GB2218320A - Protective clothing - Google Patents

Abstract

A protective garment suitable for electronic clean-room use, or use in the pharmaceutical or food industries, comprises an upper body portion 1, a lower body portion 2 and a hood portion 3. The front 4 of the upper body portion is comprised of air impermeable material giving 100% filtration of 0.5 micron particles and at least a portion (5, Fig 2) of the back is composed of an air permeable material giving at least 80% filtration of 0.5 micron particles. The garment also includes one or more sections of resiliently stretchable material, viz. at the neck, the cuffs at the wrists and ankles and a section at the back of the waist. The garment is substantially composed of material containing electroconductive strands with the lower body portion preferably having the higher density electroconductive facility. A side entry slidable fastener 8 is provided. The garment gives good filtration properties for the majority of bacteria and reduces dust emission due to the reduction of the "bellows" effect. <IMAGE>

Description

Protective Clothing This invention relates to protective clothing suitable for use to prevent or reduce particulate or bacterial transmission from an operative or his clothing into his working environment as well as to provide the operative with protection against spillages of corrosive or other deleterious liquids. Such clothing is of use in clean rooms in the electronics industry in which semiconductor wafers or integrated circuitry based thereon are treated or manufactured, or in the the food or pharmaceutical industries in which it may be desired to prevent or reduce bacterial contamination of foods or drugs.

There is normally considerable particulate emission from operatives although this is not noticable except in particularly sensitive environments as exemplified above.

Such emission may derive from skin particles shed by the operative, or from fibre particles shed by his clothing in use, or may derive from extraneous dust which has been deposited in the interstites of his clothing in normal use.

There can also be bacterial emission from the operative or his clothing and it may be important to prevent contamination of, for example, pharmaceutical products by such emissions.

To prevent or reduce particulate or bacterial emission from operatives it is normal practice for operatives to wear coverall garments, often integral garments composed of an upper body portion including arms, a lower body portion including legs and a hood portion which usually includes, or has provision for, a face mask to provide filtration capability for the operative's breath. Such garments are often composed of vapour impervious material and can be extremely unpleasant to wear for any extended period of time.

One example of a prior integral coverail suit for clean-room use is disclosed in United States Patent No. 4677696. In that coverall all--seams are covered by airtight tape so as to securely prevent dust from leaking from inside to outside. The ends of the arms and legs of the garment are closed by cuffs and there are drawstrings at the waist and neck.

Garments of the above type suffer from a "bellows" effect in which the movements of the operative cause local variations in pressure within the garment. These variations cause the expulsion pf particulate laden air, for example through cuffs, or through slidable fasteners. Expulsion through cuffs, particularly, can cause contamination problems due to proximity-to-the point of work.

According to the present invention particulate, or bacterial contamination in the vicinity of the point of work for example by particulate emission through cuffs, may be maintained at acceptable levels by the judicious use of a combination of air permeable and air impermeable fabrics in a coverall garment. Limited particulate emission is tolerated but is directed to points distant from the point of work. Additionally it has been found, as a further feature, that a particular profile of antistatic ability, which is greater in the lower part of the garment, is advantageous.

Accordingly the present invention provides an integral garment suitable for clean-room use comprising an upper body portion including arms together with a lower body portion including legs and a hood portion the front of the upper body portion being composed of a single sheet of air impermeable material giving substantially 100% filtration of 0.5 micron particles, at least a portion of the back of the upper body portion being composed of an air permeable material, preferably having an air permeability of about 0.5cc/cm2/sec to 5.0cc/cm2/sec and giving at least some but preferably at least 80% filtration of 0.5 micron particles the garment preferably also including one or more sections of resiliently stretchable material arranged to tension the upper body portion of the garment in at least the vertical direction during use to reduce the void volume within that portion.

Such a garment prevents or reduces the "bellows effect" and is comfortable for extended periods of wear. Besides giving particulate filtration to normal clean-room standards it is also effective to reduce the emission of the many bacteria having largest dimensions above about 0.5 microns or even to substantially eliminate the emission of bacteria only somewhat larger than that.

The garment is particularly suitable for use by a sitting operative in a clean room having air extraction at a low level. Clearly the particular design of the garment may be conditioned by the precise intended use as to, for example, the precise extent of the upper body portion and the particular material of construction used to form it.

Preferably the upper body portion extends to about hip level. Preferably the front of the upper body portion, composed of air impermeable material, extends around at least a part of the sides of the operative to maximise the protective effect of the garment at the point of work.

Preferably the resiliently stretchable material comprises garment inserts at least at the base of the back of the upper body portion and/or at the neck and is of a sufficient area to give stretch capability in the vertical direction to the garment as a whole of at least about 2cm together with sufficient stretch capability in the horizontal direction to give a snug fit to the operative.

To avoid destroying the integrity of the upper front of the garment a means of entry for the operative at another point is preferably provided. It has been found that a side entry comprising a slidable or other suitable fastener from the armpit and down one side to below hip level is particularly easy to use and minimises the length of the slidable fastener required in comparsion with the crotch entry taught in US Patent No. 4677697 which latter entry is, however, also usable. A back entry is another possibility.

The upper front of the garment is preferably comprised of a polymer-coated fabric, suitably a twill, or a polymeric sheet, to give a complete air and particulate barrier and to give the operative protection from spillages of, for example strong acid or other corrosive or noxious substances from the work station. Preferably the entire arms, save possibly for cuffs, are also composed of such a material. A polyurethane-coated polyester fabric having electroconductive strands at suitable intervals, for example forming a 0.5cm grid, ic particularly suitable. Such a fabric is available from Teijin Limited under the Trade Name SELGUARD W. Alternatively a coated polyamide fabric or other suitable fabric may be used.It is understood that the effect of the invention may also be attained by the use of a front body portion having sealed seams since the essential concept of air impermeability would be utilised.

Such a construction is regarded as falling, to practical purposes, within the term "single sheet".

The back of the upper body portion of the garment is preferably comprised of an air permeable material giving at least 90% filtration of 0.5 micron particles and at least 85% filtration of 0.3 micron particles or, particularly preferably giving at least 95% and at least 90% filtration respectively of such particles. A preferred material is a taffeta weave continuous filament polyester fabric preferably having electroconductive strands at similar intervals to the front of the upper body portion of the garment. Preferably the hood is made of a similar material to the back of the upper body portion. A suitable material is available from Teijin Limited under the Trade Name SELGUARD M.

The resiliently stretchable material is preferably capable of stretch in two directions. Such a material may have some particulate barrier properties although it may be less effective in this respect than the other fabrics utilised. The area of the garment occupied by the resiliently stretchable material is preferably kept to a minimum to achieve the required tensioning of the garment and the required range of fit and is preferably sited at the back only of the main body portion and, possibly, of the neck. The degree of stretch provided by the material is preferably from 0% to 30%, particularly preferably from 10% to 30% in the horizontal direction, and from 0% to 30% particularly preferbly from 5% to 20% in the vertical direction. Such properties are suitably provided by fabric available from Roquimet under the Trade Name Lycra.Fabrics of the type described are capable of high quality decontamination.

The lower body portion of the garment is preferably composed of a durable and relatively heavyweight fabric with good air and moisture permeability, some degree of filtration capacity for particles and excellent antistatic properties. The function of this portion of the garment is to provide good wearing properties and a degree of operator comfort due to its air and moisture permeability. Such a fabric may, for example be a texturised continuous filament polyester with electroconductive strands, preferably high density electroconductive strands which may preferably be at from 0.2 to 0.5cm intervals in a grid arrangement. Such a fabric may, and preferably does, give at least 70% filtration of 0.5 micron particles preferably at least 75% filtration for 0.3 micron particles.Such properties are suitably provided by a fabric available from Teijin Limited under the designation T76997 Twill. Leakage of particles from this portion of the garment is acceptable in a suitably ventilated clean room since the leakage will be at below the working level.

The hood of the garment preferably has an aperture for the face of the operative who will usually wear a separate disposable filter over nose and mouth. Preferably the below eye level portion of the face aperture is covered by an insert of a lightweight fabric giving good sub-l micron filtration capability to reduce the effect of possible particle shedding by the disposable filter. A voile is a suitable fabric for this purpose.

Other properties of the materials used for the main garment portions are preferably as stated in the following Table.

Table Front Upper Back Upper Lower Body Body Body + Hood Moisture 0-2000 5000-10,000 5000-10,000 Permeability preferably preferably preferably g/m2/24 hrs 0-1500 5000-8000 5000-8000 Air Permeability 0 0.5-5 > 5-25 cc/cm2/sec preferably preferably 0.5-2 10-20 Static Charge < 12 < 5 < 4 pc/m2 preferably preferably preferably < 8 < 4 < 2 Weight gm/m2 100-200 50-150 100-250 The garment is suitably constructed using seams which individually do not leak to a greater extent than the more permeable material in any particular seam. This may reduce or eliminate the need for completely impermeable sealed seaming.

A particular embodiment of the invention will now be described by way of Example and with reference to Figures 1 and 2 attached hereto.

FIGURE 1 is a front view not to scale of garment according to the invention.

FIGURE 2 is a rear view not to scale of the same garment.

The garment comprises an upper body portion 1, a lower body portion 2 and a hood 3. The front of the upper body portion and all of the arms are made of polyurethane coated polyester twill woven fabric 4 with electroconductive strands on a 0.5cm grid arrangement. The fabric gives 100% filtration for 0.3 micron and 0.5 micron particles, is air impermeable, has a moisture vapour permeability of 1200 gm/m2/24 hours, accepts a static charge of 6.0 pc/m2 2 and a fabric weight (including coating) of 144 gm/m2.

The centre of the back of the upper body portion and the hood are made of a continuous polyester taffeta weave fabric 5 having electroconductive strands in a 0.5 grid arrangement. The fabric gives a 95% filtration of 0.5 micron particles and 90% filtration of 0.3 micron particles, has an air permeability of lcc/cm2/sec, a moisture vapour permeability of 7000 gm/m2/24 hours, accepts a static charge of 1.5 uc/m29 and has a fabric weight of 90 gm/m2.

The lower body portion 6 of the garment is made of a texturised continuous filament polyester twill fabric having high density electroconductive fibres in a 0.3cm grid arrangement. The fabric has an air permeability of 16 cc/cm2/sec, a moisture vapour permeability of 7000 gm/m2/24 hours, accepts a static charge of 1.0 uc/m2 and has a fabric weight of 160 g/m2.

The cuffs at wrists and ankles, the neck and insert at the back of the waist of the garment is made of two way stretch Lycra fabric 7 giving about a 15% stretch capability in both horizontal and vetical directions.

A slidable fastener 8 is provided in the centre of the side of the garment for operative entry.

The hood front aperture is made of a lightweight voile fabric 9 giving good filtration of particles greater than 1 micron.

The garment is suitable for Class 10 clean room use.

Claims (11)

1. An integral garment suitable for clean-room use comprising an upper body portion including arms together with a lower body portion including legs and a hood portion the front of the upper body portion being composed of a single sheet of air impermeable material giving substantially 100% filtration of 0.5 micron particles, at least a portion of the back of the upper body portion being composed of an air permeable material giving at least 80% filtration of 0.5 micron particles the garment also including one or more sections of resiliently stretchable material arranged to tension the upper body portion of the garment during use to reduce thevoid volume within that portion.

2. A garment as claimed in claim 1 wherein the resiliently stretchable material is resiliently stretchable in the horizontal and in the vertical directions in use.

3. A garment as claimed in claim 1 or 2 wherein the air permeable material in the back of the upper body portion has an air permeability of from 0.5cc/cm2/sec to 5.0cc/cm2/sec.

4. A garment as claimed in claim 3 wherein the said air permeable material is capable of giving at least 90% filtration of 0.5 micron particles and at least 85% filtration of 0.3 micron particles.

5. A garment as claimed in claim 4 wherein the said air permeable material is capable of giving at least 95% filtration of 0.5 micron particles and at least 90% filtration of 0.3 micron particles.

6. A garment as claimed in claim 2 wherein the degree of stretch provided by the resiliently stretchable material is up to 30% in each of the horizontal and vertical directions.

7. A garment as claimed in any preceding claim wherein the upper body portion and the lower body portion are composed of materials containing spaced electroconductive strands.

8. A garment as claimed in claim 7 wherein the material of which the lower body portion is composed contains a higher density of electroconductive material than the material of which the upper body portion is composed.

9. An upper body portion for an integral garment as claimed in any preceding claim.

10. A garment substantially as described herein with reference to and as illustrated by Figure 1 or Figure 2.

11. A garment as claimed in claim 1 and substantially as described herein.