Such block copolymers have been hydrogenated to further differentiate the range of physical properties and the oxidative stability. Hydrogenation of the polymerized conjugated diene block can be achieved alone or in combination with hydrogenation of the aromatic ring of the polymerized vinyl aromatic monomer. Depending on hydrogenation conditions and the catalyst employed, it is possible to hydrogenate the conjugated diene polymer portion of the block copolymer without substantially affecting the vinyl aromatic polymer block, or to substantially saturate both block types.

Fully hydrogenated block copolymers prepared from vinyl aromatic and conjugated diene monomers, wherein both blocks are substantially saturated, are well known in the art.

U. S. Patent Nos. 3,333,024 and 3,431,323 disclose hydrogenated triblock (ABA) copolymers of vinyl aromatic and conjugated diene polymers having a 20 to 30 percent hydrogenation level and improved tensile properties, when compared to their non- hydrogenated counterparts. However, such copolymers containing very low molecular weight hydrogenated polystyrene blocks, for example 4,000, have low heat resistance and do not afford rigid compositions with good physical properties. U. S. Patent No. 3,598,886 discloses hydrogenated vinyl substituted aromatic hydrocarbon-conjugated diene block copolymers having less than 3 percent aromatic unsaturation, however the compositions disclosed do not have a good balance of physical properties and processability. Moreover, Thermoplastic Elastomers, Chapter 14, Ed. N. R. Legge, et al., Hanser Publishers, New York, 1987 discloses that fully hydrogenated block copolymers have generally poor physical properties at only slightly elevated temperatures.

U. S. Patent No. 4,911,966 issued to Mitsubishi discloses hydrogenated vinyl aromatic polymers and copolymers and their use in optical media applications. However, the broad composition disclosed suffer from numerous disadvantages including high birefringence, poor processability and poor dimensional stability in such applications.

Therefore, it remains desirable to obtain a hydrogenated block copolymer composition prepared from i vinyl aromatic and a conjugated diene monomer having improved physical properties, retention of these properties at elevated temperatures, and good birefringence, processability and dimensional stability for use in thin wall injection molding applications.

In one aspect, the present invention is a composition comprising a hydrogenated pentablock copolymer prepared by hydrogenating a pentablock copolymer produced from at least one vinyl aromatic monomer and at least one conjugated diene monomer, wherein the hydrogenated pentablock copolymer has a total number average molecular weight (Mnt) of from 40,000 to 70,000 and is of the structure ABABA, and wherein each vinyl aromatic polymer block (A) has a Mna of from 8,700 to 21, 000 and is hydrogenated to greater than 90 percent, and each conjugated diene polymer block (B) has a Mnb of from 2,000 to 12,500, further characterized in that the total amount of block B is from 10 to 35 weight percent of the copolymer based on the combined weights of all A and B blocks, and is hydrogenated to greater than 95 percent, while block A is hydrogenated to at least 90 percent.

The hydrogenated pentablock copolymers of the present invention having these Mn, block content and hydrogenation characteristics, have superior properties and processability characteristics when compared to other block and pentablock copolymers, especially in thin wall injection molding applications such as optical media discs. The hydrogenated copolymers of the present invention also exhibit higher resistance to yield, and improved toughness. In addition, the pentablocks exhibit lower melt viscosity compared to the conventional hydrogenated diblock and triblock copolymers at identical molecular weights.

The hydrogenated pentablock copolymers of the present invention are advantageously used in thin wall injection molded applications such as optical media discs due to their excellent processability, birefringence, dimensional stability and other physical properties.

The present invention relates to a composition comprising a hydrogenated pentablock copolymer, wherein the copolymer is prepared by hydrogenating a pentablock copolymer produced from at least one vinyl aromatic monomer and at least one conjugated diene monomer, having the structure ABABA, wherein the A block is a hydrogenated polymerized vinyl aromatic monomer, herein referred to as hydrogenated vinyl aromatic

polymer, and the B block is a hydrogenated polymerized conjugated diene monomer, herein referred to as a hydrogenated conjugated diene polymer.

The vinyl aromatic monomer is typically a monomer of the formula: wherein R is hydrogen or alkyl, Ar is phenyl, halophenyl, alkylphenyl, alkylhalophenyl, naphthyl, pyridinyl, or anthracenyl, wherein any alkyl group contains 1 to 6 carbon atoms which may be mono or multisubstituted with functional groups such as halo, nitro, amino, hydroxy, cyano, carbonyl and carboxyl. More preferably Ar is phenyl or alkyl phenyl with phenyl being most preferred. Typical vinyl aromatic monomers include styrene, alpha- methylstyrene, all isomers of vinyl toluene, especially paravinyltoluene, all isomers of ethyl styrene, propyl styrene, butyl styrene, vinyl biphenyl, vinyl naphthalene, vinyl anthracene and the like, and mixtures thereof. The pentablock copolymer can contain more than one specific polymerized vinyl aromatic monomer. For instance, the pentablock copolymer can contain a polystyrene block and a poly-alpha-methylstyrene block. The hydrogenated vinyl aromatic polymer block may also be a copolymer of a vinyl aromatic wherein the vinyl aromatic portion is at least 50 weight percent of the copolymer.

The conjugated diene monomer can be any monomer having 2 conjugated double bonds. Such monomers include for example 1, 3-butadiene, 2-methyl-1, 3-butadiene, 2- methyl-1,3 pentadiene, isoprene and similar compounds, and mixtures thereof. The pentablock copolymer can contain more than one specific polymerized conjugated diene monomer. In other words, the pentablock copolymer can contain a polybutadiene block and a polyisoprene block.

The conjugated diene polymer block can be chosen from materials which remain amorphous after the hydrogenation process, or materials which are capable of crystallization after hydrogenation. Hydrogenated polyisoprene blocks remain amorphous, while hydrogenated polybutadiene blocks can be either amorphous or crystallizable depending upon their structure. Polybutadiene can contain either a 1,2 configuration, which hydrogenates to give the equivalent of a 1-butene repeat unit, or a 1, 4-configuration, which hydrogenates to give the equivalent of an ethylene repeat unit. Polybutadiene blocks having

at least approximately 40 weight percent 1,2-butadiene content, based on the weight of the polybutadiene block, provides substantially amorphous blocks with low glass transition temperatures upon hydrogenation. Polybutadiene blocks having less than approximately 40 weight percent 1,2-butadiene content, based on the weight of the polybutadiene block, provide crystalline blocks upon hydrogenation. Depending on the final application of the polymer it may be desirable to incorporate a crystalline block (to improve solvent resistance) or an amorphous, more compliant block. The conjugated diene polymer block may also be a copolymer of a conjugated diene, wherein the conjugated diene portion of the copolymer is at least 50 weight percent of the copolymer.

A block is herein defined as a polymeric segment of a copolymer which exhibits microphase separation from a structurally or compositionally different polymeric segment of the copolymer. Microphase separation occurs due to the incompatibility of the polymeric segments within the block copolymer. Microphase separation and block copolymers are widely discussed in"Block Copolymers-Designer Soft Materials", PHYSICS TODAY, February, 1999, pages 32-38.

The hydrogenated pentablock copolymer of the present invention typically contains from 65 to 90 weight percent of a hydrogenated vinyl aromatic polymer, for example polyvinylcyclohexane or PVCH block, preferably from 70 to 85 percent, based on the total weight of the hydrogenated pentablock copolymer.

The hydrogenated pentablock copolymers of the present invention typically contain from 10 to 35 weight percent of a hydrogenated conjugated diene polymer block, preferably from 11, more preferably from 13, and most preferably from 15 to 34 weight percent, typically to 33, preferably to 32, more preferably to 31, and most preferably to 30 percent, based on the total weight of the hydrogenated pentablock copolymer.

The total number average molecular weight (Mn) of the hydrogenated pentablock copolymers of the present invention is typically from 40,000, preferably from 42,000, more preferably from 46,000 and most preferably from 50,000 to 70,000. Number average molecular weight (Mn) as referred to throughout this application is determined using gel permeation chromatography (GPC). The molecular weight of the hydrogenated pentablock copolymer and properties obtained are dependent upon the molecular weight of each of the hydrogenated polymeric blocks. It has been discovered that by optimizing the molecular weight of the hydrogenated polymeric blocks, hydrogenated block copolymers of low

molecular weight (40,000 to 70,000) can achieve high heat distortion temperatures and excellent toughness and tensile strength properties. Surprisingly, we have found that good physical properties can be obtained at relatively low hydrogenated block copolymer molecular weight which gives superior processability.

Typical number average molecular weight values for each hydrogenated vinyl aromatic polymer block are from 10,000, preferably from 11,000 to 50, 000, preferably to 40,000, more preferably to 30,000 and most preferably to 20,000. It should be noted that good properties are obtained at hydrogenated vinyl aromatic polymer molecular weights which are lower than the entanglement molecular weight of the hydrogenated vinyl aromatic polymer. It is generally accepted in the art that the weight average molecular weight of a polymer must far exceed the entanglement molecular weight in order to achieve acceptable properties. The entanglement molecular weight of a polymer is associated with the chain length required for a given polymer to show a dramatic increase in melt viscosity due to chain entanglements. The entanglement molecular weights for many common polymers have been measured and reported in Macromolecules, 1994, Volume 27, page 4639. It is commonly observed for glassy polymers that maximum values of strength and toughness are achieved at about 10 times the entanglement molecular weight (see for instance Styrene Polymers in the Encyclopedia of Polymer Science and Engineering, 2nd edition, Volume 16, pages 62-71,1989). The entanglement molecular weight is approximately 38,000 for polyvinylcyclohexane. We have determined that an optimum balance of properties and processability can be obtained at hydrogenated vinyl aromatic polymer block molecular weights (Mn) of less than 0.6 times the entanglement molecular weight of a hydrogenated vinyl aromatic polymer. The molecular weight of each hydrogenated conjugated diene polymer block is typically lower than that of the hydrogenated vinyl aromatic polymer block when a high modulus, rigid polymer is desired. The molecular weight of each hydrogenated diene polymer block is typically from 2,000, preferably from 2,500, more preferably from 3,000 and most preferably from 3,750 to 20,000, preferably to 15,000, more preferably to 12,000 and most preferably to 10,500.

It is important to note that each individual block of the hydrogenated pentablock copolymer can have its own distinct Mn. In other words, for example, the hydrogenated vinyl aromatic polymer blocks within the hydrogenated pentablock copolymer of the present invention may each have a different Mn.

Methods of making block copolymers are well known in the art. Typically, block copolymers are made by anionic polymerization, examples of which are cited in Anionic Polymerization : Principles a ld Practical Applications, H. L. Hsieh and R. P. Quirk, Marcel Dekker, New York, 1996. In one embodiment, block copolymers are made by sequential monomer addition to a carbanionic initiator such as sec-butyl lithium or n-butyl lithium. In another embodiment, the pentablock copolymer is made by coupling a triblock material with a divalent coupling agent such as 1,2-dibromoethane, dichlorodimethylsilane, or phenylbenzoate. In this embodiment, a small chain (less than 10 monomer repeat units) of a conjugated diene polymer can be reacted with the vinyl aromatic polymer coupling end to facilitate the coupling reaction. Vinyl aromatic polymer blocks are typically difficult to couple, therefore, this technique is commonly used to achieve coupling of the vinyl aromatic polymer ends. The small chain of diene polymer does not constitute a distinct block since no microphase separation is achieved. The coupled structure achieved by this method is considered to be the functional equivalent of the ABABA pentablock copolymer structure.

Coupling reagents and strategies which have been demonstrated for a variety of anionic polymerizations are discussed in Hsieh and Quirk, Chapter 12, pgs. 307-331. In another embodiment, a difunctional anionic initiator is used to initiate the polymerization from the center of the block system, wherein subsequent monomer additions add equally to both ends of the growing polymer chain. An example of a such a difunctional initiator is 1,3-bis (l- phenylethenyl) benzene treated with organolithium compounds, as described in U. S Patents 4,200,718 and 4, 196,154.

After preparation of the pentablock copolymer, the copolymer is hydrogenated to remove sites of unsaturation in both the conjugated diene polymer block and the vinyl aromatic polymer block segments of the copolymer. Any method of hydrogenation can be used and such methods typically include the use of metal catalysts supported on an inorganic substrate, such as Pd on BaS04 (U. S. Patent 5,352,744) and Ni on kieselguhr (U. S. Patent 3,333,024). Additionally, soluble, homogeneous catalysts such as those prepared from combinations of transition metal salts of 2-ethylhexanoic acid and alkyl lithiums can be used to fully saturate block copolymers, as described in Die Makromolekulare Chemie, volume 160, pp 291,1972. The copolymer hydrogenation can also be achieved using hydrogen and a heterogeneous catalyst such as those described in U. S. patents 5,352,744, U. S. 5,612,422 and U. S. 5,645,253. The catalysts described therein are heterogeneous catalysts consisting

of a metal crystallite supported on a porous silica substrate. An example of a silica supported catalyst which is especially useful in the polymer hydrogenation is a silica which has a surface area of at least 10 m2/g which is synthesized such that it contains pores with diameters ranging between 3000 and 6000 angstroms. This silica is then impregnated with a metal capable of catalyzing hydrogenation of the polymer, such as nickel, cobalt, rhodium, ruthenium, palladium, platinum, other Group VIII metals, combinations or alloys thereof.

Other heterogeneous catalysts can also be used, having a diameter in the range of from 500 to 3,000 angstroms.

Alternatively, the hydrogenation can be conducted in the presence of a mixed hydrogenation catalyst characterized in that it comprises a mixture of at least two components. The first component comprises any metal which will increase the rate of hydrogenation and includes nickel, cobalt, rhodium, ruthenium, palladium, platinum, other Group VIII metals, or combinations thereof. Preferably rhodium and/or platinum is used.

However, platinum is known to be a poor hydrogenation catalyst for nitriles, therefore, platinum would not be preferred in the hydrogenation of nitrile copolymers. The second component used in the mixed hydrogenation catalyst comprises a promoter which inhibits deactivation of the Group VIII metal (s) upon exposure to polar materials, and is herein referred to as the deactivation resistant component. Such components preferably comprise rhenium, molybdenum, tungsten, tantalum or niobium or mixtures thereof.

The amount of the deactivation resistant component in the mixed catalyst is at least an amount which significantly inhibits the deactivation of the Group VIII metal component when exposed to polar impurities within a polymer composition, herein referred to as a deactivation inhibiting amount. Deactivation of the Group VIII metal is evidenced by a significant decrease in hydrogenation reaction rate. This is exemplified in comparisons of a mixed hydrogenation catalyst and a catalyst containing only a Group VIII metal component under identical conditions in the presence of a polar impurity, wherein the catalyst containing only a Group VIII metal component exhibits a hydrogenation reaction rate which is less than 75 percent of the rate achieved with the mixed hydrogenation catalyst.

Preferably, the amount of deactivation resistant component is such that the ratio of the Group VIII metal component to the deactivation resistant component is from 0.5: 1 to 10: 1, more preferably from 1 : 1 to 7 : 1, and most preferably from 1: 1 to 5: 1.

The mixed catalyst can consist of the components alone, but preferably the catalyst additionally comprises a support on which the components are deposited. In one embodiment, the metals are deposited on a support such as a silica, alumina or carbon. In a more specific embodiment, a silica support having a narrow pore size distribution and surface area greater than 10 meters squared per gram (m2/g) is used.

The pore size distribution, pore volume, and average pore diameter of the support can be obtained via mercury porosimetry following the proceedings of ASTM D-4284-83.

The pore size distribution is typically measured using mercury porosimetry.

However, this method is only sufficient for measuring pores of greater than 60 angstroms.

Therefore, an additional method must be used to measure pores less than 60 angstroms.

One such method is nitrogen desorption according to ASTM D-4641-87 for pore diameters of less than about 600 angstroms. Therefore, narrow pore size distribution is defined as the requirement that at least 98 percent of the pore volume is defined by pores having pore diameters greater than 300 angstroms and that the pore volume measured by nitrogen desorption for pores less than 300 angstroms, be less than 2 percent of the total pore volume measured by mercury porosimetry.

The surface area can be measured according to ASTM D-3663-84. The surface area is typically between 10 and 100 m2/g, preferably between 15 and 90 with most preferably between 50 and 85 m2/g.

The desired average pore diameter of the support for the mixed catalyst is dependent upon the polymer which is to be hydrogenated and its molecular weight (Mn). It is preferable to use supports having higher average pore diameters for the hydrogenation of polymers having higher molecular weights to obtain the desired amount of hydrogenation.

For high molecular weight polymers (Mn>200,000 for example), the typical desired surface area can vary from 15 to 25 m2/g and the desired average pore diameter from 3,000 to 4000 angstroms. For lower molecular weight polymers (Mn<100, 000 for example), the typical desired surface area can vary from 45 to 85 m2/g and the desired average pore diameter from 300 to 700 angstroms.

Silica supports are preferred and can be made by combining potassium silicate in water with a gelation agent, such as formamide, polymerizing and leaching as exemplified in U. S. Patent No. 4,112,032. The silica is then hydrothermally calcined as in Iler, R. K., The Chemistry of Silica, John Wiley and Sons, 1979, pp. 539-544, which generally consists

of heating the silica while passing a gas saturated with water over the silica for about 2 hours or more at temperatures from 600°C to 850°C. Hydrothermal calcining results in a narrowing of the pore diameter distribution as well as increasing the average pore diameter.

Alternatively, the support can be prepared by processes disclosed in Iler, R. K., The Chemistry of Silica, John Wiley and Sons, 1979, pp. 510-581.

A silica supported catalyst can be made using the process described in U. S. Patent No. 5,110,779. An appropriate metal, metal component, metal containing compound or mixtures thereof, can be deposited on the support by vapor phase deposition, aqueous or nonaqueous impregnation followed by calcination, sublimation or any other conventional method, such as those exemplified in Studies in Surface Science and Catalysis,"Successful Design of Catalysts"V. 44, pg. 146-158,1989 and Applied Heterogeneous Catalysis pgs.

75-123, Institute Français du Pétrole Publications, 1987. In methods of impregnation, the appropriate metal containing compound can be any compound containing a metal, as previously described, which will produce a usable hydrogenation catalyst which is resistant to deactivation. These compounds can be salts, coordination complexes, organometallic compounds or covalent complexes.

Typically, the total metal content of the mixed supported catalyst is from 0.1 to 10 wt. percent based on the total weight of the silica supported catalyst. Preferable amounts are from 2 to 8 wt. percent, more preferably 0.5 to 5 wt. percent based on total catalyst weight.

Promoters, such as alkali, alkali earth or lanthanide containing compounds, can also be used to aid in the dispersion of the metal component onto the silica support or stabilization during the reaction, though their use is not preferred.

The amount of mixed supported catalyst used in the hydrogenation process is much smaller than the amount required in conventional unsaturated polymer hydrogenation reactions due to the high reactivity of the hydrogenation catalysts. Generally, amounts of less than 1 gram of supported catalyst per gram of unsaturated polymer are used, with less than 0.1 gram being preferred and less than 0.05 being more preferred. The amount of supported catalyst used is dependent upon the type of process, whether it is continuous, semi-continuous or batch, and the process conditions, such as temperature, pressure and reaction time wherein typical reaction times may vary from 5 minutes to 5 hours.

Continuous operations can typically contain 1 part by weight supported catalyst to 200,000 or more parts unsaturated polymer, since the supported catalyst is reused many times during

the course of continuous operation. Typical batch processes can use 1 part by weight supported catalyst to 5,000 parts unsaturated polymer. Higher temperatures and pressures will also enable using smaller amounts of supported catalyst.

The hydrogenation reaction can be conducted in the absence of a solvent but is preferably conducted in a hydrocarbon solvent in which the polymer is soluble and which will not hinder the hydrogenation reaction. Preferably the solvent is a saturated solvent such as cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, dioxane, diethylene glycol dimethyl ether, tetrahydrofuran, isopentane, decahydronaphthalene or mixtures thereof, with cyclohexane being the most preferred.

The temperature at which the hydrogenation is conducted can be any temperature at which hydrogenation occurs without significant degradation of the polymer. Degradation of the polymer can be detected by a decrease in Mn, an increase in polydispersity or a decrease in glass transition temperature, after hydrogenation. Significant degradation in polymers having a polydispersity between 1.0 and 1.2 can be defined as an increase of 30 percent or more in polydispersity after hydrogenation. Preferably, polymer degradation is such that less than a 20 percent increase in polydispersity occurs after hydrogenation, most preferably less than 10 percent. In polymers having polydispersity greater than about 1.2, a significant decrease in molecular weight after hydrogenation indicates that degradation has occurred.

Significant degradation in this case is defined as a decrease in Mn of 20 percent or more.

Preferably, a Mn decrease after hydrogenation will be less than 10 percent. However, polymers such as poly-alpha-methylstyrene or other alpha substituted vinyl aromatic polymers which are more prone to polymer degradation, can tolerate a decrease in Mn of up to 30 percent.

Typical hydrogenation temperatures are from 40°C preferably from 100°C, more preferably from 110°C, and most preferably from 120°C to 250°C, preferably to 200°C, more preferably to 180°C, and most preferably to 170°C.

The pressure of the hydrogenation reaction is not critical, though hydrogenation rates increase with increasing pressure. Typical pressures range from atmospheric pressure to 70 MPa, with 0.7 to 10. 3 MPa being preferred.

The hydrogenation reaction vessel is purged with an inert gas to remove oxygen from the reaction area. Inert gases include but are not limited to nitrogen, helium, and argon, with nitrogen being preferred.

The hydrogenating agent can be any hydrogen producing compound which will efficiently hydrogenate the unsaturated polymer. Hydrogenating agents include, but are not limited, to hydrogen gas, hydrazine and sodium borohydride. In a preferred embodiment, the hydrogenating agent is hydrogen gas.

The level of hydrogenation of the pentablock copolymer of the present invention is preferably greater than 95 percent of the conjugated diene polymer block and greater than 90 percent of the vinyl aromatic polymer block segments, more preferably greater than 99 percent of the conjugated diene polymer block and greater than 95 percent of the vinyl aromatic polymer block segments, even more preferably greater than 99.5 percent of the conjugated diene polymer block and greater than 98 percent of the vinyl aromatic polymer block segments, and most preferably greater than 99.9 percent of the conjugated diene polymer block and 99.5 percent of the vinyl aromatic polymer block segments. The term 'level of hydrogenation'refers to the percentage of the original unsaturated bonds which become saturated upon hydrogenation. The level of hydrogenation in hydrogenated vinyl aromatic polymers is determined using UV-VIS spectrophotometry, while the level of hydrogenation in hydrogenated diene polymers is determined using proton NMR.

Another aspect of the present invention is a thin wall injection molded article such as an optical media disc prepared from a hydrogenated pentablock copolymer as described previously. Discs can be molded using any molding technique such as those described in The Compact Disc Handbook, 2nd edition, by Pohlmann.

Methods of molding optical media discs are well known in the art and include injection-compression molding. A preferred method includes injection compression- molding as described in Injection Molding An Introduction, pgs. 171-172 Hanser/Gardner/ Publication, Inc., Cincinnati, 1995 by Potsch and Michaeli.

It has been found that the use of the compositions of the present invention are far superior in processability and dimensional stability for applications which have a need for thin walls. The properties required for such compositions in these applications include high flowability and toughness among others. The advantage of a hydrogenated pentablock system is one of flow and toughness balance.

It is thought, without being bound to such, that this balance of properties is provided by a unique morphology in such pentablock polymers. The use of standard morphological determination techniques such as transmission electron microscopy and small angle X-ray

scattering have shown that the copolymers of this invention, when fabricated via typical fabrication methods (injection molded, compression molded, extruded sheet, etc.), do not have well defined morphological features typically found in block copolymers. These typical morphologies with long range order are described in"Block Copolymers-Designer Soft Materials"by Bates and Fredrickson, Physics Today, Feb. 1999, Vol. 52, No. 2, pgs.

32-38. Hydrogenated pentablocks in this molecular weight and composition range are clearly surprising in that they have excellent mechanical properties such as tensile elongation even though they lack longer-range order and a well defined morphology. In addition, these polymers have superior processability. Rheological analysis of the melt, ramping up temperature at low shear rates, results in elastic modulus decreases that are gradual and continuous, as opposed to the discontinuous decreases due to order-disorder transition typically observed in block copolymers which show longer-range order.

The hydrogenated block copolymers of the present invention are useful in the production of optical media storage devices such as discs, flash memory cards, integrated circuit cards, smart cards, and other media or information-carrying substrates.

In particular, the hydrogenated block copolymers of the present invention are useful in the production of optical storage media devices and components thereof. Optical storage media components include a transparent substrate, a protective layer, a protective case, or an information layer, any of which can comprise the hydrogenated block copolymers of the present invention. Examples of storage media formats which use these devices include prerecorded, recordable and rewriteable versions of CD and DVD formats, optical recording mediums such as those disclosed in U. S. Patent Nos. 4,965,114 and 5,234,792, all of which are well known in the art and discussed in The Compact Disc Handbook 2 Edition by Pohlmann.

The hydrogenated block copolymers of the present invention can be used to produce the information carrying transparent substrates for both CD (compact disc) and DVD (digital versatile disc) prerecorded formats as, for example, disclosed in U. S. Patent No.

5,635,114. In the case of the CD format the transparent substrate is coated with a reflective metal layer, for example, aluminum, followed by a protective coating, for example, a U. V. curable lacquer. The DVD structure includes two information carrying substrates, for example, comprising the hydrogenated block copolymers of the present invention, which are sputtered with an aluminum reflective layers, or gold or silicon semi-reflective layers. The

individual substrates are bonded together to form a dual layer disc with an overall thickness equal to the thickness of a CD media device. In order to produce high density pre-recorded DVD formats, stampers are inserted into the mold with track pitch of 0.4 to 0.5 in order to achieve data density of 10 to 20 Gb. High density developmental formats can also use a data carrying thin film layer which is supported by a non-data containing substrate layer in which case either or both media layers can be produced from the hydrogenated block copolymers of the present invention.

Hydrogenated block copolymers are also useful for the production of substrates with a wobbled spiral groove for recordable optical disc formats. The substrate is typically coated with a light absorbing dye layer and then a reflective layer. Examples of reflective layers include gold or silver. During the recording process the dye absorbs heat from the laser beam recorder. The substrate, dye and reflective layer composite structure is deformed by the heat which forms a permanent pit. Signal strength is enhanced by optical change in the dye. Dual layer DVD style media differs from CD format in that two groove containing substrates are bonded together to form a single optical storage device with information stored on two layers.

In a specific embodiment, one aspect of the present invention is a pre-recorded or recordable optical media disc comprising: (a') a first substrate layer; (b') an optional first photosensitive dye layer; (c') at least one group of the following two reflective or semi-reflective sublayers: (i') a first sublayer comprising a metal, an inorganic carbide, or an inorganic nitride; (ii') a second sublayer comprising a protective or adhesive composition; (d') an optional second metal/inorganic layer comprising a metal, an inorganic carbide, or an inorganic nitride; (e') an optional second photosensitive dye layer; (f) an optional second substrate layer; wherein at least one of the first substrate layer or optional second substrate layer comprises the hydrogenated block copolymer composition of the present invention.

Suitable photosensitive dye layers include photosensitive nitrogen-containing compounds, such as cyanine phthalocyanine, and azo-compounds. Typically, the photosensitive dye layer will be at least 1 microns, preferably at least 10 microns; typically no more than 100 microns, preferably no more than 75 microns.

Suitable reflective or semi-reflective metal layers and sublayers include elemental aluminum, silver, or gold. Other suitable reflective or semi-reflective sublayers include silicon compounds such as silicon nitride and silicon carbide. Typically, the reflective or semi-reflective layer or sublayer will be at least 5 nm, preferably at least 10 nm ; typically no more than 100 nm, preferably no more than 30 nm in thickness. The metal layer may be applied by cathode sputtering techniques well-known in the art.

Suitable protective compositions include, for example, photocured acrylates (such as polymethylmethacrylate, epoxy acrylates). Such lacquers will include a photoinitiator, such as to result in, for example, radical curing or cationic UV curing of the lacquer.

Suitable adhesive compositions include hot melt or solvent based adhesives. Such adhesives will typically comprise a polymeric component (for example, polyethylene, styrene block copolymers (including block copolymers having been hydrogenated along the backbone, such as SBS, SEBS, SPS, SEPS, and SIS), amorphous polyolefins, etc.), in conjunction with one or more additional components selected from the group consisting of waxes, tackifiers, plasticizers, and fillers. The polymeric component may be optionally functionalized, such as to promote adhesion between the adjacent components.

In a specific embodiment, the hydrogenated block copolymers of the present invention are used to produce pre-recorded audio compact discs (CD-audio). Specifications for a compact disc system are well known in the art and disclosed in The Compact Disc Handbook, 2nd Edition, Pohlmann, pg. 49. The disc diameter is 120 millimeters (mm), the hole diameter is 15 mm and the thickness is 1.2 mm. Data is recorded on an area 35.5 mm wide. The CD substrate comprises the hydrogenated block copolymers of the present invention and is transparent. Data is physically contained in pits which are impressed along its top surface and are covered with a very thin (50 to 100 nanometers) metal such as aluminum, silver or gold. Another thin plastic layer of 10 to 30 micrometers protects the metallized pit surface, on top of which the identifying label is printed.

A specific embodiment of the present invention is a pre-recorded CD comprising: (al) a substrate layer;

(bl) a metal layer, wherein the metal is preferably selected from the group consisting of aluminum, silver, or gold; and (cl) a lacquer layer; wherein the substrate comprises the composition of the first aspect of the present invention.

In another specific embodiment, the optical media disc will be a CD-R (recordable), comprising: (a2) a substrate; (b2) a photosensitive dye layer; (c2) a reflective or semi-reflective metal layer; and (d2) a lacquer.

The substrate, dye layer, metal and lacquer are as described previously.

In another specific embodiment, the optical media disc can be a DVD such as a DVD-5 disk, comprising: (a3) a first substrate layer; (b3) a metal layer, preferably selected from the group consisting of gold and silver; (c3) a lacquer layer; and (d3) a second substrate layer, wherein at least one of the first substrate layer or second substrate layer comprises a hydrogenated block copolymer of the present invention.

In another embodiment, the optical media disc will be a DVD-9 disk, comprising: (a4) a first substrate layer; (b4) an inorganic carbide or inorganic nitride layer, preferably selected from the group consisting of silica carbide and silica nitride, or alternatively a gold layer; (c4) a lacquer layer; (d4) a metal layer, typically aluminum or alloy thereof ; and (e4) a second substrate layer, wherein at least one of the first substrate layer or second substrate layer comprises a hydrogenated block copolymer of the present invention.

In another embodiment, the optical media disc will be a DVD-14 disc, comprising: (a5) a first substrate layer;

(b5) an inorganic carbide or inorganic nitride layer, preferably selected from the group consisting of silica carbide and silica nitride, or alternatively a gold layer; (c5) a lacquer layer; (d5) at least one group of the following two sublayers: (i5) a first sublayer comprising a metal, an inorganic carbide, or an inorganic nitride, preferably a metal in each instance, more preferably aluminum or gold in each instance; (ii5) a second sublayer comprising a protective lacquer or an adhesive composition; (e5) a second substrate layer; wherein at least one of the first substrate layer and the second substrate layer comprises a hydrogenated block copolymer of the present invention.

In another embodiment, the optical media disc will be a DVD-18 disc, comprising: (a6) a first substrate layer; (b6) a first inorganic carbide or inorganic nitride layer, preferably selected from the group consisting of silica carbide and silica nitride, or alternatively a gold layer; (c6) a lacquer layer; (d6) at least two groups of the following two sublayers: (i6) a first sublayer comprising a metal, an inorganic carbide, or an inorganic nitride, preferably a metal in each instance, more preferably aluminum or gold in each instance; (ii6) a second sublayer comprising a protective lacquer or an adhesive composition ; (e6) a second inorganic carbide or inorganic nitride layer, preferably selected from the group consisting of silica carbide and silica nitride; and (f6) a second substrate layer; wherein at least one of the first substrate layer and the second substrate layer comprises a hydrogenated block copolymer of the present invention.

Metal layers, lacquers and inorganics recited herein, are as previously described herein.

The hydrogenated block copolymers of the present invention can also be used in other CD formats including CD-ROM, CD-I, DVI, CD-V, CD+G/M, mini-discs and CD-3.

CD-ROM (Read Only Memory) incorporates nonaudio data, such as data base and software data. CD-I (Interactive) and DVI are specific applications of CD-ROM, wherein data storage includes audio-visual information stored in a user interactive manner. DVI (Digital Video Interactive) is an all digital optical disc format capable of reproducing full-motion, full-screen video, computer-generated video graphics and digital audio via a CD-ROM drive. CD-V is a combination of audio and video technology which merges the audio with Laservision video format. Other CD formats which can be produced from the composition of the present invention include CD+G/M (Graphics) which is a storage disc for graphics and other nonmusical data. This format takes advantage of the nonaudio data area, wherein still color images, text or other material is stored on an audio compact disc and displayed on a television monitor while the music plays. Another format is CD-3 which is used for applications requiring shorter playing time. The data format is identical to the regular 12 cm diameter CD, but its diameter is only 8 cm and can additionally be used for CD-ROM applications. Photo CD's and CDTV may also be produced from the composition of the present invention. CDTV, which is similar to CD-I, employs the compact disc standard as a basis for multimedia presentations of audio and video including images, graphics, text and animation.

Hydrogenated block copolymers can also be used as the transparent substrate and/or the protective layer of a rewritable/erasable disc having one or more layers. In this case the recording layer is sandwiched between a transparent substrate, for example comprising the hydrogenated block copolymer of the present invention, and a protective layer. The recording layer is typically approximately 50 nm thick. Recording layers include magneto- optical and phase-change layers. For magneto-optical formats several magnetic materials can be used for recording layers including rare-earth transition metals such as gadolinium terbium iron, terbium iron cobalt, and terbium iron.

In one embodiment, the rewritable/erasable disc comprises: (a7) a substrate; (b7) a recordable metal layer; and (c7) a protective layer.

In particular, the polymers of the present invention will be usefully employed in a rewriteable/erasable optical media disc comprising: (a8) a first substrate layer

(b8) a first inorganic layer; (c8) a metal alloy 1 ; tyer ; (d8) a second inorg mic layer; (e8) a metal layer; (f8) a lacquer layer; and (g8) optionally, one or more of an optional second metal layer, an optional third and/or fourth inorganic layer, and optional second metal alloy layer, and an optional second substrate layer, wherein at least one of the first substrate layer and the optional second substrate layer comprises a hydrogenated block copolymer of the present invention.

In another specific embodiment, rewriteable/erasable CD formats can also be produced from the hydrogenated block copolymers of the present invention.. In one embodiment, a rewriteable/erasable CD comprises : (a8') a substrate; (b8') a barrier layer; (c8') a magneto optical layer or a phase change layer; (d8') a barrier layer; (e8') a reflective or semi-reflective metal layer; (f8') a lacquer.

The substrate comprises the composition of the present invention. The barrier layer is typically a tin nitride for magneto optical or ZnS-Si02 for phase change discs. The magneto optical layer is, for example TbFeCo, while the phase change layer is, for example an alloy of TeGeSb. The reflective or semi-reflective layers are as taught previously and are preferably an aluminum alloy. The lacquer typically comprises a photocurable acrylic as taught previously.

Rewritable and erasable DVD formats include DVD-RAM (Random Access Memory), DVD+RW (Rewriteable) and DVD-R/W (Rewriteable) formats which are all based on phase change technology. Phase change technology uses the difference in reflectivity of the low reflectivity amorphous or high reflectivity crystalline state. The phase change alloy is made of tellurium, germanium and antimony (TeGeSb). The active phase change layer is surrounded by two dielectric films (ZnS-Si02) and covered by an aluminum alloy reflector and protective coating. The difference in reflectivity of the phase change

layer is accomplished by heating the layer by laser beam and this becomes the data storage surface.

Additionally, the hydrogenated block copolymers of the present invention can be used to produce a mini-disc. The mini-disc is a 2.5 inch, recordable, erasable, optical disc format, which stores 74 minutes of stereo digital audio. Mini-discs and methods of making are well known to those skilled in the art.

In another embodiment, the hydrogenated block copolymers of the present invention are used to produce digital business cards comprising: (a9) a substrate layer, (b9) a first metal layer covering at least a portion of the first substrate layer, and (c9) a lacquer layer, wherein the substrate layer comprises the hydrogenated block copolymers of the present invention. The metal layer and lacquer layer can be substances as taught previously within this specification. These cards are typically the size of a standard business card, having a thickness of approximately 1.2mm and contain 40 to 50 megabytes of information.

In another embodiment, the hydrogenated block copolymers of the present invention are used to produce thin film discs as disclosed in U. S. Patents 4,356,066 and 4,880,514, as well as EP-892,393. U. S. Patent No. 4,356,066 discloses multi-layer magnetic thin film discs comprising a synthetic resin layer on an aluminum-containing substrate and an overlying metallic magnetic layer. In one embodiment of the present invention a thin film disc is produced comprising, (al 0) a substrate; (b 10) a synthetic resin layer; (c 10) at least one thin metal layer which may also serve as a metallic magnetic layer; and (d10) optionally, a metallic magnetic layer, if not included in c9). wherein the substrate or synthetic resin layer comprises a hydrogenated block copolymer of the present invention.

In another aspect, thin film magnetic recording members as disclosed in U. S. Patent No. 4,880,514, can also be made from the composition of the present invention. In one embodiment, a thin film magnetic recording member comprises: (all) a substrate;

(bl l) a metal layer, such as chromium; (c 11) a metal alloy recording layer; wherein the substrate comprises a hydrogenated block copolymer of the present invention.

In another embodiment, the hydrogenated block copolymers of the present invention are used to produce smart cards as disclosed in U. S. Patent 6,025,054 and U. S. Patent 5,955,021. Smart cards are small cards the size of a conventional credit card containing an IC (integrated circuit) chip and are used as bankcards, ID cards, and telephone cards. They are based upon the use of an electromagnetic coupling (either by physical contact or by electromagnetic waves) between the smart card's electronic components and a card reader or other receiving device. Such cards are usually made by assembling several layers of plastic sheets in a sandwich array. Typically, the smart card comprises: (a 12) a first substrate layer; (bl2) a second substrate layer; and (c12) a center or core layer comprising a thermosetting polymeric material, having an electronic component embedded therein, that is sandwiched between the first and second substrate layers; wherein all three layers are unified into a body by bonding action between the thermosetting polymeric material used to create the core layer and the materials out of which the first and second substrate layers are made and wherein at least one layer comprises a hydrogenated block copolymer of the present invention. Additionally, the smart card can comprise: (al 3) a substrate layer have an indentation, (bl3) an information-containing microchip retained within the indentation, wherein the substrate layer comprises a hydrogenated block copolymer of the present invention.

Methods of making optical media discs are well known in the art and described in The Compact Disc Handbook 2nd Edition by Pohlmann, and referenced in U. S. Patent No.

4,911,966.

The high data density optical media disc of the present invention has a retardation of less than 25 nm per 0.6 mm substrate (birefringence of less than 0.000042), and a water absorbance of less than 0.05% as measured according to ASTM D 570. Birefringence

Retardation is measured by placing a molded DVD disc substrate between crossed polarizers and quarter wave plates (oriented in opposition). The retardation is measured 20 mm from the injection gate of the disc using light from a 633 nm laser. Transmitted intensity is measured and the retardation calculated using the following formula: I = 10 sin2 ( (7t/) (And)) where Retardation = And Measured = I Incident intensity = I 0 Wavelength = X The birefringence is calculated from the measured retardation by dividing retardation by the thickness of the substrate. Preferably the retardation is less than 20 nm, more preferably less than 15 nm and most preferably less than 10 nm in a disc substrate which is 0.6 mm thick. The water absorbance is preferably less than 0.04%, more preferably less than 0.02% and most preferably less than 0.01%.

The following examples are provided to illustrate the present invention. The examples are not intended to limit the scope of the present invention and they should not be so interpreted. Amounts are in weight parts or weight percentages unless otherwise indicated.

Example 1 I) General Procedure for preparing Block Copolymers Sequential Polymerization of Pentablock Copolymer A mixture of 386 Kg of cyclohexane containing approximately 8 to 15 weight percent isopentane is added to a 1136 liter stirred reactor under nitrogen atmosphere. The reactor is blanked by adding 0.5 Kg of a cyclohexane solution which is 0.0979 molar in low molecular weight polystyryl lithium. To this mixture is added 1.08 liters of a 1.4M solution of sec-butyllithium in cyclohexane. The solution is heated to approximately 65°C and 22.6 Kg of styrene monomer is added, followed by a 34 Kg hydrocarbon solvent purge of the styrene line. After 20 minutes of polymerization, 11.3 Kg of butadiene monomer is added at a temperature of about 70°C, followed by 34 Kg of hydrocarbon solvent which is followed immediately by another styrene addition of 22.6 Kg. After another 20 minutes, a second

addition of 11.3 Kg of butadiene is made at about 70°C, followed by a 34 Kg line flush with solvent. After another 20 minutes, the third addition of 22.6 Kg of styrene is made and the polymerization continues for a final 20 minutes. At this point 114 grams of 2-propanol is added to terminate the reaction.

This general procedure is used to produce Examples 1-4, as listed in Table 1, with the only modifications being the percentages of polystyrene and polybutadiene, wherein obtaining such modifications are well known by those skilled in the art.

Table 1 Examples Actual Actual Actual % Polystyrene Actual % Polybutadiene Actual % 1,2 Mp* Mw/Mn before hydrogenation before hydrogenation Content 1 62000 1.03 71 29 11 2 60000 1.01 77 23 10 3 63000 1.02 80 20 8 4 61000 1.02 85 15 12 *Mp is peak Molecular weight.

These block copolymers are then hydrogenated such that all of the polybutadiene blocks and polystyrene blocks are completely saturated.

II) Hydrogenation Approximately 20 grams of a dried block copolymer is dissolved in 700 mL cyclohexane. This polymer is hydrogenated using a Pt on Si02 hydrogenation catalyst as described in U. S. Patent No. 5,612,422. The polymer to catalyst ratio is 10 to 1. The hydrogenation reaction is conducted in a PPI (Precision Pressure Industry) reactor for 12 hours at 177°C under 3447 MPa hydrogen.

Table 2 shows a series of physical properties for the hydrogenated block copolymers described above. Mechanical properties are obtained using compression molded samples.

Tensile properties are measured according to ASTM D638 using type 5 microtensile specimens at a crosshead speed of 0. 127cm/min. and a 101. 9 Kg load cell.

Table 2 Ex. Tensile Tensile Tensile Complex Melt Flow Yield Rupture Modulus Viscosity Rate (MPa) (MPa) (MPa) (poise) (g/min.) 1 29. 6 30. 3 1, 860 4 2 29.0 29. 0 1, 820 1.21 x 10 4 5 330.3 31. 4 2, 070 2. 89 x 103 95 431.7 31. 4 2, 140 <1000 187

The hydrogenated pentablock copolymers exhibit excellent toughness in combination with excellent flow properties.

CD Example A CD substrate is injection molded from the hydrogenated block copolymer of Example 1, using an injection molding machine with a maximum clamping force 600kN, maximum injection stroke capability of 100mm and injection screw diameter of 32mm. The substrate mold is a CD single cavity substrate mold. A data bearing stamper is inserted into the mold which contains approximately 0.6 Gb of data and a track pitch of approximately 1.6 microns. Process temperatures are melt temperatures of 290 to 330°C, and mold temperatures of 30 to 80°C. Injection velocity is varied from 25 mm/s to 125mm/s, increasing as the mold is filled. Once filled, the part is further packed with polymer by applying initial hold pressure of approximately 600 bar, which is then reduced to 0 bar over a period of 0.3 sec. The polymer injection shot size is approximately 30 mm to achieve a completely full part with an actual part thickness of 1. 2 mm. The overall cycle time for the process including part removal is 3 to 10 seconds. The CD substrate is 120 mm in diameter and 1.2 mm thick.

The CD substrate is inert gas plasma sputtered to deposit a reflective aluminum layer followed by a UV curable lacquer protective layer.

Similarly, a digital business card is produced using the appropriately shaped data stamper in the mold.

DVD Example A DVD substrate is injection compression molded from the hydrogenated block copolymer of Example 1, using an injection/compression molding machine with a maximum clamping force 600kN, maximum injection stroke capability of 100mm and

injection screw diameter of 32mm. The substrate mold is a DVD single cavity substrate mold. DVD 5 and 9 optical discs are prepared using data bearing stampers which are inserted into the mold which contain approximately 4.7 Gb of data, and a track pitch of approximately 0.74 microns. Process temperatures are melt temperatures of 290 to 330°C, and mold temperatures of 40 to 80°C. Injection velocity is varied from 25 mm/s to 200 mm/s, increasing as the mold is filled. Once filled, the part is further packed with polymer by applying initial hold pressure of approximately 300 bar which is then reduced to 0 bar over a period of 0.8 sec. The polymer injection shot size is approximately 13.5 mm to achieve a completely full part with an actual part thickness of 0.6 mm. The compression phase is accomplished by applying 55 to 65% clamp force to the injection mold at the time when approximately 85% of the polymer shot has been injected into the mold cavity. Prior to compression the mold cavity is typically between 1.0 and 1.2 mm thick. The overall cycle time for the process including part removal is 5 to 10 seconds. The DVD substrates are 120 mm in diameter and 0.6 mm thick.

Once molded, the DVD substrates are sputtered with an aluminum reflective layers.

Two individual substrates are bonded together to form a dual layer DVD 9 disc.

Similarly, in order to produce high density pre-recorded DVD formats, stampers are inserted into the mold with track pitch of 0.4 to 0.5 in order to achieve data density of 10 to 20 Gb.

Recordable DVD and CD formats Recordable versions of both CD and DVD formats are made in similar fashion to the prerecorded formats described above except for the following. The stamper produces a continuous spiral groove of combination of pits and a groove instead of data containing pits.

The substrate is then coated with a barrier layer, followed by either a magneto optic layer or a phase change alloy layer. Another barrier layer is applied followed by a reflective layer and finally a protective lacquer layer.

In the case of DVD recordable formats, two data layers are used with a gold semi reflective layer for one data layer and an aluminum reflective layer for the other.