WO2025241626A1 - Halogen-free flame-retardant acrylic acid material containing amino acid, and preparation method therefor - Google Patents

Abstract

A halogen-free flame-retardant acrylic acid material containing an amino acid. A preparation method therefor comprises the following steps: (1) emulsification and dispersion: respectively adding deionized water, an emulsifier, an acrylate monomer, an initiator and a flame-retardant monomer into an emulsifying kettle, and stirring the mixture for 30-60 minutes after the addition is finished, to perform emulsification and dispersion, so as to prepare an emulsified liquid; (2) nucleophilic addition reaction: adding the emulsified liquid into a reaction kettle, heating same to 30-60°C, and then adding an amino acid thereto, wherein the temperature of the reaction system is maintained constant during the process until the reaction is finished; (3) curing and degassing the reacted materials, and then filtering same to obtain an acrylate emulsion containing an amino acid; (4) adding a defoaming agent and a thickening agent into the emulsion in step (3), and adjusting the product quality; and (5) filtering and filling the materials to obtain a flame-retardant material.

Description

A halogen-free flame-retardant acrylic material containing amino acids and its preparation method Technical Field

This invention relates to the field of fine chemical technology, and in particular to a halogen-free flame-retardant acrylic material containing amino acids and its preparation method.

Background Technology

The halogen-free transformation of flame retardants has become an irresistible historical trend. While halogenated flame retardants offer the advantage of high cost-effectiveness, they produce large amounts of toxic and corrosive gases during combustion, raising concerns about their environmental impact. Current research is moving towards greener and more environmentally friendly flame retardants, with bio-based flame retardants gradually becoming the mainstream research direction. However, simultaneously ensuring both flame retardant efficiency and durability remains a challenge. Therefore, high-performance bio-based hydrophobic flame retardants are urgently needed functional products in the current market.

Amino acids, as a common and diverse class of small molecule compounds, are the basic building blocks of proteins, biological functional macromolecules. Amino acids are widely available, abundant, and structurally diverse, containing both amino and carboxyl groups. The amino group can serve as a reaction site, allowing for the synthesis of nitrogen-containing flame retardants with high design flexibility. Traditional techniques utilize the combination of glycine and a triazine ring to prepare a synergist for use in intumescent flame retardant systems. Patent CN111440357B discloses a fully bio-based flame retardant, a flame-retardant PLA composite material, and its preparation method, using phytic acid and sulfur-containing amino acids from biological sources to synthesize the fully bio-based flame retardant. Patent CN114249768A uses the reaction of amino acids with aldehydes and phosphorus-containing compounds to prepare a phosphorus-based flame retardant based on amino acids. However, the above-mentioned bio-based flame retardant technologies are not yet perfect, mainly due to the relatively complex reaction systems and the need for further improvement in overall flame retardant performance.

Therefore, the main technical problems existing in flame retardant systems are:

(1) Halogenated flame retardants produce a large amount of toxic and corrosive gases when burning, which are harmful to the environment and human body.

(2) Bio-based flame retardant technology is not yet perfect, and the flame retardant effect needs to be improved.

Summary of the Invention

The purpose of this invention is to solve the above-mentioned problems by providing an amino acid-containing halogen-free flame retardant acrylic material and its preparation method.

The objective of this invention is achieved through the following technical solution:

A halogen-free flame-retardant acrylic material containing amino acids, characterized in that the flame-retardant material is prepared by reacting amino acids and acrylate emulsions as raw materials; and has a structure represented by the following formula:

_R1 = CHCONH - _R2

Where _R1 is an acrylate emulsion unit and _R2 is an amino acid unit.

The amino acid is at least one selected from glycine, phenylalanine, tyrosine, arginine, aspartic acid, glutamic acid, lysine, threonine, serine, and tryptophan.

The method for preparing the flame-retardant material is characterized by comprising the following steps:

① Emulsification and dispersion: Deionized water, emulsifier, acrylate monomer, initiator and flame retardant monomer are added to the emulsification kettle. After the addition is complete, the mixture is stirred for 30-60 minutes to emulsify and disperse, and an emulsion is obtained.

② Nucleophilic addition reaction: Add emulsion to the reaction vessel, raise the temperature to 30~60℃, then add amino acids, keeping the temperature of the reaction system constant during the process until the reaction is completed;

③After the reacted material is cured and degassed, it is filtered to obtain an acrylate emulsion containing amino acids;

④ Add defoamer and thickener to the emulsion in ③ to adjust the product quality;

⑤ The materials are filtered and filled to obtain flame-retardant materials.

The molar ratio of the amino acid to the acrylate emulsion is 1:0.8 to 1:8.

The acrylate emulsion is prepared from the following raw materials in parts by weight: 50-60 parts acrylate monomer, 5-8 parts emulsifier, 0.5-1.0 parts initiator, 2-10 parts flame retardant monomer, and 30-40 parts deionized water.

The thickener is 1-3 parts.

The defoamer is 0.5-1 part.

In the raw materials for preparing the acrylate emulsion, the acrylate monomers are a mixture of acrylic acid, ethyl acrylate, butyl acrylate, and methyl methacrylate; preferably, the mass ratio of acrylic acid, butyl acrylate, ethyl acrylate, methyl methacrylate, and vinyl acetate is 2:1:1:1.

The flame-retardant monomer is at least one of ammonium polyphosphate, phosphate ester, tricresyl phosphate, melamine, and urea.

The emulsifier is at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate;

Preferably, the initiator is at least one of sodium persulfate, potassium sulfate, or ammonium persulfate;

Preferably, the thickener is a polyacrylate-based alkaline thickener;

Preferably, the defoamer is a mineral oil defoamer or an organosilicone defoamer.

During the polymerization reaction of the acrylic emulsion preparation, the temperature of the reaction system is controlled at 40~50℃.

In step ④, when adding defoamer and thickener to the reaction solution, a bactericide may also be added. Potassium sorbate and sodium benzoate are preferred bactericides.

The amino acid-containing halogen-free acrylic flame retardant material of the present invention has good mechanical properties, excellent flame retardant function and durability, and has good application prospects in materials such as cotton fabrics.

The amino acid-containing halogen-free acrylic flame retardant material of the present invention has the following mechanism:

1. Acrylic ester emulsions acquire certain flame retardant properties by combining with flame retardant monomers.

2. The carboxyl groups in amino acids can undergo dehydration reactions with the char source during heating, promoting the formation of more char. Through the nucleophilic addition reaction between acrylate emulsion and amino acids, its structure plays a role in regulating the ratio and interaction between acid source, char source, and gas source in the flame retardant system.

Meanwhile, the acrylate monomers, a mixture of acrylic acid, ethyl acrylate, butyl acrylate, and methyl methacrylate, can improve the polymer's adhesive properties and coating adhesion, providing a foundation for the later-stage crosslinking and curing of the emulsion. This facilitates the transfer of monomers from droplets to micelles during the reaction, acting as a "bridge transport" and thus increasing the reaction rate. The emulsifier reduces the interfacial tension between the oil and aqueous phases in emulsion polymerization and, through its emulsifying effect, produces a stable emulsion system. Therefore, the amino acid-containing halogen-free acrylic flame-retardant material prepared in this application possesses good mechanical properties, excellent flame-retardant function, and durability.

Detailed Implementation

The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. It should be noted that, unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available products. To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below.

Preparation Example 1

The following raw materials were prepared in parts by weight: 50 parts acrylate monomer, 5 parts emulsifier (sodium dodecylbenzenesulfonate), 0.5 parts initiator (sodium sulfate), 40 parts deionized water, and 2 parts flame-retardant monomer (ammonium polyphosphate). The acrylate monomers were acrylic acid, butyl acrylate, ethyl acrylate, and methyl methacrylate, in a mass ratio of 2:1:1:1. The preparation method is as follows:

Add the above-mentioned mass fractions of deionized water, emulsifier, acrylate monomer, and flame retardant monomer to the emulsification kettle. After the addition is complete, stir for 30 minutes to emulsify and disperse, and obtain an emulsion.

Preparation Example 2

The following raw materials were prepared in parts by weight: 60 parts acrylate monomer, 8 parts emulsifier (sodium dodecyl sulfate), 1 part initiator (potassium sulfate), 35 parts deionized water, and 10 parts flame-retardant monomer (tricresyl phosphate). The acrylate monomers were acrylic acid, butyl acrylate, ethyl acrylate, and methyl methacrylate, in a mass ratio of 2:1:1:1. The preparation method is as follows:

Add the above-mentioned mass fractions of deionized water, emulsifier, acrylate monomer, and flame retardant monomer to the emulsification kettle. After the addition is complete, stir for 60 minutes to emulsify and disperse, and obtain an emulsion.

Preparation Example 3

The following raw materials were prepared in parts by weight: 55 parts acrylate monomer, 6 parts emulsifier (sodium dodecyl sulfate), 0.8 parts initiator (ammonium persulfate), 30 parts deionized water, and 6 parts flame-retardant monomer (melamine). The acrylate monomers were acrylic acid, butyl acrylate, ethyl acrylate, and methyl methacrylate in a mass ratio of 2:1:1:1. The preparation method is as follows:

Add the above-mentioned mass fractions of deionized water, emulsifier, acrylate monomer, and flame retardant monomer to the emulsification kettle. After the addition is complete, stir for 50 minutes to emulsify and disperse, and obtain an emulsion.

In the above preparation examples

Emulsions can be obtained by replacing the flame retardant monomer with phosphate esters, urea, or mixtures thereof.

Example 1

Take the following raw materials in parts by weight: 55 parts of the acrylate emulsion obtained in Preparation Example 2, 110 parts of amino acids, 1 part of thickener (alkaline thickener of polyacrylate), and 0.5 parts of defoamer (mineral oil defoamer).

The preparation method of amino acid-containing halogen-free flame-retardant acrylic materials is as follows:

① Emulsification and dispersion: Deionized water, emulsifier, acrylate monomer, initiator and flame retardant monomer are added to the emulsification kettle. After the addition is complete, the mixture is stirred for 30-60 minutes to emulsify and disperse, and an emulsion is obtained.

② Nucleophilic addition reaction: Add emulsion to the reaction vessel, raise the temperature to 30°C, then add phenylalanine, keeping the temperature of the reaction system constant until the reaction is complete;

③After the reacted material is cured and degassed, it is filtered to obtain an acrylate emulsion containing amino acids;

④ Add defoamer and thickener to the emulsion in ③ to adjust the product quality;

⑤ The materials are filtered and filled to obtain flame-retardant materials.

Note: After the reaction in step ②, infrared detection showed an infrared absorption peak corresponding to the amide group (-CONH-) at around 3100 ^cm⁻¹ .

Examples 2-5

Take the components in the mass fractions shown in Table 1:

Table 1. Raw material composition ratio of amino acid-containing halogen-free acrylic flame retardant materials in Examples 2-5

Flame-retardant materials containing acrylate emulsions were prepared using the preparation method described in Example 1.

Comparative Example 1

The flame-retardant material was prepared according to the method of Example 1 in patent document CN114249768A. The amount of amino acids used was the same as in Example 1.

Comparative Example 2

After the emulsion in Preparation Example 1 of this application was aged and degassed, filtered, and then an antifoaming agent and a thickener were added to obtain a flame retardant material.

Test Example 1

The afterflame time and limiting oxygen index of the flame-retardant materials prepared in Examples 1-5 and Comparative Examples 1-2 were compared as follows:

The products obtained in Examples 1-5 and Comparative Examples 1-2 were used as soaking solutions for cotton fabrics. The cotton fabrics were soaked in the above solutions at 70°C for 1 hour, with a mass ratio of cotton fabric to flame retardant material (emulsion) of 1:20. After soaking, the cotton fabrics were passed through a roller to maintain a liquid retention rate of 100%. The cotton fabrics were then passed through a continuous setting dryer at 190°C for 5 minutes. Finally, the flame retardant material (emulsion) adhering to the surface of the cotton fabrics was washed off, and the fabrics were dried in an oven at 60°C. The above procedure was repeated once. The limiting oxygen index (ASTM D2863-2000), vertical burning test (ASTM D6413-99), and fabric flame retardancy and wash resistance test (AATCC 61-2006) of the cotton fabrics were tested. The test results are shown in Table 2.

Table 2. Afterflame time and limiting oxygen index test results of the flame retardant materials obtained in Examples 1-5 and Comparative Examples 1-2

Analysis of the data in the table above shows that the products prepared in the embodiments of the present invention have excellent flame retardancy and durability. All embodiments exhibit high oxygen indices, with the highest limiting oxygen index reaching 44.2%. Even after 50 washes, the limiting oxygen index remains at a maximum of 34.3%, meeting the flame retardant standard for cotton fabrics. Compared to Comparative Examples 1 and 2, they demonstrate better synergistic flame retardant effects.

The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims (10)

A halogen-free flame-retardant acrylic material containing amino acids, characterized in that the flame-retardant material is prepared by reacting amino acids and acrylate emulsions as raw materials; and has a structure represented by the following formula: _R1 = CHCONH - _R2 Where _R1 is an acrylate emulsion unit and _R2 is an amino acid unit. The flame retardant material according to claim 1 is characterized in that the amino acid is at least one selected from glycine, phenylalanine, tyrosine, arginine, aspartic acid, glutamic acid, lysine, threonine, serine, and tryptophan. The method for preparing flame-retardant materials according to any one of claims 1-2 is characterized by comprising the following steps: ① Emulsification and dispersion: Deionized water, emulsifier, acrylate monomer, initiator and flame retardant monomer are added to the emulsification kettle. After the addition is complete, the mixture is stirred for 30-60 minutes to emulsify and disperse, and an emulsion is obtained. ② Nucleophilic addition reaction: Add emulsion to the reaction vessel, raise the temperature to 30~60℃, then add amino acids, keeping the temperature of the reaction system constant during the process until the reaction is completed; ③After the reacted material is cured and degassed, it is filtered to obtain an acrylate emulsion containing amino acids; ④ Add defoamer and thickener to the emulsion in ③ to adjust the product quality; ⑤ The materials are filtered and filled to obtain flame-retardant materials. The flame-retardant material according to any one of claims 1-3 is characterized in that the acrylate emulsion is prepared from the following raw materials in parts by weight: 50-60 parts of acrylate monomer, 5-8 parts of emulsifier, 0.5-1.0 parts of initiator, 2-10 parts of flame-retardant monomer, and 30-40 parts of deionized water; 1-3 parts of thickener; and 0.5-1 parts of defoamer. The flame-retardant material according to any one of claims 1-4 is characterized in that the mass ratio of the amino acid to the acrylate emulsion is 1:0.5 to 1:10. The flame retardant material according to any one of claims 3-5 is characterized in that, in the raw materials for preparing the acrylate emulsion, the acrylate monomer is a mixture of acrylic acid, ethyl acrylate, butyl acrylate, and methyl methacrylate; preferably, the mass ratio of acrylic acid, butyl acrylate, ethyl acrylate, methyl methacrylate, and vinyl acetate is 2:1:1:1. The flame-retardant material according to any one of claims 3-6 is characterized in that the flame-retardant monomer is at least one selected from ammonium polyphosphate, phosphate ester, tricresyl phosphate, melamine, and urea; Preferably, the emulsifier is at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate; Preferably, the initiator is at least one of sodium persulfate, potassium sulfate, or ammonium persulfate; Preferably, the thickener is a polyacrylate-based alkaline thickener; Preferably, the defoamer is a mineral oil defoamer or an organosilicone defoamer. The method for preparing flame-retardant materials according to claim 3 is characterized in that, during the polymerization reaction of the acrylic emulsion, the temperature of the reaction system is controlled at 40~50℃. The method for preparing flame-retardant materials according to any one of claims 3-6 is characterized in that, in step ④, when adding defoamer and thickener to the reaction solution, bactericide may also be added; wherein the bactericide is preferably potassium sorbate or sodium benzoate. The application of the amino acid-containing halogen-free flame-retardant acrylic material as described in claim 1 or 3 in cotton fabric materials.