HIGH NITROGEN CONTENT POLYURETHANE FOAMS

Abstract

The invention pertains generally to a shelf-stable polyurethane HFO-blown two-component polyurethane foam composition which includes incorporating nitrogen-containing aminopolyols.

Claims

1. A low-pressure two-component polyurethane foam composition in which A-side and B-side reactants comprise: at least one A-side diisocyanate and at least one HFO propellant; at least one B-side polyol, wherein the at least one B-side polyol comprises at least one aminopolyol, at least one B-side plasticizer, at least one surfactant, at least one catalyst, wherein the at least catalyst is a metal-based catalyst; and at least one HFO propellant; wherein a theoretical nitrogen content of the polyurethane foam composition is greater than 1.0 wt. %; and a catalytic decay ratio of the polyurethane foam being approximately equal to or less than 2.5.

2. The low-pressure two-component polyurethane foam composition of claim 1 wherein the at least one catalyst is at least two catalysts, and further wherein at least one of the at least two catalysts is a nitrogen-containing catalytic compound has at least one 6-membered ring groups attached to the nitrogen.

3. The low-pressure two-component polyurethane foam composition of claim 1 wherein the at least one nitrogen-containing catalytic compound has at least two 6-membered ring groups attached to the nitrogen.

4. The low-pressure two-component polyurethane foam composition of claim 3 wherein the at least one nitrogen-containing catalytic compound is n-methyldicyclohexylamine; and the at least one metal-containing catalytic compound is di-N-butylbis(dodecylthio)tin.

5. The low-pressure two-component polyurethane foam composition of claim 1 wherein the at least one amino polyol contains less than or equal to approximately 8 wt. % nitrogen.

6. The low-pressure two-component polyurethane foam composition of claim 5 wherein the at least one amino polyol contains less than or equal to approximately 7 wt. % nitrogen.

7. The low-pressure two-component polyurethane foam composition of claim 6 wherein the at least one amino polyol contains less than or equal to approximately 6 wt. % nitrogen.

8. The low-pressure two-component polyurethane foam composition of claim 7 wherein the at least one amino polyol contains less than or equal to approximately 5 wt. % nitrogen.

9. The low-pressure two-component polyurethane foam composition of claim 8 wherein the at least one amino polyol contains less than or equal to approximately 4 wt. % nitrogen.

10. The low-pressure two-component polyurethane foam composition of claim 1 wherein the B-side further comprises: less than approximately 2.5 wt. % of added water; and less than approximately 5 wt. % of added glycerin.

11. The two-component polyurethane foam composition of claim 1 wherein the at least one amino polyol is selected from the group consisting of ##STR00037## wherein n ranges from 1 to 50 ##STR00038## wherein 1<r+s+t+u+v+w+x+y+z<8.5; and further wherein r, s, t, u, v, w, x, y and z independently range from 0 to 10 inclusive; and ##STR00039## wherein n and k independently range from 1 to 25 inclusive.

12. The two-component polyurethane foam composition of claim 11 wherein the at least one amino polyol is selected from the group consisting of ##STR00040## wherein n ranges from 1 to 50; and ##STR00041## wherein 1<r+s+t+u+v+w+x+y+z<8.5; and further wherein r, s, t, u, v, w, x, y and z independently range from 0 to 10 inclusive.

13. The two-component polyurethane foam composition of claim 11 wherein the at least one HFO propellant is a liquid HFO propellant at room temperature and pressure.

14. The two-component polyurethane foam composition of claim 11 wherein the at least one HFO propellant is a gaseous HFO propellant at room temperature and pressure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a graph of CDR ratio over time of several synthesized polyurethane foams.

DETAILED DESCRIPTION OF THE INVENTION

[0021] The best mode for carrying out the invention will now be described for the purposes of illustrating the best mode known to the applicant at the time of the filing of this invention. The examples and figures are illustrative only and not meant to limit the invention, as measured by the scope and spirit of the claims.

[0022] Unless the context clearly indicates otherwise: the word and indicates the conjunctive; the word or indicates the disjunctive; when the article is phrased in the disjunctive, followed by the words or both or combinations thereof both the conjunctive and disjunctive are intended.

[0023] As used in this application, the term approximately is within 10% of the stated value, except where noted.

[0024] As used in this application, the term catalytic decay ratio or CDR is defined as the ratio of accelerated aging gel time to that of initial gel time. This value was recorded in order to determine gel time shift over the age of the system. A low CDR would indicate greater catalytic stability over that of a high CDR. For long term stability, the CDR ratio should remain less than or equal to approximately 2.5, more preferably less than or equal to approximately 2.0.

[0025] As also used in this application, shelf life means a polyurethane foam which when subjected to accelerated aging, still results in a foam having physical properties such as foam height, gel time, density, etc., preferably within approximately 25% of those parameters prior to accelerated aging.

[0026] As further used in this application, accelerated aging means storing the reactant combination and propellant at 50? C. for 12-48 days prior to reacting the A and B cylinders and spraying the polyurethane foam. Using the Arrhenius equation, this equates to 3-12 months at room temperature.

[0027] As additionally used in this application, low-pressure means a pressure less than 250 psi at room temperature. Typically, the pressure in the full cylinders is between approximately 130-250 psi.

[0028] As used in this application, amino polyol means a polyol, including, but not limited to polyester polyols, polyether polyols, natural polyols, polycarbonate polyols, etc., having a nitrogen content of at least about 1% by weight, preferably at least ?1.1% by weight, preferably at least ?1.2% by weight, preferably at least ?1.3% by weight, preferably at least ?1.4% by weight, preferably at least ?1.5% by weight, preferably at least ?1.6% by weight, preferably at least ?1.7% by weight, preferably at least ?1.8% by weight, preferably at least ?1.9% by weight, preferably at least ?2.0% by weight, preferably at least ?2.2% by weight, preferably at least ?2.4% by weight, preferably at least ?2.6% by weight, preferably at least ?2.8% by weight, preferably at least ?3.0% by weight, preferably at least ?3.5% by weight, preferably at least ?4.0% by weight, preferably at least ?4.5% by weight, preferably at least ?5.0% by weight, preferably at least ?5.5% by weight, preferably at least ?6.0% by weight, preferably at least ?7% by weight, preferably at least ?8% by weight, preferably at least ?9% by weight, preferably at least ?10% by weight, preferably at least ?12% by weight.

[0029] The literature would appear to teach that polyol pre-mixes contain less than 1 wt. % nitrogen based on the weight of the polyol pre-mix, and preferably the polyol premix has a nitrogen content not exceeding 0.1 wt. % nitrogen based on the weight of the polyol pre-mix (see United States Published Patent Application 2018/0079881 A1).

[0030] The invention will now be described by a series of examples and identification of various reactants used in the invention.

[0031] Polyols

[0032] As illustrated in a non-exhaustive, non-exclusive, exemplary list below, there are a myriad of polyols (both polyester polyols and polyether polyols) which are useful in effecting the reaction with a diisocyanate to form a foam having varying characteristics. The ability to add widely varying amounts of polyols and/or different polyol combinations could easily be affected via either supplementing existing amounts of B-side polyol(s) via the third stream or by essentially eliminating B-side polyol(s) and making their addition via the third stream. In one aspect of the invention, the polyol(s) are added by using a pumping mechanism from a B-side cylinder or other container, and the third stream is employed to add the blowing agent and/or pressurizing agent.

TABLE-US-00001 Polyester Polyol(s) [00006] Hydroxyl Number, mg KOH/g 230-250 Water, % by wt., max. 0.15 Acid Number, mg KOH/g, max. 0.6-1.0 Viscosity at 77? F. (25? C.), cP 2,000-4,500 Equivalent Weight (average) 234 Molecular Weight (average) 468 Color, Gardner 4 Density at 77? F. (25? C.), lb./U.S. gal 9.9 n 1-30 Specific Gravity at 77? F. (25? C.) 1.19 [00007] n ranges from 1-30 inclusive; o ranges from 1 to 5 inclusive; and p ranges from 1 to 5 inclusive; [00008] Hydroxyl Number, mg KOH/g 335-365 Water, % by wt., max. 0.15 Acid Number, mg KOH/g, max. 0.5-2.0 Viscosity at 77? F (25? C.), cP 2,500-3,500 Color, Gardner 4-5 Specific Gravity at 77? F. (25? C.) 1.233 Functionality 2.2 n 1-25 DEG/TA backbone (diethylene glycol terephthalate anhydride) [00009] n ranges from 1-30 inclusive; o ranges from 1 to 5 inclusive; and p ranges from 1 to 5 inclusive; Stepanpol? Aromatic diethylene glycol-phthalic anhydride polyester polyol (DEG/PA backbone)- PS-3152 avg. viscosity @ 25? C. ~2756 cP; Avg. ~350; and Hydroxyl Value (mgKOH/g) ~300-350 Isoexter 3061 Aromatic phthalic anhydride polyester polyol Stepanpol? Saturated polyester polyol (DEG/AA backbone) wherein AA = adipic acid)- avg. PC 2011-225 viscosity @ 25? C. ~400-600 cP; Avg. MW ~500; and Hydroxyl Value (mgKOH/g) ~215-235 Stepanpol? Hybrid phthalate anhydride polyester polyol (DEG/PA backbone)- avg. viscosity @ PDP-70 25? C. ~1900 cP; Avg. MW ~1600; and Hydroxyl Value (mgKOH/g) ~70 Stepanpol? Aromatic polyester polyol PS-3422 Stepanpol? Aromatic phthalic anhydride polyester polyol (DEG/PA backbone)- avg. viscosity @ PS-1752 25? C. ~3900 cP; Avg. MW ~640; and Hydroxyl Value (mgKOH/g) ~175 with some propylene carbonate (unspecified by the manufacturer)

[0033] Furthermore without being bound to any one theory or mode-of-operation, it is believed that the use of glycerin as a fluoride ion scavenger may beneficially increase the shelf life stability of this product. Note that it is now possible to have significant amounts of polyester polyols and polyether polyols in the composition, provided that at least some glycerin (synonymously glycerol) is also present, a simple triol. It is recognized that the fluoride ion scavenger will preferably have a functionality of?2.0, preferably?2.2.

[0034] While glycerin is one specific example of a triol with scavenging capabilities, the invention is not limited to such. In fact, lower molecular weight polyols, e.g., a triol or specifically a polyol (including diols) having a functionality?2, preferably?2.2 are believed to be useful in this invention. Molecular weight ranges of the polyol(s) are anticipated to range between ?90 to ?1500 g/mol are believed to be applicable to this invention.

TABLE-US-00002 Polyether Polyol(s) (actual and potential) [00010] sucrose polyether polyol based on a sucrose-glycerol mixture with a functionality of ~4.5 having a hydroxyl number of ~360 wherein x ranges from 1 to 100 [00011] glycerin-based oxypropylated polyether polyol having a functionality greater than or equal to 3 and a molecular weight of about 600, an OH number of about 274, an acid number (max) of 0.05, an average pH of about 6.5 wherein n ranges from 2 to 50 [00012] 1,2,3-propanetriol, methyloxirane polymer wherein n ranges from 2 to 50 Poly-G? Polyether triol having an average molecular weight of ~4,000, an OH number of about 30-42 40, an acid number (max) of ~0.03, an average pH of about 5.5 [00013] ethylene oxide triol, ethylene oxide capped, and glycerin initiated wherein the polyol has a hydroxyl number of ~35 and a M.W. of ~4800 and provides for chain entanglement and packing without distorting a profile wherein x ranges from 2 to 50. [00014] 3,3,3-[nitrilotris(ethane-2,1-diyloxy)]tripropan-1-ol [00015] ethoxylatedtriethanolamine wherein n ranges from 1 to 50 [00016] and [00017] wherein 1 <r + s + t + u + v + w + x + y + z <8.5 r, s, t, u, v, w, x, y and z independently range from 0 to 10 inclusive OH # is 388, MW is 578 g/mol estimated nitrogen content ~4.93 wt. % [00018] OH # is 800, MW is 278 g/mol estimated nitrogen content is ~10.07 wt. % wherein n and k range from 1 to 25 inclusive [00019] Block copolymer of propylene oxide and polyethylethylene oxide having a nominal molecular weight of 4,000 and wherein n & m are integers ranging from 2 to 50. Poly-G Polyether polyol having a hydroxyl number of ~112 and a M.W. of ~1000 and a 20-112 viscosity @ 25? C. of ~145 cP [00020] Ethanol, 2,2 imino bis, polymer with 2-methyl oxirane, a polyether triol having a hydroxyl number of ~600 and a M.W. of ~163-280 and a viscosity @ 25? C. of ~380 cP estimated nitrogen content is ~4.98 wt. %

[0035] Flame Retardants and/or Plasticizers

[0036] As illustrated in a non-exhaustive, non-exclusive, exemplary list below, there are a myriad of flame retardants and/or plasticizers which are useful in modifying the properties of the reaction of a polyol with a diisocyanate to form a foam having varying characteristics. The ability to add widely varying amounts of flame retardants/plasticizers and/or different flame retardant/plasticizer combinations could easily be effected via either supplementing existing amounts of B-side flame retardant(s)/plasticizer(s) via the third stream or by essentially eliminating B-side flame retardant(s)/plasticizer(s) and making their addition via the third stream.

TABLE-US-00003 Tris (1-chloro-2-propyl) phosphate (TCPP) [00021] Tetrabromophthalate diol (PHT4-diol) [00022]

[0037] Surfactants

[0038] As illustrated in a non-exhaustive, non-exclusive, exemplary list below, there are a myriad of surfactants which are useful in modifying the properties of the reaction of a polyol with a diisocyanate to form a foam having varying characteristics. The ability to add widely varying amounts of surfactants and/or different surfactant combinations could easily be affected via either supplementing existing amounts of B-side surfactant(s) via the third stream or by essentially eliminating B-side surfactant(s) and making their addition via the third stream.

TABLE-US-00004 Trade name Composition (if known) Tegostab? B-8433 Polyether polydimethylsiloxane copolymer Tegostab? B-8870 Polyether polydimethylsiloxane copolymer Dabco? LK?-443 Non-silicone organic surfactant Nonoxynol-9 [00023] the hydroxyl number is ~88 L12-8 ethoxylated alcohol (dodecyl alcohol ethoxylate) [00024] Tegostab? B-8465 Polyether polydimethylsiloxane copolymer Surfonic N-95 ethylene oxide content of 65.5% & HLB value of 13.1

[0039] Catalysts

[0040] As illustrated in a non-exhaustive, non-exclusive, exemplary list below, there are a myriad of catalysts which are useful in effecting the reaction of a polyol with a diisocyanate to form a foam having varying characteristics. The ability to add widely varying amounts of catalysts and/or different catalyst combinations could easily be affected via either supplementing existing amounts of B-side catalyst(s) via the third stream or by essentially eliminating B-side catalyst(s) and making their addition via the third stream.

TABLE-US-00005 Trade name and/or Chemical name Chemical structure Dabco? K-15 (Potassium octoate/DEG (diethylene glycol)) [00025] Dabco? TMR-20 Proprietary K-carboxylate composition DABCO? T-120/Patcat 3014 (CH.sub.3(CH.sub.2).sub.3).sub.2SnS(CH.sub.2).sub.11CH.sub.3 (dibutyl tin dilauryl mercaptide) Polycat? 12 [00026] DMDEE (2,2-dimorpholinediethylether) [00027]

[0041] Other

[0042] Water can be both beneficial and deleterious to catalyst foams, depending on the blowing agent used or the end-use application. The ability to add widely varying amounts of water could easily be affected via either supplementing existing amounts of B-side water via the third stream or by essentially eliminating B-side water and making its addition via the third stream of a spray gun.

[0043] Glycerin has been found to be beneficial to the reactant mix and is one specific example of a triol with scavenging capabilities, the invention is not limited to such. In fact, lower molecular weight polyols, e.g., a triol or specifically a polyol (including diols) having a functionality?2, preferably?2.2 are believed to be useful in this invention. Molecular weight ranges of the polyol(s) are anticipated to range between ?90 to ?1500 g/mol are believed to be applicable to this invention.

[0044] Blowing Agent(s)

[0045] As illustrated in a non-exhaustive, non-exclusive, exemplary list below, there are a myriad of blowing agents which are useful in effecting the reaction of a polyol with a diisocyanate to form a foam having varying characteristics. The ability to add widely varying amounts of blowing agents and/or different blowing agent combinations could easily be effected via either supplementing existing amounts of A-side and/or B-side blowing agent(s) via the third stream or by essentially eliminating blowing agent(s) and making their addition via the third stream.

[0046] In one aspect of the invention, blowing agents having up to four carbon atoms in their backbone and which are useful in this invention fall within the general formula (I) illustrated below:

[CV.sub.a].sub.m?A?[CX.sub.b].sub.n?B?[CY.sub.c].sub.o?D?[CZ.sub.d].sub.p

[0047] wherein [0048] C is a carbon atom; [0049] V, X, Y & Z are independently selected from the group consisting of H, F and CI; [0050] a & d are independently selected from the integral values ranging from 0 to 3 inclusive; [0051] b & c are independently selected from the integral values ranging from 0 to 2 inclusive; [0052] o, p & n are equal to 1; [0053] m is selected from the integral values ranging from 0 to 1 inclusive; [0054] A, B & D are covalent bonds sufficient to satisfy the available bonding sites of adjacent carbon atoms, if such carbon atoms are present; and

[0055] the blowing agent, including miscible blends and azeotropes thereof, having a boiling point between approximately ?5? C.-50? C., and an ozone depletion potential of essentially zero; and

[0056] in a preferred embodiment, the blowing agent is non-flammable, recognizing that co-blowing agents may be flammable, although in a more preferred embodiment, the co-blowing agent will be added in such an amount as to render the combination non-flammable either as a blend or as an azeotrope.

[0057] In another aspect of the invention, and listed more generically, the blowing agents having up to six carbon atoms in their backbone and which are useful in this invention fall within the general formula (II) illustrated below:

[CU.sub.e].sub.q?E?[CW.sub.f].sub.r?F?[CV.sub.a].sub.m?A?[CX.sub.b].sub.n?B?[CY.sub.c].sub.o?D?[CZ.sub.d].sub.p

[0058] wherein [0059] C is a carbon atom; [0060] U, W, V, X, Y and Z are independently selected from the group consisting of H, F and CI; [0061] d & e are independently selected from the integral values ranging from 0 to 3 inclusive; [0062] a, b, c & f are independently selected from the integral values ranging from 0 to 2 inclusive; [0063] o, p & n are equal to 1; [0064] m, q & r are independently selected from the integral values ranging from 0 to 1 inclusive; [0065] A, B, D, E and F are covalent bonds sufficient to satisfy the available bonding sites of adjacent carbon atoms, if such carbon atoms are present;

[0066] the blowing agent having a boiling point between approximately ?5? C.-50? C., and an ozone depletion potential of not greater than 0.05; and

[0067] in a preferred embodiment, the blowing agent is non-flammable, recognizing that co-blowing agents may be flammable, although in a more preferred embodiment, the co-blowing agent will be added in such an amount as to render the combination non-flammable either as a blend or as an azeotrope.

[0068] As illustrated in a non-exhaustive, non-exclusive, exemplary list below, there are a myriad of blowing agents which are useful in effecting the reaction of a polyol with a diisocyanate to form a foam having varying characteristics. The ability to add widely varying amounts of blowing agents and/or different blowing agent combinations could easily be effected via either supplementing existing amounts of A-side and/or B-side blowing agent(s) via the third stream or by essentially eliminating blowing agent(s) and making their addition via the third stream.

TABLE-US-00006 HFO 1234ze(E) (1,3,3,3-tetrafluoropropene) [00028] HFO-1233zd(E) sold commercially under the name (Solstice LBA) (E) 1-chloro-3,3,3-trifuloro-propene (trans isomer) [00029] Opteon 1150 (E) (trans-1,1,1,4,4,4 hexafluoro-2-butene) [00030] Opteon 1100 (Z) (cis-1,1,1,4,4,4-hexafluoro-2-butene) [00031]

[0069] As used in this application, a non-limiting definition for the term blowing agent which includes miscible mixtures and azeotropes of blowing agents, means a propellant or solvent which are useful and provide efficacy to various applications in the form of performance, pressure performance, or solubility, without deleterious effect due to molar gas volume, flammability migration, or GWP reduction, yet which have a vapor pressure within defined limits as defined herein. Exemplary and non-limiting blowing agents include HFO-1233zd(E), HFO-1336mzz or sold under the trade name Opteon? 1100 (Chemours), namely cis-1,1,1,4,4,4 hexafluoro-2-butene or Opteon? 1150 (Chemours), namely trans-1,1,1,4,4,4 hexafluoro-2-butene

[0070] And while the above identified blowing agents are preferred from an ozone depletion potential (ODP) perspective as well as a global warming potential (GWP) perspective, the third stream within the spray gun offers the ability to use a myriad of blowing agents, alone or in combination with others, the combination in one aspect including all non-flammable blowing agents, while in another aspect including a combination of non-flammable and flammable blowing agents. A non-limiting list of other blowing agents includes, but is not limited to air, C.sub.1 to C.sub.6 hydrocarbons, C.sub.1 to C.sub.8 alcohols, ethers, diethers, aldehydes, ketones, hydrofluoroethers, C.sub.1 to C.sub.4 chlorocarbons, methyl formate, water, carbon dioxide, C.sub.3 to C.sub.4 hydrofluoroolefins, and C.sub.3 to C.sub.4 hydrochlorofluoroolefins. Examples of these non-exclusively include one or more of difluoromethane, trans-1,2-dichloroethylene, difluoroethane, 1,1,1,2,2-pentafluoroethane, 1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,1-trifluoroethane, 1,1-difluoroethane, fluoroethane, hexafluoropropane isomers, including HFC-236fa, pentafluoropropane isomers of HFC-245fa, heptafluoropropane isomers, including HFC-227ea, hexafluorobutane isomers, and pentafluorobutane isomers including HFC-365mfc, tetrafluoropropane isomers, and trifluoropropene isomers (HFO-1243). Specifically included are all molecules and isomers of HFO-1234, including 1,1,1,2-tetrafluoropropene (HFO-1234yf), trans-1-chloro-3,3,3-trifluoropropene (HFO-1233zd(E)) sold under the trade name Solstice LBP by Honeywell and cis- and trans-1,2,3,3-tetrafluoropropene (HFO-1234ye), HFC-1233zd, and HFC-1225ye. The blowing agents may be used in combination with at least one co-blowing agent which non-exclusively include: hydrocarbons, methyl formate, halogen containing compounds, especially fluorine containing compounds and chlorine containing compounds such as halocarbons, fluorocarbons, chlorocarbons, fluorochlorocarbons, halogenated hydrocarbons such as hydrofluorocarbons, hydrochlorocarbons, hydrofluorochlorocarbons, hydrofluoroolefins, hydrochlorofluoroolefins, CO.sub.2, CO.sub.2 generating materials such as water, and organic acids that produce CO.sub.2 such as formic acid. Examples non-exclusively include low-boiling, aliphatic hydrocarbons such as ethane, propane(s), i.e. normal pentane, isopropane, isopentane and cyclopentane; butanes(s), i.e. normal butane and isobutane; ethers and halogenated ethers; trans 1,2-dichloroethylene, pentafluorobutane; pentafluoropropane; hexafluoropropane; and heptafluoropropane; 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124); and 1,1-dichloro-1-fluoroethane (HCFC-141b) as well as 1,1,2,2-tetrafluoroethane (HFC-134); 1,1,1,2-tetrafluoroethane (HFC-134a); 1-chloro 1,1-difluoroethane (HCFC-142b); 1,1,1,3,3-pentafluorobutane (HFC-365mfc); 1,1,1,2,3,3,3-heptafluoropropane (HCF-227ea); trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12); 1,1,1,3,3,3-hexafluoropropane (HFC-236fa); 1,1,1,2,3,3-hexafluoropropane (HFC-236ea); difluoromethane (HFC-32); difluoroethane (HFC-152a); trifluoropropenes, pentafluoropropenes, chlorotrifluoropropenes, tetrafluoropropenes including 1,1,1,2-tetrafluoropropene (HFO-1234yf), 1,1,1,2,3-pentafluoropropene (HFO-1225ye), and 1-chloro-3,3,3-trifluoropropene (HCFC-1233zd). Combinations of any of the aforementioned are useful including blends and azeotropes thereof. The relative amount of any of the above noted additional co-blowing agents, as well as any additional components included in present compositions, can vary widely within the general broad scope of the present invention according to the particular application for the composition, and all such relative amounts are considered to be within the scope hereof.

[0071] As used herein, a non-limiting definition for the term co-blowing agent which includes mixtures or miscible blends and/or azeotropes of blowing agents, means a one or more co-blowing agents, co-propellants, or co-solvents which are useful and provide efficacy to various applications in the form of performance, pressure performance, or solubility, without deleterious effect due to molar gas volume, flammability mitigation, or GWP reduction. These co-agents include but are not limited to those described previously.

[0072] Without being held to any theory or mode of operation, glycerin imparts greater reactivity stability over time. If glycerin is taken out of the reactants, reactivity stability suffers.

[0073] In the ensuing tables, a catalytic decay ratio (CDR)?2.5, more preferably?2 was deemed to pass. For density drift, for a pass, the density should not exceed past +/?25% of the initial value. And for insulation properties, (R) values, the R-value must not be below 1.0 of initial value and the closed cell content should be above 80%.

[0074] All experiments in this application employed the following recognizing that the exact percentages can vary and still produce acceptable polyurethane foam. Most cans were pressurized to between 130-250 psi (typically using an inert gas, e.g., nitrogen), although several formulations were tested in II-12 cans, which limit pressures from about 70 psig to 130 psig.

TABLE-US-00007 LBA Expts. GBA Expts. All Cans* A-side B-side A-side B-side PMDI 93% 94% Respective blend 86% 86-89% 1234ze 7% 14% 6% 11-14% 100% 100% 100% .sup.100% Optimal A/B Ratio~1:1

TABLE-US-00008 TABLE 1 #1 #2 #3 #4 #5 % % % % % #6 #7 #8 #9 Polyol(s) Isoexter 3061-US 27.00 PS-1752 38.00 37.00 Poly-G 30-168 43.00 41.00 Poly-G 37-600 (4.98% 20.00 20.00 23.00 27.00 26.00 50.00 60.00 50.00 60.00 N) Poly-G 20-112 Plurocol 2010 15.00 Poly-G 30-42 6.00 17.60 8.90 Multrinol 8114 (~4.93% N) Poly-Q 40-800 (~10.07% N) Plasticizer TCPP 27.15 27.15 27.15 27.15 27.15 27.15 27.15 27.15 27.15 Surfactant(s) Tegostab B-8870 4.00 4.00 4.00 Dabco DC-198 3.00 3.00 Surfonic N-95 3.50 3.50 3.50 3.50 Tegostab B-8465 2.50 2.50 2.50 2.50 Pluronic L-31 Surfynol 485 Tegostab B-8499 Catalyst(s) Dabco? T-120/PC3014 0.05 0.05 0.05 0.05 0.05 0.05 0.15 0.15 0.15 Dabco? TMR-20 Polycat 12 0.80 0.80 0.80 0.80 0.80 0.80 0.80 0.80 0.80 Other Additive(s) Water 2.00 2.00 2.00 2.00 2.00 1.30 1.30 Glycerin 3.00 3.00 1.00 1.00 1.00 Polyol % by type Polyester Polyol % 0.00 0.00 27.00 38.00 37.00 0.00 0.00 0.00 0.00 Polyether Polyol % 63.00 61.00 38.00 27.00 26.00 50.00 60.00 50.00 60.00 Theoretical Nitrogen % 1.054 1.054 1.203 1.403 1.350 2.549 3.047 2.549 3.047 Expt Nitrogen % 1.048 (ASTM D6979) Physical Properties CDR (6 months) 1.26 1.31 1.45 1.40 1.24 1.24 1.00 1.82 1.29 CDR (12 months) 1.53 1.35 1.56 1.50 1.00 1.10 1.00 1.85 1.32 #10 #11 #12 #13 #14 #15 #16 #17 #18 Polyol(s) Isoexter 3061-US PS-1752 Poly-G 30-168 41.00 51.00 43.00 53.00 43.00 44.00 Poly-G 37-600 (4.98% N) 13.50 81.00 50.00 Poly-G 20-112 Plurocol 2010 Poly-G 30-42 Multrinol 8114 20.00 20.00 40.00 22.00 22.00 (~4.93% N) Poly-Q 40-800 10.00 10.00 25.00 (~10.07% N) Plasticizer TCPP 27.15 27.15 27.15 27.15 35.00 15.80 21.80 24.30 24.40 Paroil 45/CPAR P-45 5.30 Surfactant(s) Tegostab B-8870 4.00 4.00 2.00 3.00 3.00 4.00 4.00 Dabco DC-198 Surfonic N-95 3.50 3.50 Tegostab B-8465 2.50 2.50 1.00 Pluronic L-31 1.00 Surfynol 485 Tegostab B-8499 Catalyst(s) Dabco? T-120/PC3014 0.05 0.05 0.05 0.05 0.20 0.20 Dabco? TMR-20 1.00 1.70 1.00 Polycat 12 0.80 0.80 0.80 0.80 0.80 0.60 0.40 Other Additive(s) Water 2.00 2.00 2.00 2.00 1.40 1.40 1.20 Glycerin 3.00 3.00 3.00 3.00 3.00 3.00 Polyol % by type Polyester Polyol % 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Polyether Polyol % 61.00 61.00 63.00 63.00 53.50 81.00 75.00 65.00 66.00 Theoretical Nitrogen % 1.026 1.065 1.026 1.065 2.666 4.034 5.009 1.065 1.065 Expt. Nitrogen % 1.043 1.074 2.700 4.978 1.128 1.128 (ASTM D6979) Physical Properties (measured at 1.048 per ASTM D6979 CDR (6 months) 1.06 2.10 1.43 2.18 1.45 1.39 1.60 1.70 0.90 CDR (12 months) 1.00 1.80 1.50 2.51 1.73 1.39 1.90 1.86 1.10 #19.sup.(1) Polyol(s) Isoexter 3061-US PS-1752 Poly-G 30-168 Poly-G 37-600 (4.98% N) 40.00 Poly-G 20-112 Plurocol 2010 Poly-G 30-42 Multrinol 8114 (~4.93% N) Poly-Q 40-800 (~10.07% N) Stepanpol 3524 27.70 Plasticizer TCPP 25.00 Paroil 45/CPAR P-45 Surfactant(s) Tegostab B-8870 1.50 Dabco DC-198 Surfonic N-95 Tegostab B-8465 Pluronic L-31 Surfynol 485 2.40 Tegostab B-8499 1.50 Catalyst(s) Dabco? T-120/PC3014 Dabco? TMR-20 Polycat 12 Dabco K-15 (KC) 1.30 Dabco TMR-31 0.50 DMDEE 0.10 Other Additive(s) Water Glycerin Polyol % by type Polyester Polyol % 27.70 Polyether Polyol % 40.00 Theoretical Nitrogen % >1.008 Experimental Nitrogen % 2.073 (ASTM D6979) Physical Properties CDR (6 months) 1.21 CDR (12 months) 1.18 .sup.(1)Used liquid blowing agent LBA - HFO-1233zd (1-chloro-3,3,3-trifluoropropene)

[0075] As illustrated in the table, minor changes impact properties which is indicative of formulation sensitivity (lack of robustness). Amine-containing polyols, i.e., systems with ether-based polyols and aminopolyols pass shelf life stability.

[0076] It is possible to synthesize a polyurethane foam having over a 3% theoretical nitrogen loading by liquid chemical weight analysis and still pass shelf life analysis. Nitrogen steric hindrance appears to be important and reactivity stability is highly dependent on the choice of amino polyol. Without being bound to any one theory or mode of operation, it appears that the nitrogen needs to be shielded from HFO attack. As illustrated by the figure, the type of amine-containing polyol has a strong influence over CDR (catalytic decay ratio), not nitrogen content alone. All blends have theoretical nitrogen content between 1.02 wt. % and 1.07 wt. %. The figure shows that high content amino polyols (e.g., Poly-Q 40-800) with about 10.07 wt. % nitrogen did not synthesize a polyurethane foam with a higher nitrogen content than for example Multrinol 8114 with about 4.84 wt. % nitrogen. However, the less shielded nitrogen in Poly-Q 40-800 clearly produced consistently poorer results as evidenced by the CDR ratios greater than 2.0.

TABLE-US-00009 TABLE #2 Physical Properties Characterization Initial 3 months 6 months 9 months 12 months Expt. #1 Gel (sec) 57 61 72 73 87 Tack (sec) 115 138 155 135 162 CDR 1.00 1.07 1.26 1.28 1.53 A/B 1.17 1.06 1.06 1.04 1.03 Density pcf 1.97 2.13 1.92 2.00 1.95 R 5.98 6.11 5.64 5.92 5.64 % CCC 97.27 92.53 94.12 93.63 95.08 II comp. (psi) 18.23 12.46 13.39 12.40 11.98 Expt. #2 Gel (sec) 52 71 68 73 70 Tack (sec) 95 138 145 135 100 CDR 1.00 1.37 1.31 1.26 1.35 A/B 1.09 1.02 1.09 1.01 1.02 Density pcf 1.94 2.06 1.96 1.95 2.02 R 6.04 5.91 5.62 3.98 3.72 % CCC 98.03 96.21 94.13 13.53 16.28 II comp. (psi) 16.45 13.13 16.38 19.35 19.52 Expt. #3 Gel (sec) 51 57 74 70 80 Tack (sec) 95 106 166 130 140 CDR 1.00 1.12 1.45 1.37 1.57 A/B 1.19 1.19 1.09 1.12 1.13 Density pcf 2.10 2.19 2.14 2.13 2.13 R 5.91 4.82 4.33 4.26 4.20 % CCC 92.72 93.79 38.96 5.40 8.36 II comp. (psi) 16.10 17.79 12.76 12.36 Expt. #4 Gel (sec) 50 69 70 75 Tack (sec) 95 106 166 140 CDR 1.00 1.38 1.40 1.50 A/B 1.18 1.15 1.10 0.98 Density pcf 2.18 2.31 2.33 R 6.30 6.33 6.02 % CCC 91.52 91.91 84.87 II comp. (psi) 18.71 15.64 17.16 Expt. #5 Gel (sec) 55 58 68 65 Tack (sec) 80 140 110 130 CDR 1.00 1.05 1.24 1.18 A/B 1.11 0.94 0.96 0.64 Density pcf 2.08 1.95 1.91 R 5.95 6.14 3.99 % CCC 91.52 91.54 46.98 II comp. (psi) 14.03 11.05 12.80 Expt. #6 Gel (sec) 50 57 62 55 Tack (sec) 90 80 100 90 CDR 1.00 1.14 1.24 1.10 A/B 1.05 1.06 1.04 0.98 Density pcf 2.09 2.01 2.21 R 5.41 3.94 3.46 % CCC 88.73 44.40 3.45 II comp. (psi) 12.26 15.16 16.35 Expt. #7 Gel (sec) 55 45 55 65 55 Tack (sec) 80 70 80 85 90 CDR 1.00 0.82 1.00 1.18 1.00 A/B 1.11 1.15 1.09 0.80 1.07 Density pcf 3.17 2.82 3.14 3.32 2.86 R 6.03 5.33 3.71 5.16 4.56 % CCC 94.66 92.87 5.07 83.47 II comp. (psi) 32.17 30.11 36.42 19.55 Expt. #8 Gel (sec) 34 50 62 57 63 Tack (sec) 46 70 90 75 90 CDR 1.00 1.47 1.82 1.68 1.85 A/B 1.09 0.85 0.63 1.16 1.06 Density pcf 2.16 2.53 2.25 2.29 R 4.58 4.22 4.05 3.99 % CCC 94.80 2.82 5.78 3.46 II comp. (psi) 12.31 12.68 18.13 19.28 Expt. #9 Gel (sec) 31 33 40 35 41 Tack (sec) 40 50 65 55 65 CDR 1.00 1.06 1.29 1.13 1.32 A/B 1.21 1.09 0.83 0.89 1.04 Density pcf 3.28 3.36 3.25 3.17 3.33 R 5.67 4.81 4.16 4.18 5.51 % CCC 94.73 82.37 32.56 67.09 72.27 II comp. (psi) 40.68 38.69 24.24 31.20 34.00 Expt. #10 Gel (sec) 75 78 80 85 75 Tack (sec) 180 165 210 170 150 CDR 1.00 1.04 1.07 1.13 1.00 A/B 1.07 1.11 1.12 1.07 0.93 Density pcf 2.04 1.99 2.03 2.04 1.93 R 6.01 5.70 5.68 5.47 5.56 % CCC 88.79 94.22 92.23 95.36 90.96 II comp. (psi) 14.66 14.14 14.18 13.27 8.12 Expt. #11 Gel (sec) 50 90 105 90 90 Tack (sec) 105 255 300 250 285 CDR 1.00 1.80 2.10 1.80 1.80 A/B 1.06 0.99 1.04 1.02 1.05 Density pcf 2.08 2.02 2.22 2.43 2.06 R 6.15 5.19 3.86 3.69 3.40 % CCC 89.13 93.08 32.77 11.71 14.23 II comp. (psi) 11.89 12.32 20.95 18.08 16.93 Expt. #12 Gel (sec) 70 * 100 90 105 Tack (sec) 200 * 225 270 225 CDR 1.00 * 1.43 1.29 1.50 A/B 1.23 * 1.36 1.33 1.14 Density pcf 2.08 * 1.93 2.44 2.20 R 5.68 * 5.53 6.17 5.79 % CCC 91.61 * 94.42 92.41 90.53 II comp. (psi) 17.17 * 15.32 16.20 15.32 Expt. #13 Gel (sec) 55 130 120 140 138 Tack (sec) 130 335 360 540 495 CDR 1.00 2.36 2.8 2.55 2.51 A/B 1.22 1.34 1.24 1.15 1.25 Density pcf 2.19 2.30 2.29 2.36 2.30 R 5.66 5.25 5.47 5.66 5.44 % CCC 91.10 89.36 92.16 91.02 92.04 II comp. (psi) 14.67 22.40 18.34 15.66 18.08 Expt. #14 Gel (sec) 110 120 160 190 Tack (sec) 285 300 540 525 CDR 1.00 1.25 1.45 1.73 A/B 1.25 1.18 1.18 1.04 Density pcf 2.06 2.07 2.42 2.31 R 5.86 5.69 5.44 4.69 % CCC 95.45 93.63 94.10 86.11 II comp. (psi) 20.57 16.33 28.51 26.44 Expt. #15 Gel (sec) 28 35 39 37 39 Tack (sec) 35 52 53 51 52 CDR 1.00 1.25 1.39 1.32 1.39 A/B 1.06 1.14 0.76 1.11 0.86 Density pcf 2.91 2.94 3.54 3.12 3.19 R 6.63 6.60 5.39 6.34 5.05 % CCC 93.41 95.66 87.86 93.54 74.40 II comp. (psi) 34.68 33.82 22.62 36.01 29.76 Expt. #16 Gel (sec) 20 30 32 37 38 Tack (sec) 26 52 52 60 55 CDR 1.00 1.50 1.60 1.85 1.90 A/B 1.20 1.40 1.37 1.42 1.40 Density pcf 2.96 3.22 3.15 3.00 3.09 R 6.64 3.66 3.65 5.06 6.05 % CCC 94.57 17.80 49.54 96.50 II comp. (psi) 38.96 30.22 29.13 37.45 46.12 Expt. #17 Gel (sec) 70 93 120 120 130 Tack (sec) 130 160 197 240 240 CDR 1.00 1.33 1.71 1.71 1.86 A/B 1.24 1.10 1.10 0.98 1.00 Density pcf 1.88 1.95 1.99 2.06 2.02 R 5.54 5.87 5.68 5.56 4.02 % CCC 97.18 97.51 80.65 93.79 15.52 II comp. (psi) 17.25 17.77 19.70 16.40 15.66 Expt. #18 Gel (sec) 150 153 135 165 165 Tack (sec) 290 285 285 390 320 CDR 1.00 1.02 0.90 1.10 1.10 A/B 1.19 1.12 0.92 0.99 0.97 Density pcf 2.28 2.30 2.16 2.28 2.32 R 5.67 5.88 5.14 5.31 5.44 % CCC 96.48 99.32 97.35 97.96 98.52 II comp. (psi) 20.47 19.14 16.87 18.17 18.05 Expt. #19 Gel (sec) 76 82 92 98 90 Tack (sec) 116 107 152 137 158 CDR 1.00 1.08 1.21 1.29 1.18 A/B 1.15 1.20 1.27 1.22 1.17 Density pcf 3.00 3.00 3.07 3.04 2.98 R 5.82 6.74 7.40 7.25 6.15 % CCC 97.00 95.27 97.44 91.69 91.53 II comp. (psi) 51.19 43.14 38.70 47.50 39.38 * = data not collected

[0077] As illustrated in the data above, Formula #1 exceeds 1% nitrogen by weight of liquid chemical and is a successful formulation pursuant to the identified success criteria. In Formula #2, much like Formula #1 but with a different surfactant package, this formulation appears to have a better CDR, but is not as robust for insulation stability. Formula #3 adds some polyester polyol in order to expand capabilities, and demonstrates that ester polyols are usable in high nitrogen compositions. In Formula #4, despite using a known stable polyester polyol (PS-1752), both formulas inexplicably collapse in aging regardless of two previous surfactant packages and failed.

[0078] The theoretical nitrogen content to was increased to ?3.0% in Formula #7 and the product passes even with no added water as water is known to cause issues with HFO's. Formulas #8 and #9 both pass with the 8870 surfactant package, although CDR is worse in both cases. It is hypothesized that the N95/B8465 surfactant package helps with CDR, while the 8870 helps with insulation stability.

[0079] In formulas #10 and #12, Multranol 8114 seems to impart better stability than 37-600 with similar theoretical nitrogen loadings thereby indicating some sort of steric hindrance phenomenon. Similar surfactant trends are noticed here as with previous studies. In formulas #11 and #13, Poly-Q 40-800 has much worse performance than the previous amino polyols despite similar nitrogen loadings in the liquid blends. Similar surfactant trends are noticed here as with previous studies.

[0080] For Formula #14, Multranol 8114 and Poly-G 37-600 were used noting that the formulation uses TMR-20, not T-120. Formula #15 increased the theoretical nitrogen threshold to ?4%. The catalyst PC-12 was removed, the amount of TCPP was reduced while the amount of T-120 was increased to demonstrate faster reactivity. Formula #16 increased theoretical nitrogen threshold to ?4% and the product passed all metrics. It is noted that this formulation passes insulation at initial, then bottoms out closed cell from 3-6 months, 9 months shows improvement, then 12 months is back to>90% closed cell content.

[0081] Formulas #17 and #18 used the catalysts TMR-20+PC-12 in order to change reaction mechanics with Formula #18 being a slower version of Formula #17.

[0082] What has been illustrated is that systems with ether-based polyols and/or ester based polyols and amino polyols pass shelf life stability. Most formulas presented are at 1-3% theoretical nitrogen loading although it should be noted that it is possible to get a formulation with over 5% theoretical nitrogen by liquid chemical weight to pass shelf life (Formula #16) which has a CDR of 1.60 at 6 months and 1.90 at 12 months.

[0083] Contrary to the teachings of the Prior Art, which has taught that the more nitrogen in a blend, the worse CDR becomes as seen in FIG. 1, a plot of CDR vs theoretical nitrogen yield a correlation of almost zero.

[0084] By removing typical aging culprits (water) and limiting TCPP, it is possible to construct a formula that has 4% and 5% nitrogen loadings (Formula #15 and #16). The issue with these formulations was viscosity concerns. In this application, it is taught that reactivity stability is highly dependent on the choice of amino polyol, but the nitrogen needs to be shielded.

[0085] In this application, it is shown that systems with sterically-hindered amines (PC-12) and metal-based catalysts (K and Sn), or simply metal-based catalysts can be employed and that unlike the teachings of the Prior Art, are not limited by the requirement of amine catalysts. It is possible to formulate compositions that react fast (?0:30 sec to gel) and formulas that react slow (?2:00 minutes to gel).

[0086] To a lesser extent, surfactants play a role in the reactivity shelf life stability of these systems. The tandem of the surfactants N95 and B-8465 are more shelf life stable in reactivity than B8870 (though B8870 seems to have better insulation stability).

[0087] Noticeably, Formula #13 has a CDR greater than 2 from 3 months onward yet maintains minimal density drift and does not appear to decrease in insulation and is unique in that it is not stable in reactivity, but is stable for physical properties.

[0088] It is noted that when using HFO propellants, not only gaseous HFO propellants are able to be successfully employed in the various compositions but also liquid HFO propellants (as illustrated with Formula #19) which uses HFO 1233zd as the HFO propellant.

[0089] In one aspect, the invention provides a polyol premix composition which comprises a combination of a blowing agent, a polyol, a silicone surfactant, and a sterically hindered amine catalyst; wherein the blowing agent comprises a hydrohaloolefin, and optionally a hydrocarbon, fluorocarbon, chlorocarbon, fluorochlorocarbon, halogenated hydrocarbon, CO.sub.2 generating material, or combinations thereof; wherein the sterically hindered amine catalyst has the formula R.sub.1R.sub.2N-[A-NR.sub.3].sub.nR.sub.4 wherein each of R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is independently H, a C.sub.1-8 alkyl group, a C.sub.1-8 alkenyl group, a C.sub.1-8 alcohol group, or a C.sub.1-8 ether group, or R.sub.1 and R.sub.2 together form a C.sub.5-7 cyclic alkyl group, a C.sub.5-7 cyclic alkenyl group, a C.sub.5-7 heterocyclic alkyl group, or a C.sub.5-7 heterocyclic alkenyl group; A is a C.sub.1-5 alkyl group, a C.sub.1-5 alkenyl group, or an ether; n is 0, 1, 2, or 3; with the proviso that the sterically hindered amine catalyst has a sum of Charton's steric parameters of about 1.65 or greater.

[0090] Charton's steric parameters for a group X are determined by: comparing the rates of acid catalyzed hydrolysis of substituted esters XCH.sub.2C(O)OR with the rate of the hydrolysis of the corresponding unsubstituted ester. The differences correlate in a linear fashion with the Van der Waals radii of X (see R.W. Taft in Steric effects in organic chemistry M.S. Newman, ed., Wiley, New York, NY (1956) p. 556 and M. Charton, J. Am. Chem. Soc., 97 (1975) p. 1552, which are incorporated herein by reference. A list of the values v can be found in M. Charton, J. Organic Chemistry, 41(12) (1976) p. 2217-2220, which is incorporated herein by reference.

[0091] In another aspect of the invention, the sterically hindered amine component contains at least one sterically hindered tertiary amine catalysts and at least one sterically hindered secondary amine catalyst. The polyol premix composition may optionally further comprise a non-amine catalyst. Suitable non-amine catalysts may comprise an organometallic compound containing bismuth, lead, tin, titanium, antimony, uranium, cadmium, cobalt, thorium, aluminum, mercury, zinc, nickel, cerium, molybdenum, vanadium, copper, manganese, zirconium, sodium, potassium, or combinations thereof. These non-exclusively include bismuth nitrate, lead 2-ethylhexoate, lead benzoate, ferric chloride, antimony trichloride, antimony glycolate, stannous salts of carboxylic acids, zinc salts of carboxylic acids, dialkyl tin salts of carboxylic acids, potassium acetate, potassium octoate, potassium 2-ethylhexoate, glycine salts, quaternary ammonium carboxylates, alkali metal carboxylic acid salts, and N-(2-hydroxy-5-nonylphenol) methyl-N-methylglycinate, tin (II) 2-ethyl hexanoate, dibutyltin dilaurate, or combinations thereof. When the optional non-amine catalyst is used, it is usually present in the polyol premix composition in an amount of from about 0.01 wt. % to about 2.5 wt. %, preferably from about 0.05 wt. % to about 2.25 wt. %, and more preferably from about 0.10 wt. % to about 2.00 wt. %. by weight of the polyol premix composition. While these are usual amounts, the quantity amount of metallic catalyst can vary widely, and the appropriate amount can be easily determined by those skilled in the art.

[0092] The quantification of steric effects has been a source of some controversy and several parameters have been developed, both experimentally and computationally, and applied with varying degrees of success in biological and chemical settings. Assessing the origin and derivation of some of the most widely known parameters yields insight into how and when they may be appropriately used. Winstein-Holness values (A-values) arise from the conformational study of mono-substituted cyclohexane rings. A-values are based on the observed equilibrium of conformers in mono-substituted cyclohexane rings, where perturbation of this equilibrium is presumably due to 1,3-diaxial steric repulsion. Interference values are another example of an experimentally determined steric parameter and are based on the heat-induced half-life of racemization in 2,2-substituted biphenyl systems. The steric interaction between the substituent R and the opposing aryl ring is presumed to be the key factor responsible for the different energies required for racemization of the atrop-isomers. Molar refractivity, a steric parameter found in many early QSAR studies is defined by the Lorentz-Lorenz equation and has proven to be an adequate descriptor of total steric volume but disregards molecular shape. Another steric parameter that has had a wide impact on the organometallic community is the Tolman cone angle. Tolman and others have measured projected cone angle of phosphine substituents from a hypothetical metal center. However, the scope of this parameterization may be limited to phosphite ligands. A widely used steric parameter in QSAR studies and other branches of chemistry is the Taft parameter. Taft developed these parameters in his efforts to delineate steric effects from electronic effects in aliphatic ester hydrolysis, by means analogous to those used to derive Hammett's electronic parameters. Taft hypothesized that, under acid-catalyzed conditions, the preservation of charge through the rate-determining step would diminish any inductive or resonance electronic contributions from the R substituents. More recently, Charton found a correlation between Taft's experimentally measured rates and the calculated minimum van der Waals radii of each symmetrical substituent.

[0093] A slightly different approach, but building on the Charton work, is that of Kaid Harper, Elizabeth Bess and Metthew Sigman in their paper published in Nature Chemistry Published online 18 Mar. 2012 and titled Multidimensional steric parameters in the analysis of asymmetric catalytic reactions pages 366-374. Yet another variant employs Winstein-Holness parameters (A-value) as a metric for steric hindrance. The Tolman cone angles are yet another approach as well as the Taft steric effects.

[0094] In the following further embodiments are disclosed:

[0095] In a first embodiment, a low-pressure two-component polyurethane foam composition is described in which A-side and B-side reactants comprise: [0096] at least one A-side diisocyanate and at least one HFO propellant; [0097] at least one B-side polyol, wherein the at least one B-side polyol comprises [0098] at least one aminopolyol, [0099] at least one B-side plasticizer, [0100] at least one surfactant, [0101] at least one catalyst, [0102] wherein the at least catalyst is a metal-based catalyst; and [0103] at least one HFO propellant; [0104] wherein a theoretical nitrogen content of the polyurethane foam composition is greater than 1.0 wt. %; and [0105] a catalytic decay ratio of the polyurethane foam being approximately equal to or less than 2.5.

[0106] In a second embodiment of the first embodiment, the at least one catalyst is at least two catalysts, and further wherein at least one of the at least two catalysts is a nitrogen-containing catalytic compound has at least one 6-membered ring groups attached to the nitrogen.

[0107] In a third embodiment of the first embodiment, the at least one nitrogen-containing catalytic compound has at least two 6-membered ring groups attached to the nitrogen.

[0108] In a fourth embodiment of the third embodiment, the at least one nitrogen-containing catalytic compound is n-methyldicyclohexylamine; and the at least one metal-containing catalytic compound is di-N-butylbis(dodecylthio)tin.

[0109] In a fifth embodiment of the first embodiment, the at least one amino polyol contains less than or equal to approximately 8 wt. % nitrogen.

[0110] In a sixth embodiment of the fifth embodiment, the at least one amino polyol contains less than or equal to approximately 7 wt. % nitrogen.

[0111] In a seventh embodiment of the sixth embodiment, the at least one amino polyol contains less than or equal to approximately 6 wt. % nitrogen.

[0112] In an eighth embodiment of seventh embodiment, the at least one amino polyol contains less than or equal to approximately 5 wt. % nitrogen.

[0113] In a ninth embodiment of the eighth embodiment, the at least one amino polyol contains less than or equal to approximately 4 wt. % nitrogen.

[0114] In a tenth embodiment of the first embodiment, the B-side further comprises: less than approximately 2.5 wt. % of added water; and less than approximately 5 wt. % of added glycerin.

[0115] In an eleventh embodiment of the first embodiment, the at least one amino polyol is selected from the group consisting of

##STR00032## [0116] wherein n ranges from 1 to 50

##STR00033## [0117] wherein 1<r+s+t+u+v+w+x+y+z<8.5; and further wherein [0118] r, s, t, u, v, w, x, y and z independently range from 0 to 10 inclusive; and

##STR00034## [0119] wherein n and k independently range from 1 to 25 inclusive.

[0120] In a twelfth embodiment of the eleventh embodiment, the at least one amino polyol is selected from the group consisting of

##STR00035## [0121] wherein n ranges from 1 to 50; and

##STR00036## [0122] wherein 1<r+s+t+u+v+w+x+y+z<8.5; and further wherein [0123] r, s, t, u, v, w, x, y and z independently range from 0 to 10 inclusive.

[0124] In a thirteenth embodiment of the eleventh embodiment, the at least one HFO propellant is a liquid HFO propellant at room temperature and pressure.

[0125] In a fourteenth embodiment of the eleventh embodiment, the at least one HFO propellant is a gaseous HFO propellant at room temperature and pressure.

[0126] The best mode for carrying out the invention has been described for purposes of illustrating the best mode known to the applicant at the time. The examples are illustrative only and not meant to limit the invention, as measured by the scope and merit of the claims. The invention has been described with reference to preferred and alternate embodiments. Obviously, modifications and alterations will occur to others upon the reading and understanding of the specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.