CA1320772C - Neutralization of polyalkylene carbonate polyols for polyurethane prepolymer synthesis - Google Patents
Neutralization of polyalkylene carbonate polyols for polyurethane prepolymer synthesisInfo
- Publication number
- CA1320772C CA1320772C CA000558306A CA558306A CA1320772C CA 1320772 C CA1320772 C CA 1320772C CA 000558306 A CA000558306 A CA 000558306A CA 558306 A CA558306 A CA 558306A CA 1320772 C CA1320772 C CA 1320772C
- Authority
- CA
- Canada
- Prior art keywords
- acid
- prepolymer
- polyalkylene carbonate
- pac
- polyol
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
- C08G18/44—Polycarbonates
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/08—Processes
- C08G18/089—Reaction retarding agents
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
- C08K5/41—Compounds containing sulfur bound to oxygen
- C08K5/42—Sulfonic acids; Derivatives thereof
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Polyurethanes Or Polyureas (AREA)
Abstract
ABSTRACT
A prepolymer stabilization process for polyalkylene carbonate polyols includes the steps of adding a small quantity of an organosulfonic acid with stirring until base neutralization is achieved. One measure of base neutralization is a negative CPR, a test relating to controlled polymerization rate.
34,982-F -11-
A prepolymer stabilization process for polyalkylene carbonate polyols includes the steps of adding a small quantity of an organosulfonic acid with stirring until base neutralization is achieved. One measure of base neutralization is a negative CPR, a test relating to controlled polymerization rate.
34,982-F -11-
Description
2~377~
NEUTRALI~ATION OF POLYAL~YLENE CARBONATE
POlYOLS FOR POLYURETHANE PREPOLYMER SYNTHES~S
Polyuret~lanes come to mind first when one thinks of foam products, and indeed polyurethanes dominate the solid foam market. Such foams may be either rigid or flexible, depending on how the process of manufacture Lakes place. In fact~ polyurethane systems allow enormous variations in the polymerization and fabrication processes; it is this complexity which keeps the urethane area a fertile field for development and expansion.
Like many macromolecules~ polyurethalles are a general class of materials which can be prepared via many different routes? at least in principle~ However, industrial practicalities dictate a preferred approach based on, for example, feedstock availability and ease of processing. For example, ordinary condensation polymerization of bischloroformates with diamines will yield polyurethanes, but the universal large scale practice calls for condensation of diisocyanates with diols. (More generally, the common synthesis involves diisocyanates and polyols, wherein the diol is a special case? where triol species produce crosslinking). A
typical instance might have 2,4-toluene diisocyanate (TDI) reacting wi~h l~-butanediol. In any case, the practical problems show up not at the level of individual chemical molecules but rather with the physical production and molding steps.
34 9~2-F
~ '~
.f~
-2- ~32~72 PolyureLhanes are notoriously defiant regarding fabrication. The production of a good, useful foam object involves precise controL over the size an(l distribution of the hollow vo;ds, or cells in the product. An open cell foam would malce a poor life preserver while a closed cell foanl would make a poor sponge. Volumes have been wril:ten on the problems associated with polyurethane processing, and the subject is generally beyond the scope of this discussion, except as relates to prepolymer stabilization.
Most polyurethanes cannot simply be made into a melt and injected into a mold in the way that polyethylene normally perform. One viable method is the "one shot" approach, whereby all the reactants are combined simultaneously with injection into the mo]d.
The alternative process calls for controlled synthesis uf a prepolymer, i.e., a short chain polyurethane intermediate. The use of the intermediaLe provides a polyurethane which has generally better properties. The prepolymer method is generally more forgiving than the one shot approach, and hybrid techniques are possible, but the present art still has much room for i~npro~ements. This patent addresses the practical problem of prepolymer stability.
3o 34,982-F
,,. ....~ ,~ .
NEUTRALI~ATION OF POLYAL~YLENE CARBONATE
POlYOLS FOR POLYURETHANE PREPOLYMER SYNTHES~S
Polyuret~lanes come to mind first when one thinks of foam products, and indeed polyurethanes dominate the solid foam market. Such foams may be either rigid or flexible, depending on how the process of manufacture Lakes place. In fact~ polyurethane systems allow enormous variations in the polymerization and fabrication processes; it is this complexity which keeps the urethane area a fertile field for development and expansion.
Like many macromolecules~ polyurethalles are a general class of materials which can be prepared via many different routes? at least in principle~ However, industrial practicalities dictate a preferred approach based on, for example, feedstock availability and ease of processing. For example, ordinary condensation polymerization of bischloroformates with diamines will yield polyurethanes, but the universal large scale practice calls for condensation of diisocyanates with diols. (More generally, the common synthesis involves diisocyanates and polyols, wherein the diol is a special case? where triol species produce crosslinking). A
typical instance might have 2,4-toluene diisocyanate (TDI) reacting wi~h l~-butanediol. In any case, the practical problems show up not at the level of individual chemical molecules but rather with the physical production and molding steps.
34 9~2-F
~ '~
.f~
-2- ~32~72 PolyureLhanes are notoriously defiant regarding fabrication. The production of a good, useful foam object involves precise controL over the size an(l distribution of the hollow vo;ds, or cells in the product. An open cell foam would malce a poor life preserver while a closed cell foanl would make a poor sponge. Volumes have been wril:ten on the problems associated with polyurethane processing, and the subject is generally beyond the scope of this discussion, except as relates to prepolymer stabilization.
Most polyurethanes cannot simply be made into a melt and injected into a mold in the way that polyethylene normally perform. One viable method is the "one shot" approach, whereby all the reactants are combined simultaneously with injection into the mo]d.
The alternative process calls for controlled synthesis uf a prepolymer, i.e., a short chain polyurethane intermediate. The use of the intermediaLe provides a polyurethane which has generally better properties. The prepolymer method is generally more forgiving than the one shot approach, and hybrid techniques are possible, but the present art still has much room for i~npro~ements. This patent addresses the practical problem of prepolymer stability.
3o 34,982-F
,,. ....~ ,~ .
-3- .~ 32 ~ ~ ~2 6~693-4193 In particular, the present invention provides tor treatment of polyols: this process involves the treatment of polyalkylene carbonate polyols, leading to more stable prepolymers and improved urethane products.
Polyalkylene carbonate (PAC) polyols may be made by a base-catalyzed reaction, and some catalyst remains in the product PAC. Accordingly, the prior art has depended on residual acid species, e.g., HCl, in the TDI
to neutralize the residual base species in the polyol.
Where necessary, it is possible to add an aci~ chloride to the TDI (invariably benzoyl chloride) to provide for the neutralization: but the limitation on the prior art is that benzoyl chloride simply does not stabilize PAC
prepolymers -- even when added in large excess. ~enzoyl chloride may prevent a runaway exothermic reaction, but even so, it is just as objectionable as HCl for many applications because residual chloride ions remain in the product. Even further, benzoyl chloride does not provide a stable prepolymer. The present invention resides in a method of stabilizing a prepolymer comprising the step of adding an effective amount of an organosulfonic acid to polyalkylene carbonate polyol to obtain a stabilized polyalkylene carbonate polyol and produces stable PAC prepolymers with dual advantages of longer storage times ~before fabrication) and longer gel times (during fabrication). Thus, premature curing does not occur, and the molded products have better physical properties, environmental resistance, etc.
The PAC polyol is typically a diol with an equivalent weight of about 250 to 2000, although triols are available. Addition of a strong acid to the PAC
34,982-F -3-!l _~
-3a- 1 3 2 0 7 7 2 64693 4193 polyol neutralizes the residual base catalyst, preventing side reactions, including trimerization of the TDI.
Specifically, the P~C polyol requires initial characte~ atioll with respect to its "CPR" count.
34,982-F -3a-g ~
D
,, ~ 3~7~2 "CPR" represents the phrase "controlled polymerization rate," signifying the amount of residual base in the prepolymer. CPR determination protocol calls for 30 g of PAC ;n 100 ml of methanol to be titrated with 0.01 N
HC1, where the ten times the acid volume is equal to Lhe CPR value. See "Urethane Polyether Prepolymers and - Foams: Influence of Chemical and Physical variables on Reaction Behavior" by Schotten, Schuhmann, and Ten~loor, in J. Chem. En~. ~ata. Vol. 5, No. 3, July 1960~ The key is to achieve a negative CPR value by addition of the strong acid. But a CPR value below -100 would be unnecessary, possibly even counterproductive and detrimental to the product.
The strong acids used here include methanesulfonic acid (MSA) and para-toluenesulfonic acid (PTSA). Certainly many other strong acids will also work, but each acid type should be tested experimentally, not to verify its ability to clean up the PAC polyol, but rather to determine whether unwanted side reactions also occur. For example, as suggested earlier, HC1 has been found to be an undesirable acid.
But it is equally clear that virtually any organosul~onic acid will perfGrm satisfactorily.
E'urthermore, some acids react directly with TDI, e.g., H2S04 and PTSA; so it is necessary to treat the PAC polyol with the acid prior to its reaction with a polyisocyanate.
3o The process involves mixing an acid with a selected polyol, more particularly with PAC, either before or after it is reacted with a polyisocyanate to form a prepolymer. The mixing procedure is best carried out at 60F (15"C) to 95F (35C~, in a closed container.
34,9c2-F` -4-"~ ' _5_ ~ 3 2 ~Y~12 The acid is added to the PAC iJi~h stirring. The acid is stirred into the PAC using, for laboratory amounts~ a stirring device, to mix acid. The amount of acid is quite small; as an example, for Oile liter of PAC, acid is added with stirring in an e~fective amount of just a few ppm, or only a few drops. Since only a s~all amount of acid is needed, a neutral diluent (preferably the PAC
polyol i~self) is added to the acid, perhaps l0 to 50 to one of acid. The acid is added over time with stirring.
If the residual base species in the PAC is known beEore treatment, the amount of acid can be calculated. On the other hand, acid can be ratably aclded to achieve base neurtalization over time to avoid excessive over dosing.
Therefore, the preferred procedure is adding acid while stirring the PAC until the requisite neutralization is accomplished. This extent oE acid addition varies primarily with the degree of PAC neutralization. Should insufficient acid be added, the step is repeated until a negative CPR value is obtained.
The following examples and comparative run are provide~ to illustrate the invention but are not intended to limit the scope thereof.
Comparative Run A
This comparative run shows the inefEicacy of benzoyl chloride as a stahi]izer. A PAC polyol was reacted with tol~ene diisocyanate to form a prepolymer having an isocyanate content of 5 percent. The prepolymer CPR values were found according to the procedure mentioned above. Viscosity of the prepolymer after treatment is given in centipoises3 as measured with a Brookfield Viscometer Model RVTD. This machine is rotational viscometer containing various spindles3 34,982-F` -5--6-- ~32~72 previously cali~rated by the manu~acturer. The spindle is placed in ~he solution to be analyzed and rotated.
~`he viscosity is calculated by multiplying the RYM by the appropriate spindle calibraLion factor.
TABLE I
Prepolymer Prepolymer Viscoslty, cp Time Before _ CPR ~ Gela tion 1.76 instantaneous 1.4074,200 (74.2) 1 hour 0.9940,400 (40.4) 1 day 0.00633,000 (33) 1 day -2.0127,000 (27) 1-2 days -4.9824,000 (24) 1-2 days -7.9529,800 (29.8) 1-2 days -13.8941,200 (41.2) 1-2 days -31.3537,000 (37) 1-2 days -61.4126,800 (26.8) 1-2 days Yarious side reactions appear to have occurred, 25 including trimerization of the isocyanate, resulting in gelation.
34,982-F -6-..... _.. _ .
. ~ , . .
_7-~ ~ 32~772 In a second test described in Table II, PTSA
was used to treaL a quantity of PAC. The treated PAC
was then reacted with an excess oÇ toluene diisocyanate to form a prepolymer containing 5 percent isocyanate groups. Measurements were taken after 24 hours at 80C.
TABLE :[I
CPR of PAC Prepolymer Result 5.2 gelation 1.2 gelation 150.2 no gelation (stil l liq u id) -5.0 no gelation (still liquid) The first two runs evidence trimerization with the TDI, while the two runs at lower CPR show stability of the prepolymer made with a properly treated PAC.
Example 2 For a third test described in Table lII, more quantitative data was obtained by measuring % NC0 loss (a weight percent of the prepolymer). The percentage value is found by carrying out a dibutylamine reaction, followed by back titratin with HCl. Measurements were taken after 24 hours at 80~C.
34,982-F -7--8- ~32(~7f~
Table III
-CPR of PAC Acid /0 N_O Los-t 6.0Benzoyl chloride gela-tior -10 PTSA 0 . 04 1.7 MSA 0.01 Treatment or neutralization of the polyol in the latter two cases was sufficient to stop virtually any trimerization of the prepolymer As shown from the foregoing tables, l~AC polyol neutralization is accomplished to obtain a more useful prepolymer. While variations in the present process may be incorporated, the scope of the present disclosure is determined by the claims which follow.
-.g~r ~ ~4,982-F -8-~ !
Polyalkylene carbonate (PAC) polyols may be made by a base-catalyzed reaction, and some catalyst remains in the product PAC. Accordingly, the prior art has depended on residual acid species, e.g., HCl, in the TDI
to neutralize the residual base species in the polyol.
Where necessary, it is possible to add an aci~ chloride to the TDI (invariably benzoyl chloride) to provide for the neutralization: but the limitation on the prior art is that benzoyl chloride simply does not stabilize PAC
prepolymers -- even when added in large excess. ~enzoyl chloride may prevent a runaway exothermic reaction, but even so, it is just as objectionable as HCl for many applications because residual chloride ions remain in the product. Even further, benzoyl chloride does not provide a stable prepolymer. The present invention resides in a method of stabilizing a prepolymer comprising the step of adding an effective amount of an organosulfonic acid to polyalkylene carbonate polyol to obtain a stabilized polyalkylene carbonate polyol and produces stable PAC prepolymers with dual advantages of longer storage times ~before fabrication) and longer gel times (during fabrication). Thus, premature curing does not occur, and the molded products have better physical properties, environmental resistance, etc.
The PAC polyol is typically a diol with an equivalent weight of about 250 to 2000, although triols are available. Addition of a strong acid to the PAC
34,982-F -3-!l _~
-3a- 1 3 2 0 7 7 2 64693 4193 polyol neutralizes the residual base catalyst, preventing side reactions, including trimerization of the TDI.
Specifically, the P~C polyol requires initial characte~ atioll with respect to its "CPR" count.
34,982-F -3a-g ~
D
,, ~ 3~7~2 "CPR" represents the phrase "controlled polymerization rate," signifying the amount of residual base in the prepolymer. CPR determination protocol calls for 30 g of PAC ;n 100 ml of methanol to be titrated with 0.01 N
HC1, where the ten times the acid volume is equal to Lhe CPR value. See "Urethane Polyether Prepolymers and - Foams: Influence of Chemical and Physical variables on Reaction Behavior" by Schotten, Schuhmann, and Ten~loor, in J. Chem. En~. ~ata. Vol. 5, No. 3, July 1960~ The key is to achieve a negative CPR value by addition of the strong acid. But a CPR value below -100 would be unnecessary, possibly even counterproductive and detrimental to the product.
The strong acids used here include methanesulfonic acid (MSA) and para-toluenesulfonic acid (PTSA). Certainly many other strong acids will also work, but each acid type should be tested experimentally, not to verify its ability to clean up the PAC polyol, but rather to determine whether unwanted side reactions also occur. For example, as suggested earlier, HC1 has been found to be an undesirable acid.
But it is equally clear that virtually any organosul~onic acid will perfGrm satisfactorily.
E'urthermore, some acids react directly with TDI, e.g., H2S04 and PTSA; so it is necessary to treat the PAC polyol with the acid prior to its reaction with a polyisocyanate.
3o The process involves mixing an acid with a selected polyol, more particularly with PAC, either before or after it is reacted with a polyisocyanate to form a prepolymer. The mixing procedure is best carried out at 60F (15"C) to 95F (35C~, in a closed container.
34,9c2-F` -4-"~ ' _5_ ~ 3 2 ~Y~12 The acid is added to the PAC iJi~h stirring. The acid is stirred into the PAC using, for laboratory amounts~ a stirring device, to mix acid. The amount of acid is quite small; as an example, for Oile liter of PAC, acid is added with stirring in an e~fective amount of just a few ppm, or only a few drops. Since only a s~all amount of acid is needed, a neutral diluent (preferably the PAC
polyol i~self) is added to the acid, perhaps l0 to 50 to one of acid. The acid is added over time with stirring.
If the residual base species in the PAC is known beEore treatment, the amount of acid can be calculated. On the other hand, acid can be ratably aclded to achieve base neurtalization over time to avoid excessive over dosing.
Therefore, the preferred procedure is adding acid while stirring the PAC until the requisite neutralization is accomplished. This extent oE acid addition varies primarily with the degree of PAC neutralization. Should insufficient acid be added, the step is repeated until a negative CPR value is obtained.
The following examples and comparative run are provide~ to illustrate the invention but are not intended to limit the scope thereof.
Comparative Run A
This comparative run shows the inefEicacy of benzoyl chloride as a stahi]izer. A PAC polyol was reacted with tol~ene diisocyanate to form a prepolymer having an isocyanate content of 5 percent. The prepolymer CPR values were found according to the procedure mentioned above. Viscosity of the prepolymer after treatment is given in centipoises3 as measured with a Brookfield Viscometer Model RVTD. This machine is rotational viscometer containing various spindles3 34,982-F` -5--6-- ~32~72 previously cali~rated by the manu~acturer. The spindle is placed in ~he solution to be analyzed and rotated.
~`he viscosity is calculated by multiplying the RYM by the appropriate spindle calibraLion factor.
TABLE I
Prepolymer Prepolymer Viscoslty, cp Time Before _ CPR ~ Gela tion 1.76 instantaneous 1.4074,200 (74.2) 1 hour 0.9940,400 (40.4) 1 day 0.00633,000 (33) 1 day -2.0127,000 (27) 1-2 days -4.9824,000 (24) 1-2 days -7.9529,800 (29.8) 1-2 days -13.8941,200 (41.2) 1-2 days -31.3537,000 (37) 1-2 days -61.4126,800 (26.8) 1-2 days Yarious side reactions appear to have occurred, 25 including trimerization of the isocyanate, resulting in gelation.
34,982-F -6-..... _.. _ .
. ~ , . .
_7-~ ~ 32~772 In a second test described in Table II, PTSA
was used to treaL a quantity of PAC. The treated PAC
was then reacted with an excess oÇ toluene diisocyanate to form a prepolymer containing 5 percent isocyanate groups. Measurements were taken after 24 hours at 80C.
TABLE :[I
CPR of PAC Prepolymer Result 5.2 gelation 1.2 gelation 150.2 no gelation (stil l liq u id) -5.0 no gelation (still liquid) The first two runs evidence trimerization with the TDI, while the two runs at lower CPR show stability of the prepolymer made with a properly treated PAC.
Example 2 For a third test described in Table lII, more quantitative data was obtained by measuring % NC0 loss (a weight percent of the prepolymer). The percentage value is found by carrying out a dibutylamine reaction, followed by back titratin with HCl. Measurements were taken after 24 hours at 80~C.
34,982-F -7--8- ~32(~7f~
Table III
-CPR of PAC Acid /0 N_O Los-t 6.0Benzoyl chloride gela-tior -10 PTSA 0 . 04 1.7 MSA 0.01 Treatment or neutralization of the polyol in the latter two cases was sufficient to stop virtually any trimerization of the prepolymer As shown from the foregoing tables, l~AC polyol neutralization is accomplished to obtain a more useful prepolymer. While variations in the present process may be incorporated, the scope of the present disclosure is determined by the claims which follow.
-.g~r ~ ~4,982-F -8-~ !
Claims (11)
1. A method of stabilizing a prepolymer comprising the step of adding an effective amount of an organosulfonic acid to polyalkylene carbonate polyol to obtain a stabilized polyalkylene carbonate polyol.
2. The method of Claim 1 wherein the addition of acid proceeds until a negative controlled polymerization rate is obtained.
3. The method of Claim 2 wherein the acid is para-toluenesulfonic acid or methanesulfonic acid.
4. The method of Claim 1 wherein the acid is ratably added with stirring.
5. The method of Claim 4 wherein the step of adding acid is repeated until a negative controlled polymerization rate is measured for the polyalkylene carbonate polyol.
6. The method of Claim 4 wherein the stirring is conducted at ambient temperature.
7. The method of Claim 4 wherein stirring is done in a closed container.
34,982-F -9-
34,982-F -9-
8. The method of Claim 4 wherein the acid is mixed with a diluent before addition to the polyalkylene carbon polyol.
9. The method of Claim 1 wherein the acid is added before preparation of the prepolymer.
10. The method of Claim 1 wherein the acid is added after preparation of the prepolymer.
11. The product made by the practice of the method of Claim 4.
34,982-F -10-
34,982-F -10-
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US1495487A | 1987-02-17 | 1987-02-17 | |
| US014,954 | 1987-02-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1320772C true CA1320772C (en) | 1993-07-27 |
Family
ID=21768761
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000558306A Expired - Fee Related CA1320772C (en) | 1987-02-17 | 1988-02-05 | Neutralization of polyalkylene carbonate polyols for polyurethane prepolymer synthesis |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0363360A4 (en) |
| JP (1) | JPH02501830A (en) |
| AU (1) | AU605240B2 (en) |
| BR (1) | BR8807361A (en) |
| CA (1) | CA1320772C (en) |
| WO (1) | WO1988006150A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2058048T3 (en) * | 1992-03-24 | 1999-06-16 | Dow Chemical Co | NEW FINISHING PROCEDURE FOR HYDROXY-FUNCTIONAL POLYETERS. |
| TWI761404B (en) * | 2016-12-19 | 2022-04-21 | 德商科思創德意志股份有限公司 | Process for producing (cyclo) aliphatic polycarbonate polyols having low reactivity |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3770793A (en) * | 1970-05-15 | 1973-11-06 | American Cyanamid Co | Aminium and dimonium salts used as polymerization inhibitors of diallyl digylcol carbonate |
| US4448727A (en) * | 1976-03-22 | 1984-05-15 | General Electric Company | Color-stabilized halobisphenolethylene polycarbonates |
| AU536979B2 (en) * | 1982-04-26 | 1984-05-31 | Ppg Industries, Inc. | Polyol(allyl carbonate) composition |
| DE3231397A1 (en) * | 1982-08-24 | 1984-03-01 | Bayer Ag, 5090 Leverkusen | USE OF CARBONYL COMPOUNDS AND / OR HETEROANALOGIC CARBONYL COMPOUNDS AS A STABILIZING AGENT FOR SOLUTIONS CONTAINING PYROCARCOURED ACYLEDIUM CYLESTER AND POLYISUBYANITATE-ZONATE COMPOUNDS |
| US4528364A (en) * | 1984-04-19 | 1985-07-09 | The Dow Chemical Company | Removal of alkaline catalysts from polyether polyols and polyalkylene carbonate polyols |
| US4814428A (en) * | 1987-06-04 | 1989-03-21 | General Electric Company | Method of increasing the thermal stability of cyclic carbonate oligomers |
-
1988
- 1988-02-01 EP EP19880901720 patent/EP0363360A4/en not_active Withdrawn
- 1988-02-01 WO PCT/US1988/000285 patent/WO1988006150A1/en not_active Application Discontinuation
- 1988-02-01 JP JP50171588A patent/JPH02501830A/en active Pending
- 1988-02-01 BR BR888807361A patent/BR8807361A/en not_active Application Discontinuation
- 1988-02-05 CA CA000558306A patent/CA1320772C/en not_active Expired - Fee Related
- 1988-02-10 AU AU11498/88A patent/AU605240B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| AU605240B2 (en) | 1991-01-10 |
| AU1149888A (en) | 1988-08-18 |
| EP0363360A4 (en) | 1990-06-27 |
| JPH02501830A (en) | 1990-06-21 |
| EP0363360A1 (en) | 1990-04-18 |
| WO1988006150A1 (en) | 1988-08-25 |
| BR8807361A (en) | 1990-03-01 |
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