JP2006164496A - Optical recording medium and method for producing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical recording medium having adequate antifouling properties and adhesion which can be commercially advantageously produced by a simple method. <P>SOLUTION: The optical recording medium comprises a base and a recording/reproducing function layer formed on the base and further comprises a light-transmitting layer formed on the recording/reproducing function layer and an antifouling layer formed on the light-transmitting layer. The light-transmitting layer is formed by curing a composition which contains silica particles and an oligomer having an urethane bond and is cured by irradiation with a radiation ray. The antifouling layer contains an alkoxysilane compound containing a fluorine atom and/or a hydrolysis product of an alkoxysilane compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical recording medium and a method for manufacturing the same.

  In an optical recording medium such as the next DVD that uses a blue laser for reading, in order to protect the recording / reproducing functional layer for recording, a protective layer (hereinafter referred to as “ A protective layer). Such a protective layer is required to have properties such as low curing shrinkage and high hardness, and to have antifouling properties in order to prevent contamination of the surface of the optical recording medium. In response to such demands, various developments have conventionally been made on techniques for providing an appropriate protective layer on the surface of an optical recording medium.

For example, Patent Document 1 discloses a light transmission layer mainly composed of urethane acrylate and a top layer mainly composed of an active energy ray-curable compound that may contain dispersed inorganic component particles on the surface of an optical recording medium. And a technique for providing an antifouling layer formed of a photocurable resin containing a fluorine compound, thereby providing the optical recording medium with antifouling properties.
Furthermore, Patent Document 2 proposes a composition exhibiting low shrinkage and high hardness using silica particles and an oligomer having a urethane bond, and this composition may be used for a protective layer of an optical recording medium. It was described.

JP 2004-83877 A International Publication No. 2004/041888 Pamphlet

  However, the technique described in Patent Document 1 has a problem that the layer formed on the surface of the optical recording medium has a three-layer structure, which is expensive, inferior in workability, and poor in practicality. Further, according to the study by the present inventors, when the top layer is used as an anchor layer having a large film thickness, the anchor layer is cracked or deformed such as warping of the optical recording medium due to curing shrinkage. It has been found that there is a problem that causes Furthermore, it was also found that the adhesion between the top layer and the antifouling layer was poor.

Further, the technique described in Patent Document 2 has a problem that it is difficult to improve the antifouling property of the optical recording medium.
The present invention was devised in view of the above problems, and an object thereof is to provide an optical recording medium provided with sufficient antifouling properties and adhesion by a simple and industrially advantageous method and a method for producing the same. And

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention contain silica particles and an oligomer having a urethane bond in an optical recording medium having a substrate and a recording / reproducing functional layer. By providing a light-transmitting layer obtained by curing a curable composition and an antifouling layer containing a fluorine atom-containing alkoxysilane compound and / or a hydrolysis product of the alkoxysilane compound, sufficient The present invention has been completed by finding that an optical recording medium provided with an excellent antifouling property and adhesion between the light transmission layer and the antifouling layer can be provided by a simple and industrially advantageous method.

That is, the gist of the present invention is a substrate, a recording / reproducing functional layer formed on the substrate, a light-transmitting layer formed on the recording / reproducing functional layer and cured by the following component A, and the light-transmitting layer. The optical recording medium comprises an antifouling layer formed on the layer and containing the following component B (claim 1).
Component A: A composition containing silica particles and an oligomer having a urethane bond, which can be cured by irradiation with radiation.
Component B: An alkoxysilane compound containing a fluorine atom and / or a hydrolysis product of the alkoxysilane compound.

At this time, it is preferable that the silica particle contained in this component A is a silica particle which consists of colloidal silica or the hydrolyzate of the oligomer of alkoxysilane (Claim 2).
The silica particles contained in Component A preferably have a number average particle diameter of 0.5 nm or more and 50 nm or less (Claim 3).

Furthermore, the silica particles contained in the component A are preferably surface-treated with a silane coupling agent (claim 4).
The alkoxysilane compound containing a fluorine atom contained in Component B is preferably a silane coupling agent containing a fluoroalkyl group or a fluoroaryl group.

  Another gist of the present invention is a method for producing the optical recording medium, wherein the component A is cured on the recording / reproducing functional layer to form the light transmissive layer, and the light transmissive layer is formed. And a step of applying the composition containing the component B and a solvent and having a solid content of 0.01% by weight to 1% by weight and drying to form the antifouling layer. The present invention resides in a method for manufacturing the optical recording medium.

  At this time, in the method for producing an optical recording medium, the silica particles are prepared in a liquid medium containing a solvent, the oligomer having the urethane bond is dissolved in the liquid medium, and then the solvent of the liquid medium is used. It is preferable to have the process of preparing the said component A by removing (Claim 7).

Moreover, it is preferable that the said solid content contains the alkoxysilane compound containing a fluorine atom, and / or the hydrolysis product of the said alkoxysilane compound (Claim 8).
Furthermore, it is preferable to use a halogen-based organic solvent as the solvent.

According to the optical recording medium of the present invention, the optical recording medium can be provided with sufficient antifouling property and adhesion by a simple and industrially advantageous method.
Further, according to the method for producing an optical recording medium of the present invention, an optical recording medium having sufficient antifouling properties and adhesion can be reliably produced by a simple and industrially advantageous method.

Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following examples and the like, and can be arbitrarily modified without departing from the gist of the present invention.
The optical recording medium of the present invention includes a substrate, a recording / reproducing functional layer, a light transmission layer, and an antifouling layer. In this case, the light transmission layer contains component A, that is, silica particles (preferably silica particles made of hydrolyzate of alkoxysilane oligomer) and oligomers having urethane bonds, and can be cured by irradiation with radiation. It is formed as a cured composition (hereinafter referred to as “composition A” as appropriate). Further, the antifouling layer is formed as containing component B, that is, an alkoxysilane compound containing a fluorine atom and / or a hydrolysis product of the alkoxysilane compound.

[1. substrate]
There is no restriction | limiting about a board | substrate, A well-known thing can be used arbitrarily as a board | substrate of an optical recording medium.
The substrate of an optical information recording medium is generally formed as a plate having concave and convex grooves (tracking grooves) for use in recording and reproducing optical information on one main surface. Although the shape is arbitrary, it is usually formed in a disk shape.

  The substrate material is not limited as long as it is a light transmissive material. That is, it can be formed of any material that can transmit light of a wavelength used for recording and reproducing optical information. Specific examples thereof include thermoplastic resins such as polycarbonate resin, polymethacrylate resin, and polyolefin resin, and glass. Of these, polycarbonate resins are most preferred because they are most widely used in CD-ROMs and the like and are inexpensive. In addition, the material of a board | substrate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Further, the dimensions of the substrate are not limited and are arbitrary. However, the thickness of the substrate is usually 0.1 mm or more, preferably 0.3 mm or more, more preferably 0.5 mm or more, and usually 20 mm or less, preferably 15 mm or less, more preferably 3 mm or less. Among them, a substrate having a thickness of about 1.2 ± 0.2 mm is often used. Further, the outer diameter of the substrate is generally about 120 mm.
Moreover, although there is no restriction | limiting in the manufacturing method of a board | substrate, it is arbitrary, For example, it can manufacture by injection molding of the light transmissive resin etc. which used the stamper.

[2. Recording / playback functional layer]
The recording / reproducing functional layer is a layer formed on the substrate so that an information signal can be recorded / reproduced or reproduced. There is no restriction | limiting in the specific structure of this recording / reproducing functional layer, A well-known thing can be arbitrarily used as a recording / reproducing functional layer of an optical recording medium.

  The recording / reproducing functional layer may have a single layer structure composed of only one layer or a laminated structure composed of a plurality of layers. When the optical recording medium is a reproduction-only medium (ROM medium), when the optical recording medium is a write-once medium (Write Once medium) that can be recorded only once, and when it is a rewritable medium (Rewriteable medium) that can be repeatedly recorded and erased. Depending on the case of the medium), it is possible to adopt a layer structure according to each purpose.

  For example, in a read-only optical recording medium, the recording / reproducing functional layer is usually configured as a single-layered layer including only a reflective layer containing a metal. In this case, the recording / reproducing functional layer can be formed, for example, by forming a reflective layer on the substrate by sputtering or the like.

  Further, for example, in a write-once type optical recording medium, the recording / reproducing functional layer is usually configured as a layer having a laminated structure in which a reflective layer and a recording layer containing an organic dye are formed in this order on a substrate. In this case, the recording / reproducing functional layer can be formed, for example, by forming a reflective layer by sputtering or the like, and forming an organic dye on the reflective layer as a recording layer by spin coating or the like. .

  Another specific example of the recording / reproducing functional layer of the write-once optical recording medium is a layered structure in which a reflective layer, a dielectric layer, a recording layer, and a dielectric layer are formed in this order on a substrate. Is mentioned. In this case, generally, the dielectric layer and the recording layer contain an inorganic material. Such a write-once medium can be formed by forming a reflective layer, a dielectric layer, a recording layer, and a dielectric layer by sputtering.

  Further, for example, in a rewritable optical recording medium, the recording / reproducing functional layer is usually a laminated structure in which a reflective layer, a dielectric layer, a recording layer, and a dielectric layer are formed in this order on a substrate. Configured as a layer. In addition, such a rewritable medium can be generally formed by forming a reflective layer, a dielectric layer, a recording layer, and a dielectric layer by sputtering.

Another specific example of the recording / reproducing functional layer of the rewritable optical recording medium includes a recording / reproducing functional layer similar to that used for the magneto-optical recording medium. In this case, the recording / reproducing functional layer is formed of a reflective layer, a recording layer, and a dielectric layer.
Furthermore, in general, an optical recording medium is provided with a recording / reproduction area for actual recording and reproduction. This recording / reproducing area is usually provided in an area having an inner diameter larger than the inner diameter of the recording / reproducing functional layer and an outer diameter smaller than the outer diameter of the recording / reproducing functional layer. In the recording / reproducing area, a tracking groove of the substrate is formed.

Hereinafter, each layer constituting the recording / reproducing functional layer will be described in detail.
[2-1. Reflective layer]
The reflective layer is a layer for reflecting light used for recording and reproduction of the optical recording medium. The specific configuration is not limited, and a known layer can be arbitrarily used as the reflection layer of the optical recording medium.

As the material used for the reflective layer, any material can be used as long as it can reflect light used for recording and reproduction, but a substance having a high reflectance is usually preferable. Moreover, the material of a reflection layer may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
Examples of preferable materials for the reflective layer include metals such as Au, Ag, and Al. This is because a heat dissipation effect can be expected.
Further, in order to control the thermal conductivity of the reflective layer itself and improve the corrosion resistance, metals such as Ta, Ti, Cr, Mo, Mg, V, Nb, Zr, and Si may be used in combination. The amount of the metal used in combination is usually 0.01 mol% or more and 20 mol% or less as a ratio in the reflective layer.

Among them, an aluminum alloy containing 15 mol% or less of Ta and / or Ti, particularly an aluminum alloy of Al _α Ta _(1-α) (where 0 ≦ α ≦ 0.15) has excellent corrosion resistance. Therefore, it is particularly preferable for improving the reliability of the optical recording medium.
In addition, an Ag alloy containing at least one of Mg, Ti, Au, Cu, Pd, Pt, Zn, Cr, Si, Ge, and rare earth elements in an amount of 0.01 mol% to 10 mol% is reflective. Rate and thermal conductivity are high, and heat resistance is also excellent, which is preferable.

  The thickness of the reflective layer is not limited and is arbitrary, but is usually 40 nm or more, preferably 50 nm or more, and usually 300 nm or less, preferably 200 nm or less. If the thickness of the reflective layer is excessively large, the shape of the tracking groove formed on the substrate may change, and further, the film formation takes time and the material cost tends to increase. In addition, if the thickness of the reflective layer is too small, there is a risk that light transmission may occur and the reflective layer may not function, and an island-like structure formed in the initial stage of film growth tends to occur on a part of the reflective layer. The reflectance and thermal conductivity may be reduced.

[2-2. Dielectric layer]
The dielectric layer is a layer for preventing evaporation and deformation accompanying the phase change of the recording layer and controlling thermal diffusion during the phase change. The specific configuration is not limited, and any known dielectric layer for optical recording media can be used.

  The material used for the dielectric layer can be any material as long as it is a dielectric, but usually pay attention to the refractive index, thermal conductivity, chemical stability, mechanical strength, adhesion, etc. It is preferable to select. In general, dielectric materials such as oxides, sulfides, nitrides, carbides, and fluorides such as Ca, Mg, and Li, which are highly transparent and have a high melting point, can be used. Moreover, the material of a dielectric material layer may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Furthermore, the materials such as oxides, sulfides, nitrides, carbides and fluorides described above do not necessarily have a stoichiometric composition, and the composition is controlled or mixed for controlling the refractive index and the like. It is also effective to use.

  Specific examples of such a dielectric layer material include Sc, Y, Ce, La, Ti, Zr, Hf, V, Nb, Ta, Zn, Al, Cr, In, Si, Ge, Sn, Sb, And oxides of metals such as Te; metals such as Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Zn, B, Al, Ga, In, Si, Ge, Sn, Sb, and Pb And nitrides of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Zn, B, Al, Ga, In, and Si, and mixtures thereof. Further, a sulfide of a metal such as Zn, Y, Cd, Ga, In, Si, Ge, Sn, Pb, Sb, and Bi; a selenide or a telluride; a fluoride such as Mg or Ca, or a mixture thereof. It can also be mentioned.

In particular, considering the repeated recording characteristics of the optical recording medium, it is preferable to form the dielectric layer from a mixture of dielectrics. For example, a dielectric layer is formed by a mixture of a chalcogen compound such as ZnS or rare earth sulfide and a heat-resistant compound such as oxide, nitride, carbide, or fluoride. Further, for example, a mixture of a heat-resistant compound containing ZnS as a main component and a mixture of a rare-earth sulfate, particularly a heat-resistant compound containing Y ₂ O ₂ S as a main component are examples of a preferable dielectric layer composition. More specifically, ZnS—SiO ₂ , SiN, SiO ₂ , TiO ₂ , CrN, TaS ₂ , Y ₂ O ₂ S and the like can be mentioned. Among these materials, ZnS—SiO ₂ is widely used because of its high deposition rate, low film stress, small volume change rate due to temperature change, and excellent weather resistance.

  Furthermore, although there is no restriction | limiting in the thickness of a dielectric material layer, it is 1 nm or more normally, and is usually 500 nm or less normally. By setting the thickness to 1 nm or more, the effect of preventing deformation of the substrate and the recording layer can be sufficiently secured, and the role as a dielectric layer can be sufficiently achieved. Further, when the thickness is 500 nm or less, it is possible to prevent the occurrence of cracks due to a significant difference in the internal stress of the dielectric layer itself and the elastic property with respect to the substrate while sufficiently fulfilling the role as the dielectric layer. .

[2-3. Recording layer]
The recording layer is a layer for recording information by the phase change. The specific configuration is not limited, and any known recording layer of an optical recording medium can be arbitrarily used.
As the material used for the recording layer, known materials can be arbitrarily used, and one kind may be used alone, or two or more kinds may be used in any combination and ratio.
Specific examples thereof include compounds having a composition such as GeSbTe, InSbTe, AgSbTe, AgInSbTe. Among _{them, {(Sb 2 Te 3)} (1-x) (GeTe) x} (1-y) Sb y ( however, 0.2 ≦ x ≦ 0.9,0 ≦ y ≦ 0.1) alloy, Or {Sb _x Te _(1-x) } _y M _(1-y) (where 0.6 ≦ x ≦ 0.9, 0.7 ≦ y ≦ 1, and M represents Ge, Ag, In , Ga, Zn, Sn, Si, Cu, Au, Pd, Pt, Pb, Cr, Co, O, S, representing at least one atom selected from Se, V, Nb, Ta) The thin film is preferable because it is stable in both crystalline and amorphous states and can undergo high-speed phase change (phase transition) between both states. Furthermore, these materials have the advantage that segregation hardly occurs when repeated overwriting, and are the most practical materials.

  Further, as a material for the recording layer, an organic dye may be used instead of or in combination with the above inorganic compound. Specific examples of the organic dyes include macrocyclic azaannulene dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), pyromethene dyes, polymethine dyes (cyanine dyes, merocyanine dyes, squarylium dyes, etc.), anthraquinone dyes, Examples include azulenium dyes, metal-containing azo dyes, and metal-containing indoaniline dyes. Among these organic dyes, metal-containing azo dyes are preferable because they are excellent in recording sensitivity and excellent in durability and light resistance.

  Further, the organic dye used in the recording layer is preferably a dye compound having a maximum absorption wavelength λmax in the visible light to near infrared region of about 350 to 900 nm and suitable for recording with a blue to near microwave laser. A near-infrared laser having a wavelength of about 770 to 830 nm (typically 780 nm, 830 nm, etc.) used for a CD-R or a red laser having a wavelength of about 620 to 690 nm (typically used for a DVD-R) 635 nm, 650 nm, 680 nm, etc.), or a dye suitable for recording with a so-called blue laser having a wavelength of 410 nm or 515 nm is more preferable.

  The thickness of the recording layer is not limited and is arbitrary, but the lower limit is usually 5 nm or more, preferably 10 nm or more. With such a range, a sufficient optical contrast between the amorphous state and the crystalline state of the recording layer can be obtained. Further, the upper limit of the thickness of the recording layer is usually 30 nm or less, preferably 20 nm or less. With such a range, it is possible to obtain an increase in optical contrast due to the light transmitted through the recording layer being reflected by the reflective layer, and the heat capacity can be controlled to an appropriate value, so that high-speed recording can be performed. It can also be done.

  In particular, if the film thickness of the recording layer is 10 nm or more and 20 nm or less, both higher speed recording and higher optical contrast can be achieved. In addition, by setting the thickness of the recording layer in such a range, the volume change due to the phase change is reduced, and the repeated volume by repeated overwriting is performed on the recording layer itself and other layers in contact with the upper and lower sides of the recording layer. The influence of change can be reduced. Furthermore, accumulation of irreversible microscopic deformation of the recording layer is suppressed, noise is reduced, and repeated overwrite durability is improved.

[2-4. Others]
The recording / reproducing functional layers such as the reflective layer, the recording layer, and the dielectric layer can be formed by any method, but are usually formed by a sputtering method or the like. In the sputtering method, it is possible to form a layer with an in-line device in which a target for a recording layer, a target for a dielectric layer, and, if necessary, a target for a reflective layer material are installed in the same vacuum chamber. This is desirable in terms of preventing It is also excellent in terms of productivity. In addition, when forming a layer with an organic dye or the like, the layer can be formed by a spin coating method or the like.

  By the way, in the optical recording medium of the present invention, a light transmission layer and an antifouling layer are provided on a medium having the substrate and the recording / reproducing functional layer as described above. Among such media, a blue laser is used. Next generation high density optical recording media are preferred. Accordingly, the wavelength of light used for recording and reproduction of the optical recording medium of the present invention is not limited and is arbitrary, but light having a wavelength of usually 350 nm or more, preferably 380 nm or more, and usually 800 nm or less, preferably 450 nm or less. It is desirable to form as an optical recording medium to be used.

[3. Light transmission layer]
The light transmission layer is a layer formed on the recording / reproducing functional layer in order to protect the recording / reproducing functional layer. In the optical recording medium of the present invention, the light transmission layer is formed by curing the composition A.
Here, the composition A contains silica particles (hereinafter sometimes referred to as “fine silica particles” as appropriate) and an oligomer having a urethane bond (hereinafter also referred to as “urethane oligomer” as appropriate). The composition can be cured by irradiation with radiation. Further, the composition A may appropriately contain other inorganic components (hereinafter sometimes referred to as “combined inorganic components” as appropriate).

[3-1. Fine silica particles]
The particle diameter of the fine silica particles contained in the composition A is arbitrary as long as the effects of the present invention are not significantly impaired. However, the lower limit of the number average particle size of the fine silica particles of the composition A is usually 0.5 nm or more, preferably 1 nm or more. If the number average particle size is too small, the cohesiveness of the fine silica particles, which are ultrafine particles, is extremely increased, and when the composition A is cured, the cured composition A, that is, the transparency of the light transmitting layer is transparent. There is a possibility that the properties and mechanical strength are extremely lowered, and the characteristics due to the quantum effect are not remarkable. Moreover, the upper limit of the number average particle diameter of the fine silica particles of the composition A is usually 50 nm or less, preferably 40 nm or less, more preferably 30 nm or less, further preferably 15 nm or less, and particularly preferably 12 nm or less.

  Further, in the composition A, it is desirable that the proportion of fine silica particles having a predetermined particle size be within a predetermined range. Specifically, among the fine silica particles of the composition A, the fine silica particles having a particle size of usually larger than 30 nm, preferably larger than 15 nm, are usually 1% by weight or less, preferably 0.8%. It is desirable that the amount be 5% by weight or less. Alternatively, it is desirable that the fine silica particles having a particle size in the same range is usually 1% by volume or less, preferably 0.5% by volume or less with respect to the light transmission layer. If the composition A contains a large amount of fine silica particles having a particle size in the above-mentioned predetermined range, light scattering increases, which is not preferable because the transmittance decreases.

  In addition, the numerical value measured from a transmission electron microscope (TEM) observation image is used for determination of said number average particle diameter. That is, the diameter of a circle having the same area as the observed fine silica particle image is defined as the particle size of the silica particle image. Using the particle size determined in this manner, the number average particle size is calculated by, for example, a known statistical processing method of image data. At this time, it is desirable that the number of ultrafine particle images (number of statistical processing data) used for the statistical processing is as large as possible. For example, in terms of reproducibility, the number of randomly selected fine silica particle images is usually 50 or more, preferably 80 or more, more preferably 100 or more. Moreover, calculation of the volume% of the fine silica particle which occupies in the hardened | cured composition A is converted with the volume of the ball | bowl which makes the particle diameter measured as mentioned above a diameter.

  By the way, the conventional ordinary silica particles generally have a broad particle size distribution and include particles having a particle size larger than 50 nm, for example, so that the transparency is often poor. Easy to settle. Although what isolate | separated the silica particle of a big particle size (what is called a cut product) is also known, they tend to aggregate easily and most of them are impaired in transparency.

On the other hand, the composition A contains fine silica particles.
Such fine silica particles are not particularly limited, and examples thereof include silica particles formed by hydrolysis of colloidal silica or an oligomer of alkoxysilane.

  First, colloidal silica will be described. Colloidal silica is usually in a state where ultrafine particles of silicic anhydride are dispersed in water or an organic solvent. Here, the primary particle diameter of colloidal silica is usually 1 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 80 nm or less. When the primary particle size of colloidal silica is below the lower limit of the above range, the silica component tends to gel during storage and production, and when the primary particle size exceeds the upper limit, the transparency of the light transmission layer tends to decrease. It is in.

  Moreover, as a specific example of the dispersion medium used for dispersion of the ultrafine particles of silicic anhydride, a known medium can be arbitrarily used, for example, water; methanol, ethanol, 2-propanol, n-propanol, 2-butanol. Alcohol solvents such as n-butanol; polyhydric alcohol solvents such as ethylene glycol; polyhydric alcohol derivatives such as ethyl cellosolve and butyl cellosolve; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and diacetone alcohol; 2-hydroxyethyl Examples thereof include monomers such as acrylate, 2-hydroxypropyl acrylate, and tetrahydrofurfuryl acrylate. Among these, alcohol solvents having 3 or less carbon atoms are particularly preferable. In addition, the said dispersion medium may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Colloidal silica can be produced by a known method, but is also commercially available.

  Next, silica particles formed by hydrolysis of an alkoxysilane oligomer will be described. According to a specific synthesis method of hydrolysis of an oligomer of alkoxysilane, fine silica particles having a very small particle diameter can be stably obtained, and the fine silica particles have a property of hardly aggregating. Therefore, if the silica particles obtained by this synthesis method are used as the fine silica particles of the composition A, there is an advantage that high transparency can be obtained even when the composition A is cured.

Here, the hydrolyzate refers to a product obtained by a reaction including at least a hydrolysis reaction, and may be accompanied by dehydration condensation, for example. The hydrolysis reaction includes a dealcoholization reaction.
Alkoxysilane is a compound in which an alkoxy group is bonded to a silicon atom, and these also generate alkoxysilane multimers (oligomers) by hydrolysis reaction and dehydration condensation reaction (or dealcoholization condensation). The type of alkoxysilane used for the raw material of the fine silica particles of composition A is not limited and is arbitrary. However, since the alkoxysilane oligomer is compatible with water and a solvent to be described later, The number of carbon atoms is preferably not too large, usually 1 or more, and usually 5 or less, preferably 3 or less. Specific examples of the alkoxysilane used as the raw material for the fine silica particles of the composition A include tetramethoxysilane and tetraethoxysilane.

  The fine silica particles of the composition A are usually obtained using the above alkoxysilane oligomer as a starting material. The reason why the alkoxysilane monomer (monomer) is not used as a starting material is that the control of the particle size of the alkoxysilane monomer is difficult and the particle size distribution tends to be broad and the particle size is difficult to be uniform. This is because there is a possibility that the composition A cannot be made transparent, and because there are some toxic types of alkoxysilane monomers, it is not preferable for safety and health.

As the alkoxysilane oligomer, an alkoxysilane oligomer produced by any known production method can be used. For example, the method described in JP-A-7-48454 can be used.
Furthermore, the alkoxysilane oligomer used as the raw material for the fine silica particles of the composition A is preferably compatible with the solvent and water used during hydrolysis. This is to prevent phase separation during the hydrolysis step.

Further, the molecular weight of the alkoxysilane oligomer used as a raw material for the fine silica particles is not limited and is arbitrary as long as the effects of the present invention are not significantly impaired. Usually, 100 or more, preferably 200 or more, more preferably 300 or more, Usually, it is 1500 or less, preferably 1200 or less, more preferably 1000 or less. If it is out of this range, it tends to cause white turbidity or gelation when forming fine silica particles.
In addition, the alkoxysilane oligomer used for a raw material may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

There are no restrictions on the method of hydrolysis of the alkoxysilane oligomer, and any method can be used. For example, a certain amount of water is added to the alkoxysilane oligomer in a specific solvent and a catalyst is allowed to act. it can. By this hydrolysis reaction, fine silica particles of the composition A can be obtained.
The solvent used for the hydrolysis is arbitrary as long as the alkoxysilane oligomer can be hydrolyzed. For example, one or two kinds of alcohols, glycol derivatives, hydrocarbons, esters, ketones, ethers and the like can be used. The above can be used in combination, and alcohols and ketones are particularly preferable among them.

Here, specific examples of alcohols include methanol, ethanol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, octanol, n-propyl alcohol, acetylacetone alcohol, and the like.
Specific examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone.
Furthermore, in order to make the fine silica particles that are hydrophilic stably exist, it is preferable that these alcohols and ketones have a small carbon number. Particularly preferred are methanol, ethanol and acetone. Among these, acetone has an advantage that the boiling point is low and the time required for the step of removing the solvent is relatively short.

  Moreover, there is no restriction | limiting in the quantity of the water used for the hydrolysis reaction of said alkoxysilane oligomer, As long as a hydrolysis is possible, it is arbitrary. However, it is desirable to use water having a mole number of usually 0.05 times or more, preferably 0.3 times or more, relative to the number of moles of the alkoxy group possessed by the alkoxysilane oligomer. If the amount of water is too small, the fine silica particles do not grow to a sufficient size, and therefore the fine silica particles tend not to exhibit the desired characteristics. However, the upper limit is usually 1 time or less. If the amount is too large, the alkoxysilane oligomer tends to form a gel.

  Moreover, there is no restriction | limiting in the catalyst used in the case of a hydrolysis, As long as the said hydrolysis is possible, arbitrary catalysts can be used. For example, a metal chelate compound, an organic acid, a metal alkoxide, a boron compound, or the like can be used. Of these, metal chelate compounds and organic acids are preferred. In addition, the catalyst used for a hydrolysis may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Specific examples of the metal chelate compound used as the catalyst include aluminum tris (acetylacetonate), titanium tetrakis (acetylacetonate), titanium bis (isopropoxy) bis (acetylacetonate), zirconium tetrakis (acetylacetonate), Zirconium bis (butoxy) bis (acetylacetonate), zirconium bis (isopropoxy) bis (acetylacetonate), and the like can be used, and one or more of these can be used in combination. Tris (acetylacetonate) is preferably used.

  Specific examples of the organic acid used as the catalyst include formic acid, acetic acid, propionic acid, maleic acid and the like. Among these, one or more kinds can be used in combination. Is preferably used. When maleic acid is used, there is an advantage that the hue of the light-transmitting layer obtained when the composition A is cured by radiation is good and the yellowing tends to be small, which is preferable.

  The amount of these catalyst components used is not particularly limited as long as the function is sufficiently exerted, but is usually 0.1 parts by weight or more, preferably 0.5 parts by weight with respect to 100 parts by weight of the alkoxysilane oligomer. It is desirable to use more than one part. However, since the action does not change even if it is too much, it is usually 10 parts by weight or less, preferably 5 parts by weight or less.

Furthermore, there is no restriction | limiting in the temperature conditions in the case of performing a hydrolysis, Although it is arbitrary as long as a hydrolysis advances, Usually, 10 degreeC or more, Preferably it is 30 degreeC or more, Usually, 90 degreeC or less, Preferably it is 70 degreeC or less. It is desirable to use temperature. If the lower limit of this range is not reached, the reaction for forming fine silica particles may not proceed sufficiently. Conversely, if the upper limit is exceeded, the gelation reaction of alkoxysilane oligomers may occur easily. .
Moreover, although there is no restriction | limiting in the hydrolysis time which performs a hydrolysis, Usually, it is 30 minutes to 1 week.

By the way, in the present invention, as silica particles used in the composition A, by using fine silica particles made of hydrolyzate of alkoxysilane oligomer, compared with silica particles generally used as a filling component in the past, There is an advantage that fine ultrafine particles having a uniform particle size can be contained in the light transmission layer. Further, since the fine silica particles made of the hydrolyzate of the above alkoxysilane oligomer also have the property of not easily agglomerated, the fine silica particles can be uniformly dispersed in the composition A, and consequently in the light transmitting layer. In this case, the fine silica particles can be uniformly dispersed. According to this, even if a large amount of fine silica particles are used, the radiation transmittance is not impaired, so that a sufficient amount of fine silica is sufficient to increase the dimensional stability and mechanical strength of the light transmission layer and the optical recording medium. Particles can be used. Furthermore, by using together the fine silica particles obtained by such a specific production method and the surface treatment of the fine silica particles with a silane coupling agent or the like described later, a larger amount of fine silica particles can be obtained by using a urethane oligomer. There is an advantage that can be dispersed without agglomerating.
Therefore, the light transmission layer using the above-mentioned fine silica particles has an advantage of having excellent properties having transparency, dimensional stability, mechanical strength, adhesion, and the like.

[3-2. Combined inorganic component]
In addition to the fine silica particles, the composition A can contain other inorganic components (combined inorganic components). There is no restriction | limiting in particular in a combined use inorganic component, In the range which does not impair the effect of this invention remarkably, arbitrary inorganic substances can be used. Examples of the combined inorganic component include colorless metals and colorless metal oxides. Specific examples include silver, palladium, alumina, zirconia, aluminum hydroxide, titanium oxide, zinc oxide, silica particles other than the fine silica particles described above, calcium carbonate, clay mineral powder, and the like. Among these, Alumina, zinc oxide, silica particles other than fine silica particles, and titanium oxide are preferable. In addition, a combined use inorganic component may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in particular as a manufacturing method of a combined use inorganic component, Arbitrary methods can be used. However, since it is preferable that the combined inorganic component has a small particle size, those produced through a method capable of reducing the particle size of the particles are preferable. Specific examples include a method of pulverizing a commercial product of a combined inorganic component with a pulverizer such as a ball mill; a method of manufacturing a combined inorganic component by a sol-gel method, and the like. Among these, those manufactured by a sol-gel method are preferable.

  The particle diameter of the combined inorganic component contained in the composition A is arbitrary as long as the effects of the present invention are not significantly impaired. Usually, as described above, the combined inorganic component may be ultrafine particles having a small particle diameter. preferable. The lower limit of the particle size of the combined inorganic component is the number average particle size, and is usually 0.5 nm or more, preferably 1 nm or more. If the number average particle size is too small, the cohesiveness of the ultrafine particles may be extremely increased, and the transparency and mechanical strength of the light transmission layer may be extremely decreased, or the characteristics due to the quantum effect may not be remarkable. The upper limit of the particle diameter of the combined inorganic component is a number average particle diameter, usually 50 nm or less, preferably 40 nm or less, more preferably 30 nm or less, still more preferably less than 15 nm, and particularly preferably 12 nm or less.

  Furthermore, in the composition A, it is desirable that the ratio of the combined inorganic component having a predetermined particle size falls within a predetermined range, as with the fine silica particles. Specifically, among the combined inorganic components in the composition A, the combined inorganic component having a particle size usually larger than 30 nm, preferably larger than 15 nm, is usually 1% by weight or less, preferably 0% with respect to the composition A. .5% by weight or less is desirable. Alternatively, the combined inorganic component having a particle size in the same range is usually 1% by volume or less, preferably 0.5% by volume or less, based on the light transmission layer. If the composition A contains a large amount of the combined inorganic component having a particle size in the above-mentioned predetermined range, light scattering increases, which is not preferable because the transmittance decreases. Examples of the method for determining these number average particle diameters include the same methods as described above.

[3-3. Composition of inorganic components]
In the composition A, the content of the entire inorganic component (hereinafter referred to as “dispersed inorganic component” as appropriate) including the fine silica particles and the combined inorganic component is to increase the dimensional stability and hardness characteristics of the light transmission layer. It is preferable to contain a large amount in the range that can be contained. Specifically, it is desirable that the dispersed inorganic component is contained in the composition A in an amount of usually 5% by weight or more, preferably 10% by weight or more. Alternatively, it is desirable to contain the dispersed inorganic component in an amount of usually 2% by volume or more, preferably 5% by volume or more with respect to the light transmission layer.

  However, in order to keep the transparency and mechanical strength of the light transmitting layer high, it is preferably not too much. The content of the dispersed inorganic component is usually 60% by weight or less, preferably 40% by weight with respect to the composition A. % Or less, more preferably 30% by weight or less. Alternatively, the content of the dispersed inorganic component is usually 30% by volume or less, preferably 20% by volume or less, more preferably 15% by volume or less with respect to the light transmission layer.

  Furthermore, the content of the fine silica particles in the dispersed inorganic component is not particularly limited and is arbitrary, but is usually 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, Usually 100% by weight or less.

[3-4. surface treatment]
It is preferable that the dispersed inorganic component including the above-described fine silica particles protects the particle surface by surface treatment, if necessary.
In general, the dispersed inorganic component, particularly the fine silica particles of the composition A formed as described above, has a strong polarity and is compatible with water, alcohol, etc., and may not be compatible with urethane oligomers. is there. For this reason, there is a possibility of causing aggregation or white turbidity when dispersed in a urethane oligomer.

Therefore, a surface treatment agent is used for the dispersed inorganic component, and the surface of the dispersed inorganic component particles is hydrophobized to make the dispersed inorganic component compatible with the urethane oligomer, thereby preventing aggregation and white turbidity. . In addition, as a surface treating agent used in this case, for example, one having a hydrophilic functional group and a hydrophobic functional group can be used, and specifically, a dispersant, a surfactant, a coupling agent or the like can be used. it can. In addition, a surface treating agent may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no limitation on the surface treatment method, and there is no other limitation as long as the above aggregation and white turbidity can be prevented. For example, the surface is modified with the use of the above-described dispersant or surfactant, or a coupling agent. And the like are preferably used.

As the dispersant, known ones can be arbitrarily used. For example, polymer dispersants used in fine particle dispersions such as various inks, paints, and electrophotographic toners can be selected and used. As such a polymer dispersant, an acrylic polymer dispersant, a urethane polymer dispersant and the like are appropriately selected and used. Specific examples include trade names such as EFKA (manufactured by Fuka Additives), Disperbyk (manufactured by BYK (BYK)), disparon (manufactured by Enomoto Kasei Co., Ltd.), and the like.
The amount of the dispersant used is arbitrary, but is usually 10% by weight or more, preferably 20% by weight or more, and usually 500% by weight or less, preferably 300% by weight or less based on the dispersed inorganic component.

Furthermore, known surfactants can be arbitrarily used, for example, selected from cationic, anionic, nonionic or amphoteric polymers or various non-aqueous surfactants of low molecular weight. be able to. Specific examples include sulfonic acid amides (Avesia Pigments & Additives "Solsperse 3000"), hydrostearic acid (Abesia Pigs & Additives "Solsperse 17000"), fatty acid amines, and ε-caprolactone. Examples include "Solsperse 24000" manufactured by Avecia Pigments & Additives, 1,2-hydroxystearic acid multimer, beef tallow diamine oleate ("Duomine TDO" manufactured by Lion Akzo), and the like.
The amount of the surfactant used is arbitrary, but is usually 10% by weight or more, preferably 20% by weight or more, and usually 500% by weight or less, preferably 300% by weight or less based on the dispersed inorganic component. .

  Furthermore, among the dispersed inorganic components, the fine silica particles are particularly preferably surface-treated with a silane coupling agent. A silane coupling agent is a compound having a structure in which an alkoxy group and an alkyl group having a functional group are bonded to a silicon atom, and has a role of hydrophobizing the surface of silica particles. That is, when surface treatment of fine silica particles is performed using a silane coupling agent, a dealcoholization reaction occurs between the alkoxy group of the silane coupling agent and the hydroxy group on the surface of the fine silica particle, and Si—O—Si. Will result in a bond.

  The silane coupling agent is not particularly limited as long as the purpose is achieved, and any silane coupling agent can be used, but trialkoxysilane having a radiation curable functional group is particularly preferable. Specific examples include epoxycyclohexylethyltrimethoxysilane, glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, acryloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, mercaptopropyltrimethoxysilane. And mercaptopropyltriethoxysilane.

  The amount of the silane coupling agent used is arbitrary as long as the above aggregation and white turbidity can be prevented, but usually 1% by weight or more, preferably 3% by weight or more, more preferably 5% by weight with respect to the fine silica particles. % Or more is desirable. If the amount of the silane coupling agent used is too small, the surface of the fine silica particles is not sufficiently hydrophobized, which may hinder uniform mixing with the urethane oligomer. On the other hand, if the amount is too large, a large amount of the silane coupling agent that does not bind to the fine silica particles will be mixed into the composition A, and this tends to adversely affect the transparency, mechanical properties, etc. of the resulting light-transmitting layer. Therefore, the upper limit of the amount of the silica coupling agent used is usually 400% by weight or less, preferably 350% by weight or less, more preferably 300% by weight or less.

  Furthermore, the silane coupling agent may be partially hydrolyzed during the surface treatment. Therefore, when the fine silica particles are surface-treated with a silane coupling agent, the resulting composition A is a silane coupling agent, a hydrolysis product of the silane coupling agent, and a condensate thereof. May contain fine silica particles that have been surface treated with a selected compound. In addition, there may be a condensate of silane coupling agents and / or a silane coupling agent and a hydrolysis product thereof.

The hydrolysis product of the silane coupling agent means that a part or all of the alkoxysilane group contained in the silane coupling agent undergoes a hydrolysis reaction to become a silanol group, and part or all of the silane coupling agent is Refers to hydroxysilane. For example, when the silane coupling agent is epoxycyclohexylethyltrimethoxysilane, it may be epoxycyclohexylethylhydroxydimethoxysilane, epoxycyclohexylethyldihydroxymethoxysilane, or epoxycyclohexylethyltrihydroxysilane.
The silane coupling agents and / or the condensate of the silane coupling agent and its hydrolysis product are those in which an alkoxy group undergoes a dealcoholization reaction with a silanol group, or a Si-O-Si bond, or This refers to a silanol group that has undergone a dehydration reaction with another silanol group to form a Si—O—Si bond.

The surface treatment agent mentioned above can perform the surface treatment of the dispersed inorganic component by using the method according to the type and purpose of each surface treatment agent.
For example, when a surfactant or dispersant is used as the surface treatment agent, a liquid medium in which fine silica particles are dispersed and the surface treatment agent are mixed, and the temperature is from room temperature to 60 ° C. for about 30 minutes to 2 hours. Examples thereof include a method of stirring and reacting, a method of mixing and reacting, and aging for several days at room temperature. When mixing, it is preferable not to select a solvent having a very high solubility of the surface treatment agent as the liquid medium. This is because when a solvent having a very high solubility of the surface treatment agent is used, the dispersion inorganic component is not sufficiently protected, or the protection process may take a long time. In addition, when a solvent having a very high solubility of the surface treatment agent is used for the liquid medium, for example, a solvent having a difference in solubility value (SP value) between the solvent and the surface treatment agent of 0.5 or more is used. In many cases, the protection to the dispersed inorganic component is sufficiently performed.

  For example, when a silane coupling agent is used as the surface treatment agent, the surface treatment reaction is usually allowed to proceed at room temperature (25 ° C.). Usually, the stirring operation is performed for 0.5 to 24 hours to allow the reaction to proceed, but heating may be performed at a temperature of 100 ° C. or lower. When heated, the reaction rate increases and the reaction can be carried out in a shorter time. Furthermore, when a silane coupling agent is used, water may be mixed. Usually, it is desirable that water is mixed in the range of the amount necessary for hydrolysis of the alkoxy group derived from the silane coupling agent and the remaining alkoxy group derived from the alkoxysilane.

Furthermore, the silane coupling agent may be mixed once, or may be divided and mixed twice or more. When the silane coupling agent is divided and mixed twice or more, water may be divided and mixed twice or more, and the amount is described in the amount of water used for the silane coupling agent. It is the same as the description.
However, when surface treatment is performed using a silane coupling agent, before mixing the dispersed inorganic component and the urethane oligomer, mixing the dispersed inorganic component and the urethane oligomer after the surface treatment is sufficiently completed. It is preferable to do so. This is because if the dispersed inorganic component and the urethane oligomer are mixed before the surface treatment sufficiently proceeds, the urethane oligomer may not be mixed uniformly or the composition A may become cloudy in the subsequent steps. In addition, confirmation that the surface treatment using the silane coupling agent has been sufficiently completed can be performed by measuring the residual amount of the silane coupling agent in the reaction solution on which the surface treatment is performed. Usually, when the remaining amount of the silane coupling agent in the reaction solution becomes 10% or less with respect to the charged amount, it can be determined that the reaction in the surface treatment step has been sufficiently completed.

[3-5. Urethane oligomer]
The urethane oligomer contained in the composition A is not particularly limited as long as it is an oligomer of an organic compound having a urethane bond, and any oligomer can be used. Here, by including the urethane oligomer in the composition A, there is an advantage that the adhesion and the surface curing degree of the light transmission layer formed by curing the composition A are increased.

The phenomenon that the adhesion to the adherend (usually the recording / reproducing functional layer) is improved when the urethane oligomer is used is derived from the fact that the electrical polarity of the urethane bond enhances the interaction with the adherend. Conceivable.
The reason why the degree of surface hardening is improved when urethane oligomer is used is not clear, but in composition A containing a certain amount or more of urethane oligomer, an intramolecular hydrogen bond derived from the electrical polarity of the urethane bond And the intermolecular hydrogen bond is easily formed, so that the agglomeration property of the oligomer is enhanced, and as a result, the free movement of oxygen in the composition A is inhibited and the radical polymerization inhibition is suppressed. It is estimated that this is the reason.

  Further, as the urethane oligomer, the urethane oligomer itself preferably has a radiation curable functional group. As a result, the urethane oligomer is integrated into the radiation-cured network structure, so that the composition A becomes more cohesive when the composition A is cured by irradiation with radiation, and as a result, it aggregates in the light transmission layer. There is an advantage that breakage hardly occurs and the adhesion of the light transmission layer is improved. In addition, since the effect of limiting the free movement of oxygen is enhanced, there is an advantage that the degree of surface hardening of the light transmission layer is improved.

  The urethane oligomer can be produced by any known method, but is usually produced by oligomerizing a monomer having a urethane bond. The method for producing the monomer having a urethane bond is arbitrary. For example, a method of reacting chloroformate with ammonia or amine, a method of reacting isocyanate with a hydroxyl group-containing compound, or reacting urea with a hydroxyl group-containing compound. The method may be performed according to a known method.

  Furthermore, when the monomer has a reactive group, a urethane oligomer can be obtained by oligomerizing the monomer. Usually, a urethane oligomer can be produced by subjecting a compound having two or more isocyanate groups in the molecule and a compound containing a hydroxyl group to an addition reaction by a conventional method.

  Examples of the compound having two or more isocyanate groups in the molecule include tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, isophorone diisocyanate, And polyisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, naphthalene diisocyanate.

  Among these, it is preferable to use bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, isophorone diisocyanate, and the like because the hue of the resulting composition is good. In addition, the compound which has an isocyanate group may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  Moreover, as the compound containing a hydroxyl group, polyols containing two or more hydroxyl groups are preferably used. Specific examples thereof include alkyl polyols such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, trimethylol propane, pentaerythritol, sorbitol, mannitol, and glycerin, and polyether polyols that are multimers thereof, or these polyols. And polyester polyols such as polyester polyols synthesized from polyhydric alcohols and polybasic acids, and polycaprolactone polyols. In addition, the compound containing a hydroxyl group may also be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  Furthermore, it is desirable that the urethane oligomer obtained by these contains the polyether polyol as a compound containing a hydroxyl group. Specifically, it is desirable that the average content of the structural units derived from the polyether polyol in one molecule of the urethane oligomer is usually 20% by weight or more, preferably 25% by weight or more, more preferably 30% by weight or more. . The upper limit is not particularly limited, but it is usually 90% by weight or less, preferably 80% by weight or less, and more preferably 70% by weight or less.

If the content ratio of this polyether polyol is too small, the light transmission layer becomes brittle as a cured product, and the elastic modulus of the light transmission layer is too high, and internal stress tends to occur, which tends to cause deformation. On the other hand, if it is too large, the surface hardness of the light transmission layer as a cured product tends to decrease, and problems such as easy scratching tend to occur.
Moreover, the addition reaction of an isocyanate compound and a hydroxyl compound can be performed by any known method. For example, it can be carried out by dropping a mixture of a hydroxyl compound and an addition reaction catalyst, specifically, dibutyltin laurate, in the presence of an isocyanate compound under conditions of 50 ° C to 90 ° C.

  In particular, when synthesizing a urethane acrylate oligomer, it can be produced by making a part of the hydroxyl group-containing compound a compound having both a hydroxyl group and a (meth) acryloyl group. The amount used is arbitrary, but it is usually 30 mol% to 70 mol% in the total hydroxyl group-containing compound, and the molecular weight of the resulting oligomer can be controlled according to the ratio.

  Specific examples of the compound having both a hydroxyl group and a (meth) acryloyl group include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, glycidyl ether compound and (meth) acrylic acid, Addition reaction products, mono (meth) acrylates of glycol compounds, and the like.

Furthermore, urethane having (meth) acryloyl groups at both ends by addition reaction of one compound having two or more isocyanate groups in the molecule and two compounds having both a hydroxyl group and a (meth) acryloyl group. Oligomers can be produced.
In particular, a urethane oligomer having (meth) acryloyl groups at both ends has an advantage that the adhesion and surface curing degree of the obtained light transmission layer are further increased.

  Moreover, it is preferable that the urethane oligomer further has an arbitrary acidic group. By having an acidic group, there is an advantage that the adhesion between the adherend and the light transmission layer can be improved over time (that is, even when time passes). Here, the acidic group means a functional group having acidity. Examples of acidic groups include sulfonic acid groups, phosphoric acid groups, carboxyl groups, and tertiary amine compound neutralized salts or metal salts thereof. Of these, a carboxyl group is most preferred. In addition, the acidic group which a urethane oligomer has may be 1 type, and 2 or more types may exist by arbitrary combinations and a ratio.

  When making a urethane oligomer have an acidic group, what has only to have a carboxyl group as a raw material compound used for the manufacturing method of a urethane oligomer may be used, for example. In particular, among these, it is preferable to use a hydroxyl group-containing compound having a carboxyl group as a raw material compound.

  There is no limitation on the hydroxyl group-containing compound having a carboxyl group, and any compound can be used. For example, so-called acid diols containing two or more hydroxyl groups are preferably used. Specific examples thereof include dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutanoic acid, dimethylolheptanoic acid, dimethylolnonanoic acid, dihydroxybenzoic acid, and other alkanol carboxylic acids and their caprolactone adducts; or polyoxy Examples thereof include compounds having two hydroxyl groups and a carboxyl group in one molecule, such as a half ester compound of propylene triol and maleic anhydride or phthalic anhydride.

Moreover, there is no restriction | limiting in the molecular weight of a urethane oligomer, Although it is arbitrary unless the effect of this invention is impaired remarkably, Usually, 500 or more, Preferably it is 1000 or more, More preferably, it is 1500 or more, Moreover, it is usually 10000 or less, Preferably it is 8000 or less. More preferably, 6000 or less is desirable. If the lower limit of this range is not reached, curing shrinkage may increase, and if it exceeds, the viscosity will increase significantly and workability may be deteriorated.
In addition, a urethane oligomer may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

[3-6. Other ingredients]
In the composition A, other components may be appropriately contained.
For example, a radiation curable monomer and / or an oligomer thereof (hereinafter appropriately referred to as “radiation curable component”) may be contained. By using this radiation-curable component, even if the urethane oligomer does not have radiation curability, the composition A can be provided with radiation curability and the composition A can be cured by irradiation with radiation. become able to.
Of the radiation curable components, it is preferable to use a bifunctional or trifunctional (meth) acrylate compound.

As the above-mentioned bifunctional or trifunctional (meth) acrylate compound, any compound can be used. For example, alicyclic poly (meth) acrylate, alicyclic poly (meth) acrylate, aromatic poly (meta) ) Acrylates. Specific examples include triethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, 2,2-bis [4- (meth) acryloyloxyphenyl] propane, 2,2-bis [4- (2- (Meth) acryloyloxyethoxy) phenyl] propane, bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane = dimethacrylate, p-bis [β- (meth) acryloyloxyethylthio] xylylene, Divalent (meth) acrylates such as 4,4′-bis [β- (meth) acryloyloxyethylthio] diphenylsulfone, trimethylolpropane tris (meth) acrylate, glycerin tris (meth) acrylate, pentaerythritol tris ( Trivalent (meth) acrylates such as (meth) acrylate Tetravalent (meth) acrylates such as pentaerythritol tetrakis (meth) acrylate, indeterminate polyvalent (meth) acrylates such as epoxy acrylate and the like. Of these, the divalent (meth) acrylates are preferably used because of the controllability of the cross-linking reaction.

In addition, trifunctional or higher functional (meth) acrylates are preferably used for the purpose of improving the heat resistance of the cross-linked structure of the light transmission layer and the surface hardness. Specific examples thereof include trifunctional (meth) acrylates having an isocyanurate skeleton as well as trimethylolpropane tris (meth) acrylate exemplified above.
Furthermore, a (meth) acrylate compound containing a hydroxyl group is preferably used for the purpose of improving the adhesion and adhesion of the light transmission layer. Specific examples thereof include hydroxyethyl (meth) acrylate.

Further, among the (meth) acrylates exemplified above, it is particularly preferable to use the following component I and the following component II in that the transparency of the light transmission layer and the low optical distortion property are realized in a balanced manner. is there.
Component I is a bis (meth) acrylate having an alicyclic skeleton represented by the following formula (1).

ただし、上記式（１）において、Ｒ^a及びＲ^bは、それぞれ独立して、水素原子又はメチル基を表わす。また、Ｒ^c及びＲ^dは、それぞれ独立して、炭素数６以下のアルキレン基を表わす。さらに、ｘは１又は２を表わし、ｙは０又は１を表わす。

However, in the above formula (1), R ^a and R ^b each independently represent a hydrogen atom or a methyl group. R ^c and R ^d each independently represents an alkylene group having 6 or less carbon atoms. Further, x represents 1 or 2, and y represents 0 or 1.

Specific examples of component I represented by the above formula (1) include bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane = diacrylate, bis (hydroxymethyl) tricyclo [5.2. 1.0 ^2,6] decane = dimethacrylate, bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6] decane = acrylate methacrylate and mixtures thereof, bis (hydroxymethyl) pentacyclo [6.5. 1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] pentadecane diacrylate, bis (hydroxymethyl) pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] pentadecane = dimethacrylate, bis (hydroxymethyl) pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . ^0,13 ] pentadecane = acrylate methacrylate and mixtures thereof. In addition, these components I may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  On the other hand, Component II is bis (meth) acrylate having a sulfur atom represented by the following formula (2).

However, in the above formula (2), R ^a and R ^b are the same as R ^a and R ^b in each of the above formula (1).
Each R ^e independently represents an alkylene group having 1 to 6 carbon atoms.
Further, each Ar independently represents an arylene group or an aralkylene group having 6 to 30 carbon atoms. Note that each Ar hydrogen atom may be independently substituted with a halogen atom other than a fluorine atom.

Each X ¹ independently represents an oxygen atom or a sulfur atom.
Further, when each X ¹ is an oxygen atom, X ² represents a sulfur atom or a sulfone group (—SO ₂ —). On the other hand, when at least ^one of each X ¹ is a sulfur atom, X ² is a sulfur atom, a sulfone group, a carbonyl group (—CO—), and an alkylene group having 1 to 12 carbon atoms, an aralkylene group, an alkylene ether group, It represents one of an aralkylene ether group, an alkylene thioether group and an aralkylene thioether group.
J and p each independently represent an integer of 1 to 5, and k represents an integer of 0 to 10. When k is 0, X ¹ represents a sulfur atom.

  Specific examples of component II represented by the above formula (2) include α, α′-bis [β- (meth) acryloyloxyethylthio] -p-xylene, α, α′-bis [β- (meth). [Acryloyloxyethylthio] -m-xylene, [alpha], [alpha] '-bis [[beta]-(meth) acryloyloxyethylthio] -2,3,5,6-tetrachloro-p-xylene, 4,4'-bis [ β- (meth) acryloyloxyethoxy] diphenyl sulfide, 4,4′-bis [β- (meth) acryloyloxyethoxy] diphenylsulfone, 4,4′-bis [β- (meth) acryloyloxyethylthio] diphenyl sulfide 4,4′-bis [β- (meth) acryloyloxyethylthio] diphenyl sulfone, 4,4′-bis [β- (meth) acryloyloxyethylthio] dipheni Ketone, 2,4′-bis [β- (meth) acryloyloxyethylthio] diphenyl ketone, 5,5′-tetrabromodiphenyl ketone, β, β′-bis [p- (meth) acryloyloxyphenylthio] diethyl And ether, β, β′-bis [p- (meth) acryloyloxyphenylthio] diethylthioether, and the like. In addition, these component II may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Among the radiation-curable components described above, bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane = dimethacrylate has excellent transparency and heat resistance and is particularly preferably used.
In addition, a radiation curable component may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Further, the amount of the radiation curable component used is arbitrary as long as the effects of the present invention are not significantly impaired, but a composition other than the dispersed inorganic component in the composition A, that is, dispersed silica particles, a combined inorganic component and its surface. The amount is usually 50% by weight or less, preferably 30% by weight or less, relative to other components other than the treatment agent.

  Further, for example, the composition A may contain a reactive diluent for the purpose of adjusting the composition viscosity. The reactive diluent is a low viscosity liquid compound, and is usually a monofunctional low molecular compound. There is no restriction | limiting in a reactive diluent, Although arbitrary things can be used unless the effect of this invention is impaired remarkably, For example, the compound which has a vinyl group or a (meth) acryloyl group, mercaptans, etc. are mentioned.

  However, as the reactive diluent, those having radiation curability are preferable, and for example, a compound having a vinyl group or a (meth) acryloyl group is preferable. Specific examples of such compounds include aromatic vinyl monomers, vinyl ester monomers, vinyl ethers, (meth) acrylamides, (meth) acrylic esters, di (meth) acrylates, A compound having a structure having no aromatic ring is preferable in terms of hue and light transmittance. Among them, (meth) acryloylmorpholine, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylate having an alicyclic skeleton such as (meth) acrylate having a tricyclodecane skeleton, (Meth) acrylamides such as N, N-dimethylacrylamide, aliphatic (meth) acrylates such as hexanediol di (meth) acrylate, neopentylglycol di (meth) acrylate, etc. have good hue and viscosity, Particularly preferably used.

A compound having both a hydroxyl group such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and a (meth) acryloyl group can also be used for this purpose. These are preferable because the adhesion of the light transmission layer to the adherend may be improved.
In addition, a reactive diluent may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Further, the amount of the reactive diluent used is arbitrary as long as the effects of the present invention are not significantly impaired, but the composition other than the dispersed inorganic component in the composition A, that is, the dispersed silica particles, the combined inorganic component and the surface thereof. It is usually 0.5% by weight or more, preferably 1% by weight or more, and usually 80% by weight or less, preferably 50% by weight or less with respect to other components other than the treatment agent. If the amount is too small, the dilution effect may be reduced. On the other hand, if the amount is too large, the light-transmitting layer tends to become brittle, and the mechanical strength tends to be lowered.

  Furthermore, in order to initiate the polymerization reaction that proceeds with active energy rays (for example, ultraviolet rays), the composition A usually preferably contains a polymerization initiator. As such a polymerization initiator, a radical generator which is a compound having a property of generating radicals by light is generally used, and there is no limitation on the polymerization initiator, and a known one can be arbitrarily used.

Examples of the radical generator include benzophenone, benzoin methyl ether, benzoin isopropyl ether, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2,6-dimethylbenzoyl diphenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenyl. Examples include phosphine oxide. Of these, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzophenone, and the like are preferable.
In addition, a polymerization initiator may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

The amount of the polymerization initiator used is arbitrary as long as the composition A can be cured, but is usually 0.001 with respect to 100 parts by weight of the total of the monomers containing radiation curable functional groups and / or oligomers thereof. Part by weight or more, preferably 0.01 part by weight or more, more preferably 0.05 part by weight or more. However, it is usually 10 parts by weight or less, preferably 8 parts by weight or less. If the amount used is too large, the polymerization reaction may proceed rapidly, leading to an increase in optical distortion in the light transmission layer, and the hue of the light transmission layer may be deteriorated. On the other hand, if the amount is too small, the composition A may not be sufficiently cured.
In addition, when starting a polymerization reaction with an electron beam, although the said polymerization initiator can also be used, it is preferable not to use a polymerization initiator.

[3-7. Method for forming light transmission layer]
[3-7-1. Preparation of Composition A]
The light transmission layer is formed by curing the composition A containing at least fine silica particles and a urethane oligomer. At this time, the composition A is first prepared, but the method for preparing the composition A is not limited, and any method can be used as long as the dispersed inorganic component can be uniformly dispersed in the urethane oligomer. Specific examples of the method include the following methods.
(1) A method of preparing a fine silica particle powder, subjecting it to an appropriate surface treatment, and then directly dispersing it in a suitably liquid urethane oligomer.
(2) A method of synthesizing fine silica particles in a suitably liquid urethane oligomer.
(3) A method of preparing fine silica particles in a liquid medium, dissolving a urethane oligomer in the liquid medium, and then removing the solvent from the liquid medium.
(4) A method in which a urethane oligomer is dissolved in a liquid medium, fine silica particles are prepared in the liquid medium, and then the solvent is removed from the liquid medium.
(5) A method of removing the solvent from the liquid medium after preparing the fine silica particles and the urethane oligomer in the liquid medium.

Among the methods for preparing the composition A, the method (3) is most preferable because it is easy to obtain a product having high transparency and good storage stability.
Furthermore, in the above method (3), specifically, (a) a step of hydrolyzing an alkoxysilane oligomer in a liquid medium such as a solvent, a surface treatment agent or a diluent to synthesize fine silica particles; It is preferable to sequentially perform the step of b) surface-treating the fine silica particles, (c) the step of mixing the urethane oligomer and the fine silica particles, and (d) the step of removing the solvent. According to this production method, a radiation curable resin composition in which fine silica particles having a uniform particle size are highly dispersed can be more easily obtained as the composition A.

Hereinafter, each step of the method (3) will be described in more detail.
In the step (a), alkoxysilane oligomers are hydrolyzed in the presence of an alkoxysilane oligomer, a catalyst and water in a liquid medium to synthesize fine silica particles.
The liquid medium is not particularly limited, but is preferably compatible with the urethane oligomer. Specifically, the above-described solvent, surface treatment agent, diluent or the like is used. Among them, in the method (3), alcohols or ketones are preferably used as the solvent, and alcohols having 1 to 4 carbon atoms, acetone, methyl ethyl ketone, or methyl isobutyl ketone are particularly preferably used. In the method (3), the amount of the liquid medium is preferably 0.3 to 10 times that of the alkoxysilane oligomer.

Further, the same catalyst as described above is used as the catalyst. Among them, in the method (3), usually, organic acids such as formic acid and maleic acid; inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid; and metal complex compounds such as acetylacetone aluminum, dibutyltin dilaurate and diztiltin dioctate The hydrolysis catalyst is used. The amount of the catalyst used is preferably 0.1 to 3% by weight based on the oligomer of alkoxysilane.
Furthermore, in the method (3), water is usually used in an amount of 10 to 50% by weight based on the alkoxysilane oligomer.

  Next, in the step (b), the fine silica particles are surface-treated. Although the specific method of surface treatment is arbitrary, it can usually carry out using a surface treating agent similarly to what was mentioned above as surface treatment of a dispersed inorganic component. Accordingly, examples of the surface treatment agent include surfactants, dispersants, silane coupling agents, and the like.

Next, in the step (c), the urethane oligomer and the fine silica particles are mixed. However, as described above, when the surface treatment is performed using the silane coupling agent in the step (b), the step (c) is performed after the reaction in the step (b) is sufficiently completed. It is preferable. Moreover, it can confirm that reaction of the process of (b) is fully complete | finished by measuring the residual amount of the silane coupling agent in a reaction liquid. Usually, when the remaining amount of the silane coupling agent in the reaction solution becomes 10% or less with respect to the charged amount, it can be determined that the reaction in the step (b) has been sufficiently completed.
Furthermore, the step (c) can be performed at room temperature (25 ° C.). However, when the viscosity of the urethane oligomer is high or when the melting point of the urethane oligomer is room temperature (25 ° C.) or more, the temperature is 30 to 90 ° C. You may carry out by heating. The mixing time is usually preferably 30 minutes to 5 hours.

  Next, in the step (d), removal of a solvent such as a solvent mainly used as a liquid medium or an alcohol generated by hydrolysis of an alkoxysilane oligomer is performed. However, it may be removed within a necessary range, and may not necessarily be completely removed, and it is preferably removed so as not to substantially contain a solvent. Here, “substantially containing no solvent” means a state in which the content of a so-called organic solvent having volatility or a low boiling point is very low, and the solvent content in the composition A is usually 5% by weight. Hereinafter, it is preferably 3% by weight or less, more preferably 1% by weight or less, and still more preferably 0.1% by weight or less. For simplicity, it means a state in which no odor of the organic solvent is observed.

As another method, the composition A is spin-coated with a film thickness of 100 ± 15 μm, heated at 70 ° C. for 1 minute, then irradiated with ³ J / cm ² of ultraviolet rays or 5 Mrads of electron beam, or the surface hardening described later. After curing to a state where the evaluation by the degree evaluation method becomes ◯, bubbles or white turbidity due to volatilization of the solvent remaining in the light transmission layer as a cured product does not occur.
Surface curing degree evaluation method: after irradiating the composition A with a specified amount of ultraviolet light, the sample was lightly sandwiched with the right index finger and thumb wearing rubber gloves so that the thumb was on the application surface side, and the thumb was separated from the application surface When the trace is not visually observed, ◯, when thin is observed Δ, when densely observed, ×.

Further, when removing the solvent, the removal is usually performed by drying the solvent under a temperature condition in the range of 10 ° C to 75 ° C. If the temperature is lower than the lower limit of this range, the solvent may not be sufficiently removed, which is not preferable. Conversely, when it is higher than the upper limit, the composition A is easily gelled, which is not preferable. The temperature may be controlled step by step.
Further, the solvent removal time is preferably 1 to 12 hours.
Moreover, it is preferable that the pressure conditions at the time of solvent removal are 20 kPa or less, More preferably, it removes by pressure reduction of 10 kPa or less. Furthermore, it is preferable to remove at 0.1 kPa or more. Further, the pressure may be gradually reduced.

  According to the preferred preparation method described above, compared with a method of adding a surface treatment agent such as a filler (micro silica particles) or a silane coupling agent to the resin composition (urethane oligomer, etc.) and dispersing the filler later. Thus, there is an advantage that ultrafine particles having a smaller particle diameter can be dispersed in a large amount without agglomeration. Therefore, the composition A, which is a radiation curable resin composition, is obtained by dispersing a sufficient amount of fine silica particles to increase the dimensional stability and mechanical strength of the resin without impairing the radiation transmission. It becomes. And the light transmissive layer which is a radiation hardened | cured material obtained by hardening it has transparency, high surface hardness, and low cure shrinkage. In addition, there is an advantage in that it has both dimensional stability and adhesion, and more preferably has a degree of surface hardening.

[3-7-2. Application of Composition A]
The composition A prepared as described above is applied directly on the recording / reproducing functional layer or, if another layer is formed on the recording / reproducing functional layer, through the other layer, and then applied. By being cured, a light transmission layer is formed. At this time, there is no limitation on the coating method of the composition A, and the coating can be performed by an arbitrary method as long as the composition A can be formed with a predetermined thickness in accordance with the thickness of the target light transmitting layer. it can.

Specific examples of the coating method include spin coating, dip coating, roll coating, bar coating, die coating, and spray coating.
In this case, the thickness of the layer of the applied composition A is not limited, but is usually 10 μm or more, preferably 50 μm or more, more preferably 80 μm or more, and usually 1 mm or less, preferably 0.5 mm or less, more Preferably it is 0.3 mm or less. The thickness of the applied layer is usually substantially the same as the thickness of the light-transmitting layer after curing, or about 2% thick in consideration of curing shrinkage.
Furthermore, the coating may be performed once or may be performed in two or more times. However, it is usually more economical and preferable to perform the coating once.

[3-7-3. Curing of Composition A]
The composition A applied on the recording / reproducing functional layer is cured to form a light transmission layer. When the composition A is cured, so-called “radiation curing” is performed in which the composition A is irradiated with radiation (active energy rays or electron beams) to initiate a polymerization reaction of monomers and oligomers in the composition A.

  As long as the composition A can be cured by radiation curing, specific procedures and conditions for radiation curing are arbitrary. Therefore, there is no restriction | limiting in the form of the polymerization reaction at the time of radiation curing, For example, arbitrary well-known polymerization forms, such as radical polymerization, anionic polymerization, cationic polymerization, and coordination polymerization, can be used. Among these polymerization modes, the most preferable polymerization mode is radical polymerization. The reason for this is not clear, but it is presumed to be due to the homogeneity of the product due to the initiation of the polymerization reaction being homogeneous and proceeding in a short time within the polymerization system.

The radiation is an electromagnetic wave (gamma ray, X-ray, ultraviolet ray, visible ray, infrared ray, microwave, etc.) that acts on a polymerization initiator that initiates a necessary polymerization reaction to generate a chemical species that initiates the polymerization reaction. ) Or particle beam (electron beam, α-ray, neutron beam, various atomic beams, etc.).
For example, as an example of preferably used radiation, ultraviolet rays, visible rays, and electron beams are preferable, and ultraviolet rays and electron beams are more preferable because energy and a general-purpose light source can be used.

  In the case of using ultraviolet rays, a method is usually employed in which a photo radical generator that generates radicals by ultraviolet rays is used as a polymerization initiator and ultraviolet rays are used as radiation. Here, as the photoradical generator, a known compound called a photopolymerization initiator or a photoinitiator can be arbitrarily used. Specific examples of the photo radical generator include, for example, benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoyl benzoate, 4-phenylbenzophenone, thioxanthone, diethylthioxanthone, Isopropylthioxanthone, chlorothioxanthone, t-butylanthraquinone, 2-ethylanthraquinone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin methyl Ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-methyl-1- [4- (methylthio) phenyl]- -Morpholinoprop-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6- And trimethylbenzoyl) -phenylphosphine oxide, methylbenzoylformate and the like. In addition, a photo radical generator may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Furthermore, when the composition A is used for an optical recording medium or the like using a laser having a wavelength of 380 nm to 800 nm as a light source, the laser light necessary for reading can pass through the light transmission layer in which the composition A is sufficiently cured. Thus, it is preferable to select and use the type and amount of the photoradical generator as appropriate. In this case, it is particularly preferable to use a short-wavelength photosensitive photoradical generator as the photoradical generator, in which the obtained light transmission layer hardly absorbs laser light. Specific examples of the short wavelength photosensitive type photo radical generator include, for example, benzophenone, 2,4,6-trimethylbenzophenone, methylorthobenzoylbenzoate, 4-phenylbenzophenone, diethoxyacetophenone, 2-hydroxy-2-methyl Examples include -1-phenylpropan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and methyl benzoyl formate. In addition, these may also be used individually by 1 type and may use 2 or more types together by arbitrary combinations and ratios.

  In composition A, the content of the photoradical generator is not limited and is arbitrary as long as the effects of the present invention are not significantly impaired. Excluding dispersed silica particles, combined inorganic component and surface treatment agent in composition A Usually 0.001 parts by weight or more, preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and usually 10 parts by weight or less, preferably 100 parts by weight or more of the total amount of other components. 9 parts by weight or less, more preferably 7 parts by weight or less is desirable. If the content of the photo radical generator is below the lower limit of the above range, the mechanical properties of the composition A tend to be insufficient, and if it exceeds the upper limit, the radiation curability of the film of the composition A may be poor. This is because the light transmission layer tends to be colored and information reading using light tends to be poor.

  At this time, you may use a sensitizer together as needed. There is no restriction | limiting in a sensitizer and a well-known sensitizer can be used arbitrarily. Specific examples of the sensitizer include methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, amyl 4-dimethylaminobenzoate, 4-dimethylaminoacetophenone and the like. In addition, a sensitizer may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  Furthermore, the ultraviolet rays having a wavelength in the range of usually 200 to 400 nm, preferably 250 to 400 nm can be used. As an apparatus for irradiating ultraviolet rays, any known apparatus such as a high-pressure mercury lamp, a metal halide lamp, or an ultraviolet lamp having a structure for generating ultraviolet rays by microwaves can be preferably used. A high-pressure mercury lamp is preferable. The output of the apparatus is usually 10 to 200 W / cm. When the apparatus is installed at a distance of 5 to 80 cm with respect to the irradiated object, light deterioration, thermal deterioration, thermal deformation, etc. of the irradiated object are caused. Less and preferred.

  Further, the composition A can be preferably cured by an electron beam, and a cured product having excellent mechanical properties, particularly tensile elongation properties, can be obtained. When an electron beam is used, the light source and irradiation device are expensive, but are preferably used because the use of an initiator can be omitted and the polymerization is not inhibited by oxygen, and therefore the degree of surface hardening is good. There is a case. The electron beam irradiation apparatus used for the electron beam irradiation is not particularly limited, and any apparatus can be used. Examples thereof include a curtain type, an area beam type, a broad beam type, and a pulse beam type. Furthermore, the acceleration voltage at the time of electron beam irradiation is usually preferably 10 to 1000 kV.

Furthermore, the intensity of the radiation to be irradiated during the radiation curing is optional so long as capable of curing the composition A, usually 0.1 J / cm ² or more, preferably that irradiated with 0.2 J / cm ² or more energy desirable. The irradiation is usually performed at an energy range of 20 J / cm ² or less, preferably 10 J / cm ² or less, more preferably 5 J / cm ² or less, further preferably 3 J / cm ² or less, and particularly preferably ² J / cm ² or less. Is desirable. If the intensity of the radiation is within this range, it can be appropriately selected depending on the type of the composition A. For example, when the composition A is a radiation curable resin composition containing a urethane bond and a monomer having a urethane bond or a hydroxyalkylene group and / or an oligomer thereof, the radiation irradiation intensity is ² J / cm ² or less. preferable. When the irradiation energy and irradiation time of such radiation are extremely small, the polymerization is incomplete, and the heat resistance and mechanical properties of the light transmission layer may not be sufficiently exhibited.

The irradiation time of the radiation is arbitrary as long as the composition A can be cured, but is usually 1 second or longer, preferably 10 seconds or longer. However, if it is extremely excessive, on the other hand, deterioration such as hue deterioration due to light such as yellowing may occur. Therefore, the irradiation time is usually 3 hours or less, and preferably about 1 hour or less in terms of reaction acceleration and productivity.
Furthermore, the irradiation of radiation may be performed in one step, or may be performed in two or more steps. As the radiation source, a diffusion radiation source in which radiation spreads in all directions is usually used.

[3-8. Physical properties of light transmission layer]
The light-transmitting layer formed as described above usually exhibits insoluble and infusible properties in a solvent or the like, and has properties that are advantageous for the use of optical members even when it is thickened. It is preferable that the temperature is excellent. Specifically, it is preferable to exhibit low optical distortion (low birefringence), high light transmittance, dimensional stability, high adhesion, high degree of surface curing, and a certain level of heat resistance. Further, the smaller the curing shrinkage, the better.

This will be described in more detail.
The thickness of the light transmission layer is not limited and can be arbitrarily set, but is usually 5 mm or less, preferably 2 mm or less, more preferably 1 mm or less, further preferably 500 μm or less, and usually 0.1 μm or more, The thickness is preferably 1 μm or more, more preferably 10 μm or more, further preferably 50 μm or more, particularly preferably 70 μm or more, and most preferably 90 μm or more.

  Furthermore, the transparency of the light transmission layer is optional within a range not contrary to the spirit of the present invention, but the light transmittance per optical path length of 0.1 mm at 550 nm is usually 80% or more, preferably 85% or more, More preferably it is 89% or more. More desirably, the light transmittance per optical path length of 0.1 mm at 400 nm is usually 80% or more, preferably 85% or more, more preferably 89% or more. Particularly preferably, those having the light transmittance per 1 mm of the optical path length are preferable. The upper limit of the light transmittance is ideally 100%. The light transmittance may be measured at room temperature using, for example, an HP8453 ultraviolet / visible absorptiometer manufactured by Hewlett-Packard Company.

  The surface hardness of the light transmission layer is also arbitrary, but the surface hardness according to the pencil hardness test in accordance with JIS K5400 is preferably 2B or more. Furthermore, it is preferably HB or more, more preferably F or more, and further preferably H or more. Moreover, it is preferable that it is 7H or less. In this case, the light transmission layer preferably satisfies the above hardness even if it is a cured product on an inorganic substrate such as glass or metal or a resin substrate, and more preferably cured on a plastic substrate such as polycarbonate. The cured product preferably satisfies the above hardness. If the hardness is too small, it is not preferable because the surface is easily scratched. Although there is no problem with the hardness being too large, the light transmission layer tends to become brittle, and cracks and peeling tend to occur.

  Furthermore, the curing shrinkage when the composition A is cured to form the light transmission layer is preferably as small as possible, and is usually 3% by volume or less, preferably 2% by volume or less. The measurement of cure shrinkage is generally replaced by a method in which the composition A is applied on a substrate and the amount of concave warpage generated after curing is measured. Specifically, a film of the composition A having a thickness of 100 ± 15 μm was formed on a circular polycarbonate plate having a diameter of 130 mm and a thickness of 1.2 ± 0.2 mm using a spin coater, After irradiating with radiation, leave it on the surface plate for 1 hour. After standing, the concave warpage of the polycarbonate plate caused by the curing shrinkage of the composition A is measured. The concave warp is preferably 1 mm or less, more preferably 0.5 mm or less, and still more preferably 0.1 mm or less. The lower limit value of the concave warp is ideally 0 mm. The “concave warp” refers to the amount of warpage from the surface plate observed when the polycarbonate plate warps as the composition A formed on the polycarbonate plate shrinks by curing. The measurement of “concave warpage” may be obtained by measuring the warpage amount at a plurality of points on the polycarbonate plate and averaging the measured values.

Moreover, although the magnitude | size of the thermal expansion of a light transmissive layer is also arbitrary, it means that it has better dimensional stability, so that thermal expansion is small. For example, the light transmission layer preferably has a smaller linear expansion coefficient, which is one of the specific indicators of thermal expansion, and is usually 13 × 10 ⁻⁵ / ° C. or less, preferably 12 × 10 ⁻⁵ / ° C. or less, more preferably 10 × 10 ⁻⁵ / ° C. or less, more preferably 8 × 10 ⁻⁵ / ° C. or less is desirable. However, the lower limit value of the thermal expansion coefficient is actually about 2 × 10 ⁻⁵ / ° C. The linear expansion coefficient is, for example, a weight of 1 g by a compression method thermomechanical measurement (TMA; SSC / 5200 type; manufactured by Seiko Instruments Inc.) using a plate-shaped test piece of 5 mm × 5 mm × 1 mm. It can be measured at a rate of 10 ° C./min, the linear expansion coefficient can be evaluated in increments of 10 ° C. in the range from 40 ° C. to 100 ° C., and the average value can be used as the representative value.

  In addition, the adhesiveness of the light transmission layer is preferably higher. In addition, the adhesiveness is measured by, for example, hanging a composition A in an amount capable of forming a coating on a 10 cm square optically polished glass plate, irradiating a prescribed amount of radiation, and then allowing to stand at room temperature for 1 hour. A cut is made in the center of the cured composition A part with a cutter knife so as to reach the glass surface, and after standing for another 14 days at room temperature, a cured product of composition A (corresponding to the light transmission layer) in the cut part and the glass surface It can be evaluated by whether or not peeling at the interface with the substrate is visually observed. When the number of samples is 5 and no peeling is observed for all the samples, ◎ when no peeling is observed for two or more samples, ○ when no peeling is observed for only one sample, Δ, all The case where peeling was visually observed for the sample of can be evaluated as x. The degree of adhesion is preferably ◯ or ◎, and more preferably ◎. Further, a plastic substrate such as polycarbonate having the above adhesiveness is more preferable than on the optically polished glass plate.

  In addition, it is preferable that the light transmissive layer has a hard surface. To measure the degree of surface hardening, after irradiating a specified amount of ultraviolet light, the sample is lightly sandwiched between the right index finger and thumb wearing rubber gloves so that the thumb is on the application surface side, and the thumb is separated from the application surface. When the trace is not visually observed, it is measured as ◯, when it is observed as thin, Δ, when it is observed as dark. The surface hardness is preferably ◯.

Regarding the heat resistance of the light transmission layer, the glass transition temperature measured by differential thermal analysis (DSC), thermomechanical measurement (TMA) or dynamic viscoelasticity measurement of the cured resin is usually 120 ° C. or higher, preferably It is desirable that the temperature be 150 ° C. or higher, more preferably 170 ° C. or higher. However, the glass transition point is practically 200 ° C. or lower.
Furthermore, it is preferable that the light transmission layer does not dissolve in various solvents. Typically, it is preferable not to dissolve in a solvent such as toluene, chloroform, acetone, or tetrahydrofuran.

[4. Antifouling layer]
The antifouling layer is a layer formed on the light transmission layer in order to prevent dirt from adhering to the optical recording medium. Further, the antifouling layer preferably has antifouling properties and lubricating functionality, that is, water repellency and oil repellency. Therefore, in the optical recording medium of the present invention, the antifouling layer is formed containing component B.
Here, the component B is an alkoxysilane compound containing a fluorine atom (hereinafter appropriately referred to as “fluorine-containing alkoxysilane compound”) and / or a hydrolysis product of the fluorine-containing alkoxysilane compound.

[4-1. Component B]
As described above, component B is a fluorine-containing alkoxysilane compound and / or a hydrolysis product of the fluorine-containing alkoxysilane compound.
Here, the fluorine-containing alkoxysilane compound is not particularly limited, and any known one can be used, and examples thereof include a silane coupling agent containing a fluoroalkyl group or a fluoroaryl group.

  Among the silane coupling agents having a fluoroalkyl group, alkoxysilanes having a fluoroalkyl group having 3 to 12 carbon atoms are preferred. Specific examples include (3,3,3-trifluoropropyl) triethoxysilane, (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, and (heptadecafluoro-1,1,2). , 2-Tetrahydrodecyl) triethoxysilane, (Henicosafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane, and multimers of these compounds, or these compounds and other alkoxysilane compounds and / or Or the modified body etc. which condensed the hydroxyl-containing compound are mentioned.

  Moreover, in the silane coupling agent which has a fluoroaryl group, the alkoxysilane which has a C6-C9 fluoroaryl group is preferable. Specific examples include pentafluorophenyltriethoxysilane, (pentafluorophenyl) propyltriethoxysilane, multimers of these compounds, or these compounds and other alkoxysilane compounds and / or hydroxyl group-containing compounds. Examples include condensed modified products.

Commercially available products include OPTOOL DSX (manufactured by Daikin Industries), Fluorosurf FS-1000 series, FS-2000 series, FG-3000 series, FG-4000 series, and FG-5000 series (more from Fluoro Technology). , Novec EGC-1720 (manufactured by Sumitomo 3M Limited) and the like. Among these, OPTOOL DSX, FG-5010 and Novec EGC-1720 in the fluorosurf FG-5000 series are preferable, and Novec EGC-1720 is most preferable.
In addition, a fluorine-containing alkoxysilane compound may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Furthermore, as the component B, a hydrolyzate of a fluorine-containing alkoxysilane compound may be used instead of the fluorine-containing alkoxysilane compound or together with the fluorine-containing alkoxysilane compound. Usually, a fluorine-containing alkoxysilane compound produces | generates a hydroxyl group by a hydrolysis reaction with water. This hydroxyl group often has high reactivity. Therefore, the antifouling layer using the hydrolyzate can enhance the adhesion to the light transmission layer.

  There is no limit to the water required for the hydrolysis reaction of the fluorine-containing alkoxysilane compound, and other than normal tap water, pure water, ion-exchanged water, etc., a water composition such as a hydrated compound may be mixed, Water in the air may be used. When hydrolysis is performed using water in the air, the hydrolysis reaction proceeds slowly.

  A catalyst may be used for hydrolysis of the fluorine-containing alkoxysilane compound. Although there is no restriction | limiting in the catalyst used for this hydrolysis and arbitrary things can be used, For example, catalyst components, such as a metal chelate compound, an organic acid, a metal alkoxide, a boron compound, can be used. In addition, these catalyst components may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Furthermore, these catalyst components may coexist with the fluorine-containing alkoxysilane compound immediately before hydrolysis, or may coexist with a small amount of water in advance to advance a desired hydrolysis reaction.

  The amount of these catalyst components used is not particularly limited as long as the function is sufficiently exerted, but is usually 0.1 parts by weight or more, preferably 0.8 parts per 100 parts by weight of the alkoxysilane oligomer. It is desirable to use 5 parts by weight or more. However, since the action does not change even if it is too much, it is usually 10 parts by weight or less, preferably 5 parts by weight or less.

  In addition to the above component B and solvent, the antifouling layer may contain an optional additive. There is no restriction | limiting in the additive used with component B, Although it is arbitrary in the range which does not impair the effect of this invention remarkably, For example, the other compound containing a fluorine atom, a silicone compound, etc. can be used.

Before forming the antifouling layer, component B and the additive used as appropriate are usually a composition dissolved or dispersed in a solvent (hereinafter referred to as “coating composition” as appropriate). This is because a coating method is usually used when forming the antifouling layer.
There is no restriction | limiting in the solvent used for the composition for application | coating, Although it is arbitrary unless the effect of this invention is impaired remarkably, Usually, it is preferable to use a halogenated organic solvent, and especially a fluorine-type solvent is especially preferable. Specific commercial products of preferred solvents include Fluorinate FC-87, Fluorinate FC-72, Fluorinate FC-84, Fluorinate FC-77, Fluorinate FC-3283, Fluorinate FC-40, Fluorinate FC-43, Fluorinate FC-70. HFE-7100, HFE-7200 (manufactured by Sumitomo 3M), Asahi Clin AK-225, Asahi Clin AK-225AES, Asahi Clin AE-3000, Asahi Clin AE-3100E, Clin Dry, Clin Dry α Manufactured) and the like. Among these, Fluorinert FC-3283 and Fluorinert FC-40 are most preferable in that the boiling point is in the range of 80 to 170 ° C., the evaporation rate is appropriate, and the spreadability is good.

Furthermore, the composition of the component B and the coating composition is arbitrary as long as the effects of the present invention are not significantly impaired.
However, the solid content in the coating composition, that is, the weight ratio of the fluorine-containing alkoxysilane compound and / or its hydrolysis product, and the solid additive used as appropriate is usually 0.01% by weight or more, preferably Is 0.05% by weight or more, more preferably 0.07% by weight or more, and usually 1% by weight or less, preferably 0.5% by weight or less, more preferably 0.2% by weight. If it falls below the lower limit of this range, the antifouling layer may be peeled off and the antifouling property may be remarkably reduced. If the upper limit is exceeded, the applicability is remarkably lowered or the effect does not change even when used at an appropriate concentration or more. May decrease.

[4-2. Formation of antifouling layer]
There is no restriction | limiting in the formation method of a pollution protection layer, Arbitrary methods can be used if the layer containing a fluorine-containing alkoxysilane compound and / or its hydrolysis product can be formed. For example, a coating composition containing component B, a solvent, and additives used as appropriate is prepared, and the coating composition is formed on the above-described light-transmitting layer directly or on the light-transmitting layer. If it is, the antifouling layer containing the component B can be formed by coating through the other layer and drying the solvent.

When applying the coating composition, the coating method is not limited, and any known method such as a spin coating method, a dip coating method, or a spray coating method can be used.
Moreover, the drying method is also arbitrary. For example, heating may be performed at a temperature of 30 ° C. to 100 ° C., but drying may be performed at room temperature. For example, the drying time is preferably 1 day, more preferably 3 days. By sufficiently drying, the antifouling property and the adhesion between the light transmission layer can be improved.

[4-3. Physical properties of antifouling layer]
The antifouling layer formed by containing the component B is excellent in antifouling property and adhesion, so that it is possible to prevent dirt from adhering to the optical recording medium of the present invention, and the above light transmission When the antifouling layer is provided on the layer, the adhesion of the antifouling layer to the light transmissive layer can be very high.

The antifouling property can be quantitatively evaluated by a pure water contact angle, a hexadecane contact angle, or the like.
The pure water contact angle of the antifouling layer is usually 85 degrees or more, preferably 95 degrees or more, more preferably 100 degrees or more. On the other hand, the upper limit of the pure water contact angle is practically 150 degrees.
Further, the hexadecane contact angle of the antifouling layer is usually 40 degrees or more, preferably 50 degrees or more, more preferably 60 degrees or more. On the other hand, the upper limit of the hexadecane contact angle is practically 150 degrees.

  Furthermore, as one of the antifouling properties, it is preferable that the antifouling layer is difficult to attach a fingerprint and the fingerprint is not conspicuous. Quantitatively, for example, when the fingertip is pressed against the surface of the antifouling layer by applying a nasal oil to the thumb and then observed using an optical microscope, the observed oil droplets are preferably 30 μm. Hereinafter, when the thickness is more preferably 10 μm or less, it can be evaluated that the fingerprint is hardly attached and is not noticeable. Ideally, the oil droplet is 0 μm, that is, no oil droplet is observed.

  On the other hand, the adhesion of the antifouling layer can be evaluated by examining the magic repellency. Specifically, it can be evaluated by a magic test. For example, when using a magic pen (Mitsubishi PIN-03A) and writing on the antifouling layer surface with normal strength (0.05 MPa to 0.1 MPa), it is evaluated that the adhesion is good when the magic repels. it can. If the adhesion is poor, writing with magic will cause the antifouling layer to peel off due to the shearing stress and prevent the magic from repelling.

  Further, there is no limitation on the film thickness of the antifouling layer, and it is optional as long as the effects of the present invention are not significantly impaired. Usually, it is 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 100 nm or less, more preferably Is 50 nm or less. If the lower limit of this range is not reached, there is a possibility that the antifouling property may be uneven, and if the upper limit is exceeded, the antifouling layer may be easily peeled off.

  Further, the antifouling layer preferably has a high transmittance for light used for recording and reproduction of the optical recording medium of the present invention. For example, the transmittance for light having a wavelength of 550 nm is usually 85% or more, preferably 89% or more. The upper limit of the transmittance is ideally 100%.

The antifouling layer usually contains the solvent used in forming the antifouling layer. Usually, the solvent contained in the coating composition cannot be removed even after drying and remains in the antifouling layer. Therefore, for example, when a halogen organic solvent is used as the solvent of the coating composition, the organic solvent is also contained in the antifouling layer.
However, the proportion of the organic solvent in the antifouling layer is usually preferably as low as possible. Specifically, the weight proportion of the solvent in the antifouling layer is usually 30% by weight or less, preferably 10% by weight or less, more preferably It is desirable to be 5% by weight or less. However, the lower limit of the organic solvent is actually 100 ppm. In this specification, ppm represents a ratio based on weight.

[5. Other layers]
The optical recording medium of the present invention may be provided with another layer. Further, the position at which the optical recording medium is formed is arbitrary, and the optical recording medium can be formed at an appropriate position according to the type, purpose, application, and the like of the optical recording medium.
However, the antifouling layer is preferably the outermost layer of the optical recording medium. This is to more reliably prevent the adhesion of dirt.
Further, the light transmission layer is preferably provided directly on the recording / reproducing functional layer, and the antifouling layer is preferably provided directly on the light transmission layer. This is to increase the adhesion of each layer.

  In the so-called Blu-ray disc, the total film thickness including the light transmission layer and the antifouling layer is about 100 μm. It is preferable to adjust about 10 μm around 100 μm in consideration of the refractive index of these layers. Further, the thickness of the light transmission layer is preferably 80% or more of the total thickness, and more preferably 90% or more. On the other hand, the film thickness of the antifouling layer is preferably 0.1% or more, more preferably 1% or more of the total film thickness. The film thickness of the antifouling layer is usually 20% or less, preferably less than 20%, more preferably 10% or less, and particularly preferably less than 10% of the total film thickness.

[6. Effect]
The optical recording medium of the present invention configured as described above contains component A, that is, silica particles and an oligomer having a urethane bond, in the optical recording medium having a substrate and a recording / reproducing functional layer, and is irradiated with radiation. A light-transmitting layer obtained by curing the composition A that can be cured by the above, and a component B, that is, an alkoxysilane compound containing a fluorine atom, and / or an antifouling layer containing a hydrolysis product of the alkoxysilane compound Therefore, sufficient antifouling properties can be provided. Furthermore, since the light transmission layer can be manufactured by applying the composition A and irradiating and curing the composition A, the light transmission layer is easy to manufacture, and the adhesion of the light transmission layer to the recording / reproducing functional layer, etc. Can be increased.

Hereinafter, the advantages of the present invention will be described in detail in comparison with the prior art.
For example, the conventional protective layer proposed in Patent Document 2 does not have sufficient antifouling properties. Even if a fluorine-based compound is added to the composition described in Patent Document 2, sufficient antifouling properties could not be imparted to the optical recording medium. However, the optical recording medium of the present invention has sufficient antifouling properties.

  Further, for example, in the technique of Patent Document 1, since the layer formed on the surface of the optical recording medium has a three-layer structure, the cost is high, the workability is inferior, and the practicality is poor. However, in the optical recording medium of the present invention, the function performed in the three-layer configuration in Patent Document 1 including antifouling property can be performed in two layers of the light transmission layer and the antifouling layer. It can be produced in a simple and industrially advantageous manner.

In the optical recording medium of the present invention, since the light transmission layer is formed by radiation curing using a urethane oligomer, the adhesion between the light transmission layer and the recording / reproducing layer can be improved.
Furthermore, when the dispersed inorganic component is not dispersed in the light transmitting layer (the top layer in Patent Document 1) as in the prior art, the adhesion between the light transmitting layer and the antifouling layer containing the inorganic component may be reduced. When the antifouling layer of the optical recording medium of the present invention is formed directly on the surface of the light transmission layer, the adhesion between the antifouling layer and the light transmission layer can be improved.
Conventionally, cracks and warping have occurred when the thickness of the light transmission layer (for example, the anchor layer of Patent Document 1) is increased. However, in the optical recording medium of the present invention, the light transmission layer is composed of a urethane oligomer and a dispersed inorganic component. Therefore, it is also possible to suppress the occurrence of cracks and warpage as in the prior art.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and may be arbitrarily modified and implemented without departing from the gist of the present invention. Can do.

[Evaluation methods]
(Anti-fouling test)
Using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd .: CA-DT type), the contact angle of pure water and the hexadecane contact angle were evaluated.
(Adhesion test)
Using a magic pen (Mitsubishi PIN-03A), a straight line having a length of 2 cm was drawn on the antifouling layer surface with a free hand with a strength of 0.05 MPa. A case where magic repelling was observed was marked as ◯, and a case where magic repelling was not observed was marked as x.

[Preparation]
(A) Preparation of tetramethoxysilane oligomer After mixing 1170 g of tetramethoxysilane which is alkoxysilane and 370 g of methanol, 111 g of 0.05% hydrochloric acid was added, and a hydrolysis reaction was performed at 65 ° C. for 2 hours.
Next, the temperature inside the system was raised to 130 ° C., and the produced methanol was removed. Then, the temperature was gradually raised to 150 ° C. while blowing nitrogen gas, and the tetramethoxysilane monomer was removed by keeping it for 3 hours. An oligomer of methoxysilane was obtained.

(B) Preparation of silica sol After adding 225.3 g of methanol to 122.7 g of the tetramethoxysilane oligomer obtained in the above step (a) and stirring uniformly, 24.6 g of 5% methanol solution of acetylacetone aluminum was added. And stirred for 30 minutes. 26.0 g of demineralized water was gradually added dropwise to this solution while stirring, and the mixture was stirred at 60 ° C. for 2 hours to grow fine silica particles.
Next, 119.6 g of acryloxypropyltrimethoxysilane and 4.0 parts of maleic acid are added as a silane coupling agent (surface treatment agent), and after stirring and aging at 60 ° C. for 2 hours, 53.5 g of demineralized water and acryloxy are added. 119.6 g of propyltrimethoxysilane was gradually added, and the mixture was stirred at 60 ° C. for 4 hours. The surface of the fine silica particles was reacted with a silane coupling agent to prepare a silica sol.

(C) Synthesis of urethane acrylate oligomer 222.3 g of isophorone diisocyanate and 0.06 g of dibutyltin laurate are placed in a 2 L four-necked flask and heated to 70-80 ° C. in an oil bath until the temperature becomes constant. Was stirred. When the temperature became constant, a mixture of 29.6 g of dimethylolbutanoic acid and 255.0 g of polytetramethylene glycol was added dropwise with a dropping funnel, and the mixture was stirred for 2 hours while maintaining the temperature at 80 ° C. After the temperature was lowered to 70 ° C., a mixture of 145.0 g of hydroxyethyl acrylate and 0.3 g of methoquinone was added dropwise using a dropping funnel, and when the addition was completed, the temperature was maintained at 80 ° C. and stirred for 10 hours. An acrylate oligomer was synthesized. Immediately after the synthesis, 217.4 g of isobornyl acrylate was added and stirred to prepare a urethane resin composition.

(D) Preparation of silica-containing composition for light transmission layer (component A) In a 500 cc eggplant flask, 79.7 g of silica sol prepared in step (b) and 53 urethane resin composition prepared in step (c) were added. .2 g, and as a radiation curing component, polypropylene glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd .: APG400: molecular weight of about 500) 10.6 g (10% by weight of the total resin components) and isobornyl acrylate 31. 9 g and 10.6 g of hydroxyethyl acrylate, and 2.5 g of 1-hydroxycyclohexyl phenyl ketone and 2.5 g of benzophenone as photo radical generators, respectively, were stirred at room temperature for 2 hours. A transparent radiation curable resin composition was obtained. Further, this radiation curable resin composition was evaporated at 50 ° C. under reduced pressure for 1 hour to remove low-boiling components contained in the radiation curable resin composition, and as component A, a silica-containing composition for a light transmission layer Was prepared.

(E) Preparation of silica-free composition for forming light transmission layer 53.2 g of the urethane resin composition prepared in the above step (c), and polypropylene glycol diacrylate (Shin Nakamura Chemical Co., Ltd.) as a radiation curing component Co., Ltd .: APG400: molecular weight of about 500) 10.6 g (10% by weight of the total resin component), isobornyl acrylate 31.9 g, hydroxyethyl acrylate 10.6 g, and photo radical generator Then, 2.5 g of 1-hydroxycyclohexyl phenyl ketone and 2.5 g of benzophenone were added and stirred at room temperature for 2 hours to prepare a silica-free composition for a light transmitting layer.

(F) Preparation of antifouling layer composition α Novec EGC1720 (manufactured by Sumitomo 3M; solid concentration 0.1% by weight) was defined as antifouling layer composition α. The solid content of Novec EGC 1720 is component B.

(G) Preparation of antifouling layer composition β In a flask, 0.5 g of OPTOOL DSX (manufactured by Daikin Industries; solid concentration 20% by weight) and 10 g of FC-3283 (manufactured by Sumitomo 3M) as a solvent were added. The antifouling layer composition β (solid content: 0.1% by weight) was prepared by weighing and stirring for 30 minutes at room temperature using a magnetic stirrer. The solid content of OPTOOL DSX is component B.

[Example 1]
On a circular polycarbonate substrate having a diameter of 130 mm and a thickness of 1.2 mm, the silica-containing composition for light transmission layer (component A) prepared in the step (d) at a thickness of 100 ± 15 microns using a spin coater. The composition is cured by applying ultraviolet light for 15 seconds (irradiation intensity is 1 J / cm ² ) with a high-pressure mercury lamp with an output of 80 W / cm installed at a distance of 15 cm from the composition film, and the light is transmitted. A layer was formed.

After leaving at room temperature for 1 hour, the anti-staining layer composition α (coating composition containing component B) prepared in the step (f) was applied at 1000 rpm × 10 seconds using a spin coater, The laminate was allowed to stand at room temperature for 3 days and dried to form an antifouling layer, thereby producing an optical recording medium-like laminate.
The antifouling test and adhesion test of the antifouling layer of the resulting optical recording medium-like laminate were conducted. The results are shown in Table 1.

[Example 2]
Optical recording was carried out in the same manner as in Example 1 except that the anti-stain layer composition β (coating composition containing component B) prepared in the step (g) was used instead of the anti-soil layer composition α. A medium-like laminate was produced.
The antifouling test and adhesion test of the antifouling layer of the resulting optical recording medium-like laminate were conducted. The results are shown in Table 1.

[Comparative Example 1]
An optical recording medium-like laminate was produced in the same manner as in Example 1, except that the silica-free composition for light transmissive layer prepared in step (e) was used instead of the silica-containing composition for light transmissive layer. .
The antifouling test and adhesion test of the antifouling layer of the resulting optical recording medium-like laminate were conducted. The results are shown in Table 1.

[Comparative Example 2]
An optical recording medium-like laminate was produced in the same manner as in Example 1 except that the antifouling layer was not formed.
The antifouling test and adhesion test of the antifouling layer of the resulting optical recording medium-like laminate were conducted. The results are shown in Table 1.

When Examples 1 and 2 are compared with Comparative Example 2, it can be seen that the optical recording medium-like laminates of Examples 1 and 2 have far better antifouling properties than those of Comparative Example 2. Thereby, it was confirmed that the optical recording medium-like laminated body provided with the light transmission layer which hardened the composition A, and the antifouling layer containing the component B was excellent in antifouling property.
Further, when Examples 1 and 2 are compared with Comparative Example 1, the optical recording medium-like laminates of Examples 1 and 2 are superior in adhesion of the antifouling layer to those of Comparative Example 1. I understand. Thereby, it was confirmed that the optical recording medium-like laminate including the light transmissive layer obtained by curing the composition A and the antifouling layer containing the component B has excellent adhesion of the antifouling layer to the light transmissive layer. It was.

  The present invention can be widely used in any field related to an optical recording medium. In particular, it is particularly suitable for use in CD, CD-R, CD-RW, DVD, blue laser compatible optical recording media and the like.

Claims (9)

A substrate,
A recording / reproducing functional layer formed on the substrate;
A light-transmitting layer formed on the recording / reproducing functional layer and cured by the following component A;
An optical recording medium comprising an antifouling layer formed on the light transmission layer and containing the following component B.
Component A: A composition containing silica particles and an oligomer having a urethane bond, which can be cured by irradiation with radiation.
Component B: An alkoxysilane compound containing a fluorine atom and / or a hydrolysis product of the alkoxysilane compound. 2. The optical recording medium according to claim 1, wherein the silica particles contained in the component A are silica particles comprising colloidal silica or a hydrolyzate of an alkoxysilane oligomer. The optical recording medium according to claim 1, wherein the silica particles contained in the component A have a number average particle diameter of 0.5 nm or more and 50 nm or less. The optical recording medium according to any one of claims 1 to 3, wherein the silica particles contained in the component A are surface-treated with a silane coupling agent. The alkoxysilane compound containing a fluorine atom contained in the component B is a silane coupling agent containing a fluoroalkyl group or a fluoroaryl group. An optical recording medium according to 1. A method for producing an optical recording medium according to any one of claims 1 to 5,
Curing the component A on the recording / reproducing functional layer to form the light transmission layer;
Applying the composition containing the component B and the solvent on the light transmission layer and having a solid content of 0.01% by weight or more and 1% by weight or less and drying to form the antifouling layer. A method for manufacturing an optical recording medium. Preparing the component A by preparing the silica particles in a liquid medium containing a solvent, dissolving the oligomer having a urethane bond in the liquid medium, and then removing the solvent from the liquid medium. The method of manufacturing an optical recording medium according to claim 6, comprising: 8. The optical recording medium according to claim 6, wherein the solid content contains an alkoxysilane compound containing a fluorine atom and / or a hydrolysis product of the alkoxysilane compound. Method. The method for producing an optical recording medium according to claim 6, wherein the solvent is a halogen-based organic solvent.