Patent Application
20220042237
The invention relates to a textile heat, fire and/or smoke protection material comprising a textile, flat substrate coated with a polymer composition, the polymer composition containing a crosslinked polysiloxane and metal pigments, a process for the production of a textile heat, fire and/or smoke protection material and the use of a textile heat, fire and/or smoke protection material according to the headings of the independent claims as a heat protector.
For the combustion of exhaust gases, for example in the engine compartment or exhaust systems, high combustion temperatures are necessary. Cables and hoses used in such systems (turbochargers, flame tubes, catalytic converters), which are often made of elastomers, must be protected from such high temperatures in the long term to prevent their early aging and fatigue. Fatigued elastomers can crack or burst, causing further damage and, in the worst case, vehicle fires.
To protect the hoses or cables from hot/cold cycles, heat protection materials are used. These can be laminated, e.g. with an aluminum foil, a reflective coating or a glass fabric. For lamination, mostly multi-component systems are used, which require a precoat, an additional bond and/or a backcoat. In some cases, systems are used that do not exhibit sufficient heat resistance at temperatures >300° C. Finally, paints, varnishes and coatings are known, but these are not applied to textile structures but to flat devices and thus lose flexibility and formability compared to textiles.
In DE 10 2006 048 912, a glass fabric is provided with a primer of polydimethylsiloxane. This precoat is aluminized by means of vapor deposition in a vacuum and a backcoat is applied to the product.
The product is sometimes used near turbolasers. However, the process discussed is on the one hand complex and expensive. On the other hand, the coatings peel off after a certain time when tested in a thermal oven at temperatures >300° C.
It is known from EP 1 522 534 that heat barriers can be formed from a silicone-containing base substrate, a bonding layer and a protective layer with aluminates. However, neither flexible substrates nor single-component coatings are disclosed.
From US 2010/0258371 a curable coating of polysilo-xane resin and reflective metal pigments is known. However, the coating is applied to metal substrates in the automotive industry, such as titanium, iron or aluminum. The coating of a fabric is not disclosed.
EP 1 429 104 discloses a heat camouflage sheet for covering heat sources against detection by thermal imaging cameras. The aluminum powder is included in a silicone elastomer and/or po-lyurethane based coating. The backing textile comprises glass filament. However, the heat camouflage fabric can be exposed to high temperatures of over 1000° C. only for periods of a few minutes and thus does not perform well enough for high temperature applications.
U.S. Pat. No. 6,872,440 discusses a composition consisting of a glass fiber substrate coated with a binder material (acrylic latex) and a filler material (such as fly ash) and additionally having a heat-reflective layer, for example of elastomer, aluminum fiber or ceramic. The coating is not only more expensive, but also limited in design (flat substrate) and heat resistance (88° C.) to the intended use in insulating roof construction.
It is therefore the task of the invention to overcome the disadvantages of the prior art. In particular, a flexible structure for insulation against heat and protection against fire and/or smoke should be provided. The structure should be resistant to high temperatures over long periods of time, in particular also be suitable for use in the automotive sector. The manufacturing should be simple and cost-efficient.
The invention relates to a textile heat, fire and/or smoke protection material comprising a textile sheet-like substrate coated or impregnated in whole or in part with a polymer composition, the polymer composition comprising a cross-linked polysiloxane and metal pigments.
By crosslinked polysiloxane in the sense of the present invention is meant a po-lysiloxane resulting from polymerization reactions, in particular condensation reactions, of silicone resin.
A silicone resin in the sense of this invention is curable to cross-linked polysi-loxane; in the silicone resin, some of the silicon atoms in the resin are already mutually bonded via oxygen atoms in branched structures before curing. The silicone resin is prepared from a precrosslinking reaction of oligosiloxanes containing units of the formula
—(R1R2Si—O)n—
wherein R1 and R2 are independently hydrogen, hydroxy, alkoxy, alkyl, aryl, vinyl groups and n is a natural number between 1 and 100, preferably between 5 and 60. Preferably, the oligosiloxanes have at least partially reactive groups, in particular hydrogen, hydroxy and/or alkoxy groups, at the positions R1, R2. Particularly preferably, the oligosiloxanes at the sites R1, R2 have, in addition to the hydrogen, hydroxy and/or alkoxy groups, partially organic side groups, in particular alkyl and/or aryl side groups, in particular methyl and/or phenyl side groups, or combinations thereof. The silicone resin may be in the form of an emulsion or dispersion.
The polymer composition comprising a crosslinked polysiloxane and metal pigments preferably contains 60 wt %, more preferably 70 wt % and most preferably 80 wt % of crosslinked polysiloxane.
A crosslinked polysiloxane according to the invention can have a high density; it can be hard but flexible. A crosslinked polysiloxane according to the invention has proven to be particularly resistant to heat compared to alternative polymers, for example silicone-based elastomers. Insulating materials based on crosslinked polysiloxane according to the invention are characterized by the fact that they are non-flammable even at temperatures above 800° C.
Known formulations from the heat protection sector, for example heat, fire and/or smoke protection materials based on polyurethane and/or polydimethylsiloxane, cannot withstand high temperatures over the long term, i.e. only for a few minutes. A textile structure coated according to the invention, on the other hand, shows a high heat-reflecting effect, even when exposed to temperatures >450° C. over a long period of time, up to 150 hours. The heat-reflecting effect was determined as heat delta according to the flame retardancy test standard DBL 5307-5.2 of the automotive industry (Mercedes-Benz AG). Here, the heat delta is the difference between a first temperature measured on a first side of a specimen facing a heat source and a second temperature measured on the opposite side of the specimen from the first side facing away from the heat source. The details of the test arrangement can be seen in the examples below.
When a textile fire and/or smoke protection material according to the invention is subjected to a flame retardancy test according to DBL 5307-5.2, the heat delta at temperatures up to 500° C. remains essentially constant for several hours. The coated structure does not lose significant amounts of the metal pigment even after several hours in the thermal oven. After 120 minutes at 800° C., the metal pigment continues to adhere to the textile. Flammability is not observed even at temperatures >800° C.
The textile according to the invention is particularly suitable for use as a smoke curtain according to the European standard for smoke and heat control DIN EN 12101. However, the textile is also suitable for use in the automotive industry. The textile shows very good results in media resistance tests according to ASTM D896-04, for example against gasoline, diesel, engine oil, brake fluid, brake cleaner and road salt solutions.
The crosslinked polysiloxane may be a crosslinked polysiloxane having pendant organic groups, wherein the pendant groups are independent of each other and are preferably selected from the group consisting of alkyl, aryl, hydrogen, hydroxy and alkoxy, and combinations thereof. Preferably, the crosslinked polysiloxane has at least in part side chains having phenyl groups, methyl groups and/or combinations thereof. The use of phenyl side groups has the advantage that a particularly high heat resistance of the coated or impregnated substrate can be achieved. In addition, phenyl groups have a higher compatibility with other resins and with fillers.
The polymer composition may contain at least one other polymer that is different from crosslinked polysiloxane. For example, in addition to crosslinked po-lysiloxane, the polymer composition may include at least one other polymer selected from the group consisting of polyacrylate, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, styrene-acrylate copolymer, ethylene-vinyl acetate copolymer, acrylate-urethane copolymer, polyurethane copolymer, vinyl chloride-ethylene, vinyl chloride-vinyl acetate, vinyl chloride-vinyl acetate-ethylene copolymer, and combinations thereof. The further polymer may have been provided in the form of a co-emulsion or co-dispersion.
The polymer composition comprising a crosslinked polysiloxane, at least one further polymer and metal pigments preferably contains between 5 and 30% by weight of the at least one further polymer, particularly preferably between 10 and 20% by weight.
A polymer composition containing, in addition to crosslinked polysiloxane, at least one further suitable polymer proves to be more elastic, more flexible, less brittle and thus more suitable for coating a textile substrate. The polymer composition comprising at least one further suitable polymer also adheres better to the substrate; it does not crumble off when the substrate is folded, gathered and creased. In addition, the further polymer can be selected in such a way that the aluminum pigments are better incorporated.
The textile, sheet substrate can be a woven, scrim or nonwoven fabric. The fabric, scrim or nonwoven can comprise fibers, in particular glass fibers or mineral fibers. Polyaramide fibers, e.g. Kevlar, or oxidized, thermally stabilized polyacrylonitrile (PAN) fibers, e.g. Panox®, are also conceivable.
Textile structures are flexible, foldable, shirred and compliant. They can be easily adapted to the needs of the application site, such as complex cable or hose structures. This avoids unnecessary material costs and prevents superfluous material from interfering, for example in the engine compartment. In fire protection installations, textile structures can be provided in a space-saving manner, for example as smoke protection curtains or heat protection shutters. Textile structures are particularly flexible compared with flat protective walls or insulation panels. At the same time, textile structures are more resistant than paints or coatings thanks to their woven, scrim or nonwoven structure. They offer an advantageous compromise between insulation substance and adaptability to the space conditions at the place of use.
The metallic pigments exhibit high heat stability. They are preferably aluminum pigments. Pigments made of chromium, silver or copper are also conceivable, in addition or as an alternative to aluminum pigments. Aluminum is preferred due to its suitable melting point and economic considerations.
The metal pigments can be platelet- or flake-shaped and/or have a maximum diameter in the area of 1 to 100 μm, preferably 5 to 45 μm, determinable by screen ana-lysis. Preferably, metal pigments of the non-leafing type are used, which are uniformly distributed in the film matrix. Preferably, the metal pigments are used in the form of a VOC-free paste for aqueous systems.
The textile, flat substrate, is coated or fully or partially impregnated with a polymer composition, whereby this polymer composition preferably contains metal pigments in a minimum proportion of the polymer composition of 7% by weight, preferably between 10 and 25% by weight, particularly preferably between 12 and 20% by weight. A relatively high proportion of metal pigments can better ensure the heat resistance of the heat, fire and smoke protection material.
The textile heat, fire and/or smoke protection material may be such that the substrate is coated on one side only. Despite the single coating, the heat, fire and/or smoke protection material has the required heat and fire resistance.
The invention further relates to a method for producing a textile heat, fire and/or smoke protection material, preferably a textile heat, fire and/or smoke protection material as described above, comprising the steps of:
As described above, a fabric, scrim or nonwoven can serve as a textile, flat substrate, optionally made of glass fibers or mineral fibers.
For the purposes of this invention, dispersion or emulsion means that, in addition to the dispersed metal pigments, the other additives, in particular silicone resin, other polymers, fillers, additives for suppressing flammability, may be present in a dispersed and/or emulsified state.
Preferably, the silicone resin can be prepared from oligosiloxanes with side groups and chain lengths as defined above. Particularly preferably, the silicone resin has, in addition to the hydrogen, hydroxy and/or alkoxy groups, side chains with methyl and/or phenyl groups and combinations thereof, since such silicone resins react to form particularly heat-resistant coatings, as described above. The silicone resin emulsion can be a methyl/phenyl silicone resin emulsion (Me/Ph-Si resin)
Hydroxy or alkoxy groups as side group of the siloxane main chains of the silicone resin lead to better curing. During curing, condensation reactions between polysiloxane segments are favored. However, reactions can also occur between silicone resin on the one hand and fillers, other resins, further monomeric or prepolymeric components in co-dispersion or co-emulsion, other additives and/or substrates on the other hand.
It is preferred that the dispersion or emulsion is applied to only one upper side of the textile sheet substrate. Even with a single coating, the advantageous properties as described above are achieved, in particular the single-coated substrate passes the flame retardancy test standard DBL 5307 and complies with the smoke and heat retention standard according to DIN EN 12101. No further coatings are required, which makes the process time-saving and efficient.
When applied, the silicone resin is in the form of a dispersion or emulsion, preferably in the form of an aqueous dispersion. The silicone resin dispersion can be in the form of a one-component system. Such a one-component system can be easily crosslinked under heat input. Handling of such a one-component system is relatively simple. In addition, material costs can be saved compared to multi-component systems.
The dispersion or emulsion can contain a co-dispersion or co-emulsion. In addition to the silicone resin, a polymer other than polysiloxane is present in the dispersion or emulsion, preferably a co-dispersion comprising polyacrylates, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, styrene-acrylate copolymers, ethylene-vinyl acetate copolymers, acrylate-urethane copolymers, polyurethane copolymers, vinyl chloride-ethylene, vinyl chloride-vinyl acetate, vinyl chloride-vinyl acetate-ethylene copolymers and/or combinations thereof.
After curing, the dispersion or emulsion also serves as a binder in addition to its main function as an insulator and fire/smoke protection. A binder can, for example, strengthen or support the fabric at the point of warp/weft intersection.
The dispersion or emulsion may be water-based. By “was-ser-based” it is meant that the continuous phase is water. A water-based dispersion or emulsion can penetrate well into the substrate, is easy to handle, and is gentle to health and the environment.
The hydroxyl and alkoxy groups of the silicone resin can react together after a condensation reaction, resulting in post-crosslinking of the silicone resin and thus curing. The condensation reaction can be accelerated by adding a tin-based catalyst, for example dibutyltin dilaurate. The post-crosslinking is preferably carried out with the addition of heat, preferably in a temperature range between 100 and 300° C., particularly preferably between 120 and 250° C. and most preferably between 150 and 230° C. Such post-crosslinking, in particular post-crosslinking of the silicone resin, results in particularly high heat resistance of the coating.
Preferably, after application of the dispersion or emulsion to at least part of the substrate and before curing of the applied dispersion or emulsion to form a coating, another intermediate step is carried out, namely drying of the dispersion or emulsion at 25 to 75° C., preferably at 40 to 60° C. However, the drying and curing of the dispersion or emulsion may also be carried out during a single temperature treatment, in which case a temperature gradient may be applied, for example starting at 50° C. and ending at 230° C.
The dispersion or emulsion may contain organic solvents. However, the solvent content should not exceed 6% by weight. A low solvent content helps to protect the environment and also increases occupational safety.
Composites coated with a dispersion or emulsion according to the invention retain their original properties, such as flexibility, even after drying. There is no stiffening of the material due to the coating.
The components of the dispersion or emulsion may be premixed. The dispersion or emulsion according to the invention is doctored directly onto the textile substrate. A preprimer is not necessary. A backcoat is also not necessary. A single coating coat can be used. However, the invention also encompasses processes in which several, in particular two to five, strokes are used.
The dispersion or emulsion can comprise further components. For example, further pigments and/or fillers may be added to the composition for high temperature performance, viscosity adjustment and improved coating.
The dispersion or emulsion may also contain thickeners, preferably inorganic and particularly preferably highly dispersed silica, without deterioration of heat resistance compared to organic thickeners. Thickening agents can simplify the applicability of the dispersion or emulsion.
Other additives may include neutralizing agents, dispersing agents, rheological aids, thickening agents, defoaming agents such as biocides, or wetting agents.
The dispersion or emulsion preferably has a pH value between 6 and 10 at the time of application.
The pH value serves the formulation and compatibility of the components. Furthermore, the pH of the dispersion or emulsion should be chosen so that it does not attack the metal particles.
The dispersion or emulsion can be applied over a wide area. The application weight is preferably at least 70 g/m2. The dispersion or emulsion can then be dried at a defined temperature between room temperature and 150° C., preferably from 30° C. to 100° C. and particularly preferably from 50° C. to 80° C.
The dispersion or emulsion can be applied by roller, stencil, squeegee or spraying.
The advantage of the different application methods is that the silicone resin can be applied to different substrates and according to the intended use.
The solids content of the dispersion or emulsion is preferably above 50 percent by weight and particularly preferably between 60 and 80 percent by weight.
In aqueous systems, a high solids content has the advantage that faster drying is possible or less energy is required for drying. The solids content may result from a high content of silicone resin, fillers and/or insoluble additives. However, the solids content should not exceed 50 wt. %.
Additives can be added to suppress the flammability of the coated substrate.
The dispersion or emulsion can have a viscosity of 500 to 40,000 mPa·s, preferably a viscosity of 1,000 to 30,000 mPa·s and most preferably a viscosity of 2,000 to 10,000 mPa·s.
The values for viscosity were determined according to the Brookfield method using a Brookfield DVI+. Measurements for viscosities from 500 to 40,000 mPa·s were made at 23° C. with a spindle 4 at 20 rpm.
A system according to the invention can be of low viscosity so that the textile structure is well wetted. Due to the lower viscosity of the dispersion or emulsion compared to conventional 100% silicone resin, the dispersion or emulsion can penetrate the glass fabric very well. Warp/weft intersections are significantly strengthened.
Textile heat, fire and/or smoke protection materials are particularly suitable for components in the automotive industry, especially for the engine and exhaust area, but also for structural fire protection.
The invention therefore relates to the use of a textile heat, fire and/or smoke protection material as described above in the construction sector and as a heat protector in a vehicle. Components with such heat, fire and smoke protection materials can contribute significantly to safety. On the one hand, the components are more durable than previously used components due to the material properties, and on the other hand, the spread of fires and damage to buildings/engines can be significantly limited due to the advantageous properties.
The following example is for illustrative purposes and is not intended to limit the scope of the invention.
An isoGLAS filament fabric (GIVIDI) with a weight of 420 g/m2 and a thickness of 0.5 mm was used as the textile, flat substrate. Table 1 lists the starting raw materials of two exemplary aqueous coatings.
The examples according to the invention are hereinafter referred to as test specimen 1 (PK1) and test specimen 2 (PK2).
For comparison, the following four samples were used, which will be referred to as comparison samples (VM) in the following:
Production of the Test Specimens
The isoGLAS filament fabric (approx. 60×30 cm) was coated on one side with the respective aqueous formulation for PK1 and PK2 (approx. 80 g/m2, dry). Subsequently, the sample was oven dried at 50° C. for 20 min and activated at 230° C. for 20 min. The sample sizes required for the test methods (to be taken from the method specification in each case) were cut to size. Positioning of the samples during one day.
Preparation of the Reference Samples
For VM1, an isoGLAS filament fabric with a weight of 420 g/m2 and a thickness of 0.5 mm (approx. 60×30 cm) was coated on one side with an aqueous formulation (approx. 80 g/m2, dry). The aqueous formulation consisted of 99 wt % aqueous Me/Ph-Si resin emulsion (50% solids, Silres EP 52 M) and 1 wt % polyacrylate-based thickener (BorchiGel A LA). The sample was oven dried at 50° C. for 20 min and activated at 230° C. for 20 min. The sample sizes required for the test methods were cut to size. Storage of the samples during one day.
For VM2 and VM3, commercially available products from the automotive and heat protection sectors were purchased (details above).
For VM4, an isoGLAS filament fabric (GIVIDI) with a weight of 420 g/m2 and a thickness of 0.5 mm (approx. 60×30 cm) was provided. In addition, an aqueous formulation was provided consisting of 35 wt. % heat-sealable adhesive based on aqueous ethylene-acrylic acid copolymer dispersion (nolax S35.3110), 52 wt. % aqueous Me/Ph-Si resin emulsion (50% solids content, Sil-res MPF 52 M from Wacker Silicone), 13 wt. % calcined kaolin (Kamin 70), 0.02 wt. % defoamer (Agitan 701, Munzing) and 0.5 wt. % dispersant. The aqueous formulation was applied to the matte side of a 25 m thick aluminum foil (approx. 70 g/m2). Directly into the still wet film, the isoGLAS filament fabric (a piece of approx. 20×30 cm) was now placed lengthwise (with the reverse side facing down) and evenly pressed on. The sample was dried in the oven at 50° C. for 20 min and activated at 230° C. for 20 min. The sample sizes required for the test methods were cut. Storage of the samples during one day.
Heat Resistance Infrared Steel (Standard DBL5307-5.2)
To test the heat resistance, the test specimens (including reference specimens) were cut to a size of 25×25 cm. The test specimens were sprayed in the center on a size of approx. 2.5×2.5 cm with a heat-resistant paint (exhaust paint).
The test specimens were placed on a stainless tungsten wire mesh. An infrared source was placed below the test specimen at a distance of 20 mm from the grate. A Krelus quartz radiator with a nominal power of 2 KW was used as the infrared radiator.
The IR illuminator was aligned with the specimen. The temperature of the IR emitter was measured by a first pyrometer located in the emitter and set to 459° C. A second pyrometer was placed on the side of the specimen facing away from the IR emitter, at a distance of 2 cm from the specimen. A second pyrometer was placed on the side of the specimen facing away from the IR emitter, at a distance of 2 cm from the specimen. The specimen was irradiated at a temperature of 459° C. for 2 hours. The temperature differences between the first and the second pyrometer (heat delta) at the beginning of the two-hour irradiation (Δ1) and at the end of the two-hour irradiation (Δ2) were determined.
Burn Test (Standard DBL 5307-5.3).
The firing test was carried out using a BBW type furnace from Wazau, Berlin. The test specimens (including comparison samples) were cut to a size of 56 cm×16 cm and fixed on a support. The Bunsen burner was ignited and allowed to burn for at least 2 min before starting the test. The burner was then directed onto the specimen at a distance of 2 cm from the test piece. The specimen was flamed horizontally for 5 seconds (ignition test) and horizontally for 15 seconds (flammability test).
Heat Resistance Thermal Oven
The respective test specimens (incl. reference samples) were stored for 1 h at 400° C. in a high-temperature furnace, standing on a rack.
Results
Table 1 lists the test results of the individual formulations in the heat resistance test (infrared), the burning test and the heat resistance test (thermal oven).
The tests show that the test specimens coated with polymer compositions according to the invention perform very well in all three tests. In the IR test, samples VM2 and VM4 also showed similarly good shielding against the beam temperature of 459° C. The samples VM2 and VM4, however, disintegrated after 15 seconds in the burn test and showed very good shielding. However, sample VM2 disintegrated after 15 seconds in the burn test and showed a more pronounced decrease in shielding effectiveness during the two-hour test under IR radiation. Sample VM4 shows good heat and fire resistance, but obtains it by caschie-ring with an aluminum foil, losing the advantages of the textile structure (flexibility, foldability, gatherability) and the efficiency of the manufacturing process.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18215385.8 | Dec 2018 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/083278 | 12/2/2019 | WO | 00 |
