Binding agent for mineral wool and mineral wool product bonded therewith

Abstract: The present invention relates to a binding agent for mineral wool, comprising at least one thermoplastic homo- or copolymer, that is cross-linkable with phenolic resin, at least one phenolic resin and at least one flameproofing agent. Optionally, a part of the flameproofing agent may be replaced by metal oxide nanogels and/or glass powder. Using such binding agents, even low melting fibers can be processed into mineral wool products, which, for example as fire-protection elements, show a hold-up time of up to 90 minutes, according to DIN 4102, part 5.

Description: The present invention relates to a binding agent for mineral wool according to claim 1 and to a bonded mineral wool product according to claim 13. For binding mineral wool, in particular rock wool and glass wool, it is known since long to apply a phenol-formaldehyde resin based binding agent onto the fibers, preferably in the dropping pipe subsequent to the defiberizing machine. Hereby the prior art binding agent is preferably sprayed onto the fibers as an aqueous solution or a dispersion, respectively, whereby the phenol-formaldehyde resin is then further polymerized due to still relatively high temperatures of the fibers on the fiber surface and links the single fibers with each other by the polymerization process, in particular at crossing points of fibers, because the fibers lying over each other on a crossing point are quasi embedded there by solidified resin droplets and, therefore, hinder or prevent the displaceability of the single fibers among one another. As is known, mineral wool products are used as a protection against heat, coldness, sound or fire, and are, for the predominant part, classified as nonflammable according to DIN 4102. For this purpose the level of organic - i.e. combustible or smoulderable - material, therefore, needs to be kept at a minimum. Another criterion along with the nonflammability is the mineral wool products' resistance to fire stress, which is of special importance for use of these products as a fire-protection element. As is known, the fire resistance is defined by the period of time by which, upon a particular rise of the temperature on one side of the fire-protection element, e.g. a fire-proof door, the other side of the fire-protection element remains below a defined limit of temperature, for example 180°C. The hold-up time in minutes of the fire-protection element until reaching the temperature limit on the cold side results in the fire resistance class, whereby according to DIN 4102, part 5, the classification for example of fire resistance class T 30 means a hold-up time of 30 minutes, T 60 a hold-up time of 60 minutes, etc. In the past layer structures were used to obtain high fire-protection levels, such as for example in the DE-A 38 24 598, which uses as a fire-protection layer a mixture of a dehydrating hydroxide, such as aluminium hydroxide, and waterglass or silica sol, which is arranged as connective layer between two bodies of bonded mineral wool. The german utility model DE-U 295 07 498 discloses a teaching extending the above, which discloses a fire-protection element with a layer structure, which comprises a center layer of inorganic material, which releases water upon influence of temperature and remains dimensionally stable and is arranged between the outer layers of bonded mineral wool as a prefabricated half-stuff. EP-A-748 777, DE-A-4 024 727 and US-A-4 073 849 describe binding agents for fibres comprising a thermoplastic resin and a phenotic resin. EP-A-668 391 and EP-A-669 418 describe binding agents for glass fibres comprising a polymer mixture and a flame proofing agent. Said prior art has been well approved, but naturally increased layer thicknesses are required, to obtain satisfactory fire resistance levels. If the fire-protection layers cited in the prior art were omitted, then the risk will occur that the mineral wool of the fire-protection element used would become sintered at possible high fire temperatures, whereby-the fire-protection element loses its efficiency relatively fast. On the other hand, it depends on the nature of the used mineral wool by which temperatures sintering of the mineral wool occurs. Hereby especially a mineral wool is of great interest which shows a very low biological durability. The judgement of such mineral wools is defined in the prescriptions of the TRGS 905, which has been. published by the Bundesministerium für Arbeit. Such mineral fibers may become sintered for example at temperatures of above about 700°C. Therefore, it is the object of the present invention to treat lower melting wool by simple means in such a way, in particular compared to basaltic mineral wool, that insulating materials and fire-protection elements, respectively, are produceable, the fire-resistance of which meets the requirements according to DIN 4102, part 5. The object above is solved by a binding agent according to claim 1 as well as by a mineral wool product according to claim 13. As at least one thermoplastic homo- or copolymer, that is cross-linkable with phenolic resin, phenolic resin as well as at least one flameproofing agent are incorporated in the binding agent according to the invention, high fire-resistance levels reveal which correspond at least to those, which were obtained with conventional fire-protection elements made of basalt wool. Surprisingly it became apparent that, although organic substances, namely homo- or copolymers cross-linkable with phenolic resin, are added to the binding agent, whereby one skilled in the art would rather expect a deterioration of the fire-protecting behaviour, with for example plates of mineral wool bonded with the binding agent according to the invention having a melting point < 1000°C, e.g. a glass or rock wool having KI ≥ 40 according to TRGS 905, temperatures above 1000°C became possible without sintering or melting the fibers as would have been expected. At present, the mechanism hereof is not yet clear, but it seems, however, without being limited thereto, that decomposition products of the thermoplast cross-linked with the phenolic resin and the flameproofing agent, so-called crack-products, react with the fibers at high temperatures above 500°C, whereby it could be imaginable that carbon is incorporated in or attached to the fibers such that the fibers undergo a chemical conversion. If plates of mineral wool which are bonded with the binding agent according to the invention are produced, serial experiments for classifying the fire-resistance time according to DIN 4102, part 5, reveal that surprisingly high hold-up times of up to 90 minutes are achieved. Important herewith is, that a thermoplastic homo- or copolymer cross-linkable with phenolic resin is used, which then cross-link with eachother on the still hot fibers by being sprayed onto the fibers in the dropping pipe subsequent to the fiber insulation, such that a mixed resin comprising phenolic resin and thermoplastic polymer evolves. Thus, a mixture consisting of thermoplastic homo- or copolymer, cross-linkable with phenolic resin and the phenolic resin, has also importance per se, although it is not part of the present invention, because such a binding agent also exhibits increased temperature resistance without a flameproofing agent and, apart from that, also results in improved properties of the mineral wool, because the brittleness of the total mineral wool product is reduced and, thus, an improved fiber breakage strength in the individual mineral wool products is provided. Particularly suitable as thermoplastic homo- or copolymer cross-linkable with a phenolic resin those according to claim 2 have been approved; here in particular, acrylic resins, polyvinyl acetates, polyurethanes as well as their homo- and copolymers, but especially copolymers based on acrylic acid esters also using acrylonitriles, are excellently suited for the purposes of the present invention. Thus, according to claims 3 and 4, phenolic resins, i.e. the conventionally known phenol-formaldehyde condensation products as well as phenol-urea condensation products or phenol-formaldehyde-urea condensation products, may be used as suitable phenolic resins for the purposes of the present invention. The usual flameproofing agents known in the prior art, are preferably used as flameproofing agent according to claim 5. These have been very well approved in practice. Furthermore, additives according to claim 6 may of course be added depending on the intended application of the mineral wool product to be produced. Particularly effective additives for increasing the temperature resistance of bonded fibers, which are free from suspicion of causing cancer according to TRGS 905, e.g. ≥ KI 40, have been shown to be the so-called fiber stabilizers. The known stabilizers china clay and silica sol stabilize the mineral wool fibers and prevent excess shrinkage at high temperatures but, surprisingly, in context with the present invention it was found, that a considerable increased stabilization of the fibers is provided, if metal oxide nanogels and/or ceramic and glass powder, respectively, are added to the binding agent. Due to interaction of the organic substances contained in the binding agent according to the present invention, in particular the thermoplastic polymers, the fibers of rock wool, for example, crystallize at temperatures above about 700°C. The fibers maintain their shape essentially, their surface appears somewhat roughened, and they show themselves as being crystalline in a polarization microsope. This could be a mechanistic explanation for mineral wool KI-40, which is bonded with a stabilizer-containing binding agent, endures temperatures of up to about 1000°C without being sintered or even being melted. It was shown, that stabilizers comprising colloidal metal oxides, especially nanogels and/or ceramic and / or glass particles according to claims 7 to 9, which are added to the binding agent, are particularly advantageous. A further benefit of using fiber-stabilizers according to the claims 7 to 9 is, that the higher the proportion of the stabilizers is the less flameproofing agents are required to obtain the same temperature resistance and fire strength of bound mineral wool products. A preferred embodiment of the present invention uses at least 10 % of phenolic resin according to claim 10, relative to the dry mass of the binding agent. The subclaims 11 and 12 represent preferred quantitative compositions of the binding agent according to the present invention. The subclaims 14 to 16 represent preferred embodiments of the mineral wool product of the present invention according to claim 13. Further benefits and features follow from the descripiton of embodiments of the present invention. Example 1 The following components were mixed for the manufacture of a binding agent according to the present invention: 165 parts water 50 parts ammonium polyphosphate flameproofing agent 60 parts aluminium hydroxide flameproofing agent 60 parts melamine as flameproofing agent and 60 parts polyvinyl acetate The pH was about 7.4 and the solids content of the mixture of this so-called flameproofing compound was about 51 %. This blend was admixed to the binding agent as follows: 100 parts 50 % phenolic resin 201 parts of the above flameproofing compound 20 parts 40 % silica sol The so obtained binding agent according to the present invention was still further diluted, if required, and sprayed onto KI 40 fibers in the dropping pipe in a known manner, whereby a concentration of about 0.1 % to 10 % binding agent in the mineral wool product, relative to the fiber mass, was obtained. If such bonded mineral fibers were processed to a mineral wool plate and this plate was tested in a fire-resistance test according to DIN 4102, part 5, hold-up times of 60 to 90 minutes were obtained. It was found, that using the binding agent according to the invention in the above exemplified embodiment mineral wool products were obtained, which endured 1000°C without being sintered. After cooling, the mineral wool product merely was of a blackish colour, which might suggest the already mentioned importance of the carbon. Example 2 For production of a further binding agent according to the present invention at first the following components were blended to a flameproofing compound: 60 parts water 65 parts of an ammonium-polyphosphate flameproofing agent 50 parts of a copolymer based on acrylic acid ester also using acrylonitrile as a thermoplastic polymer cross-linkable with phenolic resin, and then 175 parts of said flameproofing compound were mixed with 50 parts phenolic resin such that a solids content of about 40 % was provided. After that, this blend was sprayed in a known manner onto the KI 40 fibers in the dropping pipe. Mineral wool plates to be used as fire-protection elements for fireproof doors have also shown in the fire-resistance test to have a hold-up time of at least 90 minutes according to DIN 4102, part 5. Example 3 Two binding agent dispersions A and B were produced, the quantitative composition of which is shown in table 1. Component Binding agent A Binding agent B %, based on dry mass %, based on dry mass Ammonium phosphate 26.8 16.8 Urea 12.8 7.7 Dicyanodiamide 6.9 5.7 Pentaerythritol 2.1 1.7 Polyvinyl acetate 22.9 22.9 Phenolic resin 28.5 28.5 Glass, about 5 µm grain size 16.7 Although binding agent B (in comparison with A) has reduced levels of the flame proofing agents ammonium phosphate, urea, dicyanodiamide and pentaerythritol, mineral wool plates bound therewith, which are to be used as fire-protection elements in fireproof doors, exhibit a hold-up time of at least 90 minutes according to DIN 4102, part 5, in the fire-resistance test. The glass in binding agent B may be replaced by colloidal metal oxides, so-called metal oxide-nanogels, e.g. acetate-stabilized ZrO 2 , CeO 2 , Al 2 O 3 , Y 2 O 3 , SnO 2 , B 2 O 3 , BeO, MgO, ZnO, SiO 2 or TiO 2 . Other counter-ions than acetate, such as nitrate, can also be used. Using the binding agent according to the invention, glassy mineral fibers, for example KI 40 fibers, can thus be processed to fire-protection elements for the first time, which can endure temperatures up to more than 1000°C without being softened or sintered or melted. Thus, such products are capable of replacing fire-protection elements consisting of conventional basalt wool.

Claims: A binding agent for mineral wool, containing: at least one thermoplastic homo- or copolymer cross-linkable with phenolic resin; at least one phenolic resin; and at least one flameproofing agent. A binding agent according to claim 1, characterized in that the thermoplastic polymers are selected from the group consisting of: acrylic resins, polyvinyl acetates, polyurethanes as well homo- and copolymers thereof, in particular copolymers based on acrylic acid esters also using acrylonitriles. A binding agent according to claim 1 or 2, characterized in that the phenolic resins are phenol-formaldehyde condensation products. A binding agent according to claim 1 or 2, characterized in that the phenolic resins are phenol-formaldehyde-urea condensation products. A binding agent according to any one of claims 1 to 4, characterized in that the flameproofing agent is selected from the group consisting of: hydroxides, that are water-releasing at increased temperature, in particular aluminium hydroxide, substances, which are halogen-releasing at increased temperature, in particular halogenated paraffins, oxygen-excluding substances, phosphines, phosphates, in particular ammonium phosphates, especially ammonium polyphosphates, phosphoric acid esters, antimony oxides and/or antimony salts; melamine; and mixtures thereof. A binding agent according to any one of claims 1 to 5, characterized by containing additives, which are selected from the group consisting of: stabilizers, in particular silica sol, clays, especially kaolinites, montmorillonites, china clay and/or bentonite; thixotropic agents, particularly polysaccharides such as starch, potato starch, polysaccharide derivates such as methyl cellulose; pigment dispersers; and mixtures thereof. A binding agent according to claim 6, characterized in that the stabilizers are selected from the group consisting of: oxides, in particular colloidal oxides, of aluminium, cerium, silicon, zinc, antimony, tin, yttrium, zirconium, titanium, beryllium, magnesium, boron, especially nanogels of said metal oxides, preferably acetate-stabilized metal oxid nanogels, as well as ceramic powders, in particular glass powder, preferably glass powder having an average particle diameter ranging from about 1 µm to 50 µm, in particular ranging from about 5 µm to 30 µm, especially preferred about 5 µm, and mixtures thereof. A binding agent according to claim 7, characterized in that the metal oxide nanogels are selected from the group consisting of: CeO 2 , Al 2 O 3 ,Y 2 O 3 , ZrO 2 , SnO 2 , B 2 O 3 , BeO, MgO, ZnO, SiO 2 and TiO 2 . A binding agent according to any one of claims 7 or 8, characterized in that the average particle diameter of the nanogels is about 1 nm to 150 µm, in particular about 5 nm to 1 µm, preferably about 5 nm to 200 nm, especially preferred about 5 nm to 100 nm, particularly preferred about 5 nm to 50 nm, preferably about 5 nm to 20 nm, in particular preferred about 5 nm to 10 nm. A binding agent according to any one of claims 1 to 9, characterized by containing at least about 10 % of phenolic resin, relative to the dry mass of the binding agent. A binding agent according to any one of claims 1 to 10, characterized by containing, relative to its dry mass: about 2.5 to 70 % thermoplastic polymer, about 10 to 95 % phenolic resin, about 2.5 to 70 % flameproofing agent, and about 1 to 50 % stabilizers, particularly metal oxide nanogels and/or glass particles; in particular about 2.5 to 60 % thermoplastic polymer, about 10 to 80 % phenolic resin, about 2.5 to 50 % flameproofing agent, and about 5 to 30 % stabilizers, particularly metal oxide nanogels and/or glass particles; preferably about 10 to 60 % thermoplastic polymer, about 10 to 70 % phenolic resin, about 10 to 60 % flameproofing agent, and about 5 to 20 % stabilizers, particularly metal oxide nanogels and/or glass particles. A binding agent according to any one of claims 1 to 11, characterized by containing, relative to its dry mass: about 25 %, preferably about 23 % thermoplastic polymer, about 30 %, preferably about 29 % phenolic resin, and about 45 %, preferably about 48 % flameproofing agent. A bound mineral wool product, characterized by being bonded with the binding agent according to one of claims 1 to 12. A mineral wool product according to claim 13, characterized in comprising rock wool or glass wool, the fibers thereof complying with the KI 40 criteria. A mineral wool product according to claim 13 or 14, characterized by being provided as plate, mat or felt. A mineral wool product according to any one of claims 13 to 15, characterized in being provided as a plate of KI 40 mineral wool and having a fire resistance time according to DIN 4102, part 5, of at least 60 minutes, preferably 90 minutes.

Inventors: BIHY LOTHAR, KUMMERMEHR HANS, BIHY, LOTHAR, KUMMERMEHR, HANS
Applicants: SAINT GOBAIN ISOVER, SAINT-GOBAIN ISOVER
Application year: 1998
Main classification: C03C25
IPC codes: C08K13, C03C25, C09J161, C09K21, C08K5, C04B20, C04B26