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Introduction of aromatic fiber

The textiles produced by aromatic fiber are known as the "second skin" of human beings. It can create a microclimate for people's life, and people can create the environment they like according to their own wishes. For example, the fragrance of lavender, geranium, chamomile, Achyranthes bidentata, basil, sage, honeysuckle, jasmine, rose, lemon and cinnamon can be used for bed sheet, quilt cover, curtain, carpet and pajamas These fragrances help to eliminate fatigue, improve sleep, relieve high blood pressure, kill bacteria, and play a variety of special functions such as sedation, calming and awakening The Japanese first put forward the concept of "forest bath" in the development of aromatic products. It was found that the special function of forest bath was due to the presence of a terpene in the fragrance emitted by trees. It can not only produce some sedative or exciting effects on human physiology, but also has the efficacy of killing or inhibiting bacteria, mold and other microorganisms, and even has some medicinal functions on human body.

Preparation of aromatic fiber

The preparation principle and method of aromatic fiber: the aromatic fiber is made of natural or synthetic aromatic agents into fragrant masterbatch or microcapsule. It is added to spinning solution or melt or impregnated with fiber, and then a kind of functional fiber is produced by impregnating, spraying, blending, grafting and spinning. According to the different processing technology of aromatic fiber, the main preparation methods of aromatic fiber are: blending melt spinning, composite spinning, microencapsulation and grafting

1.1 blending melt spinning

The principle of blending melt spinning method: blending melt spinning method is to prepare aromatic fiber, which is to make different types of perfume and spinning raw materials into fragrance masterbatch, and then blend and melt spinning with a certain proportion of chips to melt perfume molecules in the fiber, so that the fiber has natural fragrance On the one hand, because of the high melt spinning temperature, which generally exceeds 200 ℃, the perfume is required to have high heat resistance; On the other hand, in order to make the perfume volatilize continuously at room temperature, it is required to have a lower boiling point. This condition makes the choice of high boiling point and good thermal stability perfume which can meet the requirements of high temperature spinning very limited.

The way to solve the high demand of perfume for CO blended yarn is to select the fiber forming polymer with lower spinning temperature and aromatic agent with higher boiling point for CO blended yarn.

For example, in 2007, Zhejiang Textile Industry Research Institute used the co blending method to blend natural cooling oil raw materials, such as eucalyptus leaf oil, mint, camphor, cinnamon oil, etc. with the carrier to prepare the masterbatch with high aromatic concentration, and then co blended the masterbatch with polypropylene chips according to a certain proportion to obtain the cooling oil type aromatic polypropylene fiber. The product can effectively control the release of fragrance, and the half-life of fragrance can be maintained at more than half a year.

1.2 composite spinning method

The composite spinning method usually uses aromatic agent and polymer with relatively low melting point as core layer, and polypropylene or polyester as skin layer to prepare aromatic fiber.

Compared with melt spinning: because of the relatively low spinning temperature of core material, aromatic agents with lower boiling point can be selected than blend melt spinning. The main components of most natural flavors are made up of monoterpenes or diterpenoids. Their boiling point is generally at 150~190 C, which makes the choice of fiber flavor better.

In addition, because the aromatic agent is enveloped in the core layer of the fiber, the fragrance can only be emitted through the fiber cortex by swimming, and the escape rate of the fragrance is controlled. Therefore, the aromatic fiber has the characteristics of long fragrance retention time, and the fragrance can be balanced and sustained with time.

The Teito GS fiber developed by Japanese Tek company is blended with the essence extracted from cypress trees into the core of polyester hollow fiber and made into a composite fabric made of leather core structure. After wearing it, it can make the environment full of natural breath, which is refreshing and pleasant. It is like being placed in the forest, and its fragrance can last for more than three years.

1.3 microcapsule method

The microencapsulation method is usually to wrap natural plant essential oil or synthetic perfume in natural or synthetic polymer membrane to form aromatic fiber with diameter of 1-1000 μ M microcapsules are then adhered to the fiber by means of impregnation or spray with suitable carriers (adhesive), and then fixed on the surface of the fibers by baking and so on.

Due to the sustained-release property of microcapsules, this kind of aromatic fiber has the characteristics of slow fragrance release, which can greatly prolong the fragrance retention time.

Because the microcapsule is only mechanically attached to the surface of the fiber, the microcapsule is easy to break or fall off when the fabric is washed, rubbed and heated, so it also has the characteristics of short fragrance retention life and poor washing resistance.

The microencapsulated aromatic fiber can also be prepared by blending solution spinning method. For example, we prepared the microencapsulated aromatic fiber by enveloping method in the laboratory β- Cyclodextrin is a wall material, jasmine essence is core material, and the ratio of core to core is 10:3. β- The content of cyclodextrin was 15% and the inclusion temperature was 45 ℃; In addition, the feasibility of preparing cellulose aromatic fiber with microcapsule blending solution was discussed under the condition of conventional chemical fiber wet forming. The results show that the microcapsules are well coated and the particle size is 10 ~ 15 μ The size of the fiber sample is 3.19 dtex, and the cross section is irregular round (Fig. 2).

However, due to the complex process and long process of blended spinning, the chemical environment that aromatics have to endure is relatively harsh, a considerable part of aromatics in the spinning solution will enter the coagulation bath during fiber forming, which is difficult to recover, and the aromatics are easy to lose in the subsequent washing, setting, drying and other processes, which increases the production cost. Therefore, there are many difficulties in the preparation of aromatic fibers by this method.

1.4 grafting method

At present, a new method of preparing aromatic fiber, namely, grafting fragrance storage method, has been attached importance to and developed. It is to graft cyclodextrin onto the fiber and make use of the "fragrance" effect of cyclodextrin to make the fiber have the function of continuous inclusion / release fragrance. The so-called "fragrance effect" is to store the fragrance molecules corresponding to cyclodextrin in its cavity. When the fragrance molecules are used, they can be loaded and filled again, so as to maintain the fragrance of the fiber permanently.

The release of flavors stored in cyclodextrins can be achieved by a small amount of moisture, so a gentle breath can make people feel the aroma. When wearing close to the body, the fragrance can be released with the help of normal humidity on the surface of human skin.

Advantages of aromatic fiber made by grafting method: this new type of grafted cyclodextrin aromatic fiber can be filled with fragrance, which greatly improves the fragrance retention time of the fiber, overcomes the shortcomings that the fragrance of other aromatic fibers becomes lighter and lighter with the extension of release time, and can not be reused, and also solves the problem of early release of fragrance, In addition, different aromatic substances can be selected as guest molecules according to personal preference to prepare aromatic fibers with various aroma types.

At present, the inclusion ability of grafted cyclodextrin silk aromatic fiber has been successfully prepared in the laboratory. Cyclodextrin 6-aldehydes were synthesized with o-iodobenzoic acid as oxidant, and then grafted onto silk fibers by reductive ammoniation under weak acid conditions, and used to inclusion aromatic substances. The obtained functional fiber has good inclusion ability, and the aromatic fiber can keep fragrance for a long time.

Cyclodextrins (CD) are composed of more than six glucopyranose units α According to the number of glucose units 6,7,8, 21,4-type cyclic oligosaccharides can be divided into four groups α 2CD、 β 2CD、 γ 2CD et al. Cyclodextrins and their derivatives are characterized by a chiral cavity microenvironment with hydrophilic outside the ring and hydrophobic inside the ring, which can envelop small organic molecules with appropriate size. The inclusion properties of cyclodextrin grafted onto silk fiber can be introduced, and the fiber with aromatic or health care function can be obtained after inclusion with suitable small molecules. However, the research on this aspect has not been reported yet. β 2-cyclodextrin has been widely used because of its easy preparation, low price, and matching cavity size with aromatic groups.

Figure 1 β Chemical structure of 2-cyclodextrin

graft β Synthesis and reaction mechanism of 2-cyclodextrin silk fiber

•    β 2-cyclodextrin MONOALDEHYDE is an important new intermediate compound. Because of its active aldehyde group, it can not only react with hydroxylamine, hydrazine, urea and other ammonia derivatives, but also graft with amino containing macromolecules. The mechanism is reductive amination. The first is nucleophilic addition of aldehyde group, but the addition product is unstable, and then loses 1 molecule of water to form a product with - CHN - structure, but the product is still not stable, and can be hydrolyzed to the original aldehyde under the action of dilute acid; A suitable reducing agent is added to obtain a stable product with - CH2 - NH - structure.

β 2-cyclodextrin MONOALDEHYDE is an important new intermediate compound. Because of its active aldehyde group, it can not only react with hydroxylamine, hydrazine, urea and other ammonia derivatives, but also graft with amino containing macromolecules [7]. The mechanism is reductive amination. The first is nucleophilic addition of aldehyde group, but the addition product is unstable, then loses 1 molecule of water, and forms a product with - CH = n - structure, but the product is still not stable, and can be hydrolyzed to the original aldehyde under the action of dilute acid; A suitable reducing agent was added to obtain a stable product with - CH2 - NH - structure.

The physical and chemical properties of silk mainly depend on the crystalline region and non crystalline region. The crystalline region is mainly composed of glycine, alanine and serine residues with smaller side chains, and its properties are relatively stable; The amorphous region is mainly composed of amino acids with larger side chains except glycine and alanine, such as proline and tyrosine. Due to the existence of amino groups in the functional amino acid side chain of silk, cyclodextrin monoaldehydes and silk fibers can be crosslinked by reductive amination. The reaction route is shown in Fig. 2.

In conclusion, the optimal grafting process is as follows: the mass ratio of cyclodextrin aldehyde to silk fiber is 2 ∶ 1, pH is 6.2, and the reaction time is 7 d. Under the optimum conditions, the grafting rate is 2.24%.

In this experiment, IBX was used as oxidant and could be synthesized under mild conditions β A new type of grafted silk fiber was prepared by reductive ammoniation of 2-cyclodextrin with nacnbh3 as reducing agent β The structure of the fiber was characterized by FTIR, and the inclusion ability of the fiber was investigated by uv-2 vis with phenolphthalein as substrate.

2.1 aromatic household textiles

Aromatic home textile products reflect people's desire for nature and health, which is the future development trend of home textile products. At present, the varieties of aromatic home textile products in the market are more and more diversified, and their functions reflect the diversification of consumer groups

requirement. Bedding, such as reed quilt and rose quilt, has the function of skin beauty and health care; Rush mat with pine resin has the effect of mite prevention and skin beauty; All kinds of curtains, wall hangings, dining mats, cushions, cushions, pillows, etc. have unique effects when combined with aromatic Chinese herbal medicines.

Aromatics can also be used with the color of home textiles, such as purple series or light series representing clove and lavender; Yellow and white represent jasmine and chrysanthemum; Green represents buckwheat skin, mint, etc.

"Kulibi-65" aromatic fiber [9] developed by Mitsubishi Rayon company of Japan has the fragrance of cypress, which can be used as home textile products such as bedding, pillow and mattress; The hollow fiber is mixed with natural fragrance with lavender essence as the main ingredient. The fragrance is pure and has the effect of tranquilizing the mind. It has good promoting effect on sleep. 2. Cross section of aromatic fiber (400 times) under Leica polarizing microscope.

2.2 aromatic healthcare textiles

Aromatic healthcare textile is a kind of functional clothing material developed by applying the research results of aromatherapy to textiles. Aromatherapy is a new kind of treatment method which uses the volatile odor produced by plant essential oil to promote or inhibit the human brain nervous system, thus changing the human psychological and physiological feelings, and achieving the medical purpose.

Research shows that after the fragrance from clothing is absorbed into the body by the respiratory tract mucosa, it can promote the increase of human immune protein, improve human resistance, etc., and it can also design and make health care products suitable for different groups of people according to human acupoints, so as to give better play to the efficacy.

2.3 aromatic clothing

Wearing fragrance is one of the ways for consumers to get happy mood. The fragrant smell from clothing helps to eliminate and alleviate the pressure and panic when people are in a state of tension or frightened. Therefore, fragrant clothing has become a new direction of functional development of clothing.

For example, IKEA clothing company of South Korea has developed a kind of casual clothes and formal dresses with lavender fragrance. When wearing and taking off such clothes or when people are crowded, the fragrance will diffuse, elegant, noble and fashionable.. Associate professor of psychology, University of Philadelphia, USA

Professor John pierce et al is developing a new type of aromatic fiber with odor masking effect [12] and applying it to sportswear, so that athletes can experience the feeling of "fragrant sweat dripping" during sports, which can enhance sports effect and improve sports performance.

To sum up, the development and utilization of aromatic textiles have broad development prospects and market value, no matter from the application level of increasing the functionality and practical value of textiles, or from the perspective of increasing marketing means and improving their economic benefits. In today's "eyeball economy" era, olfactory stimulation is expected to become a new means of sales promotion, which undoubtedly provides new vitality for the wide application and best-selling of aromatic textiles. From the current consumption trend, the single aromatic function of textiles can not meet the market demand. It has gradually become the trend of textile product development in recent years to combine it with antistatic, far infrared, negative ion, flame retardant, anti ultraviolet and other functions.