At all times, the textile industry was one of the most important sectors of the national economy in our country, as it provided the state with a huge amount of fabric so necessary for it, which was constantly required not only for the production of clothing, but was even used in the manufacture of weapons.
And therefore, almost from the first days of the existence of the USSR, chemists were given the task of obtaining artificial fabrics, since there were sorely lacking natural materials. As a result, acetate fiber was created.
What it is?
In fairness, it should be noted that this is not called a particular type of fabric , but several types of artificial fibers. In all cases, they are made from cellulose acetate. The most common fiber is triacetyl cellulose, as well as ordinary acetate fiber made from recycled cellulose acetate.
Important qualities of artificial fibers
The hygroscopicity of such tissues does not exceed 3.5%. The fiber practically does not absorb moisture, does not swell and does not precipitate even after a multiple soaking / drying cycle. Compared to natural tissues, artificial ones are much less exposed to microorganisms, light and heat. In addition, the mole is completely indifferent to them. These fabrics are able to withstand heat up to 100 degrees Celsius without losing their qualities.
Things made from acetate fibers are very pleasant to look at, they are perfectly erased and dry quickly. In addition, when washing them, it is required to add much less detergents, since dirt is easily washed out of this type of fiber.
Note that weak acids and alkalis do not act on the acetate fiber as destructively as in the case of natural tissues, but as a result, it is saponified and loses most of its useful qualities. Concentrated inorganic acids immediately destroy it.
Microscopic structure of the fiber
If you look at such a tissue under a microscope, you can see hundreds of longitudinal grooves on the surface of the fiber. Because of this, individual threads do not adhere well to each other, and the fabric as a whole is sufficiently elastic and poorly wrinkled. Their luster is similar in appearance to natural silk, and in terms of thickness the individual fibers are quite similar to the thread that the larvae of silkworms give out . If the manufacturer is faced with the task of obtaining a fabric in which the threads are securely adhered to each other, then H-shaped transverse cuts are made on the surface of the fibers.
In addition to increased strength, such a canvas is characterized by a very beautiful sparkling sheen, and therefore it is often used for decoration purposes.
Acetate deficiencies
Unfortunately, not everything is so good: these varieties of artificial materials are very poorly resistant to abrasion, very easily gain static electricity, poorly painted with standard dyes, which are usually used in the textile industry. They should be ironed without raising the temperature of the iron above 115 °, since otherwise thermal deformation is possible.
Other negative qualities
Given the very high ability of acetate fiber to accumulate a static charge, it is quite difficult to produce fabrics from it. If during ironing you go a little too far with the temperature of the iron, then deep defects appear on the surface of the fabric, which can no longer be eliminated. Acetate burns in bright yellow. It is quite easily extinguished, after which it smolders for a long time, releasing a large amount of dense smoke with a specific smell into the surrounding air.
Production
As you can already understand, acetate fiber is obtained from cellulose. Of course, it is preferable to use cotton, but with its shortage or absence, it is quite possible to use high-quality wood. After development and purification, it is treated with acetic anhydride. Sulfuric acid is used as a reaction catalyst, and acetic acid is added to dissolve the resulting cellulose acetate.
In the presence of a small amount of water, the fibers begin to saponify, resulting in diacetyl cellulose. A mixture of acetone and water (95: 1) is added to the resulting substance. Everything, the spinning mixture is ready. It is filtered, cleaning from an excess of coarse mechanical impurities, and then sent to a spinning machine. Obtaining acetate fiber occurs in air (dry method).
This method is also good because it does not require the use of any additional chemicals. A thick and viscous spinning mass is simply forced through a die with many holes, after which it enters the steam-air chamber at a temperature of about 87 degrees Celsius. Since the production of acetate fiber requires a huge amount of water and cellulose, many plants are located near Lake Baikal.
Some color information
High temperature is necessary for acetone to finally evaporate from the mixture. After that, the obtained filaments are cooled, their surface coated with oil to prevent the formation of a static charge, and then wound on a bobbin. Up to 600 meters of thread are formed per minute. In the future, it does not require almost any processing, with the exception of only twisting in the production of thicker fibers.
What is the color? In most cases, the dye is introduced at the production stage, so that the thread of the desired shade is already wound on the bobbin. We have already said that acetate fiber is very poorly dyed by standard means, and therefore, at present, 90% of fabrics are made from threads made from spinning mixtures with specified qualities.
Nowadays, thousands of varieties of special dispersed paints have been created. They allow you to get not just colored fabric, but real masterpieces that have an amazing iridescent color. This impression is created due to the fact that the paint does not stick to the surface of the threads, as is the case with the same viscose fabric, but is part of the fabric itself.
If necessary, white dyes are used, as a result of which fabrics of almost perfect snow-white color are obtained. Since acetate fiber is very resistant to UV rays and very easy to wear, the durability of such a fabric is many times higher than that for cotton or other natural fabrics.
How is molding
Most often, dies having about 200 holes are used in production. If the resulting thread is planned to be twisted into thick fibers or ropes, the mixture is passed through spinnerets with corrugated and crimped walls. If we talk about staple acetate fibers, then their production is practically no different from the process described above.
The peculiarity is that the individual threads leaving the forming device are immediately collected in a bundle, which is immediately cut into pieces of the required length. In addition, staple fibers can be made in the form of ribbons, which are further cut into pieces of the required length.
The main properties of the fibers
What are the main properties of acetate fiber? The thickness of the produced threads in any case is from 11.1 tex X 25 to 16.7 tex X 25 (No. 90/25 - 60/25). When compared with viscose fibers of the same thickness, the strength of acetate filaments is slightly lower (about 10-12%). But! If this fabric gets wet (yes, the same hygroscopicity of 3.5%), then the strength indicators decrease immediately by 40-45!
The tensile strength (tensile elongation) is approximately 27%, but the elastic elongation is much higher than that for the repeatedly mentioned viscose fabrics. It is because of this that “acetates” crumple very poorly, and things from them look perfect for a long time.
Upgraded Option
All of the above may prompt the attentive reader to the idea that this type of fabric has too many shortcomings. This statement is quite true for the recent past, but today in its production modifiers are almost always used, which do not have any chemical effect on the acetate fiber. The formula in this case looks like this: [C6H7O2 (OH) 3-x (OCOCH3) x].
In addition, today increasingly use directed heat treatment of the spinning mass: molecules begin to form more ordered structures. As a result, acetate tissue becomes much stronger, and is not so afraid of strong heating.
Today, Alon fiber, produced by the type of staple web, is characterized by such qualities. It is very strong and elastic, has high durability and a beautiful appearance. Empirically, it was found that a small amount of aluminum pyrophosphate added to the spinning mass, allows you to get acetate fiber, the use of which is possible in any area where there is a danger of fire (curtains for theaters, for example).