GB2362190A

GB2362190A - Closure tab

Info

Publication number: GB2362190A
Application number: GB0010566A
Authority: GB
Inventors: Bert Bogaerts; Paul Dhondt; Rudy Lievens
Original assignee: Avery Dennison Corp
Current assignee: Avery Dennison Corp
Priority date: 2000-05-02
Filing date: 2000-05-02
Publication date: 2001-11-14
Also published as: GB0010566D0

Abstract

The present invention relates to a closure tab for forming the closure of a diaper. The closure tab incorporates both elements of a mechanical closure system in the tab. The design of the tab is such to allow it to be formed as a stable convoluted roll of material that can be supplied in long yardage lengths. The arrangement of the closure tab is particularly designed to allow easy processability in forming the convoluted rolls and then using these rolls in a diaper production line. The invention further relates to method of forming and using the closure tabs.

Description

2362190 CLOSURE TAB This invention relates to a closure tab for forming

closures for disposable diapers which can be opened and refastened without destroying either the diaper shell or the closure tab. In particular the invention relates to a closure tab for a diaper formed with both parts of the closure system and a composite roll material for forming the same.

A disposable diaper typically comprises a thin, flexible, low density film cover, for example, polyethylene, an absorbent filler within the cover, and a porous inner liner overlying the filler. The diaper is positioned at the crotch of a wearer with the two ends of the diaper extending toward the front and back respectively. Edges on each side of the diaper are then either positioned adjacent to each other or overlapped using a strip of pressure sensitive adhesive coated tape. The tape is adhered to the cover film at border regions adjacent each of the two edges to hold the diaper closed.

After a tape closure has been opened, it is frequently discovered that the diaper has not been soiled and hence that there is no need to replace it. Reclosable fastening systems are now well known using both adhesive based closure or hook and loop-type mechanical closure systems.

1 2 Adhesive closures of this type have involved a combination of two or more tapes, one of which remains permanently adhered to one edge of the diaper and the other being removably adhered to the other edge of the diaper. Examples of such products are shown in US-A-3,9S1,149.

Closure tabs are often produced in the diaper assembly process with the various parts of the tab being brought together on the diaper. Although this may be advantageous for simple closure tabs, it is often difficult and/or costly for more complex closure tabs.

In many circumstances it is more efficient for the tape closures to be fabricated by positionably mounting a plurality of individual rolls of the appropriate tapes and combining them in situ to form a composite convoluted roll of tape. The width of the tape is substantially the same as the length of the diaper closure to be fabricated. In a separate process the diapers are assembled using closure tabs cut from the composite roll. In the diaper assembly process, the composite roll is then severed at right angles to the edges of the composite strip at intervals corresponding to the width of the desired tape closure and adhered at appropriate locations along the border adjacent the side edges of the diaper as exemplified in US-A- 3,616,114.

3 Typically the closure tab contains one part of the closure system. In an adhesive system the closure tab will normally have the adhesive patch which is securable to a permanently fixed landing zone on the front of the diaper. In a mechanical closure system, the tab will typically have the hook material with the landing zone presenting the loop material for engagement.

US-A-5,383,872 provides a hook and loop fastener having both components of the mechanical fastener where both components are provided on the fastening tab. The user applies one component to the front of the diaper to form a mini-landing zone when first fitting the diaper. The first and second parts of the mechanical closure are of approximately the same dimension. The tab is secured just to the outer shell of the diaper. There is no suggestion that the tab is formed from a composite roll material The present invention seeks to provide an improved closure tab for a diaper.

According to first aspect of the present invention there is provided a closure tab for a diaper comprising first, second and third layers, each layer comprising a lamina substrate extending axially between first and second opposed edges and having first and second surfaces, wherein the first layer has the first surface substantially covered with adhesive 4 and the first layer comprises first, second, third and fourth zones extending between said opposed edges, the second layer has the first surface comprising a release surface and said second surface substantially covered with an adhesive, and the second layer comprising f irst, second and third zones extending between said opposed edges, the third layer has said first surface substantially covered with an adhesive and said second surface comprising a first part of a mechanical fastener extending substantially between the opposed edges and the third layer having first and second zone extending between said opposed edges, the closure tab being formed with adhesive of the first layer in its second zone in surface-to-surface contact with the adhesive of the second layer in its first zone, the adhesive of the first layer in its third zone has a second part of said mechanical fastener secured thereonto and the adhesive of the first layer in its fourth zone has a first finger lift tab secured thereonto, the second surface of said third layer is in surface-to-surface contact with the release surface of the first zone of the second layer and the second part of the mechanical fastener secured onto the third zone of the first layer, the first surface of the third zone of the second layer is in surface-to-surface contact with the second surface of the first zone of the third layer, and the first surface of the second zone of the third layer having a second finger lift tab secured thereonto.

The closure tab of the invention thus permits a portion of the fastening tape to be adhered permanently to the outer sheet of the diaper at a first location in a secure manufacturers joint. The remaining portion of the closure tab with the target tape can be adhered to a second location. Thus the closure tab of the present invention allows adjustability on the length of the diaper not just the width.

The target tape forms a mini-landing zone and becomes permanently fixed to the diaper outer shell. The diaper can thereafter be repeatedly reopened and adjusted by the hook and loop mechanical closure system. The third layer comprises the part of the tab which is fixed by the user to form the landing zone when the diaper is fitted. The landing zone must have a greater extent than the repositionable tab on the first layer as it also covers the first zone of the second layer. This allows the repositionable tab to be moved relative to the landing zone to provide precise positioning, an improved fit and consequently less likelihood of leakage. In this way the tab of the present invention provides increased adjustability due to the two components of the mechanical fastener being of different sizes and so minimises the material used for the mechanical closure compared to known 6 mechanical closures.

The tab also provides a particularly cost effective way to produce a tab with both parts of the closure system. Advantageously, the tab of the present invention is simple to produce as the various layers are either completely covered by adhesive or remain uncoated.

Preferably the second surface of the first layer of the closure tab is a release surface. Advantageously the release surfaces are coated with a release coating which may be of any of the normal species which are used to form release coatings such as curable silicones or carbamides, as known to those skilled in the art. By selection of suitable adhesive and release coating the manufacturer can precisely control the nature and degree of tack.

Preferably the adhesive coating is a pressure sensitive adhesive or heat curable adhesive on the first surface of the first tape layer which may be any of the normal species which are used as pressure sensitive adhesives, or as heat curable adhesives, as known to those skilled in the art. Advantageously the pressure sensitive adhesive will have a 900 peel strength on polyethylene film of between 1.5 and 25 N/25 mm.

Advantageously, the first fingerlift tab is visually 1 7 distinct from the second fingerlift tab. This allows the user to easily distinguish between the two and separate the appropriate layers at the appropriate time. For example the two fingerlift tabs may be different colours produced by using differently coloured substrate materials.

According to a second aspect of the invention there is provided a composite roll a roll of prelaminated tape wound convolutely upon itself and being arranged to form the closure tab according to the first aspect of the invention. The roll may be provided in spool form especially in cases where only small roll diameters may be accommodated by the diaper manufacturer.

According to a third aspect of the invention there is provided a diaper including one or more of the closure tabs according to the first aspect of the invention.

The invention is particularly advantageous when the wearer is an adult e. g. weighing at least 40kg. In such cases the diaper will often have four tape closures to ensure closure. Using tape closures of the invention on adult diapers is estimated to save up to 30% loop material which would otherwise be used leading to a cost reduction of upto 35%, which does not include the saving made through the simpler manufacturing technique permitted.

8 According to a f ourth aspect of the invention there is provided a method for manufacturing a closure tab according to the f irst aspect of the invention comprising the steps of:

a) providing a first layer comprising a lamina substrate extending axially between first and second opposed edges and having first and second surfaces, the first layer having the first surface substantially covered with adhesive and the first layer comprises first, second, third and fourth zones extending between said opposed edges; b) providing a second layer comprising a lamina substrate extending axially between first and second opposed edges and having first and second surfaces, the second layer has the first surface comprising a release surface and said second surface substantially covered with an adhesive, and the second layer comprising first, second and third zones extending between said opposed edges; C) providing a third layer comprising a lamina substrate extending axially between first and second opposed edges and having first and second surfaces, the third layer has said first surface substantially covered with an adhesive and said second surface comprising a first part of a mechanical fastener extending substantially between the opposed edges and the third layer having first and second zone extending between said opposed 9 edges; and d) arranging the said layers such that adhesive of the first layer in its second zone in surface-to-surface contact with the adhesive of the second layer in its first zone, the adhesive of the first layer in its third zone has a second part of said mechanical fastener secured thereonto and the adhesive of the first layer in its fourth zone has a first finger lift tab secured thereonto, the second surface of said third layer is in surface-to-surface contact with the release surface of the first zone of the second layer and the second part of the mechanical fastener secured onto the third zone of the first layer, the first surface of the third zone of the second layer is in surface-to-surface contact with the second surface of the first zone of the third layer, and the first surface of the second zone of the third layer having a second finger lift tab secured thereonto; wherein the various first, second and third substrates are unwound from yardage rolls of material and the other components fixed thereonto and the layers are brought together to form the closure tab.

Preferably the closure tab is made via forming a convoluted roll of material and the method further includes the step:

e) rolling the three layers into a convoluted roll of material to form a roll of material, wherein a winding of said roll can be cut in the axial direction to form the closure tab.

According to a fifth aspect of the invention there is provided a method of manufacturing a diaper including the step of attaching a closure tab according the first aspect of the invention.

The diaper may be provided with closure tab according to the first aspect of the invention with the tab being made in the diaper manufacturing process with the closure tab being formed on the diaper.

Alternatively the closure tab is cut from a roll of material and the preformed tab is attached to the diaper in the diaper manufacturing process. The tab of the present invention is particularly convenient to reliably fix to the diaper in a continuous assembly process from the convoluted roll of material. Advantageously, the composite roll does not have exposed areas of adhesive which can be contaminated during the production process. A roll material of the invention offers much simpler manufacture of a diaper as there is no need to separately apply a landing zone. Also, the nature of the roll is such to allow easy processability compared to prior art rolls. Thus, this embodiment allows a much simpler and so more economical diaper line assembly compared to prior art lines where the landing zone is separately applied.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 shows a cross-section through a laminate tape construction in accordance with the invention; Figure 2 shows a plan view of a diaper incorporating the closure tabs of Fig. 1; and Figure 3 shows a transverse section of a roll of the tape of the present invention.

The present invention concerns a closure tab 10 for forming closures for diapers e.g. disposable diapers which can be opened and refastened without destroying either the diaper shell or the closure tab. In particular the present invention is used in connection with adult diapers as the material savings brought about by this invention are particularly significant for adult sized diapers.

Figure 1 shows a tape construction according to a preferred embodiment of the invention The closure tab 10 is subdivided into a first layer 20, a 12 second layer 40 and a third layer 60.

The first layer 20 comprises a polymeric substrate 21 extending axially between a first edge 22 and opposed second edge 24. Suitable materials for the substrate layer are paper, kraft paper, polyethylene, polypropylene, blends and copolymers of polyethylene and polypropylene, non-woven substrates, non-woven laminates, elastic materials, woven materials and embossed materials as are commonly known to the skilled person. Preferably polypropylene will be used. The first layer has a first surface 26 and a second surface 28. The first layer 20 is comprised of first 23, second 25, third 27 and fourth 29 adjacent and touching zones extending between said opposed edges 22, 24.

The second layer 40 comprises a polymeric substrate 41 extending axially between a first edge 42 and opposed second edge 44. The second substrate may be made from the same choice of materials as the first substrate 21. The second layer has a first surface 46 and a second surface 48. The second layer 40 is comprised of first 33, second 35 and third 37 adjacent and touching zones extending between said opposed edges 42, 44.

The third layer 60 comprises a polymeric substrate 61 extending axially between a first edge 62 and opposed second edge 64. The third substrate may be made from the same 13 materials as the first substrate 21. It is preferred if the third substrate forms the backing of the loop material which in this embodiment will extend across the whole of the third layer. The third substrate is thus provided in a laminate with the loop material. The third layer has a first surface 66 and a second surface 68. The third layer 60 is comprised of first 53 and second 55, adjacent and touching zones extending between said opposed edges 62, 64.

The first surface 26 is substantially covered, e.g. greater than 50% covered, with a layer 30 of adhesive. The adhesives may be heat activatable adhesives, or rubber based hot melt pressure sensitive adhesives. The rubbers will be selected from SIS, SBS, SE, copolymers, block copolymers and terpolymers thereof as supplied by Shell, Exxon & Nippon Zeon. The resins can be synthetic or modified resins as supplied by Hercules, Exxon, Goodyear, Nippon Zeon and DRT. A pressure sensitive adhesive is preferred. Typical adhesive film thicknesses are 20-50g/M2, preferably 25-40g/M2. The adhesive does not have to entirely cover the first surface 26 and any pattern of dots, strips or otherwise may be adopted. The adhesive will provide sufficient tack to form a suitable manufacturers joint to a diaper shell.

The second surface 28 is provided with a release coating 32 applied directly to the polymeric material 21 to facilitate unwinding of the composite tape when wound upon itself about 14 the core. Suitable release coatings 32 include silicone compositions such as PDMS compounds such as the radiation curable systems supplied by Th. Goldschmidt, General Electric or Rhodia or thermably curable as supplied by Dow Chemicals, Rhodia, or Wacker Chemie. The face or surface of some polymeric materials may inherently provide acceptable peel-back release for adjacent substrate adhesives.

The second layer 40 is comprised of any suitable polymeric material 41 said first surface 46 is provided with a release coating 50 and a second surface 48 which is substantially covered, greater than 50%, with an adhesive layer 52 which may be of the same type of adhesive as the layer 30. A pressure sensitive adhesive is preferred such as those mentioned above in relation to the layer 30.

The first surface 66 substantially covered, e.g. greater than 50% covered, with an adhesive layer 70 which may be of the same type as the layer 30. A pressure sensitive adhesive is preferred such as those mentioned above in relation to the layer 30. The second surface 68 comprises a first part 72 of a mechanical fastener 18 extending substantially between the opposed edges 62, 64. Suitable materials for the first part 72 of the mechanical fastener include the loop part of hook and loop closure system as known in the art. Typically, knitted, brushed fabric or lock loop materials made from polyamides or polyester yarn is such as manufactured by Sitip, Tybor, Guilford Mills, Miti, Radici, Aplix or Milliken can be used. Non-wovens can also be used, such as polyester based or polypropylene based materials as known in the art.

The closure tab 10 is formed with adhesive 30 of the first surface 26 of the first layer 20 in its second zone 25 in surface to surface contact with the adhesive 52 of the second surface 48 of the second layer 40 in its first zone 33.

The adhesive 30 of the first layer 20 in its third zone 27 has a second part 34 of said mechanical fastener 18 secured thereto. Suitable materials for the second part 34 of the mechanical fastener include the hook part of said hook and loop systems. The hooks that are used will compliment the loop material. The hooks that are used are mainly extruded microhooks in polypropylene or polyethylene as available from Gottlieb Binder GmbH & Co., YKK, Velcro, 3M and Aplix. Preferably the supplier is Gottlieb Binder GmbH & Co.

The adhesive 30 of the first layer 20 in its fourth zone 29 has a first fingerlift tab 36 secured thereto. Suitable materials for the first fingerlift tab 36 include polyesters, polypropylene and polyethylenes. Alternatively, rather than using a substrate material, the adhesives may be simply printed upon in a colour or pattern to render it non- 16 adhesive. The substrate material of the f irst layer may simply be folded over to form the tab or an adhesive free area could be used.

The second surface 66 of the third layer 60 is in surface to surface contact with the release surface 50 of the first zone 35 of the second layer 40.

The first surface 46 of the third zone 37 of the second layer 40 is in surface to surface contact with the second surface 68 of the first zone 53 of the third layer 60.

The first surface 66 of the second zone 55 of the third layer 60 has a second fingerlift tab 74 secured thereonto. Preferably the first and second fingerlift tabs are visually distinct from one another, e.g. differently coloured polymeric substrates, to facilitate easy identification of the correct tab by the user. However, the second fingerlift tab may be produced in the same f ashion and f rom the same materials as the first fingerlift tab.

The first and second fingerlift tabs 36, 74 permit and facilitate the separation of the various layers 20, 40, 60. The separation of the first layer 20 from the third layer 60 is facilitated by lifting the first fingerlift 34. The separation of the first layer 20 and third 60 layer disengages the mechanical fastener 18 by separating the 17 f irst part 72 and the second part 34 of the mechanical fastener 18.

The separation of the third layer 60 from the second layer 40 is facilitated by using the second fingerlift 74.

The invention can be used in other applications where there is a need for providing a reclosable tab at low cost.

The tape construction of Fig. 1 will normally then be wound to form a self wound tape which is then transferred to where the tape is used. No release liner need be used with the preferred embodiments of the invention. The tab construction of Fig. 1 is particularly useful in the diaper industry for the forming of resealable tabs.

The tape construction of Fig. 1 may be used in the diaper industry to f orm. a resealable tab as shown in Fig. 2. A disposable diaper 80 is formed with a plastic layer e.g. of polyethylene, covering the outer surface thereof. The constituents, materials and design of diapers is well known to those skilled in the art. Tabs 84 are provided comprising strips of the closable tabs of Fig. 1. A landing zone 82 is provided to which the tabs 84 are releasably securable to fit the diaper on a user. The manner in which the tabs 84 is secured to the diaper 80 is known as the branching configuration. Examples of this type of mounting 18 are illustrated in WO 96/12464 from which further details may be obtained. In Fig 2 the left hand tab 84 is shown in the storage position where part of the tab 54 is wrapped around to the unseen surface of the diaper. The right hand tab 54 is deployed for fastening.

The tape construction of Fig. 1 when wound to form a self wound tape 90 as shown in Fig. 3. The winding tension will normally be in the range of 10 to 500 N/m, preferably 30 to 200 N/m. The winding tension is concentrated in the area of the tape for easy processability. Alternatively the tape of the present invention could be produced in line in the diaper assembly, but this is not thought to be as cost effective as producing composite rolls of the materials as shown in Fig. 3.

Thus in general the present invention relates to a closure tab for forming the closure of a diaper. The closure tab incorporates both elements of a mechanical closure system in the tab. The design of the tab is such to allow it to be formed as a stable convoluted roll of material that can be supplied in long yardage lengths. The arrangement of the closure tab is particularly designed to allow easy processability in forming the convoluted rolls and then using these rolls in a diaper production line. The invention further relates to method of forming and using the closure tabs.

Claims

19 CLAIMS:

1. A closure tab for a diaper comprising first, second and third layers, each layer comprising a lamina substrate extending axially between first and second opposed edges and having first and second surfaces, wherein the first layer has the first surface substantially covered with adhesive and the first layer comprises first, second, third and fourth zones extending between said opposed edges, the second layer has the first surface comprising a release surface and said second surface substantially covered with an adhesive, and the second layer comprising first, second and third zones extending between said opposed edges, the third layer has said first surface substantially covered with an adhesive and said second surface comprising a first part of a mechanical fastener extending substantially between the opposed edges and the third layer having first and second zone extending between said opposed edges, the closure tab being formed with adhesive of the first layer in its second zone in surface-to-surface contact with the adhesive of the second layer in its first zone, the adhesive of the.first layer in its third zone has a second part of said mechanical fastener secured thereonto and the adhesive of the first layer in its fourth zone has a first finger lift tab secured thereonto, the second surface of said third layer is in surface-to-surface contact with the release surface of the first zone of the second layer and the second part of the mechanical fastener secured onto the third zone of the first layer, the first surface of the third zone of the second layer is in surface-to- surface contact with the second surface of the first zone of the third layer, and the first surface of the second zone of the third layer having a second finger lift tab secured thereonto.

2. A closure tab according to claim 1, wherein the second surface of the first layer is a release surface.

3. A closure tab according to claim 1 or 2, wherein the surface or surfaces are siliconised.

4. A closure tab according to any of claims 1 to 3, wherein the adhesive is a pressure sensitive adhesive.

5. A closure tab according to any of claims 1 to 4, wherein the adhesive has a 900 peel strength on polyethylene film of between 1.5 and 25 N/25 mm.

6. A closure tab according to any one of claims 1 to 5, wherein the first fingerlift tab is visually distinct from the second fingerlift tab.

7. A roll of prelaminated tape wound convolutely upon 21 itself and being arranged to form the closure tab according to claim 1 to claim 6.

8. A diaper including one or more of the closure tabs according to claims 1 to 6.

9. The diaper of claim 8, wherein the diaper is for a wearer weighing at least 40kg, i.e an adult-sized diaper.

10. A method for manufacturing a closure tab according to any one of claims 1 to 6, comprising the steps of:

a) providing a first layer comprising a lamina substrate extending axially between first and second opposed edges and having first and second surfaces, the first layer having the first surface substantially covered with adhesive and the first layer comprises first, second, third and fourth zones extending between said opposed edges; b) providing a second layer comprising a lamina substrate extending axially between first and second opposed edges and having first and second surfaces, the second layer has the first surface comprising a release surface and said second surface substantially covered with an adhesive, and the second layer comprising first, second and third zones extending between said opposed edges; C) providing a third layer comprising a lamina substrate 22 extending axially between first and second opposed edges and having first and second surfaces, the third layer has said first surface substantially covered with an adhesive and said second surface comprising a first part of a mechanical fastener extending substantially between the opposed edges and the third layer having first and second zone extending between said opposed edges; and d) arranging the said layers such that adhesive of the first layer in its second zone in surface-to-surface contact with the adhesive of the second layer in its first zone, the adhesive of the first layer in its third zone has a second part of said mechanical fastener secured thereonto and the adhesive of the first layer in its fourth zone has a first finger lift tab secured thereonto, the second surface of said third layer is in surface-to-surface contact with the release surface of the first zone of the second layer and the second part of the mechanical fastener secured onto the third zone of the first layer, the first surface of the third zone of the second layer is in surface-to-surface contact with the second surface of the first zone of the third layer, and the first surface of the second zone of the third layer having a second finger lift tab secured thereonto; wherein the various first, second and third substrates are unwound from yardage rolls of material and the other 23 components fixed thereonto and the layers are brought together to form the closure tab.

11. The method of claim 10, further including the step:

12. A method of manufacturing a diaper including the step of attaching a closure tab according to any one of claims 1 to 6.

13. The method according to claim 12, wherein the closure tab is produced according to claim 10 in the diaper manufacturing process and the closure tab is formed on the diaper.

14. The method according to claim 12, wherein the closure tab is produced according to claim 11 and preformed closure tab is applied to the diaper in the diaper manufacturing process.

15. A closure tab as hereinbefore described with reference to, and/or as illustrated by the accompanying drawings.

16. A roll of prelaminated tape as herein before described 24 with reference to and/or as illustrated by the accompanying drawings.

17. A diaper having at least one closure tab as herein before described with reference to and/or as illustrated by the accompanying drawings.

18. A method of manufacturing a closure tab as hereinbefore described with reference to, and/or illustrated by, the accompanying drawings.

19. A method of manufacturing a diaper incorporating the closure tab as hereinbefore described with reference to, and/or illustrated by the accompanying drawings.