JPH03162730A - Information recording medium - Google Patents

Abstract

PURPOSE:To prevent slippage between disk substrates and to reduce deformation such as warpage by sticking two disk substrates having recording layers with a specified adhesive. CONSTITUTION:The information recording medium 1 has such a structure with a center hole 6 that two disk substrates 2a, 2b are stuck with ring spacers 4a, 4b interposed with an adhesive 5 in a manner that the recording layers 3a, 3b face to each other. The adhesive used for sticking two disk substates 2a, 2b and ring spacers 4a, 4b is hot-melt type, having >=40,000 cps melt viscosity at 170 deg.C. By this method, the obtd. medium shows little deformation such as warpage since no slippage between the two disk substrates 2a, 2b is cuased even when the medium is used for a long time under conditions of high temp. and high humidity.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an information recording medium used as an optical disk or the like, particularly an optical information storage medium in which two disk substrates are bonded together with an adhesive via a ring-shaped spacer. It is related to recording media. [Prior art] Two disk substrates are pasted via a ring-shaped substrate to a plastic information recording medium that writes and reads information by focusing light such as a laser beam onto a recording layer. There is a disc with a so-called air sand inch structure. Adhesives used for such air sand inch discs include UV-curable adhesives, double-sided tape,
There are room temperature curing adhesives and hot melt adhesives. In general, UV-curable adhesives and double-sided tapes have the disadvantages of large deformations such as warpage, cracks and pitting in their appearance, and low adhesive strength. There is also the problem of air getting inside. On the other hand, room-temperature curing adhesives have a good appearance and high adhesive strength, but have the disadvantage of being susceptible to warping and other deformation. On the other hand, hot-melt adhesives that are applied by nozzle discharge, etc. have a good appearance, have high adhesive strength, and are less likely to warp or otherwise deform than the aforementioned adhesives, so they are attracting attention as adhesives with potential for future development. There is. However, under high temperature and high humidity conditions (e.g. temperature 80°C, humidity 85%) for a long time (e.g. 300°C)
In tests that last for several hours, there is a problem in that misalignment occurs between the two disk substrates bonded together, which increases deformation such as warping. [Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problems, and to solve the problem that misalignment occurs between two bonded disk substrates even if they are khmed for a long time under high temperature and high humidity conditions. The purpose of the present invention is to provide an information recording medium that is free from warping and has minimal deformation such as warpage. [Means for Solving the Problems] The present invention provides an information recording system in which two disk substrates each having a recording layer formed on one side of at least one transparent IIM resin substrate are bonded together with an adhesive via a ring-shaped spacer. In the medium, the melt viscosity of the adhesive is 40,000 at 170°C.
The information recording medium is characterized in that it is a hot melt adhesive with a cPs or higher. In the present invention, the disk substrate has a structure in which a recording layer is formed on one side of at least one transparent resin substrate, and the two disk substrates are pasted with an adhesive through a ring-shaped spacer with the recording layer inside. combined,
An information recording medium is formed. The material of the transparent resin substrate for forming the disk substrate is polycarbonate,
Thermoplastic resins such as polymethyl methacrylate and polyolefin can be used. A preferred resin is a cyclic olefin random copolymer (a
), a ring-opening polymer of a cyclic olefin component represented by the following general formula [1] or its hydrogenated product (b). (
In the formula, R1 to R12 are hydrogen atoms, hydrocarbon groups, or halogen atoms, and may be the same or different. Further, R' and Rll, or R1'' and Rl2 may be combined to form a divalent hydrocarbon group, and R9 or R10 and R1'' or R12 may mutually form a ring. n is 0 or a positive integer, and RS,
,, When Ra is repeated multiple times, they may be the same or different. ) The cyclic olefin that is a component of the cyclic olefin random copolymer (a) constituting the material of the transparent resin substrate used in the present invention is a group consisting of unsaturated monomers represented by the general formula [1] above. At least one cyclic olefin selected from. In the cyclic olefin random copolymer (a), the cyclic olefin represented by the general formula [1] above mainly forms repeating units having a structure represented by the following general formula (1-a). (In the formula, n and R1 to R18 are the general formula [1]
is the same as ) R1 to RL2 in the general formula (1) are hydrogen atoms,
An atom or group selected from the group consisting of halogen atoms and hydrocarbon groups. Examples of RL to R1 in the general formula [1] include hydrogen atoms; halogen atoms such as fluorine, chlorine, and bromine; and lower alkyl groups such as methyl, ethyl, proyl, and butyl groups. , these may be different from each other, may be partially different, or may be entirely the same. As R9 to H1ffi in the general formula (1),
For example, a hydrogen atom; a halogen atom such as fluorine, chlorine, or bromine; a methyl group, an ethyl group, a probyl group, an isoprobyl group,
Alkyl groups such as butyl group, isobutyl group, hexyl group, stearyl group; cycloalkyl groups such as cyclohexyl group; Substituted or unsubstituted phenyl group, tolyl group, ethylphenyl group, isopropylphenyl group, naphthyl group, anthryl group, etc. Aromatic hydrocarbon groups include benzyl groups, phenethyl groups, and other aralkyl groups in which an alkyl group is substituted with an aryl group, and these may be different or all may be the same. Also R
'' and R1'', or R11 and RLZ are integrated into 2
R9 or Pll and R11 or H1m may form a ring with each other. Examples of the divalent hydrocarbon group formed by combining R9 and Rill or R11- and R12 include alkylidene groups such as ethylidene groups, propylidene groups, and isopropylidene groups. R9 or Hl
The ring formed by a and Rl1 or H12 may be monocyclic or polycyclic, may be a polycyclic ring having a bridge, or may be a ring having a double bond. It may also be a ring consisting of a combination of rings. Examples of such rings include, for example. These rings may have a substituent such as a methyl group. In addition, in the above chemical formula, the carbon atom with 1 or 2 represents the carbon atom to which R@~R12 is bonded in the above general formula [1]. In the general formula [1], R9 or Hill and H1
Specific examples of the olefin in which a ring is formed from m or Ri2 include the following general formula [2] (where p, q
, r and S are O or 1, and t is O or a positive integer. ) Cyclic olefins can be mentioned. An ethylene/cyclic olefin random copolymer having repeating units derived from this cyclic olefin and a method for producing the same are as follows:
For example, it is disclosed in International Publication No. 10 89/01950. In the above ethylene/cyclic olefin random copolymer, the cyclic olefin copolymerized with ethylene and represented by the general formula [2] is mainly represented by the following general formula (2-a) (where p, q. r.s and t are the same as the above general formula [2]. 8 and t are the same as in the above general formula [2].) The repeating unit of the structure resulting from ring-opening polymerization represented by the formula [2] is substantially absent, or even if it is present, it is only in a very small amount. It is. Therefore, ethylene/cyclic olefin random copolymers are chemically stable. A typical example of the cyclic olefin represented by the general formula [2] is 1 represented by the following general formula [3] (wherein p.q and S are the same as in the general formula [2]). ,4,5.8-dimethano-1.2,3,
Examples include 4,4a, 4b, 5,8, 8a, 9a-decahydrofluorenes. In the ethylene/cyclic olefin random copolymer, the repeating unit derived from this cyclic olefin is mainly represented by the following general formula (3-a). During the ceremony. p. q and S are the same as in the general formula [2] above. ), and the structure resulting from ring-opening polymerization is virtually absent, or even if it is present, it is only in a very small amount. The cyclic olefin represented by the general formula [1] can be easily produced by condensing a cyclopentadiene and a corresponding olefin or cyclic olefin by a Diels-Alder reaction. Examples of the cyclic olefin represented by the general formula [1] include bicyclo(2.2.1)hept-2-ene or its derivatives, tetracyclo(4.4.0.1'''1
"")-3-dodecene or its derivatives, hexagonal (6.6.1.13".1"・L!.gj,?.0"・
14)-4-heptadecene or its derivative, octase [8.8. on1"'*1"'*1"""sl""
” so co + @ , ■L m h 1 ? ) −
5-docosene or its derivatives, pentacyclo(6
．． 6. l. P・6.02・'. 0"")-4-hexadecene or its derivatives, pen'i shi') o (6.
5.1.1'I'. 0"・'.0' l13)
-4-pentadecene or its derivative, heptacyclo [
8.7.0. p-. 1411. IL1117.0! ,@
．． (pl,11)-5-eicosene or a derivative thereof,
Heptacyclo(8.8.0.1”'141?.IL11
1m. 0311.01!・14)-s-heneicosene or its derivative, tricyclo(4.3.0.1”・6
]-3-decene or its derivatives, tricyclo(4.4
．． 0.1"')-3-undecene or its derivatives, pentacyclo(6.5.1.1".0"l'.0
' ””) - 4. 10-pentadecadiene or its derivative, pentacyclo(6.5.1.1”'O!,
? ．． gS+13)-4.11-pentadecadiene or its derivative, /<:/tashik o(4.7.0.1!Is
．． 0"". 111”]-3-pentadecene or its derivative, pentacyclo(4.7.0.1” ”.0@I1
".1'"") - 3.10-bentadecadiene or its derivative, heptacyclo (7.8.0.121!
．． Ojl'F. 1111.17,011,1G. 1 work 2
,1!3-4-eicosene or its derivative, nonacyclo(9.10.1.1'-'03#●92 * za
．． 01m ** 1. 113mlm. 014
1 as. Examples include 11g 1 as )-5-hentacocene and its derivatives. Further, examples of the cyclic olefin represented by the general formula [1] include compounds represented by the following general formula [4]. (In the formula, p is O or an integer of 1 or more, q and r are O,
1 or 2, R1 to R4, and Rill to RL2 are the same as those in the general formula [1], and R13 to B21 each independently represent a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and an alkoxy Indicates an atom or group selected from the group consisting of Hill to RLR and R1
3 to R21 may be bonded directly or via an alkylene group having 1 to 3 carbon atoms to form a ring. ) Specific examples of R0 to Hfil in the general formula [4] include, for example, a hydrogen atom; a halogen atom such as fluorine, chlorine, or bromine; a methyl group, an ethyl group, a proyl group, an isoprobyl group, a butyl group, an isobutyl group; aliphatic hydrocarbon groups such as hexyl and stearyl groups; cycloalkyl groups such as cyclohexyl; substituted or unsubstituted phenyl, tolyl, ethylphenyl, isopropylphenyl, naphthyl, and anthryl groups; Aromatic hydrocarbon groups; aralkyl groups such as benzyl groups and phenethyl groups; alkoxy groups such as methoxy groups, ethoxy groups, and propoxy groups; these may be different or partially different. They may all be the same. In the compound represented by the general formula [4], p is O
~3 is preferred. Specific examples of the compound represented by the general formula [1] include those listed in Table 1. Table 1 Table 1 (Continued 1) Table 1 (Continued 2) Table 1 (Continued 3) Table 1 (Continued 4) Table 1 (Continued 5) Table 1 (Continued 6) Table 1 (Continued 7) Table 1 ( Continued 8) Table 1 (Continued 9) Table 1 (Continued 10) Table 1 (Continued 11) Table 1 (Continued 12) Table 1 (Continued 13) Table 1 (Continued 14) Table 1 (Continued 15) Table 1 (Continued 16) The cyclic olefin-based random copolymer (a) has the above-mentioned cyclic olefin component and ethylene component as essential components, but in addition to these two essential components, there are no substances that impair the purpose of the present invention. If necessary, other copolymerizable unsaturated monomer components may be contained within the range. Examples of unsaturated monomers that may optionally be copolymerized include those having 3 carbon atoms,
-20 α-olefins, hydrocarbon monomers containing two or more carbon-carbon double bonds per molecule, etc. As an α-olefin having 3 to 20 carbon atoms,
Specifically, propylene, 1-butene, 1-pentene, 4
-methyl-1-pentene, 3-methyl-1-pentene,
l-hexene, 1-heptene, 1-octene, ■-nonene, l-decene, ■-dodecene, ■-tetradecene, l
Examples include -hexadecene, 1-octadecene, and l-eicosene. Examples of hydrocarbon monomers containing two or more carbon-carbon double bonds in one molecule include 1,4-hexadiene, 1,6-octadiene, 2
-Methyl-1,5-hexadiene, 4-methyl-1.5
-hexadiene, 5-methyl-1,5-hexadiene,
6-methyl-1,5-hebutadiene, 7-methyl-1.
Chained non-conjugated dienes such as 6-octadiene: cyclohexadiene, dicyclopentadiene, methyltetrahydride indene, 5-vinyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5- Isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene,
4,9,5,8-dimethano-3a,4,4a,5,8,
Cyclic non-conjugated dienes such as 8a,9.9a-octahydride-IH-penzoindene; 2,3-diisobutyridene-
Examples include 5-norbornene: 2-ethylidene-3-isopropylidene-5-norbornene; 2-propenyl-2,2-norbornadiene. Among these, 1,4-hexadiene, 1,6-octadiene, and cyclic nonconjugated dienes, especially dicyclopentadiene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, 5-methylene-2- Norbornene, 1,4-hexadiene, and 1,6-octadiene are preferred. In the cyclic olefin random copolymer (a), the structural units derived from the ethylene component range from 40 to 85 mol%, preferably from 50 to 75 mol%, and the structural units derived from the cyclic olefin component range from 15 to 60 mol%. , preferably 2
A suitable range is 5 to 50 mol%, and the structural units derived from the ethylene component and the structural units derived from the cyclic olefin component form a substantially linear cyclic olefin random copolymer in which they are randomly arranged. ．． The fact that the cyclic olefin random copolymer (a) is substantially linear and does not have a gel-like crosslinked structure means that this copolymer has 1
This can be confirmed by complete dissolution in decalin at 35°C. The intrinsic viscosity [η] of the cyclic olefin random copolymer (a) measured in decalin at 135°C is 0.01~]O
dR/g, preferably in the range of 0.05 to 5 dn/g. Furthermore, a cyclic olefin random copolymer (a
), the softening temperature (TMA) measured with a thermal mechanical analyzer is 70°C or higher, preferably 9
0 to 250°C, more preferably 100 to 200°C,
The glass transition temperature (Tg) is usually 50 to 230°C, preferably 70 to 210°C, and the degree of crystallinity measured by X-ray diffraction is 0 to 10%, preferably 0 to 7%, particularly preferably 0 to 5%. Preferably, the range is . As the cyclic olefin random copolymer (a), one type of copolymer having physical properties within the above range may be used;
The intrinsic viscosity [η] measured in decalin is 0.05 to 1.
To 100 parts by weight of a cyclic olefin random copolymer having a softening temperature (TMA) of 0 dll/g and a softening temperature (TMA) of 70°C or higher, preferably 90 to 250°C, the intrinsic viscosity measured in decalin at 135°C [ η] is 0. Ol~5d
l/g range and has a softening temperature (TMA) of 70°C
It is also possible to use a composition blended with 0.1 to 10 parts by weight of a cyclic olefin random copolymer having a temperature of less than -10 to 60°C.

The cyclic olefin random copolymer (a) comprises an ethylene component, a cyclic olefin component represented by the above general formula [1], and other monomer components to be copolymerized if necessary.
It can be produced by polymerization in the presence of a well-known Ziegler series catalyst. Examples of the Ziegler-based catalysts include (a) a catalyst consisting of a composite containing at least magnesium, titanium, and a halogen and an organoaluminum compound, and (b) a catalyst consisting of a vanadium compound and an organoaluminum compound. can.
Among these, the latter catalyst (a) is preferred, and a catalyst comprising a soluble vanadium compound and an organoaluminum compound is particularly preferred. Specific methods for producing the cyclic olefin random copolymer (a) are described in JP-A-60-168708, JP-A-61-120816, and JP-A-61-11591.
Publication No. 2, JP-A-61-115916, JP-A-6
1-271308, JP-A-61-272216, JP-A-62-252406, JP-A-62-
This is disclosed in Publication No. 252407, etc. In addition to the cyclic olefin random copolymer (a), preferred resins for the transparent resin substrate used to form the disk substrate include cyclic olefins represented by the general formula [1]. A ring-opening polymer comprising one or more cyclic olefin components or a hydrogenated product (b) thereof (hereinafter referred to as a cyclic olefin-based ring-opening polymer) can also be used. Such a cyclic olefin ring-opening polymer is
For example, it is disclosed in Japanese Patent Application Laid-Open No. 60-26024. The cyclic olefin constituting the cyclic olefin-based ring-opening polymer (b) is at least one cyclic olefin selected from the group consisting of unsaturated monomers represented by the above general formula [1]. In the ring-opening polymer before hydrogenation of the hydrogenated cyclic olefin-based ring-opening polymer, the cyclic olefin content represented by the above general formula [1] is expressed by the following general formula (1-b).
It mainly forms repeating units with the structure represented by the following general formula (1) in the ring-opened polymer after hydrogenation.
-c) It mainly takes the form of repeating units of the structure. (In the formula, n and R1 to R12 are the same as in the above general formula [1].) The cyclic olefin-based ring-opening polymer (b) has the above-mentioned cyclic olefin as an essential component, but the present invention If necessary, other copolymerizable unsaturated monomer components may be contained within the range that does not impair the purpose. Examples of unsaturated monomers that may optionally be copolymerized include the following general formula [
Examples include cyclic olefins represented by [5]. (In the formula, R2M and H23 are hydrogen atoms, hydrocarbon groups, or halogen atoms, and may be the same or different, respectively. Q is an integer of 2 or more, and R22R2
) is repeated multiple times, they may be the same or different. ) Examples of the monomer component represented by the general formula [5] include cyclobutene, cyclobentene, cycloheptene, cyclooctene, cyclononene, cyclodecene, methylcyclopentene, methylcycloheptene, methylcyclooctene, methylcyclononene, methylcyclodecene, ethylcyclobentene,
Examples include ethylcycloheptene, ethylcyclooctene, ethylcyclononene, ethylcyclodecene, dimethylcyclopentene, dimethylcycloheptene, dimethylcyclooctene, and trimethylcyclodecene. Furthermore, examples of monomer components other than the cyclic olefin represented by the general formula [5] include cyclooctadiene and cyclodecadiene.

The intrinsic viscosity [η] of the cyclic olefin ring-opening polymer (b) measured in decalin at 135°C is 0.01 to 10 dl/
g. Preferably it is 0.05 to 5 dl/g. Furthermore, the cyclic olefin ring-opening polymer (b) has a softening temperature (TMA) of 70°C or higher, preferably 90 to 200°C.
, crystallinity measured by X-ray diffraction method is 0~10%
, preferably 0 to 7%, particularly preferably 0 to 5%. As the cyclic olefin ring-opening polymer (b), a polymer consisting only of those having physical properties within the above range may be used, but a polymer having physical properties outside the above range may be partially included. In this case, it is sufficient that the entire physical property value is within the above range. In order to produce the ring-opening polymer of the cyclic olefin component represented by the general formula (1), the general formula [1]
] can be ring-opening polymerized using a heptanomer component selected from ] as a raw material by a conventional ring-opening polymerization method for cyclic olefins. In this case, the polymerization catalyst includes, for example, halides such as ruthenium, rhodium, palladium, osmium, iridium, platinum, molybdenum, tungsten, nitrates or acetylacetone compounds, and organic tin compounds,
A system consisting of a reducing agent such as alcohol. Alternatively, a system consisting of a halide such as titanium, vanadium, zirconium, tungsten, or molybdenum or an acetylacetone compound and an organic aluminum or the like can be used. The molecular weight of the resulting ring-opening polymer can be adjusted by adding an olefin or the like during ring-opening polymerization. When hydrogenating the ring-opened polymer obtained above, a conventional hydrogenation method can be used. As the hydrogenation catalyst, those used in the hydrogenation of olefin compounds can generally be used. Specifically, heterogeneous catalysts include nickel, palladium, platinum, etc., or solid catalysts in which these metals are supported on supports such as carbon, silica, diatomaceous earth, alumina, titanium oxide, etc. For example, nickel/silica , nickel/diatomaceous earth, palladium/carbon, palladium/silica, palladium/diatomaceous earth, palladium/alumina, etc. Homogeneous catalysts include those based on metals from group Ⅰ of the periodic table, such as nickel naphthenate/triethylaluminum, cobalt octate/n-butyllithium, nickel acetylacetonate/triethylaluminum, etc. ．． Examples include those consisting of a Co compound and an organometallic compound of metals from groups ① to ② of the periodic table, or Rh compounds.

The hydrogenation of the ring-opening polymer is carried out in a homogeneous or heterogeneous system depending on the type of catalyst, under a hydrogen pressure of 1 to 150 atmospheres, at a temperature in the range of 0 to 180 °C, preferably 20 to 100 °C. ．． The hydrogenation rate can be adjusted by hydrogen pressure, reaction temperature, reaction time, catalyst concentration, etc.

These resins can be used alone or in a blend of two or more. In order to form a transparent resin substrate from the resin that is the material of the transparent resin substrate, a general method such as injection molding can be used, and a transparent resin substrate of a desired shape can be obtained.

In the present invention, as the material of the ring-shaped spacer interposed between the transparent resin substrates, thermoplastic resins such as polycarbonate, polymethyl methacrylate, polyolefin, etc. can be used, similar to the material of the transparent resin substrates. The resin forming this spacer includes Tie2, Sin
, etc. may be added. Further, the recording layer for forming the disk substrate is made of a low melting point metal material such as Te, or Te-C-H. Te-Cr
, a recording material mainly composed of a low melting point metal material such as a Te-Cr-C-H film, or a heat mode recording material suitable for the information recording medium of the present invention, such as an organic dye material, or a Tb
-Fe-co. A magneto-optical recording material containing a rare earth element such as Tb-Fe-co with pt or Pd added and a 3D transition metal, and an underlayer laminated on and/or below these recording material layers as necessary. , an antireflection layer, a reflective layer, an interference layer, a protective layer, an enhancement layer, etc. are used. The adhesive used in the information recording medium of the present invention has a melt viscosity (measured using an Emiller viscometer at a shear rate of 17.6 sec-1) of 400 at 170°C.
It is a hot melt adhesive with a strength of 00 cPs or more, and is coated in a molten state at a high temperature and hardens by cooling. As the material for such a hot melt adhesive, a polyolefin hot melt adhesive containing a polyα-olefin (A), a styrene polymer (B) and a tackifier (C) is preferable. The poly-α-olefin (A) constituting such a polyolefin-based hot melt adhesive is an α-olefin having 2 to 20 carbon atoms.
Olefin homopolymers or copolymers can be used. Examples of such poly-α-olefin (A) include ethylene-propylene copolymer (A-1). Polypropylene (A-2) and polyisobutylene (A-3) are preferred, especially (A-1), (A-2) and (A-3).
) is preferred. (A-1) to ( in the mixture
The mixing ratio of A-3) is 1 to 98 parts by weight, preferably 5 to 90 parts by weight of (A-1) to the mixture of (A-1), (A-2) and (A-3). , (A-2) is 1 to 98
parts by weight, preferably 5 to 90 parts by weight, (A-3) is 1
~49 parts by weight, preferably 5 to 45 parts by weight.
The ethylene content in the ethylene-propylene copolymer (A-1) is preferably in the range of 5 to 80% by weight, particularly 5 to 50% by weight. Moreover, the melt flow rate value (ASTM) of this ethylene-propylene copolymer (A-1)
D1238) is preferably 0.1=lOOg/10 minutes, more preferably 0.5 to 50 g/10 minutes. Further, the preferable intrinsic viscosity [η] (measured in decalin at 135°C) of the ethylene-propylene copolymer (A-1) is 0.1 to 6.
Odl/g, and a more preferable intrinsic viscosity [η] is 0.
2 to 4.5d (1/g. This ethylene-propylene copolymer (A-1) may be partially modified with an unsaturated carboxylic acid or a derivative thereof. The modification method is copolymerization. Modification or graft modification may be used.As unsaturated carboxylic acids or derivatives thereof,
For example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acid
, 3-dicarboxylic acid); maleyl chloride, maleimide, itaconic anhydride, maleic anhydride,
Examples include acid halides, amides, imides, anhydrides, and esters such as citraconic anhydride, monomethyl maleate, dimethyl maleate, and glycidyl maleate. Among these, unsaturated dicarboxylic acids or their acid anhydrides are preferred, with maleic acid or maleic anhydride being particularly preferred. The amount of modification is preferably 0.1 to 5% by weight of the unsaturated carboxylic acid or its derivative component in the copolymer. As polypropylene (A-2), any polypropylene containing propylene as a main component, such as a propylene homopolymer or a copolymer of propylene with other comonomers such as ethylene or α-olefin having 4 to 20 carbon atoms, can be used. Among them, random type polypropylene is preferred, and ethylene-propylene random copolymers containing less than 20% by weight of ethylene or an α-olefin component as a comonomer are particularly preferred. Polyisobutylene (A-3) has a number average molecular weight of sooo
oo or less, particularly preferably 2,000 to 300,000. The styrenic polymer (B) is a polymer containing at least styrene or its derivative as one component of the structural unit, and specifically includes polystyrene, styrene-butadiene rubber (SBR), and styrene-butadiene-styrene block copolymer. polymer (S B S block copolymer) and SEBS copolymer which is a hydrogenated product of SBS block copolymer or SBR, styrene/acrylonitrile copolymer, styrene/α-methylstyrene copolymer,
Styrene/maleic anhydride copolymer, styrene/methyl methacrylate copolymer, styrene/N-phenylmaleimide copolymer, styrene/α-methylstyrene/acrylonitrile terpolymer, styrene/acrylonitrile/methacrylic acid Methyl terpolymer, styrene/maleic anhydride/acrylonitrile terpolymer. In addition to styrene/maleic anhydride/N-phenylmaleimide terpolymer, so-called ABS resin is a blend of the above resins with polybutadiene, ethylene/propylene copolymer rubber, acrylic rubber, etc. as rubber components. AES resin, A
An example is AS resin. Such a styrenic polymer (B) has a glass transition temperature (Tg) of 50 to 200°C, preferably 70 to 200°C.
Melt flow rate (ASTM 01238) at 150℃, 200℃ and 2.16kg load is 0.05 to 1
00 g/10 minutes, preferably 0.1 to 50 g/10 minutes. Examples of the tackifier (C) used in the present invention include rosin and its derivatives, terbene-containing resin (terpene resin), aromatic petroleum resin, cyclopentadiene resin, dicyclopentadiene resin, and carbon in the polymer structure. Examples include aliphatic cyclized resins such as aliphatic hydrocarbon resins having rings. This tackifier (
C) is different from component (A) or (B).

Preferred examples of rosin derivatives include hydrides and esters of rosin. Preferred examples of the cyclopentadiene resin include cyclopentadiene homopolymers and copolymers containing cyclopentadiene as a main component. Preferred examples of dicyclopentadiene-based resins include dicyclopentadiene homopolymers and copolymers containing dicyclopentadiene as a main component. Preferred examples of aliphatic hydrocarbon resins having carbon rings in the polymer structure include cyclopentadiene and/or dicyclopentadiene and carbon atoms having 4 and/or 5 carbon atoms.
olefins or diolefins, or aliphatic olefins having 5 carbon atoms obtained by decomposition of petroleum (e.g. 2-methyl-1-butene and/or 2-methyl-2-butene). ) and/or a fraction containing aliphatic diolefins having 5 carbon atoms (e.g. isobrene and/or piperylene) (CS fraction), obtained by polymerizing in the presence of a cationic catalyst such as a Friedel-Crafts catalyst, So-called aliphatic petroleum resin, or C4
or C. Examples include petroleum resins obtained by polymerizing ~C and fractions in the presence of cationic catalysts. Among these, as the tackifier (C) in the present invention, aliphatic cyclized resins are most preferable, and among the aliphatic cyclized resins, aliphatic hydrocarbon resins having a carbon ring in the polymer structure, Particularly preferred are aliphatic petroleum resins.

The aliphatic cyclized resin preferably has a number average molecular weight of 5000 or less, more preferably 50 to 3000, particularly preferably 300 to 3000, and preferably 30-120°C, more preferably 70°C. It has a softening point (ring and ball method) of ~120°C.

The aliphatic stone-derived resin, which is a particularly preferred aliphatic cyclized resin, preferably has a number average molecular weight of 300 to 2,000, and preferably 30 to 120°C, particularly preferably 70°C.
It has a softening point (ring and ball method) of ~100°C.

Furthermore, in the present invention, not only the component (A-1) but also the component (A-2
), (A-3). Component (B) or (C) may also be modified with the unsaturated carboxylic acid or its derivative, if necessary.

The polyolefin-based hot melt adhesive may contain other components, such as less than 1% by weight of filler, in addition to the components (A) to (C) above.

The blending amount of each component constituting the polyolefin hot melt adhesive is such that component (A) is 4 to 69% by weight, preferably 5 to 60% by weight, and component (B) is 1 to 30% by weight. , preferably from 5 to 20% by weight, and (C) is from 30 to 95% by weight, preferably from 35 to 80% by weight. The melt viscosity of such hot melt adhesive is 170℃
It is more than 40,000 cPs. If the melt viscosity is 170° C. and 100,000 cPs or more, the operability in nozzle discharge tends to deteriorate. In the information recording medium of the present invention, the hot-melt adhesive is applied to the disk substrate by nozzle discharge, and before it hardens, a ring-shaped spacer is attached, and then the hot-melt adhesive is hardened and bonded. Next, the hot-melt adhesive described above was applied on the ring-shaped spacer in the same manner, and the other disk substrate was bonded, cured, and bonded. Generally, a hub is inserted and pasted together. In the present invention, the information recording medium includes all media that record information in a recording layer, such as optical discs and flexible optical discs. [Function] In the information recording medium of the present invention, the recording layer side of the disk substrate on which the recording layer is formed is placed inside, a ring-shaped spacer is interposed, and an adhesive is applied between the spacer and the substrate.
It is manufactured by bonding the recording layer of the other disk substrate inside.

The information recording medium manufactured in this way has an adhesive used for bonding between the disk substrate and the ring-shaped spacer.
Because we use a hot melt adhesive with a melt viscosity of 40,000 cPs or more at 170°C, no misalignment occurs between the two disk substrates even when used for long periods of time under high temperature and high humidity conditions, and deformation such as warping is small. Become.

〔Example〕

The present invention will be explained below with reference to the drawings. FIG. 1 is a sectional view showing an information recording medium according to an embodiment. In the figure, 1 is an information recording medium, which includes two disk substrates 2a,
2b are bonded together with an adhesive layer 5 via ring-shaped spacers 4a, 4b so that the recording layers 3a, 3b are on the inside, and a center 66 is provided in the center. 2(a) and 2(b) show the process of applying hot melt adhesive onto the disk substrate on the recording layer side by nozzle discharge using a dispenser device, and FIG. 3(a). (b
) shows the process of compressing and bonding disk substrates coated with hot melt adhesive using a room-temperature press machine. In Figure 2(a). Reference numeral 11 indicates a hot melt adhesive, and a barrel 12 stores 1 liter of adhesive by heating and melting it.
is provided. A needle l3 is arranged at the discharge port of the barrel 12, and a rotation stage 14 is provided below it.
The rotation stage l4 attracts the disk substrates 2a and 2b with a vacuum chuck and rotates in the direction A. At this time, the adhesive 1l in the barrel 12 is discharged from the needle l3 and forms the adhesive layer 5.
is expressed. The rotation stage l4 has a structure that prevents displacement due to rotation. In the present invention, the thickness of the adhesive layer is preferably 10 to 300 II m. The thickness of the applied adhesive layer 5 can be adjusted by adjusting the distance h between the needle l3 provided on the vertically movable barrel 12 and the disk substrates 2a, 2b and the rotation speed R of the rotation stage l4.
Discharge of 1 liter of adhesive can be performed by pressure feeding with gas, mechanical feeding with a pump, etc., but in this example, the case where nitrogen is used as the gas is shown. In Figure 2(a),
Adhesive l is applied independently so as to independently adhere the ring-shaped spacer 48 part on the outer periphery and the ring-shaped spacer 4b part on the inner periphery.
1 is applied, but in this case, barrel 1 is applied.
2 has a mechanism that can also move the disc in the radial direction.
Figure 2(b) shows ring-shaped spacers 4a and 4b on the inner and outer peripheries.
The structure of the barrel l2 has been improved so that the adhesive 11 can be applied at the same time to bond the parts at the same time. Disc substrate 2a on which adhesive layer 5 is formed as described above
Fig. 3(a) shows the arrangement of ring-shaped bases 4a and 4b.
It is set on the positioning pin 23 of the fixed lower die 21 of the room temperature press machine. Next, the disk substrate 2a and the ring-shaped basers 4a, 4b are compressed and bonded together by moving the movable upper mold 22 in the direction B. When the adhesive layer 5 is cooled to below the melting temperature of the adhesive 11 and hardened, the disk substrate 2a and the ring-shaped spacers 4a, 4b are bonded to each other. Next, in the same manner, adhesive 1 is applied onto the ring-shaped spacers 48, 4b of the disk substrate 2a using the method shown in FIG.
Apply 1 again. Thereafter, as shown in FIG. 3(b), the disk substrate 2a is set on the fixed lower mold 21, the disk substrate 2b is set on top of it so that the recording layer 3b faces the disk substrate 2a side, and the movable upper The mold 22 is moved in direction B, compressed, and pasted together. As a result, the information recording medium 1 is manufactured. [Test Example] Below, based on the examples of the present invention, various adhesives were subjected to environmental tests at a temperature of 80°C and a humidity of 85%.
Change in sled (■rad) after 500 hours (after test/
(before testing) was calculated and evaluated using the following formula. Test Example 1 As an adhesive, a maleic anhydride-modified ethylene-propylene copolymer containing 35% by weight of ethylene and 65% by weight of propylene (maleic anhydride-containing 'jt1) was used as an adhesive.
(% by weight) 23% by weight, 13% by weight of ethylene-propylene random copolymer containing 5% by weight of ethylene comonomer, polyisobutylene 12 with a number average molecular weight of about 80,000.
% by weight, SEBS copolymer (hydrogenated product of styrene-butadiene-styrene copolymer) with a styrene content of 38% by weight, and aliphatic cyclized resin (aliphatic petroleum) with a number average molecular weight of about 500. Resin) Contains 40%, melt viscosity 50000cPs measured with Emiller viscometer
(170℃) hot melt adhesive was used. As a transparent resin substrate, ethylene content measured by C-NMR was 62 mol%, MFR (260°C) 35 g
Intrinsic viscosity [η
) 0.47dffi/g, TMA 148°C ethylene and 1,4,5.8-dimethano-1,2,3,4.4a
, 5,8,8a-A resin obtained by copolymerizing octahyde-naphthalene was used. As a ring-shaped spacer, the thickness is 0.
．． A material made of 4■ polycarbonate resin was used. A To film was used as the optical memory layer. Using these materials, information recording medium 1 was manufactured using the manufacturing method described above, and the environmental test was conducted. The results are shown in Table 2. Test Example 2 As an adhesive, a maleic anhydride modified product of an ethylene/propylene copolymer containing 135% by weight of ethylene and 65% by weight of propylene (!! water maleic acid content of 1% by weight), 23% by weight of ethylene 13% by weight ethylene/propylene random copolymer containing 5% comonomer;
SEBS copolymer (hydrogenated product of styrene-butadiene-styrene copolymer) containing 12% polyisobutylene with a number average molecular weight of about 80,000 and styrene content 38% by weight
12% by weight, 40% by weight of aliphatic cyclized resin (aliphatic petroleum resin) with a number average molecular weight of about 500, and 0.1% of talc.
Information recording medium 1 was prepared in the same manner as in Test Example 1, except that a hot melt adhesive containing
We created it and conducted the environmental tests mentioned above. The thickness of the hot melt adhesive layer was approximately 120μ. The results are shown in Table 2. Comparative Example As a comparative example, the adhesive has a melt viscosity of 26QOOcPs (1
The test was carried out in the same manner as in Test Example 1, except that MU102 (Konishi Co., Ltd. 11, trade name) was used. The results are shown in Table 2. [Effects of the Invention] As described above, the information recording medium of the present invention has a melt viscosity of 4000 at 170°C as an adhesive for bonding disk substrates.
Because a hot melt adhesive with a strength of 0 cPs or more is used, even if exposed to high temperature and high humidity conditions for long periods of time, no misalignment will occur between the two bonded disk substrates, and deformation such as warping will be reduced.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the information recording medium of the example, Figure 2 (a)
．． (b) is a cross-sectional view showing the adhesive application process, and Figure 3 (
a) and (b) are cross-sectional views showing the bonding process. In each figure, the same reference numerals indicate the same or corresponding parts, and l indicates the information recording medium. 2a. 2b is a disk substrate, 3a, 3b are recording layers, 4a, 4b are ring-shaped substrates, 5 is an adhesive layer, 11 is a hot melt adhesive, 12 is a barrel, 14 is a rotation stage, 21 is a fixed lower mold, 22 is a Movable upper mold, 23
is a positioning bin.

Claims (5)

[Claims] (1) In an information recording medium in which two disk substrates each having a recording layer formed on one side of at least one transparent resin substrate are bonded together with an adhesive via a ring-shaped spacer, the melt viscosity of the adhesive is 170 An information recording medium characterized in that it is a hot melt adhesive having a temperature of 40,000 cPs or more at °C. (2) The information recording medium according to claim 1, wherein the information recording medium is an optical information recording medium. (3) The transparent resin substrate has an intrinsic viscosity [η] of 0.01 to 10 dl/g as measured in decalin at 135°C (a
) A cyclic olefin random copolymer consisting of an ethylene component and a cyclic olefin component represented by the following general formula [1], or (b) a ring-opening polymer of a cyclic olefin component represented by the following general formula [1], or The information recording medium according to claim 1 or 2, which is made of a hydrogenated substance thereof. ▲There are mathematical formulas, chemical formulas, tables, etc.▼... [1] (In the formula, R^1 to R^1^2 are hydrogen atoms, hydrocarbon groups, or halogen atoms, and may be the same or different. Good. Also R^3 and R^1^0, or R^1^
1 and R^1^2 may be combined to form a divalent hydrocarbon group, and R^9 or R^1^0 and R^1^1 or R^1^2 may form a ring with each other. n may be 0 or a positive integer, and when R^5 to R^8 are repeated multiple times, they may be the same or different. ) (4) The hot melt adhesive contains (A) a polyα-olefin, (B) a styrene polymer, and (C) a tackifier. information recording medium. (5) Poly α-olefin (A) is (A-1) ethylene/propylene copolymer, (A-2)
5. The information recording medium according to claim 4, which is a mixture of polypropylene and (A-3) polyisobutylene.