This article is developed from four aspects: the basics of fabric shrinkage (definition, principle, common…
100% Cotton fabrics are neither environmentally friendly nor healthy, the use of chemicals is not less than other fabrics, this article will be through the production and manufacturing process of the pure cotton fabric, rational discussion, which will overturn your inherent knowledge of cotton clothes.
Some sellers often recommend pure cotton fabrics on the grounds of natural, comfortable and healthy, however, in the eyes of textile chemical engineers, there is a different picture: 100% cotton fabrics with far more chemical reagents than chemical fabrics, now follow this article to understand what pure cotton clothes have undergone chemical treatment it.
Table of Contents
In the textile factories, when cotton fibers are spun into yarns for weaving, the yarns tend to break due to the very high speed, which requires sizing the yarns to improve the mechanical properties. Most of these sizing materials are polyvinyl alcohol and acrylic sizing, of which polyvinyl alcohol, is also the main component of our commonly used solid glue.
The yarn sizing is good for textile weaving, but not good for dyeing later because the sizing will penetrate into the tissue dye. I believe we all don’t want to have all kinds of unsightly dye spots on our clothes. Therefore, in the printing and dyeing factory, it is necessary to boil with a penetrating agent and caustic soda to desizing.
Refining and bleaching to remove impurities
In addition, although cotton is naturally grown, but not pure, cotton will be attached to a variety of impurities, such as pectin, wax, cotton seed shells, inorganic salts, dust, pigments, nitrogenous substances. Such impurities, if not removed, worn on the body will not only yellow, there will be a bright black spot of cotton seed shell, so it is necessary to refine and bleach the cotton fabric, which will use penetrant, caustic soda, hydrogen peroxide, sodium silicate, sodium sulfite and so on.
Dyeing after bleaching, the main component of cotton is cellulose, so there are azoic dyes, direct dyes, reactive dyes, and vat dyes of four types for dyeing. Among them, azoic dyes and direct dyes are the lowest end, not only the dyeing is not strong, and the dye itself will decompose 24 kinds of carcinogenic aromatic amines, which have now been banned. Because they are particularly easy to handle, they are often featured in children’s tie-dye craft classes.
The most commonly used dyeing is reactive dyes, which requires the use of sodium carbonate, dispersant, and a large amount of sodium sulfate. Due to the defect of the dyeing mechanism, reactive dyes will definitely lead to 30% of dyes will be hydrolyzed to form floating colors, these floating colors can not be closely combined with the clothes, and will fade. For example, some friends have passed puberty, but the back will still grow acne, it is likely to be caused by this floating color formation of color deposits blocking the pores.
Soap wash to remove floating color
In order to remove these floating colors, it is necessary to soap with surfactants and dispersant-type substances, which can also wash off some of the bad things on the clothes. The soaping process to use a lot of water, more than the dyeing water several times, which is the reason for the high pollution in the printing and dyeing industry. As the cost of soaping the sewage treatment costs or very high, some small workshops just wash a bit, or even not wash, then to the hands of consumers is easy to fade clothes.
In addition, there is a kind of vat dyes, which has very good dyeing quality, such as soldiers’ uniforms and high-quality shirts and home textiles, most of which are this kind of dye. After dyeing, not only the color is bright, but also can keep lasting without fading, but in its dyeing process to use caustic soda, sodium carbonate, even sodium dithionite, formaldehyde water, sodium hyposulfite and hydrogen peroxide, etc., dyeing will produce hydrogen sulfide, sulfur dioxide gas, toxicity and pollution are not small, the smell is particularly unpleasant.
Q: It should be okay to buy white clothes that are not dyed, right?
Some people will feel that I buy non-dyed white clothes should be fine, however, this is not the case. White fabric will be dyed with the fluorescent whitening agent, white cotton fabric is divided into this white and whitening. After bleaching, this white cloth directly does clothes, and the whitening cloth will use a fluorescent whitening agent, so that it becomes more white and bright. Because most consumers do not understand, sellers do not necessarily understand and do not necessarily say, so this looks more beautiful whitening cloth is the most popular in the market.
The difference between this white cloth and whitened cloth is like the difference between napkin and A4 paper, although they are both white, they are not the same whiteness. After observation through the Color Matching Cabinet TU 300, it was found that the cloth that was just bleached would have a cotton light yellow color, while the whitened cloth is bright white.
If your clothes are white than the napkin, it must use a fluorescent whitening agent, if possible, use a UV light to distinguish whitening cloth.
Add color fixing agent to fix the color
After dyeing, in order to better improve the quality, or to cover up the poor quality dyes used during the dyeing process, we need to use the color fixing agent. A color fixing agent is like the glue that holds the dye firmly to the garment. The low-end color fixing agent, there is dicyandiamide and formaldehyde condensation resin, slightly better is polyacetamide, or diallylammonium hydrochloric acid polymer, etc.
Many friends buy clothes will have a bad smell, some even very pungent, if you can return, return the clothes, do not wear, because 90% of the possibility is the use of poor quality color fixing agent, resulting in a serious formaldehyde overload, remember that the new clothes must be washed in water before wearing.
Do you think this is the end? Of course not, the cotton fabric made at this time is rough, not soft at all, so you need to add a softener. 90% of the textiles will add softener, because the effect of enhancing the softness of the fabric is too obvious, simply do not need to choose very good fiber raw materials, you can get a great feel.
Hold the clothes with your fingers, rubbing hard for 5 seconds, and then touch your fingers, if there is a sticky feeling, it must have added softener. Add softener is a very conventional production operation, but poor quality softener will have an emulsifier, which is called APEO. It is a kind of biological hormone, chemical structure and human estrogen is very similar to hepatotoxicity and reproductive toxicity. APEO is low priced, good emulsification effect, often appears in the hang tags is no garbage clothes.
For most of the softener, there is basically no soft effect after 5 washes, then in order to improve the softness of the washability to add binder, which involves the problem of formaldehyde again. So buying clothes, just determining the quality of the fabric is good or bad by the feel, is simply useless.
If you want, adding softener can make the rotten rag softer than the towel for washing your face. So, is there any cotton fabric here without any chemical treatment? Of course is the cotton gray cloth, that rough texture, people definitely do not want to wear close to the body. On the contrary, everyone hates chemical fabrics, because they are synthetic, so they are purer.
Chemical fabrics can also be obtained by deformation textured yarn method, both the comfortable performance of cotton, and do not need extra chemical reagents to remove impurities, only wash away the oil agent during spinning. In addition, the dispersed dyes during dyeing can be fully utilized, and the color fastness will be better, while more impurities will be washed away subsequently using reduction washing and other methods.
For example, sportswear or outdoor clothing is more demanding in terms of comfort and conditions of use, and almost no cotton products are used. Pure cotton fabrics absorb moisture but are not breathable, so athletes will almost never wear pure cotton fabric clothing in sports.
High-end home textile products, but also gradually use a class of Lyocell chemical fiber, which is more skin-friendly and comfortable than cotton, so we must learn to look at natural fibers and chemical fibers with a rational eye.
Finally, I would like to say that there is no good or bad fabric, only suitable or unsuitable for its use. For example, natural and chemical fibers blended with each other can make up for each other’s shortcomings and better improve comfort. This is the TESTEX blog, follow me, it will bring you more professional and healthier textile knowledge.