Lignin type benzoxazine and preparation method thereof

A technology of benzoxazine and lignin, which is applied in the field of benzoxazine preparation, can solve the problems of low addition amount and poor solubility, and achieve the effects of increased addition amount, increased thermal stability, and good solubility

Active Publication Date: 2021-02-02
GUANGXI TEACHERS EDUCATION UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Studies have shown that lignin can replace part of phenol for the preparation of phenolic resin adhesives, but in the prior art, lignin is introduced into benzoxazine by blending, and lignin is also directly used as phenol source It is introduced into benzoxazine, but the dispersion of lignin in benzoxazine or the solubility in the reaction mixture system is not good, and the addition amount is low, and it is not effective in the curing process of benzoxazine or benzoxazine During the oxazine synthesis process, it will be precipitated and deposited from it, resulting in only a small amount of hydroxyl or carboxyl groups on the surface of lignin particles acting on the ring-opening polymerization of benzoxazine

Method used

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  • Lignin type benzoxazine and preparation method thereof
  • Lignin type benzoxazine and preparation method thereof
  • Lignin type benzoxazine and preparation method thereof

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] Embodiment 1: Preparation of phenolated lignin

[0034] Add lignin, phenol, NaOH solution and an appropriate amount of water into a three-necked flask, reflux at a certain temperature for a period of time to obtain phenolized lignin, and use phenolized lignin to replace 5% phenol by mass fraction to prepare lignin-phenol-aniline Taking benzoxazine (5L-Pa) as an example, the effects of factors such as the mass ratio of lignin to phenol, the amount of NaOH, temperature and time on the phenolization of lignin were investigated by DSC. First, the effect of the mass ratio of lignin to phenol on phenolization was studied. The mass ratios of lignin to phenol were 1:1, 1:1.5, 1:2 and 1:2.5, respectively; The influence of the phenolization of lignin, the dosage of NaOH is 2.5%, 5.0%, 7.5% and 10.0% of the mass of lignin; finally, the influence of reaction temperature and time on the phenolization is investigated, the temperature and time are respectively 60 ℃ for 9h, 70°C for 6...

Embodiment 2

[0047] Embodiment 2: Preparation of lignin-hydroquinone-hexamethylenediamine type benzoxazine

[0048] Add paraformaldehyde and distilled water into a three-necked flask equipped with a condenser and a stirring device, adjust the pH value to about 8 with 4% sodium hydroxide, and stir at 60°C to dissolve all of it to obtain an aqueous formaldehyde solution. After the formaldehyde aqueous solution is cooled to room temperature, add hexamethylenediamine and dioxane; after reacting in an ice bath for 30 minutes, add hydroquinone, dioxane and ethanol, and when the temperature rises to 80°C, add phenolized lignin, The reaction was continued at 80° C. for 5 h to obtain a mixture of lignin-hydroquinone-hexamethylenediamine-type benzoxazine. Wherein, the ratio of the amount of the above-mentioned phenols (including hydroquinone and phenolated lignin), hexamethylenediamine and paraformaldehyde is 1:1:4, and the mass ratio of phenolated lignin to hydroquinone It is 3:97, that is, the re...

Embodiment 3

[0049] Embodiment 3: Preparation of lignin-cardanol-cyclohexylamine type benzoxazine

[0050] Add paraformaldehyde and distilled water into a three-neck flask equipped with a condenser and a stirring device, adjust the pH value to 9.0 with 4% sodium hydroxide, and stir at 65°C to completely dissolve it to obtain an aqueous formaldehyde solution. After the formaldehyde solution is cooled to room temperature, add cyclohexylamine and xylene; after reacting at room temperature for 30 minutes, add cardanol, xylene and ethanol, wait until the temperature rises to 80°C, add phenolated lignin, and continue the reaction at 80°C for 5 hours A lignin-cardanol-cyclohexylamine-type benzoxazine mixture is obtained. Wherein, the ratio of the amount of the above-mentioned phenols (comprising cardanol and phenolized lignin), cyclohexylamine and paraformaldehyde is 1:1:2, and the mass ratio of phenolized lignin to cardanol is 3:97 , that is, the substitution amount of phenolized lignin for phe...

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Abstract

The invention discloses a preparation method of lignin-type benzoxazine, comprising: step 1, dissolving paraformaldehyde in solvent 1, adding amines and solvent 2, after reaction, adding phenolic mixture and solvent 3, Heating and continuing the reaction to obtain a benzoxazine mixture; step 2, washing the benzoxazine mixture to neutrality, rotary steaming, and drying to obtain a lignin-type benzoxazine; wherein, the phenolic The mixture includes phenolated lignin. The present invention uses phenolized lignin to replace part of phenol or bisphenol A, so that lignin can have good solubility in mixed systems such as amines, phenols, solvents, etc., the addition of lignin is large, and the obtained benzoxazine The ring-opening polymerization temperature was significantly lowered.

Description

technical field [0001] The invention relates to the field of preparation of benzoxazines. More specifically, the present invention relates to a lignin-type benzoxazine and a preparation method thereof. Background technique [0002] As a new type of phenolic resin, benzoxazine not only has the excellent thermal properties, mechanical properties and electrical properties of traditional phenolic resins, but also has the advantages of no need for external catalysts during the polymerization process, no small molecule release during the curing process, and close to zero volume shrinkage. , low water absorption and surface energy, etc. In addition, benzoxazine has low melt viscosity and good processing performance. However, benzoxazine still has some disadvantages, such as high ring-opening polymerization temperature and high brittleness, which limit its application in many fields. At present, there are mainly two methods for reducing the temperature of the ring-opening polymeri...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G14/073C08H7/00
CPCC08G14/06C08H6/00
Inventor 朱永飞程马力王乐萌苏俊铭李沛林
Owner GUANGXI TEACHERS EDUCATION UNIV
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