Stock material or miscellaneous articles – Hollow or container type article – Glass – ceramic – or sintered – fused – fired – or calcined metal...
Reexamination Certificate
1999-09-01
2002-06-11
Koslow, C. Melissa (Department: 1755)
Stock material or miscellaneous articles
Hollow or container type article
Glass, ceramic, or sintered, fused, fired, or calcined metal...
C427S387000, C427S389700, C427S535000, C428S034400
Reexamination Certificate
active
06403175
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing surface-sealed hollow glass containers with the aid of a specific cold end coating composition.
2. Discussion of the Background
It is known that, in the production of hollow glass containers, the latter can be subjected to a surface treatment which is performed to cover external damage such as microcracks and minimize further damage. Thus, the hot end coating is applied as a thin layer to the glass surface which is at from 500 to 550° C. immediately after the production machine. These hot end coating materials are, in particular, titanium and tin chlorides which produce a titanium dioxide or tin dioxide layer on the glass surfaces, with the chlorine liberated going into the waste gas. The hot end coating material is applied by vapor deposition or spray atomization.
After hot end coating, the hollow glass containers run through an annealing lehr in which they are slowly cooled to avoid damaging stresses.
At the discharge end of the annealing lehr, the previously hot end coated hollow glass containers are cold end coated either by means of vapor deposition or by spray atomization. This results in the smoothness necessary for further procedures in the glassworks and in bottling operations.
The substances most frequently used for cold end coating are surfactants, fatty acid products, partial fatty acid esters, ester wax emulsions and various polyethylene dispersions.
A coating process in which hot end coating is first carried out and an olefin polymer, a polyurethane, a polystyrene or an acetic acid salt of an alkylamine is subsequently sprayed on as cold end coating material is known from DE-C 12 91 448. However, the bottles coated in this way do not meet all requirements.
Some improvement in the scratch resistance is achieved if the polyethylene dispersion which is sprayed on as cold end coating composition further comprises a silane (U.S. Pat. No. 3,438,801, 3,801,361, 3,873,352, 4,130,677, 4,374,879, EP-A-0 146 142). However, the property level is not sufficient for all applications.
A further development of the prior art was to spray on, as cold end coating, first the solution or dispersion of a silane and subsequently a further component such as a polyethylene dispersion. Here, reference may be made to U.S. Pat. No. 3,438,801, 4,130,677, 4,304,802, 5,567,235 (corresponds to WO-A-95/00259) and to EP-A-0 146 142 and EP-A-0 478 154.
Furthermore, it is known that cold end coating can also be carried out using a polysiloxane (U.S. Pat. No. 4,985,286; DE-A-31 44 457).
EP-A-0 011 519 describes a process in which glass bottles are treated with a silane and with a powdered polyurethane precursor. In addition, GB-A-2 021 124 describes a process for coating glass containers in which a polyaminoacrylate ester, a crosslinker, a wax and a vinylaminosilane are applied.
Although the coating methods described ensure a good basic strength of the glass containers, this strength decreases rapidly in the further production process and in subsequent use of the containers. A cause of this loss in strength is microscopic damage which inevitably occurs during shaping and the subsequent hot end transport of the glass containers and, depending on the degree and position of damage and the stresses on the container, can act as potential fracture origins.
Accordingly, there remains a need for improved coating processes.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for producing surface-sealed hollow glass containers.
It is another object of the present invention to make, during the production process itself, the microscopic damage discussed above no longer harmful.
It is a further object of the present invention to make the hollow articles less sensitive to mechanical action on the surface during subsequent handling, i.e. on the conveyor belt, during packing, during transport and during filling.
Another important aspect is that the hollow articles should have an improved basic strength and an improved long-term use strength compared to the prior art. Thus, in particular, returnable bottles for carbonated beverages should still have a sufficiently high strength and particularly internal pressure resistance even after many returns.
In addition, the hollow glass containers should have improved chemical resistance, in particular to water and detergent solutions.
Furthermore, the dry and wet scratch resistance should be increased and the scratch-through properties should be improved.
Overall, the mechanical properties compared to the prior art should be improved so that the weight of the container can be reduced while maintaining the same strength.
The mechanical properties should, furthermore, be improved in comparison with the known processes so that hot end coating can be omitted while maintaining the same final strength.
Compared to the coating process customarily carried out, improved labeling, even using conventional glues, should be possible.
Furthermore, it should also be possible to color the hollow glass containers by means of the surface seal and this coloration should be scratch- and detergent-resistant in order to achieve a high flexibility in the product line without subsequent problems during glass recycling.
The objects above, and others, may be accomplished with a process for producing surface-sealed hollow glass containers in which, in the production process in the region of the exit from the annealing lehr, which may be located downstream of a machine for producing hollow glass containers, the hollow glass containers are coated by means of a water-based cold end coating composition comprising at least the following components:
(I) a trialkoxysilane, a dialkoxysilane and/or a tetraalkoxysilane or a hydrolysis and/or condensation product thereof, and
(II) a water-soluble or water-dispersible mixture of a polyol and a crosslinker,
where the applied layer of the cold end coating composition is subsequently subjected to a crosslinking step in the temperature range from 100 to 350° C.
The objects of the invention may also be accomplished with the glass containers produced by the inventive process.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description.
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment of the process of the present invention, the water-based cold end coating composition further comprises, in addition to the components I and II, the following component:
(III) a silicon-free component selected from the group consisting of
(a) a wax,
(b) a partial fatty acid ester,
(c) a fatty acid, and
(d) a surfactant.
In another preferred embodiment of the process, the water-based cold end coating composition further comprises, in addition to the components I, II, and optionally III, the following additional component:
(IV) a colorant selected from the group consisting of organic pigments, inorganic pigments and organic dyes.
In addition, the water-based cold end coating composition may comprise conventional auxiliaries such as antifoams, leveling agents, catalysts (e.g. for the crosslinking of the components I and II additive resins or thixotropes.
The invention further provides the hollow glass containers produced using the process of the present invention.
As used herein, the term “hollow glass containers” includes essentially any type of packaging glass, for example bottles, jars for preservatives, ampoules, tablet vials or flacons.
If desired, a hot end coating material known per se may be applied by any known method art to the surfaces of the freshly produced hollow glass containers in the region of entry to the annealing lehr. However, in view of the tremendous increase in the use strength achieved according to the present invention, the hot end coating may also be omitted, which is not only cheaper but also offers an ecological advantage due to a reduction in emissions. Further
Buchmayer Gerd
Fickler Alois
Jenkner Peter
Lomölder Rainer
Speier Peter
Degussa - AG
Koslow C. Melissa
Manlove Shalie
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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