FR2667619A1 - COMPOSITE POLYESTER / VISCOSE YARNS AND ETOFFE CONTAINING SUCH YARNS AS A SOFT SUPPORT OF APPLIED ABRASIVE. - Google Patents

Abstract

A composite polyester/viscose spun yarn comprising polyester fibers and viscose fibers, fabrics comprising the polyester/viscose spun yarns, and a method of making the same are taught. The fabric is useful as a backing for coated abrasive articles.

Description

COMPOSITE YARN OF POLYESTER / VISCOSE AND ETOFFE CONTAINING
OF SUCH THREADS AS A SOFT SUPPORT OF ABRASIVE
APPLIED
FIELD OF THE INVENTION
The present invention relates to the field of flexible abrasive media. More particularly, it relates to polyester / viscose composite yarns, fabrics or textiles made from these composite yarns as flexible coated abrasive materials and a process for preparing said supports.

PRIOR ART
The flexible abrasive media currently used are essentially made of combed Egyptian cotton yarn (in English: "combed Egyptian cotton").

 These are woven textile supports which have been prepared according to a process comprising in particular the steps (i) of sizing the warp yarns, (ii) desizing, (iii) stretching in an aqueous bath and then (iv) ) finishing treatment on one or both sides, in particular by coating. The woven supports thus obtained are then coated on one side (in particular the so-called top face) of an adhesive layer, said adhesive layer making it possible to bind the grains or particles of the abrasive material to the support.

 In this process, the desizing step (ii) is intended to eliminate sizing agent which hinders or reduces the quality of the adhesion of the layer or of the finishing layers.

 The sizing agent, mainly deposited on the warp threads of woven textile fabrics to consolidate said warp yarns, has the disadvantage of reducing the adhesion of the finishing materials to the glued fibers. The desizing is therefore performed to obtain a better attachment of the finishing material on the son and to confer the desired qualities of flexibility and surface being for the support.

 The commercial success of the woven Egyptian cotton woven supports lies in the qualities of flexibility, surface condition and cohesion, especially resistance to breakage. In particular, the woven Egyptian cotton woven supports of the weight class J have, in general, in a relative humidity environment of 0%, a weight of up to 220 g / m 2, a breaking strength in the machine direction (ie in the warp direction) and respectively in the transverse direction Ci.e. in the weft direction) about 140 daN / s cm and respectively about 60 daN / s cm.

 Attempts to replace combed Egyptian cotton fiber yarn with less expensive fiber yarns have proved unsuitable for the mechanical properties of the resulting fabrics as flexible supports for the coated abrasive. Such is the case of the technical solutions proposed in US-A-3,316,072, GB-A-1,251,676, US-A-4,035,961 and US-A-4,282,011.

 US Pat. No. 3,316,072 recalls in its preamble the difficulties of using polyester fiber yarns in the manufacture of flexible abrasive supports and recommends composite polyester / cotton yarns.

 GB-A-1,251,676 proposes a process for the preparation of flexible abrasive supports similar to the one mentioned above with the difference that the step (ii) of desizing is not carried out and that stages (iii) and (iv) are carried out simultaneously, the finishing step comprising the use of an aqueous finishing emulsion containing a solvent system for partially swelling the sizing agent at a temperature of 15-450C and then partially dissolving said agent sizing at a temperature of 65-2000C, so that the final support comprises the finishing means deposited on the sizing means. This patent, which involves swelling of the sizing agent and the use of an organic solvent system, does not describe any example of polyester / viscose composite yarns.

 US-A-4,035,961 emphasizes in its preamble the difficulties associated with the use of polynosic fibers such as rayon in the manufacture of flexible abrasive media. On the other hand, it neither describes nor suggests polyester / viscose composite yarns in the manufacture of the supports that it recommends.

 US-A-4,282,011 recommends the use of a composite woven fabric comprising in one direction (warp) fiberglass yarns and, in the weft transverse direction, yarns of organic cotton, polyester, polyester fibers. -cotton, nylon, wool or acrylic.

PURPOSE OF THE INVENTION
According to the invention, a new technical solution is proposed to solve the problem of obtaining textile fabrics useful as coated abrasive supports having the required properties of flexibility, surface state and cohesion.

 For this purpose, it is proposed according to the invention to use polyester and viscose fibers whose composite son are well known in the field of clothing textiles.

 According to a first aspect of the invention, it is proposed, as a new industrial product, a composite yarn of polyester and viscose fibers for obtaining fabrics for flexible supports of applied abrasive.

 According to a second aspect of the invention, it is proposed to provide woven, nonwoven or flexible knitted textile supports having properties of flexibility, surface condition and cohesion comparable to or superior to those of the cotton fiber supports. Egyptian combed without the fibers of the supports used in accordance with the invention are altered by the adhesive for fixing the grains or abrasive particles.

 According to a third aspect of the invention, a novel process for the preparation of fibrous supports intended to be coated with an adhesive mass which bonds the abrasive means is recommended.

OBJECT OF THE INVENTION
According to the invention, it is recommended to use a polyester / viscose composite yarn for a flexible fabric coated with an abrasive means, said composite yarn being characterized in that it consists of a mixture of (1) fibers of a viscose component. and (2) fibers of a polyester component, and in that it has a basis weight of less than or equal to 350 g / m 2.

 According to the invention, a fabric for use as a flexible abrasive support is also recommended, said fabric being characterized in that it comprises at least 25% by weight of polyester / viscose composite yarns.

The process for preparing said fabric can be carried out according to known operating procedures, by application of conventional mechanisms. The method that is recommended according to the invention for the preparation of a flexible support of abrasive composite material, is characterized in that it comprises the steps of
(a) use a glued woven fabric
selected from the group consisting of
woven fabrics comprising at least 25% by weight
of polyester / viscose composite yarns next
any one of claims 1 to 8; and,
(b) wet stretching said woven fabric
containing said polyester / composite yarns
viscose without substantial desizing, then
drying said stretched fabric thus obtained,
a temperature of at least 900 C and preferably
110-200 C.

 The technical solution according to the invention is distinguished by several aspects of the technical solution described in GB-A-1,251,676, it is distinguished in particular by the fact that, unlike the teaching of GB-A No. 1,251,676, it does not use an organic solvent or a system of organic solvents; this avoids the tedious and expensive operations of disposal and collection of organic solvents to protect staff and the environment.

DETAILED DESCRIPTION OF THE INVENTION
As indicated above, the composite yarn according to the invention consists of a blend of viscose viscose fibers and polyester polyester fibers), the density of said composite yarn being less than or equal to 350 g / m 2.

 In this composite yarn, the fibers of the viscose component will advantageously be chosen from the group consisting of rayon fibers and fibers of fibranne, the fibers more particularly preferred here being the fibers of fibranne (abbreviated to MF). spun staple rayon fibers "], especially those supplied under the commercial reference of" MODAL "by the company known as LENZING.

 Also advantageously according to the invention, the composite yarn comprises (1), as a viscose component, 35 to 70% by weight of viscose fibers, and (2) as a polyester component, 65 to 30% by weight. weight of polyester fibers.

 The viscose component which is used in the composite yarn according to the invention is chosen from the so-called high-tenacity products. The yarns made from the high tenacity viscose fibers have, in the conditioned condition of 65% relative humidity and 200 C, a fracture toughness greater than or equal to 25 cN / tex.

 Also advantageously according to the invention, the polyester / viscose composite yarn is such that (1) the viscose component consists of viscose fibers having a cutting length of 32-40 mm and a linear density of 1.3. 1.7 dtex, and (2) the polyester component (abbreviated as PE) consists of polyester fibers having a cutting length of 25-50 mm and a linear density of 1.3-1.7 dtex, especially a linear density of 1.3-1.5 dtex.

 The weight ratio (R) of the polyester component to the viscose component is a very important element according to the invention.

 Thus, when said ratio R is greater than 65/35, the resulting fabric does not exhibit the required properties of elongation resistance and breaking strength. When said ratio R decreases from 65/35 to 30/70, the compromise flexibility / resistance to breakage and elongation of the resulting fabrics increases overall to a maximum corresponding to a ratio R of 1/1 and then decreases said ratio R = 1/1 to R ratio of 30/70. When said ratio R is less than 30/70, the resulting fabrics are no longer suitable for the intended use as flexible coated abrasive media.

 The textile fabric useful as an abrasive support applied may be a nonwoven, a woven or even a knit. According to the best mode of implementation of the invention, it will be used, as an abrasive support applied to a woven fabric containing composite yarns based on polyester fibers and fibers of fibranne, the weight ratio polyester / viscose then being 1/1 in said composite son.

 In practice, the textile fabric according to the invention is characterized in that it contains at least 25% by weight of composite yarns according to the invention, preferably the viscose component of said composite yarns consisting of fibers of fibranne, especially the "MODAL" fibers mentioned above.

 In the woven fabric frame, the weft and warp threads may be constituted by said composite yarns. As a variant, some of these threads may be replaced by threads of fibers of another kind; for example, in a woven fabric, only the warp yarns will be polyester / viscose composite yarns, the weft yarns then being of a different nature. Alternatively also, one can use in the chain a mixture of composite son according to the invention and son of other nature. If necessary, it is possible, mutatis mutandis, to use, as warp threads, the aforementioned weft threads and, as weft threads, the aforementioned warp threads.

 Among the composite fabrics that can be used according to the invention, those whose weft and warp consist of said polyester / viscose composite yarns, on the one hand, and those whose warp consists of said polyester / viscose composite yarns and whose weft is made of polyester or cotton yarn, on the other hand. If necessary, it is also possible to combine in the warp and / or weft the polyester and viscose composite fibers according to the invention with other textile fibers, in particular polyamide or acrylic fibers.

 The fabric according to the invention will consist of a woven fabric having a dry weight less than or equal to 350 g / m2. In particular, said fabric may have in particular a dry weight in the range of 260-300 g / m2, 220-260 g / m2 or 80-220 g / m2. These aforementioned ranges include so-called J-type textile varieties which have a weight of 180 + 20 g / m 2, X which have a weight of 240 + 20 g / m 2 and Y which have a weight of 280 + 20 g / m 2.

 The invention also relates to the use of such a fabric as a coated abrasive carrier.

The method of the invention referred to above may, where appropriate, also comprise the step of
(c) coating said fabric, thus dried, on
least one of its faces with a material
softwood suitable for a surface coating.

 Preferably in step (a), the viscose fibers of the viscose component are essentially rayon and preferably fibran fibers. Also preferably, the weight ratio of the polyester component to the viscose component will be in the implementation of this method of about 1/1, the preferred viscose fibers being, as indicated above, fibers of fibranne.

 When the fabric to be used as an applied abrasive carrier is a woven fabric, the sizing is essentially performed on the warp yarns. The woven fabric, which has been glued, is constituted by glued string yarns and weft yarns which, in general, have not been glued.

 For carrying out the process according to the invention, in step (b), the wet drawing is carried out by passing said polyester / viscose woven fabric in an aqueous bath at a temperature of about 150 to about 1000 C, and under a load of 10 to 100 kg / 40 cm width. The aqueous bath may contain, if appropriate, a coloring agent. Preferably, the drying of stage (b) will be carried out at a temperature of at least 900.degree. C., and preferably of 1102000.degree.

 The surface treatment of stage (c) is carried out so as to obtain a dry weight input of 10150 g / m 2 on at least one side. This treatment is a finishing treatment on one side (i.e. the so-called side weft or non-twill side) or on two sides (i.e. the so-called side weft side and the opposite side called side chain or twill).

 The finishing of the warp side consists in the deposition of a layer of pre-primer to be subsequently coated with the adhesive mass fixing the abrasive material.

The finish of the weft side face is advantageously carried out according to a first coating.

 The finish of the side chain side, when it is necessary to perform it, consists in the deposition of another primer composition used for the consolidation of the thus pre-primed fabric.

 The finish of the chain side is advantageously carried out following a second coating.

 According to another characteristic of the process of the invention, in step Ca), the woven fabric containing said polyester / viscose composite yarns is sized according to the warp yarns, and has superior breaking strength in the machine direction or equal to 70 daN / S cm width in the conditioned state of 65% relative humidity and 200C.

 The support according to the invention for abrasive material, which is obtained according to the aforementioned method, advantageously has a machine direction elongation of less than or equal to 8%, under a load of 90 daN / s cm in the conditioned state of 65% relative humidity and 200C. It will even more advantageously have a machine direction elongation of 6.5 Z or less under a load of 90 daN / S cm in the conditioned state of 65% relative humidity and 200 ° C.

 Said support according to the invention is then treated according to a conventional method for the deposition of the adhesive layer carrying the abrasive material.

 The abrasive material is preferably a material selected from the group consisting of aluminum oxide, aluminum oxide ceramics, zirconia containing alumina, silicon carbide, flint, garnet, diamonds and their mixtures. Typically, the grains or abrasive particles are fixed by a first adhesive layer or binder layer commonly referred to as "bond coat". A second adhesive layer or even a third adhesive layer or layers of binder may be applied to the abrasive grains; they are designated by the terms "coated layer" (English: "size coat") and, respectively, "rerencollage layer" (in English: "supersize coat") and provide additional reinforcement of the binding of abrasive grains. Usual adhesives for these three aforementioned layers include phenol-formaldehyde, melamine-formaldehyde, urea-formaldehyde resins, animal glues, epoxy resins, acrylic resins, and mixtures thereof. Alternatively, the applied abrasive material article may not necessarily include the "bonding layer" and "bonding layer", in which case the abrasive grains are mixed with an adhesive or binder and then applied to the substrate under the bonding layer. form of a dispersion (in English: "slurry"). After the coated abrasive article has been prepared, it can be processed into a variety of different shapes such as discs, sheets and endless belts.

 Other advantages and characteristics of the invention will be better understood on reading the following description of examples of embodiments and tests. Of course, these elements are in no way limiting, but are given by way of illustration.

EXAMPLE 1
Preparation of an abrasive woven support applied from polyester / fibran composite yarns.

(a) fibers used
The selected fibers of polyester (so-called PE) and fibran ("spun staple rayon fibers") are used here
- PE: "TERGAL" Tell "fibers supplied by the company known as RHONE-POULENC and presenting
- a title of 1.45 dtex,
- a section of 38 (ranging from 30 to 40
mm)
a tenacity of 62-64 cN / tex [measured at
conditioned state (65 Z RH; 200C)], and
- an elongation at break of 16 Z [me
conditioned state (65% RH;
200C)]; and,
- NF: "LENZING MODAL HIGH TENACITY" fibers supplied by the LENZING company and presenting
- a title of 1.7 dtex,
- a cut of 40,
a tenacity of 34-36 cN / tex [measured at
the condition conditioned above], and
- an elongation at break of 13-15 Z
measured in the above conditioned state].

(b) Obtaining composite yarn
The aforementioned PE and NF fibers were intimately mixed in a PE / MF weight ratio of 1/1, then carded, doubled, stretched to form wicks having a slight twist, the intensity of the twist being of the order of 600 to 850 turns / m. The conventional spinning system (of the ring-slider type) then made it possible to deliver 34, 40 and 50 m metric threads for 1 g (ie metric number (Nm) of 34, 40 from these melts. and 50] respectively.

 The influence of the torsion exerted in the continuous spinning is illustrated by the results of comparative tests recorded in Table I below.

TABLE I

<tb> Thread <SEP> Nm <SEP> (1) <SEP> (2) <SEP> (3)
<tb> A <SEP> 34 <SEP> 619 <SEP> 26.0 <SEP> 12.0
<tb> B <SEP> 34 <SEP> 32.0 <SEP> 16.0
<tb> C <SEP> 34 <SEP> 23.0 <SEP> 10.8
<tb> D <SEP> 34 <SEP> 16.0 <SEP> 7.0
<tb> E <SEP> 34 <SEP> 651 <SEP> 20.8 <SEP> 11.1
<tb> A <SEP> 40 <SEP> 690 <SEP> 25.0 <SEP> 11.8
<tb> E <SEP> 40 <SEP> 725 <SEP> 20.5 <SEP> 10.6
<tb> A <SEP> 50 <SEP> 801 <SEP> 23.0 <SEP> 11.5
<tb> E <SEP> 50 <SEP> 841 <SEP> 19.5 <SEP> 10.1
<Tb>
Notes
PE / MF composite yarn according to the invention with report
1/1
B polyester yarn (PE)
C fibrous thread (MF)
D worsted Egyptian cotton yarn
E composite polyester / cotton yarn Egyptian combed with
weight ratio 1/1 (1) torsional strength (in revolutions / m) (2) toughness in the above conditioned state (expressed in
cN / tex) (3) elongation at break, in pre-conditioned state
quoted (in%)
The results of Table I show that, according to the invention, the best compromise with regard to toughness and elongation at break is obtained with the composite yarns having a low intensity twist and of the order of 600-850. revolutions / m, and that the intensity of the torsion increases with the Nm (from 619 revolutions / m for the wire A of Nm 34 to 801 turns / m for said wire A of Nm 50).

 The results of Table I also show that the polyester / viscose composite yarns, and in particular the PE / MF yarns, can be used as a replacement for combed Egyptian cotton yarns with regard to the properties of toughness and resistance to elongation.

 The polyester / viscose composite yarns according to the invention, and in particular the PE / MF yarns, also have the advantage of being less expensive than combed Egyptian cotton yarns, of having an excellent surface regularity due to the nature of the polyester and viscose fibers, and subsequently avoid the expensive desizing operation. According to the invention, despite the sizing, thanks to the choice of composite PE / MF son, is retained the desired flexibility and tacking ability of the finishing means.

(c) Weaving
The composite yarns, to be used as warp yarns on the loom, are cylinder-woven and glued by means of a conventional sizing device. Sizing (in English: "sizing") is intended to impregnate the warp son by means of an aqueous bath so as to leave around the composite wire, which is treated, a superficial deposit allowing it to better endure the future constraints affecting the loom.

The aqueous sizing bath used here responded to the following formulation I
FOBMUL & ION I - water ............................ 100 parts by weight - carboxymethylcellulose mixture
polyvinyl alcohol ("ROTTA 989"
provided by the company
ROTTA) 4 parts by weight - carboxymethylcellulose ("CMC P 400"
provided by the so-called society
SOPATIS) ....................... 2 parts by weight - bath temperature ............ 75-850C.

With the composite yarns A of Table I according to the invention, woven fabrics of type J (ie "Jean") of twill weave 2/1 weighing 180 + 20 g / m 2 were prepared, namely
Ex 1A:
Jean cloth 38 x 24 Nm 34/40 which the sons of
warp and weft are PE / MF composite yarns
in the 1/1 weight ratio;
Ex 1B:
Jean fabric 38 x 24 Nm 40/50 which the son of
warp and weft are PE / MF composite yarns
in the 1/1 weight ratio; and,
Ex 1C:
Cloth Jean 38 x 24 Nm 34/50 which the sons of
chain are PE / MF composite yarns in the
1/1 weight ratio, and the weft threads are
American cotton threads carded.

The values shown in Table II below for the fabrics of Examples 1A, 1B and 1C, as well as those relating to the D1-D3 fabrics woven from combed Egyptian cotton warp and weft threads, show that the fabrics according to US Pat. invention have breaking strengths of the same order as those of D1
D3, the D1-D3 fabrics having different but neighboring contexts.

TABLE II

<tb> Cloth <SEP> Jean <SEP> (1) <SEP> (2) <SEP> (3)
<tb><SEP> Ex <SEP> 1A <SEP> 170 <SEP> 128 <SEP> 65
<tb><SEP> Ex <SEP> 1B <SEP> 151 <SEP> 96 <SEP> 52
<tb><SEP> Ex <SEP> 1C <SEP> 160 <SE> 129 <SEP> 35
<tb> D1 <SEP> (4) <SEP> 130-135 <SEP> 75-80
<tb> D2 <SEP> (4) <SEP> 120-125 <SEP> 45-50
<tb> D3 <SEP> (4) <SEP> 130-135 <SEP> 45-50
<Tb>
Notes
(1) weight in the conditioned state Co% RH; 200C)
in g / m2
(2) breaking in daN / S cm in the warp direction
(3) breaking in daN / S cm in the weft direction
(4) The values shown are in agreement with
those given in the literature
or who are commonly recognized
(D1) Combed Egyptian cotton jeans 38.5 x 26.5
Nm 34/34
(D2) Combed Egyptian Cotton Jean 37 x 20.5
Nm 34/40
(D3) Combed Egyptian Cotton Jean 38.5 x 24
Nm 34/40
The example fabrics 1A, 1B and 1C) according to the invention were then subjected to different treatments.

(d) Drawing
The aim of the stretching operation is to reduce the clogging of the wires and consequently to increase their resistance to elongation. The fabrics according to the invention were immersed in an aqueous bath maintained at about 75850C where they are stretched. According to a feature of the invention, a drawing bath is used in which there is substantially no desizing. Also advantageously, said drawing bath may contain a coloring means.

 In the present example, the aqueous drawing bath responded to Formulation II below.

FOBMULATION II - water ............................ 1000 parts by weight - dye dye brown-black
provided under the reference
"CORIACIDE" by the so-called society
HERE) 175 parts by weight - wetting agent (of the type
alkylphosphate) 100 parts by weight - bath temperature ............ 75-850C.

 After impregnation, each woven fabric was expressed and dried in a stretched state on a heating cylinder at 175 ° C. and at a linear tension of 60 kg / 40 cm in width.

(e) First coating
A first coating was then carried out on the so-called weft side of each woven fabric (1A, 1B and 1C) according to the invention, for the offset of a pre-primer (in English: "presize") of a binding composition. In practice, this pre-primer on the woven side of the woven fabric ensures the connection between the woven fabric and the future "bonding layer" binding the abrasive means.

In the present example, the pre-primer, which was applied on the side of the weft threads, corresponded to the formula III below, so as to make a deposit on the top of the fabric (in English: "front-filling ").

FOROLATION III - thermosetting resin (from
50% formophenolic type
of dry extract in water) 150 parts by weight - latex (styrene butadiene type) 850 parts by weight - antifoaming agent (of the type
silicone) 2 parts by weight - thickening agent (emulsion
anionic) ll parts by weight.

 The pre-primer composition was applied to the rake at a viscosity of 3500-5000 cP (i.e. 3.5-5 Pa.s) and dried at 135 ° C. to give a solids deposit of 50 + 5 g / m2.

(f) Second coating
On the untreated side (ie chain side) of said fabric (example 1A, 1B or 1C) provided with said pre-primer, a second coating (in English: "back-filling") was carried out using a composition corresponding to formulation IV below.

FORN (JLÂTION IV - latex (styrene type)
butadiene) 10,000 parts by weight - antifoaming agent (silcone) .... 20 parts by weight - dye supplied under the reference
"CHLORAZOL BLUE GD LIQUID"
by the company called ICI) ... 3 parts by weight.

 The coating composition on the chain side was applied by means of a cylinder, so as to obtain, after drying at 110 ° C., a solids deposit of 18-22 g / m 2.

 In Table III below, part of the results of the tests undertaken to record the mechanical properties of the abrasive supports applied according to the invention after "front-filling" and "back filling" were recorded.

 These supports thus obtained are then treated, as indicated above, to receive the abrasive material by means of (i) the "bonding layer" and, where appropriate, the "bonding layer", or (ii) the adhesive mass mixture abrasive material.

TABLE III

<tb> Properties <SEP> Ex <SEP> 1A <SEP> Ex <SEP> 1B
<tb> adhesion <SEP> (a) <SEP> 10-12 <SEP> 8-10
<tb> weight <SEP> (b) <SEP> 257 <SEP> 235
<tb> rupture <SEP> (c)
<tb><SEP> string <SEP> 170 <SEP> 120
<tb><SEP> frame <SEP> 75 <SEP> 50
<tb> lengthening <SEP> (d)
<tb><SEP> chain <SEP> 6.5 <SEP> 6.5
<Tb>
Note (a) measurement of the force required to delaminate
pre-primer layer of the cut fabric tested
in strips 5 cm wide; membership is expri
here in daN / S cm (b) weight in g / m2, in the conditioned state [OZ HR; 200C] (c) breaking force expressed in daN / S cm, in the state
conditioned [65 Z RH; 200C] (d) elongation expressed as a percentage under a force
90 daN / s cm in the warp direction, in the con
packaged [65% RH; 200C].

EXAMPLES 2-6
Proceeding as indicated in Example 1, replacing the 1/1 weight ratio PE / MF composite yarn by composite yarns of different weight ratios, examples were prepared for each example of fabric-like abrasive backing cloths of the examples 1A, 1B and 1C, according to Table IV below.

TABLE IV

<tb> Examples <SEP> Report <SEP> Weight <SEP> PE / MF
<tb> 2A, <SEP> 2B, <SEP> 2C <SEP> 65/35
<tb> 3A, <SEP> 3B, <SEP> 3C <SEP> 60/40
<tb> 4A, <SEP> 4B, <SEP> 4C <SEP> 40/60
<tb> 5A, <SEP> 5B, <SEP> 5C <SEP> 35/65
<tb> 6A, <SEP> 6B, <SEP> 6C <SEP> 30/70
<Tb>
The abrasive carriers of Examples 2-6 have suitable mechanical properties with respect to flexibility, surface condition, and tensile strength compared to conventional coated Egyptian coated abrasive media. However, they are less interesting with respect to said mechanical properties than coated abrasive media made with PE / MF composite yarns having a 1/1 weight ratio according to Example 1 above.

EXAMPLES 7-8
Using the procedure given in Example 1, but modifying the weaving conditions, abrasive carriers were prepared according to weight classes X (about 240 g / m 2) and Y about 280 g / m 2).

Claims (29)

A polyester / viscose composite yarn for soft fabric coated with an abrasive means, said composite yarn being characterized in that it consists of a blend of (1) fibers of a viscose component, and (2) fibers of a polyester component, and in that it has a basis weight of less than or equal to 350 g / m2. Polyester / viscose composite yarn according to claim 1, characterized in that said viscose component is made of rayon fibers. 3. polyester / viscose composite yarn according to claim 1, characterized in that said viscose component is made of fibran fibers. A polyester / viscose composite yarn according to any one of claims 1, 2 and 3, characterized in that it comprises (1), as a viscose component, 35 to 70% by weight of viscose fibers, and (2), as a polyester component, 65 to 30% by weight of polyester fibers. 5. Composite polyester / viscose yarn according to claim 4, characterized in that said viscose component which it contains has, in the conditioned state of 65% relative humidity and at 200 ° C., a breaking strength greater than or equal to at 25 cN / tex. The polyester / viscose composite yarn according to claim 4, wherein (1) the viscose component is viscose fibers having a cutting length of 32-40 mm and a linear density of 1.3-1.7 dtex, and (2) the polyester component consists of polyester fibers having a cutting length of 25-50 mm and a linear density of 1.3-1.7 dtex. A polyester / viscose composite yarn according to any one of claims 5 and 6, characterized in that it has, in the conditioned condition of 65% relative humidity and 200 ° C, (i) a metric value. greater than or equal to 28 m for 1 g of yarn, and (ii) a fracture toughness greater than or equal to 20 cN / tex. The polyester / viscose composite yarn according to claim 1, wherein the weight ratio of the polyester component to the viscose component is about 1/1. 9. Fabric characterized in that it comprises at least 25% by weight of composite yarns according to claim 1. The fabric of claim 9, wherein the viscose component of the composite yarns is rayon fibers and wherein the weight ratio of the polyester component to the viscose component is about 1/1. 11. Fabric according to any one of claims 9 and 10, characterized in that it is selected from the group consisting of non-woven fabrics, woven textiles and knitted fabrics. 12. Fabric according to claim 11, characterized in that it is a woven fabric in which the warp son are constituted by said polyester / viscose composite son and the weft son are made of polyester son or cotton. 13. The fabric of claim 11, characterized in that it is a woven fabric in which the warp and weft son consist of said polyester / viscose composite yarns. 14. Fabric according to claim 11, characterized in that it consists of a woven fabric having a dry weight less than or equal to 350 g / m2. 15. Fabric according to claim 11, characterized in that it consists of a woven fabric having a dry weight of 260-300 g / m2. 16. Fabric according to claim 11, characterized in that it consists of a woven fabric having a dry weight of 220-260 g / m2. 17. Fabric according to claim 11, characterized in that it consists of a woven fabric having a dry weight of 80-220 g / m2. 18. Use of a fabric according to claim 9 as an abrasive composite material carrier. 19. A process for the preparation of a carrier of abrasive material, said method being characterized in that it comprises the steps of  (a) use a glued woven fabric  selected from the group consisting of  woven fabrics comprising at least 25% by weight  of polyester / viscose composite yarns next  any one of claims 1 to 8; and,  (b) wet stretching said woven fabric  containing said polyester composite yarn  / viscose without substantial desizing, then  drying said stretched fabric thus obtained,  a temperature of at least 900 C and preferably  from 110-2000 C. The method of claim 19, further comprising the step of  (c) coating said fabric, thus dried, on  least one of its faces with a material  softwood suitable for a surface coating. 21. The method of claim 19, wherein in step (a), the viscose fibers of the viscose component are substantially rayon fibers. 22. A process according to claim 19, wherein in step (a), the weight ratio of the polyester component to the viscose component is about 1/1, the viscose fibers being fibrous fibers. 23. A process according to claim 19, wherein in step (b) the wet drawing is carried out by passing said polyester / viscose woven fabric in an aqueous bath at a temperature of about 150 to about 1000 C, and under a load of 10 to 100 kg / 40 cm width. 24. The process of claim 23, wherein said aqueous bath contains a coloring agent. 25. The process according to claim 19, wherein in step (b) the drying is carried out at a temperature of at least 900 ° C, and preferably at a temperature of 110-200 ° C. 26. The method of claim 20, wherein, in step (c), said surface coating is performed so as to obtain a recovery in dry weight of 10 to 150 g / m2 on at least one side. The method of any one of claims 19 and 20, wherein in step (a), the woven fabric containing said polyester / viscose composite yarns is sized according to the warp yarns, and has resistance to machine direction fracture greater than or equal to 70 daN / s cm in conditioned condition of 65% relative humidity and 200c. 28. Support for abrasive material, characterized in that it is obtained according to the method of claim 27, and in that it has an elongation in the machine direction of less than or equal to 8%, under a load of 90 daN / 5 cm wide, in the conditioned state of 65 Z relative humidity and 200C. 29. Support according to claim 28, characterized in that it has a machine direction elongation less than or equal to 6.5% under a load of 90 daN / S cm, in the conditioned state of 65% humidity relative and 200C.