Preparation method of flame-retardant cyanate resin adhesive

Abstract

The invention discloses a preparation method of a flame-retardant cyanate ester resin adhesive, which comprises the following steps: respectively preparing phosphorus-containing phenolic resin and silicon-containing phenolic resin, respectively preparing phosphorus-containing cyanate ester resin and silicon-containing cyanate ester resin from the phosphorus-containing phenolic resin and the silicon-containing phenolic resin and hydrogen bromide, and mixing the prepared phosphorus-containing cyanate ester resin and silicon-containing cyanate ester resin to prepare the flame-retardant cyanate ester resin adhesive. Phosphate ester is used for modifying phenolic resin and can be used as a connection point to connect the phenolic resin, so that a compact carbon layer can be formed on the surface of the resin during combustion, further pyrolysis of the resin can be prevented on one hand, and substances generated by thermal decomposition in the resin can be prevented from entering a gas phase to participate in combustion on the other hand; due to the existence of the silicon element, the stability of a formed carbon layer can be improved, the carbon residue amount of the carbon layer at a high temperature is increased, the structural strength of the carbon layer is enhanced, and the problem that the flame-retardant effect is reduced due to the fact that the carbon layer is easy to crack when the phosphorus content of the resin is relatively low is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer resin materials, in particular to a method for preparing a flame retardant cyanate ester resin adhesive. Background Art

[0002] Cyanate resin has good high temperature resistance and low dielectric properties, and is very suitable for use as an adhesive. The water absorption rate of cyanate resin is extremely low, usually less than 1.5%, which is very effective in improving the stability and reliability of adhesives in humid environments. It also has low curing absorption rate, low molding shrinkage, and good dimensional stability, which makes the strength of the bonding more reliable. Patent CN118725219A provides a phenolic cyanate resin, a preparation method and an application. Cyanate resin is prepared using phenolic resin and hydrogen bromide as raw materials. The obtained resin has the characteristics of high strength and high temperature resistance. However, as an organic material, its flame retardant properties cannot meet the growing flame retardant performance requirements of modern materials. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing a flame retardant cyanate ester resin adhesive with excellent flame retardant effect.

[0004] In order to solve the above technical problems, the present invention comprises the following steps:

[0005] S1 Introduction of phosphorus-containing flame retardant groups: 1-2.5 kg of phenolic resin and 3-7 moles of phosphate compound are mixed in a reaction solvent, hydrogen chloride is added as a catalyst, the reaction is carried out at a temperature range of 60°C-80°C for 1-2 hours, and distilled at 75-79°C under normal pressure for 0.5 hours, dichloromethane is added to fully dissolve, and then toluene is added to fully dissolve, the solution is filtered, and the solution is evaporated to remove the solvent to obtain a phosphorus-containing phenolic resin;

[0006] S2 introduction of silicon-containing flame retardant groups: 1-2.5 kg of phenolic resin and 2-4 moles of silanol compounds are mixed in a reaction solvent, stirred and gradually heated to reflux of the solvent, reacted for 3-5 hours, added dichloromethane to fully dissolve, then added butanone to fully dissolve, filtered the solution, evaporated the solution to remove the solvent, and prepared a silicon-containing phenolic resin;

[0007] Preparation of S3 cyanate resin: 1-2.5 kg of phosphorus-containing phenolic resin prepared in S1 and silicon-containing phenolic resin prepared in S2 are weighed and mixed with 10-30 mol of hydrogen bromide in a reaction solvent, a catalyst is added, and the mixture is reacted at a temperature range of 50-55° C. for 5-15 hours, dichloromethane is added to fully dissolve the mixture, and then butanone is added to fully dissolve the mixture, the solution is filtered, and the solvent is evaporated to obtain phosphorus-containing cyanate resin and silicon-containing cyanate resin, respectively;

[0008] S4 mixing: the phosphorus-containing cyanate resin prepared in S3 is mixed with the silicon-containing cyanate resin to prepare a flame-retardant cyanate resin adhesive.

[0009] Preferably, the mass of the phenolic resin described in S1 is 2 kg, and the amount of the phosphate compound is 5 mol.

[0010] Preferably, the mass of the phenolic resin described in S2 is 2 kg, and the amount of the silanol compound is 3 mol.

[0011] Preferably, the phosphate compound described in S1 is triphenyl phosphate, tricresyl phosphate, isopropylated triphenyl phosphate, triethyl phosphate or BDP (bisphenol A-bis(diphenyl phosphate)).

[0012] Preferably, the silanol compound described in S2 is trimethylsilanol, triphenylsilanol, tripropylsilanol or polydimethylsiloxane.

[0013] Preferably, the catalyst described in S3 is trialkylamine or triethylamine.

[0014] Preferably, the mass ratio of the phosphorus-containing cyanate resin to the silicon-containing cyanate resin in S4 is 7:5.

[0015] The beneficial effects of the present invention are:

[0016] The use of phosphate to modify the phenolic resin can connect the phenolic resin with the phosphate as the connection point, so that a dense carbon layer can be formed on the surface of the resin during combustion, which can prevent the resin from further pyrolysis on the one hand, and prevent the substances produced by the internal pyrolysis of the resin from entering the gas phase to participate in combustion on the other hand. The presence of silicon can improve the stability of the formed carbon layer, increase the amount of residual carbon in the carbon layer at high temperature, enhance the structural strength of the carbon layer, and effectively solve the problem that the carbon layer is easy to break when the phosphorus content of the resin is low, resulting in a decrease in the flame retardant effect. The present invention improves the flame retardant effect of the cyanate ester resin through the synergistic effect of phosphorus and silicon when the phosphorus content of the reactive flame retardant is limited. DETAILED DESCRIPTION

[0017] The instruments, reagents, materials, etc. involved in the following embodiments, unless otherwise specified, are all conventional instruments, reagents, materials, etc. in the prior art and can be obtained through regular commercial channels. The experimental methods, detection methods, etc. involved in the following embodiments, unless otherwise specified, are all conventional experimental methods, detection methods, etc. in the prior art.

[0018] The phenolic resin in all the following specific examples and comparative examples adopts thermoplastic phenolic resin with an average molecular weight of 650. Fully dissolved in the present invention means that the solvent is added during the stirring process until the solid phase no longer decreases.

[0019] Embodiment 1:

[0020] S1 Introduction of phosphorus-containing flame retardant group: 2 kg of phenolic resin and 5 mol of triphenyl phosphate were mixed in 10 L of butanone, hydrogen chloride was added to adjust the pH value to be in the range of 4.2-4.5, the reaction was carried out in the temperature range of 60°C-70°C for 2 h, and distilled at 75°C for 0.5 h. After adding dichloromethane to fully dissolve, toluene was added to fully dissolve, the solution was filtered, and the solution was evaporated to remove the solvent to obtain a phosphorus-containing phenolic resin;

[0021] S2 introduction of silicon-containing flame retardant groups: 2 kg of phenolic resin and 3 mol of trimethylsilanol were mixed in 10 L of acetone, stirred and gradually heated to solvent reflux, reacted for 4 h, added dichloromethane to fully dissolve, then added butanone to fully dissolve, filtered the solution, evaporated the solution to remove the solvent, and prepared silicon-containing phenolic resin;

[0022] Preparation of S3 cyanate resin: 1 kg of phosphorus-containing phenolic resin prepared in S1 and 1 kg of silicon-containing phenolic resin prepared in S2 were weighed and mixed with 15 mol of hydrogen bromide in 20 L of acetone, 0.5 mol of trialkylamine was added as a catalyst, and the mixture was reacted at 50°C for 6 h. After dichloromethane was added to fully dissolve the mixture, butanone was added to fully dissolve the mixture, the solution was filtered, and the solvent was evaporated to obtain phosphorus-containing cyanate resin and silicon-containing cyanate resin, respectively.

[0023] S4 mixing: the phosphorus-containing cyanate resin prepared in S3 is mixed with the silicon-containing cyanate resin in a mass ratio of 7:5 to prepare a flame-retardant cyanate resin adhesive.

[0024] The limiting oxygen index (LOI) of the flame retardant cyanate resin adhesive prepared by S4 was measured according to GB / J2406.2-2009. The LOI of this embodiment was 37.2. The residual carbon rate and the 5% thermal weight loss temperature (T 5％ ), 700℃ residual carbon rate is 46.8%, T 5％ It is 383℃.

[0025] Embodiment 2:

[0026] The difference from Example 1 is that tricresyl phosphate is used as the phosphate ester compound instead of triphenyl phosphate, and triphenylsilanol is used as the silanol compound instead of trimethylsilanol.

[0027] The flame retardant cyanate resin adhesive prepared in this embodiment has a LOI of 36.7, a carbon residue rate of 44.5% at 700°C, and a T 5％ It is 378℃.

[0028] Embodiment 3:

[0029] The difference from Example 1 is that isopropylated triphenyl phosphate is used as the phosphate ester compound instead of triphenyl phosphate, and tripropylsilanol is used as the silanol compound instead of trimethylsilanol.

[0030] The flame retardant cyanate resin adhesive prepared in this embodiment has a LOI of 35.9, a carbon residue rate of 42.4% at 700°C, and a T 5％ is 370℃.

[0031] Embodiment 4:

[0032] The difference from Example 1 is that BDP is used as the phosphate compound instead of triphenyl phosphate, and polydimethylsiloxane is used as the silanol compound instead of trimethylsilanol.

[0033] The flame retardant cyanate resin adhesive prepared in this embodiment has a LOI of 35.1, a carbon residue rate of 44.6% at 700°C, and a T 5％ It is 354℃.

[0034] Embodiment 5:

[0035] The difference from Example 1 is that S1 uses 1 kg of phenolic resin and 3 moles of triphenyl phosphate for reaction, and S2 uses 1 kg of phenolic resin and 2 moles of trimethylsilanol for reaction.

[0036] The flame retardant cyanate resin adhesive prepared in this embodiment has a LOI of 36.3, a carbon residue rate of 37.4% at 700°C, and a T 5％ It is 336℃.

[0037] Embodiment 6:

[0038] The difference from Example 1 is that S1 uses 2.5 kg of phenolic resin and 7 mol of triphenyl phosphate for reaction, and S2 uses 2.5 kg of phenolic resin and 4 mol of trimethylsilanol for reaction.

[0039] The flame retardant cyanate resin adhesive prepared in this embodiment has a LOI of 36.5, a carbon residue rate of 38.4% at 700°C, and a T 5％ It is 374℃.

[0040] Embodiment 7:

[0041] The difference from Example 1 is that in S4, the phosphorus-containing cyanate resin and the silicon-containing cyanate resin are mixed in a mass ratio of 1:1.

[0042] The flame retardant cyanate resin adhesive prepared in this embodiment has a LOI of 33.6, a carbon residue rate of 36.8% at 700°C, and a T 5％ It is 367℃.

[0043] Embodiment 8:

[0044] The difference from Example 1 is that in S4, the phosphorus-containing cyanate resin and the silicon-containing cyanate resin are mixed in a mass ratio of 8:5.

[0045] The flame retardant cyanate resin adhesive prepared in this embodiment has a LOI of 36.0, a carbon residue rate of 38.8% at 700°C, and a T 5％ It is 342℃.

[0046] Comparative Example 1:

[0047] 2 kg of phenolic resin and 5 mol of triphenyl phosphate are mixed in 10 L of butanone, 1 mol of hydrogen chloride is added, the reaction is carried out in the temperature range of 60°C-70°C for 2 hours, and distilled at 75°C for 0.5 hour. After adding dichloromethane to fully dissolve, toluene is added to fully dissolve, the solution is filtered out, and the solution is evaporated to remove the solvent to obtain a phosphorus-containing phenolic resin; 1 kg of phosphorus-containing phenolic resin is mixed with 15 mol of hydrogen bromide in a reaction solvent, trialkylamine is added as a catalyst, the reaction is carried out in the temperature range of 50°C for 6 hours, dichloromethane is added to fully dissolve, butanone is added to fully dissolve, the solution is filtered out, and the solution is evaporated to remove the solvent to obtain a phosphorus-containing cyanate resin.

[0048] The phosphorus-containing cyanate resin prepared in this comparative example has a LOI of 33.5, a carbon residue rate of 29.5% at 700°C, and a T 5％ It is 284℃.

[0049] Comparative Example 2:

[0050] 2 kg of phenolic resin and 3 mol of trimethylsilanol were mixed in 10 L of acetone, stirred and gradually heated to solvent reflux, reacted for 4 hours, added dichloromethane to fully dissolve, then added butanone to fully dissolve, filtered out the solution, evaporated the solution to remove the solvent, and obtained a silicon-containing phenolic resin; 1 kg of silicon-containing phenolic resin was mixed with 15 mol of hydrogen bromide in a reaction solvent, trialkylamine was added as a catalyst, reacted at a temperature range of 50°C for 6 hours, added dichloromethane to fully dissolve, then added butanone to fully dissolve, filtered out the solution, evaporated the solution to remove the solvent, and obtained a silicon-containing cyanate resin.

[0051] The LOI of the silicon-containing cyanate resin prepared in this comparative example is 32.4, the carbon residue rate at 700°C is 33.6%, and the T 5％ It is 276℃.

[0052] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a flame retardant cyanate ester resin adhesive, characterized in that: The following steps are involved: S1 Introduction of phosphorus-containing flame retardant groups: 1-2.5 kg of phenolic resin and 3-7 moles of phosphate compound are mixed in a reaction solvent, hydrogen chloride is added as a catalyst, the reaction is carried out at a temperature range of 60°C-80°C for 1-2 hours, and distilled at 75-79°C under normal pressure for 0.5 hours, dichloromethane is added to fully dissolve, and then toluene is added to fully dissolve, the solution is filtered, and the solution is evaporated to remove the solvent to obtain a phosphorus-containing phenolic resin; S2 introduction of silicon-containing flame retardant groups: 1-2.5 kg of phenolic resin and 2-4 moles of silanol compounds are mixed in a reaction solvent, stirred and gradually heated to reflux of the solvent, reacted for 3-5 hours, added dichloromethane to fully dissolve, then added butanone to fully dissolve, filtered the solution, evaporated the solution to remove the solvent, and prepared a silicon-containing phenolic resin; Preparation of S3 cyanate resin: 1-2.5 kg of phosphorus-containing phenolic resin prepared in S1 and silicon-containing phenolic resin prepared in S2 are weighed and mixed with 10-30 mol of hydrogen bromide in a reaction solvent, a catalyst is added, and the mixture is reacted at a temperature range of 50-55° C. for 5-15 hours, dichloromethane is added to fully dissolve the mixture, and then butanone is added to fully dissolve the mixture, the solution is filtered, and the solvent is evaporated to obtain phosphorus-containing cyanate resin and silicon-containing cyanate resin, respectively; S4 mixing: the phosphorus-containing cyanate resin prepared in S3 is mixed with the silicon-containing cyanate resin to prepare a flame-retardant cyanate resin adhesive.

2. The method for preparing a flame retardant cyanate ester resin adhesive according to claim 1, characterized in that: The mass of the phenolic resin described in S1 is 2 kg, and the amount of the phosphate compound is 5 mol.

3. The method for preparing the flame retardant cyanate ester resin adhesive according to claim 1, characterized in that: The mass of the phenolic resin described in S2 is 2 kg, and the amount of the silanol compound is 3 mol.

4. The method for preparing the flame retardant cyanate ester resin adhesive according to claim 1, characterized in that: The phosphate compound described in S1 is triphenyl phosphate, tricresyl phosphate, isopropylated triphenyl phosphate, triethyl phosphate or BDP (bisphenol A-bis(diphenyl phosphate)).

5. The method for preparing the flame retardant cyanate ester resin adhesive according to claim 1, characterized in that: The silanol compound described in S2 is trimethylsilanol, triphenylsilanol, tripropylsilanol or polydimethylsiloxane.

6. The method for preparing the flame retardant cyanate ester resin adhesive according to claim 1, characterized in that: The catalyst described in S3 is trialkylamine or triethylamine.

7. The method for preparing a flame retardant cyanate ester resin adhesive according to claim 1, characterized in that: The mass ratio of the phosphorus-containing cyanate resin to the silicon-containing cyanate resin in S4 is 7:5.