Labeled containers and processes for producing
View Patent ↗The invention provides novel processes for producing in-mold labeled containers and the containers produced using such processes. The processes involve setting a multilayered label having an oxygen barrier layer into a mold and injecting a melted resin suitable for forming a container into the mold. The process forms a container with an oxygen barrier layer. In preferred embodiments, the multilayered label has at least an oxygen absorbing resin layer containing ethylene-vinyl alcohol copolymer and an oxygen absorbent and the container is retortable.
1. A process for producing an in-mold labeled container, the process comprising:
setting a multilayered label comprising an oxygen absorbing resin layer onto an inner wall surface of a female mold part, the oxygen absorbing resin layer is a sublayer in a multilayered oxygen barrier layer, the multilayered oxygen barrier layer further comprising at least one oxygen barrier resin sublayer, the multilayered label further comprising at least one moisture resistant resin layer as the outermost layer or both the outermost and innermost layers of the multilayered label, the total thickness of one or more layers layered outside the multilayered oxygen barrier layer is represented by X and the total thickness of the container is represented by Y, the ratio of X/Y is from 0.06 to 0.1; and
injecting a melted resin that is polypropylene into a cavity between the female mold part and a male mold part, thereby molding and labeling the container simultaneously.
2. The process of claim 1 wherein the multilayered label covers all of an outer surface of the container.
3. The process of claim 1 comprising setting a multilayered sheet comprising an additional oxygen absorbing resin layer onto an outer wall surface of the male mold part before the injecting of the melted resin into the cavity, wherein the multilayered label covers all of the outer surface of the container, and the multilayered sheet covers all of the inner surface of the container.
4. The process of claim 1 wherein the oxygen absorbing resin layer comprises an ethylene-vinyl alcohol copolymer (EVOH) and an oxygen absorbent.
5. The process of claim 4 wherein the ethylene content by percentage in the EVOH contained in the oxygen absorbing resin layer is from about 5 to about 60%.
6. The process of claim 4 wherein the saponification degree of the EVOH contained in the oxygen absorbing resin layer is about 90% or more.
7. The process of claim 4 wherein the oxygen absorbent is an organic compound, a polymer having a secondary or tertiary carbon atom, a polyamide resin, or a powder of reducible metal.
8. The process of claim 4 wherein the oxygen absorbent is an organic compound.
9. The process of claim 8 wherein the organic compound has a double bond.
10. The process of claim 9 wherein the compound having a carbon-carbon double bond is selected from the group consisting of polybutadiene, polyisoprene, polychloroprene, poly(2-ethylbutadiene), poly(2-butylbutadiene), polypentenylene, polynorbornene, styrene-isoprene-styrene triblock copolymer, and polyoctenylene.
11. The process of claim 1 wherein a thickness of the multilayered oxygen barrier layer is from about 5 to about 100 μm.
12. The process of claim 1 wherein the multilayered oxygen barrier layer has a layered structure as follows: first oxygen barrier resin sublayer/oxygen absorbing resin layer/second oxygen barrier resin sublayer.
13. The process of claim 1 wherein the moisture resistant resin layer has a moisture vapor transmission rate of about 40·30 μm/m2 day or less at a temperature of about 40° C. and a relative humidity of about 90%.
14. The process of claim 1 wherein the moisture resistant resin layer is made of a resin identical to the melted resin.
15. The process of claim 1 wherein the container is retortable.