Opaque multi-layer container

Abstract

The invention discloses an opaque multi-layer container with light shielding, of the type produced by blowing a preform or by injection-blowing, preferably intended to contain photosensitive substances, which includes at least two layers of thermoplastic material with opacifying materials dispersed in the layers of the thermoplastic material, said thermoplastic material being polyethylene terephthalate (PET) in all of the layers and including, in at least one of the layers, aluminium metal (Al) and a light absorbent as opacifying material dispersed in the thermoplastic matrix. The invention that is presented provides the main advantage of being able to achieve practically total protection at any wavelength of the light spectrum, with much lower filler levels than those conventionally used to date.

Description

technical field [0001] As the title indicates, the present description relates to opaque multilayer containers of the type produced by blow molding preforms or by injection blow moulding, having light-shielding properties, preferably intended to contain light-sensitive substances, comprising at least Two layers of thermoplastic material, opaque material interspersed with thermoplastic material Either layer, the thermoplastic material is polyethylene terephthalate (PET) in all layers and in at least one layer includes an opaque material: metallic aluminum (Al) dispersed in a thermoplastic matrix and optical absorbent. [0002] Many substances are sensitive to deterioration under the action of light, with consequent changes in organoleptic and nutritional properties. Among the substances that will be mentioned are vitamins, ascorbic acid, peroxides or fats, each of which is particularly sensitive to one or a few wavelengths, is specific to each substance, and between the vario...

AI Technical Summary

Problems solved by technology

[0031] However, for a wide variety of products, especially UHT-treated milk and other dairy products with a long shelf life, because certain inappropriate vitamins (essentially E vitamins) and certain proteins and fats will Degradation, so transparency is not appropriate, as known from the previous description, the original organoleptic and nutritional properties change within a few days after bottling

[0032] There are other well known alternatives to increase the light shielding properties of PET such as described in US patent US 7150902 "High T.sub.g coatings" or in European patent EP 069953 "Hollow containers with inert or waterproof surface layers" , which is intended to apply to conventional preforms or similar plastic objects a covering of a different material, which may include additives or pigments, but the results of this type of operation are not ideal mechanically or light-shielding, and are not Provide solutions to the above problems

Likewise, compounds are known, such as those described in European patent EP 1541623 "Photoprotective composition for food containers", which claims a compound of aluminum powder and pearlescent pigments, which renders plastic opaque, Adding it to the plastic material itself increases lifespan by up to three weeks, but it involves high costs

[0033] Another single layer container is described in European patent EP 1541623 "Photoprotective composition for food containers" which uses a mixture of white pigment, aluminum powder, black pigment, pearlescent pigment to make the plastic opaque , but it presents the disadvantage compared with the present invention that a complex formulation is required, including high proportions of other fillers than Al, which means that presumably higher concentrations would be required in order to achieve high shielding than the proposed solution Filler and higher economic cost

[0037] The fundamental problems associated with the three-layer solution (conventional co-injection molding) are: the reduction in the production performance of the preform forming system compared to a similar single-layer preform; the mold must be service-intensive, especially the hot rails carrying the molten material ; due to the sensitivity to the process conditions of the depth and relative position of the intermediate shielding layer, the difficulty of ensuring the uniform quality of the preform; and the difficulty of the compatibility of the intermediate layer material with the wrapping layer material, which frequently leads to failures in the subsequent procedures of blow molding containers Imbalance, and delamination due to lack of adhesion due to different components of the layers

Multilayer embodiments of this known type (with outer, middle and inner layers) present a series of problems: because they have different compositions, with significantly different filler contents, when in the blow molding stage (i.e. During the final formation of a container or bottle) the layers behave differently when stretched

[0044] European patent application 12000408 "Opaque single-layer containers" proposes the use of Al as an opaque material, but only in single-layer containers

[0045] Applications are also known in which the shielding in the protective layer is realized by using only high shielding carbon black compounds, so that the content of shielding material in this layer can be very low (less than 1%), but this has the disadvantage that, outside Layers must use a relatively high dose of filler (approximately 5%) to hide the anti-aesthetic effect of black

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