GB2137268A

GB2137268A - Gasket

Info

Publication number: GB2137268A
Application number: GB08308010A
Authority: GB
Inventors: Hiroshi Ishikawa; Masaki Takahashi
Original assignee: Nishiyama Corp
Current assignee: Nishiyama Corp
Priority date: 1983-03-23
Filing date: 1983-03-23
Publication date: 1984-10-03
Also published as: GB2137268B; GB8308010D0

Abstract

A gasket 3 for the door of a freight container is made of soft, i.e. plasticised, PVC; where the gasket comes into contact with the painted surface of the container, i.e. at 32, it is provided with a layer of a thermoplastic elastomer e.g. a styrene-ethylene-butylene-styrene block co-polymer, a polyurethane or a polyester. The elastomer layer prevents the migration of the plasticiser into the paint layer which would cause deterioration. The gasket is particularly recommended for use in marine containers where chlorinated rubber based paints are used. <IMAGE>

Description

SPECIFICATION Gasket The present invention relates to a gasket that is suitable for use as a sealing member of a container and the like.

Heretofore, as a sealing member for doors of various containers such as a marine container and the like, a gasket made of natural rubber or synthesized rubber has been used.

However, since these rubbers are expensive, in view of a cost, most of the gaskets have been replaced by gaskets made of soft vinyl chloride resin.

On the other hand in a container ship for accommodating the containers, in most of the ships bottom section, waterplane section, outer hull section and other exposed sections, chlorinated rubber series paint is used as an anti-corrosion paint against a sea water and a sea breeze. In practice, this chlorinated rubber series paint was employed as a result of experiences and practical uses over many years at ship manufacturing companies, hence with respect to a paint for a container also, often a ship manufacturing company designates to use chlorinated rubber paint, and it is no exageration to say that most of the marine containers are painted with chlorinated rubber series paint.

However, if a gasket made of soft vinyl chloride resin is mounted to a door portion of a container painted with chlorinated rubber series paint and it is held for a long period, then the phenomena would occur that a plasticizer contained in the soft vinyl chloride resin transfers into the chlorinated rubber series paint, hence softening as well as peeling of the paint occur, therefore a metallic portion of the container is exposed resulting in degradation of an anti-corrosion effect, and the corrosion is especially remarkable during a navigation.

In the past, in order to prevent this corrosion, it was a common practice to paint an acrylic acid series paint or an urethane series paint over the chlorinated rubber series paint only at the portion of the container where the gasket is mounted or where the container butts against the gasket, and so, careful attention and a great deal of labour was necessitated for the over-painting.

The inventors of this invention have earnestly investigated with respect to a method for obviating the above-mentioned shortcoming by modifying the structure of the gasket made of soft vinyl chloride resin, and as a result it has been discovered that a gasket of low cost in which a plasticizer is soft vinyl chloride resin does not transfer into a chlorinated rubber series paint can be obtained by forming a thermoplastic elastomer layer at the portion of the gasket which makes contact with a chlorinated rubber series paint over a long period.

One object of the present invention is to provide a gasket made of soft vinyl chloride resin in which a plasticizer does not transfer into a paint layer on a container.

According to one feature of the present invention there is provided a gasket made of soft vinyl chloride resin in which a thermoplastic elastomer layer is formed at the portion where said gasket makes contact with a gasket-mount body.

The gasket according to the present invention is used in doors of a marine container, a land container, a refrigerator car, a fresh food carrier car, a refrigerator, a refrigerated storage, an air-tight chamber, etc. and also used as a sealing member for a glass window of a ship. Especially the value of utilization is high in a marine container.

The above-mentioned and other objects, features and advantages of the present invention will become more apparent by reference to the following description of preferred embodiments of the invention taken in conjunction with the accompanying drawings, wherein: Figure 1 is a perspective view of a container with the gasket according to the present invention mounted thereon; Figure 2 is a partial enlarged front view of an opening-closing door; Figure 3 is a transverse cross-section view showing the state of mounting a gasket according to the present invention to an opening-closing door; Figure 4 is a transverse cross-section view showing another preferred embodiment of the present invention; and Figure 5 is a transverse cross-section view showing still another preferred embodiment of the present invention.

Now explaining the present invention in connection to its preferred embodiment, a container 1 is provided with a double door 2 on its one side surface, a gasket 3 is generally has a long length and fixedly mounted around the doors 2. The method of mounting the gasket to the door 2 is, as shown in Fig. 3, such that a press metal 33 is placed inside of a U-shaped gasket 3 and the gasket is threadedly fastened by means of a screw 34 via the press metal 33. Free ends of the gasket 3 are deformed by the elasticity of the gasket 3 per se as a result of opening and closing of the door, and when the door is closed, the gasket 3 makes tight contact with one end of the other door or with the frame of the container main body so that the interior of the container may be sealingly closed.

In the gasket 3 according to the present invention, the portion to be brought into contact with a gasket-mount body, for example, the container 1 is formed of thermoplastic elastomer 32, hence the gasket has such structure that a plasticizer contained in soft vinyl chloride resin may not transfer to the surface of the container. In other words, in a gasket made of soft vinyl chloride resin, the portion of the gasket fixedly contacting with the container door and the portion of the gasket butting against a door when the door is opened or closed are formed of thermoplastic elastomer layers 32. The gasket according to the present invention should not be limited to the illustrated gasket 3 but it could be a gasket having any structure. For instance, it could be a gasket 4 or a gasket 5 having a cross-section structure as shown in Figs. 4 and 5, respectively.Or else it could be a gasket for fixing a glass plate having a Hshaped cross-section structure. The gaskets 4 and 5 have the structures having a thermoplastic elastomer layer 42 and a thermoplastic elastomer layer 52, respectively, at the portions where soft vinyl chloride resin 41 and soft vinyl chloride resin 51 make contact with the gasket-mount bodies. Imaginary positions of the respective gasket mount bodies are shown by double-dotted chain lines.

While the vinyl chloride resin used for the gasket according to the present invention could be general vinyl chloride resin, such general one has an average polymerization degree of about 1500 or less, and so, for a long period of use its durability is degraded and its elasticity becomes insufficient. Accordingly, it is desirable to use vinyl chloride resin especially having an average polymerization degree of 2000 or more for the gasket according to the present invention. A resin including the aforementioned resin of 100 parts in weight and a plasticizer of 30-1 50 parts in weight is suitable for the gasket made of soft vinyl chloride resin. Then, the resin can be semi-permanently given a rubber elasticity, and can be prevented from becoming brittle.

On the other hand, as the thermoplastic elastomer layer to be formed in the gasket made of soft vinyl chloride resin, various kinds of elastomers can be used such as, for example, an elastomer principally made of stylene series block copolymer, stylene-ethylene-butylene stylene block copolymer, olefin series soft thermoplastic elastomer such as, for instance, vinyl acetate-ethylene series copolymer rubber. Besides, urethane series elastomers and polyester series elastomers can be used.

The gasket is a flexible structure having a thickness of 1-10mm and a most portion thereof is made of soft vinyl chloride resin. In the gasket, the thickness of the thermoplastic elastomer would vary depending upon the thickness of the gasket itself and the content of a plasticizer in the soft vinyl chloride resin, but the portion of the elastomer making contact with the mount body is necessitated to be 0.1 mm or thicker, and preferably a thickness of the elastomer of 0.5-1 mm is sufficient.

Claims

1. A gasket made of soft vinyl chloride resin in which at the portion where said gasket makes contact with a gasket-mount body is formed a layer of thermoplastic elastomer.

2. A gasket as claimed in claim 1, in which an average polymerization ratio of the vinyl chloride resin is 2000 or higher.

3. A gasket as claimed in claim 1, in which the gasket-mount body is a container.

4. A gskect as claimed in claim 1, in which said thermoplastic elastomer includes principally a stylene series block copolymer or a vinyl acetate-ethylen series copolymer rubber.

5. A gasket substantially as herein described with reference to and as shown in the accompanying drawings.