CN110283289B

CN110283289B - Preparation method and application of phosphorus-containing benzoxazine resin with high flame retardance

Info

Publication number: CN110283289B
Application number: CN201910661271.4A
Authority: CN
Inventors: 马瑞
Original assignee: Shanghai Ruiyi Chemical Technology Co ltd
Current assignee: Shanghai Ruiyi Chemical Technology Co ltd
Priority date: 2019-07-22
Filing date: 2019-07-22
Publication date: 2022-07-01
Anticipated expiration: 2039-07-22
Also published as: CN110283289A

Abstract

A preparation method of high flame-retardant phosphorus-containing benzoxazine resin comprises the steps of uniformly mixing a phosphorus-containing bisphenol intermediate, primary amine and an aldehyde compound in an organic solvent, and then adding an amine catalyst to react to synthesize the phosphorus-containing benzoxazine resin; the chemical structural formula of the phosphorus-containing benzoxazine resin is shown as a formula I:

Description

Preparation method and application of phosphorus-containing benzoxazine resin with high flame retardance

Technical Field

The invention relates to the technical field of preparation of benzoxazine resin, in particular to a preparation method and application of phosphorus-containing benzoxazine resin with high flame retardance.

Background

The benzoxazine is subjected to ring-opening polymerization under the action of heating or a catalyst to generate polybenzoxazine which contains nitrogen and is similar to a phenolic resin net structure, so that the benzoxazine is also named as a novel phenolic resin. Benzoxazine resin is widely applied to a large number of industrial products, such as high-temperature resistant composite materials, high-performance copper clad laminates, high-quality plastic packaging materials and the like. It can also be compounded with other resins or additives (catalyst, toughening agent, etc.) to further improve the performance; the benzoxazine resin has better performance than the traditional phenolic resin and epoxy resin, has moderate price and cost, and can play a role in some middle-high-end applications in the future. The compatibility of the benzoxazine resin with other resins can also be compounded with other resins to increase the heat resistance of the material and improve the functions of dimensional stability and the like of the material.

The current synthesis methods commonly used for benzoxazine resin include a solution method, a solvent-free method, a suspension method and the like. The solution method is that reactants are dissolved in a proper solvent and are uniformly mixed, then the temperature is raised for reaction, and the solvent is removed after the reaction polymerization is finished. The disadvantages are that a large amount of toluene solvent is needed, the solvent can cause cancer, and the cost is high when a large amount of the solvent is used; the solvent-free synthesis method has the advantages that the reaction monomers are solid, are heated into a molten state after being mechanically mixed to start reaction, and start reaction at a certain temperature, and the method does not use solvents, can effectively avoid environmental pollution and reduce cost, but causes that the reaction heat release is not easy to control, the reaction local heat release is severe, and the product yield is influenced; the suspension method uses water as a dispersion medium, and the suspension method is used for cooling and washing products after high-speed stirring granulation under the action of a suspending agent. The suspension method uses water as a dispersion medium, avoids using an organic solvent, reduces environmental pollution, further reduces cost, but has slow reaction speed, low product purity and low yield due to poor direct solubility of reactants.

And along with the increasing requirement of the flame retardant property of the material of the laminated board, the fireproof material and the interior prepreg, a benzoxazine resin polymer with a phosphorus-containing hot book structure and high flame retardancy is provided. The flame retardant grade of the common benzoxazine resin glass cloth laminated board can reach V-0 grade by adding inorganic aluminum hydroxide, polysilane, methyl phosphate and other flame retardants, but the influence on the electrical and mechanical properties of the material is serious, and the addition amount is more than 10-20%. For example, after hexaphenoxycyclotriphosphazene is added, the flame retardant grade of the laminated board reaches V-0 grade, but the full strength of the laminated board is reduced from 484MPa to 410MPa, the 5 percent thermal weight loss is reduced from 420 ℃ to 290 ℃ of pure benzoxazine resin, and the appearance of the product is influenced when the laminated board is cured.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the high-flame-retardance phosphorus-containing benzoxazine resin, which overcomes the defects of the prior art, changes the monomer structure of the benzoxazine resin through a chemical modification method, increases the molecular structure of phosphorus-containing monomers in benzoxazine, designs and synthesizes phosphorus-containing ring type benzoxazine monomers, effectively improves the heat resistance and flame retardance of the polybenzoxazine resin, and has no great influence on mechanical properties and electrical properties; the purity and the yield of the product can be improved in the preparation process; can be suitable for large-scale production.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a high flame-retardant phosphorus-containing benzoxazine resin has a chemical structural formula shown in formula I:

wherein the content of the first and second substances,

is any one of the following structures:

the invention also discloses a preparation method of the phosphorus-containing benzoxazine resin, which comprises the following steps:

(1) preparing a benzoxazine monomer, sequentially adding a phosphorus-containing bisphenol intermediate, primary amine, an aldehyde compound and an amine catalyst into an organic solvent in a self-priming exhaust heat exchange reactor, starting a stirring machine to stir and mix, performing reaction for 1.5 to 2.5 hours by adopting gradient heating to 100 to 110 ℃, introducing condensed water to cool when the system becomes transparent, and stopping the reaction; obtaining the benzoxazine monomer mixture.

(2) And (2) purification treatment, namely adding an alkali solution into the benzoxazine monomer mixture obtained in the step (1), stirring for 1-2 hours, removing oligomers and other impurities generated in the system, and washing with water for 3 times to enable the system to be close to neutral.

(3) Removing the solvent: and (3) heating the system purified in the step (2) to 90-100 ℃, and quickly removing the solvent and residual moisture in the system under vacuum to obtain the benzoxazine monomer.

(4) And (3) curing the compound: and (4) placing the benzoxazine monomer obtained in the step (3) in a stainless steel mold, and starting temperature programming after exhausting air in an electrothermal blowing drying oven for 30 min. Curing and temperature rising procedures: 1 hour at 160 ℃,1 hour at 180 ℃,1 hour at 200 ℃ and 1 hour at 240 ℃ to obtain the cured phosphorus-containing benzoxazine resin product.

Preferably, the molar ratio of the phosphorus-containing bisphenol intermediate, the primary amine and the aldehyde compound in the step (1) is 1: 1: 2.

preferably, the chemical structural formula of the phosphorus-containing bisphenol intermediate in the step (1) is shown as formula II:

preferably, the phosphorus-containing bisphenol intermediate has a synthesis reaction formula shown in formula III:

the synthesis steps are as follows:

a. adding acetic acid and sodium hypophosphite monohydrate into a three-opening reaction bottle, adding initiators of benzoyl peroxide and p-allyloxyphenol after the acetic acid and the sodium hypophosphite monohydrate are dissolved, reacting for 4 hours at 100 ℃, and cooling to room temperature to obtain light yellow liquid.

b. Transferring the yellow liquid to a single-mouth round-bottom flask, evaporating the solvent in a rotary manner, recycling, washing the residual solid in the flask with dichloromethane to remove organic impurities, and pumping to obtain the phosphorus-containing bisphenol intermediate.

Preferably, the organic solvent in step (1) is one or more of methanol, ethanol, ethyl acetate, dichloromethane, chloroform, toluene, xylene, acetone, butanone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, dioxane and dimethyl sulfoxide.

Preferably, the aldehyde compound in the step (1) is an aqueous formaldehyde solution or paraformaldehyde.

Preferably, the alkali solution added in the step (2) is sodium hydroxide or potassium hydroxide, and is matched with a phase transfer catalyst.

The invention also discloses a manufacturing process of the glass cloth laminated board, which comprises the following steps: uniformly mixing the phosphorus-containing benzoxazine resin monomer obtained by the preparation method with a curing agent, bisphenol A epoxy resin and butanone, adding certain aluminum hydroxide, and dispersing at a high speed to obtain high-flame-retardancy benzoxazine resin liquid; then, the benzoxazine resin liquid is impregnated into alkali-free glass cloth and prepared into prepreg on a gluing machine, wherein the content of benzoxazine resin in the prepreg is 37-42%; preparing prepreg into a required size, taking a plurality of prepreg superposed layers according to the required thickness of a product, placing the prepreg superposed layers on a smooth stainless steel plate, and coating a release agent; and hot-press molding on a press, controlling gradient temperature rise, setting the temperature to be 10-20 ℃/30min, gradually raising the temperature and pressurizing, keeping the temperature for 30min after raising the temperature to 220 ℃, increasing the pressure to 5Mpa, hot-press molding for 2h, and demolding to obtain the product.

The invention provides a preparation method of high-flame-retardance phosphorus-containing benzoxazine resin. The method has the following beneficial effects: the monomer structure of the benzoxazine resin is changed by a chemical modification method, the molecular structure of a phosphorus-containing monomer in benzoxazine is increased, a phosphorus-containing ring-shaped benzoxazine monomer is designed and synthesized, the heat resistance and the flame retardance of the polybenzoxazine resin are effectively improved by improving the phosphorus content in the monomer, and the mechanical property and the electrical property are not greatly influenced; and the purity and the yield of the product can be improved in the preparation process.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings.

In the first embodiment, the chemical structural formula of the phosphorus-containing benzoxazine resin is shown in formula I:

wherein the content of the first and second substances,

is any one of the following structures:

(1) preparing a benzoxazine monomer, and sequentially adding the benzoxazine monomer into an organic solvent in a self-suction exhaust heat exchange reactor according to a molar ratio of 1: 2: 4, adding a phosphorus-containing bisphenol intermediate, a primary amine and an aldehyde compound, adding an amine catalyst, starting a stirring machine to stir and mix, performing gradient heating to 80-120 ℃, reacting for 2-8 hours, and introducing condensed water to cool when the system becomes transparent, and stopping the reaction; obtaining the benzoxazine monomer mixture. The amine catalyst can better reduce the residue of free amine, increase the reaction activity and accelerate the reaction speed. Wherein the chemical structural formula of the phosphorus-containing bisphenol intermediate is shown as a formula II:

(2) and (2) purification treatment, namely adding an alkali solution of sodium hydroxide or potassium hydroxide into the benzoxazine monomer mixture obtained in the step (1), stirring for 1-2 hours, removing oligomers and other impurities generated in the system, and washing for 3 times to enable the system to be close to neutral. The alkali solution of sodium hydroxide or potassium hydroxide needs to be added with a small amount of phase transfer catalyst during preparation, and the phase transfer catalyst is mainly used for washing away unreacted phenolic substances.

Example two

The reaction equation for preparing the benzoxazine resin by the solution method is as follows:

the experimental steps are as follows: 0.1mol of aniline, 30mL of toluene and 0.2mol of paraformaldehyde were added to a 100mL three-necked round-bottomed flask equipped with a reflux condenser and a thermometer at room temperature, and 0.05mol of phosphorus-containing bisphenol intermediate A was added thereto with stirring, followed by heating to 80 ℃ and reacting for 4 hours. After cooling to room temperature, the reaction was washed with water three times, and the solvent and residual water were removed by distillation under the reduced pressure to obtain about 26.5g of the objective benzoxazine resin BZ-1 with a yield of 85%. The resulting composition was subjected to 31P NMR measurement, and the results are shown in FIG. 1; the results of the DSC test are shown in FIG. 2; the results of the TGA test are shown in FIG. 3.

EXAMPLE III

the experimental steps are as follows: 0.1mol of methylamine, 30mL of dioxane and 0.2mol of paraformaldehyde are charged into a 100mL three-necked round-bottomed flask equipped with a reflux condenser and a thermometer at room temperature, and after 0.05mol of phosphorus-containing bisphenol intermediate A is added with sufficient stirring, the temperature is raised to 60 ℃ to react for 8 hours. After cooling to room temperature, the reaction was washed with water three times, and the solvent and residual water were removed by distillation under the reduced pressure to obtain about 19.4g of the objective benzoxazine resin BZ-2 with a yield of 78%.

Example four

the method comprises the following steps: 0.1mol of n-butylamine, 30mL of dioxane and 0.2mol of paraformaldehyde were charged into a 100mL three-necked round-bottomed flask equipped with a reflux condenser and a thermometer at room temperature, and 0.05mol of phosphorus-containing bisphenol intermediate A was added thereto with stirring, followed by heating to 100 ℃ and reacting for 6 hours. After cooling to room temperature, the reaction was washed with water three times, and the solvent and residual water were removed by distillation under the reduced pressure to obtain about 23.9g of the objective benzoxazine resin BZ-3 with a yield of 82%.

EXAMPLE five

the experimental steps are as follows: 0.1mol of n-butylamine, 30mL of xylene and 0.2mol of paraformaldehyde were charged into a 100mL three-necked round-bottomed flask equipped with a reflux condenser and a thermometer at room temperature, and 0.05mol of phosphorus-containing bisphenol intermediate A was added thereto with stirring, followed by heating to 120 ℃ and reacting for 2 hours. After cooling to room temperature, the reaction was washed with water three times, and the solvent and residual water were removed by distillation under the reduced pressure to obtain about 29.6g of the objective benzoxazine resin BZ-4 with a yield of 88%.

EXAMPLE six

The invention also discloses a process for manufacturing a glass cloth laminated board by using the phosphorus-containing benzoxazine resin monomer obtained by the preparation method, which comprises the following steps: uniformly mixing the phosphorus-containing benzoxazine resin monomer obtained by the preparation method with a curing agent, bisphenol A epoxy resin and butanone according to a ratio, adding aluminum hydroxide with different mass fractions, and dispersing at a high speed to obtain a high-flame-retardancy benzoxazine resin liquid; then, the benzoxazine resin liquid is impregnated into alkali-free glass cloth, and a prepreg is prepared on a gluing machine according to a specified process, wherein the benzoxazine resin content of the prepreg is 37-42%; preparing prepreg into a required size, taking a plurality of prepreg superposed layers according to the required thickness of a product, placing the prepreg superposed layers on a smooth stainless steel plate, and coating a release agent; and hot-press molding on a press, controlling gradient temperature rise, setting the temperature to be 10-20 ℃/30min, gradually raising the temperature and pressurizing, keeping the temperature for 30min after raising the temperature to 220 ℃, increasing the pressure to 5Mpa, hot-press molding for 2h, and demolding to obtain the product.

The flame retardancy test experiment of the benzoxazine resin product obtained in the above is as follows:

the test is carried out according to the UL94V-0 vertical burning standard, and 5 sample bars with the length of 125 +/-5 mm, the width of 13.0 +/-0.5 mm and the thickness of 3mm are taken, ground and dried for testing. Adjusting the height of the flame of the UL-94 vertical combustor to 2cm, igniting one end of the sample strip vertical to the flame for 10s, recording the time of the sample strip continuing to burn until self-extinguishing after the flame is ignited; each specimen was fired twice and the duration after firing was recorded 10 times. The test results are shown in table 1:

TABLE 1 relationship between the amount of aluminum hydroxide added and the flame retardancy grade

In table 1 above: the V-0 level is expressed as maximum sustained combustion time not exceeding 10 seconds, 10 times of average sustained combustion time not exceeding 5 seconds, no dripping;

UL 94V-1 rating expressed as maximum sustained burn time of no more than 30 seconds, average burn time of no more than 25 seconds, no drips;

UL 94V-2 rating indicates maximum sustained burn time of no more than 30 seconds, average burn time of no more than 25 seconds, and dripping.

Typical properties of the cured product of the above described benzoxazine resin are shown in table 2 below:

TABLE 2 typical Properties of the cured product

The experiments show that the phosphorus-containing benzoxazine resin polymer prepared by the method is added with a phosphorus-containing structure on a polymerization structure compared with common bisphenol A type resin and diamine type benzoxazine resin, the heat resistance and the flame retardance of the polybenzoxazine resin are effectively improved by adding a small amount of flame retardant aluminum hydroxide, and the mechanical property and the electrical property are not greatly influenced.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of high flame retardant phosphor-containing benzoxazine resin is characterized by comprising the following steps: the chemical structural formula of the phosphorus-containing benzoxazine resin is shown as formula I:

wherein the content of the first and second substances,

is any one of the following structures:

the preparation method of the high-flame-retardance phosphorus-containing benzoxazine resin comprises the following steps:

(1) preparing a benzoxazine monomer, sequentially adding a phosphorus-containing bisphenol intermediate, primary amine, an aldehyde compound and an amine catalyst into an organic solvent in a self-priming exhaust heat exchange reactor, starting a stirring machine to stir and mix, performing reaction for 2-8 hours by adopting gradient heating to 80-120 ℃, and introducing condensed water to cool when the system becomes transparent, and stopping the reaction; obtaining a benzoxazine monomer mixture;

(2) purifying, namely adding an alkali solution into the benzoxazine monomer mixture obtained in the step (1), stirring for 1-2 hours, removing oligomers and other impurities generated in the system, and washing for 3 times to enable the system to be close to neutral;

(3) and (3) removing the solvent: heating the purified system in the step (2) to 90-100 ℃, and rapidly removing the solvent and residual moisture in the system under vacuum to obtain a benzoxazine monomer;

(4) and (3) curing the compound: placing the benzoxazine monomer obtained in the step (3) in a stainless steel mold, and starting temperature programming after air is exhausted in an electrothermal blowing drying oven for 30 min; curing and temperature rising procedures: 1 hour at 160 ℃,1 hour at 180 ℃,1 hour at 200 ℃ and 1 hour at 240 ℃ to obtain a cured phosphorus-containing benzoxazine resin product;

the synthesis reaction equation of the phosphorus-containing bisphenol intermediate is shown as the formula III:

the synthesis steps are as follows:

a. adding acetic acid and sodium hypophosphite monohydrate into a three-opening reaction bottle, adding initiators of benzoyl peroxide and p-allyloxyphenol after the acetic acid and the sodium hypophosphite monohydrate are dissolved, reacting for 4 hours at the temperature of 100 ℃, and cooling to room temperature to obtain light yellow liquid;

2. The method for preparing the high-flame-retardancy phosphorus-containing benzoxazine resin according to claim 1, wherein the method comprises the following steps: the molar ratio of the phosphorus-containing bisphenol intermediate to the primary amine to the aldehyde compound in the step (1) is 1: 2: 4.

3. the method for preparing the high-flame-retardancy phosphorus-containing benzoxazine resin according to claim 1, wherein the method comprises the following steps: the organic solvent in the step (1) is one or a mixture of more of methanol, ethanol, ethyl acetate, dichloromethane, chloroform, toluene, xylene, acetone, butanone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, dioxane and dimethyl sulfoxide.

4. The method for preparing the high-flame-retardancy phosphorus-containing benzoxazine resin according to claim 1, wherein the method comprises the following steps: the aldehyde compound in the step (1) is formaldehyde aqueous solution or paraformaldehyde.

5. The method for preparing the high-flame-retardancy phosphorus-containing benzoxazine resin according to claim 1, wherein the method comprises the following steps: the alkali solution added in the step (2) is sodium hydroxide or potassium hydroxide and is matched with a phase transfer catalyst.

6. The manufacturing process of the glass cloth laminated board is characterized in that: uniformly mixing the phosphorus-containing benzoxazine resin monomer according to claim 1 with a curing agent, bisphenol A epoxy resin and butanone, adding certain aluminum hydroxide, and dispersing at a high speed to obtain a high-flame-retardancy benzoxazine resin solution; then, the benzoxazine resin liquid is impregnated into alkali-free glass cloth and prepared into prepreg on a gluing machine, wherein the content of benzoxazine resin in the prepreg is 37-42%; preparing prepreg into a required size, taking a plurality of prepreg superposed layers according to the required thickness of a product, placing the prepreg superposed layers on a smooth stainless steel plate, and coating a release agent; and hot-press molding on a press, controlling gradient temperature rise, setting the temperature to be 10-20 ℃/30min, gradually raising the temperature and pressurizing, keeping the temperature for 30min after raising the temperature to 220 ℃, increasing the pressure to 5Mpa, hot-press molding for 2h, and demolding to obtain the product.