New technology of textile antibacterial finishing

1、 Plasma antibacterial finishing of textiles

Plasma surface treatment is a new technology of surface antibacterial modification. Compared with the whole material antibacterial finishing, surface treatment has more advantages in antibacterial and does not harm the properties of wood materials. After years of development, the research on the surface modification of materials by vacuum ion / plasma treatment has been greatly developed. The main methods to obtain the antibacterial properties of materials by plasma surface are ion implantation, ion beam assisted deposition (IBAD) and plasma immersion ion assisted deposition (PIII-D).

(1) Ion implantation

Ion implantation is a method of accelerating the implantation of high energy ions into solid surface under vacuum. This method can inject any kind of ions. The depth of ion implantation is related to the energy, type and matrix state of ions. Ions are in the displacement or indirect position in the solid solution, forming metastable phase or precipitate phase, which is beneficial to the corrosion resistance of the alloy. In the research field of antibacterial materials, some antibacterial elements (such as Ag, Cu, etc.) are injected into the surface of materials to achieve antibacterial function. The advantage of ion implantation is that a new alloy layer is formed on the surface of the material to change the surface state so as to obtain the antibacterial property, thus solving the connection problem between the coating surface prepared by other processes and the substrate.

(2) Ion beam assisted deposition (IBAD)

Ion beam assisted deposition (IBAD) is a new surface modification technology which integrates ion beam deposition and thin film deposition. It refers to the formation of single or compound film by bombarding and mixing with - constant energy ion beam at the same time of vapor deposition. In addition to the advantages of ion implantation, it can continuously grow films of any thickness at low bombardment energy, and can synthesize compound films with ideal chemical ratio at or near room temperature (including new films which can not be obtained at room temperature and atmospheric pressure). This technology is also called ion beam enhanced deposition (IBED), ion beam assisted coating (IAC), dynamic ion blending (DIM). The research of IBAD technology used in antibacterial materials is less and has great development potential. (3) Plasma immersion ion implantation deposition (PIII-D)

The principle of this technology is to produce plasma in the vacuum chamber in advance, and then apply negative bias voltage on the workpiece to obtain ion implantation or deposition. The biggest advantage of this technology is that it has both the ion implantation effect and the conventional ion plating effect, and people pay attention to this composite effect. It can effectively improve the physical and chemical properties of the film and composite layer, so it can be used in the research of antibacterial materials.

2、 Silver plating finishing of textiles

As mentioned before, silver coated antibacterial textiles have good antibacterial properties. The silver plating methods include chemical plating, vacuum plating and splash plating. The chemical plating process is simple, but the durability, fastness and uniformity are not ideal. The following two methods are further introduced.

(1) Vacuum silver plating antibacterial textiles

The vacuum silver plating is carried out under the condition of high vacuum, and its technical features are as follows.

(1) Use the pressure difference of vacuum to generate physical energy (easy to evaporate).

(2) In vacuum, the flight distance of released silver atom increases (because in vacuum, the energy loss of collision between released silver atom and gas molecule is reduced). When the pressure P (Torr) ● in the vacuum vessel is related to the average free path λ (CM) of the gas atom or molecule, it is λ = 102 / P. If the pressure is l0torr, λ is about 10 m. That is, the silver atom flying from the target can fly 10 m after colliding with the gas in the container.

(3) The collision between the released silver atom and the gas molecule is reduced, so that the occurrence of chemical reaction (oxidation or nitridation will be produced when colliding with air) is reduced.

(4) Keeping the surface of the coated textiles clean can improve the adhesion fastness of silver atoms and fibers. The evaporation chamber in the vacuum silver plating device is 

shown in Figure 1-13:

Figure 1-13 schematic diagram of evaporation chamber cut off in vacuum silver plating device

● Torr is a non legal unit of measurement. The legal measurement unit of pressure is PA, 1torr = 133.322p

When vacuum silver plating, the textile should not contain moisture, otherwise the vacuum degree will be reduced. Vacuum silvered Fiber Watch

The silver layer attached to the surface is very thin, and its adhesion fastness is an important problem of quality.

(2) Silver splashed antibacterial textiles

Textile splashing can be carried out in a DC secondary splashing device. First, pump the pressure in the device to (5x10-6) - (5x10-5) Torr, and then inject a small amount of argon (emotional gas) into the vacuum device to make its vacuum degree reach 0.1-0.01 Torr, The current is applied to regulate the DC voltage and current between the two poles to the range of 100-1000v and 10-200a. At this time, the discharge between the two poles will cause argon to form positive ions (Ar +, which will fly from the anode to the metal target surface on the cathode. Due to the vertical magnetic field on the surface of the metal target, Ar + appears cycloidal high-speed rotation acceleration. When Ar + collides with the gold target on the cathode, the metal on the surface of the metal target can be sputtered in atomic (or molecular) state and attached to the surface of the textile. Figure 1-14 is the schematic diagram of silver splashing processing device.

Figure 1-14 schematic diagram of sputter processing and piping

The crystal energy of metal atom (or molecule) is about 5ev, while the collision energy of Ar + is ≥ 10ev in splash plating. It can be seen that the adhesion fastness of metal in my plating is better than that in vacuum plating, and it is convenient to adjust the thickness of metal film, but the film forming speed is slow.

When sputtering, water molecules interfere with vacuum discharge, and fibers with high standard moisture content, low heat resistance and hydrophilic groups will affect the coating. For polyester, cotton and viscose fiber, the experiments of copper splashing by magnetron (MC) and high frequency (RF) show that polyester fabric is easy to be splashed, and magnetron is more suitable than high frequency. When cotton and viscose fiber become bronze after splashing, it indicates the disappearance of metallic luster. The air permeability of sputtered polyester does not change, which is wrapped on the surface of each fiber with metal film instead of adhering to the fiber 

The gap is related. Compared with untreated textiles, the rigidity and flexibility of sputtered textiles vary from 4% to 24%, that is to say, they tend to harden slightly, which is similar to that of resin finishing and heat setting.

Magnetron sputtering is a high-speed, low-temperature coating method. The film prepared by magnetron sputtering is uniform and firm, beautiful in color and variety. At present, there are few researches on the application of magnetic controlled lasing in antibacterial materials, but there will be more room for development in combination with other surface modification processes.

Beijing jieershuang High Tech Co., Ltd. has developed a new type of silver coated fiber and fabric by using multi rake magnetron vacuum sputtering and composite coating technology. The nano silver and fiber sputtered are polymerized into one, and the fiber surface forms a solid oxide resistant film structure. Among them, the low silver content fiber has excellent antibacterial performance, which is used in the wide frequency range of severe medical dressings such as burns; it shields more than 99.99% electromagnetic waves, has a resistance of less than 1.5 Ω / cm, is resistant to washing for 100 times, and has the characteristics of antibacterial deodorization, antistatic, temperature control, moisture absorption and quick drying, good air permeability, light and soft, can be worn close to the body, anti-oxidation, etc.

2、 Renewable antibacterial finishing

In general, the antibacterial properties of textile materials can be obtained by combining functional finishing agents with textiles by chemical or physical methods. The durability of antibacterial properties of textile materials can be classified into two categories: temporary and durable. The temporary antibacterial property of textiles is easy to obtain in finishing, but easy to lose in washing; and the durability of antibacterial textiles is mostly achieved by slow-release method. According to this method, enough antibacterial finishing agents should be combined into textiles in the wet finishing process. The treated textiles slowly release antimicrobial agents from the material, thus making the bacteria inactive. However, if the antibacterial agent enters the material without covalent bond with the fiber, they may disappear completely in the long-term use. Once the antibacterial agent disappears gradually in the textile, the function of the assigned sub will be reduced until it is lost, and become a kind of non renewable finishing.

(1) Renewable mechanism (halogen Chemistry)

In order to realize the renewability of antibacterial function, a new finishing method has emerged, which is the development of theoretical model proposed in the 1962 report of Gagliardi. According to this process, in the new process, the parent (potential antibacterial agent) of the antibacterial compound replaces the antibacterial agent itself and is applied to the antibacterial treatment of cellulose materials. Before the group with antibacterial function is activated, the parent of the antibacterial compound is covalently bound to the cellulose material, and then it can be activated by a reversible chemical process (such as an oxidation-reduction reaction) to release the group with antibacterial function. This finishing method is similar to the wrinkle resistant finishing process. Activation can be achieved in a conventional process, such as bleaching, whereby the antibacterial properties of textiles can also be regenerated. The release process of antibacterial agent is as follows:

The potential antibacterial agent is a hydantoin derivative, i.e. monohydroxymethyl-5,5-dimethylhydantoin compound is a compound with heterocyclic structure, i.e. hydantoin ring. The structure is as follows:

The infrared light potential of the hydantoin compound is 1720cm-1 and 1770cm-1. There are two prominent stretching bands, which correspond to two carbonyls on its ring. This is the characteristic absorption of the hydantoin structure. The intensity of DMH and mdmh in these two bands is obviously different. Therefore, the bands at 1720 < M-1 and 1770 cm-1 can be used to characterize the grafting of intraacyl vein onto the fabric.

The ring structure of hydantoin is similar to that of DMDHEU, another popular textile chemical widely used in durable setting finishing. In the molecular structure of mdmh, there are two methyl groups on the a-position carbon atom adjacent to the nitrogen atom, unlike hydantoin, which is hydrogen atom, so after NH chlorination of the former

There is no chance to eliminate HCI, resulting in a relatively stable structure of chloroprene rubber, without yellowing and air loss of the fabric. In addition to the specific structure of the bond, the stability of hydantoin halide may also be due to its unique heterocyclic structure. This special stability of hydantoin halide has made it widely used in many practices. For example, dihalo-5,5-dimethylhydantoin is an excellent chlorine stabilizer and Hangzhou bacterial agent, which is widely used in swimming pools.

Halogenated hydantoin is not only a stabilizer for chlorine or bromine, but also an effective disinfectant. It has been reported that haloamines are polymers with oxidation function. The halogen elements (such as chlorine and bromine) in the halogen amine bond are positively charged, which can oxidize many chemical structures, so the halogen amine bond can show antibacterial properties. In addition, the halogen amine bond on the hydantoin ring can be dehalogenated and halogenated reversibly without ring cracking.

This is an important reversible redox reaction. Among them, the halogenation reaction is completed by chlorine bleaching, and the dehalogenation process is to inactivate microorganisms through disinfection and other functions. Therefore, a reproducible antibacterial system is established by the chemical reaction of haloamines. This unique property has also been used in the preparation of renewable polymer disinfectants.

(2) Antibacterial and regenerative properties of haloamines

The renewable antibacterial haloamines polymers were developed on the basis of controlling the structural and chemical properties of haloamines. The cellulose fabric was treated with the monohydroxymethyl-5,5-dimethylhydantoin (mdmh). Mdmh has two functional groups, in which hydroxymethyl can react with the hydroxyl group on the molecular chain of cellulose fiber to form covalent bond (grafting reaction occurs); secondary amino group can be treated with solution containing effective chlorine to form halogen amine structure, and the

reaction formula is as follows. 

Heterocyclic haloamines produce positively charged chloride ions (Cl +) during decomposition

The covalent gas in the structure of halogen amine has strong polarity, so that part of the positively charged chlorine (Cl +).

It can oxidize many proteins or some organic compounds, leading to microbial inactivation; after chlorination, the chlorine atom is reduced to chloride, and the halogen amine bond is converted to secondary amino group, which can be regenerated after re chlorination. Its antibacterial and renewable properties can be expressed as follows.

(3) Bactericidal, pesticide detoxification and durability of mdmh finishing

1. The antibacterial function of mdmh treated fabric is very durable after repeated washing test, especially the fabric treated with high concentration of mdmh. This durability can be attributed to the covalent bond between the hydantoin ring and the cellulose chain. The N-H bond of amides and imines on the hydantoin ring is very active, which can form halogen amine structure with halogen. Normal chlorine bleaching process can easily regenerate the activated halogen amine bond without losing the covalent bond on the fabric, so each washing and regeneration cycle can fully restore the antibacterial function of the fabric.

2. The detoxification and durability of pesticides polymers containing effective chlorine and peroxides can be used as antidotes to decompose pesticides. The oxidation function of polymers has been extensively studied. It is reported that haloaminated polymers can convert alcohols into ketones, sulfides into sulfoxides and sulfoxides, and cyanide into carbon dioxide and ammonia in water.

As mentioned above, after the haloamination treatment, the vinylon fiber has durable and renewable antibacterial properties, effectively inactivating microorganisms.

The pesticide detoxification process of haloaminated fabric can be completely expressed by the above-mentioned reaction formula of sterilization and regeneration of haloaminated polymer. Through the durability test of the finished fabric, we can clean the fabric after detoxification test, wash off the decomposition of pesticides, then carry out air bleaching treatment, and then determine its detoxification ability. According to the setting of many researchers, one washing on the washing fastness tester is equivalent to five conventional mechanical washing at the same temperature. The results show that after the haloamination treatment, it can withstand 50 times of conventional mechanical washing, so it can be considered to meet the durability requirements.

The durable, recyclable and antibacterial finishing of fabrics has many advantages, such as durable and renewable antibacterial functions; on fabrics, the activation and regeneration of specific functions are simple and convenient; antibacterial fabrics have broad-spectrum antibacterial properties. However, this anti-bacterial finishing process can only be applied to cellulose materials and polyester / cotton fabrics to obtain excellent anti-bacterial effect and narrow application range. At the same treatment concentration, the antibacterial property of T / C fabric is better than that of cotton fabric. The reason may be that, except for the influence of polyester, although the total grafting amount of mdmh on T / C fabric is lower than that on cotton fabric, the grafting rate of cellulose fiber is higher than that on cotton fabric. The antibacterial effect, durability and regeneration of the new technology are ideal, but the grafting rate is low (about 20%) according to the industrial requirements, which needs to be improved.

(4) Synthesis of regenerated antibacterial agent of hydantoin

Take 25ml of 0.05mol DMH (Dimethylhydantoin) aqueous solution, add 0.05ml Koh, mix with 0.05mol allyl bromide ioml, and stir at 60 ℃ for 2h. After cooling, the solid was dried in vacuum at room temperature and crystallized in petroleum ether. The crystal was organic antibacterial agent ad-mh.

ADMH can form its modifier under certain conditions, and then through chlorination regeneration treatment, the modified organic regeneration antibacterial agent can be obtained.

Under the action of initiator, ADMH can form graft copolymers on fibers through graft copolymerization. After chlorination and regeneration, ADMH has good antibacterial effect and broad-spectrum antibacterial property.

3、 Application of nanotechnology in antibacterial finishing of textiles

Nanoparticle is a metastable intermediate substance between solid and liquid. Nano materials have the characteristics of surface effect, quantum size effect and macro quantum tunneling effect, which are different from the conventional materials in mechanical, optical, thermal, magnetic, catalytic performance and biological activity. They have many new functions and wide application prospects. At present, the research on the physical properties, preparation technology, test methods and other aspects of nano antibacterial materials has made rapid development, which has attracted the attention of all countries in the world. Nano antibacterial materials can be divided into natural nano antibacterial materials, organic nano antibacterial materials and inorganic nano antibacterial materials. In addition, nano antibacterial materials can also be classified according to the structure, carrier type and antibacterial active ingredients.

With the development of nanotechnology, nano silver inorganic antibacterial agents have appeared in recent years. Nano silver antibacterial powder can be widely used in plastics, ceramics, fibers and other products because of its uniform dispersion and no special requirements for processing technology. The antibacterial agent is neutral, insoluble in water and organic solvent, resistant to acid, salt and weak base, and has good heat and light stability. It depends on contact reaction to destroy microbial activity. Its antibacterial component is silver ion, and its antibacterial effect is lasting. At the same time, under the action of light, silver ion can play the role of catalytic active center, activate the oxygen in water and air, produce active oxygen ion, while active oxygen ion has strong oxidation ability, can destroy the reproduction ability of bacteria in a short time, cause cell death, so as to achieve antibacterial purpose.

Through physical adsorption and ion exchange, silver ions are fixed on the surface of zeolite, ceramics, silica gel and other porous materials to make antibacterial agents, and then nano materials are added to the corresponding products to obtain antibacterial materials. With silver complex as the main antibacterial body and nano-TiO2 and SiO2 as the carrier, the special effect of nano-sized powder particles greatly improves the overall antibacterial effect, making the temperature resistance, powder fineness, dispersion and functional effect fully play. The treatment effect of other metal ions is worse than that of silver ions. For example: Mercury, cadmium, nickel, cobalt, lead and other metals also have antibacterial ability, but are harmful to human body; copper plasma has color, which affects the beauty of products; zinc has certain antibacterial ability, but its antibacterial strength is only 1 / 1000 of silver. Therefore, silver ion antibacterial agents play a leading role in inorganic antibacterial agents.

The preparation methods of nano antibacterial materials can be divided into post addition method and bulk addition method according to the structure of antibacterial nano sustained-release carrier.

1. Post addition method post addition method is carried out by loading antibacterial ions on the existing inorganic nano materials. It can be divided into ion exchange method and complexation coating method. Among them, the ion-exchange method uses the antibacterial metal ions to exchange with the cations such as sodium, potassium and calcium, which play the role of balancing the electricity price in the carrier, so as to give the carrier antibacterial function. This method is the most common method for the preparation of nano antibacterial materials. In principle, it can be applied to inorganic carriers with exchangeable cations in - cut structure, such as frame silicate, layered silicate, phosphate and many other minerals with abundant holes or channels inside. The complex one is coated by antibacterial Gold Phoenix ions and complexing agent sodium thiosulfate and then complexed with silica gel to absorb negatively charged complex metal ions or metal ions. Finally, the antibacterial product is obtained by sol-gel method coated with silicon dioxide film. -In general, the nano antibacterial materials prepared by complex coating method have excellent stability.

2. Bulk addition method bulk addition method refers to the synthesis method of nano antibacterial materials with antibacterial ions as one of the raw materials and nano carriers. This method is mainly used in the preparation of soluble glass antibacterial materials, that is, the salt resistant to South metal ions is taken as a component in the composition design, and the glass antibacterial materials are prepared according to the usual preparation method of glass. In addition, the preparation of silver bearing apatite can also be realized by adding silver ion salt into the raw material.

(3) Application of nano antibacterial powder

1. Main problems to be solved in the application of nano antibacterial ceramic powder in textiles

(1) How to make the ceramic body and the ground on the textile.

(2) Ceramic powder is inorganic, fabric fiber is polymer, how to realize the solid combination of inorganic and organic.

(3) How to reduce the yellowing of bleached fabrics (especially after sun exposure) and the discoloration of dyed fabrics caused by Ag +.

2. A more mature method of dispersing and fixing nano ceramic powder on textiles

(1) Coating printing. That is to say, ceramic powder is uniformly applied on the surface of textile by adhesive, or mixed in the printing paste, and the combination of ceramic powder and textile is realized by printing process. The process of this method is simple, and it can achieve certain functional indexes. However, the dispersion of ceramic powder on textiles is difficult to be uniform, and because there is no bond between ceramic powder (inorganic matter) and fabric (organic matter), the washing fastness is low, the function is not durable, at the same time, the hand feel is hard and the air permeability is poor, so it has been washed out gradually.

(2) Spinning method. The method of dispersing ceramic powder in melt solution of polyester (or polypropylene fiber) and spinning into fiber can achieve better combination effect of ceramic powder and textile, but the production process is complex, the production is difficult, the yield is low, and the cost is high. In addition, this method can only be applied to chemical fiber textiles, but not to natural fibers, which limits its wide application.

In addition to the above two methods, there are a variety of antibacterial finishing technologies based on nano antibacterial technology. Nano antibacterial material is the cutting-edge field of science and technology in the 21st century. There will be more and more comfortable, fashionable, green, bad and healthy products produced with nano antibacterial material. It will guide people to change the treatment after the medical and health care mode into prediction and prevention in advance.

(3) Examples of nano silver inorganic antibacterial agents

1. Hangzhou bacteria finishing agent scj-951

(1) characteristics. The antibacterial finishing agent scj-951 is a white powder with the particle size of nanometer, which can be dispersed in water, non-toxic, non combustible, non explosive, and safe for human body.

(2) use. The antibacterial finishing agent scj-951 has good safety and high efficiency. It is suitable for antibacterial finishing of cotton, polyester / cotton, nylon and other fabrics. Such as the production of antibacterial, deodorant indoor decorative fabrics, socks, carpets, nonwovens, shoe fabrics, air filter materials and other textile products and functional fibers with low hand feel requirements. Several domestic authoritative health units have tested and proved that scj-951 antibacterial finishing fabric has obvious antibacterial, deodorant and antipruritic effects, with an antibacterial rate of more than 99.9% for bacteria, fungi and molds, no irritation and allergic reaction to skin, no toxicity to human body, and significant effect on prevention and treatment of sweat, foot odor and skin itch.

(3) Process flow. Scj-951 can be used to treat fabric by dip rolling, coating and brushing. The dosage of scj-951 is 2% - 3% (OWF). The specific dosage depends on the variety and use of the treated fabric.

Dip rolling process:

Fabric - dyeing and drying → immersion rolling and anti-treatment solution (rolling liquid rate 70%) → drying (80-110 ℃, with moisture free degree of fabric) → stretching (180 ℃, 30s or 150 ℃, 2min)

(4) Process formula.

Antibacterial agent scj-951      20-40g / L

Antibacterial agent scj-959      40-80g / L

2. Nano silver antibacterial and deodorizing powder scj-120

(1) characteristics. Scj-120 is a kind of antibacterial odorant specially developed for synthetic fiber. It can be dispersed in synthetic resin slice, sponge, rubber, plastic and other materials. Scj-120 is a light white powder. Its main component is nano silver anti odor powder.

(2) Preparation of antibacterial synthetic fiber.

Process formula:

Nano silver antibacterial deodorant scj-120   1% - 3%

PP or PET chips                                                   97% - 99%

Process flow: mixed full granulation → spinning → finished product

(4) Nano antibacterial biological protein fiber

Some people use wool, cow hair and camel hair which have no value to prepare keratin solution suitable for spinning, then add the protein solution to cellulose, and evenly disperse the nano antibacterial powder in the protein spinning solution to prepare better antibacterial protein fiber. The addition amount of inorganic antibacterial agent is 0.5% - 5.0%. This technology marks the successful docking of biotechnology and modern textile technology. Nano antibacterial biological protein fiber retains the natural wool component, has the hand feeling of wool and cashmere, and increases the style of silk smoothness, with a sense of draping and straightness, the fabric has soft hand feeling, strong moisture absorption, good dyeing, bright luster, protein fiber is rich in a large number of amino acid components, good serviceability, no wrinkle, no wool, no pilling, no static electricity, strong spinnability. The inhibition rates of Escherichia coli, Staphylococcus aureus and Candida albicans were 99.6%, 97.7% and 99.9%, respectively.


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