Disc shaped high density recording medium

1. An optical recording medium in which at least a recording layer and a light transmitting layer are sequentially formed on a substrate and in which the light is illuminated from the light transmitting layer side for recording and/or reproducing information signals, said substrate comprising an injection molded part and said substrate having a Young's modulus E of at least 2.15 GPa and a Q factor of lower than 160 measured at 25° C. at 2000 Hz in accordance to ASTM E 756-05 and a transcriptability>85%.

2. An optical recording medium according to claim 1 , wherein the substrate is molded at a mold temperature>Tg (glass transition temperature)−30° C.

3. An optical recording medium according to claim 2 , wherein the mold temperature>Tg (glass transition temperature)−20° C.

4. The optical recording medium according to claim 1 , wherein said substrate has a Young's modulus E of at least 2.93 GPa and a Q factor of lower 160 measured at 25° C. at 2000 Hz in accordance to ASTM E 756-05.

5. The optical recording medium according to claim 1 , wherein said substrate is polycarbonate containing fillers.

6. The optical recording medium according to claim 5 , wherein said filler, measured on a bulk sample, has a hardness, in accordance to the Mohs scale of less or equal to 5.

7. The optical recording medium according to claim 6 , wherein said filler is based on primary nano particles with a d 50 of less than 100 nm.

8. The optical recording medium according to claim 1 , wherein said substrate having pits aligned along a spiral track and or spiral grooves with a track pitch of less than 350 nm.

9. The optical recording medium according to claim 1 , wherein said light transmitting layer is a UV curable and spin-coatable resin with a real part n of the index of refraction of at least 1.41.

10. The optical recording medium according to claim 1 , wherein said light transmitting layer is a UV curable and spin-coatable resin having (i) a complex refractive index in which the real component n is at least 1.70 and in which the imaginary component k is at most 0.016, (ii) a surface roughness R a of less than 20 nm and (iii) a scratch resistance of not greater than 0.75 um scratch depth, said real component n and imaginary component k measured at a wavelength of 400 to 410 nm, and said surface roughness R a determined by Atomic Force Microscopy, and said scratch depth determined by moving a diamond needle having a tip radius of 50 um over the coating on a polycarbonate substrate at a rate of advance of 1.5 cm/s under an applied weight of 40 g.

11. The optical recording medium according to claim 1 , wherein said light transmitting layer is a UV curable and spin-coatable resin comprising nanoparticles with an average particle size (d 50 ) of less than 100 nm.

12. An optical recording medium according to claim 1 , wherein the thickness of the light transmitting layer is from 1 nm to less than 3000 nm.

13. An optical recording medium according to claim 1 , wherein the thickness of the light transmitting layer is from 500 nm to less than 1500 nm.

14. The optical recording medium according to claim 1 , wherein the substrate comprises a polycarbonate resin in which the aromatic dihydroxymonomer is derived from aromatic dihydroxy compounds of formula (1)

HO—Z—OH  (1)

in which Z denotes a radical of the formula (1a)

in which

R′ and R 2 independently of each other represent H or C 1 -C 8 -alkyl and X represents a single bond, C 1 -C 6 -alkylene, C 2 -C 5 -alkylidene or C 5 -C 6 -cycloalkylidene, which may be substituted by C 1 -C 6 -alkyl,

with the proviso that R 1 and R 2 represent hydrogen if X represents 3,3,5 trimethylcyclohexylidene.

15. A method of preparing the substrate as basis for the optical recording medium according to claim 1 wherein the substrate is molded at a mold temperature>Tg (glass transition temperature)−30° C. against a stamper including pits and/or grooves by which method said pits and/or grooves are replicated into the substrate with a transcriptability>85%.