Water-resistant polyurethane foams

Abstract

A water resistant polyurethane foam composition comprising the reaction product of: an isocyanate component comprising, in weight percent (wt%), from 65 wt% to 85 wt% of a polymeric MDI blend, from 10 wt% to 35 wt% of a plasticizer, and from 0.2 wt% to 2 wt% of a cell opener; and an isocyanate-reactive component containing, in wt%, 20 to 50 wt% of a copolymer polyol, 15 to 60 wt% of a polyether polyol having a functionality of 3 to 8, 1 to 10 wt% of a tertiary amine catalyst, 1 to 10 wt% of a polyetheramine crosslinking agent having a number average molecular weight of 1 kDa or more, 1 to 8 wt% of a foam stabilizer, and 5 to 15 wt% of a blowing agent, the isocyanate-reactive component containing, in wt%, 20 to 50 wt% of a copolymer polyol, 15 to 60 wt% of a polyether polyol having a functionality of 3 to 8, 1 to 10 wt% of a tertiary amine catalyst, 1 to 10 wt% of a polyetheramine crosslinking agent having a number average molecular weight of 1 kDa or more.

Description

Technical Field

[0001] The present invention relates to multi-component polyurethane foam-forming compositions and methods for preparing water-resistant polyurethane foams. Background Art

[0002] Polyurethane foams have been used in the automotive and other industries for a variety of purposes, including various cavity-filling applications. For example, foams are often inserted into hollow vehicle parts to dampen sound and vibration and seal the parts against penetration by water and other fluids. These foams are typically formed by combining reactive polyurethane foam-forming components, applying the resulting composition to the assembled part, and allowing the formulation to foam within the cavities present in the part. In practice, part cavities are filled by applying the foam-forming composition during assembly, which is facilitated by components that are easy to mix, dispense, and cure quickly at moderate temperatures.

[0003] Polyurethane foam is used to seal and insulate parts that encounter various operating conditions, such as the environment below the vehicle's waterline. Common below-waterline cavities are located beneath the seatbelt tracker mechanism and / or the lower portion of the structural pillar. When exposed to water during the vehicle's life, cavities containing hydrophilic foam can retain moisture, leading to metal corrosion, biofilm formation, and unpleasant odors. Summary of the Invention

[0004] In one aspect, embodiments of the present disclosure are directed to a water-resistant polyurethane foam composition comprising the reaction product of an isocyanate component comprising, by weight percent (wt %), 65 to 85 wt % of a polymeric MDI blend, 10 to 35 wt % of a plasticizer, and 0.2 to 2 wt % of a cell opener; and an isocyanate-reactive component comprising, by weight percent, 20 to 50 wt % of a copolymer polyol, 15 to 60 wt % of a polyether polyol having a functionality of 3 to 8, 1 to 10 wt % of a tertiary amine catalyst, 1 to 10 wt % of a polyetheramine crosslinker having a number average molecular weight of 1 kDa or greater, 1 to 8 wt % of a foam stabilizer, and 5 to 15 wt % of a blowing agent.

[0005] In another aspect, embodiments of the present disclosure are directed to a method comprising inserting a solid thermally expandable polyolefin composition into a cavity, and performing a thermal expansion step by heating the thermally expandable polyolefin composition in the cavity to a temperature sufficient to expand the polyolefin composition to form a foam that fills at least a portion of the cavity. DETAILED DESCRIPTION

[0006] The compositions disclosed herein include water-resistant polyurethane foams, foam-forming compositions, and methods for producing and applying foams. The water-resistant polyurethane foam-forming compositions may include one or more of a polyol, a high molecular weight cross-linking agent, and a surfactant that increases the hydrophobicity of the foam and reduces water absorption. In particular, the combination of a high molecular weight (i.e., greater than 1 kDa) cross-linking agent and a specific cell opener is essential for preparing PU foams with low water absorption and foam stability. At the same time, phase separation does not occur in the polyol portion.

[0007] The polyurethane foam composition can be water-resistant, thereby minimizing absorption in applications where humidity and direct water exposure may occur. For example, the water-resistant polyurethane foams disclosed herein can be used to fill cavities in structural components (e.g., below the waterline in an automotive cavity to reduce noise and vibration), which also prevents water ingress and reduces corrosion and mold growth. In particular, the polyurethane foam-forming composition can be used to produce a water-resistant foam that absorbs less than 15 wt% or less than 8 wt% water by weight (wt%) when exposed to 100% relative humidity for 10 days.

[0008] The polyurethane foam compositions disclosed herein generally comprise a product obtained by combining the following two-component curable compositions: an isocyanate component ("A-side") and an isocyanate-reactive component ("B-side"). During application, the isocyanate component and the B-side are mixed, initiating a curing reaction at room temperature and forming the polyurethane foam composition. The polyurethane foam composition may also include one or more polyurethane foam fillers in the isocyanate component and / or the B-side to enhance heat transfer properties.

[0009] A.) Isocyanate component

[0010] The isocyanate component may contain one or more isocyanates or polyisocyanates; linear and / or branched plasticizers; and foam stabilizers and / or other surfactants.

[0011] Isocyanate can include any polyurethane foam in those polyurethane foams for the preparation of polyurethane foam known in the art, such as difunctional monomers, oligomers and prepolymers.Isocyanate can include aliphatics, alicyclics, aromatic aliphatics and aromatic isocyanates having an isocyanate functionality greater than 2, such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), including its oligomers and polymers, "rough" or polymerization MDI (polymethylene polyphenylene polyisocyanate), the variant of the MDI containing urethane, allophanate, urea, biuret, carbodiimide, uretonimine and / or isocyanurate groups. The example of polyisocyanates modified through carbodiimide and / or uretonimine is described in USP 6,765,034, which is incorporated herein by reference in its entirety.

[0012] The isocyanate component may also include one or more isocyanate prepolymers produced by reacting an isocyanate-reactive compound with a molar excess of an isocyanate-containing compound or a polyisocyanate compound under conditions that do not result in gelation or curing. The formation of isocyanate prepolymers is known in the art and may include reacting (1) at least one isocyanate compound and (2) at least one polyol compound. Examples of commercial isocyanates include, but are not limited to, VORANATE, all available from The Dow Chemical Company under the trade name VORANATE. TM 、PAPI TM and ISONATE TM , such as VORANATE TM M 220 or PAPI TM 20 of polyisocyanate.

[0013] Isocyanate prepolymers and polyisocyanates can be described by an isocyanate index, which is defined as the ratio of isocyanate groups to isocyanate-reactive groups (such as OH groups) multiplied by 100. The isocyanate prepolymers disclosed herein may have an isocyanate index in the range of 60 to 300, 75 to 300, or 100 to 200. For isocyanates, the isocyanate value (NCO value) measured by ASTM D5155-19 may be 10% or greater, 15% or greater, or 18% or greater. The average isocyanate equivalent weight of the isocyanate may be 80 g / eq to 400 g / eq, such as a lower limit of 80 g / eq, 90 g / eq, or 100 g / eq to an upper limit of 400 g / eq, 390 g / eq, or 380 g / eq.

[0014] In terms of weight percent (wt %), the isocyanate component may include 50 wt % or greater, such as 50 wt % to 95 wt %, 60 wt % to 90 wt %, or 65 wt % to 85 wt % of one or more isocyanates.

[0015] The isocyanate component may include one or more plasticizers, including one or more branched and / or linear plasticizers. In some cases, the one or more plasticizers may include a blend of branched and linear plasticizers, wherein the linear plasticizer is present at 25 wt% or greater, 30 wt% or greater, or 45 wt% or greater, based on the weight percentage of the total plasticizer.

[0016] Suitable plasticizers are various carboxylic acid ester compounds such as di(2-ethylhexyl) phthalate, diisononyl phthalate, di(n-butyl) phthalate, butyl benzyl phthalate, diisodecyl phthalate, diethyl phthalate, diisobutyl phthalate, di-n-hexyl phthalate, trimethyl trimellitate, tri(2-ethylhexyl) trimellitate, tri(n-octyl, n-decyl) trimellitate, tri(heptyl, nonyl) trimellitate, n-octyl trimellitate, di(2-ethylhexyl) adipate, dimethyl adipate, monomethyl adipate, dioctyl adipate, dibutyl sebacate, dibutyl maleate, diisobutyl maleate, various benzoates, various vegetable oils and modified The present invention also includes but is not limited to epoxidized vegetable oils (such as epoxidized vegetable oils), various sulfonamides (such as N-ethyltoluenesulfonamide, N-(2-hydroxypropyl)benzenesulfonamide, N-(n-butyl)benzenesulfonamide (DOA)), various phosphates (such as tricresyl phosphate and tributyl phosphate), glycol esters (such as triethylene glycol dihexanoate and tetraethylene glycol diheptanoate), polybutene polymers, various acetylated monoglycerides, alkyl citrates (such as triethyl citrate, acetyl triethyl citrate, tributyl citrate, trioctyl citrate, acetyl trioctyl citrate, acetyl trihexyl citrate, butyryl trihexyl citrate, etc.); alkyl sulfonic acid phenyl esters, 1,2-cyclohexanedicarboxylic acid diesters, such as 1,2-cyclohexane diisononyl ester, etc.

[0017] The isocyanate component may include, by weight percentage (wt %), one or more plasticizers in an amount ranging from 5 wt % to 40 wt %, from 10 wt % to 40 wt %, or from 10 wt % to 35 wt %.

[0018] The isocyanate component may include at least one surfactant, which may be the same as or different from the isocyanate-reactive component surfactant(s).

[0019] Examples of foam stabilizing surfactants include nonionic surfactants and wetting agents such as those prepared by sequentially adding propylene oxide and then ethylene oxide to propylene glycol, solid or liquid organosilicones, and polyethylene glycol ethers of long chain alcohols. Ionic surfactants such as tertiary amine or alkanolamine salts of long chain alkyl acid sulfates, alkyl sulfonates, and alkylaryl sulfonic acids may also be used. Surfactants prepared by sequentially adding propylene oxide and then ethylene oxide to propylene glycol are preferred, as are solid or liquid organosilicones. Examples of useful organosilicone surfactants include commercially available polysiloxane / polyether copolymers such as those from of B8935, B8871 and B8934, DABCO available from Air Products TMDC-198, and NIAX from Momentive Performance Materials TM L2171 surfactant.

[0020] The isocyanate component may include, by weight percentage (wt %), one or more surfactants in an amount ranging from 0.1 wt % to 4 wt %, 0.2 wt % to 4 wt %, or 0.2 wt % to 2 wt %.

[0021] B.) Isocyanate Reactive Components

[0022] The isocyanate reactive component (or B-side) may contain one or more of a copolymer polyol, a polyether polyol, a tertiary amine catalyst, a high molecular weight polyetheramine crosslinker, a cell opener, a blowing agent, and other additives.

[0023] The isocyanate reactive component may comprise one or more copolymer polyols (or neat modified polyols), including products obtained by graft polymerization of one or more vinyl monomers (e.g., styrene, acrylonitrile) as a mixture with a polymer polyol (e.g., polyether polyol). Copolymer polyols may also include graft polymerization products produced by the reaction of polyisocyanates and amino or hydroxy compounds (e.g., triethanolamine) as a mixture with a polymer polyol.

[0024] By weight percentage (wt%), isocyanate reactive components can comprise one or more copolymer polyols in the scope of 15wt% to 60wt%, 20wt% to 60wt% or 20wt% to 50wt%.Copolymer polyol can comprise 40% or the dispersion of bigger polymer in aqueous solvent, such as 5% to 50%.The particle diameter of dispersed copolymer polyol can be less than 50 microns.Copolymer polyol can have the hydroxyl value of 10mg KOH / g to 50mg KOH / g as measured by ASTM D4274-21 scope.In some embodiments, copolymer polyol can comprise the grafted polyether polyol of the copolymerization styrene that contains at least 40wt% and acrylonitrile solid, and has 20mg KOH / g or bigger hydroxyl value.

[0025] The isocyanate-reactive component may include one or more polyether polyols, such as the reaction product of an alkoxide (eg, ethylene oxide and / or propylene oxide) and one or more polyol initiators.

[0026] The polyol initiator can have a functionality of 2 to 8, or 3 to 8, and an average hydroxyl number in the range of 100 to 850 mg KOH / g, or 200 to 650 mg KOH / g as determined by ASTM D4274-21.

[0027] The one or more polyols may have a viscosity of at least about 500 cP at 25° C., as measured according to ASTM D455. In some embodiments, a higher viscosity of at least about 2,000 cP may be preferred. Preferably, the one or more polyols have an average molecular weight of 100 to 10,000, more preferably 200 to 5,000.

[0028] Suitable initiators of the present invention include: polyols, such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol and sucrose; polyamines, such as ethylenediamine, toluenediamine, diaminodiphenylmethane and polymethylenepolyphenylenepolyamine; and amino alcohols, such as ethanolamine and diethanolamine; and mixtures of such initiators. Other suitable polyols include polyesters obtained by condensation of diols and higher functionality polyols with polycarboxylic acids in appropriate proportions. Further suitable polyols include hydroxyl-terminated polythioethers, polyamides, polyesteramides, polycarbonates, polyacetals, polyolefins and polysiloxanes. Further suitable isocyanate-reactive components include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, glycerol, trimethylolpropane, ethylenediamine, ethanolamine, diethanolamine, triethanolamine and the other initiators mentioned above. Mixtures of such isocyanate-reactive components may also be used.Most preferably, polyols are used which do not comprise primary, secondary or tertiary nitrogen atoms.

[0029] In terms of weight percent (wt %), the isocyanate-reactive component can include one or more polyether polyols in an amount ranging from 10 wt % to 65 wt %, from 10 wt % to 60 wt %, or from 15 wt % to 60 wt %.

[0030] The isocyanate-reactive component may include one or more tertiary amine catalysts, which function to promote the reaction between the polyol and the isocyanate. Suitable tertiary amine catalysts may include N-alkylmorpholines, N-alkylalkanolamines, amino alcohols, N,N-dialkylcyclohexylamines, alkylamines (wherein the alkyl group is methyl, ethyl, propyl, butyl and isomeric forms thereof) and heterocyclic amines. Examples of tertiary amine catalysts include trimethylamine, triethylamine, dimethylethanolamine, N-methylmorpholine, N-ethylmorpholine, N,N-dimethylbenzylamine, N,N-dimethylethanolamine, N,N,N',N'-tetramethyl-1,4-butanediamine, N,N-dimethylpiperazine, 1,4-diazabicyclo-2,2,2-octane, bis(dimethylaminoethyl)ether, bis(2-dimethylaminoethyl)ether, 4,4'-(oxydi-2,1-ethanediyl)bismorpholine, triethylenediamine, pentamethyldiethylenetriamine, dimethylcyclohexylamine, N-acetyl N,N-dimethylamine, N-cocoyl-morpholine, N,N-dimethylaminomethyl N-methylethanolamine, N,N,N'-trimethyl -N'-hydroxyethyl bis(aminoethyl) ether, N,N-bis(3-dimethylaminopropyl) N-isopropanolamine, (N,N-dimethyl)amino-ethoxyethanol, N,N,N',N'-tetramethylhexanediamine, 1,8-diazabicyclo-5,4,0-undecene-7, N,N-dimorpholinodiethyl ether, N-methylimidazole, dimethylaminopropyldipropanolamine, bis(dimethylaminopropyl)amino-2-propanol, tetramethylaminobis(propylamine), (dimethyl(aminoethoxyethyl))((dimethylamino)ethyl) ether, tris(dimethylaminopropyl)amine, dicyclohexylmethylamine, bis(N,N-dimethyl-3-aminopropyl)amine, 1,2-ethylenepiperidine, and methyl-hydroxyethylpiperazine.

[0031] On a weight percent (wt %) basis, the isocyanate reactive component can include one or more tertiary amine catalysts in an amount ranging from 0.5 wt % to 15 wt %, from 1 wt % to 15 wt %, or from 1 wt % to 10 wt %.

[0032] The isocyanate-reactive component may include one or more polyetheramine crosslinkers, particularly polyetheramines having a number average molecular weight greater than 1 kDa or in the range of 1 kDa to 6 kDa. The polyetheramines may include monoamines, diamines, and higher order amines (e.g., triamines, tetraamines, etc.) having an amine functionality of two or more (e.g., in the range of 2 to 4).

[0033] Suitable polyetheramines include resins made by adding lower alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, or mixtures thereof, to a suitable initiator and then aminating the resulting hydroxyl-terminated polyol. When two or more oxides are used, they may be present as a random mixture or as blocks of one or another polyether. In the amination step, the terminal hydroxyl groups in the polyol may be primary or secondary hydroxyl groups. Reductive amination processes are known and are described in U.S. Patent 3,654,370. The polyetheramines may include commercially available amines, such as primary aliphatic JEFFAMINE available from Huntsman Corporation. TM Series of polyetheramines; including T-403, T-3000, T-5000, D-400, D-4000, etc.; or available from BASF, including Baxxodur TM EC 3003 and Baxxodur TM EC311.

[0034] On a weight percent (wt %) basis, the isocyanate-reactive component can include one or more high molecular weight crosslinking agents in an amount ranging from 0.5 wt % to 15 wt %, 1 wt % to 15 wt %, or 1 wt % to 10 wt %.

[0035] The isocyanate-reactive component may include one or more cell openers that function to stabilize foam formation and reduce phase separation. The cell opener includes a polyethylene / polyoxypropylene (EO / PO) copolymer having an EO content of at least 60 wt% or at least 75 wt% and a hydroxyl functionality of at least 4 or at least 6. The EO / PO copolymer may have a number average molecular weight of at least 1.5 kDa, such as in the range of 1.5 kDa to 5 kDa.

[0036] The cell opener may also include a contact product prepared from at least one organic polyacid (e.g., a diacid, a triacid, etc.) and at least one of a tetraalkylguanidine and a tertiary amine catalyst containing an isocyanate reactive group (as described in U.S. Patent Nos. 9,765,009 and 10,023,681). In some cases, the cell opener includes a silicone-free stabilizer, including one from EVONIK TM ORTEGOL TM 500, 501, etc.

[0037] Based on weight percent (wt %), the isocyanate reactive component may include one or more cell openers in an amount ranging from 5 wt % to 40 wt %, from 10 wt % to 40 wt %, or from 10 wt % to 35 wt %.

[0038] The polyurethane foam-forming composition may contain one or more blowing agents, including water and aqueous fluids; chemical blowing agents such as hydrocarbons, acids, volatile organic compounds, and the like; and physical blowing agents, including gases such as nitrogen, air, carbon dioxide, and the like. During mixing, the blowing agent may be added to the foam-forming composition in an amount ranging from 1 wt% to 15 wt%, or from 5 wt% to 15 wt%, by weight percentage (wt%). The blowing agent may be added to the isocyanate component and / or the isocyanate-reactive component in an amount sufficient to provide a mixture having the above-mentioned corresponding weight percentages.

[0039] The isocyanate component and / or isocyanate-reactive component may have one or more functional additives, such as those useful in the particular manufacturing process being used or to impart desired properties to the resulting foam. These include, for example, catalysts, chain extenders, odor modifiers, fillers, colorants, flame retardants, pigments, antistatic agents, reinforcing fibers, antioxidants, preservatives, acid scavengers, and the like.

[0040] The water-resistant polyurethane foam disclosed herein can be prepared by mixing an isocyanate and an isocyanate-reactive component in the presence of a catalyst and a blowing agent, dispensing the resulting mixture (e.g., into a cavity of a vehicle component or insulation panel), and allowing the reaction mixture to form foam. In cavity-filling applications, the foam is dispensed into the cavity and allowed to expand to occupy the available space. The cavity is preferably open, meaning that the portion of the substrate into which the reaction mixture is dispensed is open to the atmosphere while the foam reacts, expands, and cures.

[0041] As used herein, "cavity" refers to a hollow space or other suitable shape within a part. A cavity can be one that, due to its shape or orientation, cannot retain a fluid. Examples of vehicle components containing cavities include pillars, rockers, door sills, sails, hoods, air chambers, seams, frame rails, vehicle subassemblies, hydroformed parts, cross-car beams, and engine cradles. Once the foam formulation is applied and expanded, these components can be assembled to the vehicle or vehicle frame.

[0042] Examples of insulating panels include interior and / or exterior walls of buildings, or portions of such walls; walls of appliances such as freezers, refrigerators, coolers, ovens, thermoses or other insulated carafes, and the like.

[0043] The ratio of the isocyanate and the isocyanate-reactive component is selected to provide an isocyanate index (ratio of NCO to isocyanate-reactive groups) of 0.7 to 1.5, or 0.85 to 1.35, or 0.85 to 1.25. The isocyanate and the isocyanate-reactive component can be formulated in a volume ratio of 5:1 to 1:5, 4:1 to 1:4, 2:1 to 1:2, or 1.5:1 to 1:1.5.

[0044] The components can be mixed together and dispensed at ambient or slightly elevated temperatures (e.g., 30°C to 80°C). It is generally not necessary to apply heat to the vehicle component or insulation panel to drive the expansion and curing reaction, but it is within the scope of the present invention. Upon expansion and curing, the foam formulation produces a foam having a volumetric capacity of 1.25 lbs / ft³ to 5 lbs / ft³ (20 kg / m³). 3 Up to 80kg / m 3 ) density, which at least partially fills the cavity. The foam formulation should expand to fill the entire cross-sectional area of ​​the cavity, for at least a portion of its length. In some applications, such as vehicle cavity sealing and building wall insulation, the resulting foam acts as a barrier to water and other fluids penetrating the cavity, and also suppresses noise and vibration through the filled structure.

[0045] The mixture of the isocyanate component and the isocyanate-reactive component can be cured at a temperature (e.g., RT) of 0° C. to 60° C., 10° C. to 50° C., 15° C. to 45° C., or 18° C. to 35° C. Curing can be indicated by an increase in viscosity after mixing the isocyanate component and the isocyanate-reactive component, ultimately forming a cured foam with a measurable hardness. The cured foam composition can have a hardness range of 40 Shore 00 to 90 Shore 00, 50 Shore 00 to 85 Shore 00, or 60 Shore 00 to 80 Shore 00 as determined by ASTM D-2240-15.

[0046] The water-resistant polyurethane foam disclosed herein may have a water absorption of less than 15% after exposure to 100% relative humidity for 10 days. In some cases, the cured foam may have a relative humidity of 20 g / cm2 according to ASTM D1622-20. 3 Up to 80g / cm 3 density.

[0047] The following examples are provided to illustrate the present invention and are not intended to limit the scope of the present invention.Unless otherwise indicated, all parts and percentages are by weight.

[0048] Example

[0049] The following examples are provided to further illustrate embodiments of the present invention in detail, but should not be construed as limiting the scope of the claims.Unless otherwise indicated, all parts and percentages are by weight.

[0050] In the following examples, the polyurethane formulations were reacted to form foams, which were then characterized by three criteria: a water absorption target of 8% or less; the foam was stable with no shrinkage 15 minutes after dispensing; and the isocyanate-reactive components were stable after 24 hours at 60°C, as indicated by a lack of phase separation. Table 1 lists the materials used in the following examples:

[0051]

[0052] The sample formulation was prepared by combining the ingredients of the isocyanate component and the isocyanate-reactive component in a blender for 15 minutes. The isocyanate-reactive component was prepared by combining all ingredients in no particular order, except for the addition of water in the final step. The isocyanate component was similarly blended together in a blender under a nitrogen atmosphere for 15 minutes. Both components were then added to an AP-10 cannon dispenser.

[0053] Both materials were loaded into an AP-10 Cannon (Italy) dispenser at 46°C and 750 psi in a 2:1 ratio of isocyanate component:isocyanate reactive component.

[0054] Water absorption is determined by filling a 100 mm x 300 mm box constructed from an electronically coated metal panel with 100 to 150 g of the foam formulation. The foam is allowed to cure at room temperature for 24 hours and the weight is recorded. The cured foam assembly is then exposed to 100% RH at 38°C for 10 days, followed by a conditioning period of 50% RH at 23°C for 24 hours. The weight of the "wet foam" is then recorded. Water absorption is calculated from the change in weight according to the following formula: (wet foam weight - dry foam weight) / (dry foam weight) x 100.

[0055] The phase stability of the isocyanate-reactive components was tested by adding all ingredients and stirring for one hour. The samples were then placed at 50°C for 72 hours after which they were visually inspected for phase separation.

[0056] Polyurethane foam stability is defined as the production of foam that exhibits no shrinkage 15 minutes after mixing.

[0057]

[0058]

[0059] As shown, comparative samples CE1-5 used low molecular weight crosslinkers (polyamines or polyols), and the foams were stable and showed no phase separation, but the water absorption was significantly above the target specification of less than 15 wt%. For CE6 and CE7, formulations containing high molecular weight crosslinkers showed minimal phase separation and minimal water absorption in the isocyanate-reactive component, but the samples failed to produce stable foams. For CE8, the combination of a low molecular weight crosslinker and the cell opener Ortegol 501 produced a stable PU foam with poor water resistance, despite no phase separation in the isocyanate-reactive component. For CE9, the combination of a high molecular weight crosslinker and a high EO content cell opener (Voranol 4053) produced a stable PU foam with excellent water resistance, but the isocyanate component was unstable and phase separation occurred.

[0060] In contrast, the inventive examples demonstrate that the combination of a high molecular weight crosslinker and a cell opener produces PU foams with low water absorption and foam stability. IE1, formulated with a cell opener, provides a very stable foam with no phase separation and excellent water absorption. For IE2, the combination of a high molecular weight crosslinker with the cell opener Ortegol 501 produces a very stable foam with no phase separation in the isocyanate-reactive component and excellent water absorption. Without being limited by theory, it is believed that the use of a high molecular weight polyetheramine crosslinker at concentrations above 3 wt% interacts with the cell opener to strengthen the foam, thereby preventing water from penetrating the pore structure.

Claims

1. A water-resistant polyurethane foam composition comprising the reaction product of: The isocyanate component, measured by weight percentage (wt%), comprises: 65 wt% to 85 wt% polymeric MDI blend, 10 wt% to 35 wt% of a plasticizer, and 0.2 wt% to 2 wt% of a cell opener; and An isocyanate-reactive component, measured in wt%, comprising: 20wt% to 50wt% of copolymer polyol, 15 wt% to 60 wt% of a polyether polyol having a functionality of 3 to 8, 1wt% to 10wt% of a tertiary amine catalyst, 1 wt% to 10 wt% of a polyetheramine crosslinker having a number average molecular weight of 1 kDa or greater, 1 wt% to 8 wt% of a foam stabilizer, and 5wt% to 15wt% of a blowing agent.

2. The composition of claim 1, wherein the foam has a water absorption of less than 15% after exposure to 100% relative humidity for 10 days.

3. The composition of claim 1, wherein the cell opener is a high EO content polyol.

4. The composition of claim 1, wherein the cell opener is a contact product prepared from at least one organic polyacid and at least one of a tetraalkylguanidine and a tertiary amine catalyst containing an isocyanate-reactive group.

5. The composition of claim 1, wherein the isocyanate component and the isocyanate-reactive component are combined in a volume ratio of 2:

1.

6. The composition of claim 1 wherein the isocyanate reactive component comprises a copolymer polyol containing at least 40% solids.

7. The composition of claim 1 wherein the polymeric MDI blend has an NCO content of 18% to 25%.

8. The composition of claim 1, wherein the foam has a g / cm 2 foaming capacity according to ASTM D1622-20. 3 Up to 80g / cm 3 density.

9. An automotive part comprising the foam composition of claim 1.

10. A method comprising: inserting the solid thermally expandable polyolefin composition according to claim 1 into the cavity, and The thermal expansion step is performed by heating the thermally expandable polyolefin composition in the cavity to a temperature sufficient to expand the polyolefin composition to form a foam that fills at least a portion of the cavity.

11. The method of claim 7, wherein the cavity is contained in a part, assembly, or subassembly of an automotive vehicle.

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