UV radiation absorbing package

Details UV radiation absorbing package UV radiation absorbing package

1998-01-29

2000-12-26

Marcheschi, Michael

Compositions: ceramic

Ceramic compositions

Glass compositions, compositions containing glass other than...

501 70, 501905, 501904, 215400, C03C 3087, C03C 400, C03C 408

Patent

active

06165924&

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of international application number PCT/NL96/00206, filed May 20, 1996.
The present invention relates to a package for foods that are sensitive to UV radiation. More in particular, the invention relates to a package made of UV absorbing green glass, e.g. a bottle made of UV absorbing green glass that is highly permeable to visible light and has a dominant wavelength of 500 to 575 nm, for packaging foods and beverages.
As is known, ultraviolet radiation, more in particular radiation having a wavelength less than about 400 nm, has a negative effect on the smell and the flavor of foods and beverages, such as beer. This negative effect is ascribed to the chemical reaction of components under the influence of UV radiation.
It has long since been known that it is possible to reduce UV radiation by using glass that contains a number of additives, mostly metal compounds. Until recently, UV radiation absorbing green glass, which is the subject of the present invention, was obtained mainly by including chromium compounds in the glass. EP-A 261 725 describes the manufacture of green, UV radiation absorbing soda-lime glass having an amount of chromium compounds which may be partially replaced by nickel compounds. To obtain sufficient absorption of UV radiation, it is necessary to include relatively large amounts of chromium in the glass, preferably as Cr(VI). According to the examples of the above European patent application it is necessary to include at least 0.7% by weight of chromium in the glass to obtain a reasonable absorption of UV radiation.
From the literature it is already known that green colored glass having absorptivity to IR and UV radiation can be obtained by including iron compounds in glass. This often concerns the manufacture of glass used for windows, e.g. heat- and light-resistant car windows. In general, this concerns a small reduction of the transmission of the radiation, by including a minor amount of iron, mostly in combination with some other additives. Such a material is described in EP-A 452 207. According to this publication, iron, chromium, and cobalt are used to obtain a glass suitable for use in sunroofs of cars.
The amount of iron compounds in such glass compositions is in general below 2.5% by weight, if chromium is also present, more in particular below 1% by weight of the glass composition.
The transmission of UV radiation in such glass compositions is still high, because otherwise the transmission of the visible light is too much inhibited. For this reason the transmission at 380 and 400 nm is still at a level that makes the glass composition unsuitable for use as a protective packaging glass for foods and beverages that are sensitive to UV radiation.
On the other hand, the problem occurs that the transmission to visible light must be at least partially maintained, because the consumer/user must be able to see the contents of the package. Moreover, the wish to obtain a specific color can be at least partially inconsistent with the object of the absorption of UV radiation. If the transmission for IR radiation must be high, this result in the color and/or the absorption of UV radiation being negatively influenced.
Glass Technology, Vol. 26, No. 1, 1985, pp. 60-62, states that in soda-lime glass containing iron and chromium the iron inhibits the formation of hexavalent chromium. This conclusion is also drawn in The Glass Industry, May 1966, pp. 252-256 and 280-281. Hexavalent chromium is particularly responsible for the absorption of UV radiation, so that this will prevent those skilled in the art from using the combination of iron and chromium in soda-lime glass.
It is an object of the invention to provide a package for foods and/or beverages that are sensitive to UV radiation, which package is based on green soda-lime glass. More in particular, it is the object of the invention to provide a package of which the transmission of radiation having a wavelength of <400 nm and more in particular also of 380 nm, at a glass thickness of 2 mm, is nil or negligibly

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Database WPI, Week 22, Derwent Publications Ltd., London, GB; AN 75-36593, XP002009604 & JP,A,49 098 816 (Asahi Glass KK), Sep. 18, 1974, see abstract.
Chemical Abstracts, vol. 106, No. 6, Feb. 9, 1987, Columbus, Ohio, US; abstract No. 37472, p. 288; XP002009602, see abstract & JP,A,61 151 041 (Matsushita Electric Works Ltd), Jul. 9, 1986.
Glass Industry, vol. 47, No. 5, May 1966, New York US pp. 252-256, XP002009601, R.C. Knupp, et al.: "Effects of Iron in UV-Absorbing Green Glass" cited in the application, see the whole document.
Database WPI, Week 49, Derwent Publications Ltd. GB; AN 71-77787, XP002009603 & SU,A,291 886 (Gusev Branch Glass RES IN), 1971, see abstract (no month).

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