Method for polyester-polyol production

FIELD: organic chemistry, polymer materials.

SUBSTANCE: polyester-polyols are obtained by double metalcyanide catalyzed polyaddition of alkylenoxide to starting material containing active hydrogen atoms. Alkylenoxide is continuously fed into reactor during induction period while maintaining constant pressure in reactor.

EFFECT: method for polyester-polyol production with decreased induction time.

2 ex, 1 dwg

 

The invention relates to catalyzed double metallocyanide (DMC) method of producing polyether polyols, which significantly reduced the duration of the induction period.

In accordance with the state of the art the polyether polyols obtained by polyprionidae of alkalisation to the original compounds containing active hydrogen atoms, using as catalysts metal hydroxides, for example potassium hydroxide (KOH) (see “Ullmans Encyclopådie der technische Chemie”, Bd. 14, 1963, p. 49 ff.). However, the reaction rate polyaddition according to this method is extremely low. When using the method according to modern technology, depending on the reaction temperature, concentration of catalyst and the hydroxyl number of the resulting polyetherpolyols additional production of monofunctional polyethers with terminal double bonds, so-called monopoly, which limits the possibilities of future use of the product for the synthesis of polyurethanes. In this regard, upon completion of the polyaddition reaction, you must remove used as a catalyst base. This can be accomplished, for example, by adding acid, the use of providing neutralization adsorbing means of ion-exchange substances, or in other ways. However, water and salt, arr is generated as a result of neutralization of the base, before further processing polyetherpolyols also want to remove from the polymer. The above brief description of the method of producing polyether polyols according to the state of the art shows that it is expensive and cost-intensive process.

About the use of catalysts based on double metallocyanide (DMC) for the synthesis of polyether polyols known for a long time (see, for example, U.S. patent US-A 3404109, US-A 3829505, US-A 3941849 and US-A 5158922). Compared with the conventional method of producing polyether polyols by alkaline catalysis using catalysts based on DMC primarily leads to a decrease in the proportion of generated monofunctional polyethers with terminal double bonds, so-called Manolov. Obtained in this way, the polyether polyols can be used for the synthesis of high quality polyurethane (for example, elastomers, foams, coatings). In addition, improved DMC catalysts described, for example, in European patent applications EP-A 700949, EP-A 761708, international patent applications WO 97/40086, WO 98/16310, German patent applications DE-A 19745120, DE-A 19757574 and DE-A 19810269, have an extremely high activity, and the polyether polyols can be obtained at very low concentrations of such catalyst (25 ppm or less), so that you do not need them beats the population of addition polymerisation products.

The disadvantage of the method of producing polyether polyols using catalysts based on DMC is, however, a rather long induction periods. During the induction period, the growth of polymer chains proceeds very slowly, and therefore achieved only very limited yield of polymer per unit volume per unit time. This, in turn, implies a decrease in economic benefits due to faster flow of polyaddition and much more simple processing of the polymer compared with the method of producing polyether polyols, catalyzed by potassium hydroxide (KOH).

Due to the increase in the concentration of alkalinized in the reactor is the possibility of reducing the duration of the induction period. However, the high concentration of free accelerated represents a very large potential danger, as in this case, the activated catalyst may be accompanied by intense heat, and therefore uncontrolled temperature rise. This would increase the heat load on polyetherpolyols, in consequence of which, firstly, can be to the detriment of its quality, for example, due to the higher viscosity or a broader molecular weight distribution, and the second is, due to accelerated aging of the catalyst can significantly decrease its activity. In extreme situations, uncontrolled temperature increase can cause even the adiabatic thermal decomposition of polyetherpolyols.

In connection with the foregoing problems initially in the reactor is usually only download the part of alkalinized of the total needed to become polyetherpolyols number (see, for example, international patent application WO 97/23544). After that, waiting for the moment when significant pressure drop in the reactor will not indicate that the catalyst is fully activated, and only then carry out further introduction of accelerated in the reactor.

Unexpectedly, it was found that it is possible to significantly reduce the induction period upon receipt of polyether polyols using catalysts based on DMC, if continuously feeding into the reactor a small amount of accelerated and during the induction period, preferably dosing it such portions to the inside of the reactor was kept constant pressure. The number of free alkalinized used to activate the catalyst, must be determined or the maximum allowable temperature in the reactor (Tmax)or, if the latter is higher than the temperature of decomposition of recip is imago of polyetherpolyols, this temperature decomposition (Tmax). The maximum concentration of free accelerated in the reactor (CGrenz) can be calculated depending on the temperature and the enthalpy of the reaction (TRktionand ΔNRrespectively) according to the following formula:

In accordance with this object of the invention is a method of producing polyether polyols, catalyzed by DMC, by polyaddition of alkalisation to the original compounds containing active hydrogen atoms, according to which during the induction period in the reactor continuously dispense accelerated. Preferably at the beginning of the reaction in the reactor load all necessary to obtain the polyether polyols and the amount of parent compound and catalyst. The introduction of accelerated preferably carried out so that during the induction period in the reactor remained constant pressure.

Activation of the catalyst based on the DMC during the induction period in General carried out at temperatures from 20 to 200°C, preferably in the temperature range from 40 to 180°C, particularly preferably at temperatures from 50 to 150°C. the Reaction during the induction period can be carried out at total pressures of from 0.001 to 20 bar, preferably at a total pressure of the 0.5 to 10 bar and particularly preferably at a total pressure of from 1 to 6 bar.

The induction period is characterized by the fact that in order to maintain a constant pressure in the reactor accelerated should be dosed only in very small amounts. The activity of the catalyst at this stage of the reaction is slowly increased, and therefore a dosed quantity of accelerated can be gradually increased. Proof of full activation of the catalyst is that the rate of dispensing of accelerated can be significantly increased without increasing the pressure in the reactor accompanying this increase in speed. After full activation of the catalyst starts polyprionidae, which often occurs so rapidly that the rate of dispensing of accelerated limited only by the rate of heat transfer reactor or located outside the reactor heat exchanger. As shown in the drawing when using this method compared with intermittent dosing accelerated can be achieved significantly faster activation of the catalyst.

With continuous dosing free accelerated in the amount of 10 wt.% in relation to the mass introduced the original connection of the induction period may be comparable to that observed in the case of intermittent dosing of about 18 wt.% accelerated. On completion of the induction period should stage alcox the modelling of the mixture, containing DMC. At this stage of the reaction in General is not pressure, and temperature in the reactor. Therefore, due to the high activity of the catalyst, the rate of dispensing of accelerated often limited by the rate of thermal conductivity of the reactor or its connected through the bypass line of the heat exchanger.

Suitable to implement the method according to the invention catalysts based on DMC in principle known and described in the above patent literature concerning the current state of the art. Preferably use advanced, highly active DMC catalysts described, for example, in European patent applications EP-A 700949, EP-A 761708, international patent applications WO 97/40086, WO 98/16310, German patent applications DE-A 19745120, DE-A 19757574 and DE-A 19810269. Typical examples are described in the German patent application DE-A 19810269 DMC-catalysts, which along with the double metallocyanide (for example, hexacyanocobaltate (III), zinc) and organic complex ligand (e.g. tert-butanol) contain a polyester of ethylene oxide with srednetsenovoj molecular weight of more than 500 g/mol.

As the source alkalisation preferred ethylene oxide, propylene oxide, butylenes, as well as mixtures of these monomers. The polymer chain can be built, nab is emer, due to the implementation of alkoxysilane using only one Monomeric epoxide or may consist of statistically or block distributed two or three different Monomeric epoxides. More detailed information on this subject can be found in Ullmans Encyclopådie der technische Chemie”, Bd. A21, 1992, S.670 f.

As a source of compounds containing active hydrogen atoms, predominantly use a compound which has a molecular weight of from 18 to 2000 g/mol, preferably from 200 to 2000 g/mol and containing from 1 to 8, preferably from 2 to 6, hydroxyl groups. As an example, should be called butanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,6-hexanediol, bisphenol a, trimethylolpropane, glycerin, pentaerythritol, sorbitol, cane sugar, split starch or water.

It is more profitable to use those containing active hydrogen atoms of the parent compound, which have been obtained, for example, by conventional alkaline catalysis of the above low molecular weight starting compounds, and represent oligomeric products alkoxysilane with srednetsenovoj molecular weight of from 200 to 2000 g/mol.

Preferred is the use of oligomeric propoxycarbonyl source compounds containing from 1 to 8 hydroxyl groups, on obanno preferably from 2 to 6 hydroxyl groups, and with srednetsenovoj molecular weight of from 200 to 2000 g/mol. Such compounds can be obtained, in particular, in accordance with the “Ullmans Encyclopådie der technische Chemie”, Bd. A21, 1992, S.670 f.

Catalyzed DMC, polyprionidae of alkalinized to the original compounds in General carried out at temperatures from 20 to 200°C, preferably in the temperature range from 40 to 180°C, particularly preferably at temperatures from 50 to 150°C. the Reaction can be carried out with a total pressure of from 0.001 to 20 bar. Polyprionidae can be carried out in bulk or in an inert organic solvent such as toluene or tetrahydrofuran. The solvent content in relation to the quantity of received polyetherpolyols is usually from 10 to 30 wt.%.

The concentration of catalyst based on DMC pick up so that when adherence to the required reaction conditions it was possible the proper regulation of the progress of the polyaddition reaction. The concentration of catalyst in relation to the quantity of received polyetherpolyols in the range of from 0.0005 to 1 wt.% preferably from 0.001 to 0.1 wt.%, particularly preferably 0.001 to 0.01 wt.%.

The molecular mass obtained according to the invention the polyether polyols is in the range from 1000 to 100,000 g/mol, preferably in the range from 1500 to 50000 g/the ol, particularly preferably in the range from 2000 to 20,000 g/mol.

High molecular weight polyether polyols are of great importance as starting materials for the synthesis of polyurethanes. Depending on the molecular weight and functionality of the polyether polyols preferably used to produce elastomers, prepolymers for dispersions, elastic foams and polyurethane varnishes.

Examples

Obtaining a highly active catalyst on the basis of DMC synthesis in accordance with European patent application EP-A 700 949)

A solution of 12.5 g (from 91.5 mmol) of zinc chloride in 20 ml of deionized water under vigorous stirring (24000 rpm) was added to a solution of 4 g (12 mmol) of hexacyanocobaltate potassium in 70 ml of deionized water. Immediately thereafter, to the resulting suspension was added a mixture of 50 g of tert-butanol and 50 g of deionized water, followed by intensive mixing (24000 rpm) for 10 minutes. Then add a mixture consisting of 1 g of polypropyleneglycol with srednetsenovoj molecular weight 2000 g/mol, 1 g of tert-butanol and 100 g of deionized water, and produce stirring for 3 minutes (1000 rpm). Solid allocate filtering, for 10 minutes, stirred with a mixture consisting of 70 g of tert-butanol, 30 g of deionized water and 1 g of the above-mentioned polypropylenglycol (10000 Rev/mi is), then again distinguish by filtration. In conclusion, once again produce mixing of the solids within 10 minutes with a mixture of 100 g tert-butanol and 0.5 g of the above-mentioned polypropylenglycol (10,000 rpm). The filtered catalyst is dried at 50°and normal pressure until constant weight.

The output of the dried powdered catalyst is 6,23,

Example 1

Getting polyether polyols with continuous dosing of propylene oxide

2696 g of a polyester having a molecular weight of 416 g/mol and 0.4 g of a catalyst based on DMC loaded into the reactor with a capacity of 20 liters and heated to a temperature of 105°C. thereafter, the reactor create an inert atmosphere and load 268 g of propylene oxide, which corresponds to 10% of the source connection. The absolute pressure in the reactor is equal to 2.3 bar, and during the stage of activation of the catalyst support it at this level due to the continuous dosing of propylene oxide. Full activation of catalyst, corresponding to the completion of the induction period, shows a marked increase in the rate of dispensing of propylene oxide. During the reaction in the reactor to maintain a constant temperature. After activation of the catalyst remaining amount of propylene oxide (10000 g) is metered into the reactor with a rate of 4.6 kg/the speakers. The resulting polyester has a viscosity of η=384 MPa· (25°S), a hydroxyl number of 55.3 mg KOH/g, a content of double bonds in 5 mmol/kg Induction period is 224 minutes

Example 2 (comparative)

Getting polyether polyols with intermittent dosing of propylene oxide during the induction period

2724 g of a polyester having a molecular weight of 416 g/mol and 0.4 g of a catalyst based on DMC loaded into the reactor with a capacity of 20 liters and heated to a temperature of 105°C. thereafter, the reactor create an inert atmosphere and load it with 545 g of propylene oxide, which corresponds to 20% of the used source connection. The absolute pressure in the reactor is 3,4 bar. About the activation of the catalyst shows the pressure drop occurring when increasing the reaction rate. During the reaction in the reactor to maintain a constant temperature. After activation of the catalyst remaining amount of propylene oxide (10234 g) is metered into the reactor with a rate of 4.6 kg/hour. The resulting polyester has the following properties: viscosity η=382 MPa· (25°S), a hydroxyl number of 55.2 mg KOH/g, the content of double bonds in 5 mmol/kg Induction period is 144 minutes

Additional comparative experiments using intermittent dosing propyl is noxide show although by increasing the concentration of free nitric oxide in the reactor period of activation of the catalyst and may be reduced, however, this is accompanied by a decrease in system security. The decrease in the concentration of alkalinized with intermittent dosing, for example, up to 10 wt.% it is impractical, because the induction periods in this case are so long that the economic benefit is very small or disappears altogether. As shown in the drawing, when using the method according to the invention and the given reaction conditions, the amount of free accelerated entered to activate the catalyst, can be without any problems reduced to 10 wt.%, moreover, the periods of activation become comparable to those which are characteristic of activation by intermittent dosing of about 18 wt.% accelerated in relation to the mass introduced the original connection.

1. The method of producing polyether polyols by catalyzed double metallocyanide polyaddition of alkalisation to the original compounds containing active hydrogen atoms, in which accelerated continuously injected into the reactor during the induction period, and the pressure in the reactor during the induction period of constant support.

2. SPO is about according to claim 1, in which all is required to obtain polyetherpolyols amount of parent compound and catalyst is introduced into the reactor at the beginning of the reaction.

3. The method according to claim 1 or 2, in which use the original compounds containing from 1 to 8 hydroxyl groups and having a molecular weight of from 18 to 2000 g/mol.

4. The method according to claim 3, in which as a source of compounds containing active hydrogen atoms, using oligomeric propoxycarbonyl source compounds containing from 1 to 8 hydroxyl groups and having srednetsenovoj molecular weight of from 200 to 2000 g/mol.

5. The method according to claims 1 to 4, which uses a catalyst based on double metallocyanide, the concentration of which ranges from 0.001 to 0.1 wt.% in relation to the quantity of received polyetherpolyols.



 

Same patents:

FIELD: polymerization catalysts.

SUBSTANCE: invention provides double metal cyanide catalysts for production of polyetherpolyols via polyaddition of alkylene oxides to starting compounds containing active hydrogen atoms, which catalysts contain double metal cyanide compounds, organic complex ligands, and α,β-unsaturated carboxylic acid esters other than above-mentioned ligands.

EFFECT: considerably increased catalytic activity.

6 cl, 16 ex

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SUBSTANCE: polyoxyalkylene-polyols are obtained via direct polyoxyalkylenation of acid-sensitive low-molecular initiator with molecular weight below 400 Da in presence of double complex metal cyanide catalyst. Process comprises: (i) creation of appropriate conditions in reactor of polyoxyalkylenation in presence of double complex metal cyanide catalyst; (ii) continuously feeding into reactor alkylene oxide and above-mentioned initiator; and (iii) discharging polyether product. Loss of catalyst activity is reduced by performing at least one of the following operations: acidification of acid-sensitive low-molecular initiator before feeding it into reactor; and treatment of the same with effective amount of a substance other than acid, which reacts with base or absorbs base, before feeding it into reactor.

EFFECT: prevented catalyst from loosing its activity and essentially decreased high-molecular fraction and polydispersity of polyoxyalkylene-polyols.

21 cl, 2 dwg, 2 tbl, 3 ex

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FIELD: organic chemistry, polymer materials.

SUBSTANCE: polyester-polyols are obtained by double metalcyanide catalyzed polyaddition of alkylenoxide to starting material containing active hydrogen atoms. Alkylenoxide is continuously fed into reactor during induction period while maintaining constant pressure in reactor.

EFFECT: method for polyester-polyol production with decreased induction time.

2 ex, 1 dwg

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