EP0174425A2

EP0174425A2 - Anti-NBC (nuclear, biological or bateriological, chemical) overshoe and its manufacturing process

Info

Publication number: EP0174425A2
Application number: EP85102503A
Authority: EP
Inventors: Oreste Fabbro
Original assignee: MORGAN TECHNIQUE Ltd; MORGAN TECH Ltd; SGE Generale Elastomeri SpA Soc
Current assignee: SGE Generale Elastomeri SpA Soc
Priority date: 1984-08-30
Filing date: 1985-03-06
Publication date: 1986-03-19
Also published as: CH662253A5; DE3582541D1; EP0174425B1; GB2163638B; DE174425T1; EP0174425A3; GB2163638A

Abstract

The invention is characterised in that it comprises a textile insert (1) which is completely permeated by and embedded in the mixture (2) and is made inseparable from the latter by means of moulding and vulcanisation in an injection-moulding press with a closing pressure of approximately 200 atmospheres.

This insert is embedded in the mixture in an asymmetrical manner, as a result of which externally the insert is covered with a thick layer of rubber, whereas internally the mixture permeates beyond the insert on account of the moulding pressure and reaches a reduced thickness of 0.1mm. Thus, unlike those of the prior art, anti-NBC overshoes are obtained which have an ergonomic shape, are without joints, and hence are practically impermeable to NBC aggressive agents, and which have excellent mechanical characteristics.

They are used, in particular, for protection against the attacks of chemical, biological and bacteriological agents and for protection against thermonuclear radiation.

Description

The development of nuclear technologies and their varied applications, along with the preparation of new chemical, biological or bacteriological aggressive agents, has brought about a need for suitable garments or articles which can be worn by authorised personnel whilst performing repairs, overhauls and maintenance work, by the civil population in the event of accidents or catastrophes and by the special civil defence corps in the course of their duties and during decontamination operations.
Furthermore, in a manner consistent with the threat of an NBC war, the General Staffs of the armed forces of the technologically advanced countries have commissioned the various research institutes and specialised companies to undertake product research and development studies in this direction, that is regarding how to defend oneself and, if necessary, neutralise an NBC threat.
In this respect there may be cited the specifications of NATO, which in 1977 was already issuing precise instructions to its member countries, namely that the troops should be provided with equipment constituting an effective form of defence for resisting chemical, biological and bacteriological attacks and for entering the scene of the action, without danger, after thermonuclear attacks.
In particular, various models of the overshoe have been produced, which tend to guarantee impermeability with respect to NBC aggressive agents and at the same time possess the required degree of mechanical strength.
All of the known models (from Canada, Great Britain, Belgium and Italy) were produced by means of a process involving a rubberised fabric; the latter, suitably cut, is glued and shaped on an aluminium last and the whole assembly is vulcanised in an autoclave.
In Germany, for example, an overshoe has been produced by means of compression moulding; this article has a very low mechanical strength which does not satisfy in any way the conditions stipulated in the specifications.
The inventor has provided an overshoe and an associated Manufacturing process, described below, which are complex tely novel and avoid all of the disadvantages of the prior art: overshoes with joints which have low reliability as regards the risk of leaks and/or having low mechanical strength; complex and costly manufacturing processes.
The anti-NBC overshoes which are the subject of the present invention, in contrast, possess high characteristics as regards quality since they have an external surface without joints, i.e. there is no interruption of the surface continuity; as a result, they remain practically impermeable without losing the necessary mechanical characteristics and hence satisfy the conditions required.
This eliminates in practice any possibility of the NBC aggressive agents penetrating due to manufacturing defects or as a result of wear of the joints.
The manufacturing process, which is also the subjects of the invention, is characterised, on the one hand, by improved economy and speed of production and, on the other hand, by the fact that it makes it possible to obtain easily overshoes which have superior quality characteristics, impermeability and resistance.
The present invention relates to an anti-NBC overshoe, comprising a textile insert which is completely embedded in a suitable mixture based on vulcanised rubber and which is inseparable from the said mixture, characterised in that it does not have any internal or external joints and in that there is no interruption of the surface continuity so that it does not allow any possibility of the NBC aggressive agents penetrating inside, but still possesses excellent mechanical characteristics.
In particular the anti-NBC overshoe is characterised in. that the textile insert, which is completely embedded in and permeated by the mixture based on vulcanised rubber, in the manner of a core, is completely off-centre with respect to the covering formed by the above-mentioned mixture, this mixture having'on the outside of the said textile substrate a thickness of at least two mm, this mixture permeating the said substrate and covering the internal surface of the said substrate with a thin layer of a thickness of about 0.1 mm.
Also forming part of the invention is a process for manufacturing the anti-NBC overshoe, completely made of rubber and without joints, consisting essentially of the following operations:

a) Fitting of a textile insert, which has been appropriately prepared, onto the male part of an appropriately shaped injection mould;
b) Closing of the mould and consequent tensioning of the textile insert which thus adheres completely to the said male part of the injection mould;
c) Injection of a high-pressure rubber-based mixture into the mould by means of an injection press so as to make a sufficient layer of mixture penetrate beyond the above-mentioned textile insert, which is thus completely permeated by and embedded in the rubber itself;
d) Vulcanisation, in the mould, of the mixture until completion, after which mixture and insert are intimately bonded, thereby giving rise to an inseparable whole.

There now follows a description of a particular embodiment of the invention, with reference also to its production cycle, in relation to the Figures of the attached drawings, without, however, detracting in any way from the general nature of the subject of the invention itself.
Figure la shows a perspective view of a particular embodiment of the overshoe, as designed with excellent characteristics from the ergonomic point of view; it can, in fact, be very easily put on and taken off; this embodiment has also been the subject of an application filed for a model.

Figure Ib shows a plan view of the anti-NBC overshoe which is the subject of the invention, seen from the sole, the said overshoe being provided with the anti- slip pattern and relief.
Figure 1c shows a section of the overshoe at the level of the instep.
Figure 2 shows a flow chart of the process for manufacturing the anti-NBC overshoe, broken down into its most important operations.

The anti-NBC overshoe, in a more characteristic embodiment (Fig. la), is shaped in an ergonomic manner so as to allow it to be easily put on or taken off, the cross-section 3 of entry, or respectively the lenght of the leg-piece 9, being about 9/16, or respectively 3/4, of the cross-section, or length, of the upper 4.
The toe 5 of the overshoe is thus extremely short, whereas a bulge at the heel 6 further facilitates introduction, or removal of the foot once inside. In practice an overshoe is obtained in which the cross-section at the instep 7 and the cross-section at the upper end of the leg-piece 9 are very similar in size to the area of the upper 4.
The height of the leg-piece 9 can be chosen as required, in accordance with the various requirements, from the foot 10 of the anti-NBC overshoe. The anti-NBC overshoe is fixed to the leg by means of a cord or lace which passes through the holes 8 in the upper edge of the leg-piece 9 and which has precisely the function of fastening the overshoe to the leg.
The sole 11 has a special relief pattern to prevent slipping (Fig. lb).
This particular embodiment, because of its characteristic features, has also been the subject of an application for a model.
Structurally, the overshoe which is the subject of the invention (Figures la and 1c) consists of the textile insert 1 which is made of polyamide fabric and has been specially woven and prepared and which is completely permeated by and embedded in the mixture 2 based on butyl or nitrile rubber to which KOEDUR has been added.
This insert 1, which is completely permeated by the mixture and embedded in it in the manner of a core, is off-centre with respect to the said mixture in the sense that it is arranged asymmetrically with respect to the covering formed by the said mixture.
Externally the covering layer on the insert, which insert has a thickness of 0.3 + 0.1 mm, can reach a thickness of 2 + 0.1 mm on the leg-piece, 2,3 + 0.1 mm on the toe and 3.2 (+0.4, -0.2) mm on the sole, whereas internally the layer of mixture, which has penetrated through the textile insert during the injection-moulding operation, reaches the thickness of 0.1 + 0.02 mm.
The overshoe thus consists completely of rubber on the outside and is without joints, whereas on the inside it is permeated by the mixture which extends by a thin layer beyond the insert, the insert and mixture, after vulcanisation, thereby forming a whole which is intimately bonded and inseparable.
In this way a high, almost total degree of impermeability is guaranteed, whilst excellent mechanical characteristics are retained.
There now follows a detailed description of the production cycle (Figure 2).
Moulds are made from tempered AQ 50 steel suitable for treatment by nitriding. The moulds are intended for injection moulding and consist of:

- a male part shaped at an angle of 75
- jaws
- a cover

Due to the special shape of the male part, the textile insert can be introduced and the finished product removed despite the almost complete inelasticity.
The textile insert 1 is made of polyamide fabric with 12 beating-up operations both for the warp and for the weft and is prepared from pieces of cloth which are hollow-punched at 45⁰ with respect to the beating-up; thus the elasticity required to compensate for the variability of the article is produced and perfect adaptability to the male part of the mould is ensured. The mixture for moulding the anti-NBC overshoe is based on a butyl or nitrile rubber to which KOEDUR has been added. The textile insert is fitted onto the open male part and, when the mould is closed, is tensioned and adheres perfectly to the male part.
The mixture is injected at a pressure of approximately 200 atmospheres so as to make a layer of about 0.1 mm penetrate beyond the textile insert, which is thus completely permeated by and embedded in the rubber and hence in inseparable from the latter once the vulcanisation process has been completed. At the end of the cycle the overshoe consists completely of rubber on the outside and is without joints.
Anti-NBC overshoes are thus obtained which are particularly suited for protection against NBC aggressive agents and which can be used by the civil population, by civil defence personnel in the event of an NBC catastrophe, by specialists who operate, repair, overhaul and maintain NBC plants and by troops in the event of an NBC threat or conflict.

Claims

1. Anti-NBC overshoe, comprising a textile insert (1) which is completely embedded in a suitable mixture based on vulcanised rubber (2) and which inseparable from the said mixture, characterised in that it does not have any internal or external joints and in that there is no interruption of the surface continuity so that it does not allow any possibility of the NBC aggressive agents penetrating or passing inside, but still possesses excellent mechanical characteristics.

2. Anti-NBC overshoe according to Claim 1, characterised in that textile insert (1), which is completely embedded in the mixture based on vulcanised rubber (2), in the manner of a core, is completely off-centre with respect to the covering formed by the above-mentioned mixture, this mixture having on the outside of the said textil substrate a thickness of at least two mm, this mixture permeating the said substrate and covering the internal surface of the said substrate with a thin layer of a thickness equal to about 0.1 mm.

3. Anti-NBC overshoe according to Claim 1 or 2, characterised in that it is shaped in an ergonomic manner, the cross- section of the leg-piece (9) being about 9/16 of that of the upper (4) so as to allow the said overshoe to be easily put on or taken off, whereas the said overshoe is fixed to the leg by means of a lace or cord which passes through the holes (8) in the upper edge of the leg-piece (9).

4. Process for manufacturing the anti-NBC overshoe, completely made of rubber and without joints, according to Claim 1, 2 or 3, characterised in that it comprises the following operations:

a) Fitting of a textile insert (1), which has been appropriately prepared, onto the male part of an appropriately shaped injection mould;

b) Closing of the mould and consequent tensioning of the textile insert (1) which thus adheres completely to the said male part;

c) Injection under high pressure of a rubber-based mixture into the mould by means of an injection press so as to make a sufficient layer of mixture penetrate beyond the above-mentioned insert, which is thus completely permeated by and embedded in the rubber itself;

d) Vulcanisation, in the mould, of the mixture (2) until completion, after which mixture (2) and insert (1) are intimately bonded, thereby giving rise to an inseparable whole.

5. Process according to Claim 4, characterised in that the male part of the injection mould is shaped at an angle of 75⁰ so as to allow introduction of the textile insert and removal of the finished vulcanised product, despite the almost complete inelasticity.

6. Process according to Claim 4 or 5, characterised in that the textile insert (1) is made of polyamide fabric with 12 beating-up operations both for the warp and for the weft and is prepared from pieces of cloth which are hollow-punched at 45⁰ with respect to the beating-up so as to produce the elasticity required to compensate for the variability of the article and so as to ensure perfect adaptability to the male part of the mould,

7. Process according to Claim 4, 5 or 6, characterised in that the mixture for injection-moulding of the anti-NBC overshoe is based on butyl rubber to which KOEDUR has been added.

8. Process according to Claim 4, 5 or 6, characterised in that the mixture for injection-moulding of the anti-NBC overshoe is based on nitrile rubber to which KOEDUR has been added.

9. Process according to one of Claims 4 to 8, characterised in that the mixture is injected with a closing pressure of the injection-moulding press equal to about 200 atmospheres, so as to obtain the penetration of a layer of mixture of at least 0.1 mm of thickness beyond the textile insert and on the inside of the latter, in addition to the external covering of the same.

10. Process according to Claim 9, characterised in that the textile insert is completely permeated by and embedded in the mixture, thereby making it completely inseparable from the said mixture once vulcanisation has been completed.

11. Use of the anti-NBC overshoe according to Claim 1, 2 or 3 for protection against nuclear radiation and attack by chemical, biological and bacteriological aggressive agents.

12. Use of the anti-NBC overshoe according to Claim 1, 2 or 3 in preparation for or following an NBC catastrophe.