CA1160519A

CA1160519A - Method of producing a supporting bandage and bandaging material suitable for this purpose

Info

Publication number: CA1160519A
Application number: CA000289443A
Authority: CA
Inventors: Franz A. Straube; Gunther Lehnert
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1976-11-09
Filing date: 1977-10-25
Publication date: 1984-01-17
Also published as: FR2369830B1; FR2369830A1; SE426289B; BE860638A; IT1106242B; PL201981A1; ES463943A1; JPS5361184A; DE2651089A1; FI773323A; CH633718A5; SU741779A3; US4376438A; GB1578895A; AU505816B2; NO143129B; AU3045277A; SE7712606L; NL7712248A; DE2651089B2

Abstract

Abstract of the Disclosure The present invention relates to a process for producing a supporting bandage for surgical or veterinary surgical use comprising covering the part of the body which is required to be supported with an air-permeable dressing and then applying a self-hardening bandage over this dress-ing characterized in that the self-hardening bandage com-prise strips of air-permeable, flexible fabric coated and/or impregnated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer which contains free isocyanate groups and is based on aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms, the prepolymer having an isocyanate content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5 by weight, the coated fabric being soaked with water immediately before it is applied. The present invention also relates to lengths of bandaging material which comprise pieces of flexible, air-permeable fabric coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer based on aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms, the isocy-anate prepolymer having an isocyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

Description

l 16~519 ;

This invention relates to a bandaging material and to a process of producing a bandaging material.
It is known to use bandaging material impregnated with plaster of Paris for making stiff bandages. These plaster of Paris bandages are too heavy and insufficiently permeable to air and once set they rapidly lose their strength when moist, for example when brought into contact with water.
Furthermore, owing to their capacity to absorb and scatter X-rays, they affect the diagnostic results of X-ray photo-graphs and, owing to their inadequate resistance to water, they often give rise to skin irritation brought about by bacterial or;mold growth in the bandage.
m ere have, therefore, been many attempts to provide bandaging materials which are free from these disadvantages.
It has for example been attempted to impregnate bandaging ^' material with polymer solutions which harden under exposure to W light and then to harden the impregnated bandage by irradiation with W lamp. (Chemical Orthopaedics and Related Research 108, 109 - 117 (1974)).
The W lamps required for this purpose are difficult to handle, and moreover, the W light only reaches the upper layers of the bandage so that the deeper layers harden only after a considerable time if at all. Another serious disadvantage of this method is that while the bandage is being hardened by W light, the fracture under the bandage cannot be observed by X-rays.
A bandaging material which is capable of stiffening has been described in German Offenlegungsschrift No. 2,353,212.

F a~

l 16~519 It consists of a flexible basic material treated with sub-stances which contain oxycarbonyl isocyanate groups. The bandaging material described in German Offenlegungsschrift No.

2,353,212 was not successful in practice, partly because practically insurmountable difficulties were encountered in the manufacture of the bandaging material owing to the extremely high reactivity of oxycarbonyl isocyanates and partly because casts or supporting bandages made from these materials were not strong.enough for the purposes required. Furthermore, the high.reactivity of oxycarbonyl isocyanates rendered the impregnated bandaging material extremely unstable in storage since the prepolymers with oxycarbonyl isocyanate and urethane groups used according to German Offenlegungsschrift No.2,353,212 rapidly harden even.in the absence of atmospheric moisture.

lS The process described in German OffenlegungsSChrift No. 2,357,931 for producing hardened bandages is also generally unsuitable for medical or surgical purposes because the process of hardening by the action of atmospheric moisture described in thae Offenlegungsschrift takes too long.

The present invention provides a novel process for producing supporting bandages for surgical and veterinary surgical use which is substantially free from the disadvantages of the above mentioned processes known in the artO The process according to the invention described below is dis tinguished ln partlcular by the following advantages:

1. The material is highly permeable to X-rays so that X-ray photographs can be taken through the bandage without any shadow;
2. the bandages required for producing a given supporting effect are much lighter than LeA 17,557 -2-l 1~0519 the known plaster of Pari.s bandageR providing the same effect, the saving in weight being up to about 80%;

3. the bandages are resistant to water;

4. the bandages attain weight bearing strength after only about 10 to 15 minutes;

5. the heat of reaction produced during hardening of the bandage is slight compared with that of conventional plaster of Paris bandages;

6. both application of the bandaaes and their removal after completion of the healing process are extremely simple and clean;

7. the risk of skin irritation due to bacteria or molds is much smaller than in known plaster of Paris bandages:

8. no apparatus is required for applying the bandage;

9. the bandages according to the invention have excellent permeability to air and hence breath-ing activity.
The present invention relates to a process for pro-ducing~a supporting bandage for surgical or veterinary surgical use comprising covering the part of the body which is required to be supported with an air-permeable~dressing and then applying a self-hardening bandage over this dressing, characterized in that self-hardening bandage comprises strips cf air-permeable, flexible fabric impregnated and/or coated with about 50 to 300/ by weight, based on the uncoated fabric, of an isocyanate prepolymer which contains free isocyanate groups and is based on at lea~-one ar~mati~~Fcl~lsn--cyanate and at least one polyol, containing tertiary amino nitrogen, the prepolymer having an isocyanate content of about 5 to about 30/O by weight and a .,..~
3 ~

l 16~519 tertiary amine nitrogen content of about 0.05 to 2.5% by weight, the impregnated and/or coated fabric being soaked with water immediately before it is applied. Even the impregnation time is not critical, kneading in water for 3 to 5 seconds is sufficient. Due to the short hardening time storage in water preferably should not exceed 2 minutes.
The present invention also relates to lengths of band-aging material which comprise pieces of flexible, airpermeable fabric coated and/or impregnated with about 50 to 30~h by weight, based on the uncoated fabric, of an isocyanate prepolymer which contains free isocyanate groups and is based on at least one aromatic polyisocyanate, and at least one polyol, containing tertiary amino nitrogen atoms, the isocyanate polymer having an isocyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.
To carry out the process according to the invention, the part of the body which is required to be supported is first covered with an air permeable, unimpregnated dressing. Suit-able materials for this dressing include, for example, porouspaper, non-woven webs or textile fabrics. The materials used for this dressing preferably have only a limited hydrophilic character. Non-woven polyester or polypropylene fabrics, for example, are therefore particularly suitable.
When the affected part of the body has been covered with the unimpregnated dressing, a bandage according to the invention which has previously been saturated with water is wound over it. This saturation with water of the bandaging material used according to the invention is carried out immediately before application of the bandage, for example, .~ ~

t ~6~9 by immersing it in water.

The bandaging materials according to the invention are fle~ihle, air-permeable fabrics having a weight per unit area of from about 20 to lOOOg/m2, preferably about 30 to 500 g/m , which are impregnated with certain isocyanate prepolymers.
The basic ~abric of the bandaging material is preferably a textile. Suitable fabrics for this purpose include, for example, the following:

tl) Woven, knitted or warp knitted textile fabrics having a weight of about 20 to 200 g/m , preferably about 40 to lO0 g/m and a thread count of preferably about 2 to 20 threads per centimeter in the longitudinal and transverse direction. The woven or knitted textile fabric may be produced from any natural or synthetic yarn, but it is preferred to use fabrics made of mixed yarns containing both hydrophobic filaments or fibers with a high elastic modulus (for example polyester) and hydrophilic natural or synthetic filaments or fibers (for example cotton or polyamide).

(2~ Wove~ knitted or warp knitted glass fiber fabrics weighing from about 60 to 500 g/m2, preferably about lO0 to 400 g/m2 and having a thread count of preferably about 2 to 20 per centimeter in the longitudinal and transverse direction. Glass fiber fabrics which have been treatedwith a hydrophilic sizing agent are preferred.

(3) Bonded or non-bonded or stitched non woven~
based LeA 17,557 -5-- 1 16~519 on inorganic and preferably organic fibres and having a weight of about 30 to 400 g/m ~ preferably about 50 to 200 g~m2.
! For producing stiff bandages according to the invention .j in the form of shells or splints, it is also suitable to use textile materials (preferably non-wovens) of the kind mentioned above weighing up to about 1000 g/m2.
~: The woven, knitted or warp knitted fabrics mentioned under paragraph (1) above are particularly preferred.
Isocyanate prepolymers suitable for impregnating the , flexible fabrics mentioned above as examples include in parti-cular those which have from about 5 to 30% by weight, prefer-~; ably about 10 to 25% by weight, of aromatically bound iso-cyanate groups and about 0.05 to 2.5% by weight, preferably about 0.1 to 1.5% by weight, of tertiary amino nitrogen atoms.
`. Furthermore, suitable choice of the viscosity of the starting materials used for preparing the isocyanate prepolymers ensures that the prepolymers have a viscosity of from about 5000 to 50,000 cP at 25C, preferably about 10,000 to 30,000 cP at 25C.
The preparation of the isocyanate prepolymers is carried out in known manner, and in particular by reacting excess ,' quantities of aromatic polyisocyanates with polyols which con-tain tertiary amino nitrogen atoms, preferably at an NCO/OH-ratio of between 2:1 and 15:1.
The aromatic polyisocyanates used may be any of the aromatic polyisocyanates known in polyurethane chemistry which have been described, for example, in "Polyurethanes, Chemistry and Technology", Part I, Interscience Publishers (1962) or in "Kunststoff-Handbuch`', Volume VII, Polyurethane, l 1 6~

Carl Hanser Verlag, Munich (1966). The following are preferre~
2,4-diisocyanatotoluene or 2,6-diisocyanatotoluene or isomeric mixtures thereof; 4,4'-diisocyanatodiphenylmethane and 2,4'-diisocyanatodiphenylmethane and mixtures of these isomers which may contain small quantities of 2,2'-diisocyanatodiphenylmethane, or any mixtures of the above mentioned polyisocyanates or poly-isocyanate mixtures which can be obtained by the phosgenation of aniline-formaldehyde condensates and which contain higher nuclear diphenylmethane polyisocyanates in addition to 2,2'-2,4'- and 4,4'-diisocyanatodiphenylmethane. The last mentioned diphenylmethane polyisocyanate mixtures are particularly preferred.

The following are examples of suitable polyols con-taining tertiary amino nitrogen atoms:

(1) Low molecular weight polyols having a molecular weight of from about 105 to 300 which contain tertiary nitrogen atoms and are free from ether groups, e.g. N-methyl-diethanolamine, N-ethyl-. diethanolamine, N-methyl-dipropanolamine, tri-ethanolamine or tripropanolamine;
(2) polyester polyols having a molecular weight of from about 300 to 2000, preferably about 800 to 1500, containing tertiary nitrogen atoms, which polyester polyols can be obtained by the reaction of polybasic acids with amino alcohols of the kind mentioned in (1) above as examples, if desired together with poly-hydric alcohols which are free from nitrogen.
: Suitable polybasic acids include, for example~
adipic acid, phthalic acid and hexahydrophthalic - acidO Suitable nitroge~ free polyhydric alcohols LeA 17,557 -7-1 ~60519 for the preparation of the polyesters include, for example, ethyle~e glycol, tetramethylene glycol, hexamethylene glycol and trimethylol-propane~
~3) Polyether polyols with tertiary amino nitrogen atoms having a molecular weight of from about 300 to 2000, preferably about 800 to 1500, which can be obtained in known manner by the alkoxylation of nitrogen containing starting compounds. Suitable starting compounds of this kind include, for example, ammonia, the amino alcohols mentioned in (1) above as examples and amines containing at least two-NH-bonds, e.g. ethylene diamine, aniline and hexamethylene-diamine. Suitable alkylene oxides for the preparation of the polyethers include, for example, ethylene oxide and propylene oxide.
Propoxylation products of the above mentioned nitrogen containing starting materials are particularly preferred.

coating and/or Any method may be used for/impregnating the bandaging materials used in the process according to the invention with the above mentioned isocyanate prepolymers. Conventional apparatus or devices may be used, for e~ample the bandages may be coated by means of doctor coat wlpers or impregnated and subsequently squeezed off on rollers or centrifuged or they may be sprayed with ff~isocyanate prepolymer.-The prepolymer may be usedeither solvent-free or as a solution. In the case of a solution, the preferred solvents are volatile solvents such as methylene chloride~ acetone, methyl ethyl ketone9 chloroform, THF, ethyl acetate 7 chlorobenzene and DMF.
LeA 17,557 -8-1 1 6~5~9 Pre~erably the weight per unit area, density of mesh o~ the flexible support and quantity of isocyanate prepolymer applied within the ranges specified above are chose~ so that only the fibers of the fabric become coated with the impregnating agent while gaps between the fibers are preserved to ensure the necessary porosity to air.

If auxiliary solvents have been used, the impregnated substrate is subsequently freed from them, for e~ample, by a vacuum treatment. After impregnation, the resulting bandaging materials according to the invention may be stored in sealed containers in the absence of moisture. They are preferably stored as rolls or folded flat in airtight metal containers, for example aluminum containers. Sealed bags made of poly-ethylene coated aluminum foils or moisture sealed aluminum tins are particularly suitable for storing the bandages according to the invention.

One of the advantages of the bandaging materials according to the invention, compared with the bandaging materials according to ~erman Offenlegungsschrift No. 2,353,212 is that when packed airtight as described above they can be stored under normal conditions.

Whenever the bandaging materials are required for the process according to the invention, they can be removed from the container a~ld impregnated with water.
The thicknoss of the supporting bandage (e.g. splint or ca~t)~ormed by the process according to the invention depends on the surgical requirements and is generally between about 3 and 10mm. The bandaging materials according to the invention may be used in the process according to the invention both for ~orming supporting bandages or casts by winding the strips o~ material around the parts of the body which require LeA 17,557 -9 ~ 1 6~519 support or they may be used as flat folded bandages for form~
ing shells or splints.

The ba~daging materials may be colored, for example, by the addition of pigments or dyes to the isocyanate pre-polymers. To increas~ the rigidity of the supporting band-ages formed according to the invention, inorganic additives which may be chemically inert or capable of hardening under the action of water may be added to the isocyanate prepolymers used for lmpregnating the bandaging materials, but the use of such additives is generally unnecessary due to the excellent mechanical properties of the supporting bandages obtained by the process according to the invention.
Suitable additives would be, for example, chalk, glass fibers or plaster of Paris.

The invention is further illustrated, but is not intended to be limited by the following examples in which all parts and percentages are by weight unless otherwise specified.

LeA 17,557 -10-l 1 6~519 EXAMPLES

~XAMPLE 1 /

A strip of bandage gauze made of bleached cotton 12 cm in width and 4 m in length and having a weight of 31 g/m2 and a thread count of 11 threads per cm in the longitudinal direction and 8 threads per cm in the trans-verse direction of the woven fabric is impregnated with 24 g of an isocyanate prepolymer obtained from a) a phosgenation product of an aniline-formaldehyde condensate having an isocyanate group content of about 30% by weight and a viscosity of 200 cP at 25C and b) a trihydroxypolyether obtained by propoxylation of triethanolamine and having an OH number of 146 and a viscosity of 1200 cP/25C in a ratio by weight of a:b = 3:1 (tertiary N: 0.3% by weight; free isocyanate group ~5 content: 18.7~ by weight; viscosity: 21,300 cP at 25C) on impregnating rollers with stringent exclusion of atmospheric moisture (dew point below -50C), and the impregnated gauze is wound on a core of polyethylene and sealed into a bag made of a three-layered laminate of polyester, aluminum and poly-ethylene equipped with a sealing edge.

When it has been stored for one week at about 25C r the impregnated bandaglng material is removed from its package, dipped in water at about 25C for 3 to 5 seconds and lightly kneaded. It is then wound within 3 minutes around a tubular body having an internal diameter of 42 mm and a length of about 12 cm.

The supporting bandage hardens within a further 5 minutes with slight evolution of heat (ma~imum surface tem-perature 35C) to form a stable, solid structure which is LeA 17,557 -11-.

l ~ 6~19 capable of bearing loads and has excellent bonding between the layers.

.

30 impregnated strips of bandaging material are prepared by the process described in Example 1 and tested for use after storage at about 25C for 3, 6 and 9 nths.
In the bending test (width of unsupported material 40 mm, maximum bending load 50 kp), the test samples obtained as described in Example 1 show a maximum deviation of the deformation due to load of +10%, which is within the range of de~iations due to manufacture found in such hand finished test samples. No fracture of the test samples under load occurred up to the maximum load.

The process described in Example l was repeated but instead of the 4 m long strip of bandage gauze, a 2 m long strip of warp knitted fabric (width lO cm) made of a mixed yarn of 67% polyester fibers and 33% cotton fibers and having a weight of 97 g/m2 and a thread count of 4 threads per cm in the longitudinal direction and lO threads per cm in the transverse direction was used. The ratio by weight of the isocyanate prepolyme~ described in Example l to the weight of fabric was 1.4:1. A sample prepared by the process according to Example l hardened within 6 to 7 minutes and in the mechanical test it showed the same rigidity as a sample produced from twice the length of fabric by the method described in Example l.

A strip of bandage gauze 12 cm in width produced from a mixed yarn of 40~ cotton and 60% viscose and weighing LeA 17,557 -12-l ~ 6051~

30 g/m and having a thread count of 12 threads per cm in the warp and 8 threads per cm in the weft is impregnated with 25 g of the isocyanate prepolymer described in Example 1 in the form of a solution in methylene chloride (ratio by weight of prepolymer/solvent = 1/1) under moisture free conditions, and the solvent was removed by an oil pump vacuum. The resin impregnated bandaging material was pack-aged as in Example 1 and stored for about one month at about 25C. The package was opened at the end of this time and a test sample is produced as in Example 1. The setting time and strength of the sample are similar to those of the sample obtained in Example 1.

EXAMPL_ 5 45 strips of bandaging material were prepared and packaged as in Example 4. Over a period of three months, the strips were used in clinical tests for preparing surgical supporting bandages or casts on the upper and lower extremities of patients with fractures of the long bones. The dressing used under the bandages was a polyester fleece or cotton wadding about 0.4 cm in thickness. The bandages hardened within a maximum of 10 minutes and were load bearing after only one hour.

The supporting bandages could be applied without soiling the surgery and could be exactly modelled. There was no need to remove the bandages for X-ray examination of the fracture since they caused no shadow on X-ray films.
They were radiologically practically invisible.

The bandages were removed with the aid of the usual tools used for plaster casts (plaster shears, oscillating saw).

LeA 17,557 -13-l l 60519 The bandages without exception produced very little dust compared with plaster castsO ~11 the patients found the very low weight of the bandages and the porosity to air extremely pleasant.

The condition of the skin areas which had been covered by the bandages was extremely satisfactory in all cases. No allergic reactions were observed.

Strips of woven glass fiber fabric 1 m in length and about 10 cm in width and weighing 285 g/m2 and having a thread count of 20 threads per cm in the warp and 6 threads per cm in the we~t were impregnated with the isocyanate pre-polymer described in Example 1 by the process according to Example 4. The quantity of prepolymer applied was 150 g/m .
Tubular test samples having the dimensions described in Example 1 were prepared by hand as in Example 1 and tested for bending. No fracture could be produced under a load of 50 kp. The maximum sagging obtained under the test conditions of Example 2 was 4 mm.

A striE? of glass silk fabric 2.3 m in length and

10 cm in width and having a thread count of 20 threads per cm in the warp and ~ thread~ per cm in the weft and weighing 290 g/m was impregnated by the process described in Example 4 with 69 g of the prepolymer described in Example 1. The impregnated length of fabric was then folded to a length of about 8 cm and packed airtightly into a tin under exclusion of moisture. When the packaging material was removed from its package after several months of storage~ it showed no LeA 17,557 -14-l ~ 6~19 signs of change. It was placed in water at a temperature of 20C for about 2 minutes and then spread out on a poly-ethylene foil to form six layers of equal length placed above one another~ After about 3 minutes~ the viscosity of the PU
resin applied to the fabric increased sharply with moderate xise in temperature. While in this condition, the stack of bandaging material was applied to the forearm of a patient to form a supporting half shell for the wrist and forearm.
The hardening reaction was substantially completed after a further two minutes. The dimensionally stable half shell was then placed inside a circular stiffening bandage for added rigidity.

EXP~PLE 8 _. _ Strips of a st~hed non-~woven of polyester fibers measuring 10 x 25 cm in width and length and about 4 mm in height and weighing 820 g/m2 were impre~nated with 240% b~ weight, based on the weight of the textile, of the PU prepolymer described in Example 1 by the method of solution impregnation described in Example 4. The impregnated strips were dipped in water at a temperature of about 40C for about one minute and used immediately for modelling a half shell on a human forearm after the usual application of a dressing to the skin. The bandage had hardened substantially completely after about 5 minutes.

The case obtained in this way was perforated mechan-ically to make it permeable to air and used as surgical forearm splint.

E~AMPLE 9 .

The strips of bandaging material specified in Example LeA 17,557- -15-l 1 6~519 3 were impregnated by the method of solution impregnation described in Example 4 with an isocyanate groups containing pre-polymer obtained from a) a phosgenation product of an aniline-formaldehyde condensate having an isocyanate group content of about 30~ by weight and a viscosity of 100 cP at 25C and b) a polyether obtained by propoxylation of ethylene diamine and having a molecular weight of il40 and an OH
number of 196, in proportions by weight of a:b = 4:1 (viscosity of the prepolymer 15,400 cP at 25C; free isocyanate content 20.4~ by weight, tertiary nitrogen: 0.24% by weight)~

When the bandaging material was made up into test . . .
samples as described in Example 1, they hardened within about 8 minutes. }n the mechanical tests, the samples were found to have exceptlonally high impact strengths.

.

Numerous strips of bandaging material were prepared for use as stiffening bandages by the process according to Example 4 and made up into test samples. The samples were stored in groups of 4 (length of fabric 4 m, width of fabric 10 cm) in 1 liter of twice distilled water for 4 hours at 23C and 2 hours a~ 50C, and the aqueous extracts were examined for thelr carbon content after filtration. The carbon content was found to be between about 0.002 and 0.007 by weight, showing that the hardened bandages release practically no organic material when moist.

Strips of bandaging material con~orming to the speci~icationsgiven in Claim 1 were prepared by the process according to Example 1 and made up into test samples as LeA 17,557 -16-1 ~60519 described. Some of the test samples weretested for their flexural strength and breaking strength after about 24 hours~
Another portion of the test samples were stored in water at about 20C ~ox 2 hours, dried and then tested under loads of up to a maximum of 50 kp ~or comparison with the test samples mentioned above. The decrease in strength after storage in water was insignificant within the limits of statistical error. This indicates that showers or baths can be taken when wearing the supporting bandage according to the invention.

~ .

A cotton bandage gauze 12 cm in width conforming to the specifications given in Example 1 was impregnated by the process described in Example 4 with an isocyanate prepolymer obtained from a mixture of 4,4'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate (proportions by weight 1:1.5) and a propoxylated triethanolamine having a molecular weight of about 1200 and an OH number of 146 in proportions by weight of the diisocyanates to the propoxylated triethanolamine of 1.25:1, in a manner analogous to the process of Example 1. The prepolymer contained about 12%
of free isocyanate groups and had a viscosity of l9,000 cP
at 25C.

Test s<~mples prepared in a manner analogous to Example 1 were completely hardened after only 5 minutes, had sufficient mechanical strength for surgical use and were highly permeable to air and moistureO

_ A strip of bandaging fabric 10 cm in width and 4 m LeA 17,557 -17-~ 1 8~519 in length manufactured from a mixed yarn of 65% polyester and 35~ cotton and having a weight of 60 g/m2 and a thread count of 12 threads per cm in the warp and 8 double threads per cm in the weft was impregnated with about 160~ by weight, based on the weight of the textile, of the isocyanate pre-polymer described in Example 12, and sealed into a poly-ethylene coated aluminum bag with sealed edge. After 9 months in storage at an average temperature of 23C, the bandaging fabric was used for preparing a test sample as in Example 1.
When the impregnated fabric was made up into a test sample and mechanically tested, no significant differences in properties were found between test sa~ples of ~reshly prepared bandaging material and the above described test samples.
.

Strips of tubular knitted fabric 50 cm in Length and 10.5 cm in width when laid out flat made of untextured polyacrylonitrile yarn and having an open mesh of about 1 mm2 and a weight of 238 g/m2 ~when double) were impregnated each with 12 g of the prepolymer described in Example 1 by the method according to Example 4 and made up into test samples of the kind descxibed in Example 1, using the tubes as double layered bandaging fabric. The hardening time was approximately 7 minutesO The test samples had good breathing activity and excellent bonding between the layers so that the hardened bandages could not be unwound without destroying the textile structure.

Numerous strips of bandaging fabric 4 m in length conforming to the specifications given in Example 13 were LeA 17,557 -18-l l 6~19 impregnated with the PU prepolymer described in Example 1 by the method according to Example 4. The quantities of prepolymer applied were 104,156 and 208% by weight, based on the weight of the dry, unimpregnated fabric.

The base of a transparent tube 30 cm in length and 0.9 cm in diameter was glued to the test samples and the outflow time or a water column 10 cm in height was measured.

The outflow time through fabrics which had been impregnated with 104% by weight and 156~ by weight was approximately 3 seconds; when the fabrics were impregnated with 208~ by weight, the outflow time increased to approxi-mately 10 minutes.

This test demonstrates the excellent breathing . .
activity of bandaging fabrics which have been impregnated with the optimum amount of 150 to 160~ by weight. In the case of the least impregnated fabric ~104%), the test sample was destroyed in the bending test under a load of only 35 kp while more highly impregnated test samples remainedcompletely intact under a load of 50 kp and were deformed by only about 2 mm.

EXAMPLE 16 (Comparison Example) Numerous strips of bandage gauze described in Example 4 were impregnated each with 25 g of trimeric hexamethylene diisocyanate by the method indicated in Example 4. The impregnated bandaging fabrics were kneaded for 10 seconds in water at 20C and made up into tubular test samples having a length of about 12 cm and an internal diameter of 42 mm. The time required for complete hardening at about 23C was about ~8 hours.

LeA 17,557 19-1 ~6~9 In another ~est series, 0.3~ by weight of tertiary nitrogen in the form of N,N-dimethylaniline was added as activator to the polyisocyanate~ The test samples obtained in this series showed no significant reduction in the hardening time but had an unpleasant odor due to free amine.

In another test series, N,N'-dimethylaminoethane was used as activator instead of N,N-dimethylaniline. Test samples prepared from the bandaging fabrics in this series did not harden significantly more rapidly than the starting material. These were also found to have an unpleasant odor.

EXAMPLE 17 (Comparison Example) Strips of bandage gauze conforming to the specifica-tion given in Example 4 were impregnated with an isocyanate prepolymer of a) a phosgenation product of an aniline-formalde-hyde condensate having an isocyanate group content of about30% by weight and a viscosity of 100 cP at 25C and b) a polypropylene glycol polyether which had been started with moist glycerol and had an OH number of 159, a molecular weight of 920 and a functionality of 2.62 by the method described in Example 4. The ratio by weight of a:b was 3:1. The prepolymer was found to have a viscosity of 12,600 cP at 25C and to contain 20.4% by weight of free isocyanate groups~

After storage in sealed polyethylene-aluminium-polyester bags, the strips of bandaging fabric were made upinto test samples by the method described in Example 1 and their hardening time was determined. This was in all cases more than 45 minutes, which indicated that the prepolymer system free from activator was unsuitable for use as surgical supporting bandage or cast~

LeA 17,557 -20-

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Process for the preparation of a supporting bandage for surgical or veterinary surgical use comprising covering the part of the body which requires support with an air-permeable dressing and then applying a self-hardening bandage, characterized in that the self-hardening bandage comprises strips of air-permeable, flexible bandaging fabric which have a weight per unit area of from about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate pre-polymer which contains free isocyanate groups and has been prepared from aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms, the prepolymer having an iso-cyanate content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, the impregnated and/or coated bandaging fabric being soaked with water immediately before its use.

2. Strips of bandaging material suitable for surgical or veterinary surgical use, characterized in that they comprise flexible, air-permeable pieces of fabric having a weight per unit area of from about 20 to 1000 g/m and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer based on aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms, the isocyanate prepolymer having an isocyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

3. The bandaging material of claim 2, wherein the air-permeable pieces of fabric have a weight per unit area of from about 30 to 500 g/m2.

4. The bandaging material of claim 2, wherein the iso-cyanate prepolymer has a viscosity of from about 5000 to 50,000 cP at 25°C.

5. The bandaging material of claim 2, wherein the iso-cyanate prepolymer has an isocyanate group content of about 10 to 25% by weight and a tertiary amino nitrogen content of about 0.1 to 1.5% by weight.

6. The bandaging material of claim 2, wherein in the impregnation and/or coating of said isocyanate prepolymer, the prepolymer is in a solvent free form.

7. The bandaging material of claim 2, wherein in the impregnation and/or coating of said isocyanate prepolymer, the prepolymer is in a solution form.

8. The bandaging material of claim 2, wherein the iso-cyanate prepolymer is based on aromatic polyisocyanates which are the phosgenation product of aniline-formaldehyde con-densates and polyether polyols having tertiary amino nitrogen atoms and having a molecular weight of from about 300 to 2,000.

9. A process for the preparation of a supporting bandage comprising:
(A) applying an air-permeable dressing to a structural unit which needs support, and (B) applying a self-hardening bandage to the air-permeable dressing, said self-hardening bandage comprising strips of air-permeable flexible bandaging fabric which have a weight per unit area of from about 20 to 1000 g/m and which have been impregnated and/or coated with about 50 to 300% by weight , based on the uncoated fabric, of an isocyanate prepolymer, said isocyanate prepolymer (1) being based on aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms, (2) having an isocyanate group content of about 5 to 30% by weight, (3) having a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, and (4) having a viscosity of from about 5000 to 50,000 cP at 25°C.

10. A medical supporting material comprising flexible, air-permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer based on aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms, the isocyanate prepolymer having an isocyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

11. A medical supporting material enclosed in a moisture-impervious container comprising flexible/ air-permeable pieces of fabric, which have a weight per unit area of about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer based on aromatic polyiso-cyanates and polyols containing tertiary amino nitrogen atoms, the isocyanate prepolymer having an isocyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen con-tent of about 0.05 to 2.5% by weight.

12. Process for the preparation of a rigid supporting bandage for surgical or veterinary surgical use which attains weight bearing strength in less than about fifteen minutes comprising covering the part of the body which requires support with an air-permeable dressing and then applying a self-hardening bandage, characterized in that the self-hardening bandage comprises strips of air-permeable, flexible bandaging fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer which contains free isocyanate groups and has been prepared from aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms, the prepolymer having an isocyanate content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, the impregnated and/or coated bandaging fabric being soaked with water immediately before its use.

13. Strips of bandaging material suitable for surgical or veterinary surgical use, characterized in that they comprise flexible, air-permeable pieces of fabric having a weight per unit area of about 20 to 1000 g/m2 and which have been impre-gnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer based on aro-matic polyisocyanates and polyols containing tertiary amino nitrogen atoms, the isocyanate prepolymer having an isocyan-ate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, said bandaging material being capable of attaining weight bearing strength in less than about fifteen minutes after being soaked with water.

14. The bandaging material of claim 13, wherein the air-permeable pieces of fabric have a weight per unit area of from about 30 to 500 g/m2.

15. The bandaging material of claim 13, wherein the iso-cyanate prepolymer has a viscosity of from about 5000 to 50,000 cP at 25°C.

16. The bandaging material of claim 13, wherein the iso-cyanate prepolymer has an isocyanate group content of about 10 to 25% by weight and a tertiary amino nitrogen content of about 0.1 to 1.5% by weight.

17. The bandaging material of claim 13, wherein in the impregnation and/or coating of said isocyanate prepolymer, the prepolymer is in a solvent free form.

18. The bandaging material of claim 13, wherein in the impregnation and/or coating of said isocyanate prepolymer, the prepolymer is in a solution form.

19. The bandaging material of claim 13, wherein the isocyanate prepolymer is based on aromatic polyisocyanates which are the phosgenation product of aniline-formaldehyde condensates and polyether polyols having tertiary amino nitrogen atoms and having a molecular weight of from about 300 to 2,000.

20. A process for the preparation of a rigid supporting bandage which attains weight bearing strength in less than about fifteen minutes comprising (A) applying an air-permeable dressing to a structural unit which needs support, and (B) applying a self-hardening bandage to the air-permeable dressing, said self-hardening bandage comprising strips of an air-permeable, flexible bandaging fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer, said isocyanate prepolymer (1) being based on aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms, (2) having an isocyanate group content of about 5 to 30% by weight, (3) having a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, and (4) having a viscosity of from about 5000 to 50,000 cP at 25°C wherein said self-hardening bandage is soaked with water immediately before its application.

21. A medical supporting material which attains weight bearing strength in less than about fifteen minutes after being soaked with water comprising flexible,air-permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer based on aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms, the isocyanate prepolymer having an isocyanate group content of about 5 to 30%
by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

22. A medical supporting material which attains weight bearing strength in less than about fifteen minutes after being soaked with water enclosed in a moisture free and moisture impervious container comprising flexible, air-permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer based on aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms, the isocyanate prepolymer having an isocyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

23. A process for the preparation of a rigid supporting bandage for surgical or veterinary surgical use which attains weight bearing strength in between about 5 and 15 minutes comprising covering the part of the body which requires support with an air-permeable dressing and then applying a self-hardening bandage wherein the self-hardening bandage is prepared by impregnating or coating solvent free strips of air-permeable,flexible bandaging fabric having a weight per unit area of about 20 to 1000 g/m2 with about 50 to 300% by weight, based on the weight of the untreated fabric, of a solvent free isocyanate prepolymer which contains free isocyanate groups and has been prepared from aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms at an NCO to OH ratio of between about 2:1 and 15:1, the prepolymer having an isocyanate content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, the self-hardening bandage being soaked with water immediately before its use.

24. A medical supporting material which attains weight bearing strength in between about 5 and 15 minutes after being soaked with water enclosed in a moisture free and moisture impervious container comprising substantially solvent free flexible, air-permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been coated or impregnated with about 50 to 300% by weight, based on the weight of untreated fabric, of an isocyanate prepolymer, said prepolymer (A) being the reaction product of aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms prepared with an NCO to OH ratio of between 2:1 and 15:1, (B) having an isocyanate group content of 5 to 30% by weight, and (C) having a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

25. The medical supporting material of Claim 24 wherein the polyol containing the tertiary amino nitrogen is the ethoxylation or propoxylation product of ammonia, an amine or an amino alcohol.

26. A medical supporting material which attains weight bearing strength after being soaked with water enclosed in a moisture free and moisture impervious container comprising substantially solvent free flexible, air-permeable pieces of fabric, which have a weight per unit area of about 20 to 1000 g/m and which have been coated or impregnated with about 50 to 300% by weight, based on the weight of untreated fabric, of an isocyanate prepolymer, said prepolymer (A) being the reaction product of aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms prepared with an NCO to OH ratio of between 2:1 and 15:1, (B) having an isocyanate group content of 5 to 30% by weight, and (C) having a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

27. A medical supporting material which attains weight bearing strength in less than about fifteen minutes after being soaked with water enclosed in a moisture free and moisture impervious container comprising substantially solvent free flexible, air-permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m and which have been coated or impregnated with about 50 to 300% by weight, based on the weight of untreated fabric, of an isocyante prepolymer, said prepolymer (A) being the reaction product of aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms prepared with an NCO to OH ratio of between 2:1 to 15:1, (B) having an isocyanate group content of 5 to 30% by weight, and (C) having a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

28. A medical supporting material which hardens substantially completely in between about five and fifteen minutes after being soaked with water enclosed in a moisture free and moisture impervious container comprising substantially solvent free flexible, air-permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been coated or impregnated with about 50 to 300% by weight, based on the weight of untreated fabric, of an isocyanate prepolymer, said prepolymer (A) being the reaction product of aromatic polyisocyanates and polyols containing tertiary amino nitrogen atoms prepared with an NCO to OH ratio of between 2:1 to 15:1, (B) having an isocyanate group content of 5 to 30% by weight, and (C) having a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

29. Process for the preparation of a rigid supporting bandage for surgical or veterinary surgical use which attains weight bearing strength in from five to about fifteen minutes comprising covering the part of the body which requires support with an air-permeable dressing and then applying a self-hardening bandage, characterized in that the self-hardening bandage comprises strips of air-permeable, flexible bandaging fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer composition which contains free isocyanate groups and has been prepared from at least one aromatic polyisocyanate and at least one polyol, and which contains tertiary amino nitrogen atoms, the composition having an isocyanate content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, the impregnated and/or coated bandaging fabric being soaked with water immediately before its use.

30. Strips of bandaging material suitable for surgical and veterinary surgical use, characterized in that they com-prise flexible, air-permeable pieces of fabric having a weight per unit area of about 20 to 1000 g/m and which have been impregnated and/or coated with about 50 to 300%
by weight, based on the uncoated fabric, of an isocyanate prepolymer composition based on at least one aromatic polyisocyanate and at least one polyol, and containing tertiary amino nitrogen atoms, the isocyanate prepolymer composition having an isocyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, said bandaging material being capable of attaining weight bearing strength in from five to about fifteen minutes after being soaked with water.

31. The bandaging material of claim 30, wherein the iso-cyanate prepolymer has a viscosity of from about 5000 to 50,000 cP at 25°C.

32. The bandaging material of claim 30, wherein the iso-cyanate prepolymer composition has an isocyanate group con-tent of about 10 to 25% by weight and a tertiary amino nitrogen content of about 0.1 to 1.5% by weight.

33. The bandaging material of claim 30, wherein in the impregnation and/or coating of said isocyanate prepolymer composition, the composition is in a solvent free form.

34. The bandaging material of claim 30, wherein in the impregnation and/or coating of said isocyanate pre-polymer composition, the composition is in a solution form.

35. The bandaging material of claim 30, wherein the iso-cyanate prepolymer is based on aromatic polyisocyanates which are the phosgenation product of aniline-formaldehyde condensates and polyether polyols and having a molecular weight of from about 300 to 2,000.

36. A process for the preparation of a rigid supporting bandage which attains weight bearing strength in from five to about fifteen minutes comprising:
(A) applying an air-permeable dressing to a structural unit which needs support, and (B) applying a self-hardening bandage to the air-permeable dressing, said self-hardening bandage comprising strips of an air-permeable, flexible bandaging fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer composition, said isocyanate prepolymer composition (1) being based on at least one aromatic polyisocyanate and at least one polyol and containing tertiary amino nitrogen atoms, (2) having an isocyanate group content of about 5 to 30% by weight, (3) having a tertiary amino nitrogen content of about 2.5% by weight, and (4) having a viscosity of from about 5000 to 50,000 cP at 25°C wherein said self-hardening bandage is soaked with water immediately before its application.

37. A medical supporting material which attains weight, bearing strength in from five to about fifteen minutes after being soaked with water comprising flexible air-permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer composition based on at least one aromatic polyisocyanate and at least one polyol, and containing tertiary amino nitrogen atoms, the isocyanate prepolymer composition having an iso-cyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

38. A medical supporting material which attains weight bearing strength in from five to fifteen minutes after being soaked with water enclosed in a moisture free and moisture-impervious container comprising flexible, air-permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer composition based on at least one aromatic polyisocyanate and at least one polyol, and contain-ing tertiary amino nitrogen atoms, the isocyanate prepolymer composition having an isocyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

39. A process for the preparation of a rigid supporting bandage for surgical or veterinary surgical use which attains weight bearing strength in between about 5 and 15 minutes comprising covering the part of the body which requires support with an air-permeable dressing and then applying a self-hardening bandage wherein the self-hardening bandage is prepared by impregnating or coating solvent free strips of air-permeable, flexible bandaging fabric having a weight per unit area of about 20 to 1000 g/m2 with about 50 to 300%
by weight based on the weight of the untreated fabric, of a solvent free isocyanate prepolymer composition which con-tains free isocyanate groups and has been prepared from at least one aromatic polyisocyanate and at least one polyol, and which contains tertiary amino nitrogen atoms at an NCO
to OH ratio of between about 2:1 and 15:1, the prepolymer composition having an isocyanate content of about 5 to 30%
by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, the self-hardening bandage being soaked with water immediately before its use.

40. A medical supporting material which attains weight bearing strength in between about 5 and 15 minutes after being soaked with water enclosed in a moisture free and moisture impervious container comprising substantially solvent free flexible, air permeable pieces of fabric, which have a weight per unit area of about 20 to 1000 g/m2 and which have been coated or impregnated with about 50 to 300% by weight, based on the weight of untreated fabric, of an isocyanate prepolymer composition, said prepolymer composition a) being the reaction product of at least one aromatic polyisocyanate and at least one polyol, and containing tertiary amino nitrogen atoms, prepared with an NCO to OH
ratio of between 2:1 and 15:1, b) having an isocyanate group content of 5 to 30% by weight, and c) having a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

41. The medical supporting material of claim 40, wherein the tertiary amino nitrogen carries an oxyethyl or oxypropyl moiety.

42. A medical supporting material which hardens sub-stantially completely in between about five and fifteen minutes after being soaked with water enclosed in a moisture free and moisture impervious container comprising sub-stantially solvent free flexible, air permeable pieces of fabric having a weight per unit area of about 20 to 1000 g/m and which have been coated or impregnated with about 50 to 300°by weight, based on the weight of untreated fabric, of any isocyanate prepolymer composition, said prepolymer composition a) being the reaction product of at least one aromatic polyisocyanate and at least one polyol, and containing tertiary amino nitrogen atoms, prepared with an NCO to OH ratio of between 2:1 and 15:1, b) having an isocyanate group content of 5 to 30% by weight, and c) having a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

43. Process for the preparation of a rigid supporting bandage for surgical or veterinary surgical use which attains weight bearing strength in from five to about fifteen minutes comprising covering the part of the body which requires support with an air-permeable dressing and then applying a self-hardening bandage, characterized in that the self-hardening bandage comprises strips of air-permeable, flexible bandaging fabric which have a weight per unit area of about 20 to 1000 g/m and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer composition which contains free isocyanate groups and has been prepared from aromatic polyisocyanates and polyols and which contains tertiary amino nitrogen atoms, the composition having an isocyanate content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, the impregnated and/or coated bandaging fabric being soaked with water immediately before its use.

44. Strips of bandaging material suitable for surgical and veterinary surgical use, characterized in that they comprise flexible, air-permeable pieces of fabric having a weight per unit area of about 20 to 1000 g/m and which have been impregnated and/or coated with about 50 to 300%
by weight, based on the uncoated fabric, of an isocyanate prepolymer composition based on aromatic polyisocyanates and polyols and containing tertiary amino nitrogen atoms, the iso-cyanate prepolymer composition having an isocyanate group con-tent of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, said bandaging mate-rial being capable of attaining weight bearing strength in form five to about fifteen minutes after being soaked with water.

45. The bandaging material of claim 44, wherein the iso-cyanate prepolymer has a viscosity of from about 5000 to 50,000 cP at 25°C.

46. The bandaging material of claim 44, wherein the iso-cyanate prepolymer composition has an isocyanate group con-tent of about 10 to 25% by weight and a tertiary amino nitrogen content of about 0.1 to 1.5% by weight.

47. The bandaging material of claim 44, wherein in the impregnation and/or coating of said isocyanate prepolymer composition the composition is in a solvent free form.

48. The bandaging material of claim 44, wherein in the impregnation and/or coating of said isocyanate prepolymer composition, the composition is in a solution form.

49. A process for the preparation of a rigid supporting bandage which attains weight bearing strength in from five to about fifteen minutes comprising (A) applying an air-permeable dressing to a structural unit which needs support, and (B) applying a self-hardening bandage to the air-permeable dressing, said self-hardening bandage comprising strips of an air-permeable, flexible bandaging fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate pre-polymer composition, said isocyanate pre-polymer composition (1) being based on aromatic polyisocyanates and polyols and containing tertiary amino nitrogen atoms, (2) having an isocyanate group content of about 5 to 30% by weight, (3) having a tertiary amino nitrogen content of about 2.5% by weight, and (4) having a viscosity of from about 5000 to 50,000 cP at 25°C wherein said self-hardening bandage is soaked with water immediately before its application.

50. A medical supporting material which attains weight, bearing strength in from five to about fifteen minutes after being soaked with water comprising flexible air-permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer composition based on aromatic polyisocyanates and polyols and containing tertiary amino nitrogen atoms, the isocyanate prepolymer composition having an isocyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

51. A medical supporting material which attains weight bearing strength in from five to about fifteen minutes after being soaked with water enclosed in a moisture free and moisture-impervious container comprising flexible, air-permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m2 and which have been impregnated and/or coated with about 50 to 300% by weight, based on the uncoated fabric, of an isocyanate prepolymer composition based on aromatic polyisocyanates and polyols and containing tertiary amino nitrogen atoms, the isocyanate prepolymer com-position having an isocyanate group content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

52. A process for the preparation of a rigid supporting bandage for surgical or veterinary surgical use which attains weight bearing strength in between about 5 and 15 minutes comprising covering the part of the body which requires support with an air-permeable dressing and then applying a self-hardening bandage wherein the self-hardening bandage is prepared by impregnating or coating solvent free strips of air-permeable, flexible bandaging fabric having a weight per unit area of about 20 to 1000 g/m2 with about 50 to 300%
by weight, based on the weight of the untreated fabric, of a solvent free isocyanate prepolymer composition which contains free isocyanate groups and has been prepared from aromatic polyisocyanates and polyols and which contains tertiary amino nitrogen atoms at an NC0 to 0.05 ratio of be-tween about 2:1 and 15:1, the prepolymer composition having an isocyanate content of about 5 to 30% by weight and a tertiary amino nitrogen content of about 0.05 to 2.5% by weight, the self-hardening bandage being soaked with water immediately before its use.

53. A medical supporting material which attains weight bearing strength in between about 5 and 15 minutes after being soaked with water enclosed in a moisture free and moisture impervious container comprising substantially solvent free flexible, air permeable pieces of fabric, which have a weight per unit area of about 20 to 1000 g/m2 and which have been coated or impregnated with about 50 to 300% by weight, based on the weight of untreated fabric, of an isocyanate prepolymer composition, said prepolymer composition a) being the reaction product of aromatic poly-isocyanates and polyols and containing tertiary amino nitrogen atoms, prepared with an NCO to OH ratio of between 2:1 and 15:1, b) having an isocyanate group content of 5 to 30% by weight, and c) having a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.

54. The medical supporting material of claim 53, wherein the tertiary amino nitrogen carries an oxyethyl or oxypropyl moiety.

55. A medical supporting material which hardens sub-stantially completely in between about five and fifteen minutes after being soaked with water enclosed in a moisture free and moisture impervious container comprising sub-stantially solvent free flexible, air permeable pieces of fabric which have a weight per unit area of about 20 to 1000 g/m and which have been coated or impregnated with about 50 to 300% by weight, based on the weight of un-treated fabric, of any isocyanate prepolymer composition, said prepolymer composition a) being the reaction product of aromatic poly-isocyanates and polyols, and containing tertiary amino nitrogen atoms, prepared with an NCO to OH ratio of between 2:1 , and 15:1, b) having an isocyanate group content of 5 to 30% by weight, and c) having a tertiary amino nitrogen content of about 0.05 to 2.5% by weight.