WO2003055817A1

WO2003055817A1 - Method for laying a protective and/or containment coating on glass objects

Info

Publication number: WO2003055817A1
Application number: PCT/IT2002/000772
Authority: WO
Inventors: Eugenio Magnani; Vincenzo Di Giuseppantonio; Fabio Paloschi
Original assignee: Bormioli Rocco & Figlio S.P.A.
Priority date: 2001-12-21
Filing date: 2002-12-10
Publication date: 2003-07-10
Also published as: ITPR20010092A1; AU2002367120A1

Abstract

Method for laying a protective and/or containment coating on glass objects, of the type comprising the steps of: laying at least one layer of priming substance on a surface of the object and/or on a pre-existing coating layer; laying at least a layer of protective and/or containment coating, based on an organic compound and having a predetermined thickness, on the priming layer or on another coating layer; and heating the coated object to allow the organic compound to polymerise and to enhance the action of the priming substance. The subject method is characterised in that the laying phase has variable time duration to optimise the thickening of the coating layer. In particular, the step of laying the coating layer takes place in a time interval of between 0.3 and 10 seconds.

Description

METHOD FOR LAYING A PROTECTIVE AND/OR CONTAINMENT COATING ON GLASS OBJECTS

TECHNICAL FIELD AND BACKGROUND ART. The present invention relates to a method for laying a protective and/or containment coating on glass objects, of the type comprising the steps of: laying at least one layer of priming substance, or "primer" on a surface of the object and/or on a pre-existing coating layer; laying at least a layer of protective and/or containment coating, based on an organic compound and having a predetermined thickness, on the primer layer or on another layer of coating; heating the object thus coated to allow the organic compound to polymerise and to enhance the action of the priming substance. In the household goods industry, methods are known for laying a layer of protective coating on frangible objects, such as dishes, containers and/or glasses, typically made of glass or ceramics.

The Canadian patent application CA 2236759 discloses a method comprising the steps of:

- applying on the surface of container a first primer coating, preferably based on organo-functional silicone; - applying at least a second coating, preferably based on an ethylene copolymer, able to absorb impacts;

- applying a third thermoplastic coating, preferably made of polyurethane, able to withstand heat, chemical agents and impacts.

In case of breakage, the second layer of coating retains the fragments that are formed, preventing them from being scattered. Such coatings, preferably laid by spraying, are substantially constituted by liquid paints and can be decorated with drawings or with ornamental motifs, even relief ones.

As patent application WO 00/43324 discloses, there is also a method for coating frangible items, comprising the steps of:

- laying on the surface of the object a first primer coating made of plastic material;

- laying at least a second coating made of plastic material that is able to absorb impacts; - laying a third coating made of thermoplastic and impact-resistant material.

In particular, the first coating is made of plastic material based on organo- functional silicone, preferably Silano A-l 106 and Silano A-l 130, both using water as a solvent.

The second coating is made of a plastic material constituted by a mixture based on an ethylene copolymer dispersed in water.

The third coating is made of thermoplastic material, typically water-based urethane. In particular, the possibility is provided of making the third coating with polyurethane, using ethyl acetate as a solvent.

Each coating, being substantially constituted by a liquid paint, is preferably laid on the object to be coated by means of spraying.

Currently, both methods described above provide for several layers of coating to be laid in succession, without any interruption, and very rapidly.

The methods briefly described above have some drawbacks.

First of all, to obtain a thickness of the coating that is adequate to withstand impacts and contain the fragments in case of breakage, it is necessary to lay numerous layers of paint and/or primer, with significant manufacturing costs. Secondly, if powder paints are adopted, the laying of multiple layers entails considerable difficulties, because of electrostatic phenomena deriving from spraying paint powder, which is charged electrostatically by rubbing against the walls of the gun and/or of the conduit by means of which the spraying operation is conducted. Two adjacent layers of paint, laid successively one after the other, therefore tend mutually to repel due to the electrostatic repulsion existing between them. DISCLOSURE OF INVENTION. An aim of the present invention is to eliminate the aforesaid drawbacks by making available a method for laying a protective and/or containment coating on glass objects, which allows to maximise the thickness of each coating layer, thereby reducing the number of layers required to obtain an adequate protective layer against impacts and/or a coating for containing fragments in case of breakage.

Another aim of the present invention is to propose a method for laying a protective and/or containment coating that allows to use powder paints, able to be laid by spraying. An additional aim of the present invention is to obtain all this in an extremely easy and economical manner.

Said aims are fully achieved by the method for laying a protective and/or containment coating on glass objects, of the present invention, which is characterised by the content of the claims set out below and in particular in that the laying step has a variable time duration to optimise the thickening of the protective and/or containment layer. In particular, the step of laying the coating layer takes place in a time interval ranging between 0.5 and 10 seconds, and preferably of about 2 seconds.

The subject method is further characterised in that it comprises a step of waiting a variable time interval between the laying of the layer of priming substance and the laying of the coating layer, in order to optimise the action of the priming substance itself. In particular, said waiting step has a duration of between 0.1 and 10 seconds and preferably 1.5 seconds.

With the values respectively of 2 seconds for the laying of the coating layer and 1.5 seconds for the waiting step, an optimal priming action was surprisingly observed, along with the possibility of obtaining a good adhesion of the organic compound to the priming layer, since one works with the best conditions of viscosity and humidity of the primer.

BEST MODE FOR CARRYING OUT THE INVENTION.

These and other characteristics will become more readily apparent from the following description of a preferred embodiment illustrated herein purely by way of non limited example.

The present invention relates to a method for laying a protective and/or containment coating on glass objects, of the type comprising the steps of: laying at least a layer of priming substance on a surface of the object and/or on a pre-existing coating layer; laying at least a layer of protective and/or containment layer, based on an organic compound and having a predetermined thickness, on the priming layer or on another coating layer; and heating the coated object to allow the organic compound to polymerise and to enhance the action of the priming substance, and is characterised in that the laying step has a variable duration to optimise the thickening of the protective and/or containment layer. In particular, the step of laying the coating step takes place in a time interval of between 0.5 and 10 seconds. The method also comprises a waiting step, of variable duration, between the laying of the layer of priming substance and the laying of the coating layer, in order to optimise the action of the priming substance itself. Specifically, said waiting step has a duration of between 0.1 and 10 seconds. The time intervals mentioned above, both in regard to the laying of the coating layer and in regard to the waiting step, allow to optimise the thickening, since they assure the best compromise between the humidity of the primer, necessary to obtain a good adhesion of the organic compound to the primer layer itself, and the viscosity of the primer, necessary to assure its adhesion to the object to be coated. The method provides for the primer layer to be preferably based on organo- functional silicone, whilst the coating layer is substantially a liquid or powder paint. In both cases, however, the laying of the paint is preferably accomplished by spraying. The aforesaid time intervals, both for the step of laying the coating layer, and for the waiting step, also allow to use powder paints, since they allow the dissolution of at least part of the electrostatic charges that develop as a result of the spraying operation.

At the end of the laying of all coating layers, the coated object is typically placed in a stove at a temperature of between 100 and 300 °C for a time interval that may vary between 5 and 30 minutes, depending on the type of paint that was used. This heating step is necessary to allow the organic compound to polymerise and to enhance the action of the priming substance. In this regard, usable types of paints are all for food use and preferably belong to the following families: - epoxies;

- epoxy polyesters;

- polyesters;

- polyurethanes;

- polyamides; - acrylic.

Use of different types of paint has the purpose of creating different decorative effects, whilst providing the coating with resilience as well as the ability to contain glass fragments in case of breakage.

The subject method, in addition to being applicable on common glass items, can also be advantageously used to coat items made of toughened glass. In this case, since the latter type of glass has significant resilience, the coating can be thinner, as its purpose is solely to contain fragments in case of breakage.

The method provides for completing multiple coating layers, taking care to lay a layer of primer after each layer of paint, or other organic compound.

Alternatively, in any case, it is possible to lay several coating layers, without interposing any priming substance.

The laying operation can be done on a chain with continuous or intermittent motion, although the latter is to be preferred, in order to obtain a good homogeneity of application with values of thickness that may reach even 300 microns.

The invention achieves important advantages.

First of all, such a method allows to maximise the thickness of each coating layer, thereby decreasing the number of layers needed to obtain an adequate coating to protect against impacts and/or a coating for containing fragments in case of breakage. The time intervals indicated in this description allow to optimise the thickening of each coating layer, since they assure the best compromise between the humidity of the primer, necessary to obtain a good adhesion of the organic compound to the primer layer itself, and the viscosity of the primer, necessary to assure its adhesion to the object to be coated. In the second place, such a method allows to lay coating layers by spraying powder paints on a primer layer.

Advantageously, the subject method can be employed also with liquid paints and in this case they are mixed to the primer substance before being laid onto the item to be coated.

Another advantage of the present method is represented by the fact that its implementation is economical and that it can be used to coat indifferently objects made of annealed or toughened glass. Another advantage of the present invention is given by the capability of using various types of paints, in order to create decorative effects whilst guaranteeing resilience and the containment of fragments in case of breakage.

Claims

1. Method for laying a protective and/or containment coating on glass objects, of the type comprising the steps of: laying at least one layer of priming substance on a surface of the object and/or on a pre-existing coating layer; laying at least a layer of protective and/or containment coating, based on an organic compound and having a predetermined thickness, on the priming layer or on another coating layer; and heating the coated object to allow the organic compound to polymerise and to enhance the action of the priming substance, characterised in that the laying phase has variable time duration to optimise the thickening of the protective and/or containment coating layer.

2. Method as claimed in claim 1, characterised in that it comprises a step of waiting, for a variable time interval, between the laying of the layer of priming substance and the laying of the coating layer, to optimise the action of the priming substance itself.

3. Method as claimed in claim 1, characterised in that the step of laying the coating layer takes place in a time interval of between 0.5 and 10 seconds.

4. Method as claimed in claim 1, characterised in that the step of laying the coating layer takes place in about 2 seconds.

5. Method as claimed in claim 2, characterised in that the waiting step has a time duration of between about 0.1 and 10 seconds.

6. Method as claimed in claim 2, characterised in that the waiting step has a time duration of about 1.5 seconds.

7. Method as claimed in claim 1 , characterised in that the layer of priming substance is based on organo-functional silicone.

8. Method as claimed in claim 1, characterised in that organic compound is substantially a liquid paint.

9. Method as claimed in claim 1, characterised in that said organic compound is substantially a powder paint.

10. Method as claimed in claims 8 or 9, characterised in that the laying of the paint is accomplished by spraying.

11. Method as claimed in claim 1 , characterised in that the heating step takes place in a range of temperatures of between 100 and 300°C.

12. Method as claimed in claim 1, characterised in that the object to be coated is made of toughened glass.

13. Glass object, characterised in that it is provided with a protective and/or containment coating obtained with a method as claimed in any of the previous claims.