AU667170B2

AU667170B2 - Preservative

Info

Publication number: AU667170B2
Application number: AU65980/94A
Authority: AU
Inventors: Christopher Ian Lee-Steere
Original assignee: CHRISTOPHER IAN LEE STEERE
Current assignee: CHEMTECH DEVELOPMENT Pty Ltd
Priority date: 1993-07-15
Filing date: 1994-06-27
Publication date: 1996-03-07
Anticipated expiration: 2014-06-27
Also published as: AU6598094A

Description

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FILING DATE: CHRISTOPHER IAN LEE-STEERE PL9 959 15/ 7/93 *0 *fee 0 00 Invention Title: PRESERVATIVE The following statement is a full description of this invention, including the best method of performing it known to me/us: 0*S* 0O 00 o 0

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00 o S S. S, This invention in one aspect resides broadly in a process for the production of a preservative, the process including:preparing a dry mixture of a hydrated boron compound and a non-hydrated boron compound; heating the mixture to form a slurry, and extruding the slurry to form a predetermined shape.

The slurry may be utilised as a preservative for external application to timber, but it is preferred that the preservative be such as can be utilised internally within timber such as, for example, by being located in a bore drilled in the timber. Accordingly it is preferred that" the process includes forming the slurry into a predetermined shape. In a preferred embodiment the 15 slurry is formed into the predetermined shape by extrusion.

The hydrated boron compound can be chosen from a range of suitable .compounds and is preferably a sodium boron complex. Suitably the sodium boron complex is disodium tetraborate and preferably is disodium tetraborate decahydrate. The non-hydrated boron compound is preferably boric acid.

The hydrated boron compound and the non-hydrated boron compound are mixed in a ratio in accordance with the desired physical properties of the slurry... Thus if it-is desired that the slurry be relatively thin and free flowing a relatively higher proportion of hydrated boron compound is used, whereas if a thicker slurry is required for extrusion a relatively lesser proportion of the hydrated compound is used. If the compounds are disodium tetraborate decahydrate and boric acid the compounds are mixed in a ratio by weight of between 1:1 and 6:1 respectively. It is preferred that the ratio is substantially 3:1.

Preferably the mixture is heated such that the boron compounds are not fully dissolved. The mixture may be heated to a lower temperature sufficient to form a thick S slurry. Alternatively the mixture may be heated until 00 Zo '4V the boron compounds are fully dissolved to form the slurry which may then thickened if required by mixing a hydrated boron compound and/or a non-hydrated boron compound with the slurry.

Suitably the mixture is heated to a temperature of greater than approximately 65 degrees Celsius.

Preferably the mixture is heated to a temperature of between approximately 65 and 85 degrees Celsius. More preferably the mixture is heated to a temperature of between approximately 77 and 81 degrees Celsius. Most preferably the mixture is heated to a temperature of approximately 79 degrees Celsius.

The mixture may be heated by any suitable means such as in an oven, on a hotplate or in a heat-jacketed 15 conduit during a flow processing operation. The mixture can be formed into a slurry in much less time if heated S.by microwave means such as in a microwave oven and this is preferred.

In another aspect this invention resides broadly in 20 a process for the production of a preservative, the process including:preparing a dry mixture of a hydrated boron compound and a non-hydrated boron compound, and oo o heating the mixture to a temperature greater than' approximately 65 degrees Celcius to form a slurry.

In another aspect this invention resides broadly in oooo a preservative produced by a process as defined above.

Preferably the preservative contains approximately 14.8% boron. It is also preferred that the preservative is in the form of a tablet or pellet.

Description of preferred embodiment of Invention In order that this invention may be more easily understood and put into practical effect, reference will now be made to the following example which describes a preferred embodiment of the invention.

fkk Three parts by weight disodium tetraborate decahydrate was mixed with one part by weight boric acid T to form a dry mixture. The mixture was heated in a microwave oven to a temperature of approximately 79 degrees Celsius. The boron compounds were not fully dissolved and the mixture formed a thick slurry which was fed to an extrusion device and extruded to form a continuous length which was then cut to length to form cylindrical tablets or pellets. It was unnecessary for the extruded material or the tablets to be racked or stored to allow time for setting as it was found that the material acquired the majority of its set during the extrusion process and within a matter of minutes formed a 00o os

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S S as in an oven or on a hotplate. However the mixture can be formed into a slurry in much less time if heated by microwave means such as in a microwave oven and this is preferred.

In another aspect this invention resides broadly in a preservative produced by heating a dry mixture of a hydrated boron compound and a non-hydrated boron compound. Preferably the preservative is produced by a process as defined above.

In order that this invention may be more easily understood and put into practical effect, reference will now be made to the following example which describe a preferred embodiment of the invention.

Three parts by weight disodium tetraborate decahydrate was mixed with one part by weight boric acid to form a dry mixture. The mixture was heated in a microwave oven for three minutes to a temperature of between approximately 40 and 70 degrees Celsius. The boron compounds were not fully dissolved and the mixture formed a thick slurry which was fed to an extrusion device and extruded to form a continuous length which was 0ego then cut to length to form cylindrical tablets or pellets. It was unnecessary for the extruded material or the tablets to be racked or stored to allow time for S 25 setting as it was found that the material acquired the majority of its set during the extrusion process and within a matter of minutes formed a white crystalline solid. The tablets are approximately 9 millimeters in diameter and approximately 25 millimeters in length although other sizes can be utilised. The tablet contains approximately 14.8% boron.

In another example the above mixture was heated on a hot plate for 25 minutes to a temperature of approximately 80 degrees Celsius at which the boron compounds were fully dissolved and formed a slurry. A quantity of the dry mixture was mixed with the slurry to thicken it to a consistency suitable for extrusion.

Once the slurry has been produced, known extrusion techniques may be utilised to produce the tablets. Thus the extruder may have a variable diameter die to produce extrusions of differing diameter and the extruded length can be fed onto a conveyor belt in known manner and conveyed to a cutting station for severing into tablet lengths.

In use a tablet is inserted in a hole drilled in the end grain of timber and is suitable for use in window frames, pergolas, decks and other exposed timbers. The boron compounds processed in accordance with the invention form a diffusible chemical which diffuses through the timber in dependence on the moisture content of the timber.

The production process in accordance with the invention has been found to produce an effective preservative utilising little heat input. Without the addition of water to the dry mixture a slurry is produced which sets quickly thereby simplifying production methods and reducing the time required for production.

A preservative produced in accordance with the invention does not have the toxicity of preservatives including fluorine derivatives and depending on the dampness of the environment of use should have an active life of up to 10 years before having to be replaced. A tablet made in accordance with this invention has a very stable shelf life and is odourless and non-inflammable.

It will of course be realised that whilst the above has been given by way of an illustrative example of this invention, all such and other modifications and variations hereto, as would be apparent to persons skilled in the art, are deemed to fall within the broad scope and ambit of this invention as is hereinafter claimed.

Claims

1. A process for the production of a preservative, said process including:- preparing a dry mixture of a hydrated boron compound and a non-hydrated boron compound, and heating said mixture to a temperature greater than approximately 65 degrees Celsius to form a slurry.

2. A process as claimed in claim 1, wherein said slurry is extruded to form a predetermined shape.

3. A process as claimed in claim 2, wherein said hydrated boron compound is a sodium tetraborate and said non-hydrated boron compound is boric acid.

4. A process as claimed in claim 3, wherein said sodium tetraborate and said boric acid are mixed in a ratio by weight of between 1:1 and 6:1 respectively. i:

5. A process as claimed in claim 4, wherein said ratio is substantially 3:1.

6. A process as claimed in claim 2, wherein said S. 25 mixture is heated to a temperature of between approximately 65 and 85 degrees Celsius.

7. A process as claimed in claim 6, wherein said mixture is heated to a temperature of between approximately 77 and 81 degrees Celsius.

8. A process as claimed in claim 7, wherein said mixture is heated to a temperature of approximately 79 degrees Celsius.

9. A process as claimed in claim 2, wherein a hydrated boron compound and/or a non-hydrated boron compound is mixed with said slurry.

A process as claimed in claim 2, wherein said mixture is heated by microwave means.

11. A preservative produced by a process as claimed in claim 2.

12. A preservative as claimed in claim 11, wherein the preservative contains approximately 14.8% boron.

13. A preservative as claimed in claim 12, wherein said preservative is in the form of a tablet or pellet.

14. A process for the production of a preservative, said process including:- preparing a dry mixture of a hydrated boron compound and a non-hydrated boron compound; heating said mixture to form a slurry, and extruding said slurry to form a predetermined shape. e *0 *0:0 ooo •I ABSTRACT A process is described for the production of a preservative, in which a dry mixture of a hydrated boron compound and a non-hydrated boron compound is heated to form a slurry. e* o a 6