Method for reinforcing hollow glass articles
The invention relates to: 1) a process for the mass production of hollow glass articles which, when positioned beside one another with the same orientation in one and the same plane, are liable to come into mutual contact along a surface of revolution, characterized in that after they have left the annealing lehr, they are rotated through one turn at least along the axis of said surface of revolution, this surface then being coated, by a process without any solid contact, with an additional layer which reduces the coefficient of friction; 2) a hollow glass article as obtained by this process; and 3) a packaging assembly of such articles.
1. A process for mass producing hollow glass articles which, when positioned beside one another with the same orientation in one and the same plane, are liable to come into mutual contact along a surface of revolution, the method comprising
hot treating the hollow glass articles before entering an annealing lehr to apply a first coating comprising a metal oxide to the hollow glass articles,
after the hollow glass articles have left the annealing lehr and before entering into an optical checking machine, coating the surface of revolution with a second layer comprising a polymer without any solid contact between the hollow glass articles, and
rotating the hollow glass articles through another turn at least along an axis of said surface of revolution in the optical checking machine and
simultaneously coating the surface of revolution with a third layer comprising a polymer that is different from the polymer comprised in the second layer at a temperature of 20° C. to 100° C.,
wherein the maximum thickness of the combined thickness of the second coating and the third coating of the surface of revolution is from 1.5 to 5 times higher than the combined thickness of the second coating and the third coating on a surface other than the surface of revolution,
wherein the second layer and the third layer reduce the coefficient of friction between the hollow glass articles and are not visible to a naked eye,
wherein the hollow glass articles are glass bottles, glass flasks, or glass pots, and
wherein the surface of revolution represents at most 50% of the external surface of the hollow glass articles.
2. The process according to claim 1 , wherein said surface of revolution is coated with said second layer by a reactive or unreactive, gas and/or liquid spray.
3. The process according to claim 1 , wherein said second layer is left to dry after its application, in the absence of any solid contact with said second layer while it is drying.
4. The process according to claim 1 , wherein regions of mutual contact of said hollow glass articles are coated.
5. The process according to claim 1 , wherein the hollow glass articles are glass bottles.
6. The process according to claim 1 , wherein the second coating comprises additive-modified polyethylene wax and the third coating comprises polyethylene wax.
7. The process according to claim 1 , wherein the surface of revolution represents at most 30% of the external surface of the hollow glass articles.
8. The process according to claim 5 , wherein the surface of revolution represents at most 30% of the external surface of the hollow glass articles.