GB2057296A - Protective materials and clothing - Google Patents

Abstract

A fire-retardant, gas-absorbing material includes a substrate, generally of fabric, charcoal and a cured acrylate bonding agent, antimony oxide and a halogenated solid particulate fire retardant material. The bonding agent, antimony oxide and particulate fire retardant material are best introduced as an aqueous dispersion.

Description

SPECIFICATION Protective materials and clothing It is well known to make air-permeable material suitable for making up into protective garments which will provide protection against toxic vapours and other chemicals.

Such material broadly comprises an air-permeable substance such as a nonwoven, felt or polyurethane foam, which may be laminated to a second layer for development of specific protective properties, or to a woven or knitted fabric for reinforcement.

Such protective materials contain activated charcoal and desirably liquid-repellent and flame-retardant agents. Materials of this type are described for instance in British Patent Specifications Nos. 1,127,581, 1,173,142, 1,173,143, 1,206,581, 1,222,502 and 1,245,965.

The activated charcoal may be contained within or on the air-permeable substrate by bonding with an acrylate bonding agent, or be trapped in particulate form between laminated layers, as described in 1,245,965.

Nonwoven fabrics are conveniently bonded and rendered flame-retardant by bonding of the fibrous web with flame-retardant bonding system, whilst felts and foams may also be rendered flame-retardant by treatment with similar formulations.

The main bonding agent proposed in the above Patent Specifications for bonding the fabric is polychloroprene, although in Patent Specification No. 1,127,581 it was suggested that binders of acrylate and including chlorinated polymers and antimony oxide could also be used. However, thus-modified acrylate formulations resulted in fabrics that were too hard and the inclusion of plasticizers was unsatisfactory and there has instead been large-scale use of polychloroprene. Also other bonding agents, for instance acrylates, have been proposed and used for bonding the charcoal into the material.

The resultant products have been manufactured on a wide scale, but it has been observed that they have variable and unsatisfactory ageing characteristics in respect of retention of gas or vapour absorption properties on storage. Thus if a large number of samples are tested it will be found that the average decrease in absorption properties is greater than is desirable and that the decrease varies widely from one sample to another. This latter feature is particularly undesirable and in an attempt at maintaining absorption properties additional charcoal was often included and this in turn resulted in the material being stiffer than was desirable.

A flame-retardent vapour-absorbing material according to the invention comprises activated charcoal bonded to a substrate and the material includes antimony oxide, a fire-retardant particulate halogenated organic compound that is solid at ambient temperature and a cured acrylate bonding agent.

The described bonding system can be used in place of the chloroprenetraditionally used to give products having a good handle (such that they are suitable for clothing) and good flame retardence, vapour absorption and air permeability and the products are thus preferably substantially free of chloroprene. In particular we have found that the decrease in the average absorption properties of such materials on ageing is much les than when polychloroprene is used and, especially, the decrease is more uniform.

The acrylate, antimony oxide and organic fire retardent are best introduced as an aqueous dispersion followed by curing. The methods of preparing and applying and curing the binder are thus much simpler than those associated with polychloroprene.

The dispersion is usually applied to the substrate by impregnation. The substrate may be of foam but preferably comprises a fabric substrate. Preferably the substrate comprises a bonded nonwoven fabric made by impregnating a nonwoven web with the dispersion and curing it. The nonwoven fabric may be bonded to a scrim.

Any acrylic bonding agent suitable for use in fabrics and capable of giving a soft handle can be used, such as the acrylics traditionally used for bonding nonwoven fabrics. It may be self-curing.

The organic fire retardent compound should be water-insoluble, stable at high temperatures (e.g. above 350or), highly halogenated and high melting (e.g. above 200"C). It may be a brominated aromatic fire retardent compound, preferably a brominated diphenyl oxide. Decabromodiphenyl oxide is very satisfactory. Suitable fire retardent systems than can be used with the acrylic bonding agent are described in U.S.

Patent Specifications Nos. 3,877,974, 3,955,032 and 3,974,310, the preferred system being an aqueous dispersion of a mixture of decabromodiphenyl oxide and antimony oxide, as sold under the trade name Caliban FRP44 by White Chemical Corporation of Bayonne, New Jersey.

In the dispersion preferably the amount of the halogenated organic compound is 5 to 20%, the amount of antimony oxide is 2 to 10% and the amount of the acrylate bonding agent is 25to 50%, all calculated as dry weight based on the weight of fibres in the fabric substrate. The amount of halogenated compound may be 20 to 50%, and the amount of antimony oxide may be 10 to 30%, both based on the dry weight of the acrylate.

Conventional additives, such as wetting agents, softeners, lubricants, pigments and catalysts, may be included in the dispersion. The dispersion generally has a solids content of 20 to 30%, generally about 25% by weight.

The activated charcoal is generally applied after the acrylate, antimony oxide and organic fire retardent and may be bonded in conventional manner, e.g. using an acrylate bonding agent. It may be applied to one side only of the substrate. Fluorocarbon or other water repellant may be applied.

A preferred material according to the invention is made by preparing a nonwoven web in traditional manner, laying it against a reinforcing scrim, impregnating the composite with the described binder dispersion, drying and curing and washing the product, applying fluorocarbon water repeliant from one side (often the side of the nonwoven) or by saturation, curing the product and then spraying activated charcoal in an acrylic binder onto the other side and curing the final material.

The resultant material can be used as protective clothing in known manner.

The following are some examples, Example 3 being comparative. Primal, Permafresh, Caliban, Silastan, Acronal, Artilene, Celacol, Breon, Neoprene, Warcodet, Timonox, Permanex and Atolex are trade marks.

Example 7 A mixture of 85% Nylon and 15% Viscose fibres was carded and crosslayered to provide a web of 74 g/m2.

The web was laid on to a 26 g/m2 cotton scrim and lightly needled to attach the web to the scrim. This composite was then impregnated with binder dispersion and dried at 1 50"C, a temperature suitable to simultaneously cure the binder. The weight of binder added was 53 g/m2 dry weight.

The binder dispersion consisted of Solid Liquid Acrylate (Primal HA8) 95.0 206.0 Ethylene-urea resin (Permafresh 5.0 10.0 Resin E) Caliban FRP 44 55.0 82.5 Wetting agent (Silastan L) 4.0 4.0 Acid catalyst 1.0 3.0 Pigment dispersion (Artilene 5.4 13.6 Olive Green DFJ) Water 314.9 165.4 634.0 The bonded nonwoven was washed to remove surfactant and dried. The material was then impregnated with a fluorocarbon composition to impart oil- and water-repellent properties. Impregnation was such as to give a dry increase in weight of approximately 0.65%. The impregnated material was dried and cured for 5 minutes at 160 C.

The repellent nonwoven fabrics then had charcoal applied to the scrim side by spraying at such a rate as to give a dry weight increase of 40 g/m2. The charcoal composition was formed of Solid Liquid Nutshell Charcoal 110.0 200.0 Methylcellulose (Celacol 100) 0.73 29.0 Acrylate (Primal B15) 55.0 120.9 Water 570.6 165.73 920.5 Example 2 Example 1 was repeated, but the binder recipe was modified by the reduction of the Caliban FRP44 content from 55 parts solid to 40 parts solid.

Example 3 Example 1 was repeated but instead of using the described dispersion the binder system was based on polychloroprene essentially as described in BP 1,127,581.

Solid Liquid Butadiene-Acrylonitrile (Breon 9370) 5.00 10.00 Polychloroprene (Neoprene 842A) 95.00 190.00 Ball Mill Dispersion 45.80 100.00 Wetting agent (Warcodet K 54) 3.50 8.75 Pigment (Artilene Olive DFJ) 5.44 13.60 Water 64.50 154.74 386.85 The ball mill dispersion was: Zinc dibutyldithiocarbamate 1.5 1.5 Sulphur Dispersion 1.0 2.0 Zinc Oxide 20.0 20.0 Antimony Oxide (Timonox) Water paste 18.5 25.0 Antioxidant (Permanax WSP) 4.0 4.0 Dispersing Agent (Atolex DA/25) 0.8 3.2 Water 44.3 45.8 100.0 The bonded and dried material was vulcanised for 2 hours at 120"C, washed to remove surfactants, dried and rendered liquid-repellent and charcoal treated on the scrim side as described in Example 1.

Other acrylates that have been used in place of Primal HA8 include Primal J161, Primal E821 and Acronal 35D.

The products made in Examples 1,2 and 3 were tested. In the test methods: Weight (glm2) in accordance with BS 2471 Permeability BS 3424 Method 18. Volume of air in ccs/cm2/sec at a pressure drop across the fabric of 10 mm water gauge.

Bending Length (cms) BS 3356.

MD - Machine Direction XMD - Cross Machine Direction Absorption (mins) Record as the time taken for Mustard Gas to penetrate upwards through two layers of the fabric placed with charcoal faces together at a temperature of 20"C.

Flammability BS 2963 Method A.

The results were Example 1 2 3 Weight 196 196 190 Permeability 74 90 60 Bonding Length (cms) MD 7.0 6.6 6.6 XMD 6.0 5.8 5.6 Absorption (mins) 102 106 116 Flammability Not Self- Self propagated extinguishing extinguishing Absorption loss 14% after 6% after 49% after onageing 11 months 8months 12 months These results show that the new materials have improved permeability, the same or better flame retardance and improved storage properties. Also the materials have good handle and the methods involved in making the new materials are simpler to conduct.

Claims (13)

1. A flame-retardent, vapour absorbing, air-permeable material comprising activated carbon bonded to a substrate and in which the material includes antimony oxide, a fire-retardant particulate halogenated organic compound that is solid at ambient temperature and a cured acrylate bonding agent.

2. A material according to claim 1 in which the acrylate bonding agent, the organic compound and the antimony oxide have been introduced as an aqueous dispersion impregnated into the substrate, followed by curing of the bonding agent.

3. A material according to claim 2 in which the substrate comprises a nonwoven fabric formed by impregnating a nonwoven web with the dispersion and curing the bonding agent.

4. A material according to claim 2 or claim 3 in which the activated carbon has been applied after application of the dispersion.

5. A material according to claim 4 in which the activated carbon has been bonded to the substrate by an acrylate bonding agent.

6. A material acording to any preceding claim in which the organic compound is a brominated aromatic fire-retardant compound.

7. A material according to claim 6 in which the compound is a brominated diphenyl oxide.

8. A material according to claim 7 in which the compound is decabromodiphenyl oxide.

9. A material according to claim 3 in which the amount of the halogenated organic compound is 5 to 20% the amount of antimony oxide is 2 to 10% and the amount of the acrylate bonding agent is 25 to 50%, all calculated as dry weight based on the weight of fibres in the substrate.

10. A material according to claim 3 in which the substrate also comprises a scrim impregnated with the dispersion.

11. A material according to any preceding claim in which the activated carbon is present only on one side of the substrate.

12. A material according to claim 1 substantially as herein described.

13. Clothing formed from a material according to any preceding claim.