Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2002-02-14
2003-11-11
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...
C510S408000, C510S412000, C510S415000, C521S131000, C521S155000, C521S170000, C521S172000, C521S173000, C521S174000
Reexamination Certificate
active
06646020
ABSTRACT:
FIELD OF THE INVENTION
The herein disclosed invention finds applicability in the field of plastic foam manufacture and more particularly in the field of plastic blowing agents. More particularly, the invention herein disclosed is directed to producing blowing agents with reduced flammability.
BACKGROUND OF THE INVENTION
Closed-cell polyurethane foams are widely used for insulation purposes in building construction and in the manufacture of energy efficient electrical appliances. In the construction industry, polyurethane (polyisocyanurate) board stock is used in roofing and siding for its insulation and load-carrying capabilities. Poured and sprayed polyurethane foams are also used in construction. Sprayed polyurethane foams are widely used for insulating large structures such as storage tanks, etc. Pour-in-place polyurethane foams are used, for example, in appliances such as refrigerators and freezers plus they are used in making refrigerated trucks and railcars. All of these polyurethane foams require expansion agents (blowing agents) for their manufacture. Insulating foams depend on the use of halocarbon blowing agents, not only to foam the polymer, but primarily for their low vapor thermal conductivity, a very important characteristic for insulation value. Historically, polyurethane foams are made with CFC-11(trichlorofluoromethane) as the primary blowing agent.
The art is continually seeking new fluorocarbon based azeotropic mixtures or azeotrope-like mixtures which offer alternatives for new and special applications for industrial cleaning, blowing agent and aerosol applications. Currently, fluorocarbon-based azeotrope-like mixtures are of particular interest because they are considered to be stratospherically safe substitutes for presently used fully halogenated chlorofluorocarbons (i.e., e.g., CFC-11, CFC-12, CFC-113). The latter have been implicated in causing environmental problems associated with the depletion of the earth's protective ozone layer.
Accordingly, it is an object of the present invention to provide novel environmentally acceptable azeotrope-like compositions which are useful in a variety of applications including industrial cleaning, blowing agent and aerosol applications. More particularly, the herein disclosed invention is directed to formulations wherein the flammability of 2-chloropropane (IPC) is reduced so that it can be used in blowing agent applications.
The following U.S. patents are of interest as showing various blowing agent compositions, but do not disclose the inventive compositions disclosed herein.
Inventors
U.S. Pat. Nos.
Merchant
5,066,418
Merchant
5,116,525
LeBuc
5,149,473
Swan (U.S. Pat. No. 5,213,707) teaches an azeotrope-like mixture of 2-chloropropane and a chlorofluorohydrocarbon, as seen in col. 3, lines 40-55; however, this reference does not teach 2-chloropropane with a hydrofluorohydrocarbon per se. The composition of Swan always contains a chlorofluorohydrocarbon.
Ashida (U.S. Pat. No. 4,898,893) teaches isopropyl chloride as a blowing agent together with liquid chlorofluorocarbon as a blowing agent. This reference is deficient in not disclosing an azeotropic mixture with reduced flammability and specifically does not disclose fluorocarbons.
Monstrey (U.S. Pat. No. 5,064,872) discloses 2-chloropropane and chlorofluorohydrocarbons. This reference does not recognize the fact of no flash point or reduced combustibility of the herein disclosed invention. Nor is the recognition of azeotropic mixtures recognized.
OBJECT OF THE INVENTION
A main object of the invention is to formulate non-flammable blowing agents.
A most significant object of this invention is to produce blowing agents containing 2-chloropropane which have reduced flammability.
A further object of this invention is the formulation of azeotropic mixtures which are useful in the formulation of blowing agents.
These and other objects of the present invention will become apparent from a reading of the following specification taken in conjunction with the enclosed drawings.
BRIEF SUMMARY OF THE INVENTION
The herein disclosed invention is directed to formulations containing 2-chloropropane wherein the flammability of the 2-chloropropane has been reduced.
DESCRIPTION
The herein disclosed invention relates to a polyisocyanurate foam or with polyurethane modified polyisocyanurate foam, which show very good fire-resistant and thermo-insulating properties.
The presently known polyisocyanurate foams and polyurethane modified polyisocyanurate foams, which are prepared by using a physical blowing agent, consisting of hydrochlorofluorocarbons, distinguish themselves as an insulation material by their good and lasting insulation coefficient, their good dimensional stability and their excellent fire behavior. It is accepted that the use of these hydrochlorofluorocarbon compounds as blowing agents, offer good fire-resistance and contribute to the excellent fire behavior of the foams concerned. As is well-known, such blowing agents show important drawbacks and nowadays it is accepted that they, in part, are responsible for the destruction of the ozone layer in the stratosphere and would, at the same time, increase the greenhouse effect on earth. Accordingly, the herein disclosed invention is intended to remedy these important drawbacks. A polyisocyanurate foam or polyurethane modified polyisocyanurate foam is proposed which shows the above mentioned beneficial properties, especially the good insulation coefficient and the excellent fire behavior, but not the disadvantages of the ones which are involved with the use of hydrochlorofluorocarbons, such as HCFC-141b. To this end, the polyisocyanurate foam or the polyurethane modified polyisocyanurate foam describes, according to the invention, closed cells wherein 2-chloropropane, in combination with hydrofluorocarbons and, if desired, pentanes are enclosed.
The invention relates also to a method for preparing the foam concerned, wherein a physical blowing agent is used for obtaining the foam structure, which method is characterized in that a 2-chloropropane containing physical blowing agent is applied. In a particular embodiment of the invention, use is made of a physical blowing agent consisting of at least 5% isopropyl chloride (2-chloropropane). 2-Chloropropane (isopropyl chloride) is a clear colorless liquid and has a flash point of −32° C.
For the manufacture of these polyisocyanurate foams, use is essentially made of the mutual trimerization and other reactions of polyisocyanates, effected by typical catalysts. These polyisocyanurates are known for their exceptional fire behavior.
Since pure polyisocyanurate foams often have inadequate physical properties, they are in practice usually mixed with polyurethanes based on the same isocyanate and certain polyols, so that a reaction starts which develops synchronously with the trimerization. These foams are called polyurethane modified polyisocyanurates.
Besides the polyisocyanate, the polyols, the typical catalysts and the blowing agents, use is also made of foam stabilizers, flame extinguishing additives, etc.
The organic polyisocyanate compounds are of the R(NCO)
n
, wherein n>2 and R represents an aliphatic or aromatic group. Preferably, use is made of diisocyanates or polyisocyanates comprising on average 2 to 4 isocyanate groups per molecule. A typical example thereof comprises diphenylmethane-4,4″-diisocyanate (MDI) and mixtures of the latter with its polymeric forms (“crude”MDI), which are usually applied in the manufacture of rigid polyurethane foam and polyisocyanurate foam.
Under the influence of specific catalysts, such isocyanates can mutually react by dimerization and trimerization to form polyisocyanurate. In order to modify such polyisocyanurates with polyurethanes, each molecule with active hydrogen groups. E.g., R—OH, R13 COOH, R—SH, R
2
—NH, R—NH
2
, R—SH, . . . is in principle appropriate for use as reactive substrate. Preferable substrates include polyalcohols of the polyetherpolyol or polyesterpolyol type or mixtures thereof. A molecular weight
Mainz Eric L.
Nyberg Janice M.
Armstrong Westerman & Hattori, LLP
Cooney Jr. John M.
Vulcan Chemicals a division of Vulcan Materials Company
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