CA2056775A1

CA2056775A1 - Process for removing cured flexible polyurethane foams from substrates

Info

Publication number: CA2056775A1
Application number: CA 2056775
Authority: CA
Inventors: Edward Thomas Marquis
Original assignee: Individual
Current assignee: Huntsman Corp
Priority date: 1990-12-18
Filing date: 1991-12-02
Publication date: 1992-06-19

Abstract

Abstract (D# 80,968-F) A process for the dissolution of cured flexible polyurethane foams is disclosed. A cured flexible polyurethane foam may be dissolved, or removed from a substrate, by contacting the flexible polyurethane foam with a mixture comprising (1) an alkylene carbonate and (2) at least one non-alkylene carbonate co-solvent in which said cured flexible polyurethane foam is at least partially soluble.

Description

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D# 80,968-F
RRS

A PROCESS FOR REMOVING CURED FLEXIBLE POLYURETHANE FOAMS
FROM SUBS~RATES
(D# 80,968-F) Cross-Reference to Related_A~plications This application is related to the following co-pending U. S. Patent Applications: Serial No. 07/610,635, filed November 8, 1990; and Serial No. (D# 80967!, filed December 13, 1990.
Backaround of the Invention Field of the Invention The invention relates to solvents for loosening or removing cured flexible polyurethane foams from tools, processing equipment and other substrates.
Descri~tion of Related Methods A variety of solvents have been used to clean processing equipment, metal parts and tools after a flexible polyurethane foam has cured on them. Some of the solvents used include such compounds as dimethyl formamide, l,l,l-trichloroethane, methylene chloride, N-methyl piperazine, chlorofluorocarbons, toluene, xylene, acetone, methyl ethyl ketone, ethylene glycol ethers, tetrahydrofuran, and 7-butyrolactone. However, though these compounds are effective solvents, the use of each presents a hazard or complication of one type or another. For example, the chlorine-containing compounds are now thought to contribute to ozone depletion in the atmosphere. The other solvents are either toxic, suspected carcinogens, or very volatile, and thus present health and safety problems. An alternative solvent, N-methyl ' 20S6775 pyrrolidinone, is more easily handled and presents fewer environmental problems, but is expensive. Thus, it would be a substantial improvement in the art if a relatively inexpensive yet effective solvent formulation were available to remove cured flexible polyurethane foams, and that did not present the environmental, health and safety problems of the prior art solvent formulations.
Applicant has discovered, surprisingly, that cured flexible polyurethane foam may be removed from a substrate by contacting the flexible polyurethane foam with a co-solvent system comprising an alkylene carbonate and one or more other solvents.
The present inventive process, by substituting alkylene carbonate for a portion of the more hazardous prior art solvents, reduces many of the health, safety and environmental hazards associated with the prior art solvents, and is economically attractive as well.
Summary of the Invention The invention concerns, in a process for removing a cured flexible polyurethane foam from a substrate by contacting said flexible polyurethane foam with a solvent in which said cured flexible polyurethane foam is at least partially soluble, the improvement comprising diluting said solvent with a co-solvent comprising alkylene carbonate. In another of its aspects, the invention concerns a process for removing cured flexible polyurethane foam from a substrate, comprising contacting a cured flexible polyurethane foam with a co-solvent system comprising a .
.. '' ' ;.

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mixture of alkylene carbonate and at least one non-alkylene carbonate solvent selected from the group consisting of aromatic hydrocarbons, alcohols, ketones, esters, ethers, glycol ethers, imidazoles, and ureas. The invention also concerns a process for dissolving cured flexible polyurethane foam, comprising contacting a cured flexible polyurethane foam with a co-solvent system comprising a mixture of (l) an alkylene carbonate selected from the group consisting of ethylene carbonate, propylene carbonate, and 1,2-butylene carbonate and (2) at least one non-alkylene carbonate solvent in which said flexible polyurethane foam`is at least partially soluble, selected from the group consisting of aromatic hydrocarbons, alcohols, ketones, esters, ethers, glycol ethers, imidazoles, and ureas.
Description of the Preferred Embodiments Alkylene carbonates useful in the present invention may be represented by the following formula:

R

where R is H or an alkyl group containing from 1 to about 20 carbon atoms. It is preferred that R be H or a methyl group, i.e. that the alkylene carbonate be ethylene carbonate, propylene carbonate, or 1,2-butylene carbonate. Ethylene carbonate and propylene carbonate are commercially available from Texaco Chemical Co. as ~...~, . . .

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Texacar EC Ethylene Carbonate and Texacar PC Propylene Carbonate, respectively. Alternatively, a mixture of alkylene carbonates may be used. A mixture of ethylene carbonate and propylene carbonate is commercially available as Texacar EC-50.
Solvents that may be diluted by alkylene carbonates in the present invention include, but are not limited to, solvents selected from the group consisting of aromatic hydrocarbons, alcohols, ketones, esters, ethers, glycol ethers, imidazoles, and ureas. For example, Applicant has demonstrated the removal of flexible polyurethane foams from substrates using co-solvent formulations containing an alkylene carbonate and one or more of the following solvents: 2-ethyl-1-hexanol, ethylene glycol, tetrahydrofurfuryl alcohol, tetramethyl urea, diethylene glycol butyl ether, ethylene glycol butyl ether, dipropylene glycol methyl ether, methyl isobutyl ketone, propylene glycol methyl ether, cyclohexanol, toluene, methyl caproate, diethyl succinate, dimethyl succinate, diethyl carbonate, n-propyl alcohol, and isobutyl isobutyrate.
Preferably, the non-alkylene carbonate solvent is selected from the group consisting of toluene, l-isopropyl-2-methyl imidazole, methyl caproate, 2-ethyl-1-hexanol, N-methyl pyrrolidinone, tetrahydrofurfuryl alcohol, tetramethyl urea, diethylene glycol butyl ether, ethylene glycol butyl ether, methyl iso-amyl ketone, cyclohexanol, diethylene glycol methyl ether, dipropylene glycol methyl ether, methyl isobutyl ketone, 1,2-dimethyl imidazole, N,N'-dimethyl ethylene urea, furfuryl ^ ~ 20S677~

alcohol, propylene glycol methyl ether, dimethyl formamide, isobutyl isobutyrate, and the like. More preferably, the non-alkylene carbonate solvent is selected from the group consisting of 2-ethyl-1-hexanol, N-methyl pyrrolidinone, toluene, l-isopropyl-2-methyl imidazole, tetramethyl urea, isobutyl isobutyrate, methyl isobutyl ketone, methyl iso-amyl ketone, 1,2-dimethyl imidazole, methyl caproate, N,N'-dimethyl ethylene urea, furfuryl alcohol, tetrahydrofurfuryl alcohol, propylene glycol methyl ether, ethylene glycol butyl ether, diethylene glycol butyl ether, dimethyl formamide, and the like. Optionally, other solvents may be added to the formulations of the present invention as well.
Preferably, the portion of conventional solvent replaced with alkylene carbonate in a formulation containing one or more conventional (non-alkylene carbonate) solvents will be such that the alkylene carbonate and the conventional solvents in the formulation are present in a weight ratio of alkylene carbonate to total conventional solvent of about 4:1 to about 1:4. It is more preferred that the alkylene carbonate and the conventional solvents in the formulation be present in a weight ratio of alkylene carbonate to total conventional solvent of about 1:2 to about 1:3.
One skilled in the art may find other weight ratios to be optimum and not depart from the scope of the present invention. Those skilled in the art will appreciate that the portion of conventional solvent(s) in a formulation which should be replaced with alkylene carbonate for a given flexible polyurethane foam involves a balance of possible reduction in dissolution power versus the reduction or . -. 205677~

avoidance of additional expense and/or environmental, health and safety risks associated with the conventlonal solvents. Applicant has demonstrated the use of several different formulations in the examples that follow.
Optionally, other additives may be employed in the formulations of the present invention. For example, suitable thickeners may be included, such as ethylcellulose, hydroxypropyl cellulose, organic modified clay, hydrogenated castor oil, and the like. Surfactants, to enhance the water washability of the substrate, may be included as well. Suitable surfactants include potassium oleate, the dioctyl ester of sodium sulfosuccinic acid, sodium alkylnaphthalene sulfonate, sodium alkylbenzene sulfonate, and the like.
Applicant's inventive process is effective at temperatures of from about room temperature to about 100 ~C and at pressures of from about atmospheric to several hundred psi.
Optionally, the process of the present invention may be performed at an elevated temperature. While Applicant's invention works well at room temperature, more effective dissolution may be obtained by heating the alkylene carbonate-containing formulation to a temperature of about 50 to about 100 C. The alkylene carbonate-containing formulation may be applied to the flexible polyurethane foam in any conventional manner. Typically, the flexible polyurethane foam-coated substrate will be placed in a vat or sonic bath containing the alkylene carbonate-containing formulation.
Alternatively, the alkylene carbonate-containing formulation could -`- 20~677~
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be applied to the foam-coated substrate by brush or spray. The period of time for which the alkylene carbonate-containing formulation should be permitted to work undisturbed on the flexible polyurethane foam to be removed will vary. After said period of time, agitation of the surfaces to be cleaned of the foam via wiping, brushing or scraping is preferred.
Flexible polyurethane foam formulations are well known in the art and are commercially available. In contrast to rigid foams, flexible foams are not highly cross-linked. Other characteristics generally true of flexible polyurethane foams include (1) a structure having a high percentage of open cells;
(2) air permeability: (3) reversible deformability; (4) a limited resistance to an applied load; and (5) low dimensional stability.
Generally, flexible polyurethane foams are based on polyols having a molecular weight greater than 1000 (about 70 atoms or more per chain). Flexible polyurethane foams usually are based on a polyol having a functionality of about 2 to 4, and more typically of about 2 to 3.
The invention will be further illustrated by the following examples, which are given by way of illustration and not as limitations on the scope of this invention.

Examples In the examples recorded in the table below, the following procedure was used. Previously coated stainless steel 3/4" screw stock rods were wire brushed and cleaned with a solvent.

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-~` 20S6775 Rods that had been coated with cured fiberglass were treated with acetone to remove any fiberglass residue; those that had been coated with cured rigid or flexible polyurethane foam were treated with methylene chloride. The rods were then sand blasted with micro beads. The rods were then coated with a polyether-based flexible foam formulation having the following components:
Component Parts by Weiaht Thanol~ SF-55051 60.0 Niax~ 34-28 Polymer Polyol2 40.0 Deionized Water 3.5 Diethanolamine 1.5 Silicon Oil L-53093 1.5 TEXACAT~-33A4 (33 % TEDA in DPG) 0.5 UL-l (organotin in cmp.)5 0.0065 Toluene diisocyanate 44.5 lArco: 2Union Carbide; 3Union Carbide; 4Texaco Chemical Co.; 5Witco Fomrez-.
The coatings were then allowed to cure for two days or more before dissolution studies were begun. Each coated stock rod was then suspended in a beaker from a ring stand. Each beaker contained one of the alkylene carbonate-containing formulations to be tested. At the bottom of each beaker was a stirring bar. After from about 16 to about 22 hours at room temperature the rods were observed and the approximate percentage of flexible polyurethane foam removed by each formulation was estimated and recorded.

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Ex. No~ Co Solvent System Components Woight Ratlo of Appro~matc % l~le~ible ___ Component~ Eoam Removed 1 PC/'lMU~rOL 56.7/56.7/56.7 ~ 100%
2 PC/TMU 85/85 95 %
3 PCrrMU/lBIB 56.7/56.7/56.7 95 %

4 PC/'IMU/IBIBITOL 425/425/425/425 95 %
S PC/lNUIMlBK~rOL 425/425/42.2/425 90 %
6= PC/lMU/MlBK = 56.7/56.7~56.7 75 %
7 EC~rMU/MlBR/TOL 20/24/29/27 100 %
8 EC~IMU/`TOL 28/34/38 95 %
9 EC/TMU/IBIB 28/34/38 90 %
EC/TMU/IBIB/TOL 20/?5/28/27 90 %
11 EC/TMU/MIBK 27/33/40 90 %
_ EC/TMU 45/SS 50 %
¦~ PC~IHFA/MIBR 613/613/60.1 95 %
14 PC/'Il~FA/IB18/TOL 40.8/40.8/57.7/36.8 40 %
~ PCtIHI7A/MlBR/TOL 45/45/45/45 10 %
¦ 16 EC/IUFA/IBIB/TOL 19/21/37/23 50 9'0 ¦ 17 EC~lHEA/l~flBVTOL 20/23/30/27 10 %
18 eC/lHPA/lBlB 28/31/41 10 %
¦ 19 PC/EB/MIBK 613/70.9/60.1 90 %
1 20 PC/EB/IBIB 51.1/59.1/72.1 90 %
I
¦ 21 PC/EB/IBIBITOL 40.8/473/57.7/36.8 80 %
22 PC/EB/PIII/MIBK 46.0/53.2/405/45.1 40 %
23 PC/EB 102.1/118.2 33 %
24 EC/EB/IBIB/TOL 17/27/34/22 20 %
I
C/EB/lBlB , 22/34/44 10%
26 EC/EB/MIBK 30/35/~S 5 %
.
PC - Propgtenc calbona~e; ec ethgtene c~ale; TMU - Tcmmethyt ure; TOL ~ Toluene; IBIB = Isobutyl isobutgrate;
THPA - Tet~hgdrorurrutyl akobd; EB ~ Ethy1ene glgcol butgl ether, MIBR - Methgt i~butgl l~etone.

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~ 20~6775 _ ~
E~ No. Co-Solvcnl S~n~om C~mponent~ Weiithl i~tlo ot Appro~nale % Piatiblc Components Po~m Rcmoved 27 PC/Methyi c proate 85/R5 90 %
28 PC/Methyi cap~te/TOL 56.7/56.7/56.7 70 %
29 PC/DB~I`OL 72!72/36 t0 *
PC/DB/MIBK 56.2/892/55.1 75 %
31 PC/DB 102.1/162.2 25 %
32 PC/PM/MIBK 51.1/45.1/50.1 75 %
._ 33 PC/PM 102.1/90.1 50 %
3~1 PC/2~ethyi-1-hc~nol/(~gchbexanol 51.1/65.1/50.1 50 %
PC/2~clhyhl-i~nd/Cycbhcuanol/TOL 42.9/54.7/42.1/3a7 10 %
36 PC/DPM/MIBK 37/70/70 33 %
37 PC/DPM/~iBR 51.1/74.1/50.1 20 %
38 PC/BG/MIBK ~2 LAYERS) 65.7/39.9/64A 25 %
39 PC/DeC/MlBK 542/62.7/53.1 25 %
PC/Diethyiwcdnate/MiBK/TOL 42.5/425/4 5/425 10%
41 PC/Dimeli yi ~uc~le/MlBKJlOL 42.5/42.5/42.5/42.5 7 %
42 EC/n!pr~p nolMlBR 25/35/40 S %
43 Dimetb~i fonnamide i 100 %
: 44 1~i' op~2-mcthyl imidlude i 100 %
3~0p~2~iinone ~ 20 %
,' ~ - -~,"... ....
iLC ~ i~lenc c lbon b; PC - P~lenc ~Ibonate; DeC ~ Dielbyi cubona~e; TMU ~ Telnmethyi ule; DB - Dietbylene ~bcol butyi etber, PM - P~1ene i~'i methyi elhcr DPM - Dilmpyene ~i mctihyi ether, PM ~ P~tenc giycol methyi cthcr MilBR ~ Meti~ i'~butyi ktonc; TOL - Toiuene; EG ~ Ethyene islpo.

Claims

1. In a process for removing a cured flexible polyurethane foam from a substrate by contacting said flexible polyurethane foam with a solvent in which said cured flexible polyurethane foam is at least partially soluble, the improvement comprising diluting said solvent with a co-solvent comprising alkylene carbonate.

2. The process of claim 1, in which the alkylene carbonate is 1,2-butylene carbonate.

3. The process of claim 1, in which the alkylene carbonate is propylene carbonate.

4. The process of claim 1, in which the flexible polyurethane foam is a polyether-based polyurethane foam.

5. The process of claim 1, in which the alkylene carbonate is ethylene carbonate.

6. A process for removing cured flexible polyurethane foam from a substrate, comprising contacting a cured flexible polyurethane foam with a co-solvent system comprising a mixture of alkylene carbonate and at least one non-alkylene carbonate solvent selected from the group consisting of aromatic hydrocarbons, alcohols, ketones, esters, ethers, glycol ethers, imidazoles, and ureas.

7. The process of claim 6, further comprising the second step of mechanically agitating the flexible polyurethane foam attached to the surface of said substrate.

8. The process of claim 6, in which the co-solvent system is heated to a temperature of about 50 to about 100 °C.

9. The process of claim 6, in which the cured flexible polyurethane foam is contacted with the co-solvent system at room temperature.

10. The process of claim 6, in which the non-alkylene carbonate solvent is selected from the group consisting of toluene, 1-isopropyl-2-methyl imidazole, methyl caproate, 2-ethyl-1-hexanol, N-methyl pyrrolidinone, tetrahydrofurfuryl alcohol, tetramethyl urea, diethylene glycol butyl ether, ethylene glycol butyl ether, methyl iso-amyl ketone, cyclohexanol, diethylene glycol methyl ether, dipropylene glycol methyl ether, methyl isobutyl ketone, 1,2-dimethyl imidazole, N,N'-dimethyl ethylene urea, furfuryl alcohol, propylene glycol methyl ether, dimethyl formamide, isobutyl isobutyrate.

11. The process of claim 6, in which the non-alkylene carbonate solvent is selected from the group consisting of 2-ethyl-1-hexanol, N-methyl pyrrolidinone, toluene, l-isopropyl-2-methyl imidazole, tetramethyl urea, isobutyl isobutyrate, methyl isobutyl ketone, methyl iso-amyl ketone, 1,2-dimethyl imidazole, methyl caproate, N,N'-dimethyl ethylene urea, furfuryl alcohol, tetrahydrofurfuryl alcohol, propylene glycol methyl ether, ethylene glycol butyl ether, diethylene glycol butyl ether, dimethyl formamide.

12. The process of claim 6, in which the alkylene carbonate is 1,2-butylene carbonate.

13. The process of claim 6, in which the alkylene carbonate is propylene carbonate.

14. The process of claim 6, in which the alkylene carbonate is ethylene carbonate.

15. The process of claim 6, in which the weight ratio of alkylene carbonate to non-alkylene carbonate solvents in the mixture is from about 1:2 to about 1:3.

16. The process of claim 6, in which the co-solvent system comprises a mixture of alkylene carbonate and at least two non-alkylene carbonate solvents selected from the group consisting of toluene, 1-isopropyl-2-methyl imidazole, methyl caproate, 2-ethyl-1-hexanol, N-methyl pyrrolidinone, tetrahydrofurfuryl alcohol, tetramethyl urea, diethylene glycol butyl ether, ethylene glycol butyl ether, methyl iso-amyl ketone, cyclohexanol, diethylene glycol methyl ether, dipropylene glycol methyl ether, methyl isobutyl ketone, 1,2-dimethyl imidazole, N,N'-dimethyl ethylene urea, furfuryl alcohol, propylene glycol methyl ether, dimethyl formamide, isobutyl isobutyrate.

17. The process of claim 6, in which the flexible polyurethane foam is a polyether-based polyurethane foam.

18. A process for dissolving cured flexible polyurethane foam, comprising contacting a cured flexible polyurethane foam with a co-solvent system comprising a mixture of (1) an alkylene carbonate selected from the group consisting of ethylene carbonate, propylene carbonate, and 1,2-butylene carbonate and (2) at least one non-alkylene carbonate solvent in which said flexible polyurethane foam is at least partially soluble, selected from the group consisting of aromatic hydrocarbons, alcohols, ketones, esters, ethers, glycol ethers, imidazoles, and ureas.

19. The process of claim 18, in which the cured flexible polyurethane foam is a polyether-based polyurethane foam.

20. The process of claim 18, in which the non-alkylene carbonate solvent is selected from the group consisting of 2-ethyl-1-hexanol, N-methyl pyrrolidinone, toluene, 1-isopropyl-2-methyl imidazole, tetramethyl urea, isobutyl isobutyrate, methyl isobutyl ketone, methyl iso-amyl ketone, 1,2-dimethyl imidazole, methyl caproate, N,N'-dimethyl ethylene urea, furfuryl alcohol, tetrahydrofurfuryl alcohol, propylene glycol methyl ether, ethylene glycol butyl ether, diethylene glycol butyl ether, dimethyl formamide.