High-rigidity polyurethane foam composition

Abstract

The foam-forming composition comprises (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 in the range of 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 in the range of 2 to 8 and a hydroxyl equivalent weight in the range of 1500 Da to 10,000 Da; and (iii) optionally, at least one EO-capped high molecular weight polyether polyol having an average functionality in the range of 1 to 8 and a hydroxyl equivalent weight in the range of 8. (ii) is present in a weight percent (wt%) range of 25 wt% to 75 wt% based on the total polyols in the isocyanate-reactive composition; (c) a catalyst package comprising at least one latent gelling catalyst; and (d) at least one blowing agent, wherein the foam-forming composition has an Isocyanate Index of 60 to 300, and the foam has a blowing capacity of 250 kg / m according to ASTM D1622-20. 3 ~750kg / m 3 The molded foam density is

Description

[Technical Field]

[0001] Embodiments relate to foam-forming compositions, processes for making polyurethane foam articles, and high density foam articles having high modulus, elongation, and tensile strength.

[0002] Introduction Polyurethane foams are known in the art and are utilized in a variety of end uses, including cushioning, support articles, encapsulants / pottants, and thermal insulation. Polyurethane foams can be formed from a variety of chemical compositions and may utilize physical and / or chemical blowing agents. For example, polyurethane foams are generally formed by reacting isocyanates with polyols in the presence of a blowing agent. The performance properties of foams, including hardness, density, flexibility, etc., are a function of the components utilized in their preparation. High-density polyurethane foams with high modulus, elongation, and tensile strength, while maintaining adhesive and insulating properties in thin-walled applications (1-6 mm), are useful in many applications, such as electric vehicle battery packs.

[0003] Currently, hard and high-density foams (≥ 250 kg / m) that are cured at low temperatures (25-45°C) are available. 3 ) have been found to be very brittle and prone to fracture at low elongation values. Additionally, most rigid foam formulations require exothermic conditions for cure and development, which 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 of the Invention

[0004] In one embodiment, the foam-forming composition comprises (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 in the range of 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 in the range of 2 to 8 and a hydroxyl equivalent weight in the range of 1500 Da to 10,000 Da; and (iii) optionally, at least one EO-capped high molecular weight polyether polyol having an average functionality in the range of 1 to 8. and at least one high molecular weight polyether polyol having a hydroxyl equivalent weight in the range of 800 Da to 10,000 Da, (ii) being present in a weight percent (wt%) in the range of 25 wt% to 75 wt% based on the total polyols in the isocyanate-reactive composition; (c) a catalyst package comprising at least one latent gelling catalyst; and (d) at least one blowing agent, wherein the foam-forming composition has an Isocyanate Index of 60 to 300, and the foam has a blowing capacity of 250 kg / m according to ASTM D1622-20. 3 ~750kg / m 3 The molded foam density is DETAILED DESCRIPTION OF THE INVENTION

[0005] Embodiments relate to polyurethane foams and compositions having high density and stiffness, particularly at thicknesses as low 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, where a catalyst package retards foam formation and can remain a workable liquid at temperatures up to 50°C for enhanced in-mold performance. The high MW polyether polyol can also include at least one high MW polyether polyol capped with ethylene oxide. Polyurethane foams produced by the compositions disclosed herein may be from closed-cell foams and may be thermally insulating.

[0006] As used herein, a "high density" foamed polyurethane composition is one that has a density of 200 kg / m 3 ~700kg / m 3 , or 250 kg / m 3 ~700kg / m 3 The density may range from 0.01 to 0.01.

[0007] Unless otherwise specified, all molecular weights herein are listed as number average molecular weights.

[0008] Polyurethane (PU) foams and methods for producing foams include combining a reactive chemical component, such as an isocyanate component, with an isocyanate-reactive component to produce a foam-forming composition. The isocyanate component contains a diisocyanate or polyisocyanate containing reactive isocyanate (N=C=O) functional groups. The isocyanate-reactive component contains two or more functional groups, such as hydroxyl or amine, that react with the isocyanate functional groups. The foam-forming composition may also include other additives, such as suitable catalysts, surfactants, flame retardants, viscosity modifiers, fillers, and blowing agents, which may be added to either or both of the isocyanate and the isocyanate-reactive component.

[0009] The isocyanate and isocyanate-reactive components can be combined in various stoichiometric ratios described by the isocyanate index, which is equal to the ratio of isocyanate groups to isocyanate-reactive groups (e.g., OH groups) multiplied by 100. The foam-forming PU compositions disclosed herein may have an isocyanate index ranging from 60 to 300 and are used to produce foam articles having relatively high densities while reducing excessive brittleness.

[0010] While increasing the relative amount of isocyanate is often used to increase stiffness, the foamed PU compositions disclosed herein may exhibit a relative increase in stiffness and flexural modulus at lower relative isocyanate indexes. The foamed polyurethane compositions may also exhibit good performance at relatively thin thicknesses ranging from 1 mm to 10 mm, or from 1 mm to 5 mm. The foamed PU compositions may have a torsional (i.e., shear) modulus greater than 150 MPa, or greater than 175 MPa, as determined by ASTM D5279-21. In some cases, the foamed PU compositions may have a torsional (i.e., shear) modulus ranging from 150 MPa to 800 MPa. The foamed articles may also exhibit reduced elongation at break values ​​(e.g., elongation of 6% or more) when tested in a microtensile tester according to ASTM D1708-18 standard.

[0011] The foam-forming PU compositions disclosed herein may exhibit slower foam rise (creaming) after dispensing (or spraying) compared to standard foam compositions, which can increase flowability and coverage in molding applications, particularly for molds with large surface areas and / or complex geometries. In some cases, the foam-forming PU compositions may include isocyanates and isocyanate-reactive components that remain liquid at ambient temperature for 30 seconds or more after mixing, or for 60 seconds or more after mixing. Ambient temperature may range from 15°C to 35°C, with room temperature often being about 23°C. In some cases, the isocyanates and isocyanate-reactive components remain liquid for 30 seconds or more at temperatures up to molding temperatures, such as up to 50°C.

[0012] The foam-forming PU compositions disclosed herein include two-component compositions containing an isocyanate component and an isocyanate-reactive component, as well as various additives, such as a blowing agent and catalyst combination. The isocyanate-reactive component may include a polyether polyol, particularly a combination of (1) a low molecular weight (MW) polyether polyol having an average hydroxyl equivalent weight 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 polyol may be ethylene oxide (EO)-capped at a weight percent (wt%) of 3% to 80% by weight of the polyol.

[0013] The polyether polyols disclosed herein may include products obtained by the polymerization of cyclic oxides, such as ethylene oxide ("EO"), propylene oxide ("PO"), butylene oxide ("BO"), tetrahydrofuran, or epichlorohydrin, in the presence of a polyol initiator having a functionality ranging from 2 to 8, or from 2 to 5. As understood in the art, the initiator compound or combinations thereof are generally selected based on the desired functionality of the resulting polyether polyol. The polyether polyols may be formed using one or more polyol initiators such as neopentyl glycol; 1,2-propylene glycol; trimethylolpropane; pentaerythritol; sorbitol; sucrose; glycerin; alkanediols such as 1,6-hexanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,3-propanediol, 1,2-propanediol, 1,5-pentanediol, 2-methylpropane-1,3-diol, 1,4-cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,5-hexanediol; ethylene glycol; diethylene glycol; triethylene glycol; 9(1)-hydroxymethyloctadecanol, 1,4-bishydroxymethylcyclohexane; hydrogenated bisphenols; 9,9(10,10)-bishydroxymethyloctadecanol; 1,2,6-hexanetriol; and combinations thereof.

[0014] The isocyanate-reactive component can include one or more low MW polyether polyols having an average hydroxyl equivalent weight in the range of 30 Da to 400 Da, as determined according to ASTM D4274 D. In some cases, the low MW polyether polyols can have a number average molecular weight of 450 Da or less, or 200 Da or less. In some cases, the low MW polyether polyols include propoxylated derivatives of polyol initiators such as glycerin, sorbitol, and butanediol.

[0015] The isocyanate-reactive component may include a low MW polyether polyol present in a weight percent (wt%) range of 25 wt% to 75 wt%, or 30 wt% to 70 wt%.

[0016] In some cases, the isocyanate-reactive component may include a low MW polyol, such as the polyol initiators disclosed above, instead of or in addition to the low MW polyether polyol. In some cases, the isocyanate component may include a low MW polyol in a weight percent range of 1% to 10%, or 1% to 5%, based on the weight of the isocyanate-reactive component.

[0017] The isocyanate-reactive component may comprise one or more high MW polyether polyols having an average functionality ranging from 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 8,000 Da. The high MW polyether polyols may be prepared using chemicals and polyol initiators as described above for polyether polyols. The high MW polyether polyols may have a functionality of 1 to 8 and a primary hydroxyl content of greater than 60%, greater than 40%, or greater than 20%.

[0018] Additionally, high MW polyether polyols may be capped with ethylene oxide oligomers or polymers (EO-capped), which modify elongation and toughness properties when compared to rigid foams of similar density. The EO-capped high MW polyether polyols may have a weight percent (wt%) ethylene oxide (EO) content of 3 wt% to 80 wt%. In some cases, the high MW polyether polyols may comprise 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 an average molecular weight ranging from 800 Da to 10,000 Da, with greater than 40% primary hydroxyls. In some cases, the EO content may range from 3 wt% to 50 wt%. In some cases, the EO content may range from 3 wt% to 28 wt%, a functionality ranging from 1 to 8, a molecular weight ranging from 800 Da to 10,000 Da, and greater than 60% primary hydroxyls.

[0019] The isocyanate-reactive component can include a high MW polyether polyol in weight percent (wt%) ranging from 25 wt% to 75 wt%, 30 wt% to 70 wt%, or 35 wt% to 65 wt%, based on the sum of all polyols in the isocyanate-reactive component.

[0020] The foam-forming composition may include an isocyanate component containing one or more isocyanates, such as polymeric isocyanates, aromatic isocyanates, carbodiimide-modified isocyanates. The isocyanate species may be monomeric, oligomeric, prepolymeric, etc. The isocyanate component may include, for example, one or more isocyanate and / or polyisocyanate compounds.

[0021] The isocyanate component may include a polyisocyanate having a nominal functionality greater than 1.5, or greater than 2.0. In some cases, the isocyanate component may include a polyisocyanate having an isocyanate (NCO) content by weight greater than or equal to 10%, greater than or equal to 20%, or greater than or equal to 30%.

[0022] The isocyanate compound can be an aliphatic polyisocyanate, a cycloaliphatic polyisocyanate, an araliphatic polyisocyanate, an aromatic polyisocyanate, or a combination 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, among others. 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. In addition to the isocyanates mentioned above, some modified polyisocyanates may be utilized, including uretdione, isocyanurate, carbodiimide, uretonimine, allophanate, or biuret structures, and combinations thereof, among others.

[0023] The isocyanate may have an average isocyanate equivalent weight of from 80 g / eq to 400 g / eq, for example, 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.

[0024] The isocyanate component may also include an isocyanate prepolymer resulting from the reaction of an isocyanate-reactive compound with a molar excess of a polyisocyanate compound or a polymeric isocyanate compound under conditions that do not cause gelation or solidification, and the isocyanate prepolymer may have a higher average isocyanate equivalent weight of greater than 400 g / eq. Formation of an isocyanate prepolymer is known in the art and may include reacting (1) at least one isocyanate compound with (2) at least one polyol compound. The isocyanate prepolymer may be described by its isocyanate index, which is defined as the ratio of isocyanate groups to isocyanate-reactive groups (e.g., OH groups) multiplied by 100. The isocyanate prepolymers disclosed herein may have an isocyanate index ranging from 60 to 300, 75 to 300, or 100 to 200.

[0025] Examples of commercially available isocyanates include, but are not limited to, VORANATE™, PAPI™, and ISONATE™ trade name polyisocyanates, such as VORANATE™ M 220 and PAPI™ 27, all of which are available from The Dow Chemical Company.

[0026] The isocyanate component can 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 of as low as 150 g / mol, 200 g / mol, 250 g / mol, or 300 g / mol to as high as 350 g / mol, 400 g / mol, 450 g / mol, 500 g / mol, or 750 g / mol. Number average molecular weight values ​​reported herein are determined by end group analysis, gel permeation chromatography, and other methods known in the art. The isocyanate compound can be a monomer and / or polymer known in the art.

[0027] The foam-forming composition may include an isocyanate component in weight percent (wt%) ranging from 30 wt% to 80 wt%, 35 wt% to 75 wt%, 40 wt% to 70 wt%, or 45 wt% to 65 wt%.

[0028] The foam-forming PU composition may contain one or more blowing agents, including chemical blowing agents such as water and aqueous fluids, hydrocarbons, acids, and volatile organics, as well as physical blowing agents including gases such as nitrogen, air, and carbon dioxide. The blowing agent may be added to the foam-forming composition during mixing in a weight percent (wt%) ranging from 0.05 wt% to 10 wt%, or from 0.1 wt% to 5 wt%. In some cases, the one or more blowing agents may be present in a weight percent (wt%) of 0.45 wt% or less, or 0.4 wt% or less, based on the total polyols in the isocyanate-reactive composition. The blowing agent may be added to the isocyanate component and / or isocyanate-reactive component in an amount sufficient to provide a mixture having the corresponding weight percents described above.

[0029] The foam-forming PU composition may include a catalyst package containing one or more catalysts, which 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 distinguished by their tendency to favor either a urea (blow) reaction in the case of a blowing catalyst, or a urethane (gel) reaction in the case of a gelling catalyst. A trimerization catalyst may be utilized to promote the isocyanurate-forming reaction in the composition. The catalyst package may also be added as a separate stream to the reaction mixture of the isocyanate and the isocyanate-reactive composition. The catalyst package may be present in the foam-forming composition in a weight percent (wt%) ranging from 0.1 wt% to 5 wt%, or from 1 wt% to 5 wt%.

[0030] The blowing catalyst may include bis-(2-dimethylaminoethyl)ether, pentamethyldiethylenetriamine, triethylamine, tributylamine, N,N-dimethylaminopropylamine, dimethylethanolamine, N,N,N',N'-tetra-methylethylenediamine, and combinations thereof, among others. One example of a commercially available blowing catalyst is POLYCAT® 5 from Evonik, among other commercially available blowing catalysts.

[0031] Gelling catalysts include organometallic compounds, cyclic tertiary amines and / or long-chain amines (e.g., containing several nitrogen atoms), and combinations thereof. Organometallic compounds include organotin compounds such as tin(II) salts of organic carboxylic acids, such as tin(II) diacetate, tin(II) dioctanoate, tin(II) diethylhexanoate, and tin(II) dilaurate, and dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate. Bismuth salts of organic carboxylic acids can also be used as gelling catalysts, such as bismuth octanoate. Cyclic tertiary amines and / or long-chain amines include dimethylbenzylamine, triethylenediamine, and combinations thereof. Examples of commercially available gelling catalysts are POLYCAT® 8, DABCO® 33-LV, and DABCO® T-12 from Evonik, among other commercially available gelling catalysts.

[0032] The trimerization catalyst may include any such catalyst known in the art. Examples of trimerization catalysts include N,N',N"-tris(3-dimethylaminopropyl)hexahydro-s-triazine; N,N-dimethylcyclohexylamine; 1,3,5-tris(N,N-dimethylaminopropyl)-s-hexahydrotriazine; [2,4,6-tris(dimethylaminomethyl)phenol]; potassium acetate, potassium octanoate; 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. Some commercially available trimerization catalysts include, for example, DABCO® TMR-2, DABCO® TMR-20, DABCO® TMR-30, DABCO® TMR-7, DABCO® K, among other commercially available trimerization catalysts. 2097; DABCO® K15, POLYCAT® 41, and POLYCAT® 46, each available from Evonik.

[0033] The catalyst package may also include a "latent catalyst" or "delayed catalyst," which is defined as a catalytic compound that has low catalytic activity or is relatively inactive at ambient temperature and becomes more catalytically active upon heating by dissociation, decoordination, ring-opening, ionization, or tautomerization, etc., to catalyze at least one of the chemical reactions involved in the production of PU foam. Ambient temperature may range from 15°C to 32°C, and room temperature is often about 23°C.

[0034] Latent / delayed action catalysts may be gelling, blowing, and / or trimerization type catalysts, depending on their function in the foaming process. Latent catalysts are often a subset of tertiary amine gelling catalysts, including acid salts, phenol salts, or complexes of tertiary amine catalysts, where the acid or phenol is often a carboxylic acid or phenolic species such as, but not limited to, formic acid, acetic acid, propionic acid, 2-ethylhexanoic acid, phenoxyacetic acid, gluconic acid, tartaric acid, citric acid, phenol, nonylphenol, diisopropylphenol, and mixtures thereof. Some commercially available latent catalysts that can be used 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.

[0035] The catalyst package may include a mixture of one or more of the above catalysts and / or latent catalysts in weight percent (wt%) ranging from 0.1 wt% to 5 wt% of the foam-forming composition. Optionally, the catalyst package may be added to the isocyanate component and / or isocyanate-reactive component in an amount sufficient to provide a mixture having the corresponding wt% above.

[0036] The foam-forming composition may include one or more fillers, including glass fiber, fibers, silica, CaCO3, kaolin, talc, alumina, alumina trihydrate (ATH), and the like. The one or more fillers may be added in weight percents (wt%) ranging from 0 wt% to 15 wt%, or from 1 wt% to 10 wt% of the foam-forming composition. In some cases, the filler may be added to the isocyanate component and / or isocyanate-reactive component in an amount sufficient to provide a mixture having the corresponding wt% above.

[0037] The foam-forming composition may include a surfactant present in the isocyanate and / or isocyanate-reactive component in an amount sufficient to provide a surfactant weight percentage of 0.1% to 5% by weight of the foam-forming mixture. Surfactants may include silicone-based surfactants, polyether-modified silicone surfactants, and organic surfactants. Some representative surfactants include polysiloxane polyoxyalkylene 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, such as those 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 aryl acid sulfates, alkyl sulfonates, alkylaryl sulfonic acids, and combinations thereof. Some commercially available surfactants useful in isocyanate-reactive compositions include VORASURF™ DC 193, VORASURF™ 504, TEGOSTAB® B8418, and mixtures thereof.

[0038] The composition 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 poloxamers, viscosity modifiers, cell openers, emulsifiers, adhesion modifiers, antioxidants, surfactants, colorants, UV stabilizers, antistatic agents, bacteriostatic agents, and mixtures thereof.

[0039] The foam-forming compositions, foamed polyurethane articles, and methods of the present disclosure are useful for a variety of end uses, such as space-filling applications and automotive applications (e.g., for control modules). The foamed polyurethane articles can be used to at least partially coat or encapsulate articles such as batteries and other electronic components. The foamed polyurethane articles can also be used for thermal insulation. Additionally, the foamed polyurethane articles can be used as fire-blocking materials. Generally, the foamed polyurethane articles of the present disclosure offer a combination of desirable physical properties over conventional foams, including one or more of the following: reduced weight, reduced density, increased heat resistance, increased stability, etc. The foamed polyurethane articles can be formed in environments where hydrogen gas formation is a concern. Additionally, the foamed polyurethane articles can be foamed at or around room temperature, which is useful for temperature-sensitive applications.

[0040] Foam production involves the following steps: (1) equilibrating the isocyanate component and the isocyanate-reactive composition for mixing; (2) preheating the mold surface to a molding temperature (typically, e.g., 25°C to 60°C) with optional woven and nonwoven glass or carbon fiber fabrics (e.g., fiber mats, meshes, or preforms) placed in the mold; (4) determining the fill level of the foam-forming reaction mixture to achieve the desired overfill (typically, e.g., 150% to 400%); (5) thoroughly and rapidly mixing the isocyanate component and the isocyanate-reactive composition within 10 seconds; and (6) performing a time-lapse analysis at the start of mixing step (5). (7) immediately transferring the foam-forming reaction mixture into a mold or injecting the foam-forming reaction mixture directly into the mold; (8) closing the mold (if not a closed mold) and reacting the resulting foam-forming reaction mixture to form a PU foam article (i.e., a molded foam article) in the mold; (9) opening the mold after a preset demold time has been reached; (10) demolding the foam article; and (11) visually inspecting the foam article for defects such as expansion, contraction, blistering, and cracks after the foam article has been completely demolded.

[0041] The process for preparing the PU foam article can be accomplished by any process technique known in the art. Generally, the PU foam article of the present disclosure may be produced by a continuous or discontinuous process, including a process commonly referred to as a reaction injection molding (RIM) process or a casting process, in which the subsequent foaming reaction and curing take place in a mold.

[0042] Mixing of the components of the foam-forming composition can be carried out at a temperature of 5° C. to 80° C., 10° C. to 60° C., or 15° C. to 50° C. Molding of the PU foam article can be carried out at a mold temperature range of 20° C. to 80° C., 30° C. to 70° C., or 40° C. to 60° C. [Example]

[0043] The following examples are provided to illustrate embodiments of the present invention, but are not intended to limit its scope. All parts and percentages are by weight unless otherwise indicated.

[0044] [Table 1]

[0045] Procedures for analyzing foaming and molding The isocyanate-reactive component reagents were weighed on an analytical balance and combined using a DAC 600.1 FVZ-K Speed ​​Mixer. Batches were 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 was recorded. A sample of the foam-forming composition was then analyzed as a liquid mixture or decanted in the mold. Samples were also prepared by mixing using a high-pressure spray system. The isocyanate and isocyanate-reactive components were combined by high-pressure spraying in a GRACO sprayer at 1000-3000 psi.

[0046] After mixing the foam-forming composition, it was sprayed (for the inventive examples) and / or poured (for the inventive examples and comparative examples) into a container (e.g., an open cup or mold) and the reaction rate was analyzed. The samples were allowed to react, and the cream time, rise time, and green strength were recorded. Timing began when the two components were mixed. Cream time is defined as the time between the start of mixing and the rise of the liquid level (the start of foam rise). Rise time is defined as the time between the start of mixing and the foam rising until it stabilizes at a specific height (including the cream time). Gel time is defined as the time between the start of mixing and the point at which the material forms a continuous thread when probed. Tack-free time is defined as the time between the start of mixing and the time at which no thread comes off the surface when taped with a tongue depressor stick (including the cream time and rise time). Handling time is defined as the time between the start of mixing and the foam developing sufficient rigidity to resist compression when pressed with a finger (with significant force).

[0047] Mold tests included parallel and perpendicular molds. For the parallel rise test in Mold A (19 cm x 12.5 cm x 0.2 cm, where 19 cm is the rise direction), the mold was preheated in an oven at 40°C and the mixed resin sample was transferred into the mold for a time of approximately 32-34 seconds. The mold was then placed in a 40°C oven for 20 minutes. The mixed resin sample it contained was then measured and the amount of material remaining in the cup after pouring was calculated.

[0048] The sample is then demolded and the foam dimensions, weight are recorded and the density is calculated. If the sample foam breaks, shatters or snaps during demolding, it is considered too brittle for further testing. A "testable" foam does not break during demolding or while cutting the sample shape for property testing. The remaining testable foam sample was allowed to cure overnight before cutting the sample for property testing.

[0049] For the vertical rise test in Mold B (20 cm x 15 cm x 0.5 cm, where 0.5 cm is the rise direction), the mold was preheated in an oven at 40°C and the mixed resin sample was transferred into the mold for a time of approximately 32-34 seconds. The mold was then placed in a 40°C oven for 20 minutes. The mixed resin sample it contained was then measured and the amount of material remaining in the cup after pouring was calculated.

[0050] The sample is then demolded, and the foam dimensions and weight are recorded, and the density is calculated. The surface hardness of the foam sample is measured with a Durometer (Shore A scale) after demolding (10-12 minutes), and then 30 minutes later with a Durometer (Shore D scale). If the sample foam breaks, shatters, or snaps during demolding, it is considered too brittle for further testing. A "testable" foam does not break during demolding or while cutting the sample shape for property testing. The remaining testable foam sample was allowed to cure overnight, after which samples were cut for property testing.

[0051] A series of properties (I-XI) were tested on the samples as follows:

[0052] The properties of sample (I) are a qualitative description of the brittleness of the sample in terms of whether it was possible to demold it after foaming for further testing of its mechanical properties.

[0053] Density (II) is a quantitative measure of the density (ie, weight / volume) of a foam sample, performed according to ASTM D3574 Test A.

[0054] The elastic modulus E' (III), elongation at break (IV), and ultimate tensile strength (V) were all obtained on a micro-tensile tester using ASTM D1708-18 standard, and 0.2 mm thick PU foam sheets were obtained after molding, aging at room temperature (23 °C) for 2 days, and punched into dog-bone shapes.

[0055] The shear moduli (VI-VIII) and glass transition temperatures (IX) in torsion mode were obtained by dynamic mechanical analysis (DMA) using ASTM D5279-21 on a TA Instruments Advanced Rheometric Expansion System (ARES-G2) equipped with liquid nitrogen environmental control and a torsion-rectangle fixture. 2 mm thick rectangular specimens (45 mm long and 12.8 mm wide) were punched from the prepared foams in metal molds (A and B). The specimen length was aligned axially with respect to the torsion axis, and DMA was performed in torsion mode. The temperature was ramped from -70 °C to 200 °C at a rate of 3 °C / min. The test frequency was 1 Hz at 0.05% torsional strain, and the specimen was held taut with an axial tension of 0.098 N, with a data collection interval of 30 s per point. The primary outputs from the characterization identified were shear modulus (G'), loss modulus (G''), and storage modulus in Tan δ.

[0056] Cream time (X) is a quantification of the time to foam formation measured after combining the isocyanate and isocyanate-reactive components by high-pressure mixing and dispensing into cup (cream) or mold B (handling time). For cream time, the time to foam bubble formation and rise time were visually determined and recorded. Handling time is defined as the time between the start of mixing and the foam developing sufficient stiffness to resist compression by probing with a tongue depressor. Hardness was measured after demolding, and handling time was recorded as Shore D > 20.

[0057] Lap shear adhesion strength (XI) was determined according to ASTM D-1002-10 and quantified the apparent shear strength of adhesively bonded metal specimens with a single lap connection by tensile loading. A 1 mm thick polypropylene spacer was placed between the metal substrates with a 0.5 inch overlap. The 1 inch wide panels were assembled using removable tape at the bottom. Resin was filled into the cavity from the top, penetrated by gravity, and sealed. The specimens were then placed in an oven at 40°C for 3 hours to cure. The density of the foam between the plates was confirmed gravimetrically. The substrates included e-coated cold-rolled steel (1 inch x 4 inch x 0.032 inch) from a commercial source, i.e., ACT Panels. Failure during the lap shear test was classified as adhesive failure (foam residue on only one side of the substrate due to adhesive failure), cohesive failure (foam residue on both sides of the substrate due to foam failure), or substrate failure (e-coat peeling on the foam or substrate rupture).

[0058] Viscosity measurements of the isocyanate-reactive components were performed on a TA Instruments AR 2000 rheometer with a 54 mm cone-plate geometry and a 450 micron gap. Data were collected from 100 to 0.01 seconds at a temperature of 25°C. -1 Viscosity was measured at 25°C using ASTM D4889 for the isocyanate component and the individual polyol components.

[0059] The hydroxyl number (OH number) of each polyether polyol in the formulation is determined according to ASTM D4274, and the OH number is used to determine the hydroxyl equivalent weight.

[0060] Water content was determined using Karl Fischer volumetric titration according to ASTM E203-16 for Standard Test Methods for Water.

[0061] Example 1: Preparation and characterization of PU foams In this example, comparative water-blown foam samples (C) and (I) of the present invention were prepared as shown in Tables 2-7.

[0062] [Table 2]

[0063] [Table 3]

[0064] [Table 4]

[0065] [Table 5]

[0066] [Table 6]

[0067] [Table 7]

[0068] The properties of comparative samples C1-C8 and inventive samples I1-I13 are shown in Tables 8-13. Property I (foam property) indicates whether the formulation foamed or broke / shattered during the process of preparing the sample for testing for properties III-IX.

[0069] [Table 8]

[0070] [Table 9]

[0071] [Table 10]

[0072] [Table 11]

[0073] [Table 12]

[0074] [Table 13]

[0075] The results show that the comparative examples are more brittle than the comparative examples. For example, comparative samples C1-C3 were crushed or not foamed (Property I), while C5 exhibits a lower elongation at break than required (i.e., Property IV < 6%). In other cases, comparative samples C4 and C7-8 exhibited lower ultimate tensile strength than required (Property V < 10 MPa). Finally, for C6, the mechanical properties are satisfactory (Property II > 700 kg / m 3 ).

[0076] In comparison, inventive samples I1-I13, which contain polyether polyols having average hydroxyl equivalent weights of 800 Da or greater at concentrations of 25 wt. % or greater in the isocyanate-reactive component, exhibit elongation at break values ​​(Property IV) of 6% or greater. Ultimate tensile strength (Property V) remains greater than 10 MPa for all inventive samples. Foam densities (Property II) for the inventive samples range from 400 to 700 kg / m 3 The foam adhesion was tested using lap shear adhesion (Property XI) to >8 MPa for I2.

[0077] Additionally, for inventive samples I1-I13, the incorporation of ethylene oxide (EO)-capped polyether polyols with OHW greater than 1900 Da resulted in an isocyanate index of 115 and a yield of 250-700 kg / m 3 The foam modulus (Property III) was improved at foam densities in the range of 0.01 to 0.01 (Property II). Furthermore, the elongation at break (Property IV) of the foam samples of the present invention was maintained and / or increased. Thus, not only was stiffness improved, but so was the elongation at break and, therefore, ultimate tensile strength (Property V).

[0078] While the foregoing is directed to exemplary embodiments, other and further embodiments may be devised without departing from the basic scope thereof, which scope is determined by the claims that follow.

Claims

1. 1. A foam-forming composition comprising: (a) at least one isocyanate component; (b) at least one isocyanate-reactive composition, (i) at least one low molecular weight polyether polyol having an average functionality in the range of 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 ranging from 1500 Da to 10,000 Da; and (iii) optionally, at least one high molecular weight polyether polyol having an average functionality in the range of 1 to 8 and a hydroxyl equivalent weight in the range of 800 Da to 10,000 Da; at least one isocyanate-reactive composition, wherein (ii) is present in a weight percent (wt%) ranging from 25 wt% to 75 wt% based on the total polyol in said isocyanate-reactive composition; (c) a catalyst package comprising at least one latent gelling catalyst; (d) at least one blowing agent; The foam-forming composition has an isocyanate index of 60 to 300, and the foam has a viscosity of 250 kg / m according to ASTM D1622-20. ３ ~750 kg / m ３ 1. The foam-forming composition of claim 1, wherein the foam-forming composition has a molded foam density of

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

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

4. 4. The composition of claim 3, wherein the at least one blowing agent is present at 0.45 weight percent or less of the total of the polyols in the isocyanate-reactive composition.

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

6. 10. The composition of claim 1, wherein polyols (b)(ii) and (b)(iii) are present in a combined weight percent range of 25% to 75% by weight relative to the isocyanate-reactive component.

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

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

9. A foam article prepared from the composition of claim 1.

10. 10. The foam article of claim 9, having an elongation at break according to ASTM D1708-18 greater than 6%.

11. 9. A method of making polyurethane rigid molded foam, comprising providing the foam-forming composition of any one of claims 1 to 8 and reacting the foam-forming composition to produce a foam article.

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