Durable antibacterial and flame-retardant multifunctional silk product and preparation method thereof

Abstract

The application discloses a durable antibacterial and flame-retardant multifunctional silk product and a preparation method thereof. Polyhexamethylene biguanide and benzene dialdehyde are added into an alcohol solution and heated for a period of time, an aldehyde-amine condensation reaction between the polyhexamethylene biguanide and the benzene dialdehyde is controlled, then a phosphite ester is added, a reaction type antibacterial and flame-retardant finishing liquid is prepared, and then a silk fabric is immersed in the finishing liquid, so that the durable antibacterial and flame-retardant multifunctional silk fabric is prepared through an immersion method. The prepared silk fabric has the advantages of synergistic antibacterial, efficient intumescent flame-retardant system and washing resistance.

Description

Technical Field

[0001] This invention belongs to the field of textile processing technology, and particularly relates to a method for preparing a durable, antibacterial, flame-retardant, multifunctional silk product. Background Technology

[0002] Silk fibers are highly absorbent, have a soft luster, a supple hand feel, and a distinctive rustling sound, earning them the title of "Queen of Fibers." my country is a major silk-producing country, ranking among the world's leading producers of silk. Silk products are widely used in high-end textiles, such as silk pajamas, cheongsams, scarves, and bedding. These applications require high levels of antibacterial and flame-retardant properties in textiles. However, silk fabrics have poor antibacterial properties, easily fostering bacterial growth and providing nutrients and energy for bacterial reproduction, ultimately endangering human health. Furthermore, silk is a flammable fiber, with a limiting oxygen index (LOI) of only 23%–24%, making it extremely flammable. Therefore, multifunctional antibacterial and flame-retardant finishing processes for silk products are of great significance.

[0003] Polyhexamethylene biguanide (PHBQ) is currently a widely used guanidine salt antibacterial agent. It primarily works by electrostatically adsorbing its positive charge onto the negatively charged bacterial cell membrane, thereby disrupting the cell membrane and achieving an antibacterial effect. It is widely used in medical devices, public environments, home furnishings, textiles, and food. However, PHBQ is a cationic polymer, which creates a repulsive reaction with the amino groups in silk fibers. Furthermore, its high water solubility results in poor wash resistance in modified silk products, making it difficult to meet practical application requirements.

[0004] Chinese invention patent CN107724075A discloses a flame retardant finishing agent for ramie fabrics. It uses phosphorus-nitrogen flame retardants, chitosan, zirconium phosphate, zinc hydroxystannate-coated halloysite nanotubes, and cerium phenylphosphonate as flame retardants, compounded with dimethylolvinyl urea, phosphoric acid, diethylene glycol, carboxylated silicone oil, epoxy silicone oil, octadecylamine polyoxyethylene ether, soybean lecithin, sodium tripolyphosphate, polyhexamethylene biguanide, nano zinc oxide sol, aloe vera glycoside, and diethylphosphonoethyltriethoxysilane, etc., to perform a multifunctional finishing process on ramie fabrics, providing flame retardancy, antibacterial properties, and UV protection. However, the amount of flame retardant used is extremely high, and the finishing agent cannot form a stable bond with the ramie fabric, resulting in poor wash resistance of the finished fabric.

[0005] Reference (Liu Jing, Zhu Huajun, Wang Qiang, et al. Electrostatic self-assembly of polyhexamethylene biguanide hydrochloride on cotton fabric and its antibacterial properties [J]. Journal of Textile Research, 2012, 33(4): 86-90.) Polyhexamethylene biguanide hydrochloride and sodium polystyrene sulfonate were electrostatically self-assembled on the surface of cotton fibers. The layer-by-layer electrostatic self-assembly method improved the wash resistance of polyhexamethylene biguanide hydrochloride antibacterial cotton fabric. However, this method requires multiple assemblies to deposit anionic and cationic compounds on the fabric surface. The process is complicated and has a serious impact on the hand feel of the fabric. It cannot be applied to the durable functional modification of silk products.

[0006] Furthermore, antibacterial finishing of silk products requires a lower dosage of antibacterial agents, offering a low-concentration, high-efficiency effect compared to flame-retardant finishing, which requires a higher dosage of flame retardant. Developing finishing agents that simultaneously possess flame-retardant and antibacterial functions without resulting in an excessively high effective concentration of antibacterial groups is a challenge. Currently, this problem is often addressed by combining antibacterial finishing agents and flame retardants, but the compatibility between the antibacterial finishing agents and flame retardants, as well as the durability of the multifunctional modification, must be considered. Developing an efficient flame-retardant system is one effective way to reduce the content of flame-retardant groups and match them with antibacterial groups. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a multifunctional silk product with excellent antibacterial and flame-retardant properties, as well as superior washability. It is prepared under mild conditions, is easy to operate, and has significant practical application value.

[0008] The first objective of this invention is to provide a method for preparing durable, antibacterial, flame-retardant, multifunctional silk products, comprising the following steps:

[0009] S1. Polyhexamethylene biguanide and phenylene dialdehyde are subjected to an aldehyde-amine condensation reaction. After the reaction is completed, phosphite is added to obtain an antibacterial and flame-retardant finishing liquid.

[0010] S2. The silk product is treated with an antibacterial and flame-retardant finishing liquid to obtain the durable antibacterial and flame-retardant multifunctional silk product.

[0011] Furthermore, the phenylene dialdehyde is selected from one or more of terephthalaldehyde, 1,3-phenylene dialdehyde, 2,5-dihydroxyterephthalaldehyde, 2-hydroxyisophthalaldehyde, and 2,5-dihydroxyterephthalic acid.

[0012] Furthermore, in step S1, the reaction temperature of the aldehyde-amine condensation reaction is 75–85°C, and the reaction time is 30–60 min. Increasing the temperature helps to promote the dissolution of phenylenedialdehyde and promote the condensation reaction of polyhexamethylene biguanide and phenylenedialdehyde.

[0013] Furthermore, in step S1, the aldehyde-amine condensation reaction is carried out in the presence of an alcohol solution.

[0014] Furthermore, the alcohol accounts for 5% to 10% of the volume of the alcohol solution system. Since phenylenedialdehyde is poorly soluble in cold water, adding alcohol helps to promote the dissolution of phenylenedialdehyde.

[0015] Furthermore, in step S2, the mass ratio of the silk product to the antibacterial and flame-retardant finishing liquid is 1:30 to 40.

[0016] Further, in step S2, the finishing temperature is 75–85°C, and the time is 40–60 min. During the finishing process, the aldehyde groups of the polyhexamethylene biguanide / phenylene dialdehyde condensate and the aldehyde groups of phenylene dialdehyde, the amino groups of the silk fibers, and the PH bonds of the phosphite can undergo covalent grafting reactions. Increasing the temperature helps to promote the reaction and makes the antibacterial and flame-retardant modification more uniform.

[0017] Furthermore, silk products include, but are not limited to, silk fibers and silk fabrics.

[0018] A second objective of this invention is to provide silk products obtained by the above-described preparation method.

[0019] The third objective of this invention is to provide a method for antibacterial and flame-retardant finishing of silk fabrics, comprising the following steps:

[0020] S1. Polyhexamethylene biguanide and phenylene dialdehyde are subjected to an aldehyde-amine condensation reaction. After the reaction is completed, phosphite is added to obtain an antibacterial and flame-retardant finishing liquid.

[0021] S2. Immerse the silk products in an antibacterial and flame-retardant finishing solution for finishing.

[0022] Preferably, the dosage of polyhexamethylene biguanide is 0.5–3 g / L. Increasing the dosage of polyhexamethylene biguanide helps to further improve the antibacterial effect of silk products, but too much dosage is wasteful.

[0023] Preferably, the amount of phenyl dialdehyde is 3-7 g / L. The aldehyde group of phenyl dialdehyde can undergo a condensation reaction with the guanidine group of polyhexamethylene biguanide, and can undergo a Schiff base reaction with the amino group of silk fiber. Increasing the amount of phenyl dialdehyde helps to promote the above reactions, but too much will be wasteful.

[0024] Preferably, the phosphite is one or more of diethyl phosphite or dimethyl phosphite, and the amount of phosphite used is 15-30 g / L. Increasing the amount of phosphite helps to improve the flame retardant effect of the finished silk products. Within the scope provided by this patent, the finished silk products can obtain a better flame retardant effect.

[0025] The fourth objective of this invention is to provide an antibacterial and flame-retardant finishing agent for silk fabrics, wherein the antibacterial and flame-retardant finishing agent is obtained by reacting polyhexamethylene biguanide and phenylene dialdehyde with an aldehyde-amine condensation reaction, followed by the addition of a phosphite at 75-85°C.

[0026] In this invention, the guanidinium group of polyhexamethylene biguanide and the aldehyde group of phenylene dialdehyde undergo a condensation reaction, which is then mixed with phosphite to prepare a reactive antibacterial and flame-retardant finishing solution. During the multifunctional finishing process, the pH bond of the phosphite can undergo a Pudovik addition reaction with the imine C=N double bond of the polyhexamethylene biguanide / phenylene dialdehyde condensate; the aldehyde group of the polyhexamethylene biguanide / phenylene dialdehyde condensate can react with the amino group of the silk fiber to form a Schiff base C=N structure; and the aldehyde group of the polyhexamethylene biguanide / phenylene dialdehyde condensate, the aldehyde group of phenylene dialdehyde, the amino group of the silk fiber, and the pH bond of the phosphite can undergo a Kabachnik-Fields reaction, thereby grafting the antibacterial and flame-retardant groups onto the silk fiber through chemical bonds, thus endowing the antibacterial and flame-retardant multifunctional silk product with excellent wash resistance.

[0027] Polyhexamethylene biguanide, as a cationic antibacterial finishing agent, mainly adsorbs bacteria through electrostatic interaction, thereby preventing bacteria from dividing and multiplying and losing their activity. At the same time, the Schiff base structure generated during the cross-linking process between the finishing agent and silk also has antibacterial properties, which can further improve the antibacterial properties of finished silk products through synergistic effects with the antibacterial finishing agent.

[0028] Polyhexamethylene biguanide, rich in nitrogen and containing phenylene dialdehyde, rich in aromatic groups, can organically combine with the phosphorus-containing flame-retardant groups of phosphite esters to construct a highly efficient intumescent flame-retardant system through a synergistic flame-retardant effect. During heating, the phosphorus-containing flame-retardant groups in this system promote the decomposition of phenylene dialdehyde and silk fibers into char, while the thermal decomposition of nitrogen-containing groups generates a large amount of non-flammable gases, causing the char layer to expand rapidly. Due to the high thermal stability of the aromatic rings and imine C=N structures, the thermal stability of the intumescent char residue is also high, effectively isolating heat and oxygen, thereby improving the flame-retardant performance of silk products. Therefore, the flame-retardant system developed in this invention has high flame-retardant efficiency, thereby reducing the amount of phosphorus-containing flame-retardant groups used and achieving compatibility with antibacterial finishing.

[0029] The beneficial effects of this invention are:

[0030] (1) The reactive antibacterial and flame-retardant finishing liquid prepared in this invention has excellent antibacterial effect due to the synergistic antibacterial properties of polyhexamethylene biguanide and Schiff base structure; at the same time, the finishing agent has high flame-retardant efficiency and can improve the flame-retardant performance of silk products through the expansion flame-retardant mechanism.

[0031] (2) In this invention, the aldehyde group of the polyhexamethylene biguanide / phenylene dialdehyde condensate reacts with phenylene dialdehyde, silk fibers and phosphite to form a covalent bond, which makes the antibacterial and flame-retardant multifunctional silk products have excellent water-washing resistance.

[0032] (3) The preparation process of the present invention is simple, the reaction conditions are mild, the process is short, and it has broad application prospects and important practical application value. Attached Figure Description

[0033] Figure 1 Images shown are vertical burning test images of the antibacterial and flame-retardant multifunctional silk products and unfinished silk products in Example 1 of this invention.

[0034] Figure 2 The antibacterial rate of the antibacterial and flame-retardant multifunctional silk products in Example 1 and Comparative Example 1 of this invention after washing;

[0035] Figure 3 The carbon length of the antibacterial and flame-retardant multifunctional silk products in Embodiment 1 and Comparative Example 1 of this invention after washing is shown. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0037] Example 1

[0038] A method for preparing a durable, antibacterial, flame-retardant, multifunctional silk product, the specific steps of which are as follows:

[0039] Polyhexamethylene biguanide and terephthalaldehyde were added to a distilled water / ethanol solution, wherein ethanol accounted for 8% of the volume ratio of the distilled water / ethanol system, the concentration of polyhexamethylene biguanide was 2 g / L, and the concentration of terephthalaldehyde was 5 g / L. The mixture was heated to 80°C and reacted for 50 min. Then, diethyl phosphite was added, with a concentration of 25 g / L, to obtain an antibacterial and flame-retardant finishing solution. Then, silk crepe fabric was immersed in the antibacterial and flame-retardant finishing solution, with a mass ratio of silk crepe fabric to antibacterial and flame-retardant finishing solution of 1:35. The mixture was kept at 80°C with shaking for 50 min. After washing and drying, an antibacterial and flame-retardant multifunctional silk crepe fabric was obtained.

[0040] Example 2

[0041] A method for preparing a highly effective and durable antibacterial silk fabric, comprising the following specific steps:

[0042] Polyhexamethylene biguanide and 2,5-dihydroxyterephthalaldehyde were added to a distilled water / ethanol solution, wherein ethanol accounted for 6% of the volume ratio of the distilled water / ethanol system, the concentration of polyhexamethylene biguanide was 1 g / L, and the concentration of 2,5-dihydroxyterephthalaldehyde was 4 g / L. The mixture was heated to 85°C and reacted for 30 min. Then, dimethyl phosphite was added at a concentration of 20 g / L to obtain an antibacterial and flame-retardant finishing solution. The silk crepe fabric was then immersed in the antibacterial and flame-retardant finishing solution at a mass ratio of 1:30. The mixture was kept at 85°C with shaking for 40 min. After washing and drying, the antibacterial and flame-retardant multifunctional silk crepe fabric was obtained.

[0043] Example 3

[0044] A method for preparing a highly effective and durable antibacterial silk fabric, comprising the following specific steps:

[0045] Polyhexamethylene biguanide and 2-hydroxyisophthalaldehyde were added to a distilled water / ethanol solution, wherein ethanol accounted for 7% of the volume of the distilled water / ethanol system, the concentration of polyhexamethylene biguanide was 1.5 g / L, and the concentration of 2-hydroxyisophthalaldehyde was 5 g / L. The mixture was heated to 83°C and reacted for 45 min. Then, diethyl phosphite was added, with a concentration of 23 g / L, to obtain an antibacterial and flame-retardant finishing solution. Then, silk crepe fabric was immersed in the antibacterial and flame-retardant finishing solution, with a mass ratio of silk crepe fabric to antibacterial and flame-retardant finishing solution of 1:33. The mixture was kept at 79°C with shaking for 55 min. After washing and drying, an antibacterial and flame-retardant multifunctional silk crepe fabric was obtained.

[0046] Example 4

[0047] A method for preparing a highly effective and durable antibacterial silk fabric, comprising the following specific steps:

[0048] Polyhexamethylene biguanide and 2,5-dihydroxyphenylene glycol were added to a distilled water / ethanol solution, wherein ethanol accounted for 10% of the volume ratio of the distilled water / ethanol system, the concentration of polyhexamethylene biguanide was 3 g / L, and the concentration of 2,5-dihydroxyphenylene glycol was 7 g / L. The mixture was heated to 82°C and reacted for 50 min. Then, diethyl phosphite was added, with a concentration of 30 g / L, to obtain an antibacterial and flame-retardant finishing solution. Subsequently, a silk crepe fabric was immersed in the antibacterial and flame-retardant finishing solution at a mass ratio of 1:38. The mixture was kept at 78°C with shaking for 60 min. After washing and drying, an antibacterial and flame-retardant multifunctional silk crepe fabric was obtained.

[0049] Comparative Example 1

[0050] A method for preparing a durable, antibacterial, flame-retardant, multifunctional silk product is basically the same as in Example 1, except that terephthalaldehyde is not added. That is, the antibacterial and flame-retardant finishing liquid contains only polyhexamethylene biguanide and diethyl phosphite, and does not contain terephthalaldehyde.

[0051] The antibacterial properties, flame retardant properties, and washability of the antibacterial and flame retardant silk fabrics prepared in Examples 1-4 and the antibacterial and flame retardant silk fabric prepared in Comparative Example 1 were tested.

[0052] The antibacterial and flame-retardant properties of silk fabrics against Escherichia coli and Staphylococcus aureus were tested in accordance with GB / T20944.3-2008 "Evaluation of antibacterial properties of textiles - Part 3: Vibration method".

[0053] The limiting oxygen index (LOI) of antibacterial and flame-retardant silk fabrics was determined according to the standard GB / T 5454-1997 "Test for Burning Performance of Textiles - Oxygen Index Method".

[0054] The damage length of antibacterial and flame-retardant silk fabrics was determined according to GB / T 5455-2014 "Determination of vertical damage length, smoldering and afterflame time of textiles".

[0055] The washing method for antibacterial and flame-retardant silk fabrics shall be in accordance with AATCC 61-2006 "Accelerated test for color fastness to washing in household and commercial use".

[0056] The final measured antibacterial and flame-retardant properties of the antibacterial and flame-retardant silk fabric are shown in Table 1 below:

[0057]

[0058] As shown in Table 1, the antibacterial effect of untreated silk fabrics is poor, with inhibition rates of only 22.3% and 21.1% against Escherichia coli and Staphylococcus aureus, respectively. The LOI of untreated silk fabrics is 23.6%, and it burns completely in the vertical burning test with a char length of 30 cm, indicating poor flame retardant properties. Silk products treated with the antibacterial and flame-retardant finishing liquid of this invention show inhibition rates of 95.1% and 94.0% against Escherichia coli and Staphylococcus aureus, respectively. When the concentration of the antibacterial finishing liquid increases, the inhibition rate against both Escherichia coli and Staphylococcus aureus can reach 99.9%, indicating that treated silk products have excellent antibacterial effects. The LOI of silk products treated with the antibacterial and flame-retardant finishing liquid of this invention increases to 29.0%, and the char length decreases to 10.9 cm. With increasing concentration of the antibacterial finishing liquid, the flame retardant properties of multifunctional treated silk products further increase, indicating that treated silk products have excellent flame retardant properties.

[0059] like Figure 2 and Figure 3As shown, the antibacterial and flame-retardant properties of the treated silk fabric gradually decrease with increasing washing cycles. This is because the antibacterial and flame-retardant groups redissolve in the washing liquid during the washing process, leading to a decline in functionality. However, after 20 washes, the antibacterial rate of the treated silk fabric against Escherichia coli and Staphylococcus aureus is still higher than 93.2% and 92.0%, respectively, and its damaged length is still less than 15 cm, meeting the requirements of Class B1 flame retardant performance in GB / T 17591-2006 "Flame-retardant Fabrics," indicating that the treated silk fabric has excellent wash resistance.

[0060] The above results show that silk products treated by the method of the present invention have excellent antibacterial properties, flame retardant properties and washability.

[0061] Comparing Example 1 with Comparative Example 1, it can be seen that the silk fabric treated in Comparative Example 1 can achieve good antibacterial and flame-retardant effects. However, after 20 washes, the inhibition rate against Escherichia coli and Staphylococcus aureus decreased to 62.5% and 60.3%, respectively, and the char length increased to 30 cm, losing its antibacterial and flame-retardant effects. This is because polyhexamethylene biguanide and phosphite cannot form stable covalent bonds with silk fibers, and polyhexamethylene biguanide is easily soluble in water and easily falls off the silk products during the washing process, thus it is not water-resistant.

[0062] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a durable antibacterial and flame-retardant multifunctional real silk product, characterized in that, The method comprises the following steps: S1, carrying out an aldehyde-amine condensation reaction on polyhexamethylene biguanide and benzene dialdehyde, and adding phosphite after the reaction is completed to obtain an antibacterial and flame-retardant finishing liquid; S2, finishing a silk product with the antibacterial and flame-retardant finishing liquid to obtain the durable antibacterial and flame-retardant multifunctional silk product; wherein the benzene dialdehyde is selected from one or more of p-phthaldehyde, 1,3-benzene dimethyl aldehyde, 2,5-dihydroxy p-phthaldehyde, 2-hydroxy m-benzene dimethyl aldehyde and 2,5-dihydroxy p-phthaldehyde.

2. The method of claim 1, wherein: In step S1, the temperature of the aldehyde-amine condensation reaction is 75-85℃.

3. The method of claim 1, wherein: In step S1, the aldehyde-amine condensation reaction is carried out in the presence of an alcohol solution.

4. The method of claim 1, wherein: In step S2, the mass ratio of the silk product to the antibacterial and flame-retardant finishing liquid is 1:30-40.

5. The method of claim 1, wherein: In step S2, the finishing temperature is 75-85℃.

6. The method of claim 1, wherein: In step S2, the finishing time is 40-60 min.

7. The silk product obtained by the preparation method in any one of claims 1-6.

8. A method for antibacterial and flame-retardant finishing of silk fabric, characterized in that, The method comprises the following steps: S1, carrying out an aldehyde-amine condensation reaction on polyhexamethylene biguanide and benzene dialdehyde, and adding phosphite after the reaction is completed to obtain an antibacterial and flame-retardant finishing liquid, wherein the benzene dialdehyde is selected from one or more of p-phthaldehyde, 1,3-benzene dimethyl aldehyde, 2,5-dihydroxy p-phthaldehyde, 2-hydroxy m-benzene dimethyl aldehyde and 2,5-dihydroxy p-phthaldehyde; S2, immersing a silk product in the antibacterial and flame-retardant finishing liquid for finishing.

9. An antibacterial and flame retardant finishing agent for real silk fabric, characterized in that: The antibacterial and flame-retardant finishing agent is obtained by carrying out an aldehyde-amine condensation reaction on polyhexamethylene biguanide and benzene dialdehyde, and adding phosphite at 75-85℃, wherein the benzene dialdehyde is selected from one or more of p-phthaldehyde, 1,3-benzene dimethyl aldehyde, 2,5-dihydroxy p-phthaldehyde, 2-hydroxy m-benzene dimethyl aldehyde and 2,5-dihydroxy p-phthaldehyde.

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