CN110396861B

CN110396861B - Preparation method of microencapsulated flame retardant

Info

Publication number: CN110396861B
Application number: CN201910607908.1A
Authority: CN
Inventors: 刘洪斌; 孙熠炜; 安兴业
Original assignee: Tianjin University of Science and Technology
Current assignee: Tianjin University of Science and Technology
Priority date: 2019-07-08
Filing date: 2019-07-08
Publication date: 2022-02-18
Anticipated expiration: 2039-07-08
Also published as: CN110396861A

Abstract

The invention belongs to the field of flame retardant materials, and particularly relates to a preparation method for improving a microencapsulated flame retardant. The method provided by the invention is characterized in that chitosan hydrochloride is used as a capsule material, ammonium polyphosphate is used as a core material, the mass ratio of the chitosan hydrochloride to the core material is 3: 1, the ammonium polyphosphate is added into a chitosan hydrochloric acid solution after being subjected to ultrasonic crushing, and the microencapsulated ammonium polyphosphate with flame retardant property is prepared by a physical coating method. The prepared microcapsule can be applied to paper sheets or high polymer materials to obtain better flame retardance. The invention provides a method which is relatively simple to operate and has important significance for preparing the microencapsulated flame retardant with good flame retardance.

Description

Preparation method of microencapsulated flame retardant

Technical Field

The invention belongs to the field of flame retardant materials, and particularly relates to a preparation method of a microcapsule with good flame retardant property.

Technical Field

Since the security requirements of the modern society are higher and higher, researchers have been devoted to research on flame retardants from the nineties of the last century so as to impart flame retardancy to flammable materials and ensure the safety of lives and properties of people. After halogen flame retardants and metal flame retardants, phosphorus flame retardants are widely used due to their advantages of cleanness, environmental protection and good flame retardant effect, wherein ammonium polyphosphate is the most commonly used, but ammonium polyphosphate also has some problems, such as poor dispersibility, influence on material strength and the like.

Disclosure of Invention

The invention aims to prepare a flame retardant with an affinity shell to improve the utilization efficiency of the flame retardant and further reduce the using amount of the flame retardant, and is characterized by comprising the following steps of:

step 1: taking 0.5g-3g of chitosan hydrochloride, adding deionized water to dilute to 300ml-1000ml, and forming a uniform chitosan hydrochloride solution;

step 2: dispersing 0.1-0.5 g of ammonium polyphosphate into 100-500 ml of deionized water, carrying out ultrasonic crushing treatment for 2-20 min, adding into the chitosan hydrochloride solution obtained in the step 1, and stirring for 0.5-1.5 h to form an ammonium polyphosphate microcapsule suspension system with a chitosan hydrochloride shell;

and step 3: carrying out suction filtration and washing on the suspension prepared in the step 2, and taking a filter cake to obtain an ammonium polyphosphate microcapsule with a chitosan hydrochloride shell;

and 4, step 4: and (3) carrying out a flame retardance test on the microencapsulated flame retardant obtained in the step (3).

The medicine is high poly ammonium polyphosphate with the purity of 90-99 percent and chitosan hydrochloride solid with the purity of 80-99 percent.

The preferable mass ratio of the medicine is ammonium polyphosphate to chitosan hydrochloride is 1: 3

The concentration of the chitosan hydrochloride solution is preferably 0.5 wt%

The prepared microencapsulated flame retardant has a good core-shell structure, and when the addition amount of the microcapsules reaches 30%, the microencapsulated flame retardant is applied to the surface of a handsheet to enable the paper sheet to obtain good flame retardance.

The chitosan hydrochloride is used as the capsule wall material, and certain flame retardance is provided while the ammonium polyphosphate particles are coated; meanwhile, the cationic charge microcapsules with higher chitosan hydrochloride are easier to adsorb on the surface of the material, so that the loss of the flame retardant is reduced; ammonium polyphosphate serving as a core material provides good flame retardance and is decomposed in a heating process; nitrogen is released, the reaction temperature is reduced, and meanwhile oxygen is isolated, so that the combustion is prevented from continuing. The invention provides a method which is relatively simple to operate and has important significance for preparing the flame retardant with good flame retardant performance, reducing the consumption of the traditional flame retardant and saving the cost.

Drawings

FIG. 1 is a scanning electron micrograph of microencapsulated ammonium polyphosphate; FIG. 2 is a scanning electron micrograph (a) of microencapsulated ammonium polyphosphate and the distribution of phosphorus (b), carbon (c), nitrogen (d), and oxygen (e) in the microcapsules

Detailed Description

The following examples are intended to enable those skilled in the art to better understand the present invention, but are not intended to limit the present invention in any way.

The vertical combustion tester of each embodiment is an ZBY-1 type vertical combustion tester; . And are not intended to limit the invention.

Example 1

A preparation method of microcapsules with good flame retardant property comprises the following steps:

1) adding chitosan hydrochloride powder into 600ml deionized water, and stirring for 30min under the condition of 300rpm/min to obtain a uniform solution;

2) adding ammonium polyphosphate suspension subjected to ultrasonic treatment for 6min into the solution prepared in the step (1), wherein the mass ratio of ammonium polyphosphate to chitosan hydrochloride is 1: 3, and fully stirring to obtain microencapsulated ammonium polyphosphate; and carrying out suction filtration and washing to obtain the ammonium polyphosphate microcapsule containing a small amount of water.

3) Adding the microcapsule obtained in the step (2) into a carboxyl modified nano-cellulose-containing turbid liquid, continuously stirring to uniformly mix the substances, and pouring the mixed solution into a mould, wherein the mass ratio of the carboxyl modified nano-cellulose to the microencapsulated ammonium polyphosphate is 7: 3;

3) placing the mold into an oven, and drying at 60 deg.C for 2.5 hr to obtain a quantitative content of 30g/m²The film material of (1);

4) transferring the membrane material to a quantitative of 100g/m²High strength flame retardant paper (No. 1) was prepared on the surface of the handsheet of (a), and a vertical burning test was performed on the paper sample and compared with the results of the vertical burning test of a handsheet without a film material (blank) (table 1).

TABLE 1 vertical burn test results for the samples

As can be seen from table 1, the coupon sheet not carrying the microcapsules had a relatively short afterflame time and ignition time due to complete combustion, and the char length was the actual length of the sample, and the ash content was very small. But the flame self-extinguishing time (i.e. average flame-holding time) was 5.5s after the addition of the flame retardant; the average flame burning time is shortened to 6 s; the average carbonization length is shortened from 200mm to 65mm, the ash content is obviously increased, and the carbonization phenomenon is obvious. The flame retardant on the surface of the paper sheet changes the decomposition mode of the fiber in the combustion process, promotes the dehydration and carbonization of the fiber, thereby reducing the heat release amount of combustion, simultaneously, the carbonized fiber forms a compact carbonized layer on the surface of the unburned fiber, reducing the contact area of combustible materials, and simultaneously playing a certain role in isolating oxygen.

Example 2

3) adding chitosan hydrochloride powder into 600ml deionized water, and stirring for 30min under the condition of 300rpm/min to obtain a uniform solution;

4) adding ammonium polyphosphate suspension subjected to ultrasonic treatment for 6min into the solution prepared in the step (1), wherein the mass ratio of ammonium polyphosphate to chitosan hydrochloride is 1: 3, and fully stirring to obtain microencapsulated ammonium polyphosphate; and carrying out suction filtration and washing to obtain the ammonium polyphosphate microcapsule containing a small amount of water.

3) Adding the microcapsule obtained in the step (2) into a carboxyl modified nano-cellulose-containing suspension, continuously stirring to uniformly mix the suspension, and pouring the mixed solution into a mould, wherein the mass ratio of the carboxyl modified nano-cellulose to the microencapsulated ammonium polyphosphate is 1: 1;

4) transferring the membrane material to a quantitative of 100g/m²High strength flame retardant paper (No. 2) was prepared on the surface of the handsheet of (a), and a vertical burning test was performed on the paper sample and compared with the results of the vertical burning test of the handsheet without the film material (blank) (table 2).

TABLE 2 vertical burn test results for the samples

As can be seen from table 2, the coupon sheet not carrying the microcapsules had a relatively short afterflame time and ignition time due to complete combustion, and the char length was the actual length of the sample, and the ash content was very small. But after the flame retardant is added, the flame self-extinguishing time (namely the average flame-holding time) is 1 s; the average flame burning time is shortened to 3.5 s; the average carbonization length is shortened from 200mm to 50mm, the ash content is obviously increased, and the carbonization phenomenon is obvious. The flame retardant on the surface of the paper sheet changes the decomposition mode of the fiber in the combustion process, promotes the dehydration and carbonization of the fiber, thereby reducing the heat release amount of combustion, simultaneously, the carbonized fiber forms a compact carbonized layer on the surface of the unburned fiber, reducing the contact area of combustible materials, and simultaneously playing a certain role in isolating oxygen.

Claims

1. A preparation method of a microencapsulated flame retardant is characterized by comprising the following steps:

the mass ratio of the chitosan hydrochloride to the ammonium polyphosphate is 3: 1.

2. The method as set forth in claim 1, wherein the concentration of the chitosan hydrochloride solution is < 5 wt%.

3. The method as set forth in claim 1, wherein the ammonium polyphosphate ultrasonication time is 2min to 20 min.

4. The method as set forth in claim 1, wherein the suspension of ammonium polyphosphate is at a concentration of < 5 wt%.