EP4634259A1

EP4634259A1 - High stiffness polyurethane foam compositions

Info

Publication number: EP4634259A1
Application number: EP23821837.4A
Authority: EP
Inventors: Abhishek SHETE; Paolo Diena; Adebola OGUNNIYI; Maribel CANNON; Harshad M. Shah; Micol Federica TRESOLDI; Kaoru Aou; Yuri ALENCAR MARQUES
Original assignee: Dow Global Technologies LLC
Current assignee: Dow Global Technologies LLC
Priority date: 2022-12-16
Filing date: 2023-11-14
Publication date: 2025-10-22
Also published as: AR131312A1; WO2024129282A1; TW202428678A; CN120303316A; JP2026501097A; KR20250114131A; TWI909272B

Abstract

Foam-forming compositions may include (a) at least one isocyanate component; and (b) at least one isocyanate-reactive composition including: (i) at least one low molecular weight polyether polyol having an average functionality ranging from 2 to 8 and a hydroxyl equivalent weight in the range of 30 Da to 450 Da; (ii) at least one EO-capped high molecular weight polyether polyol having an average functionality ranging from 2 to 8 and a hydroxyl equivalent weight in the range of 1500 Da to 10,000 Da; and (iii) optionally, at least one high molecular weight polyether polyol having an average functionality ranging from 1 to 8 and a hydroxyl equivalent weight in the range of 800 Da to 10,000 Da, wherein (ii) is present at a percent by weight (wt%) of the sum of the polyols in the isocyanate-reactive composition ranging from 25 wt% to 75 wt%; (c) a catalyst package comprising at least one latent gelling catalyst; and (d) at least one blowing agent; wherein an isocyanate index of the foam-forming composition is from 60 to 300 and the foam has a molded foam density of from 250 kg/m³ to 750 kg/m³ according to ASTM D1622-20.

Description

HIGH STIFFNESS POLYURETHANE FOAM COMPOSITIONS Field Embodiments relate to foam-forming compositions and processes for producing polyurethane foam articles, and high density foam articles having high modulus, elongation and tensile strength. Introduction Polyurethane foams are known in the art and utilized in various end use applications, including cushions, support articles, encapsulants/pottants, and insulation. Polyurethane foams can be formed from various chemical compositions, and may utilize physical and/or chemical blowing agents. For example, polyurethane foams are generally formed from reacting an isocyanate and a polyol in the presence of a blowing agent. Performance properties of foams, including hardness, density, flexibility, and the like, are a function of the components utilized in their preparation. Polyurethane foams of high-density with high modulus, elongation, and tensile strength are useful in a number of applications such as electric vehicle battery packs, while maintaining the adhesion and thermal insulation applied in low thickness regions (1-6 mm). Currently, stiff and high density foams (≥ 250 kg/m³) cured at low temperatures (25-45 °C) are found to be very brittle and tend to break at low elongation values. Additionally, in a majority of rigid foam formulations, exothermic conditions are needed to cure and develop properties, but are often difficult to achieve in EV applications due to the presence of metal substrates and heat sinks that draw heat away from the foam-forming composition and/or potential damage to lithium ion batteries at higher temperatures. Summary In an aspect, foam-forming compositions may include (a) at least one isocyanate component; and (b) at least one isocyanate-reactive composition including: (i) at least one low molecular weight polyether polyol having an average functionality ranging from 2 to 8 and a hydroxyl equivalent weight in the range of 30 Da to 450 Da; (ii) at least one EO-capped high molecular weight polyether polyol having an average functionality ranging from 2 to 8 and a hydroxyl equivalent weight in the range of 1500 Da to 10,000 Da; and (iii) optionally, at least one high molecular weight polyether polyol having an average functionality ranging from 1 to 8 and a hydroxyl equivalent weight in the range of 800 Da to 10,000 Da, wherein (ii) is present at a percent by weight (wt%) of the sum of the polyols in the isocyanate-reactive composition ranging from 25 wt% to 75 wt%; (c) a catalyst package comprising at least one latent gelling catalyst; and (d) at least one blowing agent; wherein an isocyanate index of the foam-forming composition is from 60 to 300 and the foam has a molded foam density of from 250 kg/m³ to 750 kg/m³ according to ASTM D1622-20. Detailed Description Embodiments relate to polyurethane foams and compositions having high density and stiffness, particularly at low thicknesses such as 1 mm to 8 mm. In another aspect, polyurethane foams are produced by reacting an isocyanate component with an isocyanate-reactive component containing a mixture of high and low molecular weight (MW) polyether polyols, and a catalyst package may have delayed foam formation and remain a workable liquid at temperatures up to 50 ^oC for enhanced in-mold performance. High MW polyether polyols may also include at least one high MW polyether polyol capped with ethylene oxide. Polyurethane foams produced by compositions disclosed herein may from closed-cell foams and may be thermally insulating. As used herein, “high density” foamed polyurethane compositions may have a density in the range of 200 kg/m³ to 700 kg/m³, or 250 kg/m³ to 700 kg/m³. Unless otherwise specified, all molecular weights in this specification are listed as number average molecular weight. Polyurethane (PU) foams and methods of manufacturing foams include the combination of reactive chemical components, such as an isocyanate component with an isocyanate-reactive component, to generate a foam-forming composition. The isocyanate component contains a di- or poly- isocyanate that contains reactive isocyanate (N=C=O) functional groups. The isocyanate- reactive component contains two or more functional groups such as hydroxyls or amines that react with isocyanate functional groups. Foam-forming compositions may also include other additives such as suitable catalysts, surfactants, flame retardants, viscosity modifiers, fillers, and blowing agents, which may be added to one or both of the isocyanate and isocyanate-reactive components. The isocyanate and isocyanate-reactive components may be combined at various stoichiometric ratios that are described by the isocyanate index. The isocyanate index equals the ratio of isocyanate groups to isocyanate-reactive groups (such as OH groups) multiplied by 100. Foam-forming PU compositions disclosed herein may have an isocyanate index ranging from 60 to 300, which is used to generate foam articles having relatively high densities, while reducing excessive brittleness. Increased relative amounts of isocyanate are often used to increase stiffness, however, foamed PU compositions disclosed herein may exhibit comparative increases in stiffness and flexural modulus at lower relative isocyanate indices. Foamed polyurethane compositions may also exhibit good performance at relatively low thicknesses in a range of 1 mm to 10 mm, or 1 mm to 5 mm. Foamed PU compositions may have a torsional (i.e, shear) modulus as determined by ASTM D5279-21 greater than 150 MPa, or greater than 175 MPa. In some cases, foamed PU compositions may have a torsional (i.e., shear) modulus in the range of 150 MPa to 800 MPa. Foamed articles may also exhibit reduced elongation at break values (e.g., equal to or greater than 6% elongation) when tested according to ASTM D1708-18 standard on a microtensile testing machine. Foam-forming PU compositions disclosed herein may have delayed foam rise (creaming) compared to standard foaming compositions after dispensing (or spraying), which can increase flow and coverage in mold applications, particularly for molds having large surface area and/or complex geometries. In some cases, foam-forming PU compositions may include isocyanate and isocyanate-reactive components that remain liquid at ambient temperatures for 30 seconds or more after mixing, or for 60 seconds or more after mixing. Ambient temperatures may range 15 °C to 35 °C, where room temperature is often around 23 °C. In some cases, the isocyanate and isocyanate-reactive components remain liquid for 30 seconds or more up to mold temperatures such as up to 50 ^oC. Foam-forming PU compositions disclosed herein include a two-part composition including an isocyanate component and an isocyanate-reactive component, and various additives such as a blowing agent and catalyst(s) combinations. Isocyanate-reactive components may include a combination of polyether polyols, particularly, (1) low molecular weight (MW) polyether polyols having an average hydroxyl equivalent of 450 Da or less, and (2) a high MW polyether polyol having an average hydroxyl equivalent weight of 800 Da to 10,000 Da. In some cases, the high MW polyether polyols may be ethylene oxide (EO) capped at a percent by weight (wt%) of 3 wt% to 80 wt% of the polyol. Polyether polyols disclosed herein may include products obtained by the polymerization of a cyclic oxide, for example, ethylene oxide (“EO”), propylene oxide (“PO”), butylene oxide (“BO”), tetrahydrofuran, or epichlorohydrin, in the presence of polyol initiators having a functionality ranging from 2 to 8, or 2 to 5. As understood in the art, the initiator compound, or combination thereof, is generally selected based on desired functionality of the resulting polyether polyol. Polyether polyols may be formed with one or more polyol initiators such as neopentylglycol; 1,2-propylene glycol; trimethylolpropane; pentaerythritol; sorbitol; sucrose; glycerine; alkanediols, such as 1,6-hexanediol, 1,4- butanediol, 1,3-butane diol, 2,3-butanediol, 1,3-propanediol, 1,2-propanediol, 1,5-pentanediol, 2-methylpropane-1,3-diol, 1,4-cyclohexane diol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,5-hexanediol; ethylene glycol; diethylene glycol; triethylene glycol; 9(1)-hydroxymethyloctadecanol, 1,4- bishydroxymethylcyclohexane; hydrogenated bisphenol; 9,9(10,10)- bishydroxymethyloctadecanol; 1,2,6-hexanetriol; and combinations thereof. Isocyanate-reactive components may include one or more low MW polyether polyols having an average hydroxyl equivalent weight determined according to ASTM D4274 D in the range of 30 Da to 400 Da. In some cases, low MW polyether polyols may have a number average molecular weight of 450 Da or less, or 200 Da or less. In some cases, low MW polyether polyols include propoxylated derivatives of polyol initiators such as glycerine, sorbitol, butanediol, and the like. Isocyanate-reactive components may include a low MW polyether polyol at a percent by weight (wt%) ranging from 25 wt% to 75 wt%, or 30 wt% to 70 wt%. In some cases, the isocyanate-reactive component may include low MW polyol, such as the polyol initiators disclosed above, in place of or in addition to the low MW polyether polyols. In some cases, the isocyanate component may include a low MW polyol at a percent by weight of the isocyanate-reactive component ranging from 1 wt% to 10 wt%, or 1 wt% to 5 wt%. Isocyanate-reactive components may include one or more high MW polyether polyols having an average functionality in a range of 1 to 8, and an average hydroxyl equivalent weight (OHW) of 800 Da to 10,000 Da, 800 Da to 8,500 Da, or 1,000 Da to 8,000Da. High MW polyether polyols may be prepared using the chemistries and polyol initiators as discussed above with respect to polyether polyols. High MW polyether polyols may have a functionality of 1 to 8, with a primary hydroxyl content of >60%, >40% or >20%. Further, high MW polyether polyols may be capped with oligomers or polymers of ethylene oxide (EO-capped) that modify elongation properties and toughness when compared to rigid foams of similar density. EO-capped high MW polyether polyols may have an ethylene oxide (EO) content at a percent by weight (wt%) of 3 wt% to 80 wt%. In some cases, high MW polyether polyols may include EO-capped high MW polyether polyols having an EO content ranging from 3 wt% to 80 wt%), an average functionality ranging from 1 to 8, and average molecular weight ranging from 800 Da to 10,000 Da with >40% primary hydroxyl. In some cases, the EO content may range from 3 wt% to 50 wt%. In some cases, EO content may range 3 wt% to 28 wt% with functionality of 1 to 8 and molecular weight ranging from 800 Da to 10,000 Da with >60% primary hydroxyl. Isocyanate-reactive components may include a high MW polyether polyol at a percent by weight (wt%) of the sum of all polyols in an isocyanate-reactive component ranging from 25 wt% to 75 wt%, 30 wt% to 70 wt%, or 35 wt% to 65 wt%. Foam-forming composition may include an isocyanate component containing one or more isocyanates, such as polymeric isocyanates, aromatic isocyanates, carbodiimide-modified isocyanates. Isocyanate species may be monomeric, oligomeric, prepolymers, and the like. The isocyanate component can include, for example, one or more isocyanate and/or polyisocyanates compounds. Isocyanate components may include polyisocyanates having a nominal functionality of > 1.5, or >2.0. In some cases, isocyanate components may include polyisocyanates having an isocyanate (NCO) content by weight of 10% or more, 20% or more, or 30% or more. The isocyanate compound may be an aliphatic polyisocyanate, a cycloaliphatic polyisocyanate, an araliphatic polyisocyanate, an aromatic polyisocyanate, or combinations thereof. Examples of isocyanates include, but are not limited to, polymethylene polyphenylisocyanate; toluene 2,4-/2,6-diisocyanate (TDI); methylenediphenyl diisocyanate (MDI, including its isomers); polymeric and prepolymeric MDI; triisocyanatononane (TIN); naphthyl diisocyanate (NDI); 4,4’-diisocyanatodicyclohexyl-methane; 3-isocyanatomethyl-3,3,5- trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI); tetramethylene diisocyanate; hexamethylene diisocyanate (HDI); 2-methyl-pentamethylene diisocyanate; 2,2,4- trimethylhexamethylene diisocyanate (THDI); dodecamethylene diisocyanate; 1,4- diisocyanatocyclohexane; 4,4’-diisocyanato-3,3’-dimethyl-dicyclohexylmethane; 4,4’- diisocyanato-2,2-dicyclohexylpropane; 3-isocyanatomethyl-1-methyl-1-isocyanatocyclohexane (MCI); 1,3 -diisooctylcyanato-4 -methylcyclohexane; 1,3 -diisocyanato-2-methylcyclohexane; and combinations thereof, among others. In addition to the isocyanates mentioned above, partially modified polyisocyanates including uretdione, isocyanurate, carbodiimide, uretonimine, allophanate or biuret structure, and combinations thereof, among others, may be utilized. Isocyanates may have an average isocyanate equivalent weight of from 80 g/eq to 400 g/eq, such as from 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. The isocyanate component may also include isocyanate prepolymers resulting from reaction of an isocyanate-reactive compound with a molar excess of a polyisocyanate compound or polymeric isocyanate compound under conditions that do not lead to gelation or solidification, the isocyanate prepolymers can have a higher average isocyanate equivalent weight of > 400 g/eq. 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. Isocyanate prepolymers may be described by an isocyanate index, defined as the ratio of isocyanate groups to isocyanate-reactive groups (such as OH groups) multiplied by 100. Isocyanate prepolymers disclosed herein may have an isocyanate index range of from 60 to 300, 75 to 300, or 100 to 200. Examples of commercial isocyanates include, but are not limited to, polyisocyanates under the trade names VORANATE™, PAPI , and ISONATE , such as VORANATE^TM M 220, and PAPI^TM 27, all of which are available from Dow Chemical Company. The isocyanate component may include an isocyanate compound having a number average molecular weight of 150 g/mol to 750 g/mol. In some cases, the isocyanate compound can have a number average molecular weight from a low value of 150 g/mol, 200 g/mol, 250 g/mol or 300 g/mol to an upper value of 350 g/mol, 400 g/mol, 450 g/mol, 500 g/mol or 750 g/mol. The number average molecular weight values reported herein are determined by end group analysis, gel permeation chromatography, and other methods as is known in the art. The isocyanate compound can be monomeric and/or polymeric, as are known in the art. Foam-forming compositions may include an isocyanate component at a percent by weight (wt%) ranging from 30 wt% to 80 wt%, 35 wt% to 75 wt%, 40 wt% to 70 wt%, or 45 wt% to 65 wt%. Foam-forming PU compositions may include one or more blowing agents, including water and aqueous fluids; chemical blowing agents, such as hydrocarbons, acids, volatile organics, and the like; and physical blowing agents including gases such as nitrogen, air, carbon dioxide, and the like. Blowing agents may be added to the foam-forming composition during mixing at a percent by weight (wt%) ranging from 0.05 wt% to 10 wt%, or 0.1 wt% to 5 wt%. In some cases, one or more blowing agents may be present at a percent by weight (wt%) of the sum of the polyols in the isocyanate-reactive composition that is less than or equal to 0.45 wt%, or less than or equal to 0.4 wt%. Blowing agents may be added to the isocyanate component and/or the isocyanate- reactive component in amount sufficient to provide the mixture with the corresponding weight percentages above. Foam-forming PU compositions may include a catalyst package containing one or more catalysts that may include one or more of a blowing catalyst, a gelling catalyst, and a trimerization catalyst. The catalyst package may be present in the isocyanate-reactive composition. As used herein, blowing catalysts and gelling catalysts, may be differentiated by a tendency to favor either the urea (blow) reaction, in the case of the blowing catalyst, or the urethane (gel) reaction, in the case of the gelling catalyst. A trimerization catalyst may be utilized to promote the isocyanurate forming reaction in the compositions. The catalyst package can also be added as a separate stream into the reaction mixture of isocyanate and isocyanate-reactive composition. The catalyst package may be present in the foam-forming composition at a percent by weight (wt%) ranging from 0.1 wt% to 5 wt%, or 1 wt% to 5 wt%. Blowing catalysts may include bis-(2-dimethylaminoethyl)ether, pentamethyldiethylenetriamine, triethylamine, tributyl amine, N,N-dimethylaminopropylamine, dimethylethanolamine, N,N,N′,N′-tetra-methylethylenediamine, and combinations thereof, among others. An example of a commercial blowing catalyst is POLYCAT^® 5, from Evonik, among other commercially available blowing catalysts. Gelling catalysts include organometallic compounds, cyclic tertiary amines and/or long chain amines, e.g., that contain several nitrogen atoms and combinations thereof. Organometallic compounds include organotin compounds, such as tin(II) salts of organic carboxylic acids, e.g., tin(II) diacetate, tin(II) dioctanoate, tin(II) diethylhexanoate, and tin(II) dilaurate, and dialkyltin(IV) salts of organic carboxylic acids, e.g., dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate. Bismuth salts of organic carboxylic acids may also be utilized as the gelling catalyst, such as, for example, bismuth octanoate. Cyclic tertiary amines and/or long chain amines include dimethylbenzylamine, triethylenediamine, and combinations thereof. Examples of a commercially available gelling catalysts are POLYCAT^® 8, DABCO ^® 33-LV, and DABCO^® T-12 from Evonik, among other commercially available gelling catalysts. Trimerization catalysts may include any such catalysts known in the art. Examples of trimerization catalysts include N,N',N''-tris(3-dimethylaminopropyl) hexahydro-S-triazine; N,N- dimethylcyclo-hexylamine; 1,3,5-tris(N,N-dimethylaminopropyl)-s-hexahydrotriazine; [2,4,6-tris (dimethylaminomethyl) phenol]; potassium acetate, potassium octoate; tetraalkylammonium hydroxides such as tetramethylammonium hydroxide; alkali metal hydroxides such as sodium hydroxide; alkali metal alkoxides such as sodium methoxide and potassium isopropoxide; and alkali metal salts of long-chain fatty acids having 10 carbon atoms to 20 carbon atoms, and combinations thereof, among others. Some commercially available trimerization catalysts include, for example, DABCO^® TMR-2, DABCO^® TMR-20, DABCO^® TMR-30, DABCO^® TMR-7, DABCO^® K 2097; DABCO^® K15, POLYCAT^® 41, and POLYCAT^® 46, each from Evonik, among other commercially available trimerization catalysts. Catalyst packages may include a “latent catalyst” or “delayed catalyst,” which is defined as a catalyst compound that is of low catalytic activity or is relatively inactive at ambient temperatures, and which becomes more catalytically active, such as by disassociation, decoordination, ring opening, ionization, or tautomerization upon heating to effect catalysis of least one of the chemical reactions involved in making a PU foam. Ambient temperatures may range 15 °C to 32 °C, where room temperature is often around 23 °C. Latent/delayed action catalysts can be gelling, blowing, and/or trimerization types of catalysts in terms of their function in the foaming process. The latent catalyst is often a subset of tertiary amine gelling catalysts that include acid salts, phenolic salts, or complexes of a tertiary amine catalyst where the acid or phenolic is often a carboxylic acid or phenol species, but not limited to, such as formic acid, acetic acid, propionic acid, 2-ethylhexanoic acid, phenoxyacetic acid, gluconic acid, tataric acid, citric acid, phenol, nonylphenol, diisopropyl phenol, and the like; and mixtures thereof. Some useable commercially available latent catalysts include, for example, DABCO^® TMR-30, POLYCAT^® SA2 LE, POLYCAT^® SA-1/10, DABCO^® 8154, NIAX™ A- 107, NIAX™C-31, NIAX™C-225, JEFFCAT™ ZF-54, JEFFCAT™ LED-204; and mixtures thereof. Catalyst packages may include a mixture of one or more of the above catalysts and/or latent catalysts at a percent by weight (wt%) of the foam-forming composition ranging from 0.1 wt% to 5 wt%. In some cases, a catalyst package may be added to the isocyanate component and/or the isocyanate-reactive component in amount sufficient to provide the mixture with the corresponding weight percentages above. Foam-forming compositions may include one or more fillers including fiberglass, fiber, silica, CaCO3, kaolin, talc, alumina, alumina trihydrate (ATH), and the like. One or more fillers may be added at a percent by weight (wt%) of the foam-forming composition ranging from 0 wt% to 15 wt%, or 1wt% to 10 wt%. In some cases, fillers may be added to the isocyanate component and/or the isocyanate-reactive component in amount sufficient to provide the mixture with the corresponding weight percentages above. Foam-forming compositions may include a surfactant present in the isocyanate and/or isocyanate-reactive component in an in amount sufficient to provide the surfactant at a percent by weight of the foam-forming mixture of 0.1 wt % to 5 wt %. Surfactant may include silicone-based surfactants, polyether-modified silicone surfactants, and organic-based surfactants. Some representative surfactants include polysiloxane polyoxylalkylene block copolymers, such as those disclosed in U.S. Pat. Nos. 2,834,748; 2,917,480; and 2,846,458; organic surfactants containing polyoxyethylene-polyoxybutylene block copolymers, as are described in U.S. Pat. No.5,600,019, and the like. Other surfactants include polyethylene glycol ethers of long-chain alcohols, tertiary amine or alkanolamine salts of long-chain allyl acid sulfate esters, alkylsulfonic esters, alkyl arylsulfonic acids, and combinations thereof. Some commercially available surfactants useful in the isocyanate-reactive composition include VORASURF™ DC 193, VORASURF™ 504, TEGOSTAB^® B8418, and mixtures thereof. Compositions may also include one or more functional additives such as chain extenders, expandable graphite, additional physical or chemical blowing agents, flame retardants, thixotropic agents such as poloxamer, viscosity modifiers, cell openers, emulsifiers, adhesion modifiers, antioxidants, surfactants, colorants, UV stabilizers, antistatic agents, bacteriostats, and mixtures thereof. Foam-forming compositions, foamed polyurethane articles, and methods of this disclosure are useful for a variety of end applications, such as space filling applications, automotive applications (e.g. for control modules), and the like. The foamed polyurethane articles can be used to at least partially cover or encapsulate articles, such as batteries and other electronic components. The foamed polyurethane articles can also be used for thermal insulation. Moreover, the foamed polyurethane articles can be used as a fire block. In general, the foamed polyurethane articles of this disclosure provide a combination of desirable physical properties relative to conventional foams, including one or more of the following: reduced weight, lowered density, increased thermal resistance, increased stability, etc. The foamed polyurethane articles can be formed in environments where the formation of hydrogen gas is a concern. In addition, the foamed polyurethane articles can be foamed at room temperature or thereabout, which is useful for temperature sensitive applications Foam production may include the steps of: (1) equilibrating the isocyanate component and isocyanate-reactive composition to the mixing; (2) preheating mold surfaces to the molding temperature (generally, for example, between 25 °C to 60 °C) with optional woven and non- woven glass or carbon fibers (e.g., fiber mats, meshes or preforms) placed in the mold; (4) determining the loading quantity of foam forming reaction mixture to achieve the desired overpacking ratio (generally, for example from 150 % to 400 %); (5) mixing the isocyanate component and the isocyanate-reactive composition thoroughly and quickly within 10 s; (6) starting a timer at the beginning of the mixing step (5); (7) transferring the foam forming reaction mixture to the mold immediately or directly injecting the foam forming reaction mixture into the mold; (8) closing the mold (if not a closed mold) and allowing the resulting foam-forming reaction mixture to react to form a PU foam article in the mold (i.e., a molded foam article); (9) opening the mold after reaching the preset demolding time; (10) demolding the foam article; and (11) after completely demolding the foam article, inspecting the foam article by visually observing the foam article for defects such as swelling, shrinkage, bulging, and cracking, if any. Processes for preparing a PU foam article can be achieved through any known process techniques in the art. In general, the PU foam article of the present disclosure may be produced by continuous or discontinuous processes, including the process referred to generally as the reaction injection molding (RIM) process or casting molding process with the foaming reaction and subsequent curing being carried out in molds. The mixing of the components of the foam forming composition can be carried out at a temperature of from 5 °C to 80 °C, 10 °C to 60 °C, or 15 °C to 50 °C. The molding of PU foam articles can be performed at a mold temperature range from 20 °C to 80 °C, 30 °C to 70 °C, or 40 °C to 60 °C. Examples The following examples are provided to illustrate the embodiments of the invention, but are not intended to limit the scope thereof. All parts and percentages are by weight unless otherwise indicated. Table 1: List of components used in the Examples e a ^t Surfactant - VORASURF™ ^{A polyether-modified silicone surfactant} 2 DC 5103 Fluid _Dow TM BL A i f i 2 i h l i h l i^k ^ik ^ik ik y g g g Isocyanate-reactive component reagents were weighed on an analytical balance and combined using an DAC 600.1 FVZ-K speedmixer. Batches are used within two hours of mixing. Water content was measured according to ASTM E203-16 and the appropriate amount of water was added to the blend to achieve the desired target. The isocyanate component was then added to the isocyanate-reactive component in the selected ratio (isocyanate index) and the mass of the mixture is recorded. Samples of the foam-forming composition were then analyzed as a liquid mixture or decanted into a mold. Samples were also prepared by mixing using a high-pressure spray system. Isocyanate and isocyanate-reactive components were combined by high-pressure spraying in a GRACO sprayer at 1000-3000 psi. Following mixing of the foam-forming composition were sprayed (for Inventive examples) and/or poured (inventive and comparative examples) into a vessel (e.g., open cup or mold) and the rection kinetics were analyzed. Samples were allowed to react and cream time, rise time, and green strength were recorded. Timing was initiated as the two components are mixed. Cream time is defined as the time between start of mixing and rise in the liquid level (initiating of foam rise). Rise time is defined as the time between start of mixing and foam rise plateauing to a certain height (includes cream time). Gel time is defined as the time between start of mixing & a point at which the material forms a continuous string when probed. Tack-free time is defined as the time between start of mixing and no string coming off the surface upon taping with a tongue depressor stick (includes cream and rise time). Handling time is defined as the time between start of mixing and foam developing enough rigidity to not get compressed upon being pushed with finger (with considerable force). Mold testing included parallel and perpendicular molds. For parallel rise testing in Mold A (19 cm X 12.5 cm X 0.2 cm, where 19 cm is the rise direction), the mold was preheated at 40 °C in the oven and mixed resin samples were transferred to the mold while timing for ~32-34 seconds. The mold is then placed in an oven at 40 °C for 20 minutes. The mixed resin sample containing is then measured and the amount of material remaining in the cup after the pour is calculated. Samples are then demolded and the dimensions, weight of the foam are recorded, and the density is calculated. If the sample foam breaks or shatters or snaps during the demold, it is regarded as too brittle for further testing. The “Testable” foams do not break during the demold or during the cutting for sample shapes for property tests. The remaining testable foam samples were left overnight to cure before cutting the samples out for property testing. For perpendicular rise testing in Mold B (20 cm X 15 cm X 0.5 cm, where 0.5 cm is the rise direction), the mold was preheated at 40 °C in the oven and mixed resin samples were transferred to the mold while timing for ~32-34 seconds. The mold is then placed in an oven at 40 °C for 20 minutes. The mixed resin sample containing is then measured and the amount of material remaining in the cup after the pour is calculated. Samples are then demolded and the dimensions, weight of the foam are recorded, and the density is calculated. After demolding (10-12 minutes), measure the hardness on the surface of the foam sample with Durometer (Shore A scale) and then after 30 minutes, with a Durometer (Shore D scale). If the sample foam breaks or shatters or snaps during the demold, it is regarded as too brittle for further testing. The “Testable” foams do not break during the demold or during the cutting for sample shapes for property tests. The remining testable foam samples were left overnight to cure before cutting the samples out for property testing. A series of properties (I-XI) were tested for the samples as follows: Nature of sample (I) is a qualitative description of the brittleness of the sample in terms of whether demolding was possible post foaming to test it further for mechanical properties. Density (II) is a quantitative measure of the density of the foam sample (i.e., weight/volume), performed pursuant to ASTM D3574 Test A. Elastic modulus, E’ (III), elongation at break (IV), and ultimate tensile strength (V) were all obtained using ASTM D1708-18 standard on a microtensile testing machine in which a PU foam sheet of 0.2 mm thickness was obtained post-mold, aged at room temperature (23 ^oC) for 2 days, and punched into a dog-bone shape. Shear modulus in torsion mode (VI to VIII) and glass transition temperature (IX) were obtained by dynamic mechanical analysis (DMA) with ASTM D5279-21 on an Advanced Rheometric Expansion System (ARES-G2) from TA Instruments equipped with liquid nitrogen environmental control and torsion rectangular fixtures. A rectangular sample from the foams prepared in metal molds (A and B) at 2 mm thickness were punched (45 mm length and 12.8 mm width). The sample length is lined up axial to the torsional axis, and the DMA is performed in torsional mode. The temperature was increased from -70 °C to 200 °C at a ramp rate of 3 °C/min. The frequency of testing was 1 Hz at 0.05% torsional strain, with an axial tensile force of 0.098 N applied to keep sample taut, and at a data collection interval of 30 sec per point. The major output from the characterization identified were the storage modulus in shear modulus (G’), Loss modulus (G’’), and Tan δ. Cream time (X) is the quantification of the time to foam generation measured following the combination of the isocyanate and isocyanate-reactive components by high-pressure mixing and dispense into a cup (cream) or into Mold B (handling time). For cream time, time to foam bubble generation as well as rise time were judged visually and the time recorded. Handling time is defined as the time between start of mixing and foam developing enough rigidity to resist compression by probing by tongue depressor. Hardness was measured after demold, and the handling time was noted as a Shore D > 20. Lap Shear Adhesion Strength Test (XI) was determined according to ASTM D-1002-10 tests to quantify apparent shear strength of single-lap-joint adhesively bonded metal specimens by tension loading. A polypropylene spacer of 1 mm thickness was placed between metal substrates with 0.5 inch overlap. 1 inch wide panels were assembled with removable tapes on bottom. The resin was filled in cavity from top, percolated by gravity, and sealed. The specimen was then placed in oven at 40 °C for 3 hours to cure. The density of foam between the plates was confirmed gravimetrically. The substrate include E-coated cold rolled steel (1 inch X 4 inch X 0.032 inch) from commercial source, i.e., ACT panels. Failure during the lap shear tests is categorized as adhesive failure (foam residue on only one side of substrate due to adhesion failure), cohesive failure (foam residue on both side of substrate due to foam failure), or substrate failure (e-coat strip off on foam or break of substrate). Viscosity measurements for the isocyanate-reactive components were performed on a TA Instruments AR 2000 rheometer with 54 mm cone-plate geometry and 450 micron gap. Data were collected at shear rate sweep of 100 to 0.01 sec^-1 with temperature 25 °C. For the isocyanate components and the individual polyol components, viscosity was measured using ASTM D4889 at 25 °C. Hydroxyl number (OH #) of individual polyether polyols in the formulations was determined according to ASTM D4274 and OH# is used to determine the hydroxyl equivalent weight. Water content was determined according to ASTM E203-16 for the standard test method for water using volumetric Karl Fischer titration. Example 1: Preparation and characterization of PU foams In this example, comparative (C) and inventive (I) samples of water blown foams were prepared as shown in Tables 2 to 7. Table 2: Formulations of comparative samples C1-C3 of foam-forming compositions 2 0 Table 3: Formulations of comparative samples C4-C6 of foam-forming compositions Sample C4 C5 C6 o 0 5 5 4 8 1 2 2 2 8 Table 4: Formulations of comparative samples C7-C8 of foam-forming compositions Sample C7 C8 0 .5 .5 5 39 08 81 4 4 2 .5

Table 5: Formulations of inventive samples I1-I5 of foam-forming compositions Sample I1 I2 I3 I4 I5 5 5 5 8 8 4 4¹

Table 6: Formulations of inventive samples I6-I8 of foam-forming compositions Table 7: Formulations of inventive samples I9-I13 of foam-forming compositions S m l I9 I10 I11 I12 I13 5 5 9 8 1 2 Surfactant - 2 Surfactant 0.32 0.32 0.32 0.32 0.32 Isocyanate-reactive component T_l ^{- 102 102 102 102 102} 5 in Tables 8-13. Property I (nature of foam) indicates whether the formulation foamed or broke/shattered during the process preparing samples for testing of properties III-IX. Table 8: Properties for comparative samples C1-C3 Property P Performance 1² e Table 9: Properties for samples C4-C5 Property Performance t le Table 10: Properties for comparative samples C6-C8 Property Performance le 2 , Table 11: Properties for inventive samples I1-I5 Pr rt Prf rmn e^d

Table 12: Properties for samples I6-I8 P_{T f P} ^Performance e Table 13: Properties for samples I9-I13 t le 0 5 ₄ ₇ Results show that comparative examples are brittle relative to comparative examples. For example, comparative samples C1-C3 shattered or did not foam (Property I), while C5 exhibit lower than the required elongation at break (i.e., Property IV < 6 %). In other cases, comparative samples C4 and C7-8 had lower than the required Ultimate Tensile Strength (Property V < 10 MPa). Finally, for C6, the mechanical properties are satisfactory, except that the density is higher than required (Property II > 700 kg/m³). In comparison, inventive samples I1-I13 including polyether polyols with average hydroxyl equivalent weights of ≥ 800 Da at ≥ 25 wt% concentration in the isocyanate-reactive component exhibit elongation at break values (Property IV) ≥ 6%. The ultimate tensile strength (Property V) is kept above 10 MPa for all inventive samples. The density of the foam for the inventive samples (Property II) is kept between 400-700 kg/m³. The adhesion of foam tested using the lap shear adhesion (Property XI) for I2 to > 8 MPa. Additionally, for inventive samples I1-I13, incorporation of ethylene oxide (EO) capped polyether polyols with OHW of > 1900 Da enhanced the modulus of the foam (Property III) at an isocyanate index of 115 and a foam density in range of 250-700 kg/m³ (Property II). Further, the elongation at break (Property IV) of the inventive foam samples is maintained and/or increased. Thus, not only the stiffness is enhanced but the elongation at break and in turn the ultimate tensile strength (Property V) is also enhanced. While the foregoing is directed to exemplary embodiments, other and further embodiments may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claims 1. A foam-forming composition, comprising: (a) at least one isocyanate component; and (b) at least one isocyanate-reactive composition comprising: (i) at least one low molecular weight polyether polyol having an average functionality ranging from 2 to 8 and a hydroxyl equivalent weight in the range of 30 Da to 450 Da; (ii) at least one EO-capped high molecular weight polyether polyol having an average functionality ranging from 2 to 8 and a hydroxyl equivalent weight in the range of 1500 Da to 10,000 Da; and (iii) optionally, at least one high molecular weight polyether polyol having an average functionality ranging from 1 to 8 and a hydroxyl equivalent weight in the range of 800 Da to 10,000 Da, wherein (ii) is present at a percent by weight (wt%) of the sum of the polyols in the isocyanate-reactive composition ranging from 25 wt% to 75 wt%; (c) a catalyst package comprising at least one latent gelling catalyst; and (d) at least one blowing agent; wherein an isocyanate index of the foam-forming composition is from 60 to 300 and the foam has a molded foam density of from 250 kg/m³ to 750 kg/m³ according to ASTM D1622-20.

2. The composition of claim 1, wherein the at least one low molecular weight polyether polyol is present in an amount from 25 wt% to 75 wt%, based on a total weight of the isocyanate-reactive component.

3. The composition of claim 1, wherein the at least one blowing agent is water.

4. The composition of claim 3, wherein the at least one blowing agent is present at less than or equal to 0.45 wt% of the sum of the polyols in the isocyanate-reactive composition.

5. The composition of claim 1, wherein the at least one EO capped high molecular weight polyether polyol comprises 3 wt% to 80 wt% of ethylene oxide.

6. The composition of claim 1, wherein polyols (b)(ii) and (b)(iii) are present at a total percent by weight of the isocyanate-reactive component ranging from 25 wt% to 75 wt%.

7. The composition of claim 1, wherein the catalyst package comprises a blocked tertiary amine.

8. The composition of claim 1, wherein the foam-forming composition comprises a percent by weight (wt%) the total composition of isocyanate ranging from 30 wt% to 80 wt%.

9. A foamed article prepared from the composition in claim 1.

10. The foamed article of claim 9, wherein the elongation at break according to ASTM D1708-18 is greater than 6%.

11. A process of making polyurethane rigid molded foam including providing the foam- forming composition as claimed in any one of claims 1 to 8, and reacting the foam- forming composition to generate a foam article.