A method for flame-retardant finishing of polyester by graft modification

Abstract

The application discloses a method for flame-retardant finishing of polyester by graft modification, and belongs to the technical field of textile dyeing and finishing. Specifically, first, polyester fabric is treated by means of ester hydrolase to hydrolyze ester bonds on the surface of the polyester fabric to generate hydroxyl groups; then, methacrylic anhydride is reacted with the hydroxyl groups on the surface of the polyester fabric to introduce vinyl groups on the surface of the polyester fiber; finally, the polyester fabric is immersed in a mixed solution of vinyl phosphonic acid and N,N'-methylene bisacrylamide, and graft polymerization is catalyzed by horseradish peroxidase to form a polyvinyl phosphonic acid layer on the surface of the polyester, thereby realizing the method for flame-retardant finishing of the polyester. The specific steps include: (1) ester hydrolase pretreatment of the polyester; (2) introduction of vinyl groups on the surface of the polyester; and (3) graft polymerization catalyzed by horseradish peroxidase. Compared with the traditional baking finishing method, the method has good flame-retardant finishing, and avoids the shortcomings of easy strength decrease of the polyester and high production energy consumption in the traditional high-temperature baking finishing method.

Description

Technical Field

[0001] This invention relates to a method for flame-retardant finishing of polyester through grafting modification, belonging to the field of textile dyeing and finishing technology. Background Technology

[0002] Flame-retardant textiles have long been used in specialized industries such as firefighting and the military. In recent years, with technological advancements and improved living standards, people's safety awareness has increased, leading to higher demands for flame-retardant properties in everyday clothing and interior decoration fabrics. To reduce the loss of life and property caused by fires, countries worldwide have dedicated themselves to researching new flame-retardant technologies for fabrics, developing textiles with excellent flame-retardant properties, and enacting various regulations that strictly define the flame-retardant performance of specific textiles. Polyester is a commonly used synthetic fiber raw material, widely used in sportswear and outdoor clothing fabrics. Compared to natural cotton fibers, polyester fabrics not only have higher fiber strength and a smoother feel but also excellent shape retention, making them widely used in home textiles such as curtains, screens, and bedding. However, polyester fiber has a limiting oxygen index of 20%–22%, classifying it as a flammable fiber, which does not yet meet the requirements of some specific applications. Therefore, flame-retardant finishing can be applied to polyester fabrics to broaden their application range.

[0003] Flame-retardant finishing of polyester fabrics can be achieved using two main methods. First, the fabric is woven from flame-retardant polyester fibers, where flame-retardant materials are added during the melt spinning process of synthetic fibers to create flame-retardant fibers. However, due to limitations in the amount of flame-retardant materials added, this type of flame-retardant fiber generally does not achieve the desired flame-retardant effect and is rarely used. Second, the fabric is finished using finishing methods. Based on the characteristics of the flame retardant, this can be divided into non-durable flame-retardant finishing and durable flame-retardant finishing. The former often involves padding and drying the fabric with solutions of certain concentrations of borax-boric acid, ammonium polyphosphate, magnesium hydroxide, etc., resulting in a poor hand feel and lack of wash resistance. Durable flame-retardant finishing processes often use phosphorus-nitrogen-based flame retardants as finishing agents, employing methods including padding and baking, high-temperature bonding, or coating. These finishing agents can react with polyester fibers or form a film on the surface of the polyester fibers, thus providing better wash resistance. Durable flame-retardant finishing, due to its high processing temperature, while imparting flame-retardant properties to fabrics, also suffers from drawbacks such as fiber strength damage during high-temperature baking, leading to yellowing and a deterioration in hand feel. Therefore, optimizing the flame-retardant finishing process to improve the flame retardancy of polyester fabrics while minimizing fiber damage is a key area of ​​research.

[0004] Enzymatic finishing of polyester offers advantages such as low processing temperature, mild reaction conditions, minimal fiber damage, and avoidance of yellowing issues associated with high-temperature baking. Therefore, enzymatic pretreatment of polyester can be considered to catalyze the hydrolysis of surface ester bonds to generate hydroxyl groups, followed by a reaction with methacrylic anhydride to introduce vinyl groups onto the polyester fibers. Finally, graft polymerization with phosphorus-containing vinyl monomers is performed to achieve flame-retardant finishing of polyester fabrics based on enzymatic graft polymerization. Compared to traditional chemical finishing methods, this biological approach increases the reactivity of polyester fibers, enabling flame-retardant finishing under mild conditions, and offers advantages such as energy saving, reduced consumption, safety, and high efficiency. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for flame-retardant finishing of polyester through grafting modification. Using this invention can improve the flame retardancy of polyester fabrics and solve the technical problems of high energy consumption, decreased fabric hand feel, and yellowing in traditional high-temperature baking flame-retardant finishing methods, thereby achieving the goal of optimizing the flame-retardant finishing effect.

[0006] The technical solution of this invention: A method for flame-retardant finishing of polyester through graft modification, characterized in that: firstly, the polyester fabric is treated with an enzymatic hydrolysate to hydrolyze the ester bonds on the polyester surface to generate hydroxyl groups; then, methacrylic anhydride reacts with the hydroxyl groups on the polyester surface to introduce vinyl groups onto the polyester fiber surface; finally, the polyester fabric is immersed in a mixed solution of vinylphosphonic acid and N,N'-methylenebisacrylamide, and graft polymerization is catalyzed by horseradish peroxidase to form a polyvinyl phosphate layer on the polyester surface, thereby achieving flame-retardant finishing of polyester. The specific process steps are as follows:

[0007] (1) Polyester ester hydrolysin pretreatment: Polyester fabrics were pretreated with ester hydrolysin.

[0008] Processing formula and conditions: ester hydrolase 2~5 U / mL, temperature 40~60℃, pH range 8.0~9.5, treatment time 3~6 hours;

[0009] (2) Polyester grafting modification: The polyester fabric treated in step (1) is treated with methacrylic anhydride and then washed with deionized water to obtain the modified polyester fabric.

[0010] Treatment process formulation and conditions: methacrylic anhydride 2~5 g / L; treatment temperature 0~4℃, pH range 8~9, time 12~24 hours;

[0011] (3) Horseradish peroxidase-catalyzed grafting: The polyester fabric treated in step (2) was immersed in a mixed solution of vinylphosphonic acid and N,N'-methylenebisacrylamide, horseradish peroxidase and acetylacetone were added, and H2O2 was added under nitrogen protection to promote the formation of polyvinyl phosphate on the polyester surface through grafting polymerization.

[0012] Treatment process formula and conditions: horseradish peroxidase 2.5~5 U / mL, acetylacetone 4~8 g / L, H2O2 1.5~5 g / L, vinylphosphonic acid 15~50 g / L, N,N'-methylenebisacrylamide 1~2.5 g / L, treatment temperature 30~40℃, pH 6.5~7.5, time 3~12 hours; after treatment, the polyester fabric is washed with water at room temperature for 10 minutes and dried at 105℃.

[0013] A method for flame-retardant finishing of polyester by grafting modification, wherein the ester hydrolase includes keratinase, lipase and polyester hydrolase derived from animals, plants or microorganisms.

[0014] Beneficial effects:

[0015] This invention first utilizes ester hydrolase to pretreat polyester fabrics, and then uses horseradish peroxidase to catalyze free radical graft polymerization to form a phosphorus-containing flame retardant layer with a network structure on the surface of the polyester fibers, thereby improving the flame retardant effect. Compared with traditional high-temperature baking flame retardant finishing, this invention has the following advantages:

[0016] (1) The reaction conditions are mild. The present invention uses ester hydrolase and horseradish peroxidase to catalyze the hydrolysis and graft polymerization of polyester under low temperature and near-neutral conditions, avoiding the defects of high temperature baking and finishing that can easily cause the fabric to lose its hand feel or turn yellow.

[0017] (2) Low production energy consumption. This invention introduces vinyl groups into the polyester surface after generating hydroxyl groups, and then performs enzymatic graft polymerization with vinylphosphonic acid. This not only improves the flame retardancy of polyester fabrics, but also achieves low-energy finishing processing.

[0018] (3) The finishing effect is long-lasting. When the enzymatic grafting polymerization of polyester surface generates polyvinyl phosphate, N,N'-methylenebisacrylamide and vinyl phosphonic acid are copolymerized. Therefore, a network cross-linked structure can be formed on the polyester fiber surface, which not only increases the flame retardant effect of polyester, but also has a longer-lasting finishing effect and is also conducive to maintaining the strength of polyester. Detailed implementation method:

[0019] Polyester was treated with ester hydrolase, and vinyl groups were introduced through a reaction with methacrylic anhydride. Then, polyvinyl phosphate was grafted onto the polyester fabric using horseradish peroxidase to achieve flame retardancy. The flame retardancy of the treated polyester fabric was determined according to the oxygen index method in GB / T 5454-1997, and the drape coefficient was determined according to the breaking strength of the fabric in GB / T 3923.1-1997 using the image method. Specific examples are as follows:

[0020] Example 1:

[0021] (1) Polyester keratinase pretreatment: Polyester fabric was pretreated with keratinase; Treatment process formula and conditions: 2 U / mL keratinase, treated at 45℃ and pH 8.0 for 3 hours;

[0022] (2) Introducing vinyl groups onto polyester surface: The polyester fabric treated in step (1) is treated with methacrylic anhydride and then washed with deionized water to obtain modified polyester fabric; Treatment process formula and conditions: 2 g / L methacrylic anhydride, treated at 0℃ and pH 8 for 12 hours.

[0023] (3) Horseradish peroxidase-catalyzed graft polymerization: The polyester fabric treated in step (2) was immersed in a mixed solution of vinylphosphonic acid and N,N'-methylenebisacrylamide, horseradish peroxidase and acetylacetone were added, and H2O2 was added under nitrogen protection to promote the formation of polyvinylphosphonic acid on the polyester surface through graft polymerization; the treatment process formula and conditions were: horseradish peroxidase 2.5 U / mL, acetylacetone 4 g / L, H2O2 1.5 g / L, vinylphosphonic acid 15 g / L, N,N'-methylenebisacrylamide 1 g / L, treated at 30℃ and pH 6.5 for 3 hours; the treated polyester fabric was washed with water at room temperature for 10 minutes and dried at 105℃;

[0024] Sample 1: Untreated polyester fabric

[0025] Sample 2: Processed using traditional flame-retardant finishing technology, polyester fabric was impregnated with a finishing solution consisting of 15 g / L polyvinyl phosphate and 2.5 g / L adhesive, and baked at 175℃ for 3 minutes;

[0026] Sample 3: processed in steps (1) and (3), but not in step (2);

[0027] Sample 4: processed by steps (1), (2) and (3);

[0028] After the above-mentioned processing, the limiting oxygen index (LOI), fabric strength, and drape coefficient of samples 1-4 were measured respectively. Specifically, sample 1 had a limiting oxygen index (LOI) of 20.1% and a drape coefficient of 46%; sample 2 had a limiting oxygen index (LOI) of 29.2%, fabric strength decreased by 6.5% compared to sample 1, and a drape coefficient of 57%; sample 3 had a limiting oxygen index (LOI) of 21.5%, fabric strength decreased by 3.1% compared to sample 1, and a drape index of 49%; and sample 4 had a limiting oxygen index (LOI) of 30.1%, fabric strength decreased by 1.2% compared to sample 1, and a drape index of 50%.

[0029] Example 2:

[0030] (1) Polyester pretreatment with polyester hydrolase: Polyester fabric was pretreated with polyester hydrolase; Treatment process formula and conditions: 5 U / mL polyester hydrolase, treated for 6 hours at 60℃ and pH 9.

[0031] (2) Introducing vinyl groups onto polyester surface: The polyester fabric treated in step (1) is treated with methacrylic anhydride and then washed with deionized water to obtain modified polyester fabric; Treatment process formula and conditions: 5 g / L methacrylic anhydride, treated at 4℃ and pH 9 for 24 hours.

[0032] (3) Horseradish peroxidase-catalyzed graft polymerization: The polyester fabric treated in step (2) was immersed in a mixed solution of vinylphosphonic acid and N,N'-methylenebisacrylamide, horseradish peroxidase and acetylacetone were added, and H2O2 was added under nitrogen protection to promote the formation of polyvinylphosphonic acid on the polyester surface through graft polymerization; the treatment process formula and conditions were: horseradish peroxidase 5 U / mL, acetylacetone 8 g / L, H2O2 5 g / L, vinylphosphonic acid 50 g / L, N,N'-methylenebisacrylamide 2.5 g / L, and treated at 40℃ and pH 7.5 for 12 hours; the treated polyester fabric was washed with water at room temperature for 10 minutes and dried at 105℃.

[0033] Sample 5: Untreated polyester fabric

[0034] Sample 6: Processed using traditional flame-retardant finishing technology, the polyester fabric was impregnated with a finishing solution consisting of 50 g / L polyvinyl phosphate and 5 g / L adhesive, and baked at 175℃ for 3 minutes;

[0035] Sample 7: processed in steps (1) and (3), but not in step (2);

[0036] Sample 8: processed by steps (1), (2) and (3);

[0037] After the above-mentioned processing, the limiting oxygen index (LOI), fabric strength change rate, and drape coefficient of samples 5-8 were measured respectively. Specifically, sample 5 had a limiting oxygen index (LOI) of 20.8% and a drape coefficient of 53%; sample 6 had a limiting oxygen index (LOI) of 28.2%, fabric strength decreased by 4.1% compared to sample 5, and a drape coefficient of 68%; sample 7 had a limiting oxygen index (LOI) of 21.3%, fabric strength decreased by 0.9% compared to sample 5, and a drape index of 54%; and sample 8 had a limiting oxygen index (LOI) of 29.4%, fabric strength decreased by 1.3% compared to sample 5, and a drape index of 55%.

[0038] The results show that, compared with untreated samples 1 and 5, samples 2 and 6, after flame-retardant finishing using the traditional high-temperature baking method, have higher LOI values, but their strength decreases significantly at high temperatures, and their fabric drape is poor. The flame-retardant effect of samples 3 and 7, which were directly grafted with polyvinylphosphonic acid after ester hydrolysis, is not ideal because the polyester surface lacks vinyl reaction sites, preventing the vinylphosphonic acid monomer from undergoing graft polymerization with the polyester fiber during horseradish peroxidase catalysis. Samples 4 and 8, treated with the method described in this invention, not only have better flame-retardant effects but also show no significant decrease in fabric strength and good fabric drape. Therefore, the flame-retardant finishing method described in this invention for polyester fabrics has a good finishing effect.

[0039] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for flame retardant finishing of polyester by graft modification, characterized in that The method comprises the following steps: firstly, treating the polyester fabric with an ester hydrolytic enzyme to hydrolyze the ester bond on the surface of the polyester fabric to generate hydroxyl groups; then, introducing vinyl groups on the surface of the polyester fiber by reacting methyl acrylate with the hydroxyl groups on the surface of the polyester fabric; and finally, immersing the polyester fabric in a mixed solution of vinyl phosphonic acid and N,N'-methylene bisacrylamide, and forming a polyvinyl phosphonic acid layer on the surface of the polyester fabric by graft polymerization catalyzed by horseradish peroxidase, so as to realize the flame-retardant finishing of the polyester fabric; The specific process steps of the method are as follows: (1) polyester ester hydrolytic enzyme pretreatment: pretreating the polyester fabric with an ester hydrolytic enzyme; Treatment process prescription and conditions: ester hydrolytic enzyme 2-5 U / mL, temperature 40-60 DEG C, pH range 8.0-9.5, treatment time 3-6 hours; (2) introducing vinyl groups on the surface of the polyester: treating the polyester fabric treated in step (1) with methyl acrylate, and washing the treated fabric with deionized water to obtain modified polyester fabric; Treatment process prescription and conditions: methyl acrylate 2-5 g / L; treatment temperature 0-4 DEG C, pH range 8-9, time 12-24 hours; (3) horseradish peroxidase catalyzed graft polymerization: immersing the polyester fabric treated in step (2) in a mixed solution of vinyl phosphonic acid and N,N'-methylene bisacrylamide, adding horseradish peroxidase, acetylacetone, and H2O2 under nitrogen protection, so as to promote the formation of a polyvinyl phosphonic acid layer on the surface of the polyester fabric by graft polymerization; Treatment process prescription and conditions: horseradish peroxidase 2.5-5 U / mL, acetylacetone 4-8 g / L, H2O2 1.5-5 g / L, vinyl phosphonic acid 15-50 g / L, N,N'-methylene bisacrylamide 1-2.5 g / L, treatment temperature 30-40 DEG C, pH 6.5-7.5, time 3-12 hours; after finishing, the polyester fabric is washed in water at room temperature for 10 minutes and dried at 105 DEG C.

2. The method of claim 1, wherein, The ester hydrolytic enzyme includes cutinase, lipase and polyester hydrolytic enzyme derived from animals, plants or microorganisms.