GB2096902A

GB2096902A - Sanitary pads

Info

Publication number: GB2096902A
Application number: GB8211167A
Authority: GB
Original assignee: Courtaulds PLC
Current assignee: Akzo Nobel UK PLC
Priority date: 1981-04-16
Filing date: 1982-04-16
Publication date: 1982-10-27

Abstract

A sanitary pad 1 is made of a fibrous needlefelt 5 secured to a substantially impervious backing 6. The needlefelt has sufficient integrity and the required aesthetics for use without a fabric cover and this gives benefits in cost saving and more rapid fluid uptake. Cellulosic fibres are suitable for making the needlefelt, particularly high absorbency hollow fibres having a multi-limbed cross- section.The sanitary pad is useful in the mini-pad and panty liner markets. <IMAGE>

Description

SPECIFICATION Sanitary pads This invention relates to a sanitary pad and is particularly concerned with the smaller pads for use during light menstrual flow or as a safeguard or clothes protector between periods.

The conventional sanitary pad is a mass of absorbent material, for example fluffed wood pulp and/or paper tissue, enclosed in a cover which is usually a non-woven fabric. Commonly, it has a sheet of impermeable plastics film bonded to the face which is to lie against the wearer's clothes to prevent leakage or wicking from the pad. The small sanitary pads known as mini-pads are also of this general construction.

A newer type of small pad, used primarily as a panty liner between periods, is of laminate construction, being essentially a layer of pulp or tissue sandwiched between a plastics film backing and a non-woven cover. The latter does not enclose the whole pad but terminates in a free, cut edge.

We have devised a sanitary pad of simplified and improved construction. According to this invention, a sanitary pad comprises an elongate layer of a fibrous needlefelt secured to a substantially impervious backing layer.

Whilst it is possible to overlay the face of the needlefelt remote from the backing layer with a cover fabric, we have found that the needlefelt itself possesses sufficient integrity and has the required aesthetics for use in a sanitary pad without a cover. In addition to saving on its cost, the absence of a cover allows a more rapid uptake of fluid by fibres of the needlefelt and makes the pad easier to flush away. The needlefelt has a higher rate of fluid wicking, and an improved retention of fluid under load compared with other absorbent material such as fluffed wood pulp. It also has excellent resistance to abrasion.

The needlefelt preferably comprises cellulosic fibres, especially regenerated cellulose fibres.

Blends with other fibres may be used, but for the best absorbency and purity standards the needlefelt should be made from 100 per cent cellulose fibres. Absorbency is increased by the use of finer fibres, for example 4 dtex and below, and can be increased further by the use of the highly absorbent grades of regenerated cellulose fibres, either alone or in blend. One such fibre made by Courtaulds Limited is hollow, with a multi-limbed cross-section, and is described in British Patent Specification No.

1,393,778.

The density of the needling operation top which the needlefelt has been subjected need be no more than is required to give it the required integrity. We have used needle densities of 258 punches/cm2 quite satisfactorily and lower densities such as are used in so-called tack-needling are quite adequate. Indeed, over-needling is to be avoided because it reduces the absorbency of the needlefelt and can adversely affect its aesthetics.

The specific absorbency of the needlefelt, that is the weight of fluid in grams which a gram of felt will hold, has been found to increase as the basis weight (g/m2) of the needlefelt decreases. Thus there is a diminishing benefit in increasing the basis weight beyond what is required for the purposes of pad structure and absorbency. Basis weights in the range 150 to 600 g/m2 generally will provide the range of absorbencies required for the smaller type of pad, with basis weights at the lower end of that range, say 150 to 350 g/m2, being suitable for panty liners.

The sanitary pad of the invention is elongate in shape and may be generally rectangular with rounded ends. The centre portion of the pad may be a little narrower than one or both end portions to improve its comfort in use.

The performance of the pad, in terms of making use of as much of its area as possible for absorbing fluid, is improved if the needlefelt has a degree of fibre orientation length-wise of the pad.

This promotes preferential wicking of fluid along the length of the pad so that fluid initially absorbed in a centre portion is drawn away towards both ends rather than being allowed to saturate the centre portion of the pad and leave the end portions unused. The orientation may be achieved in known manner during the laying down of the fibres to form the web which is needled to convert it to a needlefelt.

The face of the needlefelt which is remote from the backing layer, i.e. that face which is to contact the body in use, may be finished to reduce any slight hairiness. For example, it may be given one or more of a number of treatments including hot pressing, calendering, schreinering and chemical finishing.

The substantially impervious backing layer may be a synthetic organic polymeric material, formed either as a separate layer which is bonded to the needlefelt or formed in situ by coating. Polyolefin films are suitable, particularly polyethylene. Acrylic polymers or copolymers may be coated onto the needlefelt, for example by extrusion coating, to form a backing layer.

The sanitary pad of the invention may have means for securing the pad in position during use. The preferred means comprises one or more stripes or spots of adhesive material located on the exposed face of the backing layer, so that the pad may be removably stuck in position inside a pair of pants. The adhesive may be protected by a release strip which is peeled off the pad prior to use.

Manufacture of the sanitary pads of the invention may be carried out by making a needlefelt of the desired basis weight, slitting to a suitable width for making a sanitary pad, and then feeding it to a padmaking machine together with the other components of the pad. In this machine the needlefelt is bonded to the backing layer, adhesive is printed onto the face of the backing layer and covered by a release strip, the laminate is cut to pad size and shape, and the resulting pads are packaged.

If the backing layer is formed by coating the needlefelt, this may be done prior to the slitting operation. Similarly any treatment of the body-contacting face of the needlefelt is suitably carried out before it is slit to pad width.

The invention will now be described, by way of example, with reference to the accompanying drawing, in which~ Figure 1 is a plan of a sanitary pad according to the invention, Figure 2 is a sectional view, on an enlarged scale, taken on the line Il-Il of Figure 1, and Figure 3 is a schematic sectional view of apparatus used to measure the absorbency of the needlefelt component of a sanitary pad according to the invention.

Referring to Figure 1, the sanitary pad 1 is of the elongate shape shown with end portions 2 and 3 slightly wider than the centre portion 4. As shown in Figure 2, the pad is a laminate of a layer of a fibrous needlefelt 5 bonded to a backing layer 6 of a plastics film. The clothes-contacting face 7 of the backing layer is printed with a stripe of adhesive material 8 which is protected by a release paper strip 9.

The absorbency measuring apparatus shown in Figure 3 comprises a table 10 having a central orifice 1 1 of 0.3 cm diameter connecting with a tube 12 leading via a T-piece 1 3 to a fluid reservoir 14 and a horizontal burette 1 5. A clamp 16 is provided on the tube 1 7 connecting the reservoir 14 to the T piece 13.

The system is filled with test solution, for example saline solution or blood, by opening clamp 1 6 which is then closed again to isolate the reservoir. The horizontal burette is levelled so that there is zero fluid pressure at the orifice 1 The table 10, which is coated with PTFE, is wiped clean of test solution, and then a circular, weighed sample 1 8 of needlefelt 4 cm in diameter is placed centrally over the orifice 1 1 and covered with a weighted plate 19, also coated with PTFE, and impressing a load of 12.3 g/m2 on the sample. The sample 1 8 and the weighted plate 1 9 are shown suspended over the table 1 0 for the sake of clarity.

The sample gradually takes up the test fluid from the orifice and as that happens the fluid meniscus 20 gradually moves along the horizontal burette. When the sample is saturated and no longer 'demanding' further fluid from the system, the meniscus remains static, and that is the end-point of the test. The saturated sample of needlefelt is then removed from the apparatus and is rn-we)ghed. The absorbency is then calculated as: Wet weight - Dry weight Absorbency = g/g.

Dry weight The invention is illustrated by the following Examples:~ EXAMPLES 1 TO 8 Sanitary pads as described with reference to, and as illustrated in, Figures 1 and 2 were made from needlefelt of various basis weights and varying densities of needling. In the first four Examples the fibres used to make the needlefelt were 3.3 dtex crimped, round cross-section regenerated cellulose fibres ("Sarille" -Trade Mark) and in Examples 5 to 8, the fibres were 25 per cent by weight of "Sarille" fibres and 75 per cent by weight of 3.3 dtex hollow regenerated cellulose fibres having a multi limbed cross-section (made by Courtaulds Limited and code-named "5.1." Fibres).

The needlefelts were tested for absorbency using the demand wettability test described with reference to Figure 3, both with a 1 per cent by weight saline solution and with animal blood. The results are shown in the following table~

Basis Needle Saline Blood weight density absorbency absorbency Example g 1m2 punches /cm2 9/9 9/9 100% 100% "Sari l le" 1 170 258 10.44 10.30 2 235 397 8.91 8.90 3 250 258 9.69 9.70 4 350 258 8.75 9.00 75% "8.1." and 25% "Sari l le" 5 170 258 12.33 12.40 6 235 397 11.43 11.70 7 250 258 11.29 11.90 8 350 258 10.77 11.30 The needlefelts were also tested for abrasion resistance using the Martindale test. All were satisfactory, giving only slight surface pilling after 2,000 rubs.

Claims

1. A sanitary pad comprising an elongate layer of a fibrous needlefelt secured to a substantially impervious backing layer.

2. A sanitary pad as claimed in claim 1, in which the face of the needlefelt remote from the backing layer is not overlaid by a cover fabric.

3. A sanitary pad as claimed in claim 1 or claim 2, in which the needlefelt comprises cellulosic fibres either exclusively or in blend with other fibres.

4. A sanitary pad as claimed in claim 3, in which the cellulosic fibres comprise hollow fibres having a multi-limbed cross-section.

5. A sanitary pad as claimed in any of claims 1 to 4, in which the needlefelt comprises fibres having a fineness of 4 dtex or less.

6. A sanitary pad as clairned in any of claims 1 to Sin which the needlefelt has a degree of fibre orientation lengthwise of the pad.

7. A sanitary pad as claimed in any of claims 1 to 6, in which the needlefelt has a basis weight in the range of from 1 50 to 600 g/m2.

8. A sanitary pad as claimed in any of claims 1 to 6, in which the needlefelt has a basis weight in the range of from 150 to 350 g/m2.

9. A sanitary pad as claimed in any of claims 1 to 8, in which the face of the needlefelt remote from the backing layer has been given a finishing treatment to reduce its hairiness.

10. A sanitary pad as claimed in any of claims 1 to 9, in which the substantially impervious backing layer comprises a -layer of synthetic organic polymeric material.

1 1. A sanitary pad as claimed in claim 10, in which the layer of a synthetic organic polymeric material has been formed by coating said material onto the needlefelt.

12. A sanitary pad substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.

13. A sanitary pad substantially as hereinbefore described in any of the Examples.

14. A sanitary pad as claimed in claim 1, and substantially as hereinbefore described.