WO2009136245A1

WO2009136245A1 - Protective textile material against the action of melted materials

Info

Publication number: WO2009136245A1
Application number: PCT/IB2009/005416
Authority: WO
Inventors: Roberto Fenzi
Original assignee: Lenzi Egisto S.P.A.
Priority date: 2008-05-06
Filing date: 2009-04-29
Publication date: 2009-11-12
Also published as: EP2274167A1

Abstract

A protective textile material against (1) the action of melted materials, comprising at least one textile layer (2) including fibres having flameproof properties, said at least one textile layer (2) being associated to at least one protective layer (6a, 6b) comprising: (a) at least one binding resin,- (b) at least one mineral filler; (c) at least one fluorinated polymer; (d) at least one flame retardant agent.

Description

"PROTBCTIVE TEXTILE MATERIAL AGAINST THE ACTION OF MELTED MATERIALS"

DESCRIPTION

The present invention relates to a protective textile material against the action of melted materials.

The present invention arises from the need to protect workers in various industrial fields, e.g. carpentry, building field, metallurgic field, in particular those working in blast furnaces or with metal welding devices, from sparks and spatters of melted material, especially melted metals or asphalt or bitumen, so as to prevent injuries resulting from the accidental contact with these materials. Traditionally, garments are made to this purpose, such as e.g. aprons, gloves, jackets and the like, comprising very thick leather layers, which are heavy, with bad wearability and low comfort.

More recently, protective garments made with real fabrics have been proposed, which are more comfortable and lighter but which do not often give suitable protection.

Materials used for making such protective garments are generally made of aramid fibres, specifically para- aramid and meta-aramid fibres, often in combination with other fibres such as wool or viscose fibres treated with flame retardant agents (the so-called FR or "flame retardant" yarns) . In particular_/ the latter act as sacrificial fibres, absorbing heat released by the melted material when cooling, so as to enable the aramid fibres to perform a real protective action,.

The Applicant has faced the problem to combine in one textile material a high resistance to flame and to the action of melted materials with a sufficient smoothness, such as to allow to make protective garments that are also light and comfortable, so as to drastically reduce the risk of stresses due to fatigue and heat resulting from heavy jobs performed in high temperature environments., In particular, the Applicant has faced the problem to achieve this objective without necessarily using fibres having per se a very high flame resistance, which are expensive and hard to find on the market. while trying to solve this problem, the Applicant has realized that commonly used fabrics have a low protection which is sometimes wholly inadequate for splashes of high melting metals or alloys, such as e.g. iron which has a melting point of 1536ºC, or steel which melts at 115O ºC to 1536ºC depending on carbon percentage. In particular, the Applicant has found that prior art garments do not ensure an adequate protection especially against melted aluminium. Aluminium has a melting point of 660ºC and a high thermal capacity, i.e. it can release much heat with a small temperature variation. As a matter of fact, in the first instants of the cooling process aluminium undergoes the passivation phenomenon, i.e. it is covered with an oxide coating which drastically slows down heat exchanges with the surrounding environment and thus cooling itself.

The combined action of melting point, though not particularly high^, and above all of thermal capacity, which extends cooling time, makes aluminium compromise the action of sacrificial fibres: aramid fibres are therefore decomposed and the protective action of the fabric fails.

In this context, the main technical task of the present invention is to provide a protective textile material which overcomes the drawbacks of prior art as mentioned above.

In particular, an aim of the present invention is to provide a protective textile material which can resist the contact with high temperature melted materials, and especially steel or aluminium, so as to affectively protect the worker. A further aim of the present invention is to provide a textile material allowing to make protective garments that are light, easily wearable and comfortable for the user. Another aim of the present invention is to provide a protective textile material which can resist the contact with high temperature melted materials, which is washable and maintains its peculiar features even after several washing operations, in particular water washing at 30ºC.

The Applicant has found that these and other aims of the invention can be achieved by means of a protective textile material comprising at least one textile layer including fibres having flameproof properties, which is associated - e.g.. by coating - to at least one protective layer comprising at least one binding resin, at least one mineral filler, at least one fluorinated polymer and at least one flame retardant agent. This protective layer has a high resistance to flame and high temperatures and further enables to drastically reduce the adhesion onto the protective material of splatters of melted materials, in particular melted metals, so as to reduce the time they remain on the material and thus improve the protective action for the user. The protective textile material thus obtained is further particularly resistant to several washing operations, in particular water washing at 30ºC.

According to a first aspect, the present invention therefore relates to a protective textile material comprising at least one textile layer including fibres having flameproof properties, wherein said at least one textile layer is associated to at least one protective layer comprising: (a) at least one binding resin; (b) at least one mineral filler; (c) at least one fluorinated polymer; (d) at least one flame retardant agent.

In a second aspect, the present invention relates to the use of a protective textile material as defined above for manufacturing a protective item, in particular a garment, against the action of melted materials. Examples of garments that can be made according to the present invention are: aprons, gloves, jackets, shoes (in particular shoe uppers) . λs far fibres having flameproof properties are concerned/ these are generally of natural, artificial or synthetic origin, preferably having a Limiting Oxygen Index (LOI) not lower than 25, more preferably of 28 to 40. LOI can be determined according to standard ASTM D-2863. The above fibres can be selected for instance among wool, cotton, viscose rayon, polyester, rαodacrylic, basalt, ararαid (in particular para-aramid) , pre- oxidized fibres (in particular pre-oxidised polyacrylonitrile fibres) or combinations thereof.

These fibres can be intrinsically flameproof or to them can be conferred flameproof properties by suitable treatments. To this purpose the fibres can be preferably treated with at least one flame retardant agent. This treatment can be made during the spinning step or during the finishing step on the fibre, according to processes that are well known in the art. This treatment can make use of flame retardant agents selected among the products listed below as possible flame retardant agents for the protective layer according to the invention,,

Said at least one textile layer can be made of at least one layer of real fabric obtained by weaving with a weft-warp structure, or of at least one non- woven layer, or also of a combination of at least one layer of fabric with at least one non-woven layer. As an alternative, the textile layer can comprise at least one layer having a knitted structure, particularly a blocked knitted structure. In the case of a layer of fabric, this can be made with various patterns_/ e.g. it can be a orthogonal fabric with weft and warp yarns arranged perpendicularly to one another. Weft and warp yarns can be made with the same or different fibres. In the case of a non-woven layer, this can be obtained with known techniques, e.g. with a needle punching process .

Advantageously, the protective textile material can comprise one textile layer only or a plurality of textile layers in a number ranging from 2 to 6.

Preferably, each textile layer is associated to at least one protective layer according to the present invention. Preferably, each textile layer is applied onto at least one face of the textile layer in an amount generally ranging from 15 to 50 g/m², preferably from 20 to 40 g/m².

Advantageously, a protective layer lies on the outer face of at least one of the outer textile layers, and it is therefore designed to be directly exposed to the outer environment in use.

In order to improve the transpirability of the protective textile material according to the present invention, it can be provided with a plurality of through microholes, i.e. small holes getting through the material from side to side. Thus the comfort of the end item is significantly improved, since the microholes enable air to pass through, preventing heat and/or moisture stagnation in the space between the user's body and the item,, This feature is particularly suitable if the user works in overheated environments, e.g. near blast furnaces, and/or makes relevant physical efforts causing an intense perspiration. The density of microholes required to obtain the desired effect can vary within wide ranges as a function of the specific conditions of use of the item. In general, a sufficient transpirability can be achieved with a number of microholes ranging from 10 to 50 microholes/cm², preferably from 20 to 35 microholes/cm² , Microholes in the protective textile material according to the present invention can be obtained by making holes in the finished material with a plurality of needles having a diameter generally ranging from 0.5 to 5 mm, preferably from 1 to 3 mm. Preferably, microholes are distributed on the material surface according to a predefined pattern so as to obtain a basically constant hole density on the whole surface .

It should be pointed out that the presence of these microholes does not compromise in any way the protective properties of the textile material according to the present invention, since microhole size is such to prevent the penetration of high viscosity and/or surface tension melted materials, such as metals, asphalts and the like. The protective layer according to the present invention preferably comprises :

(a) from 5 to 40% by weight_/ preferably from 10 'to 30% by weight, of at least one binding resin;

(b) from 25 to 75% by weight/ preferably from 35 to 65% by weight_/ of at least one mineral filler;

(c) from 5 to 40% by weight, preferably from 10 to 30% by weight, of at least one fluorinated polymer;

(d) from 2 to 30% by weight/ preferably from 5 to 20% by weight_/ of at least one flame retardant agent. As far as the binding resin is concerned/ this is preferably selected among: acrylic resins, polyurethane resins, polyurethane-acrylic resins, nitrile resins, silicone resins_/ or mixtures thereof. Preferably, these resins are used in the form of an aqueous dispersion or emulsion.

The mineral filler is preferably used in the form of a fine powder, having an average particle size not higher than 0.5 mm, preferably not higher than 0.1 mm, and can be selected among e.g. : silicates (e.g. iron silicates), carbides (e.g. silicon carbide, titanium carbide, boron carbide), nitrides (e.g. silicon nitride, boron nitride) , oxides (e.g. silica, alumina, magnesium oxide) , ceramic materials, and the like., As far as the fluorinated polymer is concerned, this can be selected among products known in the art as agents for finishing natural, artificial or synthetic fibres. Preferably, said fluorinated polymer is a polyfluoroacrylate. Suitable polyfluoroacrylates can be obtained e.g. by polymerisation of at least one monomer having formula;

wherein:

is a non-fluorinated alkylene group having 1 to 8 carbon atoms ; Rf is an at least partially fluorinated organic group, preferably a perfluoroalkyl group having 4 to 24 carbon atoms,,

These fluorinated polymers can be used in the form of a solution or dispersion in at least one organic solvent, such as e.g. ethylene glycol or acetone. As an alternative, said fluorinated polymers can be used in the form of an aqueous emulsion stabilized by at least one non-ionic or cationic surfactant. Particularly preferred are the commercial products Oleophobol® of Huntsman Corp. As far as flame retardant agents are concerned, these can be selected among e.g.: - inorganic agents, e.g. magnesium hydroxide, aluminium hydroxide, mixed magnesium-aluminium hydroxide, zinc borate, ammonium polyphosphate, red phosphor; - organophosphorated compounds, e.g. triphenyl phosphate, tricresyl phosphate, tri(isopropylphenyl) phosphate; halogenated compounds, e.g. polybrominated diphenyl ethers, polybrominated diphenyls, if necessary combined with antimony trioxide;

- melamine compounds, e.g. melamines, derivatives thereof or salts thereof with organic or inorganic acids;

- silicone compounds; or mixtures thereof.

The composition making up the protective layer according to the present invention can be prepared by mixing with conventional techniques, particularly with a room temperature mixer. The aforesaid composition can be applied onto the textile layer with known techniques, e.g. by coating, particularly by air knife coating, followed by a drying step. The present invention will now be disclosed in further detail thanks to some examples of embodiment, which are provided as mere examples not limiting the scope of the invention, referring in particular to the figures accompanying the present description, in which: Figure 1 is a schematic sectioned view of a portion of protective textile material according to the present invention, in a first embodiment thereof;

Figure 2 is a schematic sectioned view of a portion of protective textile material according to the present invention, in a second embodiment thereof. With reference to Figure 1, a first embodiment of the protective textile material 1 comprises at least one layer 2 of fabric in which the warp 3 and the weft 4 are made up of flameproof fibre yarns, with a count generally ranging from 200 to 450 dtex, with a density of warp yarns ranging from 10 to 25 yarns/cm, and with a density of weft yarns ranging from 8 to 20 yarns/cm,, The cloth resulting from the weaving of weft and warp as described above generally has a weight ranging from 300 to 500 g/m², preferably from 350 to 400 g/m².

At least one of the faces 5a and 5b of the layer of fabric 2 is associated to a protective layer 6a and/or 6b, respectively, according to the present invention,. Preferably, each protective layer is applied onto at least one of said faces 5a and 5b in an amount generally ranging from IS to 50 g/m², preferably from

20 to 40 g/m².

A second variant, shown in Figure 2, comprises at least two layers 2a and 2b of flameproof fibre fabric having a weft-warp structure like the one shown in

Figure 1, each layer of fabric being associated to at least one protective layer 6a and 6b. Preferably, as shown in Figure 2, a further protective layer 6c according to the present invention is present between the two layers of fabric 2a and 2b.

EXAMPLE.

A protective textile material according to the present invention was made starting from: a layer of fabric made up of pre-oxidized fibres and para-aramid fibres, having a count of 2/36 NM, with orthogonal structure (density of warp yarns 25.5 yarns/cm; density of weft yarns 18.5 yarns/cm; weight

390 g/m²); a protective layer obtained by coating (26 ± 10% g/m²) onto a face of the layer of fabric a composition made up of:

wherein :

SiC: silicon carbide in the form of a powder, of Wester Mineralien GmbH;

Oleophobol® S: catioriic polyfluoroacrylate, in the form of a dispersion in an ethylene glycol/acetone mixture, of Huntsman Textile Effects GmbH;

E 821 : acrylic resin in water, of Acril Nova SrI;

Cabertex© DB: flame retardant agent comprising 15-20% of antimony oxide in aqueous dispersion, stabilized with surfactants.

The textile material thus obtained was subjected to tests of resistance to melted metals according to Standards EN 470-1 :1995/A1 and EN 531:1995. (1) Flame spread.

Tests were made on six samples of the above textile material, after water washing as described in 7.2 of standard EN 470-1 :1995/A1. The samples were then conditioned for 24 hours at 20° ± 2°C with relative humidity of 65 ± 5%. The test method is described in detail in standard EN B32. The tests were made at a temperature of 1O°C to 3OºC and relative humidity of 15% to 80% and with a pressure wave above 0.2 m/s. Each sample was mounted onto a sample holder (a frame sized 190 x 150 ± 1 cm) by means of pins, and kept at a"distance of 20 mm from the sample holder by means of suitable spacers. The flame of a burner (horizontal flame with a length of 25 ± 2 mm) was applied onto the sample thus mounted" and kept in vertical position, perpendicularly to the same at a distance of 17 ± 1 mm from the surface. The flame was applied for 10 sec. All of the six samples have passed the test since on each sample:

- no flame could be seen on the surface; — no holes formed;

- the average value of post-inflammation time was less than 2 sec;

- the average value of afterglow time was less than 2 sec. (2) Impact of droplets of melted metal.

The test method defines the behaviour of the material when hit by small splashes of melted metal, in particular by droplets of melted steel. The execution mode is described in detail in standard EN 348. To summarize, the test involves the determination of the minimum number of droplets required to cause a temperature rise of 4OºC in a temperature sensor (of resistive type) , placed behind the sample in vertical position. The test is passed if this number is of at least 15 droplets. The samples (sized 120 mm x 20 mm) were washed and conditioned as described above. Droplets are made by melting a steel bar according to standard ISO 636 type gl, with a linear density of 0.5 ± 0.2 g/cm. By means of a welding torch the steel bar is melted, with the resulting formation of droplets of melted steel which are directed towards the sample with a guide. The tests carried out have shown that 40 droplets of melted steel determined in the sensor a temperature variation of 20..1ºC (average value on 10 tests), thus much below the maximum value of 40ºC required by the standard.

(3 ) Convective heat transmission. The test enables to determine the protection ensured by the material towards the transmission of convective heat. Test details are described in standard EN 367. The sample (sized 140 x 140 mm) is first washed and conditioned as described above,. The sample, placed in horizontal position, is subjected to an incident heat flow of SO kW/m² sent by the flame of a propane gas burner located under the sample. The test involves the measurement of the average time in seconds required to obtain a temperature rise of a copper disc, placed on the sample at a starting temperature of 25° ± 5ºC, of 24° ± 0.2ºC The performance level is determined according to the following Table 1:

The performance level of the samples (three tests) was B2. (4) Radiant heat transmission.

The test enables to determine the protection ensured by the material towards the transmission of radiant heat. Test details are described in standard ISO 6942 Method B. The sample (sized 230 x 80 mm) is first washed and conditioned as described above. The sample, placed in horizontal position, is subjected to a radiation source made up of six bars of silicon carbide heated by electrical current (density of heat flow 20 kw/m²) . The sample is placed in contact with the curved face of a calorimeter applying a force of 2 N. The test involves the determination of the time T₁₂ required to obtain a temperature rise of 12º ± 0.1ºC in the calorimeter, and. the determination of the time T24 required to obtain a temperature rise of 24° + 0.1ºC in the calorimeter. The difference between these two times (T₂) provides the performance level according to the following Table 2 :

The performance level of the samples (three tests) was

C1.

{ 5) Resistance to splashes of melted, metals . The test enables to determine the resistance of the material to splashes of melted metals, in particular of aluminium or steel. Test details are described in standard EN 373. According to this method, materials are tested by pouring given amounts of melted metal onto a sample of the material (sized: 240 ± 2 mm x 80 + 2 mm) installed on, a frame with a predefined inclination with respect to the horizontal plane. Deterioration is evaluated by placing a PVC film (standardized film) directly behind the sample and by observing the deterioration thereof after pouring the metal. The minimum amount of metal causing a deterioration of the PVC film determines the performance level, as shown in the following Tables 3 and 4:

The specific conditions used for aluminium and iron are listed in Table 5. TABLE 5

The results obtained for aluminium and iron are listed in the following Tables 6 and 7, respectively:

TABLE 6

The samples of the protective material according to the invention can therefore be classified with performance level D3 (aluminium) and E3 (iron) (standard EN 531: 1995).

Claims

X. A protective textile material comprising at least one textile layer comprising fibres having flameproof properties, wherein said at least one textile layer is associated to at least one protective layer comprising: (a) at least one binding resin,- (b) at least one mineral filler; (c) at least one fluorinated polymer; (d) at least one flame retardant agent.

2 , The protective textile material according to claim 1, wherein said at least one textile layer comprises fibres of natural, artificial or synthetic origin having a Limiting Oxygen Index (LOl) not lower than 25, preferably comprised from 28 to 40.

3 ♦ The protective textile material according to anyone of the previous claims, wherein said at least one textile layer is formed by at least one layer of a fabric having a weft-warp structure, or by at least one woven-non-woven layer, or by a combination of at least one layer of fabric with at least one woven-non- woven layer, or said at least one textile layer comprises at least one layer having a knitted structure, particularly a blocked knitted structure,,

4. The protective textile material according to anyone of the previous claims, wherein said at least one protective layer is applied on at least one surface of each textile layer in an amount generally comprised from 15 to 50 g/m², preferably from 20 ro 40 g/m².

5. The protective textile material according to anyone of the previous claims, wherein a plurality of passing through microholes is present.

6. The protective textile material according to claim 5, wherein the microholes have a density ranging from 10 to 50 microholes/cm², preferably from 20 to 35 microholes/cm².

7. The protective textile material according to anyone of the previous claims, wherein said at least one protective layer comprises: (a) from 5 to 40% by weight, preferably from 10 to 30% by weight_/ of at least one binding resin;

(b) from 25 to 75% by weight, preferably from 35 to 65% by weight, of at least one mineral filler/

(d) from 2 to 30% by weight, preferably from 5 to 20% by weight, of at least one flame retardant agent.

8. The protective textile material according to anyone of the previous claims, wherein said at least one binding resin is selected, from: acrylic resins, polyurethane resins, polyurethane -polyacrilic resins, nitrile resins, silicone resins, or mixtures thereof.

9. The protective textile material according to anyone of the previous claims, wherein said at least one mineral filler is used in the form of a fine powder, having an average particle size not higher than 0,5 mm, preferably not higher than 0 „ 1 mm.

10. The protective textile material according to anyone of the previous claims, wherein said at least one mineral filler is selected from: silicates, carbides, nitrides, oxides, ceramic materials, or mixtures thereof .

11» The protective textile material according to anyone of the previous claims, wherein said at least one fluorinated polymer is a polyfluoroacrylate .

12. The protective textile material according to claim 11, wherein the polyfluoroacrylate is obtained by polymerizing of at least one monomer of formula: ^"

wherein:

is a non-fluorinated alkylene groups having from 1 to 8 carbon atoms; R_f is an at least partially fluorinated. organic group, preferably a perfluorinated group having from 4 to 24 carbon atoms.

13. Use of a protective textile material according to anyone of the previous claims for manufacturing an article, particularly a garment protecting against melted materials.