NO854814L - COVER OR COATING DISPOSAL FOR SURRENDER USE OF THE SURGERY AND PROCEDURE FOR ITS MANUFACTURING. - Google Patents

Description

The invention relates to a covering or dressing cloth for single use for surgery and which consists of a water vapour-permeable, drapeable carrier fleece fabric and a polymer cover foil which does not penetrate this.

Such disposable cloths are increasingly used in surgery,

as single use ensures absolute hygiene and could thus clearly lower the postoperative infection rate in patients compared to washed, reusable OP tissue cloths made of cotton.

The area of application according to the invention therefore lies on the one hand in protective clothing for the persons participating in the operative intervention, on the other in covering the patient in the peripheral area not immediately connected to the incision site (surgical wound). For both application areas, the following requirements are essentially placed on a disposable cloth: High water vapor permeability with high water absorption capacity (breathing activity, water balance),

Water tightness according to DIN 53 886-77 in the order of

at least 2 . 10 ~* Pa,

Lint (waste) freedom or high wear resistance and

very high drapeability (ie textile "fall") as well as sufficient mechanical strength to withstand the forces of confection and practical use. Lint-free refers to the property of a textile material when used not to

give off some particles such as fiber fragments or fiber dust or to release such. Such suspended particles released in the air of the operating room can act as germ carriers and thus lead to postoperative wound infection. In particular, ordinary cotton fabrics that can be used again tend more and more to lint with increasing number of washes.

A disposable surgical drape fulfills its essential function as a barrier against bacteria. prevents infection the more perfectly, the smaller its degree of lint and the denser it is

above water, alcohol and physiological fluids.

The known composite materials of foil/flour fabric or foil/tissue paper or tissue/foil/flour fabric is indeed absolutely airtight and waterproof, and thus also absolutely germ-proof, but has the major disadvantage that they are paper-like, stiff, non-textile and difficult to drape, have a rattling grip and lead to heat stiffening in patients, especially in longer continuous operation.

Water jets of extremely high pressure are also known

needle-punched composite fabrics of polyester fibers and a tissue layer. These so-called~"spunlaced" products do not have the above disadvantages. Due to the binder-free finish, they can combine good bacteria barrier function with high textileity and drapeability, however, have the major disadvantage of clearly higher lint rates than with wet pile fabrics, which is especially true for the relatively open-structured polyester side. This is essentially due to the fact that the cellulose fibrids used have little self-bonding with each other and are too short for sufficient fiber entanglement.

The task of the invention is to provide a surgical cover-cloth made of non-woven fabric for single use which meets the aforementioned requirements, overcomes the above-mentioned disadvantages of known fabrics and is also suitable for OP clothing. Furthermore, a method for producing such a cloth must be provided.

As a solution, a disposable cover or upholstery fabric is proposed which has a carrier fiber fabric layer and a polymeric cover layer

which does not penetrate this and has the features in the characterizing part of claim 1. The production according to the invention proceeds in such a way that with the help of the "Crushed Foam" technique, an aqueous polymer foam dispersion is applied with the help of squeegees and/or rollers, which consists of polyacrylic ester, polyvinyl acetate acrylate or nitrile butadiene and is low in emulsifiers,

in that its foam weight is less than 0.2 g/cm<3> and its application weight 15-50 g/m<3> and the foam contains respectively referred

to the total weight

1-15% hydrophobic agent

3-15% of a foam stabilizer, consisting of an ammonium or alkylammonium salt of a long-chain fatty acid with a carbon number between 14 and 20

and at least 0.25% methyl or methyl hydroxyalkyl cellulose as a thickener.

The principle of the "Crushed Foam" coating method based on aqueous polyacrylic acid ester dispersions is in and of itself a chain: You mix the polymeric, disperse ironing paste binder dispersion, the foam stabilizer, the thickening agent and any foaming aid and fillers, foam it all up and apply the foam by using a squeegee and/or rollers on the textile base material. It is then dried slowly because the foam layer is pressed between cold or heated rollers.

The above method has so far not proved suitable

for the production of highly waterproof single-use OP cotton fabric. Due to the open structure of the fluorspar base materials

as well as the foam film, the product's waterproofness is insufficient even when it is subsequently hydrophobicized. Even the addition of a hydrophobing agent to the ironing paste to be washed up does not lead to usable OP substances,

as this drastically reduces the stability of the foam and this, as a consequence, undesirably penetrates into the carrier material. Furthermore, those mentioned as aqueous dispersions are foamable polymers. However, only according to the invention the complete mixture composition of the disperse ironing paste surprisingly led to the possibility of preparing the foam with the hydrophobing agent necessary for the OP application without reducing the stability of the foam or the foam penetrates

in the carrier material.

The viscosities of the unfoamed mixture measured according to Brookfield (DIN 53 019 for rotational viscometers) range between 0.8 and 6 Pa s. Viscosities from 1-2 Pa s have been found to be advantageous.

To achieve a high water tightness with the least possible foam application and a high drapeability, it is necessary to work with a very low foam weight of less than 200 g/l. This results in an extreme foam viscosity or foam stiffness that reliably prevents penetration of the coating during the foam application and the subsequent drying process.

In those cases where the "binder dispersions are poorly foamable or only give a coarse-pored foam, it is necessary to add a smaller amount (1% by weight) of a foaming aid. However, this process step is common to those skilled in the art and is not covered by the invention.

Due to the properties of the foam layer alone, the product is sufficiently waterproof ('at least 2.10~<5>Pa according to DIN 53 886-77) without the carrier pile fabric having to be additionally hydrophobicised. The hydrophobicity of the layer material can therefore be sufficiently adjusted by the amount of "Crushed Foam" foil alone for most purposes, as the foil's basis weight of 15 g/m<2> for hydrophobically finished and of 50 g/m<2> non-hydrophobic carrier pile materials form appropriate boundaries.

Larger quantities would reduce the fabric's drapeability too much.

According to the invention, 1-15% by weight (content respectively referred to the foam weight) of hydrophobing agents is added to the foamable ironing paste, with 2-15% by weight of a water-insoluble but dispersible ammonium or alkylammonium salt of a long-chain (C- ^-C^q ) fatty acid and at least 0.25% by weight of a high molecular methyl or methylhydroxyalkyl cellulose must be added as a foam stabilizer or thickener. Among the salts of a long-chain fatty acid, ammonium-

stearate proved to be particularly advantageous in its action.

Due to the fact that the surfactant effect of thickeners increases with the number of methyl groups, medium to highly etherified methyl or methyl hydroxyalkyl celluloses are particularly suitable. Carboxymethylcelluloses, starch, alginates, polyacrylates and other natural, semi- or fully synthetic thickeners cannot be used.

As a preferred hydrophobic agent for the ironing paste

according to the invention, it was found: Fatty acid modified. melamine resins, their mixtures with paraffin, zirconium salt-containing aqueous paraffin emulsions, polymeric fluorinated hydrocarbons and their mixtures with the above-mentioned substances.

In a special embodiment according to the invention, the highly waterproof coated fleece can also be washed and then treated hydrophobically. In this case, however, the associated increase in water density is excluded.

end up being attributed to a washing out of the fiber avivage from the carrier pile material and to the hydrophobing of the uncoated fiber material and not to an additional improvement of the waterproofness within the foam coating. Appropriately, this washing process and hydrophobing is carried out without intermediate drying, i.e.

using the so-called wet-on-wet impregnation method.

With the method according to the invention, it is thus possible

to equip even very open-structured, weakly bonded, fluffed and highly absorbent fleece fabrics with a closed surface coating that protects against water penetration and at the same time provides extremely good drapeability.

When using pressure-bound, detergent-containing flours with a hydrophilic binding system, a washing process is unavoidable either before or after the foam coating in order to release aqueous preparations with surface-active properties.

As soft, drapeable coating carriers, there are also water-jet needled, binder-free non-woven fabrics with or without structuring.

Such materials have the particular advantage that they are absolutely free of: water-soluble components such as spinning preparations or other aids.

For surgical protective clothing, the backing fabric for a water balance may contain cotton or cell wool to improve wear comfort.

The method according to the invention is therefore applicable to all known, well-draperable carrier pile fabrics.

When preparing polymer dispersions with a very soft film or even a mixture of adhesive raw products, the stickiness of the coating can be avoided by post-treatment with anti-blocking agents. this includes, for example, full-bath impregnations with silicones and talc treatment that only covers the foam surfaces: Talc is suitably powdered before the foam coating is compressed. When pressed, it can then be superficially impressed into the foam. Excess powder is brushed off or shaken off and extracted using a vacuum. Talc is particularly advantageous because already with the smallest applied amounts excellent anti-blocking properties and an additional grip improvement (silky grip) can be achieved.

Instead of talc treatment, microfibers of hydrophobic hard polymers, such as e.g. polycarbonates, are applied by means of electrostatic spinning and pressed into the foam.

In those cases where absorbency or wettability of the base material is not desirable or necessary, the coated material is suitably washed and hydrophobicized, using such hydrophobic agents which also act as antiblocking agents, such as e.g. cationic emulsions of fluorinated or part-fluorinated hydrocarbons. Thereby, in a single step, the carrier fleece can be finished waterproof and the coating can be finished non-stick.

In the following examples, the state of the art will first be made clear and then some: some specially found products/methods will be shown.

Comparein2seksemgel_li_answers

A transverse fiber pile of 90% perlon staple fibers (dtex

1.7/40 mm, matte) and 10% viscose cellulose (dtex 1.3/40 mm, glossy) were thermally bonded in a calender between a heated, smooth steel roll and a steel screen roll. The grid depth was 0.51 mm. Both rolls were heated to 211°C.

The calender line pressure was 686.5 N/cm. The portion of welded together fiber surfaces on the total fiber surface was 24%. This binder-free carrier fabric was coated with a commercially available foamed polyacrylate paste mixture. The viscosity of the unfoamed paste was 1.25 Pa s, measured with spindle no. 3 at a speed of 20 revolutions per revolution. minute (DIN 53 019, Brookfield rotational viscometer). The paste was foamed with a foam mixer to a density of 0.20 g/cm 3 . Its viscosity was 7.50 Pa s, as measured by Brookfiled with a No. 4 spindle at 20 revolutions per minute. minute.

On the 35 g/m<2> heavy basic fleece fabric, it was brushed on

30 g/m<2>foam paste and dried in a belt dryer at 130°C.

The dried foam was then compressed between unheated steel rollers with a line pressure of 98 N/cm. The coated product was then impregnated with a 3% hydrophobizing agent mixture of a paraffinic, fatty acid-modified melamine resin. After squeezing out the bath, the moisture absorption amounted to 100%, referred to the dry weight of the flour material. It was dried and cross-linked in a belt dryer at 150°C. The finished material weight was 67 g/m2. Before the water-repellent finish, the product had a water tightness measured according to DIN 53 886-77 of 6. 10 — 6 Pa and after finishing a value of 1.7 . 10~5 Pa.

This watertightness is not sufficient for use as OP cover fleece fabric or OP gown material. Here, densities of at least 2 are required. 10 -5 Pa.

In addition, the 35 g/m<2> heavy base fleece fabric was also hydrophobically prepared without "Crushed Foam" coating as described above in order to be able to determine which part the base contributes to the improvement of water tightness. In this case, the water density was 1.1. 10 ^ Pa. This means that the pressed foam, even after finishing, only contributes 6 . 10 — 6 Pa to a total water tightness of 1.7. 10 - 5 Pa. In view of the relatively high layer weight of 30 g/m<2>, this value is very poor.

Example_2

1 The 35 g/m<2> heavy base material from example 1 was coated with 30 g/m<2> (solid) of a paste of the following recipe:

Solids content of the mixture: 40%

<+>^High molecular weight granules with moderate etherification,

degree of substitution 1.4-1.6. The 2% solution had a viscosity of 20 Pa s, measured with a

..Haake rotational viscometer at 20°C and a shear drop

of 2.72 s"<1> (DIN 53 788).

The 40%-igé mixture had an unfoamed viscosity according to Brookfield (DIN 53 019) of 2.5 Pa s, measured at 20°C with spindle no. 4 and 20 revolutions per revolution. minute. It was brought to a foam top weight of 0> in a shaking mixer; 13 g/m3. Kon-i

the consistency of this extremely light foam remained a very fine-pored and stable shaving foam. The Brookfield viscosity of the foam was 7.5 Pa s measured with spindle no. 3 at 20 revolutions per minute.

By means of an ironing plant consisting of a steel roller and

with a squeegee knife, 32.5 g/m<2>firm was applied to the base fleece fabric and gently dried in a belt dryer at 130°C for

to prevent tearing of the coating surface due to the water's too rapid evaporation. The foam did not collapse during drying, but retained its volume. The foam was then compressed between two cold steel rollers with a line pressure of 98 N/cm. The water densities measured at 6 different locations were between 3.2. 10 — (first drop of water) and 4.2 . 10-5 Pa (third drop), measured according to DIN 53 886-77. The product had an average weight of 67.4 g/m2, of which 32.4 g/m<2>foam coating.

Additional sample data:

Air permeability at 5 . 10~<7>Pa (DIN 53 887):

14 0 dm3 /s m<2>

Water vapor permeability measured according to Mitton (DIN 53 333):

12.4 mg/cm<2>h

Needle pull-out force: longitudinally 4.5 N

across 6.3N

Fall coefficient as a measure of drapeability (according to DIN 54 306): 58.7%

Linting: No particle shedding, abrasion resistant on

foam side.

Even without subsequent hydrophobing, an extremely high waterproof value is achieved. The item is well water vapor and air permeable and also has an extremely low drop coefficient. The product produced according to example 2 is thus far superior to all coated and uncoated disposable surgical drapes and gown materials according to the state of the art.

In Example_el_3

The coated material produced in example 2 was additionally washed, impregnated wet-in-wet with a hydrophobizing agent emulsion and dried at 145°C on a cylinder dryer. The hydrophobing agent bath consisted of a zirconium salt-containing, aqueous paraffin emulsion with a solids content of 8%. The wet absorption, referred to wet product, amounted to 25% and referred to air-dry product 35%. The finished material weighed an average of 69.3 g/m2. This subsequent finishing increased the water tightness from 3.8. 10 ^ to 4.6 . 10 Pa and furthermore the weak surface stickiness from example 2 could be completely eliminated.

Example<m>pel_4_

The high molecular methyl cellulose used in example 2 was replaced with equal solids of a medium etherified, low molecular type (Haake viscosity (DIN 53 788) of 3 Pa s in a 2% solution). The Brookfield viscosity (DIN 53 019) of the 40% unfoamed paste was 3.2 Pa s (spindle no. 4, 20 revolutions per minute) higher than that of Example 2.

After foaming to a container weight of 0.13 g/cm<3>, a Brookfield viscosity of 7.5 Pa s (spindle #3, 20 rpm) was measured. The foam paste was applied as in example 2. The water density measured on 4 samples fluctuated greatly

-5 -5 little, namely from at least 4.6 . 10 to a maximum of 5.15. 10 Pa. The arithmetically determined water resistance was

4.8. 10~<5>Pa (DIN 53 886-77) without subsequent hydrophobing. The average finished material weight was 6 8.4 g/m2, of which 3 3.4 g/m<2>foam.

Exermoel_5_

In comparison to Example 4, the amount of ammonium stearate was reduced by about 50% and the total amount of fatty acid modified light cationic resin was replaced with 2.5 parts (solid) of a cationically active emulsion of a polymeric fluorinated hydrocarbon.

Here, a hydrofever agent was used, which at the same time exerted an anti-blocking effect on the coating.

The solids content of the foam mixture was again set at 40%. The viscosity measured according to Brookfiled (DIN 53 019) at 20 revolutions per minute with spindle no. 4 in the unfoamed state amounts to 1.35 Pa s and after foaming to 0.13 g/cm<3>

7.52 Pa s (spindle no. 3, 20 revolutions per minute). After processing as in example 2, with an average finished material weight of 67.4 g/m<2>, a water tightness of

4.2. 10~<5>Pa according to DIN 53 886-77 and a completely block-free coating surface.

A material produced according to example 5 can be used in the same way

like all previous tests, disposable surgical gowns and coveralls are used as well.

Example_6

One with cross-crem laid down, two-layer staple fiber fleece

15 g/m<2> of a fiber mixture consisting of 95% perlon and 5% cell wool and of 15 g/m<2> of a mixture of 25% perlon and 75% cell wool were thermally fixed under the same conditions as in example 1. however, the weld area was 14% instead of 24$ and the grid depth 0.65 mm. Due to the special structure and the greater grid depth, a one-sided, extremely frayed, voluminous and very soft pile was produced compared to example 2. As described under example 2, the fluffier of the two sides was coated with 29 g/m<2>foam.

It was then washed and refinished wet-on-wet with

an 8% paraffin emulsion. A water tightness of 3 was achieved. 10 ^ Pa (DIN 53 886-77) at an average finished material weight of 61 g/m2.

Air permeability at 5 . 10 Pa: 120 dm<3>/cm<2>

(DIN 53 887)

Air permeability at 2 . 10 ^ Pa: 450 dm<3>/sm<2>Water vapor permeability according to Mitton (DIN 53- 333):

33.2 mg/cm<2>h

Fall coefficient according to DIN 54 306:

Foam side in the measuring device upwards: 35.4% Foam side in the measuring device downwards: 32.3%

With none of the hitherto known methods of coating or waterproof finishing can a degree of excellent fall ability be achieved with high water tightness on the one hand and high air permeability and water vapor permeability on the other hand.

Claims (12)

1. Covering or dressing cloth for surgery for single use and which has a drapeable carrier fleece material and subsequently a polymeric, waterproof covering layer which does not penetrate this, characterized in that the covering layer consists of a drapeable, water vapor permeable, emulsifier-poor, pressed polymer foam film based on polyacrylic acid ester, polyvinyl acetate acrylate and/or nitrile butadine with a basis weight of 15-50 g/m <2> which respectively referred to foam weight contains 1-15% hydrophobing agent, 3-15% of an ammonium or alkylammonium salt of a long-chain fatty acid with a carbon number between 14 and 20 as a foam stabilizer and at least 0.25% methyl or methylhydroxyalkyl cellulose as thickener. 2. Tire or upholstery fabric according to claim 1, characterized in that the foam stabilizer is ammonium stearate. 3. Tire or upholstery fabric according to claim 1 or 2, characterized in that the foam as hydrophobic agent contains fatty acid modified melamine resins, their mixtures with paraffins, aqueous paraffin emulsions containing zirconium salts, polymeric fluorinated hydrocarbons or their mixtures with the aforementioned substances. 4. Tire or upholstery fabric according to one or more of the preceding requirements, characterized in that the fluorine carrier layer is hydrophobic. 5. Covering or upholstery fabric according to one or more of the preceding claims, characterized in that the coating contains anti-blocking agents. 6. Method for the production of cover or dressing cloth for surgery intended for single use, where, using the "Crushed Foam" technique, an aqueous polymer foam dispersion is applied on one side using squeegees and/or rollers, characterized in that the polymer foam dispersion is based on polyacrylic ester, polyvinyl acetate acrylate or nitrile butadiene and is emulsifier-poor, with the foam weight being less than 0.2 g/cm <3> and the application weight being 15-50 g/m <2> and that the foam, referred to respectively to its total weight, contains 1-15% hydrophobic agent, 3-15% of a foam stabilizer, consisting of an ammonium or alkylammonium salt of a long-chain fatty acid with a carbon number between 14 and 20, and at least 0.25% methyl or methylhydroxyalkyl cellulose as a thickener. 7. Method according to claim 6, characterized in that the viscosity of the unfoamed mixture measured according to DIN 53 019 amounts to 1-2 Pa s. 8. Method according to claim 6 or 7, characterized in that ammonium stearate is used as foam stabilizer. 9. Method according to one or more of the preceding claims, characterized in that the methyl or methyl hydroxyalkyl cellulose is medium to highly etherified. 10. Method according to one or more of the preceding claims, characterized in that it is used as a hydrophobic agent fatty acid modified melamine resins, their mixtures with kerosene, aqueous paraffin emulsions containing zirconium salts, polymeric fluorinated hydrocarbons or their mixtures with the aforementioned substances. 11. Method according to one or more of the preceding claims, characterized in that the product is additionally washed after manufacture, the carrier pile material is then impregnated directly in connection with a hydrophobic agent emulsion and the layer material is then dried. 12. Method according to one or more of the preceding claims, characterized in that the finished coating is impregnated with an anti-blocking agent or the foam is powdered with such before the compression.