CA1244726A - Disposable sheet or drape for surgical use and a process for producing of same - Google Patents
Disposable sheet or drape for surgical use and a process for producing of sameInfo
- Publication number
- CA1244726A CA1244726A CA000511870A CA511870A CA1244726A CA 1244726 A CA1244726 A CA 1244726A CA 000511870 A CA000511870 A CA 000511870A CA 511870 A CA511870 A CA 511870A CA 1244726 A CA1244726 A CA 1244726A
- Authority
- CA
- Canada
- Prior art keywords
- foam
- water
- agent
- sheet
- repellant
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
- A61L31/08—Materials for coatings
- A61L31/10—Macromolecular materials
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
- A61L31/14—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
- A61L31/146—Porous materials, e.g. foams or sponges
Abstract
ABSTRACT
A disposable sheet or garment cloth for surgical use, having a drapable carrier fleece material with a polymeric, waterproof covering layer, which does not penetrate the carrier fleece material. The covering layer consists of a drapable, water vapour permeable, low-emulsifier, pressed polymeric foam film based on polyacryl acid ester, polyvinylacetate acrylate, and/or nitrile butadiene with a surface weight of 15 to 50 g/m2, which, relative to the foam weight, contains 1-15% water repellant agent, 3-15% of an ammonium or alkyl ammonium 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 a thickening agent.
The sheet or garment cloth has good drapability whilst exibiting the required properties of good wear-resistance and water impermeability.
A disposable sheet or garment cloth for surgical use, having a drapable carrier fleece material with a polymeric, waterproof covering layer, which does not penetrate the carrier fleece material. The covering layer consists of a drapable, water vapour permeable, low-emulsifier, pressed polymeric foam film based on polyacryl acid ester, polyvinylacetate acrylate, and/or nitrile butadiene with a surface weight of 15 to 50 g/m2, which, relative to the foam weight, contains 1-15% water repellant agent, 3-15% of an ammonium or alkyl ammonium 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 a thickening agent.
The sheet or garment cloth has good drapability whilst exibiting the required properties of good wear-resistance and water impermeability.
Description
~Z~4726 The present invention relates to a disposable sheet or garment cloth for surgical use, which consists of a water vapour permeable, drapable carrier fleece and a polymeric covering layer that does not permeate the fleece.
Such disposable cloths are being used to an ever increasing extent in surgery, since one-time use ensures total hygiene and the post-operative infection rate in patients is undoubtedly lower than the rate which prevails when laundered, reusable woven cloth is used for surgical purposes.
Thus, the area of application for the present invention is, on the one hand, protective clothing for personnel participating in surgical procedures, and on the other hand, for draping the patient in the peripheral areas that are not immediately adjacent the site of the surgical incision. Essentially, a number of demands are imposed on a disposable cloth for bo~h such areas of use - namely, a high level of water vapour permeability with a high water absorption capability (breathing activity, water balance); water impermeability according to DIN 53 886-77 of the order of at least 2.10 Pa; freedom from lint (high wear resistance) and very good draping ability (i.e. "drape") as well as satisfactory mechanical strength to withstand the forces involved in the manufacture and practical use of the cloth. Freedom from lint is taken to mean the property of a textile material whereby it does not lose or shed particles of fibre or fibre dust during use. Such particles, generated and floating about in the atmosphere of an operating theatre, can act as germ carriers and thus lesd to post-operative infection of the wound.
In particular, re-usable conventional cotton fabrics display an increasingly strong tendency to lint as the number of launderings to which they are subjected increases.
The smaller the lint rate and the greater the impermeability to water, alcohol and physiological fluids a disposable one-time use surgical sheet has, the better it fulfills its important function as a bacterial block or infection preventative.
Known compound materials o film/fleecc or film~tissue paper, or tissue/film/fleece are absolutely impermeable to air and water, and are thus absolutely germ-proof; however, these have the major disadvantage that thay are papery, stiff, non-textile in character, and drape very poorly; they have a rough feel and lead to heat build-up in the patient, particularly during long surgical procedures. Compound materials of polyester fibres and a layer ~Z447~6 of tissue, needled with extremely high-pressure water jets, are also Xnown.
The so-called spun-laced products do not display the above-cited disadvantages. Because they are finished without bonding agents, they combine good bacterial-blocking properties with a high level of textility and good draping qualities, but they also have the disadvantage of significantly higher lint rates than is the case with wet-fleece materials, which applies particularly to the relatively open-structured polyester side. Essentially, this can be attributed to the fact that the cellulose fibrides that are used display less individual bonding with each other and are too short for adequate interlacing of the fibres.
It is an objPct of the present invention to provide a su~gical drape or sheet of fleece material, which is intended for one-time use and meets the requirements set out above, which overcomes the disadvantages discussed herein, and which is also suitable for operating theatre clothing. There is further provided a process for the production of such material.
According to the invention, a disposable cloth for use as a sheet or clothing material has a fleecy carrier layer and a polymer covering that does not penetrate the carrier layer. More particularly, according to the invention, there is provided a disposable sheet or garment cloth for surgical use, having a drapable carrier fleece material with a polymeric, waterproof covering layer, which does not penetrate the carrier fleece material, characterized in that said covering layer consists of a drapable, water vapour permeable, low-emulsifier, pressed polymeric foam film based on polyacryl acid ester, polyvinylacetate acrylate, and/or nitrile butadiene with a surface weight of 15 to S0 g/m , which, relative to the foam weight, contains 1-15%
water repellant agent, 3-15~ of an ammonium or alkyl ammonium 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 a thickening agent.
According to the present invention, the material is produced by the so-called "crushed foam" technique, whereby an aqueous polymer foam dispersion is applied to one side of a drapable fleecy carrier material by means of doctor blades and/or rollers. The polymeric foam dispersion is based on polyacryl ester, polyvinyl acetate acrylate or nitrile butadiene and contains little emulsifying agent; its foam weight is less than 0.2 g/cm3 and its
Such disposable cloths are being used to an ever increasing extent in surgery, since one-time use ensures total hygiene and the post-operative infection rate in patients is undoubtedly lower than the rate which prevails when laundered, reusable woven cloth is used for surgical purposes.
Thus, the area of application for the present invention is, on the one hand, protective clothing for personnel participating in surgical procedures, and on the other hand, for draping the patient in the peripheral areas that are not immediately adjacent the site of the surgical incision. Essentially, a number of demands are imposed on a disposable cloth for bo~h such areas of use - namely, a high level of water vapour permeability with a high water absorption capability (breathing activity, water balance); water impermeability according to DIN 53 886-77 of the order of at least 2.10 Pa; freedom from lint (high wear resistance) and very good draping ability (i.e. "drape") as well as satisfactory mechanical strength to withstand the forces involved in the manufacture and practical use of the cloth. Freedom from lint is taken to mean the property of a textile material whereby it does not lose or shed particles of fibre or fibre dust during use. Such particles, generated and floating about in the atmosphere of an operating theatre, can act as germ carriers and thus lesd to post-operative infection of the wound.
In particular, re-usable conventional cotton fabrics display an increasingly strong tendency to lint as the number of launderings to which they are subjected increases.
The smaller the lint rate and the greater the impermeability to water, alcohol and physiological fluids a disposable one-time use surgical sheet has, the better it fulfills its important function as a bacterial block or infection preventative.
Known compound materials o film/fleecc or film~tissue paper, or tissue/film/fleece are absolutely impermeable to air and water, and are thus absolutely germ-proof; however, these have the major disadvantage that thay are papery, stiff, non-textile in character, and drape very poorly; they have a rough feel and lead to heat build-up in the patient, particularly during long surgical procedures. Compound materials of polyester fibres and a layer ~Z447~6 of tissue, needled with extremely high-pressure water jets, are also Xnown.
The so-called spun-laced products do not display the above-cited disadvantages. Because they are finished without bonding agents, they combine good bacterial-blocking properties with a high level of textility and good draping qualities, but they also have the disadvantage of significantly higher lint rates than is the case with wet-fleece materials, which applies particularly to the relatively open-structured polyester side. Essentially, this can be attributed to the fact that the cellulose fibrides that are used display less individual bonding with each other and are too short for adequate interlacing of the fibres.
It is an objPct of the present invention to provide a su~gical drape or sheet of fleece material, which is intended for one-time use and meets the requirements set out above, which overcomes the disadvantages discussed herein, and which is also suitable for operating theatre clothing. There is further provided a process for the production of such material.
According to the invention, a disposable cloth for use as a sheet or clothing material has a fleecy carrier layer and a polymer covering that does not penetrate the carrier layer. More particularly, according to the invention, there is provided a disposable sheet or garment cloth for surgical use, having a drapable carrier fleece material with a polymeric, waterproof covering layer, which does not penetrate the carrier fleece material, characterized in that said covering layer consists of a drapable, water vapour permeable, low-emulsifier, pressed polymeric foam film based on polyacryl acid ester, polyvinylacetate acrylate, and/or nitrile butadiene with a surface weight of 15 to S0 g/m , which, relative to the foam weight, contains 1-15%
water repellant agent, 3-15~ of an ammonium or alkyl ammonium 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 a thickening agent.
According to the present invention, the material is produced by the so-called "crushed foam" technique, whereby an aqueous polymer foam dispersion is applied to one side of a drapable fleecy carrier material by means of doctor blades and/or rollers. The polymeric foam dispersion is based on polyacryl ester, polyvinyl acetate acrylate or nitrile butadiene and contains little emulsifying agent; its foam weight is less than 0.2 g/cm3 and its
- 2 -~L24~
application wei~ht is 15 to 50 g/m . Relative to its total weight, the foam contains:
1-15% water repellant agent;
application wei~ht is 15 to 50 g/m . Relative to its total weight, the foam contains:
1-15% water repellant agent;
3-15% foam stabilizer, consisting of an ammonium or alkylammonium salt of a long-chain fatty acid with between 14 and 20 carbon atoms per molecule; and at least 0.25% methyl or methylhydroxylalkyl cellulose as a thickening agent.
The principle of the "crushed foam" coating process using aqueous polyacryl acid ester dispersions is known in the art. The polymeric dispersed coating paste bonding agent dispersions, foam stabilizers, thickening agent and, optionally, secondary foam agent and filler are mixed together and the mixture foamed. The foam is applied to the textile base material with doctor blades and/or rollers, and is then dried slowly and the foam layer pressed between cold or heated rollers.
The above process has not, up to the present, been suitable for the production of one-time use surgical fleece material that i9 waterproof to a large extent. The product is not sufficiently waterproof because of the open structure of the fleecy base material and the foam film, even if it '` 20 subsequently made water-repellant. The addition of a water-repellant agent to the coating paste that is to be foamed does not result in a practical surgical material, since this addition results in a drastic reduction in the stability of the foam, which also penetrates into the carrier material to an unacceptable degree. Also known are the above-mentioned foamable polymers as aqueous dispersions. However, the inventors have found that complete mixing to~ether of the dispersed coating paste leads surprisingly to the possibility of providing the foam with the necessary water-repellant agents required for surgical use, without attendant reduction in the stability of the foam and without the foam penetrating into the carrier material.
The viscosities of the unfoamed mixture, measured according to BrooXfield (DIN 53 019 for rotational viscosimeter), vary in the range of 0.8 to 6 Pa s.
Viscosities from l to 2 Pa s have been found preferable.
In order to achieve a high degree of impermQability to water with the lowest applicaton of foam, together with good draping qualities, it is necessary to work with very low foam weights of less than 200 g~litre. This PAT 8118-l ~:4~7~t~
results in extremely high foam viscosity or foam stiffness, which reliably prevents penetration of the coating during application of the foam and the subsequent drying process.
In those cases in which the bonding agent dispersions are difficult to foam or result only in a coarse pored foam, it is necessary to add a small quantity (l~-wt) of a secondary foaming agent, as will be apparent to those skilled in the art.
The product is sufficiently waterproof on the basis of the properties of the foam layer alone (at least 2.10 Pa according to DIN 53 886-77) without the need to make the carrier fleece material water-repellant as well. The water-repellant properties of the foam layer material can be sufficiently well adjusted for most applications simply by way of the "crushed foam" film, whereby film surface weights of 15 g/m in the case of water-repellant carrier fleece materials and of 50 g/m in the case of non-water-repellant carrier fleece materials represent practical limits. Larger quantities would affect the draping qualities of the cloth too much.
According to the present invention, l-1570-wt (all quantities relative to the foam weight) of water-repellant agent is added to the foamable coating paste, in which connertion it is necessary to mix in 2-l5~wt of an ammonium of alkylammonium salt of a long-chain (C14 to C20) fatty acid which is insoluble but dispersable in water, with at least 0.25%-wt of a high molecular weight methyl or methylhydroxalXyl cellulose as a foam stabilizer or thickening agent. Of the salts of long-chain fatty acids, ammonium stearate has been found to be particularly advantageous.
Because of the fact that the ampholytic effect of thickeners increases ~ith the number of methyl groups, moderately or highly etherified methyl or methylhydro~alkyl celluloses are particularly suitable. CarbQxymethyl celluloses, starches, alginates, polyacrylates and other natural, semi- or totally synthetic thickening agents cannot be used.
Preferred water-repellant agents for the coating paste are the following:
fatty acid modified melamine resins, mixtures of fatty acid modified melamine resine with paraffin, aqueous paraffin emulsions containing zirconium, poly fluorinated hydrocarbons and mixtures thereof with the foregoing.
In one embodiment of the present invention, the largely waterproof, coated . - 4 -~LZ~4~2~
fleece material can be additionally washed and subsequently made water-repellant. ~owever, in this case the increased water repellant property is attributable solely to washing out the fibre brighteners of the carrier fleece material and waterproofing the uncoated fibres, and not to an extra improvement of the water-repellant properties within the foam coating. It is best that this washing process and the waterproofing be carried out without any intermediate drying, i.e., by the so-called "wet-in-wet saturation method".
Thus, with the process of the invention, it is possible to provide even fleeces that are of very open structure, weaXly bonded, fluid, and strongly absorbent with a closed surface coating that provides protection against the passage of water and at the same time drapes extremely well.
When pressure-bonded fleeces containing dispersants and having hydrophilic bonding systems are used, a wash process is unavoidable either prior to or after the foam coating procedure so as to detach or loosen aqueous preparations with properties that lower interfacial tension.
Water-jet needled fleeces that contain no bonding agent, with or without structuring, also make soft coating carrier shaving good "drape". Such materials also offer the special advantage that they are completely free of water-soluble components such as spinning preparations or other secondary agents.
For protective surgical garb, the carrier fleece can contain cotton or viscose staple fibre so as to arrive at a better water balance, in order to provide greater comfort during wear.
Thus, the process according to the present invention can be used for all known carrier fleece materials having good drape properties.
In the processing of polymeric dispersions with a very soft film or even blended with adhesive raw products, the adhesiveness of the coating is increased by subsequent treatment with antiblocking agents. Numbered among such treatments are, for example, ordinary bath impregnation with silicones and talcum treatment which covers only the surface of the foam, the talcum preferably being sprinkled on before the foam coating is compressed. It can then be pressed into the surface of the foam during the pressing process.
Excess powder is brushed or sha~en and vacuumed off. For this reason, talcum is particularly desirable, since outstanding antiblocking properties and an extra improvement in the feel of the fabric (a softer feel) can be achieved by ~L2~7;~
the application of only small quantities.
Instead of applyin~ talcum, it is also possible to apply microfibres of water-repellant resin polymers, such as polycarbonates, for example, which can be spun on electrostatically and pressed into the foam.
In those cases where it is not desired or necessary that the bases material be absorbent or wettable, the coated material is best washed and waterproofed; when this is done, waterproofin~ a~ents that are simultaneously effective as antiblockin~ a~ents are used - for example, action-active emulsions of fluorinated or partially fluorinated hydrocarbons. By this means, the carrier fleece can be made water-repellant and the coatin~ made free of adhesive.
The following examples illustrate the state of the art, followed by examples of preferred products and processes for their production in accordance with the invention.
Comparative Example 1 ~ DL-~h~ f the Art A traversely laid-up fibre fleece of 90~ Perlon* staple fibre (dtex 1.7/40 mm, matte) and 10% viscose staple fibre (dtex 1.4/40 mm, shiny) were thermally consolidated in a calender between a heated, smooth steel roller and a steel screened roller. The screen depth was 0.51 mm. Both rollers were heated to 211C.
The linear pressure of the calender was 686.5 N/cm, and the proportion of welded fibre surface to the total fleece surface amounted to 24%. This binder-free carrier fleece material was coated with a commercially available foamed polyacrylate paste mixture. The viscosity of the unfoamed paste amounted to 1.25 Pa s, measured with spindle No. 3 at a rotational speed of 20 rpm (DIN 53 019, Brookfield rotatin~ viscosimeter). The paste was foamed to a density of 0.20 g/m with a foam mixer. Its viscosity was 7.50 Pa s, measured accordin~ to Brookfield with spindle No. 4 at 20 rpm.
*trademark . -- 6 --~;~44~726 Foam paste was applied to the 35 g/m base fleece material at a rate of 30 g/m and dried in a belt dryer at 130C. The dried foam was then compressed between unheated steel rollers with a linear pressure of 98 N/cm.
Subsequently, the coated material was impregnated with a 3% waterproofing agent mixture of a fatty acid modified melamine resin containing paraffin.
The wet absorption after quenching the liquor was 100~, relative to the dry wei~ht of the fleece. Drying and cross-linking were carried out in a belt dryer at 105C.
The wei~ht of the finished material was 67 gJm . The material was water-repellant, prior to waterproofing, at 6.10 Pa, measured according to DIN 53 886-88 and, after finishing, this value was 1.7.10 Pa.
This de~ree of water-repellancy is insufficient for use as a surgical drape material or as a material for surgical gowns. Such applications require a value of at least 2.10 Pa.
In addition, the 35 g/m base fleece material was also finished to be water-repellant, as described above, without the "crushed foam" coating, in order to ascertain to what degree the base material contributed to improving the water-repellant properties. The water-repellant value was 1.1.10 Pa in this case. This means that even after finishing, the compressed foam only contributes 6.10 Pa to the overall water-repellancy value of 1.7.10 Pa. This value is very poor when one considers the relatively high coating wei~ht of 30 g/m .
: - 7 -72~i Exan~le ~o. 2 The 35 g/m base material as in Example No. 1 was coated at a fixed rate of 30 ~,/m with a paste made up as follows:
Parts Parts Constituent Solid Liquid Cold water - - 26.26 Pigment dye 0.315 0.63 Anionic secondary foaming a~ent 0.800 4.00 10 Liquid, modified fatty acid, weakly cationic melam;ne resin; 40%
emulsion 12.000 30.00 Methylcellulose; 0.37O* 0.300 10.00 ~anonium stearate; 507O 11.000 22.00 Polyacryl acid ester dispersion; 507O 20.000 40.000 Low emulsifier dispersion of a soft polyacryl acid ester; 45% 80.000 178.000 TOTAL 124.315 310.79 20 Solids content of mixture: 40%
*Hi~h molecular wei~ht ~ranulate with avera~e etherification, substitution deg,ree 1.4-1.6. The 2% solution had a viscosity of 20 Pa s, measured with a Haake rotation viscosimeter at 20C and a shear rate of 2.72 sec.
tDIN 53 788).
~4~7~
Unfoamed, the bO% mixture had a viscosity according to Brookfield (DIN 53 019) of 2.5 Pa s, measured at 20C with spindle No. 4 and at 20 rpm.
It was brought to a foam weight of 0.13 g/m in an agitation-mixer. The consistency of this extremely light foam was like that of a shaving cream, very fine pored and stable. The Brookfield viscosity of the foam was 7.5 Pa s, measured with spindle No. 3 at 20 rpm.
Using a spreading device consisting o a steel roller and a doctor blade, 32.5 g/m was applied to the base fleece, and then carefully dried in a belt dryer at 130C, care being taken to prevent tearing of the surface of the coating resulting from too rapid evaporation of the water. The foam did not collapse, but retained its volume during the drying period. Finally, the foam was compressed between two cold steel rollers with a linear pressurc of 98 N/cm. The water-proof value, measured at six di~ferent locations, was between 3.2.10 Pa tfirst water droplets) and 4.2.10 Pa (third droplets), measured according to DIN 53 886-77. The product had an average weight of 67.4 g/m , of which 32.4 g/m was the foam coating.
Additional Test Data:
Air permeability at 5.10 Pa (DIN 53 887): 140 dm /s m .
Water vapour permeability, measured according to Mittou (DIN 53 333):
12.4 mg/cm h Needle tear force: lengthwise 4.5 ~
crosswise 6.3 N
Coefficient of drape, as an indication of drapability (according to DIN 54 306): 58.7~
Linting: no particle separation, wear resistant on the foam side.
Even without subsequent waterproofing, an extremely high water-repellancy value was achieved. The material's permeability to water vapour and air was good, and its drape coefficient was extremely low. The material produced as in Example No. 2 was far superior to any one-time use surgical drape or gown material, coated or uncoated, according to the state of the art.
Example No. 3 The material produced and coated as in Example No. 2 was additionally washed, wet-in-wet impregnated with a water-repellant agent emulsion, and dryed at 145C on a cylinder dryer. The water-repellant agent bath consisted of an aqueous paraffin emulsion containin~ zirconium, with a solids content of _ g _ 447;~i 8~. The wet absorption, relative to wet material, was 25% and 35~ relative to air-dryed material. The finished material wei~hed on average 69.3 ~/m .
This subsequent finishing increased impermeability to water from 3.8.10 to
The principle of the "crushed foam" coating process using aqueous polyacryl acid ester dispersions is known in the art. The polymeric dispersed coating paste bonding agent dispersions, foam stabilizers, thickening agent and, optionally, secondary foam agent and filler are mixed together and the mixture foamed. The foam is applied to the textile base material with doctor blades and/or rollers, and is then dried slowly and the foam layer pressed between cold or heated rollers.
The above process has not, up to the present, been suitable for the production of one-time use surgical fleece material that i9 waterproof to a large extent. The product is not sufficiently waterproof because of the open structure of the fleecy base material and the foam film, even if it '` 20 subsequently made water-repellant. The addition of a water-repellant agent to the coating paste that is to be foamed does not result in a practical surgical material, since this addition results in a drastic reduction in the stability of the foam, which also penetrates into the carrier material to an unacceptable degree. Also known are the above-mentioned foamable polymers as aqueous dispersions. However, the inventors have found that complete mixing to~ether of the dispersed coating paste leads surprisingly to the possibility of providing the foam with the necessary water-repellant agents required for surgical use, without attendant reduction in the stability of the foam and without the foam penetrating into the carrier material.
The viscosities of the unfoamed mixture, measured according to BrooXfield (DIN 53 019 for rotational viscosimeter), vary in the range of 0.8 to 6 Pa s.
Viscosities from l to 2 Pa s have been found preferable.
In order to achieve a high degree of impermQability to water with the lowest applicaton of foam, together with good draping qualities, it is necessary to work with very low foam weights of less than 200 g~litre. This PAT 8118-l ~:4~7~t~
results in extremely high foam viscosity or foam stiffness, which reliably prevents penetration of the coating during application of the foam and the subsequent drying process.
In those cases in which the bonding agent dispersions are difficult to foam or result only in a coarse pored foam, it is necessary to add a small quantity (l~-wt) of a secondary foaming agent, as will be apparent to those skilled in the art.
The product is sufficiently waterproof on the basis of the properties of the foam layer alone (at least 2.10 Pa according to DIN 53 886-77) without the need to make the carrier fleece material water-repellant as well. The water-repellant properties of the foam layer material can be sufficiently well adjusted for most applications simply by way of the "crushed foam" film, whereby film surface weights of 15 g/m in the case of water-repellant carrier fleece materials and of 50 g/m in the case of non-water-repellant carrier fleece materials represent practical limits. Larger quantities would affect the draping qualities of the cloth too much.
According to the present invention, l-1570-wt (all quantities relative to the foam weight) of water-repellant agent is added to the foamable coating paste, in which connertion it is necessary to mix in 2-l5~wt of an ammonium of alkylammonium salt of a long-chain (C14 to C20) fatty acid which is insoluble but dispersable in water, with at least 0.25%-wt of a high molecular weight methyl or methylhydroxalXyl cellulose as a foam stabilizer or thickening agent. Of the salts of long-chain fatty acids, ammonium stearate has been found to be particularly advantageous.
Because of the fact that the ampholytic effect of thickeners increases ~ith the number of methyl groups, moderately or highly etherified methyl or methylhydro~alkyl celluloses are particularly suitable. CarbQxymethyl celluloses, starches, alginates, polyacrylates and other natural, semi- or totally synthetic thickening agents cannot be used.
Preferred water-repellant agents for the coating paste are the following:
fatty acid modified melamine resins, mixtures of fatty acid modified melamine resine with paraffin, aqueous paraffin emulsions containing zirconium, poly fluorinated hydrocarbons and mixtures thereof with the foregoing.
In one embodiment of the present invention, the largely waterproof, coated . - 4 -~LZ~4~2~
fleece material can be additionally washed and subsequently made water-repellant. ~owever, in this case the increased water repellant property is attributable solely to washing out the fibre brighteners of the carrier fleece material and waterproofing the uncoated fibres, and not to an extra improvement of the water-repellant properties within the foam coating. It is best that this washing process and the waterproofing be carried out without any intermediate drying, i.e., by the so-called "wet-in-wet saturation method".
Thus, with the process of the invention, it is possible to provide even fleeces that are of very open structure, weaXly bonded, fluid, and strongly absorbent with a closed surface coating that provides protection against the passage of water and at the same time drapes extremely well.
When pressure-bonded fleeces containing dispersants and having hydrophilic bonding systems are used, a wash process is unavoidable either prior to or after the foam coating procedure so as to detach or loosen aqueous preparations with properties that lower interfacial tension.
Water-jet needled fleeces that contain no bonding agent, with or without structuring, also make soft coating carrier shaving good "drape". Such materials also offer the special advantage that they are completely free of water-soluble components such as spinning preparations or other secondary agents.
For protective surgical garb, the carrier fleece can contain cotton or viscose staple fibre so as to arrive at a better water balance, in order to provide greater comfort during wear.
Thus, the process according to the present invention can be used for all known carrier fleece materials having good drape properties.
In the processing of polymeric dispersions with a very soft film or even blended with adhesive raw products, the adhesiveness of the coating is increased by subsequent treatment with antiblocking agents. Numbered among such treatments are, for example, ordinary bath impregnation with silicones and talcum treatment which covers only the surface of the foam, the talcum preferably being sprinkled on before the foam coating is compressed. It can then be pressed into the surface of the foam during the pressing process.
Excess powder is brushed or sha~en and vacuumed off. For this reason, talcum is particularly desirable, since outstanding antiblocking properties and an extra improvement in the feel of the fabric (a softer feel) can be achieved by ~L2~7;~
the application of only small quantities.
Instead of applyin~ talcum, it is also possible to apply microfibres of water-repellant resin polymers, such as polycarbonates, for example, which can be spun on electrostatically and pressed into the foam.
In those cases where it is not desired or necessary that the bases material be absorbent or wettable, the coated material is best washed and waterproofed; when this is done, waterproofin~ a~ents that are simultaneously effective as antiblockin~ a~ents are used - for example, action-active emulsions of fluorinated or partially fluorinated hydrocarbons. By this means, the carrier fleece can be made water-repellant and the coatin~ made free of adhesive.
The following examples illustrate the state of the art, followed by examples of preferred products and processes for their production in accordance with the invention.
Comparative Example 1 ~ DL-~h~ f the Art A traversely laid-up fibre fleece of 90~ Perlon* staple fibre (dtex 1.7/40 mm, matte) and 10% viscose staple fibre (dtex 1.4/40 mm, shiny) were thermally consolidated in a calender between a heated, smooth steel roller and a steel screened roller. The screen depth was 0.51 mm. Both rollers were heated to 211C.
The linear pressure of the calender was 686.5 N/cm, and the proportion of welded fibre surface to the total fleece surface amounted to 24%. This binder-free carrier fleece material was coated with a commercially available foamed polyacrylate paste mixture. The viscosity of the unfoamed paste amounted to 1.25 Pa s, measured with spindle No. 3 at a rotational speed of 20 rpm (DIN 53 019, Brookfield rotatin~ viscosimeter). The paste was foamed to a density of 0.20 g/m with a foam mixer. Its viscosity was 7.50 Pa s, measured accordin~ to Brookfield with spindle No. 4 at 20 rpm.
*trademark . -- 6 --~;~44~726 Foam paste was applied to the 35 g/m base fleece material at a rate of 30 g/m and dried in a belt dryer at 130C. The dried foam was then compressed between unheated steel rollers with a linear pressure of 98 N/cm.
Subsequently, the coated material was impregnated with a 3% waterproofing agent mixture of a fatty acid modified melamine resin containing paraffin.
The wet absorption after quenching the liquor was 100~, relative to the dry wei~ht of the fleece. Drying and cross-linking were carried out in a belt dryer at 105C.
The wei~ht of the finished material was 67 gJm . The material was water-repellant, prior to waterproofing, at 6.10 Pa, measured according to DIN 53 886-88 and, after finishing, this value was 1.7.10 Pa.
This de~ree of water-repellancy is insufficient for use as a surgical drape material or as a material for surgical gowns. Such applications require a value of at least 2.10 Pa.
In addition, the 35 g/m base fleece material was also finished to be water-repellant, as described above, without the "crushed foam" coating, in order to ascertain to what degree the base material contributed to improving the water-repellant properties. The water-repellant value was 1.1.10 Pa in this case. This means that even after finishing, the compressed foam only contributes 6.10 Pa to the overall water-repellancy value of 1.7.10 Pa. This value is very poor when one considers the relatively high coating wei~ht of 30 g/m .
: - 7 -72~i Exan~le ~o. 2 The 35 g/m base material as in Example No. 1 was coated at a fixed rate of 30 ~,/m with a paste made up as follows:
Parts Parts Constituent Solid Liquid Cold water - - 26.26 Pigment dye 0.315 0.63 Anionic secondary foaming a~ent 0.800 4.00 10 Liquid, modified fatty acid, weakly cationic melam;ne resin; 40%
emulsion 12.000 30.00 Methylcellulose; 0.37O* 0.300 10.00 ~anonium stearate; 507O 11.000 22.00 Polyacryl acid ester dispersion; 507O 20.000 40.000 Low emulsifier dispersion of a soft polyacryl acid ester; 45% 80.000 178.000 TOTAL 124.315 310.79 20 Solids content of mixture: 40%
*Hi~h molecular wei~ht ~ranulate with avera~e etherification, substitution deg,ree 1.4-1.6. The 2% solution had a viscosity of 20 Pa s, measured with a Haake rotation viscosimeter at 20C and a shear rate of 2.72 sec.
tDIN 53 788).
~4~7~
Unfoamed, the bO% mixture had a viscosity according to Brookfield (DIN 53 019) of 2.5 Pa s, measured at 20C with spindle No. 4 and at 20 rpm.
It was brought to a foam weight of 0.13 g/m in an agitation-mixer. The consistency of this extremely light foam was like that of a shaving cream, very fine pored and stable. The Brookfield viscosity of the foam was 7.5 Pa s, measured with spindle No. 3 at 20 rpm.
Using a spreading device consisting o a steel roller and a doctor blade, 32.5 g/m was applied to the base fleece, and then carefully dried in a belt dryer at 130C, care being taken to prevent tearing of the surface of the coating resulting from too rapid evaporation of the water. The foam did not collapse, but retained its volume during the drying period. Finally, the foam was compressed between two cold steel rollers with a linear pressurc of 98 N/cm. The water-proof value, measured at six di~ferent locations, was between 3.2.10 Pa tfirst water droplets) and 4.2.10 Pa (third droplets), measured according to DIN 53 886-77. The product had an average weight of 67.4 g/m , of which 32.4 g/m was the foam coating.
Additional Test Data:
Air permeability at 5.10 Pa (DIN 53 887): 140 dm /s m .
Water vapour permeability, measured according to Mittou (DIN 53 333):
12.4 mg/cm h Needle tear force: lengthwise 4.5 ~
crosswise 6.3 N
Coefficient of drape, as an indication of drapability (according to DIN 54 306): 58.7~
Linting: no particle separation, wear resistant on the foam side.
Even without subsequent waterproofing, an extremely high water-repellancy value was achieved. The material's permeability to water vapour and air was good, and its drape coefficient was extremely low. The material produced as in Example No. 2 was far superior to any one-time use surgical drape or gown material, coated or uncoated, according to the state of the art.
Example No. 3 The material produced and coated as in Example No. 2 was additionally washed, wet-in-wet impregnated with a water-repellant agent emulsion, and dryed at 145C on a cylinder dryer. The water-repellant agent bath consisted of an aqueous paraffin emulsion containin~ zirconium, with a solids content of _ g _ 447;~i 8~. The wet absorption, relative to wet material, was 25% and 35~ relative to air-dryed material. The finished material wei~hed on average 69.3 ~/m .
This subsequent finishing increased impermeability to water from 3.8.10 to
4.6.10 Pa, and in addition the weak surfsce adhesiveness found in Example No. 2 could be totally removed.
Example No. 4 The hiBh molecular weight methyl cellulose used in Example No. 2 was replaced by equal parts of solids of a medium-etherified, low molecular weight type (Haake viscosity (DIN 53 788) of 3 Pa s in a 2~ solution). At 3.2 Pa s (spindle No. 4, 20 rpm~ the Brookfield viscosity (DIN 53 019) of the 40%
unfoamed paste was higher than that in Example No. 2. After foaming to a weight of 0.13 g/cm , a Broo~field viscosity of 7.5 Pa s (spindle No. 3, 20 rpm) was measured. The foam psste was applied as in Example No. 2. The water-repellant value, measured on four samples, varied v0ry little, from at least 4.6.10 to at most 5.15.10 Pa. The arithmetically average water holding ability was 4.8.10 Pa (DIN 53 886-77), without subsequent waterproofin~. The average wei~ht of the finished material was 68.4 g/m , of which 33.4 g/cm was foam.
Example No. S
The proportion of ammonium stearate was reduced by 50~ by comparison with Example No. 4, and the total quantity of fatty acid modified, slightly cationic resin was replaced by 2.5 parts (solids) of a cationically active emulsion of a polymer fluorinated hydrocarbon. Thus, in this instance, a water-repellant agent that simultaneously exerted an antiblocking effect on the coating was used.
Material finished as in Example No. S can be used, like all the former samples, for one-time use sur~ical gowns and sur~ical draping material.
Example No. 6 A two-layered staple fibre was laid up with transverse combs from a 15 g/m fibre blend consisting of 95% Perlon* and 5~ synthetic fibra, and from a lS g/m2 blend of 25~ Perlon and 75% synthetic fibre was thermally consolidated under the same conditions as in Example ~o. 1. The welding area was 14~ instead of 24~, however, and the screen depth was 0.65 mm. Because of the special structure and the ~reater screen depth, a one-sided, extremely fluid, voluminous and very soft fleece was produced by comparison with that of *Trade Mark ~'` -- 10 --Example No. 2. The more fluid of the two sides was covered with 29 g/m foam, as described in Example No. 2. Next, this was washed and wet-in-wet finished with an 8% paraffin emulsion. This resulted in a water-repellant value of 3.10 (DIN 53 886-77) at an average finished material weight of 61 g/m .
Air permeability at 5.10 Pa: 120 dm /sec. m (DIN 53 887) Air permeability at 2.10 Pa: 450 dm /sec. m Water permeability according to ~itton (DIN 53 333): 33.2 mgtcm .
hr.
Drape coefficient according to DIN 54 306:
Foam side measured as above: 35.470 Foam side measured as below: 32.3%
With none of the methods for coating or water-repellant finishing used up to now is it possible to achieve such excellent draping qualities with a hi~h water-repellancy on the one hand, and a high level of air permeability and water vapour permeability on the other.
Example No. 4 The hiBh molecular weight methyl cellulose used in Example No. 2 was replaced by equal parts of solids of a medium-etherified, low molecular weight type (Haake viscosity (DIN 53 788) of 3 Pa s in a 2~ solution). At 3.2 Pa s (spindle No. 4, 20 rpm~ the Brookfield viscosity (DIN 53 019) of the 40%
unfoamed paste was higher than that in Example No. 2. After foaming to a weight of 0.13 g/cm , a Broo~field viscosity of 7.5 Pa s (spindle No. 3, 20 rpm) was measured. The foam psste was applied as in Example No. 2. The water-repellant value, measured on four samples, varied v0ry little, from at least 4.6.10 to at most 5.15.10 Pa. The arithmetically average water holding ability was 4.8.10 Pa (DIN 53 886-77), without subsequent waterproofin~. The average wei~ht of the finished material was 68.4 g/m , of which 33.4 g/cm was foam.
Example No. S
The proportion of ammonium stearate was reduced by 50~ by comparison with Example No. 4, and the total quantity of fatty acid modified, slightly cationic resin was replaced by 2.5 parts (solids) of a cationically active emulsion of a polymer fluorinated hydrocarbon. Thus, in this instance, a water-repellant agent that simultaneously exerted an antiblocking effect on the coating was used.
Material finished as in Example No. S can be used, like all the former samples, for one-time use sur~ical gowns and sur~ical draping material.
Example No. 6 A two-layered staple fibre was laid up with transverse combs from a 15 g/m fibre blend consisting of 95% Perlon* and 5~ synthetic fibra, and from a lS g/m2 blend of 25~ Perlon and 75% synthetic fibre was thermally consolidated under the same conditions as in Example ~o. 1. The welding area was 14~ instead of 24~, however, and the screen depth was 0.65 mm. Because of the special structure and the ~reater screen depth, a one-sided, extremely fluid, voluminous and very soft fleece was produced by comparison with that of *Trade Mark ~'` -- 10 --Example No. 2. The more fluid of the two sides was covered with 29 g/m foam, as described in Example No. 2. Next, this was washed and wet-in-wet finished with an 8% paraffin emulsion. This resulted in a water-repellant value of 3.10 (DIN 53 886-77) at an average finished material weight of 61 g/m .
Air permeability at 5.10 Pa: 120 dm /sec. m (DIN 53 887) Air permeability at 2.10 Pa: 450 dm /sec. m Water permeability according to ~itton (DIN 53 333): 33.2 mgtcm .
hr.
Drape coefficient according to DIN 54 306:
Foam side measured as above: 35.470 Foam side measured as below: 32.3%
With none of the methods for coating or water-repellant finishing used up to now is it possible to achieve such excellent draping qualities with a hi~h water-repellancy on the one hand, and a high level of air permeability and water vapour permeability on the other.
Claims (12)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A disposable sheet or garment cloth for surgical use, having a drapeable carrier fleece material with a polymeric, waterproof covering layer, which does not penetrate the carrier fleece material, characterized in that said covering layer consists of a drapable, water vapour permeable, low-emulsifier, pressed polymer foam film based on polyacryl acid ester, polyvinylacetate acrylate, and/or nitrile butadiene with a surface weight of 15 to 50 g/m2,which, relative to the foam weight, contains 1-15% water repellant agent, 3-15% of an ammonium or alkyl ammonium 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 a thickening agent.
2. A sheet or garment cloth as in claim 1, characterized in that the foam stabilizer is ammonium stearate.
3. A sheet or garment cloth as in claim 1, characterized in that the foam contains a water-repellant agent selected from:
fatty acid modified melamine resins or mixtures thereof with paraffin;
aqueous paraffin emulsions containing zirconium; and polymer fluorinated hydrocarbons of mixtures thereof with the foregoing.
fatty acid modified melamine resins or mixtures thereof with paraffin;
aqueous paraffin emulsions containing zirconium; and polymer fluorinated hydrocarbons of mixtures thereof with the foregoing.
4. A sheet or garment cloth according to any of claims 1 to 3, characterized in that the fleece material carrier layer is water-repellant.
5. A sheet or garment cloth according to any of claims 1 to 3, characterized in that the covering layer contains antiblocking agent.
6. A process for the production of a one-time use sheet or garment cloth for surgical use, in which an aqueous polymeric foam dispersion is applied to one side of a drapable carrier fleece material by means of doctor blades and/or rollers using a "crushed foam" technique, characterized in that the polymeric foam dispersion is based on polyacryl ester, polyvinylacetate acrylate or nitrile butadiene, and has a low emulsifier content, its foam weight being less than 0.2 g/cm3 and its application weight being 15 to 50 g/m2; and in that, relative to its total weight, the foam contains 1-15% water-repellant agent, 3-15% foam stabilizer, consisting of an ammonium or alkyl ammonium 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 thickening agent.
7. A process as claimed in claim 6, characterized in that the viscosity of the unfoamed mixture, measured according to DIN 53 019, is 1 to 2 Pa s.
8. A process as in claim 6 or claim 7, characterized in that ammonium stearate is used as the foam stabilizer.
9. A process as claimed in claim 6 or claim 7, characterized in that the methyl or methylhydroxyalkyl cellulose is medium to highly etherified.
10. A process as claimed in claim 6 or claim 7, characterized in that the water-repellant agent is selected from:
fatty acid modified melamine resins, or mixtures thereof with paraffin;
aqueous paraffin emulsions containing zirconium; and polymeric fluorinated hydrocarbons or mixtures thereof with the foregoing
fatty acid modified melamine resins, or mixtures thereof with paraffin;
aqueous paraffin emulsions containing zirconium; and polymeric fluorinated hydrocarbons or mixtures thereof with the foregoing
11. A process as claimed in claim 6 or claim 7, characterized in that the product is additionally washed and the carrier fleece is then impregnated with a waterproofing agent emulsion and the material is then dried.
12. A process as claimed in claim 6 or claim 7, characterized in that the finished coating is impregnated with an antiblocking agent prior to compression.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3522051.1 | 1985-06-20 | ||
| DE19853522051 DE3522051A1 (en) | 1985-06-20 | 1985-06-20 | DISPOSABLE DISCLOSURE OR CLOTHING CLOTH FOR SURGERY AND METHOD FOR THE PRODUCTION THEREOF |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1244726A true CA1244726A (en) | 1988-11-15 |
Family
ID=6273722
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000511870A Expired CA1244726A (en) | 1985-06-20 | 1986-06-18 | Disposable sheet or drape for surgical use and a process for producing of same |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0205660A3 (en) |
| JP (1) | JPS61290951A (en) |
| CN (1) | CN86100715A (en) |
| BR (1) | BR8600880A (en) |
| CA (1) | CA1244726A (en) |
| DE (1) | DE3522051A1 (en) |
| ES (1) | ES8705765A1 (en) |
| NO (1) | NO854814L (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4031943A1 (en) * | 1990-10-09 | 1992-04-16 | Silver Plastics Gmbh & Co Kg | Sterilisable surgical cloth - with heat bonded absorbent outer thermoplastic layer, impermeable thermoplastic barrier layer and permeable thermoplastic base layer |
| DE4031942A1 (en) * | 1990-10-09 | 1992-04-30 | Silver Plastics Gmbh & Co Kg | Sterilisable surgical cloth with outer viscose layer - and permeable base layer, with thermoplastic synthetic adhesive between outer and barrier layers |
| DE4324136A1 (en) * | 1993-04-02 | 1994-10-06 | Rotecno Ag | Medical operation covering system |
| FR2765777B1 (en) * | 1997-07-11 | 1999-10-29 | Borreani Patrick | PROCESS FOR COATING A TEXTILE SUBSTRATE, IN THE FORM OF A GLOVE IN PARTICULAR |
| DE102004024042A1 (en) * | 2004-05-07 | 2005-11-24 | Paul Hartmann Ag | Non-woven / film laminate |
| DE102004024043A1 (en) * | 2004-05-07 | 2005-11-24 | Paul Hartmann Ag | Non-woven / film laminate |
| US7594512B2 (en) * | 2005-10-07 | 2009-09-29 | Allegiance Corporation | Fenestrated extremity surgical drape |
| CN105415768A (en) * | 2015-12-21 | 2016-03-23 | 常熟市一心无纺制品有限公司 | Wear-resisting nonwoven fabric |
| CN110696460A (en) * | 2017-03-20 | 2020-01-17 | 蔡仁杰 | Preparation method of surgical drape cloth base material |
| CN113829703B (en) * | 2021-09-16 | 2023-04-28 | 圣华盾防护科技股份有限公司 | Reusable non-woven fabric composite fabric and processing technology |
| CN113796621B (en) * | 2021-09-17 | 2023-01-31 | 佛山市嘉信盈科技有限公司 | Moisture-absorbing, breathable and shock-absorbing acrylic ester foam material insole and preparation method thereof |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3887408A (en) * | 1973-04-24 | 1975-06-03 | Rohm & Haas | Method of forming permeable polymeric liner on absorbent diapers, wound dressings, catamenial pads and the like |
| US3974308A (en) * | 1974-04-05 | 1976-08-10 | Kimberly-Clark Corporation | Method for treating a disposable surgical drape |
| US4146027A (en) * | 1976-09-24 | 1979-03-27 | Rohm And Haas Company | Method for dressing a wound |
| US4308303A (en) * | 1978-11-02 | 1981-12-29 | Johnson & Johnson | Flocked, foam-coated, fibrous-reinforced, water vapor permeable, bacterial barrier |
| US4353945A (en) * | 1978-11-02 | 1982-10-12 | Johnson & Johnson | Flocked, foam-coated, water vapor permeable, bacterial barrier |
| FR2494128B1 (en) * | 1980-11-20 | 1985-11-29 | Johnson & Johnson | BACTERIAL BARRIER WITH TEXTILE FILLER, COATED WITH FOAM AND PERMEABLE WITH WATER VAPOR |
-
1985
- 1985-06-20 DE DE19853522051 patent/DE3522051A1/en not_active Withdrawn
- 1985-11-15 EP EP85114533A patent/EP0205660A3/en not_active Withdrawn
- 1985-11-29 NO NO854814A patent/NO854814L/en unknown
- 1985-12-18 ES ES550097A patent/ES8705765A1/en not_active Expired
-
1986
- 1986-01-28 CN CN198686100715A patent/CN86100715A/en active Pending
- 1986-02-28 BR BR8600880A patent/BR8600880A/en unknown
- 1986-05-12 JP JP61108391A patent/JPS61290951A/en active Pending
- 1986-06-18 CA CA000511870A patent/CA1244726A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3522051A1 (en) | 1987-01-02 |
| EP0205660A3 (en) | 1988-09-28 |
| CN86100715A (en) | 1986-12-24 |
| ES550097A0 (en) | 1987-05-16 |
| NO854814L (en) | 1986-12-22 |
| EP0205660A2 (en) | 1986-12-30 |
| BR8600880A (en) | 1987-01-13 |
| JPS61290951A (en) | 1986-12-20 |
| ES8705765A1 (en) | 1987-05-16 |
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