Process for preparing synthetic polyethylene waxes having a high crystallinity and low viscosity

1. A process for preparing a polyethylene wax, the wax having a penetration number in accordance with DIN 51579 of not more than 1 mm·10 −1 , by polymerizing of ethylene in the presence of a Ziegler-Natta catalyst system composed of titanium tetrachloride and a dialkylaluminium halide, wherein

the polymerization temperature is in the range from 170 to 200° C.,

the polymerization is carried out essentially in the absence of solvents,

the dialkylaluminium halide is added to the process at a rate of 1.4 kg/hour,

and the Al/Ti molar ratio is less than 1.6.

2. The process according to claim 1 , wherein the polymerization temperature is in the range from 175 to 195° C.

3. The process according to claim 1 , wherein the Al/Ti molar ratio is less than 1.5.

4. A polyethylene wax prepared according to the process of claim 1 that has the following properties:

dropping point in accordance with DIN 51801 in the range from 115 to 125° C.;

penetration number in accordance with DIN 51579 of not more than 1 mm·10 −1 ;

viscosity in accordance with DIN 52007/1 at 150° C. of less than 60 mPas;

density of from 0.945 to 0.960 g/cm 3 at 23° C.;

molar mass in accordance with ASTM D 6474-99 of less than 1500 g/mol;

crystallinity in accordance with ISO 11357-3 of more than 70% and

a polydispersity of between 3.4 and 4.2.

5. The polyethylene wax according to claim 4 having a viscosity in accordance with DIN 52007/1 at 150° C. of less than 50 mPas.

6. The polyethylene wax according to claim 4 , wherein the density is from 0.950 to 0.960 g/cm 3 at 23° C.

7. The polyethylene wax according to claim 4 , wherein the molar mass is less than 1400 g/mol.

8. An additive used for printing inks, surface coating compositions, powder coatings or hot melts, the additive comprising a polyethylene wax that has the following properties:

dropping point in accordance with DIN 51801 in the range from 115 to 125° C.;

penetration number in accordance with DIN 51579 of not more than 1 mm·10 −1 ;

viscosity in accordance with DIN 52007/1 at 150° C. of less than 60 mPas;

density of from 0.945 to 0.960 g/cm 3 at 23° C.;

molar mass in accordance with ASTM D 6474-99 of less than 1500 g/mol;

crystallinity in accordance with ISO 11357-3 of more than 70% and

a polydispersity of between 3.4 and 4.2.

9. A nucleating agent for expandable polystyrene, a lubricant in PVC and a starting material for producing wax oxidate, all of which comprise a polyethylene wax that has the following properties:

dropping point in accordance with DIN 51801 in the range from 115 to 125° C.;

penetration number in accordance with DIN 51579 of not more than 1 mm·10 −1 ;

viscosity in accordance with DIN 52007/1 at 150° C. of less than 60 mPas;

density of from 0.945 to 0.960 g/cm 3 at 23° C.;

molar mass in accordance with ASTM D 6474-99 of less than 1500 g/mol;

crystallinity in accordance with ISO 11357-3 of more than 70% and

a polydispersity of between 3.4 and 4.2.

10. The process of claim 1 , wherein the dialkylaluminium halide is diethylaluminium bromide.

11. The process of claim 1 , wherein the dialkylaluminium halide is diethylaluminium chloride.

12. The polyethylene wax according to claim 4 , having a viscosity in accordance with DIN 52007/1 at 150° C. of less than 45 mPas.

13. The polyethylene wax according to claim 4 having a throughput micronization of 160 kg/h.

14. A printing ink containing a polyethylene wax that has the following properties:

dropping point in accordance with DIN 51801 in the range from 115 to 125° C.;

penetration number in accordance with DIN 51579 of not more than 1 mm·10 −1 ;

viscosity in accordance with DIN 52007/1 at 150° C. of less than 60 mPas;

density of from 0.945 to 0.960 g/cm 3 at 23° C.;

molar mass in accordance with ASTM D 6474-99 of less than 1500 g/mol;

crystallinity in accordance with ISO 11357-3 of more than 70% and

a polydispersity of between 3.4 and 4.2.

15. The printing ink of claim 14 , comprising 1% by weight of the polyethylene wax according to claim 4 , and wherein the printing ink has an abrasion protection of 1200 strokes as determined using a Prüfbau Quartant abrasion tester.

16. A surface coating composition containing a polyethylene wax that has the following properties:

dropping point in accordance with DIN 51801 in the range from 115 to 125° C.;

penetration number in accordance with DIN 51579 of not more than 1 mm·10 −1 ;

viscosity in accordance with DIN 52007/1 at 150° C. of less than 60 mPas;

density of from 0.945 to 0.960 g/cm 3 at 23° C.;

molar mass in accordance with ASTM D 6474-99 of less than 1500 g/mol;

crystallinity in accordance with ISO 11357-3 of more than 70% and

a polydispersity of between 3.4 and 4.2.

17. A powder coating containing a polyethylene wax that has the following properties:

dropping point in accordance with DIN 51801 in the range from 115 to 125° C.;

penetration number in accordance with DIN 51579 of not more than 1 mm·10 −1 ;

viscosity in accordance with DIN 52007/1 at 150° C. of less than 60 mPas;

density of from 0.945 to 0.960 g/cm 3 at 23° C.;

molar mass in accordance with ASTM D 6474-99 of less than 1500 g/mol;

crystallinity in accordance with ISO 11357-3 of more than 70% and

a polydispersity of between 3.4 and 4.2.

18. A hot melt containing a polyethylene wax that has the following properties:

dropping point in accordance with DIN 51801 in the range from 115 to 125° C.;

penetration number in accordance with DIN 51579 of not more than 1 mm·10 −1 ;

viscosity in accordance with DIN 52007/1 at 150° C. of less than 60 mPas;

density of from 0.945 to 0.960 g/cm 3 at 23° C.;

molar mass in accordance with ASTM D 6474-99 of less than 1500 g/mol;

crystallinity in accordance with ISO 11357-3 of more than 70% and

a polydispersity of between 3.4 and 4.2.