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Use of N-Cyclohexyldiazeniumdioxide - Copper salt (CuHDO) to Preserve Plasterboards

IP.com Disclosure Number: IPCOM000215448D
Publication Date: 2012-Feb-28
Document File: 3 page(s) / 226K

Publishing Venue

The IP.com Prior Art Database


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Use of N-Cyclohexyldiazeniumdioxide - Copper salt (CuHDO) to Preserve Plasterboards

It is well known that fungal and algal growth can be problematic to materials used within the construction industry. Materials such as wood, can be used untreated where prevailing conditions are suitable, however where there is a potential threat from fungal or algal attack, biocide treated material is specified. Other construction materials are also prone to problems, especially when used in moist conditions. Plasterboard (also known as Gypsum Board, Drywall or Sheetrock) is one such material; if stored and used in low humidity environments no biocide treatment is required. However, in certain high humidity environments and for certain uses, where exposure to water cannot be ruled out (in bathrooms and kitchens, for example) pre treated biocide boards are preferred.

N-Cyclohexyldiazeniumdioxide - Copper salt (CuHDO) has been established as a wood treatment biocide. Liquid formulations containing this active ingredient have been approved for use in the US under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the active ingredient has been notified, identified and is awaiting annex 1 listing in Europe under Product Type (PT) 8 for Wood Preservatives in the Biocidal Products Directive (BPD).

Potential applications could be under Product Types (PT) 7, 9 and 10 of the BPD. PT7 covers Film Preservatives including binders used to protect the initial properties of the surface of materials. PT9 covers Fibre, Leather, Rubber and Polymerised Materials preservatives; these include preservation of fibrous materials, such as Paper products. PT10 covers Masonry preservatives, used to treat construction materials other than Wood against microbiological attack.

Plasterboard is constructed out of a fibrous outer layer (PT9) and a gypsum core (PT10), biocide treatments which are applied to the gypsum core may partition out into the outer fibrous material and vice versa; alternatively a film or coating containing the biocide (PT7) may be applied to the surface of the board. It is foreseen that solutions of CuHDO may be applied directly into the gypsum stucco or together with one of the other commonly used additives (accelerators, retarders, foamers, superplasticizer etc.). It is also possible to envisage the CuHDO solution being sprayed, painted or applied via a coating onto the board either before or after the drying phase; or the carton / paper envelope could be pre treated with CuHDO, if the biocide application is best kept out of the plasterboard production area itself. In each case, the current regulatory position within Europe is sufficient to cover any foreseen application and use within this sector.

In laboratory testing, the efficacy of CuHDO solutions against problem microorganisms in this application has been well demonstrated.

Specimens of commercially available biocide treated and untreated gypsum wallboards (ca. 3x3 cm) and CuHDO tr...