Carbamate solutions with bound carbon dioxide prepared from...

Details Carbamate solutions with bound carbon dioxide prepared from... Carbamate solutions with bound carbon dioxide prepared from...

1999-11-12

2001-11-13

Wilson, James O. (Department: 1623)

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acid esters

C560S157000, C560S158000, C560S160000

Reexamination Certificate

active

06316662

ABSTRACT:

The present invention relates to carbamate solutions obtainable by reacting at least one alkanolamine with carbon dioxide in, as solvent, at least one organic compound having a molecular weight of from 60 to 600 and containing at least one hydroxyl group, wherein the carbamate contains at least 0.51 mol, preferably from 0.61 to 2.5 mol, of bound carbon dioxide per mole of alkanolamine and the alkanolamine has one of the following formulae:
(I): NH
2
—X—OH
(II): HO—X—Y—OH
(III): HO—X—NR
9
—(CR
7
R
8
)
n5
—Y—OH
where
X: —[(CR
1
R
2
)
n1
—NR
3
]
n2
—[(CR
4
R
5
)
n3
—NR
6
]
n4
—(CR
7
R
8
)
n5
—
Y: —[NR
6
—(CR
4
R
5
)
n3
]
n4
—[(NR
3
—(CR
1
R
2
)
n1
]
n2
—
and
n1, n3, n5: identical or different integers selected from the group consisting of 1, 2, 3, 4,
n2, n4: identical or different integers selected from the group consisting of 0, 1, 2, 3, 4, 5, 6, preferably 0 and/or 1, where for each of X and Y the sum of n2 and n4 is greater than or equal to 1,
R1, R2, R4, R5, R7, R8: identical or different radicals selected from the group consisting of hydrogen, aliphatic, cycloaliphatic, araliphatic and aromatic radicals having from 1 to 20 carbon atoms, preferably from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl,
R3, R6, R9: identical or different radicals selected from the group consisting of hydrogen, aliphatic, cycloaliphatic, araliphatic and aromatic radicals having from 1 to 20 carbon atoms, preferably from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl, where preferably in (I), (II) and (III), particularly preferably in (II) and (III), at least one of the radicals R
3
, R
6
, R
9
is hydrogen.
Furthermore, the invention relates to processes for producing foams based on polyisocyanate polyaddition products and to polyisocyanate polyaddition products obtainable in this way.
Foamed polyisocyanate polyaddition products, which usually comprise polyurethane and possibly polyisocyanurate structures, are generally known. As blowing agent for producing these foams, use is frequently made of water which reacts with the isocyanate groups to form carbon dioxide which is the actual blowing agent. Furthermore, to supply carbon dioxide as blowing agent in the production of the foams, WO 98/04606, EP-A 652 250, EP-A 121 850 and EP-A 236 895 disclose carbamates, usually adducts of carbon dioxide to alkanolamines. Compared to water, the use of these carbamates as blowing agent has the significant advantage that the formation of urea structures in the foams resulting from the reaction of water with the isocyanate groups is avoided. As carbon dioxide-amine adducts, the carbamates liberate the chemically bound carbon dioxide during the polyisocyanate polyaddition reaction. A disadvantage of the known carbamates is their low content of carbon dioxide, based on the amines. The alkanolamines described in WO 98/04606 and EP-A 652 250 bind no more than 0.5 mol of carbon dioxide per mol of alkanolamine, since two mol of amine groups are required to bind one mol of carbon dioxide. A further significant disadvantage, particularly of the teachings of EP-A 121 850, is the preferred preparation of the carbamates in an aqueous medium, since the water reacts with the isocyanates during the production of the foamed polyisocyanate polyaddition products. Even if water is used as additional blowing agent, specific metering in admixture with the carbamate is difficult to achieve. In addition, especially carbamates which have been prepared without solvent have an undesirably high viscosity which makes their use in the production of foams more difficult.
Since the amines can, owing to their catalytic activity, influence the polyaddition reaction, the amount of carbamate which can be used is limited. The ability to produce foams, particularly those having a low density and thus a high volume yield from the weight of reaction mixture used, is therefore restricted.
It is an object of the present invention to develop carbamates obtainable by reacting at least one alkanolamine with carbon dioxide, which carbamates contain as many mol of carbon dioxide as possible per mol of alkanolamine. Furthermore, the carbamates should have a desirably low viscosity in order to make them easier to use in the polyisocyanate polyaddition reaction. In addition, a process for producing foams based on polyisocyanate polyaddition products, preferably flexible foams, in particular flexible or semirigid integral foams based on polyisocyanate polyaddition products, for example by reacting (a) isocyanates with (b) compounds which are reactive toward isocyanates in the presence of (c) blowing agents and, if desired, (d) catalysts and/or (e) auxiliaries and/or additives, is to be developed. Such a process should improve the volume yield of carbamate-foamed foams and the economics, for example by saving blowing agents or catalysts, and foams having a relatively low density should be able to be obtained. Furthermore, the mechanical properties of the polyisocyanate polyaddition products, in particular flexible or semirigid integral foams, e.g. the abrasion behavior, the tensile strength and the visual appearance of the external skin, should be improved.
We have found that this object is achieved by the above-defined carbamates in the novel solutions of the carbamates in the solvents and their use as blowing agents in processes for producing foams based on polyisocyanate polyaddition products.
The carbamates of the present invention have the particular advantage that they are based on alkanolamines which can bind more than 0.5 mol of carbon dioxide per mole of alkanolamine. This is due to the particular structure of the alkanolamines used. In addition, the viscosity of the solutions has been able to be matched to the requirements in foam production. None of the documents cited disclose this inventive solution or make it obvious. EP-A 121 850 specifically states that the preparation of the carbamates is preferably carried out without organic solvents. The high molecular weight polyols indicated in EP-A 121 850 as possible, but not preferred, solvents have the specific disadvantage that a solution of the carbamate in these compounds has an undesirably high viscosity.
Particular preference is given to carbamate solutions based on NH
2
—CH
2
—CH
2
—NH—CH
2
—CH
2
—OH, hereinafter ref erred to as
2-(2-aminoethylamino)ethanol, H
2
N—(CH
2
)
2
—NH—(CH
2
)
3
—OH
(3-[(2-aminoethyl)amino)]propanol), H
2
N—(CH
2
)
3
—NH—(CH
2
)
2
—OH
(2-[(3-aminopropyl)amino]ethanol), CH
3
—CHOH—CH
2
—NH—(CH
2
)
2
—NH
2
(1-[(2-aminoethyl)amino]-2-propanol, HO—(CH
2
)
2
—NCH
3
—(CH
2
)
3
—NH
2
(2-[(3-aminopropyl)methylamino]ethanol,
1-[(2-amino-1-methylethyl)amino]-2-propanol,
2-[((2-amino-2-methylpropyl)amino]-2-methyl-1-propanol,
2-[(4-amino-3-methylbutyl)amino]-2-methyl-1-propanol,
17-amino-3,6,9,12,15-pentaazaheptadecan-1-ol and/or
3,7,12,16-tetraazaoctadecane-1,18-diol, in particular those based on 2-(2-aminoethylamino)ethanol as alkanolamine.
According to the present invention, these carbamates are prepared by introducing solid or gaseous carbon dioxide into a solution of the alkanolamine or alkanolamines in at least one of the solvents described below, usually at from 0 to 130° C., preferably from 20 to 100° C. The preparation of the carbamates can be carried out as described in EP-A 236 895, page 6, line 50 to page 7, line 9. The alkanolamine or alkanolamines is/are preferably saturated with carbon dioxide to prepare the carbamates.
Solvents used in the preparation of the carbamates are organic compounds containing at least one, preferably from 2 to 8, in particular 2 or 3, hydroxyl groups and having a molecular weight of from 60 to 600, preferably from 60 to 300, for example customary chain extenders and/or crosslinkers which are known for the polyisocyanate polyaddition reaction, preferably ethylene glycol, diethylene glycol, 1,2- and/or 1,3-propanediol, dipropylene glycol, 1,4-, 1,2- and/or 1,3-butanediol, 1,6-h

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