EP2403913A1

EP2403913A1 - Coating composition for foam particles

Info

Publication number: EP2403913A1
Application number: EP10706263A
Authority: EP
Inventors: Benjamin Nehls; Klaus Hahn; Bernhard Schmied; Michael Riethues; Andreas Keller; Murray Orpin
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2009-03-06
Filing date: 2010-03-04
Publication date: 2012-01-11
Also published as: WO2010100230A1

Abstract

The invention relates to a coating composition containing at least one cross-linking agent and a hydrophobically acting amount of a compound containing silicon, to foam particles coated therewith, to molded foam bodies produced therefrom, and to the use thereof.

Description

Coating composition for foam particles

description

The invention relates to a coating composition, thus coated foam particles, as well as molded foam articles produced therefrom and their use.

Particulate foams are usually obtained by sintering foam particles, for example prefoamed expandable polystyrene particles (EPS) or expanded polypropylene particles (EPP) in closed forms by means of steam.

Flame-retardant polystyrene foams are generally equipped with halogen-containing flame retardants, such as hexabromocyclododecane (HBCD). However, the approval as an insulating material in the construction sector is limited to certain applications. One of the reasons for this is the melting and dripping of the polymer matrix in case of fire. In addition, the halogen-containing flame retardants can not be used without restriction in terms of their toxicological properties.

WO 00/050500 A1 describes flameproofed foams of prefoamed polystyrene particles which are mixed together with an aqueous sodium silicate solution and a latex of a high molecular weight vinyl acetate copolymer, poured into a mold and dried in air while shaking. This results in only a loose bed of polystyrene particles that are glued together at a few points and therefore have only insufficient mechanical strength.

WO 2005/105404 A1 describes an energy-saving process for the production of foam moldings, in which the prefoamed foam particles are coated with a resin solution which has a lower softening temperature than the expandable polymer. The coated foam particles are then sealed in a mold using external pressure or by post-expansion of the foam particles with hot steam.

WO 2007/023089 A1 describes a process for producing foam moldings from prefoamed foam particles which have a polymer coating. The preferred polymer coating used is a mixture of a waterglass solution, waterglass powder and a polymer dispersion. If desired, hydraulic binders based on cement or metal salt hydrates, for example aluminum hydroxide, may be added to the polymer coating. A similar process is described in WO 2008/0437 A1, according to which the coated foam particles can be dried and then processed into a fire and heat-resistant foam moldings.

WO 00/52104 A1 relates to a fire protection coating which forms an insulating layer in the event of fire and based on foam-forming and carbon-forming substances in the event of fire, which contains melamine polyphosphate as the blowing agent. Information on water resistance is not included.

WO 2008/043700 A1 relates to a process for producing coated foam particles with a water-insoluble polymer film. The non-prepublished patent application PCT / EP 2008/06136 relates to a coating composition for foam particles containing a clay mineral, an alkali metal silicate and a film-forming polymer.

Hydraulic binders such as cement bind in aqueous slurry with carbon dioxide even at room temperature. As a result, embrittlement of the foam plate occur. In addition, keep the foam plates produced according to the cited prior art temperatures of about 800 ⁰ C in case of fire and break down in case of fire.

The known coating compositions are in need of improvement in view of the simultaneous improvement of flame / heat resistance and their water resistance in water exposure or in increased humidity. Many known materials lose their original shape after a short time in the case of direct water exposure. In addition, if a standard fire test is performed, such materials often completely lose their structural integrity. As a rule, this leaves powdery mixtures which no longer meet the technical requirements.

The object of the present invention was to provide coating compositions for foam particles, coated foam particles and foam moldings which have both adequate flame / heat resistance and adequate water resistance with prolonged water exposure, in particular in the case of so-called durability tests, in which a building material increased Humidity (near 100%) and temperatures around 65 ⁰ C is exposed.

The invention relates to a coating composition comprising:

a) 20 to 70 parts by weight of a clay mineral b) 20 to 70 parts by weight of an alkali metal silicate c) 1 to 30 parts by weight of a film-forming polymer d) 1 to 20 parts by weight of a crosslinking agent, in particular based on a phosphate or a melamine compound.

The coating composition is preferably used as an aqueous dispersion, wherein the water content including the water bound, for example, as water of crystallization is preferably in the range of 10 to 40, in particular 15 to 30 wt .-% based on the total aqueous dispersion.

In a particularly preferred embodiment, furthermore, e) contains a hydrophobizing amount of a silicon-containing compound, in particular a silicone, in particular 0.2 to 5 parts by weight. In a particularly preferred embodiment, this is a silicone emulsion with silicone particles of different sizes. As a result, a particularly good penetration in porous materials can be achieved.

A preferred coating composition contains

a) 30 to 50 parts by weight of a clay mineral b) 30 to 50 parts by weight of an alkali silicate c) 5 to 20 parts by weight of a film-forming polymer d) 5 to 10 parts by weight of a phosphate or a melamine e) 0.5 to 3 parts by weight of a silicone f) 5 to 40 parts by weight of an infrared absorbing pigment.

The amounts given above each refer to solids based on solids of the coating composition. The components a) to e) or a) to f) preferably add up to 100% by weight.

Preferably, the weight ratio of clay mineral to alkali silicate in the coating composition is in the range of 1: 2 to 2: 1.

Suitable clay minerals a) are in particular allophan Al ₂ [SiO ₅ ] SO ₃ ^.n H ₂ O, kaolinite Al ₄ I (OH) ₈ ISi ₄ OiO], Halloysite Al ₄ E (OH) ₈ ISi ₄ Oi ₀ ] ^■ 2 H ₂ O, montmorillonite (smectite) (Al, Mg, Fe) ₂ [(OH ₂ | (Si, Al) ₄ Oi ₀ ] ^■ Na _o , ₃₃ (H ₂ _O ) ₄ , vermiculite

Kaolin is particularly preferably used ^■ Mg ₀₃₅ (H ₂ O) ₄ or mixtures thereof containing minerals | Mg ₂ (Al, Fe, Mg) [(Si, Al) ₄ Oi ₀ (OH _2].. The alkali silicate b) used is preferably a water-soluble alkali metal silicate with the composition M ₂ O (SiO ₂ ) _n with M = sodium or potassium and n = 1 to 4 or mixtures thereof.

In general, the coating composition contains as the film-forming polymer e) an uncrosslinked polymer which has one or more glass transition temperatures in the range of -60 ° to + 100 ⁰ C. Preferably, the glass transition temperatures of the dried polymer film are in the range from -30 ° to + 80 ⁰ C, more preferably in the range of -10 ° to + 60 ⁰ C. The glass transition temperature can by means of differential scanning calorimetry (DSC, in accordance with ISO 1 1357-2, Heating rate 20 K / min) can be determined. The molecular weight of the polymer film, determined by gel permeation chromatography (GPC), is preferably below 400,000 g / mol.

The coating composition preferably comprises as film-forming polymer an emulsion polymer of ethylenically unsaturated monomers such as vinylaromatic monomers, such as α-methylstyrene, p-methylstyrene, ethylstyrene, tert-butylstyrene, vinylstyrene, vinyltoluene, 1,2-diphenylethylene, 1,1-diphenylethylene, alkenes such as ethylene or propylene, dienes such as 1, 3-butadiene, 1, 3-pentadiene, 1, 3-hexadiene, 2,3-dimethylbutadiene, isoprene, piperylene or isoprene, α, ß-unsaturated carboxylic acids such as acrylic acid and methacrylic acid, esters thereof, in particular alkyl esters, such as C 1-10 -alkyl esters of acrylic acid, in particular the butyl esters, preferably n-butyl acrylate, and the C 1-10 -alkyl esters of methacrylic acid, in particular methyl methacrylate (MMA), or carboxylic acid amides, for example, acrylamide and methacrylamide.

The polymers may optionally contain from 1 to 5% by weight of comonomers, such as (meth) acrylonitrile, (meth) acrylamide, ureido (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, Acrylamidepropanesulfonic acid, methylolacrylamide or the sodium salt of vinylsulfonic acid.

More preferably, the polymer is verfilmende from one or more of the monomers styrene, butadiene, acrylic acid, methacrylic acid, d- ₄ alkyl acrylates, acrylates d- ₄ -Alkylmeth-, acrylamide, methacrylamide and constructed methylolacrylic.

Suitable polymers c) are obtainable, for example, by free-radical emulsion polymerization of ethylenically unsaturated monomers, such as styrene, acrylates or methacrylates, as described in WO 00/50480.

The polymers c) are prepared in a manner known per se, for example by emulsion, suspension or dispersion polymerization, preferably in the aqueous phase. The polymer can also be prepared by solution or bulk polymerization, optionally divided and the polymer particles subsequently dispersed in water in the usual way. During the polymerization, the initiators, emulsifiers or suspension aids, regulators or other auxiliaries customary for the particular polymerization process are used with used; it is polymerized continuously or discontinuously at the usual temperatures and pressures for the respective process in conventional reactors.

The crosslinker d) to be used according to the invention is, in particular, a phosphate or a melamine compound.

In a particularly preferred embodiment, the phosphate is an inorganic phosphate, in particular aluminum phosphate, boron phosphate or ammonium phosphate.

In a further preferred embodiment, the melamine is a melamine phosphate or melamine cyanurate.

In a further particularly preferred embodiment, the crosslinker is a methyl aminopolyphosphate, in particular of the formula

(HMPO3) _n

in which mean

M is a melamine radical n is an integer of at least 2, in particular 2 to 10,000.

In a preferred embodiment, crosslinking agent d) comprises melanin polyphosphate together with melamine cyanurate.

Further crosslinkers d) are, for example, amine sulfonate, dicyandiamide and tris-hydrazino-notriazines.

The silicone e) to be used according to the invention is preferably an aqueous silicone emulsion. In a particularly preferred embodiment, at least one of the following constituents is contained in the silicone emulsion: silicic acid, diethoxycylsilyltrimethylsilyl ester, dimethylsiloxane, hydroxy-limited aminoethylaminopropylsilsesquioxane. To reduce the thermal conductivity, preference is given to using an infrared-absorbing pigment (IR absorber), such as carbon black, coke, aluminum, graphite or titanium dioxide, in amounts of from 5 to 40% by weight, in particular in amounts of from 10 to 30% by weight, based on the solid of the coating used. The particle size of the IR-absorbing pigment is generally in the range of 0.1 to 100 .mu.m, in particular in the range of 0.5 and 10 microns.

Carbon black with an average primary particle size in the range from 10 to 300 nm, in particular in the range from 30 to 200 nm, is preferably used. The BET surface area is preferably in the range of 10 to 120 m ² / g.

The graphite used is preferably graphite having an average particle size in the range from 1 to 50 μm.

Furthermore, the coating composition, flame retardants, such as expanded graphite, borates, in particular zinc borates, in particular ortho-boron phosphate, or intumescent compositions which inflate when exposed to higher temperatures, usually over 80 to 100 ⁰ C, swell, or foam, and a form insulating and heat-resistant foam, which protects the underlying heat-insulating foam particles from the effects of fire and heat.

When flame retardants are used in the polymer coating, it is also possible to achieve adequate fire protection with foam particles which contain no, in particular no halogenated, flame retardants, or to use relatively low amounts of flame retardant, since the flame retardant concentrates in the polymer coating is located on the surface of the foam particles and forms a solid scaffolding net when exposed to heat or fire.

The coating composition may, as additional additives, cleave intumescent compositions containing chemically bound water, or at temperatures above 40 ^° C., such as metal hydroxides, metal salt hydrates, and metal oxide hydrates.

Suitable metal hydroxides are in particular those of groups 2 (alkaline earth metals) and 13 (boron group) of the Periodic Table. Preference is given to magnesium hydroxide, calcium hydroxide, aluminum hydroxide and borax. Alumni- nium hydroxide is particularly preferred.

Suitable metal salt hydrates are all metal salts in whose crystal structure water of crystallization is incorporated. Likewise suitable as metal oxide hydrates are all metal oxides which are available in the crystal structure contains incorporated water of crystallization. The number of crystal water molecules per formula unit may be the maximum possible or below, z. As copper sulfate pentahydrate, trihydrate or monohydrate. In addition to the water of crystallization, the metal salt hydrates or metal oxide hydrates may also contain constitutional water.

Preferred metal salt hydrates are the hydrates of metal halides (especially chlorides), sulfates, carbonates, phosphates, nitrates or borates. Suitable examples are magnesium sulfate decahydrate, sodium sulfate decahydrate, copper sulfate pentahydrate, nickel sulfate heptahydrate, cobalt (II) chloride hexahydrate, chromium (III) chloride hexahydrate, sodium carbonate decahydrate, magnesium chloride hexahydrate, and the tin borate. hydrates. Magnesium sulfate decahydrate and tin borate hydrates are particularly preferred.

Also suitable as metal salt hydrates are double salts or alums, for example those of the general formula: MW (SCU) ₂ ^.12H ₂ O. As M ¹ , z. As potassium, sodium, rubidium, cesium, ammonium, thallium or aluminum ions occur. As M ¹ ", for example, aluminum, gallium, indium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, rhodium or iridium.

As metal oxide hydrates z. For example, alumina hydrate and preferably zinc oxide hydrate or boron trioxide hydrate.

In addition to the clay minerals, additional minerals, for example cements, aluminum oxides, vermicullite or perlite, may additionally be added to the coating. These can be incorporated into the coating composition in the form of aqueous slurries or dispersions. Cements can also be applied by "powdering" on the foam particles. The water necessary for setting the cement can then be supplied with steam during sintering.

The coating composition is used in particular for coating foam particles. The invention therefore furthermore relates to a process for producing coated foam particles by applying the coating composition according to the invention, preferably in the form of an aqueous dispersion, to the foam particles and optionally drying.

As foam particles can be expanded polyolefins, such as expanded polyethylene

(EPE) or expanded polypropylene (EPP) or prefoamed particles of expandable styrene polymers, in particular expandable polystyrene (EPS) used become. The foam particles generally have a mean particle diameter in the range of 2 to 10 mm. The bulk density of the foam particles is generally 5 to 100 kg / m ³ , preferably 5 to 40 kg / m ³ and in particular 8 to 16 kg / m ³ , determined according to DIN EN ISO 60.

The foamed particles based on styrene polymers can be obtained by prefetching EPS with hot air or steam in a prefoamer to the desired density. By prefoaming once or several times in a pressure or continuous prefoamer, final bulk densities of less than 10 g / l can be achieved.

For the production of insulation boards with high thermal insulation capability it is particularly preferred to use prefoamed, expandable styrene polymers containing athermal solids, such as carbon black, aluminum, graphite or titanium dioxide, in particular graphite having an average particle size in the range from 1 to 50 μm particle diameter in amounts of 0, 1 to 10 wt .-%, in particular 2 to 8 wt .-%, based on EPS, and are known for example from EP-B 981 574 and EP-B 981 575 are known.

Furthermore, the foam particles may contain from 3 to 60% by weight, preferably from 5 to 20% by weight, based on the prefoamed foam particles, of a filler. Suitable fillers are organic and inorganic powders or fibrous materials, as well as mixtures thereof. As organic fillers z. As wood flour, starch, flax, hemp, ramie, jute, sisal, cotton, cellulose or aramid fibers are used. As inorganic fillers z. As carbonates, silicates, barite, glass beads, zeolites or metal oxides are used. Preference is given to pulverulent inorganic substances, such as talc, chalk, kaolin (Al ₂ (Si ₂ O ₅ ) (OH) ₄ ), aluminum hydroxide, magnesium hydroxide, aluminum nitride, aluminum silicate, barium sulfate, calcium carbonate, calcium sulfate, silica, quartz powder, Aerosil®, Alumina or wollastonite or spherical or fibrous inorganic substances, such as glass beads, glass fibers or carbon fibers.

The mean particle diameter or, in the case of fibrous fillers, the length should be in the range of the cell size or smaller. Preference is given to an average particle diameter in the range from 1 to 100 μm, preferably in the range from 2 to 50 μm.

Particular preference is given to inorganic fillers having a density in the range from 1.0 to 4.0 g / cm ³ , in particular in the range from 1.5 to 3.5 g / cm ³ . The whiteness / brightness (DIN / ISO) is preferably 50-100%, in particular 60-98%. The type and amount of fillers can affect the properties of the expandable thermoplastic polymers and the particle foam moldings obtainable therefrom. The use of adhesion promoters, such as maleic anhydride-modified styrene copolymers, epoxy group-containing polymers, organosilanes or styrene copolymers with isocyanate or acid groups, can significantly improve the binding of the filler to the polymer matrix and thus the mechanical properties of the particle foam moldings.

In general, inorganic fillers reduce flammability. In particular, by adding inorganic powders, such as aluminum hydroxide, magnesium hydroxide or borax, the fire behavior can be further improved.

Such filler-containing foam particles can be obtained, for example, by foaming filler-containing, expandable thermoplastic granules. At high filler contents required for this expandable granules by extrusion blowing agent-containing thermoplastic melts and subsequent pressurized underwater granulation such. As described in WO 2005/056653.

The polymer foam particles may additionally be equipped with other flame retardants. For example, they may contain from 1 to 6% by weight of an organic bromine compound, such as hexabromodylcododecane (HBCD) and optionally additionally from 0.1 to 0.5% by weight of dicumyl or a peroxide in the interior of the foam particles or the coating. However, preferably no halogen-containing flame retardants are used.

The coating composition according to the invention is preferably applied to the foam particles in the form of an aqueous polymer dispersion together with the clay mineral and the alkali metal silicate and optionally infrared-absorbing pigments and further additives.

The water glass powder contained in the coating mixture leads to a better or faster filming and thus a faster curing of the foam molding. Optionally, additional hydraulic binders based on cement, lime cement or gypsum may be added in amounts at which no appreciable embrittlement of the foam occurs.

For coating the foam particles, conventional methods, such as spraying, dipping or wetting the foam particles with an aqueous coating Composition in conventional mixers, sprayers, dipping devices or drum apparatuses are used.

Furthermore, the foam particles coated according to the invention can additionally be coated with amphiphilic or hydrophobic organic compound. The coating with hydrophobing agent is expediently carried out before the application of the aqueous coating composition according to the invention. Among the hydrophobic organic compounds are in particular C ₁ 0 - C30 paraffin waxes, reaction products of N-methylolamine and a fatty acid derivatives, reaction products of a C ₉ -Cn oxo alcohol with ethylene oxide, propylene oxide or butylene oxide or polyfluoroalkyl (meth) acrylates or mixtures thereof , which can preferably be used in the form of aqueous emulsions.

Preferred hydrophobizing agents are paraffin waxes having 10 to 30 carbon atoms in the carbon chain, which preferably have a melting point between 10 and 7O ⁰ C, in particular between 25 and 6O ⁰ C. Such paraffin waxes are contained, for example, in the BASF commercial products RAMASIT KGT, PERSISTOL E and PERSISTOL HP, as well as in AVERSIN HY-N from Henkel and CEROL ZN from Sandoz.

Another class of suitable hydrophobizing agents are resinous reaction products of an N-methylolamine with a fatty acid derivative, e.g. Example, a fatty acid amide, amine or alcohol, as z. For example, in US-A 2,927,090 or GB-A 475 170 are described. Its melting point is generally from 50 to 9O ⁰ C. Such resins are for. In the BASF commercial product PERSISTOL HP and in ARCOPHOB EFM from Hoechst.

Finally, polyfluoroalkyl (meth) acrylates are also suitable, for example, perfluorooctyl acrylate. This substance is contained in the BASF commercial product PERSISTOL O and in OLEOPHOBOL C from Pfersee.

Further suitable coating agents are antistatic agents, such as emulsifier K30 (mixture of secondary sodium alkanesulfonates) or glycerol stearates, such as glycerol monostearate GMS or glycerol tristearate. However, the method according to the invention is distinguished by the fact that the coating materials which are customary for the coating of expandable polystyrene, in particular stearates, can be used to a reduced extent or eliminated altogether, without negatively influencing the product quality.

For the production of foam moldings, the foam particles provided with the coating according to the invention can be sintered in a mold. there The coated foam particles can be used while still wet or after drying.

The drying of the coating composition applied to the foam particles can take place, for example, in a fluidized bed, paddle dryer or by passing air or nitrogen through a loose bed. In general, a drying time of 5 minutes to 24 hours, preferably 30 to 180 minutes at a temperature in the range of 0 to 80 ⁰ C, preferably in the range of 30 to 60 ⁰ C is sufficient for the formation of the water-insoluble polymer film.

The water content of the coated foam particles after drying is preferably in the range from 1 to 40 wt .-%, more preferably in the range of 2 to 30 wt .-%, most preferably in the range of 5 to 15 wt .-%. It can be determined, for example, by Karl Fischer titration of the coated foam particles. The weight ratio of foam particles / coating mixture after drying is preferably 2: 1 to 1:10, particularly preferably 1: 1 to 1: 5.

The foam particles dried according to the invention can be sintered in conventional molds with hot air or steam to give foam moldings.

When sintering or gluing the foam particles, the pressure can be generated for example by reducing the volume of the mold by means of a movable punch. As a rule, a pressure in the range from 0.5 to 30 kg / cm ^{2 is} set here. For this purpose, the mixture of coated foam particles is filled into the opened mold. After closing the mold, the foam particles are pressed with the stamp, wherein the air between the foam particles escapes and the gusset volume is reduced. The foam particles are connected by the coating to the foam molding.

Preferably, a compression takes place about 10 to 90%, preferably 60 to 30%, in particular 50 to 30% of the initial volume. In a mold with a cross section of about 1 m ² , a pressure of 1 to 5 bar is usually sufficient for this purpose.

The mold is designed according to the desired geometry of the foam molding. The degree of filling depends, inter alia, on the desired thickness of the later molded part. For foam boards, a simple box-shaped form can be used. In particular, in the case of more complicated geometries, it may be necessary to compact the bed of the particles introduced into the mold and in this way to eliminate unwanted voids. The compression can z. B. by shaking the form, tumbling or other suitable measures. To accelerate setting, hot air or water vapor can be pressed into the mold or the mold heated. For tempering the mold, however, any heat transfer media, such as oil or steam can be used. The hot air or the mold is suitably tempered for this purpose to a temperature in the range of 20 to 120 ⁰ C, preferably 30 to 90 ⁰ C.

Alternatively or additionally, the sintering can be carried out continuously or discontinuously under the action of microwave energy. In this case, microwaves are generally used in the frequency range between 0.85 and 100 GHz, preferably 0.9 to 10 GHz and irradiation times between 0.1 to 15 minutes. It is also possible to produce foam boards with a thickness of more than 5 cm.

When using hot air or steam at temperatures in the range of 80 to 150 ⁰ C or by irradiation of microwave energy usually forms an overpressure of 0.1 to 1, 5 bar, so that the method is carried out without external pressure and without volume reduction of the mold can be. The internal pressure resulting from higher temperatures allows the foam particles to expand slightly further, and in addition to bonding via the polymer coating, these can also be welded by softening the foam particles themselves. The gussets disappear between the foam particles. To accelerate setting, the shape can also be heated with a heat transfer medium as described above. When microwaves are irradiated, the inorganic coating constituents are generally heated, which then crosslink or condense more quickly as a result.

For the continuous production of foam moldings are also double belt systems as they are used for the production of polyurethane foams. For example, the prefoamed and coated foam particles may be continuously applied to the lower of two metal bands, which may optionally have a perforation, and processed with or without compression by the converging metal bands into endless foam sheets. In one process embodiment, the volume between the two belts is progressively reduced, compressing the product between the belts and eliminating the gussets between the foam particles. After a curing zone, an endless plate is obtained. In another embodiment, the volume between the bands can be kept constant and pass through a zone of hot air or microwave irradiation in which the foam particles re-foam. Again, the gussets disappear and an endless plate is obtained. It is also possible to combine the two continuous process operations. The thickness, length and width of the foam sheets can vary within wide limits and is limited by the size and closing force of the tool. The thickness of the foam sheets is usually 1 to 500 mm, preferably 10 to 300 mm. Further preferred sizes and order ranges are 10 to 200 mm, preferably 20 to 110 mm, particularly preferably 25 to 95 mm.

The density of the foam moldings according to DIN 53420 is generally 10 to 150 kg / m ³ , preferably 20 to 90 kg / m ³ . With the method it is possible to obtain foam moldings with uniform density over the entire cross section. The density of the edge layers corresponds approximately to the density of the inner regions of the foam molding.

The process can also be used crushed foam particles made of recycled foam moldings. To produce the foam moldings of the invention, the comminuted foam recycled to 100% or z. B. in proportions of 2 to 90 wt .-%, in particular 5 to 25 wt .-% are used together with virgin material, without significantly affecting the strength and mechanical properties.

The coating may also contain other additives which preferably or only slightly contribute to the combustibility and / or substances which in the non-fired state have a positive influence on the mechanical or thermal properties, for example vermiculites, in addition to the mechanical and hydraulic properties to modify

A preferred method comprises the steps:

i) prefoaming of expandable styrene polymers into foam particles, ii) applying the coating composition according to the invention in the form of an aqueous dispersion to the foam particles, iii) drying the polymer dispersion on the foam particles to form a water-insoluble polymer film iv) filling the polymer film-coated foam particles into a mold and sintering.

A particularly preferred method involves the pressing of the still water-moist foam particles according to the following process:

i) prefoaming of expandable styrene polymers into foam particles, ii) applying the coating composition according to the invention in the form of an aqueous dispersion to the foam particles, iii) filling the coated with the coating composition and still moist foam particles in a mold, pressing and curing by exposure to temperature and / or microwave.

The process is suitable for the production of simple or complex foam moldings, such as plates, blocks, tubes, rods, profiles, etc. Preferably, sheets or blocks which can be subsequently sawn or cut into sheets are produced. For example, they can be used in construction for the insulation of exterior walls. They are particularly preferably used as core layer for the production of sandwich elements, for example so-called structural insulation panels (SIP), which are used for the construction of cold stores or warehouses.

The clay minerals can be easily dispersed in aqueous polymer dispersions and applied to the prefoamed foam particles. The ceramization with the alkali silicate is carried out only in case of fire at temperatures of about 500 ⁰ C. The use of clay minerals, such as kaolin in the coating composition does not lead to embrittlement of the foam molding in sintering. The resulting in case of fire porous ceramic framework structure then withstands temperatures of about 1000 ⁰ C stood.

The foam particles provided with the coating according to the invention can be sintered into foam moldings which have a high fire resistance value E30, in particular E60 or F30, in particular F60, and prevent flame penetration even with prolonged flame exposure of more than 30 or 60 minutes and the structural integrity the resulting porous ceramic framework structure is maintained.

Such foam moldings can be used as sandwich elements. For better sealing between the joints of such sandwich elements sealing strips between the individual sandwich panels (panels) are usually used, especially in cooling and storage halls. Ideally, the seal should be designed so that the gas-tightness of the fugue facing away from the joint even if the panels in case of fire, ie subject to heat, dimensional changes, in the joints to the effects of force and resulting shifts in different spatial directions can lead. Sealing tapes of polyurethanes brittle usually at about 120 ⁰ C. If hot vapors reach the sealing tape brittle this and loses its sealing properties. Therefore, it comes to the breakthrough of the hot gases and the corresponding heating of the temperature sensors on the outside.

Preferably sealing tapes are used which have a certain elasticity even at higher temperatures. Ie. When the joint and the band heats up and "warps", the band still seals (airtightness), which prevents the gases from escaping at the front, as shown, for example, by the fact that there is almost no difference in temperature even after 30 minutes In this case, it is not necessary to make an asymmetrical structure, since very high temperatures occur within the furnace within a very short time, whereupon the outer sheets of the sandwich elements detach from the core. which immediately allow the gases to escape inside the oven.

The sealing tapes should not only remain elastic when exposed to heat but, within certain limits, also be able to "re-inflate", ie possess intumescent properties in order to be able to maintain gas-tightness in the case of dimensional changes in the region of the joint, in particular in the case of gap formation Therefore, intumescent sealing tapes are inserted between the abutting core layers of the sandwich elements, which then foam step by step as the joint widens and both the temperature and the gas propagation are decelerated.This measure reduces the temperature load acting on the joint remote from the source of the fire and thus significantly improve the service life of the "outer joint".

Also conceivable are foam-like structures or elastic fiber structures, which are inserted into the joints during the construction of the panel construction and are pressed together when the panels are finally fixed on the substructure. In the event of fire, especially if the panels are subject to dimensional changes due to the effects of heat, this elastic "inlay" can adapt to the changed dimensions in the area of the joint and thereby seal it more efficiently Suitable for this purpose are melamine resin foams (Basotect® from BASF SE), mineral wool strips or a flame-retardant polyethylene foam strip.

The cores could also be provided with a profile, e.g. B. stepped rabbet or tongue and groove, with integrated or inserted spring, are provided so that the cores engage with each other and thus also better seal. Of importance is also the geometry of the joint. Preference is given to "standard joints" with the greatest possible overlap and mechanical rigidity. To seal the joint own from the core material milled groove and springs, for example, after the Inta-Lock concept, with milled into the core material, several centimeters deep groove but with loose, nachzuläglich einzusetzender on the site spring. This can be made of a large number of heat-resistant materials and serves primarily to prevent / reduce gas leakage through the joint in case of fire, even if the core material shrinks slightly due to the effect of heat or the panels deformed in the joint, which without a spring to a Gaping and resulting escape of hot fire lanes in the area of the joint would result.

As materials for the spring, for example, Regips strips, strips of silicone or intumescent materials such as expanded graphite or silicates, for example Palusol® or the coating composition according to the invention, mineral fiber wedges, wedges of melamine resin foams (Basotect®), thin sheet metal strips, the can be inserted on both sides in a thin groove.

If necessary, the springs can be fixed mechanically by means of screws, rivets, etc. Furthermore, elastic inlays and sealing tapes are suitable, which are inserted into the metal recess of the joint profile and swell when exposed to heat and seal the joints. The elastic inlays in the surface would be

Structure of the panel wall compressed between the bumps of the core material and in the

Fire, if the gap gapes due to the effect of heat, shrinks or deforms, within certain limits sealing effect or at least significantly reduce the outflow of fumes.

Applications include pallets made of foam as a replacement for wooden pallets, cover panels, refrigerated containers, caravans. Due to their excellent fire resistance, they are also suitable for airfreight. Particularly preferred application forms are building applications, for example facades, in particular ventilated facades, flat roofs, trapezoidal flat roofs and fire bars.

Examples:

test methods

To check the quality of the samples, a series of investigations was carried out. First, after the proper deposition time, the volume loss in case of fire (test A) was determined. This was a cube with 5 cm edge length Sintered for 15 minutes at 1030 ⁰ C, or 800 ⁰ C in a muffle furnace. The cubic volume was then determined again and subtracted from the initial value. Furthermore, the water absorption of the cubes was determined (test B). For this purpose, a cube of 5 cm edge length was completely immersed in 50 ⁰ C warm water and completely wetted with water for 24 hours. Subsequently, the cube was weighed again after drying and thus determined the proportion of leached coating. The water in the container was evaporated and the residue was weighed to give a more accurate reading. Subsequently, the cube was again completely dried and subjected to a fire test as described in Test A). This resulted in the loss of fire after water exposure (Test C).

Preparation of the coating mixtures and the polystyrene foam particles

Commercially available polystyrene foam particles (10 g / L, Neopor ^® 2300) were incubated with the indicated in Table 1 coating in a weight ratio of 1: coated homogeneously. 4 The coated particles were then filled into an aluminum mold (20 x 20 cm) and pressed under pressure to 50% of the original volume. The examination of the samples obtained was carried out as described under "Test Methods".

Table 1 :

Ex. 1 Ex.2 Ex.3 Ex.4 Ex 5 Ex 6 Ex 7 Composition Parts by weight Parts by weight Parts by weight Parts by weight Parts by weight Parts by weight Wt. parts

Water glass powder 100 100 100 100 100 100 100

Kaolin 100 100 120 120 100 100 120

Titanium dioxide 20 20

Acronal S790 22 22 30 30 30 30 30

Silicone emulsion 7 7 7 7 7

Melamine cyanurate 10 20 20 20 20 20

Melamine polyphosphate 20 20 20 ortho-boron phosphate 10 10 10

VE water 80 15 100 100 100 100 100

Compression [%] 50 50 50 40 50 40 50

Coating quantity 1: 4 1: 4 1: 4 1: 4 1: 4 1: 4 1: 4

Test A at 1030 ° C [-%] 15 45 32 30 11 11 13

Test A at 800 ^° C [-%] 6 15 4 4 3 4 4

Test B [-%] _* 16 10 14 9 13 11

Test C at 1030 ° C [-%] _* 28 27 18 19 15 15

Test C at 800 ^° C. [-%] _* 20 20 26 15 10 7 ^* does not mean measurable.

Examples 2 to 7 according to the invention showed good values after water exposure according to test B and C, whereas the comparative sample according to example 1 was not measurable ( ^* ) due to decomposition.

Claims

claims

A coating composition containing

a) 20 to 70 parts by weight of a clay mineral b) 20 to 70 parts by weight of an alkali metal silicate c) 1 to 30 parts by weight of a film-forming polymer d) 1 to 20 parts by weight of a crosslinking agent, in particular based on a

Phosphates or a melamine compound and optionally e) a hydrophobizing effective amount of a silicon-containing compound.

2. A coating composition according to claim 1, comprising

a) 30 to 50 parts by weight of a clay mineral b) 30 to 50 parts by weight of an alkali silicate c) 5 to 20 parts by weight of a film-forming polymer d) 5 to 10 parts by weight of a phosphate or a melamine e) 0.2 to 5 parts by weight of a silicone f) 5 to 40 parts by weight of an infrared absorbing pigment

3. Coating composition according to at least one of the preceding claims, characterized in that the phosphate is an inorganic phosphate, in particular aluminum phosphate, boron phosphate or ammonium phosphate.

4. Coating composition according to at least one of the preceding claims, characterized in that the melamine compound is melamine cyanate.

5. Coating composition according to at least one of the preceding claims, characterized in that the crosslinker is a Melaminpolyphos- phat, in particular the formula

(HMPOa) _n

in which mean

M is a melamine radical n is an integer, at least 2, in particular 2 to 10,000.

6. Coating composition according to at least one of the preceding claims, characterized in that the weight ratio of clay mineral to alkali metal silicate in the range of 1: 2 to 2: 1.

7. Coating composition according to at least one of the preceding claims, characterized in that it contains as clay mineral allophan Al ₂ [SiO ₅ ] SO ₃ xnH ₂ O, kaolinite Al ₄ [(OH) ₈ / Si ₄ 0io], Halloysite Al ₄ [( OH) ₈ / Si ₄ Oi ₀ ] x 2 H ₂ O, montmorillonite (smectite) (Al ₁ Mg, Fe) ₂ [(OH ₂ / (Si, Al) ₄ Oi ₀ ] x Na ₀ , ₃ 3 (H ₂ O) ₄ , vermiculite Mg ₂ (Al, Fe, Mg) [(OH ₂ / (Si, Al) ₄ Oio] x Mg ₀ , 35 (H ₂ O) ₄ or mixtures thereof.

8. Coating composition according to at least one of the preceding claims, characterized in that it contains as alkali metal silicate a water-soluble alkali metal silicate having the composition M ₂ O (SiO ₂ ) _n with M = sodium or potassium and n = 1 to 4 or mixtures thereof.

9. Coating composition according to at least one of the preceding claims, characterized in that it contains as a film-forming polymer, an emulsion polymer of ethylenically unsaturated monomers which has a glass transition temperature in the range of -30 ° to +80 ⁰ C.

10. foam particles with a coating according to at least one of the preceding claims.

1 1. Foamed particles according to claim 10, characterized in that the foam particles are selected from expanded polyolefin particles or possibly prefoamed particles of expandable styrene polymers.

12. A process for the production of foam moldings, characterized marked, that sintered foam particles according to claim 10 or 1 1 in a mold.

13. The method according to claim 12, characterized in that it is the stages

(i) prefoaming expandable styrene polymers into foam particles, (ii) applying the coating composition according to the invention in

Form of an aqueous dispersion on the foam particles, (iii) drying of the polymer dispersion on the foam particles with the formation of a water-insoluble polymer film and (iv) filling the polymer film-coated foam particles into a mold and sintering,

includes.

14. The method according to claim 12, characterized in that it is the stages

i) prefoaming of expandable styrene polymers into foam particles, ii) applying the coating composition according to the invention in

Form of an aqueous dispersion on the foam particles) iii) filling the coated with the coating composition and still wet with water foam particles in a mold, pressing and curing by exposure to temperature and / or microwave.

includes.

15. Use of the foam moldings produced according to at least one of the preceding methods for building applications, in particular as a replacement for wooden pallets, ceilings, viewing panels, refrigerated containers, caravans, facades, in particular ventilated facades, flat roofs, trapezoidal roofs and fire bars.