Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-06-23
2001-02-20
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S105000, C428S3550RA
Reexamination Certificate
active
06191189
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a combination of a substrate with a topical adhesive for attachment to the skin. In particular the present invention relates to a combination of a substrate with a topical adhesive which can be employed for attachment to the skin in the area were absorption of bodily liquids is desired, particularly for the adhesion of sanitary napkins, pantiliners, adult incontinence products or sweat pads. The combination provides secure attachment and is pleasing to the skin upon application, yet causes no discomfort upon removal. This is achieved by selecting the chemical composition and rheological characteristics of the topical adhesives and with the physical characteristics of the substrate on which the topical adhesive is applied, particularly the viscous modulus G″ of the topical adhesive and the stiffness S of the combination of the substrate with the topical adhesive.
BACKGROUND OF THE INVENTION
The general prior art in the field of topical adhesives for attachment to the skin is particularly developed in the field of band-aids, plasters and bandages. These articles are, however, typically applied in an emergency situation where for example a cut into the skin of the wearer has occurred and absorption of the body liquids emanating from a wound is desired. In this context performance aspects of the absorbent article such as comfortable and easy use and application, painless removal, discreteness are subordinate to criteria such as sterility, healing support, mechanical protection of the wound. Also such wound covering absorbent articles are mostly adhered to skin areas where prior to application of the absorbent article body hair can be removed or where little or no hair grows.
The present invention relates to combination of a substrate with a topical adhesive which is particularly useful to absorbent articles for absorption of body liquids which naturally emanate from a body without a wound. For example to attach sanitary napkins or pantiliners in the genital region. Also incontinence devices which are worn e.g. in the genital region or sweat pads which are worn in the arm pit region of a person can suitably employ the adhesive of the present invention.
Topical adhesives that are used for absorbent articles have generally been disclosed in US statutory invention registration H1602 or WO 96/33683. Some more details of the adhesive have been disclosed in PCT application WO 95/16424. In this document sanitary articles having a topical adhesive which is applied on the wearer facing side of a sanitary napkin along the entire periphery are disclosed. The problem underlying this document is primarily the safe attachment to the skin but mentions also the problems of detachment of such articles after use without causing undue pain to a wearer.
The disclosure of WO 95/16424 includes a detailed analysis of the criteria for the topical adhesive in respect to rheological criteria. However, this document has little regard to the problem of painless removal of such articles since the rheological criteria taught include epilatory, i.e. hair removal, compositions which are commercially available such as STREP MIELE™ sold in Italy by Laboratori Vaj S.p.A. The adhesives for topical attachment mentioned in WO 95/16424 include also today's pressure sensitive adhesives which are used to attach sanitary napkins to undergarments. Further, this document only identifies static rheological characteristics but is silent as to the dynamic rheological behaviour of a topical adhesive.
In WO 96/13238 a frequency dependent topical adhesive model is disclosed. However, all measurements disclosed, e.g. on page 9, were made at temperatures between −60° C. and +120° C. and at actual frequencies of 0.1 to 100 rad/s. In order to obtain the necessary data at application temperature (about 20° C., typical bath room, i.e. storage temperature) the Williams-Landel-Ferry (hereinafter WLF) equation was used.
This WLF equation is empirical and only valid within certain limits e.g. it cannot be used to extrapolate to temperatures below the glass transition temperature of a polymeric adhesive also the WLF cannot be used on the basis of values obtained below the glass transition temperature. Details about the WLF equation and its applicability can be found in “Principles of Polymer processing” by Z. Tadmor and C. G. Gogos, published by John Wiley & Sons or in “Viscoelastic Properties of Polymers” by J. D. Ferry also published by John Wiley & Son. Since this is already missing from WO 96/13238 the applicability of the disclosed data cannot be assessed.
European Patent Application EP-638 303 discloses the use of a topical adhesive on side cuffs of sanitary napkins in order to keep the cuffs in an upright position. Swiss publication CH-643730 discloses the use of a very long sanitary napkin having chamfered outer edges with a topical adhesive at the four corners of the outer edges in order to provide a topical adhesive area well outside the region of pubic hair growth. Both applications are silent as to the adhesive composition.
Based on the above state of the art it is an objective of the present invention to provide a combination of a substrate with a topical adhesive for secure attachment and painless removal from the skin of a disposable absorbent article. It is another objective of the present invention to ensure upon removal that no residual adhesive remains on the skin or on the hair.
It is yet a further objective of the present invention that the adhesive of the combination for topical attachment does not cause a cold or otherwise unacceptable temperature sensation upon application despite a temperature difference of the adhesive in respect to the skin temperature.
In addition to the above objectives of the present invention it is also desirable for topical adhesives of the combination to provide additional benefits such as delivery/dispersal of a compound or composition which is beneficial for the skin or for the body in general. Further, topical adhesives which do not affect the natural skin condition, e.g. by being breathable or water vapour transmitting or water vapour/sweat absorbing, are preferred.
BRIEF DESCRIPTION OF THE INVENTION
The present invention will be explain ed in its use on disposable absorbent articles for topical adhesive attachment to a wearer of such articles. The article typically has a wearer or body facing surface and an outside surface. The article comprises an absorbent core structure between the wearer facing surface and the outside surface for absorbing liquids emanating from a wearer such as urine, feces, menses, sweat and vaginal discharge. The article further comprises a combination of a substrate with a topical adhesive applied thereon, the combination having a stiffness or flexibility S measured in grams (g) according to the Flexibility Test method described hereinafter. The topical adhesive of the combination allows to attach an article to the skin of the wearer, being typically applied on the substrate on at least part of the wearer facing surface of the article.
Detailed analysis of the sequence of common situations occurring from the application of a disposable absorbent article to the time of removal of such an article has shown that specific adhesive characteristics need to be preferably satisfied in order to achieve the desired performance objectives, in particular secure initial attachment, secure attachment during use and painless removal at the end. The characteristics which have been considered in this context are the elastic modulus describing the elastic behaviour of the material and the viscous modulus which describes the viscous behaviour of the adhesive material.
The viscous behaviour of the adhesive can be interpreted to represent an indication of the ability of the adhesive to quickly attach and securely adhere. The elastic behaviour can be interpreted as an indication of the “hardness” behaviour of the adhesive. Its value is also critical for good initial attachment. Their combination is believed
Cinelli Fabio
Coles Peter
Corzani Italo
Cain Edward J.
Fitzpatrick Matthew P.
Lewis Leonard W.
The Procter & Gamble & Company
Wyrozebski Katarzyna
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