FR2605023A1 - MODIFIED SURFACE STATE FABRICS AND METHOD FOR OBTAINING THEM. - Google Patents

Abstract

THE INVENTION CONSISTS OF NEEDLING A FABRIC CONSTITUTED OF CONTINUOUS FILAMENT YARNS, EACH YARN INCLUDING A LARGE NUMBER OF LOW TWISTED (AT LEAST 50) FILAMENTS (AT LEAST 250 TURNS PER METER). THE ACTION OF THE NEEDLES HAS THE EFFECT OF CUTTING CERTAIN FILAMENTS AND OF MOVING THE CUT FILAMENTS TOWARDS THE SURFACE OF THE FABRIC OPPOSED TO THAT OF INTRODUCTION OF THE NEEDLES. THE MECHANICAL CHARACTERISTICS OF THE FABRIC ARE REDUCED BUT THE ADHESION IS VERY STRONGLY INCREASED. THE FABRIC IS USED AS A COATING SUPPORT.

Description

SURFACE-MODIFIED FABRICS AND METHOD FOR OBTAINING SAME

  The present invention relates to a fiber-like fabric obtained at

  from a fabric consisting of continuous filament yarns.

  The continuous filament yarn, or continuous yarn, is inherently smooth whereas the yarn of fibers is bulkier, more swelling and has better adhesion to the coatings.

  On the other hand, the continuous yarn is stronger than the yarn of fibers.

  Texturing of continuous yarns has already sought to manufacture yarns combining the advantages of continuous yarns and yarns of fibers, but texturing gives the yarn an elasticity which is undesirable in certain applications, particularly in the field of coating media fabrics. In these technical applications, the properties

  of the fabric must first and foremost be very

  and the best adhesion possible with the coating product.

  To obtain this combination of properties, the producers used

  either high-strength twisted yarns of high strength, or core yarns, i.e. yarns made of a filament core

  continuous and a cover in fiber yarns: the soul brings the

  resistance, the cover the power of adhesion. These two products are

  much more expensive than traditional continuous wire, and in

  most common cations the producers use the fabric

  in spite of its mediocre properties in terms of adhesion

  ence. Now it has been found, and this is the subject of the invention, a process for obtaining a fabric having the state of fibrous surface

  which considerably increases its adhesion with the product of

  while having sufficient strength for this application.

  According to the process of the invention, we start from a fabric made up of

  filaments, each yarn having a large number of

  weakly twisted laments, the tissue is subjected to the double action of

  bearded guilleas, resulting in the penetration of

  in the fabric, on the one hand to cut some filaments and on the other hand

  part of moving the cut filaments towards the surface of the oppo-

  the introduction of the needles. The needling technique which is advantageously used for the implementation of the method of

  the invention is a well known technique in the field of non-war

  A large number of bearded needles cross a web of

  in a back-and-forth movement, the action of the barbs tends to move the fibers relative to each other, to intertwine them

  and thus to bind the web of fibers through the intermingling of fibers.

  It is also known to needle a sheet of fibers by placing it on a consolidation grid formed by a fabric, a plastic film or even a paper. The fibers of the sheet penetrate into the grid.

  consolidation under the action of the needles and the non-woven is solidari-

  se with said grid. But until now, the breaking of fibers or continuous filaments during needling has always been considered a disadvantage, since it entails a loss of strength.

  of the finished product. It is therefore the peculiarity of the invention that

  the needling technique on a given type of product.

  to take advantage of what was previously

  stunned as a disadvantage. The fact that the constituent threads of

  tissue have weakly twisted strands allows good

  needle setting within each wire; the fact that the son have a large number of strands keeps the fabric, after needling, sufficient strength through the uncut strands. The action of the needles on the strands is twofold: in a

  first time the strand that was previously a continuous filament is

  second, because the cut slice has an extremity

  free, it can move during other penetrations of the needle.

  The displacement of the cut strands under the dragging effect of the beards

  the needle creates a fibrous appearance on the surface of the tissue; the quantity

  of strands emerging from the surface of the fabric, opposed to that of introducing

  of the needles, is of course a function of the intensity of the

  This mechanical needling action according to the invention

  Another advantage is to improve the hold of the fabric in particular.

  especially when starting from a fabric whose contexture is relatively

loose.

  Preferably, the twist of each continuous filament yarn is at most equal to 250 turns per meter. The number of continuous filaments

per wire is at least 50.

  The invention also relates to the fabric obtained by the implementation of the aforementioned method. This fabric comprises yarns consisting of both continuous filaments and cut filaments, all of these filaments being slightly twisted, and all or part of the cut filaments being displaced relative to the continuous filaments so as to

protrude from the surface of the fabric.

  The fabric according to the invention is advantageously used as a

  coating port, the coating being performed on the face of the fabric having a surface appearance fiber-like, o exceed the filaments

cut.

  The invention will be better understood on reading the description

  which will be made of several examples of obtaining a tissue to as-

  fibrous pect. The starting fabric is a warp and weft fabric,

  stained with continuous filament yarns of high tenacity polyester. The titration of the threads is 1100 dtex, each thread has 60 twisted strands

  at 130 turns per meter. The fabric has a texture of 7.8 x 8.2, defined

  the average number of threads per centimeter in warp and weft.

  The aforementioned fabric is subjected to the repeated action of bar-shaped needles.

  bes, in a classic needling material. This material is

  of a needle board animated by a reciprocating movement of

  and -drop, two perforated plates, a food apron that carries the fabric and two output cylinders synchronized with the movement of the needle board, so that the fabric is stationary during the downward movement of the board and advances a certain distance during the upward movement, when the fabric is no longer traversed by the needles. The fabric is inserted between the two plates that hold it during the action of the needles. The needle board goes down until the needles are

  contact with the tissue and pass through it. The equipment includes a mechanism

  adjustment of the striking stroke, that is to say the movement of the needles, which makes it possible to vary the depth of penetration

  of the needle in the tissue, and thus the number of barbs of the needle.

  which will penetrate the fabric. In the example described, there were 30 needle shots per square centimeter with a penetration set to 18 millimeters. These needles were of reference 15 x 18 x 32 x

  3,5 RB 30 A06 / 15 of the brand SINGER.

  By penetrating into the fabric, which consists of continuous threads, the needle hangs through its barbs some of these filaments; under

  the mechanical action and the jolt of tension, filaments break.

  The cut filaments, which therefore have a free end, can

  then move, like the fibers in a sheet of needling fibers; the barbs of the needle cause these filaments

  cut to the surface of the tissue opposite to that of

  Guilles; the filaments thus entrained protrude from said surface, either in the free state or in the form of a loop if the cut end has remained inside the fabric. The face of the tissue presenting the state

  of modified surface, fiber appearance, was coated. The product of

  is a PVC paste. The coating was squeezed, drying at 140 ° C. for 4 minutes followed by cooking at 180 ° C. for 2 minutes. To measure the adhesion of a coated fabric, the coating product is peeled and the force used is measured.

  to perform this peeling at a speed of 100 millimeters per minute.

  In the case of the untreated control fabric according to the invention, the peel force is 4.5 daN; in the case of treated fabric it is 32.5

  daN. Adhesion between the fabric and the coating product has been considered

  durably improved by a factor of 1 to 7. As far as

  the loss of strength of the fabric itself after treatment is 18% in weft direction and 40% in the warp direction. Tear resistance dropped 60% in both directions. After needling

fabric has a texture of 10 x 10.

  The example above illustrates the very significant increase in

  the adhesion that can be achieved, but of course to the detriment of the

  mechanical properties of the fabric, namely breaking strength and tearing.

  In the following example, we sought to maintain better

  mechanical characteristics while having a very high adhesion. he

  is a fabric made of continuous filament yarns of polyamide.

  The titration of the threads is 940 dtex, each thread having 140 strands twisted at 200 turns per meter. The fabric has a texture of 7 x 7. The

  tissue is subjected to the action of the same needles as above,

  sound of 30 needle shots per square centimeter with a penetration set to 10 millimeters. After needling, the fabric has an 8 × 8 texture. The needled fabric exhibits a loss of tensile strength of 26% in the weft direction but a 5% strength gain in the warp direction. The tear resistance is almost unchanged. The peel strength is 18.8 daN, whereas it is only 2.25 daN for the non-needled control tissue.

  The invention is not limited to the examples which have just been

  writings; for each product, each intended application, it is possible

  It is possible to achieve a balance between the change in surface condition of the fabric and the loss of strength and tear due to breaks in the continuous filaments. It is also possible to change the state

  surface area of both sides of the fabric by carrying out

  successively on one and on the other faces.

  The method according to the invention applies to any type of material; thus conclusive tests were carried out on tissues made up

  of aramid threads known as KEVLAR, which makes it possible to

  use these fabrics as a coating medium.

  As has been understood, the privileged use of the invention

  tion is the production of coating support fabric. However, the

  vention is not limited to this application, it will be usefully

  is implemented whenever o will be sought for a fabric son

  continuous fibrous-looking surface condition without significant loss

  its mechanical characteristics.

  Finally, in the text above, the general term "tis-

  su "without this being limited to the mode of crisscrossing son, it may be woven fabrics themselves and knitted fabrics.

Claims (6)

  1. Process for obtaining a tissue having on one face a fibrous surface state characterized in that one starts from a fabric constituted by   of continuous filament yams, each yarn having an important number   so many weakly twisted filaments and the said tissue is subjected to the double action of barbed needles, having the effect during penetration of   needles in the fabric on the one hand to cut some   laments and on the other hand to move the cut filaments towards the   face of the opposite fabric to that of introduction of the needles.   2. Method according to claim 1 characterized in that each wire   is at most twisted at 250 turns per meter.   3. Method according to one of claims I and 2 characterized in that   each wire comprises at least 50 strands.   4. Fabric obtained by the implementation of the method according to the claim   characterized in that it comprises yarns consisting of both continuous filaments and cut filaments, all the constituent filaments of a yarn being slightly twisted, and in that all or part of the cut filaments are displaced by ratio to the filaments   continuous so as to protrude from the surface of the fabric.   5. Fabric according to claim 4 characterized in that each wire is at most twisted at 250 turns per meter and has a total number of filaments at least 50.   6. Use of the fabric according to claim 2 as a support for duction.