| http://www.w3.org/ns/prov#value | - Thus it is preferred that the plant fibre material to be used with the present invention has a fluorescence, which is at least 1.2 times higher, more preferably at least 1.3 times higher, even more preferably at least 1.4 time higher, yet more preferably at least 1.5 times higher, even more preferably at least 2 times higher, yet more preferably at least 2.4 times higher, such as at least 4 times
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