Coating apparatus – Solid applicator contacting work – Movably mounted applicator
Patent
1987-07-15
1989-03-07
Beck, Shrive
Coating apparatus
Solid applicator contacting work
Movably mounted applicator
118304, 118320, 118322, 118DIG4, 427420, B05D 102, B05B 104
Patent
active
048096407
DESCRIPTION:
BRIEF SUMMARY
This invention relates to methods and apparatus for the coating of articles such as, by way of non-limiting example, hollow, rigid or semi-rigid containers, by application of a liquid coating material to the articles, the coating material being subsequently dried or allowed to dry. In respect of the apparatus, the invention further relates to holders for carrying the articles through the apparatus.
The invention is typically but without limitation, concerned with the coating of packaging containers made of polymers such as polyethylene terephthalate (PET), by application of a coating material to enhance the barrier properties of the containers. By "barrier properties" we mean partly the ability of the container to resist ingress, through its walls, of air or other gases, microorganisms or spores of micro-organisms, the object generally being to protect a food or other product subsequently packed in the container from spoilage by oxidation or microbial action for a period sufficiently long to give the product a desired shelf-life. The term "barrier properties" equally means the ability of the container to contain products pressurised above the ambient pressure, such as carbonated beverages, or foods or drinks packed under aseptic (sterile) conditions so that the internal pressure will not be significantly reduced, or (in the latter case) the sterility of the contents will not be contaminated from the atmosphere outside the container.
Coatings applied by the method or by the apparatus of this invention may have the further or alternative purpose of decoration, for example by providing a coloured opaque or transparent surface.
According to the invention in a first aspect, a method of applying a coating over a non-horizontal recipient surface of an article, comprises the steps of:
directing a supply of liquid coating material against a back surface of a curtain plate so as to spread the liquid over the back surface to fall as curtain from a lower edge of the curtain plate;
effecting continuous relative movement as between the article and the curtain plate, with the article closely in front of the curtain plate, such that the recipient surface intersects the curtain;
allowing the material to run freely down the recipient surface and allowing excess material to drain freely from it; and
causing the coating so applied to dry on the recipient surface.
Where the method is used for coating an external recipient surface which extends around the article, the step of effecting relative movement preferably comprises simultaneously causing the recipient surface to intersect the curtain and effecting relative rotation as between the curtain plate and the article, so as to present the recipient surface progressively to the curtain.
Where the method is used for coating an external recipient surface which extends axisymmetrically around an article defining a central axis, the step in which the recipient surface intersects the curtain is preferably carried out with the central axis inclined to the vertical.
The step of effecting relative movement as between the article and the curtain plate may be carried out with an upper portion of at least that part of the recipient surface facing the curtain plate located above the level of the lower edge of the curtain plate so that the upper portion does not intersect the curtain. The method then preferably includes the further step of applying a band of coating material over the upper portion of the recipient surface before or after applying a coating by means of the curtain.
Preferably the band is applied by the method the subject of our co-pending U.S. patent application Ser. No. 093,565, filed July 15, 1987 as a national stage applicaton of Application No. PCT/GB86/00598, filed Oct. 6, 1986, claiming priority of UK patent applications. Nos. 8524517 and 8614527. As applied to the method of the present invention, by way of this additional step, the step of coating the upper portion preferably comprises:
directing a stream of liquid coating material on to a moving donor surface of an e
REFERENCES:
patent: 2821158 (1958-01-01), Brown et al.
patent: 3422793 (1969-01-01), Lachmann
patent: 3951101 (1976-04-01), Karakawa et al.
patent: 4099486 (1978-07-01), Bialorucki et al.
patent: 4259377 (1981-03-01), Baize
Pilley, deceased Terence W. J.
Pilling Fred B.
Ryall Graham
Beck Shrive
Metal Box Public Limited Company
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