Abstract:
The present invention relates to a method of producing more uniformly distributed polyurethane form using blowing agents. More particularly, the present invention relates to a method of producing more uniformly distributed polyurethane foam for an application in which flow of liquid polyurethane foam prior to solidification is important to its performance using a hydrochlorofluoroolefin (HCFO), such as 1233zd.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a method of producing more uniformly distributed polyurethane foam using blowing agents. More particularly, the present invention relates to a method of producing more uniformly distributed polyurethane foam for an application in which flow of liquid polyurethane foam prior to solidification is important to its performance using the hydrochlorofluoroolefin (HCFO), such as 1233zd. 
       BACKGROUND OF THE INVENTION 
       [0002]    The Montreal Protocol for the protection of the ozone layer, signed in October 1987, mandated the phase out of the use of chlorofluorocarbons (CFCs). Materials more “friendly” to the ozone layer, such as hydrofluorocarbons (HFCs) eg HFC-134a replaced chlorofluorocarbons. The latter compounds have proven to be green house gases, causing global warming and were regulated by the Kyoto Protocol on Climate Change, signed in 1998. The emerging replacement materials, hydrofluoropropenes, were shown to be environmentally acceptable i.e. has zero ozone depletion potential (ODP) and acceptable low global warming potential (GWP). 
         [0003]    Currently used blowing agents for polyurethane forms include HFC-134a, HFC-245fa, HFC-365mfc that have relatively high global warming potential, and hydrocarbons such as pentane isomers which are flammable and have low energy efficiency. Therefore, new alternative blowing agents are being sought. Halogenated hydroolefinic materials such as hydrofluoropropenes and/or hydrochlorofluoropropenes have generated interest as replacements for HFCs. The inherent chemical instability of these materials in the lower atmosphere provides the low global warming potential and zero or near zero ozone depletion properties desired. 
         [0004]    Polyurethane foam processing conditions have a profound impact on the properties of foam. Density and thermal conductivity variations, compression strength etc are key parameters for the performance of the product. Arai et al Proceedings of the SPI-29 th  1995, p. 272 showed that foam density was affected by the pressure variation. Lefebvre et al Int. J. Numer Methods Fluids 1995, vol 20, p. 319 claimed that foam density was related to temperature of the exothermic reaction. The self-expanding fluid has significantly different flow behaviors from that of the Newtonian fluid with relatively constant density. Mitani et al Polym. Eng. Sci 2003 vol 43(9), p. 1603 used three-dimensional control volume finite element method to solve the Stokes equations under isothermal conditions. The density change was predicted by assuming the density was a function of time. US2008/0255262 disclosed a method of molding rigid polyurethane foams with enhanced thermal conductivity under reduced pressure. 
         [0005]    The object of the present invention is to provide a method of using compositions comprising hydrohaloolefins, in particular, 1-chloro-3,3,3-trifluoropropene-1 (HCFO-1233zd) for polyurethane foams that provides improved processability and foam properties that are related to thermal insulation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a graph of foam density versus distribution within the panel. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0007]    The present invention relates to a method of generating liquid polyurethane foams that have unexpectedly uniform density distribution along their flow pathway before they are solidified and enhance processing efficacy. According to one embodiment, the present invention comprises 1) mixing the blowing agent with other polyurethane premix components; 2) then using high pressure mixing and dispensing equipment of reaction injection molding. 
         [0008]    The foam processing efficacy was characterized by minimum fill weight in a mold, core density, average density and density distribution in the flow path, compression strength of foam, dimensional stability and thermal conductivity of foams. 
         [0009]    The present invention is directed towards using blowing agents with negligible (low or zero) ozone-depletion and low GWP based upon unsaturated halogenated hydroolefins in combination with polyol(s), silicone surfactant(s), amine catalyst(s), carbon dioxide generating agent(s), and other(s). 
         [0010]    The blowing agent comprises an unsaturated halogenated hydroolefin such as hydrofluoroolefins, hydrochlorofluoroolefins, and the like, in particular, predominately trans or E-1233zd, 1-chloro-3,3,3-trifluoropropene alone or in a combination including a hydrofluoroolefin (HFO), a hydrochlorofluoroolefin (HCFO) not including 1233zd, a hydrofluorocarbon (HFC), a hydrofluoroether (HFE), a hydrocarbon, an alcohol, an aldehyde, a ketone, an ether/diether or carbon dioxide. It was found that liquid polyurethane foam prior to solidification flowed more uniformly than others, which is surprising based on its boiling point and relative solubility in the polymer premix. The resulted polymer along the flow path showed much narrower density variation defined by overall minus core density, from 0.10 to 0.65 pound per cubic feet (pcf), preferably 0.15 to 0.50 pcf, and even more preferably from 0.20 to 0.45 pcf. 
         [0011]    The preferred hydrofluoroolefins (HFO) typically contain 3, 4, or 5 carbons, and include but are not limited to pentafluoropropenes, such as 1,2,3,3,3-pentafluoropropene (HFO 1225ye), tetrafluoropropene, such as 1,3,3,3-tetrafluoropropene (HFO 1234ze), 2,3,3,3-tetrafluoropropene (HFO 1234)yf), 1,2,3,3-tetrafluoropropene (HFO1234ye), trifluoropropene, such as 3,3,3-trifluoropropene (1243zf), all tetrafluorobutenes (HFO 1345), all pentafluorobutene isomers (HFO1354), all hexafluorobutene isomers (HFO1336), all heptafluorobutene isomers (HFO1327), all heptafluoropentene isomers (HFO1447), all octafluoropentene isomers (HFO1438), all nonafluoropentene isomers (HFO1429). HCFOs such as, 1-chloro-3,3,3-trifluoropropenen (HCFO-1233zd), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and HCFO1223. Preferred embodiments of the invention are blowing agent compositions of unsaturated halogenated hydroolefins with normal boiling points less than about 60° C. 
         [0012]    The blowing agents comprise a hydrohaloolefin such as hydrofluoroolefin, hydrochlorofluoroolefin, and the like, in particular, predominately trans or E-1233zd, 1-chloro-3,3,3-trifluoropropene alone or in combination with other blowing agents including (I) hydrofluorocarbons including but not limited to: difluoromethane (HFC32); 1,1,1,2,2-pentafluoroethane (HFC125); 1,1,1-trifluoroethane (HFC143a); 1,1,2,2-tetrafluorothane (HFC134); 1,1,1,2-tetrafluoroethane (HFC134a); 1,1-difluoroethane (HFC152a), 1,1,1,2,3,3,3-heptafluoropropane (HFC227ea); 1,1,1,3,3-pentafluopropane (HFC245fa); 1,1,1,3,3-pentafluobutane (HFC365mfc) and 1,1,1,2,2,3,4,5,5,5-decafluoropentane (HFC4310mee); (II) hydrofluoroolefins including but not limited to tetrafluoropropenes (HFO1234), trifluoropropenes (HFO1243), all tetrafluorobutenes (HFO 1345), all pentafluorobutene isomers (HFO1354), all hexafluorobutene isomers (HFO1336), all heptafluorobutene isomers (HFO1327), all heptafluoropentene isomers (HFO1447), all octafluoropentene isomers (HFO1438), all nonafluoropentene isomers (HFO1429); (III) hydrocarbons including but not limited to, pentane isomers, butane isomers; (IV) Hydrofluoroether (HFE) such as, C 4 F 9 OCH 3  (HFE-7100), C 4 F 9 OC 2 H 5  (HFE-7200), CF 3 CF 2 OCH 3  (HFE-245cb2), CF 3 CH 2 CHF 2  (HFE-245fa), CF 3 CH 2 OCF 3  (HFE-236fa), C 3 F 7 OCH 3  (HFE-7000), 2-trifluoromethyl-3-ethoxydodecofluorohexane (HFE 7500), 1,1,1,2,3-hexafluoro-4-(1,1,2,3,3,3-hexafluoropropoxy)-pentane (HFE-7600), 1,1,1,2,2,3,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane (HFE-7300), ethyl nonafluoroisobutyl ether/ethyl nonafluorobutyl ether (HFE 8200), CHF 2 OCHF 2 , CHF 2 —OCH 2 F, CH 2 F—OCH 2 F, CH 2 F—O—CH 3 , cyclo-CF 2 CH 2 CF 2 —O, cyclo-CF 2 CF 2 CH 2 —O, CHF 2 —CF 2 CHF2, CF 3 CF 2 —OCH 2 F, CHF 2 —O—CHFCF 3 , CHF 2 —OCF 2 CHF 2 , CH 2 F—O—CF 2 CHF 2 , CF 3 —O—CF 2 CH 3 , CHF 2 CHF—O—CHF 2 , CF 3 —O—CHFCH 2 F, CF 3 CHF—O—CH 2 F, CF 3 —O—CH 2 CHF 2 , CHF 2 —O—CH 2 CF 3 , CH 2 FCF 2 —O—CH 2 F, CHF2-O—CF 2 CH 3 , CHF 2 CF 2 —O—CH 3  (HFE254pc), CH 2 F—O—CHFCH 2 F, CHF 2 —CHF—O—CH 2 F, CF 3 —O—CHFCH 3 , CF 3 CHF—O—CH 3 , CHF 2 —O—CH 2 CHF 2 , CF 3 —O—CH 2 CH 2 F, CF 3 CH 2 —O—CH 2 F, CF 2 HCF 2 CF 2 —O—CH 3 , CF 3 CHFCF 2 —O—CH 3 , CHF 2 CF 2 CF 2 —O—CH 3 , CHF 2 CF 2 CH 2 —OCHF 2 , CF 3 CF 2 CH 2 —O—CH 3 , CHF 2 CF 2 —O—CH 2 CH 3 , (CF 3 ) 2 CF—O—CH 3 , (CF 3 ) 2 CH—O—CHF 2 , (CF 3 ) 2 CH—O—CH 3 , and mixture thereof; (V) C1 to C5 alcohols, C1 to C4 aldehydes, C1 to C4 ketones, C1 to C4 ethers and diethers and carbon dioxide; (VI) HCFOs such as, 1-chloro-3,3,3-trifluoropropenen (HCFO-1233zd), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and HCFO1223. 
         [0013]    The foamable compositions of the present invention generally include one or more components capable of forming foam having a generally cellular structure and a blowing agent, typically in a combination, in accordance with the present invention. In certain embodiments, the one or more components comprise a polyurethane composition capable of forming foam and/or foamable compositions. In such polyurethane foam embodiments, one or more of the present compositions are included as or part of a blowing agent in a foamable composition, or as a part of a two or more part foamable composition, which preferably includes one or more of the components capable of reacting and/or foaming under the proper conditions to form a foam or cellular structure. 
         [0014]    The invention also relates to foam, and preferably closed cell foam, prepared from a polymer foam formulation containing a blowing agent comprising the compositions of the present invention. In yet other embodiments, the invention provides foamable compositions comprising thermosetting foams, such as polyurethane and polyisocyanurate foams, preferably low-density foams, flexible or rigid, such as pour-in-place for insulation of refrigerated cavities, building and refrigerated panels, garage doors, entrance doors, insulated pipes, and water heaters; continuous lamination for metal and flexible faced panels; and spray for residential and commercial constructions and buildings. 
         [0015]    It will be appreciated by those skilled in the art that the order and manner in which the blowing agent combination of the present invention is formed and/or added to the foamable composition does not generally affect the operability of the present invention. For example, in the case of polyurethane foams, it is possible that the various components of the blowing agent combination, and even the components of the present composition, not be mixed in advance of introduction to the foaming equipment, or even that the components are not added to the same location in the foaming equipment. Thus, in certain embodiments it may be desired to introduce one or more components of the blowing agent combination in a blender with the expectation that the components will come together in the foaming equipment and/or operate more effectively in this manner. Nevertheless, in certain embodiments, two or more components of the blowing agent combination are combined in advance and introduced together into the foamable composition, either directly or as part of premix that is then further added to other parts of the foamable composition. 
         [0016]    In certain embodiments, b-side, polyol premixes may comprise polyols, silicon or non-silicon based surfactants, amine or non-amine based catalysts, flame retardants/suppressors, acid scavengers, radical scavengers, fillers, and other necessary stabilizers/inhibitors. Polyols may comprise Glycerin based polyether polyols such as Carpol GP-700, GP-725, GP-4000, GP-4520, and etc; Amine based polyether polyols such as Carpol TEAP-265 and EDAP-770, Jeffol AD-310, and etc; Sucrose based polyether polyol, such as Jeffol SD-360, SG-361, and SD-522, Voranol 490, Carpol SPA-357, and etc; Mannich base polyether polyol such as Jeffol R-425X and R-470X, and etc; Sorbitol based polyether polyol such as Jeffol S-490 and etc; Aromatic polyester polyols such as Terate 2541 and 3510, Stepanpol PS-2352, Terol TR-925, and etc. 
         [0017]    Catalysts may comprise N,N-dimethylethanolamine (DMEA), N,N-dimethylcyclohexylamine (DMCHA), Bis(N,N-dimethylaminoethyl)ether (BDMAFE), N,N,N′,N′,N″-pentamethyldiethylenetriamine (PDMAFE), 1,4-diazadicyclo[2,2,2]octane (DABCO), 2-(2-dimethylaminoethoxy)-ethanol (DMAFE), 2-((2-dimethylaminoethoxy)-ethyl methyl-amino)ethanol, 1-(bis(3-dimethylamino)-propyl)amino-2-propanol, N,N′,N″-tris(3-dimethylamino-propyl)hexahydrotriazine, dimorpholinodiethylether (DMDEE), N,N-dimethylbenzylamine, N,N,N′,N″,N″-pentaamethyldipropylenetriamine, N,N′-diethylpiperazine, and etc. In particular, sterically hindered primary, secondary or tertiary amines are useful, for example, dicyclohexylmethylamine, ethyldiisopropylamine, dimethylcyclohexylamine, dimethylisopropylamine, methylisopropylbenzylamine, methylcyclopentylbenzylamine, isopropyl-sec-butyl-trifluoroethylamine, diethyl-(α-phenyethyl)amine, tri-n-propylamine, dicyclohexylamine, t-butylisopropylamine, butylamine, cyclohexyl-t-butylamine, de-sec-butylamine, dicyclopentylamine, di-(α-trifluoromethylethyl)amine, di-(α-phenylethyl)amine, triphenylmethylamine, and 1,1,-diethyl-n-propylamine. Other sterically hindered amines are morpholines, imidazoles, ether containing compounds such as dimorpholinodiethylether, N-ethylmolpholine, N-methylmorpholine, bis(dimethylaminoethyl)ether, imidizole, n0methylimidazole, 1,2-dimethylimidazole, dimorpholinodimethylether, N,N,N′,N′,N″,N″-pentamethyldiethylenetriamine, N,N,N′,N′,N″,N″-pentaethyldiethylenetriamine, N,N,N′,N′,N″,N″-pentamethyldipropylenetriamine, bis(diethylaminoethyl)ether, bis(dimethylaminopropyl)ether, or combination thereof. 
         [0018]    Non-amine catalysts may comprise an organometallic compound containing bismuth, lead, tin, antimony, cadmium, cobalt, iron, thorium, aluminum, mercury, zinc, nickel, cerium, molybdenum, titanium, vanadium, copper, manganese, zirconium, magnesium, calcium, sodium, potassium, lithium, or combination thereof. Examples of such organometallic compound include stannous octoate, dibutyltin dilaurate (DGTDL), dibutyltin mercaptide, phenylmercuric propionate, lead octoate, potassium acetate/octoate, magnesium acetate, titanyl oxalate, potassium titanyl oxalate, quaternary ammonium formates, ferric acetylacetonate, and the like and combination thereof. 
         [0019]    The use level of catalysts are typically in an amount of 0.1 ppm to 4.00 wt % of polyol premix, preferably from 0.5 ppm to 2 wt %, and more preferably from 1 ppm to 1 wt %. 
         [0020]    The surfactants may comprise polysiloxane polyoxyalkylene block co-polymer such as B8404, B8407, B8409, B8462 and B8465 of Goldschmidt, DC-193, DC-197, DC-5582, and DC-5598 of Air Products, L-5130, L5180, L-5340, L-5440, L-6100, L-6900, L-6980, and L6988 of Momentive. Non-silicone surfactants may comprise salts of sulfonic acid, alkali metal salts of fatty acid, ammonium slats of fatty acid, oleic acid, stearic acid, dodecylbenzenedidulfonic acid, dinaphthylmetanedissulfonic acid, ricinoleic acid, an oxyethylated alkylphenol, an oxyethylated fatty alcohol, a paraffin oil, a caster oil ester, a ricinoleic acid ester, Turkey red oil, groundnut oil, a paraffin fatty alcohol, or combination thereof. The typically use levels are 0.4 to 6 wt % of polyol premix, preferably 0.8 to 4.5 wt %, and more preferably 1 to 3 wt %. 
         [0021]    Flame retardants may comprise trichloropropyl phosphate (TCPP), triethyl phosphate (TEP), diethyl ethyl phosphate (DEEP), diethyl bis(2-hydroxyethyl)amino methyl phosphonate, brominated anhydride based ester, dibromoneopentyl glycol, brominated polyether polyol, melamine, ammonium polyphosphate, aluminium trihydrate (ATH), tris(1,3-diehloroisopropyl) phosphate, tri)-2-chlororthyl) phosphate, tri(2-chloroisopropyl) phosphate, chloroalkyl phosphate/oligomeric phosphonate, oligomeric chloroalkyl phosphate, brominated flame retardant based on pentabromo diphenyl ether, dimethyl methyl phosphonate, diethyl N,N bis(2-hydroxyethyl)amino methyl phosphonate, oligomeric phosphonate, and derivatives of above mentioned. 
         [0022]    In certain embodiments, acid scavengers, radical scavengers, and other stabilizers/inhibitors are desired. Stabilizers/inhibitors may comprise 1,2-epoxy butane, glycidyl methyl ether, cyclic-terpenes such as di-limonene, 1-limonene, d-limonene, and etc, 1,2-epoxy-2,2-methylpropane, nitromethane, diethylhydroxyl amine, alpha methylstyrene, isoprene, p-methoxyphenol, m-methoxyphenol, dl-limonene oxide, hydrazines, 2,6-di-t-butyl phenol, hydroquinone, organic acids such as carboxylic acid, dicarboxylic acid, phosphonic acid, sulfonic acid, sulfamic acid, hydroxamic acid, formic acid, acetic acid, propionic acid, butyric acid, caproic acid, isocaprotic acid, 2-ethylhexanoic acid, caprylic acid, cyanoacetic acid, pyruvic acid, benzoic acid, oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, and combination thereof. Other additives may comprise adhesion promoters, anti-static, antioxidant, filler, hydrolysis, lubricants, anti-microbial, pigments, viscosity modifiers, UV resistance additives, are also desired as needed. Examples of these additives include, but are not limited to, sterically hindered phenols, diphenylamines, benzofuranone derivatives, butylated hydroxytoluene (BHT), calcium carbonate, barium sulphate, glass fibers, carbon fibers, micro-spheres, silicas. Melamine, carbon black, form of waxes and soaps, organometallic derivatives of antimony, copper, and arsenic, titanium dioxide, chromium oxide, iron oxide, glycol ethers, dimethyl AGS esters, propylene carbonate, benzophenone and benzotriazole compounds derivatives. 
       EXAMPLES 
     Example 1 
     Boiling Points and Solubility of Blowing Agents in Polyol Blends 
       [0023]      
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Boiling point and solubility in polyol blends 
               
             
          
           
               
                   
                 Blowing agent 
                 Boiling point (° C.) 
                 Solubility 
               
               
                   
                   
               
               
                   
                 E-1233zd 
                 18 
                 ++ 
               
               
                   
                 HFC245fa 
                 15 
                 + 
               
               
                   
                 HCFC141b 
                 33 
                 +++ 
               
               
                   
                 Pentanes* 
                 ** 
                 − 
               
               
                   
                   
               
               
                   
                 *Cyclo-pentane/iso-pentane = 80/20, cyclo-pentane boiling point: 49° C., and iso-pentane boiling point: 28° C. 
               
             
          
         
       
     
         [0024]    Table 1 shows that E-1233zd has a boiling between HFC245fa and HCFC141b, and solubility also follows the same trend. The lower the boiling point, the higher vapor pressure, providing more expansion of foams and thus lower foam density. The solubility of blowing agent would affect the viscosity of polymer premix, the better the solubility, the lower the viscosity. 
       Example 2 
     Formulation and Reactivity 
       [0025]      
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Formulations 
               
             
          
           
               
                   
                 E-1233zd 
                 HFC245fa 
                 HCFC141b 
                 Pentanes 
               
               
                   
                   
               
             
          
           
               
                 B side 
                   
                   
                   
                   
               
               
                 Voranol 490 
                 17.39 
                 17.35 
                 17.60 
                 18.25 
               
               
                 Jeffol R-425-X 
                 10.43 
                 10.41 
                 10.56 
                 10.95 
               
               
                 Stepan 2352 
                 6.96 
                 6.94 
                 7.04 
                 7.30 
               
               
                 PMDETA 
                 0.16 
                 0.16 
                 0.16 
                 0.16 
               
               
                 (PC5) 
               
               
                 DMCHA (PC8) 
                 0.50 
                 0.50 
                 0.50 
                 0.50 
               
               
                 Tegostab B8465 
                 0.71 
                 0.71 
                 0.71 
                 0.71 
               
               
                 TCPP 
                 2.36 
                 2.36 
                 2.36 
                 2.36 
               
               
                 Blowing Agent 
               
               
                 Water 
                 0.74 
                 0.74 
                 0.74 
                 0.74 
               
               
                 E-1233zd 
                 8.04 
                 0 
                 0 
                 0 
               
               
                 HFC245fa 
                 0 
                 8.26 
                 0 
                 0 
               
               
                 HCFC141b 
                 0 
                 0 
                 7.20 
                 0 
               
               
                 Pentanes 
                 0 
                 0 
                 0 
                 4.34 
               
               
                 Total B Side 
                 47.29 
                 47.42 
                 46.86 
                 45.32 
               
               
                 A Side 
               
               
                 ROH Index 
                 115 
                 115 
                 115 
                 115 
               
               
                 Isocyanate 
                 52.7 
                 52.6 
                 53.1 
                 54.7 
               
               
                 A/B 
                 1.11 
                 1.11 
                 1.13 
                 1.21 
               
               
                 Total Blowing 
                 23.0 
                 23.0 
                 23.0 
                 23.0 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Reactivity and free rise density 
               
             
          
           
               
                   
                 E-1233zd 
                 HFC245fa 
                 HCFC141b 
                 Pentanes 
               
               
                   
                   
               
             
          
           
               
                 Chemical Temperature 
                 70/70 
                 70/70 
                 70/70 
                 70/70 
               
               
                 (° F.) 
               
               
                 Cream time (seconds) 
                 6 
                 froth 
                 5 
                 5 
               
               
                 Gel time (seconds) 
                 28 
                 29 
                 29 
                 27 
               
               
                 Tack free time 
                 43 
                 46 
                 45 
                 44 
               
               
                 (seconds) 
               
               
                 Core density in bucket 
                 1.69 
                 1.65 
                 1.65 
                 1.68 
               
               
                 (pcf) 
               
               
                   
               
             
          
         
       
     
         [0026]    Table 3 shows that the reactivities of four systems are quite similar to each other. 
       Example 3 
     Molding 
       [0027]    The total B component and isocyanate were mixed using an Edge-Sweets 25 HP-BT high-pressure foam machine equipped with an L-head. Chemical temperatures were maintained at 70° F. prior to mixing at 1800 psi mix pressure and a total chemical throughput of 160 g/sec. 
         [0028]    Molded foams were produced using a water jacketed aluminum mold commonly referred to as a Brett mold or Lanzen panel which measured 5 cm thick by 20 cm wide by 200 cm tall and were kept at a temperature around 115° F. A minimum fill density, i.e., just enough foam to fill the entire mold without any amount of packing, was first established using data (length the foam flowed and panel weight) from shots made at 2, 3, and 4 seconds. A panel was produced at 115% of the shot weight calculated for the minimum fill density. 
         [0029]    In addition to determining the density of the panel, a comparison was made of the overall density versus the core density. This was done by taking every other 10 cm section along the length of the panel starting 60 cm from the bottom, measuring the density with the foam skin on, and then trimming off the skin to measure the core density. The data was compared to similar foams made with other blowing agents and found to give the least difference between overall and core densities. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Minimum fill weight 
               
             
          
           
               
                   
                 Minimum fill weight 
                 Minimum fill density 
               
               
                   
                 (g) 
                 (pcf*) 
               
               
                   
                   
               
             
          
           
               
                   
                 E-1233zd 
                 734 
                 2.63 
               
               
                   
                 HFC245fa 
                 727 
                 2.60 
               
               
                   
                 HCFC141b 
                 796 
                 2.90 
               
               
                   
                 Pentanes 
                 790 
                 2.85 
               
               
                   
                   
               
               
                   
                 *pcf: lb/ft 3   
               
             
          
         
       
     
         [0030]    From Table 4, it can be seen that the minimum fill weight and density of E-1233zd foam fall between HFC245fa and HCFC141b. HCFC141b that has the best solubility in polyol blends does not have the lowest minimum fill weight. However, HFC245fa that has the lowest boiling point provides a foam with the lowest minimum fill density. 
         [0031]    The results suggest that the boiling point has more influence on minimum fill weight than the solubility of a blowing agent.  FIG. 1  showed how density varied in the flow path within the panel. It appeared that higher boiling point blowing agent such as HCFC141b and pentanes had more variation or less uniform distribution than lower boiling point blowing agent such as HFC245fa, and E-1233zd. Following the boiling point trend, one would predict that the density distribution of E-1233zd foam should fall between HFC245fa and HCFC141b. However, as shown in  FIG. 1 , E-1233zd foam showed the least variation of density or the most uniform form density, therefore, this result is not expected. 
         [0032]    Although the invention is illustrated and described herein with reference to specific embodiments, it is not intended that the appended claims be limited to the details shown. Rather, it is expected that various modifications may be made in these details by those skilled in the art, which modifications may still be within the spirit and scope of the claimed subject matter and it is intended that these claims be construed accordingly.