阅读说明：本技术 一种环保型改性苯并噁嗪树脂及其制备方法 (Environment-friendly modified benzoxazine resin and preparation method thereof ) 是由 田谋锋 姚亚琳 尹群皎 贾晨辉 刘红影 于 2021-11-22 设计创作，主要内容包括：本发明涉及树脂技术领域,尤其是涉及一种环保型改性苯并噁嗪树脂及其制备方法,通过加入溶剂、六氯环三磷腈和乙酰氨基苯酚、催化剂搅拌溶解,加热反应获得第一固体中间产物,将第一固体中间产物加入溶剂中,加入催化剂,加热反应,得到第二固体中间产物,再将第二固体中间产物加入溶剂中,加入甲醛和4-马来酰亚胺基苯酚,加热反应,获得环保型改性苯并噁嗪树脂；本发明还提供了一种环保型改性苯并噁嗪树脂,包括：六氯环三磷腈、对乙酰氨基苯酚、4-马来酰亚胺基苯酚和甲醛、催化剂、溶剂；获得的改性苯并噁嗪树脂结构规整、分子活性低,固化后的树脂耐热性能强,残碳率高,力学性能优异,阻燃效果佳。(The invention relates to the technical field of resin, in particular to an environment-friendly modified benzoxazine resin and a preparation method thereof, wherein a solvent, hexachlorocyclotriphosphazene, acetaminophenol and a catalyst are added and stirred for dissolving, a first solid intermediate product is obtained by heating reaction, the first solid intermediate product is added into the solvent, the catalyst is added, heating reaction is carried out to obtain a second solid intermediate product, then the second solid intermediate product is added into the solvent, formaldehyde and 4-maleimide phenol are added, and heating reaction is carried out to obtain the environment-friendly modified benzoxazine resin; the invention also provides an environment-friendly modified benzoxazine resin, which comprises the following components: hexachlorocyclotriphosphazene, acetaminophen, 4-maleimidophenol, formaldehyde, a catalyst and a solvent; the obtained modified benzoxazine resin has regular structure, low molecular activity, strong heat resistance of the cured resin, high carbon residue rate, excellent mechanical property and good flame retardant effect.)

1. The preparation method of the environment-friendly modified benzoxazine resin is characterized by comprising the following steps:

s1, adding a solvent, hexachlorocyclotriphosphazene and acetaminophenol, stirring and dissolving, adding a catalyst, heating for the first time, performing a first reflux reaction, cooling for the first time, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent, stirring and dissolving, adding a catalyst, heating for the second time, performing reflux reaction for the second time, cooling for the second time, washing with water, and drying to obtain a second solid intermediate product;

and S3, adding the second solid intermediate product into a solvent, stirring and dissolving, adding formaldehyde and 4-maleimide phenol, heating for the third time, carrying out reflux reaction for the third time, cooling for the third time after the reflux is finished, and drying in vacuum to obtain the environment-friendly modified benzoxazine resin.

2. The preparation method of the environment-friendly modified benzoxazine resin according to claim 1, wherein the first heating temperature is 57-65 ℃, the first reflux reaction time is 24-36h, and the first temperature is reduced to 30-35 ℃; the second heating temperature is 65-75 ℃, the second reflux reaction time is 12-24h, and the first temperature is reduced to 30-35 ℃; the third heating temperature is 67-75 ℃, the third reflux reaction time is 12-24h, and the third temperature is reduced to 30-35 ℃.

3. The method for preparing environment-friendly modified benzoxazine resin according to claim 1, wherein the solvent in step S1 is acetone; the solvent in step S2 is methanol; the solvent in step S3 is tetrahydrofuran.

4. The method for preparing environment-friendly modified benzoxazine resin according to claim 1, wherein step S1 uses at least one catalyst selected from potassium carbonate, sodium carbonate and calcium carbonate; in step S2, the catalyst is at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, and barium hydroxide.

5. The method for preparing environment-friendly modified benzoxazine resin according to claim 1, wherein the reaction is performed in a reaction kettle.

6. An environment-friendly modified benzoxazine resin obtained based on the preparation method of the environment-friendly modified benzoxazine resin according to any one of claims 1 to 5, comprising: 25-40 parts of hexachlorocyclotriphosphazene, 60-75 parts of acetaminophen, 70-85 parts of 4-maleimide aminophenol and 80-110 parts of formaldehyde.

7. The environment-friendly modified benzoxazine resin according to claim 6, comprising in parts by mass: 28-35 parts of hexachlorocyclotriphosphazene, 65-70 parts of acetaminophen, 75-82 parts of 4-maleimide aminophenol, a catalyst and a solvent.

8. The environment-friendly modified benzoxazine resin according to claim 7, wherein the catalyst comprises the following components in parts by weight: one of potassium carbonate, sodium carbonate, calcium carbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide and barium hydroxide.

9. The environment-friendly modified benzoxazine resin according to claim 8, wherein the solvent is a solvent comprising: acetone, methanol, and tetrahydrofuran.

10. The environmentally friendly modified benzoxazine resin according to claim 9, wherein the catalyst comprises: 3-5 parts of potassium carbonate and 0.2-0.4 part of sodium hydroxide.

Technical Field

The invention relates to the technical field of resin, in particular to environment-friendly modified benzoxazine resin and a preparation method thereof.

Background

Polymeric flame retardants are used in a wide variety of applications, such as advanced composite matrices, copper clad laminates, coatings for printed circuit boards and barrier materials, semiconductor packaging and manufacturing. Halide-containing additives in flame retardants are effective in showing higher flame retardant potential, but they release highly toxic gases and form potential carcinogens when burned, e.g. some conventional flame retardants migrate to the surface and evaporate, becoming potential pollutants of the environment which can have a long-term impact on human health and are potentially problematic flame retardant polymers even if not burned.

In order to meet the growing demand for flame retardants and the development requirements for environmental friendliness, there is an urgent need to design and use halogen-free and environmentally friendly flame retardants. Benzoxazines exhibit excellent physicochemical and mechanical properties such as hydrophobicity, cure shrinkage close to zero, high thermal stability, high char yield, good chemical resistance, high mechanical strength, excellent flame retardancy. The phosphorus-containing compound does not generate toxic substances under the conditions of combustion and normal temperature, and has excellent flame retardant effect, so that the flame retardant synthesized by the benzoxazine modified by the phosphorus-containing compound has very wide prospect.

In an article published by Maqingke et al (Sichuan chemical industry, vol.21, No. 5, 2018, pages 4-9) and entitled "synthesis of phosphazene benzoxazine and performance research thereof", hexachlorocyclotriphosphazene, phenol, p-hydroxyanisole, aniline and formaldehyde are proposed to synthesize three phosphazene benzoxazines, wherein the polymerization starting temperature of the three compounds is lower than 200 ℃, the decomposition temperature is higher than 330 ℃, the carbon residue rate at 800 ℃ is higher than 55%, and the combustion grade reaches V-0 grade. Phosphazene groups are introduced into a benzoxazine structure to develop different types of phosphazene benzoxazines, the phosphazene benzoxazines are superior to traditional benzoxazines in the aspects of flame retardance, thermal stability and the like, but the prepared resin is low in molecular regularity, non-concentrated in molecular weight distribution, large in molecular activity, low in carbon residue rate of the cured benzoxazine resin, and unstable in preparation method.

Therefore, in order to solve the above problems, the present invention urgently needs to provide an environment-friendly modified benzoxazine resin and a preparation method thereof.

Disclosure of Invention

The invention aims to provide an environment-friendly modified benzoxazine resin and a preparation method thereof, wherein the modified benzoxazine resin with regular structure and low molecular activity is obtained by improving the raw material components, the proportion and the process control, and the resin obtained after the modified benzoxazine resin is cured has strong heat resistance, high carbon residue rate, excellent mechanical property and good flame retardant effect.

The invention provides a preparation method of environment-friendly modified benzoxazine resin, which comprises the following steps:

s1, adding a solvent, hexachlorocyclotriphosphazene and acetaminophenol, stirring and dissolving, adding a catalyst, heating for the first time, performing a first reflux reaction, cooling for the first time, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent, stirring and dissolving, adding a catalyst, heating for the second time, performing reflux reaction for the second time, cooling for the second time, washing with water, and drying to obtain a second solid intermediate product;

and S3, adding the second solid intermediate product into a solvent, stirring and dissolving, adding formaldehyde and 4-maleimide phenol, heating for the third time, carrying out reflux reaction for the third time, cooling for the third time after the reflux is finished, and drying in vacuum to obtain the environment-friendly modified benzoxazine resin.

Preferably, the first heating temperature is 57-65 ℃, the first reflux reaction time is 24-36h, and the first temperature is reduced to 30-35 ℃; the second heating temperature is 65-75 ℃, the second reflux reaction time is 12-24h, and the first temperature is reduced to 30-35 ℃; the third heating temperature is 67-75 ℃, the third reflux reaction time is 12-24h, and the third temperature is reduced to 30-35 ℃.

Preferably, the solvent in step S1 is acetone; the solvent in step S2 is methanol; the solvent in step S3 is tetrahydrofuran.

Preferably, the catalyst used in step S1 is at least one of potassium carbonate, sodium carbonate and calcium carbonate; in step S2, the catalyst is at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, and barium hydroxide.

Preferably, the reaction is carried out in a reaction kettle.

The invention also provides an environment-friendly modified benzoxazine resin obtained by the preparation method of the environment-friendly modified benzoxazine resin, which comprises the following components in parts by weight: 25-40 parts of hexachlorocyclotriphosphazene, 60-75 parts of acetaminophen, 70-85 parts of 4-maleimide aminophenol and 80-110 parts of formaldehyde.

Preferably, the composite material comprises the following components in parts by weight: 28-35 parts of hexachlorocyclotriphosphazene, 65-70 parts of acetaminophen, 75-82 parts of 4-maleimide aminophenol, a catalyst and a solvent.

Preferably, the catalyst comprises the following components in parts by mass: one of potassium carbonate, sodium carbonate, calcium carbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide and barium hydroxide.

Preferably, the solvent is a solvent comprising: acetone, methanol, and tetrahydrofuran.

Preferably, the catalyst comprises: 3-5 parts of potassium carbonate and 0.2-0.4 part of sodium hydroxide.

Compared with the prior art, the environment-friendly modified benzoxazine resin and the preparation method thereof provided by the invention have the following advantages:

1. according to the environment-friendly modified benzoxazine resin and the preparation method thereof, rigid six-membered rings contained in hexachlorocyclotriphosphazene are very stable, so that the benzoxazine resin has the characteristics of acid resistance, alkali resistance and high temperature resistance, the hexachlorocyclotriphosphazene contains multi-arm high-reactivity P-Cl bonds, chemical substitution is easy to occur to obtain a phosphazene derivative, the molecular design flexibility is high, and the preparation method is very suitable for preparing a flame retardant; the phenolic hydroxyl in the acetaminophen can perform substitution reaction with multi-arm high-reactivity P-Cl bonds in hexachlorocyclotriphosphazene to generate a stable multi-substituted phosphazene compound; in addition, acetaminophen is acylated to prevent the reaction between amino and P-Cl bond and to raise the controllability of molecular structure; 4-maleimide group phenol contains maleimide group, and the group contains C = O bond and C-N bond, so that the group has better heat resistance, the heat resistance of the product can be improved, the group is cured at high temperature without release of small molecules, carbon-carbon double bonds are opened, the crosslinking degree of resin is improved, and the thermal stability and the mechanical property of the resin are further improved; the reaction of the 4-maleimide aminophenol and the amino can play a role in end capping, reduce the reaction activity of the product and improve the trial period of the product. The maleimide group contains a carbon-carbon double bond, other groups or molecules can be introduced, the design flexibility of the molecules is further improved, the synthesized phosphazene modified benzoxazine resin has good heat resistance and excellent flame retardance, and the mechanical property of the modified benzoxazine resin obtained after curing is greatly improved.

2. In the preparation process of the environment-friendly modified benzoxazine resin, the reaction is roughly divided into three stages, reactants in each stage are different and different catalysts need to be added, potassium carbonate is added in step S1, the reaction system is alkalescent, a P-Cl bond with high reaction activity of hexachlorocyclotriphosphazene is catalytically activated and generates similar hydrolysis reaction, only phenolic hydroxyl in the reaction system can participate in the reaction to generate a P-O bond, H & lt + & gt is neutralized by the potassium carbonate, hydrochloric acid generated by continuous reaction of hexachlorocyclotriphosphazene and acetamidophenol is neutralized by the potassium carbonate to promote the reaction to continuously proceed towards the direction of a generated product, in addition, in order to prevent the acetamido from being hydrolyzed in a strong alkali solution, the substitution reaction of the amino and hexachlorocyclotriphosphazene is reduced; step S2, adding sodium hydroxide to combine with acetylamino on the first solid intermediate product to generate amino to provide reactive group for the next reaction; step S3 is a cyclization reaction of amino, phenolic hydroxyl and formaldehyde to generate a six-membered ring structure of the benzoxazine, the reaction can spontaneously move towards the cyclization direction after being heated, no additional catalyst is needed, four monomers are added according to the sequence provided by the method name and are separately mixed, so that the contact reaction among different reactants during the reaction is facilitated, the molecular structure of the benzoxazine resin is improved to be regular, and the quality stability of the modified benzoxazine resin is facilitated.

3. In the preparation process of the environment-friendly modified benzoxazine resin, the flame-retardant core is phosphazene, and excessive p-acetaminophenol is added in step S1, so that the utilization rate of hexachlorocyclotriphosphazene is improved, and hexa-substituted phosphazene is generated more; in the three reaction stages, the solvent and the raw materials are stirred uniformly, and then the catalyst is added, so that different reactants are in full contact, and the molecular regularity of the product is improved; and step S3, adding excessive formaldehyde and 4-maleimide phenol to generate more benzoxazine six-membered rings, improving the molecular regularity of the resin, reducing the activity of the resin and improving the thermal stability of the resin.

4. The preparation process provided by the invention is divided into three stages, each stage is subjected to reflux reaction in different solvents, and the conversion rate of each step of reaction can be improved; step S1 is longer than the reflux time of step S2 and step S3, the conversion rate of phosphazene can be improved, on the other hand, potassium carbonate is weaker in alkalinity and slower in catalytic rate, and the reaction time is prolonged to ensure that phosphazene is converted into hexa-substituted phosphazene; in the step S1, the catalyst potassium carbonate with weak alkalinity is selected as the catalyst, so that the catalytic efficiency can be ensured; step S2 needs to hydrolyze acetamido and improve catalytic efficiency, and selects common strong alkali sodium hydroxide to better improve economic benefit in preparation process.

5. According to the environment-friendly modified benzoxazine resin and the preparation method thereof, the obtained environment-friendly modified benzoxazine resin has the advantages of high molecular regularity, low molecular activity, strong heat resistance of the cured resin, high carbon residue rate, excellent mechanical property and good flame retardant effect.

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 will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a flow chart of a synthetic reaction of the phosphazene benzoxazine resin in the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example one

In the embodiment, the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, and the environment-friendly modified benzoxazine resin comprises the following components in parts by weight: 35 parts of hexachlorocyclotriphosphazene, 70 parts of acetaminophen, 70 parts of 4-maleimidophenol and 90 parts of formaldehyde; the catalyst comprises the following components in parts by weight: 4 parts of potassium carbonate and 0.2 part of sodium hydroxide; the solvent is acetone, methanol, tetrahydrofuran.

The method specifically comprises the following steps:

s1, adding 35 parts of solvent acetone, hexachlorocyclotriphosphazene and 70 parts of paracetamol into a reaction kettle, stirring and fully dissolving, adding 4 parts of catalyst potassium carbonate, heating for the first time, heating to 60 ℃ until the solution boils, carrying out a first reflux reaction for 24 hours, finishing the reflux reaction, cooling for the first time to 30 ℃, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent methanol, stirring and dissolving, adding 0.2 part of catalyst sodium hydroxide, heating for the second time, heating to 70 ℃ for boiling, carrying out reflux reaction for the second time, wherein the reflux reaction time is 12 hours, after the reflux reaction is finished, cooling for the second time, cooling to 30 ℃, washing, and drying to obtain a second solid intermediate product;

s3, adding the second solid intermediate product into a solvent tetrahydrofuran, stirring and dissolving, adding 90 parts of formaldehyde and 70 parts of 4-maleimide phenol, heating for the third time, boiling until the temperature is 70 ℃, performing reflux reaction for the third time, wherein the reflux reaction time is 12 hours, finishing reflux, cooling for the third time, cooling to 30 ℃, and performing vacuum drying to obtain the environment-friendly modified benzoxazine resin.

Comparative example 1

In the embodiment, the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, and the environment-friendly modified benzoxazine resin comprises the following components in parts by weight: 35 parts of hexachlorocyclotriphosphazene, 70 parts of p-aminophenol, 70 parts of 4-maleimide aminophenol and 90 parts of formaldehyde; the catalyst comprises the following components in parts by weight: 4 parts of potassium carbonate and 0.2 part of sodium hydroxide; the solvent is acetone, methanol, tetrahydrofuran.

The method specifically comprises the following steps:

s1, adding 35 parts of solvent acetone, hexachlorocyclotriphosphazene and 70 parts of paracetamol into a reaction kettle, stirring and fully dissolving, adding 4 parts of catalyst potassium carbonate, heating for the first time, heating to 60 ℃ until the solution boils, carrying out a first reflux reaction for 24 hours, finishing the reflux reaction, cooling for the first time to 30 ℃, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent methanol, stirring and dissolving, adding 0.2 part of catalyst sodium hydroxide, heating for the second time, heating to 70 ℃ for boiling, carrying out reflux reaction for the second time, wherein the reflux reaction time is 12 hours, after the reflux reaction is finished, cooling for the second time, cooling to 30 ℃, washing, and drying to obtain a second solid intermediate product;

s3, adding the second solid intermediate product into a solvent tetrahydrofuran, stirring and dissolving, adding 90 parts of formaldehyde and 70 parts of 4-maleimide phenol, heating for the third time, heating to 70 ℃ for boiling, carrying out reflux reaction for the third time, wherein the reflux reaction time is 12 hours, finishing reflux, cooling for the third time, cooling to 30 ℃, and carrying out vacuum drying to obtain the benzoxazine resin.

Comparative example No. two

In the embodiment, the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, and the environment-friendly modified benzoxazine resin comprises the following components in parts by weight: 35 parts of hexachlorocyclotriphosphazene, 70 parts of p-aminophenol, 70 parts of phenol and 90 parts of formaldehyde; the catalyst comprises the following components in parts by weight: 4 parts of potassium carbonate and 0.2 part of sodium hydroxide; the solvent is acetone, methanol, tetrahydrofuran.

The method specifically comprises the following steps:

s1, adding 35 parts of solvent acetone, hexachlorocyclotriphosphazene and 70 parts of paracetamol into a reaction kettle, stirring and fully dissolving, adding 4 parts of catalyst potassium carbonate, heating for the first time, heating to 60 ℃ until the solution boils, carrying out a first reflux reaction for 24 hours, finishing the reflux reaction, cooling for the first time to 30 ℃, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent methanol, stirring and dissolving, adding 0.2 part of catalyst sodium hydroxide, heating for the second time, heating to 70 ℃ for boiling, carrying out reflux reaction for the second time, wherein the reflux reaction time is 12 hours, after the reflux reaction is finished, cooling for the second time, cooling to 30 ℃, washing, and drying to obtain a second solid intermediate product;

s3, adding the second solid intermediate product into a solvent tetrahydrofuran, stirring and dissolving, adding 90 parts of formaldehyde and 70 parts of phenol, heating for the third time, heating to 70 ℃ for boiling, carrying out reflux reaction for the third time, wherein the reflux reaction time is 12 hours, after the reflux is finished, cooling for the third time, cooling to 30 ℃, and carrying out vacuum drying to obtain the benzoxazine resin.

Comparative example No. three

In the embodiment, the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, and the environment-friendly modified benzoxazine resin comprises the following components in parts by weight: 35 parts of hexaphenoxycyclotriphosphazene, 70 parts of p-aminophenol, 70 parts of phenol and 90 parts of formaldehyde; the catalyst comprises the following components in parts by weight: 4 parts of potassium carbonate and 0.2 part of sodium hydroxide; the solvent is acetone, methanol, tetrahydrofuran.

The method specifically comprises the following steps:

s1, adding 35 parts of solvent acetone, 35 parts of hexaphenoxycyclotriphosphazene and 70 parts of acetaminophen into a reaction kettle, stirring and fully stirring for dissolving, adding 4 parts of catalyst potassium carbonate, heating for the first time, heating to 60 ℃ until the solution boils, carrying out a first reflux reaction for 24 hours, cooling to 30 ℃ after the reflux reaction is finished, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent methanol, stirring and dissolving, adding 0.2 part of catalyst sodium hydroxide, heating for the second time, heating to 70 ℃ for boiling, carrying out reflux reaction for the second time, wherein the reflux reaction time is 12 hours, after the reflux reaction is finished, cooling for the second time, cooling to 30 ℃, washing, and drying to obtain a second solid intermediate product;

s3, adding the second solid intermediate product into a solvent tetrahydrofuran, stirring and dissolving, adding 90 parts of formaldehyde and 70 parts of phenol, heating for the third time, heating to 70 ℃ for boiling, carrying out reflux reaction for the third time, wherein the reflux reaction time is 12 hours, after the reflux is finished, cooling for the third time, cooling to 30 ℃, and carrying out vacuum drying to obtain the benzoxazine resin.

Example two

In the embodiment, the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, and the environment-friendly modified benzoxazine resin comprises the following components in parts by weight: 25 parts of hexachlorocyclotriphosphazene, 60 parts of acetaminophen, 75 parts of 4-maleimidophenol and 80 parts of formaldehyde; the catalyst comprises the following components in parts by weight: 4 parts of potassium carbonate and 0.2 part of sodium hydroxide; the solvent is acetone, methanol, tetrahydrofuran.

The method specifically comprises the following steps:

s1, adding 25 parts of solvent acetone, 25 parts of hexachlorocyclotriphosphazene and 60 parts of acetaminophen into a reaction kettle, stirring and fully stirring for dissolving, adding 4 parts of catalyst potassium carbonate, heating for the first time, heating to 57 ℃ for boiling, carrying out reflux reaction for the first time, wherein the reflux reaction time is 28 hours, cooling to 35 ℃ for the first time after the reflux reaction is finished, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent methanol, stirring and dissolving, adding 0.2 part of catalyst sodium hydroxide, heating for the second time, heating to 65 ℃ for boiling, carrying out reflux reaction for the second time, wherein the reflux reaction time is 18 hours, after the reflux reaction is finished, cooling for the second time, cooling to 35 ℃, washing, and drying to obtain a second solid intermediate product;

s3, adding the second solid intermediate product into solvent tetrahydrofuran, stirring and dissolving, adding 80 parts of formaldehyde and 75 parts of 4-maleimide phenol, heating for the third time, boiling to 67 ℃, performing reflux reaction for the third time, wherein the reflux reaction time is 18 hours, finishing reflux, cooling for the third time, cooling to 35 ℃, and performing vacuum drying to obtain the environment-friendly modified benzoxazine resin.

EXAMPLE III

In the embodiment, the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, and the environment-friendly modified benzoxazine resin comprises the following components in parts by weight: 40 parts of hexachlorocyclotriphosphazene, 75 parts of acetaminophen, 80 parts of 4-maleimidophenol and 100 parts of formaldehyde; the catalyst comprises the following components in parts by weight: 4 parts of potassium carbonate and 0.2 part of sodium hydroxide; the solvent is acetone, methanol, tetrahydrofuran.

The method specifically comprises the following steps:

s1, adding 40 parts of solvent acetone, hexachlorocyclotriphosphazene and 75 parts of acetaminophen into a reaction kettle, stirring and fully stirring for dissolving, adding 4 parts of catalyst potassium carbonate, heating for the first time, heating to 65 ℃ for boiling the solution, carrying out reflux reaction for the first time, wherein the reflux reaction time is 36 hours, cooling to 34 ℃ for the first time after the reflux reaction is finished, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent methanol, stirring and dissolving, adding 0.2 part of catalyst sodium hydroxide, heating for the second time, heating to boiling at 75 ℃, carrying out reflux reaction for the second time, wherein the reflux reaction time is 24 hours, after the reflux reaction is finished, cooling for the second time, cooling to 33 ℃, washing, and drying to obtain a second solid intermediate product;

s3, adding the second solid intermediate product into tetrahydrofuran serving as a solvent, stirring and dissolving, adding 100 parts of formaldehyde and 80 parts of 4-maleimide phenol, heating for the third time, boiling until the temperature is 75 ℃, performing reflux reaction for the third time, wherein the reflux reaction time is 24 hours, finishing reflux, cooling for the third time, cooling to 33 ℃, and performing vacuum drying to obtain the environment-friendly modified benzoxazine resin.

Example four

In the embodiment, the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, and the environment-friendly modified benzoxazine resin comprises the following components in parts by weight: 38 parts of hexachlorocyclotriphosphazene, 72 parts of acetaminophen, 85 parts of 4-maleimidophenol and 110 parts of formaldehyde; the catalyst comprises the following components in parts by weight: 4 parts of potassium carbonate and 0.2 part of sodium hydroxide; the solvent is acetone, methanol, tetrahydrofuran.

The method specifically comprises the following steps:

s1, adding 38 parts of solvent acetone, hexachlorocyclotriphosphazene and 72 parts of p-acetamidophenol into a reaction kettle, stirring and fully dissolving, adding 4 parts of catalyst potassium carbonate, heating for the first time, heating to 63 ℃ to boil the solution, carrying out reflux reaction for the first time, wherein the reflux reaction time is 30 hours, after the reflux reaction is finished, cooling for the first time to 32 ℃, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent methanol, stirring and dissolving, adding 0.2 part of catalyst sodium hydroxide, heating for the second time, heating to 68 ℃ for boiling, carrying out reflux reaction for the second time, wherein the reflux reaction time is 20 hours, after the reflux reaction is finished, cooling for the second time, cooling to 32 ℃, washing, and drying to obtain a second solid intermediate product;

s3, adding the second solid intermediate product into a solvent tetrahydrofuran, stirring and dissolving, adding 80 parts of formaldehyde and 85 parts of 4-maleimide phenol, heating for the third time, heating to 72 ℃ for boiling, carrying out reflux reaction for the third time, wherein the reflux reaction time is 20 hours, finishing reflux, cooling for the third time, cooling to 32 ℃, and carrying out vacuum drying to obtain the environment-friendly modified benzoxazine resin.

EXAMPLE five

In the embodiment, the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, and the environment-friendly modified benzoxazine resin comprises the following components in parts by weight: 35 parts of hexachlorocyclotriphosphazene, 70 parts of acetaminophen, 70 parts of 4-maleimidophenol and 90 parts of formaldehyde; the catalyst comprises the following components in parts by weight: 0.4 part of sodium hydroxide; the solvent is acetone, methanol, tetrahydrofuran.

The method specifically comprises the following steps:

s1, adding 35 parts of solvent acetone, hexachlorocyclotriphosphazene and 70 parts of acetaminophen into a reaction kettle, stirring and fully dissolving, adding 0.2 part of catalyst sodium hydroxide, heating for the first time, heating to 60 ℃ to boil the solution, carrying out a first reflux reaction for 24 hours, cooling to 30 ℃ after the reflux reaction is finished, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent methanol, stirring and dissolving, adding 0.2 part of catalyst sodium hydroxide, heating for the second time, heating to 70 ℃ for boiling, carrying out reflux reaction for the second time, wherein the reflux reaction time is 12 hours, after the reflux reaction is finished, cooling for the second time, cooling to 30 ℃, washing, and drying to obtain a second solid intermediate product;

s3, adding the second solid intermediate product into a solvent tetrahydrofuran, stirring and dissolving, adding 90 parts of formaldehyde and 70 parts of 4-maleimide phenol, heating for the third time, boiling until the temperature is 70 ℃, performing reflux reaction for the third time, wherein the reflux reaction time is 12 hours, finishing reflux, cooling for the third time, cooling to 30 ℃, and performing vacuum drying to obtain the environment-friendly modified benzoxazine resin.

EXAMPLE six

In the embodiment, the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, and the environment-friendly modified benzoxazine resin comprises the following components in parts by weight: 35 parts of hexachlorocyclotriphosphazene, 70 parts of acetaminophen, 70 parts of 4-maleimidophenol and 90 parts of formaldehyde; the catalyst comprises the following components in parts by weight: 8 parts of potassium carbonate; the solvent is acetone, methanol, tetrahydrofuran.

The method specifically comprises the following steps:

s1, adding 35 parts of solvent acetone, hexachlorocyclotriphosphazene and 70 parts of paracetamol into a reaction kettle, stirring and fully dissolving, adding 4 parts of catalyst potassium carbonate, heating for the first time, heating to 60 ℃ until the solution boils, carrying out a first reflux reaction for 24 hours, finishing the reflux reaction, cooling for the first time to 30 ℃, washing with water, and drying to obtain a first solid intermediate product;

s2, adding the first solid intermediate product into a solvent methanol, stirring and dissolving, adding 4 parts of catalyst potassium carbonate, heating for the second time, heating to 70 ℃ for boiling, carrying out reflux reaction for the second time, wherein the reflux reaction time is 12 hours, after the reflux reaction is finished, cooling for the second time, cooling to 30 ℃, washing with water, and drying to obtain a second solid intermediate product;

s3, adding the second solid intermediate product into a solvent tetrahydrofuran, stirring and dissolving, adding 90 parts of formaldehyde and 70 parts of 4-maleimide phenol, heating for the third time, boiling until the temperature is 70 ℃, performing reflux reaction for the third time, wherein the reflux reaction time is 12 hours, finishing reflux, cooling for the third time, cooling to 30 ℃, and performing vacuum drying to obtain the environment-friendly modified benzoxazine resin.

EXAMPLE seven

In the embodiment, the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, and the environment-friendly modified benzoxazine resin comprises the following components in parts by weight: 35 parts of hexachlorocyclotriphosphazene, 70 parts of acetaminophen, 70 parts of 4-maleimidophenol and 90 parts of formaldehyde; the catalyst comprises the following components in parts by weight: 8 parts of potassium carbonate; the solvent is acetone, methanol, tetrahydrofuran.

The method specifically comprises the following steps:

adding 35 parts of solvent acetone, 35 parts of hexachlorocyclotriphosphazene and 70 parts of acetaminophen into a reaction kettle, stirring, adding 4 parts of catalyst potassium carbonate, 0.2 part of methanol, 0.2 part of sodium hydroxide, 90 parts of tetrahydrofuran, 90 parts of formaldehyde and 70 parts of 4-maleimide phenol, fully stirring and dissolving, heating to 70 ℃ for boiling in one step, carrying out reflux reaction for 48 hours, finishing the reflux reaction, and carrying out vacuum drying to obtain the environment-friendly modified benzoxazine resin.

Comparative example No. four

The Chengdu science is suitable for the bisphenol A benzoxazine produced by high molecular science and technology limited.

The embodiment of the invention provides an environment-friendly modified benzoxazine resin and a preparation method thereof, wherein the first embodiment and the fourth embodiment are mainly characterized in that the environment-friendly modified benzoxazine resin is obtained by adopting different raw materials, mass part ratios and a preparation method for adjusting process parameter ratios; the fifth embodiment is different from the first embodiment in that the catalyst used in the fifth embodiment is sodium hydroxide; in the sixth example, potassium carbonate was used as the catalyst; the seventh embodiment adopts a one-step heating and heat preservation reaction;

the difference between the first comparative example and the first example is that the benzoxazine resin is obtained by using p-aminophenol, namely, without adding acetaminophenol under the same other preparation process conditions; the difference between the second comparative example and the first example is that the benzoxazine resin is obtained by using phenol, namely 4-maleimide phenol is not added, and other preparation process conditions are the same; the difference between the third comparative example and the first example is that hexaphenoxycyclotriphosphazene is adopted, namely, the benzoxazine resin is obtained under the condition that the conditions of other preparation processes are the same without adding hexachlorocyclotriphosphazene; comparative example four commercially available bisphenol a benzoxazine was used.

Test method

The environment-friendly modified benzoxazine resin prepared in the above example and the benzoxazine resin obtained in the comparative example were placed on a thermal weightlessness-instrument, and the temperature was raised from 25 ℃ to 800 ℃ at a temperature-raising rate of 10 ℃/min to obtain the resin, and the carbon residue rate, the combustion grade, and the impact strength and the tensile strength were measured, and the test results are shown in the following table:

table one test results

Test item	Residual carbon ratio (%)	Grade of combustion	Tensile Strength (MPa)	Flexural Strength (MPa)
					Example one	55.7	V-0	38.8	97.2
Example two	56.2	V-0	39.4	99.1
					EXAMPLE III	59.5	V-0	40.5	103.7
Example four	59.2	V-0	42.9	110.2
					EXAMPLE five	58.6	V-0	41.5	106.9
EXAMPLE six	58.3	V-0	36.3	89.8
					EXAMPLE seven	55.4	V-0	48.7	94.6
Comparative example 1	54.7	V-0	34.5	85.5
					Comparative example No. two	55.3	V-0	36.6	90.1
Comparative example No. three	56.7	V-0	39.1	98.6
					Comparative example No. four	51.3	V-0	32.6	80.8

As shown in the reaction scheme of fig. 1, hexachlorocyclotriphosphazene reacts with acetaminophen in step S1 to obtain a first solid intermediate product, a second solid intermediate product in step S2, and an environmentally friendly modified benzoxazine resin in step S2.

As can be seen from the reaction flow of fig. 1, the rigid six-membered ring contained in hexachlorocyclotriphosphazene is very stable, and can enable benzoxazine resin to have acid resistance, alkali resistance and high temperature resistance, the hexachlorocyclotriphosphazene contains multi-arm high-reactivity P-Cl bond, and is easy to generate chemical substitution to obtain phosphazene derivative, the molecular design flexibility is high, and the preparation method is very suitable for preparing flame retardant; the phenolic hydroxyl in the acetaminophen can perform substitution reaction with multi-arm high-reactivity P-Cl bonds in hexachlorocyclotriphosphazene to generate a stable multi-substituted phosphazene compound; in addition, acetaminophen is acylated to prevent the reaction between amino and P-Cl bond and to raise the controllability of molecular structure; 4-maleimide group phenol contains maleimide group, and the group contains C = O bond and C-N bond, so that the group has better heat resistance, the heat resistance of the product can be improved, the group is cured at high temperature without release of small molecules, carbon-carbon double bonds are opened, the crosslinking degree of resin is improved, and the thermal stability and the mechanical property of the resin are further improved; the reaction of the 4-maleimide aminophenol and the amino can play a role in end capping, reduce the reaction activity of the product and improve the trial period of the product. The maleimide group contains a carbon-carbon double bond, other groups or molecules can be introduced, the design flexibility of the molecules is further improved, the synthesized phosphazene modified benzoxazine resin has good heat resistance and excellent flame retardance, and the mechanical property of the modified benzoxazine resin obtained after curing is greatly improved.

In the preparation process of the environment-friendly modified benzoxazine resin, the reaction is roughly divided into three stages, reactants in each stage are different and different catalysts need to be added, potassium carbonate is added in step S1, the reaction system is alkalescent, a P-Cl bond with high reaction activity of hexachlorocyclotriphosphazene is catalytically activated and generates similar hydrolysis reaction, only phenolic hydroxyl in the reaction system can participate in the reaction to generate a P-O bond, H & lt + & gt is neutralized by the potassium carbonate, hydrochloric acid generated by continuous reaction of hexachlorocyclotriphosphazene and acetamidophenol is neutralized by the potassium carbonate to promote the reaction to continuously proceed towards the direction of a generated product, in addition, in order to prevent the acetamido from being hydrolyzed in a strong alkali solution, the substitution reaction of the amino and hexachlorocyclotriphosphazene is reduced; step S2, adding sodium hydroxide to combine with acetylamino on the first solid intermediate product to generate amino to provide reactive group for the next reaction; step S3 is a cyclization reaction of amino, phenolic hydroxyl and formaldehyde to generate a six-membered ring structure of the benzoxazine, the reaction can spontaneously move towards the cyclization direction after being heated, no additional catalyst is needed, four monomers are added according to the sequence provided by the method name and are separately mixed, so that the contact reaction among different reactants during the reaction is facilitated, the molecular structure of the benzoxazine resin is improved to be regular, and the quality stability of the modified benzoxazine resin is facilitated.

In the preparation process of the environment-friendly modified benzoxazine resin, the flame-retardant core is phosphazene, and excessive p-acetaminophenol is added in step S1, so that the utilization rate of hexachlorocyclotriphosphazene is improved, and hexa-substituted phosphazene is generated more; in the three reaction stages, the solvent and the raw materials are stirred uniformly, and then the catalyst is added, so that different reactants are in full contact, and the molecular regularity of the product is improved; and step S3, adding excessive formaldehyde and 4-maleimide phenol to generate more benzoxazine six-membered rings, improving the molecular regularity of the resin, reducing the activity of the resin and improving the thermal stability of the resin.

The preparation process provided by the invention is divided into three stages, each stage is subjected to reflux reaction in different solvents, and the conversion rate of each step of reaction can be improved; step S1 is longer than the reflux time of step S2 and step S3, the conversion rate of phosphazene can be improved, on the other hand, potassium carbonate is weaker in alkalinity and slower in catalytic rate, and the reaction time is prolonged to ensure that phosphazene is converted into hexa-substituted phosphazene; in the step S1, the catalyst potassium carbonate with weak alkalinity is selected as the catalyst, so that the catalytic efficiency can be ensured; step S2 needs to hydrolyze acetamido and improve catalytic efficiency, and selects common strong alkali sodium hydroxide to better improve economic benefit in preparation process.

As can be seen from the table one, the selection and the proportion of each raw material are screened, the preparation method is improved, and compared with the benzoxazine resin obtained by the conventional preparation method at present and the common benzoxazine resin in the market, the environment-friendly modified benzoxazine resin prepared by the preparation method of the invention has higher tensile strength and bending strength than the benzoxazine resin obtained by the comparative example; in the embodiment, the carbon residue rate of the environment-friendly modified benzoxazine resin is higher than that of the benzoxazine resin obtained in the comparative example; the environment-friendly modified benzoxazine resin has high molecular regularity, low molecular activity, strong heat resistance of the cured resin, high carbon residue rate, excellent mechanical property and good flame retardant effect.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.