Aqueous ammoniacal zinc arsenic or zinc/copper arsenic wood preservative solutions
AssigneeCanadian Patents and Development Limited
InventorsMichael R. Clarke, Jaromir R. Rak
Life of this patent
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Abstract
Aqueous ammoniacal wood treating compositions are provided which have a pH of 9 or more. The cations are zinc ammonium or copper ammonium and zinc ammonium ions. The anions include arsenic or arsenious ions, as well as further anions of carbonate and/or bicarbonate. The weight ratio of zinc or zinc and copper (as oxide) to arsenic (as oxide) is greater than 1.5. Preferably, the weight ratio of CO.sub.2 /NH.sub.3 /Zn/As or CO.sub.2 /NH.sub.3 /Zn+Cu/As is 1.7-2.3/5.9-6.7/1.9-2.9/.9. The compositions provide a treated wood product with increased leaching resistance of arsenic. Treating procedures and treated wood products are also provided.
Claims13
A wood treating composition comprising an aqueous solution containing:
- a. soluble components adapted to form a normally water-insoluble compound of zinc or zinc and copper with arsenic acid or arsenious acid, the metal being present in an amount of 0.1-4% by weight (as Zn or Zn + Cu metal) of the total aqueous solution, the weight ratio of zinc or zinc and copper (as oxides) to arsenic (as oxides) being 1.5 or more;
- b. 0.15-10% by weight of the total aqueous solution of a water repellent component comprising at least one of carbonate and bicarbonate ions, in an amount of up to 150% of the zinc or zinc and copper, the weight ratio of CO.sub.2 /NH.sub.3 /Zn/As or of CO.sub.2 /NH.sub.3 /Zn+ Cu/As being 1.7-2.3/5.9-6.7/1.9-2.9/0.9;
- and
- c. ammonia, in an amount of 1-28% by weight of the total aqueous solution;
- the ammonia being sufficient to solubilize the normally water-insoluble salts of zinc or zinc and copper and the normally water-insoluble water repellent component.
A concentrated, aqueous wood treating composition comprising a solution, in concentrated ammonia, of:
- a. ammoniacal-solution soluble components adapted to form a normally water-insoluble compound of zinc or of zinc and copper with arsenic acid or arsenious acid, the metal being present in an amount of 4-15% by weight (as Zn or Zn + Cu metal) based on the volume of the aqueous solution, the weight ratio of zinc or zinc and copper (as oxides) to arsenic (as oxides) being 1.5 or more;
- b. a water repellent component comprising at least one of carbonate and bicarbonate ions, in an amount of up to 150% by weight of the zinc or zinc and copper, the weight ratio of CO.sub.2 /NH.sub.3 /Zn/As or of CO.sub.2 /NH.sub.3 /Zn + Cu/As being 1.7-2.3/5.9-6.7/1.9-2.9/0.9, the total solids being from about 15 to about 45% by weight, based on the volume of the aqueous solution;
- and
- c. the ammonia being sufficient to solubilize the normally water-insoluble salts of zinc or of zinc and copper and the normally water-insoluble water repellent component.
Dependencies are inferred from the claim text.