GB2032892A - Venting Closure - Google Patents

Abstract

A venting closure 10 for a container having a threaded neck portion 2 comprises a cap having a crown and an internally-threaded depending skirt, the inside face of the crown of the cap receiving a liner 12 composed of a layer of an impermeable material, e.g. closed cell expanded polyethylene, at least partially faced on the surface away from the crown of the cap with a fibrous, spun-bonded polyethylene sheet material. <IMAGE>

Description

SPECIFICATION Venting Closure This invention relates to closures for containers, and especially to a closure which will vent when the internal pressure developing in the container becomes excessive.

- Containers often carry liquids, such as bleach, which due to storage in warm places, exposure to sunlight or subjection to agitation, will build up internal vapour pressures within the container in which they are confined. Such containers require self-venting closures, which are generally constructed in such a way that the cap liner permits the escape of gas to relieve the internal buildup of pressure.

The liner is usually formed of a pulpboard material fastened to the inside of the closure and having a thin disc of any suitable facing material disposed over the pulpboard material to protect it against deterioration caused by the contents of the container and contamination of the contents of the container by the liner material. The facing material is completely impervious to liquid and gas.

According to the present invention a venting closure for a container having a threaded neck portion comprises a cap having a crown and an internally-threaded depending skirt, the inside face of the crown of the cap receiving a liner composed of a layer of an impermeable material at least partially faced on the surface away from the crown of the cap with a fibrous, spun-bonded polyethylene sheet material as hereinafter defined.

The layer of impermeable material is suitably composed of closed cell expanded polyethylene, and this may, in the closure of the invention, be faced with a film of polyethylene.

The expression "fibrous, spun-bonded polyethylene sheet material" as used herein means a material formed by a process in which a polyethylene is spun into fibres in a spinneret, the fibres are laid up to form a mat in random nondirectional fashion and the mat is subjected to heat and pressure to bond the fibres together. A very suitable material is that marketed under the trade name "Tyvek".

The liner is inserted in the cap so that the impermeable material is adjacent the crown of the cap and that, when the cap is placed on a container, the facing of spun-bonded polyethylene is pressed onto the mouth of the container. The impermeable lining material will not be affected by any liquid wetting. Thus, the excess pressure due to gas in the container is relieved by the gas passing through the facing material and out around the threads of the closure to the atmosphere.

It will be appreciated that only that part of the liner which overlies the mouth of the container need be faced with the spun-bonded material, although it is preferred that the spun-bonded material form a complete facing for the liner.

The invention will now be described in greater detail by way of example, with reference to the accompanying drawing which is a cross-sectional view of one form of closure mounted on the neck of the container.

The neck 2 of a conventional container has a substantially flat upper surface 4 against which the liner presses to form a liquid-tight seal.

Threads 6 on the container engage with threads 8 of a conventional closure 10. The closure has a lining 12 which is composed of a lining material 14 and facing 1 6. The facing material is a fibrous, spun-bonded polyethylene, e.g. the material sold under the trade name "Tyvek". The material forms a membrane which has the ability under normal operating conditions to permit the passage of gas, but to prevent the passage of liquid. As such, it functions as a semi-permeable membrane.

The lining material 14 is an impermeable material, i.e. one which permits the passage therethrough neither of liquid nor of gas. It suitably is a sheet of expanded polyethylene.

The liner acts both as a seal and as a vent.

Excessive pressure which may be built up in the container is relieved by gas passing from the interior of the container to the atmosphere via the semi-permeable membrane 16 and the threads of the closure. (The arrow shows the passage of the gas). At the same time liquid in the container cannot pass through the two-layer liner and thereby escape.

Claims

1. A venting closure for a container having a threaded neck portion comprising a cap having a crown and an internally-threaded depending skirt, the inside face of the crown of the cap receiving a liner composed of a layer of an impermeable material at least partially faced on the surface away from the crown of the cap with a fibrous, spun-bonded polyethylene sheet material as hereinbefore described.

2. A venting closure according to claim 1, wherein the layer of impermeable material is composed of closed cell expanded polyethylene.

3. A venting closure, substantially as hereinbefore described with reference to the drawing.

4. A container closed by a closure as claimed in any of claims 1 to 3.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Venting Closure This invention relates to closures for containers, and especially to a closure which will vent when the internal pressure developing in the container becomes excessive. - Containers often carry liquids, such as bleach, which due to storage in warm places, exposure to sunlight or subjection to agitation, will build up internal vapour pressures within the container in which they are confined. Such containers require self-venting closures, which are generally constructed in such a way that the cap liner permits the escape of gas to relieve the internal buildup of pressure. The liner is usually formed of a pulpboard material fastened to the inside of the closure and having a thin disc of any suitable facing material disposed over the pulpboard material to protect it against deterioration caused by the contents of the container and contamination of the contents of the container by the liner material. The facing material is completely impervious to liquid and gas. According to the present invention a venting closure for a container having a threaded neck portion comprises a cap having a crown and an internally-threaded depending skirt, the inside face of the crown of the cap receiving a liner composed of a layer of an impermeable material at least partially faced on the surface away from the crown of the cap with a fibrous, spun-bonded polyethylene sheet material as hereinafter defined. The layer of impermeable material is suitably composed of closed cell expanded polyethylene, and this may, in the closure of the invention, be faced with a film of polyethylene. The expression "fibrous, spun-bonded polyethylene sheet material" as used herein means a material formed by a process in which a polyethylene is spun into fibres in a spinneret, the fibres are laid up to form a mat in random nondirectional fashion and the mat is subjected to heat and pressure to bond the fibres together. A very suitable material is that marketed under the trade name "Tyvek". The liner is inserted in the cap so that the impermeable material is adjacent the crown of the cap and that, when the cap is placed on a container, the facing of spun-bonded polyethylene is pressed onto the mouth of the container. The impermeable lining material will not be affected by any liquid wetting. Thus, the excess pressure due to gas in the container is relieved by the gas passing through the facing material and out around the threads of the closure to the atmosphere. It will be appreciated that only that part of the liner which overlies the mouth of the container need be faced with the spun-bonded material, although it is preferred that the spun-bonded material form a complete facing for the liner. The invention will now be described in greater detail by way of example, with reference to the accompanying drawing which is a cross-sectional view of one form of closure mounted on the neck of the container. The neck 2 of a conventional container has a substantially flat upper surface 4 against which the liner presses to form a liquid-tight seal. Threads 6 on the container engage with threads 8 of a conventional closure 10. The closure has a lining 12 which is composed of a lining material 14 and facing 1 6. The facing material is a fibrous, spun-bonded polyethylene, e.g. the material sold under the trade name "Tyvek". The material forms a membrane which has the ability under normal operating conditions to permit the passage of gas, but to prevent the passage of liquid. As such, it functions as a semi-permeable membrane. The lining material 14 is an impermeable material, i.e. one which permits the passage therethrough neither of liquid nor of gas. It suitably is a sheet of expanded polyethylene. The liner acts both as a seal and as a vent. Excessive pressure which may be built up in the container is relieved by gas passing from the interior of the container to the atmosphere via the semi-permeable membrane 16 and the threads of the closure. (The arrow shows the passage of the gas). At the same time liquid in the container cannot pass through the two-layer liner and thereby escape. Claims

1. A venting closure for a container having a threaded neck portion comprising a cap having a crown and an internally-threaded depending skirt, the inside face of the crown of the cap receiving a liner composed of a layer of an impermeable material at least partially faced on the surface away from the crown of the cap with a fibrous, spun-bonded polyethylene sheet material as hereinbefore described.

2. A venting closure according to claim 1, wherein the layer of impermeable material is composed of closed cell expanded polyethylene.

3. A venting closure, substantially as hereinbefore described with reference to the drawing.

4. A container closed by a closure as claimed in any of claims 1 to 3.