technical scheme:

the preparation method of the thermoplastic phenolic resin with low bisphenol compound content comprises the following steps:

step 1, mixing thermoplastic phenolic resin and an extracting agent to obtain a mixture A; wherein the mass ratio of the extracting agent to the thermoplastic phenolic resin in the mixture A is at least 1: 2;

step 2, stirring the mixture A obtained in the step 1 at the reflux temperature of the extracting agent in the step 1 for a preset time in an inert atmosphere, pouring out the supernatant above the preset temperature to obtain the extracted thermoplastic phenolic resin, and skipping to the step 3; pouring out the supernatant above a preset temperature to prevent bisphenol compounds from being separated out;

step 3, taking the extracted thermoplastic phenolic resin obtained in the step 2 as the thermoplastic phenolic resin in the step 1, and repeating the step 1 and the step 2 for a plurality of times; and distilling under reduced pressure to remove the extractant, thereby obtaining the thermoplastic phenolic resin with low content of bisphenol compounds.

The invention further improves the method for preparing the thermoplastic phenolic resin in the step 1, which comprises the following steps:

step 1.1, dissolving a preset amount of phenolic compound, aldehyde compound and acid catalyst in water to obtain a mixture B; wherein the molar ratio of the phenolic compound to the aldehyde compound in the mixture B is 1: (0.85-1.3);

step 1.2, stirring, heating and refluxing the mixture B obtained in the step 1.1, cooling and standing, and taking out upper-layer water to obtain a mixture C;

step 1.3, distilling the mixture C in vacuum and heating; reacting for a preset time at the temperature of 110-130 ℃ under the pressure of 6-14 kPa to obtain a thermoplastic phenolic resin containing a bisphenol compound in a larger mass percentage and phenol in a certain mass percentage; wherein the mass percent of the bisphenol compounds in the obtained thermoplastic phenolic resin is 5-15%, and the mass percent of the phenol is 0.5-5%.

The invention is further improved in that in the step 1.1, in terms of mole parts, every 5-160 parts of phenolic compounds correspond to 0.01-20 parts of acidic catalyst and 200-1000 mL of water.

A further improvement of the present invention is that the phenolic compound in step 1.1 is one or more of phenol, bisphenol a, bisphenol F, naphthol, p-hydroxymethylphenol, o-hydroxymethylphenol, tris-hydroxymethylphenol, 2-hydroxybenzyl alcohol, catechol, resorcinol, hydroquinone, p-cresol, o-cresol, m-cresol, 1, 2-dihydroxybenzene, 1, 4-dihydroxybenzene, 1,3, 5-benzenetriol, cardanol, catechol, 5-p-hydroxyphenyl-1-3 alcohol, propylphenol, butylphenol, pentylphenol, heptylphenol, octylphenol, nonylphenol, and decylphenol; the aldehyde compound in the step 1.1 is one or more of formaldehyde, paraformaldehyde, trioxymethylene, acetaldehyde and furfural; the acidic catalyst in step 1.1 is one or more of oxalic acid, sulfuric acid, p-toluenesulfonic acid or phosphoric acid.

The invention is further improved in that in the step 3, the times of repeating the step 1 and the step 2 are 3-10 times.

The invention is further improved in that in the step 1, the mass ratio of the thermoplastic phenolic resin to the extracting agent is 1: (0.5 to 4).

The invention is further improved in that in the step 3, the mass percentage of the bisphenol compounds in the thermoplastic phenolic resin with low content of the bisphenol compounds is less than 1 percent.

The invention is further improved in that the extractant in the step 1 is toluene, xylene, acetonitrile-water, tetrahydrofuran-water, methanol-water, ethanol-water or isopropanol-water.

The thermoplastic phenolic resin with low content of bisphenol compounds is prepared by any one of the preparation methods;

the mass percentage of the bisphenol compounds in the thermoplastic phenolic resin with low content of the bisphenol compounds is less than 1 percent, and the mass percentage of the phenol content is less than 0.5 percent.

The application of the thermoplastic phenolic resin with low content of the bisphenol compounds is used for manufacturing molding powder, phenolic glue, phenolic fiber, anticorrosive materials, heat insulation materials, refractory materials or ablation-resistant materials.

Compared with the prior art, the invention has the following beneficial effects:

the preparation method is used for preparing the thermoplastic phenolic resin with low content of the bisphenol compounds, the thermoplastic phenolic resin obtained by the preparation method has good manufacturability and excellent thermal stability, and the resin can have better thermal stability and mechanical property by adopting a small amount of curing agent to crosslink. In the preparation method, bisphenol compounds in the traditional thermoplastic phenolic resin are removed by adopting an extraction method, the structure of the phenolic resin is optimized, and the thermoplastic phenolic resin with high glass transition temperature and high thermal decomposition temperature is obtained; compared with the traditional thermoplastic phenolic resin, the high-crosslinking-density cured resin can be obtained by curing the thermoplastic phenolic resin with low content of bisphenol compounds by adopting a small amount of curing agent, and has good thermal stability; the resin-based composite material prepared by compounding the thermoplastic phenolic resin with glass fiber, carbon fiber and the like has better manufacturability, mechanical property and ablation property. In conclusion, the method can radically improve the performance of NR by partially or completely removing bisphenol micromolecular compounds in NR, and has important application value; meanwhile, the obtained bisphenol compound is an important medical intermediate and has higher additional value. Therefore, the invention provides a preparation method with important value.

The thermoplastic phenolic resin with low bisphenol compound content has good manufacturability and excellent thermal stability, and can have better thermal stability and mechanical property by adopting a small amount of curing agent to crosslink the thermoplastic phenolic resin.

Experimental results show that the thermal weight loss of the thermoplastic phenolic resin with low content of the bisphenol compounds is obviously reduced at 300 ℃ (nitrogen atmosphere, 10 ℃/min: is reduced from 9.19% to 5.79%), the temperature corresponding to 5% mass loss is obviously increased (nitrogen atmosphere, 10 ℃/min: is increased from 256.0 ℃ to 270.5 ℃), and the char forming rate of the resin cured by 4phr HMTA is also obviously improved (nitrogen atmosphere, 800 ℃: is increased from 48.74% to 55.78%).

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; it is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

FIG. 1 is a liquid chromatogram of a phenol novolak resin having a low content of bisphenols according to the invention and a comparative example described in example 1 of the invention;

FIG. 2 is a schematic representation of the differential scanning calorimetry curves of the comparative example described in example 1 of the present invention and a phenol novolac resin of the present invention having a low bisphenol content;

FIG. 3 is a graphical representation of the thermogravimetric curves of the phenolic novolak resins of the present invention and the comparative example described in example 1 of the present invention having a low bisphenol compound content.

Detailed Description

In order to make the purpose, technical effect and technical solution of the embodiments of the present invention clearer, the following clearly and completely describes the technical solution of the embodiments of the present invention with reference to the drawings in the embodiments of the present invention; it is to be understood that the described embodiments are only some of the embodiments of the present invention. Other embodiments, which can be derived by one of ordinary skill in the art from the disclosed embodiments without inventive faculty, are intended to be within the scope of the invention.

The preparation method of the thermoplastic phenolic resin with low bisphenol compound content in the embodiment of the invention specifically comprises the following steps:

the first step is the synthesis of phenolic resin:

adding a phenolic compound, an aldehyde compound, water and an acid catalyst into a reaction kettle to obtain a mixture; specifically, the catalyst comprises, by mole, 5-160 parts of a phenolic compound and 0.01-20 parts of an acidic catalyst, wherein the molar ratio of the phenolic compound to an aldehyde compound is 1: (0.85-1.3), and then dissolving in 200-1000 mL of water.

Stirring and heating the mixture, and refluxing for 0.5-4 h. And (3) after the mixture is cooled, standing for 0.5-2h, siphoning out upper water, changing condensation into vacuum distillation, heating, and raising the temperature of the reaction kettle to 110-130 ℃ under the pressure of 6-14 kPa until the preset requirement is met or the preset reaction time is kept, so that the thermoplastic phenolic resin containing a large mass percentage of bisphenol compounds and a certain mass percentage of phenol is obtained. Specifically, the mass percent of the bisphenol compound is 5-15%, and the mass percent of the phenol is 0.5-5%.

Preferably, the phenolic compound in the first step is one or more of phenol, bisphenol a, bisphenol F, naphthol, p-hydroxymethylphenol, o-hydroxymethylphenol, tris-hydroxymethylphenol, 2-hydroxybenzyl alcohol, catechol, resorcinol, hydroquinone, p-cresol, o-cresol, m-cresol, 1, 2-benzenediol, 1, 4-benzenediol, 1,3, 5-benzenetriol, cardanol, catechol, 5-p-hydroxyphenyl-1-3 alcohol, propylphenol, butylphenol, pentylphenol, heptylphenol, octylphenol, nonylphenol and decylphenol.

Preferably, the aldehyde compound is one or a mixture of more of formaldehyde solution, paraformaldehyde, trioxymethylene, acetaldehyde and furfural.

Preferably, the acidic catalyst used in the synthesis of the phenolic novolac resin is a mixture of one or more of oxalic acid, sulfuric acid, p-toluenesulfonic acid or phosphoric acid.

The second step is solvent extraction:

selecting and mixing an extracting agent with the thermoplastic phenolic resin prepared in the first step; wherein the mass ratio of the extracting agent to the thermoplastic phenolic resin is at least 1: 2; preferably, the mass ratio of the thermoplastic phenolic resin to the extracting agent is 1: (0.5 to 4).

Stirring for 0.2-2h at the reflux temperature of the extracting agent in an inert atmosphere, and pouring out the supernatant (which can be more than 80 ℃) when the bisphenol compounds are hot before being separated out, so as to finish the primary extraction process; and (3) repeating the extraction process for 3-10 times in order to further reduce the content of the bisphenol compounds, and then carrying out reduced pressure distillation to remove the extractant, thereby obtaining the thermoplastic phenolic resin with low content of the bisphenol compounds. The content of the bisphenol compounds in the thermoplastic phenolic resin with low content of the bisphenol compounds is less than 1 percent, and the content of the phenol is less than 0.5 percent.

Specifically, 50-200 g of the thermoplastic phenolic resin obtained in the first step and the extracting agent are added into a four-neck flask provided with a stirring paddle and a condensing tube.

Preferably, the second solvent extraction step is independent and can be carried out on any phenolic novolac resin containing a certain amount of bisphenols.

Preferably, the extractant used in the extraction process may be toluene or xylene.

Preferably, the extractant used in the extraction process can be acetonitrile-water, tetrahydrofuran-water, methanol-water, ethanol-water or isopropanol-water, and the like, wherein the volume ratio of the organic solvent to the water in the mixed extractant is 1: (5-15).

The structural formula of the precipitated bisphenol compound includes, but is not limited to, the following structural formula, and is a mixture of one or more of the following structural formulas:

in the method, the bisphenol compound obtained by extraction can be separated and purified for secondary use.

The thermoplastic phenolic resin with low content of bisphenol compounds prepared by the invention can be used for manufacturing molding powder, phenolic glue, phenolic fibers, anti-corrosion materials, heat insulation materials, refractory materials or ablation-resistant materials.

In summary, in order to fundamentally solve the problems of poor manufacturability, thermal stability and mechanical property of resin matrix composite materials of the traditional thermoplastic phenolic resin and expand the application range of the thermoplastic phenolic resin, the invention provides a preparation method of the thermoplastic phenolic resin with low content of bisphenol compounds, the phenolic resin obtained by the preparation method has good manufacturability and excellent thermal stability, and the resin can have better thermal stability and mechanical property by adopting a small amount of curing agent to crosslink, the invention can fundamentally improve the property of NR by partially or completely removing bisphenol micromolecule compounds in NR, and has important application value, meanwhile, the obtained bisphenol compounds are important medical intermediates and have higher added value, therefore, the invention provides a method with important value, the embodiment of the invention has the advantages that ① the invention adopts an extraction method to remove the bisphenol compounds in the traditional thermoplastic phenolic resin, optimizes the structure of the phenolic resin, obtains a thermoplastic phenolic resin with high glass transition temperature and high thermal decomposition temperature, and has better thermal stability compared with the traditional thermoplastic phenolic resin, ② adopts a small amount of phenolic resin to cure the phenolic resin with low content, and the phenolic resin matrix composite materials with good thermal stability and good thermal property of the carbon fiber.