FR2868087A1 - BIODEGRADABLE TWINE - Google Patents

Abstract

Biodegradable twine comprising cotton yarns and vegetable silk threads.A method of preparing said twine by twisting and using said twine for staking crops.

Description

BIODEGRADABLE TWINE

1] The present invention relates to a biodegradable string or string, its method of preparation, and its use, particularly in the field of agriculture in general for the maintenance of plants, and in particular plants, shrubs and trees producing fruit or vegetables. i0

2] The use of ropes, cords, yarns, strings and others is today widely present in many types of cultures, whether for staking or trellising plants, trees and shrubs, maintaining the parts of these plants, trees and shrubs, especially the branches and branches on which the fruits or vegetables of these crops develop.

3] These cords, cords, threads and strings, grouped under the generic term of strings in the remainder of this presentation, are at the present time, for the most part made of plastics, polyester, polyamide and / or polypropylene in particular.

4] After use, these strings are not usually reused and are thrown away, buried in the ground or burned. In each case, the plastics constituting the string contribute directly, or indirectly by the fumes released during their combustion, to ever increasing environmental pollution.

5] It has therefore been sought new components of strings that are biodegradable, that is to say that can be naturally degraded without producing substantial pollution of the environment.

6] Thus, so-called biodegradable strings have already been proposed on the market. However, these strings are generally relatively resistant to traction, which represents a major drawback in their field of application.

7] Indeed, the strings used in agriculture are very often subjected to very strong constraints, in particular when they are used for the trellising, the staking, or when they themselves serve as guardian on which plants grow.

In addition, the stresses applied to these strings become more and more important, when the crops begin to be loaded with fruits or vegetables, and reach their maximum just before the harvest.

9] The biodegradable replacement strings offered today also have the disadvantage of being often dark in color and therefore absorb a large amount of the light necessary for good plant growth. This is particularly troublesome for greenhouse crops, where lack of light is a crucial factor, directly affecting crop yields.

Thus, a first object of the present invention is to provide a twine having good biodegradability, and whose residues are not harmful to the environment.

It is another object of the invention to provide a biodegradable string having a high tensile strength, and especially sufficient strength to support fruit and vegetable seedlings. s

2] A third objective is to provide a biodegradable string having a good tensile strength and absorbing only a very small amount of light, i.e. having a substantially white color.

3] Still other objectives may appear later in this paper.

4] It has now been discovered that the aforementioned objectives are achieved in whole or in part by the string according to the invention which is characterized in particular by the fact that it consists essentially of cotton threads and vegetable silk threads .

5] Cotton threads are made from vegetable fiber from cotton seed (Gossypium sp.). Vegetable silk threads are obtained from the plant fiber of certain types of plants, for example Cionura erecta (or Marsdenia erecta) of the family Asclepiadaceae, genus Marsdenia.

6] By biodegradable is meant that the string according to the present invention can be degraded under the action of natural physical and / or chemical agents, the degradation products of said string not having any character harmful to the environment.

7] Thus, thanks to its natural components, the twine according to the present invention has a very good biodegradability and can be landfilled, buried in the soil, composted or even burned, the biodegradation residues or combustion being non-polluting to the environment. 'environment.

8] The speed of degradation of the string will of course be a function of the thickness of the threads and the number of threads present in said string.

9] The amount of cotton yarn in the twine according to the invention is generally between 40% and 60% by weight. The amount of vegetable silk thread in the twine according to the invention is generally between 40% and 60% by weight.

0] These proportions may of course vary and are not limited to the above values. However, these values respond particularly well to the compromise tensile strength / cost of the string.

Preferably, the string according to the invention comprises from 50% to 60% by weight of cotton yarn and from 40% to 50% by weight of vegetable silk yarn, more preferably about 55% by weight of yarns. cotton and about 45% by weight of vegetable silk thread.

2] Without being a preferred embodiment of the present invention, the string may contain, in addition to the cotton threads and the vegetable silk threads, one or more other son, advantageously natural, such as linen, hemp, wool, silk, etc., but also artificial, such as celluloses or cellulose esters, or synthetic, for example based on polyester, polyamide, polyethylene, polypropylene, polyacrylic, modacrylic, chlorofibres, elastane, fluorofibre, or the aramids, as well as the fiberglass, carbon or ceramic or wire, and mixtures of the aforementioned son.

3] Apart from the nature of the yarns (cotton and vegetable silk) which are the essential constituents of the twine according to the invention, the structure of said string may be of any type known to those skilled in the art. For example, the twine according to the invention is formed of two or more strands, said strands themselves being composed of at least one ply comprising at least one cotton thread and at least one vegetable silk thread, in the proportions by weight indicated above.

Advantageously, the string according to the invention comprises 2, 3 or 4 strands, preferably 3 strands. Each of the strands is made up of at least one twist, generally from 3 to 12 twisted, and preferably 3 to 9 twisted, more preferably 3, 6 or 9 twisted, for example 3 or 9 twisted. Each twist consists of one or more cotton threads and one or more vegetable silk threads. It is preferred, however, that each plied yarn comprises one vegetable yarn for two cotton yarns, and in particular, each yarn comprises one vegetable yarn and two cotton yarns.

  1s [0025] By way of non-limiting example, the string according to the invention has, in a particularly advantageous embodiment a metric number (Nm) between 0.5 and 2, preferably between 0.8 and 1, 2, more preferably of the order of 1. By metric number means the length of the string (in kilometers) per kilogram of string.

As noted above, the twists are made of cotton yarn and vegetable silk yarn. Cotton yarns having a title of between 10 and 1000 dtex, preferably between 50 and 500 dtex, more preferably about 330 dtex per yarn (ie about 300 denier, or about 330/1). The vegetable silk yarns will have a title of between 10 and 1000 dtex, preferably between 50 and 500 dtex, more preferably about 330 dtex per yarn (about 300 denier per yarn).

7] Thus, a twine particularly well suited to the uses according to the invention has the following characteristics: twists consisting of 2 cotton threads measuring about 330 dtex and a vegetable silk thread measuring about 330 dtex; strands consisting of 3 plies defined above; and string consisting of three strands, finally titrating on the order of 1000 5 meters per kilogram.

The present invention also relates to the twine preparation method defined above. The process uses the techniques known to those skilled in the art of making strings, cords, wires and strings.

Thus, the process of the invention makes use of conventional techniques for assembling fibers and strands, twisting, stranding, etc. The twisting and stranding will be made in Z and / or S, that is to say in the clockwise direction (right twist) and / or anti-clockwise (left twist) respectively.

0] In the case of twisting or successive stranding, it will however be verified that these are performed alternately Z (or (S) and S (or Z) .Two strings or twists successive S (or Z) may result in a string that does not possess resistance properties, particularly to traction, which are sufficient.

1] The twisting and stranding are performed in a conventional manner on machines allowing windings S or Z, at speeds adapted to the types of strands or strands. As a rule, the twisting speeds are between 10 and 1000 rpm, preferably in the case of the process of the present invention, between 50 and 500 rpm.

According to a preferred embodiment of the present invention, the twine preparation method comprises the steps of: a) preparing twists from two cotton yarns and one vegetable silk thread, twisted at a speed 90 revolutions per minute in Z; b) preparation of strands from 3 plies, defined above, twisted at a speed of 200 revolutions per minute at S; and c) elaboration of the string itself by stranding of 3 strands defined above at 90 rpm Z. [0033] It should be understood that the method described above can be modified and adapted, in particular according to the title of the base yarns used and / or the desired final title for the string.

4] In addition, as indicated above, it may be advantageous to include, in the above preparation method, one or more other types of natural son, artificial or synthetic, or one or more son son. Also, it may be envisaged to introduce a core (central structure) in the string and / or in the strands and / or in the plies.

5] This soul may be a simple thread or an association of one or more threads, themselves possibly twisted or stranded. Thus, in order to further improve the tensile strength, while preserving a satisfactory degree of biodegradability, it may be envisaged to introduce a core consisting of a metal wire at the time of stranding of the three strands as defined above .

6] The twine according to the present invention, comprising vegetable silk threads and cotton threads as described above has a remarkable tensile strength, while having a relatively low elongation rate, of the order of 10% at the end. maximum, or even less than 7%.

7] These remarkable properties, combined with the intrinsic biodegradability of the string, and its off-white color, contribute to a particularly interesting use of the twine in the field of agriculture, horticulture, vegetable crops, fruits and vegetables. vegetables, whether outdoors or under shelter, eg in greenhouses.

8] Thus, another object of the present invention is the use of the twine previously described for trellising, staking, and in general the maintenance of plants.

9] The string according to the invention finds a particularly interesting use for so-called "long" greenhouse crops, that is to say extending over more than one season, in particular for tomato growing.

0] Indeed, the tomato plants need to be maintained by stakes or, especially in the case of greenhouse crops, the tomato plants are staked to the cultivation ramps by strings. When the fruits appear and when they grow and ripen, they give the plants, and especially the tomato plant, a very important weight gain.

1] The strings usually used to keep the seedlings on the stakes or the crop ramps must therefore offer very good tensile strength. Thus, for example for greenhouse tomato crops, the yields are high, that is to say that the number and size of fruits per plant are high, resulting in a weight of the plants to be maintained on stakes or crop ramps also very high.

2] The use of hemp strings, which has been widely used in the past, has disappeared, as their tensile strength has proven insufficient for such crops. Other biodegradable strings, such as jute, cotton and sisal strings, have been introduced to the market. These, however, have the major disadvantage of not being sufficiently resistant to traction and do not have a sufficiently white color, thus absorbing too much of the light necessary for the growth of plants, including those grown in greenhouses.

3] Other alternatives to hemp twine have also appeared with polypropylene strings, which are white in color more compatible with good plant growth. As previously stated, such strings are not biodegradable and are therefore harmful to the environment.

4] The string according to the present invention is off-white in color and is biodegradable. It also has tensile properties and properties quite compatible with use as twine staking said crops, especially for greenhouse crops climbing plants, for example tomato plants.

5] The string according to the invention is also perfectly compatible with the clips and other fixing means generally used in plant cultures, such as, for example, tomato, cucumber, aubergine, zucchini and melon plants, peppers, etc. Another advantage of the twine according to the invention is its great flexibility, which makes it particularly easy to use, particularly with respect to the strings available on the market, in particular those based on polypropylene, which are relatively rigid. .

7] The string according to the invention also has good resistance to ultraviolet radiation, which makes it particularly suitable for long crops, or winter crops, which extend over periods of 4 to 12 months or more, more particularly from 8 to 12 months.

Finally, because of its excellent biodegradability, the twine according to the invention can be composted, incinerated and / or buried in the soil at the same time as the crop residues. In addition to being safe for the environment, this feature is a major benefit for the farmer who will find a simple, fast and effective way to treat string residues after use.

  The following example illustrates the invention without limiting it in any way.

EXAMPLE

  Preparation of a biodegradable string made of cotton threads and vegetable silk threads.

  Nature of the constituent yarns: - cotton yarn measuring 330 dtex; - vegetable silk thread (Cionura erecta, origin: Ukraine) grading 20,300 deniers.

  Preparation of the Twists: Twists are prepared by twisting at a speed of 90 revolutions per minute, Z, two cotton threads and a vegetable silk thread.

  Preparation of the strands: The twists prepared previously are twisted, in a batch of three twists, at S, at a speed of 200 revolutions per minute.

  Elaboration of the twine: The twine is obtained by stranding of 3 strands defined above at 90 revolutions per minute in Z. Feature of the twine: The twine obtained is very flexible and has a natural off-white color.

  Metric number: 1000 meters per kilogram.

Maximum stretch: 10%.

  Distributed tensile strength: greater than 40 kg.

Claims (10)

  1. Biodegradable twine, characterized in that it comprises cotton threads and vegetable silk threads.   2. Twine according to claim 1, characterized in that the amount of cotton thread is between 40% and 60% by weight of the total weight of the twine and the amount of silk thread is between 40% and 60% by weight. weight of the total mass of the string.   3. Twine according to claim 1 or claim 2, characterized in that the amount of cotton yarn is between 50% and 60% by weight of ls the total weight of the twine and the amount of silk thread represents between 40% and 50% by weight of the total weight of the string, preferably about 55% by weight of cotton yarn and about 45% by weight of vegetable silk yarn.   4. Twine according to any one of the preceding claims, characterized in that it further comprises one or more other natural, artificial, synthetic or metallic yarns.   5. Twine according to any one of the preceding claims, characterized in that it has a metric number between 0.5 and 2, preferably between 0.8 and 1.2, more preferably of the order of 1 kilometer. per kilogram.   6. String according to any one of the preceding claims, characterized in that it comprises two or more strands, in particular 2, 3 or 4 strands, each consisting of at least one twist, generally 3 to 12 twisted, and preferably 3 to 9 twisted, more preferably 3, 6 or 9 twisted, for example 3 or 9 twisted, each twist comprising at least one cotton thread and at least one vegetable silk thread, preferably a vegetable silk thread for two cotton threads.   7. Twine according to any one of the preceding claims having the following characteristics: Twists made of 2 cotton threads measuring about 330 dtex and a vegetable silk thread measuring about 330 dtex; Strands consisting of 3 twisted fibers as defined above; and string made up of three strands, finally titrating on the order of 1000 lo meters per kilogram.   8. Process for preparing the string according to any one of   Claims 1 to 7, comprising the steps of:   a) preparation of twists from two cotton yarns and one vegetable silk thread, twisted at a speed of 90 revolutions per minute in Z; b) preparation of strands from 3 plies, defined above, twisted at a speed of 200 revolutions per minute at S; and c) elaboration of the string itself by stranding of 3 strands defined above at 90 revolutions per minute in Z. 9. Use of the twine according to any one of claims 1 to 7, in the field of agriculture for trellising, staking and in general the maintenance of plants.   10. The use according to claim 9, for the greenhouse cultivation of tomato, cucumber, aubergine, melon or pepper plants.