WO1992022354A1

WO1992022354A1 - Composite for protective garment

Info

Publication number: WO1992022354A1
Application number: PCT/FI1992/000182
Authority: WO
Inventors: Risto JÄRNSTRÖM
Original assignee: Finex Oy
Priority date: 1991-06-10
Filing date: 1992-06-10
Publication date: 1992-12-23
Also published as: FI912788A0; AU1889792A

Abstract

The invention relates to a composite for protective garment, comprising an inner layer (1), an outer layer (3) spaced apart from said inner layer, and at least one intermediate layer (2, 4, 5). According to the invention, the composite contains in particular two intermediate layers (2, 4), both of which are comprised of a fibrous ion exchange material, the layer (2) adjacent to the outer layer containing ion exchange groups in acid form and the layer (4) adjacent to the inner layer containing ion exchange groups in base form. The composite according to the invention may be used for the manufacturing of suits protecting against CW gases and toxic industrial chemicals.

Description

Composite for protective garment

The present invention relates to a composite for protective garment in accordance with the preamble of claim 1.

A composite of this kind generally comprises an outer layer, an inner layer spaced apart from said outer layer, and a layer fitted between said outer and inner layers, capable of interacting with toxic chemicals.

A composite according to the invention is used in particular in protective garments which are intended for protecting the wearer against toxic and poisonous chemicals. These chemical may comprise conventional industrial chemicals, such as SO,, N0₂, HCHO and HCOOH and H₂S. The poisonous chemicals may also comprise skin-penetrating chemicals which have been develope for chemical warfare, such as different mustard gases, which normally consist of organic compounds containing sulphur and chlorine, or nerve gases which may contain, for instance, organic phosphate groups.

The composite according to the invention has also been developed to protect against neutron radiation.

It is known in the art to manufacture hermetic protective suits from rubber and plastic materials. This products are impermeable to air and therefore not suitable for prolonged used (> 1 h) because of the thermal load placed on the wearer. This is one of the reasons why several products with improved breathability have been developed, which are based on the adsorption of the poisonous gas or liquid drops. The adsorbing composite normally comprises

a) an outer layer which contains water and oil repellant chemicals and fire retardants, b) an adsorbing layer, which usually comprises activated carbon either in finely divided form or in granular or fibrous form, and c) an inner layer to which the afore-mentioned adsorptive layer has been attached by lamination or in another suitable manner.

Products of the above kind are exemplified by the composite disclosed in the International Patent Application No. WO 88/10134.

There are, however, several drawbacks related also to this technique. Thus, generally the outer layer has to be made so thick that it will prevent the poisonous drops from directly penetrating the adsorbing layer, whose protective capacity otherwise would easily be exceeded. This makes the protectiv garment heavy and increases the thermal load on the wearer. The capacity of the adsorption layer is limited, and simple adsorption is an ineffective way of protection against highl toxic compounds which upon skin contact may cause death or a permanent lesion even in amounts as small as tens of milligrams. Furthermore, the contaminated protective suits are potentially dangerous. It should also^*be pointed out that the inner layer to which the adsorbing layer is attached may allow penetration of slag substances of the sweat, such as amino acids and salts, which rapidly will decrease the capacity of the adsorbing layer.

Most of these adsorbing, "breathing" suits are furthermore ineffective against neutron radiation.

It is particularly difficult to achieve protection against poisonous compounds contained as aerosols in air. As described above, according to the prior art the outer layer has to made impermeable which will unacceptably much increase the thermal load put on the wearer by the protective suit.

It is an object of the present invention to eliminate the drawbacks of the prior art and to provide an entirely new composite product which can be used particularly in protective suits.

The invention is based on the basic concept that if a compound is poisonous then it must also be reactive. And it should be possible to decompose a reactive compound. The mo effective way of providing protection against poisonous compounds is to decompose them before the reach contact wit the skin.

Several of the poison gases developed for chemical warfare (in the following abbreviated CW gases) are esters or compounds such as the mustard gas which will decompose unde acidic conditions. Of this reason, basic and acid substance are capable of catalyzing their decomposition. Thus, to mention an example, calcium hypochlorite and alkoholates ar used for decomposing CW gases. An ion exchanger in free aci or base form is therefore capable of decomposing phosphonic acid esters and mustard gas upon contact.

We have found out that a conventional granular ion exchange is not suitable for use in a composite. This is because the granulated material reacts even in very finely divided form too slowly to provide the required protective effect. Secondly, it is extremely difficult to incorporate the granulate into a protective garment.

The invention is therefore based on the concept of providing a multilayer composite comprising at least one layer which consists of a reactive textile material. That reactive layer is, according to the invention, comprised of a fibrous ion exchanger in the form of a textile fabric, the functional io exchange groups being essentially located on the surface of the fibres. Surprisingly is has been discovered that the location of the functional groups on the surface will improv reactivity by a factor of 10³ to 10⁴.

In particular, the product according to the invention is mainly characterized by what is stated in the characterizin part of claim 1.

The composite in accordance with the invention comprises at least one layer consisting of ion exchange fibres. The laye is preferably in the form of a cloth or a fabric and the io exchange groups are preferably cation exchange groups which are capable of reacting with poisonous substances by decomposing them. According to a particularly preferred embodiment of the invention the composite comprises also a second ion exchange layer consisting of an anion exchange cloth or fabric which functions as an adsorptive layer. Preferably, the anion exchange layer is placed adjacent to the layer which comes against the skin.

In a protective garment laminate according to the invention, there are ion exchange groups and/or redox (reduction/ oxidation) groups. These groups are bifunctional: they will partially adsorb acid and/or alkaline compounds and

- they will achieve the pH range which will provide the fastest reaction rate of the redox reaction.

The following reaction equations exemplify the function of the fibrous ion exchangers:

CH₃CH₂OPO(CN) {N(CH₃)₂} + n e- —> decomposition products (I

(tabun)

0 / (CH₃)₄-(CH)₂-N-(CH₂)₂-S-P-CH₃ + H₂0 >

0-CH,-CH, OH"

(VX)

(CH₃)₄-(CH)₂-N-(CH₂)₂ ,-S + HO-P- CH, \ (ID 0-CH,-CH₃

S-(CH₂CH₂)_:-C1₂ + 2 H,0 > SO, + 2 HC1 (III) (mustard gas) H^"1

HCHO + 0₂ —> H₂0 + C0₂ (IV) (formaldehyde)

In most cases, for instance in connection with the de¬ composition of tabun, the generated compounds are considerably less poisonous than the starting compound. As far as VX is concerned

0 I H0-P-CH₃ is adsorbed to the anionic ion exchanger

0-CH₂-CH₃

and (CH₃)₄-(CH)₂-N-(CH₂)₂-S is rather harmless compared to the original product. Mustard gas is catalytically decomposed i the composite, the formed compounds being "normal" poisons which are, according to the capacity of the material, adsorbed to the anion exchange material.

If necessary, boron compounds may be incorporated into the composite in order to provide protection against neutron ra diation.

The invention provides a product which may be used in garments which protect the wearer against poisonous chemicals and which will provide proper protection not only against industrial chemicals but also against nerve gases a neutron radiation.

In comparison to, e.g., the composite disclosed in the WO Published Patent Application No. WO 88/10134, the following specific advantages are achieved by means of the present invention: the ion exchange cloth of the composite will decompose the poisonous gases instead of merely adsorbing them. The fabric is mechanically more than ten times stronge than activated carbon cloth (in the following abbreviated ACC) . Thus, for the manufacture of protective garments, it not absolutely necessary to laminate the fabric to a separa supporting layer. This feature on one hand improves air permeability and on the other hand facilitates sewing of th composite. Inherently, the ion exchange fabric will also retain aerosols. Since the fabric does not shrink during th preparation process, the yield of the process is, for insta ce, five times larger than that of the manufacturing process of ACC. This advantageous feature will, in a comparison base on the price-to-quality ratio, make the present product more interesting than ACC.

The main differences are summarized in Table 1.

Table 1. Comparison of a protective garment containing activated carbon to a protective garment according to the invention

Activated carbon New composite

Function Adsorption Decomposing adsorptio

Capacity Good Limitless

Retention of No adsorption Adsorbs aerosols

No impact

Positive

Good

Strong

Good

Reasonable

It should further be pointed out that the ion exchange fabri may, if necessary, be modified by incorporating, e.g. , redox groups which will react reversibly with adsorbed organic or inorganic compounds. Thus, Cl₂ may be reduced to HC1.

Next, the invention will be examined in more detail with the aid of the attached drawing.

Figure 1 depicts the structure of a composite, i.e. laminate according to a first preferred embodiment of the invention. Figure 2 shows the structure of a composite according to a second preferred embodiment of the invention. Figure 3 indicates the structure of a composite according to a third preferred embodiment of the invention.

The flow direction of a poisonous gas is indicated by arrow in the figures, whereas arrow B indicates the path of perspiration.

A composite according to Figure 1 comprises an inner layer 1 (lining) coming against the wearer's skin, an outer layer 3 spaced apart from the inner layer and a first intermediate layer 2 fitted between the layers, capable of reacting with chemical substances which penetrate the outer layer. The intermediate layer consists of a cation exchange fabric whic has been converted to the acid form.

The composite according to Figure 2 comprises the same layer as the previous composite, but it further includes a second intermediate layer fitted between the inner layer 1 and the cation exchange cloth 2, comprising an anion exchange fabric 4 which has been converted to the base form (OH"form) .

The composite according to Figure 3 comprises the same layers as the product depicted in Figure 2 and in addition also an adsorbing layer 5 fitted between the ion exchange fabrics 2 and 4.

According to the invention the layers 2 and 4 preferably consist of an ion exchange fabric marketed under the trade name FIBAN and manufactured by the Belorussian Academy of Science and Technology in Minsk. Within the scope of the invention, the products used may be in the form of cloths, fabrics, non-woven materials, mats and needle punctured felts. They consist of fibres whose most important properties are the following: Basic material: Polypropylene coated with polystyrene with active groups attached to the polystyrene.

Table 2. Properties of the FIBAN fibres

FIBAN A-l FIBAN K-l

Active groups: -CH₂-N-(CH₃)₃-OH S-0₃-H

Fibre diameter, μ : 30 - 60 30 - 50

Ion exchange capacity, mekv/g: 2,5 - 4 3 - 4

Strength, kg s/mm²: 10 - 20 7 - 15

Elongation at break, % 15 - 40 10 - 20

Heat stability: < 70°C < 100°C

Washability: Good. Non-ionic detergents should be used for washing.

Chemical resistance: Good. Aggressive solvents, such a ketones and esters, may damage th material.

The FIBAN fibres are not poisonous nor are they allergenic.

As the table above will show, the fibres consist in particular either of a sulphonated (cation exchanger) or a quaternary ammonated (anion exchanger) acrylic. The cation exchanger decomposes the harmful substances and the anion exchanger works an adsorptive layer for the decomposed products. If desired, the adsorption capacity of the composite may be increased by the adsorptive layer 5 mentioned above, which comprises, for instance, a fibrous activated carbon cloth.

Depending on the intended use of the protective garment, additional ion exchange groups, either strongly acid or strongly basic groups, and redox resins, either reducing or oxidative or both, may be attached to the first intermediate layer 2 in a suitable manner, for instance by high frequency welding. ΪO

Furthermore, boron compounds may also be incorporated into the composite for adsorption of neutron radiation.

The cover layer 3 may comprise any suitable tough and light material based on natural fibres or synthetic fibres or mixtures thereof. The layer may be in the form of a fabric o knitwear depending on the use of the garment. For special applications, such as for military use, the material should meet certain criteria regarding flame retardation, water and oil repellency and it should be stained with colour protec¬ ting against IR.

The cover layer 3 may for instance comprise a modacrylic and nylon product with a twill structure having a breaking strength/cm in warp direction of about 465 N and in weft direction of 385 N. The air-permeability of this material is > 30 ml/s/cm²10 mm vp

The lining material 1 separates the fibrous ion exchange layers from the skin and it consists, by way of an example, of a thin knitted or woven cotton fabric.

In the following, some examples are given of the weights of per unit area of the materials used in the composite:

Outer layer 120 - 150 g/m² (e.g. Courtauld twill fabric) FIBAN K-l 120 - 150 g/m², fibre mat (non-woven) , fixed to the outer layer by bonding FIBAN A-l 120 - 150 g/m², may also be in the form of a non-woven material and it can be fixed to the lining by bonding Lining 80 g/m²8

The composites are manufacture by laminating the first intermediate layer 2, for instance by bonding, to the outer layer 3 at low temperature ( < 100 °C) . The lining 1 and the second intermediate layer 4 are also fixed to each other by bonding. The layered composites are then joined together in manner known per se, for instance by knitting.

The adsorbing material 5, which may be comprised of fibrous activated carbon, another kind of carbon or an adsorbing organic polymer or other material suitable to retaining molecules, can be attached to the inner layer 4 by bond lamination (i.e. by spreading laminating substance between the inner material and the adsorbing intermediate layer, while heating and pressing the layers together) .

The lamination may also be conducted by high frequency heating, which together with water added on the surface of the inner layer 4 will cause melting of said surface.

The ion exchange fabric adjacent to the inner layer effectively filters the slag substances of perspiration, thu preventing them from reaching and contaminating the intermediate layer.

The composite according to the invention can be employed for manufacturing protective suits which protect against CW gase and it can also be used for making protective suits and survival suits for fire departments and for persons working with dangerous chemicals (S0₂, H₂F₂, HN0₃, NH₃) . The consumption of the material is about 5 m² of both the ion exchange fabrics. The air-permeability is better than 40 cm³/cm²/s at a pressure of 10 mmvp and the permeability of steam is better than 3600 g/m²/24 h (100 % relative humidity, 37 °C) .

A contaminated composite which has been exposed to hazardous chemicals can be regenerated by separating the lining and th outer layer from each other and by regenerating the outer part with dilute acid and the lining part with dilute alkali

In the following the protective capacity of the composite according to the invention will be examined in more detail with the aid of examples relating to mustard gas and dichlorodiethyl sulphide.

Decomposition and adsorption of mustard gas

The decomposition of mustard gas is catalyzed by the acid groups of cation exchange layer 2 as described by equation (III) .

The reaction products, HCl and SO,, are adsorbed by the anion exchanger:

SO, + 2 HCl + 4 CH,-N-(CH₃)₃-OH 2 + ACH₂-N-(CH₃)₃-C1 + CH,-N-(CH₃)3A₂ + 2 H₂0

The capacity of the cation exchanger fibres is theoretically independent of the amount of mustard agent on the surface of the composite.

The theoretical adsorptive capacity of the anion exchange material may be calculated as follows:

According to equation (III) 1 mekv (159 mg) dichlorodiethyl sulphide generates 2 mekv HCl and 1 mekv S0₂. The equivalent weight of mustard is thus 159 : 4 = about 40. If the capacity of the anion exchanger is 2.5 to 4 mekv/g, it will adsorb 100 to 160 mg of decomposition compounds per gram. The area of one gram calculated from a weight by unit area of 200 g/m² of the material is 50 cm² = 7 x 7 cm. The area needed to decompose one drop containing 2 microliter of mustard (falling drop test) is about 0.1 cm² = 0.3 x 0.3 cm.

Since all of the mustard gas in any case is decomposed in the composite and since SO, and HCl in small amounts do not form any immediate danger for skin poisoning, the protective capacity of the composite is in practice larger than 40 g. As regards the nerve gas VX, the capacity of the anion ex¬ changer for the monobasic acid

0

I

H0-P-CH₃

0-CH,-CH,

is about 200 to 500 mg/g fabric, i.e. about five times larg than in the case of mustard gas.

Example l

Permeation of mustard gas of composite

A round piece of the composite shown in Figure 4 was cut an placed between two metal ring holders. A drop of indicator solution (methyl red) was put on a glass shelf and the test specimen in its holder was placed above the drop of the indicator. 50 μl of mustard gas was then applied to the test specimen. A change of colour of the indicator indicated the permeation of the mustard gas, the breakthrough time being 3.5 h.

A check of the test specimen after the experiment revealed that the Fiban A-l used in the experiment had been incompletely regenerated with NaOH, which caused HCl release during the ion exchange reaction and an untimely change of colour of the indicator. Even so, the test showed the good protecting properties of the composite.

Example 2

Permeation by dichlorodiethyl sulphide of the composite

1. Starting materials

The composition of the test composite was as follows:

Olive Drab (NATO Stock No. 8305-99-132-3430) Ϊ4

Fiban K-l H⁺ form (activated)

Fiban A-l OH^" form -"-

The test was conducted in the following manner:

The layers were pressed upon each other in a round brass holder. The holder was placed on a glass sheet. Under the holder, a drop of methyl red was placed to indicate the permeation of dichlorodiethyl sulphide by forming a hydro chloric acid with said compound which colours the indicator red. The diameter of the holder was 3 cm.

The results showed that the methyl red changed colour after 3.5 to 4 hours. In a reference test comprising the used of a inert material, the time of permeation was about 10 minutes.

Claims

Claims:

1. A composite for protective garment, comprising an inner layer (1), an outer layer (3) spaced apart from said inner layer, and at least one intermediate layer (2, 4, 5), c h a r a c t e r i z e d in that the intermediate layer is at least partially comprised of a fibrous ion exchange material.

2. The composite according to claim 1, c h a r a c t e r ¬ i z e d in that it contains two intermediate layers (2, 4), both of which are comprised of a fibrous ion exchange mate¬ rial, the layer (2) adjacent to the outer layer containing ion exchange groups in acid form and the layer (4) adjacent to the inner layer containing ion exchange groups in base form.

3. The composite according to claim 1, c h a r a c t e r ¬ i z e d in that it contains three intermediate layers (2, 4, 5) , whereat the layers adjacent to the inner and the outer layers (2, 4) are comprised of fibrous ion exchange materials and the layer between them is comprised of fibrous activated carbon.

4. The composite according to one of claims 1 to 3, c h a r a c t e r i z e d in that it contains strongly acid and/or strongly alkaline groups and/or redox groups.

5. The composite according to any one of the previous claims, c h a r a c t e r i z e d in that the ion exchange groups and the redox groups have been fixed to the intermediate layer (2, 4) by high frequency welding.

6. The composite according to any one of the previous claims, c h a r a c t e r i z e d in that it contains boron compounds for adsorbing neutron radiation.

7. A garment protecting in particular against chemical substances, c h a r a c t e r i z e d in that it is manufactured from a composite according to one of claims 1 to 6.