The invention relates to the use of silicon dixiode/silica as a moisture-absorbent material in clothing and o equipment which is used on or near the body. To be precise, the invention relates to the use of a particu silica gel in soles, socks or linings in different type footwear. That people's feet become damp to a varying det_ depending upon the shoe or boot type, the temperature degree of activity, is a well-known problem.

The invention also relates to the use of silica gel as a moisture-absorbent material in jacket linings, car seat covers and for use in the transport and storage of hot food.

Silica gel/silicon dioxide (Si0 ₂ ) is found in large quantities in nature in the form of sand, quartz and similar. Silica gel is insoluble in water and is usually found in the form of a white powder. Silica is used in many products such as, e.g., glass, cement, cosmetics, abrasives, catalysts and microcircuits. Silica gel also has a large area of application as a moisture-absorbent material, especially in industry and research where it is a requirement that work is carried out under conditions free from water. Silica gel is the amorphous, non-crystalline form of silicon dioxide (Si ,) .

Tests and calculations have shown that under extreme physical conditions, an adult human being can exude as much as 20 ml of moisture per foot per hour.

Today, several types of shoe soles are known which claim to be moisture and odour-absorbent. However, in practice this proves not to be the case. There are, for instance, soles made of various foam rubber materials, but these have a limited absorbent capacity.

NO 882095 relates to a shoe membrane material having absorbent

properties onto which activated carbon particles are dotted. The material is especially intended to be used in military combat boots or protective boots to adsorb aggressive chemicals.

NO 854987 relates to a sole which contains an absorbent layer of moisture storing fibres having capillary-active pores.

NO 890875 describes an inner sole having channels, and the function of the sole is to produce a yielding and shock- absorbing effect during use.

The present invention thus relates to a use of silica gel in an insole for footwear. A sole containing silica gel will have the property that the moisture arising from the user's sweat in boots and shoes, in particular those which have impervious over-material of rubber and synthetic substances such as PVC, or leather material covered with a coating of such a substance, will be absorbed in the silica gel thus preventing the user's feet from becoming damp. To date, there are no soles which have an effect similar to that of a silica gel sole, insofar as absorption of moisture and odour is concerned.

Silica gel also has the advantage that it is able regenerate on drying. This can be done in that the sole is dried with a boot dryer or in a tumble dryer, oven or on a drying stand over a stove. Alternatively, the drying can take place at room temperature.

The sole according to the invention may consist of three layers. The undersole must have a rigidity that prevents the sole from "curling" on use. It must be diffusion-proof so that it does not absorb moisture from below, and the material must withstand heat as high as 50°C during drying. A highly suitable material is pressed cork which is available in very thin sheets, measuring as little as 0.7 mm in thickness. This

is essential to prevent the sole from building up too much inside the boot or shoe. Other materials are also conceivable, natural or synthetic, just as long as they have the aforementioned properties.

The middle sole consists of silica gel in particulate form which is from 1.2 mm and smaller. A silica gel is used where as much as 90% is smaller than 1.2 mm. This powder is spread evenly over the entire surface of the sole. The amount of silica gel varies according to the size of the sole, and whether it is for boots or shoes, and may be from 1 mm to 5 mm.

The uppermost layer of the sole consists of textile wherein the density of the weave is such that it does not allow the silica gel particles to penetrate. The textile material in the top layer must have a wear resistance which withstands longterm use.

In order to keep the particles evenly spread on the sole surface between the bottom layer and the top layer, the sole will be sewn through in, e.g., a "waffle pattern" or a chequered pattern of approx. 0.8 sq. cm. Longitudinal, transverse, zig-zag or other patterns may also be used.

The chief function of the pattern is to keep and distribute the silica gel material evenly over the sole, and the optimal pattern will be chosen on the basis of this criterion.

By using a silica gel material which changes colour as the gel passes from a dry to a moist condition, and by using a "window" in the sole, it is possible to see, e.g., when the sole has been completely dried.

Silica gel may also be used in a sock for use in footwear. The sock may consist of a conventional textile material, but can, e.g., under the foot at the front and back be provided

with areas having a silica gel layer. Silica gel may also be used as a permanent lining in footwear, e.g., boots.

Silica gel which is used as a lining in jackets may, e.g., be in the form of a vest which can be taken out of and fastened into the jacket with the aid of fastening means. This lining may be used under jackets for use during physically demanding work or, e.g., in moutaineering jackets.

Silica gel may also be used as a moisture-absorbent seat cover in, e.g. , cars.

Within the ever-growing fast food and/or ready-made food trade where food is transported hot, there has long been a need for a material which absorbs moisture that evaporates from the hot food. If this moisture is not removed, the consistency of the food will be spoiled. By using a cushion or layer of silica gel, this moisture problem will be almost entirely solved. The silica gel can be sewn into a cushion, one side of which consists of a material which is impervious to moisture, whereas the other side which is exposed to the hot food can absorb moisture.

Paper and aluminium bags which today are used for storing grilled food can be lined on the inside with a silica gel layer. This will absorb any moisture which is given off and in this way the food, e.g., a chicken, will keep its crisp skin or crust.