JPH0637554B2 - Polyether polyol manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a process for producing a novel polyether polyol.

(Prior Art and Problems Thereof) Polyether polyols are formed by adding a alkylene oxide to a polyhydroxy compound as a starting material and used for various purposes. Among them, the polyether polyol having a polyhydroxy compound having a functionality of 3 or more as a starting material has a hydroxyl group capable of participating in a three-dimensional reaction and is further useful. However, in reality, it is difficult to form a polyether polyol starting from a hydroxy compound having 4 to 8 hydroxyl groups. The polymerization reaction for forming a polyether polyol is usually carried out in a solution because it is easy to control the reaction, but all the substances necessary for the reaction are dissolved and there are few solvents inert to the polymerization reaction.

Canadian Patent No. 1,118,417 proposes to use a hydrophilic solvent such as N-methylpyrrolidone or N-methylacetamide for the polyether polyol formation reaction. However, in this patent, the reaction is slow due to the use of an amine-based catalyst, and the molecular weight is 900 to 1200.
It is difficult to obtain a high molecular weight polymer.

Japanese Unexamined Patent Publication (Kokai) No. 58-15933 discloses that an alkali metal hydroxide is used as a catalyst and once reacted in water to form a low molecular weight nucleus, which is further chain-extended in the second step. There is. However, since water is used as a solvent, a side reaction product of water and an alkylene oxide is generated, and it is extremely difficult to completely remove this.

(Details of the Invention) The present inventors have found that a useful polyether polyol having a higher molecular weight than the above-mentioned Canadian patent can be obtained by using a special alkali metal catalyst.

That is, the present invention is a polyether characterized by reacting a polyhydroxy compound and an alkylene oxide in an aprotic solvent in the presence of an alkali metal catalyst obtained by the reaction of an alkali metal hydroxide and a cycloalkapolyene. A method for producing a polyol is provided.

Alkali metal hydroxides have high catalytic activity and are advantageous catalysts for forming polyether polyols. However,
This hydroxide does not dissolve in the aprotic solvent used in the present invention, especially N-methylpyrrolidone. In the present invention, the alkali metal hydroxide is in a form that can be dissolved in an aprotic solvent. For example, when potassium hydroxide and cyclopentadiene are adopted, the following reaction proceeds.

This compound (A) is solid and exhibits strong alkalinity when dissolved in an aprotic solvent such as N-methylpyrrolidone.

The alkali metal catalyst used in the production method of the present invention is obtained by reacting an alkali metal hydroxide with a cycloalkapolyene. This reaction usually takes place by mixing the two, but may be heated if necessary. Examples of alkali metal hydroxides include potassium hydroxide, sodium hydroxide, lithium hydroxide, rubidium hydroxide and the like. Preferred are sodium hydroxide and potassium hydroxide.
Cycloalkapolyene usually has an unsaturated group in the ring, for example, cyclopentadiene, cyclooctadiene,
Cyclododecatriene and the like are preferable, but those having an unsaturated group outside the ring, for example, methylenevinylcyclopentane are also included in the cycloalkapolyene of the present invention.

The formation reaction of the polyether polyol is carried out in the presence of the alkali catalyst obtained by the above reaction. The reaction is carried out in an aprotic solvent. The use of a solvent other than the aprotic solvent is not preferable because a side reaction product is formed by the reaction with the alkylene oxide. The aprotic solvent preferably has the following formula.

[Wherein R ₁ is hydrogen or an alkyl group having 1 to 3 carbon atoms,
R ₂ or R ₃ are the same or different and each is an alkyl group having 1 to 3 carbon atoms, and R ₁ and R ₂ or R ₁ and R ₃ may form a cyclic group. A typical example of the aprotic solvent satisfying the formula (I) is N.
-Methylpyrrolidone, dimethylacetamide, dimethylformamide and the like. Most preferred is N-methylpyrrolidone. Examples of aprotic solvents other than the above formula (I) include dimethylsulfoxide, dimethylacetamide, dimethylformamide and the like. The amount of the aprotic solvent used is 5 to 70% by weight, preferably 10 to 50% by weight, based on the total amount of the polymerization solution. Although it may be used in excess of the above upper limit, it takes time to remove the solvent.

The polyhydroxy compound used in the present invention is preferably solid at room temperature, but may be applied to diols, triols and the like which are liquid at room temperature. Examples of polyhydroxy compounds that can be used are diols such as ethylene glycol, dipropylene glycol, 1,4-butanediol, propylene glycol, diethylene glycol and the like; triols such as trimethylolpropane, glycerol and the like; tetraol and the like, for example Pentaerythritol; hexaols such as D-sorbitol, dipentaerythritol; octaols such as sucrose and lactose. Sucrose is most preferred due to its high functionality and low cost.

Any known alkylene oxide may be used. Examples of the alkylene oxide include ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide and 2,3-butylene oxide. Most preferred are ethylene oxide and propylene oxide. When water is contained in the alkylene oxide, a side reaction occurs, so that it may be removed by a known method. The amount of alkylene oxide added varies greatly depending on the chain length of the polyether polyol, that is, the molecular weight or OH value. The preferred molecular weight of the polyether polyol is 500 to
10,000, preferably 700 to 8,000,
The OH value is 10 to 650, preferably 15 to 300. Therefore, the polyalkylene oxide is added within this range.

The polymerization reaction is carried out by dropping or blowing an alkylene oxide into an aprotic solvent (including a polyhydroxy compound and an alkali catalyst obtained by the above reaction) heated under normal pressure or under pressure. Reaction temperature is usually 10
The temperature is 0 to 160 ° C, preferably 110 to 150 ° C. 1
If the temperature is 00 ° C. or lower, the polymerization reaction will be delayed, but side reactions will be suppressed. In other words, a product having a high number of functional groups is obtained. Therefore, when a polymer having a high number of functional groups is required, it is meaningful to polymerize under pressure and heating at a temperature of 100 ° C. or lower, particularly 70 to 95 ° C. When the reaction temperature exceeds 160 ° C., the side reaction in which the terminal hydroxyl group is converted into an unsaturated group becomes remarkable. When the unsaturated group formation reaction occurs, at the same time, the number of functional groups in the product is significantly lost. Unreacted monomer is recovered and used again in the reaction.

After completion of the polymerization reaction, the catalyst is removed with an ion exchange resin substituted with an aprotic solvent used in advance, and then the solvent is removed for purification.

(Effect of the Invention) The polyether polyol of the present invention is polymerized by using a specific alkali catalyst, and a high-functionality polyhydroxy compound, particularly a polymer having a high molecular weight can be obtained from sucrose. Further, since a solvent capable of reacting with alkylene oxide such as water is not used, side reaction products are rarely mixed as impurities. Furthermore, since the reaction is carried out using a hydrophilic organic solvent, purification can be easily carried out using an ion exchange resin. It has one process and is simplified. Further, it is possible to easily increase the molecular weight.

Polyfunctional polyether polyols, especially sucrose-based polyether polyols, are highly advantageous for forming polyurethanes obtained by reacting with isocyanates. In the case of a polyfunctional polyether polyol, thermal stability is extremely good. In the case of a polyether polyol having a high molecular weight, the resulting polyurethane has high impact resistance.

(Examples) The present invention will be described in more detail with reference to Examples.

Example 1 (Preparation of catalyst) 7.95 g of cyclopentadiene was added to 4.56 g of powdered KOH, and the mixture was reacted by shaking at room temperature for about 1 hour. After the reaction, the mixture was filtered to collect a blackish brown solid (catalyst).

(Polymer Polymerization) 4.2 g of the above catalyst was added to 500 m of N-methylpyrrolidone and stirred to dissolve. Subsequently, 85.5 g of sucrose was added, and the temperature was raised with stirring to dissolve at about 90 ° C. When the solution temperature reached about 130 ° C, propylene oxide 16
00m was added dropwise over about 4 hours. About 430 m of unreacted propylene oxide was trapped. After completion of dropping, the mixture was cooled to room temperature and passed through an ion exchange resin which had been previously substituted with N-methylpyrrolidone. Subsequently, distillation was performed at about 120 ° C. under a vacuum of 2 mmHg for 2 hours using an evaporator. The obtained polymer was a tan liquid with M _n = 4,1.
00, _Mw / _Mn = 1.12, OH value = 107, [C = C] =
It had 4.0 mol% / mol of [OH]. The above characteristic values were measured with a VPO (Vaper pressure osmosis) molecular weight meter manufactured by Hitachi, Ltd. Also, [C = C] was obtained by the Wij method.

Example 2 4.0 g of the catalyst obtained in the same manner as in Example 1 was added to 500 m of N-methylpyrrolidone and dissolved by stirring. Subsequently, 68 g of pentaerythritol was added, the temperature was raised with stirring, and the mixture was dissolved at about 80 ° C. The solution was heated to about 140 ° C. Next, about 1500 m of propylene oxide was added dropwise over about 3 hours. Unreacted propylene oxide about 300m
Was recovered. After completion of dropping, the mixture was cooled to room temperature and passed through an ion exchange resin which had been previously substituted with N-methylpyrrolidone. Subsequently, the solvent was removed by distillation using an evaporator at about 120 ° C. under a vacuum of 2 mmHg for 2 hours. The obtained polymer was yellowish brown and had M _n = 2100 and M _w / M _n = 1.1.
0, OH value = 106, [C = C] = 2.5 mol% / mol of
It had an [OH].

COMPARATIVE EXAMPLE 1 4.2 g of powdered KOH was added to 500 m of N-methylpyrrolidone.
And stirred. The solution was yellowish brown, but KOH was hardly dissolved. Next, 85.5 g of sucrose was added, and the temperature was raised to about 140 ° C. with stirring. Sucrose melted at about 90 ° C, but KOH did not melt and remained granular. When 500 m of propylene oxide was added dropwise as it was for about 2 hours, a large amount of precipitate was generated.

N-methylpyrrolidone 50 was added to the autoclave vessel of Example 35.
0 g of the catalyst of Example 1 (4.2 g) was added and dissolved by stirring. Subsequently, 85.5 g of sucrose was added and the nitrogen was sufficiently replaced, and then the temperature was raised with stirring (nitrogen pressure 2 kg / c.
m ² ). Sucrose melted at about 90 ° C. Temperature is 95 ℃
While maintaining at 1, 1,600 m of propylene oxide was added dropwise over about 8 hours using a high-pressure injection metering pump. After completion of dropping, the reaction was further continued for about 1 hour in order to complete the reaction. After the reaction, the mixture was cooled to room temperature and the catalyst was removed through an ion exchange resin which had been previously substituted with N-methylpyrrolidone. Then, using an evaporator,
It was distilled at 20 ° C. under a vacuum of 2 mmHg for 2 hours. The obtained polymer was a yellowish brown liquid with M _n = 5,100 and M _w / M _n = 1.1.
3, OH value = 84, [C = C] = 2.5 mol% / mol of [O
H].

Example 4 68 g of pentaerythritol was added instead of sucrose, and pentaerythritol was dissolved at about 80 ° C. An experiment was conducted in the same manner as in Example 3 except that 1600 m of propylene oxide was added dropwise over about 6 hours and the reaction was terminated by heating for 1 hour after the completion of the addition. The resulting polymer has M _n =
2,600, _Mw / _Mn = 1.15, OH number = 84, [C =
C] = 1.4 mol% / mol of [OH].

Example 5 91 g of D-sorbitol was added instead of sucrose,
D-sorbitol dissolved at about 70 ° C. An experiment was conducted in the same manner as in Example 2 except that 1200 m of propylene oxide was added dropwise over about 4 hours and the reaction was terminated by heating for 1 hour after the completion of the addition. The polymer obtained has M _n = 2,1
00, _Mw / _Mn = 1.12, OH value = 156, [C = C] =
It had 0.6 mol% / mol of [OH].

Claims (7)

[Claims] 1. A polyether characterized in that a polyhydroxy compound is reacted with an alkylene oxide in an aprotic solvent in the presence of an alkali metal catalyst obtained by the reaction of an alkali metal hydroxide with a cycloalkapolyene. Manufacturing method of polyol. 2. The method according to claim 1, wherein the polyhydroxy compound has 4 to 8 hydroxyl groups. 3. The method according to claim 2, wherein the polyhydroxy compound is sucrose. 4. The method according to claim 1, wherein the alkali metal catalyst is a reaction product of potassium hydroxide and cyclopentadiene. 5. The process according to claim 1, wherein the alkali metal catalyst is used in an amount of 1 to 10 mol% relative to 1 mol of the polyhydroxy compound. 6. The aprotic solvent is of the formula [Wherein R ₁ is hydrogen or an alkyl group having 1 to 3 carbon atoms,
R ₂ or R ₃ are the same or different and each is an alkyl group having 1 to 3 carbon atoms, and R ₁ and R ₂ or R ₁ and R ₃ may form a cyclic group. ] The manufacturing method of Claim 1 which has. 7. The method according to claim 6, wherein the aprotic solvent is N-methylpyrrolidone.