Process for preparing polyether polyols
View Patent ↗The present invention relates to a process for solvent-free preparation of polyether polyols with blockwise polyether chain structure, based on starter compounds solid at room temperature.
1. Process for preparing polyether polyols based on starter compounds having Zerevitinov-active hydrogen atoms, having n En blocks each comprising at least 75% by weight of oxyethylene units, and m Pm blocks each comprising at least 60% by weight of oxypropylene units, where n and m are each natural numbers from 1 to 10 and at least one starter compound having at least one Zerevitinov-active hydrogen atom and a melting point of ≧40° C., comprising reacting the at least one starter compound with ethylene oxide and propylene oxide in the presence of a catalyst, wherein the Pm block(s) are metered in under the conditions of the following in equation
x
m
(
PO
)
x
(
OH
)
*
t
m
(
PO
)
*
OHZ
<
0.0060
in
[
g
/
(
h
*
{
mg
KOH
}
)
]
(
1
)
where
xm(PO) is defined as the molar amount of propylene oxide metered in for the Pm block in mol,
x(OH) is defined as the molar amount of hydroxyl groups in the polyether polyol in mol,
tm(PO) is defined as the metering time for the propylene oxide of the Pm block in hours,
OHZ is defined as the calculated OH number of the polyether polyol in mg KOH/g, and
m is as defined above,
and wherein the total content of oxyethylene units in the polyether polyol, based on the total mass of the alkylene oxides metered in, is from 5 to 90% by weight.
2. Process according to claim 1 , wherein the Pm block comprises or the Pm blocks comprise at least 75% by weight of oxypropylene units, based on the total mass of the alkylene oxides metered in for this block or these blocks.
3. Process according to claim 1 , wherein the polyether polyols contain up to 85% by weight of oxyethylene units, based on the total mass of the alkylene oxides metered in.
4. Process according to claim 1 , wherein at least one En block contains at least 90% by weight of oxyethylene units.
5. Process according to claim 1 , wherein one En block is an end block.
6. Process according to claim 1 , wherein the calculated OH number of the polyether polyols is from 50 mg KOH/g to 400 mg KOH/g.
7. Process according to claim 1 , wherein the polyether polyols consist of the En and Pm blocks and the structural units originating from the starter compound.
8. Process according to claim 1 , wherein at least one further starter compound having a melting point <40° C. is used in a proportion of up to 30% by weight based on the total mass of all starter compounds.
9. Process according of claim 1 , wherein no solvent is used in the reaction of the starter compound with ethylene oxide and propylene oxide and any further alkylene oxide compounds.
10. Process according to claim 1 , wherein the catalyst is a base.
11. Process according to claim 1 , wherein the catalyst is used in a concentration, based on the amount of end product, of 0.004 to 1.0% by weight.
12. Process according to claim 1 , wherein the catalyst used is potassium hydroxide.
13. Process according to claim 1 , wherein the at least one starter compound is reacted with ethylene oxide and propylene oxide at a temperature of 70 to 170° C.
14. Process according to claim 1 , wherein the starter compound used is selected from the group consisting of pentaerythritol, sucrose, trimethylolpropane, sorbitol and mixtures thereof.
15. Polyether polyols prepared by a process according to claim 1 .
16. Polyether polyols according to claim 15 , wherein the polyether polyols at 20° C. are visually clear.
17. Polyether polyols according to claim 15 , wherein the polyether polyols at 20° C. are homogeneous.
18. Polyether polyols according to claim 15 , wherein the polyether polyols at 20° C. are visually clear and homogeneous.