The present invention relates to the use of CMC as a binder for an insulating material and to an insulating material comprising insulating fibres held together by CMC as a binder, to the use of such insulating material and to various elements made from such insulating material.

Background and Related Art

Insulating materials are known in the art comprising various types of fibres held together by a binder.

Adhesives are known in the art, which comprise traganth gum (also known as katira gum), gum arabic (also known as acacia gum) and CMC. For example, US patent application publication 10/668,950 discloses such a fiber-based product comprising i.a. solubilized cellulose, and gum, to be used as an additive to a binder. US patent

5,066,709 comprises an adhesive comprising a carrier and a polymer.

Further, adhesives are known comprising pine resin and resin acid. For example, US patent application 12/705,817 discloses an adhesive comprising a resin along with an acrylic copolymer.

In general, such insulating materials are based on polymers or other synthetic materials. There is a desire for more environmentally friendly insulating materials, using natural fibres and environmentally friendly binders while having good insulating properties for heat and sound.

Summary of the Invention

It is therefore an object of the invention to provide a binder for use in insulating materials that is non-toxic and environmentally friendly and will retain good insulating properties if used with natural fibres. It is also an object to provide an insulating material based on natural fibres with the same properties. The invention relates to the use of CMC as a binder for an insulating material.

CMC is naturally non-toxic and environmentally friendly. It is even safe to eat. Also, we have found that when mixed with natural fibres, it does not destroy the structure of the fibres. In particular, it does not cause the crevices of the fibres holding air to collapse. Therefore, a material comprising natural fibres and using CMC as a binder will comprise air-filled cavities, which contribute to the insulation and sound absorption.

The CMC may be used alone or the binder may comprise CMC together with other substances, such as a stabilizer, or preservatives, which should also be environmentally friendly and non-toxic.

Preferably, naturally antiseptic ingredients are used to prevent mold in the products in which the binder is used. Substances such as natural gums and/or resins may be added to the CMC, primarily as anti-bacterial, anti-fungal and preservatives. These substances typically include one or more of natural resin, resin acid, katira gum and gum arabic. The use of resins and gums together with CMC is particularly well suited for use as a binder for organic fibres, since they, too help preserve the structure of the fibres, as discussed above.

The binder may be used in the form of powder or liquid in varying concentrations for different needs and fields of application. To produce a liquid binder, the powder is mixed with water, or with another suitable liquid.

The binder may also comprise egg white, which is a well-known natural and edible binding agent. Other edible substances such as pectin or gelatin may also be added as stabilizers.

In one embodiment, the total content of gum in the binder is within the range of 10 % - 50 %. In one embodiment, the total content of resin and/or resin acid in the binder is within the range of 5 % - 20 %.

The content of CMC in the binder should be at least 30 % and up to 100%.

The insulating material comprises fibres mixed with the binder. Preferably fibres of organic material are used. This includes fibres such as wood or other plant fibres, or animal fibres such as wool or silk. The ratio between the fibres and the binder should be such that there is significantly more of the fibres, but enough binder to hold the fibres together. A ratio of between 8.5: 1 and 9.5: 1, preferably 9: 1 between fibres and binder has been found to be suitable, but this may of course be varied.

The binder has been found to have a strength and other properties corresponding to those of adhesives for wood.

Materials made from the inventive binder and fibres mentioned above are non-static and therefore dust-repellant. This is particularly useful for surfaces that are close to heating elements.

The fibre powder comprises up to 100 % of natural fibres. Minerals such as mica or different silicates may be added to vary the level of heat resistance and flame resistance.

A mixture of the powder with water has a neutral pH of approximately 7.

The insulating material may be used for a number of different types of elements including sheets to be used, for example, as wall covers, or thicker elements such as boards and building blocks. The material may also be reinforced by metal elements or reinforcing fibres such as armide fibres, to enhance their strength, durability and impact resistance.

After the shaping, a fire inhibiting coating may be applied. It is important that this coating does not affect the insulating properties of the insulating material negatively.

The present invention therefore also relates to a fire inhibiting composition according to the preamble of claim 1. It also relates to the use of such composition.

Fire inhibiting compositions are commonly used as a surface layer on different types of materials and for different purposes such as building and packaging, manufacturing of furniture, and for the automotive and aviation industries. Many commonly used fire inhibiting compositions for use as a coating, or surface layer, are based on metals or other chemical compounds such as bromide or borax, that are toxic to humans or animals, and/or damaging to the environment.

European patent application EP 1422261 discloses a fire inhibitor comprising potassium hydrogen tartrate and thermosetting resin together with a metal salt or an amine salt of a tetrazole compound, for use, for example in electronic components. US patent application 13/248,368 discloses a fire inhibitor comprising potassium aluminium sulphate and mica. This relates to an expanded foam comprising a binder such as a polymer and a plurality of particles, which may be flame retardant.

It is an object of the invention to provide a fire inhibiting composition suitable for use as a coating that is effective in preventing fire while being non-toxic and

environmentally friendly.

The invention relates to a fire inhibiting composition comprising

Potassium aluminium sulphate (also known as potassium alum) and/or

Potassium hydrogen tartrate (also known as potassium bitartrate, or cream of tartar). The composition may be used in dry form, or with a liquid carrier. Preferably the liquid carrier is water-based. It may also be based on other suitable non-toxic liquids. Alcohol such as ethanol, or another suitable liquid, may be added to make it dry faster.

The composition may also comprise one or more of the following:

• Mica powder

• Frankincense

• A stabilizer selected from edible stabilizers.

The stabilizer may be, for example corn flour, which has been found to be suitable in such a combination.

The composition preferably also comprises preservatives, to prevent mold.

In less preferred embodiments, the composition also comprises phosphates and copper sulphate and/or polyphosphate.

The main part of the dry material of the fire inhibiting composition is preferably constituted of potassium aluminium sulphate and potassium hydrogen tartrate.

The concentration of potassium aluminium sulphate is preferably between 30 % and 70 % of dry substance, that is, of the powder not mixed with water. The concentration of potassium hydrogen tartrate is preferably between 30 % and 70 %. It would be possible to use only one of the two, but a mixture is preferred since they enhance each other. The preferred ratio of aluminium sulphate to potassium hydrogen tartrate in dry substance is between 6:4 and 8:2, preferably 7:3.

The inventive fire inhibiting composition is based on natural ingredients, which are edible. If used on surfaces of the CMC based insulating material it will maintain the structure of the material and thereby its insulating properties. The composition is environmentally friendly as it avoids the use of hazardous chemicals such as bromine or heavy metals. It is also 100 % recyclable. Detailed Description of Preferred Embodiments

The invention relates to two parts, which can be used together or separately: The first part a building element based on CMC used as a binder for natural fibres. The second part is a fire inhibiting material, suitable for use as a coating. In particular the two parts may be used together, in that the coating is applied to a building element.

In this case, the coating makes the building element more fire resistant. In addition, if the coating comprises preservatives this will make the building element itself more resistant to bacteria and fungus, and reduce or eliminate the need for preservatives in the building element itself.

An example of a composition of the binder according to the invention is

Katira gum (traganth gum) 10%

Pine resin 5%

Resin acid 5%

Gum Arabic (acacia gum) 20%

CMC 55%

Egg white 2%

Preservatives: 3%

Examples of suitable preservatives are sodium benzoate, calcium sorbate, potassium benzoate and sodium sulfite.

The fibres are preferably in the form of a powder comprising plant or animal fibres (cotton, linen, hemp, wool, silk) and optionally added natural resin. The fibre powder can be manufactured by grinding dried fibres, preferably together with natural resin, to a desired fibre size. Normally, a uniform size will not be achieved, but a distribution of different sizes. The fibre size will influence the structure and look of the resulting material, and also the insulating properties of the powder. A suitable fibre size has been shown to be between 0.1 mm and 50 mm, but this is not essential. In dependence of the fibre size larger and smaller air cavities will be created in the insulating material. This will cause excellent insulating properties both for sound and heat, and will also reduce the weight of the material. The material effectively attenuates noise in a room. The fibre structure also makes the fibre powder heat resistant.

Pigments, such as natural pigments may also be included in the fibre powder. Also, decorative elements such as seeds and fibres can be used to make the resulting material decorative.

The insulating material may be used for a number of different types of elements including:

- Insulating and sound absorbing wall covers

- Inner or outer walls, wall panels, boards, ceiling panels

- Application directly to substrate material such as plaster, wood or concrete by means of spraying or painting

- Light-weight, sound absorbing building blocks or boards

- Beams, or other building elements in various shapes

The material may also be reinforced by metal elements or reinforcing fibres such as armide fibres, to enhance their strength, durability and impact resistance.

A manufacturing process for a building element comprising the inventive binder is shown in Figure 1 and includes the following steps:

In step S I, the fibres in dried form are ground to the desired size distribution, preferably together with pine resin. In step S2, the ground fibres are mixed with a CMC-based binder according to the invention to form a dough having the desired properties.

Step S3 is an optional step in which other substances, such as various minerals, can be added to the dough to enhance its properties, for example to make it more fire resistant or water repellant. In step S4, the dough is shaped to the desired element, for example, a board, a brick, a panel for a wall or a ceiling, an insulating sheet suitable for use as wallpaper, or any other building element. This may be done according to any process known in the art for shaping an element from a dough.

In step S5, the element is dried. This preferably includes the use of heat, for example baking the element, to speed up the drying process. It may be necessary to apply pressure to the element to preserve its shape.

If desired, in step S6, the element is cut to the desired shape and form, and in step S7 a coating may be applied. This may be a fire-inhibiting coating, preferably the one described in this document. The coating may in addition, or alternatively, be designed to give the element a particular finish, for example with a colour or a particular structure.

Finally, in step S8, the element may be packaging as desired.

In step 2, the ground fibres may be mixed with the binder in powder form, and then with water, or the ground fibres may be mixed into a binder which is already in liquid form. In both cases, the ratio between powder, water and fibres should be adapted to give the dough the desired properties. For example, for shaping into bricks, less water may be used than if the dough is to be applied to a wall.

Instead of steps S4 and S5, the dough may be applied to a substrate material and allowed to dry on this material. This may be done by spraying, or spreading directly on the wall or other substrate material, and may even be done by hand. A smoothing step is then preferably included to provide an even surface. In this way a covered building element can be achieved in one step rather than first forming and drying the element and then attaching it to the substrate. Various methods for how to shape a dough into bricks and dry it are known in the art. Also, methods for forming the dough into a sheet are known in the art.

If the insulating material is used together with a coating comprising preservatives, no preservatives are needed in the binder. Preferably, this coating should be one that also helps maintain the insulating properties of the insulating material. In the following, such a fire-inhibiting coating will be disclosed, which will not destroy the structure of the insulating material and therefore is suitable for use as a coating for the insulating material. This coating can be applied to the surface of any structure or element made from the insulating material. It may also be applied to other types of structures or elements as a fire inhibitor.

The main part of the fire inhibiting material is preferably constituted of potassium aluminium sulphate and potassium hydrogen tartrate.

The coating according to the invention may be used in the form of a powder or with a liquid carrier. The composition can be varied in terms of flame inhibition and fire protection. The relative content of the various ingredients may be varied, and the concentration of the composition in a liquid for application may be varied. In dry form, the powder may be mixed with organic fibres, such as cellulose fibres, to increase the fire resistance in the fibres when used, for example, as insulation material.

The liquid carrier is preferably aquatic, preferably comprises at least 50 % water and may be pure water. Other liquids may be used in the liquid carrier to enhance certain properties. For example, the carrier may comprise a certain amount of alcohol, such as ethanol, for example between 1 and 10 %, which will make the fire inhibiting composition dry faster. Potassium aluminium sulphate is highly soluble in water, whereas potassium hydrogen tartrate is not very soluble in water. For the purposes of the flame inhibiting liquid, both substances should be essentially fully dissolved in the liquid. Experiments have shown that the fire inhibiting composition of the invention is capable of stopping a fire in its initial phase without leaving a smouldering fire which could again turn into a fire. The fire inhibiting composition of the invention also counteracts smouldering. This is achieved by the composition's ability to stop the oxygen supply. Hence, the use of the composition will reduce the risk of extensive damage in the case of a fire.

The relative concentrations of each of the components in the composition of the fire inhibitor may be varied depending on the areas of use. Also, the concentration of dry material of the composition in water may be varied depending on the desired use.

The fire inhibitor mixed with a liquid carrier such as water may be applied to an object in various different ways, but preferably for impregnating an object, or a sheet of material. For example, the object may be soaked in the liquid fire inhibitor for a suitable amount of time. Alternatively, the liquid fire inhibitor may be applied to an object by means of a paint brush or roller, or by spraying. In any case, the object should then be allowed to dry, naturally or with the aid of a heater.

One detailed example of a fire inhibiting composition according to the invention is:

Potassium aluminium sulphate 40%

Potassium hydrogen tartrate 40%

Mica powder 5%

Frankincense (Olibanum) 5%

Corn flour 5%

Chalcanthite (copper sulphate) 1,3%

Polyphosphate 0,7%

Preservatives 3%

Examples of suitable preservatives are sodium benzoate, calcium sorbate, potassium benzoate and sodium sulfite.

The percentages given above are of dry substance, that is, not mixed with liquid. In a particularly preferred embodiment the fire inhibiting composition is applied to an object or a surface manufactured from the insulating material discussed above. As mentioned this may involve spraying or painting it on an element, or dipping the whole or part of the element into the fire inhibiting composition and then letting it dry. Preferably the fire inhibiting composition is applied after the element has been allowed to dry from the manufacturing procedure. The fire inhibiting composition helps preserve the structure of the fibres in the insulating material and therefore does not destroy the insulating properties of the element.