DE3233251C2 - - Google Patents

Description

The preparation of polyether polyols by polymerization of alkylene oxides that attach to a starter molecule with Zerewitinoff-active hydrogen atoms in the presence of basic catalysts is known. When Basic catalysts are usually alkali metal hydroxides or alkoxides used for polyether polyols with hydroxyl numbers up to 28 in quantities up to maximum 0.06 mole per equivalent of Zerewitinoff active hydrogen of the starter molecule are used. You get Polyether polyols having free hydroxyl groups, of which a part due to the basic reaction medium terminal Carries alkoxide groups. For further use the polyether polyols, z. For producing polyurethanes, it is necessary to add the alcohol radicals of the polymers, for example, by neutralization with acids, in to convert free hydroxyl group.

Activated polyether polyols are usually by Addition of ethylene oxide to polyoxypropylene glycols or polyoxyethylene-polyoxypropylene glycols, wherein the oxyethylene and oxypropylene groups in the mixed be arranged randomly or in blocks can. Here, the reactivity of the polyether polyol by the amount of polymerized ethylene oxide in the endblock certainly.

A due to the reactivity necessary high content Oxyethylene groups in the polyether polyol may be the foam affecting the properties of the material. So poly tend  urethane foams made from oxyethylene-rich poly ether polyols for the formation of closed foam cells. Furthermore, the mechanical property deteriorates level in the presence of moisture, as the foams too hydrophilic.

According to DE-OS 30 30 737 galang it by reduction the ethylene ether content in the polyoxyethylene endblock and by simultaneously increasing the catalyst concentration before the final ethoxylation polyether polyols in the reaction with organic poly Isocyanate foams with a larger open cell result. However, it also showed that the hardness of flexible polyurethane foams by a reduction of ethylene ether content in the polyether polyol becomes. It is also known that by increasing the Ethylenethergehalts in the end block of a polyether polyol the compatibility index (CI) increases and the Ge lock cell content of a polyurethane produced therewith Foam increases sharply.

The use of epoxy alcohols, especially glycidol for the production of polyether or polyester-polyether polyols is not new either. According to the GB-PS 9 73 958 are mixtures of epoxy alcohols and Alkylene oxides added together to a starter molecule. On This way, polyether polyol mixtures with a desired hydroxyl content and molecular weight, however, with regard to the individual molecules differ in their molecular weight.

DE-OS 25 39 108 describes the preparation of polyoxyethylene propylene glycols with reduced double bond content, without the content of hydroxyl end groups worth mentioning  changes, by polymerization of propylene oxide in the presence from 0.1 to 3 mol% glycidol.

According to the US-PS 34 83 169 hydroxyl or carboxyl groups containing copolymers by copolymerization of Epoxides and cyclic anhydrides to a starter molecule in specific proportions and under certain conditions Reaction conditions produced.

The object of the present invention was to To develop polyether polyols, the one with commercial Polyether polyols comparable ethylene ether content own in the endblock and also a very low have a compatibility index. The polyether polyols should be used in the production of polyurethane, semi-hard, Soft or integral foams cell-opening or foam be pressure moderately effective, wherein the foam internal pressure show a low value over a long period of time should (flat course of the foam internal pressure curve in Foam pressure-time diagram).

This task could surprisingly be solved with Assistance of asymmetric polyether polyols with a Functionality of 3 to 8 and a hydroxyl number of 15 to 112, which are available through implementation of

• a) one mole of a polyoxyalkylene glycol with a Hydroxyl number of 15 to 200 with
• b) 0.1 to 2 moles of an epoxide alcohol of the formula in the
  R¹ and R² are the same or different and represent a hydrogen atom or a methylol radical,
  x is an integer from 0 to 9 and
  y are 0 or 1 and then
• c) alkoxylation of the tri- to octafunctional Intermediate (c) to said hydroxyl number.

Asymmetric polyether polyols are within the meaning of the invention Polyether polyols with a functionality of 3 to 8 and a different equivalent weight of each Ligands.

The asymmetric polyether polyols according to the invention have the advantage that they are compared to commercial Polyether polyols with the same functionality and Hydroxyl number and the same weight ratio of ethylene ether to Alkylenether groups in the molecule a smaller one Compatibility Index CI possess. The compatibility index CI, also called cloud point, is at the known polyether polyols of the prior art sharply defined and is usually above 50 ° C. The On the other hand, polyether polyols according to the invention have either a sharply defined cloud point smaller than 50 ° C or a relatively wide cloud point range from less than 20 ° C to a maximum of 60 ° C, that means in this area the turbidity does not occur abruptly, but continuously increasing. The compatibility index CI or cloud point is determined by Mix 100 g of a solution of 50 parts by weight of water and 50 parts by weight of isopropanol with 3 g of polyether polyol and heating the solution at a rate of 3 ° C per minute until turbidity occurs.  

In this context, it should be noted that the compatible usually with increasing molecular weight with the same functionality and constant weight ratio from ethylene ether to other alkylene ether units decreases or at the same molecular weight and the same Functionality increased with increasing ethylene ether content can be.

The products also show an excellent cell-opening Effect, d. H. an internal foam pressure reduction the production of polyuretane, semi-hard, soft and Integral foams.

Among the for the preparation of asymmetric according to the invention Polyether polyols usable starting materials and Catalysts should be:

• a) Suitable polyoxyalkylene glycols having a hydroxyl number of 15 to 200, preferably from 20 to 100 and in particular from 35 to 70 can be prepared by reacting one or more alkylene oxides having 2 to 4 carbon atoms in the alkylene chain and a molecular weight of 44 to 250, preferably 44 to 72 with a starter molecule containing two reactive hydrogen atoms bound.
  As alkylene oxides its z. B. called tetrahydrofuran, epichlorohydrin, optionally substituted on the phenyl group styrene oxides, cyclohexene oxide, 1-cyclohexyl-ethylene oxide, 1,2- and 2,3-butylene oxide, 1,3-propylene oxide and preferably before 1,2-propylene oxide and ethylene oxide. The alkylene oxides can be used individually, alternately in succession or as mixtures. For example, 1,2-propylene oxide and subsequently the ethylene oxide may be polymerized onto the starter molecule, or first the entire 1,2-propylene oxide may be copolymerized in admixture with a portion of the ethylene oxide and the remainder of the ethylene oxide may be subsequently polymerized or a portion of the ethylene oxide may be gradually added. then the entire 1,2-propylene oxide and then the remainder of the ethylene oxide are polymerized. Of course, only 1,2-propylene oxide or ethylene oxide can be polymerized onto the starter molecule.
  Suitable starter molecules are, for example: water, amino alcohols such. For example, ethanolamine, N-alkyl-di-alkanolamines such. As N-methyl and N-ethyldiethanolamine, diglyme, such as. B. diethylene glycol and dipropylene glycol and diols having 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms such as. For example, ethylene glycol, 1,2-, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, octanediol-1,8 and decane-1,10. Preferably used are water, ethylene glycol, diethylene glycol, propylene glycol-1,3, dipropylene glycol, 1,4-butanediol and 1,6-hexanediol.

As starting component

• b) Be epoxide alcohols of the formula used in the
  R¹ and R² are the same or different and denote a -CO₂OH radical or preferably a hydrogen atom,
  x is an integer from 0 to 9, preferably 0 to 3 and in particular 0 and
  y is 1 or preferably 0.
  Examples of epoxide alcohols are: 1,2-epoxybutan-4-ol, 1,2-epoxy-3-methylol-butan-4-ol, 1,2-epoxy-3,3-dimethylol-butane-4 ol, 1,2-epoxy-pentan-5-ol, 1,2-epoxy-4-methylol-pentan-5-ol, 1,2-epoxy-4,4-dimethyl-lol-pentan-5-ol, 1 , 2-epoxy-hexan-6-ol, 1,2-epoxy-5-methylol-hexan-6-ol, 1,2-epoxy-5,5-dimethylol-hexan-6-ol, 1,2-epoxy -heptan-7-ol, 1,2-epoxy-octan-8-ol, 1,2-epoxy-decan-10-ol, 1,2-epoxy-dodecan-12-ol, 1,2-epoxy-11 -methylol-dodecan-12-ol, 1,2-epoxy-11,11-dimethylol-dodecane-12-ol, and preferably glycidol (1,2-epoxy-propan-3-ol). The epoxy alcohols can be used both individually and in the form of mixtures.
  For the preparation of the tri to octafunctional, preferably tri- to tetrafunctional intermediates per mole of polyoxyalkylene glycol (a) 0.1 to 2 moles, preferably, 0.5 to 1.5 moles, and in particular about 1 mol of epoxide alcohol (b) Reaction brought.
• c) The resulting intermediate is then in per se known manner in the presence of basic catalysts to a hydroxyl number of 15 to 112, preferably 25 to 55 and especially from 25 to 35 alkoxylated. For this purpose, ethylene is preferred as alkylene oxides oxide, 1,2-propylene oxide or mixtures thereof, in particular those asymmetric polyether polyols produced, based on the total weight polymerized alkylene oxide groups 5 to 40 wt .-%, preferably 10 to 30 wt .-% polymerized ethylene oxide groups bound, of which in turn from 5 to 30 wt .-%, preferably 10 to 20 wt .-% are terminally bonded. The asymmetric polyether polyols according to the invention be sit, measured according to the aforementioned method one Compatibility index CI or cloud point of less as 20 to 50 ° C, preferably from less than 20 to 40 ° C.  or a turbidity range of less than 20 ° C to maximum 60 ° C, preferably from 35 to 58 ° C.

The suitable as starting materials Polyoxyalkylenglykole (a) may be in the presence of acidic or preferably basic catalysts are produced. As well is the addition of the epoxide alcohols (b) and the final Alkoxylation (c) of the intermediates in the presence of acidic or basic catalysts carried out, wherein the use of basic catalysts is preferred.

As acidic catalysts may be mentioned by way of example: strong Mineral acids with pKs values of -5 to +4 such. B. Per chloric acid, hydrochloric acid, sulfuric acid, phosphoric acid, organic sulfonic acids, such as toluenesulfonic acid and ions exchanger with sulfonic acid groups, Lewis acids, such as. B. BF₃, AlCl₃, SnCl₄, FeCl₃, PF₅ or SbCl₅ and bleaching earths. Hydroxyl-containing polytetrahydrofurans are preferred by polymerization of tetrahydrofuran in the presence of acetic anhydride with antimony pentachloride or im essential anhydrous bleaching earth as a catalyst and subsequent transesterification produced. The reaction temperatures for the polymerization with acidic catalysts are usually between 10 and 120 ° C, preferably 30 and 66 ° C.

As basic catalysts, the z. In amounts of 0.03 to 1.0 mole, preferably from 0.06 to 0.2 mole per Equivalent hydroxyl group of the polyoxyalkylene glycols (a) or intermediates (c) are used For example: Alkali alkoxides having 1 to 4 carbon atoms in the alkyl radical, such as sodium methylate, sodium and potassium ethylate, potassium isopropylate and potassium butylate, Alkaline earth hydroxides, such as. As calcium hydroxide and preferably  Alkali hydroxides, such as lithium and in particular Sodium and potassium hydroxide.

In particular, the asymmetric polyether polyols advantageously prepared as follows:

The polyoxyalkylene glycols (a) are acidic catalysts at temperatures up to 120 ° C and reaction times of 0.5 to 5 hours or preferably in the presence of basic catalysts with an epoxide alcohol (b) or an epoxy alcohol mixture to the tri to octafunctional Intermediates implemented.

For this purpose, the polyoxyalkylene glycols (a) with the basic catalyst added and partially in the ent convicted alcoholic talking. Depending on the used Catalyst then becomes optionally formed water or low-boiling alcohol, conveniently below distilled off under reduced pressure and at temperatures of 90 to 150 ° C, preferably 100 to 130 ° C, the epoxy alcohols to the extent that they abreact, for example in 0.5 to 8 hours, preferably 1 to 2 hours at Atmospheric pressure or optionally under increased pressure at 1.1 to 20 bar, preferably 1.1 to 7 registered bar. After completion of the reaction, the unreacted Epoxide alcohol under reduced pressure, for example at Distilled off 10 to 20 mbar. The implementation will be purposeful moderately, as well as the subsequent alkoxylation, in the presence of an inert under the reaction conditions Gas, for example nitrogen performed.

Thereafter, the intermediate formed (c), optionally after introduction of additional basic catalyst and separating the formed water or alcohol,  under the above reaction conditions with 1,2-propylene oxide, mixtures of 1,2-propylene oxide and Ethylene oxide or ethylene oxide alkoxylated, preferably with the proviso that the formation of terminal Ethylene ether is finally ethoxylated.

After reaching the required according to the invention hydroxyl number are the excess alkylene oxides, preferably Ethylene oxide distilled off under reduced pressure, the formed asymmetric polyether polyols with inorganic Acids, such as. As sulfuric acid, hydrochloric acid or Phosphoric acid, acidic salts such. For example potassium hydrogen phosphate, organic acids, such as. B. lemons acid, tartronic acid and the like. a. or ion exchangers neutralized and purified by known methods.

According to a preferred embodiment, the production the polyoxyalkylene glycols (a), the reaction with the Epoxide alcohols and the subsequent alkoxylation more carried out in stages in the same reaction vessel. In a In this case, precursors are first of all made from the difunctional ones mentioned Starter molecules and alkylene oxides in the presence of basic catalysts by known methods Poly oxyalkylene glycols (a) having hydroxyl numbers of 15 to 200 prepared after removal of excess Alkylene oxide directly, d. H. in the same reaction vessel, after the method according to the invention to asymmetric poly ether polyols can be implemented.

The asymmetric polyether polyols according to the invention have functionalities from 3 to 8, hydroxyl numbers of 15 to 112, cloud points to 50 ° C or turbidity ranges up to 60 ° C. The content of primary hydroxyl groups is average at 50 to 95 wt .-%.  

The products are used to manufacture polyurethane art used. They are particularly suitable for Production of polyurethane, semi-hard, soft and inte gray foams, wherein the mixtures of the invention Asymmetric polyether polyols and conventional Polyether polyols can be used.

Examples 1 to 5 General manufacturing instructions

The asymmetric polyether polyols according to the invention were prepared in 2 precursors and 3 reaction stages, However, the alkoxylation depending on the technical Divide conditions into even more reaction stages leaves.

1st preliminary stage

134.2 parts by weight of dipropylene glycol were in a reactor submitted and with 14.7 parts by weight of 85gew .-% aqueous potassium hydroxide solution mixed. This mixture was ent to separate the ent at the alkoxide formation standing water for 2 hours under reduced pressure (10-20 mbar) heated to 105 ° C.

2nd preliminary stage

The 1,2-propylene oxide was added to the reaction mixture at a Temperature of 105 ° C and a pressure up to 7 bar in 2 to 7 hours incorporated. After a post-reaction time of about 1.5 hours, this was unreacted Stripped of 1,2-propylene oxide under reduced pressure.

1st reaction stage

To the obtained polyoxypropylene glycol were 74 parts by weight of glycidol (1 mole per mole of polyoxypropylene  glycol) at 105 ° C in 1.5 hours. After finished Reaction was the unreacted glycidol below reduced pressure (10 to 20 mbar) in 1.5 hours abge separates.

2nd reaction stage

The resulting intermediate was treated with 1,2-propylene oxide Propoxylated analogously to the precursor 2. To completed reaction, the unreacted 1,2-propylene oxide under reduced pressure (10 to 20 mbar) abdestil profiled.

3rd reaction stage

740 parts by weight of ethylene oxide became the reaction mixture at 105 ° C under a pressure of up to 7 bar in 4 hours incorporated. After the reaction was not reacted ethylene oxide under reduced pressure (10 to 20 mbar) distilled off, the reaction mixture with a Magnesium silicate and the alkaline magnesium silicate filtered off.

Comparative Example A

For separating the resulting in the alkoxide formation Water became the mixture of 1.48 parts by weight glycerol and 147 parts by weight of an 85 wt.% aqueous potassium hydroxide solution for 2 hours under reduced pressure (10 to 20 mbar) heated to 130 ° C.

To the reaction mixture were added at a temperature of 105 ° C and a maximum pressure of 7 bar in 5 to 6 hours 4160 parts by weight of 1,2-propylene oxide added. After a Afterreaction time of 4 hours was unreacted Distilled off 1,2-propylene oxide under reduced pressure.  

Thereafter, the reaction mixture 740 parts by weight of ethylene oxide at 105 ° C and under a pressure up to 7 bar in 3 hours incorporated. To complete the ethoxylation the reaction mixture was kept at 105 ° C for 4 hours, then the unreacted ethylene oxide distilled off, the reaction mixture with a magnesium silicate treated and the alkali-containing magnesium silicate abfil trated.

The order of build component addition in more schematic Form and determined on the final products obtained Characteristics are summarized in Tables 1a and 1b caught.  

Table 1a

In Tables 1b and 2b, the following abbreviations have been used used:

II₂: dipropylene PO: 1,2-propylene oxide EO: ethylene oxide (X): x wt .-% PO or EO, based on the total weight of the alkylene oxides glycidol: Glycidol (1,2-epoxy-propan-3-ol) [Y]: y mol Glyc: glycerin L1: Ligand 1 L2: Ligand 2 L3: Ligand 3 f: functionality OHN: hydroxyl CI: compatibility Index

Examples 6 to 8

The asymmetric polyether polyols were analogous to the general preparation instructions for Examples 1 to 5 produced.

The components used and their quantities, the Process parameters as well as the sequence of the building component addition in schematic form and those on the final products Identified characteristics are shown in Tables 2a and 2b summarized.  

Table 2a

Application Examples 1 to 5 and Comparative Examples E to H Production of polyurethane semi-rigid foams A component

Mixture of a polyether polyol,

8.4 parts by weight of a polyether polyol based on ethylene diamine-propylene oxide having a hydroxyl number of 770
0.3 parts by weight of dimethylethylenediamine and
1.8 parts by weight of water.

Component B

Mixture of diphenylmethane diisocyanates and polyphenyl polyisocyanates.

100 parts by weight of the A component and 50 parts by weight of the B component became intense with a stirrer for 10 sec mixed and to determine the Aufschäumcharakteristik (Start and rise time) in an open cup and to Measurement of the foaming pressure in an open pressure nut tube filled and allowed to foam there.

The determination of the foaming data is analogous to the publication by R. Jannings, Instrumental Analysis of the Performance Characteristics of Rigid Urethane Foaming Systems, in J. Cell. Plast. May / June 1969, pages 159 to 172nd

The polyether polyols used and their amounts and the determined starting and rising times, the gel point and the maximum foam pressure are summarized in Table 3.  

Table 3

Application Examples 1 to 5 and Comparative Examples E to H show that in the production of polyurethane semi-hard Foams by the use of the invention asymmetric polyether polyols or mixtures thereof usual polyether polyols a significant maximum foaming pressure reduction is achieved.

Claims (9)

1. Asymmetric polyether polyols having a functionality of 3 to 8 and a hydroxyl number of 15 to 112, obtainable by reaction of

• a) one mole of a polyoxyalkylene glycol having a hydroxyl number of 15 to 200 with
• b) 0.1 to 2 moles of an epoxide alcohol of the formula in the
  R¹ and R² are the same or different and denote a hydrogen atom or a -CH₂OH radical,
  x is an integer from 0 to 9 and
  y are 0 or 1 and then
• c) alkoxylation of the tri to octafunctional intermediate (c) formed up to said hydroxyl number.

2. Asymmetric polyether polyols according to claim 1, characterized in that the products 5 to 40 wt .-% bound polymerized ethylene oxide groups contained, based on the weight of polymerized Alkylene oxide groups, wherein 5 to 30 wt .-% of the polymerized Ethylene oxide groups are arranged terminal. 3. asymmetric polyether polyols according to claim 1, characterized in that the reaction as  Epoxide alcohol glycidol used. 4. A process for the preparation of asymmetric polyether polyols having a functionality of 3 to 8 and a hydroxyl number of 15 to 112 according to claim 1, characterized in that

• a) one mole of a polyoxyalkylene glycol having a hydroxyl number of 15 to 200 with
• b) 0.1 to 2 moles of an epoxide alcohol of the formula in the
  R¹ and R² are the same or different and represent a hydrogen atom or a methylol radical,
  x is an integer from 0 to 9 and
  y is 0 or 1, and the tri- to octafunctional intermediate formed
• c) alkoxylated in the presence of a basic catalyst up to said hydroxyl number.

5. The method according to claim 4, characterized in that the tri- to octafunctional intermediate formed ethoxylated or alkoxylated and finally ethoxylated. 6. The method according to claim 4, characterized in that one mole of polyoxyalkylene glycol (a) about 1 mole Epoxide alcohol (b) used.   7. The method according to claim 4, characterized in that one uses as epoxide alcohol (b) glycidol. 8. Use of the asymmetric polyether polyols according to An Claim 1 for the production of polyurethane plastics. 9. Use of the asymmetric polyether polyols according to An Pruch 1 for the production of open-cell polyurethane Soft and semi-rigid foams as well as integral foam materials.