IE20090350U1 - Microwave technology - Google Patents

Abstract

ABSTRACT ’ energy transparent material wherein said apparatus and splint are separated from each other by a water-impermeable, heat-conducting membrane in the form of a septum or separate pouches for the splint or absorbent. The splint filrther comprises a layer of skin—contacting padding material which is carried on the polymer on the surface opposed to that adjacent the absorbent material.

Description

Thermoformable Support Products and Heating Means Therefor This invention relates to thermoplastic polymeric products used for supporting body portions the and to methods for the use thereof. Such products include splints, casts and braces for supporting limbs, the trunk or neck of an animal body. Herein such products are thermoformable can be heated to skin tolerant temperatures and moulded around the body portion to be treated. Herein these thermoformable products will be generally referred to as “splints” or “splinting products".

Splints usually comprise a layer or substrate of a thermoplastic polymeric material such as a polycaprolactone. The polymeric substrate may carry a layer of a padding material on its body facing surface.

In use the splint is heated until it is sufficiently pliable to be wrapped around and conform to the shape of the body portion to be treated. The splint is then allowed to cool and “set”.

Heating of the splint is conventionally carried out by immersion in a hot water bath.

However, there are several disadvantages to this method. Firstly, there is the danger of scalding to both the technician and patient from the hot water and secondly if padding material is attached to the polymer substrate it will become wet and, at the very least will be uncomfortable to the wearer until it dries out. Since the padding is likely to retain water, the risk of scalding the patient will be further increased. A third disadvantage is that the provision of facilities to house the water bath and its associated operation increases the cost of the treatment and limits the availability of the treatment to fixed locations.

Attempts to “dry heat” the splint in microwave ovens have been largely unsuccessful because it has been difficult to uniformly heat the product safely without creating hotspots which could burn the patient.

The present invention seeks to provide means for heating thermoplastic polymer splints, including splints bearing a skin-contacting padding layer, safely and uniformly, using heating apparatus which does not suffer from the disadvantages associated with the prior art hot water baths.

According to the present invention there is provided a packaged splinting product comprising a thermoformable polymeric splint in combination with a water laden absorbent material sealed in a water-impervious, heat-conducting pouch, wherein said material is adapted to permit microwave energy to enter and heat the contained water and wherein the pouch material is microwave transparent.

As used herein the combination of a water laden absorbent material sealed in a water- impervious, heat-conducting, microwave transparent pouch will be referred to as a By the term “microwave transparent” we mean that the pouch material is unreactive to microwave energy. Such materials are characterised by having a structure which lacks dipolar molecules. Suitably the pouch material may be a polyethylene. Pouches may be produced from “Food Grade” polyethylene.

The thermoplastic polymers employed in the present invention should be reactive to microwave energy, i.e. contain dipolar molecules. Polymers which are useful in the present invention include those based on the caprolactone molecule. The polymeric splint material may comprise homopolymers of caprolactone or polymer blends thereof either alone or in a mixture with fillers such as fibrous ligneous materials. Preferred splinting products for use in the present invention are those described in our published patent specifications US20080154164 and WO20080412151, the disclosures of which are incorporated herein by reference. The most preferred splinting products are multi- component products comprising a thermoplastic polymer substrate bearing a skin- contacting padding layer over one surface of the substrate. Such multi-component splinting products are disclosed in our aforementioned published patent specifications Aptly, the splint and the heater pad are packaged within an outer container formed from a water-impervious, microwave energy transparent material. The container may be of rigid construction or, more preferably, is a flexible pouch.

Thus, according to a first embodiment of the invention, the splint and heater pad are contained in a single outer container.

Alternatively the pouch which contains the water laden absorbent pad may be adapted to separately contain the splint.

Thus, in an alternative embodiment of the invention, a pouch is provided having two compartments, separated by a water-impervious, heat-conducting membrane or septum, wherein the first compartment contains said water laden absorbent material and the second compartment contains the splinting product.

The compartments or pouches which contain only the water laden absorbent material may also be provided with means for pressure releasing device such as a frangible rupture seal to vent steam outside the package, in the event of excess steam build-up, to prevent distortion or contamination of the splinting product.

The compartments or pouches which contain the splint are also provided with means to allow ready removal of the heated splint. The removal means and the pressure releasing, whilst independently operable, may be formed into a unitary device The splint and heater pad should be arranged to lie adjacent to each other as closely as possible whether both components are packaged together or placed separately in the microwave heater. lEo9o35o We have found that the presence of the heater pad in close proximity to the thermoplastic substrate being heated, attenuates the microwave irradiation during heating and changes favourably the permittivity values of the nearby thermoplastic splint material and decreases the so called “Edged heating phenomena” a problem found common in heating food. This results in more even heating of the thermoplastic substrate, and reduces “hot spots”. The edge heating phenomena may be further attenuated if the heater pad is placed in close proximity to the skin-contacting padding layer of a multi-component splinting product. The even distribution of heat will reduce the occurrence of hot spots and enable higher microwave energy settings to be used and/or shorten time for heating. Even distribution of heat also prevents the occurrence of “cool spots” since evaporated water contacting and condensing on the areas of the pouch material or septum adjacent any cooler spots on the polymer substrate of the splint will heat such areas.

The water absorbent material may comprise any known material which will absorb and retain water. Such materials may comprise a hydrogel such as those based on celluloses or be composed, at least in part, of hydrophilic fibres such as those known as super- absorbing polyolefin filaments. The water absorbent material will be a material which will permit microwave heating of the absorbed water.

Preferably the water absorbent material will contain and retain sufficient absorbed water such that no free water exists outside the water absorbent material. This ensures even distribution of water over the cross sectional area of the product being heated by microwave and therefore ensures more even heat absorption and dissipation into the underlying substrate. Aptly, the absorbent will contain water in an amount ranging from 0.01 to 0.15 m|.cm2. Typically the absorbent material will contain about 0.05 ml of water per cm2 of absorbent material.

Preferably, the water laden absorbent material should lie adjacent any body-contacting padding material which may form part of the splint in order to ensure not only adequate and even heating of the thermoformable polymer but also to reduce the amount of heat applied to the body~contacting layer of the splint. Since the permittivity of the padding will be different to that of the polymer substrate it is not heated to the same temperature as that of the substrate.

Depending on the power of the microwave energy employed and other characteristics of the energy source, the time setting should be calibrated to allow heating of the substrate to a temperature such that it becomes sufficiently pliable to be wrapped or formed around the body portion to be supported and yet not high enough to cause discomfort or burning of the skin. For a commercial microwave oven generating energy at a frequency of 2.54GHz we have found, for example, a time of a about 3 minutes is required to heat the polymer substrate of a lower arm splint to about 60°C The invention will now be illustrated by reference to the following example.

IE 090350 A heater pad was formed by inserting 50ml of water into a 125 micron PE pouch containing an absorbent pad measuring 300mm x 330mm and the pouch sealed, using a heat sealer. The absorbent pad was made from a commercial grade of Cellulose and Acrylic fibres made by Elliot and sold under the name "Dry|ine” The heater pad was placed inside a commercial microwave oven (Sharp model R21AT), rated at 1000 watts at 100% power setting and a thermoplastic arm splint with padding attached , roughly having the same dimensions as the heater pad was placed on top of the heater pad with the padding side down..

The power of the oven was adjusted to the 60% setting (equating to 600 watts) and switched on for 3 minutes.

After 3 minutes the thermoplastic splint was removed and it was found to be fully activated. The product was soft and pliable and there was no evidence of over-heating, hot spots, burning or smell.

Claims (1)

Claims

1.A packaged splinting product including, in combination, heater pad comprising a water laden absorbent material sealed in a water-impervious, heat-conducting, microwave transparent pouch, said material being adapted to permit microwave energy to enter and heat the contained water and a splint comprising a polymer substrate wherein said absorbent material is adapted and arranged to lie adjacent in close proximity to the polymer substrate of the splint Apparatus as claimed in claim 1 wherein the splint further comprises a layer of skin-contacting padding material. A product as claimed in claim 2, wherein the padding layer of the splint is adapted and arranged to lie adjacent the absorbent material. A product as claimed in claim in any one of claims 1 to 3, in which the heater pad and splint are enclosed in a container formed from a water-impervious, microwave energy transparent material A product as claimed in claim 4 wherein said container is divided by a septum formed from a water-impervious, heat-conducting, microwave transparent material which septum separates the water laden absorbent material from the splint. A product as claimed in any one of the preceding claims wherein the water loading of the absorbent material is about 0.05 m|.cm2' Apparatus means for heating thermoplastic polymeric splinting products comprising a water laden absorbent material sealed in a water-impervious, heat- conducting, microwave transparent pouch wherein said material is adapted to permit microwave energy to enter and heat the contained water and is arranged to lie adjacent in close proximity to the polymer substrate of the splint. Apparatus as claimed in claim 1 wherein the water loading of the absorbent material is about 0.05 m|.cm2'