CA1240833A - Process for treating wood as well as product for treating wood - Google Patents

Abstract

ABSTRACT

The invention relates to treating wood with a wood preservative by applying in one or more recesses made in the wood solid-material together with the wood preservative in such a way that the solid material fills up the recesses at least partly, said solid material having a lower water content than the wood treated and exerts a reinforcing effect upon this wood, when it absorbs water and in result expands and/or when a permanent pressure is exerted upon it.

Furthermore, the invention relates to products to be used for this treatment, with which by one single act the filling-up of a recess in the wood to be treated and the closing thereof can be effected.

Description

~L2~8~3 The invention relates to a process for treating wood in which a wood preservative as inserted into one or more recesses made in ~ood, whereupon these recesses are closed ou-twardly.
The treatment of wood with a wood preservative aims at protecting the wood preventively or curatively against attack by moisture, micro-organisms (for ins-tance Basidiomycetes, Ascomycetes, Fungi Imperfecti, etc.), insects (for instance Hylotropes bajulus L., Anobium punctatum, Lyctus brunneus Steph., etc.), termites (for instance Calotermes flavicollis, Reticultermus Luciferus Rossi) and bacteria.
A similar process is generally known. Preferably a capsule is used.
The process followed is then that first a hole is drilled in the wood, subsequently a glass capsule with the wood preservative is inserted into it and finally the driliing hole is closed with a plug, which is applied in it in a recess, in result of which the capsule breaks and its contents are freed and spread in the wood.
A drawback of this process is that wooden beams, window-frames, etc.
forming part of supporting structures or wooden elements which are regularly charged, are weakened as a consequence of the remaining holes.
Another drawback is that the user of the capsules when breaking the capsules may come into contact with the con-tents thereof.

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~2~L~8~3 This may rappen because the plug does not close well or because the capsule is not positioned deep enough in the shallow drilling hole.
I t has a I so been suggested to app I y a wat0r repel I Ing agent In the recess.

In European patent application 81 108689.1 (published under No. 0050839) it is elucidated that the use of a water e~pellent 10 agen-t gives very great problems in practice with wood aiready painted. Not only is the expulsion of moisture strongly interfered with, but there also is a chance that locally the moisturê content will increase as a xesult of the water expellent agent. If it rises above the cri.ical value of 21 % a chance of wood attack by 15 developent of wood decay fungus is very great. Also~ the paint system can be damaged as a result of moist accumulation on the surface o~ the wood. That is why in the European patent application it is proposed to apply a solution of a water binder in an organic solvent in recesses of a wooden product. In result 20 hereof the objection of moisture accumulation is removed, but the application of a water binder has the drawback that the active substances which have to prevent wood attack, are locked up, in consequence of which a good penetration hereof in the wood is reduced. Consequently, also here the object aimed at, to wit 25 prevention and combating, resp., of wood attack by micro-organisms, insects and bacteria is not fully achieved.

The invention provides a process which meets the above-mentioned drawbacks.
According to the invention in a process as mentioned at the beginning a solid material is applied in the recess together with the wood ?reservative in such a way that this solid material at ' ~2~a!833 least partly fills up the recess, said solid material having a reinforcing effect upon this wood when it absorbs water and expands in consequence thereof and/or when a permanent pressure is exerted upon it.

Preferably, also wood is applied having a lower water content than the wood treated, most preferably resin-free splint-wood or heart-wood. Splint-wood is young wood and has a less resin-rich cell structure than has for instance heart-wood. This property is of importance in view of the absorption capacity of the wood and the capacity to absorb free liquid. By applying wood for this which has been freed from resins and other fillers, this êffect is not only strengthened, but it is also prevented that chemical reactions between the wood preservative substances and these resins and other fillers can occur.

It is preferable to apply the wood material that is applied in the recesses of the wood to be treated in such a way therein that the wood preservative present therein is released in the direction of the fibres of the wood material applied. - So that means that the fibre direction of the wooden plug is the radial direction so that the fibre direction is the same as that of the surrounding wood. This does not only give the big advantage that the delivery of the wood preservative to the surrounding wood is accelerated, but also that it also distributes itself more uniformly in the surrounding wood. In consequence the chance of problems in painting the wood over is reduced.

Owing-to the process according to the invention a material being applied in the recesses together with the wood preservative having a lower water content that the wood treated, the wooden plug will start absorbing water after application and in result expand more than the directly surrounding wood shrinks. In result a reinforcing 3~

eîfect is exerted upon the surrounding wood.

It is generally known that by nature wood contains water. This water can be present in two forms, to wit bound to the cell walls, the so-called inhibition water, and as free water in the cell cavities and vessels. This water is usually indicated as capillary or occlusion water. This water is present only if the cell walls are completely saturated. ~hen drying wood first the free water disappears from the cell cavities. In for instance deal the moisture bound, in other words the inhibition water, amounts to about 29 ~ at a maximum. In drying at a relative humidity of 80 a a wood hu~idity of about 17 % is created, at which a shrin~age of 1.25 ~ in radial and 0.1 ~ in the ribre direction occurs.

A deal pi~g, which is pxovided with a wood preserving organic agent anc a moisture content of about 10 a, will expand after application in the wood to be treated which is in constant contact with the c?en air and in result thereof has a higher moisture content. rn addition to the reinrorcing effect this has on the surroundieg wood also a stabilising effect occurs because the moisture content o~ the plate treated decreases. This is in particular important for critical spots sensitive to wood attack.
For if here the moisture content will surpass 21 a the chance that the wood aecay fungi most occurring in Europe, such as Polystict-s versocolor, Coniopohra Puteana, Gloephillum tradeuy are develo?ed, is very great.

The invencion also relates to a product for treating wood, comprising a wood preservative, optionally packed in a wrapping of prctective material, wllich wrapping is smashed up upon exertion of pressure from insi~e, said ?roduct being characterized in that that an absorbing material having a moisture content below 16 ~ which expand on absorption of water, is present. It is preferable to have the absorblng materlal conslst of wood, most preferably spllnt wood. Also cork Is consldered because It Is a blt comPresslble.
For If no protec~ing wrapplng Is applled It Is advantageous to have the product accordlng to the Inventlon whlch Is applled In a recess of wood to be treated, taper a blt, so that the dlameter of the portlon of the plug whlch closes the recess present In the wood to be treated from the outslde Is somewhat larger than the bore-hole. For In consequence thereof the plug Is anchored even more flxedly and no wood protectlve agent or glue whlch Is pre-sent In the plug, can escape along the plug. If one wlshes toglue the plug In the recess, one applles glue at the head of the plug and/or along the plug. By provldlng the plug wl th a recess, any excess of the glue Is caught hereln~ so that the glue cannot come Into contact wlth palnt applled on the outslde of the plug.
16 In result thereof dlscoloratlon of the palnt Is prevented.

In a preferred embodlment of the wooden plug one also sees to It that the portlon of the plug applled In the recess last Is not oversaturated wlth the wood protectlve agent. Thls Is of great Importance In applylng the plug for the sake of secu-rlty of the users. Also, thls has the great advantage that the wood protectlve agent cannot splash or run off after openlng the packlng or can run off In open seams of wlndow frames.

In order that one does not meet wlth problems when palntlng the wood treated over, the Impregnated plug can be pro-vlded on one end wlth an Impermeable medlum, for Instance a gal-vanlzed wood screw, whlch closes the whole borlng hole openlng when applled. It Is also posslble to apply a non-Impregnated plug on one end whlch by means of a compresslble sealIng dlsc for Instance of alumlnlum foll Is separated from the Impregnated por-tlon.

The Inventlon Is further Illustrated by way of the accompanylng drawlngs In whlch:-Flg.s 1 to 9 are vertlcal sectlons through plugsaccordlng to varlous embodlments of the presènt Inventlon.

The plug accordlng to Flgure 1 substantlally conslsts of absorbent materlal havlng a low water content, for Instance cork, wood flour, wood shavlngs, etc. Portlon 1 Is not Impreg-nated wlth a wood protectlve agent.

Portlon 2, however, Is Impregnated wlth the wood preservatlve. Both portlons are mutually separated by a fllm of compresslble materlal 3, whlch may for Instance conslsts of a remalnder of the packlng materlal In whlch the plug was packed before use or of glue or resln. Partltlon 3 prevents the wood preservatlve In the Impregnated portlon 2 from penetratlng In the non-lmpregnated portlon 1, when In applylng the plug In a recess of wood pressure Is exerted on portlon 1. If In the absorbent materlal a glue Is present, the glue runner 4 sees to It that any excess of glue present cannot escape outwards.

When the plug of Flgure 1 Is Inserted Into a recess and a pressure Is exerted from outslde, the Impregnated portlon clamps In that non-pregnated portlon.

In the embodlment accordlng to Flgure 2 the connectlon Z5 between the non-lmpregnated and Impregnated portlons Is realIzed by means of a galvanlzed headless Iron screw 5. Also a screw made of plastlc materlal, for Instance polyurethane, Is con-sldered.

In the embodlment accordlng to Flgure 3 the connectlon between the non-lmpregnated portlon and the Impregnated portlon of the absorbent materlal Is effected by means of a bayonet catch. By uslng a sprlng 6 on the InsIde and a compressIble packlng, both portlons can expand wlthout the total length of the plug belng Influenced. Thls Is of great Importance In vlew of the stablllty of the plug ~,4al8~

in the wood and for a paint layer applied thereover.

In the embodiment according to figure 4 use has been made of a plastic compressible glue layer 7. Because hereof the packing material 3 closing the impregnated portion need not be compressible.

In the embodiment according to figure 5 use is made of a glass capsule 8, to which a non-impregnated plug 1 has been screwed. A
sealing ring 11 made of for instance cork with aluminium foil or rubber sees to it that the wood protective agent in the impregnated portion 2 cannot diffuse in the portion 1. When smashing in this capsule the glass wrapping breaks and the broken glass and' the absorbent material are impressed in such a way that the whole boring hole is filled up completely all the same. After some time the absorbent mass will expand by moisture absorption from the surrounding wood and extra reinforce the whole.

Figure 6 also relates to an embodiment with a glass wrapping. In this embodiment a galvanized iron screw 9 is present. When placing the capsule the screw will smash the glass wrapping and will in consequence be anchored fixedly in the surrounding absorbing material. This embodiment has the advantage that no glue need be used, whilst moreover no wood protective agent can escape along the screw. There is no chance of splashing when applying the capsule either. The whole can be finished with a wood repair agent, so that also the substrate for the paint system to be applied over it is fully suitable for applying the paint over it.

In the embodiment according to figure 7 use is only made of an impregnated plug 10 which is reinforced with nylon or galvanized gauze. Also this offers the advantage that no contact between the wood protective agent and the user can take place. The layer of sealing material 3, which for instance can consist of aluminium 3L2~8~3 I

foil reinforced with paper prevents the wood protective agent from penetrating towards the paint on the outside of the wood treated.
This effect can even be reinforced by finishing the whole with a two-components glue, which is impermeable to polar and apolar organic liquids.

In figure 8 use is again made of a galvanized iron screw, which is screwed in the impregnated portion of the absorbent material. By applying on the other end of the compressible material a compressible foil 3, the plug can expand without the total length of the whole product being longer. This foil does see to a reinforcement of the whole.

In the embodiment according to figure 9 use is made of a flat screw 9 of galvanized iron or a plastic and a closed capsule of glass. The capsule is surrounded by a thin foil of plastic, for instance polyethylene foil or of polyvinylchloride foil. The whole is constructed such that after application of the glass capsule in the boring hole the capsule can be smashed by screwing the screw on. In case of a correct selection of the contents of the capsule, to wit by seeing to it that an organic liquid is present therein, in which the foil of plastic surrounding the glass capsule initially, dissolves, the wood protective agent can penetrate the wood to be protected.
Instead of with a plastic foil ,he capsule with screw can also be wrapped in nylon or galvanized gauze (8). Also this packing need not be removed, no more than a wrapping of plastic ~oil before applying the capsule in the boring hole. This embodiment has the advantage over the known capsule, the wrapping of which consistS
wholly of glass, that a-ter inserting the capsule into the boring hole, the screw applied as closure is inserted into the boring hole simultaneously with the capsule. ~hen using the known capsule5 ~2~a0~3~3 after application of the capsule for closing the boring hole a closing plus is to be applied in a separate act. It then could happen that such a plug was inserted after it had been forgotten to apply first the glass capsule. This is impossible when applying a closing screw, which is applied integrally with the capsule.
Figure 10 relates to an embodiment in which use is made or a unit consisting of a sealed capsule (8) of smashable material, for instance glass, filled with a solution of a wood preservative and a plug (1) of material impermeable to wood preservative, for instance heart-wood, fixedly connect herewith for instance by glueing. If the plug consists of hardwood, in particular of European oak, the plug moreover does not deform in smashing. When the plug is internally provided with a cavity (12) into which a protruding portion (13) of the sealed capsule fits, yet a relative large amount of wood preservative can be taken up into the unit, although a large part of the length of this uni-t is taken by the plug. This is in particular of importance when treating wood structures having a smaller thickness, for instance window-frames.
In general it is advantageous to select the wrapping material of the capsule, for instance the glass such that it does not transmit ultra-violet light. This promotes the keeping qualities of the wood preservative present in it.
Figure 11 relates to a variant of the connection of the plug with the capsule according to figure 10. Between the plug (1) and the collar of the capsule 8 there is an elastic ring 14, for instance of rubber or plastic, whose lower side has an opening of a somewhat smaller diameter than the drilling hole. Preferably this ring is O-shaped. The presence of this ring sees to it that the plug (1) is automatically centered, which is important in automized production. The ring may not be too thick, + 1 mm, because other-wise the ampulla can hardly be broken.

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The plug 1 generally acts wa-ter controlling. After application it absorbs water, but after the wood preservative has penetrated into the wood to be protected, the plug can again release water, if the surrounding wood dries up.
It is also possible to process the products shown in figures 1-10 into dowels made of wood, e.g. beech, European oak or merbau wood.
Dowels are used for accomplishing pin hole connections between wooden paxts, e.g. of window-sills, windows and do~rs. In general such dowels have a himidity content of less than 106 by weight.
If the dowels known per se (vide e.g. figure 12) are provided with a pre-drilled recess, which possibly is extending over the entire length thereof a product according to one of the figures can be introduced into that recess, whereupon the recess is sealed by a wooden plug (or two plugs if the recess is extending over the entire length). This is shown in figure 12. In this figure 15 represents a dowel into which a recess 16 having a diameter of e.g. 16 mm and a length of 100 mm has been drilled over the entire length. Into said recess a product, e.g. according to figure 10, has been introduced, while the open ends of the recess 15 are sealed by wooden plugs 17, which are provided with guiding edges 19.
As soon as the dowel is applied for connecting wooden parts the plugs are pressed inwardly. The dowel is longitudinally provided with small grooves for distributing the glue, by means of which the dowel is glued in the wooden parts. The wood preservative is distributed into the surrounding wood immediately when the ampulla is smashed when the wooden plugs take up water. This can take place via the dowel or through the plugs, dependent on the kind of material chosen, e.g. the kind of wood or synthetic material, combined with each other or not.
It is also possible to provide the plug(s) beEorehand with recesses, so that the wood preservative can spread more easily or earlier in the surrounding wood.

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It appeared to be advantageous, particularly when placing the ampulla in horizontal bore-holes in the wood, to provide the plug made of wood or another material with parallel pitches. For if an excess of pressure develops at a high degree of filling of the ampulla it could happen that some liquid is pressed outside along the plug. When parallel pitches are present in the plug in each pitch a separation between gas and liquid takes places, the gas being gathered in the upper portion of each pitch when the plug's position is horizontal. So the gas can escape from the upper portion of the horizontal plug along the plug, so that the excess of pressure disappears and the danger of liquid filtering through is prevented. To elucidate this reference is made to figure 13. Figure 13 relates to a plug with parallel pitches 23 which are bevelled in respect of the plug axis. Besides an extra provision is made in this plug in order to prevent filtering through of liquid after placing the ampulla in the wood to be preserved. The plug is provided with a stopping edge 20 having a diameter which is somewhat larger than the other part of the plug. In order to apply the above described plug a special, adapted form of the bore-hole is required.
This can be obtained by drilling a hole first to standard depth, after which the first part of the bore-hole is drilled to the desired size with a drill having a larger diameter.
In the shown plug under the stopping edge (20) an annular space 21 is left blank to take up glue, when the stopping edge is provided with a layer of adhesive to glue the ampulla in the wood to be preserved.
The hollow space 22 has been left blank to insert the upper portion of the ampulla therein.
Finally, it is remarked that the expression wood preservative is to be understood in the broadest sense. Also agents, which as such do not exert a killing effect on living organisms, but see to a medium in which living organisms cannot multiply are meant. For instance, ~2~ 33~

a solution of paraffin in an organic solvent can be applied. When this solution penetrates into the spaces between the wood fibres and the organic solvent evaporates partially, the paraffin remains in the spaces, in result of which no living organisms can develop therein.

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for treating wood having at least one recess, comprising inserting a wood preservative and a solid material having a lower water content than the wood into said at least one recess in the wood so as to at least partially fill and outwardly close the at least one recess, whereby the solid mate-rial exerts a reinforcing effect on the wood when water is absorbed by the solid material.

2. A process according to claim 1, wherein the solid material is resin-free splint wood or heart-wood.

3. The process according to claim 1, wherein the solid material has fibers and the wood preservative is impregnated in the solid material and is delivered to the recessed wood in the direction of the fibers of the solid material.

4. The process according claim 3, wherein the solid material is resin-free splint wood or heart-wood.

5. A process according to claim 1, wherein the wood preservative and solid material are encapsulated in a smashable material and wherein the process further comprises smashing the capsule after insertion of the capsule into the at least one recess.

6. The process according to claim 5, wherein the smashable material is glass.

7. The process according to claim 1, wherein the wood preservative is present as a solution in a capsule of smashable material and the solid material is present at one end of the cap-sule, said one end disposed at the surface of the recess and wherein the process further comprises the step of smashing the capsule by forcing the solid material into the capsule after insertion of the capsule into the at least one recess.

8. The process according to claim 7, wherein the smashable material is glass.

9. A product for the treatment of wood comprising an absorbent material having a wood preservative impregnated portion and a wood preservative non-impregnated portion and the wood preservative impregnated portion is separated from the non-impregnated portion by means of a compressible sealing disc.

10. A product consisting of a capsule of smashable material having at least a wood preservative and a solid material therein.

11. A product consisting of a sealed capsule of smash-able material having a solution of wood preservative therein and a plug of wood preservative impermeable material affixed on top of the capsule.

12. The product according to claim 10, wherein the absorbent material has a moisture content of less than about 16%
by weight and whereby the absorbent material expands in the pres-ence of water.

13. The product according to claim 10 or 11, further comprising a screw adapted to smash the capsule when the capsule is placed in a recess in wood to be treated.

14. The process according to claim 10, wherein the smashable material is glass.

15. The process of claim 11, wherein the wood preserva-tive impermeable material is heart-wood.

16. The product according to claim 9, 10 or 11, mounted in a dowel.