US 4,543,099 AGranted

Method for imparting elastic properties to a flexible substrate

AssigneeH. B. Fuller Company

InventorsWilliam L. Bunnelle, Richard C. Lindmark, Jr.

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Abstract

A purpose of the disclosed method is to impart gathers and elasticity to a relatively inelastic film, membrane, or web substrate, through elastic banding with a viscoelastic hot melt pressure-sensitive adhesive (PSA). Typically, the resulting elastic-banded substrate product (e.g. 40) will be cut into discrete units and formed in to garments or body-encircling members such as disposable diapers. One step of the preferred method involves extruding a ribbon or band (13 or 113) comprising a viscoelastic hot melt PSA, which PSA has unusually high cohesion, stretchiness, and elasticity without excessive loss of adhesive bonding strength. (The viscoelastic behavior of the PSA is believed to be determined, at least in part, by the relative size of its crystalline domains and its rubbery domains and the glass transition temperatures and softening point of its components.) A second step of the preferred method involves bringing the band of hot melt (13 or 113) into adherent contact with a surface of a moving continuous substrate (22 or 32 or 132). A typical substrate would be the polyolefin film used in the manufacture of disposable diapers. The band can be bonded to the substrate through a pressure activation technique, wherein the band itself has the necessary inherent adhesive properties.

Claims23

Dependent claims

A method for imparting elastic properties to a flexible substrate, which comprises contacting a surface of the flexible substrate with a band of a self-adhering elastic composition which consists essentially of:

a major amount by weight, not exceeding 70% by weight, of a rubbery block copolymer, which copolymer includes a rubbery midblock portion and which is terminated with vinyl arene endblocks, about 70 to 80% by weight of said rubbery block copolymer comprising said rubbery midblock portion and about 20 to about 30% by weight of said rubbery block copolymer comprising said vinyl arene endblock;
a minor amount by weight, not less than 30% by weight, of a tackifying resin generally compatible with and generally associated with said midblock portion;
- 9% by weight of an aromatic, essentially hydrocarbon resin having a glass transition temperature and a softening point above those of said vinyl arene endblocks and said tackifying resin;
said aromatic, essentially hydrocarbon resin being generally compatible with and generally associated with said endblock;
and
0-5% by weight of essentially inert extenders, fillers, pigments, and antioxidants that do not substantially affect the adhesive of elastic properties of the composition;
the foregoing proportions being selected to provide the following pressure-sensitive adhesive and rheological properties:
(i) a tensile strength at 500% elongation, determined at 20.degree.-25.degree. C., of at least 50 pounds per square inch;
(ii) a 180.degree. peel resistance, according to PSTC-1, determined at 20.degree.-25.degree. C. for 24 hours after formation of the pressure-sensitive adhesive bond, of at least about 450 grams per 25.4 millimeter-width;
(iii) a dead load deformation, tested at room temperature, 37.8.degree. C., 43.3.degree. C., and 48.9.degree. C. for 3 hours under 1500 g/cm.sup.2, of less than 50%, where dead load deformation is equal to the increased length minus the original length divided by the original length of a sample at least 25 millimeters in length, and a loss modulus, a storage, modulus, and a loss tangent measured at 0.01-0.25 Hz throughout the temperature range of 25.degree.-50.degree. C. as follows:
loss modulus:
4.times.10.sup.4 to 35.times.10.sup.4 dynes/cm.sup.2
storage modulus:
75.times.10.sup.4 to 200.times.10.sup.4 dynes/cm.sup.2
loss tangent:
0.03 to 0.3.

13 more elements

A method for imparting a self-adhering elastic to a flexible substrate comprising the steps of:

(a) unreeling a band of self-adhering elastic composition from a roll, said roll being maintained at a temperature below the softening point of said self-adhering elastic and said band of self-adhering elastic being an extrudate at least 50 microns in thickness which consists essentially of (i) a block copolymer comprising at least one substantially amorphous, rubbery polymeric midblock and at least two glassy poly(vinylarene) endblocks;
(ii) 30-115 parts per hundred of a midblock associating resin;
and (iii) 3-20 parts per hundred of an aromatic, essentially hydrocarbon endblock associating resin having a Tg and a softening point above 115.degree. C. each per one hundred parts of the block copolymer;
wherein the proportions (i), (ii), and (iii) are selected to provide the following properties:
(i) a tensile strength at 500% elongation, determined at 20.degree.-25.degree. C., of at least 50 pounds per square inch;
(ii) a 180.degree. peel resistance, according to PSTC-1, determined at 20.degree.-25.degree. C. 24 hours after formation of the pressure-sensitive adhesive bond, of at least about 450 grams per 25.4 mm-width;
(iii) a dead load deformation, tested at 37.8.degree. C. and 1500 g/cm.sup.2, less than 50%;
and
(iv) a loss modulus of 5.times.10.sup.4 to 100.times.10.sup.4 dynes/cm.sup.2, a storage modulus of 65.times.10.sup.4 to 225.times.10.sup.4 dynes/cm.sup.2, and a loss tangent of 0.3 to 1.0, at 0.01-0.25 Hz at 25.degree.-50.degree. C.;
(b) contacting the band of self-adhering elastic with a surface of a flexible substrate forming a bond between the substrate and elastic.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/399,780Filed 19 Jul 1982 · division
Priority: 26 Mar 1981
Granted: 24 Sep 1985
Term ends: Not estimatedThe source records don’t support an estimate.

Classification25 codes

B32B 27/08
As the main or only constituent of a layer, which is next to another layer of the same or of a different material: of synthetic resin
A41F 9/02
Belts, girdles, or waistbands for trousers or skirts: expansible or adjustable belts or girdles ; Adjustable fasteners comprising a track and a…
A61F 13/15593
Of babies' napkins, e.g. diapers: having elastic ribbons fixed thereto; Devices for applying the ribbons
B32B 7/12
Interconnection of layers: using interposed adhesives or interposed materials with bonding properties