FR2563769A1 - METHOD OF MANUFACTURING THERMOCONTROLLABLE ELASTOMER, APPLICATION OF SUCH METHOD TO FLEXIBLE ARTICLE, AND ARTICLE THUS FORMED - Google Patents

Abstract

THE FIELD OF THE INVENTION IS THAT OF THERMOCONTRACTABLE ELASTOMERS. THE PROBLEM SOLVED CONSISTED OF MAKING SUCH ELASTOMERS WITHOUT SUBJECT TO A THERMAL TREATMENT BEFORE THE THERMOCONTRACTION OPERATION, SO THAT THEY KEEP ALL THEIR ELASTIC PROPERTIES AFTER THERMOCONTRACTION. ACCORDING TO THE INVENTION, THE THERMOCONTRACTABLE ELASTOMER HAVING A FIRST LENGTH, IS PRODUCED BY MONOAXIALLY ORIENTING A COPOLYMER IN THE FORM OF SEGMENTS IN ALTERNATE BLOCKS OF POLYAMIDE AND POLYETHER, UP TO A SECOND LENGTH SENSIBLY THROUGH A LENGTH THAN AN INTERFORMANCE THAN A LENGTH OF LENGTH. PERMANENT PARTIAL. AFTER THE TENSIONAL FORCES ARE ABOLISHED, THE STRETCHED ELASTOMER IS NATURALLY RELAXED UP TO THIS THIRD LENGTH. AFTER APPLICATION OF HEAT, THE ELASTOMER CONTRACTS AND RECOVER ITS ELASTIC PROPERTIES. THE INVENTION ALSO RELATES TO A SINGLE-LAYER ELASTOMERIC FILM AS A MULTI-LAYER FILM WITH NON-ELASTIC OUTER LAYERS. THE INVENTION FINDS A PARTICULAR APPLICATION IN THE REALIZATION OF ELASTIC BANDS FOR DISPOSABLE HYGIENIC TOWELS 54, 56.

Description

"Method of manufacturing a thermocontractable elastomer,

  cation of such a method to an article with gathered pleats, and article thus formed ",

  The present invention relates to thermoelastomers

  contractables and more specifically the thermocontractable elastomers specially used for the elastic gathering of

  clothing, such as disposable towels or other

continence.

  The elastic gathering of clothing in

  selected, is quite interesting, even necessary, so that the garment can conform to the body of the wearer, by

  example at the waist or wrist. This characteristic is

  particularly true with regard to disposable clothing,

  such as plastic clothes of the type of

  your disposables. Therefore, the invention, the prior art, and more

  some embodiments will be described in particular by

  reference to disposable napkins or

  continence, but it is clear that the invention can be applied to other clothing and accessories, such as dresses,

  masks, shoe covers, and others.

  Disposable napkins typically have an hourglass-shaped configuration, or more generally I. These (sanitary) napkins are produced from a continuous strip of inner and outer sheets facing each other, and an absorbent pad, each portion belt of a towel

  individual being fully connected to the part of the

  immediately adjacent towels. (About this, see

  Figure 2). The ribbon is cut at the waist section

  ture, transversely to the direction of movement of the ribbon., thereby to form the individual towels. Consequently,

  the waistband is cut in a direction perpendicular to

machine eyepiece.

  The application of an elastomeric material to the crotch

  disposable towels has already been made commercially. Toute-

  When attempting to apply the elastomeric material to the belt portions on a napkin already having its crotch formed, important production problems arise. For example, if the tension is maintained in the direction of the crotch, the elastomer attached to the waist portions tends to "fluff" the napkin, and thus hinders the folding, packing and other steps. We do not know any commercial solution

to these production problems.

  Recently, some proposals have been made for thermoformed and heat-shrinkable elastomeric materials used for ruffling disposable garments such as disposable napkins or gowns as can be seen in U.S. 3912565, 3819401 and 363991, U.S. Patents 3912565 (Koch et al) and 3819401 (MASSENGALE ETAL) disclose flexible sheets of polyurethane and vinyl chloride plasticized respectively, which are heated,

  stretched and cooled to prevent premature contraction.

  In order to avoid premature contractions, the elongated leaves

  tomere are heated again to allow a looser

  mite, and cooled to thermoform the leaves. Leaves

  thermoformed are then applied to articles, and under

  heat, they contract to their original length, thus frowning the articles. As will be more fully explained with reference to FIG. 1, in KOCH et al and MASSENGALE et al., The sheet is drawn between heated rolls 25, and press rolls 31, 33, then cooled, partially released into a heated liquid bath. 45, and collected in roll 49. What should be noted in KOCH et al and MASSENGALE et al is that stretching is performed by applying external heat, cooled in stretched condition, and then heated again.

  by applying external heat to control the thermo-

contraction.

  U.S. Patent 3,639,917 (ALTHOUSE) describes an elasticity

  tomère comprising hermocontractable copolymer blocks.

  According to ALTHOUSE, these block copolymers are dilated or deformed from an original length, at high temperature, to make them take a new length, and then cooled to maintain the copolymers at this new length.

  the dilate state. The copolymers of ALTHOUSE thus keep the new

  at the time of cooling, until heated again; at this moment a contraction occurs up to the original length. The copolymers of ALTHOUSE are thus dilated from their original length to a new length, maintained at this new length by cooling, then brought back to their original length.

by application of heat.

  The elastomer of the present invention, which exhibits

  a potential elastic energy - recoverable by thermocontrac-

  is oriented in one direction, for example by drawing or rolling, without the application of external heat, up to a certain length, such as when the applied voltage is

  removed, the elastomer relaxes to a length of

  permanent formation greater than its original length, but less than the length of stretching. Precisely, the elastomer

  thermocontractable having a first length, or

  original, is stretched in one direction up to a

  significantly larger, or second length, without

  application of external heat, for example up to a length of about 200% to the original length. When released, the elastomer exhibits permanent deformation at a third length, somewhere between the first and second lengths. This third length, or intermediate state, is sometimes known as a preform. The elastomer subjected to

  tension forming the preform, has elastic properties

  reduced when in the deformed state. Then, by applying heat, the elastomer contracts, and recovers or takes its elastic properties. The elastomer, when

  subjected to a voltage of a useful or desired value,

  an increase in its length of permanent deformation when the value of tension increases, while the elastomers

  Conventional have minimal permanent deformation.

4.

  It is very important that thermoforming and

  cooling of the elastomer preform are avoided. The switching on and release of the elastomer that occurs

  apparently in monoaxial orientation of the polymer, are

  without the application of external heat, ie at ambient temperature (eg 70-75 ° F, ie approx 20-25 ° C), although internally there is an increase

  temperature. However, the elastomer retains these characteristics

  thermocontracted ticks. Thus, some process steps, and the corresponding equipment, are removed in the application

  commercial elastomer on clothing.

  According to one embodiment of the invention, the elasticity

  tomère is coextruded or laminated with a non-elastic material.

  Preferably, the elastomer and the non-elastic material

  are extruded in the form of a caposite sheet using known techniques. In a more particularly desired manner, the composite sheet comprises three layers, an intermediate layer of

  elastomer, and two outer layers. The elastomer can

  present a certain viscosity, and to block as well in

  rolled form, than unrolled. The superficial layer

  tick is chosen to ensure a release, and avoid blocking when the material is unrolled, which facilitates the manufacturing steps, namely the guiding, cutting, setting etc ... In addition, the elastomer can present a

  low or no adhesion to many clothing materials.

  Accordingly, the outer layer disposed opposite the composite, and facing the garments, is attached thereto for example by means of a pressure-sensitive or heat-sensitive adhesive. Thus, the composite sheet has many

  advantages that are not possessed by a single sheet

che.

  The invention also relates to a method of manufacturing

  cation of an article with an elastically gathered portion, according to

  first of all, an elastomer is produced by means of the method of manufacture mentioned above and described in more detail below, then the elastomer is applied to said portion

  of the article, preferably in a roughly parallel direction

  leash to the desired ruffling direction; it is heat-sealed

  following the elastomer thus fixed, to elastically gather the portion of the article in question,

  The invention finally relates to the article thus produced.

  Other features and advantages of the invention

  will appear on reading the following description and

  in which: - FIG. I is a block diagram showing the manufacturing steps of the present invention; FIG. 2 is a schematic plan view of a

  portion of a continuous sheet for disposable napkin made from

  cation, comprising ribbons of the film (composite sheet) of the present invention, attached in the waist zone, and shown before the thermocontraction operation; FIG. 3 represents a schematic view of the means

  allowing the coextrusion of the multilayer film of the invention.

  1. Embodiment of a single-layer film

  Referring to Figure 1, it can be seen that the

  The process of the present invention begins with the extrusion of the

  lymere, which may be in the form of beads, by means of ex-

  said film forming a film 12 which is stored preferably in roll 14 and transported to

  next manufacturing station, for example stretching 16 of the film.

  Advantageously, the extruded film has a thickness of about 0.05 mm to about 0.1 mm (2 mils to 4 mils), although other thickness values are also possible depending on the size of the film. stretch that is necessary to achieve the desired degree of puckering of the article, the polymer

  particular that is used, the savings of production and others.

  Although the word "film" is used here, elasto-

  Mothers of the present invention may be produced in other structural forms, such as, for example, in the form of ribbons, threads, strips, or the like. For reference facilities 6.

  however, only the word "film" will be used.

  As already mentioned briefly above, the polymer used to produce the film, according to the present invention, is

  preferably a block copolymer having in

  polyamide and polyether block polymer segments according to the general formula:

O O)

  Wherein R 1 represents the polyamide copolymer block, for example nylon 6, nylon 6,6, nylon, nylon 11 or nylon 12; and R2 represents the polyether copolymer block, for example polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; n is

  an integer. The copolymers of the above description

  are commercially available from the "Rilsan Corpora-

  Glen Rock, New Jersey ", under the brand name PEBAX.

  Particularly preferably, the films of the present invention are prepared from extrusion grade PEBAX.

2533.3533.

  The film 12 formed as described above is then

  monoaxially stretched, without the application of ex-

  dull, by means of any conventional type of film stretching means 16, such as for example by means of a method of

  differential speed. A different speed roller system

  A particularly preferred embodiment suitable for use as a film stretching means 16 for stretching the films of the present invention is the "Marshall and Williams Model P7700" drawing apparatus. According to the well-known principle of

  differential stretching, the film 12 is stretched monotonically

  axially due to the differential speed of rollers of

  slow speed and fast speed rollers. Another

  The orientation method for carrying out the thermocontraction is cold rolling, on a multilayered / multi-stage rolling mill, of the type used for rolling sheets 7.

  fine metal such as aluminum foil.

  Whatever the method adopted, however, the common result achieved is an increase in the dimension in the direction of orientation, accompanied by a corresponding decrease in thickness.

  Conventional polymer films stretched monoaxially

  Typically, they are typically preheated to a temperature equal to or greater than the second order phase transition temperature. The conventional film is then stretched while it is at this temperature, and then cooled while being kept in the stretched condition. Such preheating is important

  in the case of conventional films so as to ensure

rage and correct orientation.

  Preheating is completely unnecessary in the context of the present invention. There may be a little heat during the monoaxial stretching of the film 12 due to the frictional forces or the like, especially if differential speed rollers are used to draw the film, but we have noticed with surprise that the temperature thus released is much lower than the temperature at which the release of the copolymer film begins to deform (for example, well below 80 ° C). This means that although some heat can be released by friction during drawing

  of the film, the temperature reached by the film of the present

  The temperature is clearly below the temperature at which deformation relaxation occurs. Thermoforming, of course, assumes that the temperature is equal to or greater

  at the temperature at which the replay begins to occur.

  deformation (see U.S. Patent 3,912,565, column III

  line 28 to 38). If there is absolutely no need for thermoforming

  in the oriented film of the present invention which is quite the opposite of what is conventionally thought to be essential in dan. this area of technology,

  The value of monoaxial stretching of

  The invention of the present invention is important for achieving adequate shrinkage, and thus article crimping, using the film. According to the present invention, the mono-axial tensioning is carried out so that the film is stretched to a length of elongation substantially greater than the length at which the permanent deformation occurs. When the applied voltage is removed, the film go

  to relax naturally, (without being forced to

  let go by applying heat up to a maximum length

  greater than its original length, corresponding to the amount of permanent deformation which has been conferred on it Thus, the differential length between the length of permanent deformation e original length before stretching, is available for thermDcontractiao By application of heat (for example at a temperature equal to or greater than 80 C), the stretched film will therefore be forced to relax further and contract. That is, a large part of the

  differential length of the stretched film between the original length

  and the length of permanent deformation exists as

  permanent deformation which can be "recovered" or absorbed

dropped by the application of heat.

  The film of the present invention is stretched monoaxially

  in order to undergo an elongation

  % and about 700% per unit length of the film. We have

  that when the film of the present invention is monoaxially stretched within these elongation values there is some natural loosening upon removal of the stretching force, but this relaxation does not occur.

  will not occur below the deformation length

  nent. The length of the film corresponding to the value of

  permanent deformation which is conferred upon it is therefore

  the intensity of the monoaxial voltage to which it is subjected. However, for msnoaxial stretches of enviror

  % to 700%, the permanent deformation length will be

  taken between 20% and 60% of the length of the stretched film. This

  means that the amount of permanent deformation available

  The temperature for the thermocontraction will be between about 20% and 60% of the stretched length of the film, which has been stretched from about 200% to about 700% (i.e.

8 times its original length).

  The amount of permanent deformation that is conferred

  The film of the present invention will therefore determine the degree of thermocontraction that can be achieved to adequately frown the portion of an article to which it will be added. It has been found that a permanent deformation of between 20 and 60% of the length of elongation (still

  called "absolute contraction") could advantageously be

  between 30 and 45% contraction (called "contrac-

  restricted ") when the monoaxially stretched film is

  attached to a portion of a flexible garment, such as

  fold the belt area of a disposable towel. Consequently, since the flexible article will hinder or restrict to a certain extent the contraction of the film, a complete return to the original length of the film before stretching will not occur during the thermocontraction. In any case,

  when the film of the present invention is stretched monoaxially

  As described above, for example between a permanent deformation of about 20 to 60%, with respect to the final elongation to which the film is subjected, the gathering occurs.

desired from the article.

  Following the stretching, the film of the present

  The invention is advantageously cut by conventional film cutting means 40 in the direction of

  permanent deformation, that is to say parallel to the di-

  monoaxial stretching rection so as to form ribbons with a preferential width of 10 to 12.5 mm; but other values of the width are of course possible depending

  the intended application. The ribbons can then be

  rolled in a regulated way, using onnuesen techniques

  can be used in 42 production equipment

  your. The ribbons are preferentially cut to the desired length, (preferably about 150 mm) when they are still in the elongated and heat-controllable state, and then adhesively secured to the belt areas 50, 52 of the napkins when the connected sheet 60 flows in the direction of the machine (arrow 57 in FIG. 2) - Adhesives suitable for attaching film strips according to the invention to the belt areas of the towels are commercially available from HBFULLER Co., under the reference HL-1307-331, and from the FINDLEY Co. under the reference X807-378-01. A particularly preferred means for cutting ribbons of predetermined length and attaching them by adhesive to the waistband areas of the napkins is described in THORSON E.U.A. The same applicant, regarding a method of applying elastic belts on disposable towels, is presently intended to heat-collectively, by suitable heat-sealing means 44, a pile of towels (preferably 8 to 10 towels).

  by battery), comprising ribbons of the thermally elastomeric film

  contractable of the present invention, for the operation of ther-

  mocontraction of the ribbons, and the gathering of the belts areas of the napkins. Preferentially, thermocontraction

  ribbons in the pile of towels is carried out as

  that in the joint application POMPLUN E.U.A. 605 968 of May 1, 84 filed by the same holder, and concerning the formation of

  elasticized portions, especially in disposable garments.

  This patent application is also extended in France. In this way, there will be no problem at the level of

  towel folding equipment, which is due to an entanglement of

  or premature crimping of belt areas across the machine, 2. Embodiment of a Multilayer Film Another embodiment of the present invention is to coextrude the polyether polyamide copolymer, described above, with nonelastic polymers, such as ethylene and vinyl acetate copolymers. (EVA), EVA ionomers of the type of Plexar 3, Plexar 102 and Surlyn 1702, (Plexar 3 and Plexar 102 are available 11.

  commercially from the Chemplex Corporation, and the

  lyn 1702 is available from DuPont)! and polyethylene, or the like, so as to advantageously produce a film that is heat-shrinkable but has a pleasing feel. It is desirable for the elastic waist zones to be able to be supported by the wearer's skin when the films of the present invention are used as belts for disposable napkins. According to this embodiment of the present invention, the polyether / polyamide copolymer is coextruded in core form, or intermediate layer, with surface-exposed layers or outer layers of non-elastic polymers. Although the outer layers may not be heat-treatable, they will not interfere with the heat-control of the core in a way that can prevent

  the proper garment ruffling, because of the superior capabilities

  heat-shrink film in core layer.

  The coextrusion of the layers of the various polymers or thermoplastic materials is well known per se in the field of the art, as for example in the patents

  USA. 557265 (Chisholm et al.) And 479425 (Lefevre et al).

  The coextrusion of the different polymers is carried out so

  typical, using a multi-die coextrusion mold

  ples, or with a simple die, with

  allow the hot rolling of several layers of poly-

  different mothers. A combination adapter particularly

  adapted, which can be used to advantage in order to

  the coextruded films of this invention are described in

  U.S. Patent 4, 152387 (Cloeren).

  Conventional means of film production

  The extruded multilayers of this invention are schematically

  3. As shown, the non-elastic outer layers 70, 72 are formed by extrusion.

  non-elastic polymers 74 by means of an extrusion

  Similarly, the elastic core layer 80 is formed by hot extrusion of the elastic polymer 82 (for example preferably 2533 or 3533 extrusion grade Pebax by means of an extruder 84.

  74,82 hot-extruded polymers are then fed to the

  combination device 90 through the ducts 78,88 respectively.

  tively. As schematically shown, the elastic polymer 82 is hot rolled with the inelastic polymer 74, to form a core layer 80 of elastic polymer 82, which is sandwiched between the outer layers 70,72 of

non-elastic polymer 74.

  Although the temperature of the combination adapter

  its 90 depends on the polymers used, it is better to obtain

  this temperature between about 180 C and about 260 C

  (and preferably above 200 C), to advantageously form

  the coextruded films of this invention. In addition, it is preferable that the total thickness of the coextruded film is

  between 0.05 mm and 0.125 mm (2 to 5 mils), and preferably

  between 0.05 and 0.1 mm, although all other

  can be used for the film, depending on the thickness

  final desired draw. The coextruded film comes into contact with the cooling rollers 92, 94 so as to cool it down to approximately maintain the thickness

  extrusion. Another way of training multi-nationals

  ches, is coextrusion blowing, using a cir-

  with corresponding coaxial blowing channels

  to the individual layers of the composite sheet. The

  Coextruded film can then be oriented by labeling means.

  rabies cut into ribbons by cutting means, applied to towels in means of production of

  towels 42, then heat-treated by thermo-thermal means.

  contraction 44 as described above with reference to the

gure 1.

  The core layer of polyethylene elastic block copolymer

  Ether / polyamide is preferably the main constituent, (as a percentage by weight of the coextruded film), present in the resulting coextruded film. The core layer is therefore preferentially present in the coextruded film in an amount between about 70% and 90% by massing the remainder being distributed approximately equally between each of the outer layers. The behavior of the composite sheet coextruded, or laminated, according to the invention, is similar to the behavior of single-layer films described above. Indeed, when the composite sheet is oriented monoaxially up to a length corresponding to about 200% to 700% of its original length, it is conferred permanent deformation, between approximately 20% and about 60% of the length of 'elongation. After removal of tensile forces, the coextruded film is similarly relaxed naturally (i.e. without the application of heat) to the indicative length of permanent deformation which has been imparted to it. difference in length between the elongation length and the length of permanent deformation is available as a contraction length, so that when: is heated to heat (generally

  temperatures close to 80 C), the film relaxes

  tantially, and contracts to regain its elastic properties.

  As noted quickly above, the outer layers

  or skins of the composite sheet tend to

  to ferment with the thermocontraction operation of the film in his

  together, because of the inelastic nature of the skins. always

  However, this interference is not of such a degree that it can thwart the heat-shrinking ability of the sheet

  composite. Since the outer layers are not elastic

  ticks, monoaxially energizing the coextruded film

  will also permanently deform its outer layers.

  EXTERIOR. However, the coextruded film as a whole will still relax naturally about 20% to 60% of the elongation length after removal of tensile forces, due to the presence of the elastic core layer, 14. existing intralaminar linkage

  between the outer layers and the core layer is

  preferentially at least 48 g / mm (1200 g / in) for

  that the layers remain laminated against each other

  when subjected to the monoaxial orientation of

up to 700% elongation.

  The use of microwave energy as a means of thermocontraction of both the single layer embodiment and the multilayer film according to the invention is

  also possible. It has been found that, when elasto-

  according to the invention are exposed to microwave energy

  2450 MHz with about 3 to 6 kW for about 5 to 10 seconds.

*, we get the appropriate thermocontraction. Consequently,

  when exposed to microwave energy, the elas-

  tomers shrink from about 20% to about 60% of the

  stretching. For example, a thermal elastomer ribbon

  A particular contractable article according to the invention formed of an extrusion grade pebax core layer 33 coextruded with outer layers of Plexar 102 and monoaxially stretched.

  four times its original length (ie 300% elongation

  to obtain a tape thickness of 0.04 mm (1.5 mils), has at least 20% heat-shrinkage when attached to the inner belt area of a towel, after the

  towel with ribbon was exposed to micro-energy

  2450 MHz waves, with 3 to 6 kW for about 5 to 10 seconds.

  The following examples given as non-limiting,

  illustrate in a complementary manner the invention.

EXAMPLE 1

  Single layer films have been prepared from various commercially available polymers, using

  the cold roll casting method, using a

  the extrusion of 900mm (36in) at temperatures of 200 to 220 C and at linear speeds of about 31m / min for a

  film of 0.05 mm, and about 16 m / min for a film of 0, - mm.

Z563769

  15. The heat-shrinkability of the film samples was examined by preparing strips of 25mm x 250mm film cut in the direction of the machine. The film samples were then labeled at initial lengths of 101.6 mm (4in) and conditioned at 72 F (22.20C) and

  % relative humidity for 24 hours. Following the condition

  nally, samples were individually stretched on

  an Instron Tensile Tester at 72 F (22.2 C) and 55% human

  relative stiffness, up to 100%, 300%, and 500% elongation (ie 2 times, 4 times and 6 times stretching). The initial jaw opening of the Instron Tensile Tester was 112.5 mm (4.5 in) and operated on film lengths of 225 mm (9 in) at 100% elongation, 450 ml ( 18 in) at 300% elongation, and 675mm (27 in) at 500% elongation respectively. In each case, the draw ratio was 1000 mm / min. The stretched samples were then again

  conditioned at 22.20C and 55% relative humidity for 24 hours.

  The permanent deformation was then measured as a percentage of 100 mm (4in) of the original film length, using the formula:% Penangent deformation = Lo - Lf x 100 (1) where LO is the original length of the film and Lf represents the final length at which the film relaxes, without the application of heat, after the applied tension

has been removed.

  To determine the value of thermocontraction dis-

  available to the films, the stretched film samples were then heat-treated by submitting them to

  a temperature of 79.4 C (175 F) for 5 seconds. The length

  Lf of each film sample was then measured

  after thermocontraction, and the percentage of "thermocontrac-

  was calculated using the formula: ## EQU1 ## wherein Lf is the length of the film as defined

  previously about the percentage of permanent deformation.

  In order to determine the elasticity of the thermocured materials, the hysteresis ratio of each sample was calculated using an "Instron Tensile Tester" and equipped with an integration module. In each case, the stretched and heat-treated samples were fixed between the jaws of the "Instron Tensile Tester" to obtain an initial length of 100 mm (4in) regardless of the size of the sample resulting from the thermocontraction. Each sample then

  was stretched 100% at a draw rate of 500 mm per minute.

  Thus, all samples were extended to 200 mm (8in). During the elongation operation, the integration module

  measured the area under the elongation curve and recorded

  the corresponding value. When elongation has been obtained

  At 100%, the integration module has been reset, and

  released the jaws of the Instron "until we have

  found the initial length of 100 mm (4in). During the operation

  of relaxation, the integration module measures the area in-

  written under the relaxation curve. The hysteresis ratio (HR) was then calculated as follows: RH = area under the drawdown curve (3) area under the release curve

  In the measurement of a true elastomer (eg

  the rubber) will have a hysteresis ratio of about 1.0, the measurement of the hysterisis ratios of the films tested.

  provides an indication of their elasticity as a result of

  mocontraction. Thus, single layer films that have a thermocontraction of between about 40% and about 60% or more, and having a hysteresis ratio of less than 2.0, were suitable for use as elastic belts for disposable towels. The results are presented in Table I

TABLE I

  Sample Film Thickness% Deformation% Thermo-Hysteria Ratio

  No. Film 'xtrud6l% permanent elongation contraction rosis (RH) 1 PEBAX2533 0.1 mm 0 - 1, 6 1.4

1.4 2 6 1.3

300 74.2 37, 2 1.3

500 261, 0 63, 9 1.3

2 PEBAX-2533 0.05 mm O - 3, 9 1.4

1, 6 4 9 1.4

300 86.5 42.8 1.3

500 268.0 65.4 1.3

  3 KRATON 2703G1 0.15 mm 0 - 5.1 3.2

6.3 5.2 2 2

300 42.4 3, 3 3'5

500 73.6 5.9 2.4

4 KRATON 2109 0.15 mm 0 - 5 5 1.7

3.5 7 0 1.7

300 18.1 8 4 1.6

500 27.1 7 9 1.5

  Kraton is a nomad of Shell Oil Co.'s Noo IO ICWOTfulD tIOTpoc 'T ap arebt. ap uiou a qso aue l nL

8 0 1 0'Z E '9 005

  So'T O'Z E s OOb LO'I 0'I b Z OOE 'T 0 T 001 ulu OE'O OOLNO;) i' ITOO u C 'O (qOi LNT. L b II' ZZ 9,15 005 Zb I ú, IE b And 00E os 0I 9 b T 001 Co 080'1 5 'O - O uwn so'ozOTl-2NVj fl 9 l 1 6'Zl Ip'b 005 9'1 1' And OO00E

9 '! 9 '11' I 001

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  (Hal) T sp sp .D T------------------------------------------------------------.

EXAMPLE II

  Coextruded multilayer films having a core layer of elastomeric film, and non-elastomeric outer layers

  Tomers were prepared using a combi adapter.

  Classical product, obtained commercially from Cloeren Co., and of the type described in US Pat. 4 152 387, Tests to obtain the percentage of permanent deformation, the percentage of thermocontraction and the ratio of hysteresis

  were conducted as in Example I above, and the results obtained

  States have been grouped together in Table II.

  r ,. % O o cj A; exea xeTch ;: salTGokoD - Sd: Te> Twa4D sdTITq4daP sqildnu nuaqqo 8b auaidTos = auaedToS 9'dioD xaldwaeq ap seqdne nuaqo qC-POuE xaldwaq3 = Ad T'OZ 8'Li L úO1 005 1 'ú TSZ ll'11 OO0 6 '9 9' L Z'I OOI (neKou aqonoz ap% E) 6 ú 9'1 __ 0 tma EL'JO ZA / 60IZ uo; ev2 / 3a 6

LI to P OZZ 'L OOS

  I 's I' s 6 to 06 OOI; E úE 9 z00 (nehou aqDnoD ap% CE 9'0 9'0 0 Ua ú'0 ú. 4d / aua2dtos / gd 8 Hû) upeauff. moon ad.U07ebuol% pxa ffaffl / n2uD; sTspa: [s;, p o s --cua '% uoT4ewmou a% urT np arossTuds / anaT: pco oqnox uolTlrreq urzTj

TABLE II (CONTINUED)

  film Sample outer layer / Film thickness% Deformation% thermnno- Ratio of hysteresis layer Nau / extruded layer% Permanent elongation contraction RH) No ... tery = r __ _ _ _ _ _ __ _ _ _ __ _ _ __ _ _ _ _ _ PE / EVA / Kraton 21093 0.13 mm 0 - 0.6 3.1 (33% core layer) 100 5.5 6.7 2 8

300 58.7 34.7 211

500 71.9 29.9 2.0

  11 Plexar 3 / PEBAX 2533 / 0.10 mm Plexar 3 0 - 0.8 1.75 (90% core layer) 100 4.8 3.5 1.74

300 115.2 43.7 1 53

500 277.0 60.4 1'61

  12 Plexar 3 / PEBAX 2533 / 0.17 mm Plexar 3 0 - 0 8 3.81 (35% core layer) 100 12, 1 8, 2 3.36

300 177.2 43.1 3.63

500 376.0 51.3 4.00

  PE = Chemplex 3404-D; EVA = Chemplex 3312

  4 Plexar 3 Ost a brand name of ChWplex Oo.

rJ, in

TABLE II (CONTINUED)

  film Exterior Sample / Film Thickness% ThermoRatio deformation of hysteresis Extruded No.% Permanent Elongation ontracton (RH)

  13 EVA / PEBAX 2533 / EVA5 0 - 0.6 2.04

  (74% core layer) 0.09 mn 100 4.8 3.6 2.05

300 129.1 46.5 2.35

500 289.0 61.4 2.18

  14 Plexar 3 / PEBAX 3533 / Plexar 30 - 2.6 2.18 (67% core layer) 0.12 min 100 7.5 5.9 2.07

300 160.9 44.7 2.17

500 309.0 56.1 2.30

  Plexar 3 / PEBAX 4033 / Plexar 3 0 - 0.4 3.19 (66% core layer) 0.09 mm 100 14.3 5.6 3.11

300 181.8 34.9 3.81

500 349.0 42.9 4.19

EVA = Chemplex 4634 23.

EXAMPLE III

  Example III corresponds to the repetition of the example

  No. 11, except that Plexar 102 (available commercially from Chemplex Corporation), and Surlyn 1702 (commercially available from DuPont)

  have been used as outer layers according to

  in relative volumes of 10% / 80% / 10% (for: outermost layer

  re / core layer / outer layer, respectively), with a core layer of PEBAX 2533 and 3533. The tests to obtain the percentage of thermocontraction and hysteresis ratio were carried out as in Example Iv and the The results obtained have been grouped together in Table III below, where, as at the end of the year, there is no evidence that this is the case with the Zola ApfnSvv LAu. daoD xaidwagqD ap sqadnu luauaITDoaBulooD aIqTuodsTp aaluouoT auTsgi aun qsa Z0O jexaTd 06 '[Is 99Z 00S 99t [6E 001'

9 'I ZS 69Z 009

  9L oz oo L80 89 SZ Ozi 000 SZ1 6Z1 ZS 6LI 00tO ZOT / 8x0ld / E90 'Zt 500 um9 80'0 úESE-xeqad / Z0olleXld l81

GI 'I 19 99Z OOS

  9Z 'zs 6LI 001 9z' EL 'ZOT OOE (0T / 08 / 0T> iz THE 00E ** 40L1 U * 41JlS / E6' 1 9 s 001 and oo EESZ-xeqad / zOLi UÈArlnLi IL - issTs LLE 00

'Z EL' ç9 001 '

E6't I, P 9TRE 1't 00Eoa% (01/08/01)

ú6, -T 9C OOE9 S

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25.

  From the examples above, it appears clear that

  that both single layer films and films

  coextruded Pebax show satisfactory results in

  percent of thermocontractability (between about 30 and 70%), when stretched to elongation values included

  between 200% and about 500% so that when they are

  plicated for example to belts of towels

  tables, we obtain a satisfactory frown. For the majority

  of the films tested, the percentage of thermocontractability de-

  believes when the film elongation percentage increases by 300%

  at 500% whereas, conversely, the films according to the invention increase

  their percentage of thermocontraction when the elongation

  The film thickness increases from 300% to 500% (compare, for example, samples 4-5 and 1-2, 8-10O and 11-19). The samples n

  3 and 6, although growing slightly as a percentage of

  contractability do not have the thermocontrac-

  required for elastic gathering articles. So,

  the films of the present invention now make it economically

  It is also possible to produce disposable napkins with elastic waistbands that have a sufficient amount of heat-treatability to obtain adequate crimping. In addition, the films of the present invention overcome many of the commercial and production disadvantages of conventional thermocontractable elastomers, since no thermoforming is required to achieve the benefits described above. 26.

Claims (12)

REVENDICATIQNS   1) Method of manufacturing a thermo-plastic elastomer   tractable device comprising the steps of: (a) orienting in the monoaxial direction, over a first length, an elastomer consisting mainly of a copolymer   having polymer segments, in repeated blocks of   lyamide and polyether alternatively, said direction of o-   rientation being carried out, without the application of external heat, by orienting said elastomer monoaxially for a second   length substantially greater than a third length   which involves a permanent deformation of said elastomer; (b) releasing the monoaxial voltage applied in step (a) to allow said elastomer to relax naturally and stabilize at said third length   substantially greater than said first length.   2) Method according to claim 1, characterized in that said elastomer is oriented monoaxially beyond an elongation of about 200% to reach said second length. 30) Method according to claim 1, characterized in that said elastomer is oriented monoaxially on an elongation of about 200% to about 700%, to obtain said second length.   4) Method according to claim 1, characterized in that said third length is between about   and about 60% of said second length.    Method according to claim 1, characterized in that said elastomer undergoing said steps (a) and (b) comprises outer layers of a non-elastomeric material, and a core layer placed between said outer layers, consisting essentially of segments of polymers blocks   repeated polyamide and polyether alternately.   6) Method according to claim 5, characterized in that before step (a) is carried out a step of forming said elastomer by hot rolling said core and said 2-7. outer layers.   7) Method according to claim 5, characterized in that said core layer consists of said elastomer   in a proportion of about 70% to about 90% by weight.   8) Method according to any one of the claims   from 1 to 7, characterized by the fact that it includes the step   (c) thermocontracting said elastomer.   9) Method according to claim 8, characterized   in that step (c) is carried out by microwave energy.   10) Method according to claim 5, characterized in that said third length is between approximately   and about 60% of said second length.   11) Method according to claim 5, characterized   in that said step O) is carried out in such a way as to orient   said elastomer to a second length of between about 200% and about 700% of the said first length.   12) Method according to claim 8, characterized in that said copolymer or said core layer respectively, have the formula: HO -RH1- -OR2- H -not   wherein R1 is a polyamide selected from the group   taking nylon (6) nylon (10), nylon (11), nylon 412), and nylon (6,6); R2 is a polyether selected from the group consisting of polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; and n is an integer. 130) Application of the method according to claim 1 to a method of manufacturing an article with elastic gathered pleats portion, said method comprising the steps of: (a) forming a thermocontractable elastomer, by orienting an elastomer of a first length consisting essentially of a copolymer formed of segments 28.   of alternating polyamide and polyether alumina blocks   ternatively, said orientation being realized, without application   external heat, for orienting said elastomer monoaxially to a second length substantially greater than a third length in which a permanent deformation occurs, and reloading the monoaxial orientation to allow the elastomer to relax naturally and stabilize: at said third length, substantially greater than said first length; (b) attaching the elastomer fixed according to step (a) to the portion of the article.   ) Application according to claim 13, characterized   in that the method of manufacturing said article comprises the following complementary steps:   (c) fixing the elastomer formed according to the   (a) on said portion of the article is made in a direction approximately parallel to the desired direction of crimping and   (d) a thermocontraction operation is carried out   said elastomer so-fixed to elastically frolic said portion of the article.   ) Application according to claim 14, characterized   in that step (d) is performed by energy half cro -] des.   160) Elastic frosting portion article,   characterized in that it comprises a heat-treated elastomer attached to said article, and produced according to one of the claims from 1 to 15.   17) An article according to claim 16, characterized in that the elastomer attached to said article has then been subjected to heat to heat-seal said elastomer and thereby frown said portion to which said elastomer is fixed.