U.S. patent application number 09/793321 was filed with the patent office on 2002-03-28 for hydrogenated vinyl aromatic hydrocarbon polymer composition and an optical disk substrate.
Invention is credited to Berglund, Charles A., Namhata, Sarada, Plaver, F. Michael.
Application Number | 20020037961 09/793321 |
Document ID | / |
Family ID | 24333892 |
Filed Date | 2002-03-28 |
United States Patent
Application |
20020037961 |
Kind Code |
A1 |
Plaver, F. Michael ; et
al. |
March 28, 2002 |
Hydrogenated vinyl aromatic hydrocarbon polymer composition and an
optical disk substrate
Abstract
The present invention relates to a composition comprising: A) a
polyolefin thermoplastic, B) a hydrogenated block copolymer of a
vinyl aromatic and conjugated diene monomer having a level of
aromatic hydrogenation of at least 70 percent, and C) at least one
linear or substantially linear ethylene/.alpha.-olefin polymer.
Inventors: |
Plaver, F. Michael;
(Midland, MI) ; Berglund, Charles A.; (Midland,
MI) ; Namhata, Sarada; (Midland, MI) |
Correspondence
Address: |
THE DOW CHEMICAL COMPANY
INTELLECTUAL PROPERTY SECTION
P. O. BOX 1967
MIDLAND
MI
48641-1967
US
|
Family ID: |
24333892 |
Appl. No.: |
09/793321 |
Filed: |
February 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09793321 |
Feb 26, 2001 |
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09583623 |
May 31, 2000 |
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Current U.S.
Class: |
525/70 |
Current CPC
Class: |
C08L 51/06 20130101;
C08L 51/06 20130101; C08L 23/10 20130101; C08L 2205/02 20130101;
C08L 51/06 20130101; C08L 2666/02 20130101; C08L 2666/02 20130101;
C08L 2666/24 20130101; C08L 2666/24 20130101; C08L 2666/04
20130101; C08L 2666/04 20130101; C08L 23/0815 20130101; C08L
2666/04 20130101; C08L 53/025 20130101; C08L 51/06 20130101; C08L
23/16 20130101; C08L 53/00 20130101; C08L 53/025 20130101; C08L
23/10 20130101; C08L 53/025 20130101; C08L 53/025 20130101 |
Class at
Publication: |
525/70 |
International
Class: |
C08L 051/00 |
Claims
What is claimed is:
1. A composition comprising: A) a polyolefin thermoplastic, B) a
hydrogenated block copolymer of a vinyl aromatic and conjugated
diene monomer having a level of aromatic hydrogenation of at least
70 percent, and C) at least one linear or substantially linear
ethylene/.alpha.-olefin polymer.
2. The composition of claim 1, wherein the polyolefin of A) is
polypropylene or an ethylene-propylene copolymer.
3. The composition of claim 1, wherein the polyolefin of A) is a
combination of polypropylene and an ethylene-propylene
copolymer.
4. The composition of claim 2 or 3, wherein the ethylene-propylene
copolymer contains from 5 to 20 percent ethylene and from 80 to 95
percent propylene.
5. The composition of claim 1, wherein the polyolefin of A) is
present in an amount of from 30 to 75 weight percent, based on the
total weight of the composition.
6. The composition of claim 1, wherein the hydrogenated block
copolymer is a hydrogenated styrene-butadiene block copolymer.
7. The composition of claim 1, wherein the composition comprises
from 1 to 45 weight percent of the hydrogenated block copolymer of
B), based on the total weight of the composition.
8. The composition of claim 1, wherein the ethylene/.alpha.-olefin
polymer is selected from the group consisting of homopolymers of
.alpha.-olefins, ethylene/propylene, ethylene/1-butene,
ethylene/1-hexene, ethylene/1-octene copolymers, a terpolymer of
ethylene, propylene and hexadiene, a terpolymer of ethylene,
propylene and ethylidenenorbornene and grafted derivatives
thereof.
9. The composition of claim 8, wherein the ethylene/.alpha.-olefin
polymer is ethylene/1-octene copolymer.
10. The composition of claim 1, wherein the ethylene/.alpha.-olefin
polymer is present in an amount of from 5 to 45 weight percent,
based on the total weight of the composition.
11. The composition of claim 1 additionally comprising a second
polyolefin, which is different from the polyolefin thermoplastic of
A).
12. The composition of claim 11, wherein the second polyolefin is
high density polyethylene.
13. The composition of claim 12, wherein the amount of high density
polyethylene is from 1 to 20 weight percent based on the total
weight of the polymer composition.
Description
CLAIM OF THE INVENTION
[0001] A hydrogenated vinyl aromatic hydrocarbon polymer
composition having a structure comprising two or three components
selected from among
[0002] (a) 1.about.100 wt % or less of a polymer produced by
hydrogenation of all the double bonds and an aromatic nuclei
included in vinyl aromatic hydrocarbon-conjugated diene block
copolymer,
[0003] (b) 0.about.95 wt % of a polymer produced by hydrogenation
of at least 80 mole % of the aromatic nuclei included in the vinyl
aromatic hydrocarbon, and/or
[0004] (c) 0.about.20 wt % of a saturated hydrocarbon resin with a
number average molecular weight of 500.about.5,000 and a softening
point of 40.degree. C. or higher (in this case, the sum of
component (b) and component (c) exceeds 0 wt %).
[0005] The hydrogenated vinyl aromatic hydrocarbon polymer
composition described in claim 1 of the invention wherein the
composition is used as an optical material.
[0006] An optical disk substrate made of the hydrogenated vinyl
aromatic hydrocarbon polymer composition described in claim 1 of
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0007] 1. Field of Industrial Application
[0008] The present invention pertains to a hydrogenated vinyl
aromatic hydrocarbon polymer composition having excellent
transparency, heat-resistance, and adhesion, and the invention
further pertains to an optical disk substrate made of the
above-mentioned hydrogenated vinyl aromatic hydrocarbon polymer
composition.
[0009] 2. Prior Art
[0010] High-density data recording, storage, and playback are made
possible in optical recordings made with a laser and active
development of materials has been underway in recent years. As an
example of the above-mentioned optical recording, optical disks can
be mentioned. In general, optical disks basically consist of a
transparent substrate and a variety of recording media-coated onto
the surface of the substrate.
[0011] In many cases, a colorless transparent synthetic resin is
used for the transparent substrate of the optical disk, and as
typical examples, polycarbonate (hereinafter referred to as "PC")
and polymethylmethacrylate (hereinafter referred to as "PMMA") can
be mentioned. The above-mentioned colorless resins have excellent
transparency and each has unique properties, but not all factors
required for optical disks are not included, and many problems
remain unsolved. For example, in the case of PC, a problem of
birefringence based on the aromatic ring exists, and moisture
absorption and moisture permeability pose problems as well. On the
other hand, problems based on inadequate heat-resistance, moisture
absorption, and rigidity have been pointed out for PMMA.
[0012] As described above, each of the above-mentioned resins are
used despite the unique problems mentioned above, but additional
problems described below exist in reality for recording media
coated onto transparent substrates made of these resins.
[0013] Meanwhile, a variety of research has been conducted for a
long time on recording media used for optical disk. For example,
for the so-called write-once type used exclusively for recording
and playback, a pit type-media is used, for the so-called
recording-playback-erase-recording type, a phase transition type
medium wherein crystal transition is used, magneto-optic type media
wherein the magneto-optic effect is utilized, etc. are known. In
the above-mentioned materials used for recording media, inorganic
materials, for example, tellurium or oxides thereof, alloy
compounds, etc. are used for write-once type, and amorphous alloy
compounds of rare earth metal-transition metal compounds such as
GdFe, TbFe, GdFeCo, and TbFeCo is mainly used for erasable type,
and in general, film formation is performed onto the transparent
substrate by means of dry treatment method such as sputtering under
high vacuum.
[0014] Furthermore, problems described below further exist based on
an inadequate heat-resistance of the resin used for the substrate.
In other words, the temperature of the recording medium at the time
of writing and erasing of the information becomes as high as
200.degree. C. in optical disks, especially, write-once type. It is
expected for the temperature of the substrate becomes very high at
the time of writing and erasing of the information even when the
heat is not directly applied to the disk substrate, and in a resin
with an inadequate heat-resistance, problems such as deformation of
the substrate or deformation of the disk itself take place.
[0015] Meanwhile, a heat treatment process is included in
production process of the optical disk in order to prevent change
in the substrate or recording medium with passage of time in many
cases, and from the standpoint of productivity, reduction in the
treatment time is desired by performing the treatment at as high a
temperature as possible. In this case, a high temperature treatment
is made impossible when the heat-resistance of the resin is
inadequate, and productivity cannot be increased.
[0016] Thus, it is not possible to use PMMA with a low
heat-resistance in order to withstand the high temperature used
during the course of production of the optical disk and application
of the disk, and study is focussed on PC having a higher
heat-resistance in the past. However, the heat-resistance of the PC
is not necessarily adequate, and a resin material having a higher
heat-resistance is highly demanded.
[0017] As a means to compensate problems in resins such as PC and
PMMA conventional used, a method where a transparent resin with a
high softening point mainly comprising carbon and hydrogen can be
mentioned, and use of hydrogenated vinyl aromatic hydrocarbon
polymer is being suggested by the present inventors in Japan Patent
Application No. 63-149845.
Problems to be Solved by the Invention
[0018] However, the above-mentioned hydrogenated vinyl aromatic
hydrocarbon polymer has a low adhesion typical of polyolefins, and
adhesion with the recording film is not adequate and adequate life
as a optical disk cannot be achieved.
Means to Solve the Problem
[0019] Based on the above background, and as a result of much
research conducted by the present inventors into improvements in
the resin to achieve strong adhesion with the above-mentioned
recording layer, it was found that an optical disk substrate having
excellent adhesion with the recording layer while maintaining the
high heat-resistance of the initial hydrogenated vinyl aromatic
hydrocarbon polymer can be achieved when a hydrogenated vinyl
aromatic hydrocarbon polymer composition made of a vinyl aromatic
hydrocarbon-conjugated diene block copolymer hydrogenated material
having a specific hydrogenation-ratio, or a mixture of a
hydrogenated vinyl aromatic hydrocarbon polymer and a vinyl
aromatic hydrocarbon-conjugated diene block copolymer hydrogenated
material having a specific hydrogenation ratio, or a saturated
hydrocarbon resin having a number average molecular weight of 5000
or below and having a softening point of 40.degree. C. or higher is
added to the above-mentioned materials, and the present invention
was accomplished.
[0020] In other words, the present invention is a hydrogenated
vinyl aromatic hydrocarbon polymer composition comprising two or
three components selected from among
[0021] (a) 1.about.100 wt % or less of a polymer produced by
hydrogenation of all the double bonds and an aromatic nuclei
included in vinyl aromatic hydrocarbon-conjugated diene block
copolymer,
[0022] (b) 0.about.95 wt % of a polymer produced by hydrogenation
of at least 80 mole % of the aromatic nuclei included in the vinyl
aromatic hydrocarbon, and/or
[0023] (c) 0.about.20 wt % of a saturated hydrocarbon resin with a
number average molecular weight of 500.about.5,000 and a softening
point of 40.degree. C. or higher (in this case, the sum of
component (b) and component (c) exceeds 0 wt %), and the
above-mentioned composition exhibits excellent adhesion with
metals, metal oxides, and polymer compounds having polar groups,
and can be used as an optical disk substrate having high adhesion
with the recording layer.
[0024] Component (a) of the composition of the present invention is
a vinyl aromatic hydrocarbon-conjugated diene block copolymer.
[0025] For the vinyl aromatic hydrocarbon monomer included in the
vinyl aromatic hydrocarbon segment of the raw material vinyl
aromatic hydrocarbon-conjugated diene block copolymer, styrene,
p-methylstyrene, .alpha.-methylstyrene, etc. can be mentioned, and
as a typical example, styrene can be mentioned.
[0026] For the vinyl aromatic hydrocarbon copolymer segment,
homopolymers made of one of the above-mentioned vinyl aromatic
hydrocarbons or copolymers made of two or more of these can be
mentioned. Furthermore, other monomers that are copolymerizable
with the above-mentioned vinyl aromatic hydrocarbons can be
included in an amount that does not cause an adverse effect on the
vinyl aromatic hydrocarbon polymer. For the above-mentioned
monomers, acrylic acid, acrylate, methacrylic acid, methacrylate,
maleic acid, maleic anhydride, acrolein, vinyl esters, vinyl
ethers, vinyl ketones, acrylonitrile, etc. can be mentioned.
[0027] Furthermore, for the conjugated dienes included in the
conjugated diene segment, 1,3-butadiene, isoprene,
2,3-dimethyl-1,3- butadiene, 1,3-pentadiene, 1,3-hexadiene, etc.
can be mentioned, and 1,3-butadiene and isoprene are widely used.
The above-mentioned block copolymer structure comprising at least
two different types of segments can be easily produced using a
standard method where a living anionic polymerization reaction is
carried out, for example, a method wherein an organic lithium
compound is used as a polymerization initiator, and a
polymerization reaction is carried out in a hydrocarbon solvent
such as hexane and heptane.
[0028] In this case, the amount of the vinyl aromatic hydrocarbon
polymer segment included in the above-mentioned block copolymer is
at least 20 wt %, preferably, at least 40 wt %, and especially at
least 60 wt %. Furthermore, the amount of the conjugated diene
polymer segment is 20 wt % or below for the total composition.
[0029] When the amount of the conjugated diene segment included in
the composition becomes too high, heat-resistance and rigidity of
the composition become inadequate and it cannot be used for optical
disk substrates.
[0030] The molecular weight of the above-mentioned vinyl aromatic
hydrocarbon-conjugated diene block copolymer raw material is in the
range of 30,000.about.400,000, preferably in the range of
50,0000.about.400,000 in terms-of the number average molecular
weight.
[0031] The vinyl aromatic hydrocarbon-conjugated diene block
copolymer of component (a) of the composition of the present
invention can be produced upon performing a hydrogenation reaction
for the above-mentioned block copolymer in the presence of a
hydrogenation catalyst capable of achieving an aromatic optical
disk substrate. For the hydrogenation catalyst used in this case,
for example, metals such as nickel, cobalt, ruthenium, rhodium,
platinum, and palladium, oxides, salts, complex thereof, and the
above-mentioned metals deposited onto a carrier such as activated
carbon, diatomaceous earth, and alumina, etc. can be mentioned.
Among those listed above, catalysts produced by depositing Raney
nickel, Raney cobalt, stabilized nickel, ruthenium, rhodium, or
platinum onto carbon or alumina are especially desirable from the
standpoint of reactivity.
[0032] It is desirable to perform the above-mentioned hydrogenation
reaction under a pressure of 50.about.250 kg/cm.sup.2, and
temperature of 100.about.200.degree. C. using a saturated
hydrocarbon type solvent such as cyclohexane, methyl cyclohexane,
n-octane, decalin, tetralin, and naphtha, or an ether type solvent
such as THF. As for the hydrogenation ratio, the hydrogenation
ratio of the double bonds based on the conjugated diene segment is
essentially 100%. The hydrogenation ratio of the aromatic nuclei is
98 mol % or less, preferably, 95 mol % or less, and especially 90
mol % or less. The lower limit of the hydrogenation ratio for the
aromatic nuclei is 75 mol %, and preferably, 80 mol %. When the
aromatic nuclei ratio is above the above-mentioned value, adhesion
with the recording film becomes poor, and when the value is too
low, problems such as reduction in the heat-resistance, increase in
the birefringence, and poor solubility with component (b), etc. can
be mentioned.
[0033] The molecular weight of the vinyl aromatic
hydrocarbon-conjugated diene block copolymer of component (a)
produced as described above is in the range of
20,000.about.300,000, preferably, 50,000.about.200,000, in terms of
the number average molecular weight. When the molecular weight is
too low, the rigidity becomes inadequate, and on the other hand,
when too high, molding properties and optical uniformity become
inadequate.
[0034] Component (b) of the composition of the present invention is
a hydrogenated vinyl aromatic hydrocarbon polymer.
[0035] For the raw material vinyl aromatic hydrocarbon polymer, the
same type of polymers used for the above-mentioned vinyl aromatic
hydrocarbon polymer segment included in the raw material component
(a) can be mentioned. As for the polymerization method used, it is
not especially limited as long as it is possible to produce a
non-crystalline polymer, and in general, radical polymerization
method, anionic polymerization method, etc. are used. It is
desirable for the molecular weight of the above-mentioned raw
material vinyl aromatic hydrocarbon polymer to be at least 50,000
in terms of the number average molecular weight. When the molecular
weight is too low, heat-resistance and rigidity of the resin
produced after the hydrogenation adduct treatment becomes poor.
[0036] Meanwhile, the upper limit of the molecular weight is not
especially limited and in general, 400,000 or below is
suitable.
[0037] A nuclei hydrogenation treatment is performed for the
above-mentioned vinyl aromatic hydrocarbon as in the case of the
hydrogenation of the above-mentioned component (a).
[0038] The degree of nuclei hydrogenation based on the nuclei
hydrogenation treatment is at least 80 mol %. When the degree of
hydrogenation is low, the heat-resistance becomes inadequate, and
the birefringence as an optical material becomes too high, which is
not desirable. The degree of the nuclei hydrogenation of the
above-mentioned component is at least 90 mol % and at least 95 mol
% is preferable.
[0039] The molecular weight of the hydrogenated vinyl aromatic
hydrocarbon polymer produced as described above is in the range of
50,000.about.30,000 [sic] in terms of the number average molecular
weight, and 60,000.about.250,000 is preferable. When the number
average molecular weight is below 50,000, the strength becomes
inadequate, which is not desirable, and on the other hand, when the
above-mentioned value exceeds 300,000, molding properties and
optical uniformity become poor, which is not desirable.
[0040] Component (c) of the present invention is a saturated
hydrocarbon resin with a number average molecular weight in the
range of 500.about.5000 and softening point of 40.degree. C. or
above. It is especially desirable when the number average molecular
weight is in the range of 500.about.2000, and softening point is in
the range of 60.about.200.degree. C.
[0041] Component (c) is a component contributes for an increase in
the adhesion.
[0042] When the molecular weight of the component (c) is too high,
the increase in adhesion is not adequate. On the other hand, when
the molecular weight of the component (c) is too low, problems such
as airborne dust at the time of molding and bleeding take place and
it cannot be used in practice. Furthermore, when the softening
point is too low, the heat-resistance of the composition is
reduced. The degree of hydrogenation of the resin of component (c)
is at least 95%, and at least 98% is preferable. For the
above-mentioned saturated hydrocarbon resin, resins such as
hydrogenated petroleum resins, hydrogenated dicyclopentadiene
resins, and polyvinyl cyclohexanes with a low molecular weight can
be mentioned. The amount of each component included in the
composition is in the range of 1.about.100 wt % or below for
component (a), and preferably in the range of 10.about.99 wt %; in
the range of 0.about.95 wt %, and preferably in the range of
0.about.90 wt %, for component (b); in the range of 0.about.20 wt
%, and preferably in the range of 0.about.10 wt %, for component
(c) (in this case, the sum of component (b) and component (c)
exceeds 0 wt %.)
[0043] Means used for mixing of the above-mentioned components is
not especially limited, and in general, a method wherein the
above-mentioned components are first dissolved in a solvent and
subsequently poured into a poor solvent, or removal of the solvent
is performed, or a method wherein hot-melt mixing is performed by
an extruder, Brabender blast-graph [phonetic] banbury mixer, or
other mixing devices, etc. can be used.
[0044] Furthermore, a method wherein solution mixing is first
performed followed by hot-melt mixing is also desirable.
[0045] In general, a heat stabilizer is mixed with the resin
produced as described above in the present invention and molding is
performed.
[0046] For examples of the above-mentioned heat stabilizers,
hindered phenol type heat stabilizers, sulfur type heat
stabilizers, phosphorus type heat stabilizers, etc. can be
mentioned. From the standpoint of an increase in the heat
degradation resistance, it is desirable when a hindered phenol type
heat stabilizer and a phosphorus type heat stabilizer are used in
combination.
[0047] For examples of the hindered phenol type heat stabilizers
used in the present invention,
tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphen- yl) propionate
methane, 3,9-bis[1,1-dimethyl-2-{.beta.-(3-t-butyl-4-hydrox-
y-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetrakis-pyrro[5,5]undecane,
1,3,5-tris(3,5-di-t-butyl-4- hydroxy
benzyl-s-triazine-2,4,6(1H,3H,5H)-tr- ion,
1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene,
etc. can be mentioned.
[0048] Furthermore, for examples of phosphorus type heat
stabilizers, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene
phosphonite,
bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol-di-phosphite,
etc. can be mentioned.
[0049] A suitable amount of the above-mentioned stabilizer to be
included is in the range of 0.01.about.1 part by weight in each
case.
[0050] As for the mixing method used for the above-mentioned
stabilizers and the resin composition of the present invention is
not especially limited, and in general, mixing is done for the
resin and stabilizers using a device such as ribbon blender,
tumbler mixer, Henshel mixer, hot-melt blending is further
performed by banbury mixer, uniaxial extruder, biaxial extruder to
produce a pellet. Subsequently, the pellet produced as described
above is used and injection molding is carried out at a molding
temperature in the range of 270.degree. C..about.330.degree. C.,
especially, in the range of 280.about.340.degree. C. to produce an
optical disk substrate having excellent transparency,
heat-resistance and very low degree of optical distortion with an
absence of coloring.
[0051] In the production of an optical disk with the optical disk
substrate made of the hydrogenated vinyl aromatic hydrocarbon
polymer composition of the present invention, a film made of
SN.sub.2.multidot.TaO.sub.x, etc. are formed on the surface of the
substrate using a method such as sputtering or deposition process,
and a recording layer such as TbFeCo is formed on the surface and a
protective layer is further deposited on the surface.
[0052] The optical disk substrate made of the polymer composition
of the present invention has excellent adhesion with the recording
layer, thus a sufficiently long life of the optical disk can be
achieved.
[0053] Furthermore, in addition to the above-mentioned optical
disk, the polymer composition of the present invention may be used
for moldings such as optical lenses and optical cards based on the
excellent heat-resistance and optical properties. The high adhesion
of the polymer composition of the present invention can be
effectively utilized in the above-mentioned cases as well.
APPLICATION EXAMPLES
[0054] In the following, the present invention is explained further
in specific terms with application examples and comparative
examples, but the present invention is not limited to these
examples as long as within the range of the invention. In this
case, measurement of properties used in the application examples,
comparative examples, and reference examples was done according to
the methods explained below.
[0055] (1) Number Average Molecular Weight
[0056] Measurement was done by gel permeation chromatography (GPC)
in THF as the solvent as in the case of polystyrene and the number
average molecular weight in terms of polystyrene was obtained.
[0057] (2) Nuclei Hydrogenation Ratio (%)
[0058] Dissolving was performed for aromatic nuclei included in the
vinyl aromatic hydrocarbon type resin in tetrahydrofuran (THF) and
measurement of UV absorption was performed.
[0059] (3) Softening Point (.degree. C.)
[0060] Measurement of the softening point temperature was performed
by a Thermo-mechanical analyzer produced by Dupont [sic] Corp.
using a penetration mode probe under a load of 5 g at a rate of
5.degree. C./min. The thickness of the sample piece was 3 mm.
Resin Manufacturing Example 1
[0061] Dissolving was performed for styrene homopolymer (product of
Mitsubishi Monsant Kasei Co., HH-102, number average molecular
weight of 100,000) in tetrahydrofuran, and 5% Pd/C was added as a
catalyst and a hydrogenation reaction was performed at a
temperature of 170.degree. C., hydrogen pressure of 100 kg/cm.sup.2
for 6 hours. As a result, a hydrogenated polystyrene with a number
average molecular weight of 68,000 and nuclei hydrogenation ratio
of 99.0% was produced.
Resin Manufacturing Example 2
[0062] A hydrogenation reaction was performed for a
styrene-butadiene block copolymer (number average molecular weight
of 100,000 and butadiene content of 20 wt %) produced by an anionic
polymerization method as in the case of Resin Manufacturing Example
1 so as to produce a hydrogenated styrene-butadiene block copolymer
with a number average molecular weight of 870,000 and hydrogenation
ratio of 87.5%.
Resin Manufacturing Example 3
[0063] A hydrogenation reaction was performed for a
styrene-butadiene block copolymer (number average molecular weight
of 105,000 and butadiene content of 5 wt %) produced by an anionic
polymerization method as in the case of Resin Manufacturing Example
1 so as to produce a hydrogenated styrene-butadiene block copolymer
with a number average molecular weight of 890,000 and hydrogenation
ratio of 93.5%.
Resin Manufacturing Example 4
[0064] A hydrogenation reaction was performed for a
styrene-butadiene block copolymer (number average molecular weight
of 120,000 and butadiene content of 40 wt %) produced by an anionic
polymerization method as in the case of the Resin Manufacturing
Example 2 so as to produce a hydrogenated styrene-butadiene block
copolymer with a number average molecular weight of 950,000 and
hydrogenation ratio of 85.5%.
Resin Manufacturing Example 5
[0065] A hydrogenation reaction was performed for a styrene-methyl
methacrylate block copolymer (styrene content of 85 wt %, and
number average molecular weight of 184,000) produced by a-radical
polymerization method as in the case of the Resin Manufacturing
Example 1. As a result, a hydrogenated polymer with a hydrogenation
ratio of 100% and a number average molecular weight of 144,000 was
produced. Hydrogenation of the ester group did not take place.
Resin Manufacturing Example 6
[0066] Dissolving was performed for styrene homopolymer (product of
Mitsubishi Monsant Kasei Co., HH-102, number average molecular
weight of 130,000) in tetrahydrofuran and 5% Pd/C was added as a
catalyst and a hydrogenation reaction was performed at a
temperature of 170.degree. C., hydrogen pressure of 60 kg/cm.sup.2
for 6 hrs. As a result, a hydrogenated polystyrene with a number
average molecular weight of 75,000 and nuclei hydrogenation ratio
of 80.2% was produced.
Application Example 1
[0067] Dissolving was performed for 3.75 kg of polymer produced in
Resin Manufacturing Example 1, 1.25 kg of polymer produced in Resin
Manufacturing Example 2, and 250 g of hydrogenated petroleum resin
(product of Arakawa Chemical Co., Arukon [transliteration] P-100)
in tetrahydrofuran and coprecipitation was further performed in
methanol. For the wet powder produced above, 0.05 parts by weight
each of 1,3,5-trimethyl-2,4,6-tris-(3,5-di-t-butyl-4- hydroxy
benzyl) benzene (product of Japan Ciba Geigy Co. "Irganox 1330")
and pentaerythritol diphosphite (product of Adeka-Argus
[transliteration] Co. "MARKPEP-36") was added as add;s, and drying
was further performed. Hot-melt kneading was performed by an
extruder at 260.degree. C. and pelletization was performed.
[0068] A stamper having a groove was attached to the mobile die
side of an injection molding machine (product of Meiki Co. "M140A")
and molding of the above-mentioned pellet was performed at a resin
temperature of 300.degree. C. so as to produce a disk substrate
having a thickness of 1.2 mm and a diameter of 130 mm.
[0069] The softening temperature of the resin used for the
substrate was 163.degree. C. and the bent modulus was 28,000
kg/cm.sup.2.
[0070] The substrate produced was set for the sputtering device and
exhaust was performed to achieve 8.times.10.sup.-7 torr or below,
and a reactive sputtering was performed for the Ta target with a
mixed gas comprising Ar and O.sub.2 so as to produce an
interference layer made of Ta.sub.2O.sub.6 (thickness of 800 A).
Subsequently, two-dimensional sputtering was performed with a Tb
target and FeCo target with Ar gas so as to produce a recording
layer made of TbFeCo (thickness 300 A). Furthermore, sputtering was
performed with an Al target and a Ti chip in an Ar gas so as to
produce a reflective film. 10 lines were drawn in an area measuring
1 cm.times.1 cm on the mirror surface of the above-mentioned film
and an adhesive tape (imide film base) produced by Teraoka Co. was
applied to the checker-board area design and the adhesion of the
base with the tantalum oxide film was evaluated by peeling the
above-mentioned film.
[0071] Not one square among 100 squares was removed as a
result.
Application Example 2
[0072] 150 g of polyvinyl cyclohexane with a low molecular weight
(product of Arakawa Chemical Co., Arukon [phonetic] P-125,
softening point of 125.degree. C. and molecular weight of 820) was
added to 5 kg of the hydrogenated polymer produced in Resin
Manufacturing Example 3 and pelletization, injection molding and
sputtering were performed with the above-mentioned additives as in
the case of Application Example 1. The softening temperature of the
substrate resin was 168.degree. C. and the modulus was 29,000
kg/cm.sup.2. When the peel test was performed with a tape as in
Application Example 1, not one square among 100 squares was removed
as result.
Application Example 3
[0073] Pelletization, injection molding, and sputtering were
performed for 2.5 kg of the hydrogenated polymer produced in Resin
Manufacturing Example 1 and 2.5 kg of the hydrogenated polymer
produced in Resin Manufacturing Example 2 as in the case of
Application Example 2. The softening temperature of the substrate
resin was 158.degree. C. and the modulus was 23,000 kg/cm.sup.2.
When the peel test was performed with a tape as in the application
example above, not one square among 100 squares was removed as
result.
Application Example 4
[0074] In Application Example 1, instead of the polymer produced in
Resin Manufacturing Example 1, the polymer produced in Resin
Manufacturing Example 5 was used and sputtering was further
performed for the optical disk substrate produced above.
[0075] The softening temperature of the substrate resin was
161.degree. C. and the modulus was 28,000 kg/cm.sup.2. When the
peeling test was performed with a tape as in the case of the
above-mentioned application example, not one square among 100
squares was removed as result.
Application Example 5
[0076] 4.25 kg of the polymer produced in Resin Manufacturing
Example 1, 0.75 kg of polymer produced in Resin Manufacturing
Example 4 and 250 g of Arukon [phonetic] P-100 used in Application
Example 1 were used and sputtering was further performed for the
optical disk substrate produced above.
[0077] The softening temperature of the substrate resin was
160.degree. C. and the modulus was 27,000 kg/cm.sup.2. When the
peel test was performed with a tape as in the above-mentioned
application example, not one square among 100 squares was removed
as result.
Comparative Example 1
[0078] The additives described in Application Example 1 were added
to 5.0 kg of the polymer produced in Resin Manufacturing Example 1
and pelletization, injection molding, and sputtering were performed
in the same manner. The softening temperature of the substrate
resin was 172.degree. C. and the modulus was 32,000 kg/cm.sup.2.
When the peeling test was performed with a tape as in the
above-mentioned application example, all 100 squares among 100
squares were removed as result.
Comparative Example 2
[0079] In Application Example 1, instead of the hydrogenated
polymer produced in Resin Manufacturing Example 2, a hydrogenated
polymer with the hydrogenation ratio of 99.5% used in Resin
Manufacturing Example 2 was used, and pelletization, injection
molding, and sputtering were performed as in Application Example
1.
[0080] The softening temperature of the substrate resin was
163.degree. C. and the modulus was 28,000 kg/cm.sup.2. When the
peel test was performed as described above, 98 squares among 100
squares were removed as a result.
Comparative Example 3
[0081] Additives described in Application Example 1 were added to
5.0 kg of the polymer produced in Resin Manufacturing Example 6,
and pelletization, injection molding and sputtering were performed
as described above. The softening temperature of the substrate
resin was 150.degree. C. and the modulus was 32,000
kg/cm.sup.2.
[0082] When the peel test was performed as described above, 5
squares among 100 squares were removed as result, and the
heat-resistance was significantly reduced and adhesion remained
poor.
[0083] The results obtained in the above-mentioned application
examples and comparative examples are summarized in Table I
below.
1TABLE I Application Softening Modulus No. of squares removed
Example No. point (.degree. C.) (kg/cm.sup.2) among 100 (squares) 1
163 28,000 0 2 168 29,000 0 3 158 23,000 0 4 161 28,000 0 5 160
27,000 0 Comparison-1 172 32,000 100 Comparison-2 163 28,000 98
Comparison-3 150 32,000 5
Effect of the Invention
[0084] The composition of the present invention has excellent
heat-resistance, optical properties, and adhesion with the
recording layer and the composition can be used effectively for
optical disk substrates as well as other optical products.
* * * * *