GB2237802A - Improvements in or relating to compositions for vitreous enamelling and to methods of preparing and applying such compositions - Google Patents

Improvements in or relating to compositions for vitreous enamelling and to methods of preparing and applying such compositions Download PDF

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Publication number
GB2237802A
GB2237802A GB8925260A GB8925260A GB2237802A GB 2237802 A GB2237802 A GB 2237802A GB 8925260 A GB8925260 A GB 8925260A GB 8925260 A GB8925260 A GB 8925260A GB 2237802 A GB2237802 A GB 2237802A
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GB
United Kingdom
Prior art keywords
frit
composition
solvent
vitreous
disc
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8925260A
Other versions
GB2237802B (en
GB8925260D0 (en
Inventor
Michael Shanley
Ronald Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Stoves PLC
Original Assignee
Stoves PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Stoves PLC filed Critical Stoves PLC
Priority to GB8925260A priority Critical patent/GB2237802B/en
Publication of GB8925260D0 publication Critical patent/GB8925260D0/en
Publication of GB2237802A publication Critical patent/GB2237802A/en
Application granted granted Critical
Publication of GB2237802B publication Critical patent/GB2237802B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23D—ENAMELLING OF, OR APPLYING A VITREOUS LAYER TO, METALS
    • C23D5/00—Coating with enamels or vitreous layers
    • C23D5/02—Coating with enamels or vitreous layers by wet methods
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
    • C03C8/02—Frit compositions, i.e. in a powdered or comminuted form
    • C03C8/06—Frit compositions, i.e. in a powdered or comminuted form containing halogen
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
    • C03C8/02—Frit compositions, i.e. in a powdered or comminuted form
    • C03C8/08—Frit compositions, i.e. in a powdered or comminuted form containing phosphorus
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
    • C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
    • C03C8/16—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions with vehicle or suspending agents, e.g. slip

Abstract

A composition for vitreous enamelling comprises a finely-divided frit in suspension in a polar solvent, for example, iso-propyl alcohol. The resultant slurry is applied to a surface to be enamelled by means of a rotating disc held at a potential of from about 20Kv to about 1 50Kv. The disc is rotated at a speed of from about 5,000 to about 25,000 rpm and may have a diameter of from about 5 to 50 cm.

Description

ImProvements in or relating to compositions for Vitreous Enamellin and to methods of Preparing and a Plvinç such comPositions This invention relates to compositions for use in vitreous enamelling and to methods of preparing and applying such compositions.
Vitreous enamel compositions comprise a finely ground mixture of various components including silicates, colouring and other additives.
The composition may be applied to a surface to be enamelled either as a powder sprayed onto the surface using electrostatic deposition or the composition is mixed with water and sprayed or otherwise deposited on the surface as a slurry.
Both those methods of applying the composition have disadvantages. The "dry" electrostatic method does not always result in an even coating of powder over the surface particularly when the latter has deep recesses.
The "wet" method involves the formation of a slurry using water. It is found that water tends to attack the particles of the powder and even to leach out some of the components of the mixture. The quality of the water and the impurities present also vary and this imposes a further degree of unpredictability on the properties of the enamel coating.
Another problem that arises with the "wet" method is that of maintaining the powder in suspension in water.
It is an object of the present invention to provide an improved vitreous enamelling composition and a method of preparing the same.
According to the present invention a vitreous enamelling composition comprises a finely-ground vitreous enamel frit in suspension in a polar solvent which may be iso-propyl alcohol.
The composition is prepared by a method including the steps of preparing a finely-ground vitreous enamelling frit and suspending it in a polar solvent which may be iso-propyl alcohol.
The composition of the frit may vary according to the properties required from the finished coating.
For example, a typical frit, Frit A, comprises the following constituents: Constituent X bv weight SiO2 47 Al2O3 7 B2O3 15 Na2O 14 K2O 4 CaO 7 P2O@ 0.2 CoO 0.7 MnO 1 NiO 1 F2 3 After mixing, the constituents are ground in a ball mill or other suitable apparatus to a particle size of below 45 microns. The finely-ground mixture or frit is then added to iso-propyl alcohol in the ratio of 1 gm of frit to 1 cc of iso-propyl alcohol and agitated for about 10 minutes using a high shear mixer or other suitable blending equipment to ensure that the frit is completely in suspension.
Other ratios of frit to liquid may be used, but preferably, the ratio should not exceed 2.5 gm frit to 1 cc of liquid.
Additionally, there may be added to the frit finely ground colouring agents and\or other additives, for example SiO 2 which improves the resistance to heat of the coating.
The resultant suspension may be applied to a surface to be enamelled by any suitable process. Preferably, the suspension is applied by feeding it to the centre of a rapidly rotating disc from which it is spun off onto the surface. The disc is connected to a high potential source of from about 20Kv to about 150Kv while the surface is maintained at ground potential. A rotational speed of about 10,000 rpm is suitable for the disc.
Preferably, the disc is of a diameter of about 7.5cm but other diameters within the range of from about 5cm to about 50cm may be used.
Speeds of rotation of the disc other than that quoted above may used, but preferably, the speed lies within the range of from about 5,000 to about 25,000 rpm.
After the surface has been completely covered, the coating is allowed to dry and is then fired in the conventional manner.
It is found that the fine particles remain in suspension in the iso-propyl alcohol and no further agitation is required. No additives are required to maintain the suspension. Although iso-propyl alcohol is flammable normal precautions eliminate the risk of ignition.
Iso-propyl alcohol is a relatively inexpensive material so that its use does not greatly increase the cost of the enamelling process as compared with the conventional slurry using water.
Iso-propyl alcohol is one of the so-called polar solvents and alternative forms of the latter may be used instead of iso-propyl alcohol. Polar solvents are divided into three classes - high, medium and low and solvents in any of those classes are suitable for use in the process of the present invention. Foe example, iso-propyl alcohol referred to above is a high polar solvent. Another high polar solvent is butyl alcohol which may be preferable because it is found to evaporate less quickly than iso-propyl alcohol during spraying. Methyl acetate is another example of a suitable high polar solvent. An example of a medium polar solvent is cyclohexane although this is rather viscous. An example of a suitable low polar solvent is N-butyl acetate.
Furthermore, it is found that enamel suspensions based on mixtures of frit and iso-propyl alcohol are suitable for use in two-coat, one-fire processes without problems being encountered. For example, a base coat consisting of frit Bcomposition set out below- in suspension in iso-propyl alcohol in the ratio of 1 gm frit to 1 cc of the alcohol was applied to a thickness of about 40 microns onto a zero-carbon steel panel that had been degreased only i.e not pickled. That coating was allowed to dry, and then a second coating of frit C-composition set out below- suspended in iso-propyl alcohol as before was applied over the first coating to give a total thickness of around 100 microns. After drying, the coated panel was fired in the conventional manner to produce a white enamel finish that was well adhered to the steel substrate and which exhibited none of the defects often found when that process is carried out with water-based suspensions when it is found that the ground coat tends to boil up to the surface of the cover coat as a result of gaseous evolutions within the coating.
FRIT B Composition % by weight SiO2 26 Al24 5 BzOx 24 Na2O 24 CaO 8 BaO 6 P2O 1.7 MnO 0.4 CoO 0.6 NiO 1.4 CuO 0.2 F2 3 FRIT C Composition % by weight SiO2 13 Al2O3 20 B2O3 32 Na2O 16 CoO 2 TiO2 9 ZrO2 3 F2 5

Claims (18)

Claims.
1. A composition for vitreous enamelling comprising a finelydivided vitreous enamel frit in suspension in a polar solvent.
2. A composition as claimed in claim 1 in which the solvent is a high polar solvent.
3. A composition as claimed in claim 1 in which the solvent is a medium polar solvent.
4. A composition as claimed in claim 1 in which the solvent is a low polar solvent.
5. A composition as claimed in claim 2 in which the solvent is iso-propyl alcohol, butyl alcohol or methyl acetate.
6. A composition as claimed in claim 3 in which the solvent is cyclo-hexane.
7. A composition as claimed in claim 4 in which the solvent is N-butyl alcohol.
8. A composition as claimed in claim 1 in which the frit has the constituents set out in Frit A as herein described.
9. A method of preparing a composition for vitreous comprising the steps of preparing a finely-ground vitreous enamelling frit and suspending it in a polar solvent.
10. A method as claimed in claim 9 in which the frit is finely ground to a particle size not exceeding 45 microns.
11. A method as claimed in claim 9 or 10 in which the frit is added to the polar solvent in a ratio which does not exceed about 2.5 gm of frit to about 1 cc of solvent.
12. A method as claimed in claim 11 in which the ratio is 1 gm of frit to 1 cc of solvent.
13. A method as claimed in any one of claims 9 to 12 in which the frit is added to the solvent and then agitated for about 10 minutes in a high shear mixer.
14. A method of vitreous enamelling comprising the steps of preparing a composition as claimed in any one of claims 9 to 12, applying the suspension to a surface to form a coating thereon by means of a rotating disc, allowing the coating to dry and then firing the coated surface.
15. A method as claimed in claim 14 in which the disc is rotated at a speed of from 5,000 to 25,000 rpm.
16. A method as claimed in claim 14 or 15 in which the disc has a diameter of from 5 to 50 cm.
17. A method as claimed in claim 14 in which the disc has a diameter of 7.5 cm and is rotated at a speed of 10,000 rpm.
18. A method as claimed in any one of claims 14 to 17 in which the disc is maintained at a potential of from 20Kv to 150Kv and the surface is maintained at ground potential.
GB8925260A 1989-11-08 1989-11-08 Improvements in or relating to methods of vitreous enamelling Expired - Fee Related GB2237802B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8925260A GB2237802B (en) 1989-11-08 1989-11-08 Improvements in or relating to methods of vitreous enamelling

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8925260A GB2237802B (en) 1989-11-08 1989-11-08 Improvements in or relating to methods of vitreous enamelling

Publications (3)

Publication Number Publication Date
GB8925260D0 GB8925260D0 (en) 1989-12-28
GB2237802A true GB2237802A (en) 1991-05-15
GB2237802B GB2237802B (en) 1994-06-01

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB8925260A Expired - Fee Related GB2237802B (en) 1989-11-08 1989-11-08 Improvements in or relating to methods of vitreous enamelling

Country Status (1)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1026627A (en) * 1962-08-28 1966-04-20 Int Resistance Co Improvements in or relating to resistance materials,and electrical resistors made therefrom
GB1326433A (en) * 1969-10-24 1973-08-15 Du Pont Resistor compositions
GB1544794A (en) * 1977-01-31 1979-04-25 Beckman Instruments Inc Conductor compositions comprising aluminium silicon and glass
EP0059852A1 (en) * 1981-02-27 1982-09-15 Taiyo Yuden Co., Ltd. An electroconductive paste to be baked on ceramic bodies to provide capacitors, varistors or the like
GB2214179A (en) * 1987-11-13 1989-08-31 Ciba Geigy Ag Glass enamel coating compositions

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1489093A (en) * 1973-12-21 1977-10-19 Petroles Cie Francaise Anchorage systems
JPS6014183B2 (en) * 1975-11-11 1985-04-11 株式会社日本自動車部品総合研究所 Air flow adjustment device
SU1100257A1 (en) * 1982-07-28 1984-06-30 Рижский Ордена Трудового Красного Знамени Политехнический Институт Composition for producing enamel coating
SU1087481A1 (en) * 1982-07-28 1984-04-23 Рижский Ордена Трудового Красного Знамени Политехнический Институт Frit for enamel coating

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1026627A (en) * 1962-08-28 1966-04-20 Int Resistance Co Improvements in or relating to resistance materials,and electrical resistors made therefrom
GB1326433A (en) * 1969-10-24 1973-08-15 Du Pont Resistor compositions
GB1544794A (en) * 1977-01-31 1979-04-25 Beckman Instruments Inc Conductor compositions comprising aluminium silicon and glass
EP0059852A1 (en) * 1981-02-27 1982-09-15 Taiyo Yuden Co., Ltd. An electroconductive paste to be baked on ceramic bodies to provide capacitors, varistors or the like
GB2214179A (en) * 1987-11-13 1989-08-31 Ciba Geigy Ag Glass enamel coating compositions

Also Published As

Publication number Publication date
GB2237802B (en) 1994-06-01
GB8925260D0 (en) 1989-12-28

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