BR112019020470B1 - PROCESS OF TREATMENT OF NATURAL FIBERS AND FIBERS OBTAINED FROM IT - Google Patents

Abstract

The invention relates to a process for treating natural fibers that allows conditioning them for the optimal production of yarns and subsequently of textile bases. The process comprises the steps of alkaline treatment, bleaching and addition of softening agent.

Description

FIELD OF THE INVENTION

[001] The present invention fits into the textile sector, particularly in natural fiber treatment processes for different applications.

BACKGROUND OF THE INVENTION

[002] Currently, the leaves of the Aspargaceae family are considered a variety of fibrous plant materials with a high potential for exploitation in the textile industry. Generally, these plant materials have a high cellulose content that can be used in the manufacture of textile bases for clothing. However, its use as a raw material in the construction of textile bases is limited due to its low fiber fineness and roughness, due to the presence of non-cellulosic components, which does not make it suitable for obtaining yarns that can be spun with machinery. traditional for the construction of textile bases.

[003] With the height of the study of new applications of natural bast fibers, the most recent advances have focused on developing cottonization processes, which refer to the processing of bast or hard fibers to make them similar to cotton fibers in terms of its properties (for example, length, smoothness, diameter or fineness). This cottonization is obtained by completely or partially removing the pectins, lignin and hemicellulose without damaging the cellulose of the fiber and by separating the elementary fibers that are joined to each other by these compounds.

[004] The state of the art describes processes for treating natural fibers from the families Poaceae, Urticaceae, Malvaceae, Linaceae, Gramineae, Fabaceae, Cannabaceae, with which fibers with different properties and characteristics are obtained. The processes that are disclosed generally include alkaline treatment, bleaching and drying steps.

[005] Document US7481843 B2 describes a procedure for the extraction and preparation of bast fibers from ramie (Urticaceae family), jute (Malvaceae family) and hemp (Cannabaceae family), with which fibers are obtained for the production of fine spun yarns , pure, in which the conventional spinning train is fed 100% with the selected fiber, or mixtures, in which, before the carding process, different fibers are mixed in the desired proportions and, at the end of the spinning process, a yarn is obtained intimate blend yarn.

[006] Document US5718802 discloses the use of the by-product of sugar cane (Poaceae family) for the production of yarn and nonwovens, in which, for the extraction of fibers, an alkaline treatment with NaOH (caustic soda) and temperature Is it used. Combined mechanical treatments are also used, such as steam explosion, gas bubbles under pressure, strong boiling, among others.

[007] Document US20070199669 discloses a method for the extraction of cellulosic fibers from leaves and stalks of corn, pasture, rice, barley (Poaceae family) sorghum, wheat (Gramineae family), soybean (Fabaceae family) and cotton stalks (Malvaceae family), through an alkaline treatment to partially delignify the material and a subsequent enzymatic treatment to extract the fibers.

[008] Document US 7624478 B2 describes a method for processing bast fibers derived from the cotton stalk (Malvaceae family), which comprises extraction, desizing, preservation, cutting, opening, carding, classification and the packaging. Document US 7526837 B2 discloses a process for treating flax fibers (Linaceae family), which consists of cleaning, cottonizing, macerating and drying the raw material through an electro-hydraulic process.

[009] Document US 4,359,859 B2 describes a yarn formed with the fibers of the leaves and sheaths of corn, by immersing the leaves and sheaths in a caustic soda solution to release them and is subsequently dried, carded and spun . Document CN101041916 (A); describes a process for obtaining a thread from a mixture of bamboo fiber (Poaceae family) and ramie (Urticaceae family).

[010] In the extraction and preparation of fibers of the Aspargaceae family, improper processing can damage fibers to a great extent, generating a low yield of fibers and economic losses. Therefore, there is a need to design procedures for the extraction and preparation of fibers from the Aspargaceae family, which allow obtaining fibers suitable for the construction of high quality textiles for clothing.

[011] The process of the invention allows obtaining natural fibers for new textile bases for the diversification of their applications in clothing, expanding the portfolio of opportunities for these fibers within the textile world.

BRIEF DESCRIPTION OF THE INVENTION

[012] The process of the present invention makes it possible to obtain modified natural fibers from the leaves of plants of the Aspargaceae family, by adding a softening agent to the natural fibers after they have been subjected to an alkaline and bleaching treatment. The fibers obtained exhibit excellent tactile properties due to the removal of non-cellulosic components, favoring a decrease in fiber diameter and an increase in flexibility.

BRIEF DESCRIPTION OF THE FIGURES

[013] FIGURE 1. Photograph of natural fiber (a) and cotton fiber (b).

[014] FIGURE 2. Scanning electron microscope (SEM) images of natural fiber (a) and cotton fiber (b).

[015] FIGURE 3. Photograph of a cotton/cottonized pita mixture yarn (1:1).

[016] FIGURE 4. Photograph of a screen produced with a cotton/cottonized pita mixture thread (1:1).

DETAILED DESCRIPTION OF THE INVENTION

[017] The hard fibers from the leaves of plants of the Aspargaceae family are basically composed of cellulose (between 40% and 70%), hemicellulose, pectins and lignin, responsible for agglutinating and maintaining the integrity of cellulosic fibers. These other non-cellulosic components are responsible for these fibers being coarse, inflexible and with low hygroscopicity. These components must be removed with chemical, mechanical, enzymatic and/or physical cottonizing treatments to obtain softer and more individualized fibers for applications in the textile sector.

[018] Thus, the present invention relates to a process for the treatment of natural fibers from the Aspargaceae family, including pitta, henequem and sisal, whose leaves and stalks are initially shredded and the fibers cut lengthwise into sizes between 10 mm and 1500 mm.

[019] Once the fibers are defibrated and cut, they are subjected to an alkaline treatment that consists of submerging them in an alkaline solution of KOH or NaOH (1% to 20% w/w), with a fiber/alkaline solution ratio between 1:5 and 1:50 at a temperature between 20 and 90 °C for 1 to 24 hours. In one embodiment of the process of the invention, the fibers are submerged in an alkaline solution of NaOH between 10% and 15% (w/v), at a fiber/solution ratio between 1:20 and 1:40, at a temperature between 60 °C and 80 °C, for 1 to 5 hours. In another embodiment of the process of the invention, the fibers are submerged in a 15% (w/v) KOH solution at a temperature of 80 °C for 2 hours.

[020] The fibers obtained are rinsed one or more times with water and subjected to a bleaching phase, which can be carried out by chemical treatment or enzymatic treatment at a temperature between 20 °C and 90 °C, for 0.1 to 168 hours, after which the fibers are again rinsed with water. In one embodiment of the process of the invention, the bleaching step is carried out by chemical treatment at a temperature between 60°C and 90°C, for 0.5 to 3 hours, preferably at a temperature of 80°C, for 2 hours.

[021] For the purposes of the present invention, the chemical treatment of the bleaching stage consists of adding to the fibers a bleaching agent, a strong base, a catalyst and an antifoam. The bleaching agent is selected from chemical compounds such as chlorine in any state, compounds and/or salts derived from chlorine (e.g. sodium hypochlorite), sulphides or sulfuric compounds, oxygen or ozone or compounds that release oxygen such as peroxides, perborates , persulfates or perchlorates, alkali metals, alkaline earth metals, ammonium compounds, and mixtures thereof, in concentrations ranging from 1% to 30% (w/v). In one embodiment of the invention, the bleaching agent is hydrogen peroxide.

[022] The strong base that is added in the bleaching phase can be NaOH or KOH, at concentrations between 0.1 and 5% (w/w); the catalyst is selected from inorganic salts, hydrocarbons, alcohols, organic acids and their derivatives, in concentrations between 0.01% and 1.0%; and the antifoaming agent is selected from silicone or non-silicone emulsions or stearic alcohol or siloxane derivatives, in concentrations from 1.0% to 10.0%. In one embodiment of the process of the invention, the strong base is NaOH, the catalyst is magnesium sulfate, the bleaching agent is hydrogen peroxide, and the defoamer is stearyl alcohol.

[023] Enzymatic bleaching treatment consists of adding one or more enzymes to natural fibers such as: peroxidases, laccases, catalase oxidases, pectinases, cellulases, at concentrations between 1 and 100 g/L, at a temperature between 20 and 60 °C, for a time between 1 and 168 hours. In one embodiment of the invention, the enzymatic treatment is carried out by adding peroxidases and cellulases at a concentration between 0.01% and 5% (v/v) at a temperature between 20 °C and 40 °C, for 1 to 168 hours. In another embodiment of the invention, the enzymatic treatment is carried out by adding peroxidase at a concentration of 0.3 (v/v), temperature of 25°C, for 168 hours.

[024] Once the bleaching phase is completed, a softening agent is added to the fibers, which is selected from cationic, anionic, nonionic, reactive, amphoteric, siliconized or enzymatic emulsions, in order to make the fiber soft and to avoid hornification of the cellulose, which would make the carding process difficult, in which the fiber is opened, separated and purified of dirt and short fibers, in order to be individualized and parallelized to form a veil that will be converted into a belt of card at the end of the process.

[025] The softening agent at a concentration between 0.1% and 10%, preferably between 0.5% and 2.0%, and is added to the fibers at a temperature between 30 °C and 80 °C, with a ratio fiber/solution between 1:5 and 1:50 and for a period of time between 0.5 and 2 hours. In one embodiment of the invention the softening agent is a siliconized nanoemulsion at a concentration of 1.0%, the fiber/solution ratio is 1:40, the temperature is 60 °C, for one hour.

[026] Finally, the fibers can be subjected to a drying step, which can be carried out at room temperature (15 °C to 25 °C) or by convection in an oven at a temperature between 40 °C and 80°C for 0.5 to 36 hours.

[027] The fibers obtained through the process of the invention have characteristics similar to cotton fiber, such as soft touch, white color, greater flexibility and fineness. Because of these characteristics, the fiber can be intimately mixed with other fibers such as cotton, and with all types of artificial and synthetic fibers in the production of fine yarns, which facilitate the production of textile bases that can be used in garments, accessories , tapestry and decoration in general.

[028] The following Examples illustrate the invention without restricting the concept of the invention to them.

Example 1. Treatment of pitta fibers

[029] Pita fibers of a length of 35mm were cut with a guillotine. The fibers were subjected to an alkaline process at 80 °C for 2 hours, using a solution of 666.6 g of potassium hydroxide and 3333.3 ml of water.

[030] Subsequently, the fibers were rinsed and the bleaching phase was carried out, in which 2918 ml of water, 80 g of caustic soda at a concentration of 90%, 2.0 g of magnesium sulfate, 200 g of antifoam (stearyl alcohol) and 800 g of hydrogen peroxide in a concentration of 10% (w/w).

[031] The obtained solution was brought to a temperature of 80 °C, maintained for one hour and subsequently the fibers were rinsed 3 times by overflow. Finally, the fiber was subjected to a smoothing process, for which a solution was prepared with 3920 ml of water and 80 g of a siliconized nanoemulsion. This solution was brought to a temperature of 60 °C to add the fiber and submit it to this process for one hour. The resulting cotton fiber was dried in an oven at 40°C for 24 hours.

Example 2. Treatment of Pitta fibers

[032] Pita fibers of a length of 35mm were cut with a guillotine. The fibers were submitted to an alkaline process at 60 °C for 0.5 hours, using a solution of 222.2 g of potassium hydroxide and 3777.7 ml of water.

[033] Subsequently, the fibers were rinsed and the bleaching phase was carried out, in which 2918 ml of water, 80 g of caustic soda at a concentration of 90%, 2.0 g of magnesium sulfate, 200 g of antifoam (stearyl alcohol) and 800 g of hydrogen peroxide in a concentration of 10% (w/w).

[034] The obtained solution was brought to a temperature of 80 °C, maintained for one hour and subsequently the fibers were rinsed 3 times by overflow. Finally, the fiber was subjected to a smoothing process, for which a solution was prepared with 3920 ml of water and 80 g of a siliconized nanoemulsion. This solution was brought to a temperature of 60 °C to add the fiber and submit it to this process for one hour. The resulting cotton fiber was dried in an oven at 40°C for 24 hours.

Example 3. Treatment of Sisal fibers

[035] Sisal fibers of a length of 35mm were cut with a guillotine. The fibers were subjected to an alkaline process at 80 °C for 2 hours, for which a solution of 666.6 g of potassium hydroxide and 3333.3 ml of water was used.

[036] Subsequently, the fibers were rinsed and the bleaching phase was carried out, in which 2918 ml of water, 80 g of caustic soda at a concentration of 90%, 2.0 g of magnesium sulfate, 200 g of antifoam (stearyl alcohol) and 800 g of hydrogen peroxide in a concentration of 10% (w/w).

[037] The solution obtained was brought to a temperature of 80 °C, maintained for one hour and subsequently the fibers were rinsed 3 times by overflow. Finally, the fiber was subjected to a smoothing process, for which a solution was prepared with 3920 ml of water and 80 g of a siliconized nanoemulsion. This solution was brought to a temperature of 60 °C to add the fiber and submit it to this process for 1 hour. The resulting cotton fiber was dried in an oven at 40°C for 24 hours.

Example 4. Characterization of Pita fiber

[038] The following characterization tests were carried out with the pitta fibers obtained according to Example 1: length, diameter, tensile strength, final lignin content, final cellulose content, final hemicellulose content (Table 1). 1

Example 5. Obtaining yarn from pitta fibers

[039] From the pitta fibers obtained according to Example 1, a yarn spun with a composition of cotton/cotton pitta (1:1) was developed. For the development of this yarn, a cotton of 28 mm with a fineness of 3.6 micronaire was selected. The fibers were mixed in a 50/50 ratio, passed through the opening process in a Shirley opener and carding, in which fixed flat cards were used.

[040] The carding strap was passed three consecutive times through the passer in order to regulate the mass of the strap, which had a weight of 3.3 g/m. The resulting dowel belt was processed on an industrial electro-jet roving frame to obtain a roving of 0.850 g/m. Finally, a yarn was obtained from a cable on a Pinter ring spinning machine with a Z-twist of 520 turns/meter with a Ne 14 count.

Example 6. Obtaining a textile base

[041] From yarn obtained according to Example 5, a textile base was obtained that was produced on a Jacquard loom. The loom, previously woven with cotton-polyester blend yarn and cotton/cottonized pitta yarn (1:1), was inserted into the weft. Flat fabric was produced in plain weave, twill and satin bindings.

Claims (10)

1. Process for treating natural fibers of the Aspargaceae family CHARACTERIZED in that it comprises the following steps: a) treating natural fibers in a strong base solution at a temperature between 25 and 100 °C and for a period of time between 0, 1 and 24 hours; b) subjecting the fibers obtained in step (a) to a bleaching treatment by adding an antifoaming agent, a strong base, a catalyst and a bleaching agent, at a temperature between 20 °C and 100 °C, for a period of time between 0.1 and 24 hours; and c) adding a softening agent to the fibers obtained in step (b); d) wherein the antifoaming agent is a stearic derivative of alcohols or siloxanes; wherein the strong base of step (b) is NaOH or KOH; wherein the catalyst is magnesium sulfate; wherein the bleaching agent is selected from hydrogen peroxide, sodium chlorite, sodium hypochlorite and mixtures thereof; and wherein the softening agent is selected from silicones, silicone emulsions, silicone nanoemulsions, ligninolytic enzymes and mixtures thereof. 2. Process, according to claim 1, CHARACTERIZED by the fact that the natural fibers are selected from sisal, pitta, henequem and abaca. 3. Process, according to claim 1, CHARACTERIZED by the fact that the strong base of step (a) is NaOH or KOH between 1% w/w and 20% w/w. 4. Process, according to claim 1, CHARACTERIZED by the fact that the antifoaming agent is stearic alcohol between 1% w/w and 10% w/w. 5. Process, according to claim 1, CHARACTERIZED by the fact that the strong base of step (b) is in a concentration between 0.1% w/w to 5% w/w. 6. Process, according to claim 1, CHARACTERIZED by the fact that the catalyst of step (b) is in a concentration between 0.1% w/w and 1.0% w/w. 7. Process, according to claim 1, CHARACTERIZED by the fact that the bleaching agent is hydrogen peroxide in a concentration between 1% w/v to 30% w/v. 8. Process, according to claim 1, CHARACTERIZED by the fact that the softening agent of the step are silicone nanoemulsions. 9. Process, according to claim 1, CHARACTERIZED by the fact that it additionally comprises a drying step, carried out at a temperature between 15 °C and 80 °C. 10. Natural fibers of the ASPARGACEAE family obtained by the process as defined in claims 1 to 9, CHARACTERIZED by the fact that they have a length between 20 - 35 mm, a lignin content between 4.2% and 7.6% and a content of hemicellulose between 0% and 13.5%.

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