Compositions – Compositions containing a single chemical reactant or plural... – Organic reactant
Reexamination Certificate
2000-08-03
2002-02-19
Cooney, Jr., John M. (Department: 1711)
Compositions
Compositions containing a single chemical reactant or plural...
Organic reactant
C252S182250, C252S182260, C252S182270
Reexamination Certificate
active
06348161
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to dimensionally stable, rigid polyurethane/polyisocyanurate foams and to polyol blends used to make such foams. Particularly, the present invention relates to polyol blends containing a polyether polyol blend, a polyester polyol, and hydrocarbon blowing agent.
BACKGROUND OF THE INVENTION
Hydrocarbons are being employed in greater numbers as viable alternative blowing agents in the manufacture of rigid polyurethane or polyisocyanurate foams.
Due to the non-polar hydrophobic characteristics of hydrocarbons, they are only partially soluble in many polyols used to manufacture rigid polyurethane or polyisocyanurate foams. As a result of the poor solubility of hydrocarbon blowing agents, the blowing agent must usually be added to the polyol just prior to dispersing through a mix head. The limited shelf life of hydrocarbon-polyol mixtures has limited the ability of storing batches for later use.
Additional to the limited storage time for batches, is the potential limited process phase stability or limited resistance to separation into layers of different composition. If there is a phase separation during the process, often there may be non-uniform and uneven cell structures in the resultant polyurethane or polyisocyanurate foam. Such non-stable cell structure can lead to variations in the properties of a foam product, such as, the thermal conductivity which generally increases as a result of poor cell structure. Conversely, the R-factor, or insulative factor tends to decrease as a result of poor cell structure. Such a decrease in the R-factor would not be desirable in an application where the foam is to be used as an insulator, such as, for example, in a refrigerator door.
SUMMARY OF THE INVENTION
There is provided a phase stable polyol resin blend composition comprising a polyether polyol blend, a polyester polyol and a hydrocarbon blowing agent. The polyether polyol blend is present in an amount of at least 10 percent by weight of the polyol resin.
In one embodiment, the polyether polyol blend comprises a mixture of a toluene diamine and ethylene diamine co-initiated polyol having from 20 to 30 percent ethylene oxide and 70 to 80 percent propylene oxide, a sucrose and dipropylene glycol co-initiated propylene oxide polyol, and a polyethylene terephthalate initiated aromatic polyol blend having a functionality of between 2.3 and 3.0
In one embodiment, the polyester polyol utilized in the invention is a phthalic anhydride initiated polyester polyol having a hydroxyl number of at least 200 meq polyol/g KOH.
The hydrocarbon blowing agents used by the invention are C
4
-C
6
hydrocarbons or mixtures thereof. The pentanes are particularly preferred and are present in the polyol resin in amounts of from 20 to 30 parts by weight of the polyol resin.
In one embodiment, the method of the invention comprises providing a polyether polyol blend having at least three polyols comprising a toluene diamine and ethylene diamine co-initiated polyol, a sucrose and dipropylene glycol co-initiated polyol and a polyethylene terephthalate initiated aromatic polyol blend; providing a polyester polyol; providing a C
4
-C
6
hydrocarbon blowing agent; combining the polyether polyol blend, polyester polyol and blowing agent to form a polyol resin; providing a polyisocyanate component; providing a catalyst; and combining the polyol resin with the polyisocyanate component and catalyst to form a polyurethane foam.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
The phase stable polyol resin blend composition includes at least a polyether polyol blend, a polyester polyol and a hydrocarbon blowing agent.
The polyol resin blend composition is deemed to be phase stable when the blend composition has the capacity of retaining the hydrocarbon blowing agent in solution for a specified period of time; generally at least 24 hours. The determination as to the phase stability of the composition is measured by mixing the hydrocarbon blowing agent with the polyether polyol blend and polyester polyol in a clear container having a lid. The container is then agitated vigorously to fully mix the composition, and the container is allowed to stand undisturbed overnight. If there is no visible phase separation into distinct layers, or a cloudy appearance, then the composition is deemed to be phase stable.
Methods of forming polyoxyalkylene polyether polyols are well known, for example, by the base catalyzed addition of alkylene oxides to an initiator molecule containing reactive hydrogens such as a polyhydric alcohol. In one embodiment of the present invention, the initiator molecules are triols. Examples of such initiators include: glycerol; 1,1,1-trimethylolpropane; 1,1,1-trimethylolethane; 1,2,6-hexanetriol; pentaerythritol; and sorbitol. Other suitable initiators include both aliphatics and aromatics, such as ethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol. Also included within the term “polyhydric alcohol” are compounds derived from phenol such as 2,2-bis(4-hydroxyphenyl)propane, commonly known as Bisphenol A. The polyether polyols may be prepared by any known process such as, for example, the process disclosed by Wurtz in 1859,
Encyclopedia of Chemical Technology,
Vol. 7, pp. 257-262, Published by Interscience Publishers, Inc. (1951) or in U.S. Pat. No. 1,922,459.
Examples of useful alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, amylene oxide, mixtures thereof, tetrahydrofuran, alkylene oxide-tetrahydrofuran mixtures, epihalohydrins, and aralkylene styrene. The alkylene oxides are added onto the initiator molecule and chain propagation is carried out in the presence of catalysts by either anionic polymerization or by cationic polymerization.
The preferred catalysts are potassium hydroxide, sodium hydroxide, alcoholates of potassium hydroxide, alcoholates of sodium hydroxide, cesium catalysts, amines, Lewis acid catalysts, or double metal complex catalysts, all of which are known in the art.
The polyol resin blend composition of the present invention contains a polyether polyol blend, a polyester polyol, and a C
4
-C
6
hydrocarbon blowing agent. Other ingredients that may be included in the polyol resin blend composition are catalysts, surfactants, other blowing agents, flame retardants, fillers, stabilizers and other additives.
The polyether polyol blend useful in accordance with the present invention comprises at least a mixture of a diamine initiated polyol, a propylene oxide polyol and at least one polyethylene terephthalate (PET) initiated polyol.
The diamine initiated polyol is preferably a toluene diamine and ethylene diamine co-initiated polyol having from 20 to 30 percent ethylene oxide and 70 to 80 percent propylene oxide. The toluene diamine and ethylene diamine co-initiated polyol preferably has a nominal functionality of 4, with a hydroxyl number from 450 to 550 meq polyol/g KOH. Even more preferably the polyol has a hydroxyl number of 500 meq polyol /g KOH.
A particularly preferred diamine initiated polyol of the present invention includes Pluracol® 922, a toluene diamine and ethylene diamine co-initiated polyol commercially available from BASF Corporation (Mt. Olive, N.J.).
The propylene containing polyol is preferably a sucrose and dipropylene glycol co-initiated polyol. This polyol preferably only includes the initiators and propylene oxide.
The sucrose and dipropylene glycol co-initiated polyol preferably has a nominal functionality between 4 and 5 with a hydroxyl number from 350 to 450 meq polyol/g KOH. Even more preferably, the polyol has a hydroxyl number of 500 meq polyol/g KOH.
A particularly preferred propylene oxide polyol of the present invention includes Pluracol
200
975, a sucrose and dipropylene glycol co-initiated polyol commercially available from BASF Corporation (Mt. Olive, N.J.).
The PET initiated polyol of the polyether polyol blend preferably
Mullins James A.
Patterson Jimmy L.
Riley Robert E.
White, III Walter R.
BASF Corporation
Borrego Fernando A.
Cooney Jr. John M.
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