1. A process for producing rigid polyurethane foams by reacting
a) polyisocyanates with
b) compounds having at least two hydrogen atoms which are reactive toward isocyanate groups in the presence of
c) blowing agents,
wherein the compounds having at least two hydrogen atoms which are reactive toward isocyanate groups comprise at least one polyether alcohol bi) which can be prepared by reacting aromatic amines with ethylene oxide and propylene oxide, with firstly propylene oxide and then ethylene oxide or a mixture of ethylene oxide and propylene oxide being added on in a first process step and the remaining amount of propylene oxide being added on in a second process step.
2. The process according to claim 1, wherein the first process step in the preparation of the polyether alcohols bi) is carried out in the absence of a catalyst.
3. The process according to claim 1, wherein the second process step in the preparation of the polyether alcohols bi) is carried out in the presence of a basic catalyst.
4. The process according to claim 1, wherein firstly propylene oxide and subsequently ethylene oxide are fed in the first process step at a proportion of ethylene oxide of from 35 to 80% by weight, based on the amount of alkylene oxide in the first process step.
5. The process according to claim 1, wherein the content of ethylene oxide in the mixture in the second process step is from >0 to 5% by weight, based on the weight of the mixture of ethylene oxide and propylene oxide in the second process step.
6. The process according to claim 1, wherein from 2.5 to 4 mol of alkylene oxide are used per mole of aromatic amine in the first process step.
7. The process according to claim 1, wherein from 1.5 to 2 mol of ethylene oxide and from 1 to 2 mol of propylene oxide are used per mole of aromatic amine in the first process step.
8. The process according to claim 1, wherein the second process step is carried out in the presence of water or at least one further compound having at least two active hydrogen atoms.
9. The process according to claim 1, wherein the total content of ethylene oxide in the polyether alcohol is from 4 to 20% by weight, based on the weight of the polyether alcohol.
10. The process according to claim 1, wherein the hydroxyl number of the polyether alcohol bi) is in the range from 140 to 480 mg KOHg.
11. The process according to claim 1, wherein the hydroxyl number of the polyether alcohol bi) is in the range from 140 to 420 mg KOHg.
12. The process according to claim 1, wherein toluenediamine is used as aromatic amine for preparing the polyether alcohol bi).
13. The process according to claim 9, wherein toluenediamine having a proportion of vicinal toluenediamine of at least 95% by weight is used as aromatic amine for preparing the polyether alcohol bi).
14. The process according to claim 1, wherein the component b) comprises a polyether alcohol bii) which can be prepared by reacting H-functional sugars with alkylene oxides.
15. The process according to claim 13, wherein the sugars used for preparing the polyether alcohol bii) are sucrose andor sorbitol.
16. A process for preparing polyether alcohols by adding ethylene oxide and propylene oxide onto aromatic amines, wherein firstly propylene oxide and then ethylene oxide or a mixture of ethylene oxide and propylene oxide areis added on in a first process step and the remaining amount of propylene oxide is added on in a second process step using a basic catalyst.
17. A polyether alcohol which can be prepared according to claim 16.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A digital sound recording device comprising:
a sound input unit to which sound is input;
a storage unit that stores the input sound as digital sound data;
a data communication unit that performs data communication with an external unit; and
a processor controlling the storage unit so that input sound is stored in the storage unit as digital sound data, and controlling the data communication unit so that the digital sound data is transmitted and received tofrom the external unit through the data communication unit; and
a write protection unit that is provided between the storage unit and the data communication unit,
wherein the write protection unit prevents the external unit from performing write control on the storage unit by interrupting deletion and storage instructions from the external unit.
2. The digital sound recording device according to claim 1, further comprising:
a MAC (message authentication code) generator,
wherein when digital sound data is stored in the storage unit, the MAC generator generates a MAC corresponding to the digital sound data and stores the MAC in the storage unit.
3. The digital sound recording device according to claim 2,
wherein the MAC is generated on the basis of a hardware identifier of the digital sound recording device.
4. The digital sound recording device according to claim 2,
wherein the MAC is incorporated in the corresponding digital sound data.