Flame-retardant composite fabric and preparation method thereof

Abstract

The invention discloses a flame-retardant composite fabric and a preparation method thereof. The fabric is formed by weaving pure cotton fibers or blending and weaving nylon fibers and cotton fibers. The raw materials of the fabric further comprise a flame retardant and a pretreatment agent; the flame retardant comprises an organophosphorus oligomer and polycarboxylic acid; the cotton fibers are pre-treated by a pre-treating agent and then woven, then an activating agent is added into a flame retardant, and padding is performed to force the flame retardant to be fixed on the nylon fibers or the cotton fibers. According to the invention, the fixation rate of the flame retardant on the fabric can be increased, so that the efficient flame retardance can still be maintained after multiple times of washing.

Description

Technical Field

[0001] The present invention relates to the technical field of composite fabrics, in particular to a flame retardant composite fabric and a preparation method thereof. Background Art

[0002] Textiles are used in all areas of our production and life, and the importance of flame retardancy of textiles to our life and property safety is becoming increasingly prominent. The development of flame retardant textile materials has made great progress so far.

[0003] With growing calls for environmental protection, the development of halogen-free, formaldehyde-free, green, and environmentally friendly flame-retardant products has become increasingly urgent. One example is the use of nylon / cotton blends, primarily for the production of specialized workwear and military uniforms. These blends not only offer the wear and wrinkle resistance of textiles, but also maintain breathability and a soft, comfortable feel. Another example involves combining a phosphorus-containing organic compound, HFPO (Fyroltex HP), with dihydroxymethyldihydroxyethylene urea (DMDHEU) and butanetetracarboxylic acid (BTCA), to create a finishing system. The flame retardant is then applied to the fabric via a double-dip and double-pad process.

[0004] Among them, whether it is pure cotton after padding, pure nylon, or nylon / cotton fabric, the flame retardant effect can be greatly improved. However, the flame retardant after finishing with HFPO and butane tetracarboxylic acid (BTCA) has poor water washing effect. After multiple washings, the fixation rate of the flame retardant on the fabric will decrease. In order to increase the washability of textiles and maintain strong flame retardancy after multiple washings, the present application provides a solution. Summary of the Invention

[0005] The present application provides a flame-retardant composite fabric and a preparation method thereof, which can increase the fixation rate of the flame retardant on the fabric, thereby maintaining high flame retardancy after multiple washings.

[0006] The flame-retardant composite fabric provided in the present application is woven from pure cotton fibers, or a blend of nylon fibers and cotton fibers; the raw materials of the fabric also include a flame retardant and a pretreatment agent; the flame retardant includes an organic phosphorus oligomer and a polycarboxylic acid; the cotton fibers are pretreated with the pretreatment agent and then woven, and an activator is added to the flame retardant, followed by padding to force the flame retardant to be fixed on the nylon fibers or the cotton fibers.

[0007] By adopting the above technical solution, the present application pre-treats the cotton fibers to improve the fixation rate of the flame retardant on the fibers. By weaving the modified cotton fibers, the surface of the modified fabric is conducive to the impregnation of the flame retardant, and thus can maintain high flame retardancy after multiple washings.

[0008] Preferably, the organophosphorus oligomer is HFPO; and the polycarboxylic acid includes butanetetracarboxylic acid.

[0009] By adopting the above technical solution, the HFPO (product name Fyroltex HP) used in this application is an organophosphorus oligomer with hydroxyl functionality. Since it does not have functional groups that react with cotton fibers, it is necessary to use an adhesive to bond the HFPO to the cotton fibers by esterifying the HFPO with butanetetracarboxylic acid (BTCA).

[0010] Preferably, the pretreatment agent includes a finishing agent and a catalyst, and the finishing agent includes citric acid, succinic acid and malic acid.

[0011] By adopting the above technical solution, in the pretreatment of cotton fibers in this application, citric acid, succinic acid, and malic acid are all polycarboxylic acids. Since citric acid, succinic acid, and malic acid all have two carboxyl groups, it is difficult to form a network cross-linked structure, and therefore it is difficult to use them as additives for anti-wrinkle finishing. However, the carboxyl groups on citric acid, succinic acid, and malic acid can form ester bonds with cellulose hydroxyl groups, so they have affinity for the cotton fiber surface. Through the form of small molecule polycarboxyl groups, they are regularly and orderly stabilized on the cotton fiber surface, thereby helping to form a structure for HFPO to be fixed on the cotton fiber surface.

[0012] Preferably, the catalyst includes sodium dihydrogen phosphate, disodium hydrogen phosphate, or trisodium phosphate.

[0013] By adopting the above technical solution, the specific reaction is that the adjacent carboxyl groups of the dicarboxylic acid are dehydrated to form a cyclic acid anhydride intermediate, and then the acid anhydride undergoes an esterification reaction with cellulose. The process of converting polycarboxylic acids such as citric acid, succinic acid and malic acid into anhydrides requires overcoming a large amount of energy, and a catalyst is used to promote the occurrence of the reaction and advance the process.

[0014] Preferably, the activator is sodium hypophosphite.

[0015] By adopting the above technical solution, this application adds an activator to the flame retardant. Currently, sodium hypophosphite is used to catalyze polycarboxylic acids, among which butanetetracarboxylic acid (BTCA) can be catalyzed into anhydrides, esters, or both anhydrides and esters. Another purpose is to open the ester bonds on the surface of pretreated cotton fibers to activate the cotton fiber surface, thereby allowing the surface of the cotton fibers to be fixed with HFPO in an orderly and regular manner, improving the regularity of the cotton fiber surface. This reduces the occurrence of ester bond hydrolysis after multiple washings, allowing it to maintain high flame retardancy.

[0016] On the other hand, the present application provides a method for preparing a flame-retardant composite fabric, comprising the following steps: S1, pretreatment of textile fibers: mixing the finishing agent and the catalyst in proportion to form a pretreatment agent, then immersing the cotton fibers in the pretreatment agent, and drying the impregnated cotton fibers in an oven; alkali-washing the fibers with a sodium hydroxide solution of a certain concentration, and drying the fibers in an oven again; finally, washing the fibers with an acetone solution of a certain concentration at room temperature, and volatilizing the acetone at room temperature to obtain modified cotton fibers; S2, weaving of textile fibers: weaving the modified cotton fibers to obtain a first textile fabric; blending the modified cotton fibers with the nylon fibers to obtain a second textile fabric; S3. Preparation of flame retardant: dissolving a certain mass of HFPO in a hypophosphorous acid solution of a certain concentration, and adding a certain mass of butanetetracarboxylic acid in proportion, mixing and stirring for a certain time, adding a certain mass of protective agent, and controlling the temperature and mixing and stirring for a certain time to obtain a flame retardant; S4. Padding of flame retardant: adding the flame retardant to an activator solution to obtain an activated flame retardant solution; then, the first textile fabric or the second textile fabric is dipped and rolled twice by a padder to arrange the activated flame retardant solution on the fabric, and the arranged fabric is dried in a muffle furnace at a controlled temperature for a certain time, and the temperature is increased and continued to be baked for a certain time, and then after treatment, a flame-retardant composite fabric is obtained.

[0017] Preferably, in the step of pretreating the textile fibers, the weight ratio of the finishing agent to the catalyst is (1-3): (2-5).

[0018] Preferably, in the step of preparing the flame retardant, the weight ratio of the HFPO to the butanetetracarboxylic acid is (10-50):(1-20).

[0019] Preferably, in the step of preparing the flame retardant, the concentration of the hypophosphorous acid is 1.0-10.0%.

[0020] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0021] 1. This application uses pre-treatment of cotton fibers to improve the fixation rate of flame retardants on the fibers. By weaving the modified cotton fibers, the surface of the modified fabric is conducive to the impregnation of the flame retardant, and thus can maintain high flame retardancy after multiple washings.

[0022] 2. In this application, the carboxyl groups on citric acid, succinic acid, and malic acid form ester bonds with the hydroxyl groups of cellulose, and through their affinity for the cotton fiber surface, they are regularly and orderly fixed on the cotton fiber surface in the form of small molecule polycarboxyl groups, thereby helping to form a structure for HFPO to be fixed on the cotton fiber surface.

[0023] 3. In the present application, a catalyst is used to promote the reaction, so that the adjacent carboxyl groups of the dicarboxylic acid are dehydrated to form a cyclic anhydride intermediate, and then the anhydride reacts with cellulose to undergo an esterification reaction, thereby overcoming the large energy required for the anhydride formation of polycarboxylic acids such as citric acid, succinic acid and malic acid, thereby promoting the progress of the reaction.

[0024] 4. The present application adds an activator to the flame retardant to open the ester bonds on the surface of the pretreated cotton fiber to activate the surface of the cotton fiber, thereby enabling the surface of the cotton fiber to fix HFPO in an orderly and regular manner, thereby improving the regularity of the cotton fiber surface, thereby reducing the occurrence of ester bond hydrolysis after multiple washings, so that the cotton fiber can still maintain high flame retardancy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 The chemical structural formula of HFPO in the examples of this application;

[0027] Figure 2 is the chemical structural formula of citric acid (CA) in the examples of this application;

[0028] Figure 3 is the chemical structural formula of malic acid (MLA) in the examples of this application;

[0029] Figure 4 is the chemical structural formula of succinic acid (SA) in the examples of this application;

[0030] Figure 5 is the chemical structural formula of butanetetracarboxylic acid (BTCA) in the examples of this application. DETAILED DESCRIPTION

[0031] The present application provides a flame-retardant composite fabric and a preparation method thereof, which can increase the fixation rate of the flame retardant on the fabric, thereby maintaining high flame retardancy after multiple washings.

[0032] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only some of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of this application.

[0033] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products, or devices.

[0034] raw material

[0035] Cotton fiber CAS: 652-78-8 Molecular weight: 480.376 Gram weight 250g / m 2 This application uses commercially available cotton fibers.

[0036] Nylon fiber CAS: 32131-17-2 Molecular weight: 678.946 Gram weight 140g / m 2 .

[0037] HFPO is sold under the trade name "Fyroltex HP" and has a hydroxyl functional organophosphorus oligomer. The specific structural formula is shown in Figure 1 .

[0038] Citric acid CAS: 99026-99-0 Molecular weight: 502.51 Concentration: 980% Specific structural formula see Figure 2 .

[0039] Malic acid CAS: 6915-15-7 Molecular weight: 134.087 Concentration: 95.0% Specific structural formula: Figure 3 .

[0040] Succinic acid CAS: 110-15-6 Molecular weight: 118.088 98.0% Specific structural formula see Figure 4 .

[0041] Butanetetracarboxylic acid CAS: 1703-58-8 Molecular weight: 234.160 Concentration: 95.0% Specific structural formula: Figure 5 .

[0042] Sodium dihydrogen phosphate CAS: 7558-80-7 Molecular weight: 119.980 Concentration 98.0%.

[0043] Disodium hydrogen phosphate CAS: 7558-79-4 Molecular weight: 141.960 Concentration 98.0%.

[0044] Trisodium phosphate CAS: 7601-54-9 Molecular weight: 163.940 Degrees 98.0%.

[0045] Sodium hypophosphite CAS: 10039-56-2 Molecular weight: 03.978 Concentration: 98.0%.

[0046] Example

[0047] Example 1

[0048] S1. Pretreatment of textile fibers: 0.2 kg of citric acid (a finishing agent) and 0.4 kg of sodium dihydrogen phosphate (a catalyst) were stirred and mixed in 0.8 kg of deionized water to obtain a pretreatment agent, and 1.0 kg of cotton fibers were immersed in the pretreatment agent to achieve a wetting rate of 95%-100% for the cotton fibers. The impregnated cotton fibers were then dried in an oven at 80° C.; the fibers were then alkaline washed with a 0.1 mol / L sodium hydroxide solution for 10 min to salt the unreacted acid anhydride and carboxyl groups, and then dried in an oven at 80° C. again; and finally, the fibers were washed with a 13.5 mol / L acetone solution at room temperature for 10 min, and the acetone was volatilized at room temperature to obtain modified cotton fibers.

[0049] S2. Weaving of textile fibers: Weaving the modified cotton fibers to obtain a first textile fabric having a yarn count of 50s×50s, a warp and weft density of 145×75, and a gram weight of 122 g / m 2 ;

[0050] S3. Preparation of flame retardant: 1.0 kg of HFPO was dissolved in a 1.0% concentration hypophosphorous acid solution, and 0.1 kg of butanetetracarboxylic acid was added. After mixing and stirring for 1 hour, 0.2 kg of triethanolamine was added. The temperature was controlled at 50° C. and the mixture was stirred for 1 hour to obtain a flame retardant.

[0051] S4. Padding of flame retardant: 1.0 kg of flame retardant is added to a 10% concentration of sodium hypophosphite solution to obtain an activated flame retardant solution; the first textile fabric is then dipped and rolled twice on a padder to apply the activated flame retardant solution to the fabric, and the padding rate is controlled at about 80%. The finished fabric is dried in a muffle furnace at 90°C for 5 minutes, and then the temperature is raised to 160°C and baked for 5 minutes, and then the flame retardant composite fabric is obtained by treatment.

[0052] Examples 2-9

[0053] The difference between Example 2-9 and Example 1 is that the main components and the proportions of the main components of the pretreatment agent in the step of textile fiber pretreatment are adjusted. The specific proportions are shown in Figure 1 .

[0054] Table 1. Main components and proportions of the pretreatment agents in Examples 1-9

[0055]

[0056] Examples 10-14

[0057] The difference between Examples 10-14 and Example 1 is that, in the preparation step of the flame retardant, the weight ratio between HFPO and butane tetracarboxylic acid is adjusted. Figure 2 .

[0058] Table 2. Main components and proportions of the pretreatment agents in Examples 10-14

[0059] HFPO / kg Butane tetracarboxylic acid / kg Example 1 1.0 0.1 Example 10 1.0 1.0 Example 11 3.0 0.2 Example 12 3.0 0.5 Example 13 5.0 0.5 Example 14 5.0 1.0

[0060] Comparative Example

[0061] Comparative Example 1

[0062] The difference between Comparative Example 1 and Example 1 is that the cotton fibers are not pretreated, but are impregnated with a flame retardant.

[0063] Comparative Example 2

[0064] The difference between Comparative Example 2 and Example 1 is that the cotton fibers are pretreated but the flame retardant is not used for padding.

[0065] Comparative Example 3

[0066] The difference between Comparative Example 3 and Example 1 is that, in the flame retardant padding step, the flame retardant is not added to the activator solution.

[0067] Performance testing experiment

[0068] In order to further study the effects of various components and preparation parameters on flame retardant composite fabrics, the present application further carried out the following examples for verification.

[0069] According to Examples 1-14 and Comparative Examples 1-3, the flame-retardant composite fabrics prepared in each of the Examples and Comparative Examples were tested for flame retardancy, wear resistance, and thermal insulation after multiple washes. The flame-retardant composite fabrics were washed according to the method specified in GB / T 8629-2017, "Household Washing and Drying Procedure for Textile Testing," at a wash intensity of 5N, for 0, 50, and 100 washes. The washed flame-retardant composite fabrics were then dried and placed in an environment at 25°C and 60% relative humidity for 24 hours. The flame retardancy, wear resistance, and thermal insulation properties were then tested.

[0070] 1. Flame retardant performance test,

[0071] In accordance with GB / T5454-1997 "Textile combustion performance test method oxygen index method", the sample limit oxygen index is tested, and in accordance with GB / T5455-2014 "Textile combustion performance - Determination of vertical damage length, smoldering and afterflaming time", the sample afterflaming time, smoldering time and damage length are tested.

[0072] 2. Wear resistance test

[0073] According to GB1768-(79)88 "Test method for wear resistance of paint film", the wear amount of the sample was tested using a JM-1 paint film wear tester.

[0074] 3. Thermal insulation performance test

[0075] In accordance with GB / T11048-2018 "Determination of thermal and moisture resistance of textiles under steady-state conditions of physiological comfort (evaporating hot plate method)", the Crowe value of the sample is determined.

[0076] The data obtained from the test were sorted out after different washing times to obtain the following Tables 3-5.

[0077] Table 3. Performance test table of Examples 1-14 and Comparative Examples 1-3 without water washing

[0078]

[0079]

[0080] Table 4. Performance test table after 50 washes in Examples 1-14 and Comparative Examples 1-3

[0081]

[0082] Table 5. Performance test table after 100 washings in Examples 1-14 and Comparative Examples 1-3

[0083]

[0084]

[0085] Conclusion Analysis

[0086] According to Table 3, when the flame-retardant composite fabrics were analyzed without washing, Examples 1-14 all demonstrated excellent flame retardancy. Furthermore, in the measurement of vertical damage length, smoldering, and afterflame time for textile combustion performance, the sustained burning time and smoldering time both reached 0 seconds, and the damage length was 0 mm, demonstrating strong flame retardancy. Abrasion resistance and thermal insulation tests were also conducted, confirming excellent levels of both.

[0087] Furthermore, analysis of Comparative Example 1 shows that the flame-retardant composite fabric exhibits excellent flame retardancy without washing, even though the cotton fibers were not pretreated but padded with a flame retardant. Analysis of Comparative Example 2 also shows that the flame retardancy was poor when the flame retardant was not padded, resulting in persistent combustion and smoldering during testing.

[0088] In addition, combined with the analysis of Tables 4 and 5, the flame retardant and wear resistance of the flame retardant composite fabric after 50 and 100 washes will decrease. However, in this application, an activator is added to the flame retardant to open the ester bonds on the surface of the pretreated cotton fiber to activate the cotton fiber surface, thereby improving the regularity of the cotton fiber surface. The test results can be obtained from the afterburning time and the smoldering time. Compared with the analysis in Comparative Examples 2 and 3, it can be seen that in the impregnation step of the flame retardant, the flame retardant is not added to the activator solution. After multiple washings, it still has good flame retardancy. At the same time, its wear resistance and thermal insulation properties are also improved.

[0089] And through the analysis of Examples 1-14 in Tables 3 to 5, it can be concluded that Example 9 is the optimal example, in which the finishing agent is 0.3 kg of malic acid and the catalyst is 0.5 kg of trisodium phosphate, which can make the fabric still have good flame retardancy after multiple washings. At the same time, its wear resistance and heat insulation are also improved.

[0090] It should be noted that the above-mentioned order of the embodiments of the present application is for descriptive purposes only and does not represent the superiority or inferiority of the embodiments. The above description is of specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0091] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

[0092] This specification and drawings are merely illustrative of the present application and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Obviously, those skilled in the art may make various modifications and variations to this application without departing from the scope of this application. Thus, this application is intended to include such modifications and variations as fall within the scope of this application and its equivalents.

Claims

1. A flame retardant composite fabric, characterized in that: The fabric is woven from pure cotton fibers or a blend of nylon fibers and cotton fibers; the raw materials of the fabric also include a flame retardant and a pretreatment agent; the flame retardant includes an organic phosphorus oligomer and a polycarboxylic acid; The cotton fibers are pretreated with a pretreatment agent and then woven. An activator is added to the flame retardant, and then padding is performed to force the flame retardant to be fixed on the nylon fibers or the cotton fibers.

2. The flame retardant composite fabric according to claim 1, characterized in that: The organic phosphorus oligomer is HFPO; the polycarboxylic acid includes butane tetracarboxylic acid.

3. The flame retardant composite fabric according to claim 1, characterized in that: The pretreatment agent comprises a finishing agent and a catalyst, and the finishing agent comprises citric acid, succinic acid and malic acid.

4. The flame retardant composite fabric according to claim 3, characterized in that: The catalyst includes sodium dihydrogen phosphate, disodium hydrogen phosphate, and trisodium phosphate.

5. The flame retardant composite fabric according to claim 1, characterized in that: The activator is sodium hypophosphite.

6. A method for preparing the flame-retardant composite fabric according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Textile fiber pretreatment: the finishing agent and the catalyst are mixed in proportion to form a pretreatment agent, and then the cotton fiber is immersed in the pretreatment agent, and the impregnated cotton fiber is dried in an oven; the cotton fiber is alkali-washed with a sodium hydroxide solution of a certain concentration, and then dried in an oven again; finally, the cotton fiber is washed with an acetone solution of a certain concentration at room temperature, and the acetone is volatilized at room temperature to obtain a modified cotton fiber; S2. Weaving of textile fibers: weaving the modified cotton fibers to obtain a first textile fabric; blending the modified cotton fibers with the nylon fibers to obtain a second textile fabric; S3. Preparation of flame retardant: dissolving a certain amount of HFPO in a hypophosphorous acid solution of a certain concentration, adding a certain amount of butanetetracarboxylic acid in proportion, mixing and stirring for a certain period of time, adding a certain amount of protective agent, and controlling the temperature and stirring for a certain period of time to obtain a flame retardant; S4. Padding with flame retardant: adding the flame retardant to the solution of the activator to obtain an activated flame retardant solution; then, the first textile fabric or the second textile fabric is dipped and rolled twice by a padder to finish the activated flame retardant solution on the fabric, and the finished fabric is dried in a muffle furnace at a controlled temperature for a certain time, and then the temperature is increased and continued to be baked for a certain time, and then the flame retardant composite fabric is obtained after treatment.

7. The method for preparing the flame retardant composite fabric according to claim 6, wherein: In the step of pretreating the textile fibers, the weight ratio between the finishing agent and the catalyst is (1-3): (2-5).

8. The method for preparing a flame retardant composite fabric according to claim 6, wherein: In the step of preparing the flame retardant, the weight ratio of the HFPO to the butanetetracarboxylic acid is (10-50):(1-20).

9. The method for preparing a flame retardant composite fabric according to claim 8, wherein: In the step of preparing the flame retardant, the concentration of the hypophosphorous acid is 1.0-10.0%.

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