AU598911B2 - Treatment of timber - Google Patents

Description

Australian attorney THE COMMISSIONER OF PATENTS This form must be accompanied by either a provisional specification (Form 9 and true copy) or by a complete specification (Form 10 and true copy).

COMMONWEALTH OF Patents Act AUSTRALiA 1952 COMPLETE SPECIFICATION (Original) FOR OFFICE USE Application Number: PLO444 PI0489 Class Lodged: 19-2-87 23-2-87 Complete Specification Lodged: Accepted: Published: Priority: Related Art: Int. Class This document contains the amendments made under Section 49 and is correct for urintirip- 0 0 V o 00 0 o o 0 00 0 0 o o 0 0 0 0 0 0 0 0 0 0 0 o a a i~ St.

TO BE COMPLETED BY APPLICANT Name of Applicant: HERB-E-R--eeR-PERAT--- M I Address of Applicant: 57 Division Street, Welshpool, in the State of Western Australia, Commonwealth of Australia Actual Inventor: Stephen Joseph Retter Address for Service:- Wray Associates Primary Industry House 239 Adelaide Terrace Perth Western Australia 6000.

Complete Specification for the invention entitled: "TREATMENT OF TIMBER" The following statement is a full description of this invention, including the best method of performing it known to me:- 1 Li1 iIhM IAN I tstil 111,1111,1~1 1 11 4 ,-I11 i" -2 THIS INVENTION relates to the treatment of timber an din particular, treatment of timber with light organic solvent based treatment agents.

It is an object of this invention to provide a method of treatment of timber with light organic solvent based treatment agents which facilitate substantially complete penetration of the sapwood with the treatment agent without excess retention of the treatment agent at the conclusion of the treatment process.

In one form the invention resides in a method of treating timber with a light organic solvent based treatment agent, said method comprising placing the timber within a treatment chamber evacuating the treatment chamber 0° 0. introducing an inert gas into the treatment chamber oo so pressurising the treatment chamber with the inert gas, flooding the chamber with the treatment agent under pressure for a period of time, draining the treatment agent from the treatment chamber, evacuating the chamber to a pressure below atmosphere pressure and pressurising the chamber to atmospheric pressure using said inert gas.

In another form the invention resides in a chamber of cylindrical configuration having a treatment chamber at one end and a storage chamber at the other end said treatment and storage chambers being of substantially equal volume, means provided for evacuating the treatment chamber, introducing an inert gas into the treatment chamber, pressurising the treatment chamber and I transferring the treatment agent between the treatment and 1 storage chambers the free end of said treatment chamber having an opening associated with a closure, at least one trolley adapted to support a stack of timber and being movable into and out of the treatment chamber through said opening.

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~JNT i THE COMMISSIONFYR OF PAl ENTS Thbis fofmn Iiust be~ accoflpattIPd Iy ithii a1 wo(vImInhl s iiicatioii 0 oi m 9 and tim U'Copy) oi hy a Complete qwificaloim (Formt 10 ail it ,Copy, -3- The invention will be more fully understood in the light of the following description of one specific embodiment.

'ii The embodiment relates to a method of treating timber with light organic solvent based preservative agents. The method of the embodiment utilises a treatment chamber in the form of a cylinder which may be opened at least at one end in order that timber can be loaded into the chamber.

If desired, suitable trolleys may be provided which are supported on rails or tracks extending from within the treatment chamber through the one end to the exterior of the chamber. The trolleys are loaded and unloaded outside the chamber to facilitate rapid loading and unloading of 0 the treatment chamber. The treatment chamber is associated 0 with a storage vessel for said treatment agent which if desired may constitute an extension of the treatment 0 0 chamber and which has substantially the same volume as the treatment chamber. The treatment chamber and storage 0 00 chamber are associated with pumps to facilitate the A 04) o 0000transfer of treatment agent between the storage chamber and the treatment chamber. In addition, the treatment 0 chamber is associated with a vacuum pump and with a source of inert gas such as nitrogen.

According to the process of the embodiment, timber is so~o Cloaded into the trolleys outside the chamber and when stacking is completed the trolleys are moved into the treatment chamber. In loading the trolleys the timber is stacked on the trolleys in a manner to maximise gravitational drainage of any excess liquid from the surface of the timber. This is facilitated for example in the case of right angle finished timber by having the plane surfaces located at 450 to the horizontal.

c i- r- 4 On loading of the timber into the treatment chamber, it is thcn sealed and a vacuum of the order of 550-600 mm is applied to the interior of the treatment chamber for a period of the order of ten minutes. At the conclusion of that time, nitrogen gas is then introduced into the treatment chamber to a pressure of the order of 120 to 350 kPa. The magnitude of the pressure applied depends upon the properties of the timber being treated. In addition, the pressure in the storage chamber is substantially equalised to that within the treatment chamber and the treatment chamber is then flooded with the light organic solvent based treatment agent under pressure such that the timber within the treatment chamber is fully immersed therein. The pressure maintained in the treatment chamber above that existing therein under the influence of the nitrogen gas introduced previously by the liquid is in the order of 200 to 720 kPa (the magnitude depends upon the properties of the timber). The presence of the treatment agent under pressure within the treatment chamber is 20 maintained for a period of time and during that time, the penetration of the treatment agent into the timber is monitored by the rate at which liquid is pumped into the treatment vessel to maintain the required pressure.

0 93 00 9 0 3 6 00 6o 6 6 10 6 00 6o 6 6 60 At the conclusion of the treatment period, all the liquid within the treatment chamber is pumped to the storage chamber to reduce the pressure to that created by the nitrogen gas prior to flooding of the treatment chamber.

When empty a vacuum is applied to the treatment chamber which is of the order of 700 mm for a period of time in the order of 15-30 minutes. The effect of the vacuum is to cause the expelling of excess treatment agent from within the timber by the expansion of the nitrogen absorbed thereby prior to the flooding of the treatment chamber and facilitate the evaporation of any excess undrained solvent i! V

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remaining on the surface of the timber. When the drainage of the treatment agent from the timber appears to be complete, the pressure within the treatment chamber is then returned to substantially atmospheric pressure by the use of nitrogen gas. The treatment chamber is then opened and the load is removed and taken to a holding area to allow for any further evaporation of residual solvent from the timber. At the conclusion of the treatment process the storage vessel is replenished with treatment agent from bulk storage to the full capacity of the storage vessel.

0 The amount of treatment agent required to replenish the storage chamber can be measured to indicate the volume of So~ -treatment agent absorbed by the timber charge previously °o treated.

It has been found that timber treated according to the above process exits the treatment chamber in a substantially "dry" state and after a short period of time go s to allow for evaporation of any residual solvent the °00 timber is sufficiently dry for it to be used in whatever manner that may be required. In addition, it has been o0 found that the penetration of the treatment agent as a result of the process is substantially throughout the sapwood of the timber.

00 Because of the utilisation of the light organic solvent based treatment agent, it is necessary that all electrical and electronic installations and components used in relation to the apparatus be protected to prevent arcing or be suitably shielded and/or flame proofed to avoid -6 ignition of any of the treatment agent or any of the vapours produced thereby.

The embodiment described above has resulted in a relatively rapid treatment of timber and a treatment process which can produce substantially consistent results with a wide variety of timber types.

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment described above.

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Claims (10)

1. A method of treating timber with a light organic solvent based treatment agent, said method comprising placing the timber within a treatment chamber evacuating the treatment chamber introducing an inert gas into the treatment chamber pressurising the treatment chamber with the inert gas, flooding the chamber with the treatment agent under pressure for a period of time, draining the treatment agent from the treatment chamber, evacuating the chamber to a pressure below atmosphere pressure and pressurising the chamber to atmospheric pressure using said inert gas.

2. A method as claimed at claim 1 wherein on said treatment agent being introduced into the treatment chamber the pressure in the treatment chamber is increased above that existing in the treatment chamber prior to the flooding. o t3. A method as claimed at claim 1 or 2 wherein the inert gas comprises nitrogen.

4. A method as claimed at claim 1, 2 or 3 wherein the Ii treatment chamber prior to the introduction of the inert gas is subjected to a vacuum of the order of 550-600mm. A method as claimed at any one of claims 1, 2, 3 or 4 wherein the pressure in the treatment chamber after the introduction of the inert gas is of the order of 120- 0o 350k~a. 0 1

6. A method as claimed at any one of the preceding0 claims wherein the pressure maintained in the treatment o' 0 t S 1R NT -8- chamber on flooding is of the order of 200-72OkPa above the pressure of the inert gas prior to flooding.

7. A method as claimed at any one of the preceding claims wherein the vacuum in the treatment chamber after draining the treatment agent ana evacuating the treatment chamber is of the order of 700mm.

8. A method as claimed at any one of the preceding claims wherein the time period between evacuating the treatment chamber and pressurising the treatment chamber with inert gas prior to flooding is of the order of ten minutes.

9. A method as claimed at any one of the preceding claims wherein the time period between evacuating the treatment chamber and introducing the inert gas subsequent ~o to flooding is of the order of 15 to 30 minutes. A method substantially as herein described with reference to the embodiment.

11. An apparatus for treating timber according to the method as claimed at any one of claims 1 to 10 comprises a chamber of cylindrical configuration having a treatment chamber at one end and a storage chamber at the other end said treatment and storage chambers being of substantially equal volume means provided for evacuating the treatment OV chamber, introducing an inert gas into the treatment 0444 chamber, pressurising the treatment chamber and transferring the treatment agent between the treatment and storage chambers the free end of said treatment chamber having an opening associated with a closure, at least one trolley adapted to support a stack of timber and being movable into and out of the treatment chamber through said opening. la A7-- I 9

12. An apparatus as claimed at claim 11 wherein the at least one trolley is supported on a set of tracks or rails.

13. An apparatus substantially as herein described with reference to the embodiment. DATED this EIGHTEENTH day of APRIL 1990. HERBERT CORPORATION LIMITED Applicant. Wray Associates Perth, Western Australia, Patent Attorneys for the Applicant. 0 O 4 0 I 41~( /N4