FR2791708A1 - PROCESS FOR PRODUCING FABRICS BASED ON SYNTHETIC FIBERS, ESPECIALLY POLYAMIDES, WITH A SURFACE EFFECT OBTAINED BY CALENDERING - Google Patents

Abstract

This process is characterized in that: - the calendering operation is carried out on a fabric (3) having received a pre-treatment making it suitable for dyeing and consisting of degreasing and heat-setting by passing through a ream; - during the calendering operation, the counter-cylinder (2) is superficially preheated to bring it to a temperature of the order of 130degreC, the temperature of the steel cylinder (1) being set at a level greater than 1 'of the order of 5 to 10% relative to a normal calendering temperature which, for polyamide, is traditionally of the order of 190 ° C; - The calendered fabric is cooled immediately after leaving the calender before being wound up to then be subjected to a conventional dyeing treatment, full bath, without pressure and at a temperature of the order of 100 ° C; - after dyeing, the treated fabric receives a conventional finishing treatment (drying / finishing) on a ream.

Description

1 2791708 PROCESS FOR THE PRODUCTION OF FIBER-BASED FABRICS

  SYNTHETICS, ESPECIALLY POLYAMIDES, HAVING A SURFACE EFFECT OBTAINED BY CALENDERING.

  Technical Field The present invention relates to an improvement made to the operations of finishing textile fabrics, more particularly based on synthetic threads, with a view to modifying their surface state to communicate to them either a lacquered appearance, or relief effects and intaglio. 10

  It relates more particularly to a treatment carried out by calendering.

  PRIOR ART It has been known for a very long time to subject fabrics or knits, generally made of synthetic fibers, to a calendering treatment in order to modify their surface appearance and / or give them relief patterns. In general, the installations used to produce such articles essentially consist, as is apparent in particular from FR-A-2 340 201, of a grille made up of a steel heating cylinder, the surface of which can be smooth or have patterns in relief , and a counter cylinder which can be

  also either smooth or have recessed patterns corresponding to those of the heating steel cylinder.

  If for certain applications, the counter cylinder can also be made of steel, when it is desired to carry out embossing, stamping or lacquering operations, the

  against cylinder has a coating of plastic or densified cardboard, the hardness of which depends on the articles to be treated and the patterns to be produced.

  As an indication, the steel heating cylinder will have a maximum hardness corresponding to that of the metal used to make it, while the counter cylinder

  will have a hardness between 60 Shore and 90 Shore.

  Generally, when it is desired to make a real embossing, that is to say relatively large reliefs, the heating cylinder will have 2 2791708 raised areas corresponding to the patterns, and the counter cylinder hollow areas . In the case of a stamping operation, only the heating steel cylinder will have relief patterns, the counter cylinder being smooth, and, in the case of a simple lacquering operation, the two cylinders will have a surface smooth. In all cases, the peripheral speed of the two cylinders is identical and the pressure exerted against the fabric will depend on the one hand, on the spacing of the cylinder and the counter-cylinder and, on the other hand, for a given spacing of the cylinder and the counter-cylinder, by modifying the contact pressure, for example at

  means of cylinders acting in a plane containing the axes of the two cylinders.

  In general, to date, such a calendering operation, term which will be used

  in the following description, to designate both an embossing operation and a striking or lacquering operation, is carried out on fabrics which have been

  previously dyed or printed.

  Recently, in FR-A-2 729 158, it has been proposed, in particular with a view to reducing the pressure exerted on the textile web by the cylinder and the counter-cylinder, to preheat the face of the fabric to be embossed, for example by

  infrared radiation until a temperature of said face is obtained, for example of the order of 80 ° C., which promotes malleability, in particular the softening of said sheet before subjecting it to the calendering operation proper.

  Such a fabric preheating technique, which has been proposed for a very long time, as is apparent in particular from FR-A-1,562,544 which relates to the embossing of "velvet" type fabrics, however presents implementation difficulties when wishes to process fabrics or knits of light grammage, generally between 50 g / m2 and 200 g / m2, such as those which are generally

  used in the field of female lingerie.

  Furthermore, the "calendering" conditions, temperature and pressure, must be adapted as a function not only of the effects which one wishes to obtain, but also of the nature of the textile web which one wishes to treat. no 3 2791708 will treat a fabric or knit, a yarn-based article in a similar manner

  synthetic (polyamide, polyester ..) and an article based on natural fibers ...

  Finally, it is well known that the characteristics of a fabric or knitted fabric, in particular with regard to the feel and appearance, strongly depend on the strand count of the threads entering into its constitution. As an indication, nowadays, it is considered that for conventional textile applications (clothing, furnishing articles, lingerie ...), that synthetic threads can be classified into four main categories according to the fineness of the strands, at to know: _ microfibers, whose elementary title is less than a decitex and which are more and more proposed to make clothing articles or light, comfortable underwear, _ extra-fine strands, whose filaments are less than 2 dtex; - fine strands, whose filaments have a titer between 2 and 4 dtex and;

  ordinary strands, with filaments greater than 4 dtex.

  Of course, there may also be technical threads whose title by strand

  can be significantly higher than 4 dtex.

  However, it has been found in use that when calendering a fabric or knitted fabric made from polyamide yarns, and more particularly yarns whose elementary strands have a count of less than 2 dtex, that there had a problem regarding the permanence of the effect obtained, which effect tends to disappear during

  subsequent maintenance and washing operations in particular.

  Disclosure of the invention However, we have found, and this is the subject of the present invention, an improved method which makes it possible to solve this problem of the permanence of the effects obtained on such articles, knitted fabrics in particular, from synthetic yarns, more particularly based on polyamide and the filaments of which have a titer which can be less than 2 dtex, it being understood that such a process could possibly be

  used to process articles based on higher titer yarns.

4 2791708

  Furthermore, the method according to the invention is particularly suitable for carrying out a calendering operation on knitted fabrics, according to the technique of knitted fabrics (knitting / warp), of light grammage, generally between 50 g / m2 and 200 g / m2, and which are generally used in the field of female lingerie. In general, the invention therefore relates to a method of calendering a fabric produced from polyamide yarns in order to modify its surface appearance and / or give it relief patterns by passing between a heating cylinder 10 in steel and a counter-cylinder comprising a coating of plastic or densified cardboard, said process being characterized in that: _ the calendering operation is carried out on a fabric having received a pre-treatment making it suitable for dyeing and consisting in degreasing and thermofixation by passing over a train; during the calendering operation, the counter-cylinder is surface preheated to bring it to a temperature of the order of 130 C, the temperature of the steel cylinder being set at a higher level of the order of 5 to 10% relative to a normal calendering temperature which, for polyamide, is traditionally of the order of 190 C; _ the calendered fabric is cooled immediately after it leaves the calender before being rolled up to be then subjected to a conventional dyeing treatment, full bath, without pressure and at a temperature of the order of 100 C; - after dyeing, the treated fabric receives a conventional finishing treatment

(drying / priming) on oar.

  Such a method is particularly suitable for being applied to fabrics, in particular warp knits, based on polyamide, the filaments of which are microfibers possibly associated with another constituent, such as for example

  elastane yarn giving extensibility to the product produced.

  It has also been observed, in particular when the calendering operation is intended to carry out a simple lacquering of one face of the product, that it is advantageous for the heating cylinder to exert an action against the surface of the knitted fabric.

  on which are visible the piers under the needles.

2791708

  For the implementation of the method according to the invention, such an installation comprises, upstream of the zone for introducing the fabric between the

  cylinders, means for heating the counter-cylinder, for example an infrared ray heating ramp.

  At the outlet of the calender, the treated article can either be cooled naturally, or undergo accelerated cooling by any suitable means.

Brief description of the drawing

  The single appended figure illustrates, in general, the whole of a calendering installation allowing the implementation of the method according to the invention. Manner of Carrying Out the Invention The invention will however be better understood thanks to the concrete examples given below for information, but not limitation, the calendering operations being carried out on a conventional machine comprising a steel heating cylinder, the surface of which can be smooth or have raised patterns and a

  counter-cylinder which can also be either smooth or have recessed patterns corresponding to those of the heating steel cylinder.

  In these examples, the method according to the invention is implemented on a calendering installation as illustrated diagrammatically by the appended figure, and which essentially consists of a heating cylinder (1) made of metal, steel in particular, and a counter-cylinder (2) which, in the context of the invention,

  has a coating of plastic or densified cardboard, but is not metallic.

  Depending on the articles to be produced, the cylinders (1) and (2) can be smooth or have raised or recessed patterns.

  The fabric (3) to be treated comes from a winding (4), passes between the two cylinders (1) and (2) to, after treatment, be received in the form of a winding (5). The calendering pressure is communicated, in this form of 6 2791708 embodiment, by means of a pressing cylinder (6) making it possible to obtain a

  uniform pressure across the width.

  In the concrete examples which follow, the fabric (3) which must be calendered, is a fabric which, after weaving, has received all the treatments making it suitable for dyeing, treatment which consists of degreasing and heat-setting by

passage on oar.

  Furthermore, during the calendering operation, the counter-cylinder (2) is

  surface preheated by any suitable means, such as an infrared ramp (7).

  The conditions of tension of the fabric during treatment are adjusted so as to allow an unwinding, a passage and a winding of the fabric without folds or

deformation.

  After calendering, the treated fabric is cooled either by passage in the open air or on the cylinder plates accelerating the cooling before being returned in the form of a reel in (5) .20 The calendered fabric is then subjected to a conventional dyeing treatment which, in the context of the present invention, must be carried out full

  bath, without pressure, and at a temperature of the order of 100 C.

  Example 1 On an installation as described above, a woven article is produced, the heating cylinder (1) and the counter-cylinder (2) comprising patterns in relief and

in complementary hollow.

  The article treated is a knitting made on a 2-bar warp loom, composed of textured polyamide threads, the strands of which have a count of 1 dtex (microfibers).

  The knitting weave is a charming weave and, at the end of the trade, with an extensibility of the order of 30%, both in the long direction and in the broad direction.

7 2791708

  Before calendering treatment in accordance with the invention, this article is subjected to a conventional degreasing and heat-setting treatment by passing over a ream at 190 C for a period of 40 seconds, the knitted fabric thus treated weighing 190 g / m2 for a width of 150 cm.5 In accordance with the invention, the knitted fabric is subjected to calendering under the following conditions: _ temperature of the heating cylinder (1) established at 205 ° C., that is to say approximately 10% higher than a temperature conventional calendering of a polyamide fabric; preheating of the cylinder (2) so that in normal operation it reaches a temperature of the order of 130 C; _ bearing pressure of the cylinders (1) and (2) against the fabric: 150 bars

  - speed of passage of the fabric: 3 m / min.

  At the exit of the grille, the fabric has a pleated effect corresponding to the raised and recessed pattern of the cylinders and counter cylinder.

  The pleated fabric is then dyed in a conventional manner, full

  bath, without pressure, and at a temperature of the order of 100 C.

  After wringing and finishing treatment, the pleated article is ready to be marketed and made up.

  It is clear that by proceeding in such a way, a permanent pleated effect was obtained which was not affected by the subsequent washings.

  By way of comparison, the same polyamide knitted fabric, calendered after being dyed, and under conditions such that the counter-cylinder (2) was not preheated, the cylinder (1) having a temperature of 190 C, certainly allows '' get a pleated effect, but this effect is not permanent and fades, even disappears when

subsequent washes.

8 2791708

Example 2

  The lacquering operation is carried out on a warp knitted yarn made of textured polyamide yarn consisting of microfibers of 1 dtex, and which, after treatment as previously of degreasing and heat setting, weighs 160 g / m2 for a width of 165 cm. The lacquering operation is carried out by passing the fabric over a calender whose two cylinders (1) and (2) are smooth, the conditions for adjusting the temperature and pressure being identical to those of Example 1.10 It is advisable note that the action of the heating cylinder (1) is carried out on the face of the knitted fabric, comprising the jetties under and not against the surface of the columns

of meshes.

  The winding of the treated fabric (3) is carried out in (5) without tension on the treated fabric.

  After dyeing treatment, also carried out under the same conditions as in Example 1, the treated fabric is rewound for use.

  It should be noted that at the end of the finishing treatment, the fabric is immediately rewound to be cooled and stabilized without forming a fold.

  With such processing conditions, a fabric is obtained, one of the

  sides is perfectly lacquered and whose effect remains stable after several successive washes.

  By way of comparison, a fabric having been lacquered under conventional conditions, that is to say by carrying out a calendering operation on the fabric

  previously dyed, and without preheating the counter-cylinder, does not allow the effect to be stable over time.

  Of course, the invention is not limited to the examples given above, but it covers all the variants produced in the same

mind.

9 2791708

  If such a treatment is particularly suitable for articles based on polyamide, in particular produced from multifilament yarns the strands of which are made of microfibers, it could also be envisaged to use it for any

  other type of fibers which can be dyed at a temperature below 100 C.

2791708

Claims (5)

  1 / Method of calendering a fabric (3) made from polyamide threads in order to modify its surface appearance and / or give it relief patterns by passing between a steel heating cylinder (1) and a counter -cylinder (2) comprising a coating of plastic or densified cardboard, characterized in that: _ the calendering operation is carried out on a fabric (3) having received a pre-treatment making it suitable for dyeing and consisting of degreasing and heat-setting by passing over a train; _ during the calendering operation, the counter-cylinder (2) is surface preheated to bring it to a temperature of the order of 130 C, the temperature of the steel cylinder (1) being set at a higher level of of the order of 5 to 10% relative to a normal calendering temperature which, for polyamide, is traditionally of the order of 190 C; _ the calendered fabric is cooled immediately after it leaves the calender before being rolled up to be then subjected to a conventional dyeing treatment, full bath, without pressure and at a temperature of the order of 100 C; 20 _ after dyeing, the treated fabric receives a conventional finishing treatment (drying / priming) on oar.   2 / A method according to claim 1, characterized in that the fabric (3) consists of a warp knit based on polyamide, the filaments of which are   microfibers possibly associated with another constituent, such as for example an elastane yarn conferring extensibility on the product produced.   3 / Method according to one of claims 1 and 2, characterized in that the heating steel cylinder (1) exerts its action against the surface of the knitted fabric   which are visible the piers under the needles.   4 / Method according to one of claims 1 to 3, characterized in that the surface of the cylinder (4) and the counter-cylinder (2) are smooth, making it possible to obtain a lacquering effect. 35 il l 2791708   / Method according to one of claims 1 to 4, characterized in that the heating cylinder (1) comprises patterns in relief, the counter-cylinder (2) being able   be either smooth or have recessed parts corresponding to those in relief of the heating cylinder.   6 / Installation for the implementation of the method according to the invention according to one of claims 1 to 5, characterized in that the means of   preheating (7) of the counter-cylinder consist of an infrared ray heating ramp positioned opposite the counter-cylinder upstream of the area 10 for introducing the fabric against said cylinder.