MXPA97007987A - Multi-layer flexible plastic film with controlled degradation for agricultural use - Google Patents

Abstract

The present invention relates to the improved composition of an opaque plastic film with multilayer structure, of at least two layers with controlled photodegradation characteristics. Said film is particularly effective to be used as padding of agricultural furrows where it is required to control the photodegradation of said film by the sun so that it degrades in a desired period and avoid its collection once the agricultural cycle is over. This film for quilting is made by the coextrusion process and can be formed by at least two layers of resins: a layer of polyolefin resin formulated with black pigment and additives stabilizers to Ultra Violet radiation and another layer of polyolefin resin formulated with photodegradable additives . The resin can be low or high density polyethylene (LDPE or HDPE) or ethylene or alpha-olefin copolymers (LLDPE). The black pigment is essentially black smoke, the Ultra Violet light stabilizer additive is mainly of the sterically hindered amines (HALS) type, benzophenones or deactivators of hydroperoxides or their mixtures and the photodegradable additive is mainly based on metal complexes. transition

Description

MULTI-LAYER FLEXIBLE PLASTIC FILM WITH CONTROLLED DEGRADATION FOR AGRICULTURAL USE. D E S C R I N C: The present invention relates to the improved composition of an opaque, coextruded, multilayer plastic film with controlled photodegradation characteristics. This film is particularly effective to be used as a quilting • agricultural furrows where it is required to control the photodegradation of said film by the sun in order to avoid its collection after the end of the agricultural cycle. This opaque film for agricultural mulch is elaborated by the coextrusion process and can be formed by at least two layers of resins: a layer of resin formulated with black pigment and stabilizing additives to the # Ultra Violet radiation and another layer of resin formulated with additives photodegradable. Example 1 .- One of the layers, which will act as protection to Ultra Violet radiation, may be formed by a resin selected from the group of polyolefins such as polyethylene (I), being this polyethylene either low or high density or copolymers of ethylene with 1 -butene,! -hexene or 1-octene or any of its mixtures. The density of (I) may be in the range of # 0.912 to 0.965 and its flow index between 0.2 to 6.0 g / 10 min. This resin is formulated with black pigment (II) mainly based on carbon black with a particle size that can vary between 19 to 95 nanometers; plus 5 can be formulated with an Ultra Violet radiation absorbing additive (III) mainly of the hindered amines type (HALS), benzophenones or deactivators of -hydroperóxidos or mixtures of these. The • composition of this layer can consist essentially of 50 to 95% by weight of (I) with 1 to 5% by weight of (II) and 0.05 to 0.2% by weight of (III). On the other hand, a second layer, which will act as a photodegradant, can be formed by a resin of the type of (I) formulated with a photodegradable additive.

(IV) mainly based on transition metal complexes. The composition of this layer may consist essentially of 50 to 95% in * weight of (I) with 1 to 6% by weight of (IV). The total thickness of the film is in the range of 10 to 50 microns and the thickness of each layer varies between 5 and 15 microns for the black protective layer to the sun and between 5 and 35 microns for the photodegradable layer.

Claims (4)

1. R E I V I N D I C T I O N S: 1.- An improved composition of coextruded plastic film of at least two layers with characteristics of controlled photodegradation for use in agricultural mulch. This film fulfills the essential characteristics of 5 an opaque film for agricultural mulch where the improvement is characterized by being formed of at least two layers, one layer acts as protection to the Ultra Violet radiation of the sun which, with the right thickness, allows to obtain # periods of induction in which a certain period is protected to a second photodegradable layer which will begin to disintegrate the film 10 after the end of the agricultural crop cycle or after a certain time; This is achieved with an adequate thickness and content of additives and pigments in each layer of the film. The composition of one of the layers consists of 50 to 95% by weight of (I) with 1 * to 5% by weight of (II) and 0.05 to 0.2% by weight of (H-I). While the second The layer consists essentially of 50 to 95% by weight of (I) with 1 to 6% by weight of (IV). Where (I) is formed by a low density polyethylene having a density in the range of 0.912 to 0.94 and a flow index in the range of 0.2 to 6.0 g / 10 min. (II) is formed by a black pigment, essentially carbon black with a particle size between 19 to 95 nanometers, while * (III) is formed by an ultra violet radiation absorber additive, mainly of the sterically hindered amines (HALS) type, benzophenones or hydroperoxide deactivators or their mixtures. For another 5 side, (IV) is formed by a photodegradable additive mainly based on transition metal complexes.
2. 2. An improved coextruded plastic film as defined in claim 1, wherein the improvement consists of using high density polyethylene (I) having a density in the range of 0.94 to 0.965 and an index of fluidity in the range from 0.2 to 6.0 g / 10 min.
3. 3. An improved plastic film as defined in claim 1, wherein the improvement consists in using polyethylenes (I) based on ethylene copolymers with 1-butene, 1 -hexene or 1-ketene with a density in the range from 0.916 to 0.965 and a flow index in the range of 0.2 to 6.0 g / 10 min.
4. 4. An improved plastic film as defined in claim 1, wherein the improvement consists of using as a base resin (I), mixtures of polyethylenes either of low density, high density or copolymers of ethylene with 1-butene , 1-hexene or 1-octene having a density in the range of 0.912 to 0.965 and a flow index between 0.2 to 6.0 g / 10 min. R E S U M E N: * The present invention relates to the improved composition of an opaque plastic film with multilayer structure, of at least two layers with controlled photodegradation characteristics. This movie is 5 particularly effective to be used as padding of agricultural furrows where it is required to control the photodegradation of said film by the action of the sun so that it degrades in a desired period and prevent its collection # once the agricultural cycle has ended. This film for quilting is elaborated by the process of coextrusion and 10 can be formed by at least two layers of resins: a polyolefin resin layer formulated with black pigment and Ultra Violet radiation stabilizing additives and another layer of polyolefin resin formulated with photodegradable additives. The resin can be low or high polyethylene "Density (LDPE or HDPE) or copolymers of ethylene with α-olefins (LLDPE). 15 The black pigment is essentially black smoke, the Ultra Violet light stabilizer additive is mainly of the sterically hindered amines (HALS), benzophenones or deactivators of hydroperoxides or their mixtures and the photodegradable additive is mainly based on metal complexes of Transition.