CN114409909B

CN114409909B - Sulfur-containing intumescent flame retardant and preparation method thereof

Info

Publication number: CN114409909B
Application number: CN202210097255.9A
Authority: CN
Inventors: 倪恨美; 周川; 郭剑桥
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2022-01-26
Filing date: 2022-01-26
Publication date: 2023-08-04
Anticipated expiration: 2042-01-26
Also published as: CN114409909A

Abstract

The invention discloses a sulfur-containing intumescent flame retardant and a preparation method thereof, aiming at replacing toxic phosphorus element with sulfur element in a catalytic acid source. The preparation method is characterized in that raw materials such as environment-friendly melamine, sodium sulfanilate, carboxymethyl cellulose and the like are selected, and the polymer intumescent flame retardant connected through covalent bonds is obtained through aldol condensation. The invention has small addition amount and good flame retardant effect through sulfur nitrogen synergistic flame retardance, and is suitable for materials such as polyurethane, epoxy resin and the like. The preparation process is simple and is suitable for large-scale production and application.

Description

Sulfur-containing intumescent flame retardant and preparation method thereof

Technical Field

The invention relates to a high molecular auxiliary agent and a preparation method thereof, in particular to a sulfur-nitrogen synergistic flame retardant and a preparation method thereof.

Background

The polymer material has penetrated into various aspects of human life, and the inflammability of the polymer material often threatens the human life while bringing various performances such as portability, comfort, attractive appearance and the like to the human, so that the flame retardant modification is the most important part in the application link of the polymer material, and the requirement on the flame retardant is higher and higher due to the importance of environmental protection along with the development of modern civilization.

From the development history of flame retardants, halogen flame retardants occupy more than 80% of the flame retardant market due to the characteristics of good flame retardant effect, small filling amount, low price and the like. However, since the beginning of the 80 s of the 20 th century, researchers have found that halogen is the main catalyst for the production of environmental dioxins, and thus the use of halogen-containing flame retardants was globally prohibited in the beginning of the 21 st century. Instead, phosphorus-containing flame retardants become the mainstream product, now accounting for 90% of the market share of flame retardants. However, the phosphorus-containing organic matter itself is either a nerve agent or is at risk of producing nerve agents under the promotion of various factors of the natural environment. Thus, the application of the phosphorus-containing compound as the flame retardant is at the beginning of raising the vigilance of environmental protection researchers, and the current wide application is completely inequality.

From the development of environmental awareness, the current environmental protection scope is not limited to oceans, rivers and open fields, but is deep into small spaces for individual activities of human beings, such as decorations, furniture, clothes, appliances and the like in public places, families, production workshops and the like, so that the concept of full life cycle environmental protection is provided for the polymer materials, namely, environmental protection is required in the production process, the use process and the waste process. In particular to a flame retardant, the production process is required to generate no dust or harmful gas and the like; dust, volatilization, dialyzate and the like are not generated in the using process; no toxic substances are produced after the waste. A number of research reports have now emerged. Dust studies for large urban households of various countries indicate that: the dust contains organic phosphorus components, which may be harmful to human health when exposed for a long time.

In conclusion, just as the use of phosphorus-containing detergents was completely prohibited in the beginning of the 21 st century, the time of prohibiting the use of phosphorus-containing organic flame retardants became long.

Elemental sulfur has more outstanding properties in terms of flame retardance than elemental phosphorus, but has long been excluded from flame retardant applications because of the generation of toxic gases such as sulfur dioxide during combustion. However, from a macroscopic point of view, mass-produced flame retardants rarely function in applications, i.e. are burned out in the event of a fire, and thus exert a flame-retarding effect. The final fate of most flame retardants is to follow the waste polymeric materials, either recovered or discarded in the environment at the discretion of the wind and sun. This is just an advantage of sulfur-containing organics: stable and nontoxic, and can not generate toxic compounds in the environment.

Based on the above-mentioned points, substitution of phosphorus element with sulfur element is an unwieldy choice from the viewpoint of "two harmfulness" and light weight.

Disclosure of Invention

The invention aims to: the invention aims to provide a sulfur-containing intumescent flame retardant with high flame retardant efficiency.

It is another object of the present invention to provide a method for preparing the flame retardant.

The technical scheme is as follows: the sulfur-nitrogen synergistic intumescent flame retardant has the following chemical structural formula:

the preparation method of the intumescent flame retardant comprises the following steps:

(1) Polyhydroxy compounds such as isovaleryl alcohol, polyglycidyl alcohol, polyvinyl alcohol, chitin, various celluloses (e.g., carboxymethyl cellulose) and the like are selected as carbon sources.

(2) Amino-containing benzenesulfonate, mercapto and thiophene compounds are selected as acid sources. For example, sodium aminobenzenesulfonate, sodium aminododecylsulfate, aminotetrathiol, aminopolysulfide, 3-aminothiophene, derivatives thereof, and the like.

(3) Melamine was selected as the gas source.

(4) An aldehyde or anhydride compound is selected as a reactant to link the compounds together to form a compound. For example, formaldehyde is added to carry out aldol condensation reaction to obtain a product, or acetic anhydride or phthalic anhydride is added to carry out acylation reaction, and similar acylation products are obtained.

In the step (1), carboxymethyl cellulose is dissolved in water at normal temperature, and the mass ratio of the carboxymethyl cellulose to the water is 5:1000.

Further, in the step (2), sodium sulfanilate, melamine and formaldehyde are magnetically stirred for 1-2 hours at the temperature of 30-50 ℃ to obtain an intermediate product.

Further, the molar ratio of the sodium sulfanilate to the melamine to the formaldehyde is 1:1:2.

Further, in the step (3), the carboxymethyl cellulose solution and the prepared intermediate product are magnetically stirred for 24 hours at 50 ℃ to obtain the intumescent flame retardant.

Principle of: the intumescent flame retardant is prepared by taking carboxymethyl cellulose as a char forming agent, sodium sulfanilate as a dehydrating agent, melamine as a foaming agent and aldol condensation reaction, so that the flame retardant efficiency is improved.

The beneficial effects are that: compared with the prior art, the invention has the following advantages:

the sulfur-based flame retardant has good flame retardant effect and less harm. Meanwhile, the carboxymethyl cellulose is polysaccharide with very rich content, is low in price, and accords with the concept of green and environment-friendly development.

Drawings

FIG. 1 is an infrared spectrum of an intumescent flame retardant;

FIG. 2 is a thermogravimetric analysis of intumescent flame retardant.

Detailed Description

Example 1:

the preparation method of the intumescent flame retardant provided by the embodiment comprises the following steps:

(1) Dissolving 5 parts of carboxymethyl cellulose in 1000 parts of water to obtain carboxymethyl cellulose solution;

(2) 1mol of sodium sulfanilate and 1mol of melamine are magnetically stirred for 1h at 50 ℃ and dissolved in 2mol of 37% formaldehyde aqueous solution to obtain an intermediate product;

(3) And magnetically stirring the carboxymethyl cellulose solution and the prepared intermediate product at 50 ℃ for 24 hours to obtain the intumescent flame retardant.

The chemical structural formula of the intumescent flame retardant provided in this example is tested as follows:

fig. 1 is an infrared spectrum of the intumescent flame retardant provided in this example.

As shown in the figure, the wave number is 3000-3500cm ^-1 The peak fluctuation in the range is small, indicating that-OH is basically replaced by monomer; at wave number 1605cm ^-1 The characteristic peak at c=o at 1124cm wavenumber ^-1 The characteristic peak of the ether is shown to indicate aldol condensation; at wave number 1088cm ^-1 At which is-SO ₃ Characteristic peaks of H.

Fig. 2 is a thermogravimetric analysis of the intumescent flame retardant provided in this example.

As shown, the intumescent flame retardant has a thermal weight loss of 5% at 190.2 ℃; at 490.5 ℃, the thermal weight loss reaches 50 percent. When the thermal decomposition temperature reached 800 ℃, the carbon residue of the intumescent flame retardant was 30.5%.

Example 2:

the intumescent flame retardant and the aqueous polyurethane were mixed at 50 ℃ according to the following ratio of table 1, thoroughly and uniformly mixed with mechanical stirring, and then the solution was introduced into a custom polytetrafluoroethylene mold to prepare a standard sample. According to GB/T2408-2008 standard, the vertical burning condition of the flame-retardant aqueous polyurethane sample is measured.

Table 1WPU formulation

Sample of	Waterborne polyurethane/%	Flame retardant/%
			WPU	100	0
WPU1	98	2％
			WPU2	97	3％
WPU3	96	4％

The results are shown in the following Table 2, the flame retardant rating of the aqueous polyurethane without flame retardant is HB rating only, and the dripping occurs; when the addition amount of the flame retardant is 3%, the flame retardant grade reaches V-1, and no molten drop appears. And the better the flame retardant effect as the content of the flame retardant is increased.

Table 2 vertical burn test data

Sample of	Flame retardant additive/%	UL-94	Molten drop
				WPU	0	HB	Yes
WPU1	2％	V-1	No
				WPU2	3％	V-1	No
WPU3	4％	V-0	No

Claims

1. A preparation method of a sulfur-containing intumescent flame retardant is characterized in that:

(1) Selecting a polyhydroxy compound as a carbon source;

(2) Selecting benzene sulfonate, mercapto or thiophene compound containing amino as acid source;

(3) Melamine is selected as a gas source;

(4) An aldehyde or anhydride compound is selected as a reactant to link the compounds together to form a compound.

2. The method for preparing the sulfur-containing intumescent flame retardant as claimed in claim 1, characterized in that: in the step (1), carboxymethyl cellulose is dissolved in water at normal temperature, and the mass ratio of the carboxymethyl cellulose to the water is 5:1000.

3. the method for preparing the sulfur-containing intumescent flame retardant as claimed in claim 1, characterized in that: in the step (2), sodium sulfanilate, melamine and formaldehyde are magnetically stirred for 1-2 hours at the temperature of 30-50 ℃ to obtain an intermediate product.

4. The method for preparing the sulfur-containing intumescent flame retardant as claimed in claim 1, characterized in that: in the step (2), the molar ratio of the sodium sulfanilate to the melamine to the formaldehyde is 1:1:2.

5. the method for preparing the sulfur-containing intumescent flame retardant as claimed in claim 1, characterized in that: in the step (3), the carboxymethyl cellulose solution and the intermediate product are magnetically stirred for 24 hours at 50 ℃ to obtain the intumescent flame retardant.

6. The sulfur-containing intumescent flame retardant of any of claims 1-5.