HK1030227A - Flame resistant rigid polyurethane foams blown with hydrofluorocarbons - Google Patents

Description

Rigid polyurethane fire-resistant foams blown with fluorinated hydrocarbons

Field of the invention

The present invention relates to foams having improved fire resistance. In particular the foams of the present invention are closed-cell rigid polyurethanes or urethane-modified polyisocyanates.

Background of the invention

An important factor that rigid polyurethane foams are commercially affordable on a large scale in the building insulation industry is their ability to provide a good balance of properties. Rigid polyurethane foams are known to provide excellent thermal insulation, excellent fire resistance and superior structural properties, uniform and reasonably low density. Such rigid foams are (generally) prepared by reacting a suitable polyisocyanate and an isocyanate-reactive compound in the presence of a blowing agent. Chlorofluorocarbon blowing agents (CFCs) such as CFC-11 (CCl)₃F) And CFC-12 (CCl)₂F₂) Are commercially most important blowing agents primarily for their good thermal insulation and low or non-flammability. The use of such blowing agents is rigid polyurethanesThe main reason for the good balance of properties of foams. CFCs have recently been associated with decaying ozone concentrations in the earth's atmosphere, and their use has been severely limited. Chlorofluorinated hydrocarbons, in particular HCFC-141b (CCl)₂FCH₃) With HCFC-22 (CHClF)₂) Solutions that have become transitional in many applications are also known for their good thermal insulation and low or no flammability. HCFCs have a tendency to deplete ozone and their use is constantly under examination, and the production and use of HCFC-141b is currently planned to terminate in 2003 in the United states.

This environmental impact has led to the development of reactive systems which utilize blowing agents which have a zero ozone depletion potential while retaining the good balance of properties of the known rigid polyurethane foams. One class of materials that has been discussed as such blowing agents are fluorinated Hydrocarbons (HFCs) such as 1, 1, 1, 3, 3-pentafluoropropane (HFC-245 fa); 1, 1, 1, 3, 3-pentafluorobutane (HFC-365 mfc); 1, 1, 1, 2-tetrafluoroethane (HFC-134 a); 1, 1-difluoroethane (HFC-152 a). There are numerous patents and literature on the use of HFC's as blowing agents for rigid polyurethane foams. Uses of this material are disclosed in, for example, U.S. patent 5,496,866 (Bayer); 5,461,084 (Bayer); 4,997,706 (Dow); 5,430,071 (BASF); 5,444,101(ICI), etc. Although HFCs are more environmentally acceptable than CFCs and HCFCs, they are slightly inferior in flame retardancy. Polyurethane foams made with HFC blowing agents must have good fire resistance while maintaining good thermal and structural properties, all at densities comparable to CFC and HCFC blowing agents. Rigid polyurethane foams used in the construction industry are of particular importance for their fire resistance properties, since they must meet stringent fire protection specifications.

Fluorinated hydrocarbons and hydrocarbons are currently the two main classes of materials evaluated by the rigid foam industry as zero ozone depleting trend (ODP) blowing agents. Neither of these two classes of materials has all the properties of an "ideal" blowing agent. For example, HFCs are highly temperature efficient globally (lower than CFCs but still high for some reasons) and have low VOC content. Hydrocarbons have very low direct global temperature but are recognized as VOCs.

Therefore, there remains a need to develop a reaction system in which the blowing agent has a zero ozone depletion potential and which produces a good balance of properties for the known rigid polyurethane foams.

Summary of the invention

It is therefore an object of the present invention to provide closed-cell rigid polyurethane or urethane-modified polyisocyanurate foams which, even when foamed with fluorinated hydrocarbons, have comparable or improved fire resistance to CFC or HCFC foamed foams.

It is a further object of the present invention to provide closed-cell rigid polyurethane or urethane-modified polyisocyanurate foams blown with fluorinated hydrocarbons which have good thermal and structural properties together with improved fire-protection properties etc.

It has now been unexpectedly found that the use of more than 40% by weight of an aromatic polyester polyol having an average functionality of less than 3.0 as the polyfunctional isocyanate-reactive component, in conjunction with the use of an organophosphate in the foam formulation, improves the fire performance of polyurethane foams made in the presence of HFC blowing agents. Such HFC-blown foams also have surprisingly good thermal and structural properties along with improved fire-retardant properties. The compositions of the invention advantageously make it possible to obtain a balance of properties that is optimally suited to the present commercial and environmental requirements.

It has been surprisingly found that the density is from 1.2 to 4.2lb/ft³Rigid polyurethane foams having excellent fire resistance and good thermal and structural properties can be obtained with the following formulation:

(1) an organic polyisocyanate, wherein the polyisocyanate is selected from the group consisting of,

(2) the foaming agent contains

(a) C capable of volatilizing under foaming conditions₁-C₄Fluorinated hydrocarbon crop protecting foaming agents, with

(b) The amount of water is controlled by the amount of water,

(3) a polyfunctional isocyanate-reactive composition comprising 40% by weight of an aromatic polyester polyol having an average functionality of less than 3.0,

(4) organic phosphorus compounds, with

(5) One or more further auxiliaries or additives conventionally formulated for the production of rigid polyurethane and urethane-modified polyisocyanurate foams. Such optional additives include, without limitation, crosslinking agents, foam stabilizers or surfactants, catalysts, infrared opacifiers, cell size reducing compounds, viscosity reducing agents, miscibility agents, mold release agents, fillers, pigments, and antioxidants, wherein the organophosphorus compound is used in an amount such that the phosphorus content is between about 0.01 and about 2.5 weight percent, based on the total weight of the foam reaction mixture.

In summary, a surprising technical advantage of the present invention is the discovery of rigid polyurethane foam formulations blown with fluorinated hydrocarbon (zero ODP) blowing agents that produce foams having fire performance in laboratory tests equal to or better than those blown with CFCs or HCFCs; structural properties such as compressive strength and long term dimensional stability properties are comparable to or better than foams blown with CFCs or HCFCs; initial and long term thermal insulation properties are comparable to CFCs or HCFCs foamed foams.

The foams of the present invention are suitable for use in continuous laminate foams for the insulation of store roofs and residential walls, as well as for metal panels, spray foams, fire doors, and the like.

Detailed description of the invention

Each of the above materials utilized in the foams of the present invention is described below.

(1) Isocyanate: any organic polyisocyanate may be used in the practice of the present invention. A preferred isocyanate is polyphenylene polymethylene Polyisocyanate (PMDI). The most preferred isocyanates are those PMDI having a diphenylmethane diisocyanate content of about 15 to about 42 weight percent based on 100 weight percent isocyanate.

The amount of isocyanate is typically from about 30 to about 75%, preferably from about 40 to about 70%, and most preferably from about 45 to about 65%, based on 100% total foam formulation weight.

(2a) HFC blowing agent: any that can be vaporized under foaming conditionsC₁-C₄The fluorinated hydrocarbons can be used alone or in mixtures. Suitable HFCs include difluoromethane (HFC-32); trifluoromethane (HFC-23); 1, 1-difluoroethane (HFC-152 a); 1, 1, 1-trifluoroethane (HFC-143 a); 1, 1, 1, 2-tetrafluoroethane (HFC-134 a); pentafluoroethane (HFC-125); all isomers of pentafluoropropane (HFC-245fa, ca, ed, ea, etc.); all isomers of heptafluoropropane (HFC-236ca, cb, ea, eb); isomers of pentafluorobutane (HFC-365); 1, 1, 1, 4, 4, 4-hexafluorobutane (HFC-356 mffm). Preferred HFCs include 1, 1, 1, 3, 3-pentafluoropropane (HFC-245 fa); 1, 1, 13, 3-pentafluorobutane (HFC-365 mfc). HFC-245fa is most preferred.

Other blowing agents, in particular air, nitrogen, carbon dioxide, alkanes, alkenes, ethers, can be used as secondary physical blowing agents. Representative alkanes include n-butane, n-pentane, isopentane, cyclopentane, mixtures thereof, and the like. Representative alkenes include 1-pentene. Representative ethers include dimethyl ether.

(2b) Water: reaction of water with isocyanate to give CO under foaming conditions₂. Water can be used with any of the physical blowing agents described in 2 (a).

The blowing agent is present in an amount sufficient to produce a foam having from 1.2 to 4.2lb/ft³Preferably 1.4 to 4.0lb/ft³Preferably 1.6 to 3.8lb/ft³. Additionally, the amount of HFC used is such that the initial preparation of the rigid foam is between about 99 to 20 percent, preferably about 97 to 30 percent, and most preferably about 95 to 40 mole percent HFC in the gaseous mixture in the closed cells.

(3) Polyfunctional isocyanate-reactive composition: they typically contain more than about 40% by weight of aromatic polyester polyols having an average functionality of 3 or less, the remainder being other types of isocyanate-reactive compounds.

Suitable aromatic polyester polyols include those prepared by the reaction of a polycarboxylic acid and/or derivative or anhydride thereof with a polyol, wherein at least one of the reactants is aromatic. The polycarboxylic acids may be any of the known aliphatic, cycloaliphatic, aromatic, and/or heterocyclic polycarboxylic acids and may be substituted (for example, with halogen atoms) and/or unsubstituted. Examples of suitable polycarboxylic acids and anhydrides include oxalic acid, malonic acid, glutaric acid, pimelic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic anhydride, pyromellitic dianhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, and dimeric and trimeric fatty acids, such as those of oleic acid, which may be mixed with monomeric fatty acids. Simple esters of polycarboxylic acids such as dimethyl terephthalate, bis-glycol terephthalate and their extracts are also useful.

Suitable examples of aromatic polycarboxylic acids are phthalic acid, isophthalic acid, terephthalic acid, and trimellitic acid. Suitable aromatic polycarboxylic acid derivatives are dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, and the dimethyl or diethyl esters of trimellitic acid. Suitable examples of aromatic anhydrides are phthalic anhydride, tetrahydrophthalic anhydride and pyromellitic anhydride.

While polyester polyols can be prepared from the substantially pure reactant materials listed above, more complex components such as side streams, waste or residue from the manufacture of phthalic acid, anhydrides, terephthalic acid, dimethyl terephthalate, polyvinyl terephthalate, and the like, can be advantageously used.

Suitable polyols for the preparation of the polyester polyols may be aliphatic, cycloaliphatic, aromatic, and/or heterocyclic. The polyols may optionally include reactive substituents such as chlorine and bromine substituents and/or may be unsaturated. Suitable amino alcohols such as monoethanolamine or diethanolamine may also be used. Examples of suitable polyols include ethylene glycol, propylene glycol, polyoxyalkylene glycols (e.g., diethylene glycol, polyethylene glycol, dipropylene glycol and polypropylene glycol), glycerol and trimethylolpropane. Suitable examples of aromatic polyols are 1, 4-benzenediol, hydroquinone bis (2-hydroxyethyl) ether, bis (hydroxyethyl) terephthalate and resorcinol.

The polyester polyols utilized in the present invention are aromatic and have an average functionality of less than 3. For example, the polycarboxylic acid (and/or derivative or anhydride component thereof) or the polyol or both are aromatic and the average functionality of the reaction productThe degree is less than 3.0. Many such polyols are commercially available. STEPANPOL^PS-2352, PS-2402, PS-3152 are several such polyols manufactured by Stepan co. TERATE^2541, 254, 403, 203 are several such polyols from Hoechst-Celanese Corp. TEROL^235, 235N, 250 are several such polyols made by Oxid, inc.

The polyfunctional isocyanate-reactive composition may contain up to 60% of other suitable isocyanate-reactive compounds. Examples of such ingredients include polyether polyols, aliphatic polyester polyols, and mixtures thereof, having an equivalent weight of from about 40 to about 4000, preferably from about 50 to about 3000, and an average hydroxyl functionality of from about 2 to about 8, preferably from about 2 to about 6. Other examples of suitable polyfunctional isocyanate-reactive compositions include active hydrogen-terminated polythioethers, polyamides, polyesteramides, polycarbonates, polyacetals, polyolefins, polysiloxanes, and the like. Additional suitable isocyanate-reactive materials include primary and secondary diamines (Unilink 4200), enamines, cyclic ureas, cyclic carbonates, and polycarboxylic acids. Several of these compounds react with isocyanates to evolve carbon dioxide, which results in foaming.

(4) Organic phosphorus compounds: various phosphorus-containing organic compounds can be used. Suitable compounds include phosphates, phosphites, phosphonates, polyphosphates, polyphosphites, polyphosphonates, ammonium polyphosphates. Suitable phosphate compounds have the following formula:in the formula R¹To R³Represents an alkyl group, a halogen-substituted alkyl group, an aryl group, a halogen-substituted aryl group, a cycloalkyl group or the like. Preferred phosphates are those wherein R¹To R³Represents C₁-C₁₂Alkyl radical, C₁-C₁₂Halogen-substituted alkyl, phenyl, tolyl, halogen-substituted phenyl and C₅-C₁₀A cycloalkyl group. More preferably a phosphate ester wherein R is¹To R³Is represented by C₁-C₈Alkyl radical, C₁-C₈Halogen-substituted alkyl, and phenyl. Most preferably the phosphate compound is R¹To R³Is represented by C₁-C₄Alkyl radical, C₁-C₄Halogen-substituted alkyl, and phenyl. Several particularly suitable phosphates are triethyl phosphate (TEP from Eastman), tributyl phosphate, tris (2-chloropropyl) phosphate (Albright)&Antiblaze80 from Wilson), and chloropropylbis (bromopropylphosphate (fiamaster fm836 from Great Lakes).

Suitable phosphite compounds have the following formula:wherein R is¹To R³Represents H, alkyl, halogen-substituted alkyl, aryl, halogen-substituted aryl, cycloalkyl, etc. Preferred phosphites are their R¹To R³Represents C₁-C₁₂Alkyl radical, C₁-C₁₂Halogen-substituted alkyl, phenyl, tolyl, halogen-substituted phenyl and C₅-C₁₀Cycloalkyl groups, and the like. More preferably the phosphite is R¹To R³Is represented by C₁-C₈Alkyl radical, C₁-C₈Halogen-substituted alkyl, and phenyl. The most preferred phosphite compounds are R thereof¹To R³Is represented by C₁-C₄Alkyl radical, C₁-C₄Halogen-substituted alkyl and phenyl. Particularly suitable phosphites are triethyl phosphite (Albright)&Albrite TEP from Wilson, tris (2-chloroethyl) phosphite, and triphenyl phosphite (Albrite TPP).

Suitable phosphonate compounds have the formula:in the formula R¹To R³Represents an alkyl group, a halogen-substituted alkyl group, an aryl group, a halogen-substituted aryl group, a cycloalkyl group or the like. Preferred phosphonates are those wherein R¹To R³Represents C₁-C₁₂Alkyl radical, C₁-C₁₂Halogen-substituted alkyl, phenyl, tolyl, halogen-substituted phenyl and C₅-C₁₀A cycloalkyl group. More preferably a phosphonate wherein R is¹To R³Is represented by C₁-C₈Alkyl radical, C₁-C₈Halogenated alkyl and phenyl. Most preferred are phosphinesThe acid ester compound is R thereof¹To R³Is represented by C₁-C₄Alkyl radical, C₁-C₄Halogen-substituted alkyl and phenyl. Several particularly suitable phosphonates are diethyl ethyl phosphonate (Albright)&Amgard V490 from Wilson), dimethyl methyl phosphonate (Amgard DMMP), bis (2-chloroethyl) phosphonate and 2-chloroethyl phosphonate.

An example of a polyphosphate compound is A&Amgaurd V-6 from W, a chlorinated diphosphate. Ammonium polyphosphate [ (NH)₄PO₃)n](ii) a An example of n-1000 is Hostaflam AP 422 from Hoechst AG.

The organophosphorus compounds useful in the present invention may have one or more isocyanate-reactive hydrogens containing hydroxyl, amino, thio, or mixtures thereof. Suitable compounds include monomeric or oligomeric phosphates, phosphites and phosphonate polyols. Suitable isocyanate-reactive phosphate compounds are prepared by reacting (1) a polyalkylene oxide with (a) phosphoric acid, (b) a partial ester of phosphoric acid; (2) reaction of an aliphatic alcohol with (a) phosphoric acid, (b) a partial ester of phosphoric acid; and (3) prepared by transesterification of the products of (1) and (2). Preferred compounds include organophosphate diols of tributoxyethyl phosphate (Phosflex T-BEP available from Akzo) oligomer (Hostaflam TP OP 550 available from Hoechst AG); ethoxylated phosphate esters (Unithox-5162 by Petrolite); and mono-and diesters of phosphoric acid with alcohols (Unithox X-1070 from Petrolite).

Suitable isocyanate-reactive phosphite compounds are prepared by the reaction of (1) polyalkylene oxides with (a) phosphorous acids (b) partial esters of phosphorous acid; (2) reaction of aliphatic alcohols with (a) phosphorous acids (b) partial esters of phosphorous acid; and (3) by transesterification of the products of (1) and (2).

Suitable isocyanate-reactive phosphonate compounds are prepared by (1) reacting a polyalkylene oxide with a phosphonic acid; (2) reaction of polyol phosphite with alkyl halides; (3) condensation of dialkyl phosphonates, diethanolamine with formaldehyde; (4) transesterification of the products from (1), (2) and (3); and (5) reaction of dialkyl alkylphosphonate with phosphorus pentoxide and alkylene oxide. Preferred compounds include diethyl N, N-bis (2-hydroxyethyl) aminoethyl phosphonate (Fyrol 6 of Akzo), oligomeric hydroxy-containing phosphonate (Fyrol 51 of Akzo).

The organophosphorus compound is present in an amount such that the phosphorus content is between about 0.01 and about 2.5 weight percent, based on the total weight of the foam-forming reaction mixture. The preferred phosphorus content is between about 0.025 to about 1.50%, and most preferably about 0.05 to about 1.0% by weight based on the total weight of the foam-forming reaction mixture.

(5) Additive: the resins may also contain various adjuvants and additives necessary for specific purposes. Suitable adjuvants and additives include cross-linking agents such as triethanolamine and glycerol; foam stabilizers or surfactants such as siloxane-oxyalkylene copolymers; ethylene oxide-alkylene oxide copolymers; catalysts such as tertiary amines (e.g., dimethylcyclohexylamine, pentamethyldiethylenetriamine, 2, 4, 6-tris (dimethylaminomethyl) phenol, triethylenediamine); organometallic compounds (e.g., potassium octoate, potassium acetate, dibutyltin dilaurate); quaternary ammonium salts (e.g., 2-hydroxypropyltrimethylammonium formate and N-substituted triazines (N, N', N "-dimethylaminopropyl hexahydrotriazine), viscosity reducers such as propylene carbonate, 1-methyl-2-pyrrolidone, infrared opacifiers such as carbon black, titanium dioxide, metal flakes, pore size reducing compounds such as inert insoluble fluorinated compounds, perfluorinated compounds, reinforcing agents such as glass fibers, ground foam waste, mold release agents such as zinc stearate, antioxidants such as butylated hydroxytoluene, and pigments such as azo-/diazo dyes, phthalocyanines, and the like.

The amount of these additives is generally between about 0.1 and 20%, preferably between about 0.3 and 15%, and most preferably between about 0.5 and 10%, based on 100% total foam formulation weight.

Carrying out the process for making rigid foams according to the present invention, one-shot, prepolymer or semi-prepolymer techniques are known to be useful with conventional mixing methods, including vibratory mixing. Rigid foams may be formed into slabstock, molded articles, cavity-filling, spray foams, spray (gas) foams, or laminates with other materials such as paper, metal, plastic, or wood.

Various aspects of the invention are illustrated by the following examples and are not intended to be limiting. Unless otherwise noted, all temperatures are in degrees Celsius and all formulation components are in parts by weight.

Examples of the invention

The following materials are mentioned in the examples.

STEPANPOL^PS-2352: an aromatic polyester polyol available from Stepan corporation having a hydroxyl number of 240mg KOH/g, an average functionality of about 2, and a viscosity of 3,000cPs at 25 ℃. The aromatic polyester polyol content of the polyol is more than 80% by weight.

VORANOL^240-800: polyether polyol available from Dow chemical having a hydroxyl number of 800mg KOH/g, an average functionality of 3, and a viscosity of 3,500 centistokes at 100 ° F.

ALKAPOL^A-630: aliphatic amino polyether polyol from Dow chemical, hydroxyl value 630mg KOH/g, average functionality 3, viscosity 450cPs at 25 ℃.

RUBINOL^R159: aromatic amino polyether polyols from ICI Americas inc. having a hydroxyl number of 500mg KOH/g, an average functionality of 3.2, and a viscosity of 18000cPs at 25 ℃.

RUBINOL^R124: aromatic amino polyether polyols from ICI Americas inc. having hydroxyl number of 395mg KOH/g, average functionality of 3.9, viscosity 18000cPs at 25 ℃.

TCPP: tris (β -chloropropyl) phosphate (P ═ 9.5%), available from Akzo nobel chem.

TEP: triethyl phosphate (P ═ 17%) available from Eastman chem.

PELRON^9540A: a solution of potassium octoate in diethylene glycol, available from Pelron corp.

PELRON^9650: diethylene glycol of potassium acetate available from Pelron corpAnd (3) solution.

POLYCAT^5: pentamethyldiethylenetriamine available from Air Products.

DABCO^33 LV: a dipropylene glycol solution of triethylene diamine available from Air Products.

DABCO^125: organotin urethane catalysts available from Air Products.

TEGOSTAB^B84 PI: a siloxane surfactant available from Goldschmidt corp.

TEGOSTAB^B8404: a siloxane surfactant available from Goldschmidt corp.

LK-221^: a non-silicone surfactant available from Air Products.

HCFC-141 b: dichlorofluoroethane blowing agents available from Elf-Atochem North America.

HFC-245fa (pressurized): available from allied signal Chemicals.

RUBINATE^1850: a high functionality polymeric MDI available from ICI Americas.

Example 1

A number of rigid polyurethane foams were prepared using the formulations shown in Table 1. All foams were made using the following general procedure.

"polyol component" all of the components listed below, except HFC-245fa, were mixed together at room temperature in a high speed mixer to make a polyol blend. The polyol blend was added to the "polyol component" tank of an Edge-Sweets high pressure vibratory mixing jet. An appropriate amount of HFC-245fa was added to the "polyol component" tank in accordance with the ingredients shown in table 2 and mixed vigorously using an air mixer mounted on the tank. The isocyanate was added to an "isocyanate component" tank mounted on a sprayer. The mechanical parameters are set as follows: mechanical parameters foam #1, 2, &3 foam #4 "isocyanate component" temperature, ° F7080 "polyol component" temperature, ° F6070 mixing pressure, Psig 2,0002,000 "side" pump RPM 7070 "polyol side" pump RPM adjusted such that polyol component is

Para isocyanate component weight fraction para isocyanate component

Such as the weight shown in table 1 versus the dispensing speed, grams per second 200200, shown in table 1

The foaming composition was injected from a jet into a 5 liter cup and the reactivity and density of the free-foaming foam were measured. Foam core density was measured according to ASTM D1622. The fire performance was tested on foam specimens taken from 4 "x 15" foam blocks according to ASTM D3014, Butler Chimney test. This test measures the weight retention and fire extinguishing time of the foam specimen. Fire resistance was also measured on a hot plate test on core specimens taken from 7 "x 15" foams made by spraying foam components into cardboard boxes. Hot plate test description see "flammability study of Hydrocarbon blown isocyanurate foams", record 35 th SPI polyurethane technology/market annual meeting, page 561 (1994). Maximum smoke density under combustion conditions in the NBS smoke test was measured according to astm e 662.

Structural properties were measured on core specimens of 7 "x 15" foams made by free-blowing the foam composition into cardboard boxes. The "Dimvac method" described in "evaluation technique of various factors affecting the long-term dimensional stability of rigid polyurethane foam" according to the polyurethane 1995 meeting bibliography at page 11 (1995) measures the dimensional stability at low temperature after 7 days of exposure to mist at-25 ℃. Procedure a measures compressive strength parallel and perpendicular to the foam direction according to astm d 1621. The thermal properties of the foam were measured according to the procedure described in ASTM C518 for foam cores taken from 4 "x 15" foam blocks. Foams #1 and #2 represent foams made with formulations according to the present invention. Foam #3 and #4 represent control foams. Foams #1, #2 and #3 were blown with HFC-245fa, a zero ODP blowing agent. The formulation used to make foam #4 represents the current state of the art and is blown with an ozone depleting blowing agent, HCFC-141 b.

In the Butler Chimney test, higher weight retention, lower flame height and shorter fire extinguishing time indicate superior fire resistance. As can be seen in Table 1, the fire resistance characteristics of foam #1 and foam #2 (as measured by the Butler Chimney test) are much better than foam #3, and comparable or better than foam # 4. In the hot plate test, the weight remains high and the thickness remains high, meaning that the fire resistance is superior. The fire resistance of foam #1 and foam #2 (as measured by the hot plate test) was much better than foam #3 and corresponded to or better than foam # 4. The lower the maximum smoke density, the better the fire resistance of the foam in the NBS smoke test. Foam #1 and #2 also gave much better fire resistance than foam #3 and # 4. Thus, in all of the laboratory fire tests, foams #1 and #2 have fire resistance properties much better than foam #3 and comparable or better than foam # 4. Although foams #1, #2 and #3 were blown with HFC and with > 50% aromatic polyester polyol, only foams #1 and #2 contained the organic phosphorus compounds reported. Foam #4 represents the current state of the art and is also blown without an organophosphorus compound and with HCFC blowing agent HCFC-141 b.

In the dimensional stability test, the closer the% linear change is to zero, the better the dimensional properties of the foam. Foams #1 and #2 had better dimensional stability than foams #3 and # 4. The higher the value, the better the structural properties of the foam in the compressive strength measurement. Here too, foams #1 and #2 have better properties than foams #3 and # 4.

In the thermal property evaluation, the lower the k-factor, the better the thermal insulation performance of the foam. It can be seen in Table 1 that foams #1, #2 and #3 have the same initial k-factor but slightly higher than # 4. Foams #1 and #2 of the present invention aged with a lower k-factor and therefore better than state of the art foam # 4.

Example 2

Rigid polyurethane foam #5 was prepared for comparison using the formulation shown in Table 2. Foam #5 was prepared using an organic polyisocyanate, a fluorinated hydrocarbon (HFC-245fa) as the blowing agent, a polyether polyol as the polyfunctional isocyanate-reactive composition, an organophosphorus compound and other additives. Foam #5 did not use an aromatic polyester polyol as the functional isocyanate-reactive component and was therefore a control foam.

As seen in Table 2, the fire resistance of foam #5 (using the Butler Chimney test, the hot plate test and the flame height test of NBS) is much poorer than for foams #1 and # 2. Foam #5 had similar and slightly inferior fire resistance to foam # 3. Although foams #1, #2 and #5 were blown with HFC and contained organophosphorus compounds, only #1 and #2 were used with the aromatic polyester polyols disclosed in the present invention. This suggests that both organophosphorus compounds and aromatic polyester polyols are necessary to obtain good fire resistance with HFC blowing agents.

Foam #5 has similar and acceptable structural properties as foam #1 and foam # 4. Foam #5 had a less good k-factor for initiation and aging than foams #1 and #2 of the present invention. The aged k-factor of foam #5 is similar to state of the art foam # 4.

This result clearly demonstrates that foams (#1 and #2) made with the formulations of the present invention have superior fire performance and comparable or better structural and thermal insulation properties when foamed with environmentally acceptable HFC blowing agents than foams (#3 and #5) made with the external formulations of the present invention. The formulation of the present invention makes it possible to produce foams having comparable or better flame resistance, structural and thermal insulation properties than those produced with current HCFC blowing agents.

The present invention has been described in considerable detail above. It will be appreciated that modifications routinely made by those of ordinary skill in the art will be considered to be within the scope of the present invention.

Table 1 foam samples foam foams

#1 #2 #3 #4 "polyol component" Stepanpol PS-2352100100100100 TCPP 7.5TEP 7.5Tegostab B84PI 2Tegostab B84041.51.51.5 Pelron 9540A 2.22.22.21.75 Pelron 96500.70.70.70.6 Polycat 50.50.50.50.5 Water 0.50.50.50.5 HCFC-141B 31HFC-245fa 40.240.239 "isocyanate component" Rubinate 1850177.6177.6177.6180 foam formulation% phosphorus 0.220.4200 aromatic polyols make up the weight% reactivity of the isocyanate 80+ 80+ 80+ reactive components: bubble time, second 4349 gel time, second 20172118 tack free time, second 25213023 foam properties: free foaming Density pcf 2.02.01.91.9 fire performance Butler Chimnney test Retention weight% 90973694 maximum flame height, cm 241625 + 25+ time to extinguish, second 18113711 Hot plate test Retention weight 73714471 Retention thickness% 97901291 maximum Smoke Density 8467104108 structural Properties: dimensional stability-7 days linear change at-25 ℃ C. -0.1-0.1-0.3-0.3 compressive strength, psi parallel to the direction of foaming 61504952 and perpendicular to the direction of foaming 21171415 thermal properties k-factor BTU.in/ft²Hr. ° F onset 0.1330.1330.1330.128 room temperature 3 months later 0.1510.1540.1550.162

Table 2 foam sample foam #5 "polyol component" Voranol 240-80028.6 Alkapol a-63019.0 Rubinol R15944.1 Rubinol R1248.3 TCPP 8.3 LK-2211.4 Dabco 33LV 0.7Dabco 1250.7 HFC-245fa 26.7 "isocyanate component" Rubinate M151.4 foam formulation% phosphorus 0.27 aromatic polyol by weight of isocyanate-reactive 0 ingredients foam properties: foam density pcf 2.6 fire performance Butler Chimnney test Retention weight%14.4 maximum flame height, cm 25+ time to extinguish, second 42 hotplate test retention wt% 0 retention thickness% 0 maximum smoke density 506 structural properties: dimensional stability-1 Linear% Change compression Strength at-25 ℃ for 7 days, parallel to the foam Direction, psi 50 compression Strength, perpendicular to the foam Direction, psi 29 thermal Properties, k-factor BTU.in/ft²Hr. ° F0.160 after 3 months at room temperature starting at 0.142

Claims (30)

1. A composition for making a foam comprising

(a) An organic isocyanate;

(b) an isocyanate reactive composition comprising at least 40% by weight, based on the total weight of the isocyanate reactive composition, of an aromatic polyester polyol having an average functionality of less than 3;

(c) c₁To C₄A fluorinated hydrocarbon blowing agent; and

(d) an organophosphorus compound.

2. A foam forming composition as claimed in claim 1 wherein the organic isocyanate is a polyphenylenepolymethylene polyisocyanate.

3. A foam forming composition as claimed in claim 2 wherein the isocyanate comprises diphenylmethane diisocyanate in an amount equal to about 15% to about 42% by weight based on the total weight of the isocyanate.

4. A foam forming composition as claimed in claim 1 wherein the amount of isocyanate is equal to from about 30% to about 75% by weight based on the total weight of the foam forming composition.

5. A foam forming composition as claimed in claim 1 wherein the aromatic polyester polyol in the isocyanate reactive composition is prepared by reacting an aromatic polycarboxylic acid with a polyol.

6. A foam forming composition as claimed in claim 1 wherein the isocyanate reactive composition also contains a compound selected from the group consisting of polyether polyols, aliphatic polyester polyols, hydrogen-terminated polythioesters, polyamides, polyesteramides, polycarbonates, polyacetals, polyolefins and polysiloxanes.

7. A foam forming composition as claimed in claim 1 wherein C₁-C₄The fluorinated hydrocarbon blowing agent is selected from the group consisting of difluoromethane, trifluoromethane, 1, 1-difluoroethane, 1, 1, 1-trifluoroethane, 1, 1, 1, 2-tetrafluoroethane, pentafluoroethane, any isomer of pentafluoropropane, any isomer of heptafluoropropane, any isomer of pentafluorobutane, 1, 1, 1, 4, 4, 4-hexafluorobutane, 1, 1, 1, 3, 3-pentafluoropropane and 1, 1, 1, 3, 3-pentafluorobutane.

8. A foam forming composition as claimed in claim 7 wherein the fluorinated hydrocarbon blowing agent is 1, 1, 1, 3, 3-pentafluoropropane.

9. A foam forming composition as claimed in claim 1 wherein the composition contains water as an additional blowing agent.

10. A foam forming composition as claimed in claim 1 wherein the organophosphorus compound is selected from the group consisting of phosphates, phosphites, phosphonates, polyphosphates, polyphosphites, polyphosphonates and ammonium polyphosphates.

11. A foam forming composition as claimed in claim 1 wherein the organophosphorus compound is a phosphate compound having the formula:

in the formula R¹、R²And R³Each independently selected from alkyl, halo-substituted alkyl, aryl, halo-substituted aryl, cycloalkyl, and the like.

12. A foam forming composition as claimed in claim 11 wherein R¹、R²And R³Each is independently selected from C₁-C₁₂Alkyl radical, C₁-C₁₂Halogen-substituted alkyl, phenyl, tolyl, halogen-substituted phenyl and C₅-C₁₀Cycloalkyl groups, and the like.

13. A foam forming composition as claimed in claim 11 wherein R¹、R²And R³Is C₁To C₈Alkyl or C₁To C₈Halogen-substituted alkyl.

14. A foam forming composition as claimed in claim 11 wherein R¹、R²And R³Is C₁To C₄Alkyl or C₁To C₄Halogen-substituted alkyl.

15. According to claim 11 the foam forming composition of wherein R¹、R²And R³Is phenyl.

16. A foam forming composition as claimed in claim 1 wherein the organophosphorus compound is a phosphite compound having the formula:

in the formula R¹、R²And R³Each independently selected from H, alkyl, halogen substituted alkyl, aryl, halogen substituted aryl and cycloalkyl, and the like.

17. A foam forming composition as claimed in claim 16 wherein R¹、R²And R³Each is independently selected from C₁-C₁₂Alkyl radical, C₁-C₁₂Halogen-substituted alkyl, phenyl, tolyl, halogen-substituted phenyl and C₅-C₁₀Cycloalkyl groups, and the like.

18. A foam forming composition as claimed in claim 16 wherein R¹、R²And R³Each is independently selected from C₁-C₈Alkyl or C₁-C₈Halogen-substituted alkyl.

19. A foam forming composition as claimed in claim 16 wherein R¹、R²And R³Each independently selected from C₁-C₄Halogen-substituted alkyl.

20. A foam forming composition as claimed in claim 16 wherein R¹、R²And R³Is phenyl.

21. A foam forming composition as claimed in claim 1 wherein the organophosphorus compound is a phosphonate compound having the formula:

in the formula R¹、R²And R³Each independently selected from alkyl, halo-substituted alkyl, aryl, halo-substituted aryl, cycloalkyl, and the like.

22. A foam forming composition as claimed in claim 21 wherein R is¹、R²And R³Each is independently selected from C₁-C₁₂Alkyl radical, C₁-C₁₂Halogen-substituted alkyl, phenyl, tolyl, halogen-substituted phenyl and C₅-C₁₀Cycloalkyl groups, and the like.

23. A foam forming composition as claimed in claim 21 wherein R is¹、R²And R³Each is independently selected from C₁-C₈Alkyl or C₁-C₈Halogen-substituted alkyl.

24. A foam forming composition as claimed in claim 21 wherein R is¹、R²And R³Each is independently selected from C₁-C₄Alkyl or C₁-C₄Halogen-substituted alkyl.

25. A foam forming composition as claimed in claim 21 wherein R is¹、R²And R³Is phenyl.

26. A foam forming composition as claimed in claim 1 wherein the organophosphorus compound contains at least one isocyanate-reactive hydrogen group selected from the group consisting of a hydroxyl group, an amino group and a thio group.

27. A foam forming composition as claimed in claim 1 wherein the organophosphorus compound is present in an amount such that the phosphorus content of the composition is equal to about 0.01 to about 2.5% by weight, based on the total weight of the composition.

28. A foam forming composition as claimed in claim 27 wherein the amount of organophosphorus compound used is such that the amount of phosphorus in the composition is in the range of about 0.025 to about 1.5% by weight, based on the total weight of the composition.

29. A foam forming composition as claimed in claim 27 wherein the amount of organophosphorus compound used is such that the amount of phosphorus in the composition is in the range of about 0.05 to about 1.0% by weight, based on the total weight of the composition.

30. A density of from 1.2 to 4.2lb/ft prepared from the composition of claim 1³The rigid polyurethane foam of (1).