WO2014088410A1

WO2014088410A1 - Method of manufacturing a glass article having a printed object within its body

Info

Publication number: WO2014088410A1
Application number: PCT/NL2012/050861
Authority: WO
Inventors: Menno KENTER
Original assignee: Serious Marbles Holding B.V.
Priority date: 2012-12-07
Filing date: 2012-12-07
Publication date: 2014-06-12

Abstract

The invention relates to a method of manufacturing a glass article having a printed object within its body, comprising the steps of: directly printing an object with a heat resistant ink; preheating the printed object; incorporating the printed object thus preheated in a molten glass mass; and shaping the molten glass mass into a glass article having the printed object within its body cooling of the glass article thus shaped. The method according to the invention allows a less complicated way of manufacturing glass articles in mass production, e.g. marbles, drinking glasses and the like, having uniquely printed objects or small series thereof.

Description

METHOD OF MANUFACTURING A GLASS ARTICLE HAVING A PRINTED OBJECT

WITHIN ITS BODY

The present invention relates to a method of manufacturing a glass article that has a printed object within its glass body.

A method of this kind is known from WO 94/11316. This known process of manufacturing a glass article with a transparent glass body bearing a message comprises the steps of transferring the message to a support made from a material heat compatible with the transparent glass body. The support is then fed into an apparatus for coating with molten glass. The support assembly together with the formable glass enclosing it is then processed to achieve the desired shape with a view to producing the message-bearing article. The message can be applied to one or both sides of the support by silkscreen printing, by application of a transfer, by sandblasting or by etching with an acid, by providing a multilayer glass of different colors using different masks for each color in the "cloisonne" technique in which positive or negative relief printing is applied to the support in a state in which it can be formed and the relief is filled with enamel. The message can be silkscreen printed on the support, requiring a fixing step by heating after application. If the message is applied in more than one color the support is heated to a temperature of approximately 150 DEG C. after each application of a different color. The message can be applied to the support by application of a transfer by applying to the support a carrier of a thermodegradable material carrying the message in the form of printing, enameling, etc. The combination is then fired at a temperature between about 500 °C and about 800 °C. to eliminate the thermodegradable material and to fix the message to the support. The message may include information, advertisement and the like. The object carrying the message may be a glass ball, a carafe stopper, the bottom of a drinking glass or the bottom of a plate.

The techniques specifically disclosed for application of the message to the object have serious drawbacks. A message printed by sandblasting or by etching will disappear, when the printed object is incorporated in a molten glass mass. Screen printing requires

preparation of a separate printing screen for each color to be printed. For manufacturing multicolor printed objects this technique is labor intensive and time consuming, because of the number of printing steps and the required intermediate heating step between different colours applied successively. Furthermore from commercial point of view this technique is only economically applicable to mass production of glass articles bearing the same message, i.e. the same print without any variations. E.g. unique serial numbers for each product, such as collector items (or small series thereof), would require at least one unique printing screen for each product or small series thereof. Furthermore silkscreen printing of small three- dimensional articles, e.g. small objects having a size of 1 to 3 centimeters is complicated, if not impossible at all, because of the complexity of positioning the objects with respect to the screen.

The transfer technique has similar disadvantages. This transfer technique uses a separate step of application of the message to the thermodegradable material. Compared to the support this material is very fragile, certainly in the severe conditions (high temperatures) of the manufacturing steps of the article. Moreover this technique can only be used on smooth surfaces of the support, although they may show gradually curved 3D features. Positioning and application of the transfer material to complex shaped 3D supports is a complicated process. As a result also this kind of technique is commercially not attractive or suitable for manufacturing large series of unique products, or multiple series of a limited number of identical products.

Despite the potential of WO 94/1 1316 this technique has not been commercialized yet.

Therefore there is a need of a method of manufacturing a glass article having a printed object within its body that allows to produce glass articles carrying a printed object at a minimum of steps in mass production, as well as allowing a relatively uncomplicated production of articles, being unique by means of the printed object, or small series thereof. According to the invention this is achieved by means of a method of manufacturing a glass article having a printed object within its body, comprising the steps of:

directly printing an object with a heat resistant ink;

preheating the printed object;

incorporating the printed object thus preheated in a molten glass mass; and shaping the molten glass mass into a glass article having the printed object within its body,

cooling of the glass article thus shaped.

In the method according to the invention the object is printed directly with a heat resistant ink. In the context of this application directly printing means a printing technique, wherein the ink is applied from the printer to the object without interference of a temporary substrate as used in transfer printing and wherein the print can be changed directly by changing the input to the printer. Examples of suitable direct printing methods within the above definition comprise computer printing techniques including xerography, laser printing and LED printing and inkjet printing. The printing ink advantageously comprises ceramic particles as pigment or dye. In general the particle size thereof is in the range of 5 micrometer up to 1.5 mm. Preferably pigment size is in the lower end of this range, such as below 400 micrometer. The pigment particles are preferably heat resistant to a temperature above 1000 °C, e.g. 1100 °C. Then the printed object is preheated prior to incorporation in a glass mass, otherwise the printed object would be subjected to a temperature shock resulting in a risk of inducing cracks in the object, print and/or the glass mass of the article after shaping and cooling. Heat expansion is a material property, thus depending from the composition of the object. In general preheating of the object to a temperature above about 500 °C, such as in the range of 550-700 °C has proven to be successful. After preheating the printed object thus preheated is incorporated in a molten glass mass, usually requiring a temperature above 900 °C such as about 1200 °C. and subsequently formed into the desired shape. Finally the shaped glass article incorporating the printed object is allowed to cool.

The direct printing step as used in the method according to the invention allows to produce multicolored objects in one time without intervening substeps. Moreover, direct printing allows to produce a plurality of uniquely printed objects or plurality of small series of identical objects, the printing and or objects differing in a consecutive series. This can be performed in a rather easy way by properly programming the direct printing device used.

In a preferred embodiment of the invention the object to be printed is made from a heat resistant material, preferably glass or ceramics, most preferably a transparent glass. As during the incorporating substep of the object into the molten glass mass and/or the subsequent shaping step of the glass mass the object is subjected to high temperatures, a heat resistant object will not deform thermally. A transparent glass as object incorporated in a similar transparent glass results in a print such as text and/or image "floating" in the article, which offers an attractive appearance. In a particular preferred embodiment the composition of the object and the composition of the glass mass are essentially the same, offering essentially the same expansion coefficient and transparency.

Advantageously the object is pretreated by cleaning and/or drying prior to printing, thereby improving the quality of the print regarding visibility and adherence of the print to the object. The shape of the object is not particularly limited, advantageously the object is two- dimensional or three-dimensional object, such as a 2D or 3D representation of a fairytale figure, strip figure, film actor/actresses, cartoon heroes, sport figures, company logos, miniature products, business card supports and the like.

In order to reduce the risk of initiating cracks during various substeps in a preferred embodiment at least the outer surface layer of the heat resistant material of the object has an expansion coefficient similar to the expansion coefficient of the glass mass. Typically the expansion coefficient of the glass mass is in the range of 3.1 - 12 10^"6 m/K, such as about 9 for soda lime glass. Soda lime glass is the type of glass commonly applied in the invention, although other types like borosilicate glass and lead crystal can be used similarly. If the object has a layered structure, then it is advantageous that the expansion coefficients of the different layers gradually develop (increase/decrease) from the core of the object outwardly to finally essentially match the heat coefficient of the glass mass, wherein the object is to be incorporated. E.g. in such a gradual development adjacent layers have expansion coefficients differing not more than 0.2, more preferably less than 0.1.

In a particularly preferred embodiment the method according to the invention is a two-drop technique. In such a technique the step of incorporating the printed object in a molten glass comprises providing a first amount of molten glass, positioning the printed object in or on said first amount of molten glass, and adding a second amount of glass, such that the second amount covers the whole exposed (i.e. not covered by the first amount) surface of the object. It has appeared that in this two-drop techniques the position of the object can be controlled more accurately than in a one-drop technique. In the preferred embodiment advantageously the amount of the first drop is small compared to the second amount, e.g. in a ratio of 1 : 0.5 - 40 depending on the article to be made. E.g. in the production of marbles the ratio is about 1 : 1 for a final marble weight in the range of 20 - 32 g.

Forming the shape of the final articles depends on the type of article to be made. E.g. in the production of spherical articles the glass mass including the printed object will be prepared in a mould, and subsequently the mass thus prepared will be poured between counterrotating discs have a concave depression in its perimeter. Press-blow glass shaping techniques are suitable for almost all other kind of products. Injection moulding is another option.

Glass articles manufactured according to the method of the invention are not particularly limited. Marbles, bottles, drinking glasses, tumblers, cups, plates, dishes, stemware, giftware or decorative items are suitable examples. If the shaped article comprises a base or bottom part like for example the foot of wine glasses or bottom of drinking glasses, then the object is advantageously incorporated in this base.

It is even possible to have more than one first drops of glass at least two of which incorporating an object at least one of which is directly printed according to the invention. As a result the final product contains more than one object, at least one of which is directly printed according to the invention. This system can easily be multiplied.

Claims

1. Method of manufacturing a glass article having a printed object within its body, comprising the steps of:

directly printing an object with a heat resistant ink;

preheating the printed object;

incorporating the printed object thus preheated in a molten glass mass; and

shaping the molten glass mass into a glass article having the printed object within its body cooling of the glass article thus shaped.

2. Method according to claim 1 , wherein said directly printing is selected from the group of printing techniques comprising xerography, inkjet printing, LED printing, laser printing.

3. Method according to claim 1 or 2, wherein the object is made of a heat resistant material, preferably glass or ceramics, more preferably a transparent glass.

4. Method according to any one of the preceding claims, wherein prior to printing the object is pretreated by cleaning and drying.

5. Method according to any one of the preceding claims, wherein the object is a 2D or 3D object.

6. Method according to any one of the preceding claims, wherein at least the outer surface layer of the heat resistant material of the object has an expansion coefficient similar to the expansion coefficient of the glass mass.

7. Method according to claim 6, wherein the object has a layered structure, and the expansion coefficients between adjacent layers do not differ more than 0.2.

8. Method according to any one of the preceding claims, wherein the step of

incorporating the printed object in a molten glass mass comprising providing a first amount of molten glass, positioning the printed object in or on said first amount, and adding a second amount of molten glass, such that the second amount covers the whole exposed surface of the object.

9. Method according to any one of the preceding claims, wherein the composition of the object and the composition of the glass mass are essentially the same.

10. Method according to any one of the preceding claims, wherein the shaped article is selected from marbles, bottles, glasses for drinking, tumblers, cups, plates, dishes, stemware, giftware or decorative items.

1 1. Method according to any one of the preceding claims, wherein the shaped article comprises a base and the object is incorporated in said base.