ES2955680T3 - Heat treatment of textile material and apparatus for removing oily impurities from a textile - Google Patents

Abstract

Treatment for textile material, which includes the following stages: feeding quantity of textile material; and repeatedly cooling said amount of material at a low temperature. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Heat treatment of textile material and apparatus for removing oily impurities from a textile

Invention sector

[0001] The present invention relates to a heat treatment for textile material, designed in particular for the removal from the textile material of impurities or oily residues that could remain trapped in the textile material after spinning and weaving procedures and/or due to to the increase in color fastness in the case of colored fabrics.

Previous technique

[0002] In fact, it is known that the textile material production procedure currently in use provides, during the yarn preparation and subsequent weaving stage, the application of lubricating oils on the material to be spun or woven. The application of these substances allows a reduction in friction due to the rubbing of the thread, which allows an increase in processing speed.

[0003] At the end of the weaving procedure, a product is thus obtained that is more or less rich in these oils.

[0004] Before moving on to the next stages of the textile production cycle, dyeing and finishing, it is necessary, both for reasons linked to quality and for environmental reasons, to proceed to the so-called “scrubbing”, that is, a washing procedure of the textile material intended to eliminate these oils.

[0005] The oils present in the raw textile material would in fact cause non-uniform dyeing of the textile material, and the passage to the stretch dryer would lead to the evaporation of the oils, with the consequent production of smoke, contamination and unpleasant odors.

[0006] The washing or cleaning of textile raw material, with continuous feeding or piecemeal, is carried out today mainly in two ways: either by transferring the textile material to tubs filled with a solution composed of water and detergent products (soaps) or by so-called dry cleaning, that is, a procedure that involves the use of perchloroethylene to eliminate oils.

[0007] Both procedures described above involve critical aspects linked to environmental factors.

[0008] In fact, the washing procedure involves the use of large quantities of water and the use of soaps necessary to make the oils soluble, which, once removed from the textile material, are present in the wastewater.

[0009] The dry cleaning procedure is certainly less onerous from the point of view of water consumption, but it introduces the use of a substance, perchloroethylene, which, if not handled properly, can be completely dangerous, both from the environmental point of view as well as from that of health hazards.

[0010] In particular, the treatment of oily impurities present in the textile material itself is one of the main problems related to the fabric processing cycle in the stage commonly called "finishing".

[0011] Impurities can be classified into two categories

- Primary impurities. They are substances that are generated in the fiber and are added to the fiber during the natural phase of formation of the fiber itself. These impurities are present in significant quantities in natural fibers, and their amount is proportional to the nature and origin of the fiber itself. On the other hand, they are absent or present in negligible quantities in artificial and synthetic fibers, with the exception of oligomers present in some types of polyester in quantities of up to 1.5%.

- Secondary impurities. These are substances added to the fiber at various stages of the textile production cycle, such as spinning and weaving, to improve its flow through lubrication and, at the same time, reduce the negative effects resulting from abrasion due to contact with the mechanical elements of the machines. They are present in various types of fibers in quantities that vary from one fiber to another.

[0012] The chemical nature of secondary impurities in turn can be distinguished into two types: - Paraffins. These are aliphatic hydrocarbons and therefore water-insoluble substances, which, however, can be removed from the fiber by emulsion by using surfactants in water baths.

- Spinning oils. These are emulsion products based on mineral oil, to which emulsifiers are added that allow the stability of the emulsion, antistatic products that reduce electrostatic charges and hygroscopic products that provide humidity to reduce the electrostatic effect. The property of spinning oils is that they are emulsifiable in water, in some cases in cold conditions (20° - 25 °C), in others at a temperature of 60° - 80 °C, again in the presence of surfactants , which favor their elimination from the fiber. If the spinning oils present in synthetic fibers, and in particular polyesters and polyamides, are subjected to a thermosetting treatment, they create serious environmental problems. In fact, when these oils are subjected to temperatures above 180 °C, they volatilize, producing considerable quantities of smoke which, if not completely extracted by the reduction system installed in the choke, produces contamination of the working environment. For these reasons, it is currently necessary, before heat setting, to carry out the scrubbing treatment in water or, better yet, a wash in solvent to treat the fiber now free of spinning oils. However, although heat setting confers dimensional stability and mass constancy per unit area in the finished textile material, in addition to reducing the possibility of creasing and streaking in the dyeing process, it also reduces the dyeing affinity and, in part, , the elasticity of the textile material.

- Fabric oils. These are emulsion products with a base of mineral oils and vegetable oils, which exert their specific lubricating action on the movement of the mechanical members of knitting machines. They are declared emulsifiable because their physical state of emulsion lasts throughout the entire storage period of the product; However, very frequently they are not easy to remove by emulsification of the textile substrate on which they are deposited.

[0013] Regarding raw fabrics, primary impurities and, above all, secondary impurities are frequently the cause of dyeing defects, which can occur in the form of oily stains, generally due to fabric oil, which can be colorless. , or assume whitish/opaque, yellowish and even gray/blackish colors, or give the fiber a markedly hydrophobic nature, in the case of spinning oils, since, being fatty substances, they impregnate the fiber, reducing hydrophilicity. and wettability, and create the basis for problematic and uneven distribution of the dye in the fabric and therefore generate a lack of dyeing uniformity. Furthermore, since impurities constitute a surface substrate on the outside of the fiber that absorbs the dye during the dyeing procedure, without proper preparation, they can cause a reduction in color fastness values, that is, resistance to color bleeding. color and rubbing.

[0014] From document US4411051 a procedure for treating a textile material is described, in which to selectively protect the heat-sensitive regions of the textile material bands from damage during heat treatment, said regions are preliminarily subjected to a step cooling so that the thermal rise caused by subsequent heat treatment does not damage heat-sensitive regions.

[0015] From document WO2006046265, a procedure is described for treating a textile article, which includes the steps of cooling the textile article using a cryogenic fluid and subsequently moistening the article with a product at a low condensation temperature in a liquid state and making it The liquid product acts on the fibers of the article. Therefore, the need is felt for a treatment of the textile material that allows the removal of impurities, in particular oily impurities, with a reduced environmental impact and that limits both the water consumption and the energy consumption necessary for the removal. of the impurities themselves. According to a second advantageous aspect of the invention, a method is proposed capable of also increasing the color fastness of textile materials.

[0016] It is known that the color fastness of a textile material is the stability to chromatic variations in tone and intensity, that is, the resistance it manifests with respect to aggressive agents.

[0017] The problem of color fastness has always played a very important role in the field of textile procedures, since it coincides with the definition of the qualitative level of the material. The low color fastness leads to the discoloration of the fabric during the washing of the garment, with the consequent risk of staining of the other garments washed together, or of the garment itself (for example, in the case of a garment made with two different colors, where one is "contaminated" by the other during washing). Another case in which color fastness is a factor of considerable importance concerns clothing for newborn babies. Here the fabric can repeatedly come into contact with saliva, and poor color fastness could cause the dye to pass from the garment into the baby's mouth.

[0018] Color fastness can be tarnished by various agents, each of which acts on the color with different mechanisms, causing different forms of degradation.

[0019] Agents that can weaken the bond between the dye and the fiber can be water, sweat, saliva, light radiation, friction/rubbing, etc. For this reason, there are several types of tests to test various degrees of color fastness, for example:

Light fastness (EN ISO 105-B02);

Color fastness to dry rubbing (EN ISO 105-X12);

Color fastness to wet rubbing (EN ISO 105-X12);

Color fastness to water (EN ISO 105-E01); and

Color fastness to perspiration (EN ISO 105-E04).

[0020] Therefore, color fastness depends on various factors, such as the chemical nature of the dye, the chemical nature of the fiber, the type of bonds between the dye and the fiber and the intensity of the dye. For this reason, depending on the type of result you want to obtain, different types of dyes and many types of materials are used. Higher levels of color fastness imply dyeing procedures that are more laborious and, consequently, more expensive. In general, in order to obtain higher levels of fastness, it is necessary to resort to so-called "reactive" dyes, while, when strict specifications are not established in this regard, "direct" dyes are used. In general, reactive dyeing requires twice the time necessary to carry out direct dyeing, with the consequent doubling of the amount of raw materials and energy required for the procedure (water, heat).

[0021] Therefore, a need is felt for a treatment that allows the production of fabrics with a high degree of color fastness and with a reduced environmental and economic impact compared to current production techniques.

Summary of the invention

[0022] The previous and additional purposes have been achieved with a treatment according to one or more of the attached claims that contemplates the use of low temperatures for the treatment of textile material.

[0023] In several exemplary embodiments, the temperature of the textile material is brought to a value much lower than 0 ° C by means of various cooling systems that can operate with heat transmission by conduction, or convection, or radiation.

[0024] In the first case (conduction), the textile material is brought into contact with a cold substance (temperature well below 0 °C), for example, by immersing it in liquid nitrogen.

[0025] In the second case (convection), the cold substance is injected into a chamber that is cooled (oven). The textile material, when passing through this environment, is cooled by the low-temperature gas mixture.

[0026] In the third case (radiation), heat transmission occurs due to the exposure of the textile material to previously cooled surfaces.

[0027] The reduction in the temperature of the textile material leads, as a consequence, to the state transition of the oil, wax and lubricant particles present in the textile material, which go from a liquid state to a solid state and will be more fragile. the lower its temperature. The same applies to the bonds that are created between these substances and the fiber or fibers used to make up the yarn. For the procedure to be effective, the textile material will have to reach a temperature below -60 °C. The time needed for this to occur obviously depends on different factors, including:

- the mass of the textile material to be treated;

- the specific weight of the textile material;

- the initial temperature of the textile material to be treated; and

- the cooling system used (direct immersion in cryogenic fluid, passage through the cooling tunnel, etc.).

[0028] The particles are then removed from the textile material by exclusively physical operations (agitation, vibrations, ultrasound, suction, etc.) and are recovered when they return to room temperature. A first advantage of the invention lies in the fact that the treatment according to the invention does not use polluting substances and/or substances dangerous to health and the environment.

[0029] An additional advantage lies in the fact that the textile material subjected to the low temperature treatment is cleaned of oily substances and can be used directly for subsequent textile dyeing and finishing operations.

[0030] An additional advantage lies in the fact that the considerable reduction in temperature, followed by the return step to room temperature, strengthens the bond between the dye and the fabric by carrying out the dyeing procedures carried out with direct dyes. at color fastness values comparable to those obtained with reactive dyes. The advantages offered by this procedure are, therefore, greater color fastness, with time savings (to treat 450 m of fabric at a speed of 25 m/min, keeping the fabric submerged for 20 s, 18 min compared to the 300 min difference between dyeing using a reactive procedure and dyeing using a direct procedure), and without the need to use raw materials, such as water, steam and auxiliary textiles, a fact that makes this procedure have an impact extremely reduced in the environment in comparison with the classical procedure used as reference.

List of drawings

[0031] The above and other additional advantages will be better understood by any person skilled in the art from the following description and the accompanying drawings, which are provided by way of non-limiting example and in which:

- Figure 1 shows a diagram of a system for carrying out the treatment of the invention;

- Figure 2 shows a table that exemplifies the results obtained with the treatment of the invention;

- Figure 3 shows a second diagram of a system according to the invention;

- Figure 4 is a table of comparative results on color fastness before and after treatment; - Figures 5 and 6 show, respectively, the result of the dry rub test (EN ISO 105-X12) on a dyed but untreated sample and the result of the dry rub test (EN ISO 105-X12) in a stained and treated sample;

- Figure 7 shows as an example the durations of the cooling stage;

- Figure 8 shows a table of symbols that represent the affinity of the treatment of the invention for different types of textile material; and

- Figure 9 shows a table of symbols that represent the effectiveness and efficiency of the treatment procedure according to the invention as the cooling technology varies.

Detailed description

[0032] With reference to the drawings, there now follows a description of a treatment according to the invention for removing oily impurities from a textile material.

[0033] In the described embodiment, the treatment basically comprises a step of feeding a quantity of textile material, preferably a fabric fed continuously, which is successively subjected to a cooling step at a temperature lower than the solidification temperature of said impurities, preferably lower than -130 ° C, and a step of removing the solidified oily impurities from the fabric.

[0034] Elimination is obtained by means of a physical or physical-mechanical action, for example, by vibration, agitation or suction.

[0035] According to the invention, as represented in Figure 1, the cooling step is carried out by immersing the fabric in liquid nitrogen and subsequently sucking the sublimation fumes.

[0036] The cooling step and/or the solidified impurity removal step are executed repeatedly and in succession.

[0037] Figure 1 schematically illustrates an apparatus suitable for carrying out the treatment according to the invention to remove oily impurities from a fabric, comprising a feed 1 with continuous advance of a fabric 2, which is passed under the filling level of a liquid nitrogen tank 3 established downstream of said feed 1.

[0038] After cooling, the fabric 2 is passed along a suction plate or mat 4, downstream of the tank mentioned above, for the removal of sublimation fumes from the fabric and with them the impurities.

[0039] In the illustrated diagram, the apparatus comprises an array of deflector rollers 5 arranged to cause a repeated immersion of the fabric in the tank 3 and corresponding repeated passes of the fabric against a suction plate or mat. The table in Figure 2 shows the results of the treatments according to the invention carried out on various types of tissue.

Test 1:

[0040]

- cooling stage by immersion in N2;

- elimination stage by treatment with solid CO ₂ jets and subsequent suction.

Test 2:

[0041]

- cooling stage by immersion in N2;

- suction removal stage of sublimation fumes.

Test 3:

[0042]

- cooling stage by passing through a tunnel at a temperature of -100 °C;

- elimination stage by treatment with solid CO ₂ jets and subsequent suction. The stay times in the tank or tunnel in the three tests were as follows:

Test 1: 15 s

[0043]

Test 2: 15 s

Test 3: 15 min

[0044] The suction pressure applied was 60 kPa.

[0045] The tests were carried out in accordance with the UNI 9273:1988 standard to highlight the values of impurities in the fabric before and after treatment.

[0046] The values are given in percentages by weight of the extracted substances.

[0047] The tests carried out made it possible to verify whether the treatment, and in particular the succession of the stages of cooling in liquid nitrogen and suction of the sublimation fumes, manages to significantly reduce the percentage of impurities present in the fabric and achieve the desired advantages.

[0048] With reference to Figures 3-6, a treatment according to the invention to increase the color fastness of a fabric is now described.

[0049] In the described embodiment, the treatment basically comprises a step of feeding a quantity of fabric, preferably a continuously fed fabric, which is subjected to one or more cooling steps at low temperatures, for example, lower than -130 ° c.

[0050] The color, by remaining at this temperature for a few seconds, increases its own bond with the fabric, thus increasing its solidity.

[0051] Figure 3 schematically illustrates an apparatus suitable for carrying out the procedure as described in the present description in order to increase the color fastness of the fabric, the apparatus comprising a feed with continuous advance of a fabric 7, which is passed below the filling level of a tank 9 of liquid nitrogen 10. In the illustrated diagram, the apparatus comprises an array of deflection and drive rollers 8 connected to which there is a chain with pins at which the fabric 7 is fixed. The rollers thus arranged allow the repeated immersion of the fabric in the nitrogen 10, thus allowing the processing speed to be increased.

[0052] The procedure is all the more effective the lower the temperature of the fluid through which the tissue is passed.

[0053] Figure 7 shows the table with the comparison values between the time the fabric remains in the tunnel and the time necessary for immersion. As is clear from the data, due to the different principles of heat transmission, immersion of the fabric in liquid nitrogen at a temperature close to -190 °C allows to obtain processing times shorter than the time of passage through the tunnel cooled to -130 °C.

[0054] The table in Figure 4 shows the results of the color fastness tests carried out on two samples of the same type of fabric subjected to the same dyeing treatment, one of which, however, has been subjected to the treatment. later according to the invention described herein.

[0055] Figures 5 and 6, however, visually present the difference between the two cloths used for the dry rub color fastness test. The fabric in Figure 6 used for the fabric subjected to the treatment according to the invention is much lighter than that in Figure 5 used in the untreated fabric, indicating greater color fastness.

Claims (7)

1. A treatment of a textile material (2) with oily impurities, comprising the following steps: feeding (1) a quantity of textile material (2); and cooling said amount of textile material to a temperature below -130°C; said treatment being characterized because said textile material (2) is a colored fabric and because said cooling step is carried out at a temperature lower than the dissolution temperature of said impurities, and low enough to allow the weakening of the bond between the fiber and the impurities, the treatment comprising the subsequent elimination, by means of physical action, of the solidified impurities of the textile material, and the suction of the sublimation fumes of the textile material, where said cooling step is carried out by repeated immersion of the textile material in liquid nitrogen. 2. The treatment according to claim 1, wherein said feeding step is carried out with continuous feeding of textile material in pieces. 3. The treatment according to claim 2, wherein said cooling step and said suction step are executed repeatedly and in succession. 4. The treatment according to claim 2 or claim 3, wherein said aspiration step is carried out by means of a suction plate or mat brought to the cooled tissue. 5. An apparatus for removing oily impurities from a textile material, comprising: at least one feeding (1) with continuous advance of a textile material (2); at least one tank containing liquid nitrogen (3) downstream of said feed (1) characterized in that said tank containing liquid nitrogen (3) is provided to carry out a cooling treatment at a temperature lower than the solidification temperature of said impurities; and suction means (4), arranged downstream of said tank, to suck the sublimation fumes from the textile material, and means for the elimination by physical action of solidified impurities from textile material. 6. The apparatus according to claim 5, comprising means for repeatedly subjecting said textile material to passage through the tank containing liquid nitrogen and subsequent suction. 7. The apparatus according to claim 5 or claim 6, wherein said suction means comprise at least one suction plate or mat carried to said textile material (2).