JPS6037739B2 - Band-shaped support bandage material consisting of open-cell acetalized polyvinyl alcohol foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a band-like support bandage material comprising an open cell acetalized polyvinyl alcohol foam.

A proposal to process so-called porcine polyvinyl alcohol, optionally with the addition of pigments, into film-shaped dressing materials is already covered in West German Patent Specification No. 746,751. However, this type of ribbon material could only serve its purpose if the material could be successfully processed into a ribbon foam material with an open cell structure and thus a large active surface. Since such strip materials are known today and are commercially available, they are increasingly becoming popular as dressing materials, especially for the production of support dressings. Such support bandages are disclosed, for example, in West German Utility Model No. 753,594 and No. 1.
This is listed. The open cell acetalized polyvinyl alcohol foam has the properties of being relatively stiff in the dry state and exhibiting good bending strength.

When the foam is brought into contact with water, it absorbs approximately 500-1000% of its own weight in water within a short time, with some of this water remaining as capillary water in the open pores.
Most are chemically bonded and cause the material to swell. In this state, the foam material is soft, easily movable, and can be conveniently processed into a bandage depending on the type of strip fabric. The drying time of a dressing of this type depends, in addition to the degree of acetalization, inter alia on the layer thickness and on the temperature. In the case of foam material tapes to be used as support bandages, it is recommended to choose a degree of acetalization as high as possible and therefore quantitative acetalization. This is because only in this case the highest possible strength and hardness can be achieved. Experiments have shown that the drying time of open-cell foam strips made of polyvinyl alcohol acetalized with formaldehyde and thus formalized to a degree of acetalization of 100% increases in proportion to the thickness of the strip material. did. The following values were obtained for specimens dried under air circulation at room temperature: thickness of foam material drying time 15hi
n, 2 ribs 3 ribs hin
．． 3 sails, 49 hln, 4 willows, 6 enemy hin. 5 skin
75 min, this drying time is sometimes too long for the experimental use of strip foam materials as support bandages in the surgical and orthopedic fields.

It was therefore an object to provide a band-like support dressing material consisting of an open-cell acetalized polypinyl alcohol foam whose drying time is shortened without deteriorating other values, such as in particular hardness and stiffness. arise. According to the invention, this problem is achieved by depositing a hydrophobizing agent on the open cell surface of the foam material in an amount such that the foam material contains 2 to 8% by weight of the hydrophobizing agent. ,
or {by chemically modifying the b-form material molecule by introducing into the molecule a hydrophobic group selected from the lowest chain alkyl group, aryl group, or arylalkyl group having 5 to 20 C atoms. This can be solved by making it hydrophobic. In this case, the hydrophobizing agent is a silicone resin, melamine resin, acrylate resin or fluorinated acrylate resin. In this case, although such a superficially hydrophobicized polyvinyl alcohol acetal foam is clearly limited in its water absorption capacity, the foam is nevertheless desirable for the rapid and reliable application of bandages. It has been found that it is possible to soften and change the condition considerably and that the thus treated strip material subsequently requires a significantly reduced drying time. In order to produce superficially hydrophobized ribbon foam materials, dry or previously well-swollen ribbon foam materials can be prepared using suitable compositions and materials known in principle from the textile field. This can be carried out by immersion into a hydrophobizing solution containing the hydrophobizing agent as a pre-product, optionally other additives such as pigments and dyes, and condensation catalysts.

With a sufficiently vigorous kneading and kneading process, the liquid also penetrates into the open pores of the foam material, thus covering all active surfaces,
That is, it is ensured that the inner surfaces of the pores also leak.
After squeezing out the liquid, the thus pretreated strip is then first dried at an elevated temperature and finally the hydrophobizing agent is condensed by heating briefly to the condensation temperature. It has proven advantageous to select the concentration of the hydrophobizing group in such a way that the foam material contains 4 to 5% by weight of hydrophobizing agent in the dry state. However, used as a support bandage,
The idea of the present invention to shorten the drying time of open-cell acetalized polyvinyl alcohol foam strips by hydrophobicizing them is to not only hydrophobize the active surface of the foam material, but also to incorporate hydrophobic groups in the foam material molecules. This can also be carried out, for example, by introducing a long mirror alkyl group, aryl group or arylalkyl group having 5 to 20 C atoms and thereby chemically modifying the foam material. This treatment can be carried out when synthesizing the foam material and has the advantage that no subsequent post-treatment of the already striped foam material is necessary. Furthermore, foam materials that have been rendered hydrophobic by chemical modification are stable and retain their hydrophobicity virtually indefinitely. Finally, another advantage of hydrophobization by chemical modification is that in this way the degree of hydrophobization can be precisely adjusted. This is because the number of hydrophobizing groups per molecule of foam material can be adjusted precisely. For example, polyvinyl alcohol produced by saponifying polyvinyl acetate in a conventional manner may be at least partially acetalized with a long-chain aliphatic aldehyde or aromatic aldehyde having 5 to 20 C atoms. In this case it is also possible to use aldehyde mixtures, for example mixtures of the most chain aliphatic aldehydes, for example stearyl aldehyde, and formaldehyde. In this way, the desired amount of hydroxyl groups contained in polyvinyl alcohol is acetalized, that is, formalized, with formaldehyde, and approximately 20 to 40%
The remaining content of can be acetalized with stearyl aldehyde. The result is a soft foam with controlled hydrophobicity. It has been found that a strip of material consisting of acetalized polyvinyl alcohol foam, which has been hydrophobized in the manner described above, can be advantageously used for producing support bandages.

With the method described, the drying time mentioned at the beginning can be reduced to about 1'3, so that the following drying time is required:
Foam material thickness Drying time/side
5hln, 2nd side
1 hin, 3 hin
15hln, 4 ribs
22hin, 5th side
25 mln, it is not desirable to further shorten the drying time.

The reason is otherwise the so-called “open time” (of
This is because feneZeit) is significantly limited. “
"Open time" refers to the time during which a strip of material can be processed. If this time drops significantly below 5 minutes, it is generally felt that the dressing material hardens too quickly. It has been found that due to the hydrophobizing agent the bandage material can no longer be soaked in water at room temperature and elevated temperatures must be used.

For example, when impregnating band-shaped support dressings made from formalized voripinyl alcohol foam and whose surface is hydrophobized with melamine resin, 35 to 4000 g of water is preferably used for this purpose. do. A similar observation was made in the case of a band-shaped support bandage material whose surface was hydrophobized with silicone resin. On the other hand, it has been observed that chemically modified band support dressing materials can still be macerated in room temperature water, in which case a shortened drying time is still required. The present invention will now be described in detail with reference to some examples: Example 1 Polypynylic alcohol formal with a lotus-shaped cell of about 10 centimeters, length 150 centimeters and thickness 1 bar (molecular weight about 20,000: degree of acetalization 100%) ) was soaked by soaking it in cold water.

The foam material, which was removed by squeezing out the adhering capillary water, was soaked for about 5 minutes in a hydrophobizing bath of: Melamine resin 20 minutes Paraffin.
/Zirconium dioxide dispersion 75T zinc nitrate
7 Yusui
l000 [The solution was adjusted to pH 5-6 with 50% acetic acid before adding zinc nitrate, which acts as a catalyst.
It was adjusted to

At the end of the soaking period, the band was removed from the tube and squeezed to remove excess water. The band was then dried at approximately 85°C. After completion of drying, the residual moisture content was approximately 2%.
The band was then post-treated at 150 q○ for about 3 minutes, in which case condensation of the melamine resin occurred. The thus hydrophobized bands were swollen by treatment with 40 pm of hot tap water and squeezed to remove capillary water. The band sections in 10 skins were completely dried within 5 minutes by simply standing at room temperature without air movement, in which case the band sections regained their original hardness and strength.

From the remaining bands, arm bandages were made with up to two overlapping layers. The dressing thus obtained was completely dry in 12 minutes. Example 2 A band of the same chemistry and structure consisting of 100% formalized polyvinyl alcohol foam was swollen by immersion in water.

The foam material band from which the capillary water had been removed by squeezing was treated for about 5 minutes in a hydrophobizing bath with the following composition: silanol precondensate 100% zinc chloride.
10 Yusui
After 1 treatment, the excess liquid was squeezed out and the product was dried at about 10,000 °C.

During the drying process, condensation of the silanol resulted in a water-insoluble silicone resin. Subsequently, the obtained product was heated at about 40 pm.
water until all salts were removed, then rolled up into a roll of dressing material and packaged in a water-impermeable sheet. In this way it has been demonstrated that it is actually shelf stable for an arbitrarily long period of time. After two months, the package was opened and cut into 10 arc length pieces.

The pieces dried within 4 months by being left undisturbed at room temperature. An arm support bandage from the remaining fragment was applied to the arm.

Claims (1)

[Scope of Claims] 1. A band-shaped support bandage material comprising an open-cell acetalized polyvinyl alcohol foam, wherein the foam material (a) contains a hydrophobizing agent on the surface of the open cells of the foam material; (b) form material molecules containing long chain alkyl groups having from 5 to 20 C atoms;
Consisting of an open-cell acetalized polyvinyl alcohol foam, characterized in that it has been made hydrophobic by chemical modification by introducing hydrophobic groups selected from aryl or arylalkyl groups. Band-like support bandage material. 2. The hydrophobizing agent is a silicone resin, melamine resin, acrylate resin or fluorinated acrylate resin,
A band-shaped support bandage material according to claim 1. 3. The band-shaped support bandage material of claim 2, wherein the foam material contains 4 to 5% by weight of a hydrophobizing agent. 4. The foam material is produced by acetalizing polyvinyl alcohol foam at least in part with a long-chain aliphatic aldehyde having 5 to 20 carbon atoms or an aromatic aldehyde, claim 1. The band support bandage material described.