GB1570608A - Ceramic articles - Google Patents

Description

(54) CERAMIC ARTICLES (71) We, DOULTON INDUSTRIAL PRO DUCTS LIMITED, a British company of Filleybrooks, Stone, Staffordshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to ceramic articles.

Articles which disperse products such as perfume, insecticides or germicides into the atmosphere at a controlled rate are wellknown. Fragrance-producing articles -- often termed as "air fresheners" - include a perfume together with a means for releasing the perfume into the atmosphere at a controlled rate. Pressurised containers which eject a spray of perfume and propellant are one well-known type of air freshener, whereas dispersing the perfume in a gel is another well-known type. Gel-type products however require a suitable container since the gel is not normally self-supporting or sufficiently rigid to be employed alone, whereas the aerosol-type of air freshener is expensive and, in use, releases the propellant into the atmosphere (which can be undesirable).

Similar products exist for diseminating insecticides and germicides.

We have developed a new type of article for dispersing perfumes, insecticides and germicides into the atmosphere. It is based upon the use of a particular porous ceramic material as a carrier for the perfume, insecticide or germicide. The product to be dispersed is absorbed in the pores of the ceramic (which is self-supporting) and is released therefrom at a rate dependent on the exposed surface area of the ceramic, and other properties of the ceramic such as the shape, quantity and distribution of pores.

According to the invention we provide a shaped porous ceramic article having pores thereof containing a dispersable material comprising a perfume agent, and/or an insecticide, and/or a germicide, said ceramic being formed of silica, and wherein the pore size of the ceramic is less than 5 microns, and the porosity of the ceramic is from 20 to 60. By "a shaped article" we mean a self-coherent body, and by "ceramic article" we mean a body that has been fired.

The ceramic is preferably formed from diatomaceous silica material which has been bonded with agents so as to be suitable for fabrication by the technique suitable for, and selected for, producing the shaped article -- e.g. chemical casting, slip casting, is static pressing, injection moulding, compression moulding, extrusion, core blowing, or hydraulic die pressing. The ingredients selected to provide the ceramic are dependent upon the fabrication method selected, which, itself is normally decided by the shape and quantity of the desired ceramic.

Diatomaceous silica ceramics can be produced to have a high surface area, chemical inertness, high strength, and a fine pore structure coupled with a high volume of open pores and interconnected capillary passages. Such ceramics are very suitable for the rapid absorption and efficient emanation of the product concerned perfume agent, insecticide, germicide.

When the ceramic has been manufactured, it is at least partially impregnated with the perfume agent, insecticide or germicide preferably dissolved or dispersed in a- liquid carrier. The types of perfume agents, insecticide or germicide and liquid carriers employed are, of course, selected in accordance with the use to which the article is to be employed.

In a preferred- embodiment, colouring agents are also impregnated in the ceramic such colouring agents can be selected so as to change colour when substantially all of the perfume, insecticide or germicide has been released. This provides a useful indication of the life of the product. The colouring agent acts as a chemical indicator for the presence or absence of the-perfume, insecticide or germicide and the-type- selected depends upon the product employed. An indicator dependent upon pH can be employed if the perfume, insectici or germi cide has a noticeable influence on the pH of the liquid carrier. Alternatively, the indicator can be a chemical which complexes, or reacts with or in the presence of the perfume, insecticide or germicide to provide a colour change. A typical pH indicator which changes colour is 4-dimethylaminoazobenzene.

The ceramic article is left unglazed, or is glazed only partially so as to enable the perfume agent, insecticide or germicide to emanate from the pores thereof. The article can be any shape or from - for example a ceramic fir tree may be produced and impregnated with a pine fragrance perfume agent/liquid carrier and with a colouring agent which changes say, from blue/green to yellow when the pine fragrance has substantially all been lost.

The meramic article may be shaped to form an insert or plug in another article (non-porous) so as to act as, for instance, a fragrance-producing centre of focus in the other article.

Examples of the production of porous ceramic articles for use in the invention are as follows.

EXAMPLE 1 A shaped body was slip cast from a compositioned based upon (by weight): 60% diatomaceous silica 20% perlite, 15% clay, and balance: bentonite and sodium silicate.

This composition was mixed with water to provide a dispersion suitable for slip casting, and was cast into plaster moulds.

After drying, the products were rapidly fired to about 1000"C.

Similar fired porous ceramic articles were obtained when the perlite was replaced by dicalite or diatomite.

EXAMPLE 2 A body for hydraulic pressing was prepared by mixing (by weight): 60% diatomaceous silica 20% dicalite, and balance: sodium silicate and sodium alginate.

This body was granulated and pressed in a hydraulic press between metal dies at 500 Ibf/sq. in. The pressings were then fired to above 1000or.

EXAMPLE 3 A dry mix for isostatic pressing was prepared by mixing (by weight): 80% dicalite, 20% white Spanish Kieselguhr.

The mix was further dried and filled into rubber moulds which isostatically pressed to 5000 Ibf/sq. in. The pressings were then fired to above 1000"C.

The shaped ceramic articles prepared in the above Examples may be employed as fragrance-producing articles of the invention by impregnating with a solution or dispersion of an appropriate perfume agent. The impregnation can be effected simply by spraying or pouring the solution of dispersion onto the article or by steeping the article in the solution or dispersion.

If desired, an insecticide or germicide mav be incorporated in the article either together with or in place of the perfume agent. In one example 14 percent by weight DDVP insecticide was included in the perfume liquid impregnated into the porous ceramic.

WHAT WE CLAIM IS: 1. A shaped, porous ceramic article having pores thereof containing a dispersable material comprising a perfume at, and I or an insecticide, and/or a germicide, said ceramic being formed of silica, and wherein the pore size of the ceramic is less than 5 microns, and the porosity of the ceramic is from 20 to 60%.

2. An article according to claim 1 wherein the dispersable material is present in the ceramic dispersed or dissolved in a liquid carrier.

3. An article according to claim 1 or 2 wherein the silica is diatomaceous silica.

4. An article according to any of claims I to 3 wherein the ceramic additionally contains a colouring agent in the pores thereof.

5. An article according to claim 4 wherein the colouring agent is arranged to change colour when substantially all of the dispersable material has been released.

6. An article according to any of claims 1 to 5 wherein the dispersable material is a perfume agent.

7. An article according to claim 6 wherein the dispersable material is a combination of a perfume agent and either an insecticide or germicide.

8. An article according to claim 1 wherein the shaped ceramic article is substantially as herein described in any of the Examples.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. cide has a noticeable influence on the pH of the liquid carrier. Alternatively, the indicator can be a chemical which complexes, or reacts with or in the presence of the perfume, insecticide or germicide to provide a colour change. A typical pH indicator which changes colour is 4-dimethylaminoazobenzene. The ceramic article is left unglazed, or is glazed only partially so as to enable the perfume agent, insecticide or germicide to emanate from the pores thereof. The article can be any shape or from - for example a ceramic fir tree may be produced and impregnated with a pine fragrance perfume agent/liquid carrier and with a colouring agent which changes say, from blue/green to yellow when the pine fragrance has substantially all been lost. The meramic article may be shaped to form an insert or plug in another article (non-porous) so as to act as, for instance, a fragrance-producing centre of focus in the other article. Examples of the production of porous ceramic articles for use in the invention are as follows. EXAMPLE 1 A shaped body was slip cast from a compositioned based upon (by weight): 60% diatomaceous silica 20% perlite, 15% clay, and balance: bentonite and sodium silicate. This composition was mixed with water to provide a dispersion suitable for slip casting, and was cast into plaster moulds. After drying, the products were rapidly fired to about 1000"C. Similar fired porous ceramic articles were obtained when the perlite was replaced by dicalite or diatomite. EXAMPLE 2 A body for hydraulic pressing was prepared by mixing (by weight): 60% diatomaceous silica 20% dicalite, and balance: sodium silicate and sodium alginate. This body was granulated and pressed in a hydraulic press between metal dies at 500 Ibf/sq. in. The pressings were then fired to above 1000or. EXAMPLE 3 A dry mix for isostatic pressing was prepared by mixing (by weight): 80% dicalite, 20% white Spanish Kieselguhr. The mix was further dried and filled into rubber moulds which isostatically pressed to 5000 Ibf/sq. in. The pressings were then fired to above 1000"C. The shaped ceramic articles prepared in the above Examples may be employed as fragrance-producing articles of the invention by impregnating with a solution or dispersion of an appropriate perfume agent. The impregnation can be effected simply by spraying or pouring the solution of dispersion onto the article or by steeping the article in the solution or dispersion. If desired, an insecticide or germicide mav be incorporated in the article either together with or in place of the perfume agent. In one example 14 percent by weight DDVP insecticide was included in the perfume liquid impregnated into the porous ceramic. WHAT WE CLAIM IS:

1. A shaped, porous ceramic article having pores thereof containing a dispersable material comprising a perfume at, and I or an insecticide, and/or a germicide, said ceramic being formed of silica, and wherein the pore size of the ceramic is less than 5 microns, and the porosity of the ceramic is from 20 to 60%.

2. An article according to claim 1 wherein the dispersable material is present in the ceramic dispersed or dissolved in a liquid carrier.

3. An article according to claim 1 or 2 wherein the silica is diatomaceous silica.

4. An article according to any of claims I to 3 wherein the ceramic additionally contains a colouring agent in the pores thereof.

5. An article according to claim 4 wherein the colouring agent is arranged to change colour when substantially all of the dispersable material has been released.

6. An article according to any of claims 1 to 5 wherein the dispersable material is a perfume agent.

7. An article according to claim 6 wherein the dispersable material is a combination of a perfume agent and either an insecticide or germicide.

8. An article according to claim 1 wherein the shaped ceramic article is substantially as herein described in any of the Examples.