EP0363360A1 - Neutralization of polyalkylene carbonate polyols for polyurethane prepolymer synthesis - Google Patents

Neutralization of polyalkylene carbonate polyols for polyurethane prepolymer synthesis

Info

Publication number
EP0363360A1
EP0363360A1 EP88901720A EP88901720A EP0363360A1 EP 0363360 A1 EP0363360 A1 EP 0363360A1 EP 88901720 A EP88901720 A EP 88901720A EP 88901720 A EP88901720 A EP 88901720A EP 0363360 A1 EP0363360 A1 EP 0363360A1
Authority
EP
European Patent Office
Prior art keywords
acid
prepolymer
polyalkylene carbonate
stirring
pac
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.)
Withdrawn
Application number
EP88901720A
Other languages
German (de)
French (fr)
Other versions
EP0363360A4 (en
Inventor
Anthony W. Mancusi, Iii
Samuel J. Washington
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dow Chemical Co
Original Assignee
Dow Chemical Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Dow Chemical Co filed Critical Dow Chemical Co
Publication of EP0363360A1 publication Critical patent/EP0363360A1/en
Publication of EP0363360A4 publication Critical patent/EP0363360A4/en
Withdrawn legal-status Critical Current

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

Definitions

  • Polyurethanes 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 takes 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.
  • polyurethanes are a general class of materials which can be prepared via many different routes, at least in principle.
  • industrial practicalities dictate a preferred approach based on, for example, feedstock availability and ease of processing.
  • condensation polymerization of bischloroformates with diamines will yield polyurethanes, but the universal large scale practice calls for condensation of diisocyanates with diols.
  • diisocyanates with diols.
  • TDI 2,4-toluene diisocyanate
  • P0l3rurethar.es are notoriously defiant regarding fabrication.
  • the production of a good, useful foam object involves precise control over the size and distribution of the hollow voids, or cells in the product.
  • An open cell foam would make a poor life preserver while a closed cell foam would make a poor sponge.
  • Volumes have been written on the problems associated with polyurethane processing, and the subject is generally beyond the scope of this discussion, except as relates to prepolymer stabilization.
  • the present invention provides for 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.
  • TDI invariably benzoyl chloride
  • benzoyl chloride simply does not stabilize PAC prepolymers -- even when added in large excess.
  • Benzoyl 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.
  • benzoyl chloride does not provide a stable prepolymer.
  • the present invention 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 polyol neutralizes the residual base catalyst, preventing side reactions, including trimerization of the TDI.
  • the PAC polyol requires initial characterization with respect to its "CPR" count.
  • 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 in 100 ml of methanol to be titrated with 0.01 N HCl, where the ten times the acid volume is equal to the CPR value. See “Urethane Polyether Prepolymers and Foams: Influence of Chemical and Physical variables on Reaction Behavior” by Schotten, Schuhmann, and TenHoor, in J. Chem. Eng. Data. 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).
  • MSA methanesulfonic acid
  • PTSA para-toluenesulfonic acid
  • HCl has been found to be an undesirable acid. But it is equally clear that virtually any organosulfonic acid will perform satisfactorily.
  • 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 60°F (15°C) to 95°F (35°C), in a closed container.
  • the acid is added to the PAC with 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 one liter of
  • the acid (preferably the PAC polyol itself) is added to the acid, perhaps 10 to 50 to one of acid.
  • the acid is added over time with stirring. If the residual base species in the PAC is known before treatment, the amount of acid can be calculated. On the other hand, acid can be ratably added to achieve base neutralization 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 of 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.
  • This comparative run shows the inefficacy of benzoyl chloride as a stabilizer.
  • a PAC polyol was reacted with toluene 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 centipoises, as measured with a Brookfield Viscometer Model RVTD. This machine is rotational viscometer containing various spindles, previously calibrated by the manufacturer. The spindle Is placed in the solution to be analyzed and rotated. The viscosity is calculated by multiplying the RPM by the appropriate spindle calibration factor.
  • 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.

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)
  • Polyesters Or Polycarbonates (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

Un procédé de stabilisation de prépolymères applicable à des polyols de carbonate de polyalkylène comprend l'adjonction d'une petite quantité d'un acide organosulfonique que l'on agite jusqu'à achever la neutralisation basique, en d'autres termes jusqu'à atteindre un taux négatif de polymérisation contrôlée, mesuré par un test de détermination du taux de polymérisation contrôlée.A process for stabilizing prepolymers applicable to polyalkylene carbonate polyols comprises adding a small amount of an organosulfonic acid which is stirred until complete basic neutralization, in other words until reaching a negative rate of controlled polymerization, measured by a test to determine the rate of controlled polymerization.

Description

NEUTRALIZATION OF POLYALKYLENE CARBONATE POLYOLS FOR POLYURETHANE PREPOLYMER SYNTHESIS
Polyurethanes 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 takes 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, polyurethanes 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 with 1,4-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.
P0l3rurethar.es are notoriously defiant regarding fabrication. The production of a good, useful foam object involves precise control over the size and distribution of the hollow voids, or cells in the product. An open cell foam would make a poor life preserver while a closed cell foam would make a poor sponge. Volumes have been written 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 mold. The alternative process calls for controlled synthesis of a prepolymer, i.e., a short chain polyurethane intermediate. The use of the intermediate 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 improvements. This patent addresses the practical problem of prepolymer stability. In particular, the present invention provides for 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 acid 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. Benzoyl 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 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 polyol neutralizes the residual base catalyst, preventing side reactions, including trimerization of the TDI.
Specifically, the PAC polyol requires initial characterization with respect to its "CPR" count. "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 in 100 ml of methanol to be titrated with 0.01 N HCl, where the ten times the acid volume is equal to the CPR value. See "Urethane Polyether Prepolymers and Foams: Influence of Chemical and Physical variables on Reaction Behavior" by Schotten, Schuhmann, and TenHoor, in J. Chem. Eng. Data. 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, HCl has been found to be an undesirable acid. But it is equally clear that virtually any organosulfonic acid will perform satisfactorily.
Furthermore, some acids react directly with TDI, e.g., H2SO4 AND PTSA; so it is necessary to treat the PAC polyol with the acid prior to its reaction with a polyisocyanate.
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 60°F (15°C) to 95°F (35°C), in a closed container. The acid is added to the PAC with 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 one liter of
PAC, acid is added with stirring in an effective amount of just a few ppm, or only a few drops. Since only a small amount of acid is needed, a neutral diluent
(preferably the PAC polyol itself) is added to the acid, perhaps 10 to 50 to one of acid. The acid is added over time with stirring. If the residual base species in the PAC is known before treatment, the amount of acid can be calculated. On the other hand, acid can be ratably added to achieve base neutralization 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 of 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 provided to illustrate the invention but are not intended to limit the scope thereof.
Comparative Run A
This comparative run shows the inefficacy of benzoyl chloride as a stabilizer. A PAC polyol was reacted with toluene 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 centipoises, as measured with a Brookfield Viscometer Model RVTD. This machine is rotational viscometer containing various spindles, previously calibrated by the manufacturer. The spindle Is placed in the solution to be analyzed and rotated. The viscosity is calculated by multiplying the RPM by the appropriate spindle calibration factor.
TABLE I
Prepolymer
Prepolymer Viscosity, Time Before
CPR CP (Pa s) Gelation
1.76 instantaneous
1.40 74,200 (74. 2) 1 hour
0.99 40,400 (40. 4) 1 day
0.006 33,000 (33) 1 day
-2.01 27,000 (27) 1-2 days
-4.98 24,000 (24) 1-2 days
-7.95 29,800 (29. 8) 1-2 days
-13.89 41,200 (41. 2) 1-2 days
-31-35 37,000 (37) 1-2 days
-61.41 26,800 (26. 8) 1-2 days
Various side reactions appear to have occurred, Including trimerization of the isocyanate, resulting in gelation.
Example 1
In a second test described in Table II, PTSA was used to treat a quantity of PAC. The treated PAC was then reacted with an excess of toluene diisocyanate to form a prepolymer containing 5 percent isocyanate groups. Measurements were taken after 24 hours at 80°C. TABLE II
CPR of PAC PREpolymer Result
5 . 2 gelation
1 .2 gelation
0 . 2 no gelation (still liquid)
-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 III, more quantitative data was obtained by measuring %NCO 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.
TABLE III Prepolymer
CPR of PAC Acid % NCO Lost
6.0 Benzoyl chloride gelation
-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, PAC 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.

Claims

1. A method of stabilizing a prepolymer comprising the step of adding an effective amount of an acid to polyalkylene carbonate polyol to obtain a stabilized polyalkylene carbonate polyol.
2. The method of Claim 1 wherein the acid is an organosu l f oni c acid.
3. The method of Claim 2 wherein the addition of acid proceeds until a negative controlled polymerization rate is obtained.
4. The method of Claim 3 wherein the acid is para-toluenesulfonic acid or methanesulfonic acid.
5. The method of Claim 1 wherein the acid is rateably added with stirring.
6. The method of Claim 5 wherein the step of adding acid is repeated until a negative controlled polymerization rate is measured for the polyalkylene carbonate polyol.
7. The method of Claim 5 wherein the stirring is conducted at ambient temperature.
8. The method of Claim 5 wherein the stirring is accomplished with a stirring means.
9. The method of Claim 8 wherein stirring is done in a closed container.
10. The method of Claim 5 wherein the acid is mixed with a diluent before addition to the polyalkylene carbonate polyol.
11. The method of Claim 1 wherein the acid is added before preparation of the prepolymer.
12. The method of Claim 1 wherein the acid is added after preparation of the prepolymer.
13. The product made by the practice of the method of Claim 5.
EP19880901720 1987-02-17 1988-02-01 Neutralization of polyalkylene carbonate polyols for polyurethane prepolymer synthesis. Withdrawn EP0363360A4 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US1495487A 1987-02-17 1987-02-17
US14954 1987-02-17

Publications (2)

Publication Number Publication Date
EP0363360A1 true EP0363360A1 (en) 1990-04-18
EP0363360A4 EP0363360A4 (en) 1990-06-27

Family

ID=21768761

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19880901720 Withdrawn EP0363360A4 (en) 1987-02-17 1988-02-01 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)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE590131T1 (en) * 1992-03-24 1994-12-22 Dow Chemical Co NEW FINAL TREATMENT PROCESS FOR HYDROXY-FUNCTIONAL POLYTHETHERS.
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)

* Cited by examiner, † Cited by third party
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

Also Published As

Publication number Publication date
EP0363360A4 (en) 1990-06-27
AU605240B2 (en) 1991-01-10
WO1988006150A1 (en) 1988-08-25
CA1320772C (en) 1993-07-27
AU1149888A (en) 1988-08-18
BR8807361A (en) 1990-03-01
JPH02501830A (en) 1990-06-21

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