WO1995033089A1

WO1995033089A1 - Interwoven polyester yarn for weaving without sizing

Info

Publication number: WO1995033089A1
Application number: PCT/FR1995/000662
Authority: WO
Inventors: Norbert Chabod; Chritian Fombert; Eric Maitre; Thierry Poizat
Original assignee: Rhone-Poulenc Setila
Priority date: 1994-05-27
Filing date: 1995-05-19
Publication date: 1995-12-07
Also published as: FR2720413B1; FR2720413A1

Abstract

Polyester yarn for weaving without twisting or sizing and method for the manufacture of such a yarn. The invention also concerns, in particular, a multifilament yarn comprising polyester, characterized by a cohesion factor (CF) greater than or equal to 15 knots/meter, a knot quality such that the cohesion factor is at least equal to 4 knots/meter upon testing at a tension of 50g, and a dynamic thread/metal friction coefficient less than or equal to 1.35, combined with a friction coefficient regularity corresponding to a regularity factor defined below, which is less than or equal to 0.35 and a rate of size deposition on the yarn of at least 0.4 % combined with a regularity of the rate of deposition on the yarn corresponding to a regularity factor, defined below, which is less than or equal to 0,20 %. The yarn is used, in particular, as the warp yarn on weaving machines.

Description

INTERLACE POLYESTER YARN FOR NON-SIZING WEAVING

The present application relates to a polyester yarn usable in particular for the manufacture of weaving chains and capable of being woven without sizing or twisting, in particular on a water jet loom. It also relates to a process for manufacturing this wire.

When using chains, mainly in weaving, it is known that the threads rub on the one hand against each other due to the movement of raising and lowering of the blades, and on the other hand against elements of the trade such as the eyelets of the heddles in which they pass, teeth of the comb, leaf, unwinder, chain breaker, etc. In order to prevent friction from causing defects prejudicial to the very operation of weaving and to the quality of the fabric produced, a preliminary treatment called sizing is carried out on threads. This well-known treatment by its application on yarns of fibers to ensure the cohesion of the fibers and to form a protective sheath of the yarn, is also applied to continuous artificial and synthetic multifilament yarns; the sizing must ensure the retention and protection of the filaments, generally of fine, therefore fragile titles, and surround the continuous threads with a sheath avoiding the friction described above and thereby facilitate sliding both on the looms and between threads, in order to produce fabrics with no appearance defect, and to avoid breakages and scuffs as much as possible. These sizing products are generally removed after weaving by treating the fabric.

To ensure the cohesion of the wire, a twisting operation is generally carried out on it. However, this twisting operation is increasingly being replaced by a pneumatic process of interlacing the filaments. Thus, depending on the pressure of the fluid and the interleaving means, the number of cohesion points can be varied, that is to say the number of points at which the filaments form a knot, depending on the final appearance. desired for the wire and its subsequent use.

To facilitate the sliding of fibers and threads, oils or sizing agents are commonly applied. With regard to artificial and synthetic continuous yarns, these oils or sizes are applied to the yarn one or more times during its production process.

In order to save the costs of the operations of gluing and desizing and thus eliminating two operations of handling the threads, attempts have been made to eliminate the operation of sizing, which is moreover harmful to the environment, by playing on the level. intertwining the wires. Thus, the Japanese application published under the number 289113/90 describes untwisted fibers based on polyesters, woven without sizing having an interlacing factor or cohesion factor (Fc) greater than or equal to 20 knots / meter and a factor d 'interlacing greater than or equal to 5 knots / meter after stretching under tension of 50 g. But the only factor of cohesion (FC) and the solidity of the knots under stress is not enough to obtain polyester threads capable of being woven without sizing in good conditions.

The present invention relates to a woven polyester yarn without sizing or twisting on industrial looms, working at speeds of at least 700 or 800 strokes / min. or even more.

More particularly, it relates to a multifilament yarn, based on polyester, characterized by a cohesion factor (CF) greater than or equal to 15 knots / meter, a quality of the knots such that the cohesion factor is at least equal to 4 knots / meter according to the test carried out under a tension of 50 g, and a dynamic friction coefficient wire / metal less than or equal to 1.35 associated with a regularity of the friction coefficient, represented by a regularity factor, defined below, less than or equal at 0.35 and a size deposition rate on wire of at least 0.4% associated with a regularity of the deposition rate on the wire represented by a regularity factor, defined below, less than or equal to 0 , 20%.

Preferably the cohesion factor (FC) is greater than or equal to 20 knots / meter, the frictional coefficient wire / metal is less than or equal to 1, 1. Preferably also the rate of deposition of sizing on wire is between 0 , 8 and 1.2% and the factor representing the regularity of the deposit rate is preferably less than or equal to 0.18%.

According to a characteristic of the invention, the sizing composition comprises at least one lubricating oil and at least one compound which increases the tackiness of the sizing composition. In addition, and advantageously, the sizing composition can comprise another compound which improves the abrasion resistance of the sized yarn. Preferably, this improvement in abrasion resistance is provided by the tackifying compound.

Thus, the size used in the invention makes the surface of the filaments tacky, making it possible to improve the cohesion of the filaments between them. For ease of language, the size used in the invention will be called cohesive size, and the tackifying component, a cohesive additive.

The lubricating oils suitable for the invention are all the oils conventionally used in the field of spinning synthetic polymers and more particularly polyesters. The cohesive additives suitable for the invention must advantageously be dispersible emulsifiable or soluble in water, and obviously have a natural tack. In addition, these cohesive additives must not, after deposition on the filaments or the yarn, cause an increase in the coefficient of friction beyond the value described above.

As examples of cohesive additives suitable for the invention, mention may be made of certain polymers such as polymethacrylates, certain polyesters, low molecular weight polyisobutenes or nonionic amine compounds. This list is given only as an example.

According to a preferred characteristic of the invention, the size comprises between 5 and 40% by weight of cohesive additives.

It can also comprise other compounds than the lubricating oil and the cohesive additive such as surfactants, antistatic agents which are usually used in sizing compositions.

According to another characteristic of the invention, the yarn comprises a deposition rate "of total sizing of at least 0.4 g per 100 g of yarn, preferably between 0.5 and 1.5 g, advantageously between 0, 8 and 1.2g.

According to a characteristic of the invention, this deposition rate is advantageously regular over the length of the thread to promote the passage of the thread over the looms. The regularity of the sizing rate is represented by the standard deviation between the measurements of the sizing rate of yarn samples representing a determined length of yarn or a determined yarn weight. This sizing ratio is measured by extracting the sizing agent deposited on the wire with ether and weighing the residue after evaporation of the solvent. This standard deviation, called the deposit regularity factor, is at most equal to 0.20%.

According to the invention, the threads have a cohesion factor (FC), advantageously at least 15 knots per meter of thread, preferably at least 20 knots per meter. This high cohesion factor reduces the risk of breakage of the strands and scuffing on the looms.

The cohesion factor or FC (knots / m) represents a number of cohesion points contained in one meter of yarn.

The number of nodes can be determined mechanically on an Rothschild NPT type R2040 automatic device. This detects the distance between the interlacing points using a needle which penetrates between the filaments of the moving wire, and which retracts as soon as it encounters a point of resistance, i.e. -to say a voltage higher than the imposed threshold voltage. Title (dtex) Threshold voltage = 0.2 g / dtex +.

Number of strands

The average distance (D) between the determined interlacing points (average of

100 measures) to which the advance of the thread at the interlacing node (a) is added, allows the mean cohesion factor of the thread to be calculated.

1000

FC = D + a

Generally the advance of the wire to the knot (a) is equal to 6 mm.

According to another characteristic of the invention, the polyester yarn of the invention has good quality knots, that is to say after application of a tension on the yarn, only part of the knots is destroyed. This solidity of the knots is determined by measuring the cohesion factor of the wire after having been subjected to a tension of 50 g according to the test described below:

The wire is drawn under a pre-set tension of 50 g and the cohesion factor is measured again. The tensile strength of the knots can be represented by the ratio of the cohesion factors before and after the measurement, expressed as a percentage or by the minimum value of the cohesion factor after application of the tension on the wire.

According to the invention the cohesion factor after application of a tension of 50g on the wire must be at least equal to 4 knots per meter after tension. Advantageously, the ratio between the cohesion factor of the wire and the cohesion factor before drawing is greater than 30%.

Indeed, even if the number of knots is sufficient, and the quality of the knots is insufficient, for example if the strength of the knots in traction is insufficient, the threads will not have the property of being able to be woven without gluing in acceptable conditions.

In general, the good quality of the interleaving points also implies that all the strands are caught in the nodes.

According to the invention, the wire / metal friction coefficient is less than or equal to 1.35, preferably less than or equal to 1.1. This characteristic makes it possible to assess the quality of the size and its distribution on the thread and is representative of the ability of the thread to rub on the mechanical members without deteriorating, in this case the mechanical members of the looms. Its measurement is made on a device marketed under the trade name F. METER by

Rothschild. The moving wire, at a speed of 60 m / min, rubs at an angle of

120 ° on an obstacle (steel finger). The thread tensions recorded before and after the friction make it possible to calculate the coefficient of friction μ of the thread: 1 T ₂

with T _j = input voltage ^{~ *} 2 ^≈ output voltage of contact angle on the finger.

According to the invention, the friction coefficient μ must be regular over the length of the wire. This regularity is characterized by the standard deviation between the measurements of the friction coefficient μ over the length of the wire (approximately 3000 measurements are carried out on 180 meters of wire).

According to another characteristic of the invention, the threads advantageously have an abrasion resistance represented by the Flex Abrasion Index (LFA) greater than 40,000 cycles. This index is measured with a KNICKSCHEUERGERAT device from the company HOECHST. The measurements are carried out with a wire forming an angle of 10 °.

According to the present invention, the term "polyester yarn" means multifilament yarns based on polyalkylene glycol terephthalate, preferably ethylene or butylene glycol or their copolymers containing polyalkylene glycol terephthalate units and units obtained by replacing terephthalic acid with a other diacid such as isophthalic acid, hexahydroterephthalic acid, dibenzoic etc. ... or by replacing ethylene glycol with another diol such as butanediol or hexanediol etc. ...

The present invention also relates to a process for obtaining multifilament yarns based on woven polyester without sizing which consists in carrying out after extrusion a double deposit of size on the yarn or filaments and in subjecting the filaments to at least one interlacing , the first sizing deposit being made before the interleaving step, the thread then being returned, after the second sizing deposit, at a speed advantageously of at least 3000 m / min.

According to a characteristic of the method of the invention, the first sizing deposit can be carried out with a composition not containing a cohesive additive. However, in a preferred embodiment, this size comprises a cohesive additive, advantageously at a concentration of less than 40% by weight. The sizing composition can be an oil or an aqueous emulsion. The second sizing deposit can be carried out with a sizing composition comprising a cohesive additive without lubricating oil or, preferably, as a mixture with a lubricating oil. Advantageously, the weight concentration of cohesive additive is between 10 and 40%. This size can be used in the form of an oil or an aqueous emulsion.

The size used for the 1st deposit may be different from that used for the second deposit. Thus, the lubricating oils, the cohesive additives can be different or identical in the two sizing compositions.

Advantageously, the concentration of cohesive additive in the sizing composition used during the second deposition is higher than that of the composition used during the first deposition.

The deposition of the two sizes can be carried out according to the usual techniques such as for example deposition by rolls or using gudulettes.

The wire or filaments can be stretched. Thus, the wire can be stretched along the spinning path according to any known method, at the desired rate according to the orientation and the mechanical characteristics which it is desired to confer on it. It can also be simply preoriented or oriented to spinning according to the final winding speed. It can be obtained directly or taken up on rollers to regulate the winding tension, if this proves useful or necessary.

The winding speed is generally greater than 3000 m / min. and preferably between 3000 and 6000 m / min. and the wire can be stretched before the first interlacing.

The threads produced by the process of the invention can be used, for example as warp threads on industrial weaving looms. The warp threads have titles of 30 to 150 dtex, more generally from 50 to 80 dtex.

In industrial weaving circles, a thread is considered suitable for weaving on a given loom if its use requires a rate of intervention on the loom per hour (IMH) of less than 0.5, at the usual weaving speeds, ie ie about 700 to 800 rounds per minute.

In certain cases, for example when the thread is intended to be woven on looms causing warp threads to have high stresses, it may be preferable to polish the threads with any product usually used before weaving is carried out. The warp yarns obtained from the yarns according to the invention can be used easily either in direct warping or in sectional warping without requiring gluing and can be woven on all types of loom, in particular on looms. high speed used industrially.

The invention will be illustrated by the examples below, given for information only.

Examples 1 to 6

A polyethylene terephthalate of intrinsic viscosity 190 Pa.s (measured at 25 ° C. on a 1% solution in orthochlorophenol) is spun at 285 ° C. through a die comprising 76 orifices with a diameter of 0.3 mm and cooled by an air current at room temperature. The filaments, after having been gathered in the form of threads, are taken up on a conventional drawing bench and then passes through a suitable interlacing device such as a pneumatic interlacing nozzle.

The wires are returned on a reel at a speed of the order of 3000m / min. Before passing over the drawing bench, the filaments or threads are sized by depositing a first sizing composition (El).

A second deposition of a second sizing composition (El) is carried out on the interlaced thread (s) before winding on the spool.

The deposits of the sizes are carried out by the usual techniques, to know deposit by rollers or gudulettes. The definition of the size compositions E1 and E2 is indicated in Table I below:

TABLE I

The El sizing compositions are used in the form of an emulsion in water with a weight concentration of 14%. The compositions E2 are used in the form of an oil, without the addition of water. The percentages indicated in italics represent the concentration by weight of the compound concerned in the lubricating oil / cohesive additive mixture.

. The yarns thus treated have the following properties collated in Table II

TABLE π

These examples show the influence of the various parameters on the ability of the threads to be woven with a suitable LMH. Thus, the threads of tests 2, 4 and 5 which have either a too high deposition regularity factor or a high frictional coefficient, can be woven only with a high intervention rate on the loom making their industrial exploitation impossible.

Claims

1. Multifilamentary yarn based on woven polyester without twisting or sizing, characterized in that it has a cohesion factor (CF) greater than or equal to 15 knots / meter, and a cohesion factor after application of a tension of 50 g greater than 4 knots / meter, a dynamic frictional coefficient for wire / metal less than or equal to 1.35 a regularity factor for the frictional coefficient less than or equal to 0.35 and a total deposition rate for size on wire between 0.4g and 1.5g per 100g of wire associated with a regularity factor of the deposit rate of less than 0.20%.

2. Wire according to claim 1, characterized in that it has a cohesion factor (FC) greater than or equal to 20.

3. Wire according to claim 1 or 2, characterized in that the size deposition rate on wire is between 0.8 and 1.2 g per 100 g of wire.

4. Wire according to one of the preceding claims, characterized in that the size comprises at least one lubricating oil and at least one cohesive additive.

5. A wire according to claim 4, characterized in that the rate of cohesive additive in the size is between 5 and 40% by weight.

6. Wire according to one of the preceding claims, characterized in that it has a Flex Abrasion Index (IF A) greater than 40,000 cycles

7. Yarn according to one of the preceding claims, characterized in that the cohesive additive is chosen from the group comprising compounds having a natural tack and of the polymethacrylate, polyesters, low molecular weight polyisobutenes type or nonionic amine type compounds

8. Method for obtaining a multifilament yarn according to one of the preceding claims, characterized in that, after extrusion, the yarn undergoes a double deposit of size and at least one interlacing, the first deposit being made before the interleaving, the second deposit being made before the wire is wound up.

9. Method according to claim 8, characterized in that the second deposition is carried out with a sizing composition containing a cohesive additive.

10. Method according to claim 9, characterized in that the sizing composition used during the second deposition contains a lubricating oil.

11. Method according to one of claims 8 to 10, characterized in that the first deposition is carried out with a sizing composition comprising a lubricating oil.

12. Method according to one of claims 8 to 10, characterized in that the first deposition is carried out with a sizing composition comprising a lubricating oil and a cohesive additive.

13. Method according to one of claims 8 to 12, characterized in that the concentration of cohesive additive in the sizing composition used during the second deposition is greater than that of the composition used during the first deposition.

14. Method according to one of claims 8 to 13, characterized in that the first deposit and / or the second deposit are made with a sizing composition in the form of an aqueous emulsion.

15. Method according to one of claims 8 to 14, characterized in that the first deposit and / or the second deposit are made with a sizing composition in the form of an oil.

16. Method according to one of claims 8 to 15, characterized in that the wire or filaments are drawn before interlacing.

17. Method according to one of claims 8 to 16, characterized in that the winding speed is greater than 3000m min.

18. Use of the threads according to one of claims 1 to 7, in weaving looms, characterized in that they are not free of sizing.