Method for making propylene oxide/ethylene oxide copolymers using double metal cyanide catalysts, and copolymers so made

Abstract

Random poly(propylene oxide-co-ethylene oxide) polymers are made by polymerizing a mixture of propylene oxide and a small amount of ethylene oxide in the presence of a starter and a double metal cyanide catalyst complex, and then feeding in a mixture of propylene oxide and ethylene oxide while increasing the ethylene oxide concentration in the mixture to at least 90%. This produces a polyol suitable for making high resiliency polyurethane foam without need for adding an ethylene oxide cap.

Claims

1. A random poly(propylene oxide-co-ethylene oxide) polymer having a hydroxyl equivalent weight of 1500 to 3000, the random polymer comprising one or more polyether chains extending from the residue of a hydroxyl-containing starter compound having a hydroxyl equivalent weight of up to 175, wherein such polyether chain(s) include i) an internal propylene oxide-co-ethylene oxide block that contains 95 to 99% by weight polymerized propylene oxide, 1 to 5% by weight polymerized ethylene oxide and no more than 2% by weight of other copolymerized monomers, based on the weight of the internal propylene oxide-co-ethylene block, and ii) a terminal propylene oxide-co-ethylene oxide block that contains 30 to 75% polymerized ethylene oxide, 25 to 70% by weight polymerized 1,2-propylene oxide and no more than 2% by weight of other copolymerized monomers, wherein: the internal propylene oxide-co-ethylene oxide block or blocks constitute 50 to 69% of the weight of the random poly(propylene oxide-co-ethylene oxide) polymer; the external propylene oxide-co-ethylene oxide block or blocks constitute 30 to 40% of the weight of the random poly(propylene oxide-co-ethylene oxide) polymer; the internal and external blocks together constitute at least 90% of the weight of the random poly(propylene oxide-co-ethylene oxide) polymer; 40 to 55% of the hydroxyl groups of the poly(propylene oxide-co-ethylene oxide) polymer are primary hydroxyls, polymerized ethylene oxide constitutes 10 to 25% of the weight of the poly(propylene oxide-co-ethylene oxide) polymer, the residue of the starter compound constitutes 1 to 10% of the weight of the random poly(propylene oxide-co-ethylene oxide) polymer, and the internal blocks, external blocks and residue of the starter compound together constitute 100% of the weight of the random poly(propylene oxide-co-ethylene oxide) polymer.

2. The random polypropylene oxide-co-ethylene oxide) polymer of claim 1 wherein 45 to 55% of the hydroxyl groups are primary.

3. The random poly(propylene oxide-co-ethylene oxide) polymer of claim 2 which has a hydroxyl equivalent weight of 1500 to 2200.

4. The random poly(propylene oxide-co-ethylene oxide) polymer of claim 2 in which the starter compound has 2 to 4 hydroxyl groups per molecule.

5. The random poly(propylene oxide-co-ethylene oxide) polymer of claim 2 in which the starter compound has 3 hydroxyl groups per molecule.

6. A method for making a polyurethane foam having a resiliency of at least 50% on the ASTM D3574 ball rebound test and a foam density of 20 to 80 kg/m.sup.3, comprising reacting, in one or more steps and in the presence of at least one foam-stabilizing surfactant and at least one catalyst for the reaction of a hydroxyl group with an isocyanate group, polyurethane-forming reactants comprising one or more polyol(s) having a hydroxyl equivalent weight of at least 1000 g/mol, at least one polyisocyanate and water, wherein (I) the polyol(s) having a hydroxyl equivalent weight of at least 1000 constitute at least 55% by weight of the polyurethane-forming reactants, and (II) at least 20% by weight of said polyol(s) having a hydroxyl equivalent weight of at least 1000 is one or more random poly(propylene oxide-co-ethylene oxide) polymers of claim 1.

7. A process for making a polyether polyol, comprising: a) activating a DMC catalyst complex in the presence of at least one hydroxyl-containing starter having a hydroxyl equivalent weight of up to 175 and a mixture of 95 to 99% by weight 1,2-propylene oxide, 1 to 5% by weight ethylene oxide and 0 to 2% by weight of other copolymerizable monomers; b) polymerizing an oxide mixture containing 1,2-propylene oxide and ethylene oxide onto the hydroxyl-containing starter(s) in the presence of the activated DMC catalyst to produce a poly(propylene oxide-co-ethylene oxide) polymer having one or more terminal hydroxyl groups; wherein i) in a first stage, the oxide mixture introduced to the reaction contains 95 to 99% by weight 1,2-propylene oxide, 1 to 5% by weight ethylene oxide and 0 to 2% by weight of other copolymerizable monomers, until such time as 55 to 75% of the total amount of the oxide mixture is polymerized, and the remainder of the oxide mixture is thereafter introduced to the reaction in a second stage by feeding it to the reaction under polymerization conditions as an oxide feed in which the concentration of the ethylene oxide in the oxide feed is continuously or intermittently increased until the oxide feed contains 90 to 100% by weight ethylene oxide, 0 to 10% by weight 1,2-propylene oxide and 0 to 2% by weight of other copolymerizable monomers, based on the weight of the oxide feed, ii) the oxide feed is discontinued after the concentration of ethylene oxide in the oxide feed reaches 90% but before or at the same time as the concentration of ethylene oxide in the oxide feed reaches 100% by weight, and the reaction mixture is thereafter digested, and further wherein iii) the polypropylene oxide-co-ethylene oxide) polymer has a hydroxyl equivalent weight of 1500 to 3000, contains 10 to 25% by weight polymerized ethylene oxide, and contains 40 to 55% primary hydroxyl groups.

8. The process of claim 7, wherein in the first stage of step b), the oxide mixture is fed continuously or intermittently to the reaction at a rate sufficient to maintain a level of unreacted oxides in the reaction vessel of 1 to 6% by weight.

9. The process of claim 8, wherein in the second stage of step b), the oxide feed is at a rate sufficient to maintain a level of unreacted oxides in the reaction vessel of 1 to 6% by weight.

Description

EXAMPLES 1-5 AND COMPARATIVE POLYOLS A-C

(1) Polypropylene oxide-co-ethylene oxide) polymer Examples 1 and 2 are prepared in the following manner:

(2) 691 g of a 450 molecular weight (150 equivalent weight) propoxylated glycerin and 225 mg of a zinc hexacyanocobaltate catalyst complex are introduced into a 10 liter reactor. The reactor is heated to 160 C. and pressurized with nitrogen. 77 g of a blend of 98% 1,2-propylene oxide (PO) and 2% ethylene oxide (EO) are fed to the reactor. The reactor pressure is monitored and when the pressure drops, indicating that the catalyst has become activated, 4316 g of a mixture of 98% PO and 2% EO is feed to the reactor over a period of 185 minutes. Then, the feed is continued for another 105 minutes, while linearly increasing the EO concentration in the feed to 100%, until an additional 1232 g of EO and 1184 g of PO are added. The feed is discontinued when the ethylene oxide concentration reaches 100%, and the reactor contents are digested for 20-30 minutes to consume residual monomers.

(3) The resulting polypropylene oxide-co-ethylene oxide) polymers each contain 17.6% polymerized ethylene oxide. Each polymer contains polyether chains made up of a short polypropylene oxide) segment contributed by the initiator, an internal block which has 2% polymerized ethylene oxide and 98% polymerized propylene oxide, and an external block that contains, on average, 51% by weight polymerized ethylene oxide. The internal blocks constitute about 58.6% of the weight of the polymer. The external blocks constitute about 32.2% of the weight of the polymer. The residue of the initiator constitutes about 9.2% of the weight of the polyether.

(4) Example 1 has a hydroxyl number of 34.5, which corresponds to a hydroxyl equivalent weight of 1626. It contains 50.4% primary hydroxyl groups. Its Brookfield viscosity at 25 C. is 1000 cps. It is slightly hazy in appearance at 60 C.

(5) Example 2 has a hydroxyl number of 34.9, which corresponds to a hydroxyl equivalent weight of 1607. It contains 42.3% primary hydroxyl groups. Its viscosity at 25 C. is 1010 cps. It is slightly hazy in appearance at 60 C.

(6) Comparative Polyol A is made in the same manner as Examples 1 and 2, except that after the digestion step, a pure ethylene oxide feed constituting 1.7% of the total weight of alkylene oxides is feed to the reactor, followed by a second digestion step. This produces a polyol having a hydroxyl number of 35.9, which corresponds to a hydroxyl equivalent weight of 1563. Comparative Polyol A contains 48.4% primary hydroxyl groups. Its viscosity at 25 C. is 1190 cps, which is almost 20% greater than either of Examples 1 and 2. Comparative Polyol A has a highly turbid appearance at 60 C.

(7) Examples 3-6 are made in the same general manner as Examples 1 and 2, except that after the initial feed of 98% PO and 2% EO is completed, the remainder of the alkylene oxides are added more slowly, over a period of 190 minutes, again with a linear increase in ethylene oxide concentration during that time.

(8) Examples 3-6 have hydroxyl numbers of 34.1 to 35.6, which correspond to hydroxyl equivalent weights of 1573 to 1635. They contain 40.3 to 42.8% primary hydroxyl groups. The viscosity at 25 C. is only 942-967 cps. They are even less hazy in appearance at 60 C. than Examples 1 and 2.

(9) Comparative Polyol B is made in the same manner as Examples 3-6, except that after the digestion step, a pure ethylene oxide feed constituting 3% of the total weight of alkylene oxides is feed to the reactor, followed by a second digestion step. This produces a polyol having a hydroxyl number of 35.1, which corresponds to a hydroxyl equivalent weight of 1598. Comparative Polyol B contains 51% primary hydroxyl groups. Its viscosity at 25 C. is 1210 cps, which is about 25% greater than Examples 3-6. Comparative Polyol B is very turbid in appearance at 60 C.

(10) Comparative Polyol C is made in the same manner as Comparative Polyol B, except the pure ethylene oxide feed constitutes 1.7% of the total weight of alkylene oxides is feed to the reactor. This produces a polyol having a hydroxyl number of 35, which corresponds to a hydroxyl equivalent weight of 1603. Comparative Polyol C contains 50% primary hydroxyl groups. Its viscosity at 25 C. is 1210 cps, which is about 25% greater than Examples 3-6, and is very turbid in appearance at 60 C.

(11) High resiliency polyurethane foams are made using poly(propylene oxide-co-ethylene oxide) polymer Examples 1, 2 and 5. Comparative foam F-A does not contain a poly(propylene oxide-co-ethylene oxide) polymer of the invention, being made instead exclusively with ethylene oxide-capped polyols that are the product of anionic polymerization. Foams are made by mixing the ingredients listed in Table 1 through low-pressure foaming equipment at room temperature and dispensing the resulting reaction mixture into an open container where it rises against its own weight to form a high resiliency slabstock polyurethane foam. Core density of the cured foam is measured according to ISO 845-88 and foam resiliency is measured according to ASTM D3574.

(12) Polyol A is a nominally trifunctional ethylene oxide-capped poly(propylene oxide) having a hydroxyl equivalent weight of 2000 g/mol, made in an anionic polymerization process with a potassium hydroxide catalyst.

(13) The Cell Opener is a nominally trifunctional copolymer of a major amount of ethylene oxide and a minor amount of propylene oxide. It has a hydroxyl equivalent weight of 1680 g/mol, and is made in an anionic polymerization with a potassium hydroxide catalyst.

(14) The Catalyst Mixture is a mixture of commercial solutions of triethylene diamine, (2-dimethylaminoethyl)ether and stannous octoate.

(15) The Crosslinkers are a mixture of diethanolamine and a commercial product sold by Evonik as Ortegol 204.

(16) TABLE-US-00001 TABLE 1 F-A* Foam 1 Foam 2 Foam 3 Foam 4 Ingredient Parts by Weight Polyol A 95 75 75 45 75 Cell Opener 5 5 5 5 5 Polyol Ex. 1 0 20 0 0 0 Polyol Ex. 2 0 0 20 50 0 Polyol Ex. 5 0 0 0 0 20 Crosslinkers 2.5 2.5 2.5 2.5 2.5 Catalyst Mixture 0.25 0.25 0.25 0.25 0.25 Silicone Surfactant 0.4 0.4 0.4 0.4 0.4 Toluene diamine (80% 2,4- 41.17 41.34 41.34 41.60 41.36 isomer) (to 100 Index) Foam Density, kg/m.sup.3 31.2 32.7 32.3 31.9 33.8 Resiliency, % 51 53 50 51 55 *Not an example of this invention.

(17) When substituting as much as 50% of the polyols in this formulation with the poly(propylene oxide-co-ethylene oxide) polymer of the invention, good quality foam having properties essentially unchanged from the control are obtained.