FR2730507A1 - Composite textured synthetic thread - Google Patents

Abstract

The synthetic thread, esp. a sewing thread, is obtained by an air texturing process of different types of fibres, namely a core fibre (2) and a finish fibre (3) which have different melting points which allow them to be joined together by partial fusion at the lower of the two melting points. The finish fibre is the one with the lower melting point, and the fibres are selected from a group comprising polyamides, polyesters, polypropylenes, aramids, pecks, polyethylenes, viscoses, carbon, glass and metal fibres. After the texturing process the fibres are twisted or braided and subjected to a physical or chemical reaction to give them their final properties.

Description

SYNTHETIC COMPOSITE TEXTURED YARN
The present invention relates to a textured composite synthetic yarn.

It is known that plied synthetic yarns consist of a multitude of monofilaments and which do not have the characteristics of flexibility and suitable contact.

To overcome this drawback, the yarns coming from the spinning mills are generally subjected to a certain number of operations intended to transform their characteristics.

Among these operations, there is the texturing or texturing allowing the synthetic stitching threads to look like natural fibers.

Among the known texturing methods, there may be mentioned: the stuffing box, the edge inflation, the false twist, the fixed false twist and the air texturing.

In the latter method, the monofilaments constituting a thread are introduced into a nozzle into which a stream of compressed air arrives laterally which separates the filaments and distributes them one over the other in a random manner. It is also known to use this method with a central wire or core which is, during the operation, surrounded by a peripheral wire or effect wire. The core thread has a certain diameter and runs through the texturing head at a determined speed while the finer effect thread is fed at a much higher speed. As a result, the effect wire surrounds the core wire by forming loops protruding anarchically.

Such composite threads are used for sewing, especially in the making of clothing.

The object of the present invention is to overcome this drawback and to construct a wire by assembling different materials.

According to the present invention, the air-textured composite synthetic yarn comprising a core and an effect thread surrounding the core is characterized in that the core and the effect thread are of different natures, allowing transformation by subsequent physicochemical reaction, one of the two wires being hot-melt at a temperature below the temperature of the other.

Preferably, it is the effect wire which has the lowest melting point.

Thus, the wire can be assembled by thermocompression on a support, which in particular avoids the use of metal staples or a stitch by a point bonding. It also allows for waterproof seams.

The core can be, for example, made of polyamide, while the effect thread is made of polypropylene.

Other characteristics and advantages of the invention will appear during the following description of a particular embodiment, given only by way of nonlimiting examples, with reference to the drawings which represent:
- Figure 1, a diagram of the air texturing used
according to the present invention
- Figure 2, a sectional view of the wire obtained after
air texturing.

In FIG. 1, it can be seen that a core thread 2 and an effect thread 3 are introduced into a texturing box 1 simultaneously, depending on the nature of these threads 2 and 3, it may be useful to apply before texturing a stretch which in the case of polyester is of the order of 200%. For this purpose, the wires 2 and 3 pass over the input capstans 21, 31 and respectively the output capstans 22, 32, the output capstans rotating at a speed approximately twice that of the input capstans 21, 31 Between the capstans 21, 22, there is provided a reheating oven 4 brought to a temperature of about 2200. The effect thread turns a pin 5 disposed between the capstan 31 and the capstan 32. By this drawing operation, the toughness increases from approximately 30 to 55.

As indicated above, the effect yarn is fed into the texturing box 1 at a speed higher than that of the core yarn 2 to obtain the desired texturing.

The texturing box 1 essentially comprises a nozzle 7 which is supplied with compressed air at a pressure of the order of 9 bars by conduits 6 connected to a pneumatic unit.

At the outlet of the nozzle 7, the textured yarn 23 is obtained which then undergoes a stabilization and fixing treatment by passing over the capstans 8 and in an oven 9 before being recovered on the coil 10. This fixing treatment, in known is intended to avoid the withdrawal of the wire.

According to the invention, the wires 2 and 3 are wires of a different nature with different melting points. These threads can be composed of known fibers such as polyamide 6 whose melting point is at 1880C, the effect thread being, for example, polypropylene whose melting point is of the order of 1300, 1400. D other fibers, such as polyesters and aramid fibers can be retained. Preferably, the melting temperature of the effect wire 3 is lower than the melting temperature of the core wire 2 which thus remains intact when the effect wire undergoes partial melting. Of course, the nature of the hot-melt effect wire is chosen as a function of the support on which said wire must be applied by thermocompression.

The mixture of different materials by air texturing can be used for the manufacture of yarns.

In general, the fibers are chosen from the class grouping polyamides, polyesters, polypropylenes, aramids, pecks, polyethylenes, viscoses, carbon, glass or metallic fibers.

The strands are then optionally shaped by twisting or braiding and a physical or chemical reaction makes it possible to give them their final characteristics. These operations can be avoided by bonding the different ply ends by a partial bond fusion between the fibers.

Example 1
The wire consists of three twisted ends. Each end includes a polyamide 6 core wire of 235 decitex and a polypropylene effect wire of 330 decitex.

It goes without saying that many variants can be made, in particular by substitution of equivalent technical means, without departing from the scope of the invention.

Claims (3)

10 Synthetic composite yarn, in particular sewing yarn,  characterized in that it is obtained by texturing at  the air of fibers of different natures constituting  the core wire (2) and the effect wire (3) respectively  and at different melting points allowing a connection  by partial melting of the melting point fibers on  lower. 20 Wire according to claim 1, characterized in that the  effect yarn (3) has a lower melting point than  core wire (2). 30 Wire according to claim 1, characterized in that the  fibers are chosen from the class grouping  polyamides, polyesters, polypropylenes, aramids,  pecks, polyethylenes, viscoses, carbon fibers,  glass, metallic.