METHOD AND DEVICE FOR PRODUCING FOAM COMPOSITE ELEMENTS

Abstract

The invention relates to a method and a device for applying a foamable reaction mixture to a moving cover layer (10), the reaction mixture being applied to discharge openings (400) on the cover layer (10) and the cover layer moving at a speed of 15 meters per minute relative to the discharge openings. The device also comprises 7 discharge openings (400).

Claims

1. A process, comprising: applying a foamable reaction mixture onto a moving outerlayer, wherein the reaction mixture is applied onto the outerlayer from 7 discharge openings simultaneously and the outerlayer moves at a speed of 15 meters per minute relative to the discharge openings.

2. The process of claim 1, further comprising: providing a plurality of mixing heads, wherein each mixing head is adapted for mixing two or more reactant streams to afford one product stream; providing a distributor, wherein the distributor comprises 7 discharge conduits, each of which terminate in one of the 7 discharge openings, the distributor is connected to the product streams from the mixing heads and the distributor is adapted for combining the product streams from the mixing heads and distributing them to its 7 discharge conduits in homogeneous material composition; mixing the two or more reactant streams in each of the mixing heads to obtain the product stream exiting each of the mixing heads; combining the product streams in the distributor; distributing the combined product streams to the discharge conduits of the distributor; applying the reaction mixture from the 7 discharge openings of the 7 discharge conduits onto the outerlayer.

3. The process of claim 1, further comprising: providing a plurality of mixing heads, wherein each mixing head is adapted for mixing two or more reactant streams to afford one product stream; providing a distributor, wherein the distributor comprises one or more discharge conduits, the distributor is connected to the product streams from the mixing heads and the distributor is adapted for combining the product streams from the mixing heads and distributing them to the one or more discharge conduits in homogeneous material composition; providing one or more rake applicators, wherein the number of rake applicators corresponds to the number of the one or more discharge conduits of the distributor, each rake applicator is connected to one of the one or more discharge conduits and each rake applicator has 4 of the 7 discharge openings; mixing the two or more reactant streams in each of the mixing heads to obtain the product stream exiting each of the mixing heads; combining the product streams in the distributor; distributing the combined product streams to the one or more discharge conduits of the distributor; applying the reaction mixture from the 4 of the 7 discharge openings of each of the one or more rake applicators onto the outerlayer.

4. The process of claim 3, further comprising providing at least two rake applicators arranged side-by-side viewed transversely to the direction of movement of the outerlayer and arranged one behind the other viewed in the direction of motion of the outerlayer (10).

5. The process of claim 1, further comprising: providing a single mixing head, wherein the mixing head is adapted for mixing two or more reactant streams to afford one product stream; providing a single distributor, wherein the distributor comprises one or more discharge conduits, the distributor is connected to the product stream from the mixing head and the distributor is adapted for distributing the product stream from the mixing head to the one or more discharge conduits in homogeneous material composition. providing a plurality of rake applicators, wherein the number of rake applicators corresponds to the number of the one or more discharge conduits of the distributor, each rake applicator is connected to one of the one or more discharge conduits and each rake applicator has 4 of the 7 discharge openings; mixing the two or more reactant streams in the mixing head to obtain the product stream exiting the mixing head, wherein the product stream comprises a foamable reaction mixture; transferring the product stream in the distributor; distributing the product stream to the one or more discharge conduits of the distributor; applying the reaction mixture from the 4 of the 7 discharge openings of each of the one or more rake applicators onto the outerlayer.

6. The process of claim 1, wherein the reaction mixture comprises a polyol, a polyisocyanate, and a blowing agent.

7. An apparatus for applying a foamable reaction mixture onto a moving outerlayer, the apparatus comprising 7 discharge openings adapted to apply the reaction mixture onto the outerlayer.

8. The apparatus of claim 7, further comprising: a plurality of mixing heads, wherein each mixing head is adapted for mixing two or more reactant streams to afford one product stream; a distributor, wherein the distributor comprises 7 discharge conduits, each of which terminate in one of the 7 discharge openings, the distributor is connected to the product streams from the plurality of mixing heads and the distributor is adapted for combining the product streams from the plurality of the mixing heads and distributing them to its 7 discharge conduits in homogeneous material composition.

9. The apparatus of claim 7, further comprising: a plurality of mixing heads, wherein each mixing head is adapted for mixing two or more reactant streams to afford one product stream; a distributor, wherein the distributor comprises one or more discharge conduits, the distributor is connected to the product streams from the plurality of the mixing heads and the distributor is adapted for combining the product streams from the plurality of the mixing heads and distributing them to the one or more discharge conduits in homogeneous material composition; one or more rake applicators, wherein the number of rake applicators corresponds to the number of the one or more discharge conduits of the distributor, each rake applicator is connected to one of the one or more discharge conduits and each rake applicator has 4 of the 7 discharge openings.

Description

[0015] It is an object of the present invention to at least partially remedy the disadvantages in the prior art. It is a particular object of the invention to achieve a more homogeneous product quality over the width of an insulation panel or a foam composite element.

[0016] The object is achieved in accordance with the invention by a process as claimed in claim 1 and an apparatus as claimed in claim 7. Advantageous developments are specified in the subsidiary claims.

[0017] The present invention relates to a process for applying a foamable reaction mixture onto a moving outerlayer, wherein the reaction mixture is applied onto the outerlayer from discharge openings and the outerlayer moves at a speed of 15 meters per minute relative to the discharge openings, wherein the reaction mixture is applied onto the outerlayer from 7 discharge openings simultaneously.

[0018] An improvement in the pre-distribution of the reaction mixture into the contents of the present invention allows for substantially simpler control of the process and results in improved product quality after a shorter startup phase in production.

[0019] The process according to the invention is preferably a continuous process. It is suitable for the production of foam composite elements such as insulation panels in a high-speed production procedure. Depending on thickness the outerlayer speed is for example 10 to 70 meters per minute, preferably 15 meters per minute, more preferably 30 meters per minute.

[0020] Suitable outerlayers or substrates include for example metal films, in particular aluminum films, multilayer outerlayers, for example made of aluminum and paper, and plastics films. There is generally no limitation on the width of the outerlayer. For example the outerlayer may have a width between 1000 and 1300 mm, but a width of 2400 mm is also possible.

[0021] Suitable reaction mixtures include in particular a mixture which reacts to afford a polyurethane and/or polyisocyanurate foam. In one embodiment of the process according to the invention the reaction mixture therefore comprises a polyol A), a polyisocyanate B), optionally additives such as for example stabilizers and catalysts, optionally one or more flame retardants and one (or more) blowing agents C).

[0022] The polyol A) is preferably selected from the group of the polyether polyols, polyester polyols, polycarbonate polyols and/or polyether ester polyols. The OH number of the employed polyol or of the employed polyols may be for example >100 mg KOH/g to <800 mg KOH/g and the average OH functionality of the employed polyol or of the employed polyols is 2. In the case of a single added polyol the OH number indicates the OH number of said polyol. In the case of mixtures the average OH number is reported. This value may be determined in accordance with DIN 53240. The average OH functionality of the polyols is for example in a range from 2 to <6.

[0023] Polyether polyols that may be used include, for example, polytetramethylene glycol polyethers such as are obtainable by polymerization of tetrahydrofuran by cationic ring opening. Likewise suitable polyether polyols are addition products of styrene oxide, ethylene oxide, propylene oxide, butylene oxides and/or epichlorohydrin onto di- or polyfunctional starter molecules. It is usual to employ polyether polyols with ethylene oxide or propylene oxide as chain extenders.

[0024] Suitable starter molecules are for example ethylene glycol, diethylene glycol, butyl diglycol, glycerol, diethylene glycol, trimethylolpropane, propylene glycol, pentaerythritol, sorbitol, sucrose, ethylenediamine, toluenediamine, triethanolamine, 1,4-butanediol, 1,6-hexanediol and low molecular weight hydroxyl-containing esters of such polyols with dicarboxylic acids.

[0025] Employable polyester polyols include inter alia polycondensates of di- and also tri- and tetraols and di- and also tri- and tetracarboxylic acids or hydroxycarboxylic acids or lactones. Also employable for producing the polyesters instead of the free polycarboxylic acids are the corresponding polycarboxylic anhydrides or corresponding polycarboxylic esters of lower alcohols.

[0026] Examples of suitable diols are ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols such as polyethylene glycol, and also 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,3-butanediol, 1,6-hexanediol and isomers, neopentyl glycol or neopentyl glycol hydroxypivalate. In addition, it is also possible to use polyols such as trimethylolpropane, glycerol, erythritol, pentaerythritol, trimethylolbenzene or trishydroxyethyl isocyanurate.

[0027] Examples of polycarboxylic acids that may be used include phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, tetrachlorophthalic acid, maleic acid, fumaric acid, itaconic acid, malonic acid, suberic acid, succinic acid, 2-methylsuccinic acid, 3,3-diethylglutaric acid, 2,2-dimethylsuccinic acid, dodecanedioic acid, endomethylenetetrahydrophthalic acid, dimer fatty acid, trimer fatty acid, citric acid, or trimellitic acid. Acid sources that may be used further include the corresponding anhydrides.

[0028] If the mean functionality of the polyol to be esterified is >2, it is additionally also possible to use monocarboxylic acids such as benzoic acid and hexanecarboxylic acid as well. Hydroxycarboxylic acids that may be co-used as reaction participants in the production of a polyester polyol having terminal hydroxyl groups are for example hydroxycaproic acid, hydroxybutyric acid, hydroxydecanoic acid, hydroxystearic acid and the like. Suitable lactones include caprolactone, butyrolactone and homologs.

[0029] Polycarbonate polyols that may be used are hydroxyl-containing polycarbonates, for example polycarbonate diols. These are obtainable by reaction of carbonic acid derivatives, such as diphenyl carbonate, dimethyl carbonate or phosgene, with polyols, preferably diols, or from carbon dioxide.

[0030] Examples of such diols are ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, 2-methylpropane-1,3-diol, 2,2,4-trimethylpentane-1,3-diol, dipropylene glycol, polypropylene glycols, dibutylene glycol, polybutylene glycols, bisphenol A, and lactone-modified diols of the aforementioned type. Polyether polycarbonate diols may also be employed instead of or in addition to pure polycarbonate diols.

[0031] Employable polyetherester polyols are compounds containing ether groups, ester groups and OH groups. Organic dicarboxylic acids having up to 12 carbon atoms are suitable for producing the polyetherester polyols, preferably aliphatic dicarboxylic acids having >4 to <6 carbon atoms or aromatic dicarboxylic acids used singly or in admixture. Examples include suberic acid, azelaic acid, decanedicarboxylic acid, maleic acid, malonic acid, phthalic acid, pimelic acid and sebacic acid and in particular glutaric acid, fumaric acid, succinic acid, adipic acid, phthalic acid, terephthalic acid and isoterephthalic acid. Derivatives of these acids that may be used include, for example, their anhydrides and also their esters and monoesters with low molecular weight monofunctional alcohols having >1 to <4 carbon atoms.

[0032] Examples of suitable polyisocyanates B) include 1,4-butylene diisocyanate, 1,5-pentane diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 2,4- and/or 2,4,4-trimethylhexamethylene diisocyanate, the isomeric bis(4,4-isocyanatocyclohexyl)methanes or their mixtures of any desired isomer content, 1,4-cyclohexylene diisocyanate, 1,4-phenylene diisocyanate, 2,4- and/or 2,6-tolylene diisocyanate (TDI), 1,5-naphthylene diisocyanate, 2,2- and/or 2,4- and/or 4,4-diphenylmethane diisocyanate (MDI) or higher homologs (polymeric MDI, pMDI), 1-3- and/or 1,4-bis(2-isocyanatoprop-2-yl)benzene (TMXDI), 1,3-bis(isocyanatomethyl)benzene (XDI) and also alkyl 2,6-diisocyanatohexanoates (lysine diisocyanates) having C1 to C6-alkyl groups.

[0033] In addition to the abovementioned polyisocyanates, it is also possible to use proportions of modified diisocyanates having a uretdione, isocyanurate, urethane, carbodiimide, uretonimine, allophanate, biuret, amide, iminooxadiazinedione and/or oxadiazinetrione structure and also unmodified polyisocyanate having more than 2 NCO groups per molecule, for example 4-isocyanatomethyl-1,8-octane diisocyanate (nonane triisocyanate) or triphenylmethane 4,4,4-triisocyanate.

[0034] In the reaction mixture the ratio of the number of NCO groups in the isocyanate to the number of isocyanate-reactive groups may result in an index of 110 to 600. Preferably between 115 and 400. This index may also be in a range from >180:100 to <330:100 or else >90:100 to <140:100.

[0035] The reaction mixture further contains sufficient blowing agent C) as is required for achieving a dimensionally stable foam matrix and the desired apparent density. This is generally 0.5-30 parts by weight of blowing agent based on 100 parts by weight of the component A. Preferably employed blowing agents are physical blowing agents selected from at least one member of the group consisting of hydrocarbons, halogenated ethers and perfluorinated hydrocarbons having 1 to 8 carbon atoms. In the context of the present invention physical blowing agents are to be understood as meaning compounds which on account of their physical properties are volatile and unreactive toward the isocyanate component. The physical blowing agents to be used according to the invention are preferably selected from hydrocarbons (for example n-pentane, isopentane, cyclopentane, butane, isobutane), ethers (for example methylal), halogenated ethers, perfluorinated hydrocarbons having 1 to 8 carbon atoms (for example perfluorohexane) and mixtures thereof with one another. Also preferred is the use of (hydro)fluorinated olefins, for example HFO 1233zd(E) (trans-1-chloro-3,3,3-trifluoro-1-propene) or HFO 1336mzz(Z) (cis-1,1,1,4,4,4-hexafluoro-2-butene) or additives such as FA 188 from 3M (1,1,1,2,3,4,5,5,5-nonafluoro-4-(trifluormethyl)pent-2-ene) and the use of combinations of these blowing agents. In particularly preferred embodiments the blowing agent C) employed is a pentane isomer or a mixture of different pentane isomers. It is exceptionally preferable to employ cyclopentane as the blowing agent C). Further examples of preferably employed hydrofluorocarbons are for example HFC 245fa (1,1,1,3,3-pentafluoropropane), HFC 365mfc (1,1,1,3,3-pentafluorobutane), HFC 134a or mixtures thereof. Different blowing agent classes may also be combined.

[0036] Also especially preferred is the use of (hydro)fluorinated olefins, for example HFO 1233zd(E) (trans-1-chloro-3,3,3-trifluoro-1-propene) or HFO 1336mzz(Z) (cis-1,1,1,4,4,4-hexafluoro-2-butene) or additives such as FA 188 from 3M (1,1,1,2,3,4,5,5,5-nonafluoro-4(or 2)-(trifluoromethyl)pent-2-ene and/or 1,1,1,3,4,4,5,5,5-nonafluoro-4(or 2)-(trifluoromethyl)pent-2-ene), alone or in combination with other blowing agents. These have the advantage of having a particularly low ozone depletion potential (ODP) and a particularly low global warming potential (GWP). The process according to the invention allows advantageous employment of (hydro)fluorinated olefins as blowing agents for composite systems since it allows production of composite elements having improved surface structures and improved adhesion to the outerlayer compared to composite elements produced with other application techniques.

[0037] Chemical blowing agents (also referred to as co-blowing agents) may be employed instead of or in addition to the abovementioned physical blowing agents. These are particularly preferably water and/or formic acid. The chemical blowing agents are preferably employed together with physical blowing agents. It is preferable when the co-blowing agents are employed in an amount up to 6% by weight, particularly preferably 0.5% to 4% by weight, for the composite elements based on the total amount of compounds having isocyanate-reactive hydrogen atoms in the component A.

[0038] Preferably employed for composite elements is a mixture of 0 and 6.0% by weight of co-blowing agent and 1.0% to 30.0% by weight of blowing agent in each case based on 100% by weight of the component A. However, the quantity ratio of co-blowing agent to blowing agent may also be from 1:7 to 1:35 according to requirements.

[0039] The reaction mixture optionally further contains a catalyst component D) which is suitable for catalyzing the blowing reaction, the urethane reaction and/or the isocyanurate reaction (trimerization). The catalyst components may be metered into the reaction mixture or else initially charged in the isocyanate-reactive component A) in full or in part.

[0040] Suitable therefor are in particular one or more catalytically active compounds selected from the following groups:

[0041] D1) aminic catalysts, for example amidines, such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines, such as triethylamine, tributylamine, dimethylcyclohexylamine, dimethylbenzylamine, N-methyl-, N-ethyl-, N-cyclohexylmorpholine, N,N,N,N-tetramethylethylenediamine, N,N,N,N-tetramethylbutanediamine, N,N,N,N-tetramethylhexanediamine-1,6, pentamethyldiethylenetriamine, bis(2-dimethylaminoethyl)ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, N,N,N-tris(dimethylaminopropyl)hexahydrotriazine, bis[2-(N,N-dimethylamino)ethyl]ether, 1-azabicyclo-(3,3,0)-octane and 1,4-diazabicyclo-(2,2,2)-octane, and alkanolamine compounds, such as triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine, N,N-dimethylaminoethoxy ethanol, N,N,N-trimethylaminoethylethanolamine and dimethylethanolamine. Particularly suitable compounds are selected from the group comprising tertiary amines, such as triethylamine, tributylamine, dimethylcyclohexylamine, dimethylbenzylamine, N,N,N,N-tetramethylethylenediamine, pentamethyldiethylenetriamine, bis(2-dimethylaminoethyl)ether, dimethylpiperazine, 1,2-dimethylimidazole and alkanolamine compounds, such as tris(dimethylaminomethyl)phenol, triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine, N,N-dimethylaminoethoxyethanol, N,N,N-trimethylaminoethylethanolamine and dimethylethanolamine

[0042] In a particularly preferred embodiment the catalyst component employs one or more aminic compounds having the structure:

(CH3)2NCH2-CH2-XCH2-CH2-Y

wherein YNR2 or OH, preferably YN(CH3)2 or OH, particularly preferably YN(CH3)2

[0043] and wherein XNR or O, preferably XNCH3 or O, particularly preferably XNCH3. Every R may be chosen independently of every other R and represents an organic radical

[0044] of any desired structure having at least one carbon atom. R is preferably an alkyl group having 1 to 12 carbon atoms, in particular C1- to C6-alkyl, particularly preferably methyl and ethyl, in particular methyl.

[0045] D2) carboxylates of alkali metals or alkaline earth metals, in particular sodium acetate, sodium octoate, potassium acetate, potassium octoate, and tin carboxylates, for example tin(II) acetate, tin(II) octoate, tin(II) ethylhexoate, tin(II) laurate, dbutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin acetate, and ammonium carboxylates. Sodium, potassium and ammonium carboxylates are especially preferred. Preferred carboxylates are formates, ethylhexanoates (=octoates) and acetates.

[0046] The catalyst preferably contains one or more catalysts selected from the group consisting of potassium acetate, potassium octoate, pentamethyldiethylenetriamine, N,N,N-tris(dimethylaminopropyl)hexahydrotriazine, tris(dimethylaminomethyl)phenol, bis[2-(N,N-dimethylamino)ethyl] ether and N,N-dimethylcyclohexylamine, particularly preferably from pentamethyldiethylenetriamine, N,N,N-tris(dimethylaminopropyl)hexahydrotriazine and N,N-dimethylcyclohexylamine, particularly preferably from pentamethyldiethylenetriamine, N,N,N-tris(dimethylaminopropyl)hexahydrotriazine and N,N-dimethylcyclohexylamine in combination with potassium acetate, potassium octoate or potassium formate or sodium formate.

[0047] In a preferred embodiment the catalysts required for producing the rigid foam, in particular aminic catalysts (D1) in combination with salts used as trimerization catalysts, are employed in an amount such that for example in continuously producing plants elements having flexible outerlayers can be produced at a rate of up to 80 m/min depending on element thickness.

[0048] The reactivity of the reaction mixture is generally adapted to the requirement using catalyst (or by means of other reactivity-enhancing components, for example aminopolyethers). Production of thin panels thus requires a reaction mixture having a higher reactivity than production of thicker panels. Cream time and fiber time are respectively typical parameters for the time taken for the the reaction mixture to begin to react and for the point at which a sufficiently stable polymer network has been formed. Typical cream times (characterized by commencement of foaming of the reaction mixture upon visual inspection) for processing using conventional techniques are in the range from 2 seconds to 50 seconds.

[0049] The process according to the invention now also allows advantageous processing of reaction mixtures having high or relatively high reactivities, i.e. cream times of <5 s, in particular <2 s, very particularly <1 s, and fiber times of <25 s, in particular <20 s and very particularly <14 s. The process according to the invention may be advantageous in particular for the production of thin panels since little material is available for combination here.

[0050] It is preferable to use a combination of catalyst components D1 and D2 in the reaction mixture. In this case the molar ratio should be chosen such that the D2/D1 ratio is between 0.1 and 80, in particular between 2 and 20. Short fiber times may be achieved for example with more than 0.9% by weight of potassium 2-ethylhexanoate based on all components of the reaction mixture.

[0051] The invention provides that the reaction mixture is applied onto the outerlayer from 7 discharge openings simultaneously. The higher the number of discharge openings, the lower the differences in product quality over the cross section of the obtained composite element (viewed transversely to the direction of movement of the outerlayer). The reaction mixture is preferably applied onto the outerlayer from 8 discharge openings simultaneously, more preferably applied onto the outerlayer from 12 discharge openings simultaneously, yet more preferably from 15 discharge openings.

[0052] The apparatus according to the invention is suitable for performing the process according to the invention. In such an apparatus according to the invention for applying a formable reaction onto a moving outerlayer, wherein the reaction mixture is applied onto the outerlayer from discharge openings, the apparatus comprises 7 discharge openings. The apparatus preferably comprises 8 discharge openings, more preferably 12 and yet more preferably 15 discharge openings.

[0053] The present invention is more particularly elucidated with reference to the figures which follow without, however, being limited thereto. FIG. 1-5 show apparatuses according to the invention performing processes according to the invention.

[0054] One embodiment of the apparatus according to the invention and of the process according to the invention shall be elucidated with reference to FIG. 1. The apparatus according to the invention further comprises: [0055] a plurality of mixing heads 100, 110, 120, wherein each mixing head is adapted for mixing two or more reactant streams to afford one product stream; [0056] a distributor 230, wherein the distributor comprises 7 discharge conduits 300, each of which terminate in a discharge opening 400, the distributor is connected to the product streams from the mixing heads 100, 110, 120 and the distributor is adapted for combining the product streams from the mixing heads 100, 110, 120 and distributing them to its discharge conduits 300 in homogeneous material composition.

[0057] Shown here is an apparatus comprising three mixing heads 100, 110 and 120. Each of these three mixing heads receives a product stream comprising a polyol component ROH and a product stream comprising an isocyanate component RNCO. It will be appreciated that the designations ROH and RNCO do not represent monoalcohols and monoisocyanates but rather generally polyols and polyisocyanates and blowing agents and other additives also present in these reactant streams.

[0058] The mixing heads 100, 110, 120 combine their reactant streams into product streams which are supplied to a distributor 230 connected to the mixing heads. The distributor 230 thus comprises at least as many inlets as there are mixing heads present. The product streams thus contain the foamable reaction mixture. The distributor 230 homogenizes the product stream so that for example differences in the temporal progress of the reaction or temporal differences in the properties of the reactant streams are compensated. Temporal differences in the properties of the reactant streams may be for example differences as a consequence of density variations or of variations in the conveying power of the reactant streams to the mixing heads.

[0059] The geometry of the distributor is preferably chosen such that the distance covered by the homogenized reaction mixture to the outlet conduits is of equal length. It is moreover advantageous when the cross section of the distributor outlets is identical for all distributor outlets. The cross-sections of the distributor inlets may conversely also be different. The material of the distributor may be selected from steel, stainless steel, aluminum and plastics. In each case the selected material must be resistant to the pressures and temperatures prevailing in the mixing head.

[0060] In a preferred embodiment a distributor 230 may for example be constructed such that two distributor heads such as are described for example in EP 1 857 248 A2 ([0023], FIG. 1) under the designation distributor head are connected in series. In this case the first distributor head is traversed in reverse direction, i.e. the product streams arriving from the mixing heads enter the first (reversed) distributor head via the plurality of openings, are homogenized there and exit the distributor head as one product stream which then enters a further distributor head where it is redistributed into a plurality of product streams. This is shown in more detail in FIG. 2.

[0061] The reaction mixture exits the distributor 230 via 7 discharge conduits 300 which each terminate in discharge openings 400. In the embodiment shown in FIG. 1 the distributor has fifteen discharge conduits 300. The discharge conduits 300 may be flexible or rigid, flexible discharge conduits being preferable. The discharge conduits 300 are attached to a securing rail 500, thus fixing the position of the discharge openings 400.

[0062] The reaction mixture exits the individual discharge openings 400 and contacts substantially over its entire width an outerlayer 10 which is moving away from the discharge openings and is represented by its dashed outline. Due to the expansion of the foaming reaction mixture the individual stripes of the reaction mixture combine to form the foam layer 600 on the outerlayer.

[0063] The embodiment of the process according to the invention performable with the apparatus according to the invention discussed hereinabove comprises the steps of: [0064] providing a plurality of mixing heads 100, 110, 120, wherein each mixing head is adapted for mixing two or more reactant streams to afford one product stream; [0065] providing a distributor 230, wherein the distributor comprises 7 discharge conduits 300, each of which terminate in a discharge opening 400, the distributor is connected to the product streams from the mixing heads 100, 110, 120 and the distributor is adapted for combining the product streams from the mixing heads 100, 110, 120 and distributing them to its discharge conduits 300 in homogeneous material composition. [0066] mixing two or more reactant streams in each of the mixing heads 100, 110, 120 to obtain a product stream exiting each of the mixing heads, wherein the product stream comprises a foamable reaction mixture; [0067] combining the product streams in the distributor 230; [0068] distributing the combined product streams to the discharge conduits 300 of the distributor 230; [0069] applying the reaction mixture from the discharge openings 400 of the discharge conduits 300 onto the outerlayer 10.

[0070] The number of mixing heads in these embodiments of the apparatus according to the invention and of the process according to the invention may be 2, 3 (as shown here), 4, 5, 6 or more. The number of discharge conduits per distributor may be 7, 8, 9, 10, 11, 12, 13, 14, 15 (as shown here) or more.

[0071] This embodiment not only compensates for the differences between the original reaction mixtures but also very markedly reduces problems with running and mingling of the rising reaction mixture. This embodiment has the additional advantage that basically only one quality of the reaction mixture need be employed. A further advantage over existing discharging systems is that precise positioning of the discharging streams, both symmetrically and also asymmetrically, is achievable through the use of preferably flexible hoses. This can result in advantages in panel geometry or allows targeted product application, for example into the corrugations of a roofing element. This application methodology may be used for producing metal panel sandwich composite elements, insulation panels and continuous blocks.

[0072] Further embodiments of the apparatus according to the invention and of the process according to the invention shall be elucidated by reference to FIG. 2, FIG. 3, FIG. 4 and FIG. 5. The apparatus according to the invention comprises: [0073] a plurality of mixing heads 100, 110, 120, wherein each mixing head is adapted for mixing two or more reactant streams to afford one product stream; [0074] a distributor 230, wherein the distributor comprises one or more discharge conduits (300), the distributor is connected to the product streams from the mixing heads (100, 110, 120) and the distributor is adapted for combining the product streams from the mixing heads (100, 110, 120) and distributing them to the one or more discharge conduits (300) in homogeneous material composition. [0075] one or more rake applicators 510, 520, wherein the number of rake applicators corresponds to the number of discharge conduits 300 of the distributor 230, each rake applicator is connected to a discharge conduit and each rake applicator has 4 discharge openings (400).

[0076] Rake applicators employable here may, for example, be in the form of individual rake applicators or rake applicator pairs as described in EP 1 857 248 A2, EP 2 614 944 A1 or EP 2 804 736 A1. The feed to the rake applicator(s) may be central or lateral for example.

[0077] FIG. 2, FIG. 3, FIG. 4 and FIG. 5 each show an apparatus comprising three mixing heads 100, 110 and 120. Each of these three mixing heads receives a product stream comprising a polyol component ROH and a product stream comprising an isocyanate component RNCO. It will be appreciated that the designations ROH and RNCO do not represent monoalcohols and monoisocyanates but rather generally polyols and polyisocyanates and blowing agents and other additives also present in these reactant streams.

[0078] The mixing heads 100, 110, 120 combine their reactant streams into product streams which are supplied to a distributor 230 connected to the mixing heads. The product streams thus contain the foamable reaction mixture. The distributor 230 homogenizes the product stream so that for example differences in the temporal progress of the reaction or temporal differences in the properties of the reactant streams are compensated. Temporal differences in the properties of the reactant streams may be for example differences as a consequence of density variations or of variations in the conveying power of the reactant streams to the mixing heads.

[0079] The reaction mixture exits the distributor 230 via discharge conduits 300, each of which terminate in rake applicators 500, 510, 520, 530 having discharge openings 400, 410, 420, 430. In the embodiment shown in FIG. 2 the distributor has three discharge conduits 300, in the embodiment shown in FIG. 3 there are one or more discharge conduits 300, in FIG. 4 there is one discharge conduit which in the exemplary case shown represents a direct connection to a rake applicator 400. In FIG. 5 there are three discharge conduits 300. There may be (FIG. 3) two discharge conduits for example oras in FIG. 5three discharge conduits may also be assigned to three rake applicators or rake applicator pairs or else one discharge conduit may be assigned to one rake applicator or rake applicator pair (FIG. 4). The discharge conduits 300 may be flexible or rigid, flexible outlet conduits being preferable.

[0080] FIG. 5 shows in more detail one possible distributor 230 which homogenizes and redistributes the product streams exiting the mixing heads. In the present case said distributor is constructed such that two distributor heads 231, 232 such as are described for example in EP 1 857 248 A2 ([0023], FIG. 1) under the designation distributor head are connected in series. In this case the first distributor head 231 is traversed in reverse direction, i.e. the product streams arriving from the mixing heads enter the first (reversed) distributor head via the plurality of openings, are homogenized there and exit the distributor head as one product stream which then enters a further distributor head 232 where it is redistributed into a plurality of product streams. If, as in FIG. 3, the product streams are divided into only two product streams/discharge conduits 300 it is also possible simply to employ a conduit branching such as a T-piece or a Y-piece, in particular a T-shaped branching of the discharge conduit, instead of the further distributor head 232. If, as shown in FIG. 4, the product stream is supplied to only one discharge conduit (in this case directly to the rake applicator) the further distributor head 232 may be dispensed with entirely.

[0081] The reaction mixture exits the individual discharge openings 400 of the rake applicators 500, 510, 520, 530 and contacts an outerlayer (not shown) which is moving away from the discharge openings. Due to the expansion of the foaming reaction mixture the individual stripes of the reaction mixture combine to form the foam layer 600 on the outerlayer.

[0082] The embodiment of the process according to the invention performable with the apparatus according to the invention discussed hereinabove further comprises the steps of: [0083] providing a plurality of mixing heads 100, 110, 120, wherein each mixing head is adapted for mixing two or more reactant streams to afford one product stream; [0084] providing a distributor 230, wherein the distributor comprises one or more discharge conduits 300, the distributor is connected to the product streams from the mixing heads 100, 110, 120 and the distributor is adapted for combining the product streams from the mixing heads 100, 110, 120 and distributing them to the one or more discharge conduits 300 in homogeneous material composition. [0085] providing one or more rake applicators 510, 520, wherein the number of rake applicators corresponds to the number of discharge conduits 300 of the distributor 230, each rake applicator is connected to a discharge conduit and each rake applicator has 4 discharge openings (400); [0086] mixing two or more reactant streams in each of the mixing heads 100, 110, 120 to obtain a product stream exiting each of the mixing heads, wherein the product stream comprises a foamable reaction mixture; [0087] combining the product streams in the distributor 230; [0088] distributing the combined product streams to the one or more discharge conduits 300 of the distributor 230; [0089] applying the reaction mixture from the discharge openings 400 of the one or more rake applicators 510, 520 onto the outerlayer.

[0090] The number of mixing heads in these embodiments of the apparatus according to the invention and of the process according to the invention may be 2, 3 (as shown here), 4, 5, 6 or more. The number of rake applicators may be 3 (as shown in FIG. 2), 2 (as shown in FIG. 3), 4, 5, 6 or more. The number of openings per rake applicator may be 4, 5 (as shown here), 6, 7, 8, 9, 10 or more. In a preferred embodiment the apparatus according to the invention comprises 2, 3 or 4 mixing heads and only one rake applicator or one rake applicator pair (as shown in FIG. 4).

[0091] Rake applicators employable here may, for example, be in the form of individual rake applicators or rake applicator pairs as described in EP 1 857 248 A2, EP 2 614 944 A1 or EP 2 804 736 A1. The feed to the rake applicator(s) may be central or lateral for example This application methodology may be used for producing metal panel sandwich composite elements, insulation panels and continuous blocks.

[0092] This embodiment not only compensates for the differences between the original reaction mixtures but also very markedly reduces problems with running and mingling of the rising reaction mixture. This embodiment has the additional advantage that basically only one quality of the reaction mixture need be employed. A further advantage over existing discharging systems is that precise positioning of the discharging streams, both symmetrically and also asymmetrically, is achievable through the use of preferably flexible hoses. This can result in advantages in panel geometry or allows targeted product application, for example into an asymmetrical roof panel.

[0093] It is possible that in the apparatus and the process at least two rake applicators 520 are employed and at least two of the rake applicators 520 are arranged side-by-side viewed transversely to the direction of movement of the outerlayer and arranged one behind the other viewed in the direction of motion of the outerlayer. This arrangement is shown in FIG. 2. The three rake applicators 520 are arranged substantially side-by-side in FIG. 2. The fact that the middle rake applicator has been offset backward somewhat is intended to elucidate the fact that such rake applicators have certain space requirements which can prevent them being positioned directly side-by-side.

[0094] It is likewise possible that in the apparatus and in the process at least two rake applicators 510, 520 are employed and at least two of the rake applicators 510, 520 are arranged directly one behind the other or one behind the other with a slight offset viewed in the direction of motion of the outerlayer so that the reaction mixture discharged from the discharge openings 400 of one rake applicator 510 at least partially contacts reaction mixture discharged from the discharge openings 400 of the other rake applicator 520. This arrangement is shown in FIG. 3. The reaction mixture being discharged from rake applicator 510 in streams may flow between the streams of the other rake applicator 520 to achieve an even better mingling of the streams.

[0095] The reaction mixture exits the individual discharge openings 400, 410, 420 of the rake applicators 500, 510, 520, 530 and contacts substantially over its entire width an outerlayer 10 which is moving away from the discharge openings and is represented by its dashed outline. Due to the expansion of the foaming reaction mixture the individual stripes of the reaction mixture combine to form the foam layer 610, 620, 630 on the outerlayer 10.

[0096] The optional slight offset of the rake applicators with respect to one another depends in its magnitude on the number of rake applicators and the distance between the discharge openings. In a particularly preferred embodiment the offset of the rake applicators with respect to one another is not more than a length corresponding to 50% of the distance between two adjacent discharge openings of the rake applicators. When using three rake applicators 510, 520, 530 one preferred arrangement is that the three rake applicators are each offset with respect to one another by a length corresponding to about of the distance between two adjacent discharge openings 400 of the rake applicators. This arrangement is shown in FIG. 5. The individual stripes of the reaction mixture 710, 720, 730 then recombine to form a foam layer 630.

[0097] In all of the abovementioned discharging systems discharging may be performed in the direction of the belt or counter to the direction of the belt. It may even be advantageous in one embodiment, as shown in one of the figures, when not all rake applicators are positioned at the same angle to the outerlayer.