Two component sealant for cavity filling

Abstract

The present invention relates to a process for sealing a cavity which comprises mixing at least one polyisocyanate (a), at least one polyol (b) comprising graft polyetherols b1) wherein the content of the graft polyetherpolyol (b1) is 30 to 70 % by weight based on the total weight of the polyols (b), at least one blowing agent (c), at least one catalyst (d) and at least one chain ex- tender and / or crosslinking agent (e) and optionally auxiliaries and / or additives to give a reaction mixture introducing the reaction mixture into the cavity and reacting the reaction mixture to give a polyurethane cast in place sealant having a density of 60 to 200 g / liter. The present invention is further directed to a process wherein the reaction mixture is introduced into a cavity formed by wall element and a roof element of a truck trailer and a truck trailer obtained by this process.

Description

[0001] Two component sealant for cavity filling

[0002] Description

[0003] The present invention relates to a process for sealing a cavity-which comprises mixing at least one polyisocyanate (a), at least one polyol (b) comprising graft polyetherols (b1) wherein the content of the graft polyetherpolyol (b1) is 30 to 70 % by weight based on the total weight of the polyols (b), at least one blowing agent (c), at least one catalyst (d) and at least one chain extender and / or crosslinking agent (e) and optionally auxiliaries and / or additives (f) to give a reaction mixture-introducing the reaction mixture into the cavity and reacting the reaction mixture to give a polyurethane cast in place sealant having a free foamed density of 60 to 200 g / liter. The present invention is further directed to a process wherein the reaction mixture is introduced into a cavity formed a wall element and a roof element of a truck trailer and a truck trailer obtained by this process.

[0004] Polyurethane based sealants are well known. So EP 540950 discloses a moisture-curable urethane based sealant made upon a urethane prepolymer and a polyurethane compound. US 3979364 discloses the application of amine terminated polyether in the polyol component of a two component polyurethane composition for the production of surface coatings, caulks and sealants and the effect of the amine terminated polyether polyol as thickening agent for the reaction mixture obtained by mixing the polyol and the isocyanate component.

[0005] US 5810956 discloses a non-foaming, thixotropic two-component polyurethane elastomeric material and its use as cast in place sealant. According to US 5810956 the isocyanate reactive component comprises polyether polyols. Among polyether polyols aliphatic or aromatic amine initiated-polypropylene oxide extended polyols are mentioned. As thixotropic filler fumed silica is mentioned. In the examples Mutranol 29138 is used as amine-initiated polyol which is an amine based polyethertriol.

[0006] In many construction applications larger elements are connected while small gaps remain between these elements. To seal these joints these gaps are filled with a sealing material. Examples are truck trailers where a wall element and a roof element are fixed together and the gap between these elements must be sealed. The sealing material is supposed to be a lightweight material with no or little shrinkage when curing and good adhesion to the wall element as well as to the roof element is necessary. In addition, -the sealing material should show a good elasticity to prevent delamination or the formation of cracks during operation. EP 3 066 142 B1 describes a process for the production of a locally cast polyurethane sealing which can directly applied on a carrier such as a door element.

[0007] It has been object of the present invention to provide a process for sealing cavities especially the cavity between a wall panel and a roof panel of a truck trailer-wherein a lightweight sealing is obtained-and the sealing material shows a good adhesion to the panels-especially to polyurethane rigid foam panels, shows no or a little shrinkage after application and a high elasticity to prevent delamination or crack formation during operation.

[0008] The object is achieved via a process for sealing a cavity-which comprises mixing at least one polyisocyanate (a), at least one polyol (b) comprising graft polyetherols (b1) wherein the content of the graft polyetherpolyol (b1) is 30 to 70 % by weight based on the total weight of the polyols (b), at least one blowing agent (c), at least one catalyst (d) and at least one chain extender and / or crosslinking agent (e) and optionally auxiliaries and / or additives (f) to give a reaction mixture introducing the reaction mixture into the cavity and reacting the reaction mixture to give a polyurethane cast in place sealant having a free foamed density of 60 to 200 g / liter. The present invention is further directed to a process wherein the reaction mixture is introduced into a cavity formed by a wall element and a roof element of a truck trailer and a truck trailer obtained by this process.

[0009] The sealing material according to the present invention is suitable for sealing any cavity. Such cavities can arise when different parts are joined during construction. In a preferred embodiment the parts to be joined which form the cavity to be sealed comprise a polyurethane rigid foam preferably a layer of polyurethane rigid foam resulting in a direct contact of the sealing material and the polyurethane rigid foam.

[0010] An example of a cavity to be sealed is the cavity created during the construction of truck trailer especially truck trailer shells when a wall element such as a wall panel and a roof element such as a roof panel are connected. All wall and roof panels-which are commonly used for the production of truck trailers can be used. Since during operation of the truck trailer movements of the wall panel and the roof panel relative to each other occur-a space or cavity is between the two panels is left to allow these movements. The sealant sealing this cavity-must have a certain elasticity and good adhesion to the panels in order to adsorb such as vibrations and deformations without crack formation or delamination from the panels.

[0011] In a preferred embodiment both the wall panel and the roof panel of the truck trailer are polyurethane sandwich panels comprising a core layer of rigid polyurethane foam. The polyurethane rigid foam layer is preferably covered on the outside and inside by two compact top layers. These outer layers (top layers) may be formed of a polymer material-for example polyurea, polyethylene polystyrene or co-polymers-preferably the outer layers are metal facings-for example steel facings. At the point where the panels are joined-the rigid polyurethane foam is preferably uncovered so that when sealing the cavity with the sealing material according to the invention-a direct contact between the sealing material and the rigid polyurethane foam is formed and the good adhesion is formed between sealant and rigid polyurethane foam.

[0012] The average free foamed density of the polyurethane sealing material according to the present invention is from 60 to 200 g / liter-preferably from more than 80 to 150 g / liter-and in particular from 90 to 120 g / liter.

[0013] The polyisocyanates (a) used to produce the cast in place sealant according to the invention comprise the aliphatic, cycloaliphatic and aromatic di- or polyfunctional isocyanates as known in polyurethane chemistry and also any desired mixture thereof. Examples are members of the methanediphenyldiisocyanate-family (M DI -family) as methanediphenyl 4,4'-diisocyanate (4,4’- MDI) and methanediphenyl 2,4'-diisocyanate (2,4’-MDI). Methanediphenyl 4,4'-diisocyanate and methanediphenyl 2,4'-diisocyanate are also referred to as monomeric MDI Homologues of methanediphenyl diisocyanate having a greater number of rings (polymer MDI) and modified MDI as carbodiimide modified MDI and biuret modified MDI, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), tolulene 2,4- or 2,6-diisocyanate (TDI) and mixtures of the isocyanates are to mention.

[0014] It is preferable to use members of the MDI-family especially mixtures of monomeric MDI and polymeric MDI. The preferably used members of the MDI family comprise in a preferred object of the present invention of up to about 20% by weight, based on the total weight of the MDI, of allophanate- or uretonimine-modified MDI.

[0015] Polyisocyanate component (a) is preferably used in the form of polyisocyanate prepolymers. Said polyisocyanate prepolymers are obtainable by reacting polyisocyanates as described above in stoichiometric excess with polyols and optionally chain extenders and / or cross linkers7to give the isocyanate terminated prepolymer7for example at temperatures of from 30 to 100°C7preferably from about 80°C.

[0016] Polyols are known to the person skilled in the art and are described by way of example in “Polyurethane Handbook”, Carl Hanser Publishers, 2nd edition 1993, chapter 3.1. It is preferable here to use-as polyols polyetherols as described in (b) especially polyetherols containing pro- pyleneoxide7more preferred polypropyleneoxide. Conventional chain extenders or crosslinking agents are optionally added to the polyols for the production of the isocyanate prepolymers. These substances are described under (e) below.

[0017] The isocyanate content of the isocyanate terminates prepolymer is preferably in the range of 5 to 45 % by weight-more preferred 15 to 30 and most preferred 22 to 29% by weight.

[0018] Polyols (b) according to the present invention usually have a molecular weight of at least 250 g / mol and an isocyanate functionality calculated from the functionality of the starter molecule of at least 2. Polyols (b) comprise at least one graft polyetherpolyol (b1). In addition to the graft polyetherol (b1) polyols (b) may comprise one or more alcohol initiated polyetherols (b2) and one or more aliphatic amine initiated polyetherols (b3).

[0019] Graft polyetherpolyols (b1) are also known as polymer-modified polyetherols or polymer polyetherol. Graft polyetherols (b1) usually have from 5 to 60% by weight content of preferably thermoplastic polymers preferably from 10 to 55% by weight particularly preferably from 30 to 55% by weightand in particular from 40 to 50% by weight. These polymer polyetherols are described by way of example in WO 05 / 098763 and EP-A-250 351 and are usually produced via free-radical polymerization of suitable olefinic monomers such as styrene, acrylonitrile, (meth)acrylates, (meth)acrylic acid-and / or acrylamide-in a polyetherol serving as graft base. Such graft base polyetherols may be polyetherols as disclosed below as alcohol initiated polyetherols (b2). The polymer polyetherol comprises-alongside the graft copolymers mainly the homopolymers of the olefins-dispersed in unaltered polyetherol.

[0020] In one preferred embodiment-the monomers used comprise acrylonitrile-or styrene preferably acrylonitrile and styrene. The monomers are optionally polymerized in the presence of further monomers of a macromer i.e. of an unsaturated polyol capable of free-radical polymerization and with use of a free-radical initiator, -mostly azo compounds or peroxide compounds in a polyesterol or polyetherol as continuous phase. This process is described by way of example in DE 111 394, US 3 304 273, US 3 383 351 , US 3 523 093, DE 1 152 536 and DE 1 152 537.

[0021] During the free-radical polymerization reaction the macromers are concomitantly incorporated into the copolymer chain. This gives block copolymers having a polyether block and a polyacry- lonitrile-styrene block. These act as compatibilizers at the interface between continuous phase and disperse phase and suppress agglomeration of the polymer polyesterol particles. The proportion of the macromers is usually from 1 to 20% by weight based on the total weight of the monomers used to produce the polymer polyol. The amount of the graft polyetherols (b1) comprised based on the total weight of component (b) is 30 to 70 % by weight and preferably 40 to 60 % by weight based on the total weight of the polyols (b).

[0022] Alcohol initiated polyetherols (b2) are produced by known processes for example by anionic polymerization using alkali metal hydroxides or alkali metal alcoholates as catalysts and with addition of at least one starter molecule which comprises from 2 to 4 preferably 2 to 3, reactive hydrogen atoms or by cationic polymerization using Lewis acids such as antimony pentachloride or boron fluoride etherate from one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene moiety. Examples of suitable alkylene oxides are tetra hydrofuran, propylene 1 ,3-oxide, butylene 1 ,2- or 2,3-oxide and preferably ethylene oxide and propylene 1 ,2-oxide. Other catalysts that can be used are multimetal cyanide compounds known as DMC catalysts. The alkylene oxides can be used alone in alternating succession or in the form of a mixture. Preference is given to use mixtures of propylene 1 ,2-oxide and ethylene oxide where in a preferred embodiment amounts of from 5 to 50% based on the total amount of alkylene oxides ethylene oxide is used as ethylene oxide end block ("EO cap") so that the resultant polyols have more than 70% of primary OH end groups.

[0023] A starter molecule that can be used is water or di- or trihydric alcohols such as ethylene glycol, 1 ,2- or 1 ,3-propanediol, diethylene glycol, dipropylene glycol, 1 ,4-butanediol, glycerol or trimethylolpropane. The OH-number of the at least one alcohol initiated polyetherpolyol (b2) preferably is 15 to 200 mg KOH / g more preferred 25 to 100 mg KOH / g and especially preferred 30 to 60 mg KOH / g. In a preferred embodiment the alcohol initiated polyetherols (b2) comprise at least one propylene glycol having a hydroxyl number of 40 to 60 mg KOH / g and at least one polyetherpolyol obtained from a trifunctional starter molecule having a hydroxyl value of 25 to 50 mg KOH / g.

[0024] The content of the alcohol initiated alkoxylation product (b2) is preferably 10 to 50 wt.-% more preferably 15 to 45 wt.-% and most preferably 25 to 40 wt.-% based on the total weight of the components (a) to (f).

[0025] Aliphatic amine initiated polyetherols (b3) preferably has an OH-number of 400 to 1000 mg KOH / g more preferably 450 to 900 mg KOH / g and especially preferred 500 to 800 mg KOH / g. The OH-functionality of the alkoxylated amine (b3) is 4. Alkoxylated amines (b3) are usually produced by alkoxylation of diamines by a known method. Preferably diamines as ethylenediamine, propylendiamine, butylendiamine, pentylendiamine, hexylendiamine, isophorondiamine, hexamethylenediamine (HAD) and hydrogenated methylenediphenylenediamine (H12MDA) most preferably ethylenediamine is used as amine starter. As alkylene oxides one or more al- kylene oxides having from 2 to 4 carbon atoms in the alkylene moiety can be used. Examples of suitable alkylene oxides are tetra hydrofuran, propylene 1 ,3-oxide, butylene 1 ,2- or 2,3-oxide and preferably ethylene oxide and propylene 1 ,2-oxide. In an especially preferred embodiment only propylene 1 ,2-oxide is used as alkoxylation agent.

[0026] The content of the aliphatic amine initiated alkoxylation product (b3) is preferably 0.1 to 10 wt.- % more preferably 1 to 8 wt.-% and most preferably 2 to 6 wt.-% based on the total weight of the components (a) to (f).

[0027] In a preferred embodiment polyols (b) comprise less than 20 % by weight, more preferred less than 10 % by weight, even more preferred less than 5 % by weight, based on the total weight of the polyols (b), of polyesterpolyols. In an especially preferred embodiment the polyols (b) and therefore the reaction mixture to produce the polyurethane cast in place sealant are free of polyesterpolyols.

[0028] The average functionality of the polyols (b), is preferably from 2.0 to 3.5, more preferred 2.5 to 3.0 and an average hydroxyl number is from 20 to 160 mg KOH / g, more preferred 25 to 90 mg KOH / g and most preferred 30 to 80 mg KOH / g. This ensures that a foam with sufficient flexibility is obtained.

[0029] The reaction mixture to produce the cast in place sealant according to the present invention comprises blowing agents (c). Said blowing agents (c) preferably comprise water. Blowing agents (c) that can be used may comprise well-known compounds having chemical and / or physical effect or mixtures of these blowing agents. Chemical blowing agents are compounds which use reaction with isocyanate to form gaseous products, an example being water or formic acid. Physical blowing agents are compounds which have been emulsified or dissolved in the starting materials for polyurethane production and which vaporize under the conditions of polyurethane formation. By way of example these involve hydrocarbons, halogenated hydrocarbons and other compounds-for example perfluorinated alkanes such as perfluorohexane, chlorofluorocarbons and ethers, esters, ketones, acetals and mixtures thereof for example cycloaliphatic or aliphatic hydrocarbons having from 4 to 8 carbon atoms or fluorocarbons such as Sol- kane® 365 mfc from Solvay Fluorides LLC. A preferred embodiment uses as blowing agent a mixture comprising at least one of said blowing agents and water and in particular water as sole blowing agent.

[0030] In one preferred embodiment the content of water is from 0.1 to 2% by weight, preferably from 0.2 to 1 .5% by weight, particularly preferably from 0.3 to 1.2% by weight, in particular from 0.4 to 1% by weight, based on the total weight of components (a) to (f). As catalysts (d) conventional catalysts as known in the field of production of polyurethanes can be applied. Mentioned may be by way of example tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl-, and N-cyclohexylmorpholine, N,N,N',N'- tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, N,N,N',N'- tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethylether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1 ,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane, 1,4-diazabicyclo[2.2.2]octane and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine and dimethylethanolamine. Particularly suitable are aliphatic amines such as Bis(2- dimethylaminoethyl)methylamine in contents of 0.05 wt.% to 0.5 wt.%. In addition Benzyldimethylamine in contents of 0.1 wt.% to 1.0 wt.% and / or heterocyclic organic nitrogen compounds such as 1 -Methylimidazole in percentages of 0.1 wt.% to 1.0 wt.% are particularly suitable.

[0031] Usually catalysts are applied in an amount of 0.01 to 2 % by weight, preferably 0.1 to 1 % by weight, each based on the total weight of components (a) to (f).

[0032] Chain extenders and / or crosslinking agents (e) used comprise substances with a molar weight that is preferably smaller than 500 g / mol, particularly preferably from 60 to 400 g / mol, more preferably from 60 to less than 250 g / mol, where chain extenders have 2 hydrogen atoms reactive toward isocyanates and crosslinking agents have 3 hydrogen atoms reactive toward isocyanate.

[0033] Chain extenders and / or crosslinking agents (e) can be used individually or preferably in the form of a mixture. It is preferable to use diols and / or triols with the molecular weights smaller than 400 particularly preferably from 60 to 300 and in particular from 60 to 150. Examples of chain extenders and crosslinking agents that can be used are aliphatic, cycloaliphatic, and / or arali- phatic diols having from 2 to 14, preferably from 2 to 10, carbon atoms, for example ethylene glycol, 1,3-propanediol, 1 ,10-decanediol, 1,2-, 1,3-, 1,4-dihydroxycyclohexane, diethylene glycol, dipropylene glycol and preferably 1,4-butanediol, 1,6-hexanediol and bis(2- hydroxyethyl)hydroquinone, triols such as 1,2,4- or 1,3,5-trihydroxycyclohexane, glycerol and trimethylolpropane and low-molecular-weight hydroxylated polyalkylene oxides based on ethylene oxide and / or based on propylene 1,2-oxide and on the abovementioned diols and / or triols as starter molecules. In one preferred example propoxylated trithanolamine can be used as chain extender. In this case also the amount of compound (c) applied can be lowered. In a preferred embodiment the crosslinking agents comprise an amine cross linking agent like polymeric amines such as the reaction product of di-, tri- and tetra-propoxylated propane-1, 2-diol with ammonia. If present, the content of the amine crosslinking agent is preferably 1 to 10 % by weight, more preferably 2 to 8 and especially 3 to 6 % by weight, each based on the total weight of compounds (b) to (e).

[0034] If chain extenders and / or crosslinkers are used they can be applied in an amount of 1 to 20 % by weight preferable 2 to 15 % by weight and especially preferred 4 to 10 % by weight, each based on the total weight of the components (b) to (e).

[0035] The auxiliaries and additives (f) comprise catalysts, surface-active substances, flame retardants, reinforcing materials and anti-sagging materials, bonding agents, UV stabilizers, antioxidants, dyes, pigments and hydrolysis inhibitors and also fungistatic and bacteriostatic substances. Preferred additives are pigments, bonding agents, UV stabilizers, antioxidants and / or reinforcing materials. These substances are known in polyurethane and polyurea production.

[0036] As reinforcing materials and anti-sagging are the conventionally known inorganic reinforcing materials or fillers having a particle diameter of usually greater than 10 pm preferably from 50 pm to 50 mm can be used. Here the particle diameter is the longest axis. In the case of chopped glass fibers for example the “particle diameter” according to the present invention would be the length of the fibers. Specific examples which may be mentioned as fillers or reinforcing material are: inorganic fillers such as siliceous minerals for example sheet silicates such as antigorite, bentonite, serpentine, hornblendes, amphiboles, chrysotile and talc, metal oxides such as kaolin, aluminum oxides, titanium oxides, zinc oxide and iron oxides, metal salts such as chalk and barite and inorganic pigments such as cadmium sulfide, zinc sulfide and also glass, etc.. Preference is given to use kaolin (China Clay), aluminum silicate, fumed silica and copracipitates of barium sulfate and aluminum silicate and glass fibers especially fumed silica. Most preferably used as filler and anti-sagging agent is fumed silica.

[0037] The inorganic reinforcing materials and anti-sagging materials can be used individually or as mixtures and advantageously is added to the reaction mixture in amounts of from 0.5 to 50% by weight, preferably from 1 to 30% by weight, more preferably 1 ,5 to 15 by weight and especially 2 to 10 % by weight, based on the weight of the components (a) to (e). If only fumed silica is used as filler for anti-sagging in a preferred version, fumed silica is preferably added in an amount of 0.5 to 10 % by weight, more preferred 1 to 6 % by weight and especially preferred 2 to 5 % by weight.

[0038] To seal the cavity and to produce the polyurethane cast in place sealant according to the invention the components (a) to (f) are preferably mixed at temperatures of from 10 to 90°C particularly preferably from 15 to 70°C and in particular from 20 to 50°C. In a preferred embodiment components (b) to (f) are premixed to form the so-called polyol component and then in a second step mixed with the polyisocyanate (a). This mixture is then introduced into the cavity to be filled foamed and cured to form the cast in place polyurethane sealant. In case that the cavity to be sealed is a cavity between a wall panel and a roof panel of a truck trailer the reaction mixture according to the present invention is preferably introduced into the cavity with an application machine which continuously introduces the reaction mixture into the gap formed between wall element and roof element.

[0039] The mixing ratios are selected so that the equivalence ratio of NCO groups of the polyisocyanates (a) to the sum of the reactive hydrocarbon atoms of the components (b) and optionally (c) and (d) is 08 to 1.5:1 preferably 0.95 - 1.3:1 and more preferably 1.0 to 1.1 : 1.

[0040] For the purposes of the invention, the mixture of the components (a) to (d) and if present (e) to (g) at reaction conversions of less than 90%, based on the isocyanate groups, will be referred to as reaction mixtures.

[0041] A further object of the present invention is a cavity sealed by a process according to the present invention and a cast in place sealant obtainable according to a process of the present invention. In an especially preferred embodiment of the invention the process according to the present invention is characterized in that the reaction mixture is introduced into a cavity formed by a wall element and a roof element of a truck trailer more preferred wherein the wall element and the roof element comprise a core layer of rigid polyurethane foam. In a further preferred embodiment the present invention is directed to a truck trailer obtainable according to a process according to the present invention.

[0042] The polyurethane cast in place sealants according to the present invention show outstanding mechanical properties at low free foamed density. Furthermore a low compression set, a high tensile strength, a high tear strength and a good elongation. Further the cast in place sealant can be easily obtained and shows good reaction properties as a long open time, a good antisagging behaviour even at vertical surfaces and a short cream time allowing fast curing after application. The obtained cast in place sealant further shows fine and uniform foam cells and a very smooth surface and good haptics. Finally the cast in place sealant can be easily applied into the cavity and the reaction mixture shows a viscosity profile which prevents draining of the reaction mixture after application and before hardening.

[0043] The invention is illustrated below with the aid of examples. Examples:

[0044] The parameters of the present invention were determined according to the following standards:

[0045] The hydroxyl values were determined in accordance with DIN 53420.

[0046] The overall densities were determined in accordance to DIN EN ISO 845.

[0047] The mechanical properties like tensile strength, elongation and tear strength were determined in accordance with DIN EN ISO 1798 respectively DIN ISO 34-1 , B (b).

[0048] The compression set was determined according to DIN EN ISO 1856 (method A).

[0049] Start time was determined in a cup test and is the time when the increase in foam volume begins.

[0050] Fiber time was determined in a cup test and describes the transition from a liquid to a solid state.

[0051] Rise time was determined in a cup test and is the time when the increase in foam volume ends.

[0052] Tack free time was determined in a cup test by touching the surface of the foam and corresponds to the time which is needed until the surface is dry, smooth and tack free.

[0053] Tack free time under manual pressure was determined in a cup test by touching the surface with manual pressure through the foam surface and corresponds to the time which is needed until the internal foam structure under the skin of the foam is dry and tack free.

[0054] Free rise density was determined in a cup test.

[0055] The following substances were used for producing the examples:

[0056] Polyol 1 : Polypropylene glycol with OH number of 55 mg KOH / g

[0057] Polyol 2: Polyetherpolyol with OH number of 35 mg KOH / g, based on ethylene oxide and propylene oxide with glycerol as starting material

[0058] Polyol 3: Polyetherpolyol grafted with styrene-acrylonitrile (SAN) with OH number of 20 mg KOH / g and based on ethylene oxide and propylene oxide with glycerol as starting material Polyol 4: Polyetherpolyol with OH number of 42 mg KOH / g, and based on ethylene oxide and propylene oxide with glycerol as starting material

[0059] Polyol 5: Polyetherpolyol with OH number of 740 mg / g, and based on ethylene diamine and propylene oxide

[0060] Foam stabilizer 1 : Polydimethylsiloxan

[0061] Foam stabilizer 2: Silicon glycol copolymer

[0062] Foam stabilizer 3: Polyestermodified polysiloxane

[0063] Amin based catalyst 1 : Methylbis(2- dimethylaminoethyl)amine

[0064] Amin based catalyst 2: Triethylendiamin in dipropylene glycol

[0065] Amin based catalyst 3: N,N-Dimethylbenzylamine

[0066] Polyamine 1 : Polymeric Amin, reaction products of di-, tri- and tetra-propoxylated propane-1, 2-diol with ammonia

[0067] Fumed silica: Silicon dioxide obtained by chemical process

[0068] Polyisocyanate: 1 ,1'-Methylenebis(4-isocyanatobenzene) and oligomeric reaction products of 1 ,1'-methylenebis(4-isocyanatobenzene), oxydipropanol and oligomers of oxydipropanol having an NCO content of 22,9 % by weight

[0069] Example 1 and comparative examples 1 to 3 are prepared using the ingredients as specified in table 1. Polyols, water, catalysis, foam stabilizer and fumed silica are premixed to give a polyol component. The amounts of the respective ingredients are given in table 1 in percent by weight. Polyol component and isocyanate are mixed in a cup at an isocyanate index of 105. For producing test plates, the reactive polyurethane mixture will be filled in a mould. After 24 h at 23°C and 50% relative humidity the mechanical properties were determined. table 1

[0070] Especially for the long bonding periods required in the application a good adjustment of blowing and gelling reaction is required. Polyol component and isocyanate mixed in a cup according to example 1 is shrinkage-free and shows that tack free time and in particular tack free time under manual pressure is noticeably extended with a suitable proportion of graft-polyetherpolyol. Furthermore, the foaming adhesive in the low-density range according to the invention allows squeezing. Tensile strength and compression set meet the requirements for sealing a cavity according to the invention described. Compared to example 1 all other comparative examples show surprisingly shrinkage, significantly lower tensile strength, faster tack free times and tack free times under manual pressure and in particular higher compression set and herewith a significantly lower reset.

Claims

Claims1. A process for sealing a cavity which comprises mixing a) at least one polyisocyanate b) at least one polyol comprising graft polyetherol b1) wherein the content of the graft polyetherpolyol (b1) is 30 to 70 % by weight based on the total weight of the polyols (b) c) at least one blowing agent d) at least one catalyst and e) at least one chain extender and / or crosslinking agent and f) optionally auxiliaries and / or additives to give a reaction mixture introducing the reaction mixture into the cavity and reacting the reaction mixture to give a polyurethane cast in place sealant having a free foamed density of 60 to 200 g / liter.

2. Process according to claim 1 characterized in that the polyols b) in addition to graft polyetherol b1) comprise at least one alcohol initiated polyetherols b2) and at least one aliphatic amine initiated polyetherpolyols b3).

3. Process according to claim 1 or 2 characterized in that the graft polyol dispersion of a styrene acrylonitrile copolymer in a polyetherpolyol wherein the graft polyol (b1) has a styrene acrylonitrile content of 10 to 55 % by weight based on the total weight of the graft polyol (b1).

4. Process according to any of claims 2 or 3 characterized in that the alcohol initiated polyetherols b2) comprises polypropylene glycol.

5. Process according to any of claims 2 to 4 characterized in that the aliphatic amine initiated polyetherpolyol (b3) is an alkoxylation product of an aliphatic diamine having an OH-number of 400 to 1000 mg KOH / g and a functionality of 4.

6. Process according to any of claims 2 to 5 characterized in that the aliphatic amine initiated alkoxylation product (b3) is the alkoxylation product of ethylendiamine.

7. Process according to any of claims 1 to 6 characterized in that the blowing agent (c) comprises water.

8. Process according to any of claims 1 to 7 characterized in that the catalysts (d) comprise N,N-Dimethylbenzylamin.

9. Process according to any of claims 1 to 8 characterized in that the chain extender and / or crosslinking agents (e) comprise an amine crosslinking agent.

10. Process according to claim 9 characterized in that the chain extender and / or crosslinking agents (e) comprise the reaction products of di-, tri- and tetra-propoxylated propane-1 ,2- diol with ammonia.

11. Process according to any of claims 1 to 10 characterized in that the auxiliaries and additives (f) comprise 0.5 to 10 weight- % based on the total weight of the components (b) to (f) fumed silica.

12. Process according to any of claims 1 to 11 characterized in that the polyisocyanate (a) comprises at least one prepolymer obtained by the reaction of a stoichiometric excess of aromatic isocyanates with polyether polyols.

13. Process according to any of claims 1 to 12 characterized in that the reaction mixture is introduced into a cavity formed by a wall element and a roof element of a truck trailer wherein the wall element and the roof element comprise a core layer of rigid polyurethane foam.

14. Truck trailer obtained by a process according to claim 13.

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