GB2281212A

GB2281212A - Production of absorbent hygiene products

Info

Publication number: GB2281212A
Application number: GB9410927A
Authority: GB
Inventors: Brian Pettitt
Original assignee: Robinson and Sons Ltd
Current assignee: Robinson and Sons Ltd
Priority date: 1993-06-01
Filing date: 1994-06-01
Publication date: 1995-03-01
Anticipated expiration: 2014-06-01
Also published as: GB2281212B; GB9311232D0; GB9410927D0

Abstract

A method of producing an absorbent hygiene product comprises providing a first layer of non-absorbent thermoplastic material; providing a second layer of absorbent material, the second layer comprising a mixture of thermoplastic and non-thermoplastic fibres; and securing the first and second layers to each other to form said product by ultrasonic welding. The first layer may be of film or non-woven fabric and the second layer may be of cotton fibres or a mixture of cotton and viscose fibres together with fibres of polypropylene, polyethylene, polyester or polyacrylonitrile. The product may take the form of absorbent pads or discs for cosmetic or medical purposes.

Description

PRODUCTION OF ABSORBENT HYGIENE PRODUCTS This invention relates to the production of absorbent hygiene products and more particularly to the production of composite hygiene products incorporating at least one absorbent layer and at least one layer of substantially non-absorbent material.

It is known, in the prior art, to produce composite absorbent hygiene products comprising a layer of absorbent material secured to a non-absorbent layer of, for example a thermoplastic film or non-woven web of thermoplastic fibres. The absorbent layer may comprise cotton wadding or a wadding formed from a mixture of cotton and viscose fibres.

In the prior art, the absorbent and non-absorbent layers were secured together by one of three possible means.

If a relatively weak bond was required the layers could be secured together simply by application of pressure (possibly with the addition of heat) to emboss the resultant product and give some cohesion between the layers. If a stronger bond was required an adhesive could be used to impregnate a peripheral zone of the product which was then compressed or the peripheral zone of the product was compressed to a substantial extent between blunt tools (possibly with the addition of heat) to compress the thermoplastic material of the non-absorbent layer into the fibres of the absorbent layer to produce unitary product. Both the use of adhesive and the use of the very high pressures associated with the pressure bonding technique gave rise to a relatively hard and sharp edge to the product which rendered it less than wholly satisfactory for many applications.

We have now discovered a method by which absorbent hygiene products can be formed in a rapid and economic way and yet in which a satisfactory peripheral bonding between the various layers of the product is obtained without forming a hard or sharp edge to the product.

According to the present invention a method of producing an absorbent hygiene product comprises providing a first layer of non-absorbent thermoplastic material; providing a second layer of absorbent material, the second layer comprising a mixture of thermoplastic and nonthermoplastic fibres; and securing the first and second layers to each other to form said product by ultrasonic welding.

Preferably, the second layer comprises cotton or viscose or a mixture of cotton and viscose fibres to provide absorbency and sufficient thermoplastic fibres to provide satisfactory bonding of the layers by the ultrasonic welding technique.

Preferably, the layers are secured to each other around the periphery of the product and the step of ultrasonic welding is carried out substantially simultaneously with the cutting of the product from continuous webs of first and second layer material.

It has been found, that in contrast to the prior art, a peripheral ultrasonic weld between the first and second layers of the present invention is soft and flexible and does not detract from the overall soft feel of the product The amount of thermoplastic fibre present in the second layer is selected to provide satisfactory adhesion between the layers during the ultrasonic welding process and provide adequate absorbency to the finished product. In this context, it will be understood by those skilled in the art that thermoplastic fibres are in general hydrophobic and in the circumstances incorporation of thermoplastic fibres within the absorbent layer may, at first sight, be considered to be a disadvantage. It has been found, however, that the addition of suitable fibres, for example polypropylene, polyethylene, polyester or polyacrylonitrile in an amount of between 12% and 18% provides satisfactory bonding between the layers whilst not substantially reducing the absorbency of the product.

Indeed, it is believed that in some applications the addition of the thermoplastic fibres to the absorbent layer actually improves the characteristics of the absorbent layer. This is because the thermoplastic fibres give rigidity to the absorbent layer when it is wet thereby reducing the fibre collapse which tends to take place if only cotton and/or viscose fibres are present in the absorbent layer.

The technique of ultrasonic welding of flexible sheet materials is, in itself, well known and is commonly used for the production of items from thermoplastic films and/or composites of thermoplastic films and foam materials.

For example, sun visors for motor vehicles are commonly formed by simultaneously ultransonically welding together and cutting out the product from a sandwich of two thermoplastic films and a polyurethene foam core. It is believed, however, that ultrasonic welding techniques have not previously been applied to the formation of an article comprising at least one thermoplastic layer and at least one layer comprising a mixture of thermoplastic fibres and absorbent fibres.

Typically, the invention may be applied to the production of pads or discs for cosmetic or medical purposes. In order that the invention may be better understood a number of examples of the invention will now be described.

In the first example a pad for the application or removal of cosmetics is formed from a first layer comprising a thermoplastic film or a thermoplastic non-woven fabric and .a second layer comprising a mixture of cotton fibres, viscose fibres, and polypropylene fibres, the polypropylene fibres being present in the range 12 to 18%. The layers are assembled together to form a web which is fed through an ultrasonic welding/cutting machine which simultaneously cutsular discs from the composite web and ultrasonically welds the layers of the pad together at the periphery thereof. The resulting pad has been found to have a high level of structural integrity and resistance to delamination and yet has a smooth and soft peripheral edge which does not detract from use of the pad. The presence of the polypropylene fibres within the absorbent layer does not materially affect the feel or effectiveness of the absorbent layer.

In the second embodiment of the invention a cosmetic pad is formed by cutting discs from a feed web comprising a first layer of bonded coarse thermoplastic fibres and a second layer comprising a mixture of cotton, viscose and polypropylene fibres, the polypropylene fibres being present in an amount of between 12 and 18%. Discs are cut from the feed web and simultaneously ultrasonically welded together about the periphery thereof to produce pads one surface of which is formed by the coarse fibre layer.

This layer may be used to exfoliate the skin and remove dead epidermal cells.

In a third example a pad is formed from a feed web comprising first and third layers of light-weight polypropylene spunbonded non-woven material having sandwiched therebetween an absorbent layer comprising cotton and viscose fibres together with polypropylene fibres present in an amount of between 12 and 18% by weight. Discs are cut from the feed web and simultaneously ultrasonically welded together about the periphery thereof to produce an absorbent pad both faces of which are formed by the spunbonded non-woven material. With such discs, the spunbonded material substantially prevents the loss of cotton/viscose fibres from the absorbent core. Such discs are particularly suitable for use in swabbing wounds or for applying disinfectants to wound sites. Further, because the spunbonded surface layers are generally hydrophobic the product will have a relatively "dry" feel to the surface thereof even if the absorbent core is wetted. The product may accordingly be used conveniently for application to small wound sites such as injection or vein puncture sites to provide an absorbent dry low-adherent dressing pad.

In a fourth embodiment of the invention breast pads are formed from a first layer of thermoplastic thermal bonded or spunbonded non-woven fabric; a second layer comprising 85% cotton or a blend of cotton and viscose and 15% polypropylene fibres; and a third layer comprising a barrier of polyethylene film or polyethylene coated cellulose wadding or facial paper tissue. Optionally, the feed web may comprise a fourth layer of a light-weight high bulk polypropylene cover stock to provide an outer layer in the finished product to prevent the breast pad slipping about inside a nursing bra of the wearer. The required pads are cut from the feed web and simultaneously ultrasonically welded together about the periphery thereof. The resultant products have a soft dry surface provided by the thermal bonded or spunbonded non-woven material and an absorbent core provided by the cotton/viscose/polypropylene fibre layer. In contrast with prior art breast pads produced by cutting from a composite feed web the breast pad according to the present invention has a soft peripheral edge which does not lead to irritation of the skin of the wearer.

Heretofore, to avoid a hard peripheral edge to the product, high quality breast pads were formed by cutting an inner absorbent pad to a smaller diameter than that of the barrier layer and facing layer so that only the outer layers of the pad were bonded together around the periphery thereof by suitable heat sealing techniques. Although this produced a relatively soft edge to the pad the required production technique was relatively complicated with a result that the product was relatively expensive to produce.

Claims

CLAIMS:

1. A method of producing an absorbent hygiene product comprises providing a first layer of non-absorbent thermoplastic material; providing a second layer of absorbent material, the second layer comprising a mixture of thermoplastic and non-thermoplastic fibres; and securing the first and second layers to each other to form said product by ultrasonic welding.

2. A method according to claim 1, wherein the second layer comprises cotton or viscose or a mixture of cotton and viscose fibres to provide absorbency and sufficient thermoplastic fibres to provide satisfactory bonding of the layers by the ultrasonic welding technique.

3. A method according to claim 2, wherein the thermoplastic fibres in the second layer amount to between 12% and 18% of the second layer and preferably amount to 15% of the second layer.

4. A method according to claim 1 or claim 2, wherein the thermoplastic fibres are fibres of polypropylene, polyethylene, polyester or polyacrylonitrile.

5. A method according to any preceding claim wherein the layers are secured to each other around the periphery of the product.

6. A method according to claim 5 wherein the step of ultrasonic welding is carried out substantially simultaneously with the cutting of the product from continuous webs of first and second layer material.

7. A method according to any preceding claim wherein the product incorporates additional layers and all layers of the product are simultaneously secured together by a single ultrasonic welding step.