FR2769679A1 - Valve or pump seal - Google Patents

Abstract

The seal, designed for use in contact with a propellant or a solution such as water/ethanol, is made from a butyl-polyethylene mixture, preferably in a 1 : 1 ratio and of low density. The seal is made e.g. from a strip of material, produced by extrusion and laminated between rollers to obtain the required thickness.

Description

 The present invention relates to a valve or pump seal and more particularly to a neck seal intended to produce the sealed interface between said valve or pump and the neck of the container on which the valve or pump is mounted.

A seal according to the invention can also be used as a valve seal in a valve. In fact, the invention applies to any seal intended to come into contact with a fluid product such as a propellant capable of extracting compounds included in said seal. The invention will therefore find a preferred application in the field of packaging of certain pharmaceutical products in the form of sprayers, in which the pharmaceutical product must not be polluted by polluting components extracted from the valve or pump seals by the propellant.

 Indeed, a valve or pump seal, and in particular the valve neck seal, must meet several requirements. First, it must ensure a good seal to the propellant contained in the container with the fluid to be dispensed. Then, it must ensure a good seal against the water vapor coming from the atmosphere and which penetrates into the container. In order to avoid agglomeration and / or hydrolysis of the active particles, the rate of water vapor in the propellant should be kept below 300 ppm for a propellant such as HFA (hydro-fluoro-alkane ) with or without ethanol. Finally, the pump or valve seal must not release too many compounds which it contains and which are known by the term "extractables". These extractables are compounds extracted from the joint by the propellant which contaminate or pollute the fluid product to be distributed. Among these extractables, there are two categories: first, toxic such as nitrosamines, aromatic polynuclear, but also monomers. These toxics are generally in small quantities: nitrosatuifle (ppb), aromatic polymorphonuclear (ppm), monomers (ppb). They are therefore rare. But there are especially so-called majority products that are found in higher concentration.

Among these majority products, there are antioxidants, emulsifiers, oligomers and sometimes plasticizers. Oligomers are made up of low molecular weights and are found mainly in TPE elastomeric thermoplastics.

 The object of the present invention is to overcome the drawbacks of the prior art by defining a seal which is easy to cut and distribute and which releases very few pollutants such as oligomers or even plasticizers.

 The present invention relates to a valve or pump seal intended to come into contact with a product, such as a propellant or a solution of the water / ethanol type, the seal being produced from a butylepolyethylene mixture.

 Polyethylene forms a good barrier against extraction by a propellant such as HFA and moreover has a low coefficient of friction which makes the joints easier to cut and distribute.

 On the other hand, a seal made from a butyl-polyethylene mixture gives excellent sealing qualities both to water vapor and to propellants.

With a ratio of 1: 1, the qualities have been optimal.

 Advantageously, the butyl-polyethylene mixture is preferably low density.

 In particular, the seal is used as a neck seal forming a sealed interface between said valve or pump and the neck of the container on which said valve or pump is mounted.

 The invention will now be described more fully by describing a complete method of manufacturing seals according to the invention.

 We start by making strips using a flexible material capable of forming the joint. As the material of the invention, a butyl / polyethylene mixture, preferably low density, which is part of the family of TPE elastomeric thermoplastics, is used. In the following example, reference will be made to the TPE for simplicity. The TPE strips are obtained by extrusion through an extruder which pushes the molten TPE through an elongated slot-shaped die. At the exit, the unfinished strip is laminated between rolling rollers to give it the desired thickness.

 Polyethylene has good barrier effect characteristics to the extraction of polluting compounds contained in the joint. In addition, it has a low coefficient of friction, which facilitates the cutting of the strip thus coated and the distribution of the joints thus cut.

 Such seals can be used as a neck seal forming the sealed interface between the valve or the pump and the neck of the container on which it is mounted. It is also possible to use seals thus produced as a valve seal in valves.

Claims (4)

Claims  1.- Valve or pump seal intended to come into contact with a product, such as a propellant or a solution of the water / ethanol type, characterized in that the seal is produced from a butyl-polyethylene mixture.  2. A joint according to claim 1, in which the butyl-polyethylene mixture is preferably produced in a 1: 1 ratio.  3. A seal according to claim 1 or 2, wherein the butyl-polyethylene mixture is preferably low density.  4. A seal according to any one of the preceding claims, used as a neck seal forming a sealed interface between said valve or pump and the neck of the container on which said valve or pump is mounted.