FR2774869A1 - SHEET STRUCTURE THAT CAN BE USED AS A SUPPORT FOR A STACK OF ETOFFES ON A MAKING LINE AND PROCESS FOR OBTAINING IT - Google Patents

Abstract

The invention concerns an air permeable paper sheet as support element for a layer of fabrics (mat) on a production line in particular during the cutting phase. The invention is characterised in that said sheet has in its thickness pores or fine perforations distributed over the whole surface thereof, said sheet having a bulkiness or hand more than 2.5 cm<3>/g, enabling it to allow air to pass through by the suction effect produced from beneath its lower surface.

Description

] SHEET STRUCTURE USABLE AS A SUPPORT ELEMENT

OF A STACK OF ETOFFES ON A CONFECTION LINE AND PROCEDURE FOR OBTAINING IT.

TECHNICAL FIELD The present invention relates to the technical clothing sector and relates more particularly to a new type of sheet support used as a conveyor / conveyor element of a mattress made up of a plurality of superimposed textile layers and which is intended for be cut in the form of panels

elements of appropriate shape which are subsequently assembled together to produce the final product such as a garment.

PRIOR ART In the field of clothing, it has been proposed for a very long time, as emerges in particular from FR-A-2 194 823 (corresponding to US 3,495,492) to produce mattresses from textile structures (fabrics, knits ) intended to make the finished article, mattresses which are transferred to a table

cutting.

During this operation, the fabric mattress is placed on a support permeable to air and the cutting into elementary panels is obtained by creating a

depression below said table, so that the stack is kept perfectly flat during the cutting phase.

To avoid any displacement of the elementary layers with respect to each other, and as emerges in particular from the aforementioned FR and from FR-A-2 030 792 (corresponding to US 3,495,492), the mattress is covered at its upper part by a plastic film, impermeable to air, which makes it possible to densify said mattress

at the time of the cutting phase and avoids any displacement of the elementary layers with respect to each other.

Concerning the supports permeable to air which are used to support and transfer the mattress made up of continuous textile sheets to the cutting station, various solutions have been proposed.35 Thus, in FR 2 030 792, the support consists of a layer of material in which the tool can penetrate and which has channels or passages, which allows, the vacuum exerted below the stack, to exert a suction action tending to press the material against the support table. Nowadays, the most widely used solution consists in placing relatively rigid papers underneath the stack, perforated by stamping or scratching, which have the essential advantage of being relatively inexpensive.10 One of the problems which arise with such supports therefore comprising channels or orifices allowing the flow of air, lies in the fact that

the suction is not evenly distributed over the entire surface of the mattress and in some cases there may therefore be irregular "densification" which can lead to defects in the cut panels.

In addition, the production of the perforations is necessarily carried out subsequent to the manufacture of the paper and therefore results in the production of waste.

Disclosure of the invention The object of the invention is to provide a paper sheet which can be used as a support element for a stack of fabric on a production line, in particular as a support during the cutting phase which, not only, either inexpensive to manufacture but also and above all, facilitates the compaction of the stack under the action of the suction exerted during this cutting phase, ensures good sliding when placing said mattress on the table, avoids the marking of the textile structure, in particular when it is a light structure, and finally is practically usable for any type of textile structure. As a paper sheet making it possible to produce such a support, a paper sheet will be used , which has in its thickness pores or fine perforations distributed over its entire surface, said sheet having a "bulk" or "hand" expressed in cubic centimeters per gram, greater than 2.5, making it suitable for r the passage of air under the effect of a suction produced below its

lower side.

According to a first embodiment, the sheet structure has pores uniformly distributed over its entire surface, said pores having a diameter of less than one millimeter and preferably between 50 and 150 microns. According to a second embodiment, the pores or fine perforations are distributed in the form of patterns comprising a central zone with high permeability to

air surrounded by a denser fibrous zone with lower permeability.

Finally, according to a last embodiment, the pitch between the centers of two consecutive patterns is less than 5 mm and preferably less than 3 mm, the area

High permeability core is free of fibers and has a total area of the order of 1 to 2 mm / 2.

The invention also relates to a process for obtaining a paper sheet which can be used as a support element for a stack of fabric on a production line, which consists in producing a filtering paper directly on a papermaking machine, without any particular adaptation, characterized in. in that when obtaining said paper: - during the preparation of the pulp, the cellulose fibers (wood pulp) are individualized without over-refining them in order to maintain the maximum permeability; - Said dough is brought to the machine at a very low concentration of less than one gram per liter, which makes it possible to obtain a puffy sheet and; - It is advisable to avoid, in the wet part of the machine, elements such as "presses" which have the effect of compressing the sheet and reducing its permeability. Preferably, according to the invention, the permeability is maximized by subjecting the produced paper sheet, before its drying, to a textilization treatment which consists in locally displacing the fibers by means of jets or blades of fluid through a coarse-textured canvas or a perforated cylinder of the cylinder type. rotary printing of the serigraphic type, so as to form patterns comprising a central zone of high air permeability surrounded by a zone with

lower permeability.

In such a case of a textilization treatment, the latter may result in either leaving only a small amount in the central part.

minority of fibers, or possibly not achieve a true perforation5 free of fibers.

Such a treatment can be carried out on machines of known type, for example of the type which is the subject in particular of FR-A-2 625 937.

Optionally, to improve the tear resistance of the paper, it may be considered to incorporate synthetic or artificial fibers into the cellulosic pulp, at a rate of 5 to 25%, the incorporation of such fibers also having an effect. additional aerator of the sheet and, as a result of improved permeability. 15 It was found that an incorporation of less than 5% did not provide any significant influence and that if this contribution was greater than 25%, of on the one hand, the manufacturing costs were significantly increased and, on the other hand, and above all, it is then essential to use additional binders. Finally, in a manner known in the papermaking field, it may be envisaged to incorporate an additional binder, in an amount of the order of 5 to 25%, which makes it possible to produce a chemical bond improving the mechanical characteristics. It could possibly be envisaged to use less than 5% of additional binders, but then the mechanical characteristics are practically not improved. Above 25%, the costs are significantly increased without noticeable improvement in characteristics. As reinforcing fibers, it is possible to use synthetic fibers such as polyester, polyamide, polypropylene, polyethylene, or even artificial fibers such as

than in viscose or even natural fibers such as linen or cotton for example.

The optional binders will be chosen from the following elements, optionally combined with one another: - conventional polymers also called "LATEX", in particular of acrylic, ethylene vinyl-acetate, vinyl acetate or polyvinyl alcohol type,

styrene-butadiene, ... and their polymers associated by co or ter ...

polymerization; - starch, carboxy-methyl-cellulose, hexa-methyl-cellulose - polyamide or polyamine epichlorohydrin - heat-bonding fibers. Method of Carrying Out the Invention The invention and the advantages it provides will however be better understood by virtue of the exemplary embodiments given below by way of indication, but not limitation, examples in which the characteristics of the paper in accordance with the invention are compared to three samples of conventional perforated papers

referenced respectively Echl, Ech2, Ech3.

These examples are illustrated by the appended figures in which: FIGS. 1, 2 and 3 are reproductions, on a scale of 1, of three conventional perforated papers; - Figures 4 and 5 are respectively reproductions of a sheet structure in which the pores are distributed uniformly over the entire surface of said sheet (Figure 4) and of a sheet structure having received a textilization treatment ensuring a reorientation of the fibers (figure).

Example 1

A paper in accordance with the invention which can be used as a support element for a stack of fabrics on a production line is produced from a conventional paper composition consisting of 77% of unbleached Kraft pulp of southern pine type, and

8% unbleached fluff dough.

On the circuit, a sufficient supply of water is made to obtain a dilution

final less than 1 g / liter, namely in the present case, 0.3 g / liter to ensure the homogeneity of the dispersion of the fibers.

Binders consisting of 5% pregelatinized cationic starch and 10% vinyl acetate latex are incorporated, these binders being incorporated by any technique

conventional such as padding, spraying or printing or "size-press" 5 and in the present case, a "size press".

After drying and crosslinking, the finished product is wound to the width desired by the user and has a structure as shown in Figure 4.

The table below groups together the characteristics of such a product compared to three conventional perforated papers as illustrated in figure 1 (Ech 1), figure 2

(Ech 2) and figure 3 (Ech 3).

Characteristics Unit Invention "Perforated" papers Ech 1 Ech 2 Ech 3 grammage g / m2 45.6 67 84 56 Thickness microns 161 124 16 (89 Main cm3 / g 3.53 1.85 1.9 1.59 Permeability L / M2 / S under 196Pa 30U 112 822 305 Machine direction failure N / M 3252 3726 2898 1762 Cross direction failure N / M2 123 1792 72 73-6 Machine direction elongation% 2.6 1.8 1.3.9 Cross direction elongation 5 2 1 , 4 Machine direction tear Cn 8 198 185 T Cross direction tear Cn T 332 210 T29 Average diameter of the poresmicrons 5U sieurs millimeters It has been observed that during use, as a support element for a stack of fabrics on a line of preparation, that such a paper despite an average permeability of 309 whereas in the control samples, it can sometimes be significantly higher (see sample 2), than in practice, the plating of the stack of textiles on the table of cutting was improved, the cutting being

facilitated.

Such an improvement can be explained on the one hand by the fact that the flow of air produced by the suction source takes place regularly on

the entire surface of the paper through the pores which are evenly distributed over the latter, and that, moreover, this flow is also facilitated by the "hand", significantly higher compared to previous products.

Example 2

A paper sheet which can be used according to the invention as a support for a stack of fabrics is produced by carrying out, before addition of the binder as in Example 1, a textilization treatment by passing through a machine.

conventional treatment by blades or conventional fluid jets of the type marketed by the company ICBT PERFOJET.

To produce such a paper, a paper pulp is used comprising, as in Example 1: * 77% unbleached kraft pulp of southern pine type and;

* 8% unbleached fluff dough.

The whole paste is defibrated / refined at only 15 degrees Schopper-Riegler at about 30 g / liter of water.

As in Example 1, a sufficient supply of water is made on the circuit to obtain a final dilution of less than 1 g / liter, in this case 0.3 g / liter,

which makes it possible to ensure the homogeneity of the dispersion of the fibers.

The still wet fibrous web thus formed receives a micro-perforation treatment by blade or jet of fluid on a conventional installation of the PERFOJET type, with a perforated cylinder or through a fabric with an open structure with a water pressure of 5 to 80 bars. Such a treatment makes it possible to obtain locally a partial or total displacement of the fibers according to the design of the cylinder or the mesh of

the Web. In the present case, the treatment is carried out with a layer of water at 9 bars.

After this operation, binders are added by any appropriate means, padding, spraying, printing or "size press", these binders being based on

of a composition comprising 5% pregelatinized cationic starch and 10% vinyl acetate latex.

After drying and crosslinking, the finished product is wound to the desired width for the intended use having a structure as shown in Figure 5.

The table below groups together the characteristics of such a product compared to three conventional perforated papers.

Characteristics Unit Invention "Perforated" papers Ech 1 Ech 2 Ech 3 grammageg / m2 35.6 67 84 56 Thickness microns 163 124 160 89 Main cm3 / g 4.59 1, T85.9 T1.59 Permeability L / M2 / S under 196Pa 1081 12 822 305 Machine direction failure N / M 177 3726 2898 1762 Cross direction failure N / M 1152 179 78 736 Machine direction elongation% 2, 1.83 0.9 Cross direction elongation% / 6.1 2.2 0.9 1, 4 Machinen direction tear TJ9 T1463 T9 1 () Cross direction tear (CnT6 332 216 1 T 9 Average pore diameter microns T -several mi5imetes Compared to example 1, a paper is obtained which has a significantly higher permeability than previous papers and which, compared to the product produced according to Example 1, makes it even more suitable as a support for a

stacking of fabrics on a clothing line.

Example 3

Example 2 is repeated except that reinforcing fibers are incorporated into the paper pulp.

The aqueous composition comprises 72% of unbleached kraft paste of the southern pine type and 9% of unbleached fluff paste.

The whole pulp is defibrated / refined at only 18 degrees Schopper-Riegler and 5% polyester fibers, 1.7 decitex cut 18 mm are incorporated into it.

The mixture in water is carried out at a rate of approximately 15 to 20 g / liter.

On the supply circuit to the forming fabric, a wet strength agent is added consisting of 0.7% of epichlorohydrin polyamide resin.

Water is added to the circuit in such a way that a final dilution of less than one gram / liter is obtained, making it possible to ensure the homogeneity of

the dispersion of the fibers and which, in this example, is 0.3 g / liter.

The wet fibrous web thus formed is textilized in a manner similar to Example 2, the fluid pressure being 11 bars and the water layer having been replaced by jets of fluid, at a rate of approximately 100 jets / needles per meter of

width making it possible to obtain a structure similar to that of Example 2 and which emerges from FIG. 5.

After textilization treatment, an additional bond is carried out by depositing a composition of 5% pregelatinized cationic starch and 10% of

vinyl acetate latex.

The incorporation of these elements and binders is also carried out in a conventional manner and, after drying / crosslinking, the finished product is

also coiled to the desired width.

The table below groups together the characteristics of such paper compared to conventional perforated papers.

Characteristics Unit Invention "<perforated" papers Scale 1 Scale 2 Scale 3 grammage g / m2 37.4 67 84 56 Thickness microns 160 124 160 89 Mamin cm3 / g 4.28 1.5.9.59 Permeability L / M2 / S under 196Pa644 11 822 35 Machine direction failure N / M 2905 3726 2898 1762 Cross direction failure N / M T1646 1792 7728 736 Machine direction elongation% 2, 1 1.8 1.3 0.9 Cross direction elongation 6.0 2.2 , 9 I, 4 Machine direction tear CN 168 198 T3185 10 Cross direction tear CN 240 332 2 10 129 Average poresmicrons diameter 100 several millimeters

Such a paper is also perfectly suited to serve as a support element for a stack of fabrics on a clothing line.

Compared to previous perforated papers used as supports for stacking fabrics on a clothing line, the proposed paper sheet has many advantages, among which we can cite: the distribution of the pores in the structure being uniform, the risk of dust rise in the textile during the cutting operation is almost zero; 15. in addition, the uniformity of the sheet ensures better glide on the cutting surface without clogging of the latter; with such a sheet being perfectly flat, this virtually eliminates any risk of marking on the surface of the textiles, in particular in the case of fine textiles; By virtue of its uniformity, such a sheet ensures a more homogeneous thickness of the mattress, thereby ensuring better cutting of the textile; the uniformity of the sheet also ensures an overall less thickness due to the absence of bumps and hollows, which makes it possible to consider increasing the number of layers of textile in the mattress and; lastly and above all, it is possible to use such a support regardless of the type of fabric entering into the stack, whereas, previously, it was necessary to use grams of perforated paper having different characteristics. Of course, the invention is not limited to the embodiments described above, but it covers all the variants made in the same

mind.

Claims (5)

1 / Sheet structure usable as a support element for a stack of fabrics on a line for making a paper sheet, characterized in that said sheet has, in its thickness, pores or fine perforations distributed over its entire surface, said sheet having a "bulk>" or "hand" expressed in cubic centimeters per gram, greater than 2.5, making it suitable for allowing the passage of air under the effect of a suction produced below its lower face. 10 2 / sheet structure according to claim 1, characterized in that it has pores uniformly distributed over its entire surface, said pores having a diameter less than one millimeter and preferably between 50 and 150 microns. 15 3 / Structure sheet according to Claim 1, characterized in that the pores or fine perforations are distributed in the form of patterns comprising a central zone with high air permeability surrounded by a denser fibrous zone with lower permeability. 4 / sheet structure according to claim 3, characterized in that the pitch between the centers of two consecutive patterns is less than 5 mm and preferably less than 3 mm, the central zone with high permeability being free of fibers and having a surface total of the order of 1 to 2 mmn / 2.25 / Sheet structure according to claim 4, characterized in that the central zone is free of fibers. 6 / A method of obtaining a paper sheet which can be used as a support element for a stack of fabrics on a production line which consists in producing a filtering paper directly on a paper machine, without special adaptation, characterized in that when obtaining said paper: during the preparation of the pulp, the cellulose fibers (wood pulp) are individualized without over-refining them in order to maintain the maximum permeability; - Said dough is brought to the machine at a very low concentration of less than one gram per liter, which makes it possible to obtain a puffy sheet and; - It is advisable to avoid, in the wet part of the machine, elements such as "presses" which have the effect of compressing the sheet and reducing its permeability. 7 / A method according to claim 6, characterized in that the paper sheet produced is, before its drying, subjected to a textilization treatment, which consists in locally moving the fibers by means of jets or blades of fluid through a coarse-textured canvas or a perforated cylinder of the rotary printing cylinder type, so as to form patterns comprising a central area of high air permeability surrounded by an area of lower permeability. 8 / A method according to claim 6, characterized in that the reorientation of the fibers is such that the central zone of each pattern is free of fibers and has a total surface area of the order of 1 to 2 mm2. 9 / A method according to one of claims 5 to 7, characterized that incorporates into the cellulose pulp synthetic fibers, artificial or natural, thus making it possible to improve the tear resistance of the paper and having a complementary effect of aerating the sheet and consequently improving the permeability. 25 / A method according to claim 9, characterized in that the fibers synthetic or artificial are incorporated at a rate of 5 to 25%. 11 / A method according to one of claims 1 to 10, characterized in that one incorporates into the sheet, during its manufacture, an additional binder thus making it possible to achieve a chemical bond improving the mechanical characteristics. 12 / A method according to one of claims 1 to 11, characterized in that the incorporation of the additional binder is carried out at a rate of 5 to 25%. DEPOSITOR: AHLSTROM LYSTIL SA REPRESENTATIVE: LAURENT & CHARRAS Law Firm