Flame retardant materials

Abstract

The present invention relates to an article of personal protective equipment comprising a rubber composition, said rubber composition comprising: a rubber matrix material comprising or consisting of a butyl rubber; and a flame retardant dispersed in the rubber matrix material.

Description

[0001] Mewburn Ref: 8863490

[0002] 1

[0003] FLAME RETARDANT MATERIALS

[0004] This application claims priority from GB2416783.5 filed 14 November 2024, the contents and elements of which are herein incorporated by reference for all purposes.

[0005] FIELD OF THE INVENTION

[0006] The present invention relates to flame retardant rubber compositions for use in personal protective equipment.

[0007] BACKGROUND OF THE INVENTION

[0008] Personal protective equipment refers to protective clothing or equipment which is designed to protect the user from injury, such as gloves, goggles, masks, suits, and boots, as well as equipment such as filters and breathing apparatus. These types of equipment may be used to minimise or prevent exposure to hazards, for example biological hazards, chemical hazards, electrical hazards, mechanical hazards and radiological hazards. Personal protective equipment designed to protect the user against chemical, biological, radiological and nuclear hazards is referred to as CBRN protective equipment.

[0009] As well as functioning as a barrier to hazardous substances, personal protective equipment also needs to allow good mobility and be comfortable for the user / wearer to wear for extended periods of time. Therefore, to be suitable for its desired purpose personal protective equipment needs to have good flexibility, good physical properties (such as puncture, tear and abrasion resistance), be lightweight and also lead to low skin irritation. In particular, it is desirable that personal protective equipment demonstrates good flexibility and physical properties at both low and high temperatures.

[0010] Butyl and halobutyl rubbers (generically referred to here as “butyl rubbers”) are particularly suited to use in personal protective equipment. These materials are known fortheir low permeability to liquids and gases and for their flexibility (in particular low temperature flexibility). Butyl rubbers are also able to exclude biological hazards (such as viruses and biological weapons), chemical hazards (such as mustard gas and chemical droplets) and radioactive materials. Therefore, these materials are widely used in industrial and military applications, where low permeability is paramount to give protection against toxic substances. Butyl rubber materials also demonstrate good ozone resistance, which is important for the durability of these materials meaning that they can withstand exposure to ozone naturally present in the atmosphere before breaking down. Other polymer materials such as epichlorohydrin rubber (CO / ECO) and nitrile rubbers may exhibit permeability performance approaching that of butyl rubber in some scenarios; however, the grades necessary generally do not exhibit as good low temperature flexibility.

[0011] However, butyl rubbers are highly flammable, due to these materials tending to degrade on application of a flame, leading to the evolution of low molecular weight components which act as fuel to the fire. This can lead to rapid acceleration of flame growth. Therefore, conventional Mewburn Ref: 8863490

[0012] 2

[0013] articles made from butyl rubber display poor flame resistance and are not suitable for working in environments where flames may be present. As a result, these materials are generally avoided in applications requiring flame resistance as they are not able to maintain the key CBRN performance characteristics in environments where flames are present. This is particularly relevant for industrial and military applications where flames are often present, for example in steel production.

[0014] It is challenging to develop butyl rubber formulations which have good flame resistance whilst maintaining their desirable flexibility and other physical properties (such as puncture, tear and abrasion resistance), as well as low skin irritation. Butyl rubber compositions comprising a flame retardant are known from US 3,847,723. However, US 3,847,723 does not provide any indication that such compositions are suitable for use in an article of personal protective equipment.

[0015] Therefore, there remains a need in the art to develop butyl rubber based personal protective equipment, which has improved flame resistance, whilst also maintaining desirable physical properties such as flexibility, puncture, as well as resistance to permeation, tear and abrasion; whilst also being light weight and avoiding skin irritation.

[0016] SUMMARY OF THE INVENTION

[0017] The present inventors have developed an article of personal protective equipment which helps to address the practical problems outlined above.

[0018] Broadly, the present inventors have discovered that dispersing a flame retardant in a rubber matrix material comprising or consisting of a butyl rubber can be used to enhance the flame resistance of the rubber matrix material, whilst also maintaining the desirable properties of this material. This flame-resistant butyl rubber can then be used in an article of personal protective equipment.

[0019] Accordingly, in a first aspect the present invention provides an article of personal protective equipment comprising a rubber composition, said rubber composition comprising:

[0020] - a rubber matrix material comprising or consisting of a butyl rubber; and - a flame retardant dispersed in the rubber matrix material.

[0021] In some embodiments, the flame retardant comprises or consists of one or more of aluminium hydroxide, diantimony trioxide and a halogenated flame retardant.

[0022] In a second aspect, the present invention provides a method of manufacturing an article of personal protective equipment, comprising:

[0023] (a) providing a rubber composition; Mewburn Ref: 8863490

[0024] 3

[0025] (b) producing the desired form of the article via injection moulding, injection transfer moulding, compression moulding, compression transfer moulding, extrusion, rubber solution spreading / dipping or calendering process.

[0026] The article of personal protective equipment according to the present invention has a number of advantageous features.

[0027] Firstly, the personal protective equipment according to the present invention demonstrates excellent flame resistance. The flame resistance of the personal protective equipment according to the present invention is significantly improved compared to an article of personal protective equipment made from butyl rubber without the flame retardant dispersed within the rubber matrix. In particular, the flame retardance of the personal protective equipment may be high enough to be in compliance with legal and industry standards for CBRN personal protective equipment, such as the ASTM F1358 standard.

[0028] Secondly, the personal protective equipment demonstrates good physical properties, such as Shore hardness, tensile strength and breakthrough time. In particular, the personal protective equipment demonstrates good CBRN performance and especially permeation breakthrough times to chemical warfare agents. This demonstrates that the addition of flame retardants does not compromise the desirable properties of the butyl rubber material. The butyl rubber material, therefore, has properties which are acceptable for the end user, and which are suitable for industrial or military settings.

[0029] Thirdly, the personal protective equipment demonstrates good cut / puncture resistance and abrasion resistance. These properties are crucial for military settings or industrial settings which deal with sharp objects (e.g. in a sawmill). Being able to combine these properties with effective flame resistance which meets industry standards is desirable for these applications.

[0030] Fourthly, the personal protective equipment demonstrates good flexibility (even at low temperatures), which is comparable with conventional butyl rubber. This means that the personal protective equipment is suitable for use in low temperature applications, such as in military settings. It is of key importance for the end user in industrial or military settings to be able to move easily and to not be impeded in their normal degree of movement by their personal protective equipment.

[0031] Fifthly, the rubber composition used in the manufacture of the personal protective equipment demonstrates excellent injection moulding processability. This means that the personal protective equipment can be produced using conventional equipment which is presently used for the manufacture of butyl rubber compositions avoiding the need for modifying the production methods for the personal protective equipment. Manufacture of the rubber composition can also be carried out using standard industrial mixing equipment Mewburn Ref: 8863490

[0032] 4

[0033] meaning that the rubber composition used in the manufacture of the personal protective equipment is easy to manufacture.

[0034] In some embodiments, the article of personal protective equipment comprises a conductive filler. The presence of the conductive filler helps to allow for electrical conductivity of the personal protective equipment. It may be important for personal protective equipment to be conductive as this may allow the use of touchscreens with this equipment. Preferably the article of personal protective equipment has a resistance of less than 5 x 1O10Ohms, preferably less than 5 x 106Ohms. The ability for personal protective equipment to be used with touchscreens may be important, for example when the article of personal protective equipment is a glove.

[0035] Also provided herein is a rubber composition comprising:

[0036] a rubber matrix material comprising or consisting of a butyl rubber; and

[0037] a flame retardant dispersed in the rubber matrix material, wherein the flame retardant comprises or consists of aluminium hydroxide.

[0038] In a further aspect, the present invention relates to a method of manufacturing a rubber composition as described above, comprising dispersing the flame retardant in the rubber matrix material.

[0039] These proposals also encompass the use of aluminium hydroxide and / or diantimony trioxide and / or a halogenated flame retardant to provide an article of personal protective equipment with flame retardant properties.

[0040] DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS

[0041] The present invention will now be described in detail with reference to preferred embodiments and other optional features.

[0042] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although, any methods and materials similar or equivalent to those described herein can be used in practice fortesting of the present invention, the preferred materials and methods are described herein. In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below. Unless clearly indicated otherwise, use of the terms "a," "an," and the like refers to one or more.

[0043] While the invention is described in conjunction with the exemplary embodiments described below, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments set forth herein are considered to be illustrative and not limiting. Various changes may be made without departing Mewburn Ref: 8863490

[0044] 5

[0045] from the scope of the invention which is defined by the claims. All references referred to herein are hereby incorporated by reference.

[0046] Each and every compatible combination of the embodiments described herein is explicitly disclosed herein, as if each and every combination was individually and explicitly recited.

[0047] Additionally, where used herein, “and / or” is to be taken as a specific disclosure of each of the two specified features with or without the other.

[0048] Unless context dictated otherwise, the descriptions and definitions of the features set out herein are not limited to any particular aspect or embodiment and apply equally to all aspects and embodiments which are described where appropriate.

[0049] Where values are described as “at most” or “at least” it is understood that any of these values can be independently combined to produce a range.

[0050] Unless indicated otherwise, values provided are generally recorded at room temperature, that is, within the range 20-30°C for example 20°C.

[0051] Where non-SI units are provided, it will be understood that these can be converted easily into SI units by the skilled person.

[0052] The use of headings herein is intended to be to assist the understanding of the invention by the reader and does not imply any limitation on the invention as defined in the claims.

[0053] Rubber matrix material

[0054] The article of personal protective equipment according to the present invention comprises a rubber matrix material comprising or consisting of a butyl rubber.

[0055] Within the meaning of this invention, the term rubber includes any type of natural or synthetic rubber, such as natural rubbers, butyl rubbers and butadiene rubbers.

[0056] Within the meaning of this invention, butyl rubbers include synthetic rubbers such as nonhalogenated butyl rubbers, halobutyl rubbers (e.g. chlorobutyl rubber and bromobutyl rubber) and brominated isobutylene paramethyl-styrene terpolymers (BIMSM). These materials generally show reduced permeability compared to natural rubbers and also demonstrate good flexibility across a wide temperature range and good ozone resistance.

[0057] Preferably, the rubber matrix material comprises from 20 to 50 wt.% of the total weight of the rubber composition present in the article of personal protective equipment, more preferably from 30 to 50 wt.%, most preferably from 30 to 40 wt.% of the total weight of the rubber composition present in the article of personal protective equipment. Mewburn Ref: 8863490

[0058] 6

[0059] Without being bound by any theory, it is important to balance the polymer content with the other components of the rubber composition. It is important to have enough of the polymer material to achieve the desirable physical properties and to avoid a “chewing gum” like state, where over extension of the polymer has occurred. However, too much polymer can lead to a reduction in the flame-resistant properties of the article of personal protective equipment.

[0060] Preferably, the rubber matrix material comprises at least 30 wt.%, preferably at least 40 wt.%, more preferably at least 50 wt.%, more preferably at least 60 wt.%, more preferably at least 70 wt.%, more preferably at least 80 wt.%, more preferably at least 90 wt.% of butyl rubber based on the total weight of the rubber matrix material. Optionally, the rubber matrix material may consist essentially or entirely of butyl rubber.

[0061] The butyl rubber may comprise or consist of non-halogenated butyl rubber, chlorobutyl rubber, bromobutyl rubber and / or halogenated isobutylene paramethyl-styrene terpolymers and mixtures thereof. In this context non-halogenated butyl rubber refers to a copolymer of isobutylene with isoprene.

[0062] Non-halogenated butyl rubber, Chorobutyl rubber and Bromobutyl rubber are commercially available from various commercial suppliers such as ExxonMobil (Exxon butyl, Exxon chlorobutyl and Exxon bromobutyl), ARLANXEO (X_Butyl® rubber). Halogenated isobutylene paramethyl-styrene terpolymers are obtainable from ExxonMobil as Exxpro. Preferably, the butyl rubber comprises or consists of bromobutyl rubber and / or chlorobutyl rubber. Preferably, the butyl rubber comprises or consists of bromobutyl rubber. Preferably, the butyl rubber comprises or consists of chlorobutyl rubber. Preferably the butyl rubber comprises or consists of bromobutyl rubber and chlorobutyl rubber. Alternatively, the butyl rubber may comprises or consist of non-halogenated butyl rubber.

[0063] The rubber matrix material may also comprise one or more non-butyl rubbers. The content of non-butyl rubbers may be from 1 to 30 wt.% based on the total weight of the rubber matrix material, more preferably from 1 to 20 wt.% based on the total weight of the rubber matrix material, most preferably from 1 to 10 wt.% based on the total weight of the rubber matrix material.

[0064] Suitable non-butyl rubbers include polychloroprene, natural rubber, styrene-butadiene rubbers, polyisoprene, nitrile rubber, ethylene propylene diene monomer (EPDM) rubber, polyisobutylene rubber, and silicone rubber.

[0065] Optionally, the butyl rubber comprises the synthetic rubber polychloroprene. Preferably the butyl rubber comprises from 1 to 40 phr polychloroprene, more preferably from 1 to 30 phr polychloroprene, most preferably from 1 to 20 phr polychloroprene. Without being bound by any theory, generally the polychloroprene is compounded in a way such that it is able to cross link Mewburn Ref: 8863490

[0066] 7

[0067] during curing processes, meaning that some level of co-curing with the halobutyl rubber is possible.

[0068] Without being bound by any theory, it is believed that polychloroprene may also act as a flame retardant when incorporated into the rubber matrix, this is because the polychloroprene can liberate chlorine (generally polychloroprene contains about 40% by mass chlorine) at the decomposition temperatures of butyl rubber. The chlorine may then interfere with the main exothermic reaction of the combustion process reducing the free radical concentration present in the flame. This can lead to a reduction of the major heat release step involved in the conversion of carbon monoxide to carbon dioxide and hence ultimately reduce the levels of the flames present on the article of personal protective equipment.

[0069] The rubber used in the article of personal protective equipment may be cured or vulcanised, in order to enhance its permeation resistance.

[0070] Flame retardant

[0071] The article of personal protective equipment according to the present invention comprises a flame retardant dispersed in the rubber matrix material.

[0072] Preferably, the article of personal protective equipment comprises from 20 to 190 parts per hundred rubber (phr) flame retardant, more preferably from 40 to 180 phr flame retardant, more preferably from 50 to 170 phr flame retardant, more preferably from 60 to 150 phr flame retardant, most preferably from 100 to 130 phr flame retardant. In the context of this application parts per hundred rubber refers to the total amount of rubber (that is the rubber matrix material is present at 100 phr in the rubber composition). Preferably, the article of personal protective equipment comprises from 20 to 70 wt.% flame retardant, preferably from 25 to 60 wt.%, more preferably from 30 to 55 wt.%, most preferably from 40 to 50 wt.% based on the total weight of the rubber composition.

[0073] Optimising the content of flame retardant within the article of personal protective equipment is important, as it is necessary to impart the flame resistance to the material whilst also ensuring that the rubber material retains its physical properties such as flexibility. If too little flame retardant is used then the required flame retardance is not achieved and the article of personal protective equipment will not be compliant with legal or industry CRBN standards. Alternatively, if too much flame retardant is used then the physical properties of the rubber material will not be suitable for use in industrial and military applications.

[0074] Flame retardant materials are generally solid materials in particle form. These materials are dispersed within the rubber matrix material. The flame retardant materials are preferably uniformly dispersed throughout the rubber matrix material since agglomerates (clumps) of material may decrease the performance of the article of personal protective equipment and also lead to a lower overall flame resistance as regions of the material where the flame retardant is less concentrated will be more vulnerable to flames. Mewburn Ref: 8863490

[0075] 8

[0076] The type of flame retardant used is not particularly limited. For example, the flame retardant may be selected from the group consisting of one or more of aluminium hydroxide, magnesium hydroxide, diantimony trioxide, halogenated flame retardants, metal hydroxides, carbonate fillers and boron based flame retardants.

[0077] Optionally, the flame retardant comprises or consists of one or more of aluminium hydroxide, diantimony trioxide, magnesium hydroxide and a halogenated flame retardant. Optionally the flame retardant comprises or consists of two or more of aluminium hydroxide, diantimony trioxide, magnesium hydroxide and a halogenated flame retardant. Optionally, the flame retardant comprises or consists of magnesium hydroxide, diantimony trioxide and optionally a halogenated flame retardant. Optionally, the flame retardant comprises or consists of magnesium hydroxide, diantimony trioxide, optionally a halogenated flame retardant and optionally aluminium hydroxide.

[0078] Preferably, the flame retardant comprises or consists of one or more of aluminium hydroxide, diantimony trioxide and a halogenated flame retardant, optionally the flame retardant comprises or consists of two or more of aluminium hydroxide, diantimony trioxide and a halogenated flame retardant, optionally, the flame retardant comprises or consists of aluminium hydroxide, diantimony trioxide and optionally a halogenated flame retardant.

[0079] There are multiple mechanisms which allow various flame retardants to impart flame resistance to materials. For example, aluminium hydroxide (ATH, AI(OH)3) has a flame retardant effect because it has a high heat capacity and at temperatures above around 200 °C undergoes an endothermic dehydration effect; this also releases water which has an extinguishing effect on the claims. Diantimony trioxide (Sb2O3) works synergistically with halogenated flame retardants. Without being bound by any theory, it is believed that diantimony trioxide increases the concentration of halogen retained within the flame and thereby the flame retardancy potential. Without being bound by any theory, it is believed that magnesium hydroxide may have a similar mechanism for imparting flame resistance to ATH.

[0080] In one aspect, the flame retardant comprises or consists of magnesium hydroxide. In a certain such aspect, the flame retardant may comprise from 10 to 140 phr magnesium hydroxide, preferably from 50 to 140 phr magnesium hydroxide, more preferably from 60 to 140 phr magnesium hydroxide, more preferably from 60 to 130 phr magnesium hydroxide, more preferably from 70 to 130 phr magnesium hydroxide, more preferably from 90 to 130 phr magnesium hydroxide.

[0081] In one preferred aspect, the flame retardant comprises or consists of aluminium hydroxide.

[0082] In one preferred aspect, the flame retardant comprises or consists of aluminium hydroxide and diantimony trioxide. Mewburn Ref: 8863490

[0083] 9

[0084] In one preferred aspect, the flame retardant comprises or consists of aluminium hydroxide and a halogenated flame retardant.

[0085] In one preferred aspect, the flame retardant comprises or consists of diantimony trioxide and a halogenated flame retardant.

[0086] In one preferred aspect, the flame retardant comprises or consists of aluminium hydroxide, diantimony trioxide and a halogenated flame retardant.

[0087] The flame retardant may comprise from 10 to 140 phr aluminium hydroxide, preferably from 50 to 140 phr aluminium hydroxide, more preferably from 60 to 140 phr aluminium hydroxide, more preferably from 60 to 130 phr aluminium hydroxide, more preferably from 70 to 130 phr aluminium hydroxide, more preferably from 90 to 130 phr aluminium hydroxide.

[0088] The flame retardant may consist of from 10 to 140 phr aluminium hydroxide, preferably from 50 to 140 phr aluminium hydroxide, more preferably from 60 to 140 phr aluminium hydroxide, more preferably from 60 to 130 phr aluminium hydroxide, more preferably from 70 to 130 phr aluminium hydroxide, more preferably from 90 to 130 phr aluminium hydroxide.

[0089] Alternatively, or additionally the flame retardant may comprise from 5 to 25 phr diantimony trioxide, more preferably from 5 to 20 phr diantimony trioxide, most preferably from 5 to 15 phr diantimony trioxide.

[0090] Alternatively, the flame retardant may consist of from 5 to 25 phr diantimony trioxide, more preferably from 5 to 20 phr diantimony trioxide, most preferably from 5 to 15 phr diantimony trioxide.

[0091] Alternatively, or additionally the flame retardant may comprise of from 5 to 25 phr halogenated flame retardant, more preferably from 5 to 20 phr halogenated flame retardant, most preferably from 10 to 20 phr halogenated flame retardant.

[0092] Alternatively, the flame retardant may consist of from 5 to 25 phr halogenated flame retardant, more preferably from 5 to 20 phr halogenated flame retardant, most preferably from 10 to 20 phr halogenated flame retardant.

[0093] The flame retardants listed above may be combined together in any of the amounts set out above. Optionally, the flame retardant comprises or consists of 5 to 25 phr diantimony trioxide and 5 to 25 phr halogenated flame retardant. Optionally, the flame retardant comprises of consists of to 15 phr diantimony trioxide and 10 to 20 phr halogenated flame retardant. Mewburn Ref: 8863490

[0094] 10

[0095] Optionally, the flame retardant comprises or consists of from 10 to 140 phr aluminium hydroxide, from 5 to 25 phr diantimony trioxide and from 5 to 25 phr halogenated flame retardant. Optionally, the flame retardant comprises or consists of from 70 to 130 phr aluminium hydroxide, from 5 to 25 phr diantimony trioxide and from 5 to 25 phr halogenated flame retardant. Optionally, the flame retardant comprises or consists of from 90 to 130 phr aluminium hydroxide, from 5 to 15 phr diantimony trioxide and from 10 to 20 phr halogenated flame retardant.

[0096] Without being bound by any theory, it is believed that specific levels of flame retardant are required for specific applications, so higher levels of flame retardant may be required for articles which are designed to be exposed directly to flames, whereas lower levels might be required for articles which are less likely to be in sustained contact with burning material. For example, higher levels of flame retardant may be needed for an article of personal protective equipment for use by a steel worker, whereas lower levels of flame retardant may be required for personal protective equipment for use in military applications. Within the military sphere there exist a number of classes of flame resistance, for example those outlined in NFPA 1990.

[0097] The flame retardant may comprise a halogenated flame retardant. Halogenated flame retardants (HRFs) are a group of chemicals that contain halogens, preferably chlorine or bromine, and which are used to prevent articles from burning. Halogenated flame retardants are often organohalogen compounds, including organochlorines such as chlorendic acid derivaties and organobromines, such as decabromodiphenyl ethane (DBDPE) and decabromodiphenyl ether. Halogenated flame retardants may be used in conjunction with a synergist, such as diantimony trioxide, to enhance their efficiency.

[0098] Preferably, the halogenated flame retardant is a brominated flame retardant.

[0099] The brominated flame retardant may be selected from one of three main groups recognised by ECHA, consisting of the following, the appropriate selection of which depends on the material with least regulatory concern :

[0100] - Brominated cycloalkanes, alcohols, phosphates, triazine triones, diphenyl ethers and diphenyl alkyls;

[0101] - Tetrabromobisphenol A (TBBPA) and derivatives; and

[0102] - Brominated phthalates.

[0103] A number of brominated flame retardants according to the present invention are set out in the European Chemicals Agency (ECHA), Regulatory strategy for flame retardants (March 2023), ISBN: 978-92-9468-261-1; DOI: 10.2823 / 854233, which is hereby incorporated by reference.

[0104] For example, the brominated flame retardant may be selected from the group consisting of decabromodiphenyl ethane (DBDPE); (Pentabromophenyl)methyl acrylate; 1,1'-(ethane-1,2- Mewburn Ref: 8863490

[0105] 11

[0106] diyl)bis[pentabromobenzene]; 1,1'-(isopropylidene)bis[3,5-dibromo-4-(2,3-dibromo-2-methylpropoxy)benzene]; 1 , 1 '-(isopropylidene)bis[3,5-dibromo-4-(2,3-dibromopropoxy)benzene]; 1 ,1'-isopropylidenebis[4-(allyloxy)-3,5-dibromobenzene]; 2-(2-hydroxyethoxy)ethyl 2-hydroxypropyl 3,4,5,6-tetrabromophthalate; 2,2',6,6'-tetrabromo-4,4'-isopropylidenediphenol; 2,2',6,6'-Tetrabromo-4,4'-isopropylidenediphenol (oligomeric reaction products with 1-chloro-2,3-epoxypropane); 2,2',6,6'-Tetrabromo-4,4'-isopropylidenediphenol (oligomeric reaction products with 1-chloro-2,3-epoxypropane and 2,4,6-tribromophenol);

[0107] 2,2,6,6-tetrakis(bromomethyl)-4-oxahepta; 2,2,6,6-tetrakis(bromomethyl)-4-oxaheptane-1,7-diol, 2,2'-[(1-methylethylidene)bis[(2,6-dibromo-4,1-phenylene)oxymethylene]]bisoxirane; 2,2-bis(bromomethyl)propane-1,3-diol; 2,2-dimethylpropan-1-ol (tribromo derivative); 2,3-Dibromo-2-butene-1,4-diol; 2,3-Dibromopropanol; 2,4,6-tribromophenol; 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine; 2,4-Dibromophenyl glycidyl ether; 2-Butyne-1,4-diol, polymer with 2-(chloromethyl)oxirane (brominated, dehydrochlorinated, methoxylated); 2-Ethylhexyl 2,3,4,5-tetrabromo benzoate; 3-bromophenol; ammonium bromide; Benzene, dibromoethyl Benzene, ethenyl-, ar-bromo derivs; bis(2-ethylhexyl) tetrabromophthalate; bis(pentabromophenyl) ether; bromine; Bromoacetic acid; Bromoform; bromomethane;

[0108] Bromotrifluoromethane; dipotassium 3,4,5,6-tetrabromophthalate; hexabromocyclododecane; N,N'-ethylenebis(3,4,5,6-tetrabromophthalimide); perbromo-n,n'-biphthalimide; Polymer with 2-Butyne-1,4-Diol and (Chloromethyl-)Oxirane, Brominated, Dehydrochlorinated, Methoxylated; Reaction mass of 1,1'-(isopropylidene)bis[3,5-dibromo-4-(2,3-dibromo-2-methylpropoxy) benzene] and 1 ,3-dibromo-2-(2,3-dibromo-2-methylpropoxy)-5-{2-[3,5-dibromo-4-(2,3,3-tribromo-2-methylpropoxy)phenyl]propan-2-yl}benzene; reaction products of tetrabromophthalic anhydride with 2,2'-oxydiethanol and methyloxirane; tetrabutylphosphonium bromide; Tris[3-bromo-2,2-bis(bromomethyl)propyl] phosphate; Vinyl bromide; 1,2-Dibromoethane; 1,3,5-triazine-2,4,6-triyltriamine, monohydrobromide; 1 ,3,5-tris(2,3-dibromopropyl)-1 ,3,5-triazine-2,4,6(1 H,3H,5H)-trione; tetrabromophthalic anhydride;

[0109] FIREGUARD FG-1500 (EC number: 443-430-8) and INTERSTAB FR 184 (EC Number: 400-440-7).

[0110] Preferably, the brominated flame retardant is DBDPE.

[0111] As set out above, in some circumstances polychloroprene may also act as a flame retardant due to the liberation of chlorine at decomposition temperatures. Therefore, in certain aspects, the article of personal protective equipment may comprise a rubber matrix material comprising a butyl rubber, chloroprene and a flame retardant dispersed in the rubber matrix material.

[0112] In certain, such aspects the flame retardant may comprise or consist of aluminium hydroxide. Alternatively, the flame retardant may comprise or consist of aluminium Mewburn Ref: 8863490

[0113] 12

[0114] hydroxide and diantimony trioxide. Without being bound by any theory it is believed that the polychloroprene may have a similar synergistic flame retardant effect with the diantimony trioxide as a halogenated flame retardant.

[0115] The preferred amounts of aluminium hydroxide and diantimony trioxide set out above also apply to this particular aspect.

[0116] It may be that the the rubber composition comprises a rubber matrix material comprising or consisting of a butyl rubber, a flame retardant dispersed in the rubber materix material, wherein the flame retardant comprises or consists of aluminium hydroxide and diantimony trioxide, and wherein the rubber composition comprises a further synthetic rubber that comprises or consists of polychloroprene (which as explained above, can act as a flame retardant).

[0117] Filler

[0118] The article of personal protective equipment may further comprise fillers. Generally these fillers are dispersed in the rubber matrix material of the rubber composition. The rubber composition may comprise 1 to 90 phr, preferably from 10 to 60 phr, or from 20 to 40 phr filler.

[0119] Preferably, the filler comprises a conductive filler, such as carbon black. Without being bound by any theory, it is believed that the conductive filler is required to impart conductivity to the rubber composition in the article of personal protective equipment. Conductivity can be important where a user wants to be able to use a touch screen whilst also wearing the article of personal protective equipment, for example if the article of personal protective equipment is a glove.

[0120] Preferably, the filler comprises or consists of carbon black.

[0121] The type of carbon black is not particularly limited. For example, the carbon black may be channel black, furnace black, lamp black or thermal black. Carbon black is generally obtained by the incomplete combustion of heavy petroleum products. The carbon black may have a paracrystalline or amorphous structure. The carbon black may be acidic, neutral or basic.

[0122] Carbon black is commercially available, for example under Birla Carbon, Cabot Vulcan and Orion Corax tradenames.

[0123] Preferably the carbon black is furnace black and is resistant to mechanical breakdown through mixing and processing.

[0124] Preferably, the carbon black is a furnace carbon black grade with an iodine number of 160-182g / kg and / or an oil absorption number (OAN) number of between 107-121 ml / 100g. The ideal grades exhibit a high degree of resistance to mechanical structure breakdown and maintain electrical properties through processing. Optionally, the carbon black is ASTM N300 series furnace carbon black, N200 series furnace carbon black, N100 series furnace carbon black, Mewburn Ref: 8863490

[0125] 13

[0126] Birla Raven P or Cabot Vulcan P or a mixture thereof. Preferably, the carbon black is Birla Raven P or Cabot Vulcan P or a mixture thereof.

[0127] Preferably, the filler comprises from 5 to 50 phr carbon black, more preferably from 10 to 45 phr carbon black, more preferably from 15 to 40 phr carbon black, more preferably from 20 to 40 phr carbon black, most preferably from 25 to 35 phr carbon black.

[0128] Without being bound by any theory, it is believed that the addition of a specific amount of carbon black can help to increase the conductivity of the article of personal protective equipment, without impeding the physical properties of the material.

[0129] Optionally, the filler further comprises graphene particles and / or carbon nanotubes (CNTs).

[0130] The graphene particles may take the form of monolayer graphene (i.e. a single layer of carbon) or multilayer graphene (i.e. particles consisting of multiple stacked graphene layers). Multilayer graphene particles may have, for example, an average (mean) of 2 to 100 graphene layers per particle. When the graphene particles have 2 to 5 graphene layers per particle, they can be referred to as “few-layer graphene”.

[0131] The graphene particles may take the form of plates / flakes / sheets / ribbons of multilayer graphene material, referred to herein as “graphene nanoplatelets” (the “nano” prefix indicating thinness, instead of the lateral dimensions).

[0132] Within the meaning of this invention carbon nanotubes (CNTs) are carbon tubes. Preferably, the carbon nanotubes have a diameter of from 1-50 nm, more preferably from 5-20 nm, most preferably from 5-15 nm. Preferably, the nanotubes are 1 pm or more in length, preferably 5 pm or more in length, more preferably from 8 pm or more in length, most preferably about 10 pm. The nanotubes may have an upper length of 30 pm or less, or 20 pm or less, or 15 pm or less.

[0133] The carbon nanotubes may be single-walled carbon nanotubes (SWCNTs) or multi-wall carbon nanotubes (MWCNTs). The carbon nanotubes may be produced by any known technique for the synthesis of carbon nanotubes including arc discharge, laser ablation, chemical vapour deposition and high-pressure carbon-monoxide disproportionation.

[0134] Preferably, the carbon black, graphene particles and / or carbon nanotubes (CNTs) are uniformly dispersed throughout the rubber matrix material since aggregates (clumps) of material may decrease the performance of the article of personal protective equipment.

[0135] Without being bound by any theory, it is believed that the inclusion of carbon black and graphene particles and / or carbon nanotubes (CNTs) can be associated with an increased level of conductivity of the article of personal protective equipment. Without being bound by any theory, it is believed that these materials can also be used for their chemical barrier effect. Mewburn Ref: 8863490

[0136] 14

[0137] Optionally, the filler comprises from 1 to 20 phr graphene particles and / or carbon nanotubes (CNTs) or 1 to 10 phr graphene particles and / or carbon nanotubes (CNTs) or 1 to 5 phr graphene particles and / or carbon nanotubes (CNTs).

[0138] The article of personal protective equipment may comprise additional non-conductive fillers (in addition to the conductive fillers specified above). These materials are generally added to the rubber composition to improve the performance or processing of the rubber material. The additional fillers are generally particulate materials.

[0139] The additionally non-conductive fillers present in the material are not particularly limited. The non-conductive fillers may be selected from the group consisting of talc, silica, kaolin clay, calcium carbonate, zinc oxide, barium sulphate, magnesium aluminium hydroxide carbonate (hydrate) and titanium dioxide or combinations thereof.

[0140] Preferably, the additional filler comprises or consists of talc. Without being bound by any theory, it is believed that talc is primarily used for its effect as a chemical barrier agent. In the present invention preferably, the talc is a high purity grade of talc (such as “Magsil®” available from Faber and Vanderende BV, The Netherlands, containing <1% silica, and free of asbestos) and preferably, the talc has a high aspect ratio, for example having a length / diameter (L / D) of 1 or more, preferably 2 or more, most preferably 3 or more.

[0141] The additional filler may comprise or consist of from 1 to 40 phr talc, preferably 5 to 30 phr talc, more preferably 5 to 20 phr talc, more preferably 5 to 15 phr talc, most preferably 10 phr talc.

[0142] Processing aids

[0143] The article of personal protective equipment may also comprise additional components, for example components used to improve the processing properties of the rubber matrix material.

[0144] Optionally, the article of personal protective equipment further comprises a plasticiser. Various plasticisers are known in the art. Plasticisers may act as a softener in the rubber composition and the specific plasticiser may also affect certain performance characteristics such as the wear, durability, adhesion and grip. Plasticisers may also function as internal lubricants, improving the blending of rubber formulations and facilitating the incorporation of fillers and other additives.

[0145] Optionally, the plasticiser is a low volatility process oil or bio derived oil.

[0146] The plasticiser may be selected from the group consisting of mineral hydrocarbon oils and triglyceride vegetable oils (e.g. rapeseed oil).

[0147] The rubber composition may comprise from 1 to 15 phr plasticiser, optionally from 5 to 10 phr plasticiser. Mewburn Ref: 8863490

[0148] 15

[0149] Articles

[0150] One aspect of the present invention relates to an article of personal protective equipment.

[0151] By “personal protective equipment” we mean a range of clothing or equipment that protects the wearer from injury or harm. This equipment may be used to minimise or prevent exposure to hazards such as biological hazards, chemical hazards, electrical hazards, mechanical hazards and radiological hazards. This can include clothing items such as gloves, goggles, masks, suits, boots etc, but also materials such as tubing, filters etc. which can form part of the equipment used to protect a wearer from the above hazards which is not worn directly.

[0152] Optionally, the article of personal protective equipment is a protective item of clothing / garment. The protective item of clothing / garment is preferably for human use. Examples of protective items of clothing / garments include outerwear, bodywear, arm wear, neckwear, footwear, or headwear.

[0153] For example, the protective item of clothing / garment may be a shoe (e.g. boots, protective shoes, over boots, overshoes), gloves (e.g. protective gloves, CBRN protective gloves), eye wear (e.g. goggles, safety glasses, goggle seals), an item of headgear (e.g. a hat, a helmet a hood, a mask, a partial mask, a gas mask, ear defenders), legwear (e.g. trousers, gaiters, leg protectors), upper body wear (e.g. shirts, tops, jackets), seals (e.g. a seal on a mask or goggles, neck seals, leg seals), protective suits (e.g. immersion suits, ponchos, nuclear, biological and chemical warfare suits (known as NBC suits), diving suits, wet suits, submarine escape suits and G-suits for pilots) or a strap or belt. The above terminology is based on normal U.K. English usage, and the skilled reader will understand that certain of the above items may be given different names in other English-speaking countries, such as the U.S.

[0154] The protective item of clothing / garment may be an article of military protective clothing. By “military protective clothing” we mean a range of garments suitable for use by military personal. Military protective clothing may include gloves, helmets, eye wear, headwear and nuclear, biological and chemical warfare suits (known as NBC suits), diving suits, wet suits, submarine escape suits, immersion suits and G-suits for pilots.

[0155] Preferably, the protective item of clothing / garment is a glove, a boot, an over-boot, a protective hood, a face mask, a half mask, goggles or a seal (e.g. a seal on a mask or on goggles).

[0156] Preferably, the protective item of clothing / garment is a glove, a boot, an over-boot, a protective hood, a face mask or goggles.

[0157] Most preferably, the protective item of clothing / garment is a glove. Mewburn Ref: 8863490

[0158] 16

[0159] The protective item of clothing / garment described above may have an outer surface which is textured. This may help to improve the grip of the outer surface. For example, when the protective item of clothing / garment is a glove, the textured outer surface may faciliate gripping objects. Any suitable type of texturing on the outer surface of the article may be used. For example, the texturing may include one or more of dimples, bumps, grooves, ridges, corrugations, etc. The texturing may be provided using any suitable techniques, for example the outer surface of the article may be textured during the moulding process or by compressing the rubber composition with a textured plate or calender roll.

[0160] As set out above, the protective item of clothing / garment described above may be compatable with touchscreens, including capacitive touchscreens. In particular, the inventors have found that including a conductive filler (e.g. carbon black) in the rubber composition may provide sufficient levels of conductivity to the material to enable interaction with a capacitive touchscreen. This is of particular importance, for example in gloves which may be worn by a user when seeking to interact with a capacitive touchscreen.

[0161] Alternatively, the article of personal protective equipment may be a piece of equipment which is not directly worn by a user, but which may be carried on their person and contributes to the safety of a user. Examples of these types of personal protective equipment include sleeping bags, field shelter liners, tank covers, housing for equipment (e.g. filter housing, housing for air cylinders), filter covers, tubing (e.g. a hose or tubing for breathing equipment), covers (e.g. bag covers), a plenum (e.g. a chamber intended to contain gases), a protective sheet or laminate, and seals (such as seals between tubing and a face mask).

[0162] The article of personal protective equipment may be a piece of tubing, housing for equipment, a cover or a seal.

[0163] Preferably, the article of protective equipment may be selected from the group of a glove, a boot, or overboot, a face mask, a half mask, a protective hood, goggles, tubing, a hose, a plenum, a filter cover, a component housing cover a protective suit or a seal.

[0164] The article of personal protective equipment may also be used to refer to a portion of an item of clothing or other protective article, for example the article of personal protective equipment may be the outer layer of a glove, a boot upper, a portion of a poncho.

[0165] In a further aspect, the article of personal protective equipment may also be a fabric. Said fabric should be suitable for forming a protective item of clothing / garment as described above.

[0166] The articles of personal protective equipment according to the present invention generally refer to items which are formed from a non-woven material which results from shaping the rubber composition according to the present invention into a desired 3D shape. However, the invention Mewburn Ref: 8863490

[0167] 17

[0168] also relates to items which are multilayer items which comprise a first layer of rubber material and additional layers of fabric, which may be a woven, crocheted, knitted, or non-woven fabric. For example, the present invention relates to gloves with a rubber outer layer according to the present invention and a woven inner layer to enhance the comfort for a user. These layers can then be attached together using conventional means (such as by using adhesive, sewing etc.)

[0169] In a certain aspect, the articles of personal protective equipment according to the present invention may be formed by coating a rubber composition according to the present invention onto a fabric. This may be applied via a calendering, dipping, solvent spreading or moulding process.

[0170] Physical properties

[0171] The article of personal protective equipment comprises a rubber composition. Preferably, the rubber composition should have the following properties.

[0172] Preferably, the elongation at break of the rubber composition is greater than 200%, preferably, greater than 300%, more preferably greater than 400%, most preferably greater than 550% (determined in accordance with ISO 37 Type 2).

[0173] Optionally, the tensile strength of the rubber composition is greater than 4.5 MPa, more preferably, greater than 5 MPa (determined in accodance with ISO 37 Type 2).

[0174] Without being bound by any theory it is believed that a material with a tensile strength of less than 5 MPa or an elongation at break of less than 200% would potentially be more prone to failure during service in certain applications.

[0175] Preferably, the tear strength of the rubber composition is >20N / mm according to ISO 34-C.

[0176] Preferably, the surface resistivity of the article of personal protective equipment is less than 5 x 1010Ohms, preferably less than 5 x 109Ohms, more preferably less than 5 x 108Ohms, most preferably less than 5 x 106Ohms (measured according to EN 1149-1:2006).

[0177] Preferably, the volume resistivity is less than 1 x 109, preferably less than 1 x106, preferably less than 1 x 103, when measured in accordance with standard ISO1853 (<106ohm. cm) and ISO2951 (>106ohm.cm).

[0178] Composition

[0179] Compositions according to the present invention are also useful in applications other than personal protective equipment. The compositions according to the present invention are useful in applications where their physical properties and the flame resistance of these materials is important. Examples of these applications include furniture (e.g. seating, bedding, appliances), construction (e.g. construction materials, roofing), military applications (e.g. tanks, rockets, ships), laboratory equipment (e.g. vessels, protective screens). Mewburn Ref: 8863490

[0180] 18

[0181] Therefore, in a separate further aspect, the present invention relates to a rubber composition comprising

[0182] a rubber matrix material comprising or consisting of a butyl rubber; and a flame retardant dispersed in the rubber matrix material, wherein the flame retardant comprises or consists of aluminium hydroxide.

[0183] The composition according to the present invention comprises a rubber matrix material and a flame retardant comprising or consisting of aluminium hydroxide.

[0184] The butyl rubber matrix material is as described above for the article of personal protective equipment.

[0185] The composition also comprises a flame retardant comprising or consiting of aluminium hydroxide.

[0186] Optionally, the flame retardant further comprises one or more of diantimony trioxide, a halogenated flame retardant and magnesium hydroxide.

[0187] Optionally, the flame retardant further comprises one or more of diantimony trioxide and a halogenated flame retardant.

[0188] In one preferred aspect, the flame retardant comprises or consists of aluminium hydroxide and diantimony trioxide.

[0189] In one preferred aspect, the flame retardant comprises or consists of aluminium hydroxide and a halogenated flame retardant.

[0190] In one preferred aspect, the flame retardant comprises or consists of aluminium hydroxide diantimony trioxide and a halogenated flame retardant.

[0191] The flame retardant may comprise from 10 to 140 phr aluminium hydroxide, preferably from 50 to 140 phr aluminium hydroxide, more preferably from 60 to 140 phr aluminium hydroxide, more preferably from 60 to 130 phr aluminium hydroxide, more preferably from 70 to 130 phr aluminium hydroxide, more preferably from 90 to 130 phr aluminium hydroxide.

[0192] The flame retardant may consist of from 10 to 140 phr aluminium hydroxide, preferably from 50 to 140 phr aluminium hydroxide, more preferably from 60 to 140 phr aluminium hydroxide, more preferably from 60 to 130 phr aluminium hydroxide, more preferably from 70 to 130 phr aluminium hydroxide, more preferably from 90 to 130 phr aluminium hydroxide. Mewburn Ref: 8863490

[0193] 19

[0194] Additionally the flame retardant may comprise from 5 to 25 phr diantimony trioxide, more preferably from 5 to 20 phr diantimony trioxide, most preferably from 5 to 15 phr diantimony trioxide.

[0195] Additionally or alternatively, the flame retardant may comprise from 5 to 25 phr halogenated flame retardant, more preferably from 5 to 20 phr halogenated flame retardant, most preferably from 10 to 20 phr halogenated flame retardant.

[0196] The flame retardants listed above may be combined together in any of the amounts set out above. Optionally, the flame retardant comprises or consists of from 10 to 140 phr aluminium hydroxide, from 5 to 25 phr diantimony trioxide and from 5 to 25 phr halogenated flame retardant. Optionally, the flame retardant comprises or consists of from 70 to 130 phr aluminium hydroxide, from 5 to 25 phr diantimony trioxide and from 5 to 25 phr halogenated flame retardant. Optionally, the flame retardant comprises or consists of from 90 to 130 phr aluminium hydroxide, from 5 to 15 phr diantimony trioxide and from 10 to 20 phr halogenated flame retardant.

[0197] The halogenated flame retardant are as described above for the article of personal protective equipment.

[0198] Preferably, the halogenated flame retardant is a brominated flame retardant. The brominated flame retardants are as descibed above for the article of personal protective equipment.

[0199] As set out above for the article of personal protective equipment, in some circumstances polychloroprene may also act as a flame retardant due to the liberation of chlorine at decomposition temperatures. Therefore, in certain aspects, the article of personal protective equipment may comprise a rubber matrix material comprising a butyl rubber and chloroprene and a flame retardant dispersed in the rubber matrix material.

[0200] In certain, such aspects the flame retardant may comprise or consist of aluminium hydroxide. Alternatively, the flame retardant may comprise or consist of aluminium hydroxide and diantimony trioxide. Without being bound by any theory it is believed that the polychloroprene may have a similar synergistic flame retardant effect with the diantimony trioxide as a halogenated flame retardant.

[0201] The preferred amounts of aluminium hydroxide and diantimony trioxide set out above also apply to this particular aspect.

[0202] The amounts of each component may be for the composition as described above for the article of personal protective equipment. Mewburn Ref: 8863490

[0203] 20

[0204] The composition may further comprise a filler. The amounts and types of filler are as descibed above for the article of personal protective equipment.

[0205] The composition may comprises a further synthetic rubber. The amounts and types of synthetic rubber are as descibed above for the article of personal protective equipment.

[0206] The composition may further comprises a processing aid. The amounts and types of processing aid are as descibed above for the article of personal protective equipment.

[0207] Method of manufacture of the composition

[0208] In a further aspect, the present invention provides a method of manufacture of a composition according to the present invention or a composition suitable for use in the production of personal protective equipment according to the present invention.

[0209] The method of manufacture preferably comprises dispersing the flame retardant in the rubber matrix material.

[0210] The raw materials used to produce the composition according to the present invention or a composition suitable for use in the production of personal protective equipment may be introduced over up to 3 to 4 mixing stages to ensure optimal dispersion of the flame retardants and to ensure optimal physical properties.

[0211] In some preferred embodiments, the dispersion may be formed by mixing the flame retardant into a masterbatch with of one or more rubber polymer types. The masterbatch may or may not contain butyl rubber. The masterbatch may or may not contain other constituents from the composition according to the present invention. In embodiments, where the masterbatch does not comprise a butyl rubber the flame retardant is subsequently dispersed in a butyl rubber in order to prepare the composition according to the present invention.

[0212] Preferably, the masterbatch comprises butyl rubber (the rubber matrix material) and the flame retardant. The other ingredients are then subsequently dispersed in the masterbatch.

[0213] Without being bound by any theory, the masterbatch process enables more intensive mixing processes to be used, without the risk of pre-cure or scorch occuring in the rubber compound, this process also enables optimum levels of dispersion of flame retardant to be achieved, maximising flame retardant properties..

[0214] The step of dispersing the flame retardant in the rubber matrix material (i.e. mixing the masterbatch) generally involves mixing these components together. The butyl rubber is preferably provided as a solid material, such as high concistency rubber bales. Mewburn Ref: 8863490

[0215] 21

[0216] The mixing step is preferably achieved by high shear mixing the rubber at temperatures of from about 40 °C to about 130 °C, more preferably from about 80 °C to about 130 °C. Preferably, the mixing is carried out on a tangential (Banbury type) mixer or an intermeshing type mixer.

[0217] The mixing step may be carried out for a time period of 1 minute to 10 minutes, preferably 1.5 minutes to 8 minutes, more preferably about 2 minutes to 6 minutes.

[0218] The method of manufacture may also involve combining the butyl rubber and flame retardants (masterbatch) with additional components. These additional components may include:

[0219] - fillers (such as those set out above)

[0220] plasticiser and / or

[0221] additional polymer types such as polychloroprene, polyisoprene, styrene butadiene rubber, or ethylene propylene diene terpolymer (EPDM) rubber.

[0222] Cure system ingredients

[0223] Processing aids.

[0224] These components are generally then mixed together in a second mixing step. The second mixing step is preferably achieved by high shear mixing the composition at temperatures of from about 40 °C to about 110 °C, more preferably from about 80 °C to about 110 °C. Preferably, the second mixing step is carried out on a tangential (Banbury type) mixer or an intermeshing type mixer.

[0225] The second mixing step may be carried out for a time period of 1 minute to 5 minutes, preferably 1.5 minutes to 4 minutes, more preferably about 1.5 minutes to 3.5 minutes.

[0226] Method of manufacturing the article

[0227] In a further aspect, the present invention relates to a method of manufacturing an article of personal protective equipment, the method comprising:

[0228] providing a rubber composition;

[0229] forming the rubber composition into the desired three-dimensional (3D) shape.

[0230] Preferably, the rubber composition comprises:

[0231] a rubber matrix material comprising or consisting of a butyl rubber; and

[0232] a flame retardant dispersed in the rubber matrix material.

[0233] Typically, the rubber composition is according to the composition of the present invention. The rubber composition may be manufactured as described in the section above.

[0234] The method of manufacturing the article of personal protective equipment generally involves shaping the rubber composition into a desired 3D shape. For example, the rubber composition may be shaped to form all or part of an item of clothing / garment, such as a glove. This may be achieved using a variety of manufacturing techniques. Mewburn Ref: 8863490

[0235] 22

[0236] Preferably, the article of personal protective equipment is formed by moulding the rubber composition into a desired 3D shape and then removing the shaped article from the mould. Preferably, this involves injection moulding, injection transfer moulding or compression moulding.

[0237] Alternatively, the method of manufacturing the article of personal protective equipment involves extruding the rubber composition through a die with a desired cross section to produce a particular shaped piece of material, such as a sheet or tube. These shaped pieces of material can then be attached together (for example by glueing or sewing) to produce a complete article of personal protective equipment.

[0238] Alternatively, the method of manufacturing the article of personal protective equipment involves a calendering process, whereby the rubber composition is passed between rollers at elevated temperatures and pressures to produce a sheet of material. The sheets of material produced can then be attached together (for example by glueing or sewing) to produce a complete article of personal protective equipment. The calendering process may also combine multiple layers of compound and fabric to achieve the most desirable balance of properties.

[0239] The same methods may also be used to manufacturing a section of an article of personal protective equipment, such as a section of an item of clothing for example, a sleeve of a protective jacket. In the context of this application the sleeve of a protective jacket would also be considered an article of personal protective equipment according to the present invention.

[0240] Optionally, the method of manufacture includes a further step of curing the resulting article to obtain a cross-linked article. In this case, the method of manufacture of the article of personal protective equipment generally involves combining the butyl rubber with additional components involved in cross-linking, including a cross-linking agent and preferably a cross-linking accelerator and a cross-linking activator (e.g. in a second mixing step as described above) before the step of forming the rubber composition into the desired three-dimensional (3D) shape.

[0241] The method of manufacture of the article of personal protective equipment may include a further step of joining together two or more different components (e.g. two sleeves and a jacket body). The different components may be joined together via an adhesive. Any suitable type of adhesive may be used to join the two components together. As an example, the adhesive may be a rubber-based adhesive. Alternatively, the components may be joined together using conventional means such as weaving, stitching, or using other mechanical fasteners.

[0242] When the article of personal protective equipment is a multilayered article, the method of manufacture of the article of personal protective equipment may include an additional step of joining together the two or more layers. For example, in the manufacture of a glove this might involve joining together the outer layer of the glove with an inner layer. The layers may be joined Mewburn Ref: 8863490

[0243] 23

[0244] with adhesive. Any suitable type of adhesive may be used to join the two layers together. As an example, the adhesive may be a rubber-based adhesive. Alternatively, the layers may be joined together using conventional means such as weaving and sewing.

[0245] Uses

[0246] In a further aspect, the present invention, relates to the use of a flame retardant to provide an article of personal protective equipment with flame retardant properties.

[0247] For example, the present invention may relate to the use of aluminium hydroxide to provide an article of personal protective equipment with flame retardant properties. Additionally or alternatively the present invention may relate to the use of diantimony trioxide to provide an article of personal protective equipment with flame retardant properties. Additionally or alternatively the present invention may relate to the use of a halogenated flame retardant to provide an article of personal protective equipment with flame retardant properties.

[0248] Preferably, the present invention relates to the use of a combination of aluminium hydroxide, diantimony trioxide and a halogenated flame retardant to provide an article of personal protective equipment with flame retardant properties.

[0249] The articles of personal protective equipment generally comprise a rubber matrix material comprising or consisting of a butyl rubber. Typically the items of personal protective equipment are as described above. The preferred amounts of flame retardant present in the rubber matrix material is the same as those described above for the articles of personal protective equipment.

[0250] The term flame retardant properties should be interpreted broadly. This term may be considered to mean that the article of personal protective equipment has improved flame retardant properties compared to an article of personal protective equipment comprising a rubber matrix material comprising or consisting of a butyl rubber, which has not had a flame retardant added.

[0251] Preferbly, the present invention relates to the use of a flame retardant to provide an article of personal protective equipment which is able to resist flames for at least 3 seconds of flame application (when tested in accordance with NFPA 1990 section 7.1.7.1 and 8.4.1, ASTM F1358), more preferably the present invention relates to the use of a flame retardant to provide an article of personal protective equipment which is able to resist flames for a further 12 seconds of flame application (when tested in accordance with NFPA 1990 section 7.1.7.1 and 8.4.1, ASTM F1358).

[0252] Preferred embodiments

[0253] Particularly preferred embodiments include:

[0254] A rubber composition comprising a rubber matrix material comprising or consisting of a butyl rubber and a flame retardant dispersed in the rubber matrix material, wherein the flame retardant comprises or consists of aluminium hydroxide. Mewburn Ref: 8863490

[0255] 24

[0256] Preferably, the rubber composition comprises:

[0257] 10 to140 phr aluminium hydroxide

[0258] a butyl rubber matrix material

[0259] 5 to 25 phr diantimony trioxide;

[0260] 5 to 25 phr halogenated flame retardant;

[0261] 5 to 50 phr carbon black;

[0262] Optionally, 1 to 40 phr talc;

[0263] Optionally, 1 to 30 phr polychloroprene;

[0264] Optionally, 1 to 15 phr plasticiser; and

[0265] Optionally, graphene or carbon nanotubes.

[0266] Particularly, preferably the composition comprises:

[0267] a butyl rubber matrix material

[0268] 70 to120 phr aluminium hydroxide

[0269] 5 to 25 phr diantimony trioxide;

[0270] - 5 to 25 phr DBDPE;

[0271] 10 to 30 phr carbon black;

[0272] 1 to 20 phr talc;

[0273] 1 to 20 phr polychloroprene; and

[0274] 1 to 15 phr plasticiser.

[0275] Preferably, the halogenated flame retardant is DBDPE.

[0276] Preferably, the rubber matrix material comprises from 30 to 50 wt.% of the rubber composition and comprises chlorobutyl rubber and bromobutyl rubber.

[0277] In a further preferred aspect, the present invention relates to an article of personal protective equipment comprising a rubber composition, said rubber composition comprising:

[0278] a butyl rubber matrix material;

[0279] 10 to140 phr aluminium hydroxide;

[0280] 5 to 25 phr diantimony trioxide;

[0281] 5 to 25 phr halogenated flame retardant;

[0282] 5 to 50 phr carbon black;

[0283] optionally, 1 to 40 phr talc;

[0284] optionally, 1 to 30 phr polychloroprene;

[0285] optionally, 1 to 15 phr plasticiser; and Mewburn Ref: 8863490

[0286] 25

[0287] optionally, graphene or carbon nanotubes.

[0288] Particularly, preferably the composition comprises:

[0289] a butyl rubber matrix material;

[0290] 70 to120 phr aluminium hydroxide;

[0291] 5 to 25 phr diantimony trioxide;

[0292] 5 to 25 phr halogenated flame retardant;

[0293] 10 to 30 phr carbon black;

[0294] 1 to 20 phr talc;

[0295] 1 to 20 phr polychloroprene; and

[0296] 1 to 15 phr plasticiser.

[0297] Preferably, the halogenated flame retardant is DBDPE.

[0298] Preferably, the rubber matrix material comprises from 30 to 50 wt.% of the rubber composition and comprises chlorobutyl rubber and bromobutyl rubber.

[0299] Preferably, the article of personal protective equipment is a protective article of clothing.

[0300] In a further preferred aspect, the present invention relates to a method of manufacturing an article of personal protective equipment according to the present invention, the method comprising:

[0301] providing a rubber composition

[0302] - forming the rubber composition into the desired three-dimensional (3D) shape using injection moulding or compression moulding;

[0303] curing the resulting article to obtain a cross linked article.

[0304] Particularly, preferably the composition comprises:

[0305] a butyl rubber matrix material that comprises chlorobutyl rubber and bromobutyl rubber;

[0306] 90 to 110 phr aluminium hydroxide;

[0307] 5 to 15 phr diantimony trioxide

[0308] 10 to 20 phr halogenated flame retardant

[0309] - 25 to 35 phr carbon black

[0310] 5 to 15 phr talc;

[0311] 1 to 10 phr polychloroprene; and

[0312] 1 to 15 phr plasticizer. Mewburn Ref: 8863490

[0313] 26

[0314] Particularly, preferably the composition comprises:

[0315] a butyl rubber matrix material that comprises chlorobutyl rubber and / or bromobutyl rubber;

[0316] 70 to 120 phr aluminium hydroxide;

[0317] 1 to 20 phr diantimony trioxide

[0318] 10 to 50 phr carbon black

[0319] 1 to 20 phr talc;

[0320] 1 to 20 phr polychloroprene; and

[0321] 1 to 20 phr plasticizer.

[0322] BRIEF DESCRIPTION OF THE FIGURES

[0323] The present proposals are now explained further with reference to the accompanying figures in which:

[0324] Fig. 1 is a graph showing tan delta determination for boot and glove materials produced using conventional butyl rubber and a flame-resistant butyl rubber material according to the present invention.

[0325] Fig. 2 is a graph showing the elastic modulus determination for boot and glove materials produced using conventional butyl rubber and a flame-resistant butyl rubber material according to the present invention.

[0326] Figure 1 is a plot showing the tan delta values vs. temperature for a reference glove

[0327] [T01142_A_Standard Glove Material] and reference boot [T00949_A_Standard Boot Material] (made from the comparative butyl rubber material as described in example 1 below) and for a flame-resistant glove [T01125_B_FR Compound] (made from the flame-resistant material as described in example 1 below).

[0328] Figure 2 is a plot showing the log (elastic modulus) vs. temperature for a reference glove [T01142_A_Standard Glove Material] and reference boot [T00949_A_Standard Boot Material] (made from the comparative butyl rubber material as described in example 1 below) and for a flame-resistant glove [T01125_B_FR Compound] (made from the flame-resistant material as described in example 1 below).

[0329] EXPERIMENTAL

[0330] Example 1 - Physical properties of a flame-resistant butyl rubber composition

[0331] Butyl rubber compositions were prepared with the following compositions: Mewburn Ref: 8863490

[0332] 27

[0333] <

[0334] <

[0335] <

[0336] <

[0337]

[0338] Preparation:

[0339] Mixing of test compounds was conducted using a Haake lab Banbury mixer, with mixing being carried out over 3 separate stages, to ensure optimal dispersion of flame- retardant components and compounding ingredients. Compounds were tested on an MDR rheometer, and 2mm thick tensile Test sheets, DIN abrasion buttons, flame test specimens and 0.5mm thick permeation test sheets were moulded at 170°C, using an appropriate cure time. From these tensile test sheets were taken the specimens necessary to facilitate the tests detailed below.

[0340] The properties for each of the materials was tested using the standards set out in the table below.

[0341] Table 1: Properties of example compositions

[0342] > >

[0343] > >

[0344]

[0345] Mewburn Ref: 8863490

[0346] 28

[0347] >

[0348]

[0349] Time to breakthrough of agent simulant through a 0.5mm membrane of compound

[0350] The data in table 1 demonstrate that the flame-retardant butyl rubber material has acceptable physical properties.

[0351] Breakthrough time: Breakthrough time as measured using a custom-made permeation testing machine produced by the company Ellutia and designed to achieve the specification as described in the NIOSH document “Estimating the permeation resistance of non-porous barrier polymers". The barrier performance of the rubber material was measured by placing a 32 mm 0 disc of the rubber being tested in a heated cell (35 °C) and introducing a vapour / liquid on the external side of the sample. The thickness of the disc was measured before assembly. In this test 5 pL of toluene (allowed to vaporise separate from the rubber surface). Beneath the rubber a flow of N2(16 ml min-1, 5x volume of cell) was passed, which would transport any challenge chemical which had broken through the rubber to the detector; an Ellutia GC with Flame Ionisation Detection. Six simultaneous measurements were performed on each material being studied. Breakthrough time results presented are normalised to a nominal thickness of 0.55 mm, by dividing by the square of the measured sample thickness and multiplying by 0.55.

[0352] Example 2 - Flame tests

[0353] Flame tests were conducted in accordance with NFPA 1990 section 7.1.7.1 and 8.4.1, ASTM F1358. Tests were conducted using the flame-resistant butyl rubber material described in example 1. No flames were observed after the initial 3 seconds flame exposure and subsequent 12 seconds of flame re-application, demonstrating flame resistance (the results of the individual tests are shown in table 2 below).

[0354] Tests were conducted using the comparative butyl rubber material described in example 1. Significant flaming was observed after 12 seconds of flame application. ewburn Ref: 8863490

[0355] 29

[0356] able 2: Flame test results for example compositions

[0357]

[0358] o meet the requirements of NFPA 1990-2-22 Section 7.1.7.1, ASTM F1358 samples must have no after-flame after 12 seconds of flame application. Mewburn Ref: 8863490

[0359] 30

[0360] Example 3 - Electrical volume resistivity tests

[0361] Electrical volume resistivity tests were conducted in accordance with ISO1853. Testing was carried out using a Nittoseiko Analytech “LoResta”, designed to meet the requirements of IS01853. The tests were conducted using the flame-resistant butyl rubber material described in example 1.

[0362] Table 3: Results of electrical volume resistivity testing

[0363]

[0364] The data in table 3 demonstrates that the compositions according to the present invention retain conductivity.

[0365] Example 4 - Tan delta curves

[0366] Figure 1 shows the tan delta curves for a glove produced from the flame-resistant butyl rubber material and the comparative butyl rubber material in example 1.

[0367] These materials were then formed into a boot and glove using a standard process known to a person skilled in the art. The results demonstrate a similar temperature of peak tan delta and modulus at low temperatures for articles made from the flame-resistant material and the comparative material, suggesting that the tactile properties are largely maintained.

[0368] Example 5 - Elastic modulus testing

[0369] Figure 2 shows the elastic modulus testing for the objects produced in example 4 above. It can be seen from the temperature sweep data that the elastic modulus for the flame-resistant material is similar to that for the conventional butyl rubber.

[0370] Example 6

[0371] Tables 4 to 10 provide further example compositions. The compositions are set given here in their pre-cure state. Mixing of test compounds was conducted using a Haake lab Banbury mixer, with mixing being carried out over 3 separate stages, to ensure optimal dispersion of flame-retardant components and compounding ingredients. 2mm thick tensile Test sheets, flame test specimens were moulded at 170°C, using an appropriate cure time.

[0372] Table 4

[0373]

[0374] Mewburn Ref: 8863490

[0375] 31

[0376]

[0377] Table 5

[0378]

[0379] Table 6

[0380]

[0381] Mewburn Ref: 8863490

[0382] 32

[0383] Table 7

[0384]

[0385] Table 8

[0386]

[0387] Table 9

[0388]

[0389] Mewburn Ref: 8863490

[0390] 33

[0391]

[0392] Example 7 - Flame retardancy

[0393] The flame retardancy of the compositions of Example 6 were measured as follows, with results in tables 11-21.

[0394] Flame Testing (T00924, T00940): 10mm x 110mm x 2mm strips of rubber composition were held vertically above a gas burner with 10mm gap between the sample and the burner. A 20mm high flame was applied for 10 seconds and the self-extinguishing time after removal of the flame was recorded.

[0395] Table 11

[0396]

[0397] Mewburn Ref: 8863490

[0398] 34

[0399]

[0400] All repeats of T00924E failed to extinguish and exhibited a total burn to clamp in around 1 minute 20 seconds.

[0401] All repeats of T00924C failed to extinguish and exhibited total burn to clamp in around 3 minute 08 seconds.

[0402] Flame Testing (T00966): 10mm x 110mm x2mm strips of compound were held vertically above a gas burner with 10mm gap between the sample and the burner. A 20mm high flame was applied for the longer and more severe exposure time of 15 seconds. The selfextinguishing time after removal of the flame was recorded.

[0403] Table 12

[0404] <

[0405] <

[0406] <

[0407]

[0408] Flame Testing (T01079): 10mm x 110mm x2mm strips of compound were held vertically above a gas burner with 10mm gap between the sample and the burner. A 20mm high flame was applied for the longer and more severe exposure time of 12 seconds (Table 13). The selfextinguishing time after removal of the flame was recorded. On the final sample of the T01079A I B test variants an additional test was also undertaken where once extinguished after the initial exposure, an additional and very severe 30 second exposure was applied to ensure differences between the compounds were made clear (Table 14).

[0409] Table 13

[0410] <

[0411] <

[0412] <

[0413]

[0414] Table 14

[0415] <

[0416]

[0417] Mewburn Ref: 8863490

[0418] 35

[0419] Flame Testing (T01100): 10mm x 110mm x2mm strips of compound were held vertically above a gas burner with 10mm gap between the sample and the burner. A 20mm high flame was applied for the longer and more severe exposure time of 12 seconds (Table 15). The selfextinguishing time after removal of flame was recorded. Once extinguished, the flame was reapplied for an additional 30 seconds and the afterflame time was recorded (Table 16).

[0420] Table 15

[0421]

[0422] Table 16

[0423]

[0424] Table 17

[0425]

[0426] All repeats of T00924B entirely burnt to the clamp in about 1 min 48 seconds.

[0427] Flame Testing (T01487): 10mm x 110mm x2mm strips of compound were held vertically above a gas burner with 10mm gap between the sample and the burner. A 20mm high flame was applied for the longer and more severe exposure time of 12 seconds (Table 18). The selfextinguishing time after flame removal was recorded. Once extinguished, the flame was reapplied for an additional 30 seconds and the afterflame time was recorded (Table 19).

[0428] Table 18

[0429] <

[0430] <

[0431]

[0432] Mewburn Ref: 8863490

[0433] 36

[0434] Table 19

[0435]

[0436] Flame Testing (T01125, T01175): 10mm x 110mm x2mm strips of compound were held vertically above a gas burner with 10mm gap between the sample and the burner. A 20mm high flame was applied for the longer and more severe exposure time of 12 seconds (Table 20). The self-extinguishing time after flame removal was recorded. Once extinguished, the flame was reapplied for an additional 30 seconds and the afterflame time was recorded (Table 21).

[0437] Table 20

[0438] < <

[0439] <

[0440] < <

[0441]

[0442] Table 21

[0443]

[0444] Example 8 - Physical properties of flame-resistant butyl rubber compositions

[0445] Certain physical properties of the compositions of Example 6 are measured and set out below in Tables 12-28.

[0446] Table 22

[0447]

[0448] Mewburn Ref: 8863490

[0449] 37

[0450]

[0451] Table 23

[0452]

[0453] Table 24

[0454]

[0455] Table 25

[0456]

[0457] Table 26

[0458]

[0459] Mewburn Ref: 8863490

[0460] 38

[0461] Table 27

[0462]

[0463] Table 28

[0464]

Claims

Mewburn Ref: 886349039Claims1. An article of personal protective equipment comprising a rubber composition, said rubber composition comprising:- a rubber matrix material comprising or consisting of a butyl rubber; and - a flame retardant dispersed in the rubber matrix material.

2. The article of personal protective equipment according to claim 1 , wherein the rubber composition comprises from 20 to 190 parts per hundred rubber (phr) flame retardant.

3. The article of personal protective equipment according to claim 1 or 2, wherein the flame retardant comprises or consists of one or more of aluminium hydroxide, diantimony trioxide and a halogenated flame retardant.

4. The article of personal protective equipment according to claim 3, wherein the flame retardant comprises:10-140 phr aluminium hydroxide;- 5-25 phr diantimony trioxide; and / or- 5-25 phr halogenated flame retardant;optionally, wherein the flame retardant comprises:- 70-130 phr aluminium hydroxide;- 5-25 phr diantimony trioxide; and / or- 5-25 phr halogenated flame retardant.

5. The article of personal protective equipment according to claim 3 or 4, wherein the halogenated flame retardant is a brominated flame retardant.

6. The article of personal protective equipment according to any one of the preceding claims, wherein the rubber maxtrix material comprises from 20 to 50 wt.%, more preferably from 30 to 50 wt.%, of the total weight of the rubber composition.

7. The article of personal protective equipment according to any one of the preceding claims, wherein the rubber composition further comprises a filler.

8. The article of personal protective equipment according to claim 7, wherein the filler comprises carbon black.Mewburn Ref: 8863490409. The article of personal protective equipment according to any one of the preceding claims, wherein the rubber composition comprises a further synthetic rubber, optionally wherein the synthetic rubber is polychloroprene.

10. The article of personal protective equipment according to any one of the preceding claims, wherein the rubber composition further comprising a plasticiser.

11. The article of personal protective equipment according to any one of the preceding claims, wherein the rubber composition comprises:10 to140 phr aluminium hydroxide- 5 to 25 phr diantimony trioxide;- 5 to 25 phr halogenated flame retardant;- 5 to 50 phr carbon black;- optionally, 1 to 40 phr talc;- optionally, 1 to 30 phr polychloroprene;- optionally, 1 to 15 phr plasticiser; and- optionally, 1 to 10 phr graphene or carbon nanotubes.

12. The article of personal protective equipment according to any one of the preceding claims, wherein the article of personal protective equipment is a glove, a boot, or overboot, a face mask, a half mask, a protective hood, goggles, tubing, a hose, a plenum, a filter cover, a component housing cover a protective suit, a protective sheet or laminate, or a seal.

13. The article of personal protective equipment according to any one of the preceding claims, wherein the article of personal protective equipment is a protective article of clothing.

14. The article of personal protective equipment according to any one of the preceding claims, wherein the tensile stength of the rubber composition is greater than 4.5 MPa and / or wherein the elongation at break of the rubber composition is greater than 200%.Mewburn Ref: 88634904115. A method of manufacturing an article of personal protective equipment according to any one of the preceding claims, comprising(a) providing a rubber composition;(b) producing the desired form of the article via injection moulding, injection trnsfer moulding, compression moulding, compression transfer moulding, extrusion, rubber solution spreading / dipping, or calendering process.

16. A rubber composition comprising- a rubber matrix material comprising or consisting of a butyl rubber; and - a flame retardant dispersed in the rubber matrix material, wherein the flame retardant comprises or consists of aluminium hydroxide.

17. The rubber composition according to claim 16, wherein the flame retardant further comprises one or more of diantimony trioxide and a halogenated flame retardant optionally, wherein the flame retardant comprises or consists of aluminium hydroxide, diantimony trioxide and a halogenated flame retardant.

18. The rubber composition according to claim 16 or 17, wherein the composition comprises from 20 to 190 phr flame retardant.

19. The rubber composition according to any one of claims 16 to 18, wherein the rubber matrix material comprises from 20 to 50 wt.%, more preferably from 30 to 50 wt.%, of the total weight of the rubber composition.

20. The rubber composition according any one of claims 16 to 19, further comprising a filler.

21. The rubber composition according to claim 20, wherein the filler comprises carbon black, optionally wherein the filler comprises from 5 to 50 phr carbon black.

22. The rubber composition according to any one of claims 16 to 21, comprising a further synthetic rubber; optionally, wherein the synthetic rubber is polychloroprene and optionally wherein the composition comprises from 1 to 30 phr polychloroprene.

23. A method of manufacturing a rubber composition according any one of claims 16 to 22, comprising dispersing the flame retardant in the rubber matrix material.

24. An article comprising a rubber composition according to any one of claims 16 to 22.Mewburn Ref: 88634904225. Use of aluminium hydroxide and / or diantimony trioxide and / or a halogenated flame retardant to provide an article of personal protective equipment with flame retardant properties.

Images