GB2076413A - Polyether polyol preparation - Google Patents

Abstract

Polyether polyols useful in making a polyisocyanurate polymer are prepared by oxyalkylating an alcohol by the catalytic addition of an alkylene oxide to said alcohol in presence of a catalyst selected from the group consisting of carbamate salts, aminophenols, hexahydro-s-triazines and tetrahydrooxadiazines.

Description

Polyol preparation This invention relates to the field of preparing polyether polyols. More particularly, this invention relates to the use of isocyanurate catalysts in promoting oxyalkylation of specific alcohols.

Alkylene oxide adducts of various alcohols, amino-alcohols, etc. are well known and widely used in a variety of industries. Such polyoxyalkylene polyhydric compounds are particularly useful in making polyurethane compositions and/or polyisocyanurate polymers. The polyether polyol reacts with a polyisocyanate in the presence of a catalyst to prepare the polymers, particularly in foam form. When a polyisocyanurate foam is desired, the polyol-polyisocyanate polymerization is carried out by resort two an isocyanurate group formation catalyst which is used to trimerize the isocyanate groups to form the isocyanurate linkages.

The polyether polyols are generally prepared by the catalytic addition of an alkylene oxide or mixture of alkylene oxides, either simultaneously or sequentially to an organic compound usually having at least two active hydrogen atoms. The alkoxylation catalyst may be alkaline, neutral or acid, with an alkaline catalyst, such as an alkali metal hydroxide being most preferred. In a commerical operation, the usual catalysts are either sodium hydroxide or potassium hydroxide.

However, alkoxylation catalysts of this type have a number of drawbacks. Paramount among these is the requirement that the base employed after the alkoxylation reaction is completed be neutralized.

The resultant salt must then be filtered from the polyol. This filtration step, of course, adds considerable cost and time to the overall process.

It would, therefore, be an advantage in the art if a catalyst were found which would reduce the just mentioned deficiency. It would be a further advantage if such portion of the catalyst which remains unused afterthe alkoxylation reaction could somehow be of further use in preparing polymer products which employ such polyether polyols.

Therefore, it becomes an object of the present invention to provide a method of making polyether polyols useful in preparing polyisocyanurate polymers, which polyether polyol method reduces the just discussed prior art drawback of employing conventional catalysts such as potassium hydroxide or sodium hydroxide. Other objects will appear hereinafter.

It has been found that the disadvantages of employing an alkali metal base catalyst normally used in preparing polyether polyols may be reduced by employing in said oxyalkylation process a catalyst selected from the group consisting of carbamate salts, aminophenols,hexahydro-s-triazines and tetrahydrooxadiazines. Use of such catalysts not only aids in effecting oxyalkylation of an alcohol initiator but, in addition, the so-produced polyether polyol then may be used as such in making polyisocyanurate polymers without further addition of catalysts of this type normally used to promote the trimerization of isocyanate groups to form isocyanurate linkages since the just-mentioned group of catalysts are knoin polyisocyanurate catalysts.As a minimum advantage the amount of polyisocyanurate catalyst required is reduced due to its being already present in the polyether polyol source.

The method of the invention basically follows prior art modes of making polyether polyols by oxyalkylating an alcohol through the catalytic addition of an alkylene oxide to said alcohol in presence of an oxyalkylating catalyst.

As said oxyalkylating catalyst, a catalyst of the type mentioned above normally is used to promote the trimerization of isocyanate groups to form isocyanurate linkages. Such catalyst of this type used in making polyisocyanurate polymers now has surprisingly been found here to be also useful in a conventional oxyalkylation reaction.

A number of benefits thus result from use of such isocyanurate catalyst in place of a conventional oxyalkylation catalyst such as an alkali metal hydroxide catalyst. Since the isocyanurate catalyst is soluble in the polyol produced, and no neutralization necessary, no subsequent filtration step is thus required. In addition, the final polyether polyol contains, of course, the isocyanurate catalyst used to promote the oxyalkylation reaction, and therefore, when subsequently employed to form a polyisocyanurate elastomer or foam requires addition of only small amounts of additional catalyst. In some cases, no further catalyst addition is required.

As noted above, preparation of a polyether polyol is well known in the art as evidenced, for example, by U.S. Patent Nos. 3,988,302; 3,190,927; 3,346,557 and other. The polyether polyols as prepared in the present invention are made by the catalytic addition through use of the particular catalysts mentioned here of an alkylene oxide or mixture of alkylene oxides, either simultaneously or sequentially to an organic compound having two or three active hydrogen atoms. Representative compounds ofthis type include polyhydric alcohols, such as ethylene glycol, propylene glycol, isomeric butylene glycols, 1,5-pentane diol, 1 ,6-hexane diol, glycerol, trimethylol propane, 1 ,2,6-hexane triol, diethylene glycol, dipropylene glycol, 1,1 -trimethylolethane, ethanolamine, diethanolamine, 2,(2-aminoethyl) ethanol, etc.

Alkylene oxides which may be employed in the preparation of the polyether polyols through the process of the present invention include ethylene oxide, propylene oxide, the isomeric normal butylene oxides, hexylene oxide, octylene oxide, dodecene oxide, methoxy and other alkoxy propylene oxides, styrene oxide and cyclohexene oxide.

Halogenated alkylene oxides may also be used, such as epichlorohydrin, epiiodohydrin, epibromohydrin, 3,3 - dichloropropylene oxide, 3 - chloro -1,2 - epoxypropane, 3 - chloro -1,2- epoxybutane, 1 - chloro 2,3- epoxybutane, 3,4- dichloro -1,2 - 1,2- epoxybutane, 1,4 - dichloro - 2,3 - epoxybutane, 1 - chloro - 2,3 - epoxybutane, and 3,3,3 - trichloropropylene oxide.

Mixtures of any of the above alkylene oxides may also be employed. Likewise, the polyether polyols can contain random addition, block addition or random and block addition. Preferred oxides are ethylene and propylene oxide or mixtures.

The amount of alkylene oxide added to tRe alcohol initiator may range over a wide range of about 1-100 moles of alkylene oxide per mole of initiator. More often, 1-50 moles of alkylene oxide are reacted per mole of initiator.

The temperature of reaction may range from about 50"C to about 200"C, and more often is 50-1 50"C.

Usually the polyether polyol produced by the method of the invention has a hydroxyl number of 50-1,000. The hydroxyl number is defined as the number of milligrams of potassium hydroxide required for the complete neutralization of the hyd rolysis product of the full acetylated derivative pre pared from one gram of polyol.

When a volatile alkylene oxide is employed, the reactions are normally conducted in a closed vessel at ambient pressure at the particular temperature employed. Thus, the reaction pressure here may range from atmospheric pressure up to a pressure of about 1,000 psig.

The amount of catalyst utilized may vary over a wide weight percentage range based on the weight of the alcohol reactant Usually an amount of catal yst ranging from about 0.01 to about 5 weight per cent is employed, based on the weight of the alcohol reactant. More often, the amount employed is 0.1-2%, and most often is 0.3-1 O/o.

The resultant polyether polyols then are used in a conventional manner in order to prepare isocyanu rate foams and other types of isocyanurate polym ers. Such polyisocyanurates may be made using the polyols of the invention according to methods of preparation described in U.S. Patent Nos. 4,026,836; 3,745,133; and 3,644,232, to name a few.

The invention will be illustrated further with respect to the following specific examples, which are given by way of illustration and not as limitations on the scope of this invention.

EXAMPLE 1 A five gallon kettle was charged with 10 Ibs. of trimethylolpropane and then heated to 1300C. It was held at 1300C for 112 hour while being purged with nitrogen. The reaction was then cooled to 90"C and 44.3 grams of DMP-30 [2,4,6-tri (dimethylaminomethyl)phenol, sold by Rohm and Haas Company] was added, followed by reheat ing the reaction mass to 130 C. Over a 1/2 hour period, 9.5 Ibs. of ethylene oxide was added, fol lowed by digestion for 1 hour at this temperature.

The reaction mass was cooled to 90"C and 8.7 grams of 2,6 - di - tertbutyl - p - cresol was added. It was then stripped at 100"C and 100 mm Hq vacuum for 15 minutes and discharged.

The polyol had a hydroxyl number of 646, pH of 12.70, and contained 0.069 meq. amine per gram of polyol.

EXAMPLE2 In accordance with Example 1, a 5 gallon kettle was charged with 5 Ibs. of trimethylolpropane and heated to 1300C. It was held at 1300C while purging with nitrogen for 1/2 hour and then cooled to 90"C.

44 grams of POLYCAT 41 [1,3,5 tris - (N,N dimethylaminopropyl) hexahydro - s - triazine sold ; by Abbott Laboratories] was added and the reaction mass reheated to 110 C. 4.75 Ibs. of ethylene oxide was added over a 25 minute period followed by digesting at 110"C forl hour.

The reaction mass was then cooled at 80"C and placed under 80mm Hg vaccuum for 112 hour and then discharged.

The polyol had an OH# of 631, pH of 13.3 and a total amine content of 0.152 meq. amine per gram polyol.

EXAMPLE 3 Here a 5 gallon kettle was charged with 2 Ibs. of glycerin and 10 grams of 1-2(hydroxyethyl)-3,5 bis(N, N-dimethylaminopropyll hexadydro-striazine. This was heated to 1200c and 4.3 Ibs. of ethylene oxide added. The reaction mass was digested for 1-112 hours at 120 C, vented and discharged. The polyol had a OHE of 569, pH of 12.95, and total amine of 0.049 meq./gram.

EXAMPLE 4 To a 1500 ml kettle was charged 500 grams of trimethylolpropane and 10 grams of 3,5 - bis(N,N' dimethylaminopropyl) - 1,3,5 -tetrahydroox- adiazine (I). The mixture was heated to 90"C then 475 grams of ethylene oxide was added over a 1-hour long period. The reaction was heated to 110"C and digested for 1-114 hours. It was then stripped at 80 mm Hg vac and 1 100C for 30 minutes. The product had an hydroxyl number of 652.

EXAMPLE5 The following foams were prepared by premixing the B-component, then adding the isocyanurate catalyst and rapidly mixing. The reaction was then poured into an open mold and allowed to rise.

TABLEl TABLE 1 B-component A B C polyol example 1 10.15 - polyol examplell 10.15 polyol example Ill - - 11.1 M & 'ST-452 1.0 1.0 1.0 POLYCAT 413 0.5 0.5 0.5 DC-1934 0.5 0.5 0.5 FllB(fluorocarbon) 12 12 12 MONDUR MR5 75.4 75.0 74.6 cream time(sec) 4 4 6 tack free time(sec) 15 60 15 rise time(sec) 25 60 30 1. 50% potassium octoate in a glycol solvent.

2. A product of Abbott Laboratories, 1,3,5 tris (N, N - dimethylaminopropyl) hexahydro-s- triazine.

3. Product of Dow Corning, a silicone.

4. A polyisocyanate product of Mobay Chemical Co., 2.7 functionality made by phosgenating the reaction product of aniline and formaldehyde.

Claims (10)

1. A method of preparing a polyether polyol useful in making a polyisocyanurate polymer, which comprises the steps of oxyalkylating an alcohol having a functionality of two orthree by the catalytic addition of an alkylene oxideto said alcohol in the presence of an oxyalkylating catalyst selected from carbamate salts, aminophenols, hexahydro-striazines and tetrahydrooxadiazines.

2. A method as claimed in Claim 1, wherein said oxyalkylating is carried out at a temperature of 50-200"C.

3. A method as claimed in any preceding claim, wherein said catalyst is employed in an amount ranging from about 0.1% to about 2% based on the weight of the alcohol reactant.

4. A method as claimed in any of claims 1 to 3, wherein said oxyalkylating catalyst is 2,4,6 tris(dimethylaminomethyl) phenol.

5. A method as claimed in any of claims 1 to 3, wherein said oxyalkylating catalyst is 1,3,5 -tris(N,N - dimethylaminopropyl) hexahydro-s-triazine.

6. A method as claimed in any of claims 1 to 3, wherein said oxyalkylating catalyst is 1 - (2 - hydroxyethyl) - 3,5, - bis (N,N - dimethylaminopropyl) hexa hydro-s-triazine.

7. A method as claimed in any of claims 1 to 6, wherein said oxyalkylating agent is ethylene oxide.

8. A method as claimed in any of claims 1 to 6, wherein said oxyalkylating agent is propylene oxide.

9. A method as claimed in any of claims 1 to 6, wherein said oxyalkylating agent is a mixture of propylene oxide and ethylene oxide.

10. A method of preparing a polyether polyol as claimed in Claim 1 and substantially as hereinbefore described with reference to any of the Examples.