US4959252A — Highly oriented thermotropic optical disc member

Claim 1

Independent Claim 287 words

A dimensionally stable, circular, rigid and planar substrate, adapted for use as a support substrate for a radiation sensitive layer for an optical disc, said substrate having an external diameter of from 60 mm to 360 mm, a thickness of from 0.5 mm to 4 mm, a relative density of less than 1.8, a modulus of elasticity in the radial direction of from 9000 MPa to 18000 MPa, a coefficient of heat expansion in the radial injection which is less than 30 m/m/°C., a deformation temperature under load of at least 150° C., and, on part or all of at least one of its faces, an etching made at the time of the injection molding operation consisting of a groove in the form of a spiral or of concentric tracks, with a pitch of between 0.4 and 1 μm; said substrate being formed by injection molding a thermotropic aromatic polyester polymer having a flow temperature ranging from 200° to 350° C. and an inherent viscosity of at least 1 dl/g in a mold fitted with a central injection system under the following conditions: (1) temperature of the molten polymer of from 280° to 350° C.; (2) injection pressure of from 80 MPa to 160 MPa; (3) a temperature of the mold walls which ranges from 100° to 200° C.; (4) an injection time which ranges from 2 to 10 seconds and (5) a holding pressure after injection which ranges from 40 MPa to 120 MPa, whereby said substrate is substantially perfectly smooth on the non-etched parts of its faces as reflected in a surface roughness of less than 0.05 m and is substantially perfectly planar as reflected in a warp angle of less than 1×10 -5 radian.

Claim 2

Dependent Claim 287 words

A dimensionally stable, circular, rigid and planar substrate, adapted for use as a support substrate for a radiation sensitive layer for an optical disc, said substrate having an external diameter of from 60 mm to 360 mm, a thickness of from 0.5 mm to 4 mm, a relative density of less than 1.8, a modulus of elasticity in the radial direction of from 9000 MPa to 18000 MPa, a coefficient of heat expansion in the radial injection which is less than 30 m/m/°C., a deformation temperature under load of at least 150° C., and, on part or all of at least one of its faces, an etching made at the time of the injection molding operation consisting of a groove in the form of a spiral or of concentric tracks, with a pitch of between 0.4 and 1 μm; said substrate being formed by injection molding a thermotropic aromatic polyester polymer having a flow temperature ranging from 200° to 350° C. and an inherent viscosity of at least 1 dl/g in a mold fitted with a central injection system under the following conditions: (1) temperature of the molten polymer of from 280° to 350° C.; (2) injection pressure of from 80 MPa to 160 MPa; (3) a temperature of the mold walls which ranges from 100° to 200° C.; (4) an injection time which ranges from 2 to 10 seconds and (5) a holding pressure after injection which ranges from 40 MPa to 120 MPa, whereby said substrate is substantially perfectly smooth on the non-etched parts of its faces as reflected in a surface roughness of less than 0.05 m and is substantially perfectly planar as reflected in a warp angle of less than 1×10 -5 radian.

Claim 3

Dependent Claim 19 words

The substrate of claim 1 which comprises in said groove a radiation-sensitive microrelief pattern comprising an etched intelligence pattern.

Claim 4

Dependent Claim 14 words

The substrate of claim 1, wherein said groove comprises a spirally inscribed microrelief pattern.

Claim 5

Dependent Claim 14 words

The substrate of claim 1, wherein said groove comprises a plurality of concentric tracks.

Claim 6

Dependent Claim 15 words

The substrate of claim 1, having a radiation-sensitive microrelief pattern on both face surfaces thereof.

Claim 7

Dependent Claim 29 words

The substrate of claim 1 wherein said thermotropic polymer comprises a wholly aromatic polyester, alkylaromatic polyester, wholly aromatic poly(esteramide), alkylaromatic poly(esteramide), aromatic polyazomethine, aromatic carbonate polyester or mixture thereof.

Claim 8

Dependent Claim 22 words

The substrate of claim 6 wherein said thermotropic polymer comprises a wholly aromatic polyester, alkylaromatic polyester, aromatic carbonate polyester or mixture thereof.

Claim 9

Dependent Claim 19 words

The substrate of claim 7 wherein said thermotropic polymer has an inherent viscosity ranging from 1.1 to 4.0 dl/g.

Claim 10

Dependent Claim 17 words

The substrate of claim 1 wherein said thermotropic aromatic polyester polymer is a wholly aromatic polyester polymer.

Claim 11

Dependent Claim 137 words

The substrate of claim 9 wherein said wholly aromatic polyester polymer comprises recurring units of the following formulas (I), (III) and (IV) and, optionally (II): ##STR8## in which R 1 is methyl, ethyl, chlorine or bromine, with the proviso that the units (I) are the same or different; ##STR9## wherein the molar ratio of the recurring units (I) relative to the sum of the recurring units (II) and (III) ranges from 0.95/l to 1.05/l; the quantity of units (II) to the mixture of units (II) and units (III) is from 0 to 70 mole %, and that of units (III), relative to the mixture of units (II) and (III), ranges from 100 to 30 mole %; and the quantity of recurring units (Iv), relative to the quantity of units (1), ranges from 10 to 300 mole %.

Claim 12

Dependent Claim 200 words

The substrate of claim 1 wherein said thermotropic aromatic polyester polymer is an alkyl aromatic polyester consisting of units of formulae: (--O--X.sub.1 --O--).sub.a (--O--X.sub.2 --O--).sub.b (--O--X.sub.3 --O--).sub.c (V) --CO--Y--CO-- (VI) CO--Z--CO (VII) in which: X 1 denotes a 1,4-phenylene radical monosubstituted by a methyl or ethyl group or a chlorine or bromine atom, X 2 an unsubstituted 1,4-phenylene radical, X 3 denotes a ,1,4-phenylene radical disubstituted by two methyl or ethyl groups or 2 chlorine or bromine atoms, or a 4,4'-diphenylene radical or p,p'-diphenylene ether in which each aromatic nucleus may be substituted by a methyl or ethyl group or a chlorine or bromine atom, with 0.4≦a≦1 0≦b<0.6 0≦c<0.1 and a+b+c=1, Y denotes: a 1,4-phenylene or 1,4-cyclohexylene radical or a radical containing two phenylene groups capable of being linked together by a single bond or an acyclic chain capable of containing up to 8 carbon atoms and, if desired, 1 or 2 hetero atoms, or a divalent aromatic radical containing at least two condensed phenyl nuclei in which the bonds linked to the carbonyl groups are opposite and parallel, and Z denotes a --(CH 2 ) n -- radical with 3≦n≦10 the molar ratio Z/Y+Z being between 20 and 50%.

Claim 13

Dependent Claim 129 words

The substrate of claim 1 wherein said thermotropic aromatic carbonate polyester consist of units of formulae: ##STR10## in which: the radicals R 4 , which are identical, each denote a 1,4-phenylene radical monosubstituted by a methyl or ethyl group or a chlorine or bromine atom, the radicals R 5 each denote an unsubstituted 1,4-phenylene radical with 0.3≦a'≦1; O≦b'≦7; and a'+b'=1, the radicals R 6 , which may be identical or different, each denote a radical chosen from 1,4-phenylene, 1,4-cyclohexylene, 4,4 '-diphenylene, 2,6-naphthylene, 4,4'-ethylenedioxy-1,1'-diphenylene, 4,4,'-butylenedioxy-1,1'-diphenylene and 4,4'-hexylenedioxy-1,1'-diphenylene groups; the quantity of the units (IX) in the mixture of (IX) and (X) being between 30 and 90 mole %; and the molar ratio of the units (VIII) in relation to the sum of the units (IX)+(X) being between 0.95 and 1.05.

Claim 14

Dependent Claim 41 words

In an optical disc comprising at least one transparent light incident layer and at least one radiation-sensitive layer supporting substrate, the improvement which comprises, as the radiation-sensitive layer supporting substrate therefor, the rigid and planar substrate as defined by claim 1.

Claim 15

Dependent Claim 41 words

In an optical disc comprising at least one transparent light incident layer and at least one radiation sensitive layer supporting substrate, the improvement which comprises, as the radiation-sensitive layer supporting substrate therefor, the thermotropic disc element as defined by claim 6.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-09-24	1994-03-26	1994-09-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-09-24	1998-03-26	1998-09-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-09-24	2002-03-26	2002-09-25	$7700.00	Window Closed / Lapsed

Highly oriented thermotropic optical disc member

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