Patent Application
20110143064
The present invention relates to the conditioning of hollow glass after the forming thereof in order to reinforce it and protect it against scratching.
The expression “hollow glass” is understood to mean the glasses made in order to constitute containers, such as bottles, flasks, pots, etc.
The process for manufacturing and conditioning hollow glass comprises the following operations:
The molded hollow glass resulting from the forming is placed on a conveyor and then passes to the hot surface treatment station, this treatment consisting in applying to the glass, by chemical vapor deposition (CVD), a layer of SnO2 or of TiO2 over a thickness of the order to 10-20 nm. This layer has the double role, on the one hand, of an agent for protecting the glass against defects which may be created by contacts at high temperature and, on the other hand, of a bonding primer for the cold surface treatment which will follow.
The molded and thus hot-treated hollow glass then passes into an annealing lehr where it is annealed at a temperature of 500° C.-600° C. depending on the type of glass and exits at around 150° C., then is sent, still on its conveyor, to the cold surface treatment station, during which, deposited on this hollow glass, by spraying, is at least one agent for protection against scratches and the rubbing actions from use and from handling. This agent, which has lubricating properties, is generally chosen from waxes, such as oxidized or non-oxidized polyethylene waxes, partial esters of fatty acids and fatty acids, and polyurethanes and other polymers known for their protective role, such as acrylic polymers.
This hollow glass is intended to subsequently be subjected to a great many handling operations: palletizing, transportation, depalletizing, filling bottles, flasks, etc., capping, labeling, transportation, etc.
For all these reasons, in order for the consumer to be able to receive defect-free containers, a conditioning is sought for the hollow glass after the forming thereof that has the double role of reinforcing it and of protecting it:
The mechanical properties of glass packagings are limited, in particular, by surface defects related to the forming and, more generally, to all high-temperature contacts in the production cycle. Unfortunately, these defects cannot be avoided: contact with the mold already takes place when the parison falls into this mold and, under the effect of heat shocks, cooling operations, traces of lubricant from the molds, etc., stresses appear in the glass and cracks, inclusions of batch stones, etc., appear at the surface thereof, which are the source of the defects that it is desired to avoid.
The first aforementioned surface treatment (by CVD) provides protection for the glass just after the forming thereof and before it enters into the annealing lehr. The second surface treatment (by spraying waxes or the like) is necessary to supplement the first treatment and to limit the appearance of new surface defects on the glass following this treatment. Such treatments do not, however, provide the reinforcement of the glass. They settle for protecting the surface by limiting the propagation of cracks.
Various reinforcement treatments have been studied but none has proved to be able to be used industrially. Indeed, these treatments consist of the application of resins, which can only be applied at ambient temperature, whereas it is advantageous to be able to carry out such a treatment on the glass at 80-150° C. instead of the second aforementioned surface treatment in order not to needlessly complicate or lengthen the manufacturing line. Furthermore, with such treatments, the scratch resistance is insufficient.
Also known from WO 2006/013305 A1 are compositions for the surface treatment of hollow glass, presented as being able to be applied at a temperature of 10-150° C. Such compositions in fact mainly provide only a healing of the surface defects.
Reference may be made to
The problem faced is therefore to find a treatment of the hollow glass that provides reinforcement and, at the same time, surface protection, advantageously that can be deposited on hot glass at 80-150° C. It would furthermore be advantageous to be able to do away with the CVD treatment, in other words that the treatment proposed can simultaneously provide the healing of the cracks and defects that have appeared previously, namely during the forming and during the annealing.
The objective of the present invention is to provide a solution to these problems.
One subject of the present invention is therefore firstly the use, as agent having the double role of reinforcing the hollow glass and of protecting it against scratches, of at least one glass adhesion promoter comprising at least one amine functional group and/or at least one epoxy functional group which has reacted covalently with a polymer system formed from at least one monomer and/or at least one prepolymer and of at least one curing agent or crosslinker used in an amount equivalent or substantially equivalent to the stoichiometry of the monomer(s) and/or prepolymer(s).
Another subject of the present invention is a composition for treating the surface of a hollow glass, characterized by the fact that it comprises, in water:
The constituent (A) is advantageously present in an amount of 0.5 to 2 parts by weight per 100 parts by weight of the constituent (B).
It is especially chosen from aminosilanes, aminodisilanes, epoxysilanes and organometallic adhesion promoters having at least one —NH— and/or —NH2 functional group.
In particular, the constituent (A) is chosen from the silanes of formulae (I) and (II):
in which:
R1 represents methoxy or ethoxy;
R2 represents R1 or methyl;
When R3 bears at least one amino functional group, it may be constituted by an alkyl or aralkyl radical, the aryl group of which is, where appropriate, substituted by vinyl, cycloalkylalkyl or aryl. When R3 bears an epoxy (glycidoxy) functional group, it may be constituted by an alkyl radical, the epoxy group being borne by the two terminal carbons of the alkyl radical, or by a cycloalkylalkyl radical, the epoxy group being borne by two neighboring carbons of the cycloalkyl group and the alkyl parts possibly being interrupted by an oxygen atom.
R4 is especially a divalent alkylene residue.
In particular, the constituent (A) may be chosen from:
It is preferred that the amino(di)silanes and the epoxysilanes are introduced into the composition in the hydrolyzed state.
The constituent (A) may also be chosen from coupling agents of amino zircoaluminate type, such as zirconium, β-alanine chloro hydroxy propylene glycol aluminum complexes. Mention may be made of the amino zircoaluminate complexes at 20 to 40% by weight in a solvent medium sold under the trade name CAVCO GLAS™ APG products by McGean, represented by the formula (III):
in which R is a hydrocarbon radical having an amino functional group.
Mention may also be made, as other metallic adhesion promoters, of the coupling agents sold under the names Chartwell B515.5W and Chartwell B516.5W by Chartwell, respectively having one amino group and two amino groups.
Constituent (B): Monomer(s) and/or Prepolymer(s) of the Polymer System
The constituent (B) is especially chosen from derivatives of bisphenol A, such as those represented by the formula (IV):
in which n is between 0 and 5, the limits included, derivatives of bisphenol F and epoxy novolacs, such as those represented by the formula (V):
in which n is the number of repeat units, having an average value of 0 to 2.
The constituent (B) may be any type of epoxide emulsion. It has been noted that the scratch resistance increases with the increase in the length of the epoxy monomer or prepolymer used as constituent (B).
The constituent (C) is advantageously used in an amount equivalent to the stoichiometry of the constituent (B) or to ±10 mol % of the stoichiometry of the constituent (B). It may especially be chosen from:
As Jeffamines from the D series, mention may be made of the Jeffamines D-230 (x=2-3), D-400 (x=5-6), D-2000 (x=33 on average) and D-4000 (x=68 on average) and, as Jeffamines from the ED series, the Jeffamines HK-511 (XTJ-511) (b=2.0 and a+c=2.0), XTJ-500 (ED-600) (b=9.0 and a+c=3.6) and XTJ-502 (ED-2003) (b=38.7 and a+c=6.0).
In the case where the constituent (C) is the dicyandiamide, it is especially present in an amount of 5 to 10 parts by weight, in particular of 6 to 7 parts by weight, of the constituent (B).
The dicyandiamide which is used in the case of a 4 minute firing of the glass at 200° C. with the “K54” catalyst mentioned below is preferred.
The constituent (D) is advantageously present, especially, in an amount of 0.1 to 2 parts by weight, especially of 0.5 part by weight, per 100 parts by weight of the constituent (B). It may especially be chosen from:
Constituent (E): Agent that Improves the Bonding of Labels, in Particular with Aqueous Starch and Casein Adhesives
The optional constituent (E) may advantageously represent from 0.02 to 0.5% by weight, in particular from 0.05 to 0.2% by weight, expressed as solids in water, in the total composition.
It may especially be sodium dodecyl sulfate, which is effective in particular when use is made, as constituent (B), of an Epirez epoxide emulsion from Hexion from which a portion (for example half) of the surfactant has been removed.
The present invention also relates to a process for treating the surface of a hollow glass in order to reinforce it and to protect it against scratching, characterized by the fact that a thin film of the composition as defined above is applied to the glass parts to be treated, and that the polymer system is formed and reacted with the adhesion promoter under the action of heat with removal of the aqueous carrier, leaving on the glass a layer, which may be discontinuous, of the reinforcing and anti-scratch agent.
Advantageously, it is possible to apply the thin film of the composition, by spraying, at a temperature of 80 to 200° C.
The invention also relates to a process for manufacturing and conditioning a hollow glass, characterized by the fact that the following operations are carried out:
above,
the hollow glass formed being conveyed continuously, passing through the annealing lehr and then to a station where it is subjected to the surface treatment (c).
In accordance with a first particularly preferred embodiment, the hollow glass is sent from the forming directly to the annealing step. Thus, the aforementioned step of applying SnO2 or TiO2 via CVD is dispensed with, hollow glasses that have very good mechanical strength with a scratch resistance that is still acceptable being obtained.
In accordance with a second embodiment, the hollow glass is sent to a step of surface treatment with SnO2 or TiO2 applied by CVD before being sent to the annealing step.
The present invention also relates to a hollow glass treated by a composition as defined above, according to the process as defined above.
In particular, the cured composition deposited on the glass may have an average thickness of less than 100 nm, in particular of less than 50 nm, preferably of less than 10 nm. However, the average thickness of the composition may also be greater than 100 nm.
The present invention finally relates to the use of a composition as defined above for reinforcing the hollow glass and for protecting it against scratching.
The following examples illustrate the present invention without, however, limiting the scope thereof. In these examples, the parts and percentages are by weight, unless otherwise indicated.
The following three formulations were prepared:
In these formulations:
The coating is deposited by spraying onto flat glass having dimensions of 70×70 mm and a thickness of 3.85 mm, previously indented at 50 N for 20 s by a Vickers tip. These samples were brought to 120° C. in an oven before deposition. The coated samples then underwent curing in an oven for 5 minutes at 220° C. The mechanical strength of the plates is tested by a three-point bending test, at a crosshead speed of 5 mm/s. The “controls” correspond to the case of the untreated indented glass.
The fracture stresses listed in table 1 correspond to an average value out of 10 plates tested.
Spraying tests were carried out on 300 g Burgundy bottles on an industrial line. After the spray booms, the treated bottles were recovered on the belt and deposited in two ovens at the edge of the line for crosslinking the coating. This was carried out at 220° C. (oven setpoint) for 20 minutes. These conditions are deliberately high so as to exclude any crosslinking defect and to focus the study on the effectiveness of the spray conditions.
The composition of the formulations used in tests 1 and 2 is that of example 1, described in table 1.
The spray parameters are described in table 2 below:
2%
The controls received a cold surface treatment based on modified polyethylene wax. Such a treatment does not exhibit any reinforcing power regardless of the amount deposited.
The characterization via internal pressure (IP) was carried out in situ, on 10 to 12 articles per mold (on 16 molds, 14 molds for test 1).
The appearance of the articles is good, under the two test conditions, comparable to the controls.
The effect of the reinforcing treatment according to the invention on the distribution of internal pressure is represented in
The effect of the reinforcing treatment according to the invention on the number of low values of resistance to the internal pressure (below 10 and 12 bar) is represented in
The bottles are sampled after the annealing lehr and then treated with the composition from example 1 of the invention by cold spraying, the hot-end treatment tunnel having been stopped. The control articles are sampled with and without hot treatment in order to evaluate the loss of mechanical properties after passing through the annealing lehr without the SnO2 layer. The articles without SnO2 were sampled just after cleaning the hot treatment tunnel. After treatment, the bottles are broken in the internal pressure test. The location of the source of fracture was noted and all the bottles that broke below 15 bar were analyzed.
The bottles were sampled in groups of 32 molds before the cold-end treatment. For each treatment, 5×32 bottles were sampled, i.e. a total of 480 bottles. The articles considered as controls are the articles treated at high temperature (SnO2) and at low temperature with a polyethylene wax in line.
The results are reported in
a: average of the pressures
b: cumulative percentage of fracture as a function of the internal pressure
c: percentage of fractures at low values; and
d: distribution of the location of the sources of fracture (all pressures merged).
A very great reduction in the internal pressure (of the order of 5 bar) is observed for the articles without SnO2 sampled at the outlet of the annealing lehr, compared with the articles with SnO2 (
The application of the coating according to the invention allows a great increase (8.7 bar) in the average internal pressure level, thus making it possible not only to compensate for this loss of mechanical strength in the absence of SnO2 but even to be at an average internal pressure level equivalent to the articles with SnO2.
If the relative gain in mechanical strength is considered, the coating according to the invention therefore appears significantly more effective in the absence of SnO2 layer.
The effect on the reduction in low levels (below 12 bar) is spectacular, with a change from 55% for the articles without SnO2 to 3% after treatment according to the invention (
The elimination of very low levels (
| Number | Date | Country | Kind |
|---|---|---|---|
| 085663 | Jul 2008 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR09/51349 | 7/8/2009 | WO | 00 | 3/2/2011 |
