Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2001-09-04
2002-07-02
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C252S182240, C252S182270, C510S412000, C510S415000, C521S155000, C521S170000, C521S174000
Reexamination Certificate
active
06414046
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to polyurethane and polyisocyanurate closed-cell foams. More particularly, the invention relates to polyurethane and polyisocyanurate closed-cell foams prepared with a blowing agent comprising 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124) and 1,1-dichloro-1-fluoroethane (HCFC-141b). Foams prepared with the blowing agent of the invention possess improved cell nucleation and thermal performance.
BACKGROUND OF THE INVENTION
The class of foams known as low density rigid polyurethane or polyisocyanurate foam has utility in a wide variety of insulation applications including roofing systems, building panels, refrigerators and freezers. A critical factor in the large-scale commercial acceptance of rigid polyurethane foams in the building insulation industry has been their ability to provide a good balance of properties. Rigid polyurethane and polyisocyanurate foams are known to provide outstanding thermal insulation, excellent fire properties and superior structural properties at reasonably low densities.
The methods of producing polyurethane and polyisocyanurate foams are generally known and consist in general of the reaction of an organic polyisocyanurate (including diisocyanate) and a polyol or mixture of polyols in the presence of a volatile blowing agent, which is caused to vaporize by the heat liberated during the reaction of isocyanate and polyol. This reaction can be enhanced through the use of amine and/or other catalysts as well as surfactants. The catalysts ensure adequate curing of the foam, while the surfactants regulate and control cell size. Flame-retardants are traditionally added to rigid polyurethane or polyisocyanurate foam to reduce its flammability.
The foam industry has historically used liquid fluorocarbon blowing agents such as trichlorofluoromethane (CFC-11) and 1,1-dichloro-1-fluoroethane (HCFC-141b) because of their ease of use in processing conditions. Fluorocarbons act not only as blowing agents by virtue of their volatility, but also are encapsulated or entrained in the closed cell structure of the rigid foam and are the major contributor to the low thermal conductivity properties of rigid urethane foams.
The use of a fluorocarbon as the preferred commercial expansion or blowing agent in insulating foam applications is based in part on the resulting k-factor associated with the foam produced. K-factor is defined as the rate of transfer of heat energy by conduction through one square foot of one inch thick homogenous material in one hour where there is a difference of one degree Fahrenheit perpendicularly across the two surfaces of the material. Since the utility of closed-cell polyurethane-type foams is based, in part, upon their thermal insulation properties, it would be advantageous to identify materials that produce lower k-factor foams.
1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124) is a known blowing agent. It has now been discovered that the use of HCFC-124 as a co-blowing agent for 1,1-dichloro-1-fluoroethane HCFC-141b unexpectedly results in foams having superior thermal performance to foam produced with HCFC-141b. The results are unexpected since one would anticipate on the basis of vapor thermal conductivity that the addition of HCFC-124 to HCFC-141b systems would elevate the k-factor of the foam produced.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates to a blowing agent composition comprising 1,1-dichloro-1-fluoroethane and 1-chloro-1,2,2,2-tetrafluoroethane. The preferred compositions of the invention are reported in the Table below. The ranges reported in the table are in weight percent based on the total amount of blowing agent composition and are understood to be prefaced by “about”.
% HCFC-141b in blowing
% HCFC-124 in blowing
agent composition
agent composition
50-99
1-50
60-99
1-40
70-99
1-30
80-99
1-20
90-99
1-10
In one embodiment, the invention provides a method of preparing foam compositions based on isocyanate which comprises reacting and foaming a mixture of ingredients which will react to form polyurethane or polyisocyanurate foams in the presence of the blowing agent composition of the invention.
In another embodiment, the invention provides a closed cell foam prepared from a polymer foam formulation containing the blowing agent composition of the invention.
In yet another embodiment, the invention provides a polyol premix composition comprising a polyol and the blowing agent composition of the invention.
With respect to the preparation of rigid or flexible polyurethane or polyisocyanurate foams using hydrocarbons as the blowing agent, any of the methods well known in the art can be employed. See Saunders and Frisch, Volumes I and II Polyurethanes Chemistry and Technology (1962). In general, polyurethane or polyisocyanurate foams are prepared by combining an isocyanate, a polyol or mixture of polyols, a blowing agent or mixture of blowing agents, and other materials such as catalysts, surfactants, and optionally, flame retardants, colorants, or other additives.
It is convenient in many applications to provide the components for polyurethane or polyisocyanurate foams in pre-blended foam formulations. Most typically, the foam formulation is pre-blended into two components. The isocyanate or polyisocyanate composition comprises the first component, commonly referred to as the “A” component. The polyol or polyol mixture, surfactant, catalysts, blowing agents, flame retardant, and other isocyanate reactive components comprise the second component, commonly referred to as the “B” component. While the surfactant, catalyst(s) and blowing agent are usually placed on the polyol side, they may be placed on either side, or partly on one side and partly on the other side. Accordingly, polyurethane or polyisocyanurate foams are readily prepared by bringing together the A and B side components either by hand mix, for small preparations, or preferably machine mix techniques to form blocks, slabs, laminates, pour-in-place panels and other items, spray applied foams, froths, and the like. Optionally, other ingredients such as fire retardant, colorants, auxiliary blowing agents, water, and even other polyols can be added as a third stream to the mix head or reaction site. Most conveniently, however, they are all incorporated into one B component.
Any organic polyisocyanate can be employed in polyurethane or polyisocyanurate foam synthesis inclusive of aliphatic and aromatic polyisocyanates. Preferred, as a class is the aromatic polyisocyanates. Preferred polyisocyanates for rigid polyurethane or polyisocyanurate foam synthesis are the polymethylene polyphenyl isocyanates, particularly the mixtures containing from about 30 to about 85 percent by weight of methylenebis(phenyl isocyanate) with the remainder of the mixture comprising the polymethylene polyphenyl polyisocyanates of functionality higher than 2. Preferred polyisocyanates for flexible polyurethane foam synthesis are toluene diisocyanates including, without limitation, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and mixtures thereof.
Typical polyols used in the manufacture of rigid polyurethane foams include, but are not limited to, aromatic amino-based polyether polyols such as those based on mixtures of 2,4- and 2,6-toluenediamine condensed with ethylene oxide and/or propylene oxide. These polyols find utility in pour-in-place molded foams. Another example is aromatic alkylamino-based polyether polyols such as those based on ethoxylated and/or propoxylated aminoethylated nonylphenol derivatives. These polyols generally find utility in spray applied polyurethane foams. Another example is sucrose-based polyols such as those based on sucrose derivatives and/or mixtures of sucrose and glycerine derivatives condensed with ethylene oxide and/or propylene oxide. These polyols generally find utility in pour-in-place molded foams.
Typical polyols used in the manufacture of flexible polyurethane foams include, but are not limited to, those based on glycerol, ethylene glycol, trimethylolpropane, ethylene diamine, pentaerythritol, and
Bement Leslie Bruce
Bogdan Mary Charlotte
Logsdon Peter Brian
Williams David John
Cooney Jr. John M.
Honeywell International , Inc.
Szuch Colleen
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