FR2873720A1 - PROCESS FOR TREATING SANDY COTTON - Google Patents

Abstract

The present invention relates to a method of treating sticky cotton to reduce the tackiness of the cotton fibers thus treated. The method comprises the following steps: a. inoculating said cotton fibers with bacteria by spraying, preferably uniform, an aqueous suspension of said bacteria, so as to obtain a maximum resultant moisture of 16%; b. storing the cotton fibers thus treated in the form of a compressed bale; let the bacteria seeded at room temperature especially for at least about a week.

Description

PROCESS FOR TREATING SANDY COTTON

  The present invention relates to a method of treating sticky cotton to reduce the tackiness of the treated cotton fibers. More particularly, the invention relates to a treatment of sticky cotton using bacteria.

  Cotton is one of the most used raw materials of the textile industry. World production of cotton fiber is estimated at about 20 million tonnes per year. About 20% of the cotton produced, representing approximately 4 million tonnes per year, is contaminated with sugars, forming what is known as sticky cotton. Cotton fibers can be polluted by honeydew insects, which are succulents secreted in particular by two polyphagous homopterous insects, an aphid (Aphis gossypii) and a whitefly (Bemisia tabacs).

  Sticky cotton causes significant problems during different stages of production and processing of cotton fiber in the textile industry. The bonding of cotton has a detrimental effect on the process of preparation and spinning. Indeed, the presence of honeydew hampers the smooth running of the preparation machines: opener, carding, ... can lead to a mechanical blocking thereof with the need to perform a complete cleaning. Similarly, the bonding from the sugars of honeydew causes windings of cotton fibers at the level of the drawing members (straps, cylinders, ...) both at the stage of the pin bench and the continuous spinning, resulting in breaks of strands or yarns and a deterioration in the quality of the yarn obtained (increase in the number of pimples and other irregularities).

  Many solutions have been proposed to reduce the stickiness of cotton.

  In industrialized countries, especially in the United States, cotton producers are trying to control the potential source of stickiness by treating cotton crops with pesticides. This solution is only partially satisfactory: the results obtained depend on the number of treatments carried out, the date of the last pre-harvest treatment, the difficulty of reaching the insects, located on the underside of the foliage. In addition, this solution seriously harms the environment.

  Another approach is to address the problem of stickiness by processing post-harvest cotton fiber. Numerous methods of treatment are known in this sense: heat treatment of cotton fibers, by the document EP 196449; mechanical treatment of cotton fibers, by US 5153968; thermomechanical treatment of cotton fibers, in EP 344631; electromagnetic treatment of cotton fibers, EP 350669; enzymatic treatment of cotton fibers, by the document EP 622487.

  The document EP 622487 describes an enzymatic treatment of sticky cotton by a composition comprising at least one enzyme selected from the group: transglucosidase, pectinase, α-galactosidase, these enzymes being derived from the Aspergillus fungus. The treatment method intended to reduce the tackiness of the cotton consists in applying the said enzymatic composition to the cotton fibers before (by spraying a solution of said enzymes) and / or after harvesting (by dipping in a bath containing a 4% solution of said enzymes).

  Such a treatment of sticky cotton fibers, especially in its post-harvest variant, seems difficult to apply to industrial quantities of cotton. In addition, the spraying of enzymes before harvesting must necessarily be accompanied by a sustained irrigation of the cotton fields, because these enzymes need water to act on their substrates (carbohydrates present on the cotton fibers). Finally, the high cost of the enzymes used by this method of treating sticky cotton does not allow to consider widespread use.

  The present invention proposes to overcome the disadvantages due to the known sticky cotton treatment methods.

  The purpose of the present invention is to propose a biotechnological method of treatment aimed at reducing the stickiness of cotton; this method is simple, inexpensive, has no negative impact on the environment and can be used to treat large quantities of post-harvest cotton on an industrial scale.

  According to a first aspect, the invention relates to a method of treating a batch of sticky cotton fibers intended to reduce the stickiness of said fibers, characterized in that it comprises the following steps: a. inoculating said cotton fibers with bacteria by spraying, preferably uniform, an aqueous suspension of said bacteria, so as to obtain a maximum resultant moisture of 16%; b. storing the thus treated cotton fibers as a compressed bale; c. let the bacteria seeded at room temperature especially for at least about a week.

  By resulting humidity is meant the rate of recovery in natural water of the cotton bale (about 8%) plus the percentage of moisture actually delivered (that is to say taking into account water losses during spray treatment) by the treatment of cotton fibers according to the invention.

  The storage conditions, in terms of duration and storage, are determined to obtain the desired result, namely the degradation of the sugars conferring the stickiness of the cotton. This result is obtained in one week for storage at room temperature, between 15 and 20 C, but it can be in a longer time or possibly shorter depending on local climatic conditions.

  In a preferred embodiment, the resulting moisture inside the bale treated according to the process of the invention is between 8 and 13%. The aqueous bacterial suspension comprises at least 106 colony forming units of bacteria per ml of water. The concentration of bacteria seeded inside said ball is at least 105 colony forming units per gram of treated cotton.

  The aqueous suspension used in the sticky cotton treatment process comprises bacteria selected from: Lactobacillus, Pediococcus, Bifidobacterium, Lactococcus, Leuconostoc, Enterococcus and Streptococcus. Characteristically, these bacteria are able to metabolize the sugars present in particular in insect honeydew on the cotton fibers to be treated. According to one embodiment of the invention, the aqueous suspension comprises bacteria selected from the group: Lactobacillus plantarum and Lactobacillus casei rhamnosus. Preferably, said aqueous suspension comprises bacteria selected from Lactobacillus casei rhamnosus R0011 and Lactobacillus p / antarum R1012 strains.

  According to a second aspect, the invention relates to a freeze-dried powder containing the abovementioned bacteria, which powder is sufficient to dissolve in water in order to obtain the suspension to be sprayed.

  According to a third aspect, the invention relates to a sachet containing a determined amount x of said lyophilized powder used for seeding a quantity y of sticky cotton.

  The invention will now be described in detail.

  The present application relates to a sticky cotton treatment process which aims at reducing the tackiness of cotton fibers, and thereby optimizing the processability of the thus treated cotton fibers. Processability of cotton is understood to mean the ability of cotton fibers to undergo ginning, carding, spinning, dyeing, weaving operations, to obtain quality yarns / fibers / cotton fabrics.

  The process for treating sticky cotton according to the invention is applied to the cotton harvested, either during the ginning operation even before baling, or subsequently (for example at the spinning stage), with, in this case the need to open the bales of cotton previously pressed.

  The process for treating sticky cotton fibers, intended to reduce the stickiness of said fibers, comprises the following steps: a. inoculating the cotton fibers with bacteria by spraying, preferably uniformly, an aqueous suspension of said bacteria, so as to obtain a maximum moisture content of 16%; b. storing the cotton fibers in the form of a compressed bale; c. let the bacteria seeded at room temperature especially for at least about a week.

  In one embodiment, the treatment method according to the invention applies to balls that have undergone the pressing operation. In this case, the ball to be treated containing sticky cotton is first opened by means of a bale breaker, to form thin layers of fibers. In another variant embodiment, the treatment method is applied to cotton bales just before they are pressed, this solution being particularly advantageous for production areas affected by the phenomenon of sticking.

  An aqueous suspension of bacteria is seeded on the sticky cotton fibers of said ball by spraying, preferably uniform. Spraying can be done manually or by means of a suitable spray installation.

  Preliminary tests carried out by the applicants have shown that certain bacteria, in particular those selected from the group Lactobacillus, Pediococcus, Bifidobacterium, Lactococcus, Leuconostoc, Enterococcus and Streptococcus, are capable of metabolizing the carbohydrates present on the sticky cotton fibers, carbohydrates. carbon including the natural physiological sugars of cotton (glucose, fructose, sucrose) and insect honeydew. The main sugars contained in honeydew are trehalulose, melezitose, sucrose, fructose and glucose.

  The seeded seed as described is then closed and compressed. If appropriate, the plastic or cotton wrap of the treated bale is sealed, so as to create an environment isolated from external conditions, in order to keep a constant humidity inside said bale. The bacteria are allowed to act at room temperature for at least a week.

  The higher the humidity inside the bale, the greater the metabolic activity of the seeded bacteria, and the faster the stickiness of the cotton fibers thus treated. The resulting humidity inside the seeded bale should not exceed 16%, however, to prevent mold growth. It has been found that, in the case of cotton dried before the treatment according to the invention, the activity of the seeded bacteria is decreased.

  In a preferred embodiment, the resulting moisture within the bale is less than 13%, preferably 8 to 11%.

  The bacterial treatment of the sticky cotton fibers according to the invention does not affect the degree of polymerization of the cellulose used in the constitution of the cotton fiber.

  The invention will be better understood on reading the following nonlimiting exemplary embodiments.

  EXAMPLE 1 Digestion of carbohydrates present on sticky cotton fibers by bacteria Twenty-four strains of bacteria from the Lallemand collection were subjected to a test for the use of sugars according to the API50CHL method (BIOMERIEUX). This test makes it possible to highlight the capacity of a given strain to use the various sugars and polysaccharides. The strains tested belong to the genera Lactobacillus, Pediococcus, Bifidobacterium, Lactococcus, Leuconostoc, Enterococcus and Streptococcus.

  Among the strains tested, only those using at least two of the following sugars: sucrose, trehalose and melezitose, ie nine strains, were subjected to a growth test in an MRS culture medium, where glucose had been replaced either by sucrose. either by trehalose or by melezitosis. The growth rate on these media was estimated by measuring the turbidity or optical density as a function of time for 24 hours of incubation at 30 C. The two strains having presented the best growth under these conditions: Lactobacil / us casei rhamnosus R0011 and Lactobacil / us p / antarum R1012, were selected for the application tests on cotton fibers.

  These two strains were deposited with the CNCM (National Collection of Microroganisms Cultures) under the following numbers: Lactobacillus case / rhamnosus R0011: CNCM I-1720; - Lactobacillus plantarum R1012: CNCM MA-18/50.

  In a known manner, these bacteria are not pathogenic.

  Example 2. Application of the sticky cotton fiber treatment method at laboratory scale 50 g microballs were used to study the effect of bacterial treatment on sticky cotton. These microballs have the same density as standard sized bales.

  Preliminary tests were intended to determine, as a first step, the best way of seeding and moistening micro-balls. Two seeding methods were tested: - the injection of water inside the microballs. The result is unsatisfactory because of the high density of the cotton fibers inside a micro-ball, which makes the penetration of the needles very difficult and prevents the injected liquid from dispersing uniformly within the micro-balls. micro-balls; spraying the water on the cotton fibers; in this variant, the micro-ball is opened, a solution is sprayed uniformly on the fibers, then the micro-ball is closed and kept at room temperature.

  The effect of bacteria belonging to the species Lactobacillus plantarum and Lactobacillus casei rhamnosus on the stickiness of the cotton was tested on 50 g cotton bales, as described above. The higher the humidity inside the bale, the greater the metabolic activity of the seeded bacteria, and the faster the stickiness of the cotton fibers thus treated. It has been found that, in the case of cotton dried before the treatment according to the invention, the activity of the seeded bacteria is decreased.

  Preferably, the resulting humidity inside the microballoon must be between 8 and 13%.

  The bacterial treatment of the sticky cotton fibers according to the invention does not affect the degree of polymerization of the cellulose used in the constitution of the cotton fiber.

  The best efficiency was obtained by using a suspension of Lactobacillus plantarum at 2.5 x 106 colony-forming units per 9 grams of cotton, for a resulting humidity of 16% at 21 C for one week. The results were validated by a conventional test of adhesiveness of the treated cotton.

  Example 3. Application of the sticky cotton fiber treatment process at the scale of a pilot station A pilot test was then carried out, consisting of treating cotton fibers with a high degree of stickiness with bacteria of the genus Lactobaci / / us plantarum at a concentration of 4 x 106 colony-forming units per gram of treated cotton, the resulting moisture inside the bale being between 9.5 and 12%. The cotton fibers thus treated were then subjected to a conventional spinning operation using a spindle bench and a ring spinning machine or a rotor spinning operation using the principle of centrifugal force (open end machine). The results obtained were positive, showing the total disappearance of the tackiness of the cotton thus treated. The quality of the son thus obtained is not affected by the treatment.

  Additional tests have shown that an added humidity of 5% does not lead to the appearance of mold even after one month of incubation at room temperature, which leads to the conclusion that it is not necessary to stop the growth. microorganisms by subsequent treatment.

  Example 4. Process for the Industrial Treatment of Sticky Cotton Fibers Industrial scale processing trials of sticky cotton used 6 bales of cotton having 3 levels of gluing as follows: weak gluing: balls S6 and S7; ii. medium gluing: balls S8 and S9; iii. high bonding: balls S1 and S5.

  The two bales with close bonding levels were mixed before the treatment, the total weight thus obtained for each level of bonding being then divided into two parts in order to perform spinning tests without and with bacterial treatment.

  Three of the six thus obtained were seeded by spraying a suspension of microorganisms into the water. The suspension was prepared from a lyophilized powder containing lactic acid bacteria, including bacteria belonging to the genera Lactobacillus plantarum and Lactobacillus casei rhamnosus. The said lyophilized powder is packaged in bags of a fixed weight, for example 100 g sachets. In each 100 g sachet is a necessary and sufficient dose of bacteria to seed 200 kg of cotton. The contents of a sachet are dissolved in water (100 g of freeze-dried powder for 2 liters of clean water); the powder-water mixture is well stirred. This step is followed by a dilution step in water, at room temperature, of the first suspension obtained; the volume of water added in this dilution step is a function of the weight of sticky cotton to be treated and the desired humidity. For example, to obtain a humidity brought by 10% inside a 200 kg bale, the suspension (2 liters) is diluted in 20 liters of water. The diluted suspension thus obtained must be sprayed on the cotton fibers to be treated in a sufficiently short time to avoid any decrease in bacterial activity.

  The bales were then closed and weighed to accurately determine the amount of water actually added to the fibers.

  The balls are then stored for one week at room temperature.

  After checking, the added moisture was respectively: 11% for S1 + S5; 7.2% for S6 + S7; 8% for S8 + S9.

  2873720 11 A comparison between the qualitative results (measured with Uster equipment) corresponding to the wires (NE 30/1) obtained from different bales is shown in Table 1.

  The results below show that the treatment of the sticky cotton fibers according to the invention does not cause degradation of the quality of the yarn.

  USTER S1 S5 S1 S5 S6 S7 S6 S7 S8 S9 S8 S9 with without with without without treatment treatment treatment treatment treatment treatment combed combed carded carded carded carded CV 13.38 13.42 16.31 16.45 15. 82 14.71 mass (%) End 2 4 16 14 10 7 Thick 136 124 406 406 303 174 Neps 370 395 808 792 567 450 Rendering 5.87 5.74 6.73 6.54 6.48 6.29 Toughness 14.94 14.15 13.14 12.76 13.50 14.12 (cN / Tex) Elongation 4.35 4. 57 3.99 3.70 4.03 3.99 (%)

Table 1

  A rapid test for the sugar content of the cotton fibers belonging to said balls (according to the Parkins method) was also carried out (Table 2).

  These results confirm the positive effect of the treatment on the amount of sugar contained in the sticky cotton.

  Sample Negative Positive Sample Content Comments N in sugars (%) 1 S1-S5 with treatment V <0.35 No sugar 2 S1-S5 without treatment V> 0.35 Sugar 3 S6-S7 with treatment V <0.35 No sugar 4 S6-S7 without treatment V> 0.35 Sugars S8-S9 with treatment V <0.35 No sugar 6 S8-S9 without treatment V> 0.35 Sugars 2873720 13

Claims (9)

  1. A method of treating sticky cotton fibers intended to reduce the stickiness of said fibers, characterized in that it comprises the following steps: a. inoculating said cotton fibers with bacteria by spraying, preferably uniform, an aqueous suspension of said bacteria, so as to obtain a maximum resultant moisture of 16%; b. storing the cotton fibers thus treated in the form of a compressed bale; c. let the bacteria seeded at room temperature especially for at least about a week.   2. Method according to claim 1 characterized in that the compressed treated bale is wrapped tightly.   3. Treatment process according to one of claims 1 and 2, characterized in that the resulting moisture of the treated cotton bale is at most 13%.   4. Method according to any one of claims 1 to 3, characterized in that the concentration of bacteria seeded inside said ball is at least 105 colony forming units per gram of cotton.   5. Method according to any one of claims 1 to 4, characterized in that said aqueous suspension comprises bacteria selected from: Lactobacillus, Pediococcus, Bifidobacterium, Lactococcus, Leuconostoc, Enterococcus and Streptococcus.   6. Method according to claim 5, characterized in that the aqueous suspension comprises bacteria belonging to the group: Lactobacillus plantarum and Lactobacillus casei rhamnosus.   7. Method according to claim 6, characterized in that the aqueous suspension comprises bacteria belonging to strains selected from Lactobacillus casei rhamnosus R0011 and Lactobacillus plantarum R1012.   8. Freeze-dried powder containing bacteria selected from: Lactobacillus, Pediococcus, Bifidobacterium, Lactococcus, Leuconostoc, Enterococcus and Streptococcus, used in the process according to one of Claims 5 to 7.   9. Sachet containing a determined amount x of powder according to claim 8 for seeding a quantity y of sticky cotton.