Wood preservative

Details Wood preservative Wood preservative

1999-12-09

2001-06-19

Soderquist, Arlen (Department: 1743)

Compositions: coating or plastic

Coating or plastic compositions

Contains fireproofing or biocidal agent

C106S018320, C106S012000, C252S403000, C252S380000, C424S413000, C424S084000, C424S405000, C424S078090, C514S359000, C514S383000, C427S440000

Reexamination Certificate

active

06248159

ABSTRACT:

The invention relates to a wood preservative which is particularly suitable for the protection of wood against wood-attacking insects. The preservative contains the usual carriers and aids and is suitable both for the preventive protection of wood as well as for combating an existing outbreak.
For the protection of wood against destruction and quality impairment due to attack by injurious organisms, particularly insects and fungi, chemicals with biocidal action have been used extensively to combat the respective injurious organisms. Use also has been made of insecticides such as neurotoxins which have a non-specific action mechanism, and the potential to effect the environment adversely. For this reason, most of the preparations used so far have demonstrated more or less pronounced drawbacks as regards their environmental compatibility when inexpertly used.
There is therefore a great need for environmentally compatible wood protective agents which, in the event of inexpert use, reduce to the technically achievable minimum the danger of such agents to the health of operators and end consumers. The manner in which biological or biogenic wood preservatives has been used has not so far been seen to lead to an achievement of the aim. All the substances offered so far as “biological wood preservatives”, which contain, for example, balsam terpentine oil and wood vinegar have not been able to meet the demands made on wood preservatives. Particularly, against the main wood destroyers, the house longhorn (
hylotrupes bajulus
), woodworm (
anobium punctatum
) and bark beetle (
lyctus brunneus
), it is still necessary to use highly active chemicals.
The use of insect hormones against an insect attack has long been known from integrated plant protection studies. In particular, use has been made of analogues and mimetics of moult and cocoon hormones, that is, insect juvenile hormone analogues and ecdysone agonists. These agents, because of their hormonal character, are used in the lowest application concentrations, and are highly selectively insect active, the selectivity being so specific that only individual orders of insects such as beetles are covered, and useful insects in other orders such as hymenopters are very largely spared.
These agents have not yet been used in wood preservation, as this group of active substances had not yet been available and organo-chlorine insecticides and synthetic pyrethroids were popularly used for this purpose. In addition, as there were drawbacks still attached to the use of first generation insect hormonal analogues (higher steam pressure, hydrolysis instability), these agents did not come into consideration as wood preservatives.
The object of the invention is to provide a wood preservative which is at least equivalent to the preservatives being used currently and which meets present-day environmental compatibility and toxicology standards. The agent should be long-lasting and afford reliable protection, particularly against attack by wood-destroying insects. Furthermore, the wood impregnated with the agent should, after the useful life of the construction expires, be re-usable without problems or consequences for the environment.
The present invention provides a wood preservative which contains one or more insect hormones and/or their analogues or mimetics, which control egg development, moulting or cocooning of insects, in a concentration of 0.00005 to 0.5 weight %, based on the total weight of the composition. The composition also may contain triazole compounds, particularly triazole fungicides, the combination bringing about a synergetic effect.
According to the invention, insect hormones which may be used include juvenile hormones and ecdysone as well as their analogues and mimetics.
These hormones have an effect on the hormonal control systems of insects, controlling embryonal development in the fertilized egg, moulting in the larval stage, and, at the end of the larval stage, cocooning and development to the mature organism. As long as the juvenile hormone is present, the insect remains in the larval stage, with individual moultings being induced by additional ecdysis. After the drop of the juvenile hormone level at the end of the larval phase, ecdysis brings about cocooning.
The introduction of the insect hormone into the hormonal control system therefore may be used for combating harmful insects. It is known that juvenile hormones can have an ovicidal action. Furthermore, their action on the fully developed larva leads to an artificial prolongation of the larval stage, to excessive moulting and finally to the dying of the larvae. Use of ecdysone on insect larvae results in a number of spontaneous moultings and mostly to the dying off of the larvae. The use of an excessive amount of ecdysone and/or ecdysone agonist induces a forced premature cocooning and metamorphosis to deformed adult insects which are unable to reproduce. The targeted use of insect hormones disturbs or prevents the multiplication of insects either by ovicidal action or by interference with the formation of the mature insect. In addition, these insect hormones interfere also with the control systems of the mature insect and can set off malfunctions such as chemosterilization.
Along with the actual juvenile hormones and ecdysones a number of analogues and mimetics were developed which exert a comparable action upon the hormonal control systems of insects. Such analogues and mimetics include structurally related compounds, that is, derivatives of ecdysones and juvenile hormones, and also chemical compounds which in spite of being structurally different in nature have a comparable effect. A great number of analogues, particularly of the juvenile hormones, have been developed. According to the invention, the insect juvenile hormones and ecdysteroids, their mimetics and analogues, can be used alone or in combination. According to the invention, each of the hormones or its analogues or mimetics is present in an amount in the range of 0.00005 to 0.5 weight % based on the weight of the entire formulation. Preferably, the concentration of each hormone or active agent in the formulation is 0.001 to 0.005% b.w.
Juvenile hormone analogues suitable for use in the invention are:
Pyriproxyphene: 4-phenoxyphenyl-(RS)-2-2(2-pyridyloxy) propyl ether,
Fenoxycarb: Ethyl {2-(4-fenoxyfenoxy)ethyl} carbamate,
Kinoprene: 2-propynyl-(E)-3,7,11-trimethyl-2,4-dodecadienoate,
Methoprene: Isopropyl-(2E, 4E)-11-methoxy-3,7, 11-trimethyl-2,4-dodecadienoate,
Hydroprene: ethyl-(E,E)-(R,S)-3,7,11-trimethyldodeca-2,4-dienoate.
Of the above, pyriproxyphene and fenoxycarb are preferred juvenile hormone analogues.
Ecdysone agonists suitable for use are:
Tebufenozide: N-tert-butyl-N′-(4-ethylbenzoyl) propylether,
RH-0345®: halofenozide; benzoic acid, N-tert-butyl-N-(4-chlorobenzoyl)-hydrozide; a coleopter specific variant of tebufenozide,
RH-5849®: a tebufenozide analogue; N-tert-butyl-N-(4-ethylbenzoyl)-3,5-dimethyl benzohydrozide; a beetle specific alternative to tebufenozide
Azadirachtin or Azadiractanin.
Of the above, tebufenozide and RH-0345® are preferred ecdysone agonists. The use of a combination of two juvenile hormone analogues pyriproxyphene and fenoxycarb is particularly preferred. The two agents complement each other in their effect in optimum fashion in that fenoxycarb displays effectiveness against the wood-harming insects especially at the embryonic stage and during metamorphosis, while pyriproxyphene is effective also during the larval stage. The combination of these two agents makes it possible to attack insects during the entire period of insect development. The ovicidal action of fenoxycarb is particularly effective on the eggs of the house longhorn.
Also preferred is the combination of at least one juvenile hormone analogue with an ecdysone agonist as this combination imitates the natural prerequisites for the moulting of larva and mature insects independent of the developmental condition of the larva. The repeated, untimely moultings lead to a premature dying off of the larv

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