In particular, the present invention relates to a yarn of the above-mentioned type suitable for the manufacture of fabrics for clothing, knitwear, furnishings and accessories.

The present invention also relates to a method of preparing a yarn of the above-mentioned type.

It is well known that, in the textile and fashion industry, ever greater and constant efforts are made to find new yarns and fabrics for the production of which fibres of new materials are often tested.

It is also known that glass fibre is highly non- inflammable, generally inert from a chemical point of view, and has good breaking strength and better impact strength than most natural and artificial textile fibres normally used in the textile field.

In spite of the good textile properties mentioned above, glass fibre yarns have the serious disadvantage of having a very poor ability to withstand knotting, that is to say that these yarns cannot be knotted by conventional weaving systems without substantial breakage occurring at the knots.

Moreover, glass fibre also has a limited affinity for dyes, that is, it cannot be dyed substantially by any conventional method used for the dying of yarns of natural, artificial and synthetic fibres such as cotton, viscose, polyester, and acrylic yarns, etc.

In the prior art, attempts have been made to improve the processability characteristics of glass intended for the production of fibres or for other applications by treating the glass with suitable binders such as, for example, cellulose acetate and/or sizing agents.

However, yarns of these glass fibres are not very suitable for the production of fabrics for clothing and their use is in fact limited to the production of glass- reinforced plastics products generally used in building, or of fabrics for technical use.

The technical problem upon which the present invention is based is that of providing a yarn containing glass fibre which can be used for the production of fabrics for clothing, knitwear, furnishings and accessories by conventional weaving processes without having the disadvantages mentioned above with reference to the prior art.

This problem is solved by a yarn comprising a glass- fibre core and a covering of the core constituted by least one filament of a textile fibre.

The at least one filament of textile fibre is preferably wound around the glass-fibre core in the yarn according to the invention.

The winding may, however, be performed by any conventional method known to an expert in the art such as, for example, doubling, twisting and coiling.

It has surprisingly been found that, in the yarn according to the invention, the glass fibre has a good ability to withstand knotting to the extent that the yarn can advantageously be subjected to conventional weaving operations without substantial occurrence of breakages at the knots.

In the yarn according to the invention, the ability of the glass fibre to withstand knotting is increased as the thickness of the yarn increases since the space required to close the loop of the knot is larger, thus avoiding sharp bending of the glass fibre and consequent breakage thereof.

However, this ability to withstand knotting is further increased in proportion to the number of turns of twisting per metre imparted during the winding of the textile fibre on the glass fibre.

In the yarn according to the invention, this number of twists or turns per metre may vary from 10 to 1500 and is preferably within the range of 200-400 turns/metre.

The yarn according to the invention may be produced with any count and the count is preferably within the range of 2000-40000 Nm (Nm = ratio of metres per kilogram = m/kg).

The glass fibre may be of any commercially-available count and glass composition. An E-grade glass fibre having a count of from 34 to 136 tex is preferably used.

The glass-fibre core in the yarn according to the invention is preferably pre-twisted.

A glass fibre classified as EC9-34Z28, that is, an E-grade continuous-filament glass fibre having a filament diameter of 9 microns, a count of 34 tex and a twist equal to 28 turns of Z-twist is particularly preferred.

In the yarn according to the invention, the at least one filament used for covering the glass fibre may be of any commercially-available, natural, artificial, synthetic or mixed textile fibre of any count.

For example, filaments of natural textile fibres such as wool and cotton, of artificial fibres such as viscose, of synthetic fibres such as nylon and polyester, and of mixed fibres such as, for example polyester/linen, viscose/wool, etc., may be used in the yarn according to the invention.

The textile fibres used for covering the glass-fibre core may be already dyed in the colours to be imparted to the yarn or may be used in the raw state, in which case the dying may be performed directly on the yarn on the reel or on the fabric produced from the yarn by dying the fabric in roll or garment form.

In both cases, the yarn according to the invention is advantageously distinguished by being a fancy yarn in which the colour of the textile fibre of the covering, once dyed, is mirrored in the glass fibre, giving rise to a reflecting effect which produces a particular sheen.

According to a preferred embodiment of the invention, the covering of the yarn is constituted by two filaments of a textile fibre twisted with a core of glass fibre with the same direction of twisting.

According to a particularly preferred embodiment of the invention, the covering of the yarn is constituted by two filaments coiled around a glass-fibre core, one of the filaments of textile fibre having an"S"-coil and the other having a"Z"-coil.

Naturally, the order and type of twisting may be varied in dependence on the characteristics to be imparted to the yarn.

The main advantage of the yarn according to the invention is that the glass fibre is in fact introduced into some textile processes which cannot be performed with pure glass filaments, for example, printing, dying, raising of the thread, etc.

The yarn according to the invention can advantageously be processed in many textile processes such as weaving, knitting, dyeing, printing, coating, resin-finishing, etc., and can easily be dyed by conventional dyeing methods.

Moreover, it is of good quality from an aesthetic point of view and is particularly suitable for the production of clothing textiles in accordance with new fashion trends.

The yarn according to the invention can advantageously also be used for the production of fireproof fabrics since glass has good fire resistance.

The fireproof characteristics of textile fibres such as, for example, Trevira CS polyester can thus be improved by the addition of the glass filament in the yarn according to the invention.

The present invention also relates to a method of preparing the above-mentioned yarn, characterized in that at least one filament of a textile fibre is wound around a filament of glass fibre.

In the method according to the invention, the number of twists or turns per metre imparted during the winding may vary from 10 to 1500 and is preferably within the range of 200-400.

According to a preferred embodiment of the invention, the winding is performed by twisting two textile-fibre filaments with one glass-fibre filament with the same direction of twist.

According to a particularly preferred embodiment, the winding is performed by coiling of two textile fibre filaments around the glass fibre, one of the filaments having an"S"-coil and the other a"Z"-coil.

The twisting or coiling may be performed by any conventional apparatus known to an expert in the art for the production of conventional yarns.

In particular, according to the apparatus used, the winding of two or more textile fibre filaments around or with the glass fibre may be performed simultaneously or in several steps.

The characteristics and advantages of the yarn and of the invention will become clear from the following detailed description of an embodiment of the method of the invention and of some examples illustrative of the preparation of yarns according to the invention, the description being given below by way of non-limiting example with reference to the appended drawing.

The drawing shows schematically hollow-spindle twisting apparatus suitable for implementing the method according to the invention.

With reference to the drawing, hollow-spindle twisting apparatus, generally indicated 1, comprises a supply system 2 on which a roll 3 of a glass-fibre filament 4 is mounted.

The glass-fibre filament 4 is unwound continuously from the roll 3 and is introduced by means of the supply system 2 and a pulley 5 into the hole in a first hollow spindle 6.

The filament 4, as well as the final yarn, are kept substantially taut by a wholly conventional yarn-drawing system 7.

Once the filament 4 has emerged from the hollow spindle 6, a first filament 8 of a textile fibre, unwound continuously from a reel 9, is coiled around the filament 4 in conventional manner and with an"S"twist, thus producing a semi-finished product.

This semi-finished product is then introduced into a second hollow spindle 10 and, after it has passed through this spindle, a second filament 11 coming from a reel 12 is coiled around it with a"Z"-twist, thus producing a yarn 13 according to the invention.

As is clear from the drawing, the coiling of the filament 11 is performed in the opposite direction to that of the previous"S"-coil.

After passing through the drawing rollers 7, the yarn 13 is then wound on a reel 14.

In order to satisfy further and contingent requirements, an expert in the art may apply to the above-mentioned method many further modifications and variations all of which, however, are included within the scope of protection defined by the appended claims.

EXAMPLE 1 A yarn was prepared with apparatus of the type described above by coiling two raw (that is, not dyed) nylon filaments both having a count of 44 dtex = 230000 Nm around a glass filament having a count of 34 tex = 29000 Nm.

One of the nylon filaments was coiled with an"S"- coil and the other was coiled with a"Z"-coil; in both cases a twist of. 250 turns/metre was imparted.

The yarn thus produced had a final count of 22,400 Nm and a composition of 77% by weight of glass and 23% of nylon.

The yarn was subjected to conventional weaving operations, during which the glass fibre was shown to have a good ability to withstand knotting since no substantial breakages occurred at the knots.

Finally, the fabric produced with the above- mentioned yarn could easily be dyed in conventional manner.

EXAMPLE 2 A yarn was prepared with the apparatus of Example 1 by coiling of two raw wool filaments, both having a count of 32000 Nm, around a glass filament having a count of 34 tex-29000 Nm.

One of the wool filaments was coiled with an"S"- coil and the other was coiled with a"Z"-coil; in both cases a twist of 250 turns/metre was imparted.

The yarn thus produced had a final count of 10,500 Nm and a composition of 40% by weight of glass and 60% of wool.

The yarn was subjected to conventional weaving operations, during which the glass fibre was shown to have an excellent ability to withstand knotting since no substantial breakages occurred at the knots.

Finally, the fabric produced with the yarn could easily be dyed in conventional manner.

EXAMPLE 3 A fireproof yarn was prepared with the apparatus of Example 1 by coiling of two dyed Trevira CS polyester filaments, both having a count of 167 dtex = 60000 Nm, around a glass filament having a count of 34 tex = 29000 Nm.

One of the Trevira CS polyester filaments was coiled with an"S"-coil and the other was coiled with a"Z"- coil; in both cases a twist of 250 turns/metre was imparted.

The dyed yarn thus produced had a final count of 13,200 Nm and a composition of 49% by weight of glass and 51% by weight of polyester.

The yarn was subjected to conventional weaving operations to produce a fireproof jacquard fabric, during which the glass fibre was shown to have an excellent ability to withstand knotting since no substantial breakages of this fibre occurred at the knots.