Polyol containing glycol adduct for use in producing rigid foam

Details Polyol containing glycol adduct for use in producing rigid foam Polyol containing glycol adduct for use in producing rigid foam

2003-01-16

2004-03-23

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, C252S182280, C252S182290, C521S131000, C521S173000

Reexamination Certificate

active

06710095

ABSTRACT:

BACKGROUND OF THE INVENTION
1) Field of the Invention
The invention relates to an isocyanate-reactive composition for use in the preparation of rigid polyisocyanurate and/or polyurethane foams. More particularly, the invention relates to an isocyanate-reactive composition which is readily miscible with hydrocarbon blowing agents. The isocyanate-reactive composition contains polyol with at least 5% by weight glycol adducts. Suitable glycol adducts are benzoate, naphthenate, toluate glycol adducts; substituted benzoate, naphthenate, toluate glycol adducts, or a mixture of these.
2) Prior Art
Known rigid polyurethane foams may be prepared by the reaction of a polyisocyanate, an isocyanate-reactive polyol, and a blowing agent in the presence of a catalyst. Polyisocyanurate foams, a variety of polyurethane in which some of the isocyanate components of the reaction mixture are catalyzed to react with themselves, creating strong isocyanurate linkages, can be formed with the polyurethane foams. A variety of polyols may be used for foam preparation, with the particular polyol chosen based on the desired results of the foam or compatibility with other reactants. Polyurethane and polyisocyanurate foams produced by traditional methods have employed chlorofluorocarbons such as trichlorofluoromethane (CFC-11) as the blowing agent. These chlorofluorocarbon compounds are volatized during the exothermic reaction of isocyanate with the polyester polyol. The expanding gas is entrapped within the foam reaction mixture, which polymerizes to form an insulating cellular structure.
Recent studies have shown that the halogen components of chlorofluorocarbon blowing agents, such as CFC-11, deplete ozone in the stratosphere. Hydrochlorofluorocarbons (HCFCs), such as dichlorofluoroethane (141b) and chlorodifluoromethane (HCFC-22), are partially halo-substituted hydrocarbons that have lower ozone depletion potential than the fully halogenated chlorofluorocarbons (CFCs) and have, accordingly, been used as alternative blowing agents for CFC-11 in foam production. But, ever increasing environmental regulation has placed severe burdens and costs upon the users of HCFCs as well as CFCs.
With the heavy regulation of CFCs and HCFCs there has been renewed interest in the use of simple hydrocarbons as blowing agents. Hydrocarbons, such as the isomeric forms of pentane, do not contain halogen components, and are therefore not expected to deplete stratospheric ozone. Hydrocarbon blowing agents have not been favored in the past because of their higher flammability and because of the higher thermal conductivity of the foam produced with the hydrocarbon blowing agents.
More importantly, from a production viewpoint, hydrocarbon blowing agents have limited miscibility with polyester polyols, particularly in the aromatic polyester polyols preferred for making polyurethane and polyisocyanurate insulating foams. Additionally, the low solubility of hydrocarbon blowing agents in polyols, particularly in aromatic polyester polyols, requires that the producer modify his conventional foaming equipment to process these materials. The prior art discloses a variety of materials and methods for compatibilizing blowing agents with a polyol mixture.
U.S. Pat. No. 4,444,920 to Brennan discloses the catalyzed reaction and subsequent transesterification of alkyl p-formylbenzoate from a dimethyl terephthalate (DMT) production process in order to compatibilize the described polyol mixture with a trichlorofluoromethane blowing agent. While Brennan indeed discloses that suitable blowing agents include pentane (as set forth in column 6, line 9), it is clear that Brennan never tested pentane and in fact the invention is based on CFC's. (This is particularly noted in column 4, lines 23-28.)
The Brennan patent reacted, as a preblend, an Eastman waste stream that included methyl p-formylbenzoate (MFB) over a metal alkoxide catalyst to increase the amount of DMT. In the waste stream, Example II (see table atop column 8) shows that after a reaction time of 26 hours the preblend crude waste stream contained 50% (mole percent) DMT, as well as 11% p-methyltoluate, and 14% methylbenzoate, such that they contained 25 mole percent of glycol adducts (11%+14%). In Examples II and III this preblend reaction mixture was reacted with a glycol residue to produce a noncommercial polyol. The mass balance for Examples II and III of Brennan are shown below in Table 1. (The density of methanol is taken to be 0.8 g/ml)
TABLE 1
Example II
Example III
g
g
Crude MFB
64
145
Methanol
200
456
Catalyst
7.3
12.4
Magnesol
7.9
15.4
Glycol residue
103.9
235.4
Overhead
−214
−418
Polyol/glycol
169.1
446.2
adduct
Glycol adducts,
16
36.25
25% crude
% glycol adducts in
9%
8%
polyol
In Examples II and III, the percent glycol adducts in the noncommercial polyol was 9 and 8% by weight. These noncommercial polyols were then mixed (diluted) with a commercial polyol-Thanex R-350-X to produce the commercial polyol of Brennan. The mass balance in Examples IVB and IVC for the commercial polyols of Brennan is given in Table 2 below. This indicates a final glycol adduct percentage of 2.8% and 2.4% by weight respectively, and it was these polyol/adducts that were blown with Freon® as set forth in Example IV of Brennan.
TABLE 2
Example IVB
Example IVC
g
g
Thanol
24.8
25.4
Polyol Ex 2
10.6
Polyol Ex 3
10.9
Total
35.4
36.3
Amount of glycol adducts
9%
8%
in Polyol (TABLE 1)
Wt. of glycol adducts
1.00
0.89
% glycol adducts
2.8%
2.4%
U.S. Pat. No. 4,720,571 to Trowell discloses a method of preparing a polyol with improved compatibility with CFC blowing agents by first reacting a mixture comprised of scrap polyethylene terephthalate, dimethyl terephthalate process residue and at least two glycols having a molecular weight higher than that of ethylene glycol, in the presence of an esterification/transesterification catalyst, and subsequently removing glycols from the reaction product.
U.S. Pat. No. 5,605,940 to Skowronski et al. discloses a polyol utilized in the creation of rigid polyurethane foams and polyisocyanurate foams having superior shrink resistance, strength, and long-term insulating ability. The disclosed polyol is, or contains, a hydroxy terminated polyester having an equivalent weight greater than about 350. The disclosed polyol is reacted with isocyanate with or without an additional glycol component. The preferred reactant stream for production of the described polyol contains phthalic acid or ester residues which may be derived from the production of dimethyl terephthalate, scrap polyalkylene terephthalates, phthalic anhydride, residues from the manufacture of phthalic acid, terephthalic acid, and residues from the manufacture of terephthalic acid, isophthalic acid and trimellitic anhydride. The described polyol utilizes hydrogen containing halo-carbon blowing agents such as HCFC's and optionally simple hydrocarbons.
U.S. Pat. Nos. 4,521,611 and 4,526,908 to Magnus describe a polyol composition having phthalic anhydride and a dihydroxy alkylene having two to six carbon atoms; propane diols having the middle carbon substituted with methane components, methanol components, hydroxy components, or hydrogen; or radicals of the formula HO—(R
3
O)
n
—R
3
—OH, where R
3
is an alkylene radical containing two or three carbon atoms and n is an integer from one through three. The foam making process using the disclosed polyol is carried out with excess polyol and limited isocyanate. The disclosed polyols increase the solubility of fluorocarbon blowing agents within the polyol-isocyanate mixture.
U.S. Pat. No. 4,897,429 to Trowell et al. discloses a polyol blend having tall oil fatty acids, dimethyl terephthalate process residue, and polyhydric alcohol components. The components are reacted in the presence of a transesterification catalyst and then reacted with alkylene carbonates or alkylene oxide. The disclosed improved polyol has increased compatibility with chlorofluorocarbon blowing agents. Trowell '602 also discloses an improved polyol blend having tall oil

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