HK1029129A - Isocyanate compositions for blown polyurethane foams - Google Patents
Isocyanate compositions for blown polyurethane foams Download PDFInfo
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Description
The present invention relates to a process for producing rigid polyurethane foams and to the reaction systems used therein. More particularly, the present invention relates to a process for the production of rigid polyurethane foams using specific polyisocyanate compositions, reactive isocyanate compositions and fluorocarbon or hydrocarbon blowing agents.
Rigid polyurethane foams have many known uses, such as building materials and thermal insulation. The foams are known to have excellent structural properties, significant initial and long-term thermal insulation and excellent flame retardancy.
Rigid polyurethane foams are generally prepared by reacting the appropriate polyisocyanate with a reactive isocyanate groupThe compound is prepared by reaction in the presence of a proper foaming agent. As blowing agents, the most widely used are chlorofluorocarbons (CFC's), such as CFC-11 (CCl)3F) And CFC-12 (CCl)2F2) Since the chlorofluorocarbons can be used for producing foams having good thermal insulation properties, low flammability and excellent dimensional stability. However, in addition to these advantages, CFC's have the disadvantage that they deplete ozone from the earth's atmosphere and may also contribute to the global greenhouse effect. Thus, the use of CFC's is severely limited.
Chlorofluorocarbons (HCFC's) such as HCFC 141b (CCl)2FCH3) And HCFC22 (CHClF)2) Has become a widely adopted temporary solution. However, HCFC's have also been shown to cause similar ozone depletion in the earth's atmosphere and, therefore, their use has also been carefully investigated. In fact, the widespread production and use of HCFC's is also intended to be terminated in a short time.
Accordingly, there is a need to develop a method of forming a rigid polyurethane foam that utilizes a blowing agent having a non-ozone depleting ability and yet provides a rigid polyurethane foam having excellent thermal insulation properties and dimensional stability.
The classes of materials that have been described as such blowing agents include various hydrocarbons such as n-pentane, n-butane and cyclopentane. The use of such materials is well known and is disclosed, for example, in U.S. patents 5,096,933, 5,444,101, 5,182,309, 5,367,000 and 5, 387,618. However, the known processes for making foams with these blowing agents and the reaction systems used in such processes have not been found to produce rigid polyurethane foams having commercially attractive physical properties at densities sufficiently low to make their use feasible. In short, such hydrocarbon blown foams have inferior properties to foams blown with CFCs and HCFCs.
Attention has turned to the use of hydrofluorocarbons (HFC's) including: 1, 1, 1, 3, 3-pentafluoropropane (HFC 245 fa); 1, 1, 1, 3, 3-pentafluorobutane (HFC365 mfa); 1, 1, 1, 2-tetrafluoroethane (HFC 134 a); and 1, 1-difluoroethane (HFC152 a). The use of such materials as rigid polyurethane foam blowing agents is disclosed in, for example, U.S. patents 5,496,866; 5,461,084, respectively; 4,997,706, respectively; 5,430,071 and 5,444,101. However, rigid foams attempted with such materials generally do not form foams having structural, thermal and thermal properties comparable to those obtained using CFC-11 as a blowing agent if hydrocarbons are used.
Most of the attempts to solve this problem have focused on different fluorocarbons, mixtures of hydrocarbons or mixtures of hydrocarbons and fluorocarbons and/or other blowing agents. These tests have met with limited success.
Accordingly, there remains a need for a process for producing rigid polyurethane foams that utilizes hydrofluorocarbon or hydrocarbon blowing agents and provides foams with excellent physical properties.
The object of the present invention is obtained by using polymeric polyisocyanates of specific composition in the production of rigid polyurethane foams using hydrofluorocarbon or hydrocarbon blowing agents. The present invention provides foams having improved physical and thermal insulation properties.
The present invention relates to a process for the manufacture of rigid polyurethane foams comprising reacting:
(1) polyphenylene polymethylene polyisocyanate compositions;
(2) a reactive isocyanate composition comprising a plurality of reactive isocyanate groups, which composition is useful for preparing rigid polyurethane or urethane-modified polyisocyanurate foams;
(3) a fluorocarbon or hydrocarbon blowing agent;
(4) optionally, water or other carbon dioxide-releasing compounds, and wherein the polyphenylene polymethylene polyisocyanate comprises:
(a)15 to 42% by weight (based on 100% of polyisocyanate component (1)) of diphenylmethane diisocyanate;
(b) a tricyclic oligomer of polyphenylene polymethylene polyisocyanate (hereinafter referred to as triisocyanate) in an amount such that the ratio of diisocyanate to triisocyanate is between about 0.2 and about 1.8; and is
(c) The remainder being higher homologues of polyphenylene polymethylene polyisocyanates.
The present invention further relates to a reaction system for the preparation of rigid polyurethane foams, comprising:
(1) polyphenylene polymethylene polyisocyanate compositions;
(2) a reactive isocyanate composition comprising a plurality of reactive isocyanate groups, which composition is useful for preparing rigid polyurethane or urethane-modified polyisocyanurate foams;
(3) a fluorocarbon or hydrocarbon blowing agent;
(4) optionally, water or other carbon dioxide-releasing compounds, and wherein the polyphenylene polymethylene polyisocyanate comprises:
(a)15 to 42% by weight (based on 100% of polyisocyanate component (1)) of diphenylmethane diisocyanate;
(b) a tricyclic oligomer of polyphenylene polymethylene polyisocyanate (hereinafter referred to as triisocyanate) in an amount such that the ratio of diisocyanate to triisocyanate is between about 0.2 and about 1.8; and is
(c) The remainder being higher homologues of polyphenylene polymethylene polyisocyanates.
The polyphenylene polymethylene polyisocyanate used in the present invention is represented by formula I:
the 3-ring oligomers of component 1(b) are represented by formula I, wherein n ═ 1, and the higher homologs of component 1(c) are represented by formula I, wherein n > 1.
The polyphenylene polymethylene polyisocyanate composition (1) used in the present invention comprises from about 15 to about 42%, preferably from about 20 to about 40% and more preferably from 24 to about 38% by weight (based on 100% of the polyisocyanate component) of diphenylmethane diisocyanate. Diphenylmethane diisocyanate isomers in the 2, 2 ', 2, 4 ' and 4, 4 ' forms and mixtures thereof are useful in the present invention. Any variant of the 2, 2 ', 2, 4 ' and 4, 4 ' -isomers may be used.
The polyphenylene polymethylene polyisocyanate composition (1) also includes a triisocyanate component in an amount such that the ratio of diisocyanate to triisocyanate is between 0.2 and 1.8, preferably between about 0.33 and about 1.8. Therefore, the actual triisocyanate content depends on the amount of diphenylmethane diisocyanate used in the polyphenylene polymethylene composition (1) utilizing the above-mentioned ratio. This amount is based on 100% by weight of the total polyisocyanate composition.
For clarity, given that the amount of diphenylmethane diisocyanate in the polyphenylene polymethylene polyisocyanate is 30% and the ratio of diisocyanate to triisocyanate is 1.5, the amount of triisocyanate to be added to the polyphenylene polymethylene polyisocyanate composition is 20% by weight based on 100% by weight of the total composition. As used herein, the term "triisocyanate" means all isomers of 3-ring oligomers of polyphenylene polymethylene polyisocyanates containing three phenyl groups, two methyl groups and three isocyanate groups (i.e., n ═ 1 in formula I). The seven possible isomers of triisocyanates are described in John Wiley & Sons Inc. published Henri Ulrich "chemistry and technology of isocyanates", page 388 (1996).
The remainder of the polyphenylene polymethylene polyisocyanate composition includes higher homologues of polyphenylene polymethylene polyisocyanate. Higher homologues encompass all greater than three, i.e., tetraisocyanates, heptaisocyanates, hexaisocyanates, and the like (i.e., n > 1 in Structure 1). Suitable higher homologs are described in "Polyurethanes Book" by George Woods, published by John Wiley & Sons publishers (1987). The higher homologues may be included in the polyphenylene polymethylene polyisocyanate composition in an amount of 100% by weight of the total composition, generally from about 10 to about 77, preferably from about 19 to about 69%.
The higher homologues component (c) may further comprise higher functional isocyanate groups modified with a variety of groups including ester groups, urea groups, biuret groups, allophanate groups, carbodiimide groups, isocyanurate groups, uretdione groups (uretdione groups), and urethane groups. These modified isocyanate groups and methods for their production are known in the art.
The polyphenylene polymethylene polyisocyanate composition (1) is used in an amount of about 35 to about 70 of the total reaction system.
The polyphenylene polymethylene polyisocyanate composition (1) can be prepared by a method known to those skilled in the art. Suitable methods are disclosed in, for example, John Wiley & Sons Inc. (1996), Ulrich, "chemistry and technology of isocyanates". Generally, polyphenylene polymethylene polyisocyanate compositions are prepared by the reaction of aniline with formaldehyde under acidic conditions to form an amine. The resulting material is then phosgenated and thermally cracked to a mixture of isocyanate homologs. The amounts of diphenylmethane diisocyanate, triisocyanate and higher homologues in the composition may be manipulated by adjusting the aniline to formaldehyde ratio and/or the reaction conditions. For example, a higher aniline to formaldehyde ratio results in a relatively lower yield of a composition containing higher amounts of the diphenylmethane diamine and triamine components, and higher homolog components. Thus, phosgenation and thermal cracking of the resulting polyphenylene polymethylene polyamines yields higher amounts of diphenylmethane diisocyanate and triisocyanate, and lower amounts of higher isocyanate homologues. Further, the composition containing the polyphenylene polymethylene polyisocyanate component can also separate diphenylmethane diisocyanate along various isocyanate-modified reaction paths by fractional distillation control.
The reactive isocyanate composition (2) used in the present invention comprises any one known to those skilled in the art to be useful for preparing rigid polyurethane foams. Examples of suitable reactive isocyanate compositions having a plurality of isocyanate-reactive groups include polyether polyols, polyester polyols, and mixtures thereof having an average hydroxyl number of from about 20 to about 1000, preferably from about 50 to 700 KOH/gram, and a hydroxyl functionality of from about 2 to about 8, and preferably from about 2 to about 6. Other isocyanate-reactive materials useful in the present invention include hydrogen-capped polythioethers, polyamides, polyesteramides, polycarbonates, polyacetals, polyolefins, polysiloxanes, and polymer polyols.
Suitable polyether polyols comprise the reaction product of an alkylene oxide, such as ethylene oxide and/or propylene oxide, with an initiator containing from 2 to 8 active hydrogen atoms per molecule. Suitable initiators include polyhydric alcohols such as diethylene glycol, glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol, methylglucoside, mannitol, and sucrose; polyamines such as ethylenediamine, tolylenediamine, diaminodiphenylmethane and polymethylenepolyphenylene polyamines; aminoalcohols, such as ethanolamine and diethanolamine, and mixtures thereof. Preferred initiators include polyols and polyamines.
Suitable polyester polyols include those prepared by reacting a carboxylic acid and/or derivative thereof or a polycarboxylic anhydride with a polyhydric alcohol. The polycarboxylic acids may be any of the known aliphatic, alicyclic, aromatic, and/or heterocyclic polycarboxylic acids, and may be substituted (e.g., with halogen atoms) and/or unsaturated. 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, 1, 2, 4, 5-pyromellitic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, nadic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, and di-and tri-polymerized fatty acids, such as those oleic acid which can be mixed with monomeric fatty acids. Simple esters of polycarboxylic acids, such as dimethyl terephthalate, bis-glycol terephthalate, and extracts thereof, may also be used. While the aromatic polyester polyols can be prepared from the substantially pure reactant materials listed above, more complex components such as side draw, waste or scrap residues from the preparation of phthalic acid, phthalic anhydride, terephthalic acid, dimethyl terephthalate, polyethylene terephthalate, and the like can be used.
Suitable polyols for the preparation of polyester polyols may be aliphatic, cycloaliphatic, aromatic or heterocyclic. The polyols may optionally contain substituents that are inert in the reaction, such as chlorine and bromine substituents, and/or may be unsaturated. Suitable aminoalcohols such as monoethanolamine, diethanolamine and the like may also be used. Examples of suitable polyols include ethylene glycol, propylene glycol, polyoxyalkylene glycols (such as diethylene glycol, polyethylene glycol, dipropylene glycol and polypropylene glycol), glycerol and trimethylolpropane.
The reactive isocyanate species are used in amounts of about 20% to about 70%, and preferably about 30% to about 60%, of the total reaction system.
The process may also comprise reacting the polyphenylene polymethylene polyisocyanate composition (1) and the reactive isocyanate composition (2) with one or more fluorinated hydrocarbon or hydrocarbon blowing agents which are volatile under the foam forming conditions. The fluorocarbon blowing agents used in the present invention include: 1, 1, 1, 3, 3-pentafluoropropane (HFC 245 fa); 1, 1, 1, 3, 3-pentafluorobutane (HFC365 mfc); 1, 1, 1, 4, 4, 4-heptafluorobutane (HFC 356 mff); 1, 1-difluoroethane (HFC152 a); 1, 1, 1, 2-tetrafluoroethane (HFC 134 a); and mixtures thereof. Preferred fluorinated hydrocarbons include 1, 1, 1, 3, 3-pentafluoropropane; 1, 1, 1, 3, 3-pentafluorobutane, and 1, 1, 12-tetrafluoroethane. Suitable hydrocarbons include butane, isobutane, isopentane, n-pentane, cyclopentane, 1-pentene, n-hexane, isohexane, 1-hexane, n-heptane, isoheptane and mixtures thereof. Preferred hydrocarbon blowing agents are isopentane, n-pentane, cyclopentane and mixtures thereof. The most preferred hydrocarbon blowing agent for use in the present invention is a mixture of isopentane and n-pentane in a ratio of 80: 20 to 99: 1 parts by weight.
The fluorohydrocarbon blowing agent should be used in an amount of about 2% to about 20%, and preferably about 4 to about 15%, of the total reaction system.
The hydrocarbon blowing agent should be used in an amount of about 2% to about 20%, and preferably about 4 to about 15%, of the total reaction system.
Other physical blowing agents may also be used in the process of the present invention in combination with the hydrocarbon blowing agent. Suitable blowing agents include 1, 1, 1, 3, 3-pentafluoropropane (HFC-245fa), 1, 1, 1, 2-tetrafluoroethane (HFC-134a), 1, 1-difluoroethane (HFC-152a), difluoromethane (HFC-32), chlorodifluoromethane (HCFC-22), and 2-chloropropane. When used, these blowing agents may be mixed in the reactive isocyanate component, the isocyanate component, and/or as a split stream of the reaction system.
Volatile non-fluorinated hydrocarbons such as 2-chloropropane, isopentane, cyclopentane can also be used in the process of the invention in combination with fluorinated hydrocarbon blowing agents. When used, the blowing agent may be mixed in the reactive isocyanate component, the isocyanate component, and/or as a split stream of the reaction system.
The process may further optionally comprise reacting the polyphenylene polymethylene polyisocyanate, the reactive isocyanate composition and the fluorocarbon or hydrocarbon blowing agent in the presence of water in an amount of from 0.1% to 5%, preferably from about 0.2% to about 4%, of the total reaction system. The water reacts to produce carbon dioxide as an additional blowing agent. Other compounds that release carbon dioxide may be used instead of or in addition to water. These compounds comprise carboxylic acids or cyclic amines.
The reaction system may further comprise one or more auxiliaries or additives as desired for particular purposes. Suitable auxiliaries or additives include crosslinking agents such as triethanolamine or glycerol; foam stabilizers or surfactants such as siloxane-oxyalkylene copolymers, and oxyethylene-oxyalkylene copolymers; catalysts such as tertiary amines (e.g., dimethylcyclohexylamine, pentamethyldiethylenetriamine, 2, 4, 6-tris (dimethylaminomethyl) phenol, and triethyldiamine), organometallic compounds (e.g., potassium octoate, potassium acetate, dibutyltin dilaurate), quaternary ammonium salts (e.g., 2-hydroxypropyl trimethylammonium formate), and N-substituted triazines (N, N', N "-dimethylaminopropyl hexahydrotriazine); flame retardants such as organic phosphorus compounds, for example organic phosphates, phosphites, phosphonates, polyphosphates, polyphosphonates, ammonium polyphosphates (for example triethyl phosphate, diethyl ethyl phosphonate, tris (2-chloropropyl) -phosphate) and halogenated compounds (for example tetrabromophthalate, chlorinated paraffins); viscosity reducers such as propylene carbonate (propylene carbonate) and 1-methyl-2-pyrrolidone; infrared light-screening agents such as carbon black, titanium dioxide and metal flakes; compounds that reduce cell size, such as inert, insoluble fluorinated compounds and perfluorinated compounds; reinforcing agents such as glass fiber and ground foam waste; mold release agents such as zinc stearate; antioxidants such as butylated hydroxytoluene; and pigments such as azo/azide dyes and phthalocyanine. These adjuvants or additives are generally used in amounts of about 0.1% to about 20%, preferably about 0.3% to about 15%, and most preferably about 0.5% to about 10% by weight of the total foam formulation.
In the process for producing rigid polyurethane foams of the present invention, the known one-shot, prepolymer or semi-prepolymer techniques may be used, accompanied by a general mixing method such as shaking mixing. Rigid foams may be formed in sheet form, molded, cavity filled, blown foam, foam expanded, or laminated with other materials such as paper, metal, plastic, or wood. See, for example, Interscience Press, New York, polyurethane chemistry and technology by Saunders and Frisch, second division (1962), which is incorporated herein by reference for various methods of polyurethane formation.
The present invention further comprises rigid polyurethane foams made by the process disclosed above.
The invention will now be illustrated with reference to the following specific, non-limiting examples.
Examples
Unless otherwise indicated, all temperatures in the examples described below are in degrees Celsius and all amounts of the formulation components are in parts by weight.
The following materials are used or referred to in the examples.
StepanpolPS-2352 is an aromatic polyester polyol available from Stepan co, which includes a phthalic anhydride/diol based polyol having a hydroxyl number of 240 KOH/gram and a viscosity of 3,000cPs at 25 ℃.
TCPP is tris (. beta. -chloropropyl) phosphate available from Great Lakes chemical company.
Pelron9540A is potassium octoate in diethylene glycol from Pelron Corp.
Polycat8 is dimethylcyclohexylamine available from Air Products Corp.
TegostabB8466 is a silicone surfactant available from Goldschmidt.
The Borger Isopentane was an Isopentane product containing 97.5% Isopentane and 2.5% n-pentane, available from Phillips oil.
Hydrofluorocarbon HFC245fa (compressed) was purchased from AlliedSignal.
Polyisocyanate A contained 32% diphenylmethane diisocyanate, the ratio of diisocyanate to triisocyanate was 1.2 (triisocyanate was used in an amount of 26.7%); and 41.3% higher homologues. The diphenylmethane diisocyanate content of isocyanate B was 44%; the ratio of diisocyanate to triisocyanate was 1.8 (24.4% triphenyldimethane triisocyanate); and 31.6% higher homologues. Isocyanates A and B had an NCO content of 31%.
Example 1
The polyol blend was prepared by combining 100 parts of Stepanpol PS2352 with 14 parts of TCPP, 3 parts of Pelron 9540A. 0.6 part of Polycat 8, 2.65 parts of TegostabB8466 and 1.3 parts of water are mixed at room temperature in a high-speed mixer.
Rigid foams were prepared from the formulations listed in table 1 below. The polyol blend was added to the "B side" barrel of an Edge-rolls high pressure vibratory mixing disperser. An appropriate amount of isopentane (based on the composition listed in table 1) was added to the "B side" and vigorously stirred using an air stirrer attached to a drum. The isocyanate was added to the "side a" bucket attached to the dispenser.
The machine parameters were set as follows:
side A temperature (. degree.F.) 70
Side B temperature (. degree.F.) 70
Mixed pressure (psig) 2,000
Side A Pump rpm 70
B-side Pump rpm adjustment to obtain the values as in Table 1
Appropriate weight ratio of isocyanate
Feed rate (g/s) 180
The foaming components were poured from a dispenser into a number 10 Lily cup and the reactivity was measured on free application (freeuse) foam.
Structural properties were measured on core samples taken from a 7 "x 15" foam made by injecting the foam components into an appropriate cardboard box.
Foam core density was measured according to ASTM D1622. High temperature dimensional stability was measured according to ATMD 2126. Compressive strengthThe foam rise direction was measured parallel and perpendicular according to ASTM D1621 method A. Thermal properties of the foam were measured according to ASTM C5l8 on core foam taken from a 2 "by 14" block. The flammability performance was tested according to ASTM D3014 to measure Butler Chimney weight residue. TABLE 1
| Foam #1 | Foam #2 | Foam #3 | Foam #4 | |
| "B-side" | ||||
| Polyol blends | 34.8 | 34.8 | 34.5 | 34.5 |
| Isopentane | 6.2 | 6.2 | 6.6 | 6.6 |
| "A-side" | ||||
| Isocyanate A | 59 | - | 58.9 | - |
| Isocyanate B | - | 59 | - | 58.9 |
| Isopentane | ||||
| Reactivity: | ||||
| emulsification time, second | 4 | 5 | 6 | 5 |
| Gel time, second | 24 | 24 | 24 | 26 |
| Tack free time in seconds | 42 | 43 | 62 | 51 |
| The properties of the foam plastic are as follows: | ||||
| core Density, pcf | 1.9 | 1.9 | 1.75 | 1.75 |
| Structural properties: | ||||
| dimensional stability,% linear change | ||||
| 7 days at-25 DEG C | -1 | -2.9 | -1.9 | -3.6 |
| 7 days/amb at 93 ℃ | 2 | 2.6 | 2.7 | 3.4 |
| 70 ℃/97% RH for 7 days | 2.2 | 3.4 | 3.5 | 3.6 |
| Compressive strength, psi | ||||
| Parallel to the rise | 39.4 | 34.3 | 37.6 | 33.3 |
| Perpendicular to the rise | 12.3 | 8.8 | 11.3 | 11.1 |
| Thermal properties: k-factor of BTU, in/ft2.hr.°F | ||||
| Initiation of | 0.15 | 0.15 | 0.15 | 0.15 |
| At 140 ℃ F. for 8 weeksRear end | 0.17 | 0.18 | 0.18 | 0.18 |
| Combustion performance | ||||
| Residual wt% of Butler smoke window | 93 | 88 | 88 | 86 |
As is clear from the data set forth in Table 1, foam 1 made according to the present invention using isocyanate A provides a rigid polyurethane foam superior in structural, thermal and flammability performance properties to foam 2. Foam 2 is prepared with isocyanate B and is outside the scope of the present invention.
Foams 3 and 4 are prepared at the density of typical CFC-blown foams. As shown in Table 1, foam 3 prepared according to the invention using isocyanate A has superior structural, thermal and flame performance properties compared to foam 4. Foam 4 is prepared with isocyanate B and is outside the scope of the present invention.
Further, foam 3 (according to the invention) can be compared with foam 2. The dimensional stability and Butler Chimney weight residual were almost identical for both foams. Furthermore, foam 3 has an initial and aged K factor and compressive strength superior to that of foam 2. Thus, the data demonstrate that foams made using the polyisocyanate composition of the present invention (isocyanate A) have better properties at lower densities than foams made with conventional isocyanates at higher densities.
Example 2
The polyol blend is prepared by mixing 100 parts Stepanpol PS2352 with 4.5 parts Pelron 9540A at room temperature in a high speed blender. 1.0 part of Polycat 8, 2.0 parts of Tegostab B8466 and 0.3 part of water.
Rigid foams were prepared from the formulations listed in table 1 below. The polyol blend was added to the "B-side" barrel of an Edge-sweet high pressure vibratory mixing dispenser. An appropriate amount of HFC245fa (based on the composition listed in table 1) was added on the "B side" and stirred vigorously using an air stirrer attached to a drum. The isocyanate was added to the "side a" bucket attached to the dispenser.
The machine parameters were set as follows:
side A temperature (. degree.F.) 70
Side B temperature (. degree.F.) 70
Mixed pressure (psig) 2,000
Side A Pump rpm 70
B-side Pump rpm adjustment to obtain the values as in Table 1
Appropriate weight ratio of isocyanate
Feed rate (g/s) 200
The foaming components were injected from the dispenser into a number 10 Lily cup and the reactivity was measured on a free-rise foam.
Structural properties were measured on core samples taken from a 7 "x 15" foam made by injecting the foam components into an appropriate cardboard box.
Foam core density was measured according to ASTM D1622. High temperature dimensional stability was measured according to ATMD 2126. Compressive strength was measured parallel and perpendicular to the rise direction of the foam according to ASTM D1621 method A. Thermal properties of the foam were measured according to ASTM DC518 on core foam taken from 2 "by 14" squares. The flammability performance was tested according to ASTM D3014 to measure Butler Chimney weight residue. TABLE 1
| Foam #1 | Foam #2 | Foam #3 | Foam #4 | |
| "B-side" | ||||
| Polyol blends | 34.4 | 34.4 | 34.0 | 34.0 |
| HFC245fa | 13.7 | 13.7 | 14.6 | 14.6 |
| "A-side" | ||||
| Isocyanate A | 51.9 | - | 58.4 | - |
| Isocyanate B | - | 51.9 | - | 58.4 |
| Reactivity: | ||||
| emulsification time, second | 3 | 3 | 3 | 3 |
| Gel time, second | 11 | 11 | 11 | 11 |
| Tack free time in seconds | 15 | 14 | 13 | 13 |
| The properties of the foam plastic are as follows: | ||||
| core Density, pcf | 2.14 | 2.14 | 2.02 | 2.02 |
| Structural properties: | ||||
| dimensional stability,% linear change | ||||
| 7 days at-25 DEG C | -1.1 | -3.6 | -1.3 | -5.2 |
| 7 days/amb at 93 ℃ | 2.3 | 4.4 | 3.6 | 5 |
| Compressive strength, psi | ||||
| Parallel to the rise | 47.9 | 34 | 40.2 | 32 |
| Perpendicular to the rise | 21.3 | 11.5 | 13.9 | 10.8 |
| Thermal properties: k-factor of BTU, in/ft2.hr.°F | ||||
| Initiation of | 0.128 | 0.132 | 0.129 | 0.130 |
As is clear from the data set forth in Table 1, foam 1 made according to the present invention using isocyanate A provides a rigid polyurethane foam superior in structural, thermal and flammability performance properties to foam 2. Foam 2 is prepared with isocyanate B and is outside the scope of the present invention.
Foams 3 and 4 were prepared at the densities typical for CFC-blown foams. As shown in Table 1, foam 3 prepared according to the invention using isocyanate A has superior properties of structural, thermal and flame properties compared to foam 4. Foam 4 is prepared with isocyanate B and is outside the scope of the present invention.
Further, foam 3 (according to the invention) can be compared with foam 2. The dimensional stability values are almost identical for both foams. Furthermore, foam 3 has an initial and aged K factor and compressive strength superior to that of foam 2. Accordingly, the data demonstrate that foams prepared using the polyisocyanate composition of the present invention (isocyanate A) have better properties at lower densities than foams prepared with conventional isocyanates at higher densities.
Claims (14)
1. A polyisocyanate composition comprising:
(a) about 15 to about 42 weight percent of diphenylmethane diisocyanate;
(b) a tricyclic oligomer of polyphenylene polymethylene polyisocyanate in an amount such that the ratio of (a) to (b) is equal to about 0.2 to about 1.8; and
(c) higher homologues of polyphenylene polymethylene polyisocyanates.
2. The composition of claim 1 wherein the polyphenylene isTricyclic oligomers of polymethylene polyisocyanate have the formula: wherein n is 1.
3. The composition of claim 1 wherein the higher homologues of polyphenylene polymethylene polyisocyanate have the formula:wherein n is greater than 1.
4. The composition of claim 1 wherein the amount of diphenylmethane diisocyanate used is equal to from about 20 to about 40%.
5. The composition of claim 1 wherein the amount of diphenylmethane diisocyanate used is equal to from about 24 to about 38%.
6. A process for preparing a polyurethane foam comprising reacting the polyisocyanate composition of claim 1 with a reactive isocyanate composition in the presence of a fluorocarbon blowing agent.
7. The method of claim 6 wherein the amount of hydrofluorocarbon used is equal to about 2 to about 20 weight percent of the composition.
8. The method of claim 6 wherein the amount of hydrofluorocarbon used is equal to about 4 to about 15 weight percent of the composition.
9. The method of claim 7 wherein the hydrofluorocarbon is selected from the group consisting of 1, 1, 1, 3, 3-pentafluoropropane (HFC 245 fa); 1, 1, 1, 3, 3-pentafluorobutane (HFC365 mfc); 1, 1, 1, 4, 4, 4-heptafluorobutane (HFC 356 mff); 1, 1-difluoroethane (HFC152 a); 1, 1, 1, 2-tetrafluoroethane (HFC 134a) and mixtures thereof.
10. A process for preparing a polyurethane foam comprising reacting the polyisocyanate composition of claim 1 with a reactive isocyanate composition in the presence of a hydrocarbon blowing agent.
11. The method of claim 10 wherein the hydrocarbon is present in an amount equivalent to about 2 to about 20 weight percent of the composition.
12. The method of claim 10 wherein the hydrocarbon is present in an amount equivalent to about 4 to about 15 weight percent of the composition.
13. The method of claim 10, wherein the hydrocarbon is selected from the group consisting of butane, isobutane, isopentane, n-pentane, cyclopentane, 1-pentene, n-hexane, isohexane, 1-hexane, n-heptane, isoheptane, and mixtures thereof.
14. The process of claim 10 wherein the hydrocarbon is a blend of isopentane and n-pentane in a ratio of 80: 20 to 99: 1 parts by weight.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60/050,952 | 1997-06-13 | ||
| US60/050,906 | 1997-06-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| HK1029129A true HK1029129A (en) | 2001-03-23 |
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