Environment-friendly washable flame-retardant hydrophobic fabric and preparation method thereof

Abstract

The invention discloses an environment-friendly washable flame-retardant hydrophobic fabric, a flame-retardant coating is formed on a cotton fabric, the flame-retardant coating comprises a cation coating and an anion coating, the anion coating contains phytic acid (PA), and the cation coating contains modified polyethyleneimine. The environment-friendly washable flame-retardant hydrophobic fabric has excellent flame retardance, hydrophobicity and washability.

Description

Technical Field

[0001] The invention relates to the technical field of cotton fabrics, and in particular to an environmentally friendly, washable, flame-retardant, hydrophobic fabric and a preparation method thereof. Background Art

[0002] Cotton, a natural fabric and a fundamental necessity for human life, is widely used in clothing, home furnishings, and other fields due to its excellent biodegradability, comfort, and breathability. However, cotton fabrics are often highly flammable, with a low limiting oxygen index (LOI) of typically 17-19%, leading to loss of life and property damage. There is a need to improve the flame retardancy of cotton fabrics and expand their applications.

[0003] Unlike synthetic fibers, natural cotton fibers cannot be modified by incorporating additives or reactive flame retardants (FRs) into their matrix. Post-treatment methods such as chemical bonding or physical attachment are widely used to manufacture functional cotton fabrics. Among these methods, layer-by-layer self-assembly is a simple and environmentally friendly surface modification method. The bonding strength of the coating material to the fabric and the thickness of the coating can be adjusted according to factors such as the composition, ionic strength and pH value of the coating solution. Currently, the durability of functionalized fabrics is a major issue in the long-term use of fabrics.

[0004] Imparting hydrophobicity to fabrics helps protect flame-retardant coatings under complex washing conditions, especially for hydrophilic cotton fabrics. Traditional fluorinated agents can impart excellent hydrophobicity to fabrics, but they also bring serious environmental problems. Summary of the Invention

[0005] To solve the above problems, the inventors conducted intensive research and formed a flame-retardant coating composed of a cationic coating and an anionic coating on a fabric by self-assembly. The cationic coating contains modified polyethyleneimine and the anionic coating contains phytic acid. The resulting coated modified fabric has excellent flame retardancy, hydrophobicity and washability, thus completing the present invention.

[0006] The object of the present invention is to provide an environmentally friendly, washable, flame-retardant, hydrophobic fabric, which has a flame-retardant coating formed on a cotton fabric. The flame-retardant coating includes a cationic coating and an anionic coating, wherein the anionic coating contains phytic acid (PA) and the cationic coating contains modified polyethyleneimine.

[0007] In a preferred embodiment, in the environmentally friendly, washable, flame-retardant and hydrophobic fabric, the flame-retardant coating is multi-layered, and each flame-retardant coating includes a cationic coating layer and an anionic coating layer, which are formed by self-assembly.

[0008] In a preferred embodiment, the cationic coating is obtained by reacting materials containing polyethyleneimine, acryloxysilane, alkylmethoxysilane and β-cyclodextrin.

[0009] In the present invention, polyethyleneimine is modified and cross-linked by using acryloxysilane, alkylmethoxysilane and β-cyclodextrin, which can significantly improve the flame retardancy, hydrophobicity and wash resistance.

[0010] In a further preferred embodiment, the acryloxysilane is selected from 3-(trimethoxysilyl)propyl methacrylate (TMSPA), γ-methacryloxypropyltrimethoxysilane and vinyltriethoxysilane, more preferably 3-(trimethoxysilyl)propyl methacrylate (TMSPA).

[0011] In a further preferred embodiment, the alkylmethoxysilane is selected from dodecyltrimethoxysilane (DTMS) and γ-glycidoxypropyltrimethoxysilane, more preferably dodecyltrimethoxysilane (DTMS).

[0012] In the cationic coating of the present invention, the dosage ratio of polyethyleneimine, acryloxysilane, alkylmethoxysilane and β-cyclodextrin is preferably: based on 100g of polyethyleneimine, the dosage of acryloxysilane is 10-30mL, preferably 15-25mL; the dosage of alkylmethoxysilane is 30-70mL, preferably 40-60mL; the dosage of β-cyclodextrin is 30-70g, preferably 40-60g.

[0013] In a preferred embodiment, a flame retardant coating is formed on a cotton fabric treated with alkali solution.

[0014] In a preferred embodiment, a hydrophobic cationic coating is impregnated on the flame retardant coating.

[0015] Another object of the present invention is to provide a method for preparing the above-mentioned environmentally friendly, washable, flame-retardant, and hydrophobic fabric, the method comprising:

[0016] (1) forming a cationic coating on the fabric surface through self-assembly;

[0017] (2) An anionic coating is formed by self-assembly on the cationic coating.

[0018] In step (1), self-assembly is performed by immersing the fabric in a cationic coating solution.

[0019] In a preferred embodiment, the cationic coating solution is obtained by adding a solution of polyethyleneimine to a solution of acryloxysilane and alkylmethoxysilane, and then adding β-cyclodextrin.

[0020] In step (2), self-assembly is performed by immersing the fabric in an anionic coating solution.

[0021] In a preferred embodiment, the anionic coating is obtained by adjusting the phytic acid solution to a desired pH value, for example, pH 6, using a sodium hydroxide solution.

[0022] In the method of the present invention, a double-layer flame retardant coating consisting of a cationic coating and an anionic coating is formed through steps (1) and (2).

[0023] In a preferred embodiment, multiple double-layer flame retardant coatings are formed by performing multiple rounds of steps (1) and (2).

[0024] In a preferred embodiment, after step (2), or after multiple rounds of step (2), the method further comprises step (3) of immersing in a cationic coating solution to form a cationic coating, so that the obtained modified fabric remains hydrophobic.

[0025] In a preferred embodiment, the method further comprises, before step (1), step (1') of treating the cotton fabric with an alkali solution.

[0026] The alkali solution is preferably a sodium hydroxide solution, and its concentration is not particularly limited.

[0027] In practice, after the alkali solution is impregnated and then rinsed with water and dried, the coating assembly is carried out.

[0028] The principle of the present invention is speculated as follows: the double bonds in polyethyleneimine and acryloxysilane react through a 1,4-conjugated addition reaction, and acryloxysilane and alkylmethoxysilane are co-modified on the surface of hydroxyl-rich β-CD through hydrolysis and condensation, constructing a covalent cross-linked network as a cationic coating (PEI-CD), which is then assembled to form a phytic acid coating, thereby imparting hydrophobicity, flame retardancy, and washability to cotton fabrics. However, the above is only a speculation on the principle of the present invention and the present invention is not limited to this.

[0029] The present invention has the following beneficial effects:

[0030] (1) The fabric provided by the present invention has excellent flame retardancy, hydrophobicity and washability;

[0031] (2) The fabric preparation method provided by the present invention is environmentally friendly, green, simple and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The electron microscope photographs and energy spectrum analysis of the pretreated cotton fabric and the obtained coating-modified cotton fabric in Example 1 are shown;

[0033] Figure 2 The XPS full spectrum (a), P 2p spectrum (b), N 1s spectrum (c) and Si 2p spectrum (d) of the coated modified cotton fabric obtained in Example 1 are shown;

[0034] Figure 3 Showing the TGA (a) and DTG (b) curves of the cotton fabric and the resulting coating-modified cotton fabric in Example 1;

[0035] Figure 4 The full XPS spectrum (a), Si2p (b), P 2p (c), and N1s (d) high-resolution XPS spectra of the residue of the coated modified cotton fabric obtained in Example 1 after CCT testing are shown;

[0036] Figure 5 Showing the Raman spectra of the carbon residue of the cotton fabric in Example 1 (a) and the carbon residue of the obtained coating-modified cotton fabric (b);

[0037] Figure 6 3D images of the cotton fabric and the resulting FR-Cotton after pretreatment in Example 1 (a), FTIR spectra of the cotton fabric and Cotton-5TL after pretreatment at the maximum degradation rate (b), and the release of carbonyl groups (c) and hydrocarbons (d) over time are shown; DETAILED DESCRIPTION

[0038] The present invention will be described in further detail below with reference to the accompanying drawings and examples, through which the features and advantages of the present invention will become more clearly understood.

[0039] The raw materials used in the embodiment are as follows:

[0040] Polyethyleneimine (PEI; Mn = 10000), 3-(trimethoxysilyl)propyl methacrylate (TMSPA), and dodecyltrimethoxysilane (DTMS): provided by McLean Biochemical Co., Ltd. (Shanghai)

[0041] Phytic acid (60% aqueous solution), β-cyclodextrin (β-CD, ≥98.0%): provided by Tianjin Photovoltaic Fine Chemistry Research Institute

[0042] Cotton cloth (plain weave), purchased on the market

[0043] Example 1 Preparation of environmentally friendly, washable, flame-retardant, hydrophobic fabric

[0044] (1) 2 mL of 3-(trimethoxysilyl)propyl methacrylate (TMSPA) and 5 mL of dodecyltrimethoxysilane (DTMS) were added to a beaker containing 250 mL of ethanol. 10 g of polyethyleneimine (PEI) was dissolved in water and then added dropwise to the solution. Subsequently, 5 g of β-cyclodextrin (β-CD) was added to the solution to obtain a PEI coating solution containing hydrophobic cations (cationic solution), designated PEI-CD.

[0045] (2) 60 g of phytic acid (PA) was dissolved in water and the pH value was adjusted to 6 with 4 mol / L sodium hydroxide solution to obtain a PA-based anionic solution.

[0046] (3) The cotton fabric was soaked in a sodium hydroxide solution (1 mol / L) at 80°C for 1 hour, then rinsed with deionized water and dried in an oven at 80°C. The pretreated cotton fabric was alternately immersed in the above-mentioned cationic solution and the above-mentioned anionic solution. Specifically, the cotton fabric was first soaked in a hydrophobic cationic solution at room temperature for 24 hours, and then immersed in a PA-based anionic solution for 10 minutes; after each soaking, the fabric was rinsed with water to remove excess coating material. Each cycle corresponds to a double-layer coating. Then it was dried at 60°C. According to the required number of double layers, 1, 3 and 5 double-layer coatings were formed respectively, and on this basis, the cationic solution was immersed again to form a single-layer cationic coating, thereby obtaining environmentally friendly, washable, flame-retardant and hydrophobic fabrics (also known as FR-Cotton), which were marked as Cotton-1TL, Cotton-3TL and Cotton-5TL respectively.

[0047] Test Example 1

[0048] The fabric obtained in Example 1 was subjected to the following tests:

[0049] (1) The morphology of the treated fabric was observed using a field emission scanning electron microscope (FE-SEM). Figure 1 shown.

[0050] Scanning electron microscope photos Figure 1 As shown in (a)-(f), the surface of the pretreated cotton fabric is smooth and slightly wrinkled, while the coated cotton fabric shows a rough surface. As the coating increases, the fibers are evenly buried in the coating, forming a compact structure.

[0051] The energy dispersive spectrum analysis (EDS) results of Cotton-5TL are as follows: Figure 1 As shown in (g)-(i), it can be seen that the elements in the coating, such as P, N, and Si, are evenly distributed on the surface of the modified cotton fabric, further confirming the successful construction of the coating.

[0052] (2) The chemical structure of the flame retardant coating was characterized by Fourier transform infrared spectroscopy (FTIR, Thermo Fisher Scientific Inc) in the wave number range of 4000–500 cm -1 .

[0053] The results showed that in the FTIR spectrum, the characteristic absorption band of the pretreated cotton fabric was located at 3330 cm -1 , 2900cm -1and 1650cm -1 , attributed to –OH, CH and –CO-, respectively;

[0054] As the cationic hydrophobic coating containing PEI-CD is formed, a new peak appears at 2920 cm -1 and 895cm -1 , corresponding to the stretching vibration of NH and –CH2-, respectively, originating from PEI and long-chain alkane DTMS, and the Si-O peak (895 cm -1 ) also comes from TMSPA and DTMS.

[0055] These results indicate that the hydrophobic coating has been attached to the fabric. It is worth noting that the presence of phytic acid can be seen by the PO stretching vibration (1082 cm -1 ) was observed. XPS spectroscopy also confirmed the successful construction of the coating.

[0056] (3) X-ray photoelectron spectroscopy (XPS) analysis was performed using a Thermo Escalab 250Xi. The anode X-ray source used had a photon energy of 1486.6 eV, a power of 150 W, a beam spot of 650 μm, and a voltage of 14.8 kV.

[0057] The XPS results of the sample in Example 1 are as follows: Figure 2 As shown, three elements appeared in the spectrum, namely P2p (134.27 eV), N1s (399.00 eV), Si 2s (153.97 eV) and Si 2p (102.90 eV).

[0058] The atomic percentages of P, N, and Si are 8.17%, 3.0%, and 5.87%, respectively. In the high-resolution N1s spectrum of the coated modified cotton cloth obtained in Example 1, the peaks at 398.5eV, 398.9eV, and 401eV are labeled as NH, -N=C-, and NH, respectively. 3+ , indicating that a salt was formed through the amine group of PEI and the phosphate group of PA.

[0059] The P2p high-resolution spectrum showed PC (132.8 eV) and O=PO (133.5 eV) peaks, revealing the presence of PA.

[0060] Silicon-containing long-chain alkanes are the significant components that impart hydrophobic properties to cotton fabrics, and C-Si-O (101.9 eV) and Si-C (102.48 eV) covalent bonds can also be observed on the fabrics.

[0061] The XPS results of the residues of the sample after CCT test in Example 1 are as follows: Figure 4As shown, peaks for POC (133.85 eV), O=PC (134.63 eV), NC (398.73 eV), N=C (399.75 eV), and quaternary ammonium / nitrogen oxide (400.68 eV) were observed. This indicates that under the catalytic action of PA, the P- and N-containing coating and cotton underwent dehydration and esterification, forming POC, NC, and N=C bonds. It is speculated that the presence of thermally stable N components helps improve the thermal stability of the carbon, thereby enhancing its protective effect and delaying its ignition time. Furthermore, the presence of Si-C (100.98 eV), Si-O (103.28 eV), and Si-P (100.98 eV) peaks in the Si 2p high-resolution spectrum indicates the formation of a ceramic-like carbon layer with enhanced thermal insulation properties.

[0062] (4) Thermogravimetric analysis (TGA) was performed on a TA 5500 at a heating rate of 10°C / min in a nitrogen atmosphere. Figure 3 and as shown in Table 1 below.

[0063] sample <![CDATA[T 10％ (℃)]]> <![CDATA[T max (℃)]]> <![CDATA[R max (% / ℃)]]> Residue (%) Pretreated cotton cloth 267.3 334.0 1.17 15.2 Cotton-1TL 288.1 329.2 0.96 34.2 Cotton-3TL 267.3 310.6 1.00 36.6 Cotton-5TL 229.1 311.3 0.97 37.4

[0064] The results showed that the pretreated cotton fabric decomposed mainly in the temperature range of 250-350 °C, and the final residue was 15.2% at 600 °C.

[0065] The initial decomposition temperature (T 10％ ) significantly increased to 288.1℃, while the initial decomposition temperature of pure cotton was 267.3℃.

[0066] The maximum decomposition temperature (T max ) showed two peaks, one of which remained at the same temperature as pure cotton (about 330 °C); with the increase of coating flame retardant, the other decomposition peak gradually became dominant, with a slightly lower temperature of about 310 °C.

[0067] The silicon-containing coating is converted into SiO2 nanoparticles at high temperatures, forming a ceramic-like structure, which improves the residual capacity of cotton fabrics.

[0068] It is noteworthy that the residue of the coating-modified cotton fabric sample increased significantly, almost twice that of pure cotton, which further verifies the high thermal stability of the residue.

[0069] The enhanced thermal stability and charring ability help improve the flame retardancy of cotton fabrics and reduce the release of gaseous products.

[0070] Correspondingly, the maximum degradation rate of Cotton-5TL decreased slightly. The main decomposition steps of all FR-Cotton samples occurred in almost the same temperature range, but as the number of coating layers increased to three and five, a certain weight loss was observed below 100°C, which may be due to the release of moisture in the coating material.

[0071] (5) The limiting oxygen index (LOI) test was performed according to ASTM D 2863-77.

[0072] (6) UL-94 vertical burning test analysis was performed according to ASTM D 3801-2010.

[0073] For tests (5) and (6), the results are shown in Table 2 below.

[0074]

[0075] (7) Cone calorimetry (CCT) was used to study the thermal conductivity of four-layer fabrics at 35kW / m 2 Combustion behavior under heat flux.

[0076] The results are shown in Table 3 below.

[0077]

[0078] It can be seen that flame retardant treated cotton fabrics significantly improved fire safety and effectively suppressed the release of heat and toxic gases.

[0079] (8) Raman spectroscopy analysis was performed using Renishaw inVia.

[0080] Raman spectra of carbon residues of pretreated cotton fabric and FR-Cotton Figure 5 As shown, there are two carbon bonds in the Raman spectrum, located at 1385cm-1 (D band) and 1595cm-1 (G band), representing defect structure and disordered graphite structure respectively. The ratio of D band to G band reveals the degree of graphitization of the residue. D / I G The values ​​decreased slightly to 3.41 to 3.45, showing that the degree of graphitization of its residues was higher than that of untreated cotton, which gave the fabric better thermal stability.

[0081] (9) TG-FTIR characterization was performed using an FTIR spectrometer (IZ10) connected to a thermogravimetric analyzer (TGA), and the samples were thermally degraded between room temperature and 600 °C at a heating rate of 10 °C / min.

[0082] The results are as follows Figure 6As shown in the TG-IR spectra of the pretreated cotton fabric and the FR-Cotton obtained in Example 1 during thermal degradation, the pretreated cotton fabric showed only one main peak (32.5 minutes), and the FR-Cotton fabric showed three significant peaks at 15 minutes, 31 minutes and 34 minutes, respectively, and the intensity was significantly reduced.

[0083] (10) The fabric washability test was performed according to the standard AATCC Test Method 143-2006.

[0084] The laundering durability of the flame-retardant coating on cotton fabric was evaluated by measuring the change in LOI values ​​after the fire and after 10 laundering cycles. The results showed that the LOI values ​​of the Cotton-3TL and Cotton-5TL samples after 10 laundering cycles were 23% and 24%, respectively, slightly lower than the initial LOI values ​​of 25% and 28% for the cotton fabric. However, the LOI values ​​of these two samples were still 20% higher than that of pure cotton fabric. This indicates that the flame-retardant coating can maintain a certain degree of flame retardancy under laundering conditions.

[0085] (11) Hydrophobicity test: Static and dynamic water contact angle (WCA) tests were used to evaluate the wettability of pretreated cotton fabrics and coating-modified fabrics.

[0086] The pretreated cotton fabric had a WCA of 128.9°, indicating a moderate hydrophobic effect, which was attributed to the residual sizing remaining on the surface of the pretreated cotton fabric. The WCAs of the cotton-1TL, cotton-3TL, and cotton-5TL fabrics were 137.6°, 135°, and 131.6°, respectively, further demonstrating improved hydrophobicity.

[0087] Dynamic water contact angle (DCA) measurements showed that water droplets on pretreated cotton fabrics completely penetrated the fabric within 5 minutes, while all FR-cotton fabrics maintained their water repellency for more than an hour. The WCAs for Cotton-1TL, Cotton-3TL, and Cotton-5TL fabrics after 9 minutes were 96.7°, 109.1°, and 96.8°, respectively.

[0088] The present invention has been described in detail above with reference to specific embodiments and / or exemplary examples and the accompanying drawings. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An environmentally friendly, washable, flame-retardant, hydrophobic fabric, which has a flame-retardant coating formed on a cotton fabric, wherein the flame-retardant coating comprises a cationic coating and an anionic coating, wherein: The anionic coating contains phytic acid (PA) and the cationic coating contains modified polyethyleneimine.

2. The environmentally friendly, washable, flame-retardant, hydrophobic fabric according to claim 1, comprising a plurality of flame-retardant coatings, each of which comprises a cationic coating and an anionic coating.

3. The environmentally friendly, washable, flame-retardant, hydrophobic fabric according to claim 1, wherein: The cationic coating is formed by self-assembly, and the anionic coating is formed by self-assembly.

4. The environmentally friendly, washable, flame-retardant, hydrophobic fabric according to claim 1, wherein: The cationic coating is obtained by reacting materials containing polyethyleneimine, acryloxysilane, alkylmethoxysilane and beta-cyclodextrin.

5. The environmentally friendly, washable, flame-retardant, hydrophobic fabric according to claim 4, wherein: The acryloxymethoxysilane is selected from 3-(trimethoxysilyl)propyl methacrylate (TMSPA), γ-methacryloxypropyltrimethoxysilane and vinyltriethoxysilane, more preferably 3-(trimethoxysilyl)propyl methacrylate (TMSPA); The alkylmethoxysilane is selected from dodecyltrimethoxysilane (DTMS) and γ-glycidoxypropyltrimethoxysilane, more preferably dodecyltrimethoxysilane (DTMS).

6. The environmentally friendly, washable, flame-retardant, hydrophobic fabric according to claim 4, wherein: The cotton fabric is an alkali-treated cotton fabric.

7. The environmentally friendly, washable, flame-retardant and hydrophobic fabric according to claim 1, further comprising a cationic coating outside the flame-retardant coating.

8. A method for preparing an environmentally friendly, washable, flame-retardant, hydrophobic fabric, the method comprising the following steps: (1) forming a cationic coating on the fabric surface through self-assembly; (2) An anionic coating is formed by self-assembly on the cationic coating.

9. The method according to claim 8, wherein In step (1), self-assembly is performed by immersing the fabric in a cationic coating solution; In step (2), self-assembly is performed by immersing the fabric in an anionic coating solution; The cationic coating solution is obtained by adding a solution of polyethyleneimine to a solution of acryloxysilane and alkylmethoxysilane, and then adding β-cyclodextrin; The anionic coating is obtained by adjusting the phytic acid solution to the desired pH value with sodium hydroxide solution.

10. The method according to claim 8, wherein The method further comprises, before step (1), step (1') of treating the cotton fabric with an alkali solution; After step (2), or after multiple rounds of step (2), the method further comprises step (3) of immersing in a cationic coating solution to form a cationic coating.

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