DE2439367C2 - Absorbent hygiene article - Google Patents

Description

(A) consists of a liquid-impermeable, hydrophobic, polymeric film, which after stretching has a permanent elongation of 15% or less by 30%,

(B) a multitude of protuberances arranged in the film, the height of which is 50 to 150 μm, and

(C) with a multitude of perforations lying in the protuberances with a central projected one

Diameter from 10 to 100 am, and that the second layer (25) is made of the barrier layer

a sermaterial coated on the surface of the fibers with a hydrophobic material with an air permeability of at least 30.5 dm ³ / min / dnr ^{at a pressure difference of 124.5 Pa!}

amounts to exists.

The invention relates to the absorbent hygiene article described in the claims. Such absorbent hygiene articles include, for example, disposable diapers, sanitary napkins, insert pads and bed pads intended for disposal.
Absorbent hygiene articles, such as diapers, are known to everyone. These hygiene articles are

used to absorb and retain body fluids. It is further known the exterior to cover this hygiene article with a flexible plastic layer, which is to prevent the absorbed liquid penetrates through the absorbent hygiene article and neighboring items of clothing or bed linen is dirty. The previously known, waterproof plastic layers prevent penetration of the liquid and help to store the liquid in the absorbent hygiene article. They run

But they also know that the absorbent hygiene article feels hot and is uncomfortable to wear, and can

even cause a rash or irritation. Furthermore, the known layers prevent the possible

Self-drying of the absorbent hygiene article, which is caused by the evaporation of the liquid contained therein

can be reached.

Gas-permeable barrier layers for absorbent hygiene articles belong to the known state of the art.

The purpose of these layers is to create a connection between the inside and the outside of the to produce absorbent hygiene articles and thereby enable circulation. For example, in US-PS 25 70 011 proposed the problem of a gas-permeable barrier layer for suction devices to be released with a diaper, soft an absorbent and a gas-permeable, water-repellent part having. The water repellent part is a chemically treated paper or cloth that is attached to the outside of the

(.5 diaper is folded and that, due to the chemical treatment, is intended to prevent urine from penetrating. Furthermore, in US-PS 31 56 242 an absorbent hygiene article is described which has an absorbent body contains, which is covered with a barrier layer made of a non-absorbent, flexible film of z. B. plasticized polyvinyl chloride is covered. The film is permeable to air and thus enables the drying below

! absorbent body. The air permeability of the film is achieved through micropores or holes or slits.
In US-PS 21 19 610 a combination is described, which consists of an inner removable, ₍ intended for disposal, absorbent pad and an outer, waterproof protective cover

' _k protective cover is made of a perforated layer of rubber or Japanese silk, and the padding s

* contains a perforated base made of cheap, moisture-proof material, such as cellulose glass, the

ϊ the protective cover is arranged adjacent.

In US-PS 34 39 678 baby pants are described which are intended to be worn over diapers. These Baby pants are made of a multi-layer * !, highly waterproof fabric. The tissue contains at least two Layers of z. B. Cotton, each of which is woven and permeable to air and steam and by former Treatment has been made waterproof.

From US-PS 20 27 810 a perforated web made of cellulose glass is known, which for the production of tea bags is suitable

From US-PS 32 92 619 a wound dressing is known which consists of an absorbent material and a on the surface close to the body applied film of thermoplastic material, this Has surface depressions and raised parts and in the sloping wall parts of the film between the raised parts openings are provided.

From US-PS 34 26 754 a wound plaster is known which consists of a microporous and breathable film of a polymer, this film having a lower apparent density than the polymer from which it was made and on one side at least partially with a pressure-sensitive η adhesive is coated.

From US-PS 34 46 208 a usable as a wound dressing laminate made of cotton gauze and a film made of polyethylene or polypropylene, which has 1 to 300 holes per cm ² , is known.

The invention is based on the object of an absorbent hygiene article with an absorbent body and a to provide a barrier layer which is easy to manufacture and which is well permeable to gases and vapors and to liquid chains is impermeable and which remains practically impermeable to liquids even when the absorbent Body is exposed to pressure

This object is achieved according to the invention in that the barrier layer of the hygiene article consists of two superimposed, hydrophobic, liquid-permeable layers (24, 25), of which the first layer (24) has a small proportion of voids in the total volume and of a liquid-impermeable, but with perforations (30) ) equipped film, the perforations (30) of which form an open area of 0.01 to 5.0%, based on the nominal area of the first layer (24), the mean projected diameter of the perforations being in the range between 10 and 300 μm and which has an air permeability of 3.0 to 60 dmVmin / dm ² at a pressure difference of 981 Pa, while the second layer (25) is a material formed from fibers that are hydrophobic or whose surfaces are coated with a hydrophobic material.

! riai with a Hohiraurnantei! of at least 60% of the total volume and an air permeability of

is at least 30.5 dmVmin / dm ² at a pressure difference of 124.5 Pa

i The absorbent hygiene article according to the invention is particularly advantageous if the in an absorbent body

: the liquid contained is shielded from neighboring items of clothing, forming a cooler cover and

When wearing it, the absorbent body should be allowed to dry.

i The invention is illustrated below with the aid of the drawings of some preferred exemplary embodiments

j described. In the figures, the thickness of some materials is greatly enlarged for better representation

L drawn.

Γ Fig. 1 shows the perspective view of a preferred embodiment of the present invention

1 viewed disposable diaper in the unfolded state, in which some layers are partially cut away.

IF i g. Ί shows the perspective view of a greatly enlarged part of the barrier layer of the one shown in FIG

! Disposable diaper.

', F i κ. 3 shows the perspective view of an embodiment of the device for perforating a moist

Resistant, band-shaped material.

Although the invention has been described in terms of a disposable diaper, it should be understood that it does not apply to these

j embodiment is limited.

I The in F i g. 1, the disposable diaper 21 shown as a preferred embodiment of the present invention is off

j the usual multitude of layers made from different materials. The shown disposable diaper

i contains a cover layer 22, an absorbent body 23 and a barrier layer, which consists of a first layer 24 and

C is a second layer 25.

j · The absorbent body 23 rests on the barrier layer and the cover layer 22 on the absorbent body 23. Preferably is

j the cover layer 22 in the longitudinal direction longer than the absorbent body 23, so that it is around and under the in the longitudinal direction lying ends of the suction body can be folded, as shown in FIG. Next are the [Absorbent body 23 and the cover layer 22 usually in the area of the parallel to the lateral edges and / or

I longitudinal ends on the barrier layer, which in the embodiment according to FIG. 1 is formed by the first layer 24,

0 attached. It is of course also possible to place the absorbent body and the cover layer on the entire contact

i · 'surface to attach to the barrier layer.

i; _; Any of the already known cover layers can be used as the cover layer 22, for example

% the top layer described in US Reissue PS 26 151, which consists of rayon coated with a thermal

ϊ r thermoplastic binder is bound to a hydrophobic, web-shaped tangled fiber material.

j: ¹ The absorbent body 23 can also be made from any of the materials well known to any person skilled in the art

tj, which have good moisture absorbing properties. Various examples of such

i | Absorbent materials are described in the latter patent, for example multiple layers of

creped tissue paper, cotton wool, cellulose sanding, air felt, absorbent, natural sponge and synthetic, foamed, absorbent materials.

The barrier layer formed in accordance with the present invention includes a first layer 24 and a second layer 25. In the embodiment shown, the first layer 24 consists of a perforated one. hydrophobic, band-shaped material made of polyethylene and the second layer 25 made of a hydrophobic, porous, creped tissue paper. Each of these layers is in itself permeable to liquids. In contrast, the layers stacked on top of one another form a layer impermeable to liquids. Although in the case of FIG. 1 shown Embodiment the first layer 24 is arranged on the outside of the second layer 25, the second Layer 25 can be arranged on the outside of the first layer 24.

The first layer 24 usually consists of a flexible, liquid-impermeable, sheet material, which has been perforated so that it becomes permeable for liquids. In the embodiment described, polyethylene was used for the first layer. It goes without saying, however, that this situation also results from other things Material can be made. In a preferred embodiment, the first layer 24 consists of one Polyethylene sheet with a thickness of 36 μm. The web material is perforated, as will be described below.

Furthermore, the first layer 24 has only a small proportion of cavities, as will also be described in detail below. The volume of voids created by the perforation in the first Layer practically corresponds to the percentage of the area opened by the perforation of the layer that is on the The basis of the projected perforation diameter is calculated, as will be described below.

According to the invention, the area of the first layer opened up by the perforation is in a range from 0.01 to 5.0% of the nominal area of the imperforate sheet material, preferably 0.01 to 2.0% and most preferably between 0.01 and 1.0%. The mean, projected diameter of the perforations is expediently 10 to 300 μm, preferably 10 to 200 μm and in the most preferred embodiment 10 to 100 μm. The second layer 25 of the described embodiment consists of a creped tissue paper; H. the end a fibrous web material with a high proportion of voids in the volume, which material passes through Impregnation with a paraffin wax is made hydrophobic, as is to be described below. the The porosity of the second layer 25 is still very high even after the impregnation part with the paraffin wax.

In the case of the in FIG. 1 is the circumference of the first lap. 24 larger than that of the absorbent body 23 and forms edges 26 and 27 running in the longitudinal direction and in the transverse direction. The lateral edges 27 are folded onto the top of the absorbent body 23 and form so-called "side flaps". These side flaps can be attached to the cover layer 22. Furthermore, before the diaper 21 is put on a child, the edges 26 lying in the longitudinal direction of the diaper are folded around and onto the upper side of the absorbent body 23 will. The overfolding of the side edges and the edges lying in the longitudinal direction can be advantageous because as a result, the absorbent body 23 is enclosed in a container formed by the first layer 24.

In the case of the in FIG. 1, practically the entire first layer 24 is perforated. It is also possible to limit the perforation to the "effective, gas-permeable part" of the barrier layer. The effective gas-permeable part is considered to be that part in which the first layer 24 and the second layer 25 cooperate in order to prevent the passage of liquid and allow the passage of gases. at In the embodiment shown in Fig. 1, the entire area of the barrier layer can act as a more efficient gas-permeable siger part of the diaper because the two layers work together over this entire area. If, on the other hand, the second layer covers the entire rear side of the diaper, but only a circular part with a diameter of 50.8 mm, which is arranged in the geometric center of the first layer 24, is perforated, then the effective, gas-permeable part is also limited to this perforated part because this is the only part of the first layer 24 which cooperates with the second layer in the intended manner.

The lateral edges 27 and 26 of the first layer 24 lying in the longitudinal direction can, like it is shown in Fig. 1 may be perforated, although that does not affect the gas permeability of the backing layer Has influence.

The in F i g. The diaper 21 shown in Figure 1 can be attached to a child by any of the fastening means known to those skilled in the art, such as a diaper needle. Another fastener found in is used to an increasing extent, is made from contact adhesive tape. A corresponding embodiment is described in US Reissue PS 26,151, which has already been mentioned. This fastening device Λη are not shown in the figures

F i g. Fig. 2 shows a greatly enlarged part of the first layer 24 with those in the above-mentioned polyethylene web arranged, typical protuberances 29 in which perforations 30 are arranged.

The device shown in FIG. 3 can advantageously be used to produce the protuberances and perforations. The device contains two steel rollers, a pressure roller 31 and the perforating roller 32, which are arranged in frames and bearings (not shown) and form a nip. The roller bearings can with the help of compressed air cylinders whose working pressure is known to anyone skilled in the art Pressure control valve is adjustable, moved and thereby the width of the nip 36 can be changed. at In a practically used device, the perforating roller 32 is wrapped in a spiral shape with a carding cover 33. The carding cover 33 contains four layers of cotton fabric which are impregnated with an adhesive made on the basis of rubber. The tape-shaped card cover is 3.17 mm thick and 39.7 mm wide. In the card cover pins or mandrels 34 are used, which are perpendicular to the plane formed by the tape and form a uniform, straight pattern with 82 mandrels per cm ^{2 of} surface. the

es mandrels 34 are made of tempered carbon steel with a tensile modulus of 1792 to 1999 MPa and have a round cross-section with a diameter of 228 am. The ends of the mandrels extend 3.17 mm above the surface of the belt so that the total thickness of the card cover is 6.35 mm. The perforating roller 32 wound with the carding cover has a diameter of 76.2 mm and a

Lung of more than 482 mm and is propelled in the direction indicated by the arrow in FIG. 3.

The pressure roller 31 is surrounded by a tubular felt sleeve 35 made of needled felt. The fibers used for this felt consist of a small proportion of polyester and a larger proportion of polyamide staple fibers with great tenacity, a fineness in the range from 0.167 to 0.667 tex and a length of 25.4 to 50.8 mm. The thickness of the felt sleeve 35 measured in the radial direction is 6.35 mm, the inner diameter is 76.2 mm and the weight of the felt sleeve is 87 g per 9.3 dm ^{2 of} the inner surface. The diameter of the pressure roller 31 with the felt sleeve 35 drawn on is 88.9 mm. The pressure roller 31 is driven ni,> * it.

A tape 28 made of the polyethylene film described above, the surface area of which ^{corresponded to about 31.8 m 2} per kg of weight, was passed through the nip 36, the pressure effective in the nip being about 16.67 N per linear mm and the pushing about 67 meters per minute.

The height of the protuberances 29 formed in the aforementioned band in the manner described above the surface area of the tape ranged between about 50 to 150 µm. A preferred height is around 150 μπι, which corresponds to about three times the thickness of the imperforate tape and thus an unloaded thickness the first layer 24 can be achieved, which corresponds approximately to four times the thickness of the imperforate tape 28.

The perforations 30 have a theoretical diameter of about 228 µm, which is the size of the Corresponds to the mandrels in the card cover. The expression of the perforation is used here for the mean value of the through the straight line running through the center of the perforation is used. The projected diameter of the perforation, that is the diameter of the perforation 30 after the projection onto the plane determined in front of the band 28 smaller than 228 μm, because the perforations are generally arranged in the side surfaces of the protuberances 29 and therefore include an angle with the plane defined by the tape. Also pulls the diameter of the perforations due to the elasticity of the film together as soon as the mandrels 34 of the carding cover withdrawn from the perforations.

The perforated polyethylene film had the following properties, the method of measurement thereof below to be discribed.

Perforation diameter 0.1 mm

Air permeability 23.4 dmVmin / dm ² at a pressure difference of 981 Pa

internal tensile strength according to TAPPI T414 M-49 MD-36

(Values for 4 layers or 4-fold material) CD-46

Ball drop test 39.4 cm

mean projected diameter of the perforation 55 μm

Percentage of perforated protuberances 8%
Elasticity measured as the remaining elongation after

a) 30% elongation MD-3.3%

CD-4.5%

b) 55% elongation MD-10.5%

CD-10.0%
Tensile stress at

a) 30% elongation MD-29 g / mm width

CD-20.8 / mm width

b) 55% elongation MD-34.6 g / mm width

CD-22.5 g / mm width

c) when torn MD-43.5 g / mm width

CD-25.2 g / mm width
(projected) open area 0.014%

MD = machine direction

DC = across the machine direction.

After being stretched by 30%, the first layer 24 should have a permanent deformation of at most 15% and a permeability to air of 3.0 to 60 dm ³ / min / dm ² at a pressure difference of 981 Pa.

In the embodiment described, a creped, moisture-proof, white one was used as the second layer 25 Tissue paper is used, which is made hydrophobic by treating the fiber surface with paraffin wax was made. The tissue paper treated with the wax retained a high porosity.

The tissue paper was made from bleached, chemically processed wood pulp, which contained 30% bleached sulphite pulp made from aspen species and 70% bleached for the manufacture of kraft paper suitable wood pulp made from northern spruce and pine species. The pulp was cleaned and then treated with a moisture-proof resin until the solids content of the resin is 42% to 1% of the weight of the dry fibers. This wood pulp was made on a paper machine with those known in the industry Devices made into rolls of white creped tissue paper. The percentage crepe which by the relationship: (machine speed - roll winding speed): machine speed determined was 14%.

The tissue paper made in the manner described was then subjected to a known dry waxing process subjected. In this process, paraffin wax is used, the purity of which is the same as for food Regulations and which has a melting point of about 77.8 ° C, against a surface of the with a speed of about 286 m per minute rapidly moving tissue paper web. This will be

a relatively slowly rotating heated platen is used, the speed of which is about 5% the belt speed and which is partially immersed in a bath of the melted paraffin wax. So that the wax stripped from the surface of the applicator roller onto the tissue paper covers the surface of all fibers The band coated with the wax is wetted until all the fibers are coated over additional heating rollers and then rolled up at a temperature above the melting point of the wax. In this dry waxing process, the surface of the fibers inside the tissue paper is waxed overdrawn. The amount of wax used is limited so that only the smallest voids between the fibers become clogged and only a relatively small reduction in the air permeability of the tissue paper entry.

A second layer 25 produced in the manner described had the following before and after its formation physical properties, the measurement method of which will be described later.

reason Thickness*) Tensile strength in Tensile strength in Air permeable 1 C weight (mm) dry condition Damp condition speed with one I J (g / m ² ) (N / mm width) (N / mm width) Pressure difference of 124.5 Pa MD CD MD CD (dm ³ / min / dm ² ) 20 üMgcwacfist 395 0, i27 0.254 0.093 Ö, Ö29 306 waxed 483 0.127 0.278 0.095 0.073 0.031 274

*) measured at a pressure of 1.215 kPa.

MD = machine direction. CD = across the machine direction.

The wax-treated tissue paper product described above had a void fraction of the total volume of 88%. The type of calculation used to determine the void volume is described below. The void volume of the second layer 25 should be at least 60% of the total volume. The layer used with the high proportion of void volume should have a permeability for air which, with a pressure difference corresponding to 124.5 Pa, is at least 30 dmVmin / dm ² . Another type of process was used to make the tissue paper product hydrophobic. In this other procedure, paraffin wax was dissolved in a chloroethylene solvent, the solution having about 5% by volume of paraffin wax. The tissue paper product was passed through this paraffin solution and carefully wetted in the process. The wetted tissue paper product was then dried by evaporating the solvent.

The second layer 25 can also be produced by only the bottom surface of a large Hohlraumar.tei! having absorbent body with one of the above-mentioned, for example, hydrophobic Materials is treated so that only the bottom layer of the absorbent body is down to a several fiber lengths corresponding depth becomes hydrophobic.

In order to determine the impermeability to liquids and the permeability to gases of the barrier layer, the test cushion layers described in the following examples were prepared. All test cushion layers had approximately the same dimensions; they were square with a side length of about 10 cm and had several layers. The first four layers of each cushion layer were similar and were in the following order. The first layer, which corresponded to the cover layer 22 of the diaper, was a random fiber fleece with a basis weight of 23.9 g / m ² . The second layer consisted of creped, moisture-proof bleached kraft paper with a basis weight of 19.9 g / m ² . The third layer consisted of cellulose flakes or, as they are sometimes also called, air mushrooms, which were made of bleached material obtained from soft wood and suitable for Kraft paper. This third layer had a fundamental

weight of 168 g / m ² . The fourth layer consisted of creped, bleached Kraft paper with a basis weight of 19.9 g / m ² . The layers 2, 3 and 4 corresponded to the absorbent body 23 in FIG. 1 shown diaper. The different cushion layers used for the test only had different barrier layers, which are described in the individual examples.
The padding layers used for the test were wetted with a test liquid which was intended to simulate urine and which consisted of a 1% strength aqueous NaCl solution, the surface tension of which was reduced to 0.045 Nm " ¹ by adding a surfactant. Each padding layer was wetted with the test liquid, the degree of wetting being about 5 g of liquid per 1 g of absorbent body, ie per gram of the combined weight of layers 2, 3 and 4. This degree of wetting is referred to below as "wetted up to 5x"

The liquid impermeability of the barrier layer was determined by a method to be described below Moisture penetration test determined. The gas permeability of the barrier layer was also increased by a Determines the evaporation test to be described.

Moisture penetration test. Two layers of filter paper were weighed to determine the dry weight of the filter paper to determine. The barrier layer of a wetted cushioning layer was in contact with the filter paper brought. The moistened padding layer was then applied with the aid of a 5 cm diameter Pressure star feed, the one in the middle of the outer surface of the Polslerschicht opposite the barrier layer acted, exerted a pressure of 3.45 or 6.9 kPa for 15 minutes Filter paper weighed again to determine its weight when moistened. The amount of from

Liquid absorbed by the filter paper was then determined by subtracting the weight of the dry filter paper from the weight of the wet filter paper. In order to obtain a measure of the liquid permeability of the barrier layer, the amount of liquid per unit area which had penetrated through the barrier layer under pressure was then determined. To do this, the amount of liquid leaked through the barrier layer was divided by the area under pressure, ie 19.7 cm ² .

Evaporation test. The cushion layers were wetted up to about 5 times and with a non-perforated one Polyethylene film "covered". For this purpose, the film was placed over the top layer of the cushioning layer and lightly beaten around their edges. The parts of the film turned around the edges were mixed with commercially available Polyester tape attached to the back layer.

The free rear surface, ie not covered by the film, was practically square with a side length of about 9 cm. The covered, wetted cushion layer was then weighed to provide a first layer weight. The cushioning sheet was then placed face up on a laboratory bench to expose the uncovered barrier to ambient room conditions, which were about 22-23.8 ° C and 60% relative humidity. The polder layer was exposed to these conditions for about 3 hours and then weighed again to obtain a second layer weight. The weight loss achieved through evaporation was determined by subtracting the second layer weight from the first * layer weight. The evaporation loss was converted into an evaporation rate by dividing the weight loss by the treatment time and the free area of the barrier layer. This factor then wyrrj.j converted to a crn in grams per! OQQ ² per hour ausdrückbarc Vcrdarnpfungsgeschwindigkeit specify.

Examples I-IV

For the production of test cushion layers, the four first layers described above were applied to a single one Position of the perforated polyethylene film web also described above. The polyethylene film lay there r in the layer 4, and the protuberances 29 were directed against the interior of the cushioning layer. The upholstery layer was then moistened with the test liquid up to about 5 times. The subsequently executed moisture permeability and evaporation tests gave the results given in Table 1 below.

Examples V-VlH

To produce further test cushion layers, the four first layers described above were applied to a single one Layer of the tissue paper product also described above, treated with paraffin wax, so that the tissue paper product treated with wax was in contact with layer 4 of the cushioning layer. The upholstery layer was moistened with the test liquid up to about 5 times. The results of the Moisture permeability and evaporation tests are given in Table 1 below.

Example IX-XII

Test cushioning layers were produced which contained the four first layers described above and a barrier layer formed from a sheet of the paraffin wax treated tissue paper product described above and a layer of the perforated polyethylene film also described above. Included the tissue paper product treated with wax was in contact with layer 4 of the cushioning layer, as shown in FIG. 1 for the Layer 25 of diaper 21 is shown. The perforated polyethylene film was on the wax-treated tissue paper product on, corresponding to the outer layer 24 of the FIG. 1 shown diaper 21, with the protuberances were directed against the cushion layer. The upholstery layers were up to about 5x with the test liquid moisturizes. Thereafter, the moisture permeability and evaporation tests were carried out; the Results are shown in Table 1 below.

Example XIII

A test cushion layer was produced which only had the four first layers described above, but none Had barrier layer. The test cushion layer was moistened up to about 5 times. After that, the moisture permeability and performed the evaporation test; the results are in Table 1 below listed.

Example XTV and XV

Test pad layers similar to those for Examples IX-XII were made with the The difference is that instead of the tissue paper product treated with wax, one treated with silicon dioxide Tissue paper product with a large proportion of voids in the total volume was used. The tissue paper product treated with the silica was creped as described above and immersed in a suspension of 10% by volume silicon dioxide coated in 1,1,1-trichloroethane been.

In doing so, about 0.05 g of dry substance was absorbed per 10 × 10 cm of the tissue paper surface. the Test cushion layers were moistened with the test liquid up to about 6 times. The results of after that The moisture permeability and evaporation tests performed are shown in Table 1 below

Examples XVI and XVU

Test cushion layers similar to those for Examples IX-XFV were made with the The difference is that instead of the tissue paper product treated with wax, a win fiber product is used large void fraction was used. This tangled nonwoven fabric consisted of meltblown polypropylene that had been processed into a sheet-like material. This tangled nonwoven fabric was one with a Card cover perforated polyethylene film arranged adjacent. The Winfiber product pointed for water a contact angle of 100 °, a thickness of 0.33 mm measured at a measuring pressure of 0.76 kPa, es had a permeability for air of 320 dnrVmin / dnr at a pressure difference corresponding to 124.5 pa and a basis weight of 30 g per nr, corresponding to a volume fraction of the voids of 88.9%. The test cushion layers were moistened up to about 6 times with the test liquid. The results of the test subsequently carried out for moisture permeability and evaporation are listed in Table 1 below

Examples XVIII and XIX

Test cushioning layers were produced which were similar to those of Examples IX-XII, with the difference that the foils provided with conical protuberances were replaced by a polyethylene foil which had been perforated according to the porulation process. In this process, practically cylindrical pores with a slightly protruding edge are produced. The film had a measured thickness of 46 μm, a weight corresponding to 64 mm / g, a number of pores of 309 / m ² and a pore diameter of 178 μm. The test upholstery sheets were moistened up to about 6 times with the early liquid. The results of the tests subsequently carried out for moisture permeability and evaporation are listed in Table 1 below

Examples XX and XXI

Test cushioning layers were produced which were similar to those of Examples I-IV, with the difference that the perforated film provided with conical protuberances was replaced by a perforated polyethylene film as used for the test cushioning layers according to Examples XVm and XDC above had been. The test cushion layers were moistened with the test liquid up to about 6 times The results of the tests carried out afterwards for moisture permeability and evaporation are shown in listed in Table 1 below

Table 1 Example barrier layer

Fluid permeability

(g / 15 min)

Test pressure

3.45 fcPa 6.9 kPa

Evaporation Rate (g / 1000crrrVh)

II III IV

VI

VII

VIII

IX

Xl

ΧΠ

XHI

XVI XVII

perforated polyethylene sheet

waxed tissue paper product

waxed tissue paper product and perforated polyethylene sheet

no

silicon dioxide treated tissue paper product and perforated polyethylene sheet

Random fiber fleece and perforated polyethylene sheet

0.97

0.44

0.03

0.70

1.37

0.02

0.00

0.03

6.3

5.1

12.3 12.5

5.6 5.1

16.6 5.26

3.2

continuation

example Barrier Fluid through 6.9 kPa Evaporation nonchalance 0.07 swiftly (g / 15 min) speed (g / 1000 cmVh) Test print 3.37 3.45 kPa xvm Γ
XIXj Polyethylene sheet with cylindrical xx | Perforations and waxed 45 XXI I Tissue paper product Polyethylene sheet with cylindrical - - Perforations _ 4.8

As can be seen from the test results shown in Table 1, both the perforated polyethylene film and the wax-treated tissue paper product alone are not impermeable to liquids. The combined material formed by the pier product is practically impermeable to liquids. From the table is It can also be seen that a combination of a perforated polyethylene film and a tissue paper product treated with wax is gas-permeable

The results of Examples XTV and XVII further show that a layer made of a hydrophobic material with high voids in volume in contrast to the wax-treated tissue paper product in a barrier layer can be used to form an effective liquid impervious and gas permeable layer.

It is understood by anyone skilled in the art that other porous, hydrophobic materials with a high Void fraction in volume can be used. It is also possible to use hydrophilic materials Treatment with various means, for example with fatty acids and their salts, vege tab ile waxes, To make silicones, fluoro-organic resins and olefin resins hydrophobic and, if they have a high proportion of voids in the total volume, to use them for the products according to the present invention.

Torous, hydrophilic materials with a relatively large proportion of voids in the volume are for example natural and artificial foams and sponges with open cells, winfiber products and woven textiles, as well as a wide range of paper products. Such materials can be made directly from Open cell foams are made and made from fiber materials soft from originally hydrophobic polymers such as the aforementioned organofluorine and olefin resins became.

Although olefin films, particularly those made of polyethylene, are preferred for the web material used in the present invention because they are readily available and inexpensive, many others can also be used Materials including the polymers of vinyl chloride, polyvinyl chloride, propylene and butylene can be used. To look for the most effective combination in terms of strength and fluid rejection It is also possible to achieve perforation. Foils made from different plastic material to one Laying together or provided with hydrophobic coatings, which with such materials can be generated as they were described for the products with the high proportion of voids in volume.

The most important of the above-mentioned measuring methods are described below.

The height of the protuberances produced during perforation was measured optically with the aid of a microscope which had a fine adjustment screw with a micron scale. In doing so, the microscope was on first the plane of the upper surface of the film is in focus at the base line of the protuberance and the corresponding scale value is read off the adjusting screw. Then the adjusting screw was turned until the microscope was sharply focused on the tip of the protuberance and the corresponding scale value again read. The difference between the two readings then gave the height of the protuberance in microns.

The internal tensile strength was determined according to T414M-49 of TAPPI (Technical Association of the Pulp and Paper Industry).

The ball impact strength was measured similarly to ASTM D1709, with the The difference is that instead of the arrow, a steel ball with a diameter of 19.05 mm and a weight of 28.16 g was used. The ring for fastening the film had a diameter of 76.2 mm. the acting force was changed by adjusting the height of fall of the ball. The amount at which 50% of the Impacts caused an open tear in the film was noted.

To measure the elasticity, a tensile strength testing device suitable for tension measurements was used, which is also useful for testing according to ASTM Standard D-882-67.

The test pieces used had a width of 25.4 mm and a length of 50.8 mm. The crosshead speed of the tester was 508 mm per minute in stretching and retracting. the Test pieces were stretched by 30% or 55% and then the tensile force was reduced again to zero. the permanent elongation of the specimens remaining after stretching was recorded as a percentage of the original lung.

The projected diameter of the perforation was measured by taking a sample of the perforated sheet

1 sheet of drawings

materials was placed under a microscope, which had an eyepiece with calibrated grating.

The permeability of a perforated film for an air flow was measured with the aid of an airtight chamber on which a sample holder was attached, which had a practically circular opening with an opening area of 10 cm ² . The chamber was connected to a source of air via a flow regulator with a measuring range of 0 to 68.6 kPA overpressure, and an air flow meter with a measuring range of 0-6.5 dm ³ per minute was installed between the flow regulator and the chamber. Further, a water manometer was connected at one end to the chamber and the other end to the free atmosphere to measure the pressure difference between the chamber and the atmosphere.

For this measurement, a sample with a width of 44.5 mm was cut from the perforated web material and fastened over the opening in the sample holder, with the protuberances facing away from the chamber. The air source was then turned on and a manometer readable pressure drop (AP) across the specimen was recorded. The air flow through the flowmeter was recorded and used to calculate the volume: air volume per time period per effective area of the specimen

The permeability of tissue paper products to air flow was measured in accordance with ASTM IS D-737-69 in dnrVmin / dm ² at a pressure difference of 124.5 Pa.

To calculate the voids in a silk pear product, it was assumed that the weight of the 278.7 m ² unwaxed tissue paper product was 5.62 kg and the weight of the waxed tissue paper product of the same size was 6.98 kg. The thickness of the tissue paper was 0.127 mm at a measuring pressure of 1 JL 15 kPa. The total volume of the 278.7 m ² product was d & nn at

■ 20 the specified measuring pressure: ■

■ Area X thickness = 2.78 - 10 ^{6 cm 2} X 1.27 ■ 10 " ² cm = 3.54 · 10 ^{4 cm 2} !

Of this, the volume of cellulose accounts for:
25th

Cellulose weight 5.62-10 * _, _fi r _lf) 3 3

Cellulose density (literature value) 1.54 g / cm ^{3 'Cm}

and the volume of the wax:

Wax weight ₌ (6.98-5.62) x 10 ^ g _{= tf} ,

Growth rate (literature value) 0.8 g / cm ³

The total solid volume is then calculated from the cellulose volume plus the wax volume

■ 35 5.35 · 10 ³ cm ³ and the percentage of the void according to the formula: I.

(Total volume - solid volume) "_ (35.4-5.35) · 10 ^{3 cm 3} _{v fnr} . _ _s ", ■

- 7; λ IUW j Λ IUW - OJA.

Total volume 35.4 cm

To calculate the void in a perforated polyethylene film, it was previously shown that the Polyethylene film a calculable from the weight of the surface area and the optically measured thickness Has density that corresponds quite well with the density measured by liquid displacement This means that the polyethylene film has practically all properties at least for the purpose of interest here of a material without voids.

If such a film is perforated ^{with a card cover which has 82 pins / cm 2} with a diameter of 0.228 mm each, with perfect holes being punched out, the proportion of voids caused by the perforations is proportional to the cross-sectional area of the holes.
This results in the following for the cavity created by perforation:

Area of the holes ₌ 82> r / 4 (2.28 IQ ' ² cm) ² _{= 3 35%}

Surface of the slide learn ² "'

Because of its elasticity, the film contracts after perforation, with the diameter of the perforations is decreased. Therefore, the cavity created by the perforation is actually less than was found by the above calculation, so that a perforated in the manner described above polyethylene film has only a relatively small proportion of voids.

Claims (6)

Patent claims: 1. Absorbent hygiene article, which is intended to be moved away after use and an absorbent body and a liquid impervious, gas permeable barrier layer under the absorbent body, thereby s characterized in that the barrier layer consists of two superimposed, hydrophobic, liquid-permeable Layers (24, 25) consists of which the first layer (24) has a small proportion of voids in the Has total volume and from a liquid-impermeable, but equipped with perforations (30) Foil consists, the perforations (30) an open area of 0.01 to 5.0%, based on the nominal area of the first layer (24), being the mean projected diameter of the perforations in the range between 10 to 300 do Üegt, and which has an air permeability of 3.0 to 60 dm ³ / mJn / dm ² at a pressure difference of 981 Pa, while the second layer (25) consists of fibers that are hydrophobic or their Surfaces are coated with a hydrophobic material, formed material with a void fraction of at least 60% of the total volume and an air permeability of at least 30.5 dm ³ / min / dnr at a pressure difference of 124.5 Pa 2. Hygiene article according to claim 1, characterized in that the mean projected diameter of the Perforations (30) of the first layer (24) of the barrier layer in the range between 10 and 200 μΐη and the The open area of the first layer (24) formed by the perforations in the area which is effective for the passage of gas Range 0.01 to 2.0% of the nominal area of the first layer (24) 3. Hygiene article according to claim 1, characterized in that the mean projected diameter of the Perforations (30) of the first layer (24) of the barrier layer in the range between 10 and 100 μΐη and the open area formed by the perforations in the first layer (24) in the area effective for the passage of gas Range 0.01 to 1.0% of the nominal area of the first layer (24) 4. Hygiene article according to claim I, characterized in that the second layer (25) of the barrier layer tape-like material made up of fibers or a creped tissue paper product and which Surfaces of the fibers of this tissue paper product coated with a hydrophobic material are. 5. Hygiene items! according to claim 1, characterized in that the second layer (25) of the barrier layer is flexible, polymeric, foamed material with open cells 6. Hygiene article according to claim 1, characterized in that the second layer (25) of the barrier layer is arranged between the first layer (24) of the barrier layer and the absorbent body and that the first layer (24) the outer layer