AU636079B2 - Production of shaped bodies - Google Patents

Description

Y

P/00/0011 Regulation 3.2

AUSTRALIA

COMPLEPatents 7 COMPLETE SIQCMQcrMx FOR A STANDARD PATENT

ORIGINAL

*o Name of Applicant: Actual Inventor(s): SANEISH PTY. LTD.

CHIN, Chen-Woo McEVOY, Christopher Norman Address for service in Australia: e CARTER SMITH BEADLE, Qantas House, 2 Railway Parade, Camberwell, Victoria, 3124, Australia, Attorney Code SA.

Invention Title: PRODUCTION OF SHAPED BODIES Details of Associated Provisional Applications: No: PK 5605 The following statement is a full description of this invention, including the best method of performing it known to me/us.- 1 -2- TECHNICAL FIELD This invention relates to the production of compounds which have fungicidal and insecticidal properties and their use in wooden or timber structures to combat fungal and insect deterioration.

BACKGROUND OF THE INVENTION The service life of wooden structures is greatly reduced by biodegradation processes caused by fungal decay such as soft rot, white and brown rot and attack by insects such as damp wood and dry wood termites. It is therefore desirable to treat wooden structures S1O in some way to combat biodegradation to greatly increase their service life.

It has been found that the service life of wooden structures can .oooo be considerably increased if they are inspected regularly and given remedial chemical treatment. Various methods of remedial treatment of wooden structures have been used and include the pouring of treatment liquids such creosote onto the external surface of the wooden structure or the application of bandages containing preservatives. While both of these methods are effective, they have gained only limited acceptance because they are messy and much of the chemical is lost to the environment.

The introduction of diffusible biocides into the interior of a pole should be an effective way of preventing or delaying deterioration but bc\a3\1051 .au 924 9 -3this method has not become a routine procedure because materials and a delivery system which is cost effective are not available.

Australian Patent No. 527,240 discloses the use of a fused monolithic body of boric oxide which dissolves over an extended period into the moisture present in the wood structure to form a solution toxic to organisms responsible for decay. As the shaped monolithic bodies are formed by a melt extrusion process in excess of 10000C, practical processing problems arise and the use of these bodies has consequently not gained wide acceptance, due to their [0 high cost. In addition they are extremely slow release and can take *:many years to fully dissolve even in wood with moisture content in excess of °e o 3 United States Patent No. 4,661,157 discloses the use of boron compounds capable of binding with water by hydration to form shaped bodies. The hydration of boron compounds by the method in the above U.S. Patent occurs quickly and results in a product relatively low in density and strength. The above patent suggests the mixing of the boron compounds with various carrier materials to increase the strength but this also has the effect of reducing the relative proportion of active ingredients in the rods and consequently the effectiveness of the shaped bodies.

SUMMARY OF THE INVENTION bc\a3\10510.au 9249 -4- The applicant has found that a stronger and denser rod can be formed by the hydration of a mixture of boron and fluorine compounds. Accordingly the invention provides a process for the production of a shaped body for use as a wood preservative insert comprising the steps of mixing together at least one hydratable boron compound and at least one fluorine compound, to form a dry mixture and adding water to said mixture to form a paste, shaping the paste and allowing the paste to set to form the shaped body, said shaped body being substantially free of polymeric components. T h e o addition of the fluorine compound which is itself a biocide enables the *•lo hydration reaction to be more easily controlled. A slower rate of reaction and longer reaction time results in a denser and stronger shaped body. Consequently, additive materials are not required to increase the strength or density of the shaped bodies but may be added if required.

Fluoroborate complexes are also produced by the reaction of boron compounds with fluorine compounds. The complexes are also capable of hydrating and have the advantage of exhibiting lower mammalian toxicity.

After the paste is shaped it may be cooled to slow the rate of the hydration reaction to a rate which will provide a product with the desired properties. Ey controlling the rate of hydration the final saneish2.spe\pjd 9325 strength and density properties of the shaped bodies can be controlled.

In accordance with another aspect of the invention, there is provided a shaped body for use as a wood preservative insert comprising at least one boron compound and at least one fluorine compound.

The boron compounds are preferably at least one of the group comprising disodium octoborate, borax (disodium tetraborate *e decahydrate), disodium metaborate tetrahydrate, boric acid, and zinc borate.

The fluorine compound is preferably at least one of the group comprising sodium fluoride, zinc silico fluoride, potassium fluoride, "ammonium hydrogen fluoride, magnesium silico fluoride, and potassium hydrogen fluoride.

1 In a further aspect, the present invention further provides a shaped body for use as a wood preservative insert comprising at least one boron compound and at least one fluorine compound, said shaped body being produced by forming an aqueous paste of at least one hydratable boron compound and at least one fluorine compound, shaping the paste and allowing the paste to set to form a shaped body.

PREFERRED EMBODIMENT saneish2.spe\pjd 9325 5 It is preferred that the proportion of boron compound to fluorine compound is in the range of 2:1 to 3:1.

The foregoing and other features objects and advantages of the present invention will become more apparent from the following description of the preferred embodiment.

The shaped bodies in accordance with the invention are produced by first mixing a boron compound which is capable of hydrating with a fluorine compound. The boron compound preferably a a.

4* S saneish2.spe\pjd 9325 -6is at least one of the compounds in a group comprising disodium octoborate tetrahydrate, borax (disodium tetraborate decahydrate), disodium tetraborate pentahydrate, sodium metaborate tetrahydrate, boric acid and zinc borate, with disodium octoborate tetrahydrate being the most preferred.

The fluorine compound is preferably at least one of a group comprising sodium fluoride, zinc silico fluoride, potassium fluoride, ammonium hydrogen fluoride, magnesium silica fluoride and potassium hydrogen fluoride with sodium fluoride being the most preferred. Sodium fluoride has a lower water solubility and therefore will provide longer term protection to the wooden structure than a boron compound alone.

The ratio of the boron compound to the fluorine compound is in the range of 2-3:1 with a preferred ratio of 2.4:1.

::18 To the dry mixture a structuring agent may be added such as fumed silica, clay, bentonite, colloidal or calcium carbonate in an amount from 0.05 to 0.5 wt% based on the wt of dry mixture.

Preferred colloidal calcium carbonate of 0.1 wt The powder phase is then mixed thoroughly for up to 5 minutes (preferably 2 minutes).

Prior to the water being added to the powder mixture, a wetting agent is added to the water to form the water phase and allowed to bc\a3\10510.au 9249 -7age for a minimum of 1 hour. The wetting agent may be a nonionic, cationic or anionic type and added in an amount of between 0.01 to 0.1 wt% based on the amount of water. The preferred wetting agent is Lutensit APS added in an amount of 0.05 wt%.

Immediately prior to adding the water phase into the premixed powder phase, its temperature should be within the range of 10-400C preferably 300C.

The water phase is then added to the powder phase in a ratio between 2:1 to 4:1 (preferably 2.8:1) and mixed for about 1.0 minutes (preferably 4 minutes). The mixing time allows sufficient time for the hydration reaction to take place and due to the exothermic nature of the reaction, an increase in mixture temperature is experienced.

The mixture in the form of a watering paste is then immediately poured into split plastic moulds.

As the temperature of the mixture and the rate of hydration within the split plastic moulds can have an effect on the final strength of the product, the filled moulds are immediately transferred to a cold room operating at a temperature in the range of about 1 10°C and preferably 30C. By transferring the moulds to the cold room, the hydration reaction is slowed down and the temperature increase of the hydrating mixture is reduced.

bc\a3\10510.au 9249 I -8- The presence of the fluorine compound slows the rate of hydration of the boron compound to a level whereby the reaction can be adequately controlled to produce a consistent product utilising this simple process.

Solidification of the product follows after the hydration reaction is substantially complete and optimum hardness of the shaped bodies ,z achieved after a minimum of two hours in the cold room.

The split plastic moulds are preferably manufactured by a vacuum forming process from a PVC plastic of about 0.25 1.00 mm thick. Plastic backings are glued to the moulds to provide rigidity S2. strength and flexibility. Locating lugs are built into each half of the mould to ensure the correct lining up of each shape. The moulds are paired then claranped together in banks of 30 to 40 sets prior to filling.

The products produced from the moulds are preferably rods of diameter ranging from 5 mm to 25 mm with length of 10 mm to 200 mm.

The principle elements required for any biodegradation of wood structure are moisture (generally above about 20%) nutrients and air.

Consequently wood structures are most susceptible to fungal decay and termite attack at the ground level.

To treat a wooden structure using the shaped bodies of the present invention abaxial holes are drilled in the structure starting bc\a3\10510.au 9249 -9above the groundline and extending to below the groundline.

A number of shaped bodies preferably as rods are inserted into each drilled hole and the holes are then sealed.

The moisture in the wood at ground level, slowly dissolves the chemicals in the rods and these chemicals are absorbed into the wood to prevent fungal decay and termite attack.

bc\a3\10510.au 9249

Claims (12)

1. A shaped body for use as wood preservative insert comprising at least one boron compound and at least on6 fluorine compound, said shaped body being substantially free of polymeric components.

2. The shaped body in accordance with claim 1 wherein said at least one boron compound is selected from the group comprising disodium octoborate, borax, disodium metaborate *e disodium tetraborate, boric acid and zinc borate. 0

03. The shaped body in accordance with either of one of claims 1 or 2 wherein the at least one fluorine compound is selected S-from the group comprising sodium fluoride, zinc silico fluoride, potassium fluoride, ammonium hydrogen fluoride, magnesium silico fluoride and potassium hydrogen fluoride. i5 4. The shaped body in accordance with claim 1 wherein the ratio of boron compound to fluorine compound is in the range of between 2:1 to 3:1. The shaped body in accordance with claim 1 further comprising a structuring agent.

6. A process for the production of a shaped body suitable for use as a wood preservative insert comprising the steps of mixing together at least one hydratable boron compound and at least one sanelsh2.spe\pjd 9325 -11 fluorine compound to form a dry mixture adding water phase to said mixture to form a paste, shaping the paste and allowing the paste to set to form a shaped body.

7. The process in accordance with claim 6 wherein the strength of the shaped body is controlled by allowing the paste to set in an atmosphere at a temperature between about 1 to

8. The process in accordance with claim 6 wherein the water phase also comprises a wetting agent.

9. The process in accordance with claim 6 or 8 wherein the boron compound is selected from the group comprising disodium octoborate, borax, disodium metaborate, disodium tetraborate, boric acid and zinc borate.

10. The process in accordance with claim 6 or 8 wherein the fluorine compound is selected from the group comprising sodium fluoride, zinc silico fluoride, potassium fluoride, ammonium hydrogen fluoride, magnesium silico fluoride and potassium hydrogen fluoride.

11. The process in accordance with claim 6 or 8 wherein the ratio of boron compound to fluorine compound is in the range of 2:1 to 3:1.

12. A shaped body for use as a wood preservative insert comprising at least one boron compound and at least one fluorine compound, said shaped body being produced by forming an aqueous saneish2.spe\pjd 9325 t .£yLo~ 12- paste of at least one hydratable boron compound and at least one fluorine compound, shaping the paste and allowing the paste to set to form a shaped body.

13. A shaped body for use as a wood preservative substantially as hereinbefore described with reference to the preferred embodiment.

14. A process for the production of a shaped body substantially as hereinbefore described with reference to the preferred embodiment. DATED this February 5, 1993 CARTER SMITH BEADLE Fellows Institute of Patent Attorneys of Australia "':Patent Attorneys for the Applicant: SANEISH PTY. LTD. 0. saneish2.spe\pjd 93 13- ABSTRACT The invention disclosed is a shaped rod for use as a preservative insert for wooden structures and a process of producing those rods. Water is added to a dry mixture comprising at least one boron compound and at least one fluorine compound and the resulting hydration reaction is controlled to produce the required properties in the resultant wood preservative insert. 0e *see o* 0 0 o ft bc\a3\10510.au 9249