HUT77908A - Flexible and water vapour permeable absorbent articles and their fixation to undergarments - Google Patents

Description

THE PROCTER & GAMBLE COMPANY, CINCINNATI, Ohio, US

Date of filing: 16.10.1995.

Priority: 11.11.1994 (94203229.3), US

International Application Number: PCT / US95 / 14036

International Publication Number: WO 96/14036

BACKGROUND OF THE INVENTION The present invention relates to a flexible absorbent article for use in an undergarment, optionally comprising side tabs, a backsheet, underbody surface, and an absorbent core, wherein the backsheet surface comprises an adhesive having an actual adhesive surface and defining a theoretical adhesive surface, a liquid impermeable and absorbent article wherein the ratio of actual adhesive surface to the underwear surface is 0.2-0.8, and the theoretical adhesive surface to the underwear surface is in the range of 0.5 to 1.0 for articles without side tabs; The flexibility of this article is in the 1300-5000 mg.cm range.

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63.829 / BE é & 3 I jk

KÖZZÉTÉTEU

COPIES

S.B.G. & K.

International Patent Office

H-1062 Budapest, Andrassy út 113. Phone: 34-24-950, Fax: 34-24-323

Flexible and vapor permeable absorbent articles and their attachment to underwear

THE PROCTER & GAMBLE COMPANY, CINCINNATI, Ohio, US

Inventor:

QUERQUI Daniela, KÖNIGSTEIN, DE

Date of filing: 16.10.1995

Priority: 94203229.3, 05.11.1994.

International Application Number: PCT / US95 / 13546

International Publication Number: WO 96/14036 • · ·

The present invention relates to water vapor permeable absorbent articles, such as sanitary napkins, panty liners and incontinence pads, which are adhered to the underwear during use. More particularly, the present invention relates to water vapor permeable and longitudinally flexible articles which provide increased wearer comfort.

Disposable absorbent articles such as baby diapers, cat incontinence pads, sanitary napkins and panty liners are well known in the art. These articles have a wearer-facing side through which absorbent fluids are typically absorbed by the wearer. The liquid is stored in an absorbent structure. The leakage of liquid on the opposite side of the wearer's body is generally prevented by installing a liquid impervious backsheet on this side.

It is accepted in the art that a backsheet that allows air to circulate to the environment, commonly referred to as breathability, is highly desirable. Breathability increases with the amount of air flowing through the backside. This amount is proportional to the open surface (sum of the surface area of all openings) in the backsheet. Improving breathability obviously leads to a trade-off in preventing fluid leakage, the primary function of the backsheet.

There are many suggestions in the art for making breathable backsheets. Several attempts have been made in the patent and patent applications to combine the contradictory properties of air permeability and liquid impermeability. However, the lack of commercially available breathable disposable absorbent articles which are also highly flexible shows that the technology proposed so far has not produced satisfactory results in all required technical requirements under acceptable commercial conditions.

The sanitary napkins, panty liners, and incontinence pads are typically worn on the undergarment portion of the underwear and are secured to the underwear by a so-called panty fastener. They are intended for everyday use and breathability is desirable in order to enhance the comfort of the wearer. In particular, it is believed that removing water vapor from such articles will reduce sweat, choke and warmth.

It has also been found that in order to be comfortable for the wearer, these articles must be flexible. The opinion that the more flexible an absorbent article is, the less it is perceived by the wearer. Therefore, it provides a feeling of comfort that is closer to the situation when such an absorbent article is not worn.

Flexibility can be easily achieved by reducing the amount of material in the absorbent article or replacing rigid or non-flexible components with flexible materials. However, it has long been recognized that excessive flexibility may also diminish the effectiveness of these articles, for example, by inadequate amount of absorbent material or by the use of absorbent material. During this period, it will clump or increase in density. An article that is too flexible may be difficult for the wearer to handle when attaching it to the underwear.

For example, the problem of too small a non-flexible material content, which causes too much flexibility, has been raised in U.S. Patent No. 4,217,901, which specifically increases the stiffness of the absorbent article in order to provide adequate efficiency. This prior art literature recognizes the convenience aspects associated with certain rigidity requirements. This literature does not take into account breathability.

Therefore, absorbent articles that are flexible and breathable would be highly desirable. However, using a perforated backsheet and a flexible, i.e. thin absorbent article, would be too risky to leak through the backsheet. Therefore, especially for thin, low absorption products, it has been accepted that the backsheet should not be breathable to prevent leakage.

Therefore, as an alternative to the simultaneously announced Breathable Backsheet Design for Disposable Absorbent Articles and Breathable Dual Layer Backsheet Design for Disposable Absorbent Articles, The new multi-layered, breathable backsheets disclosed in The Procter and Gamble Company patent applications are proposed and may be considered as alternatives. These multi-layered back designs also measure a certain amount of · ·

- They counteract improved flexibility for up to 5 sticks, as additional layers increase rigidity rather than flexibility.

Other prior attempts to provide breathable backsheet compositions comprising more than one layer, such as those described in U.S. Patent Nos. 3,341,216 and European Patent Specifications A-109.126 or A-203,821. One-layer, breathable backsheets include

They are known from United Kingdom Patent Nos. A-2184391, A-2184390, A-2184389, US 4,591,523 and US-A-4,839,216, or European Patent Publication No. 156471. None of these patents raise the convenience problems associated with rigid or insufficiently flexible absorbent articles. Some of them suggest that sufficient absorbent material should be provided to deal with potential leakage situations. However, this increases stiffness at the expense of breathability.

Therefore, it is an object of the present invention to solve the problem of leakage through the backsheet, flexibility and breathability. The benefits of breathability and flexibility, and in particular the ability of the article to easily bend and twist in longitudinal and preferably all directions, have become crucial, especially for everyday absorbent articles such as panties, sanitary napkins and incontinence pads.

It has been found that the problem of perforated breathable backsheet leakage can be prevented while maintaining the advantage of using water vapor permeable films. At the same

·· ·· · • · · · ·: ·· :: ·. * · · · Λ the comfort provided by absorbent articles can be dramatically enhanced by providing high flexibility in the longitudinal direction and combining it with a special panty-fastener configuration so that the vapor-permeable article is kept smooth relative to the wearer's underwear. In this case, flexibility is limited only by the material's strength requirements and the requirements for handling the absorbent article.

Therefore, it is an object of the present invention to provide sanitary napkins which have increased flexibility without the disadvantages experienced previously. High flexibility and breathability without backsheet perforation is advantageously achieved without clumping or greater handling difficulties by keeping the design parameters of the articles within a selected value range.

These and other objects of the invention will become more apparent from the following description.

Summary of the Invention

The present invention provides a water vapor-permeable absorbent article such as a sanitary napkin for underwear, an incontinence pad, and particularly a panty liner. The absorbent article has a non-perforated, water vapor-permeable, and backside-facing backsheet. An adhesive is placed on the surface facing the underwear, which serves to glue the article to the underwear.

Optionally, the article may include protective side surfaces that are folded around the side edges of the undergarment pad portion during use to assist in protecting the underwear from soiling. The absorbent article further comprises other typical components of such articles, namely, an absorbent core and a fluid-permeable surface facing the wearer's body, preferably formed by a liquid-permeable topsheet. The absorbent article comprises a liquid-permeable backsheet which, as is customary, forms the underwear side of the absorbent article. If a topsheet and a backsheet are present, the absorbent core is enclosed therein on the wearer or on the underwear side of the article.

The adhesive may be applied to all, part, or a plurality of defined portions of the surface facing the undergarment. Apply the adhesive in such a way that it does not block the entire area. If it covers the entire surface of the underwear, it may be randomly or in the form of a specific pattern, such as spiral lines. The total surface area of the adhesive on the underwear side of the absorbent article determines the actual bonding surface. In addition, a theoretical adhesive surface is defined by an infinite circumference, which is the shortest boundary of the adhesive that does not extend beyond the circumference of the underwear surface itself.

The absorbent article according to the present invention has a theoretical adhesive surface / underwear surface ratio for articles having protective side tabs of 0.6 to 1, preferably 0.85 to 1, and for articles having protective side tabs of 0.5 to 1. 1, preferably 0.7-0.9. In a preferred embodiment, the theoretical adhesive surface is substantially the same,

- 8 ······················································································································································ · · · · · · · · · · · · · · · · · · · · · · ·

In order to realize the advantages of the present invention, the absorbent article as a whole must have excellent flexibility. Flexibility is measured longitudinally according to ASTM D 1388 as described below. The term "flexibility due to this special method" is also called "wrinkling." It should be noted that the opposite behavior of matter is stiffness. The flexibility should be in the range 1300-5000, preferably 2000-3500, most preferably 200-3000 mg x cm.

These flexibility values, in combination with the surface area ratios indicated above, provide excellent wearer comfort without causing contamination and / or absorption problems due to aggregation or density of the absorbent material, and yet allow the wearer to exert excessive force on the article. for underwear. According to the present invention, flexibility is measured in the longitudinal direction because this value is easier to measure and more important. In principle, we could use transversal flexibility, which probably has a different value. However, given that the extensibility of the articles in the transverse direction is low, it is generally not possible to properly measure the extensibility in this direction.

Preferred panty liners according to the present invention have a thickness of less than 3 mm, more preferably in the range of 0.5 to 1.5 mm, according to the thickness measurement method described below.

The combination of adhesive coating and flexibility of the appropriate panties is particularly applicable to the expandable absorbent articles. For absorbent articles that can be stretched in one direction and more particularly for absorbent articles that are stretchable in two (or all) directions and are substantially flexible. The extensibility itself provides an improvement in the comfort feeling that absorbent articles combining extensibility with the present invention are particularly desirable.

Particularly useful are extensible absorbent articles having stretching properties as disclosed in U.S. Patent Application Serial No. 08 / 192,240 and in the table in Figure 7 of that application.

Another key factor of the present invention is the water vapor permeability of the backsheet of absorbent articles. The articles of the present invention have a water vapor-permeable backsheet which is not perforated. The back cover does not allow liquid to pass through. Achieving this property requires a water vapor permeable layer that is impermeable to the liquid. This can be provided by one or more additional layers that perform different functions. In particular, this may be, for example, a very thin, water vapor-permeable, thermoplastic film provided with another continuous film, such as openings, which does not delay the water vapor transmission but increases the material strength and / or with an additional layer that gives the back of the backside a pleasant, fibrous layer that resembles textiles.

- 10 Brief Description of the Figures

Fig. 1 is a top plan view of the undergarment surface of the panty liner of the present invention, which does not include protective tabs.

Fig. 2 shows the underwear side of another embodiment of a sanitary napkin having protective side tabs of the present invention.

Detailed Description of the Invention

The invention is described in terms of panty liners, but can also be applied to underwear sanitary napkins and incontinence articles, and is attached to the absorbent article during wear.

The absorbent articles of the present invention typically comprise three main components: a liquid-permeable topsheet, a water-vapor-permeable backsheet, and an absorbent core. The absorbent core is closed by the backsheet and topsheet and is worn such that the outer surface of the topsheet of the absorbent article faces the wearer while the outer surface of the backsheet faces toward the undergarment to which the article is secured by a panty fastener. This is typically an adhesive but may also be a mechanical fastener.

The present invention relates to the article's flexibility and water vapor permeability. The degree of flexibility, as mentioned above, is determined by the choice of material of the components of the article and their relative amounts. It will be apparent to those skilled in the art that in order to achieve the flexibility of the invention,

The amount of absorbent article should be balanced with other desirable characteristics of the absorbent article, such as absorbent capacity, absorbency, and surface dryness of the outer surface of the topsheet during use.

Therefore, the following description of typical materials for the main components of an absorbent article will allow for an almost infinite number of article variants within and outside the flexibility limits of the present invention. Whether an absorbent article meets the flexibility requirements of the present invention can be verified by the simple measurements described below.

In a preferred embodiment, the absorbent articles of the present invention may be elastically stretched. By "elastically stretchable" is meant that when the stretching force is released, the article attempts to return to unstretched or unstretched (i.e., original) dimensions, but does not necessarily have to reach its unstretched dimensions. If the absorbent article is elastically extensible, it can be stretched in one or two (non-parallel) directions in the plane of the article, i.e. parallel to the underwear surface.

The materials of the elastically stretchable articles may themselves be elastically stretched or manipulated so as to be elastically stretchable. To this end, particularly elastic backsheet material, elastic topsheet material, fibrous materials combined with elastic fibers, yarns or duvets may be used, as well as retracting, creasing or annular rolling. Materials and methods for this purpose are known in the art and are described in detail in U.S. Serial No. 08 / 192,240. . * · · ··: -:: ··· '·'.

U.S. Patent Application Serial No. ..... .. · · · ···,, which is incorporated herein by reference to facilitate the selection of materials suitable for the manufacture of stretchable absorbent articles of the present invention.

The following describes non-limiting embodiments of the main elements of absorbent articles that can be used for flexible or non-flexible designs.

The absorbent core

The absorbent core typically comprises the following components: (a) optionally, a primary fluid distribution layer; (b) optionally, but preferably, a second fluid distribution layer; (c) a fluid storage layer; (d) optionally a fibrous ("dusty") layer disposed beneath the storage layer; and (d) optionally other components.

(a) Primary fluid distribution layer

An optional component of the absorbent cores of the present invention is a primary fluid distribution layer. This primary fluid distribution layer is typically located underneath the topsheet and in fluid communication therewith. The topsheet transfers the collected menstrual fluid to this primary distribution layer and then to the storage layer. This fluid transfer occurs not only along the thickness of the topsheet but also along the length and width of the absorbent article.

(b) Optionally, a second fluid distribution layer

Optional absorbent cores of the present invention

13 used but preferred components are a second fluid distribution layer. This second distribution layer is typically located below and in fluid communication with the primary distribution layer. The purpose of this second distribution layer is to readily absorb the menstrual fluid from the primary distribution layer and rapidly transfer it to the underlying storage layer. This facilitates the use of the underlying storage layer to the full.

- 14 • · · 9 • · * ♦ »« »<* ·· ♦ ·

c) Liquid storage layer

In a manner communicating with and typically below the primary and secondary distribution layers, there is provided a fluid storage layer containing certain gelling and / or other absorbent materials which may form a carrier matrix of the absorbent gelling materials. Absorbent gelling agents are generally referred to as "hydrogels," superabsorbent, "hydrochlorides. Absorbent gelling agents which upon contact with water-containing liquids, in particular aqueous body fluids, absorb such liquids to form hydrogels. These absorbent gelling materials are capable of absorbing large amounts of body fluids and of holding such absorbent fluids under moderate pressure. These absorbent gelling materials are typically discrete, non-fibrous particles.

The liquid storage layer may comprise only gelling agents or these absorbent gelling materials may be homogeneously or non-homogeneously distributed in a suitable carrier or may consist of a single absorbent carrier. Suitable carriers are fluffy, fibrous, or paper-like cellulosic fibers commonly used in absorbent cores.

Modified as stiffened cellulose fibers and synthetic fibers can also be used, such as cellulose acetate, polyvinyl fluoride, polyvinylene chloride, acrylic (such as Orion) fibers, polyvinyl acetate, insoluble polyvinyl alcohol, polyethylene, polypropylene (n) , polyester, bicomponent and tricomponent fibers, mixtures thereof, and the like. Preferred synthetic fibers have a thickness of about 3-25 denier per filament. The fiber surface is preferably hydrophilic or hydrophilic treated. The storage layer contains fillers such as perlite, diatomaceous earth, vermiculite, etc. which may reduce the problem of rehydration.

If the storage layer is dispersed in an inhomogeneous manner, it may be locally homogeneous, i.e. it may have a distribution gradient in one or more directions within the dimensions of the storage layer. The inhomogeneous distribution may also apply to carrier laminates containing partially or completely absorbent gelling materials.

If absorbent gelling materials are present, the storage layer preferably contains from about 15% to about 100% absorbent gelling material and from about 0% to about 85% carrier material. The storage layer is preferably about 30% to about 100%, most preferably about 60% to about 100% of the absorbent gelling material, and about

0-70%, most preferably about 0-40% by weight.

Suitable gelling agents for use herein are mainly substantially water-insoluble, slightly cross-linked, partially neutralized polymer gelling agents. This substance forms a hydrogel in contact with water. Such polymeric materials can be prepared from polymerizable, unsaturated, acid-containing monomers. Suitable unsaturated acid monomers for use in the preparation of polymeric absorbent gelling materials used in the present invention include those listed in U.S. Patent No. 4,654,039, re-published under RE 32649. Preferred monomers include acrylic acid, methacrylic acid and 2-acrylamido.

- 16 -2-acrylamido-2-methylpropanesulfonic acid. Acrylic acid is particularly preferred for the preparation of the polymer gelling agent. The polymeric component of unsaturated acidic monomers is grafted onto other types of polymeric molecules, such as starch or cellulose.

Polyacrylate-grafted starches of this type are particularly preferred. Preferred polymeric absorbent gelling materials prepared from conventional types of monomers include hydrolyzed acrylonitrile-grafted starch, polyacrylate-grafted starch, polyacrylates, maleic anhydride-based copolymers, and combinations thereof. Polyacrylates and starch grafted with polyacrylate are particularly preferred.

Although these absorbent gelling materials are typically particulate, it is also possible that they are macrostructured, such as fibers, sheets, or strips. These macrostructures are typically prepared by converting the particulate absorbent gelling material into an aggregate, treating the aggregate with a suitable crosslinking agent, compacting the treated aggregate to form a coherent mass, and then compacting the compacted aggregate reacting the crosslinking agent with the particulate absorbent gelling agent to form a composite, porous, absorbent macro structure. Such porous absorbent macrostructures are described, for example, in U.S. Patent No. 5,102,597.

(d) Optional fibrous layer (s)

The absorbent cores of the present invention may optionally incorporate a fibrous layer adjacent to the storage layer, typically beneath it. This underlying fibrous layer is typically referred to as a "dusty layer" because it forms a substrate on which absorbent gelling material is deposited in the storage layer during the manufacture of the absorbent. This layer may contain any of the materials referred to above as carriers for the storage layer. Indeed, in situations where the absorbent gelling material has a macrostructure, i.e., fibrous, sheet or stripe, there is no need for such a "dusty layer." However, since this powdery layer provides some additional fluid handling capability, the ability for the liquid to be absorbed rapidly along the length of the pad is advantageous for the absorbent materials of the present invention.

(e) Other components, if applicable

The absorbent cores of the present invention may optionally contain other components that are normally present in the absorbent webs. For example, a reinforcing lining fabric may be disposed within or between each layer of the absorbent core. Such reinforcing lining fabrics must be shaped such that they do not form fluid barriers between surfaces, particularly when placed between the respective layers of the absorbent core. As a result of the structural integrity resulting from the heat fixation, the absorbent structures of the present invention generally do not require reinforcing lining fabrics, as they may cause the required flexibility to not be achieved.

The absorbent core of the present invention preferably has a primary

Another component which is an odor control agent can be incorporated near or as part of the 18 or secondary fluid distribution layer. Optionally, the absorbent core is typically embedded with activated carbon coated with suitable zeolite or clay materials. These components may be of any shape, but are often discrete, non-fibrous particles.

The cover

The topsheet is an elastic, soft-feeling material that does not irritate the wearer's skin. As mentioned above, the topsheet may be elastically stretchable in one or two directions. In addition, the topsheet is liquid-permeable, allowing liquids (menses and / or urine to easily penetrate through its thickness. Suitable topsheets can be made from a variety of materials such as woven and nonwoven materials; polymeric materials such as perforated, shaped foils; porous foams; Suitable woven and nonwoven materials may comprise natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polymeric fibers such as polyester, polypropylene or polyethylene fibers) or a combination of natural and synthetic fibers.

Preferred topsheets of the present invention are textured nonwoven topsheets and perforated molded foil topsheets. Perforated molded foils are particularly advantageous for topsheets because they are permeable to body fluids, yet non-absorbent and have a reduced tendency to allow fluids to flow back and thus wet the wearer's skin again. . Thus, the surface of the formed film in contact with the body remains dry, thereby reducing body contamination and providing a more comfortable feel to the wearer. Suitable shaped films are described in 3,929,135; 4,324,246; 4,342,314;

463,045; and U.S. Patent No. 5,006,394. Particularly preferred microperforated film topsheets are disclosed in U.S. Patent Nos. 4,463,045 and 5,006,394. Preferred topsheets of the present invention are molded foils as described in one or more of the above-mentioned patents sold by Procter & Gamble Company, Cincinnati, Ohio, under the name DRI-WEAVE.

The body surface side of the formed film topsheet may be hydrophilic to help the liquid penetrate the topsheet faster than if the body top side was not hydrophilic. In a preferred embodiment, the wetting agent is incorporated into the polymeric material of the formed film topsheet as described in U.S. Patent Application No. 92 / 092,227. Alternatively, the body surface of the topsheet may be hydrophilized by treatment with a wetting agent, as described in U.S. Patent 4,950,254, cited above.

Water vapor permeable back cover

The water vapor-permeable and liquid-impervious backsheet prevents materials absorbed in and absorbed from the absorbent core from wetting articles that are in contact with the sanitary napkin, such as panties, pajamas, or underwear. The back panel contains a layer of water vapor permeable to the air 20 ·· ··. The backsheet may also comprise a polymer film with apertures to provide structural strength to the backsheet. It may also be a layer of fibrous textile material forming a backsheet surface, particularly its undergarment surface.

The water vapor-permeable layer may be a polymeric film having apertures of molecular size. The film may be, for example, GORETEX or ®

A SYMPATEX type structure well known in the art for providing breathable clothing. Films of European Patent Application No. A-293,482 may also be used in the present invention. Another vapor-permeable film for use as a backing sheet in accordance with the present invention is, for example, XMP-1001 from Minnesota Mining and Manufacturing Company, St. Paul, Minnesota.

Adhesive for panties

Typically, the backsheet forms the underwear surface on which the adhesive is applied.

According to the present invention, it is important that the ratio of the theoretical adhesive surface to the actual underwear surface is in accordance with the claims of the invention. The theoretical bonding surface is defined by the area which is the shortest possible infinite line that surrounds the panty fastener, but without extending beyond the circumference of the underwear side.

In addition, the ratio of the actual adhesive to the underwear surface is in the range of 0.2-0.8.

For example, if the undergarment side has a rectangular adhesive surface, the theoretical adhesive surface and the actual adhesive surface are the same as shown in Figure 1, where the adhesive 22 is indicated by hatching. The outline 26 results in a theoretical adhesive surface 24 which is identical to the adhesive coated surface 22. In the absorbent articles having protective tabs according to Fig. 2, the three adhesive surfaces 22 are smaller than the theoretical adhesive surface 24 surrounded by line 26. If the backsheet can be flexibly stretched, the adhesive surfaces are measured on the unstretched backsheet before tensioning.

The panty fastener may be any adhesive or glue used in the art, preferably pressure sensitive adhesive. Suitable adhesives include Century A-305-IV, manufactured by Century Adhesives Corporation, Instant Lock 34-2823, manufactured by National Starch Company. Sigma 3153 from 3 Sigma and Fuller H-2238ZP from a. Manufactured by B. Fuller Co. Suitable adhesive fasteners are also described in U.S. Patent No. 4,917,697.

In order to maintain the water vapor permeability of the backsheet of the present invention, it is important that the panty liner adhesive does not block or block the entire undergarment surface of the backsheet. For this purpose, the adhesive may be used such that it seals only a portion of the surface so that no more than 80% of the surface of the underwear side is covered with adhesive. On the other hand, a 20% adhesive coating was found necessary to properly attach the absorbent article to the underwear.

Therefore, the panty liner adhesive is applied in a batch pattern such as batches of dots, stripes, random dots, stripes, or designed fiber patterns such as spirals, which allows the sanitary napkin to remain water-permeable.

In addition, other fasteners may be used instead of adhesives. These other fasteners are arranged in a pattern similar to adhesives. Such fasteners include, but are not limited to, conventional VELCRO hooks and similar fasteners.

The protective side tabs may also have fasteners, optionally for additional safety. These optional tabs may be of any of the aforementioned types. The fasteners help protect the side tabs to remain in place after folding in between the edges of the pad insert.

Before using the absorbent article, the panty liner adhesive is typically protected from soiling or adhering to an unwanted surface. This is done with a protective cover such as silicone coated release paper, plastic foil or any other easily removable cover. The protective cover device may consist of one or more pieces, for example, to cover each adhesive surface.

Measurement of flexibility or crease

The flexibility / crease of the absorbent article is measured by the following procedure:

Reference

ASTM Method D 1388-64: Standard Methods for Testing the Textile Stiffness (Modified as described herein).

Measurement principle

This test is based on the cantilever beam principle. Measure the distance over which a test strip can be extended on a flat platform before bending at an angle of 41.5 ° C. The interaction between specimen mass and stiffness, such as bending or creasing of the specimen under its own mass, is measured at a given angle under the given test conditions and used to calculate flexibility / crease.

General remarks

Flexibility testing is only one way of measuring the flexibility of the specimen and is believed to be one of the factors that users of absorbent articles often refer to as softness. This measurement method should be followed as accurately as possible and should not be confused with the multidirectional flexibility described in U.S. Patent No. 5,009,653. Only longitudinal testing of specimens is described, and according to the present invention it is necessarily possible to measure the transverse flexibility of very wide or exceptionally flexible articles.

Generally, a test strip is measured only once. The two sides of the test piece shall be measured on different test strips. If, similarly, the test strips used for this test have to be handled with great care to prevent shoots, folds, bends, etc. The test shall be carried out on articles which have not yet been folded or bent by the manufacturer. If the sample has been folded by the manufacturer, it shall be unfolded for testing. If only folded articles are available, the flexibility / crease may be approximated by taking the specimens out of the material between the fold lines. The test must be carried out on complete test pieces, ie all layers of the same shape, covering the entire surface of the test piece and fully bonded. For each sample, four different test pieces shall be measured with the top and the bottom exposed at the bottom. The test pieces shall be measured longitudinally.

Note that for relatively rigid articles, measurements may not be possible even longitudinally because the specimen is not long enough to be bent at 41.5 °.

Equipment

Cantilever fabric SDL 003B SDL stiffness gauge (manufactured by Cári von Gehlen, Germany)

25.4 mm cutting blade 25.4 mm wide double-edged cutting blade

Room talc powder conditioned at 21.7 ° C and 50% + 2% relative humidity

Zerostat is antistatic to remove static charge from the tester and / or fabric, and a tissue gun is available from Morgan Instruments, Inc., Cincinnati (never use a fabric softener to remove static charge).

Preparation of test specimens

The specimens should be placed in a room that allows maximum air circulation and equilibrium of humidity and temperature.

1. Cut out 8 specimens with the 25.4 mm knife. The specimen is cut longitudinally from the absorbent article in a rectangular shape without creasing. The size of the specimen is 2.54 x 14.0 cm / 35.56 cm. The specimens may be shorter, but must contain absorbent material throughout.

2. Remove the separation paper and weigh the specimen in mg. Round off the mass in mg to the nearest whole number.

3. Dust the panty fastener with a minimum of talc to avoid sticking. Blow out the Maraek talc from the specimen.

4. Weigh the calcined specimen strip in mg. Round off the mass in mg.

5. Calculate the base mass for each specimen from the measurement result with and without talc and the true area of the specimen.

6. Discard the specimen if its mass has increased by more than 2.0 mg / cm after talc.

Operation of the equipment

The wrinkle tester shall be placed on a work table in front of the person performing the measurement. It is important that the table is relatively vibration-free and that there is no airflow during measurement.

The person performing the measurement may sit or stand in front of the equipment while using the equipment. You should then select your position so that when you look in the mirror of the device, you see that the front reference line covers the back reference line. If you see only one line, you are in the right position to perform the measurement.

The investigator shall:

1. Removes the specimen slip bar from the specimen section at the top of the wrinkle tester platform.

2. Place the specimen strip on the specimen slot so that one end of the strip is exactly aligned with the vertical edge of the test apparatus.

3. Place the specimen slip bar on top of the specimen strip so that its leading edge is in line with the edge of the specimen in the test apparatus and touching the side rail. The specimen slide shall be carefully positioned to prevent the specimen from kneading or moving forward.

4. Pull the free end of the slide bar to move it forward at a constant speed of about 1 cm / second. As the sliding bar advances, the impactor shall move at the same low speed. When the sliding strip and the specimen strip move over the edge of the test apparatus, the specimen strip begins to bend or fall down. The movement of the sliding strip must be stopped at that moment. as soon as the leading edge of the test strip is aligned with the 41.5 ° reference lines.

If the test piece has a tendency to twist, the center of its first edge shall be taken into account. Specimens that twist more than 45 ° cannot be measured. Only specimens with a length of at least 0,5 cm greater than the bending length shall be measured. For non-measurable specimens, the bending length shall be measured only if a long strip at least 0,5 cm longer than the bending length can be made.

5. The bending length shall be noted at the top of the impactor (the length of the deflection from the start of the movement to the point where the impactor is inclined at 41.5 °).

6. The bend length shall be measured with a ruler and rounded to the nearest mm.

Calculation

According to the present invention, the flexibility / creasing can be expressed by the following equation:

G = WL ³ , where G is flexibility / crease, W is the sample weight (including talc) in mg / cm, and L is the bend length in cm. Results are expressed in mg x cm or gx cm dimensions.

thickness Measurement

The thickness should always be measured at the highest possible thickness, usually in the center of the absorbent article. Suitably, the measurement on the absorbent member includes the protective cover. The article shall be conditioned at 50% humidity and 23 ° C for 2 hours in its normal packaging and shall be removed no more than five minutes before weighing.

The thickness shall be measured with a micrometer having a measuring range of 0 to 30 mm plus a tolerance of minus 0,5 mm. The micrometer must not be spring loaded and must have a jaw that moves downwards under gravity. The micrometer jaws have a diameter of 40 mm and are loaded with a weight of 80 g. The measurement is made 5-10 seconds after it has been lowered for contact with the absorbent article. Measurements should be made with sufficient density to determine the mean thickness by statistical analysis plus-minus 0.1 mm sigma. A detailed description of the thickness measurement can be found in U.S. Patent No. 5,009,653.

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PATENT CLAIMS

Claims (10)

A flexible absorbent article for use in an undergarment, optionally comprising protective side tabs, a backsheet having an undergarment surface, and an absorbent core; wherein said undergarment surface comprises an adhesive for bonding said article to said undergarment, said adhesive having an actual adhesive surface and said adhesive defining a theoretical adhesive surface which is located within an infinite line of adhesive line without extending beyond the circumference of the underwear surface; said backsheet being a vapor-permeable and non-liquid but vapor-permeable layer, characterized in that - the ratio of said actual adhesive surface to said underwear surface is in the range of 0.2 to 0.8; - the ratio of said theoretical adhesive surface to said undergarment surface in the case of articles without said protective flaps in the range of 0.6 to 1.0, in the case of articles containing said protective flaps, It is in the range of 0.5-1.0 and the flexibility of said article is in the range of 1300 mg.cm to 5000 mg.cm according to the modified ASTM D1388 Test Method. 2. An absorbent article according to claim 1, wherein said flexibility is in the range of 2000 mg.cm to 3500 mg.cm. An absorbent article according to claim 1, wherein said flexibility is in the range of 2000 mg.cm to 3000 mg.cm. An absorbent article according to any one of the preceding claims, characterized in that the ratio of the theoretical adhesive surface to said undergarment surface for articles without said protective side tabs is in the range of 0.85 to 1.0 for articles containing said protective side tabs. the It is in the range 0.7-0.9. An absorbent article according to any one of the preceding claims, characterized in that said article has a maximum thickness along an axis perpendicular to said undergarment surface of less than 3 mm, preferably in the range of 0.5 to 1.5 mm. An absorbent article according to any one of the preceding claims, characterized in that said article is elastically stretchable in at least one direction parallel to said undergarment surface, preferably in two non-parallel directions, but both. »· • ·» • ···· An absorbent article according to any one of the preceding claims, wherein said backsheet comprises a water vapor permeable layer and at least one additional layer. The absorbent article of claim 7, wherein said further layer is a fibrous textile layer and said backsheet is arranged such that said underwear surface is formed by said fibrous textile layer. An absorbent article according to any one of the preceding claims, characterized in that said article is a panty liner. An absorbent article according to claim 7, wherein said water vapor permeable layer is a polymeric film having molecular size openings. .1 DISCLOSURE ' COPIES 1/2 63 '. 829 / BE