Stretchable tape

Details Stretchable tape Stretchable tape

2001-05-14

2002-10-15

Brittain, James R. (Department: 3677)

Buckles, buttons, clasps, etc.

Having adhesive fastener

C024S306000

Reexamination Certificate

active

06463633

ABSTRACT:

This invention relates to pressure-sensitive adhesive tapes, adhesive tabs formed therefrom, and methods for manufacturing the same. In one aspect, the invention relates to improvements in stretchable tapes and like products, and in the manufacture of the same. In this aspect, the stretchable tapes are formed of multiple layers that are manually stretchable to enable their stretchable properties. In another aspect, the invention relates to improvements in laminate web constructions of diaper fastener-tab stock of the kind adapted to be supplied to a diaper manufacturer and to be separated by the manufacturer into individual diaper-fastening tabs and applied to individual diapers, usually two tabs to a diaper for infant diapers and six tabs to a diaper for adult diapers. In this aspect, the invention particularly relates to means forming part of the diaper tabs and providing novel conveniently manipulated fingerlifts for the tabs.
The tapes are useful in a wide range of applications and constructions wherein a stretchable or variable length connector is required and/or a closing tension is to be applied to two elements as in a protective cover or item of personal clothing such as a gown. The tapes may be used as a construction film for forming an element of a more comprehensive tape or closure system including industrial or craft applications requiring pieces to be secured together with tension during a drying cycle or medical applications such as medical tapes, suture tapes, nasal dilators, bandages and the like. In such broad applications, the tape layers may be formed of polymeric, stretchable polymer and fabric constructions and cellulosic materials. The tapes are especially useful in connection with diaper fastening systems, and they are described hereinafter with particular reference to stretchable fastening tapes for use in diapers, diaper tabs and the manufacture of the foregoing.
RELATED ART
The use of stretchable or extensible fastening tapes in diaper tabs to promote user comfort through better fit and more secure mounting is known in the art. The tabs operate as extensible diaper side waist bands. Examples of such diaper fastening systems are disclosed in U.S. Pat. Nos. 4,795,456, 4,066,081, 4,051,853 and 3,800,796. The teachings of these patents are incorporated herein by reference.
It has been previously proposed to make articles from pressure-sensitive adhesive tapes in which the layer of pressure-sensitive adhesive is partially covered with a printed pattern of ink or other non-printed masking agents such as talc. For example, document or envelope containers are shown in U.S. Pat. Nos. 3,159,930 and 3,874,893, labels are shown in U.S. Pat. No. 4,068,028, a tacky floor mat is taught in U.S. Pat. No. 4,107,811 and sign stock is described in U.S. Pat. Nos. 4,671,003 and 4,787,158.
Various fingerlift arrangements specific to diaper tabs are also known in the prior art. One simple arrangement is to provide an adhesive-free zone at the fingerlift edge, as in U.S. Pat. No. 3,833,456 to Reed et al. This fingerlift edge can be difficult to grasp;
there is no clear indication of the presence of a fingerlift, and the unsupported edges of rolls from which such tabs are cut can be easily damaged.
Another fingerlift arrangement for a diaper tab is a fold-over arrangement, as in U.S. Pat. No. 3,893,460 to Karami. If such folding-over is done during manufacture of the diaper fastener stock, differences in thickness are created across the width of the stock, causing distortions when the stock is rolled up for storage and shipment. On the other hand, if the folding-over is delayed only to be attempted on the diaper line, the difficulty of performing that step as part of the fastener dispensing and application procedure on the diaper line presents a risk of line stops and delays in diaper production.
Another known fingerlift arrangement for a diaper tab is a strip lamination, as in U.S. Pat. No. 4,726,971 to Pape et al. The laminated strip extends outwardly of the width of the diaper fastener stock, so that when the same is rolled and transported, the laminated strip can be easily damaged. Also, the strip creates local thickness variations in the roll.
Still another arrangement is a pull string, as in U.S. Pat. No. 4,005,713 to Mesek. This too may cause thickness variations, and may be complicated to fabricate and manipulate, particularly at high diaper line speeds.
SUMMARY OF THE INVENTION
The inventive stretchable tape has a multiple layer construction including an adhesive layer for tape mounting of normally nonextensible and extensible layers that selectively bear tension loads. An adhesive-inhibiting masking is applied to a portion of the adhesive layer to enable relative movement between the extensible layer and adjacent adhesive layer portion to thereby provide the tape with stretchable properties.
The stretchable tape includes opposed terminal segments and a central segment. The nonextensible layer typically comprises a facestock material or substrate extending along the length of the tape. The extensible layer and adhesive masking are located adjacent the central segment. A separation line or plane is provided at the central segment.
The separation line may comprise a location of fully separated portions of the facestock or nonextensible layer, such portions being respectively associated with opposed terminal segments, or a weakened joint in the facestock layer that may be ruptured by manual stretching of the tape. The weakened joint may be formed by a tape supplier, a tape converter or an ultimate tape user such as a diaper manufacturer. The weakened joint may be formed in the facestock layer by mechanical or chemical techniques. Mechanical techniques include forming discontinuities along a failure line as by scoring, perforating, slitting or any other means known in the art. Chemical techniques include acid drip or etching.
As it relates to a fastening tape or diaper tab herein, the facestock layer has tear strength or modulus characteristics that enable it to be manufactured and processed in customary web or film sizes using conventional automated machinery that impose insufficient forces to rupture, plastically stretch or otherwise detrimentally deform the layer. The separation lines extend in the machine direction and do not tend to interfere with machine direction forces applied to the stock to carry it through the processing.
For diaper applications, the length of the fastening tape is formed in the machine cross direction and transverse direction of the stock, so that the separation line extends across the width of the tape. If the separation line comprises complete partitioning of the facestock layer, the portions of the facestock layer may simply separate to allow tape stretchability. If the separation line is a weakened joint, the tape may be manually stretched to rupture the facestock layer along the joint, and thereby transfer stretching forces to the extensible layer and achieve stretchable tape or tab properties.
In another aspect, the adhesive masking may provide a distinctive color appearance as by phosphorescence or fluorescence. This distinctive color appearance may be provided for any number of applications including designation of location of control or manipulative elements.
In diaper applications, the high visibility of the fingerlift provided by the phosphorescence or fluorescence is useful in typical household infant diaper applications. It is especially useful in a health care facility when it is not desirable to fully light the room and disturb the patient whose diaper is to be checked or changed. Further, the distinctive appearance may serve as a warning to avoid contact. For example, the protective latex gloves worn by the attendant or nurse may be torn if the pressure-sensitive adhesive is inadvertently contacted and then pulled-free.
In contrast with the prior art use of adhesive barriers, in the present invention as it relates to tapes, the adhesive masking is provided along a continuous zone or line using web processing apparatus and tech

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