CN114805431A - Synthetic method and application of halogen-free flame retardant for cotton - Google Patents

Abstract

The invention discloses a synthesis method and application of a halogen-free flame retardant for cotton. Vitamin B2 and phytic acid are mixed, reacted at 90-105 DEG C for _1-2 hours, then added with urea, and heated to 150-170 DEG C and reacted for 1.5-2 hours. 2.5h, cooled to room temperature, washed and dried to obtain a halogen-free flame retardant for cotton. The flame retardant prepared by the invention is used for deep dyeing and flame retardant of cotton fabrics. The cotton fabrics finished with the flame retardant of the invention not only have good dyeability, but also have excellent washing fastness. Excellent performance and good application prospects.

Description

A kind of synthetic method and application of halogen-free flame retardant for cotton

technical field

The invention belongs to the technical field of flame retardant materials, and particularly relates to a synthesis method and application of a halogen-free flame retardant for cotton.

Background technique

Because cotton fabric is the most commonly used fabric in people's life. In many fields such as industry, clothing and household goods, the cost-effective medium cotton is the first choice. However, pure cotton is extremely flammable and belongs to flammable materials. It is difficult to avoid the occurrence of fires. This has greatly restricted its use in some fields. Therefore, cotton fabrics are given flame retardant properties and increase the safety of cotton fabrics. It is of great significance and application prospect.

The most commonly used flame retardants are halogenated flame retardants. Halogen-based flame retardants have the advantages of high flame retardant efficiency, low price of flame retardants, relatively mature preparation technology of flame retardants and better thermal stability of flame retardants. The flame retardant has become one of the most widely used flame retardants in the world. However, the thermal cracking products of halogen-based flame retardants are not only toxic but also very likely to cause cancer. In recent years, because halogenated flame retardants can cause secondary harm to the human body, and also pollute the environment, this series of problems has attracted widespread attention, but this type of flame retardant has a fatal disadvantage: environmental pollution It is serious and causes great harm to the human body. Therefore, halogenated flame retardants are gradually being phased out. With the gradual deepening of people's awareness of environmental protection, the development prospects of halogen-free flame retardants are getting better and better, especially the halogen-free flame retardants with special properties.

Halogen-free and environmentally friendly flame retardants have attracted much attention. In particular, natural biomass materials, such as lignin, have been used to prepare various environmentally friendly, renewable and biodegradable flame retardants.

SUMMARY OF THE INVENTION

As one aspect of the present invention, the present invention provides a method for synthesizing a halogen-free flame retardant for cotton, characterized in that it consists of the following steps:

Mix vitamin B2 and phytic _acid , react at 90-105°C for 1-2h, then add urea, heat up to 150-170°C and react for 1.5-2.5h, cool to room temperature, wash and dry to obtain halogen-free flame retardant for cotton wherein, the mass ratio of the vitamin B ₂ : phytic acid: urea is (3-4): (25-30): (18-20).

As a preferred solution of the method for synthesizing the halogen-free flame retardant for cotton according to the present invention, the mass ratio of the vitamin B ₂ : phytic acid: urea is 3.76:26.40:18.81.

As a preferred solution of the method for synthesizing the halogen-free flame retardant for cotton according to the present invention, the reaction at 90 to 105° C. is 1 to 2 hours, and the reaction at 100° C. is 1.5 hours.

As a preferred solution of the method for synthesizing the halogen-free flame retardant for cotton according to the present invention, the temperature is raised to 150-170°C for 1.5-2.5 hours, and the temperature is raised to 160°C for 2 hours.

As a preferred solution of the method for synthesizing the halogen-free flame retardant for cotton according to the present invention: the washing is to clean the reaction product with ethanol; the drying is to dry the reaction product at 50-55°C.

As another aspect of the present invention, the present invention provides the application of the halogen-free flame retardant for cotton in cotton fabric finishing, which consists of the following steps:

Pretreatment of cotton fabric: first desizing cotton fabric in desizing solution, and then scouring in scouring solution;

The halogen-free flame retardant for cotton is prepared into an aqueous solution with a concentration of 30 to 50 wt %, 8 to 12 wt % of dicyandiamide is added, and the water bath is shaken at 55 to 65° C. for 0.5 to 1.5 hours, according to the bath ratio of 1:15 to 25 The pretreated cotton fabric is added, oscillated in a water bath at 55 to 65°C for 0.5 to 1.5 hours, and finally the cotton fabric is dipped and rolled twice, dried, baked, and washed to obtain flame retardant cotton; the halogen-free flame retardant For dyeing and flame retardant finishing of cotton fabrics.

As a preferred solution for the application of the halogen-free flame retardant for cotton in the cotton fabric finishing according to the present invention: the desizing solution is composed of 10g/L sodium hydroxide, 1g/L fatty alcohol polyoxyethylene ether composition, the bath ratio is 1: 20; the scouring liquid is composed of 20g/L of sodium hydroxide and 1g/L of refining agent, and the bath ratio is 1: 30; the last two dipping and two rolling of the cotton fabric, Drying, baking, wherein, the drying is drying at 75-80° C. for 5-10 minutes; and the baking is drying at 170-180° C. for 3-5 minutes.

As a preferred solution of the application of the halogen-free flame retardant for cotton in the cotton fabric finishing according to the present invention: the halogen-free flame retardant for cotton is prepared into an aqueous solution with a concentration of 30-50 wt %, and 10 wt % is added. The dicyandiamide was shaken in a water bath at 60°C for 1 hour, the pretreated cotton fabric was added in a bath ratio of 1:20, and the cotton fabric was shaken in a water bath at 60°C for 1 hour. Obtain flame retardant cotton.

Beneficial effects of the present invention: the flame retardant prepared by the present invention is used for deep dyeing and flame retardant of cotton fabrics, and the cotton fabrics finished with the flame retardant of the present invention not only have good dyeing properties, but also have excellent washing fastness, Flame retardant cotton has excellent flame retardant properties and has good application prospects.

Description of drawings

Figure 1 is a schematic diagram of the synthesis of flame retardant I.

Figure 2 is a schematic diagram of the synthesis of flame retardant II.

Figure 3 is a schematic diagram of the preparation process of flame retardant cotton I.

Figure 4 is a schematic diagram of the preparation process of flame retardant cotton II.

Fig. 5 is an external view of the fabric before and after treatment.

Figure 6 is an analysis chart of fabric whiteness.

Figure 7 is an analysis diagram of the color depth of the fabric surface.

Figure 8 is an analysis diagram of the fabric limiting oxygen index.

Figure 9 is a swatch of the fabric before burning.

Figure 10 shows the fabric sample after burning.

Figure 11 is the scanning electron microscope photos of different fabrics before and after burning.

Figure 12 shows the fabric breaking strength analysis.

Figure 13 is the infrared spectrum of the original cloth, flame-retardant cotton I, and flame-retardant cotton II.

Detailed ways

In order to make the above objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention will be described in detail below with reference to specific embodiments.

Example 1:

The synthesis process of flame retardant I is shown in Figure 1. Put 26.40g of phytic acid and 18.81g of urea into 250mL three-necked flasks respectively, react at 110°C for 1.5h, when cooled to room temperature, wash the product with N,N-dimethylformamide, and then vacuum dry at 30°C It was dried in the oven to obtain the flame retardant I.

The synthesis of flame retardant II is shown in Figure 2. First, 3.76g of vitamin B ₂ and 26.40g of phytic acid were added to a 250mL three-necked flask, and reacted at 100 °C for 1.5h, and then 18.81g of urea was added to the above reaction solution. , heat up to 160°C, continue to react for 2h, cool to a greenhouse, wash the reaction product with ethanol, and dry at 50°C to obtain flame retardant II.

Flame retardant finishing of pure cotton fabrics:

Pretreatment of cotton fabrics: first, desizing the cotton fabrics in desizing solution (sodium hydroxide: 10g/L; penetrant fatty alcohol polyoxyethylene ether): 1g/L; bath ratio: 1:20) to remove cotton Slurry on fiber; then scouring in scouring liquor (sodium hydroxide: 20 g/L; refining agent: 1 g/L; liquor ratio: 1:30).

The flame retardant I was dissolved in distilled water to prepare solutions with concentrations of 30 wt %, 40 wt % and 50 wt %, respectively. Then, 10wt% of dicyandiamide was added to the above flame retardant solution, shaken in a water bath at 60°C for 1 h, so that the dicyandiamide was fully dissolved in the solution, and then cotton fabric was added according to the bath ratio (g:g) 1:20, 60°C The cotton fabric was shaken in a water bath for 1 h, and finally the cotton fabric was dipped and rolled (80% liquid rolling rate), dried (80°C, 5min), baked (180°C, 3min), and washed with water to obtain flame-retardant cotton I-1. , flame retardant cotton I-2, flame retardant cotton I-3.

The flame retardant II was dissolved in distilled water to prepare solutions with concentrations of 30wt%, 40wt% and 50wt%, respectively. Then, add dicyandiamide accounting for 10 wt% of the total solution mass to the above flame retardant solution, shake in a water bath at 60°C for 1 hour, so that dicyandiamide is fully dissolved in the solution, and then add cotton fabric according to the bath ratio of 1:20, and water bath at 60°C After shaking for 1 hour, the cotton fabric was finally soaked and rolled twice (the rolling rate was 80%), dried (80°C, 5min), baked (180°C, 3min), washed with water to obtain flame-retardant cotton II-1, flame-retardant cotton II-1, respectively. Cotton II-2, flame retardant cotton II-3.

Fabric appearance inspection: The flame retardant cotton fabric and the original fabric are cut into the same shape, and the appearance of the fabric can be inspected and analyzed intuitively.

Fabric whiteness test: According to GB/T 8424.2-2001 "Instrumental Evaluation Method for Relative Whiteness of Textile Color Fastness Test", the pretreated blank cotton samples, flame retardant cotton I-1, flame retardant cotton I-2, Flame-retardant cotton I-3, flame-retardant cotton II-1, flame-retardant cotton II-2, and flame-retardant cotton II-3 were tested for whiteness with a whiteness tester respectively, and the average value was taken and the data was recorded.

Fabric surface color depth test: The surface color depth of finished and untreated fabrics is tested by computerized color matching system.

Fabric breaking strength test: cut the fabric into 6cm×30cm, use the HD026N electronic fabric strength tester, according to GB/T 3923.1-2013 "Textile Fabric Tensile Properties Part 1: Determination of Breaking Strength and Elongation at Break (Strip Sample) Method)" to test the breaking strength of the fabric.

Limiting oxygen index test: According to GB/T 5454-1997 "Textile Combustion Performance Test Oxygen Index Method", test the limiting oxygen index of fabrics. The specific operation method is as follows: cut the fabric into 5cm × 10cm and hold it on the burning fixture stably, keep twisting the button to adjust the ratio of oxygen and nitrogen, and then use the igniter to ignite the fabric after adjustment. During the combustion process, observe the proportion of the fabric that can achieve complete combustion, then record the oxygen concentration value and set it as the limiting oxygen index.

Vertical burning test: Cut the fabric into strips with a width of 1cm and a length of 4cm, then fix it on an iron stand, and clamp it with a clamp to keep it in a state of vertical suspension, then ignite the fabric with a lighter, and record the afterburning time of the fabric , smoldering time and photo parameters.

FT-IR test: On the Fourier transform infrared spectrometer, the finished fabric was tested by FT-IR in the wavenumber range of 400-4000cm-1 by the KBr tablet method.

SEM test: Scanning electron microscope (SEM) was used to characterize the micro-morphology of the flame-retardant cotton fabric and the surface of the carbon residue after combustion.

FT-IR analysis: the characteristic absorption peak of the original fabric is at 900-1200 cm ^-1 , the stretching vibration peak of -OH is around 3340 cm ^-1 , and the bending vibration peak of -OH is at 1640 cm ^-1 . There are several characteristic peaks in flame retardant cotton I. The strong characteristic absorption peaks are caused by the stretching and bending vibration of NH ₄ ⁺ at 3210cm ^-1 and 1450cm ^-1 , and the more obvious at 1510-1770cm ^-1 . The bending vibration peaks of OPO, the stretching vibration peaks of P=O are at 1230 cm ^-1 and the absorption peaks of POC are at 940 cm ^-1 , so it can be verified that -P=O(O-NH ₄ ⁺ ) ₂ of flame retardant I The groups react with hydroxyl groups in cellulose to form POC covalent bonds. There are several characteristic peaks of flame retardant II in flame retardant cotton II, 1555cm ^-1 is the peak of NH bond, 1374cm ^-1 is the peak of CN bond, 1228cm ^-1 is the stretching vibration peak of P=O, and 1021cm ^-1 is the peak of stretching vibration of P=O. The stretching vibration peak of the covalent bond of POC, which can verify the successful grafting of flame retardant II onto cotton fabrics.

Fabric appearance analysis: The appearance of the fabric before treatment and the cotton fabric treated with the two flame retardants are shown in Figure 5. It can be seen from the figure that the fabric colors of flame retardant cotton fabric I and flame retardant cotton fabric II become darker as the concentration increases; while the fabric colors of flame retardant cotton fabric I and flame retardant cotton fabric II are different. . The color deepening of flame retardant cotton fabric I is due to the color of phytic acid itself in flame retardant I; the color difference of flame retardant cotton fabric _II is due to the dual effects of phytic acid and vitamin B2.

Fabric whiteness analysis: The whiteness of cotton fabrics finished with different flame retardants and unfinished cotton fabrics is shown in Figure 6. It can be seen from the figure that the whiteness of the cotton samples treated with flame retardant I does not change much compared with the unfinished cotton fabrics, which indicates that flame retardant I has little effect on the fabrics; The whiteness of the cotton samples finished with flame retardant II varies greatly, which indicates that vitamin B2 in flame retardant _II has a dyeing effect. At the same time, with the deepening of the concentration of the two flame retardants, the whiteness of the fabric gradually tends to be level, and it can be inferred that the absorption of the cotton fabric reaches saturation.

Fabric surface color depth analysis: The color depth of the fabric before and after treatment is shown in Figure 7. It can be seen from Figure 7 that the K/S value of the fabric is in a curve shape in the wavelength range of 360-750nm; the K/S value of the original fabric is the largest at the wavelength of 400nm, and the K/S value of the flame retardant cotton I-1 is at the wavelength of 370nm. S value is the largest, flame retardant cotton I-2 has the largest K/S value at 380nm wavelength, flame retardant cotton I-3 has the largest K/S value at 380nm wavelength, and flame retardant cotton II-1 has the K/S value at 370nm wavelength. The K/S value of flame retardant cotton II-2 is the largest at 380 nm wavelength, and the K/S value of flame retardant cotton II-3 is the largest at 380 nm wavelength. It can be seen from Figure 7 that the surface color of the fabric after the flame retardant finishing increases as the concentration increases.

Analysis of fabric limiting oxygen index: The limiting oxygen index of flame retardant cotton is shown in Figure 8. It can be seen from the figure that the cotton sample treated with flame retardant I has a larger LOI value as the concentration increases; The LOI value of the cotton samples prepared with the fuel agent II increased with the increase of the concentration. As shown in Figure 8, the LOI value of the original fabric is 17%, the LOI value of the flame retardant cotton I-1 is 31%, the LOI value of the flame retardant cotton I-2 is 36.7%, and the LOI value of the flame retardant cotton I-3 is 39%; The LOI value of II-1 is 33%, the LOI value of flame retardant cotton II-2 is 39%, and the LOI value of flame retardant cotton II-3 is 42%. Overall, the flame retardant performance of flame retardant cotton fabric II is better than that of flame retardant cotton fabric I. It can be concluded that the flame retardant effect of the fabric is better than that without the addition of VB ₂ .

Fabric vertical burning analysis: The samples before fabric burning are shown in Figure 9, the fabric burning samples are shown in Figure 10, and the fabric vertical burning test data and phenomena are shown in Table 1. It can be seen from the figure and table that the flame retardancy of the flame retardant cotton fabric is better as the concentration increases; it can be seen from the comparison that the flame retardancy of the flame retardant cotton II is better than that of the flame retardant cotton I at the same concentration.

Table 1 Vertical burning of fabrics

SEM analysis: The morphological changes of cotton fabrics treated with different flame retardants before and after combustion are shown in Figure 11. Comparing these pre-combustion fabrics, it is found that the surface of the cotton fabric (Fig. 11a) treated with flame retardant I became slightly rough, with continuous sheet-like substances attached, and the surface structure of the fibers did not change significantly; after flame retardant II finishing The cotton fabric (Fig. 11c) has a rough surface with flocculent substances on its surface. Since the flame retardant cotton fabric has been washed many times, it can be proved that the flame retardant I and the flame retardant II have successfully reacted with the groups in the cotton fiber to form a strong covalent bond.

Washing fastness analysis of treated cotton was carried out according to AATCC 61-2006 standard using soaping fastness tester. The water temperature was 49°C and the washing time was 45min. The experimental results are shown in Table 2.

Table 2 LOI values of fabrics before and after washing

Table 3 Washing color fastness of fabrics before and after washing

Comparing the burned fabrics, it is found that the cotton fabrics treated with flame retardants can still maintain the original state of fibers after burning, and there is no breakage. It can be seen that the flame retardant has a good flame retardant effect in the combustion process of cotton fibers.

Compared with the shape of flame-retardant cotton I after burning (Figure 11b), obvious bubbles appeared on the fiber surface of flame-retardant cotton II after burning (Figure 11d), while flame-retardant cotton I only had a small amount of bubbles. It shows that these two flame retardants are intumescent flame retardants, and the flame retardant effect of flame retardant II is better than that of flame retardant I.

Fabric breaking strength analysis: The mechanical properties of the treated and untreated fabrics are shown in Figure 12. It can be seen from the figure that with the increase of the concentration of flame retardant cotton fabric I and flame retardant cotton fabric II, the breaking strength of the flame retardant cotton fabric decreases; overall, the strength of the flame retardant cotton fabric II is better than that of the flame retardant cotton fabric. The strength of I. The reason may be that vitamin B2 in flame retardant _II has acid resistance, and the grafting on cotton fiber can play a good protective role, resulting in less strength loss of the fabric than that of the cotton fabric finished with flame retardant I.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be Modifications or equivalent substitutions without departing from the spirit and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims (8)

1. A synthetic method of a halogen-free flame retardant for cotton is characterized by comprising the following steps: the method comprises the following steps of (1),

mixing vitamin B ₂ Mixing with phytic acid, reacting for 1-2 h at 90-105 ℃, adding urea, heating to 150-170 ℃, reacting for 1.5-2.5 h, cooling to room temperature, washing, and drying to obtain the halogen-free flame retardant for cotton; wherein the vitamin B ₂ The mass ratio of the phytic acid to the urea is (3-4) to (25-30) to (18-20).

2. The synthetic method of the halogen-free flame retardant for cotton according to claim 1, characterized in that: the vitamin B ₂ The mass ratio of the phytic acid to the urea is 3.76: 26.40: 18.81.

3. The synthetic method of the halogen-free flame retardant for cotton according to claim 1 or 2, characterized in that: the reaction is carried out for 1-2 h at the temperature of 90-105 ℃, and the reaction is carried out for 1.5h at the temperature of 100 ℃.

4. The synthetic method of the halogen-free flame retardant for cotton according to claim 1 or 2, characterized in that: the temperature is increased to 150-170 ℃ for reaction for 1.5-2.5 h, and the temperature is increased to 160 ℃ for reaction for 2 h.

5. The synthetic method of the halogen-free flame retardant for cotton according to claim 1 or 2, characterized in that: the washing is to wash the reaction product by ethanol; and the drying is to dry the reaction product at 50-55 ℃.

6. The use of the halogen-free flame retardant for cotton according to claim 1 in the finishing of cotton fabrics is characterized in that: the method comprises the following steps of (1),

pretreatment of cotton fabric: desizing cotton fabrics in desizing liquid, and then boiling the cotton fabrics in boiling-off liquid;

preparing the cotton into an aqueous solution with the concentration of 30-50 wt% by using a halogen-free flame retardant, adding 8-12 wt% of dicyandiamide, oscillating in a water bath at 55-65 ℃ for 0.5-1.5 h, adding the pretreated cotton fabric according to the bath ratio of 1: 15-25, oscillating in a water bath at 55-65 ℃ for 0.5-1.5 h, and finally soaking and rolling the cotton fabric twice, drying, baking and washing with water to obtain the flame-retardant cotton; the halogen-free flame retardant is used for dyeing and flame-retardant finishing of cotton fabrics.

7. Use according to claim 6, characterized in that: the desizing liquid consists of 10g/L of sodium hydroxide and 1g/L of fatty alcohol polyoxyethylene ether, and the bath ratio is 1: 20; the scouring liquid consists of 20g/L of sodium hydroxide and 1g/L of refining agent, and the bath ratio is 1: 30; finally, soaking and rolling the cotton fabric twice, drying and baking, wherein the drying is carried out for 5-10 min at the temperature of 75-80 ℃; and the baking is carried out for 3-5 min at 170-180 ℃.

8. Use according to claim 6 or 7, characterized in that: preparing the cotton into an aqueous solution with the concentration of 30-50 wt% by using a halogen-free flame retardant, adding 10 wt% of dicyandiamide, oscillating in a water bath at 60 ℃ for 1h, adding the pretreated cotton fabric according to the bath ratio of 1: 20, oscillating in the water bath at 60 ℃ for 1h, soaking and rolling the cotton fabric twice, drying, baking and washing to obtain the flame-retardant cotton.

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