Method of attaching a composite elastic material to an article

A method for attaching a composite elastic material to a gatherable article including the steps of stretching a composite elastic material; compressing said stretched composite elastic material to temporarily inhibit recovery of the composite elastic material; and attaching said temporarily inhibited composite elastic material to a gatherable article at least at two locations. Additionally, the temperature of the temporarily inhibited composite elastic material may be increased to facilitate recovery of the composite elastic material to within about 80 percent of its pre-stretched dimensions.

FIELD OF THE INVENTION 
The present invention relates to a method for attaching a composite elastic 
material to an article. Generally speaking, the present invention relates 
to a method for attaching a stretched composite elastic material to a 
gatherable article. 
BACKGROUND OF THE INVENTION 
Elastic materials have been attached to articles or garments such as, for 
example, disposable diapers at locations such as the waist and/or leg 
openings. The elastic materials are often stretched, attached to a 
gatherable article while in the stretched state and allowed to recover to 
their normal, prestretched state causing the gatherable article to pucker 
or shirr. Articles or garments elasticized in this manner may be expanded 
by the body of a wearer or the surface of an item to be covered. The 
resistance of the article to expansion will cause a snug fit between the 
article and the body or item to be covered at the location where the 
article contacts the body or item to be covered. Snug fitting locations 
may be desirable in products such as, for example, disposable diapers, 
medical garments, work-wear garments and feminine care products. 
Applying stretched, actively elastic materials to a conformable or 
gatherable article is difficult because the elastic materials must be 
maintained in a stretched condition during at least part of the 
application process. Methods of temporarily inactivating stretched elastic 
material by freezing the elastic material have been developed. The frozen 
elastic material is attached to a gatherable substrate and then 
reactivated by heat so that it returns to its normal, pre-stretched 
condition. Additionally, heat shrinkable elastic materials have been 
developed which may be applied to a conformable substrate and heated to 
cause the elastic material to heat-shrink producing puckers and shirrs in 
the laminate. 
DEFINITIONS 
The term "elastic" is used herein to mean any material which, upon 
application of a biasing force, is stretchable, that is, elongatable, to a 
stretched, biased length which is at least about 125 percent, that is 
about one and one quarter, of its relaxed unbiased length, and which, will 
recover at least 40 percent of its elongation upon release of the 
stretching, elongating force. A hypothetical example would be a one (1) 
inch sample of a material which is elongatable to at least 1.25 inches and 
which, upon being elongated to 1.25 inches and released, will recover to a 
length of not more than 1.15 inches. Many elastic materials may be 
stretched by much more than 25 percent of their relaxed length, for 
example, 100 percent or more, and many of these will recover to 
substantially their original relaxed length, for example, to within 105 
percent of their original relaxed length, upon release of the stretching 
force. 
As used herein, the term "nonelastic" refers to any material which does not 
fall within the definition of "elastic," above. 
As used herein, the term "recover" refers to a contraction of a stretched 
material upon termination of a biasing force following stretching of the 
material by application of the biasing force. For example, if a material 
having a relaxed, unbiased length of one (1) inch is elongated 50 percent 
by stretching to a length of one and one half (1.5) inches the material 
would be elongated 50 percent (0.5 inch) and would have a stretched length 
that is 150 percent of its relaxed length. If this exemplary stretched 
material contracted, that is recovered to a length of one and one tenth 
(1.1) inches after release of the biasing and stretching force, the 
material would have recovered 80 percent (0.4 inch) of its one-half (0.5) 
inch elongation. 
The term "composite elastic material" as used herein refers to a multilayer 
material having at least one elastic layer joined to at least one 
gatherable layer at least at two locations wherein the gatherable layer is 
gathered between the locations where it is joined to the elastic layer. A 
composite elastic material may be stretched to the extent that the 
nonelastic material gathered between the bond locations allows the elastic 
material to elongate. This type of composite elastic material is 
disclosed, for example, by Vander Wielen et al., U.S. Pat. No. 4,720,415 
issued Jan. 19, 1988, which is hereby incorporated by reference. 
The term "percent elongation" as used herein refers to a ratio determined 
by measuring the difference between the extended dimension and unextended 
dimension of a composite elastic material and dividing that difference by 
the unextended dimension of the composite elastic material. 
The term "percent extension" as used herein refers to a ratio determined by 
measuring the difference between the stretch-to-stop or maximum extension 
and the unextended dimension of a composite elastic material and dividing 
that difference by the unextended dimension of the composite elastic 
material. 
The term "total recovery" as used herein refers to the recovery of a 
stretched composite elastic material to generally within about 20 percent 
of its relaxed, pre-stretched dimensions. 
The term "temporarily inhibit" as used herein refers to a delay in the 
total recovery of a stretched composite elastic material. The delay may be 
imparted by compressing the stretched composite elastic material so that 
the elastic and gatherable layers are temporarily joined. Partial recovery 
of a temporarily inhibited composite elastic material may occur 
immediately after the stretching force is removed from the composite 
elastic material but total recovery of such a temporarily inhibited 
composite elastic material will require more time than the total recovery 
of the same material which has not been temporarily inhibited. For 
example, total recovery of a stretched composite elastic material which 
has not been temporarily inhibited may be instantaneous but total recovery 
of a temporarily inhibited composite elastic material may take, for 
example, from about 5 to about 60 seconds. 
As used herein, the term "nonwoven web" means a web having a structure of 
individual fibers or threads which are interlaid, but not in an 
identifiable, repeating manner. Nonwoven webs have been, in the past, 
formed by a variety of processes such as, for example, meltblowing 
processes, spunbonding processes and bonded carded web processes. 
As used herein, the term "microfibers" means small diameter fibers having 
an average diameter not greater than about 100 microns, for example, 
having a diameter of from about 0.5 microns to about 50 microns, or more 
particularly, microfibers may have an average diameter of from about 4 
microns to about 40 microns. 
As used herein, the term "meltblown fibers" means fibers formed by 
extruding a molten thermoplastic material through a plurality of fine, 
usually circular, die capillaries as molten threads or filaments into a 
high velocity gas (e.g. air) stream which attenuates the filaments of 
molten thermoplastic material to reduce their diameter, which may be to 
microfiber diameter. Thereafter, the meltblown fibers are carried by the 
high velocity gas stream and are deposited on a collecting surface to form 
a web of randomly disbursed meltblown fibers. Such a process is disclosed, 
for example, in Butin U.S. Pat. No. 3,849,241, the disclosure of which is 
hereby incorporated by reference. 
As used herein, the term "spunbonded fibers" refers to small diameter 
fibers which are formed by extruding a molten thermoplastic material as 
filaments from a plurality of fine, usually circular, capillaries of a 
spinnerette with the diameter of the extruded filaments then being rapidly 
reduced as by, for example, eductive drawing or other well-known 
spun-bonding mechanisms. The production of spun-bonded nonwoven webs is 
illustrated in patents such as, for example, in Appel et al. U.S. Pat. No. 
4,340,563 and Dorschner et al. U.S. Pat. No. 3,692,618. The disclosures of 
these patents are hereby incorporated by reference. 
As used herein, the term "sheet" means a layer which may either be a film 
or a nonwoven web. 
As used herein, the term "palindromic laminate" means a multilayer 
laminate, for example, a composite elastic material which is substantially 
symmetrical. Exemplary palindromic laminates would have layer 
configurations of A/B/A, A/B/B/A, A/A/B/B/A/A, etc. Exemplary 
non-palindromic laminates would have layer configurations of A/B/C, 
A/B/C/A, A/C/B/D, etc. 
As used herein, the term "polymer" generally includes, but is not limited 
to, homopolymers, copolymers, such as, for example, block, graft, random 
and alternating copolymers, terpolymers, etc. and blends and modifications 
thereof. Furthermore, unless otherwise specifically limited, the term 
"polymer" shall include all possible geometrical configurations of the 
material. These configurations include, but are not limited to, isotactic, 
syndiotactic and random symmetries. 
As used herein, the term "consisting essentially of" does not exclude the 
presence of additional materials which do not significantly affect the 
desired characteristics of a given composition or product. Exemplary 
materials of this sort would include, without limitation, pigments, 
antioxidants, stabilizers, surfactants, waxes, flow promoters, solid 
solvents, particulates and materials added to enhance processability of 
the composition. 
SUMMARY OF THE INVENTION 
The present invention provides a method for attaching a composite elastic 
material to a gatherable article including the steps of: 
stretching a composite elastic material; 
compressing the stretched composite elastic material to temporarily inhibit 
total recovery of the composite elastic material; and 
attaching the temporarily inhibited composite elastic material to the 
gatherable article at least at two locations. 
The method may further include the step of increasing the temperature of 
the temporarily inhibited composite elastic material to facilitate 
recovery of the stretched composite elastic material to about 80 percent 
of its pre-stretched dimensions. 
The composite elastic material includes at least one gatherable layer 
joined to at least one elastic sheet at least at two locations, with the 
gatherable layer being gathered between the two locations. The gatherable 
layer may be a film or a web such as, for example, a bonded carded web, a 
spunbonded web, a meltblown web. The gatherable layer may be made of 
polymers such as, for example, polyolefins, polyesters and polyamides. For 
example, the polyolefins may be one or more of polyethylene, 
polypropylene, polybutene, ethylene copolymers, propylene copolymers and 
butene copolymers. Alternatively, the gatherable layer may be a layer of 
crepe wadding, tissue or other pulp-based material. The present invention 
also provides that the basis weight of the gatherable layer should be at 
least about 5 grams per square meter (gsm), for example, from about 5 gsm 
to about 100 gsm. 
The elastic sheet may be a pressure sensitive elastomer adhesive sheet. If 
the sheet is a nonwoven web of elastic fibers or pressure sensitive 
elastomer adhesive fibers, the fibers may be meltblown fibers. The 
meltblown fibers may include meltblown microfibers. The elastic sheet 
should be adapted to attach to the gatherable layer with a cohesive force 
of from about 3 to about 11 kilograms. 
In one aspect of the present invention, the composite elastic material is 
stretched so that the gatherable layer is partially or fully extended 
between the locations where it is joined to the elastic sheet before the 
composite elastic material is compressed. 
According to the present invention, the composite elastic material is 
temporarily inactivated by nipping the stretched material at a pressure of 
from about 300 to about 1500 pounds per linear inch (pli). Greater 
pressures may be used if they do not degrade the composite elastic 
material. 
In another aspect of the present invention, a post-nip chill roll may be 
used to enhance the temporary inactivation achieved by nipping the 
material. The chill roll may be chilled to a temperature in the range from 
about 60.degree. F. to about 33.degree. F.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to the drawings where like reference numerals represent like 
materials or process steps and, in part, to FIG. 1, there is schematically 
illustrated at 10 a method for applying a composite elastic material 12 to 
a gatherable article. 
A composite elastic material 12 is unwound from supply roll 14 of the 
composite elastic material. The composite elastic material 12 then travels 
in the direction indicated by the arrow associated therewith as a supply 
roll 14 rotates in the direction of the arrow associated therewith. 
The composite elastic material 12 then passes through a nip 16 of an S-roll 
arrangement 18 formed by the stack rollers 20 and 22. Alternatively, 
individual components of the composite elastic material 12 may be formed 
by processes, such as, for example, spunbonding, meltblowing, film 
extrusion or bonded carded web processes, joined to form the elastic 
composite material 12 and then and passed directly through the nip -6 
without first being stored on a supply roll. 
The composite elastic material 12 passes through the nip 16 of the S-roll 
arrangement 18 in a reverse-S wrap path as indicated by the rotation 
direction arrows associated with the stack rollers 20 and 22. From the 
S-roll arrangement 18, the composite elastic material 12 passes through 
the nip 24 of a pressure nip roller arrangement 26 formed by the nip 
rollers 28 and 30. Because the peripheral linear speed of the stack 
rollers 20 and 22 of the S-roll arrangement 18 is controlled to be lower 
than the peripheral linear speed of the nip rollers 28 and 30 of the 
pressure nip roller arrangement 26, the composite elastic material 12 is 
tensioned between the S-roll arrangement 18 and the compression nip roller 
arrangement 26. By adjusting the difference in the speeds of the rollers, 
the composite elastic material 12 is tensioned so that it stretches a 
desired amount and is maintained in such stretched condition as it passes 
through the nip 24 of the compression nip roller arrangement 26. The nip 
rollers 28 and 30 are configured to compress the stretched composite 
elastic material 12 to temporarily inhibit total recovery. 
A chill roll 32 may be used to enhance the temporary inactivation achieved 
by compressing the composite elastic material 12. Idler rolls 34 and 36 
are used to maintain contact between the temporarily inactivated composite 
elastic material 12 and the chill roll 32. The temporarily inactivated 
material 12 is chilled while it contacts the surface of chill roll 32 
causing an increase the period of inactivation. Temporary inactivation may 
be prolonged, for example, from about 2 to about 5 seconds by contact with 
the chill roll 32 for a period of about 1/4 to about 11/2seconds. Greater 
contact times will result in longer periods of inactivation. Chill roll 32 
is maintained at a temperature lower than temperature of the temporarily 
inactivated material. Lower temperatures will also result in longer 
periods of inactivation. For example, temperatures from about 60.degree. 
F. to about 33.degree. F. have been found practical although lower 
temperatures may be used. 
The temporarily inhibited composite elastic material 12 may then be 
attached to a gatherable article 50 utilizing, for example, adhesives from 
an adhesive applicator 52 or stitching from a stitchbonding apparatus 54. 
Conventional drive means and other conventional devices which may be 
utilized in conjunction with the apparatus of FIG. 1 are well known and, 
for purposes of clarity, have not been illustrated in the schematic view 
of FIG. 1. 
Referring now to FIG. 2, there is illustrated a cross-sectional view of a 
composite elastic material 60 in the stretched configuration to depict the 
structure of the multilayer material. The composite elastic material 
includes gatherable layers 62 and 66 joined to each side of an elastic 
sheet 72. Gatherable layers 62 and 66 are joined to the elastic sheet 72 
at bond points 68. The gathers are not shown in FIG. 2 because the 
laminate is shown in a stretched condition due to application of 
tensioning force in the directions of the arrows 74 and 76. FIG. 3 is a 
cross-sectional view of the composite elastic material 60 shown in FIG. 2. 
Gathers 64 are present in FIG. 3 because the laminate 60 is depicted in a 
relaxed or unstretched condition. The gathers 64 result from the gathering 
of gatherable layers 62 and 66 between bond points 68 where the gatherable 
layers 62 and 66 are joined to the elastic sheet 72. Such a composite 
elastic material is commonly referred to as a "stretch-bonded laminate". 
The composite elastic material 60 may include one or more layers of 
gatherable material joined to one or more layers of an elastic sheet. The 
multiple layers may be arranged to form a palindromic laminate. The basis 
weight of the composite elastic material in its relaxed, pre-stretched 
condition may range from about 50 gsm to about 250 gsm. A basis weight of 
about 165 gsm has been found to be particularly useful. 
The elastic sheet 72 itself may be a multilayer material in that it may 
include two or more individual coherent webs or films. Additionally, the 
elastic sheet 72 may be a multilayer material in which one or more of the 
layers contain a mixture of elastic and nonelastic fibers and/or 
particulates. An example of the latter type of elastic web, reference is 
made to U.S. Pat. No. 4,209,563, incorporated herein by reference, in 
which elastomeric and non-elastomeric fibers are commingled to form a 
single coherent web of randomly dispersed fibers. Another example of such 
a composite web would be one made by a technique such as disclosed in 
Richard A. Anderson et al. U.S. Pat. No. 4,100,324, issued July 11, 1978 
and also incorporated herein by reference. That patent discloses a 
nonwoven material which includes a mixture of meltblown thermoplastic 
fibers and other materials which are combined in the gas stream in which 
the meltblown fibers are borne so that an intimate entangled commingling 
of meltblown thermoplastic fibers and other materials, e.g., wood pulp, 
staple fibers or particulates such as, for example, hydrocolloid 
(hydrogel) particulates commonly referred to as super-absorbents occurs 
prior to collection of the fibers upon a collecting device to form a 
coherent web of randomly dispersed fibers. 
The elastic sheet 72 may be made from any material which may be 
manufactured in sheet form. Generally, any suitable elastomeric fiber 
forming resins or blends containing the same may be utilized for the 
nonwoven webs of elastomeric fibers of the invention and any suitable 
elastomeric film forming resins or blends containing the same may be 
utilized for the elastomeric films of the invention. 
For example, the elastic sheet 72 may be made from elastomeric block 
copolymers having the general formula A-B-A' or A-B, where A and A' are 
each a thermoplastic polymer endblock which contains a styrenic moiety 
such as a poly (vinyl arene) and where B is an elastomeric polymer 
midblock such as a conjugated diene or a lower alkene polymer. Block 
copolymers of the A-B-A' type can have different or the same thermoplastic 
block polymers for the A and A' blocks, and the present block copolymers 
are intended to embrace linear, branched and radial block copolymers. In 
this regard, the radial block copolymers may be designated (A-B).sub.m -X, 
wherein X is a polyfunctional atom or molecule and in which each 
(A-B).sub.m - radiates from X in a way that A is an endblock. In the 
radial block copolymer, X may be an organic or inorganic polyfunctional 
atom or molecule and m is an integer having the same value as the 
functional group originally present in X. It is usually at least 3, and is 
frequently 4 or 5, but not limited thereto. Thus, in the present 
invention, the expression "block copolymer", and particularly "A-B-A'" and 
"A-B" block copolymer, is intended to embrace all block copolymers having 
such rubbery blocks and thermoplastic blocks as discussed above, which can 
be extruded (e.g., by meltblowing), and without limitation as to the 
number of blocks. The elastic sheet 72 may be formed from, for example, 
elastomeric (polystyrene/poly(ethylene-butylene)polystyrene) block 
copolymers available from the Shell Chemical Company under the trademark 
KRATON G. One such block copolymer may be, for example, KRATON G-1657. 
Other exemplary elastomeric materials which may be used as the elastomeric 
polymer in the blend include polyurethane elastomeric materials such as, 
for example, those available under the trademark ESTANE from B. F. 
Goodrich & Co., polyamide elastomeric materials such as, for example, 
those available under the trademark PEBAX from the Rilsan Company and 
polyester elastomeric materials such as, for example, those available 
under the trade designation Hytrel from E. I. DuPont De Nemours & Company. 
Formation of elastic sheets from polyester elastic materials is disclosed 
in, for example, Morman et al. U.S. Pat. No. 4,741,949, hereby 
incorporated by reference. 
A polyolefin may also be blended with the elastomeric polymer to improve 
the processability of the composition. The polyolefin must be one which, 
when so blended and subjected to an appropriate combination of elevated 
pressure and elevated temperature conditions, is extrudable, in blended 
form, with the elastomeric polymer. Useful blending polyolefin materials 
include, for example, polyethylene, polypropylene and polybutene, 
including ethylene copolymers, propylene copolymers and butene copolymers. 
Two or more of the polyolefins may be utilized. Extrudable blends of 
elastomeric polymers and polyolefins are disclosed in, for example, 
Wisneski et al. U.S. Pat. No. 4,663,220, hereby incorporated by reference. 
A particularly useful polyethylene may be obtained from U.S.I. Chemical 
Company under the trade designation Petrothene NA601 (also referred to 
herein as PE NA601). Information obtained from U.S.I Chemical Company 
states that PE NA601 is a low molecular weight, low density polyethylene 
for application in the areas of hot melt adhesives and coatings. U.S.I. 
has also stated that PE NA601 has the following nominal values: (1) a 
Brookfield viscosity, cP at 150.degree. C. of 8,500 and at 190.degree. C. 
of 3,300 when measured in accordance with ASTM D 3236; (2) a density of 
0.903 grams per cubic centimeter when measured in accordance with ASTM D 
1505; (3) and equivalent Melt index of 2,000 grams per 10 minutes when 
measured in accordance with ASTM D 1238; (4) a ring and ball softening 
point of 102.degree. C. when measured in accordance with ASTM E 28; (5) a 
tensile strength of 850 pounds per square inch when measured in accordance 
with ASTM D 638; (6) an elongation of 90% when measured in accordance with 
ASTM D638; (7) a modulus of rigidity, T.sub.F (45,000) of -34.degree. C; 
and (8) a penetration hardness (tenths of mm) at 77.degree. F. 
(Fahrenheit) of 3.6. Another useful polyethylene is identified by the 
trade designation EPOLENE C-10 and may be obtained from the Eastman 
Chemical Company. Specific information about the material may be obtained 
from the manufacturer. 
The elastic sheet 72 is a pressure sensitive elastomer adhesive sheet. For 
example, the elastic material itself may be tacky or, alternatively, a 
compatible tackifying resin may be added to the extrudable elastomeric 
compositions described above or an adhesive may be applied to the elastic 
sheet to provide an elastic sheet that can act as a pressure sensitive 
adhesive. Although the inventors should not be held to a particular theory 
of operation, it is believed that the tackiness of the elastic sheet 72 
causes temporary bonding of the stretched elastic sheet 72 to the 
gatherable layers 62 and 66 after compression so that the elastic sheet 72 
is temporarily inhibited from recovering to its pre-stretched dimensions. 
In regard to the tackifying resins and tackified extrudable elastomeric 
compositions, note the resins and compositions as described in U.S. patent 
application Ser. No. 919,901, now J. S. Keiffer and T. J. Wisneski U.S. 
Pat. No. 4,789,699, filed Oct. 15, 1986 for "Ambient Temperature Bondable 
Elastomeric Nonwoven Web", hereby incorporated by reference. Any tackifier 
resin can be used which is compatible with the elastomeric polymer and can 
withstand the high processing (e.g., extrusion) temperatures. If blending 
materials such as, for example, polyolefins or extending oils are used, 
the tackifier resin should also be compatible with those blending 
materials. Generally, hydrogenated hydrocarbon resins are useful 
tackifying resins because of their better temperature stability. 
REGALREZ.TM. 1126 and ARKON.TM. P series tackifiers are examples of 
hydrogenated hydrocarbon resins. ZONATAK.TM. 501 lite is an example of a 
terpene hydrocarbon. Of course, the present invention is not limited to 
use of such three tackifying resins, and other tackifying resins which are 
compatible with the composition and can withstand the high processing 
temperatures, can also be used. 
REGALREZ hydrocarbon resins are available from Hercules Incorporated. 
Grades 1094, 3102, 6108 and 1126 are highly stable, light-colored, low 
molecular weight, nonpolar resins suggested for use in plastics 
modification, adhesives, coatings, sealants and caulks. The resins are 
compatible with a wide variety of oils, waxes, alkyds, plastics and 
elastomers and are soluble in common organic solvents. Product 
specifications of the above-mentioned grades of REGALREZ resin and 
compatibility information are set forth in Tables 1 and 2. 
ARKON P series resins are available from Arakawa Chemical (U.S.A.), Inc., 
and are synthetic tackifying resins for pressure sensitive adhesives which 
are based on hydrocarbon resins. The general properties of ARKON P series 
resins are set forth in Table 3. 
The components of the blends utilized in the present invention may be 
present over broad ranges of the amounts of each component, such amounts 
being easily determined by one of ordinary skill in the art. As a guide, 
when utilizing an A-B-A block copolymer, a polyolefin, and a resin 
tackifier as the three components of the extrudable composition, the 
following broad and preferred ranges, as shown in Table 4, are exemplary. 
It is emphasized that these ranges are merely illustrative, serving as a 
guide for amounts of the various components in the composition. 
As stated previously, while the present invention has been discussed in 
terms of a three-component extrudable composition of (1) elastomeric 
polymer; (2) polyolefin; and (3) resin tackifier, the polyolefin, which 
functions as a viscosity-reducer for the total composition, can be 
substituted by other compatible viscosity reducers, or can be eliminated 
altogether where the tackifying resin can also act as the viscosity 
reducer. For example, low molecular weight hydrocarbon resin tackifiers 
such as, for example, REGALREZ 1126 can also act as the viscosity reducer, 
whereby the extrudable composition can be comprised of the elastomeric 
polymer and tackifying resin (e.g., REGALREZ 1126). 
While the principle components of the elastic sheet 12 have been described 
as the foregoing, the elastic sheet is not limited to only those 
components and may include other components that do not adversely affect 
the desired properties of the elastic sheet. Exemplary materials which 
could be used as additional components would include, without limitation, 
pigments, antioxidants, stabilizers, surfactants, waxes, flow promoters, 
solid solvents, particulates and materials added to enhance processability 
of the composition. 
The elastic sheet 72 may be a nonwoven web (e.g., a film, porous film, or 
fibrous nonwoven web) formed by extrusion techniques. For example, the 
elastic sheet 72 may be formed by meltblowing a blend including about 63% 
by weight KRATON G-1657 block copolymer, about 20% Polyethylene NA601 and 
about 17% REGALREZ 1126 tackifying resin having a melt flow of from about 
12 grams per ten minutes to about 18 grams per ten minutes when measured 
at 190.degree. C. and under a 2160 gram load; an elongation of about 750%; 
a modulus of elongation at 100% of from about 155 to about 200 psi; and a 
modulus of elongation at 300% of from about 200 to about 250 psi. More 
particularly, the blend may have a melt flow of about 15 grams per ten 
minutes when measured at 190.degree. C. and under a 2160 gram load; an 
elongation of about 750%; a modulus of elongation at 100% of about 175 
psi; and a modulus of elongation at 300% of about 225 psi. The blend may 
be meltblown at a temperature of from about 500 to about 600.degree. F. 
If the elastic sheet 72 is an elastic nonwoven web, the basis weight of the 
web may range from about 40 to about 200 gsm. Basis weights of about 85 to 
about 110 gsm are particularly useful. If the elastic sheet 72 is a film, 
the film may range in thickness from about 1 to about 4 mils. 
Various gatherable materials can be utilized and are discussed, for 
example, in previously referenced U.S. Pat. No. 4,720,415. 
The gatherable materials can include, but are not limited to non-elastic 
nonwoven webs such as, for example, bonded carded non-elastic polyester or 
non-elastic polypropylene fiber web, spunbonded non-elastic polyester or 
polypropylene non-elastic fiber web, non-elastic cellulosic fiber webs, 
e.g., cotton fiber webs, polyamide fiber webs, e.g., nylon 6-6 webs, and 
blends of two or more of the foregoing. Additionally, crepe wadding, 
tissue or other pulp-based materials may be used. The desirable basis 
weight of the gatherable webs depends upon various factors including the 
retraction force of the elastic sheet and the desired retraction by the 
elastic sheet. The gatherable material should have sufficient stiffness so 
that it can resist the retraction force of the elastic sheet when the 
stretched elastic sheet is temporarily bonded to the gatherable web. 
Exemplary, and not limiting, basis weight values for the gatherable web 
are from about 5 to about 100 grams per square meter (gsm), for example, 
from about 10 to about 30 gsm. Generally, elastic sheets having greater 
retraction forces will require gatherable webs having greater basis 
weights. 
Composite elastic materials such as, for example, stretch-bonded laminates 
may have a maximum elongation or stretch-to-stop which is affected by the 
amount of inelastic gatherable material gathered between the locations 
where the gatherable material is joined to the elastic sheet. When the 
gatherable material is fully extended the composite elastic material can 
be described as reaching its maximum or 100 percent extension. When 
extended beyond its maximum extension, the inelastic gatherable material 
necks or constricts causing undesirable product attributes or breaks 
causing disruptions in the manufacturing process. When the extension of 
the composite elastic material is controlled to be equal or slightly lower 
than the maximum extension, necking and breaks are minimized. 
Additionally, material usage, product attributes and process efficiency 
are maximized. 
Illustrated at FIG. 4 is an exemplary force versus extension curve for a 
typical stretch-bonded laminate. The tensioning force required to extend 
the stretch-bonded laminate to its maximum elongation may be determined by 
plotting the tension versus elongation of a stretch-bonded laminate to 
identify curve A. The tension required for maximum extension may be found 
in the general range of tension force values corresponding to the region B 
where there is a substantial increase in the slope of curve A, i.e., the 
point of inflection. 
With regard to the tension used to fully extend the composite elastic 
material, one skilled in the art will appreciate that the tension which is 
applied for maximum extension will depend not only on the type of 
elastomeric polymer, tackifying resin or other components of the elastic 
sheet but also on the basis weights of the elastic materials, the process 
used to make the material and the stretch characteristics of the material. 
However, for a given elastic material, and in view of the herein contained 
disclosure the processing conditions necessary to achieve satisfactory 
extension of the elastic sheets can be readily determined by one of skill 
in the art. 
The stretched composite elastic material 12 may be nipped utilizing various 
combinations of nip rollers such as, for example, roller arrangements 
combining rubber/steel, nylon/steel or steel/steel rollers. Nip roller 
combinations such as rubber (Shore A 100)/steel nip rollers have been 
operated at a pressure of from about 350 to about 700 pounds per linear 
inch to inactivate a composite elastic material. In general, greater 
pressures will result in longer periods of inactivation. However, some 
rubber rollers tend to heat up when operated at high pressures and/or 
speeds. Steel rollers may be used at pressures of from about 500 to about 
1500 pounds per linear inch to inactivate a composite elastic material. 
Particularly useful results have been achieved at pressures between about 
950 and 1100 pounds per linear inch. Greater pressures may be used with 
the upper limit being pressures at which the elastic material begins to 
degrade. 
With regard to the pressure used to temporarily inactivate the stretched 
elastic sheet, one skilled in the art will appreciate that the pressures 
at which the materials are subjected to for inactivation will depend not 
only on the type of elastomeric polymer, tackifying resin or other 
components of the elastic sheet but also on the degree of stretching of 
the elastic sheet, the basis weights of the materials, the residence time 
of the materials in the nip of the compression rolls and the specific 
materials used in the compression rolls. However, for a given combination 
of materials and in view of the herein contained disclosure the processing 
conditions necessary to achieve satisfactory temporary inactivation of the 
stretched elastic sheets can be readily determined by one of skill in the 
art. 
The nip rollers utilized to compress the composite elastic material should 
be maintained at a temperature ranging from about 60.degree. F. to about 
100.degree. F. In particular, useful results have been obtained when the 
nip rollers were maintained at ambient temperature, i.e., about 70.degree. 
F. The use of a chilled post-nip roll has also been found to prolong 
temporary inactivation of the compressed composite elastic material. 
The tackiness of the elastic sheet also affects the ability of the 
composite elastic material to be inactivated. When compressed, the elastic 
sheet should be adapted to adhere to the gatherable layer with a cohesive 
force of from about 3 kilograms to about 11 kilograms, for example, from 
about 7 to about 9 kilograms. The elastic sheet itself may be tacky or an 
adhesive may be applied to the elastic sheet or the gatherable material. 
If the elastic sheet itself is tacky, the tackiness may be from the 
inherent tackiness of the material used to form the sheet. 
Alternatively, an adhesive or tackifier may be blended with the elastic 
material used to make the elastic sheet to provide or increase tackiness. 
Generally, larger amounts of tackifier added to the blend result in 
greater tackiness of the elastic sheet and correspondingly longer period 
of inactivation when the elastic sheet compressed. However, too much 
tackifier degrades the stretch properties of the elastic sheet. 
The composite elastic material 60 may be attached to a gatherable article 
at least at two locations by means such as, for example, adhesives, 
hot-melt adhesives, stitchbonding, ultrasonic bonding, and pressure and/or 
thermal spot bonding. If composite elastic material 60 is a two-layer 
laminate having an elastic surface and a gatherable material surface, the 
elastic surface may be attached directly to the gatherable article at 
least at two locations. If the gatherable material surface of composite 
elastic material 60 is attached directly to the gatherable article, the 
gatherable material surface may be completely bonded to the gatherable 
article. 
Once the stretched and inactivated composite elastic material is attached 
to the gatherable article, the composite elastic material may be 
reactivated by raising the temperature of the composite elastic material 
so that it recovers to its relaxed, pre-stretched state. The temporarily 
inhibited composite elastic material will recover almost instantaneously 
to its relaxed, prestretched dimensions once the temperature of the sheet 
is raised to detach the temporary bonds between the elastic sheet and the 
gatherable material of the composite elastic material. If not heated, the 
temporary bonds will slowly detach at room temperatures and the 
temporarily inactivated material will recover to its pre-stretched 
dimensions. 
The temperature may be raised any suitable radiant, convective or 
conductive heating means such as, for example, forced hot air, infrared 
heat lamps, contact with a heated surface and/or a heated liquid. The 
temperature change required to reactivate the elastic sheet may vary 
according to factors such as, for example, the basis weight of the elastic 
sheet, the tackiness of the elastic sheet, the degree the material was 
stretched, the compression force applied to inactivate the stretched 
elastic sheet, and the intensity and method of heating. Good recovery has 
been obtained by raising the temperature of the composite elastic material 
from about 120.degree. F. to about 170.degree. F. Typically, temporarily 
inactivated materials recover to their pre-stretch dimensions when briefly 
exposed to forced hot air maintained at a temperature in the range of 
about 150.degree. F. to about 160.degree. F. 
EXAMPLE 
Composite Elastic Material 
A composite elastic material was made from a gatherable web of spunbonded 
polypropylene having a basis weight of about 14 gsm joined to both sides 
of an elastic web of meltblown fibers having a basis weight of about 100 
gsm utilizing a patterned bonder roll arrangement. The elastic web was 
formed from a blend containing, by weight, about 63% KRATON G 1657 block 
copolymer, about 20% polyethylene PE NA601, and about 17% REGALREZ 1126 
tackifying resin. The layers were joined so the gatherable spunbonded web 
gathered between the locations where joined the elastic layer. Such a 
composite elastic material is typically referred to as a stretch-bonded 
laminate. The overall basis weight of the stretch-bonded laminate was 
about 165 gsm while the material was in the relaxed, unstretched 
condition. 
Cohesion of the Composite Elastic Material 
The cohesiveness of the elastic web was determined by measuring the force 
required to pull apart a stretch bonded laminate in the Z coordinate. The 
sample measured approximately 2 inches wide by 4 inches long between and 
was placed between two pressure plates covered with double coated pressure 
sensitive tape. The force required to pull the stretch-bonded laminate 
apart was measured using an "Accuforce Cadet" 0-20 kg digital force gauge 
available from the Hunter Spring Company. The results for the stretch 
bonded laminate having an elastic Kraton web are given in Table 5 under 
the heading "Kraton". 
Other stretch-bonded laminate materials were tested to measure the 
cohesiveness of elastic layers containing different components. An elastic 
layer identified in Table 5 by the heading "RP 6517" was formed from a 
blend containing about 63% by weight KRATON G 1657 block copolymer, about 
20% Epolene C-10 polyethylene, and about 17% Arkon P-125 tackifying resin. 
Another elastic layer, identified in Table 5 by the heading "RP 6518" was 
formed from a blend containing about 63% by weight KRATON G 1657 block 
copolymer, about 20% polyethylene PE NA601, and about 17% Arkon P-125 
tackifying resin. 
Maximum Elongation of the Elastic Material 
The composite elastic material was stretched and the force required to 
achieve different amounts of extension was measured using an Instron Model 
1122 Universal Testing Instrument. The sample was 2 and 1/8 inches wide 
and the distance between the jaws of the tester was 4 inches. The jaw 
separation rate was approximately 20 inches per minute. The results are 
reported in Table 3. Maximum or 100 percent extension of the gatherable 
web was achieved at 160 percent elongation. A tensioning force of 
approximately 1500 rams was required to achieve 100 percent extension for 
the 2 and 1/8 inch wide strip. 
Inactivation of the Elastic Material 
Unextended samples were marked at points approximately 36 inches apart and 
stretched from about 48 to about 61 inches which was approximately 99 
percent extension. The marked and stretched composite elastic materials 
were passed through the nip of a steel/steel pressure roller arrangement 
and compressed at pressures of about 180, 360, 400, and 550 pli. The 
retraction of the samples was measured utilizing a yard stick and a 
stopwatch. The results are given in Tables 7-10 wherein the extended 
length of the sample upon release of the stretching force is reported 
under the row heading "-3 seconds". The extended length of the sample when 
place along the measuring stick is reported under the row heading "0 
seconds". 
Disclosure of the presently preferred embodiment of the invention is 
intended to illustrate and not to limit the invention. It is understood 
that those of skill in the art should be capable of making numerous 
modifications without departing from the true spirit and scope of the 
invention. 
TABLE 1 
______________________________________ 
REGALREZ .RTM. Resins 
1094 3102 6108 1126 
______________________________________ 
Softening point, 
90-98 98-106 104-112 
122-130 
R&B , .degree.C. 
Color crystal-clear 
Typical Properties 
Softening point, 
94 102 108 126 
R&B, .degree.C. 
Color crystal-clear 
Acid number &lt;1 
Saponification 
&lt;1 
number 
Specific gravity 
0.99 1.04 1.01 0.97 
at 21.degree. C. 
Flashpoint, COC, 
235(455) 293(560) 243(470) 
243(470) 
.degree.C. (.degree.F.) 
Melt viscosity, .degree.C. 
1 poise 190 196 200 209 
10 poises 151 164 168 182 
100 poises 126 149 143 159 
Glass transition 
33 51 52 65 
(Tg), .degree.C. 
______________________________________ 
TABLE 2 
______________________________________ 
Compatibility Information 
REGALREZ .RTM. Resins 
Compatibility With 
1094 3102 6108 1126 
______________________________________ 
Natural rubber G G G G 
SBR 1011 P G G P 
KRATON 1107 (MB) G G E G 
KRATON 1101 (MB) P F G P 
Styrene end block copolymers 
P G F P 
KRATON "G" (MB) G F G G 
E/VA copolymers 
(low vinyl acetate content) 
E F G E 
(high vinyl acetate content) 
P E F P 
Paraffin wax E G E E 
Microcrystalline wax 
E G E E 
______________________________________ 
KEY: E = Excellent; G = Good; F = Fair; P = Poor 
TABLE 3 
__________________________________________________________________________ 
ARKON 
ARKON ARKON ARKON ARKON 
P-70 P-90 P-100 P-115 P-125 
__________________________________________________________________________ 
Color number 
50 50 50 50 50 
(Hansen) 
Softening point 
70.degree. C. 
90.degree. C. 
100.degree. C. 
115.degree. C. 
125.degree. C. 
Acid number 
0 0 0 0 0 
Specific gravity 
-- 0.973 0.982 0.985 0.989 
(20.degree. C.) 
Refractive index 
-- 1.515 1.519 1.523 1.530 
(20.degree. C.) 
Molecular Weight 
-- 650 700 850 1000 
Ash (%) -- 0.05 0.05 0.05 0.05 
Dielectric constant 
50 MC -- 2.3 2.3 2.3 2.3 
1000 MC -- 2.3 2.3 2.3 2.3 
Loss tangent 
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 
__________________________________________________________________________ 
TABLE 4 
______________________________________ 
POLYMER WEIGHT PERCENT 
______________________________________ 
A-B-A block 60-70% 
Copolymer 
Polyolefin 15-25% 
Resin Tackifier 
13-20% 
______________________________________ 
TABLE 5 
______________________________________ 
COHESION (Kg) 
KRATON RP 6517 RP 6518 
______________________________________ 
7.78 8.26 7.93 
9.15 8.62 8.27 
9.24 8.64 8.84 
8.87 8.99 6.18 
9.09 
AVERAGE 8.76 9.75 AVERAGE 7.80 
AVERAGE 8.89 
______________________________________ 
TABLE 6 
______________________________________ 
TENSION 
21/8 inch wide sample 
(GRAMS FORCE) ELONGATION % 
______________________________________ 
250 20 
500 40 
700 60 
900 80 
1000 100 
1100 120 
1250 140 
1500 160 
3000 180 
5000 200 
6000 220 
______________________________________ 
TABLE 7 
______________________________________ 
Sample compressed at 180 pli 
TIME EXTENDED LENGTH DISTANCE 
(SECONDS) (INCHES) (INCHES) 
______________________________________ 
-3 56.5 54.5 
0 49.0 47.0 
5 42.0 43.5 
10 41.0 42.5 
15 40.25 41.75 
20 40.0 41.0 
30 39.25 40.25 
45 38.5 39.5 
60 38.0 39.0 
90 37.5 38.5 
120 37.25 38.0 
180 36.75 37.75 
240 36.5 37.5 
______________________________________ 
TABLE 8 
______________________________________ 
Sample Compressed at 360 pli 
TIME DISTANCE DISTANCE DISTANCE 
SECONDS (INCHES) (INCHES) (INCHES) 
______________________________________ 
-3 61.0 53.0 48.0 
0 55.0 49.0 45.0 
5 53.0 46.25 41.75 
10 52.5 45.5 40.75 
15 51.5 44.75 40.125 
20 51.0 44.0 39.75 
30 50.25 43.25 39.0 
45 49.125 42.5 38.375 
60 48.5 41.25 38.0 
90 48.0 41.25 37.25 
120 47.5 40.75 37.0 
180 47.0 40.25 36.375 
240 46.5 40.0 36.0 
______________________________________ 
TABLE 9 
______________________________________ 
Sample compressed at 460 pli 
TIME DISTANCE DISTANCE 
SECONDS (INCHES) (INCHES) 
______________________________________ 
-3 54.0 53.0 
0 51.0 49.0 
5 47.75 46.0 
10 46.75 44.75 
15 46.0 44.0 
20 45.5 43.625 
30 44.75 43.0 
45 44.0 42.25 
60 43.5 41.75 
90 42.875 41.125 
120 42.375 40.75 
180 41.75 40.125 
240 41.25 39.75 
______________________________________ 
TABLE 10 
______________________________________ 
Sample compressed at 550 pli 
TIME DISTANCE DISTANCE 
(SECONDS) (INCHES) (INCHES) 
______________________________________ 
-3 51.0 50.5 
0 48.0 48.5 
5 46.0 46.5 
10 45.0 45.75 
15 44.5 44.25 
20 44.25 44.875 
30 43.5 44.25 
45 42.75 43.625 
60 42.25 43.25 
90 41.75 42.625 
120 41.25 42.125 
180 40.75 41.5 
240 40.5 41.125 
______________________________________