EP1998943A1

EP1998943A1 - Protection against mould attack on untreated timber

Info

Publication number: EP1998943A1
Application number: EP07716123A
Authority: EP
Inventors: Peter Af Klinteberg
Original assignee: Jape Produkter I Hassleholm AB
Current assignee: JAPE PRODUKTER AB
Priority date: 2006-03-18
Filing date: 2007-03-14
Publication date: 2008-12-10
Also published as: SE0600623L; EP1998943A4; RU2429118C2; WO2007108762A1; SE529154C2; RU2008137193A

Abstract

Means for temporary protection of untreated wood articles against mould attack, the means comprising quaternary ammonium salt as fungicide dissolved in an aqueous solvent and in the aqueous solvent suspended pigment, but not comprising binding agent or fungicide comprising boron or metal cation. Also disclosed is a corresponding method.

Description

Description PROTECTION AGAINST MOULD ATTACK ON UNTREATED

TIMBER Field of the Invention

[0001] The present invention relates to a means and a method for temporary protection of untreated wood articles against mould attack and wood articles treated with the protection means.

Background of the Invention

[0002] Wood articles of various kind, in particular prefabricated wood elements and wood- built houses and sections of wood-built houses manufactured in a factory are often delivered and assembled unpainted. The reason for this is mainly to enable an individual choice of colouration at the site of assembly. Another reason is that paint applied at the manufacturing site is at risk of being impaired during transport and that the damage have to be repaired at the assembly site at an extra cost as well as the risk of disturbing colour variations. Untreated wood articles are at risk of mould attack after use and assembly outdoors, respectively, unless they are immediately painted with a paint that protects them against mould attack. Painting on wood articles and timber already attacked by mould, which are comprised by the term "wood articles", with a paint protecting against mould attack is most often insufficient to kill mould and mould spores already present in the wood. At conditions favourable to mould formation and spread, i.e. damp weather at temperatures above 5 °C, mould attack can continue under the applied layer of paint and result in great damage.

[0003] Mould attack on wood articles intended for the specified use can actually be prevented by treatment with known wood preservatives. However, these wood preservatives are not intended to be painted on. If they are painted on there is a risk of the components in the wood preservative, e.g. copper salts, bleeding through, and of colour changes resulting from that. Furthermore, there is a risk of deterioration of the absorptive capability of the wood and thereby of paint adhesion and/or penetration into the wood.

[0004] By mould is meant herein all kinds of fungi growth on timber, such as blue discolouration, white rot and brown rot.

[0005] Salts of quaternary amines such as benzalkonium chloride are known for their mould killing and mould inhibiting properties. They are used in wood preservatives in combination with other mould inhibiting substances such as copper salts.

Objects of the Invention [0006] It is an object of the invention to provide a means that can be applied on wood articles intended for use or assembly outdoors, for temporarily protecting them against mould attack without affecting the property of the wood articles that allows the application of any paint at a later point in time without having to fear of damage of the paint and/or deteriorated adhesion.

[0007] It is another object of the invention to provide a method for treatment of wood articles for temporary protection against mould attack without affecting the property of the wood articles that allows the application of any paint at a later point in time without having to fear of damage of the paint and/or deteriorated adhesion.

[0008] Still another object of the invention is to treat wood articles correspondingly.

[0009] Further objects of the invention will become evident from the following description of the invention, a number of preferred embodiments thereof, and the appended claims.

Summary of the Invention

[0010] According to the present invention is disclosed a means of the aforementioned kind comprising a quaternary ammonium salt-type fungicide dissolved in an aqueous solvent, and pigment suspended in the aqueous solvent, but not comprising binding agent and fungicide comprising boron or metal cation. Preferably, the means of the invention comprises no fungicide other than the fungicide of quaternary ammonium salt-type, in any event not other fungicide in a total amount of more than 1 % by weight of the amount of quaternary ammonium salt.

[0011] The fungicide of quaternary ammonium salt-type according to the invention is preferably a trialkyl aryl ammonium salt with the alkyl residues R , R and R . It is

1 9 preferred that R and R are same or different C 1 -C 6 alkyl, most preferred that one or both of R and R are methyl. It is preferred that R is an alkyl residue four or more

1 9 carbon atoms longer than the longest of R and R , preferably a C 12 -C 18 alkyl residue.

According to a particularly preferred aspect of the invention, the fungicide is a mixture of at least two quaternary ammonium salts of aforementioned kind, differing in regard of the length of R , the share of quaternary amine with shorter R preferably being the larger one. The aryl residue is preferably phenyl or p-tolyl, most preferred phenyl. The salt is preferably a salt of an inorganic acid such as sulfuric acid, hydrochloric acid and hydrobromic acid. Most preferred is hydrochloric acid.

[0012] According to a preferred aspect of the invention the fungicide is one known by the trade name benzalkonium chloride, which is a mixture of quaternary ammonium salts of the aforementioned kind.

[0013] The aqueous solvent according to the invention is preferably water, but mixtures of water and of an alcohol chosen from methanol, ethanol, propanol, isopropanol and n- butanol is also preferred. [0014] The pigment according to the invention is a pigment is of low water solubility. By low water solubility is meant herein that the pigment contains less than 10 % by weight of leachable parts when 1 g thereof is extracted in 1 L of water for 24 h at room temperature. The pigment is a powder whose particle size can vary within wide limits, such as between 0.2 μm and 15 μm (weight average) and up to 30 μm and even up to 150 μm (weight average). The main function of the pigment is to protect the fungicide of quaternary ammonium salt-type against decomposition due to the action of UV light from solar radiation. Thus preferred is a pigment with high absorption capability for UV radiation and resistance against decomposition caused by the action of oxygen, light, moisture etc.

[0015] By binding agent is meant herein all kinds of agents that make the paint' s pigment particles cohere and agents forming paint layers with them, such as synthetic and natural resins, e.g. acrylates, polyuretanes, polyesters, melamines, acryl modified polysiloxanes, oils of synthetic and/or natural origin setting on contact with air, such as linseed oil, natural rubber synthetic rubber, etc.

[0016] According to the invention is also provided a method of the aforementioned kind, comprising applying on an untreated wooden article a suspension of a pigment in an aqueous solvent in which a fungicide of quaternary ammonium salt-type is dissolved, wherein the suspension does not comprise binding agent or boron or metal cation comprising fungicide, and wherein the suspension preferably does not comprise any other fungicide than the fungicide of quaternary ammonium salt-type, wherein the suspension is applied in such an amount that the amount of applied fungicide of quaternary ammonium salt-type is from 2 g/m² to 15 g/m² or more, and drying the applied suspension. The applied amount of pigment is preferably capable of absorbing at least 95 %, in particular at least 98 % or more, of the natural UV radiation. By UV radiation is meant the radiation generated by the sun of a wavelength of from 100 mμ to 400 mμ. Preferably the applied amount of pigment is capable of absorbing at least 90 % of the visible light in the range of from 400 μm to 700 μm. According to a preferred aspect of the invention the suspension can comprise water soluble UV absorbent, e.g. of the kind disclosed in US 2005/0180932 Al. Preferably the suspension is sprayed onto the wooden articles. It can also be applied by brushing or by dipping or by a combination of different procedures.

[0017] According to the invention is also disclosed a wooden article treated by the method of the invention. In a mid-Swedish outdoor climate such a wooden article will remain essentially free from the attack of mould fungi for at least six months, preferably at least one year. It can be painted on at any time with any paint suitable for painting untreated wood while one does not have to fear a deterioration of the properties of the paint layer. Description of Preferred Embodiments EXAMPLE 1

[0018] Production of wood preservative according to the invention. To 1 L of soft tap water 70 g of benzalkonium chloride is added and dissolved while stirring. To the solution 90 g of Oxidrδd Tonex® (Alcro) tinting paste is gradually added while stirring. For storage the suspension is transferred to a plastic can with a cover. At least one quarter of the volume of the can is left unfilled. Before use the can is vigorously shaken/stirred to resuspend any sedimented pigment.

[0019] Tonex® is intended for use in tinting by hand of waterborne latex, alkyde and oil paints, and is obtained in various colours (with different colouring pigments). It contains pigment and only non-hardening additives such as kokomonoethanolamine ethoxylate, kathon, sodium dodecylether sulfate, sodium tetradecylether sulfate, kokos- dimethyl betaine, alkyl monoethanol amide toxylate (dispersant), n- octyl-isothiazoline-3-one, 2-methyl-2H-isothiazoline-3-one (preservative) (less than 0.04 %).

[0020] In stead of Tonex® can be used, e.g., Symphony tinting paste (Tikkurila Coatings AB, Spanga, Sweden), also a waterborne tinting paste. In addition of pigment and water it contains 1-5 % by weight of surface active compounds (dispersants) and less than 0.0015 % preservative (of isothiazolone type). The amount of preservative in Tonex and Symphony tinting paste is adjusted to protect these products against mould attack before use, but is entirely insufficient for the protection of wood surfaces treated with these products.

[0021] Lightproof inorganic pigments, especially pigments based on iron oxide, are preferred.

EXAMPLE 2

[0022] Treatment of an unpainted wooden article with the wood preservative according to the invention. By means of a conventional low pressure spray gun the wood preservative according to Example 1 is sprayed on, in an amount of 0.2 L/m , the outer walls of the modules of a prefabricated wood-built house, in a production hall with good ventilation at a temperature of 25 °C. The modules are then packed, loaded onto a truck, transported to the assembly site and assembled to form the prefabricated house. The prefabricated house is traditionally painted when the weather so permits, e.g. after a period of 7 months from assembling in October of the preceding year.

EXAMPLE 3

[0023] Test of the wood preservative according to the invention. Tongued and grooved board was spray-painted with the wood preservative according to the invention to full coverage. The timber was placed outdoors in a tree-shaded place for 6 months (March to September) at an angle of about 45 degrees with the painted side facing upwards and to the South. Repeated lawn moving was performed in the immediate vicinity of the samples. The samples were examined by stereo microscopy in regard of mould attack. The samples were then restored to their old site, and the test continued for an additional two months. The samples were subsequently examined. The samples were compared with tongued and grooved board painted with ordinary house paint (Table 1).

[0024]

[0025] Table 1. Test of mould attack [Table 0001] [Table ] Table 1

[0026]

Claims

[0001] Means for temporary protection of untreated wood articles against mould attack, the means comprising quaternary ammonium salt as fungicide, preferably a salt of an inorganic acid such as sulfuric acid, hydrobromic acid and in particular hydrochloric acid, dissolved in an aqueous solvent and pigment suspended in the aqueous solvent, but not comprising binding agent or fungicide comprising boron or metal cation.

[0002] The means according to claim 1, not comprising, in addition to quaternary ammonium salt as a fungicide, other fungicide in a total amount of more than 1 % by weight of the amount of quaternary ammonium salt.

[0003] The means according to claim 2, wherein the quaternary ammonium salt is a trialkyl aryl ammonium salt or a mixture of trialkyl aryl ammonium salts.

[0004] The means according to claim 3, wherein alkyl is named R¹, R² and R³, wherein

1 9 1

R and R are same or different C -C alkyl, wherein preferably one or both of R and R are methyl, wherein R is an alkyl residue four or more carbon atoms

1 9 longer than the longest of R and R , preferably a C -C alkyl residue. [0005] The means according to claim 4, wherein the fungicide is a mixture of at least two quaternary ammonium salts, differing in regard of the length of R , the share of quaternary amine with shorter R³ preferably being the larger one. [0006] The means according to claim 5, wherein the aryl residue preferably is phenyl or p-tolyl, most preferred phenyl.

[0007] The means according to claim 1, wherein the fungicide is benzalkonium chloride.

[0008] The means according to any of claims 1 to 7, wherein the aqueous solvent is water or a mixture of water and of an alcohol chosen from methanol, ethanol, propanol, isopropanol, n-butanol. [0009] The means according to any of claims 1 to 8, wherein the pigment is of low water solubility, preferably a pigment insoluble in water. [0010] The means according to claim 9, wherein the particle size of the pigment is from

0.2 μm to 15 μm (weight average). [0011] The means according to any of claims 1 to 10, wherein the pigment is an inorganic pigment, in particular an iron oxide pigment. [0012] The means according to any of claims 1 to 11, wherein the means comprises from 3 to 15 % by weight of quaternary ammonium salt-type fungicide and from

5 to 30 % by weight of pigment. [0013] A method for providing a wooden article with temporary protection against mould attack, wherein the method comprises treating the wooden article with the means according to any of claims 1 to 12 by spraying, brushing or dipping or a combination of these procedures. [0014] The method according to claim 13, wherein the amount of applied fungicide is from 2 g/m to 15 g/m . [0015] Wood articles treated with the product according to any of claims 1 to 12.