Coating processes – Medical or dental purpose product; parts; subcombinations;...
Reexamination Certificate
2001-04-26
2003-10-21
Beck, Shrive P. (Department: 1762)
Coating processes
Medical or dental purpose product; parts; subcombinations;...
C427S002260, C427S002270, C427S402000, C427S407100, C427S407200, C427S337000, C427S340000, C427S344000
Reexamination Certificate
active
06635305
ABSTRACT:
THE STATE OF THE ART
It is known to coat a siliceous substrate with a silicon containing layer. For example, WO 9908784 discloses a method of treating, a solid material to make it hydrophobic.
Another method of coating a siliceous substrate with a silicon layer is disclosed in PCT/BE00/00033.
The content of these two documents are incorporated herein by reference in their entirety.
It has already been proposed to treat the siliceous substrate with HF (hydrofluorhydric acid) before applying the coating.
It has now been discovered that by making various preliminary treatments, as described hereinafter, it was possible to increase drastically the chemical bonds of the silicon layer with the substrate as well as silicon bounds within the layer.
BRIEF DESCRIPTION OF THE INVENTION
The invention relates to a process for coating at least a portion of a face of a siliceous substrate with a silicon containing layer.
The process comprises at least the following steps:
a treatment step, in which at least the portion of the face of the siliceous substrate is treated with a composition containing at least one biocide, and
at least the portion of the face of the siliceous substrate is then reacted with a reactive composition for forming a silicon containing layer that is chemically bound to the siliceous substrate.
For example, no drying step is required when applying an amino silane-containing composition on the siliceous substrate.
The reaction with the reactive composition is advantageously carried out at least 10 seconds after the beginning of the treatment step with the biocide containing composition. Preferably, the reaction with the reactive composition is advantageously carried out at least 30 seconds after the beginning of treatment step with the biocide containing composition. For example, the reaction with the reactive composition is advantageously carried out 45 seconds, 1 minute, 2 minutes, 5 minutes, 10 minutes, 20 minutes after the beginning of the treatment step with the biocide-containing composition. Often a time of less than 10 minutes between the beginning of the treatment step and the reaction step is sufficient for obtaining the excellent properties of the coating, as described hereinafter. For example, the drying step (when necessary or desired) of the treated substrate was carried out less than 10 minutes after the beginning of the reaction with the reactive composition.
Advantageously, the biocide composition is selected from the group consisting of aqueous compositions, solvent-containing compositions, alcohol-containing compositions and mixtures thereof. Possible solvents are: organic solvents, such as methanol, ethanol, isopropanol, benzene, dichloro ethane, etc. and mixtures thereof, including with water. However aqueous compositions are preferred for safety reasons.
According to an embodiment, the portion treated with a biocide-containing composition is at least partly washed before being contacted with the reactive composition. The washing step can be carried out by using water, preferably pyrogen free water, solvent, solvent containing compositions, polishing slurries, etc.
Preferably, the portion treated with a biocide containing composition is at least partly dried before being contacted with the reactive composition.
Most preferably, the portion treated with a biocide containing composition is at least partly treated with a means for removing water present on said portion. This water removal can be carried out by a solvent washing (for example by spraying an organic solvent on the treated portion, by dipping the portion in a bath containing one or more organic solvents, etc), by a mechanical removal (wiper, absorbent means, etc), by a low pressure for evaporating the water, by using a gas flow (for example having a low water content, such dried air, the gas having a temperature from 20° C. up to 150° C., or possibly more, and the gas being advantageously without, or substantially without, solid particles or dusts).
Preferably, the water removal is carried out by a washing step with an organic solvent, the solvent being most preferably a solvent suitable when coating the siliceous support or substrate with the reactive composition for applying a silicon containing layer, for example a solvent used in the composition containing the reactive for forming the silicon containing layer.
According to a preferred embodiment, the process comprises at least the following steps
a treatment step, in which at least the portion of the face of the siliceous substrate is treated with an aqueous composition containing at least one biocide;
preferably, at least the treated portion is washed;
a drying step, in which the (preferably washed) portion is at least partly dried, and
at least the dried portion is reacted with a reactive composition for forming a silicon containing layer chemically bound to the siliceous substrate.
Advantageously, the treated portion layer is washed with an aqueous liquid composition and is dried so that substantially no water remains on the portion of the face to be reacted with the reactive composition. Preferably, the treated portion is free of water before applying the reactive composition for making a silicon containing layer chemically bound to the siliceous substrate.
According to an embodiment, the treated portion layer is washed with an aqueous liquid composition and is dried so that substantially no water remains on the portion of the face to be reacted with the reactive composition. The drying is at least partly carried out by a mechanical removal of the liquid present on said portion.
Preferably, the drying is at least carried out by relative movement of a water absorbing support on the portion of the face.
According to an embodiment, the aqueous composition contains an effective amount of at least a biocide for ensuring an activation of the portion of the face when reacting the portion with the reactive silicon containing composition. In some case, it seems that the use of an aqueous biocide solution with a low biocide content (such as lower than 2% by weight, advantageously lower than 1% by weight, preferably lower than 0.5% by weight) or a high biocide content (higher than 10% by weight) gives the best activation of the siliceous substrate for obtaining an excellent adhesion of the siliceous substrate. However, it has been observed in examples that the use of aqueous biocide solution or liquid composition gives the best adhesion properties of the silicon containing layer on the siliceous substrate.
According to an embodiment, the portion of the face is at least treated with a composition containing at least one metal ion before reacting the portion of the face of the siliceous substrate with the reactive silicon containing composition.
Preferably, at least one of the metal ion is selected from the group consisting of copper, silver, gold, platinum, zinc, magnesium, calcium, sodium, cadmium, rhodium, palladium, salts and mixtures thereof.
Most preferably, the portion of the face is treated with at least a biocide in the presence of a metal ion. The presence of the metal ion, such as Cu++, improves the biocide properties of the biocide solution, but also increase the stability of the solution, thus ensuring an even treatment of the surface. For example, at least one of the metal ions is selected from the group consisting of copper, silver, gold, platinum, zinc, magnesium, calcium, sodium, cadmium, rhodium, palladium, salts and mixtures thereof. The solution applied on the glass sheet has, for example, a metal content of less than 0.5%, advantageously less than 0.1% (such as 500 ppm, 300 ppm), preferably less than 0.01% (such as 100 ppm, 80 ppm, 50 ppm, 20 ppm, 10 ppm) or even in some case less.
Other stabilizing agents can also been used. Therefore, according to an embodiment, the portion of the face is treated with at least a biocide in the presence of at least an effective amount of a stabilizing agent.
According to a preferred embodiment, the portion of the face is treated
with a (preferably aqueous) solution containing bioc
Beck Shrive P.
Darby & Darby
ICT Coating N.V.
Kolb Michener Jennifer
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