CN111608013A

CN111608013A - Flame-retardant paper and preparation method thereof

Info

Publication number: CN111608013A
Application number: CN201911251263.9A
Authority: CN
Inventors: 吴敏; 黄勇; 张同玲
Original assignee: Technical Institute of Physics and Chemistry of CAS
Current assignee: Technical Institute of Physics and Chemistry of CAS
Priority date: 2019-02-26
Filing date: 2019-12-09
Publication date: 2020-09-01

Abstract

The invention relates to flame-retardant paper and a preparation method thereof, belonging to the technical field of papermaking. The invention firstly provides a flame retardant which is prepared by reacting chitosan with ammonium dihydrogen phosphate, wherein the reaction temperature is 95-100 ℃; the molar ratio of the chitosan to the ammonium dihydrogen phosphate is 1 (4-10). The invention also provides flame-retardant paper prepared from the flame retardant. The flame-retardant paper prepared by the invention has good flame-retardant effect and higher strength, and the paper also has good antibacterial performance; and has the characteristics of good thermal stability, char formation and the like, and has excellent flame retardant effect.

Description

Flame-retardant paper and preparation method thereof

Technical Field

The invention relates to flame-retardant paper and a preparation method thereof, belonging to the technical field of papermaking.

Background

In recent years, with the depletion of petroleum resources, people are turning their attention to natural polymer materials. As is well known, cellulose is a natural polymer material which is most abundant in natural resources in nature, and has good biodegradability and biocompatibility. At present, the application of cellulose mainly comprises the aspects of paper, packaging boxes, film materials, reinforced materials and the like, wherein the paper is one of the most extensive application modes of the cellulose. At present, many data exist in a paper form, and the paper has a very combustible property, so that great economic loss, personal safety and irretrievable data can be caused when a fire disaster happens, and the preparation of the flame-retardant paper has important research significance.

The preparation method of the flame-retardant paper is mainly realized by surface modification of cellulose fibers or direct addition of a flame retardant. The direct-use flame retardant is convenient to use, and different amounts of flame retardants can be added according to the use requirements so as to meet the requirements. The mixing of the flame retardant with the base material mainly comprises mechanical mixing and coating, wherein the coating is carried out by coating the surface of the finished material with a layer of flame retardant. The method is simple and convenient to operate, and therefore, the method is widely used.

Disclosure of Invention

Based on the intensive research on the flame retardance of paper, the invention unexpectedly discovers that a reaction product prepared from chitosan and ammonium dihydrogen phosphate has a very excellent flame-retardant effect, and the antibacterial property of the paper is remarkably improved. The invention is particularly proposed.

Specifically, the invention firstly provides a flame retardant which is prepared by reacting chitosan with ammonium dihydrogen phosphate. The reaction temperature is preferably 95 to 100 ℃ and more preferably 95 ℃.

Further, the reaction is carried out in a system with 1 wt% to 3 wt% of acetic acid solution as a solvent, the reaction time is preferably enough to allow the two to react, and the reaction time is preferably about 1 h.

In order to accelerate the reaction speed, the chitosan can be dissolved by 1 wt% -3 wt% acetic acid solution in advance.

Further, the molar ratio of the chitosan to the ammonium dihydrogen phosphate is 1 (4-10), and specifically can be 1:4, 1:6, 1:8 or 1: 10; preferably 1: 8.

Specifically, 1-3 wt% acetic acid solution is used for dissolving chitosan, then a proper amount of ammonium dihydrogen phosphate is added, reflux reaction is carried out (the temperature is about 95 ℃) for about 1-2 hours, white precipitate is obtained by cooling, and the white precipitate is washed to be neutral by deionized water.

The invention also provides application of the flame retardant in preparation of flame-retardant materials. The flame retardant material is preferably paper.

The flame retardant disclosed by the invention is particularly excellent in flame retardance and mechanical property (strength) improvement of paper.

Generally, the flame retardant can be dissolved in an acetic acid solution (e.g., 1 wt% to 3 wt% acetic acid solution) and coated on paper to form flame retardant paper.

Generally, the above flame retardant is coated on paper in an amount of 2.0 wt% to 24.5 wt% or preferably in a coating thickness of 0.001mm to 0.003 mm; uniform coating is preferred.

The coating amount of the invention refers to the percentage of the flame retardant in the total weight of the coated paper.

The flame-retardant paper has good flame-retardant effect and higher strength. It has surprisingly been found that the flame retardant paper also has good antibacterial properties.

The flame retardant paper provided by the invention has the characteristics of good thermal stability, flame retardance, char formation and the like, and has an excellent flame retardant effect.

The starting materials used in the present invention are commercially available or may be prepared by methods conventional in the art.

On the basis of the common knowledge in the field, the above preferred conditions can be combined with each other to obtain the preferred embodiments of the invention.

Drawings

FIG. 1 shows the flame retardant prepared in example 1³¹P NMR chart.

Fig. 2 is a heat release curve of experimental example 2.

FIG. 3 is a thermogravimetric plot of Experimental example 2.

FIG. 4 is a photograph of a test sample of Experimental example 3.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. The examples do not show the specific techniques or conditions, according to the technical or conditions described in the literature in the field, or according to the product specifications. The reagents or instruments used are conventional products available from regular distributors, not indicated by the manufacturer.

Unless otherwise specified, the following chitosans were purchased from Mecanne with a degree of deacetylation of > 95% and a viscosity of 100-.

The filter paper used below was Whatman double-circle qualitative filter paper.

Example 1

Firstly, dissolving chitosan by using 3 wt% acetic acid solution, and then adding ammonium dihydrogen phosphate, wherein the molar ratio of the chitosan to the ammonium dihydrogen phosphate is 1: 8; refluxing and reacting for 1h at 95 ℃, and cooling to obtain white precipitate; washing the precipitate with deionized water to neutrality, and drying to obtain the flame retardant.

Dissolving the flame retardant prepared in the embodiment with 3 wt% acetic acid solution to prepare 4.0 wt% solution, and uniformly coating the solution on filter paper, wherein the coating amount is 24.52 wt%; the coating thickness is about 0.003 mm.

Example 2

Flame retardant, differing from example 1 only in that: the molar ratio of chitosan to ammonium dihydrogen phosphate is 1: 6.

Flame retardant paper, similar to the preparation of example 1, except that the flame retardant prepared in this example was used.

Example 3

Flame retardant, differing from example 1 only in that: the molar ratio of chitosan to ammonium dihydrogen phosphate is 1: 4.

Example 4

Flame retardant, differing from example 1 only in that: the molar ratio of the chitosan to the ammonium dihydrogen phosphate is 1:10

Example 5

Flame retardant, differing from example 1 only in that: the reaction temperature is 100 DEG C

Example 6

Flame retardant, differing from example 5 only in that: the reaction time is 2h

Example 7

Flame retardant, differing from example 3 only in that: the reaction time is 4h

Example 8

Flame retardant, differing from example 4 only in that: the reaction time is 2h

Example 9

Flame retardant, differing from example 2 only in that: the reaction temperature is 100 DEG C

Comparative example 1

Flame retardant paper, similar to the preparation of example 1, except that only chitosan was used as the flame retardant, the coating amount was 20.46 wt%.

Comparative example 2

Flame-retardant paper, similar to the preparation of example 1, except that only ammonium dihydrogen phosphate was used as the flame retardant, the coating amount was 4.06 wt%.

Experimental example 1

Preparation of flame retardant prepared in example 1³¹The P NMR chart is shown in FIG. 1, and the phosphate radical in the flame retardant forms an ionic bond with the ammonium radical ion of chitosan, and the ionic bond³¹P NMR shifted by 0.06ppm to the lower field than diammonium phosphate.

Experimental example 2

The flame retardant papers prepared in example 1 and comparative examples 1 to 2 were subjected to a flame retardant property test, respectively.

1) Curve of heat release

Experimental methods refer to Zope, i.s.; foo, s.; seah, d.g.j.; akuniri, a.t.; dasari, A.development and Evaluation of a Water-Based Flame Retardant Spray coating for coating fabrics ACS Appl Mater Interfaces 2017,9(46), 40782-.

The results of the flame retardant paper heat release curve of the flame retardant prepared in example 1 coated in various amounts are shown in fig. 2a, and the results of the flame retardant paper heat release curve of the flame retardant paper prepared in comparative examples 1-2 are shown in fig. 2 b. In FIG. 2a, the original cellulose paper represents the filter paper without the flame retardant; "24.52 wt% CP" represents that flame retardant paper (flame retardant coating amount 24.52 wt%) was prepared in example 1; "12.62 wt% CP" represents the flame retardant paper coated with the flame retardant prepared in example 1, with the flame retardant coating amount being 12.62 wt% CP; the other meanings are the same as above. In FIG. 2b, the original cellulose paper represents the filter paper without the flame retardant; chitosan stands for flame retardant paper prepared in comparative example 1; NH (NH)₄H₂PO₄Represents the flame retardant paper prepared in comparative example 2; chitosan @ NH₄H₂PO₄Flame retardant paper (flame retardant coating amount 24.52 wt%) was prepared representing example 1.

As can be seen from the heat release curve of FIG. 2a, as the addition amount of the flame retardant increases, the heat release rate gradually decreases, and the maximum heat release rate decreases from 350W/g to 100W/g, indicating that the flame retardant imparts flame retardancy to the paper. As can be seen from the heat release curve of FIG. 2b, the flame retardant effect of the single use of chitosan and ammonium dihydrogen phosphate is not as good as that of the flame retardant prepared in example 1. The flame retardant prepared in the embodiment 1 can reduce the using amount of ammonium dihydrogen phosphate while achieving the flame retardant effect, so that the flame retardant is more environment-friendly.

2) Thermogravimetric curve

Experimental methods refer to Zheng, y.; song, j.; cheng, b.; fang, x.; yuan, Y.preparation and flame recovery of 3- (hydroxypropyl) -propanoic acid esters of cellulose and the ir fibers of cellulose 2014,22(1), 229-.

The results are shown in FIG. 3. Wherein, the meanings of "original cellulose paper", "24.52 wt% CP", "12.62 wt% CP" and the like are the same as those of FIG. 2 a.

As can be seen from the thermogravimetric curve of FIG. 3, the char yield gradually increases as the amount of the flame retardant added increases. The weight percent of the flame retardant is increased to 35 percent from 7 percent of the original paper, which shows that the flame retardant can promote cellulose to form carbon in the combustion process, so that a carbon layer is formed to be used as a physical interlayer, and external oxygen is prevented from entering the interior of the material, so that the combustion is delayed, and the flame retardant effect is achieved.

Experimental example 3 antibacterial Properties

Detecting a sample: flame retardant paper prepared in example 1 (see fig. 4). The control sample was standard PE. The test and control samples were cut into 50mm by 50mm pieces as specified by the standard.

Detecting items: and (4) antibacterial activity value.

The detection basis is as follows: GB/31402-2015 method for testing antibacterial performance of plastic surface

Detection bacteria: escherichia coli (Escherichia coli) ATCC 8739

Staphylococcus aureus (Staphylococcus aureus) ATCC 6538p

The results of the measurements are shown in the following table. The results show that the flame retardant paper prepared in example 1 has good antibacterial properties.

(in the above table, "sample to be inspected" was the flame retardant paper prepared in example 1.)

In conclusion, the flame-retardant paper prepared by the method has flame retardance, better char yield, better thermal stability and better antibacterial property.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. The preparation method of the flame retardant is characterized by comprising the process of reacting chitosan with ammonium dihydrogen phosphate, wherein the reaction temperature is 95-100 ℃.

2. The method of claim 1, wherein the reaction temperature is 95 ℃.

3. The method according to claim 1 or 2, wherein the molar ratio of chitosan to ammonium dihydrogen phosphate is 1 (4-10); preferably 1:4, 1:6, 1:8 or 1: 10.

4. The production method according to any one of claims 1 to 3, wherein the reaction solvent is 1 to 3 wt% acetic acid solution.

5. The process according to any one of claims 1 to 4, which comprises dissolving chitosan in 1 to 3 wt% acetic acid solution, adding an appropriate amount of ammonium dihydrogen phosphate, refluxing, cooling to obtain a white precipitate, and washing with deionized water to neutrality.

6. A flame retardant prepared by the process of any of claims 1-5.

7. Use of the flame retardant of claim 6 for the preparation of flame retardant materials; the flame retardant material is preferably paper.

8. A method of making a flame retardant paper comprising coating the flame retardant of claim 6 on paper.

9. The method of claim 8, wherein the flame retardant is coated in an amount of 2.0 wt% to 24.52 wt% or a coating thickness of 0.001mm to 0.003 mm;

preferably, the flame retardant is uniformly coated on the surface of the paper.

10. A flame retardant paper made by the process of claim 8 or 9.