FR2752248A1 - NON-WOVEN ABSORBENT COMPLEX MATERIAL COMPRISING A SOFT FACE AND A ROUGH FACE AND METHOD FOR OBTAINING THE SAME - Google Patents

Abstract

Absorbent nonwoven complex material comprising a flexible face and a rough face, consisting of at least two superimposed fibrous layers, linked together by interpenetration of the fibers in the direction of thickness and in which: - the first layer is made for all or part of hot-melt synthetic fibers preferably selected from the class of polyolefins; - The second ply is, for its part, made of natural and / or artificial and / or synthetic fibers that are comparatively thin compared to the synthetic fibers of the first ply and having a higher melting point than the latter; - the association of the elementary plies is carried out by subjecting them to a treatment making it possible to reorient the synthetic fibers of the first ply so that, on the one hand, they are intimately linked in the structure of the second ply and, on the other hand , has free ends or loops visible on one of the outer faces of the complex formed.

Description

ABSORBENT NON-WOVEN COMPLEX MATERIAL COMPRISING

  A FLEXIBLE FACE AND A ROUGH FACE, AND A METHOD FOR

ITS OBTAINING

  Today, many products for domestic use, clothing, hygienic, medical, industrial ... materials-based

  fibrous, are made from so-called "non-woven" textile structures.

  Among these articles, in addition to wiping materials in the form of relatively thin sheets, comparable to paper, but having very high absorption properties, it has been proposed to make real sponge substitutes whose dimensions (length, width and especially thickness), may vary within wide limits depending on the intended use. As an indication, the thickness may be of the order of a few tenths of a millimeter when a wiper is made to achieve a centimeter or even more for articles of the "sponge" type, the weight may be, as for him, vary from

g / m2 to 200 g / m2, or even more.

  To produce these articles, one uses one of the three techniques for obtaining nonwovens, namely either the so-called "dry technique" which consists of producing a fiber web mechanically or aerodynamically, using machines conventional textiles such as openers, cardes ..., or the so-called "wet" technique, a technique derived from the conventional manufacture of paper, which consists in producing a suspension of fibers that is received in the form of a sheet or the so-called "melt" technique of making a web of synthetic continuous filaments randomly oriented relative to each other, and directly at the exit of the dies

extruding said filaments.

  It has long been proposed to use these technologies to produce multilayer articles, so as to have different properties on both sides of the formed sheet, for example a printable or impermeable face and the other fibrous face, or a impervious face and another face having a great power of absorption. The present invention relates to a new type of absorbent nonwoven complex which has the essential feature of having a

  soft face, the other face being rough.

  In general, this complex material consists of at least two superimposed fibrous webs, interconnected by interpenetration of the fibers in the direction of the thickness and in which - the first web is made up of all or part of synthetic fibers hot melt materials preferably selected from the class of polyolefins; advantageously, this sheet consists of a mixture of cellulosic or other fibers and of hot melt synthetic fibers, the percentage of these latter in the sheet being greater than 30% and preferably greater than 50%; - The second layer is, in turn, made of natural fibers and / or artificial and / or synthetic comparatively thin compared to the synthetic fibers of the first sheet and having a higher melting temperature than the latter; the association of the elementary layers is carried out by subjecting them to a treatment making it possible to re-orient the synthetic fibers of the first layer so that, on the one hand, they are intimately linked in the structure of the second layer and, on the other hand, on the other hand, have free ends or loops apparent on one of the outer faces of the formed complex. The way in which elemental layers are associated will be function

the nature of said webs.

  By way of indication but not limitation, this combination may, for example, be carried out as follows: for example in the case where the two elementary layers are obtained according to the so-called wet or paper-making technique, their production will be carried out on a machine for obtaining and superimposing two jets each corresponding to one of the layers; in this case, the superposition will be in line, even before drying, and will be complexing by the action of jets of water under pressure; - In the case where the two elementary webs are obtained by the so-called dry technique, also called textile, they will also be superimposed and their connection will be obtained by a treatment of intermingling by jets of water; - Finally, in the case where a complex is made from two sheets obtained by different techniques, it will be possible to lightly prelate one or other of the layers by entanglement obtained by means of water jets avoiding blocking bonds of the chemical or thermal type; the two layers are then superimposed and linked by

entanglement by jets of water.

  Advantageously and in practice, according to the invention - the synthetic fibers used in the composition of the first sheet and which make it possible to produce the scratching surface of the article, are preferably polypropylene or polyethylene fibers: the title of which is higher 5 dtex, the upper limit being directly related to the pressure of the entangling fluid so as to ensure the solidarity of the fibers with the rest of the sheet; the upper limit of the fibers will depend on the commercial availabilities which, to date, propose fibers with a 17 dtex titre; 30. the length of which is greater than 5 mm, the upper limit being essentially dependent on the manufacturing technique; thus, a finer title results in the use of shorter fibers and the wet technique requires a shorter cut than the dry technique; whose surface is the least round possible; thus, multilobal fibers, fibrillable or flattened section, which are much more receptive to the action of the jets of the entangling fluid, are preferably used; if it is preferable to use polyolefin fibers having the characteristic of having a density of less than 1, it may however be envisaged to use other types of fibers, for example fibers made of a copolymer of vinyl chloride (85%) and vinyl acetate (15%) having a melting point of 160 C with a density of 1.37 g / cm3; as cellulosic fibers, it is possible to use any type of fiber making it possible to obtain an absorbent nature, such as wood pulp, cotton, linters, viscose; in the case of a chemical fiber such as viscose, it will optionally be of multilobal or fibrillable section so as to optimize the action of the fluid jets; if synthetic synthetic fibers are introduced into the second ply, they will have a melting point higher than those entering the composition of the first ply; for example, polyester or polyamide 6.6 (preferably polyamide 6), possibly curled, fibers will be used; - it is possible to add possibly in one or the other of

  a certain percentage of so-called binder fibers, for example fibers

  componantes, all or part of the fiber flue on neighboring fibers during a heat treatment to achieve a "collage" making the fibers integral; in such a case, the melting point of the binder portion of these binder fibers will be less than the melting point of the above-mentioned structural fibers, but it may however be lower or higher than that of the fibers of the first ply intended to provide the scratching effect; after superposition of the two layers, the resulting complex receives a heat treatment intended, on the one hand, to reveal the binding power of the binder fibers which may have been introduced, and on the other hand and, above all, to fuse the free ends of the fibers. synthetics of the first web so as to amplify the "scratching" effect; before or after heat treatment, it is optionally possible to carry out additional mechanical treatments, such as, for example, creping or use of a Micrex type apparatus intended to soften the product or chemical, such as 10. additions of polymeric emulsions of latex type intended to mechanically reinforce the product, addition of chemical softeners, addition of hydrophilic agents, impregnation of degradant liquids (washing-up liquid type),

  skin protectors, stain removers ...

  The respective grammages of the two layers are adapted according to the applications, these weights may range from 15 to 200 g / m 2 for the layer intended to form the flexible face and from 10 to 70 g / m 2 for the layer.

  intended to form the rough surface.

  The invention also relates to a method for producing such a product, said method consisting in producing two layers of elementary fibers, the two layers being bonded to one another downstream of the formation zone by a needling jet treatment. fluid acting at least against the surface of the web comprising the hot melt fibers intended to constitute the "scratching" side of the article

complex formed.

  For the implementation of such a method, it is possible to use, for example, a conventional machine for obtaining a wet nonwoven, for example a machine of the Hydroformer type from the VOITH Company, at the exit of which is disposed a hydraulic binding assembly, also of known type, for example a machine jet water jet treatment jet-type "Jet Lace" Company ICBT-PERFOJET, this machine being set so that the jets act preferentially on the face of the multilayer material constituted by the sheet which comprises the hot melt synthetic fibers, which allows to reorient said fibers in the Z direction of the sheet and somehow to "file" inside the latter. When the two elementary layers are made wet, their association is obtained on the drip sheet before

fluid jet treatment.

  It may also be envisaged to produce the second layer by the dry route, the association being formed at the exit of the formation of this layer by relating to its surface, on the side where the action of the fluid jets will be exerted. interlacing, the first veil made wet or dry. In such a case, the two superposed layers are preferably remoistened before subjecting them to the action of the entangling jets. After completion, the nonwoven complex formed is dried and then optionally impregnated with chemical binders of acrylic base (optionally copolymerized), ethylene-vinyl acetate, polyurethane, and various adjuvants for reinforcing properties.

  specific ones such as hydrophilicity, flexibility.

  After drying, it is preferably carried out on the same machine, a heat treatment to cause partial melting of the ends of the chemical fibers of the upper layer which remain connected to the base nonwoven complex, the melted ends increasing and

magnifying the effect of roughness.

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  The invention and the advantages that it brings will however be better understood thanks to the exemplary embodiments given below as indicative

but not limiting.

  These examples are made on a conventional papermaking machine of the Hydroformer VOITH type, adapted to comprise two separate suspension inlets and thus making it possible to produce

a multilayer sheet.

  At the exit of this machine, an installation is arranged

  fluid-jet interlacing marketed by ICBT-

  PERFOJET under the name JET-LACE, this machine having four rows of injectors for subjecting the complex to the action of jets / needles obtained from water under pressure between 10 bar and 125 bar. The number of jets / needles per meter of width of each row may vary from 800 to 1700 and is advantageously of the order of 1000, the diameter of each injector orifice being generally between 100 and 140 microns, but possibly reach

a value of 300 microns.

Example 1

  On a papermaking machine of the aforementioned type, a nonwoven complex according to the invention is produced from two fibrous suspensions having the following compositions - for the upper layer which will subsequently be subjected to the preferential action of the needling jets, and which constitutes globally 23% of the total fibrous mass of the complex after formation, a suspension of a mixture comprising:% polypropylene fibers (6.7 dtex title, 6 mm section, round section); these fibers are dyed in the mass, which allows, in the final product, to identify

  visually the different layers of the finished product.

  % of cellulosic fibers made of paper fibers

  long ones obtained from Scots pine.

  for the lower layer forming the second flexible and advantageously absorbent sheet, and which generally constitutes 77% of the total fibrous mass in the final complex, a suspension comprising: 67% of long cellulosic fibers obtained from Scots pine, 33% of 1.7 dtex polyester fiber - 18 mm section - section

round.

  The two plies are superimposed so that the ply comprising the polypropylene fibers is at the top and, before drying, the complex is subjected to an entanglement action by jets of water, the four successive series of jets being obtained from water under increasing pressure ranging from 23 bars for the first, 27 bars for the second, 55 bars for the third and also 55 bars for the fourth. The action of the jets of water modifies the initial position of the fusible and stiff fibers which, initially, are located perfectly in the plane of the sheet, said fibers being re-oriented along the Z axis of said sheet and their end rising under the effect of entanglement knots, or even for the longest fibers forming loops between

entanglement knots.

  The complex is then dried and is subjected to heat treatment inside a tunnel heated to 400 C (the temperature of

  burner in the case where the fused fibers are polypropylene type).

  This heat treatment results in a partial melting of the apparent polypropylene fibers on the surface of the sheet making the latter abrasive by droplet formation at the site of the melting. Although the effective temperature inside the furnace is 190 ° C., that is to say greater than the melting point of the polypropylene, the speed of passage of the ply inside the furnace is such that the fibers they only partially melt the other synthetic fibers (excluding any binder fibers) used in the composition of the complex, which in turn are not affected by this heat treatment, thus making it possible to maintain the flexibility of the article. As an indication, the speed of passage of the web inside the oven is of the order of 90 m / min, said furnace having an "effective" length of six meters, the nonwoven being previously

  preheated to a temperature of 140 C.

  Of course, these temperature and speed values are not limiting since a higher speed can be compensated for by a longer oven working length, or a higher temperature and another type of fiber will require a higher temperature.

  adaptation of the selected temperatures.

  At the output of the machine, a sheet weighing 40 g / m 2 having a soft and absorbent face is obtained, the other side of which has abrasive properties consisting of the visible ends of the polypropylene fibers. It should be noted that the choice of polyolefin fibers to constitute the scratching apparent face of the article, facilitates obtaining the latter because during the suspension to form the web, said fibers having a density less than 1 stay on the surface during the

wet conformation.

  Depending on the desired applications, this sheet can be used either to receive a complementary treatment in line with a binder, in this case a polymer emulsion

  acrylic / vinyl acetate deposited at a rate of 10 g / m2.

  The characteristics and properties of the tablecloths obtained are

  grouped in the table below.

WITHOUT IMPREGNATION WITH IMPREGNATION

  Weight (g / m2) 40.3 50.7 Thickness (microns at 100 kPa) 268 261 Permeability (L / m2 / S at 196 Pa) 1335 1103 Longitudinal break (N / M) 470 1439 Break through (N / M) ) 170 470 Length elongation (%) 2.5 12.3 Crosswise elongation (%) 5.5 30.0 Moisture outflow (N / M) 109 952 Moisture cut through (N / M) 48 286 Tear length ( cN) 118 525 Tear through (cN) 198 1152 Stiffness in long direction (cN Handle O meter 45 80 Stiffness through (cN Handle O meter) 17 27 Absorption capacity (%) 693 477 Measurements of product characteristics are performed in

the following conditions.

  Weight: according to EDANA 40.3-90 method Thickness according to AFNOR method NF Q 03 + 016 Permeability: according to EDANA 140.1-81 method Rupture: according to EDANA method 20.2 - 89 modified distance between teeth: 127 mm pulling speed: 25.4 mm / min Elongation: according to EDANA method 20.2 - 89 modified distance between workpieces: 127 mm pulling speed: 25.4 mm / min 1i 1 2752248 detection at 75% of the maximum rupture Wet failure: following the same method as dry failure tests 10 min under mm of distilled water at 20 C Tearing: according to EDANA 70.3 - 96 Rigidity: with "HANDLE-0-Meter" apparatus

  Absorption capacity: according to EDANA 10.2 - 96 method.

  It can be seen from the preceding examples that the non-impregnated product has a greater absorption capacity, is much more flexible, and on the other hand has relatively low mechanical characteristics which, if necessary, could be compensated by the introduction of a certain

  percentage of thermoling fibers, as indicated previously.

  Such products are particularly suitable for producing semi-pickling or highly absorbent wiping products, but could also be used in other fields, for example in the food industry, for solvent media, laboratory benches. The same product impregnated with a polymer binder is particularly suitable for: * wiping with dishwashing detergent for single use (camping ..), * towels impregnated with degreasing and softening agents for manual workers (garages ..), * wipers impregnated with a liquid suitable for vehicles (crushed insects, bird droppings), the domestic .., * wiping for do-it-yourselfers (cleaning of balustrades,

dedusting outdoors ..).

Example 2

  A complex material according to the invention is produced by combining, on the one hand, a nonwoven obtained by wet process, and on the other hand

  on the other hand, a nonwoven obtained by the dry method.

  The nonwoven obtained by wet process, made on the same machine as the previous example, comprises only one jet, forming

  in the final product about 50% of the total mass of fibers.

  This sheet is obtained from a fibrous suspension comprising: 33% of polypropylene fibers, of 6.7 dtex title, 6 mm section, round section;

  - 67% cellulose (wood pulp) - long fibers (resinous).

  This first ply is reported, before treatment by the set of fluid jets on a card web, constituting 50% of the total weight of fibers, a web consisting of polyester fibers having a title of 1, 7 dtex, curled, and a cut 38 mm. This card web is preferably previously slightly entangled by jets of water for

  ensure its cohesion and facilitate its handling.

  The card web is located below the wet web, the assembly being remoistened before being subjected to the action of the

  entanglement jets made in the same manner as in Example 1.

  After completion of the complex, the product is, as in the preceding example, subjected to a heat treatment resulting in a partial melting of the polypropylene fibers, making the surface o they

are present abrasive.

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  We obtain a complex product whose characteristics are

  grouped in the table below.

  Weight 68.4 g / m2 Thickness 255 microns at 100 kPa Permeability 1160 L / m2 / S at 196 Pa Longitudinal break 1920 N / M Break through 690 N / M Longitudinal stretch 29% Longitudinal stretch 30% Wet outflow 1600 N / M Wet through 550 N / M Longitudinal tear 1330 cN Tear through 2810 cN Stiffness long 31 cN (Handle-O-Meter) Stiffness through 5 cN ("" ") Absorption capacity 402% Such a product that comprises a flexible face consisting of polyester fibers and a rough face, is particularly suitable for use as various wiping materials in a manner similar to those mentioned in Example 1, and which have greatly improved flexibility. understood, the invention is not limited to the embodiments described above, but it covers all

  variants made in the same spirit.

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  Thus, it is possible to treat the product to incorporate various additives, for example surfactants, such as the alkyl sulfonates commonly used in dishwashing liquids, such as

  products being either added alone or in admixture with a binder.

  It might also be considered to add fabric softeners,

  degreasers, insecticides, bactericides, flame retardants, solvents.

  If the polypropylene is particularly suitable for producing the scratching surface of the article, it is also possible to use polyethylene fibers, or even possibly other fibers such as fibers derived from polyvinyl chloride whose melting point makes it possible to carry out a treatment. without damaging the characteristics of the fibers involved in the constitution of the complex. The choice of polypropylene as a particularly suitable material for the implementation of the invention is explained by the fact that at the date of this application, it is the product that has the best price / properties ratio ( solvent resistance, rigidity, abrasiveness, skin contact

and food).

  In addition, it could possibly envisage producing products much higher than those indicated in

above description.

  Finally, the web constituting the flexible layer preferably absorbent, will be made of selected fibers according to the characteristics primarily sought. As an indication, when it is desired to have a flexible and highly absorbent face, it is preferable to use viscose or cotton, if an article having a good tear strength is envisaged, the polyamide fiber will preferably be used and, if we want to improve the touch, we will use

  preferably acetate or cellulose fibers (artificial silk).

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Claims (9)

  1 / Absorbent nonwoven complex material comprising a flexible face and a rough face, consisting of at least two superposed fibrous layers, interconnected by interpenetration of the fibers in the direction of the thickness and in which: the first ply is constituted for all or part of synthetic hot-melt fibers preferably selected from the class of polyolefins; - The second layer is, in turn, made of natural fibers and / or artificial and / or synthetic comparatively thin compared to the synthetic fibers of the first sheet and having a higher melting temperature than the latter; the association of the elementary layers is carried out by subjecting them to a treatment making it possible to re-orient the synthetic fibers of the first layer so that, on the one hand, they are intimately connected in the structure of the second layer and, on the other hand, has free ends or loops apparent on one of the outer faces of the formed complex. 2 / material according to claim 1, characterized in that the first web consists of a mixture of cellulosic or other fibers and hot melt synthetic fibers, the percentage of the latter in the web being greater than 30% and preferably greater at 50%.   3 / Material according to one of claims 1 and 2, characterized in that   that the synthetic fibers used in the composition of the web to make the scratching surface of the article, are fibers of   polypropylene or polyethylene.   4 / Material according to claim 3, characterized in that the fibers   have a titre greater than 5 dtex for a length greater than 5 mm.   Material according to one of Claims 1 to 4, characterized in that   that cellulosic fibers to obtain the absorbency   are papermaking fibers, viscose fibers ...   6 / Material according to one of claims 1 to 5, characterized in that   that the synthetic fibers used in the composition of the second layer and which make it possible to obtain the flexible face of the article, are polyester or polyamide fibers, optionally crimped, having a melting point higher than those used in the composition of the first tablecloth.   7 / Material according to one of claims 1 to 6, characterized in that   that the complex receives an additional treatment, such as creping, treatment with wetting agents to improve its hydrophilicity, impregnation with a more or less aggressive liquid such as as dishwashing liquid.   8 / Material according to one of claims I to 7, characterized in that   that the grammage of the layer forming the flexible face is between 15 and 200 g / m 2 and that of the layer forming the rough surface is included between 10 to 70 g / m2.   9 / Process for obtaining a material according to one of   Claims 1 to 8, characterized in that two layers of   elementary fibers, the two layers being bonded together downstream of the formation zone by a fluid jet needling treatment acting at least against the surface of the web comprising the hot-melt fibers intended to constitute the "scratching" face of the Article complex formed.   / Method according to claim 9, characterized in that the two elementary layers are made by wet process, their association   being obtained on the dewatering mat before treatment by jets of fluid.   11 / A method according to claim 9, characterized in that the layer intended to form the flexible face is obtained by the technique called "dry route", the association of the two elementary layers being formed at the exit of the formation of this layer by dry route by relating to its surface, on the side where will be exerted the action of interlacing fluid jets, the first veil made wet, the two superimposed layers being preferably remoistened before subjecting them to action of the entanglement jets.   12 / Method according to one of claims 9 to 11, characterized in that   after interleaving, the nonwoven complex formed is dried and receives a complementary heat treatment to cause the partial melting of the ends of the chemical fibers of the upper layer which remain bonded to the base nonwoven complex, the molten ends increasing the effect of roughness.