阅读说明：本技术 一种改性木质素、制备方法及其在增韧阻燃复合材料中的应用 (Modified lignin, preparation method and application thereof in toughening flame-retardant composite material ) 是由 东为富 王冬 李婷 汪洋 夏碧华 张旭辉 蒋杰 杨伟军 于 2020-08-06 设计创作，主要内容包括：一种改性木质素、制备方法及其在增韧阻燃复合材料中的应用,属于阻燃剂及生物基阻燃材料领域。将质量比为1:(0.08～0.5)的三聚氰胺和甲醛加入到水中,60℃～90℃下搅拌反应0.5～2h；将所述的碱性木质素、甲醛和植酸相对于三聚氰胺按照质量比为(0.25～2):(0.13～1.0):(0.25～2):1逐步加入到步骤(1)所得的溶液中,在50～90℃下反应3～5h后,过滤干燥得到改性木质素；采用聚合物树脂、改性木质素和增塑剂共混得到增韧阻燃的复合材料。本发明改性木质素增韧阻燃复合材料的制备方法生产效率高,工艺简单,性能优良,环境友好且容易实现工业化生产。(Modified lignin, a preparation method and application thereof in toughening flame-retardant composite materials, belonging to the field of flame retardants and bio-based flame-retardant materials. Adding melamine and formaldehyde with the mass ratio of 1 (0.08-0.5) into water, and stirring and reacting for 0.5-2 h at the temperature of 60-90 ℃; adding the alkaline lignin, formaldehyde and phytic acid into the solution obtained in the step (1) step by step according to the mass ratio of (0.25-2): 0.13-1.0): 0.25-2): 1, reacting at 50-90 ℃ for 3-5 h, filtering and drying to obtain modified lignin; the toughened flame-retardant composite material is obtained by blending polymer resin, modified lignin and a plasticizer. The preparation method of the modified lignin toughening flame-retardant composite material has the advantages of high production efficiency, simple process, excellent performance, environmental friendliness and easy realization of industrial production.)

1. The modified lignin is characterized in that the structural general formula of the modified lignin is as follows:

in the formula, R⁺Is H⁺Or

2. The preparation method of the modified lignin is characterized by comprising the following specific steps:

(1) adding melamine and formaldehyde with the mass ratio of 1: 0.08-0.5 into water, and stirring and reacting for 0.5-2 h at the temperature of 60-90 ℃; the mass ratio of the water to the alkaline lignin is 5-50: 1

(2) And (2) adding the alkaline lignin, formaldehyde and phytic acid into the solution obtained in the step (1) step by step according to the mass ratio of 0.25-2: 0.13-1.0: 0.25-2: 1 relative to melamine, reacting for 3-5 h at 50-90 ℃, and filtering and drying to obtain the modified lignin.

3. The preparation method of the modified lignin according to claim 2, wherein in the step (1), the mass ratio of the melamine to the formaldehyde is 1: 0.15-0.25.

4. The method for preparing modified lignin according to claim 2, wherein in the step (2), the mass ratio of the alkaline lignin, the formaldehyde and the phytic acid to the melamine is 0.5-1: 0.25-0.55: 0.5-1: 1.

5. The method for preparing the modified lignin according to claim 2, 3 or 4, wherein the mass ratio of water to the alkaline lignin is 10-25: 1; the phytic acid is derived from seeds, roots, stems or stems of plants.

6. The toughening flame-retardant composite material based on modified lignin is characterized by comprising, by weight, 70-95 parts of modified lignin, 5-30 parts of modified lignin and 5-20 parts of a plasticizer.

7. The toughened flame-retardant composite material based on modified lignin according to claim 6, wherein the polymer resin is one or a combination of two or more of polylactic acid (PLA), polybutylene succinate (PBS), polypropylene (PP) and Polyethylene (PE).

8. The toughened flame-retardant composite material based on modified lignin according to claim 6, wherein the plasticizer is one or two of acetyl tri-n-butyl citrate ATBC, polyethylene glycol PEG400, polyethylene glycol PEG2000 and polyethylene glycol PEG 20000.

9. The toughened flame-retardant composite material based on modified lignin as claimed in claim 6, wherein one or more of antiaging agent, antiseptic, bactericide, antistatic agent crosslinking agent, pigment, filler or perfume is added as the auxiliary agent of the toughened flame-retardant composite material.

10. A preparation method of a modified lignin-based toughened flame-retardant composite material is characterized by comprising the following specific steps: drying the polymer resin, the plasticizer and the modified lignin in a vacuum oven at 80 ℃, then weighing the components according to the proportion, premixing the components, adding the premixed components into an internal mixer, and melting and blending the premixed components uniformly at the processing temperature of 110-175 ℃.

Technical Field

The invention belongs to the field of bio-based high polymer materials, and particularly relates to a modified lignin-based composite material, a preparation method thereof, a preparation method of the toughened flame-retardant composite material and application of the toughened flame-retardant composite material.

Background

Lignin is abundant in nature, is the second most abundant natural polymer next to cellulose, mainly comes from waste liquid from paper mill, and most of it is used as fuel at present, and only a small part of it is used as chemical product, resulting in great waste of resources. The basic building block of lignin is phenylpropane, comprising: guaiacyl propane, syringyl propane and p-hydroxyphenyl propane; in addition, the lignin structure unit is connected with a plurality of functional groups, such as benzene rings, phenolic hydroxyl groups, alcoholic hydroxyl groups, carboxyl groups, methoxyl groups, conjugated double bonds and the like, so that the lignin has strong reactivity, and the possibility of high-value utilization of the lignin in the field of materials is provided. The lignin has the advantages of being renewable, degradable, low in cost and the like, and can be used as a char forming agent of an expansion flame-retardant system to be compounded for flame retardance of high polymer materials, so that the lignin is efficiently and reasonably utilized, and the lignin has positive effects on economy and environment.

The lignin molecules are easy to agglomerate under the action of self chemical bonds, and have poor dispersibility in a matrix, so that the composite material has poor performance. In addition, the hydroxyl functional groups on the surface are more, which easily causes the degradation of polyester polymer materials, and leads the polymer to become brittle. Therefore, it is particularly interesting to modify lignin to improve the interfacial compatibility with polymers and to improve the mechanical properties thereof, and at the same time, to combine the properties of intumescent flame retardant.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a modified lignin-based composite material, a preparation method and application thereof in a toughened flame-retardant composite material. The modified lignin greatly reduces the size of the lignin, increases the compatibility with the polymer under the synergistic effect of the plasticizer, and greatly improves the toughness of the polymer. Meanwhile, nitrogen and phosphorus are introduced into the modified lignin, and the modified lignin and the lignin form the intumescent flame retardant. The preparation method of the modified lignin toughened flame-retardant polymer has the advantages of high production efficiency, simple process, excellent performance and easy realization of industrial production.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the toughened flame-retardant composite material based on the modified lignin comprises, by weight, 70-95 parts of the modified lignin, 5-30 parts of the modified lignin and 5-20 parts of a plasticizer.

A modified lignin, which has the following structural general formula:

in the formula, R⁺Is H⁺Or

R in structural formula of modified lignin⁺The number of the carbon atoms is more than or equal to 1.

The modified lignin is prepared by reacting alkaline lignin, melamine, formaldehyde and phytic acid in a solvent. Wherein the total mass ratio of the alkaline lignin, the melamine, the formaldehyde and the phytic acid is (0.25-2) to 1, (0.21-1.5) to (0.25-2.0), preferably (0.5-1) to 1, (0.4-0.8) to (0.5-1.0); the solvent for the reaction is water, and the mass ratio of the water to the alkaline lignin is (5-50): 1, preferably (10-25): 1.

The phytic acid is derived from seeds, roots, stems or stems of plants.

A preparation method of modified lignin comprises the following specific steps:

(1) adding melamine and formaldehyde with the mass ratio of 1 (0.08-0.5), preferably 1 (0.15-0.25) into water, and stirring and reacting at 60-90 ℃ for 0.5-2 h;

(2) adding the alkaline lignin, the formaldehyde and the phytic acid into the solution obtained in the step (1) step by step according to the mass ratio of (0.25-2): 0.13-1.0): 0.25-2): 1, preferably (0.5-1): 0.25-0.55): 0.5-1): 1 relative to the melamine, reacting at 50-90 ℃ for 3-5 h, filtering and drying to obtain modified lignin;

the polymer resin is one or the combination of more than two of polylactic acid PLA, polybutylene succinate PBS, polypropylene PP and polyethylene PE.

The plasticizer is one or two of acetyl tri-n-butyl citrate ATBC, polyethylene glycol PEG400, polyethylene glycol PEG2000 and polyethylene glycol PEG 20000.

A preparation method of a modified lignin-based toughened flame-retardant composite material specifically comprises the following steps: drying the polymer resin, the plasticizer and the modified lignin in a vacuum oven at 80 ℃, then weighing the components according to the proportion, premixing the components, adding the premixed components into an internal mixer, and melting and blending the premixed components uniformly at the processing temperature of 110-175 ℃.

One skilled in the art can add other optional additives selected from the group consisting of anti-aging agents, preservatives, bactericides, antistatic crosslinking agents, pigments, fillers, perfumes, and the like, simultaneously or separately, as needed to achieve better performance.

The invention has the beneficial effects that:

1. as the main components of the modification auxiliary agent, namely lignin and phytic acid, are bio-based sources, and the solvent used in the reaction is water, the method is environment-friendly and safe.

2. The toughened flame-retardant composite material prepared by the invention greatly improves the toughness of polymers and also has a flame-retardant effect.

Drawings

FIG. 1 is a schematic diagram of the synthesis of modified lignin synthesized according to the present invention.

FIG. 2 shows the oxygen index test results of the toughened flame retardant polymer prepared by the present invention. Wherein PLA, PLA100/ATBC15, PLA100/L20/ATBC15 and PLA100/LMP20/ATBC15 represent polymer composite materials to which 0 part additive, 15 parts ATBC, 20 parts alkaline lignin, 15 parts ATBC, and 20 parts modified lignin are added, respectively.

Detailed Description

The present invention will be further illustrated by the following detailed description, which is to be construed as merely illustrative and not limitative of the remainder of the disclosure, and it is within the scope of the present invention to be interpreted by those skilled in the art from the foregoing disclosure without limitation to the scope of the present invention.