CN113549310B - A kind of low-smoke flame-retardant polylactic acid composite material and preparation method thereof - Google Patents

Abstract

The invention discloses a low-smoke flame-retardant polylactic acid composite material and a preparation method thereof, wherein the low-smoke flame-retardant polylactic acid composite material is prepared by banburying and hot press molding by taking 85% of polylactic acid, 13-14.8% of silica gel microencapsulated ammonium polyphosphate and 0.2-2% of hexadecyl dimethyl benzyl ammonium chloride functionalized and modified titanium carbide nanosheets as raw materials, wherein the sum of the weight percentages is 100%. The low-smoke flame-retardant polylactic acid composite material has both condensed phase flame-retardant and gas phase flame-retardant mechanisms, and can obviously reduce heat and toxic smoke released during the combustion of polylactic acid, thereby obviously improving the fire safety performance of polylactic acid.

Description

A kind of low-smoke flame-retardant polylactic acid composite material and preparation method thereof

technical field

The invention belongs to the field of flame retardant material preparation, and particularly relates to a low-smoke flame-retardant polylactic acid composite material and a preparation method thereof.

Background technique

Polylactic acid has the advantages of non-toxicity, high transparency, high strength, good biocompatibility and easy processing, and is widely used in packaging, electrical and electronic industry, biomedicine and transportation. However, polylactic acid is very easy to burn, it will release a lot of heat when burning, and at the same time generate a lot of toxic and harmful fumes, which will not only seriously threaten personal safety, but also cause serious environmental pollution. In addition, the burning of polylactic acid will also be accompanied by serious melting and dripping, which can easily cause the rapid spread of fire. These shortcomings greatly limit the application of polylactic acid materials. Therefore, it is necessary to treat polylactic acid to improve its fire safety performance.

At present, the introduction of flame retardants is an effective measure to improve the fire safety performance of polymer materials. Flame retardants can be divided into various types such as intumescent flame retardants, metal oxide flame retardants and nano flame retardants. Silicon gel microencapsulated ammonium polyphosphate (SiAPP) is a typical intumescent flame retardant, which can not only catalyze the formation of dense carbon layers in the condensed phase stage, but also capture free radicals and dilute combustible gases in the gas phase stage. concentration, so it has an excellent flame retardant effect. Gao et al. introduced SiAPP into polystyrene to prepare flame retardant polystyrene composites. The results show that the introduction of 20.0% SiAPP reduces the total heat release of polystyrene by 37.8%. Ni et al. found that after the introduction of 12.5% SiAPP, the LOI of the polyurethane composite was as high as 32.0%. At the same time, the peak heat release rate of the polyurethane composite was significantly lower than that of pure polyurethane by 83.2%. Although ammonium polyphosphate has high flame retardant efficiency, the smoke suppression and detoxification effect of silicon gel microencapsulated ammonium polyphosphate is not obvious. Therefore, it is necessary to use silicone gel microencapsulated ammonium polyphosphate with other flame retardants to further improve the fire safety performance of polymer materials.

In recent years, titanium carbide nanosheets, as two-dimensional nanosheet materials, have been widely used in supercapacitors, electromagnetic shielding, batteries and other fields. In addition, titanium carbide nanosheets have good thermal stability and low thermal conductivity, and can play an excellent physical barrier function during polymer pyrolysis, effectively inhibiting polymer pyrolysis. At the same time, titanium carbide can catalyze the formation of a dense and continuous carbon layer when the polymer is burned, which can significantly reduce the heat and toxic and harmful fumes released during the burning of the polymer. Therefore, the excellent flame retardant effect of ammonium polyphosphate of silicone gel microcapsules combined with the efficient smoke suppression and detoxification effect of titanium carbide nanosheets will make the prepared flame retardant polymer composites have higher flame retardant and smoke suppression. toxic properties.

SUMMARY OF THE INVENTION

Aiming at the shortcomings that a large amount of heat and toxic fumes are generated when polylactic acid is burned, the present invention provides a low-smoke flame-retardant polylactic acid composite material and a preparation method thereof, which can effectively reduce the heat and toxic fumes generated when polylactic acid is burned to improve the fire safety performance of polylactic acid.

To achieve the above object, the present invention adopts the following technical solutions:

A low-smoke flame-retardant polylactic acid composite material, the raw materials used in the weight percentage are: polylactic acid 85%, silicon gel microencapsulated ammonium polyphosphate 13-14.8%, cetyl dimethyl benzyl chloride Ammonium functionalized modified titanium carbide nanosheets are 0.2-2%, and the sum of the three is 100%.

Wherein, the preparation steps of the silicon gel microencapsulated ammonium polyphosphate are as follows:

a. Add 150 ml of absolute ethanol and 50 ml of deionized water into a three-necked flask, mix with mechanical stirring and heat up to 45°C to obtain solution A;

b. 50 grams of ammonium polyphosphate and 0.5 grams of emulsifier OP-10 were added to solution A, and a certain amount of ammonia was added to adjust the pH of the solution to 9-10, and the mixed solution was mechanically stirred for 5 minutes to obtain solution B;

c. 10 grams of tetraethyl orthosilicate was slowly added to solution B within 30 minutes, and then mechanically stirred for 4 hours to obtain solution C;

d. After the solution C is cooled, filter, then wash the solid with deionized water and absolute ethanol, and dry the solid in a drying oven at 80 ° C for 24 hours to obtain the silica gel microencapsulated ammonium polyphosphate (SiAPP). ).

The preparation steps of the titanium carbide nanosheets functionalized and modified by hexadecyldimethylbenzylammonium chloride are as follows:

a. Add the dispersion liquid containing titanium carbide nanosheets into the three-necked flask, and then ultrasonically stir for 10 minutes under ice bath conditions, as dispersion liquid A;

b. Cetyl dimethyl benzyl ammonium chloride is added dropwise to dispersion A in a mass ratio of 2:1 to the titanium carbide nanosheets, and then stirred for 2 hours under nitrogen conditions to obtain dispersion B;

c. Centrifuge the dispersion B, then wash the solid with deionized water and absolute ethanol, and dry the solid in a vacuum drying oven at 80°C for 24 hours to obtain the cetyldimethylbenzylammonium chloride Functionalized modified titanium carbide nanosheets.

The dispersion liquid containing titanium carbide nanosheets is prepared through the following steps:

a. Slowly add 1.56 g of lithium fluoride and 1 g of carbon-aluminum-titanium to 20 ml of hydrochloric acid under magnetic stirring, and react at 35°C for 48 hours to obtain solution A;

b. After the solution A was washed with deionized water until neutral, a certain amount of deionized water was added and ultrasonically stirred in an ice bath for 30 minutes, centrifuged, and the upper layer was taken to obtain a dispersion liquid containing titanium carbide nanosheets.

The preparation method of the above-mentioned low-smoke flame-retardant polylactic acid composite material is to weigh polylactic acid, silicon gel microencapsulated ammonium polyphosphate and cetyl dimethyl benzyl ammonium chloride functionalized modified carbonization in proportion. Titanium nanosheets were placed in an internal mixer, mixed at 180°C for 10 minutes, and then hot-pressed in a flat vulcanizer at 180°C to obtain the low-smoke flame-retardant polylactic acid composite material.

The present invention has the following advantages and beneficial effects:

The invention integrates the condensed phase flame retardant and gas phase flame retardant mechanisms, so that the prepared polylactic acid composite material has excellent flame retardant and smoke suppression and detoxification properties, and the fire safety performance of polylactic acid is significantly improved, and its preparation cost low, the production process is simple, and has good application prospects.

Description of drawings

Figure 1 shows the heat and gas release curves of low-smoke flame-retardant PLA composites during combustion: a is the heat release rate; b is the total heat release; c is the smoke release rate; d is the total smoke release.

FIG. 2 is a picture of the PLA7 sample obtained in Comparative Example 3 after hot melt pressing.

Detailed ways

The technical solutions in the present invention will be clearly and completely described below with reference to specific implementation cases. Of course, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The preparation steps of the silicon gel microencapsulated ammonium polyphosphate are as follows:

a. Add 150 ml of absolute ethanol and 50 ml of deionized water into a three-necked flask, mix with mechanical stirring and heat up to 45°C to obtain solution A;

b. 50 grams of ammonium polyphosphate and 0.5 grams of emulsifier OP-10 were added to solution A, and a certain amount of ammonia was added to adjust the pH of the solution to 9-10, and the mixed solution was mechanically stirred for 5 minutes to obtain solution B;

c. 10 grams of tetraethyl orthosilicate was slowly added to solution B within 30 minutes, and then mechanically stirred for 4 hours to obtain solution C;

d. After the solution C is cooled, filter, then wash the solid with deionized water and absolute ethanol, and dry the solid in a drying oven at 80 °C for 24 hours to obtain silicon gel microencapsulated ammonium polyphosphate (SiAPP).

The preparation steps of hexadecyldimethylbenzylammonium chloride functionalized modified titanium carbide nanosheets are as follows:

a. Slowly add 1.56 g of lithium fluoride and 1 g of carbon-aluminum-titanium to 20 ml of hydrochloric acid under magnetic stirring, and react at 35°C for 48 hours to obtain solution A;

b. After the solution A was washed with deionized water to neutrality, a certain amount of deionized water was added and ultrasonically stirred in an ice bath for 30 minutes, centrifuged, and the upper layer was taken to obtain a dispersion liquid containing titanium carbide nanosheets;

c. The obtained dispersion containing titanium carbide nanosheets was added to the three-necked flask, and then ultrasonically stirred for 10 minutes under ice bath conditions as dispersion B;

d. Cetyldimethylbenzyl ammonium chloride is added dropwise to dispersion B in a mass ratio of 2:1 with the titanium carbide nanosheets, and then stirred for 2 hours under nitrogen conditions to obtain dispersion C;

e. Centrifuge the dispersion C, then wash the solid with deionized water and absolute ethanol, and dry the solid in a vacuum drying oven at 80°C for 24 hours to obtain functionalized cetyldimethylbenzylammonium chloride Modified titanium carbide nanosheets.

Example 1:

A low-smoke flame-retardant polylactic acid composite material is prepared according to the following specific steps:

a. Weigh 0.2 parts of cetyldimethylbenzyl ammonium chloride functionalized modified titanium carbide nanosheets, 14.8 parts of silica gel microencapsulated ammonium polyphosphate and 85 parts of polylactic acid;

b. Place the weighed cetyldimethylbenzyl ammonium chloride functionalized modified titanium carbide nanosheets, silicon gel microencapsulated ammonium polyphosphate and polylactic acid in an internal mixer, at 180 Banbury for 10 minutes at 180 degrees Celsius, and then place the sample after banburying in a flat vulcanizer at 180 degrees Celsius for hot pressing to form a low-smoke flame-retardant polylactic acid composite (PLA3).

Example 2:

A low-smoke flame-retardant polylactic acid composite material is prepared according to the following specific steps:

a. Weigh 0.5 parts of cetyldimethylbenzyl ammonium chloride functionalized modified titanium carbide nanosheets, 14.5 parts of silica gel microencapsulated ammonium polyphosphate and 85 parts of polylactic acid;

b. Place the weighed cetyldimethylbenzyl ammonium chloride functionalized modified titanium carbide nanosheets, silicon gel microencapsulated ammonium polyphosphate and polylactic acid in an internal mixer, at 180 Banbury for 10 minutes under the condition of degrees Celsius, and then place the sample after banburying in a flat vulcanizer at 180 degrees Celsius for hot pressing to form a low-smoke flame-retardant polylactic acid composite (PLA4).

Example 3:

A low-smoke flame-retardant polylactic acid composite material is prepared according to the following specific steps:

a. Weigh 1 part of cetyldimethylbenzyl ammonium chloride functionalized modified titanium carbide nanosheets, 14 parts of silica gel microencapsulated ammonium polyphosphate and 85 parts of polylactic acid;

b. Place the weighed cetyldimethylbenzyl ammonium chloride functionalized modified titanium carbide nanosheets, silicon gel microencapsulated ammonium polyphosphate and polylactic acid in an internal mixer, at 180 Banbury for 10 minutes at 180 degrees Celsius, and then place the sample after banburying in a flat vulcanizer at 180 degrees Celsius for hot pressing to form a low-smoke flame-retardant polylactic acid composite (PLA5).

Example 4:

A low-smoke flame-retardant polylactic acid composite material is prepared according to the following specific steps:

a. Weigh 2 parts of cetyldimethylbenzyl ammonium chloride functionalized modified titanium carbide nanosheets, 13 parts of silicon gel microencapsulated ammonium polyphosphate and 85 parts of polylactic acid;

b. Place the weighed cetyldimethylbenzyl ammonium chloride functionalized modified titanium carbide nanosheets, silicon gel microencapsulated ammonium polyphosphate and polylactic acid in an internal mixer, at 180 Banbury for 10 minutes at 180 degrees Celsius, and then place the sample after banburying in a flat vulcanizer at 180 degrees Celsius for hot pressing to form a low-smoke flame-retardant polylactic acid composite (PLA6).

Comparative Example 1:

A kind of pure polylactic acid is prepared according to the following steps:

a. Weigh 100 parts of polylactic acid;

b. Place the weighed polylactic acid in an internal mixer, mix it for 10 minutes at 180 degrees Celsius, and then place the mixed sample in a flat vulcanizer at 180 degrees Celsius for hot pressing to form pure polylactic acid. Lactic acid (PLA1).

Comparative Example 2:

A flame retardant polylactic acid composite material is prepared according to the following steps:

a. Weigh 15 parts of silicon gel microencapsulated ammonium polyphosphate and 85 parts of polylactic acid;

b. Place the weighed silicon gel microencapsulated ammonium polyphosphate and polylactic acid in an internal mixer, mix at 180 degrees Celsius for 10 minutes, and then place the mixed samples on a flat plate at 180 degrees Celsius The flame retardant polylactic acid composite material (PLA2) is obtained by hot pressing in a vulcanizing machine.

Comparative Example 3:

A flame retardant polylactic acid composite material is prepared according to the following steps:

a. Weigh 5 parts of cetyldimethylbenzyl ammonium chloride functionalized modified titanium carbide nanosheets, 10 parts of silicon gel microencapsulated ammonium polyphosphate and 85 parts of polylactic acid;

b. Place the weighed cetyldimethylbenzyl ammonium chloride functionalized modified titanium carbide nanosheets, silicon gel microencapsulated ammonium polyphosphate and polylactic acid in an internal mixer, at 180 Banbury for 10 minutes under the condition of Celsius degrees, and then place the sample after banburying in a flat vulcanizer at 180 degrees Celsius for hot pressing to form a flame-retardant polylactic acid composite (PLA7).

Fire safety performance analysis was carried out on the materials prepared in Examples 1-4 and Comparative Examples 1-2. Analysis equipment: CFZ-2 horizontal and vertical combustion measuring instrument and cone calorimeter; the thermal radiation value of the cone calorimeter is 35kW/m ² . The results are shown in Table 1-2 and Figure 1.

Table 1 UL-94 test data of low smoke flame retardant PLA composites

Table ² Cone calorimeter test data of low-smoke flame-retardant PLA composites under the condition of heat flux density of 35kW/m2

It can be seen from Table 1 that after the introduction of silicon gel microencapsulated ammonium polyphosphate and cetyldimethylbenzyl functionalized modified titanium carbide nanosheets, the obtained polylactic acid composites did not melt after burning. dripping phenomenon, and all PLA composites achieved a V-0 rating of UL-94. In particular, the LOI value of the polylactic acid composite prepared by introducing 13% silica gel microencapsulated ammonium polyphosphate and 2% cetyldimethylbenzyl functionalized modified titanium carbide nanosheets was as high as 33.3%.

It can be calculated from Table 2 and Figure 1 that compared with pure polylactic acid, the functional modification of 13.0% silica gel microencapsulated ammonium polyphosphate and 2.0% cetyldimethylbenzylammonium chloride was introduced. The peak heat release rate and total heat release of PLA composites prepared from titanium carbide nanosheets were reduced by 49.8% and 31.9%, respectively; the peak smoke release rate and total smoke release were reduced by 60.8% and 52.7%, respectively.

As can be seen from Figure 2, when the addition amount of titanium carbide nanosheets functionalized with cetyldimethylbenzyl ammonium chloride was increased to 2.0% and the addition amount of silica gel microencapsulated ammonium polyphosphate decreased up to 10.0%, due to the antagonism of the mutual catalysis between the modified titanium carbide nanosheets and the silica gel microencapsulated ammonium polyphosphate, the composite samples were extremely severe in the process of banburying and hot-melt pressing, and could not be prepared. Complete PLA composite.

From the above data analysis, it can be seen that due to the barrier and catalytic effects of modified titanium carbide, the carbon formation and free radical interruption effects of phosphorus-containing flame retardants, and the synergistic effect of modified titanium carbide and phosphorus-containing flame retardants, the obtained polymer The heat and toxic fumes released when the lactic acid composite material is burned are effectively reduced, which improves the fire safety performance of polylactic acid.

The low-smoke flame-retardant polylactic acid composite material provided by the present invention and the preparation method thereof are introduced in detail above. The preparation and application of the present invention are described herein by using specific embodiments, and the descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several modifications and improvements can be made to the present invention, and these modifications and improvements should also fall into the protection of the claims of the present invention within the range.

Claims (2)

1. a low-smoke flame-retardant polylactic acid composite material, is characterized in that: the raw materials used are in percentage by weight: polylactic acid 85%, silicon gel microencapsulated ammonium polyphosphate 13-14.8%, hexadecyl diphosphate Methylbenzylammonium chloride functionalized modified titanium carbide nanosheets 0.2-2%, and the sum of the three is 100%; The preparation steps of the silicon gel microencapsulated ammonium polyphosphate are as follows: a. Stir and mix 150 ml of absolute ethanol and 50 ml of deionized water and raise the temperature to 45°C to obtain solution A; b. 50 grams of ammonium polyphosphate and 0.5 grams of emulsifier OP-10 were added to solution A, and a certain amount of ammonia was added to adjust the pH of the solution to 9-10, and the mixed solution was mechanically stirred for 5 minutes to obtain solution B; c. Slowly add 10 grams of tetraethyl orthosilicate to solution B within 30 minutes, and mechanically stir for 4 hours to obtain solution C; d. After the solution C is cooled, filter, then wash the solid with deionized water and absolute ethanol, and dry the solid at 80°C for 24 hours to obtain the silica gel microencapsulated ammonium polyphosphate; The preparation steps of the titanium carbide nanosheets functionalized and modified by hexadecyldimethylbenzylammonium chloride are as follows: a. The dispersion liquid containing titanium carbide nanosheets was stirred ultrasonically for 10 minutes under ice bath conditions as dispersion liquid A; b. Cetyl dimethyl benzyl ammonium chloride is added dropwise to dispersion A in a mass ratio of 2:1 to the titanium carbide nanosheets, and then stirred for 2 hours under nitrogen conditions to obtain dispersion B; c. Centrifuge the dispersion B, then wash the solid with deionized water and absolute ethanol, and dry the solid at 80°C for 24 hours to obtain the functionalized modification of cetyldimethylbenzylammonium chloride of titanium carbide nanosheets; The dispersion liquid containing titanium carbide nanosheets is prepared through the following steps: a. Slowly add 1.56 g of lithium fluoride and 1 g of carbon-aluminum-titanium to 20 ml of hydrochloric acid under magnetic stirring, and react at 35°C for 48 hours to obtain solution A; b. After the solution A was washed with deionized water until neutral, a certain amount of deionized water was added and ultrasonically stirred in an ice bath for 30 minutes, centrifuged, and the upper layer was taken to obtain a dispersion liquid containing titanium carbide nanosheets. 2. a preparation method of low-smoke flame-retardant polylactic acid composite material as claimed in claim 1, is characterized in that: take by weighing polylactic acid, silicon gel microencapsulated ammonium polyphosphate, hexadecyl dimethacrylate in proportion The titanium carbide nanosheets functionalized and modified by methylbenzyl ammonium chloride were placed in an internal mixer for 10 minutes at 180 °C, and then hot-pressed in a flat vulcanizer at 180 °C. The low-smoke flame-retardant polylactic acid composite material is prepared.

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