ITMO20110259A1 - FLAME RETARDER MATERIAL - Google Patents

Description

Flame retardant material

The present invention relates to a flame retardant material and flame retardant textile products, which can be made using the aforementioned flame retardant material.

By â € œflame retardant materialâ € we mean a material, or a composition, which can be added to a flammable material in order to reduce its flammability and / or used to make products with the ability to retard the flame. In particular, the known flame retardant materials are able to prevent - or at least significantly reduce - the start of a fire and the spread of flames.

In the field of the textile industry, textile products are known - such as curtains, carpets, upholstery and padding, tents (for example camping tents, emergency tents) - equipped with the ability to retard the flame, in order to obtain suitable fire protection in domestic and work environments. A textile product with the ability to retard flame can be obtained by applying a flame retardant coating to a fabric and / or by treating the fabric with a flame retardant chemical. It is also possible to make yarns in a flame retardant material and then weave the flame retardant yarns to make a flame retardant textile product.

A drawback of known flame retardant textiles is that, once attacked by flames, they are unable to delay the spread of a fire for a long time. A further drawback of the known flame retardant textile products is that they are not able to reduce the development of dense fumes, which are usually generated by inflammable materials attacked by a fire and which substantially hinder the escape from the environments involved in the fire.

Furthermore, known flame retardant textiles are not capable of reducing the development of toxic gases, which can be produced by flammable materials when the latter are attacked by a fire.

Therefore, despite the substantial ability to retard the flame shown by the known materials, their use does not allow to obtain an optimal ability to retard the flame and can involve significant risks for human health.

An object of the invention is to improve known flame retardant materials.

Another object is to improve known textiles having flame retardant capabilities.

A further purpose is to make available a flame retardant textile product which, in the event of a fire, allows to significantly reduce the production of any toxic gases and / or dense fumes.

Yet another object is to make available a method for producing a flame retardant textile product which, in the event of a fire, allows to significantly reduce the production of any toxic gases and / or dense fumes.

In a first aspect of the invention, a flame retardant textile product is provided, as defined in claim 1.

In a second aspect of the invention, there is provided a method for making a textile product having the ability to retard the flame, as defined in claim 7.

The aforementioned flame retardant material and method are based on an unexpected technical effect, ie the possibility of using an intumescent flame retardant composition to coat flammable textiles, in order to provide them with the ability to retard the flame.

The so-called “intumescent flame retardant” compositions are known flame retardant compositions, which are used to coat building materials and architectural structures. An intumescent flame retardant material, when exposed to intense heat - such as the heat generated during a fire - becomes intumescent, meaning swollen, and generates a carbonized layer that is flame resistant and thermally insulating. The charred layer is able to act as a physical barrier against the transfer of heat to the underlying flammable material. The surface formation of the carbonized layer reduces the growth rate of the surface temperature below the carbonized substance. In addition, the charred layer hinders the diffusion of oxygen to the burning combustible material and thus helps to extinguish the fire. In comparison to other flame retardant materials, intumescent flame retardant compositions are capable of retarding the spread of a fire for a longer period of time.

However, the known intumescent flame retardant compositions cannot be used to suitably coat textile products, so as to provide the latter with the ability to retard the flame.

The Applicants have discovered that this drawback is due to the significant size of the particles forming the known compositions, a size which is over 200 Î1⁄4m and therefore does not allow the intumescent flame retardant compositions to be mixed correctly with other chemical components (e.g. e.g. acrylic and / or polyurethane resins) to produce flame retardant coating layers. Furthermore, due to the aforementioned unsuitable particle size, it is not possible to apply the known intumescent flame retardant compositions to textile products so as to coat the latter uniformly.

The Applicants have also discovered that, by making an intumescent flame retardant composition which is formed by particles having a size between 1 and 20 Î1⁄4m, a flame retardant material is obtained which can be effectively incorporated into textile products and which, in the event of a fire, it significantly reduces the production of any toxic gases and / or dense fumes.

In fact, the frothy carbonized layer produced by the intumescent flame retardant composition has a substantially porous structure that can absorb at least a part of any toxic gases and / or dense fumes developing from the combustion of flammable materials attacked by flames. Furthermore, the flame retardant textile product according to the invention allows to delay the spread of the fire for a longer period of time, in comparison with known flame retardant materials.

The invention can be better understood and implemented with reference to the attached drawings which illustrate an exemplary and non-limiting form of implementation, in which:

Figure 1 is a schematic perspective view, showing a three-dimensional structure of the flame retardant material usable to manufacture the flame retardant textile product according to the invention;

Figure 2 is a schematic, broken and incomplete cross-sectional view of a flame retardant textile product according to the invention, comprising a flammable material coated (or laminated) with a flame retardant film, which is made with the flame retardant material of Figure 1;

Figure 3 is a view like that of Figure 2, showing how the flame retardant film changes when exposed to the heat generated by a fire;

Figure 4 is a schematic, perspective and partially sectioned view, showing a procedure for manufacturing a flame retardant textile product according to the invention;

Figures 5 and 6 are schematic, perspective and partially sectioned views, showing a procedure for making a flame retardant film such as that shown in Figure 2; Figure 7 is a schematic, perspective and partially sectioned view, showing a procedure for bonding the flame retardant film of Figures 5 and 6 to a support fabric or fabric;

Figures 8 and 9 are schematic, perspective and partially sectioned views, showing a further procedure for manufacturing a flame retardant textile product according to the invention.

As used hereinafter, the term `` textile product '' includes textile and textile-like products in any suitable form, such as natural fabrics, synthetic fabrics, mixed natural / synthetic fabrics, non-woven fabrics, leather and synthetic leather , support fabrics (i.e. support layers designed to provide mechanical resistance to the fabrics), films, curtain cloths (for example for camping tents, for emergency tents, for gazebo tents). The films can be incorporated into textile and textile-like products and include both coating films and carrier films.

The aforementioned â € œtextile productâ € can be used in a plurality of manufacturing processes - for example to make carpets, curtains, mats, upholstery and padding for interiors and exteriors, garments, work clothes - and for a plurality of uses - for example for domestic use, for cars, trains, boats, airplanes, tents (for example camping tents, emergency tents, gazebo tents).

The intumescent flame retardant composition, which is used to make the flame retardant textile product according to the invention, is produced starting from a natural clay, consisting of layered silicates. The layered silicate has a three-dimensional lattice-like structure comprising a plurality of thin, flattened layers. More precisely, the layered silicate structure consists of hexagonal groups of silicon atoms forming stable planar grids, in which the various layers are connected to each other only by weak bonds.

Thanks to the aforementioned structural peculiarities, the layered silicate is provided with various chemical and physical properties, i.e. thermal conductivity, lubricating properties, high resistance to oxidation - in particular at high temperatures - and the ability to undergo intercalation. In chemistry, "intercalation" means a reversible (or irreversible) inclusion of a molecule (or chemical group) between two other molecules (or chemical groups). Thanks to the aforementioned layered structure of the silicates forming natural clay, atoms and / or small molecules can be introduced between the silicate layers. In this way, a so-called â € œexpandable silicateâ € is produced, that is an intercalated (layered) silicate that can expand due to exposure to heat, having a greater proportion of intercalated layers. In particular, the interleaved silicate can expand and carbonize when exposed to flames, so it can be used as an intumescent flame retardant composition and therefore as a flame retardant material, as will be explained in more detail below.

A natural clay containing layered silicates can be extracted from mines and quarries and, once extracted, undergoes a grinding phase and a flotation phase. The grinding step and the flotation step are carried out using known procedures and apparatuses. Thanks to the grinding phase and the flotation phase, the layered silicate can reach a degree of purity of approximately 95%.

The purified layered silicate is subjected to further treatments in order to remove any residual organic and / or inorganic impurities. The layered silicate is soaked in strong inorganic acids and then is heat treated with a basic substance at a high temperature. After washing, a layered silicate with a higher degree of purity, ie up to 99.5%, can be obtained.

Once a highly purified layered silicate is obtained, the expandable silicate can be produced by intercalating acids between the crystalline layers of the silicate. The intercalation is carried out using an electrochemical method which is of a known type and will therefore not be described in detail. After the intercalation reaction, the layered silicate is chemically neutralized, washed and dried.

The so obtained intercalated layer silicate is finely divided, i.e. further ground, in order to reduce the size of the silicate particles to less than 1/10 of the original size and obtain a particle size between 1 and 20 Î1⁄4m .

At the end of the procedure described above, an intercalated layer silicate is obtained which - as will be described below - is able to act as an intumescent flame retardant composition and whose three-dimensional structure is schematically illustrated in Figure 1.

The intercalated layered silicate thus produced is an expandable layered silicate, i.e. a layered silicate that expands significantly when exposed to heat and which is provided internally and on the surface with a plurality - in practice, millions - of microcavities, ie (superficial) holes and (internal) pores. It should be noted that, thanks to the aforementioned porous structure, a quantity equal to 1 g of the expandable intercalated silicate has a total surface of about 500 m <2> (i.e. the size of two tennis courts) when it expands as a consequence of ™ exposure to heat.

Figures 2 and 3 show an example of a textile product according to the invention, comprising a flammable material 1 - for example a conventional fabric used as upholstery - which is further coated with a flame retardant film 2. The flame retardant film 2 comprises the interleaved silicate described above.

The flame retardant film 2 has a thickness between 0.1 and 0.2 mm and can be produced by mixing the silicate in interleaved layers with a polyurethane resin, or with other suitable resins, or mixtures of resins. The mixture thus obtained is then applied, as a thin layer (film), on a sheet of so-called â € œreleasing paperâ € (ie an anti-adhesive paper, usually with silicone) of a known type. The release paper sheet is used temporarily during the film manufacturing process and is separated from the film before applying the film to the material to be coated.

A procedure for manufacturing the aforementioned flame retardant film is described in detail in Example 2.

In versions not shown, flame retardant films with thicknesses greater than 0.2 mm can be produced.

In the event of a fire, involving the environment containing the flammable material 1, due to exposure to the heat generated by the fire, the various layers forming the silicate in intercalated layers separate one from the other â € “Basically like an accordion - so that the interleaved silicate expands. When the expansion is complete (Figure 3), the original flame retardant film 2 has transformed into a lower layer 1a, which is an unburned layer adjacent to the underlying surface of the flammable material 1, and into an upper layer 3 expanded, foamy and charred.

The temperature at which the intercalated layer silicate begins to expand and the degree of this expansion depend on the quality of the intercalation, ie the proportion of intercalated layers, and on the intercalating agent used.

In particular, expansion can start as early as 150 ° C and can take place suddenly and quickly. The final volume of expansion can be several hundred times larger than the initial volume of the interleaved silicate.

Therefore, the intercalated layer silicate contained in the flame retardant film 2 acts as an intumescent flame retardant material, in which the upper layer 3 effectively slows down and hinders the spread of the fire.

In addition, the intumescent flame retardant film 2 significantly reduces two of the most dangerous effects of combustion, namely the development of dense fumes and the production of potentially noxious gases. In fact, as shown schematically in Figure 3, the carbonized upper layer 3 contains a large number of microcavities 4 (schematically represented by circles), which can trap corresponding volumes of smoke 5 (schematically represented by circles) and of gas 6 (schematically represented by circles). Therefore, the upper layer 3 is able to absorb enormous quantities of gas and fumes, so that, during a fire, a greater quantity of purer and more breathable air is made available. In this way, it is possible to more effectively protect the health of any people present in the environment involved in the fire and prevent, or at least significantly reduce, the development of dense fumes, which substantially hinder escape from the aforementioned environment.

In addition to the aforementioned flame retardant film, it is possible to make a plurality of flame retardant textile products, including the intumescent flame retardant composition based on the interleaved silicate described above. Some of these flame retardant textile products are described in the following Examples 1 to 5 and with reference to Figures 4 to 9. In Examples 1-5 and in Figures 4-9 devices and apparatuses which are known to the people who are experts in the field of the textile industry and therefore will not be described in detail.

Example 1 - Fabric with a flame retardant coating

An intumescent flame retardant composition, comprising a finely divided intercalated layer silicate in particles ranging in size from 1 to 20 Î1⁄4m, is mixed with a resin to form a fluid mixture 7. The resin may comprise a resin polyurethane, an acrylic resin or a mixture thereof. With reference to Figure 4, the fluid mixture 7 is pumped from a tank 8 and poured onto a fabric 9 for domestic use, while the fabric 9 is mechanically unwound from a first roller 10 (upstream) and rewound onto a second roller. 11 (downstream), along a direction of travel indicated by arrow F1. Fabric 9 can be cotton (100%), polyester (100%), or a mixed cotton / polyester fabric, such as CVC (so-called â € œChief Value Cottonâ €, containing more than 50% cotton). The fluid mixture 7 is spread and made to adhere on a surface 9a of the fabric 9 by means of a doctor blade (spreading) device 12. A drying chamber 13 is arranged between the first roller 10 and the second roller 11, so that © the fabric coated with fluid mixture 7 enters the drying chamber 13 and is heat treated at a temperature kept below 140 ° C. An intumescent flame retardant fabric 14 emerges from the drying chamber 13.

The procedure described above can be repeated several times in order to increase the final thickness of the flame retardant fabric 9.

Example 2 - Flame retardant film The intumescent flame retardant composition of Example 1 is mixed with a resin to form a fluid mixture 7. The resin may comprise a polyurethane resin, an acrylic resin or a mixture thereof . With reference to Figure 5 (in which the elements previously described with reference to Figure 4 are designated with the same reference numbers), the fluid mixture 7 is pumped from a tank 8 and poured onto a sheet 15 of type release paper known, while the sheet 15 is mechanically unwound by a first roller 10 (upstream) and rewound on a second roller 11 (downstream), along a direction of advancement indicated by the arrow F1. The fluid mixture 7 is spread and made to adhere on a surface 15a of the sheet 15 by means of a doctor blade device 12. A drying chamber 13 is arranged between the first roller 10 and the second roller 11, so that the sheet 15 - coated with fluid mixture 7 - enters the drying chamber 13 and is heat treated at a temperature kept below 140 ° C. In this way a semi-finished product 16 is obtained, consisting of the intumescent flame retardant coating and the underlying release paper sheet. The semi-finished product 16 is subjected to a delamination procedure (schematically shown in Figure 6), during which the release paper sheet 15 is detached from the heat treated intumescent flame retardant coating. The latter thus becomes an intumescent flame retardant film 17, which can be used to coat flammable materials, such as fabrics.

Example 3 - Flame retardant film bonded to a fabric With reference to Figure 7 (in which the elements previously described with reference to Figures 4 and 5 are designated with the same reference numbers), an intumescent flame retardant film 17 â € "obtained through the procedure described in Example 2 - It is mechanically unwound by a first roller 10 (upstream) and rewound on a second roller 11 (downstream) along a direction of advance indicated by the arrow F1, while an agent binder, that is a glue, 30 is pumped from a tank 8 and poured on the film 17. The glue 30 is sprinkled, and made to adhere, on a surface 17a of the film 17 by means of a doctor blade device 12. Between the first roller 10 and the second roller 11 a first drying chamber 13, a calender (rotary press) 18 and a second drying chamber 13a are arranged in sequence. Above the calender 18 p a third roller 10a is arranged on which a fabric 20 is wound, which must be bonded to the film 17. The film 17 - coated with glue 30 - enters the first drying chamber 13 and is heat treated at a temperature maintained below 140 ° C. The heat-treated film 17 emerges from the first drying chamber 13, while the fabric 20 is unwound from the third roller 10a and conveyed towards the calender 18, so that the film 17 and the fabric 20 are made to pass simultaneously through the calender 18. Thanks to the combined action of the calender 18 and the glue 30, the fabric 20 and the film 17 are mutually bonded (lamination). The fabric 20 bonded to the film 17 enters the second drying chamber 13a, in which the fabric 20 and the film 17 are heat treated at a temperature maintained below 110 ° C.

In this way, a finished product 40 is obtained - consisting of the intumescent flame retardant film 17 laminated with the fabric 20 - in which the film provides the fabric with the ability to retard the flame.

Example 4 - Flame retardant film bonded to a support fabric

The procedure and the equipment are the same as in Example 3 and the only difference is that a support fabric - instead of a fabric - is wound on the third roll. In this way, a finished product is obtained - consisting of the intumescent flame retardant film laminated with the backing fabric - in which the film acts as a flame retardant fabric. Example 5 - Synthetic leather or flame retardant synthetic leather With reference to Figure 8 (in which the elements previously described with reference to Figures 4-7 are designated with the same reference numbers), in a first area A of a line of production, a sheet 15 of release paper is mechanically unwound - along the direction of advancement indicated by the arrow F1 - by a first roller 10 (upstream) and rewound onto a second roller 11 (downstream). A first doctor blade device 12, a first drying chamber 13, a second doctor blade device 12a and a second drying chamber 13a are arranged in sequence between the first roller 10 and the second roller 11. A 7a polyurethane resin is pumped from a tank 8 and poured onto the 15 sheet of release paper. The risana 7a is sprinkled and made to adhere on a surface 15a of the sheet 15 by means of the first doctor blade device 12. The sheet 15 coated with resin enters the first drying chamber 13 and is thermally treated at a temperature of 140 ° C. The sheet 15 coated with resin and thermally treated emerges from the first drying chamber 13, while a fluid mixture 7b is pumped from a second tank 8a and poured onto the sheet 15. The fluid mixture 7b consists of a polyurethane resin and the composition intumescent flame retardant of Example 1. The fluid mixture 7b is sprinkled and made to adhere to the surface of the sheet 15 by means of the second doctor blade device 12a. Sheet 15 - which is coated with polyurethane resin 7a and fluid mixture 7b (polyurethane resin and intumescent flame retardant composition) - enters the second drying chamber 13a, where it is heat treated at 140 ° C . A semi-finished product 21 emerges from the second drying chamber 13a, consisting of the sheet 15 of release paper, a film of polyurethane resin 7a and the fluid mixture 7b.

With reference to Figure 9 (in which the elements previously described with reference to Figures 4-7 are designated with the same reference numbers), the semi-finished product 21 is transferred from the first area A to a second area B of the production, in which the semi-finished product 21 is mechanically unwound by a first roller 110 (upstream) and rewound on a second roller 111 (downstream). A third doctor blade device 12b, a third drying chamber 13b, a calender (rotary press) 18 and a fourth drying chamber 13c are arranged in sequence between the two rollers 110 and 111.

A further roller 110a is arranged above the calender 18, on which a support fabric 50 is wound which must be bonded to the semi-finished product 21. While the semi-finished product 21 is conveyed along the direction of advancement indicated by the arrow F1, a binder 60 is pumped from a tank 8b and poured onto a surface 21a of the semi-finished product 21. The binder 60 is sprinkled and made to adhere to the surface 21a of the semi-finished product 21 by means of the third doctor blade device 12b.

The semi-finished product 21, which is coated with binder 60, enters the third drying chamber 13b and is thermally treated at a temperature of 110 ° C. The thermally treated semi-finished product 21 comes out of the third drying chamber 13b and is conveyed towards the calender 18. The support fabric 50 is unwound by the third roller 110a and conveyed towards the calender 18, so that the semi-finished product 21 and the fabric of support 60 are made to pass simultaneously through the calender 18 and, thanks to the pressure exerted by the latter, are mutually linked. The support fabric 50 bound to the semi-finished product 21 enters the fourth drying chamber 13c, in which the support fabric 50 and the semi-finished product 21 are thermally treated at a temperature of 110 ° C. The support fabric 50 and the semi-finished product 21 come out of the fourth drying chamber 13c and are subjected to a delamination procedure. During the delamination phase, the sheet 15 of release paper is detached and wound onto a further roller 112, while a finished product 70 is wound onto the second roller 111.

The finished product 70 thus obtained is a synthetic leather, or a synthetic leather, provided with a suitable ability to retard the flame.

Variations and / or additions to what has been described above and / or what is shown in the attached drawings are also possible.

Claims (10)

CLAIMS 1. Flame retardant textile product (2; 14; 17; 40; 70), comprising an intumescent flame retardant composition. 2. Flame retardant textile product (2; 14; 17; 40; 70) according to claim 1, wherein said intumescent flame retardant composition comprises particles having a size comprised between 1 and 20 Î1⁄4m. The flame retardant textile product (2; 14; 17; 40; 70) according to claim 1, or 2, wherein said intumescent flame retardant composition comprises an intercalated layer silicate. 4. Flame retardant textile product (2; 14; 17; 40; 70) according to one of the preceding claims, wherein said intumescent flame retardant composition is made in the form of a film or coating. 5. Flame retardant textile product (2; 14; 17; 40; 70) according to one of the preceding claims, wherein said textile product is selected from a group consisting of: natural fabrics, synthetic fabrics, mixed natural / synthetic fabrics, non-woven fabrics, leather or synthetic leather, support fabrics, films, curtain cloths. 6. Use of a flame retardant textile product (2; 14; 17; 40; 70) according to one of the preceding claims to give an object, or a material, a flame retardant ability. 7. Method for making a textile product (2; 14; 17; 40; 70) provided with flame retardant capability, comprising incorporating an intumescent flame retardant composition into a textile product. 8. Method according to claim 7, wherein said intumescent flame retardant composition comprises particles having a size comprised between 1 and 20 µl 4m. The method according to claim 7, or claim 8, wherein said incorporating comprises coating said textile with said intumescent flame retardant composition. The method according to claim 7, or claim 8, wherein said incorporating comprises bonding said textile product to a film made with said intumescent flame retardant composition.