EP1580307A1 - Biodegradable string - Google Patents

Abstract

The twine is made from 40 - 60 per cent by weight of cotton yarn with a count of 330 dtex and 40 - 60 per cent of vegetable silk yarn of 300 denier, made from fibres obtained from the marsdenia plant (Cionura erecta) originating in the Ukraine. It can also contain one or more other natural, articifial, synthetic or metallic yarns, but is preferably made from two cotton yarns twisted with one of vegetable silk to give a weight of one kilogram of twine per 1000 metres of length.

Description

The present invention relates to a string or cord biodegradable, its preparation process and its use in the in the field of agriculture in general for the maintenance of plants, including plants, shrubs and trees producing fruit or vegetables.

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

These ropes, cords, threads and strings, grouped under the term generic strings in the rest of this presentation, are on time most of them made from plastics, polyester, polyamide and / or polypropylene in particular.

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

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

Thus, so-called biodegradable strings have already been proposed on the market. However, these strings are generally relatively tensile strength, which is a major drawback in their application domain.

Indeed, the strings used in agriculture are very often subject to very high constraints, especially when they are used for trellising, staking, or when serving themselves guardian on which plants grow.

In addition, the stresses applied to said strings become more important when crops begin to load in fruits or vegetables, and reach their maximum just before the harvest.

The proposed biodegradable replacement strings today also have the disadvantage of being often colored dark and therefore absorb a large amount of light necessary for the good growth of plants. This is particularly annoying for greenhouse crops, where the lack of light is a crucial factor, acting directly on crop yield.

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

Another object of the invention is to provide a string biodegradable having a high tensile strength, and in particular sufficient strength to support seedlings of fruit and vegetable crops vegetables.

A third goal is to provide a string biodegradable, with good tensile strength and absorbency that very little light, that is to say, presenting a color essentially white.

Still other objectives may appear in the rest of the present statement.

It has now been discovered that the above objectives are affected in whole or in part by the twine according to the invention which is characterized in particular by the fact that it consists essentially of cotton yarn and vegetable silk thread.

The cotton yarns are obtained from vegetable fiber from the 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.

By biodegradable is meant that the string according to the present The invention may be degraded by the action of physical agents and / or natural chemicals, the degradation products of the said twine not having no character harmful to the environment.

Thus, thanks to its natural components, the string according to the present invention has a very good biodegradability and can be landfill, buried in the ground, composted or even burned, residues of biodegradation or combustion being non-polluting for the environment.

The speed of degradation of the string will of course be according to the thickness of the threads and the number of threads string.

The amount of cotton thread in the string according to the invention is generally between 40% and 60% by weight. The amount of son of vegetable silk in the string according to the invention is generally understood between 40% and 60% by weight.

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 string.

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

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

Apart from the nature of the yarns (cotton and vegetable silk) which are the essential components of the string according to the invention, the structure of said Twine 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 being themselves made of at least one twisted material comprising at least one yarn of cotton 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 consists of at least a twist, generally 3 to 12 twisted, and preferably 3 to 9 twisted, of more preferably 3, 6 or 9 folds, for example 3 or 9 twisted. Each Twists comprise one or more cotton threads and one or more silk threads vegetable. However, it is preferred that each twist includes a silk thread plant for two cotton threads, and in particular, each twine has a vegetable silk thread and two cotton threads.

By way of non-limiting example, the string according to the invention present, in a particularly advantageous embodiment a metric number (Nm) between 0.5 and 2, preferentially understood between 0.8 and 1.2, more preferably of the order of 1. By number Metric means the length of the string (in kilometers) per kilogram of string.

As mentioned above, the twisted pieces consist of threads of cotton and vegetable silk threads. We will preferably use cotton threads having a titer of between 10 and 1000 dtex, preferably between 50 and 500 dtex, more preferably about 330 dtex per wire (i.e., about 300 deniers or a density of about 330/1). Vegetable silk threads as for them a title between 10 and 1000 dtex, of preferably between 50 and 500 dtex, more preferably about 330 dtex per wire (about 300 deniers per wire).

• retors constitués de 2 fils de coton titrant environ 330 dtex et d'un fil de soie végétale titrant environ 330 dtex ;
• torons constitués de 3 retors définis ci-dessus ; et
• ficelle constituée de trois torons, titrant au final de l'ordre de 1000 mètres par kilogramme.

Thus, a string particularly well suited to uses according to the invention has the following characteristics:

• twists made of 2 cotton yarns 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 the order of 1000 meters per kilogram.

The present invention also relates to the method of preparation of the string defined previously. The process uses the techniques known to those skilled in the art of manufacturing ropes, cords, threads and strings.

Thus the method of the invention uses the techniques conventional assembly of fibers and strands, twisting, stranding, etc. Twisting and stranding will be done in Z and / or S, that is to say clockwise (right twist) and / or anti-clockwise (twist left) respectively.

In the case of twisting or successive stranding, it will be however verified that these are performed alternately in Z (or (S) then S (or Z). Two successive strands or twists in S (or Z) which may result in a string that does not have resistance properties, especially to traction, sufficient.

Twisting and stranding are carried out on machines with windings in S or Z, speeds adapted to the types of strands or strands. As a general rule twisting speeds are between 10 and 1000 revolutions per minute, preferably, in the case of the process of the present invention, between 50 and 500 Rotations per minute.

a) préparation de retors à partir de deux fils de coton et d'un fil de soie végétale, retordus à une vitesse de 90 tours par minute en Z ;

b) préparation de torons à partir de 3 retors, définis ci-dessus, retordus à une vitesse de 200 tours par minute en S ; et

c) élaboration de la ficelle proprement dite par toronnage de 3 torons définis ci-dessus à 90 tours par minute en Z.

According to a preferred embodiment of the present invention, the method for preparing the string comprises the steps of:

a) preparation of twists from two cotton yarns and one vegetable silk yarn, 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.

It should be understood that the process described above can be modified and adapted, in particular according to the title of the basic yarns used and / or the desired final title for the string.

In addition, as indicated above, it can possibly be advantageous to include in the above preparation process one or more several other types of natural, artificial or synthetic threads, or one or more metal wires. Also, it may be considered to introduce a soul (central structure) in the string and / or in the strands and / or in the twists.

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

The string according to the present invention, comprising threads vegetable silk and cotton yarn as described above has a remarkable tensile strength, while presenting a high relatively low elongation, of the order of 10% maximum, less than 7%.

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

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

The string according to the invention finds use all particularly interesting for greenhouse crops called "long", that is to say extending over more than one season, in particular for the cultivation of tomatoes.

Indeed, the tomato plants need to be maintained by tutors or, especially in the case of greenhouses, seedlings of tomatoes are staked to the growing ramps by strings. During the appearance of fruits and their enlargement then ripening, these confers on plants, and particularly on tomato plants, a very important weight increase.

The strings usually used to hold the plants tutors or crop ramps should therefore be very good tensile strength. So, for example for crops of tomatoes in greenhouses, the yields are high, ie the number and the size of fruits per plant are high, resulting in a weight of the seedlings maintain on stakes or crop ramps also very high.

The use of hemp strings, which has been widespread in the past, has disappeared, as their tensile strength proved to be insufficient for such cultures. Other biodegradable strings, and for example strings to jute base, cotton and sisal, more resistant, appeared on the market. However, these offer the major disadvantage of not being sufficiently tensile and do not show a color white enough, absorbing too much light necessary for the growth of plants, especially those grown in greenhouses.

Other alternatives to hemp twine also appeared with polypropylene-based strings that have a white color more compatible with good growth Plant. As previously stated, such strings are not biodegradable and are therefore harmful to the environment.

The string according to the present invention is off-white in color and is biodegradable. It also has resistance properties to the traction and properties quite compatible with use as twine for staking the aforementioned cultures, in particular for cultures in greenhouses of climbing plants, eg tomato plants.

The string according to the invention is also perfectly compatible with clips and other fasteners generally used in plant crops, such as tomato plants, cucumbers, aubergines, zucchini, melons, peppers, etc.

Another advantage of the string according to the invention is its flexibility, which makes it particularly easy to use, especially compared to the strings available on the market, in particular those based on polypropylene, which are relatively rigid.

The string according to the invention also has a good resistance to ultraviolet radiation, which makes it particularly adapted to long crops, or winter crops, which extend over durations of 4 to 12 months or more, especially 8 to 12 months.

Finally, because of its excellent biodegradability, the string according to the invention can be composted, incinerated and / or buried in the soil in same time as crop residues. In addition to being safe for the environment, this feature represents a major advantage for the farmer who will find a simple, fast and efficient way to deal with the 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 yarn and yarn vegetable silk. Nature of the constituent threads:

• cotton thread measuring 330 dtex;
• vegetable silk thread (Cionura erecta, origin: Ukraine) grading 300 deniers.

Preparation of the twisted ones:

Twists are prepared by twisting at a speed of 90 rpm, in Z, two cotton threads and a vegetable silk thread.

Preparation of the strands:

The twists prepared previously are twisted, by batch of three twisted, in S, at a speed of 200 rpm.

Elaboration of the string:

The string is obtained by stranding of 3 strands defined above at 90 turns per minute in Z.

Characteristic of the string:

The string 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)

Biodegradable twine, characterized in that it comprises cotton threads and vegetable silk threads. 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 of the total mass of the string. Twine according to claim 1 or claim 2, characterized in that the amount of cotton thread is between 50% and 60% by weight of the total weight of the twine and the amount of silk thread is 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. 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. Twine according to any one of the preceding claims, characterized in that it has a metric number of between 0.5 and 2, preferably between 0.8 and 1.2, more preferably of the order of 1 kilometer per kilogram. . Twine 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 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 comprising at least one cotton thread and at least one vegetable silk thread, preferably a vegetable silk thread for two cotton threads. Twine according to any one of the preceding claims having the following characteristics: twists made of 2 cotton yarns 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 the order of 1000 meters per kilogram. A method of 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 yarn, 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. Use of the string according to any one of claims 1 to 7, in the field of agriculture for trellising, staking and in general the maintenance of plants. Use according to Claim 9 for the cultivation in greenhouses of tomato, cucumber, eggplant, melon or pepper plants.