NOISELESS POLYMERIC FILM, AND CONTAINERS FOR MEDICAL USE MADE THEREOF

Abstract: A film is formed by a composition comprising a mixture of 50-100 weight % of an ethylene-butyl-acrylate copolymer (EBA) having a content of butyl-acrylate (BA) of 5-50 weight %, and 0-50 weight % of an elastomeric polyolefin. Laminates comprising a layer constituted by said film have excellent characteristics of noiselessness and softness.

Description: The present invention relates to a polymeric film with improved properties of noiselessness or silence as well as of softness and flexibility, and relates to containers and bags for medical use which are made of said film. For certain applications, in particular of the medical type, containers are required which are used in contact with the skin, such as, for example, containers or bags for surgical drainage called "ostomy" pouches, destined to collect secretions or excretory products of patients who have undergone surgical interventions. The use of such containers may be temporary or for the remainder of a patient's life. The principle requisite which such containers must satisfy is that of being unnoticable to the greatest extent possible, both by the patient himself and by other people. To this end, they should be soft and almost imperceptible upon contact with the skin, they must not rustle or produce noise in use, and furthermore, they must have good properties of durability, abrasion and puncture resistance, and be a barrier to odours and gasses in general. Various solutions to this problem have been proposed to date, among which is patent application GB 8309722 which proposes the use of a film basically composed of polymeric mixtures of polyolefin, chlorinated polyolefin, and chlorinated paraffin. The patent EP 59739 describes a composite shock-resistant film based on a polymeric mixture of at least 40% of chlorinated polyolefin with a polyolefin. Italian patent 1.163.372 describes the use of a film based on a mixture of ethylene-vinylacetate copolymer (EVA) with elastomeric polyolefin which also comprises a certain proportion of EVA. GB-A-2138431 describes a resin composition which comprises a block copolymer, an isotactic polypropylene and an ethylene acrylate copolymer which can be an ethylene butyl acrylate copolymer. Those compositions can be used for manufacturing medical bags. The main object of the present invention is to provide a multilayer film having superior characteristics of noiselessness and flexibility combined with exceptional characteristics of softness and comfort in contact with the skin. An object of the present invention is to provide containers especially for medical use made of said multilayer film, which are noiseless, flexible and soft. A not least object of the present invention is to provide containers as mentioned above, which have good characteristics of being a barrier to odours and of mechanical resistance. These and other objects which will become apparent hereinafter are acheived by a multilayer film according to the invention, having improved characteristics of noiselessness, softness,and flexibility which multilayer comprises at least three layers of which an intermediate layer comprising a polymeric material functions as a gas or odour barrier interposed between two outer layers wherein (a) at least one of the outer layers comprises a blend of from 50 to 100 weight % of an ethylene-butyl-acrylate copolymer having a content of butyl-acrylate of 5-50 weight %, mixed with 0-50 weight % of at least one elastomeric polymer, and (b) the other outer layer comprises an olefinic copolymer with a comonomer selected from vinyl acetate and acrylate esters. The present invention is based on the use of an ethylene-butyl-acrylate copolymer (EBA) to form at least one layer of a multilayer laminated film to impart to the laminated film, exceptional characteristics of noiselessness and softness upon contact with the skin, in addition to the characteristic of mechanical resistance, in particular durability, abrasion and puncture resistance, as well as being heat-sealable. The EBA copolymer has a content of butyl-acrylate (BA) of 5-50 weight %, preferably 7 to 30 weight %, and a molecular weight corresponding to a Melt Flow Index (MFI) from 1 to 7 g/10 min. EBA copolymers of this type are available, for example, from the NESTE OY company in Finland, and are sold under the name NESTE DFDS 6440, 6427, and 6470. EBA copolymer can be used alone or in a mixture with up to 50 weight % of the mixture being constituted by an elastomeric polyolefin. The elastomeric polyolefin may be chosen, for example, from, ethylene-propylene rubbers having an ethylene content of at least 50%, ethylene-propylene-diene rubbers having an ethylene content of at least 50% or chlorinated polyethylene having a chlorine content of at least 20%. The composition of the film or layer of EBA of a multilayer laminated film according to the invention may further comprise from 0.1 to 5 weight % of an additive such as an anti-blocking agent, a flowing agent, a plasticizer, a stabilizer, an extrusion coadjuvant, or a mixture thereof. Such additives may be selected from those which are conventionally used for the desired purpose. For example, as an anti-blocking agent, one may use a silica gel such as that sold by W.R.Grace (U.S.A.) under the name Syloblock; as a flowing agent one may use amidic waxes such as erucamide or ethylene-bis-stearamide, and as a plasticizer one may use epoxydized soyabean oil or chlorinated paraffin, such as, for example, that sold by the Hoechst company under the name CERECLOR® 56. The multilayer laminated film according to the invention comprises at least one of the above-mentioned layers of EBA together with other layers as defined herein formed in polymeric material suitable for the envisaged use. In particular, for use in drainage containers for medical use, the laminated film comprises at least one layer having the function of providing a barrier against odours and gasses. Any type of polymeric material may be used to carry out the barrier function, and preferably a polymer selected from vinylidene chloride polymers and (PVDC) copolymers with comonomers selected from acrylic esters, acrylic acid, and vinyl chloride, ethylene-vinylalcohol (EVOH) copolymers, vinyledene fluoride-vinyl fluoride copolymers, polyamides and mixtures thereof. The laminated film acording to the invention comprises at least three layers of which an internal layer functions as a barrier interposed between two external layers. For the external layers, either two layers of EBA may be used as described above, or one layer of EBA and one further layer of another polymer selected from olefin copolymers with a comonomer selected from vinyl acetate and acrylate esters. The thickness of the laminated film according to the invention may vary from 20, preferably 30 to 150 µm, with the layer or layers of EBA constituting at least 50 % of the total thickness. Usually, the barrier layer has a thickness which varies from 5 to 25 µm, whilst each of the external layers has a thickness between 5 and 70 µm. The laminated film may include further layers, for example, intermediate binding layers which improve the adhesion between the external EBA layers and the barrier layer, or layers which improve certain properties of the laminated film such as the mechanical resistance or the heat sealability. To this end, known polymers or copolymers may be used for imparting the above-mentioned properties, according to neccessity. The laminated film according to the invention can be obtained by means of conventional technology, for example, by coextrusion of the EBA copolymer adjacent to a barrier layer on one or both of its sides, with or without the interposition of binding layers, or alternatively by the coextrusion of other polymers or copolymers to form other required layers. Before extrusion, the ingredients of the composition destined to form the layer or layers of EBA can be mixed and granulated by means of a double screw extruder. The coextrusion of the different layers of the laminate can be carried out by means of the technique of coextrusion through a circular die with multiple concentric slots by using the insufflation of a bubble of hot air, whereupon the coextrusion is cooled, cut into segments of desired length and welded, for example by high frequency or heat to produce containers or bags for medical use. The following exclusively illustrative examples show some possible embodiments of the laminated film according to the present invention. Example 1. Various laminated films with three layers A/B/C were prepared which had the following composition: Layer A: 100% EBA /NESTE DFDS 6440 (17% BA, MFI 2)/, 40 µm. or: 50% EBA /NESTE DFDS 6427 (27% BA, MFI 4) / + 50 % ethylene-propylene rubber /DUTRAL® CO / 034 / PLF/, thickness 40 µm. or: 50% EBA /NESTE DFDS 6470 (7% BA, MFI 1)/ + 50% ethylene-propylene-diene rubber /DSM KELTAN® TP 9200/, thickness 40 µm. or: 60% EBA /NESTE 6440/ + 35% chlorinated polyethylene /HOECHST HOSTAPREN® 803 (36% Cl)/ + 5% plasticizer (HOECHST CERECLOR® 56-56% Cl), thickness 45 µm. Layer B: is PVDC, thickness 15 µm. or: is EVOH, thickness 10 µm. Layer C: is the same as layer A or: ethylene-vinylacetate / DUPONT ELVAX® 3165 (18% VA, MFI 0.8) /, thickness 20 µm. or: ethylene-methylacrylate /GULF 2255 (18% MA, MFI 2)/, thickness 20 µm. Example 2 Various laminated films with five layers D/E/F/G/H were prepared which had the following composition: Layer D: is the same as layer A of example 1 Layer E: is 100% EBA / NESTE DSDF 6427 (27% BA, MFI 4)/, thickness 10 µm. or: ethylene-vinylacetate /DU PONT ELVAX®·3175 (20% VA, MFI 7)/, thickness 5 µm. or: a modified EVA /DU PONT BYNEL CXA-E-162/, thickness 5 µm. Layer F: is the same as layer B of example 1 Layer G: is the same as layer E Layer H: is the same as layer C of example 1.

Claims: A multilayer film having characteristics of noiselessness, softness, and flexibility comprising: at least three layers of which an intermediate layer comprising a polymeric material functions as a gas barrier interposed between two outer layers wherein (a) at least one of the outer layers comprises a blend of from 50 to 100 weight % ethylene butyl acrylate copolymer, having a butyl acrylate content of from 5-50 weight % and 0 to 50 weight % of at least one elastomeric polyolefin, and (b) the other outer layer comprises an olefinic copolymer with a comonomer selected from vinyl acetate and acrylate esters. A multilayer film according to claim 1, characterized in that said ethylene-butyl acrylate copolymer has a butyl-acrylate content from 7 to 30 weight %. A multilayer film according to claim 1 or 2, characterized in that said elastomeric polyolefin is selected from ethylene-propylene rubbers, ethylene-propylene-diene rubbers, and chlorinated polyethylene. A multilayer film according to one or more of the preceding claims, characterized in that said composition further comprises from 0.1 to 5 weight % of at least one additive selected from anti-blocking agents, flowing agents, plasticizers, a stabilizer, and an extrusion coadjuvant. A multilayer film according to claim 1 to 4, characterized in that said gas barrier layer is formed by a polymer selected from polymers and copolymers of vinylidene chloride with comonomers selected from acrylic esters, acrylic acid and vinyl chloride. A multilayer film according to claim 1 to 5, characterized in that it has a total thickness between 20 and 150 µm of which at least 50% is constituted by the thickness of said at least one outer layer a) of claim 1. A multilayer film according to claim 1 to 6, characterized in that it is obtained by means of coextrusion of said layers. Container having improved characteristics of noiselessness, softness, and flexibility characterized in that it is made of a multilayer film according to one or more of claims 1 to 7. Container according to claim 8, for medical use.

Inventors: MARTINI, FRANCESCO, PERAZZO, LUIGI
Applicants: W.R. GRACE & CO.-CONN.
Application year: 1988
Main classification: C08J5
IPC codes: C08F10, C08L23, C08L31, B32B27, C08J5, C08F8, A61L26