FR2672298A1 - Extrudable composition for forming nonwoven sheets of pressure-sensitive elastomer and composite materials incorporating such a sheet - Google Patents

Abstract

The composition includes an elastomeric polymer and a resin generating an adhesive effect and may also contain a polyolefin. The material in nonwoven sheet form may be a nonwoven web made up of fibres entrained in the molten state. The laminate can be formed by tensioning the material in elastomeric sheet form (3) and bonding at least one web capable of wrinkling (4, 5) (for example a polypropylene web bonded by a centrifugal route) or sheet material under tension (3) by the application of a pressure, the bonding being obtained by virtue of the adhesive nature of the elastomeric sheet material without application of heat with a view to softening the sheet material and/or the web(s) capable of wrinkling.

Description

 The present invention relates to an extrudable composition suitable for forming a nonwoven web (for example a film, a sheet, etc.) of pressure-sensitive elastomer, and to composite materials formed from this composition. More particularly, the present invention relates to composite materials comprising at least one elastomeric sheet formed from said extrudable composition linked in the stretched state to at least one puckering veil.

For some time, those skilled in the art have attempted to
form fibrous nonwoven elastomeric webs from
elastomeric resins. For example, attempts have been
made to form fibrous nonwoven elastomeric webs
using elastomeric resins KRATO AG.KRATO is
a mark registered in the name of Shell Chemical Company of
Houston, Texas, for various elastomeric block copolymers
res polystyrene / poly (ethylene-butylene) / polystyrene. In US Patent No. 4,323,534, it is stated that the resins of
KRATO XG rubber are too viscous to be extruded
alone without substantial rupture of the melt of the
product; and that various KRATO G resins should be
mixed with a fatty chemical compound, such as acid
stearic before extrusion, and for example, be stretched to
the molten state to overcome the problem of viscosity.

However, the physical properties of the product obtained by this
process, for example, a nonwoven web of stretched fibers
in the molten state were apparently unsatisfactory because,
after the formation of the nonwoven web, substantially all of the
fatty chemical compound is removed from the nonwoven veil of
micro-fibers extruded by soaking the veil in alcohols having a good capacity to dissolve the fatty chemical used.

To overcome the difficulties indicated above and which are, for example, related to viscosity, it has been proposed to form nonwoven elastomeric products from elastomeric block copolymer materials by providing extrudable elastomeric compositions which are mixtures of ( 1) a block copolymer ABA ',, in which "A" and "A"' may be identical or different and are each terminal blocks of thermoplastic polymer which comprise a styrene unit, such as a poly (vinyl arene) unit and in which "B" is a poly (ethylene-butyl) elastomeric intermediate block, with (2) a polyolefin which, when mixed with the block copolymer ABA 'and subjected to suitable high pressure and temperature conditions, may be extruded in the form mixed with the block copolymer
AB-A '. The presence of the polyolefin in the mixture serves to reduce the viscosity of the composition by comparison with the viscosity of the pure block copolymer ABA 'and therefore increases the possibilities of extrusion of the composition. Such a mixture must be a composition which, after extrusion, solidifies to form elastomeric products.

 Thus, using a blend of the block copolymer and the polyolefin, the composition can be extruded at conventional temperatures and pressures and, in particular, it can be extruded at temperatures below the temperatures at which the block copolymers degrade or burn. The extrudable composition can give a variety of products, such as for example fibrous nonwoven elastomeric webs preferably having micro-fibers with an average diameter not exceeding about 100 microns, and preferably having an average weight per unit area not exceeding about 300 g per square meter, for example an average weight per unit area ranging from about 5 g per square meter to about 100 g or more per square meter.

With regard to this extrudable composition, reference may be made to United States patent application no. 760 698 filed on July 30, 1985, in the names of Tony J. WINESKI and
Michael T. MORMAN, entitled "Polyolefiiî-Containing
Extrudable Compositions and Methods for Their Formation Into
Elastomeric Products ", request to which corresponds the French patent application No. 2,558,713.

 In addition, research is underway on the uses of nonwoven elastomeric webs, either in themselves or as part of a composite laminate.

Thus, composite fabrics comprising at least one layer of nonwoven textile fabric mechanically attached to an elastomeric layer are known. For example, US patent 110 4 446 189 describes textile laminate materials comprising an internal layer of elastic material, such as a polyurethane foam with a thickness of approximately 0.64 mm, fixed by punching with the needle in a series of locations with a layer of nonwoven textile fabric. The needle punched overlapping layers are then stretched within the elastic limits of the elastic layer to permanently stretch the nonwoven fabric layer material which is joined by needle punching. the elastic layer relax and return substantially to its pre-stretch condition, the non-woven fabric layer offers increased volume as a result of the loosening of its permanently stretched fibers.

 In addition, US Patent 110 4,209,563 describes a method of manufacturing an elastic material which consists in continuously advancing relatively elastomeric and elongable but relatively inelastic fibers over a forming surface and in binding at least some of the crossings between fibers to form a coherent textile which is then worked mechanically as by stretching after which it is allowed to relax. As described in the patent in column 8, lines 19 and following, the elastic modulus of the fabric is significantly reduced after stretching, which results in the loosening of the permanently stretched non-elastic filaments and the formation of loops to increase the volume and improve the feel of the fabric. This patent indicates that the bonding of the filaments to form the coherent fabric can use embossing shapes or tightenings between smooth heated rollers.

 US Patent No. 2,957,512 relates to a process for producing elastic composite sheet materials and describes that a crosslinked fibrous web formed of an elastomeric material such as rubber, including butadiene-styrene copolymers, can be used. as an elastic layer of a composite material. The patent indicates that a layer of loose sheet material can be provided with a fibrous web of elastomeric material with a smaller surface than that of the stretched sheet material so as to conform it in surface to the surface of the sheet material. and the layers are bonded together at spaced points or areas. When OI1 allows the fibrous elastomer layer to relax, it is indicated that the composite body has a fibrous web structure of elastomeric material bonded in spaced areas or lines to a layer of crimped or corrugated flexible sheet material.

In addition, it has been proposed to provide a composite elastic material comprising at least one gatherable veil linked to at least one elastic veil, in which the elastic veil (which may include a fibrous veil, such as a nonwoven veil of fibers elastomers, for example elastomeric fibers entrained in the molten state) is tensioned to lengthen it; the elongated elastic veil is linked to at least one pleatable veil under conditions which soften at least parts of the elastic veil to form a linked composite veil; and (c) the composite web is released immediately after the bonding step, whereby the gathered web is gathered to form the elastic composite material. Such a proposed method comprises a step of connecting the elongated elastic veil to the pleating veil by placing, one on the other, elastic and puckering veils, and a step of applying heat and pressure to the stacked veils, for example, in bonding locations by heating on the elastic web at a temperature ranging from at least about 650C to about 1200C, preferably from at least about 700C to about 900C. In this proposed process, the resilient fibers can be made up of (1) block copolymers
AB-A ', in which A and A' may be the same or different terminal blocks and each is a terminal block or a thermoplastic polymer segment which has a styrene unit, such as polystyrene or polystyrene homologues and B is a block intermediate or an elastomeric polymer segment, for example an intermediate block chosen from the group comprising poly (ethylene-butylene), polyisoprene and polybutadiene, or (2) mixtures of one or more polyolefins with the AB-A block copolymers ', the polyolefin being chosen from one or more polyethylene, polypropylene, polybutene, ethylene copolymer, propylene copolymer and butene copolymer. The puckering veil can be a non-woven, non-elastic material, preferably a material composed of fibers formed from materials chosen from the group comprising polyester fibers, for example, poly (ethylene terephthalate) fibers, poly (olefin) fibers, polyimide fibers, for example nylon fibers, cellulosic fibers, for example cotton fibers and their blends. With regard to this proposed composite elastomeric material and its preparation process, reference may be made to the patent application of
United States No. 760,437 filed July 30, 1985, on behalf of Jack D. TAYLOR and Michael J. VANDER WIELEN, entitled "Composite Elastomeric Material and Process for Making the
Same ", application to which European patent application 110 0 217 032 corresponds.

 In this proposed method of manufacturing elastomeric composite materials, the bond between the layers of the laminate is obtained, for example, thermally or by ultrasonic welding, which softens at least portions of at least one of the webs , so as to make the connection by applying heat and pressure. Due to the bonding of the films by heating, and the fact that the elastomeric film is bonded in the stretched state, a difficulty resulting from the fact that this bonding takes place under the application of heat, can result in a loss of capacity. elastomeric web to contract if allowed to cool, even briefly, in the stretched state. One technique proposed to overcome this difficulty is to allow the composite web to contract immediately after bonding; however, the need to allow the composite to relax immediately after bonding imposes an additional condition in the procedure. In addition, additional problems arise due to the use of heat during bonding. Thus, the number of ruptures in the veil is high and the through burns (from the holes in the elastomeric veil at the connection points) as well as an undesirable re-hardening of the elastomeric veil in the molten state occur as a result of the relatively bonding temperatures. high.

Furthermore, by using, for example, KRAT0 (c) / polyethylene blends to form the elastomeric web, it is very difficult to bond such elastomeric webs to various desirable materials, such as, for example, centrifugally bonded polypropylene, used as wrinkled sails in the composite material. Various pressure sensitive adhesive compositions are known. For example, US Patent 4,294,936 describes pressure sensitive adhesive compositions formed (1) of a synthetic rubbery thermoplastic block copolymer, for example a block copolymer ABA or AB, in which the sequences A are thermoplastic sequences and the sequences B are rubbery sequences and they can be linear, branched or radial, or a mixture of these; (2) a non-rubbery polymer which is preferably a copolyester, for example a copolyester having at least two different ester units ce and a resin generating a tacky effect. As examples of block copolymer, mention may be made of KRATON03 1102 already described ( styrene-butadiene-styrene block copolymer) and KRAT0N (0
1107 (styrene-isoprene-styrene block copolymer). As a non-rubber component, a copolyester is described although polyethylene and polypropylene can be used. Rosin and dehydrogenated rosine, as well as liposoluble phenol-formaldehyde resins, among others, are described as a resin generating a tacky effect. This patent further indicates that the adhesive composition can be applied by mixing and melting the materials in an extruder and direct coating on a suitable support and that the adhesives can be applied inter alia to non-woven textiles.

 U.S. Patent 1,103,783,072 describes methods of producing, by extrusion, sheet and tape which are normally tacky and pressure sensitive adhesives in which a blend of ABA block copolymers (where A is a styrene-derived thermoplastic polymer block and B is an elastomeric polymer block derived from isoprene) and a solid compound generating a tacky effect is extruded onto a support sheet. As tackifier generating agent, there are described compatible, conventional tackifier generating agents, comprising hydrocarbon resins and the like. The thermoplastic elastomer block copolymer KRATO 1107 is indicated as a material which can be used in the adhesive formulation described.

 US Patent No. 4,543,099 describes pressure sensitive adhesives for imparting elastic characteristics to materials which are relatively non-elastic, by extrusion of a pressure sensitive adhesive, hot melted, in contact with a substrate, l the hot melt pressure sensitive adhesive comprising (1) a rubbery block copolymer which comprises a rubbery intermediate block portion terminated by crystalline vinylarene blocks; (2) a generally compatible, and generally associated, tackifying resin with the intermediate block portion of the block copolymer and (3) an essentially aromatic hydrocarbon resin having a glass transition temperature and a softening point higher than those of the tackifying resin and the terminal blocks of the block copolymer. This patent indicates that the block copolymers which can be used comprise KRATObP and that the resins which generate a tacky effect can comprise natural and synthetic resins essentially hydrocarbons.

US Patent No. 4,539,364 describes hot melt sizes for glass fibers, applied as a hot melt onto glass fibers while they are formed to create a coating on the fibers. The hot melt size described is formed from a thermoplastic block copolymer rubber, such as
KRATON of a low molecular weight polyethylene wax; and any low molecular weight resin compatible with the terminal styrene block of the rubbery block polymer, the resin preferably being a hydrogenated styrene / methylstyrene copolymer having a weight average molecular weight of about 1000, a viscosity at molten state of 1 poise at 2090C, and a glass transition temperature of about 650C, a low molecular weight hydrocarbon resin particularly suitable being constituted by the REGALRE 1126 resin available from Hercules Incorporated.

 Despite the above, there is a need for elastomeric composite materials (eg, elastomeric composite laminates) which can be readily manufactured and which have desirable properties. In addition, there is a need for extrudable compositions for forming elastomeric sheet materials, for example composite materials which can be used to easily form elastomeric sheet materials (for example fibrous nonwoven webs, such as webs trained in In addition, there is a need for elastomeric sheet materials which can be used to impart elastomeric properties to a composite laminate, using a bond between the elastomeric sheet material and another sheet (for example example a veil) of such a composite laminate which does not require high temperatures.

 Consequently, one of the aims of the present invention is to provide an extrudable composition, which can be extruded into an elastomeric nonwoven sheet (for example a film or a veil), in particular a fibrous elastomeric nonwoven veil, and more particularly still a fibrous elastomeric nonwoven web which can be formed by entrainment in the molten state, the elastomeric nonwoven sheet having both elastic and adhesive properties.

 The invention also proposes to provide a composite material (for example a composite composite) comprising an elastomeric nonwoven sheet formed from said extrudable composition and in which the connection between the elastomeric nonwoven sheet and another sheet of the composite material can be performed without applying a high temperature during the bonding (for example at room temperature).

 The invention also proposes to provide a composite material, in which at least one sheet of the laminate is a fibrous elastomeric nonwoven web, having adhesive properties, which web is formed from said extrudable composition and can be bonded to layers of various other materials, including polypropylene linked centrifugally, without the application of high temperatures.

 Another object of the present invention is to provide a composite material, comprising an elastomeric nonwoven veil, in particular a fibrous elastomeric nonwoven veil, and better still a fibrous nonwoven elastomeric veil formed by entrainment in the molten state, in wherein said veil is formed from said extrudable composition and the laminate is a laminate bonded in the stretched state, another layer of the laminate (other than the elastomeric veil) being a pleating material.

The present invention achieves each of the objectives
aforementioned by various techniques described below, but
each technique uses an effect-generating resin
tights incorporated as part of the extrudable composition to form the noI1 elastomeric woven material.

Without limitation, the extrudable composition according to the
The present invention preferably consists of (I) a
elastomeric polymer; (2) a polyolefin; and (3) a tackifying generating resin. The composition must be extrudable and be capable of forming a solid elastomeric material after such extrusion. Thus, the composition must contain a sufficient quantity of elastomeric polymer for the extruded material to be elastomeric. In addition, such a composition must comprise a sufficient quantity of adhesive-generating resin, such as the extruded material (for example a sheet ) can act as a pressure-sensitive adhesive).

The polyolefin is added for the purpose of reducing the viscosity of the extrudable composition, so that the composition can be extruded (e.g. melted) at a temperature low enough that the elastomeric polymer is not degraded and / or Substances other than a polyolefin can be used to reduce viscosity, it follows that the
polyolefin is not necessary and that in a specific embodiment, the tackifying resin itself (for example a low molecular weight hydrocarbon resin) can be used as a viscosity reducer, in addition to offer its function generating a tacky effect, when such a resin can sufficiently reduce the viscosity of the composition to achieve the objectives of the present invention (that is to say allow the extrusion at temperatures sufficiently low to avoid degradation and / or the burning of the elastomeric polymer).

 With regard to the inclusion of polyolefin in the composition, as indicated in the aforementioned American patent application 110 760 698, various polyolefins can be used, in an amount such that the overall composition has a viscosity low enough to be extruded at temperatures low enough to avoid degradation and / or burning of the block copolymer.

 By using the composition comprising at least the elastomeric polymer and the adhesive-generating resin, and a composition also containing the polyolefin, it is possible to form an elastomeric nonwoven material, for example a veil of fibrous elastomeric nonwoven material, such as an elastomeric web driven in the molten state, and such an elastomeric nonwoven material can be used as a pressure sensitive adhesive to be bonded to a gathered material such as polypropylene centrifugally bonded at relatively low temperatures. , such a nonwoven elastomeric veil can be stretched and, while it is stretched, it can be bonded (for example at a temperature in the range from 16 to 820C, preferably at lower temperatures, in the range from 380 to 60 "C, for example, at room temperature, without significant heating of the web for bonding purposes) to u n pleat of puckable material, after which, after loosening the stretching of the elastomeric veil, a composite material is obtained having an elasticity.

 In the drawings, the single figure is a schematic illustration of a process for the continuous production in line of a collapsible gathered fabric linked in the stretched state on each of the opposite faces of an elastomeric fabric.

 Although, in the following, the invention will be described in relation to specific and preferred embodiments, it should be understood that the intention is not to limit it to these embodiments. Rather, the intention is to cover all modifications, variations and equivalents which may be included in the spirit and scope of the appended claims. Before describing the invention more specifically, various terms used below must be defined. Thus, the term "compatible" is used to describe the relationship of one polymeric material to another with respect to the extrusion process and the extrudates.

To be compatible, two different polymeric materials must have a similar rheological behavior, they must form a homogeneous melt, and after being entrained by a stream of gas to form fibers and having solidified, they must form a homogeneous solid product. .

 The terms "elastic" and "elastomer" are used interchangeably to refer to the property of any material which, when applied with a stretching force, allows this material to lengthen to reach a stretched length which is at least about 125%, that is to say about 1 × 1/4, its length at rest, and which allows this material to recover at least 40% of its elongation when the force ceases stretching. A hypothetical example which would satisfy this definition of an elastomeric material would be a sample of one (1) centimeter of material which would be extendable to 1.25 cm and which, after having been lengthened to 1.25 cm and released, would find a length not exceeding 1.15 cm. Many elastic materials can be stretched more than 25% of their relaxed length and among these many are those which recover substantially their original relaxed length when the stretching force ceases . This last class of materials is generally preferred for the implementation of the invention.

 The term "recovery" refers to a contraction of a stretched material when the force to which it is subjected ceases following the stretching of the material by application of said force. For example, if a material having a length in the relaxed state, at rest, of one (t) centimeter was elongated by 50% by stretching to a length of 1.5 cm, the material would have been elongated by 50% and it would have a stretched length equal to 150% of its relaxed length. If this example of stretched material contracted, that is, recovered a length of 1.1 cm after the stretching force had ceased, the material would have recovered 80% (0.4 cm) of its elongation.

 The term "microfibers" refers to fibers of small diameter having an average diameter not exceeding about 200 microns, and preferably having diameters in the range of from about 0.5 microns to about 50 microns and, more preferably , having an average diameter of between about 4 microns and about 40 microns. The microfibers can be entrained in the molten state by extrusion of a molten thermoplastic material through a series of small diameter capillaries forming a circular matrix in the form of molten wires and drawing of the molten wires by applying a high speed air stream, usually air, to reduce their diameter to the range indicated above.

 The term material "centrifugally bonded" refers to a material made by extruding a molten thermoplastic material in the form of filaments through a series of capillaries belonging to a centrifugal die, the diameter of the extruded filaments then being reduced for example by reductive stretching or by other well-known centrifugal connecting mechanisms. The centrifugal bonded nonwoven web product and methods of making such webs are illustrated by US Patent No. 4,340,563 to Appel.

 The term "fibrous nonwoven web" refers to a web of material which has been formed without the use of a weaving process. A fibrous nonwoven web has a structure of individual fibers or threads which are intertwined but not in an identifiable repetitive manner. Fibrous nonwoven webs have been formed in the past by a variety of processes such as, for example, melt drive processes, centrifugal bonding processes, film piercing processes and carding processes fiber. These fibrous nonwoven webs generally have an average mass per unit area not exceeding about 300 g / m and preferably an average mass per unit area not exceeding about 15 g / m up to about 100 g / m.

As indicated above, the extrudable composition according to the present invention comprises an elastomeric polymer, for example an elastomeric block copolymer. Examples of block copolymers include the block copolymer
ABA 'or AB, in which A is a thermoplastic polymer block, for example containing a styrene unit such as a poly (vinylarene) unit, and B is an elastomeric polymer block such as a conjugated diene or a lower alkene polymer . Such a block copolymer of the ABA 'type can have identical or different thermoplastic blocks A and A', and the block copolymers according to the invention intend to comprise the linear, branched and radial block copolymers. In this regard, radial block copolymers can be denoted by (ABX, formula in which X is a polyfunctional atom or molecule and each of the groups (AB) - starts radially from X in such a way that A is a terminal block. In the radial block copolymer, X can be an atom or a polyfunctional organic or inorganic molecule and m is an integer having the same value as the functional group originally present in X. I1 is usually at least 3, and is frequently 4 or 5, without being limited thereto. Thus, in the present invention, the expression "block copolymer", and in particular "ABA" and block copolymer AB means all the block copolymers having the rubbery blocks and the thermoplastic blocks indicated above, which can be extruded (for example by melt training) and without limitation as to the number of sequences. sequenced olymers, attention is drawn to US Pat. No. 4,301,255.

 Among these block copolymers, those which are preferred are those of the type A-B-A 'in which A and A' can be identical or different thermoplastic terminal blocks and B is a rubbery intermediate block. The block copolymers falling within the scope of the block copolymers A-B-A ′ include KRATOG block copolymers. In particular, two specific KRATO polymers useful for the implementation of the invention are KRATONG-1652 and KRATO 1GX-1657. Such rubbery block copolymers are polystyrene / poly (ethylene-butylene) / polystyrene block copolymers, that having the designation 1652 having a weight ratio of polystyrene A terminal blocks to poly (ethylene-butylene) intermediate blocks B of 29:71, and the one with the designation 1657 having such a weight ratio of 14:86.

Various properties of these two types of KRATOC are shown in the following table.

TABLE 1 KRATO
PROPERTIES G-1652 GX-1657
Tensile strength 3,162 2,392 kg / cm2
Module 300%, kg / cm2 49 25
Elongation,% l 500 750
Elongation at break, %
Hardness, Shore A 75 65
Density 0.91, 9
Brookfield viscosity, (toluene solution)
CPS at 39 "C 550
Viscosity in the molten state,
Viscosity index,
Condition G, g / 10 min. -
Plasticizer oil
Weight percentage content 0 O
Styrene / rubber ratio 29:71 14:86
Physical form Crumbs Pastilles.

1 ASTM D method. Jaw separation speed of the
tensile test D 412 254 mm / min.

2 Characteristic properties determined on a cast film
from a solution in toluene.

3 Clear polymer concentration, 20% by weight.

4 Report of the sum of the molecular weights of the sequences
terminals (A + A ') at the molecular weight of the sequence
Intermediate B. For example, with regard to the KRATOMW
G- 1652 the sum of the molar masses of the two sequences
terminal (A + A ') is 29% of the molar mass of
AB-A 'block copolymer.

 Naturally, the present invention is not limited to the use of such rubber block copolymers KRATO a G as an elastomeric copolymer according to the present invention and attention is drawn to, for example, the various thermoplastic rubbers which are block copolymers and which are characterized by a styrene unit (such as a polyvinyl arene) and on the elastomeric polymer intermediate blocks such as the conjugated dienes or the alkene polymers as indicated in US Pat. No. 4,301,255 in the name of Korpman. Reference may also be made to the various elastomeric materials used in the formation of the fibrous elastic webs described in the aforementioned US patent applications Nos. 760,437 and 760,698. Thus, in general, any elastomeric polymer which is capable of being extruded (by thermoplastic example) made of a solid elastomeric material entering into the composition of the present invention (including, for example, a resin generating a tacky effect) falls within the scope of the present invention.

 The polyolefin which is used in the extrudable composition must be a polyolefin which, when mixed with the block copolymer ABA 'and subjected to an appropriate combination of high pressure and temperature, is extrudable, in the mixed form, with the copolymer sequenced AB-A '. In particular, the preferred polyolefin materials include polyethylene, polypropylene and polybutene, including ethylene copolymers, propylene copolymers and butene copolymers. Mixtures of two or more of these polyolefins can be used.

A particularly preferred polyethylene can be obtained from USI Chemical Company under the trademark
Petrothene Na601 (which is also referred to here as PE Na601). Information obtained from
USI Chemical Company indicates that Na601 is a low molecular weight, low density polyethylene suitable for application in the areas of hot melt adhesives and coatings. USI also indicates that Na601 has the following ratings: (1) a Brookfield viscosity, cP at 1500C of 8.500 and 1900C of 3.300 when measured according to ASTM D 3236 (2) a specific mass of 0.903 g / cm3 when measured according to ASTM D 1505; (3) an equivalent melt index of 2,000 g / 10 min when measured according to the ATSM D 1238 standard; (4) a softening point per ring and ball of 1020C when measured according to the standard
ASTM E 28; (5) a tensile strength of 60 kg / cm2 when measured according to ASTM D 638; (6) an elongation of 90% when measured according to the standard
ASTM D 638; (7) a rigidity module, TF (45,000) of -340C; and (8) a penetration hardness (tenths of a mm) at 25 C of 3.6.

ou
MW = les diverses masses molaires des molécules indivi
duelles dans un échantillon, et
n = le nombre de molécules dans un échantillon donné
ayant une masse molaire donnée de MW.Na601 has a number average molecular weight (Mn) of about 4600; a weight average molar mass (Mw) of around 22,400 and an average molecular weight Z of around 83,300. The polymolecularity (Mw / Mn) of Na601 is approximately 4.87. The values Mn, Mw and Mz indicated above are calculated by the following formulas

or
MW = the various molar masses of the individual molecules
dual in a sample, and
n = the number of molecules in a given sample
having a given molar mass of MW.

 Naturally, the present invention is not limited to the use of such a specific polyolefin described here. In this regard, reference may be made to the polyolefins described in the aforementioned American patent application No. 760 698. More generally, and given the specific purpose of the polyolefin, as described in the subject US patent application, various polyolefins which can be used according to the present invention can be easily determined.

 Various resins generating a tacky effect which can be used according to the present intention will now be indicated. In particular, the purpose of the adhesive-generating resin is to give an elastomeric veil which can act as a pressure-sensitive adhesive, for example, to bond the elastomeric sheet to a puckering veil. Naturally, various resins generating a tacky effect are known and they have been described, in particular in the aforementioned US Pat. Nos. 4,294,936 and 3,783,072. Any resin generating a tacky effect can be used if it is compatible with the elastomeric polymer and the polyolefin and if it can withstand the high processing temperatures (for example during extrusion). In general, hydrogenated hydrocarbon resins are the resins generating sticky effect which is preferred because of their greater heat stability. In the following paragraphs, information is given on three specific resins generating a tacky effect, two of which are examples of hydrogenated hydrocarbon resins (resin generating a tacky effect REGALREZe and of the ARCO P series) and the third of which is a hydrocarbon terpene ( ZONATAC501 lite). Naturally, if these three resins generating a tacky effect are discussed in a more specific manner, the invention is not limited to the use of these three resins and other resins generating a tacky effect compatible with the other components of the composition and withstanding the high processing temperatures can also be used and achieve the objectives of the present invention.

 REGALREZ hydrocarbon resins which are products of Hercules, Incorporated, are completely hydrogenated styrene-type low molecular weight hydrocarbon resins produced by polymerization and hydrogenation of pure monomeric hydrocarbon raw materials.

Grades 1094, 3102, 6108 and 1126 are highly stable, lightly colored, low molecular weight non-polar resins intended to be used to modify plastics, such as adhesives, coatings, sealants and caulking. The resins are compatible with a wide variety of oils, waxes, alkyds, plastics and elastomers and are soluble in common organic solvents. The product specifications of the above four qualities of REGALREZe hydrocarbon resins and Accounting information for these four qualities is shown below in Tables 2 and 3 respectively. 7
TABLE 2
RESINS REGALRE #
1094 3102 6108 1126
Softening point
Ring and ball,
OC 90-98 98-106 104-112 122-130
Crystal clear color--
Characteristic properties
Softening point
Ring and ball
OC 94 102 108 126
Crystal clear color
Acid number
Saponification index
Specific mass at 210C 0.99 1.04 1.01 0.97
Flash point,
COC, OC 235 293 243 243
Viscosity in the molten state, OC
1 poise 190 196 200 209
10 poises 151 164 168 182
100 poises 126 149 143 159
Glass transition (Tg), OC 33 51 52 65
TABLE 3
Compatibility
REGALREZe resins
Compatibility with 1094 3102 6108 1126
GGGG natural rubber
SBR 1011 PGGP
KRATON 1107 (MB) GGEG
KRATON 1101 (MB) PFGP
PGFP styrene terminal block copolymers
KRATON "G" (MB) GFGG
E / VA copolymers
(low aceta content
vinyl) EFGE
(high aceta content
vinyl) PEFP
EGEE paraffin wax
EGEE microcrystalline wax
Key: E = Excellent; G = good F = fairly good; P = poor.

 In addition, REGALREZI126 has the following molecular weight, as determined by the refractive index indicator: (1) weight average molecular weight (MW) = 1385; (2) number average molecular weight (Mn) = 919; (3) Mw / Mn = 1.51.

The ARKO A series resins which are products of Arakawa Chemical (USA), Inc., are synthetic resins generating a tacky effect for pressure sensitive adhesives which are based on petroleum hydrocarbon resins, these resins sticky effect generators being colorless and odorless, resistant to weathering and heat and having the general properties indicated in the
Table 4 next
TABLE 4
ARKON ARKON ARKON ARKON ARKON
P-70 P-90 P-100 P-115 P-125
Color index
(Hansen) 50 50 50 50 50
Softening point 700C 900C 1000C 1150C 1250C
Acid number OO 0 0 O
Specific mass
(200C) - 0.973 0.982 0.985 0.989
Refractive index
tion (200C) - i, 515 1,519 1,523 1,530
Molecular mass - 650 700 850 1000
Ash (%) - 0.05 0.05 0.05 0.05
Constant constant
cudgel
50 MC - 2.3 2.3 2.3 2.3
1000 MC - 2.3 2.3 2.3 2.3
Dielectric dissipation factor
50 MC - 0.0001 max 0.0001 max 0.0001 max 0.0001 max
1000 MC - 0.0001 max 0.0001 max 0.0001 max 0.0001 max
ZONATEC501 lite resin, which is a product of Arizona Chemical Co., has a softening point of 1050C, a Gardner 1963 color (50% in heptane) of 1- and a sharp (pure) Gardner color of 2+; a color (color
Gardner approximately equal to 1- (50% in heptane) color APHA = 70) of clear water, a density (250 / 250C) of 1.02 and a flash point (closed cup, OC) of 2490C.

 The components of the composition of the present invention can be used over a wide range of amounts of each of the components, these amounts being readily determinable by those skilled in the art. As a guide, when using a block copolymer A-B-A, a polyolefin and REGALREZX for the three components of the extrudable composition, the following broad and preferred ranges given in Table 5 are given as examples. It is emphasized that these ranges are given only for illustration purposes to serve as a guide to the quantities of the various components in the composition.

TABLE 5
Polymer Wide range Preferred range
Co-polymer
ABA sequenced 40-80% 60-70%
Polyolefin 5-40% 15-25%
REGALIZE 5-30% 10-20%
As indicated above, if the present invention has been described as relating to a three-component extrudable composition formed (1) of an elastomeric polymer; (2) a polyolefin; and (3) a tackifying resin, the polyolefin, the function of which is to reduce the viscosity of the total composition (compared with the viscosity of the elastomeric polymer as such), can be replaced by other compatible viscosity reducers, or can be eliminated completely when the tackifying resin also acts as a viscosity reducer. For example, low molecular weight hydrocarbon resins, such as REGALRE # can also act as a viscosity reducer, in which case, the extrudable composition may be formed from the elastomeric polymer and the adhesive-generating resin (for example REGALRE
Although the main components of the extrudable composition according to the present invention have been described in the foregoing, such an extrudable composition is not limited to these components and may include other components which have no harmful effects on the composition in achieving the objectives set. As examples of materials which can be used as additional components, there may be mentioned, without being limiting, pigments, anti-oxygen, stabilizers, surfactants, waxes, promoters flow, solid solvents, particles and materials added to improve the processability of the composition.

 As indicated above, the extrudable composition can be incorporated into a nonwoven web (for example a film, a porous film or a fibrous nonwoven web) by known extrusion techniques. A preferred extrusion technique is to form a fibrous nonwoven elastomeric web by melt-down techniques.

Molten drive methods generally include extruding a thermoplastic polymer resin through a series of small diameter capillaries belonging to a melt drive matrix in the form of molten wires in a stream of heated gas (the primary air stream) which generally flows in the same direction as the extruded wires, so that the extruded wires are drawn, i.e. pulled or extended, to reduce their diameter to the size of fibers or, preferably, micro-fibers. The micro-fibers thus formed are then carried away from the die by the gas stream. The gas stream is directed towards a porous element, such as a porous conveyor or a porous drum which moves on a canister. empty so that the fibers carried by the air abut against the surface of the porous element and are recovered on this surface to form a coherent nonwoven web of fibers. The melt drive die arrangements usually extend across the porous collecting member in a direction which is substantially transverse to the direction of movement of the collecting surface. The die arrangements include a series of capillaries small diameter arranged in line across the matrix with the transverse dimension of the matrix substantially equal to the width desired for the fibrous nonwoven web to be produced. In other words, the transverse dimension of the matrix is a dimension which is defined by the linear row of matrix capillaries. Usually, the diameter of the capillaries will be on the order of about 0.25 mm to about 0.51 mm, for example from about 0.37 mm to about 0.46 mm. 5 to about 50 such capillaries will be provided per 25.4 mm linear face of the matrix. Usually the length of the capillaries will be from about 1.27 mm to about 5.08 mm, for example from about 2.87 mm to about 3.56 mm. A melt drive matrix may be extend for about 762 mm to about 1524 mm or more in transverse direction.

 Such drive techniques in the molten state, and the apparatuses for their implementation are known in the art considered and they are described in detail in the aforementioned American patent application No. 760 698. For example, using a composition containing by weight 67% of KRATONtG-1657, 22% of PE Na601 and 11% of REGALREZe 1126, such a composition was carried out in the molten state with a composition temperature of 2710C. In general, the following parameters can be used for the melt training of extrudable compositions according to the present invention, said parameters being given by way of illustration without any limiting character. Thus, the extrudable composition can be drawn in the molten state while it is at a temperature between 2600 and 3160C and preferably between 2740 and 3020C during the melt drive. The temperature of the primary air, during entrainment in the molten state, can be from 2600 to 3430C, and preferably from 2880 to 315tu; and the pressure of the primary air may be between 0.14 and 0.56 kg / cm2 and preferably between 0.28 and 0.35 kg / cm2.

With regard to the formation of the laminate, various gathered materials can be used; in this regard, reference may be made to the patent application of
United States No. 760,437 supra. Materials in puckering veils can include, but are not limited to, non-elastic veils such as bonded carded non-elastic polyester and non-elastic polypropylene fiber veil, centrifugally-linked non-elastic polyester or non-elastic fiber veil polypropylene elastic, non-elastic cellulosic fiber veils, for example cotton fiber veils, polyamide fiber veils, for example nylon 6-6 veils sold under the brand CEREX by Monsanto, and mixtures of two or more of the aforementioned components. It is particularly desirable to use the puckering veil as outer layers (for example, in the form of a sandwich in which the elastomeric veil constitutes the intermediate layer and the covering veils are formed of puckering veils) . The weight per unit area of the puckable veil (s) depends on various factors, including the removal force of the elastic veil and the desired withdrawal for the elastic veil. By way of example, without being limiting, mass values per unit area for the puckable sail (s) are from 5 to 100 g per square meter, and preferably from 10 to 30 g .

 A preferred material for the puckering veil is polypropylene that is centrifugally bonded. In this respect, the previously known mixtures of K RATON / polyethylene could not be linked in an acceptable manner to polypropylene webs linked centrifugally in the form of puckering webs. According to the present invention, using the tackifying resin as a component of the composition with the elastomeric polymer and the extruded polyethylene to form an elastomeric web having adhesive properties, or is capable of bonding elastomeric webs to other webs. polymers, including polypropylene linked centrifugally.

 We will now refer to the single figure of the drawings in the following discussion of the laminating process with bonding in the stretched state. This figure schematically shows an online process for the continuous production of pleating, collapsible and bindable webs in the stretched state, which webs can be non-elastic webs, and the connection being made on the two opposite faces of an elastic stretch web. Thus, the elastic web 3 of the present invention was formed by conventional melt drive equipment 1, on a training conveyor 2 and it moves in the direction indicated by the arrows carried on the conveyor rollers 2. The web 3 then passes through the connecting members (rollers 6 and 7). The roller connecting members can be formed by a relief calendering roller 6 and a roller forming a smooth anvil 7. Various configurations of connecting rollers known in the art can be used. The first veil 'forming a puckable substrate 4 is unwound from a supply reel, as is also the second veil forming a puckable substrate 5. The first veil 4 and the second veil 5 advance in the direction indicated by the arrows associated respectively with the webs 4 and 5. The elastic web 3 is stretched to a desired percentage of elongation between the conveyor 2 and the connecting rollers 6 and 7 and, to do this, the connecting rollers rotate at a higher speed larger than the forming conveyor 2. The pressure between the rollers 6 and 7 links the webs (4 and 5) to the elastic web 3 to form a composite elastic material 8. As can be seen in the single figure, the elastic material relaxes when the stretching caused by the connecting rollers relaxes, whereby the puckering webs are gathered in the elastic composite material 8. The web 8 is then wound on a take-up reel 9.

 As can be understood, the connection between the gathered sails and the elastic veil is a point connection. Various bonding designs can be used, depending on the tactile properties desired, for the final composite laminate material. Such a bond can be made at temperatures as low as 160C, for example. A range of temperatures for the calendering rollers during bonding is from 16 to 820C and preferably from 38 to 600C. In this regard, the connection can be made without heating the calendering rollers; however, without heating the calendering rollers, there would be virtually no control of the temperature of the sails during bonding. As a result, it is preferred to heat the calendering rollers to a temperature in the range of 38 to 600C to control the temperature of the sails during the connection. As can be understood, in such a temperature range (38 to 600C), the bond is provided by the sticky nature of the elastic veil (i.e. the temperature is not so high as to cause softening elastic veil with a bond mainly due to such softening). An advantage of the present invention is that due to the relatively low temperatures which can be used during the bonding step according to the present invention, smaller distances between the bonding points can be used compared to the distances used in conventional layering techniques.

In general, the connecting rollers 6 and 7 press the laminate of webs at a pressure of, for example, between 1.78 and 8.9 kg / mm and, preferably, between 4.45 and 6.23 kg / mm . These pressures are about the same as those used in conventional techniques for forming elastic composite materials.

 As specific conditions of the stratification with bonding in the stretched state and with reference to example 2 below, the speed of the formation conveyor 2 was 15.2 m / min, the connecting rollers 6 and 7 were rotating at 46.6 m / min and the take-up reel was rotating at 22.2 m / min.

 The following specific examples of the present invention show the formation of the nonwoven elastomeric veil entrained in the fibrous molten state and the use of such a veil to form a laminate bonded to the stretched state as indicated above. Naturally, the present invention is not limited to such examples, these examples being given only by way of illustrations.

 In the following examples, the online device shown in the single figure was used. With regard to the structure of the drive matrix in the molten state, reference may be made to the aforementioned American patent application No. 760 698 and in particular to FIG. 3 of this patent application. The melt drive matrix had 0.37mm openings with 30 openings per 25.4mm in length. The air gap (between the die tip and the air plate) of the melt drive die was 1.6 mm and the distance from the die tip extended beyond the air plate over 0.20 mm. In addition, in the examples, we used as pleatable sails, polypropylene linked by centrifugal method having a mass per unit area of 13.6 g / m2, the pleatable sails being applied to both sides of the elastic web.

Example I
A mixture containing, by weight, 62.5% of KRATONOG-16j7, 25% of polyethylene Na601 and 12.5% of REGALREZ431126 was entrained in the molten state with the following conditions of entrainment : melting temperature 2770C; primary air temperature (training) 3130C and primary air pressure (training) 0.28 kg / cm.

The formation distance between the melt drive dies and the formation conveyor was 254 mm.

After forming the entrained veil in the molten state, the veil then passed directly to the laminating stage by bonding in the molten state. In this regard, reference can be made to FIG. 1. For the stratification by melt bonding, the forming conveyor rotated at a speed of 16 m / min; the link rollers rotated at a speed of 48 m / min and the take-up reel rotated at a speed of 22 m / min. The bonding rollers were at a temperature of 490C and applied a bonding pressure of 2.67 kg / mm.

Example II
A mixture containing by weight 63% of KRATONBG-1657, 20% of polyethylene Na601 and 17% of REGALREZ1126 was entrained in the molten state under the following conditions, melting temperature of 2770C and primary air temperature of 3160C. The primary air pressure was 0.28 kg / cm2 with a formation distance between the dies and the formation conveyor of 254 mm. The veil entrained in the molten state then passed directly to the stratification stage by bonding in the stretched state with the forming conveyor rotating at a speed of 15 m / min, the connecting rollers rotating at a speed of 47 m / min and the take-up reel rotating at a speed of 22 m / min. The connecting rollers were at a temperature of 600C and applied a pressure of 5 kg / mm.

Comparative example I
A composition containing, by weight, 60% of KRATONRG-1657 and 40% of polyethylene Na601, without a tackifying agent, was entrained in the molten state under the following conditions: melting temperature of 2790C, temperature of primary air of 3170C, primary air pressure of 0.28 kg / cm and formation distance between the dies and the formation conveyor of 356 mm. The melt-formed web formed was then passed directly to the layering stage by stretched bonding, the forming conveyor rotating at a speed of 15 m / min, the connecting rollers rotating at a speed of 46 m / min and the take-up reel rotating at a speed of 23 m / min.

The connecting rollers were at a temperature of 820C, and they applied a pressure of 2.67 kg / mm.

 The characteristics of the veil entrained in the molten state and of the laminate linked to the stretched state, derived from the three examples above, are indicated in Table 6 below.

 The physical characteristics (physical characteristics in the direction of the machine) of fibrous nonwoven webs (in the melted state) and of laminates linked to the drawn state formed by the methods detailed in Examples I and II and in Comparative Example I, as shown in Table 6, was determined by the use of an Instron Model 1130 tensile tester. Each sample was 76 mm wide (machine transverse direction) by 178 mm long (machine direction). Each sample was placed lengthwise in the jaws of the Instron instrument with a setting of the initial separation of the jaws of 102 mm.

The following tests were carried out with the results indicated in Table 6.

(1) The sample was then drawn at a speed of
508 mm per minute to determine the load in
grams required to lengthen such a sample
100% in the direction of the machine. In
other words, we determined the charge in
grams needed to lengthen each sample
lon, in the direction of the machine, twice
the length it has, in the direction of the
machine, in the unstretched state, this for the purpose of finding
the load for 100% elongation.

(2) The load at 500% elongation was determined in
finding the charge in grams necessary for
lengthen each sample to a length, within
direction of the machine, equal to 5 times its length
in the direction of the machine in the unstretched state.

(3) The percentage extension to 1000 grams is the
percentage at which the sample stretches when
apply a force of 1000 grams to it in the
machine direction.

(4) The load at 50% elongation was determined in
finding the charge in grams necessary for
lengthen each sample to a length, within
machine direction, 50% greater than its
length, in the direction of the machine, in the state
not stretched.

(5) The internal consistency test consisted of measuring
the maximum load obtained during the stretch
of a laminate linked to the stretched state between two
pressure plates covered with adhesive tape
pressure sensitive, double sided. This essay
indicates the force necessary to destratify the
laminate linked to the stretched state.

TABLE 6
Characteristics of the veil Example I Example II Example stretched in the molten state I com from Mass / unit area 76 g / m2 72 g / m2 75 g / m2
Load for 100% elongation 448 g / 7.6mm 392 g / 7.6mm 983
g / 7.6mm
Load for 500% elongation 875 g / 7.6mm 828 g / 7.6mm 449 g / 7.6mm
Characteristics of SLE
Mass / surface unit 162 g / m2 130 g / m2 130 g / m2% elongation under 1000g 123% 117% 102%
Load for 50% elongation 452 g / 7.6mm 556 g / 7.6mm 507 g / 7.6mm
Internal consistency 3.9 kg 6.1 kg 2.3 kg
SLE = Laminate linked to the stretched state.

 As can be seen from the preceding table, the incorporation of the tackifying resin or the increase in the quantity of such a resin clearly increases the consistency of the laminate linked to the stretched state. In addition, the use of the adhesive-generating resin allows the bonding rollers to operate at a lower temperature.

Consequently, the present invention provides the following advantageous effects
(1) Due to the lower bonding temperature,
there is less rupture of the veil during the
liaison.

(2) We obtain a binding capacity to a large
number of different types of outer layers, including
including in particular polypropylene bonded by
centrifugal.

(3) Greater elongation can be obtained
laminate related to the stretched state due to the lesser
permanent hardening from the weakest
bond temperatures; and
(4) the resulting fabric offers possibilities for stretching
in the direction of the machine as well as a
good internal consistency.

 Although the invention has been described with reference to various possible embodiments, it is not limited to these embodiments but various variants, within the reach of ordinary skill in the art, may be available to him. brought.

For example, the formulations are not limited to specific embodiments, but may include other ratios and other polymers to achieve the same results. Thus, one could use a polymer of ethylene and vinyl acetate or other hydrogenated polymers of the styrene type in the composition.

Claims (25)

 1 - Extrudable composition for the formation of nonwoven sheets of pressure-sensitive elastomer, comprising: a) an elastomeric polymer, and b) a resin generating a tacky effect, the quantity of elastomeric polymer in the composition being sufficient for the nonwoven sheet formed is elastomeric, and the quantity of resin generating a tacky effect in the composition being sufficient for the formed sheet to be able to act as an adhesive.  2 - Extrudable composition according to claim 1, in which the composition also contains a polyolefin, the quantity of polyolefin in the composition being sufficient to lower the viscosity of the composition so that the composition can be extruded without degradation or burning of the elastomeric polymer.  3 - Extrudable composition according to claim 2, wherein said elastomeric polymer is an elastomeric block copolymer.  4 - An extrudable composition according to claim 3, in which the elastomeric block copolymer is chosen from the group comprising AB-A 'block copolymers, AB block copolymers, and radial block copolymers (ABX, in which A and A' are thermoplastic polymer blocks which may be the same or different and B is a rubbery polymer block and X is an organic or inorganic polyfunctional atom or molecule, with m representing an integer having the same value as the functional group originally present in X.  5 - Extrudable composition according to claim 4, wherein the elastomeric block copolymer is a block copolymer A-B-A '.  6 - Extrudable composition according to claim 5, in which A and A 'are poly (vinylarene) blocks and B is a polymer of a conjugated diene or a lower alkene polymer.  7 - Extrudable composition according to claim 6, in which the polyolefin is at least one polyolefin chosen from the group comprising polyethylene, polypropylene, polybutene, ethylene copolymers, propylene copolymers, butene copolymers, and their mixtures.  8 - Extrudable composition according to claim 7, in which the resin generating a tacky effect is a hydrogenated hydrocarbon resin.  9 - Extrudable composition according to claim 8, in which the hydrogenated hydrocarbon resin has a softening point between 90 and 1300C, a density at 21 C between 0.97 and 1.04, a glass transition temperature between 33 and 650C, a melt viscosity of 1 poise between 190 and 2090C, a melt viscosity of 10 poise between 151 and 1820C, and a melt viscosity of 100 poise between 126 and 1590C.  10 - Extrudable composition according to claim 9, in which the composition comprises by weight 40-80% of block copolymer A-B-A ', 5-40% of polyolefin and 5-30% of resin generating a tacky effect.  11 - Extrudable composition according to claim 10, in which the composition contains, by weight, 60-70% of block copolymer A-B-A ', 15-25% of polyolefin and 10-20% of resin generating a tacky effect.  12 - Extrudable composition according to claim 6, in which the resin generating a tacky effect is a terpene hydrocarbon resin.  13 - Extrudable composition according to claim 6, in which the adhesive-generating resin is a hydrogenated hydrocarbon resin.  14 - Extrudable composition according to claim 2, wherein the composition comprises by weight 40-80% of elastomeric resin, 5-40% of polyolefin and 5-30% of resin generating tacky effect.  15 - Elastomeric composite material comprising at least one elastomeric pressure-sensitive sheet formed from the extrudable composition according to any one of claims 1 to 14, said sheet being linked to at least one pleating veil which is extensible and contractible with the elastic veil when the composite material is stretched and released, in which the pressure-sensitive elastomeric sheet is bonded to the puckering veil without heating the elastomeric sheet and the puckering veil in order to soften them, the connection between the elastomeric sheet and the puckering veil being effected as a result of the tackiness of the elastomeric sheet.  16 - Elastomeric composite material according to claim 15, in which the elastomeric sheet is formed from a mixture of elastomeric polymer and a tackifying generating resin, the mixture containing a sufficient amount of elastomeric polymer for the sheet to be elastomeric. and a sufficient quantity of adhesive-generating resin so that the sheet can adhere to the puckering veil by applying pressure, without heating, in order to soften the elastomeric sheet.  17 - Elastomeric composite material according to claim 15, in which the elastomeric sheet is a fibrous elastomeric nonwoven web.  18 = Elastomeric composite material according to claim 17, in which the fibrous elastomeric nonwoven web is a web formed by entrainment in the molten state.  19 - Elastomeric composite material according to claim 15, in which the gathered fabric is a fibrous nonwoven fabric.  20 - Elastomeric composite material according to claim 19, in which the fibrous nonwoven web is a web formed by centrifugal bonding.  21 - Elastomeric composite material according to claim 20, in which the web linked by centrifugal method is a polypropylene web linked by centrifugal method.  22 - Elastomeric composite material according to claim 21, in which the gathered fabric is a fibrous nonwoven fabric.  23 - Elastomeric composite material according to claim 22, in which the fibrous nonwoven web is a web formed by centrifugal bonding.  24 - Elastomeric composite material according to claim 23, in which the veil linked by centrifugal method is a polypropylene veil linked by centrifugal method.  25 - Elastomeric composite material according to claim 15, formed by a process comprising the steps of  a) tensioning said elastomeric pressure-sensitive sheet to lengthen it; and  b) bonding of the elastomeric sheet to at least one pleating veil by applying pressure to the elastomeric sheet under tension and to the pleating veil, without heating the elastomeric sheet and the pleating veil with a view to softening them, the connection being accomplished as a result of the tackiness of the elastomeric sheet.