JP2518954C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium, and more particularly to an information recording medium capable of recording or reproducing information by light. 2. Description of the Related Art A so-called optical disc as an optically recordable information medium must have various disc structures depending on the behavior of a recording film during recording. For example, when an organic thin film (hereinafter, referred to as a recording film) is used for a recording layer, current technology mainly achieves optical recording by opening so-called pits. In the case of an optical disk having such a recording film, the optical disk structure is generally a so-called air sandwich structure in which a space is arranged on one surface of the recording film. Further, the constituent members of the optical disk are diversified, and the important one is an adhesive used for sealing. This is because the adhesive contains various kinds of reactive species as described later, and this has a considerable influence on the constituent materials of the recording film. The optical disc has three functions of recording information, properly outputting a system signal, and storing information. In each case, the recording film plays an important role. Therefore, the thin film properties must have sufficient durability against various disturbances (temperature, humidity, gas, light, etc.). Organic thin films are so-called "rusting" like metals
Although oxidation is not considered, it can react with various reactive species and cause molecular collapse, and if it is in contact with the reactive species for a certain period of time, it changes over time, in other words, changes in molecular structure Alternatively, collapse may be caused, and the function as a functional film may not be sufficiently achieved. To be specific, it is conceivable that various reactive species are generated from the constituent members to break down molecules of the organic thin film. From this point of view, it is expected that the range of the sealing adhesive used for forming the air sandwich structure is considerably limited. If we talk about the type of adhesive and its applicability, among thermosetting adhesives, there is a mixed type of isocyanate and polyol adhesives that has sufficient adhesive strength and has no adverse effect on the recording film. However, it takes a long time to cure and is not practical in terms of productivity. In addition, the organic thin film is attacked by the remaining unreacted monomer in the ultraviolet curing adhesive. Even if curing is performed in a nitrogen atmosphere to completely cure unreacted monomers, it is extremely difficult to reduce residual monomers to zero,
The process becomes complicated. That is, the most suitable sealing adhesive for the organic thin film is considerably limited and has a problem in the manufacturing process. By the way, one of the sealing methods which seems to be the simplest in view of the process is a welding method using ultrasonic waves. However, in this case, there are disadvantages that a large amount of molten gas is generated, the birefringence of the peripheral portion of the weld increases, and the drop impact strength is weak. In order to improve such a defect, it is conceivable to use a pressure-sensitive adhesive as a sealing adhesive. In this case, the point to be considered is not only that the adhesive has the necessary adhesive strength but also whether various components contained in the adhesive do not adversely affect the recording film. If the reactive species that affect the organic thin film as the recording film are viewed from the viewpoint of the adhesive component, a polymer (adhesive main component) polymer decomposed product, an unreacted monomer crosslinking agent, a polymerization initiator, and the like can be considered. Of these, particularly, is particularly generally reactive and requires attention. By the way, there are a wide variety of types of pressure-sensitive adhesives, but the rubber-based pressure-sensitive adhesive component contains a tackifier, a softener, an antioxidant, etc. in addition to the above, and is unsuitable for this use from the viewpoint of durability. is there. The acrylic pressure-sensitive adhesive hydrolyzes to derive acrylic acid, or decomposes organic substances which are components of a recording film because of containing acrylic acid (Japanese Patent Publication No. 37-1471). Conventionally known silicone-based pressure - sensitive adhesives include 40 to 60 parts by weight of a copolymer having a molar ratio of SiO ₂ units to R ₃ SiO _0.5 of 1: 0.5 to 1: 1 and dimethylpolysiloxane raw rubber 40. Dimethylpolysiloxane raw rubber or a rubber partially containing a phenyl group (Japanese Patent Publication Nos. 30-5186 and 32-5099). ing. Benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumylbenzoyl peroxide, and the like are often used as a crosslinking catalyst for the silicone-based pressure-sensitive adhesive, and aminosilanes are also known. However, when the above catalyst is used, the silicone pressure-sensitive adhesive adversely affects the organic matter of the recording film. For example, benzoyl peroxide decomposes to benzoic acid and remains in the pressure-sensitive adhesive as an unreacted substance, which itself is highly reactive and easily decomposes the organic substance. [Problems to be Solved by the Invention] In order to solve the above problems, the present invention provides a pressure-sensitive adhesive which does not adversely affect the recording film and has excellent mechanical properties (adhesive strength, temperature and humidity properties, viscoelastic properties). An object of the present invention is to provide an information recording medium which is extremely excellent in mechanical strength, reliability and durability. [Means for Solving the Problems] In order to solve the above problems, the present invention provides a method for recording a pair of substrates having an optical recording layer on one surface of at least one disk-shaped substrate, directly or via a spacer. An information recording medium bonded using a silicone-based adhesive such that a layer is on the inside, wherein the pair of substrates is a silicone-based adhesive obtained by adding a platinum-based catalyst.
Therefore, it is configured to be attached . First, a schematic configuration of an information recording medium (hereinafter, referred to as a recording medium) of the present invention will be described with reference to FIGS. FIG. 1 is a schematic perspective view in which a part of a recording medium is cut away, and FIG. 2 is a half sectional view showing a configuration of the recording medium. FIG. 3 is an enlarged sectional view of the peripheral portion of the recording medium, and FIG. 4 is a sectional view of the adhesive. As shown in FIG. 1, a recording medium 1 is composed of two opposing flat substrates 21 and 2.
5, ring-shaped spacers 3 and 5 sandwiched between these opposing substrates and disposed at the peripheral edge and the inner peripheral portion of the substrate, respectively, and magnetic clamp hubs 10 and 10 provided at the center of the substrate. It has. The substrates 21 and 25 are usually made of a plastic material, and a groove 7 as shown in FIG. 2 is usually formed on their facing surfaces, and a recording film 70 is formed on this surface.
Is formed. As an organic substance constituting the recording film 70, any one of phenylmethane, methine / polymethine, pyrylium, indanthrene, quinone, dithiol, porphine, dioxazine, dithiazine, triquinocyclopropane, fulgide, diallylethene, spiropyran, and naphthoxazine Those having a skeleton are used. Various known inorganic materials that can be optically recorded can also be used as the recording film. The recording film may be provided only on one of the opposing substrates. The substrates 21 and 25 having such a recording film 70 are fixed at fixed intervals by spacers 3 and 5 provided on the inner peripheral portion and the inner peripheral portion of the substrate. As shown in detail in FIG. 3, the spacer 3 includes a ring-shaped spacer body 39 made of a plastic material such as a polycarbonate resin, and a spacer body 3.
9 have ring-shaped adhesive bodies 30 provided on both planes, respectively. As shown in FIG. 4, the adhesive body 30 functions as a support, for example, a base material 31 made of a material such as a polyethylene terephthalate resin film, and an adhesive layer provided on both planes of the base material 31, respectively. Adhesives (silicone- based adhesives)
(Adhesive) . The silicone-based adhesives 34 and 36 contain platinum as a catalyst. Thus, as a silicone adhesive,
By using a silicone-based pressure-sensitive adhesive that has been cross-linked and polymerized using a platinum-based catalyst, there is no problem such as deterioration of the recording film due to a spacer adhesive using a catalyst such as benzoyl peroxide as in the related art. The silicone- based adhesive used in the present invention has SiO ₂ units and R ₃ SiO _0.5 units (
R represents a substituted or unsubstituted monovalent hydrocarbon group);
'Organopolysiloxane (R having ₂ SiO units' represents a hydroxyl group R, alkoxy group, or a substituted or unsubstituted monovalent hydrocarbon group, 0.005 of all organic groups
3 mol% represents a vinyl group) and an organopolysiloxane partially condensed with R ″ ₂ SiO units (R ″ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon) in all organic groups. Containing from 1 to 6% by weight of an organohydrogenpolysiloxane containing 0.02 to 10 mol% of Si-H groups and the remainder mainly methyl groups, based on the mixture of the copolymer resin and the organopolysiloxane. Is an adhesive obtained by adding The present invention will be described in more detail. In the silicone adhesive used in the present invention,
Organopolysiloxane composition contained in the and preferably 50 parts by weight than the copolymer resin 60-40 parts by weight of SiO ₂ units and R ₃ SiO _0.5 units, R _'2 S
40-60 parts by weight, more preferably 50 parts by weight, of an organopolysiloxane having iO units
It is obtained by mixing with parts by weight to cause a partial condensation reaction. The molar ratio of SiO ₂ units to R ₃ SiO _0.5 units of the copolymer resin is 1: 0.
The ratio is 5: 1 to 1: 1, more preferably 1: 0.7. If the molar ratio exceeds the above range and the amount of SiO ₂ units is too large, the compatibility with the organopolysiloxane having R ′ ₂ SiO units becomes poor, and it becomes difficult to perform partial condensation. Conversely, if the amount of SiO ₂ units is too small, the cohesiveness of the pressure-sensitive adhesive decreases. R ′ in the copolymer resin represents a hydroxyl group, an alkoxy group or a substituted or unsubstituted monovalent hydrocarbon group, and examples of the substituted or unsubstituted monovalent hydrocarbon include a methyl group, an ethyl group, and a propyl group. Examples thereof include an alkenyl group such as an alkyl group, a vinyl group and an allyl group, and an aryl group such as a phenyl group. 0.005 to 3 mol%, more preferably 0.01 to 2.0 mol%, of all organic groups bonded to silicon atoms of the organopolysiloxane having R ′ ₂ SiO units are vinyl groups. When the vinyl group content is less than 0.005 mol%, the crosslink density becomes small and the cohesiveness becomes poor. When the vinyl group content exceeds 3 mol%, the crosslink density becomes large and the adhesiveness becomes poor. If the proportion by weight of the copolymer resin and the organopolysiloxane having an R ' ₂ SiO unit is out of the above range, there is a disadvantage that the adhesiveness is poor in both upper and lower cases. On the other hand, R ″ ₂ S added to the organopolysiloxane obtained by partial condensation
The organohydrogenpolysiloxane having an iO unit is a component that undergoes a crosslinking reaction with the condensate. Here, R ″ represents a hydrogen atom or a monovalent hydrocarbon group, and 0.02 to 10 mol%, more preferably 0 to 10 mol%, of all organic groups in the R ″ ₂ SiO unit.
. 6 to 3 mol% are Si-H groups, and the rest are mainly methyl groups. When the Si-H group is out of the above range, the crosslink density becomes excessive or insufficient, and there is a disadvantage that cohesiveness or tackiness is poor. Such an organohydrogenpolysiloxane is blended in an amount of 1 to 6% by weight, more preferably 2% by weight, based on the mixture of the copolymer resin and the organopolysiloxane. When this value is less than 1% by weight, there is a disadvantage that the crosslink density is small and the cohesiveness is inferior. When this value exceeds 6% by weight , the cohesiveness of the silicone adhesive is high and the cohesiveness is inferior. Occurs. Specific examples of such an organohydrogenpolysiloxane having R ″ ₂ SiO units include the following. In the above structural formula, R is a substituted or unsubstituted monovalent hydrocarbon group as described above, R ′
Is a hydrogen atom or a monovalent hydrocarbon group, p = 0 to 3000, q = 0 to 3000, provided that the compound has two or more hydrogen atoms bonded to a silicon atom in one molecule. The platinum or platinum compound as a component of the crosslinking catalyst may be any of those conventionally known as a catalyst for an addition reaction between a vinyl group-containing organopolysiloxane and an organohydrogenpolysiloxane. Examples thereof include chloroplatinic acid, a complex of chloroplatinic acid and an olefin, and solid platinum supported on a carrier such as platinum, alumina, and silica. The structure of the spacer 5 provided on the inner peripheral portion of the substrate is the same as the spacer 3 described above.
The configuration is similar to that of. Another embodiment of the recording medium as described above is shown in FIG. 5 and FIG. FIG. 5 shows the use of disk-shaped flat plate spacers 4 in which the peripheral portions and the inner peripheral portions of the substrates 21 and 25 project, and ring-shaped adhesive bodies 30a and 30a are provided on the projections 41 and 45, respectively. And 50a, 50a are provided. The configuration of these adhesives is the same as that of the adhesive 30 described above. FIG. 6 shows an embodiment in which the substrates 21 and 25 are adhered with the adhesive layer 300 interposed therebetween. In this case, the basic configuration of the bonding layer 300 is the same as that of the bonding body 30 described above. [Operation] The medium of the present invention is generally irradiated with recording light in a pulsed manner while rotating.
At this time, a part of the recording film is melted and removed to form a pit. The pits thus formed are formed by detecting the difference between the reflected light of the read light and the rotation of the medium. EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention. Example 1 50 parts by weight of a methylpolysiloxane resin consisting of 0.7 mol of (CH ₃ ) ₃ SiO _0.5 unit and 1 mol of SiO ₂ unit, 99.8 mol of (CH ₃ ) ₂ SiO unit and (CH 50 parts by weight of a raw rubber-like diorganopolysiloxane having a ratio of ₂ = CH) (CH ₃ ) SiO units of 0.2 mol are mixed with toluene,
A partial condensation reaction was performed at a temperature of 130 ° C. for about 6 hours to obtain a 60% toluene solution of a vinyl group-containing organopolysiloxane. Both ends of the molecular chain are blocked with a trimethylsilyl group with respect to this toluene solution,
The average degree of polymerization was 200, and the content of hydrogen atoms directly connected to silicon was 0.0 g / 100 g.
5 wt% (Si-H: 1.7 mol%) of methyl hydrogen polysiloxane was added at 2 wt%, and chloroplatinic acid was added thereto so that the platinum amount became 15 ppm.
Further, the coating solution was prepared by diluting with toluene so that the nonvolatile content became 30% by weight. This coating solution was applied on both sides of a polyester film having a thickness of 25 μm,
For 10 minutes to prepare an adhesive tape having a thickness of 30 μm for each of the silicone-based adhesives . The information recording medium shown in FIG. 2 was manufactured using this adhesive tape as the adhesive 30 (sample of the present invention). Comparative Example 1 1.2 parts by weight of benzoyl peroxide and 100 parts by weight of toluene were added to 100 parts by weight of a silicone-based adhesive KR101-10 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) to prepare a coating solution, and a polyester film having a thickness of 25 μm was prepared. And dried and cured at 130 ° C. for 10 minutes to prepare pressure-sensitive adhesive tapes each having a thickness of 30 μm. Using this adhesive tape as an adhesive, an information recording medium shown in FIG. 2 was produced (Comparative Sample 1). Comparative Example 2 Silicone adhesive SH-4280 (trade name, manufactured by Toray Silicone Co., Ltd.) 100
Aminosilane KBM-603 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.); H ₂ NC ₂ H ₄ N
A coating solution was prepared by adding 1 part by weight of HC ₃ H ₆ Si (OCH ₃ ) _{3 and} 100 parts by weight of toluene, applied to both sides of a 25 μm-thick polyester film, and dried and cured at 80 ° C. for 5 minutes to obtain an adhesive. An adhesive tape having a thickness of 30 μm was prepared. Using this adhesive tape as an adhesive, an information recording medium shown in FIG. 2 was produced (Comparative Sample 2). Comparative Example 3 100 parts by weight of butyl acrylate (73.4 equivalent%), 20 parts by weight of methyl methacrylate (18.8 equivalent%), 6 parts by weight of acrylic acid (7.8 equivalent%), 350 parts by weight of benzol, A mixture of 0.25 parts by weight of benzoyl oxide was heated and polymerized at 60 ° C. while stirring in a nitrogen stream, and a polymerization rate of 90 to 93% was obtained in a polymerization time of 8 hours.
A polymer having a viscosity of about 5000 CP was obtained. The acrylic acid content in this polymer is about 10
Equivalent%. The acrylic acid in this polymer was treated with Desmodur TH (4 parts of triol diisocyanate, 1 part of hexanediol, 1 part of trimethylolpropane).
Part of the partially polymerized product), uniformly mixed, and then applied to both sides of a 25 μm-thick polyester film, dried at 130 ° C. for 10 minutes, and crosslinked to form a film having a thickness of 3 μm.
A 0 μm adhesive tape was obtained. Using this adhesive tape as an adhesive, an information recording medium shown in FIG. 2 was produced (Comparative Sample 3). The recording films of the above four samples (samples of the present invention and comparative samples 1 to 3) were all thin films of cyanine. FIGS. 7 (a) to 7 (c) show the change in the rate of change for each wavelength measured through the substrate for each of these samples. FIG. 7 (a) shows the wavelength dependence of the initial reflection characteristics of the sample of the present invention and the comparative samples 1 to 3. In the initial stage, the tendency of the reflectance is the same in each case, and therefore, it is represented by a single diagram in FIG. 7 (a). Each of the samples was allowed to stand for 200 hours in an environment of a 50 ° C. absolutely dry state, and then the change in reflectance was examined (FIGS. 7 (b) and 7 (c)). FIG. 7 (b) shows a sample of the present invention. FIG. 7 (c) shows comparative sample 1.
~ 3. Since Comparative Samples 1 to 3 show the same behavior,
This is represented by a single diagram in FIG. The measurement points were five points (-) in the radial direction as shown in the schematic diagram of FIG. In this case, the outer spacer 3, that is, the adhesive (the silicone adhesive of Example 1 or the adhesive of Comparative Examples 1 to 3) is in contact with the recording film. The sample of the present invention has no change in reflectivity as shown in FIG. 7 (b), but the samples of comparative samples 1 to 3 have a large difference depending on the portion of the recording film as shown in FIG. 7 (c). It can be seen from FIG. The decrease in reflectivity indicates that the molecular collapse of the recording film is progressing accordingly, which indicates that the sample of the present invention has no influence on the recording film. FIG. 9 shows data on the repetition call durability, and the value on the vertical axis is always 10
Ideally, 0 can be ensured, but in practice, it generally falls gradually. Comparing the sample of the present invention with Comparative Sample 1, it can be seen that the former value is superior to the latter value. For example, the sample of the present invention is 1.1 million times, which is 1.7 times that of the comparative sample 1 while it drops to 90% of the initial value, which is superior to the sample of the present invention. . This suggests that a reactive gas was emitted from the conventional adhesive used for Comparative Sample 1, which had an adverse effect on the recording film, whereas the sample of the present invention did not have such a phenomenon. doing. [Effects of the Invention] The effects of the present invention are clear from the above results. That is, the information recording medium of the present invention is a silicone-based adhesive in which a pair of substrates having an optical recording layer on one surface of at least one disk-shaped substrate are directly or through a spacer such that the recording layer is inside. An information recording medium which is bonded by using a silicone-based adhesive and containing a platinum-based crosslinking catalyst in the silicone-based adhesive, so that the information-recording medium is extremely excellent in mechanical strength, reliability and durability. Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view in which a part of an information recording medium is cut away, FIG. 2 is a half sectional view showing a configuration of the information recording medium, and FIG. 3 is a peripheral portion of the information recording medium. FIG. 4 is an enlarged sectional view, FIG. 4 is a sectional view of an adhesive body, FIGS. 5 and 6 are half sectional views showing another embodiment of the present invention,
7 (a) to 7 (c) are graphs each showing a change in reflectance for each wavelength measured through a substrate, FIG. 8 is a half-sectional view of a disk for explaining a measurement position, and FIG. It is a graph which shows the result of a durability test. DESCRIPTION OF SYMBOLS 1 ... Information recording medium, 21, 25 ... Substrate, 3, 4, 5 ... Spacer, 30 ... Adhesive body, 31 ... Base material, 34, 36 ... Adhesive, 39 ... Spacer main body.

Claims (1)

[Claims] 1. An information recording medium in which a pair of substrates having an optical recording layer on one surface of at least one disk-shaped substrate are bonded together using a silicone-based adhesive such that the recording layer is located directly or via a spacer. In addition, the silicone-based adhesive is added to the vinyl group-containing organopolysiloxane composition.
Addition reaction type silicone adhesive containing ganohydrogenpolysiloxane
An information recording medium , which comprises a catalyst and platinum as a catalyst . 2. The silicone adhesive has a molar ratio of SiO ₂ units to R ₃ SiO _0.5 units (R represents a substituted or unsubstituted monovalent hydrocarbon group) of 1: 0.5 to 1: 1.
And an organopolysiloxane having an R ′ ₂ SiO unit (R ′ is a hydroxyl group, an alkoxy group, or a substituted or unsubstituted monovalent hydrocarbon group; 005 to 3 mol% represents a vinyl group) 4
A vinyl group-containing organopolysiloxane composition obtained by mixing or condensing 0 to 60 parts by weight with a total organic compound of R ″ ₂ SiO (R ″ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group) An organohydrogenpolysiloxane in which 0.02 to 10 mol% of the group is a Si-H group and the remainder is mainly a methyl group is blended in an amount of 1 to 6% by weight based on the vinyl group-containing organopolysiloxane composition. The information recording medium according to claim 1 , wherein: 3. 2. The recording layer according to claim 1, wherein the recording layer comprises an organic thin film.
Item 3. An information recording medium according to Item 2 .