JP2010225186A - Active energy ray curing composition for optical recording medium, cured material, and laminated body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy ray curing composition for an optical recording medium which provides a laminated body suitable for the optical recording medium by reducing deformation right after a rapid change in environmental temperature or environmental humidity and having sufficient surface hardness, thereby having excellent wear resistance and recording film protection performance. <P>SOLUTION: When the active energy ray curing composition for an optical recording medium is used for the protection layer of a specific laminated body, the composition has the laminated body having specific properties with respect to (1) the surface hardness and (2) the displacement amount of the curvature caused by change in temperature, or having specific properties with respect to (3) the surface hardness and (4) the displacement amount of the curvature caused by change in humidity. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an active energy ray-curable composition for optical recording media containing a monomer and / or oligomer having an active energy ray-curable group, a cured product obtained by irradiating the composition with active energy rays, and a cured product comprising the same The present invention relates to a laminate having a film.

  In recent years, optical information recording media such as read-only optical discs and optical recording discs have been widely used as information recording media for recording or storing vast amounts of information such as moving image information. As one of them, for example, a high-density type optical disc (so-called Blu-ray disc, hereinafter sometimes referred to as “Blu-ray disc”) using a laser beam having a wavelength of 400 nm has been proposed (see Patent Document 1). The Blu-ray Disc is an optical recording medium having a resin substrate, a recording / reproducing functional layer, a protective layer, and a hard coat layer in this order. The hard coat layer is required to have scratch resistance and hardness. On the other hand, the entire disk is required to be able to read and write information stably even if the environment such as temperature and humidity changes. For example, after storing for a certain period of time under high temperature and high humidity, after returning to room temperature One of the required performances is that the deformation of the disk after a certain period of time is small, and among them, it is important to reduce the warpage of the disk that particularly affects the reading and writing of information.

  On the other hand, Patent Document 2 discloses urethane (Metal) as an active energy ray-curable composition that is excellent in transparency, abrasion resistance, recording film protection, and mechanical properties, and also excellent in heat resistance and moisture deformation resistance. ) An active energy ray-curable composition containing an acrylate is disclosed, and an optical recording medium using the active energy ray-curable composition has been proposed. In Patent Document 2, it is reported that the optical recording medium is less deformed after being stored at high temperature and high humidity for a long time and then returned to room temperature and stored for a long time.

  Further, Patent Document 3 proposes a radiation curable composition that has excellent transparency and mechanical strength, and can give a cured product having an excellent balance between surface hardness and heat and moisture resistance. In Patent Document 3, when the laminate of the cured layer of the radiation curable composition and the resin substrate is stored for a long time under high temperature and high humidity and then returned to room temperature and stored for a long time, the laminate is not deformed. Less reported.

Japanese Patent Laid-Open No. 11-273147 JP 2003-263780 A JP 2006-152289 A

  However, the optical recording medium described in Patent Document 2 has insufficient surface hardness, inferior surface wear resistance, and an object having an uneven shape is pressed against the surface of the cured product, resulting in local stress. When loaded, there is a problem such as poor load resistance, such that the surface thereof is plastically deformed to leave uneven marks (hereinafter sometimes referred to as load marks). On the other hand, when the surface hardness is increased, deformation of the optical recording medium due to environmental changes may increase and warp may occur, and the laminate may be deformed so as to be excellent in both surface hardness and warpage suppression of the optical recording medium. It is necessary to improve the surface hardness while suppressing.

  Furthermore, the present inventors have found that even if the deformation of the optical recording medium or the laminate is small when the temperature is returned from room temperature to room temperature as in the compositions described in Patent Documents 2 and 3, the environmental temperature is low. Warp tends to occur immediately after an abrupt change in environmental humidity, particularly in a low temperature range, or in a relatively low temperature environment such as room temperature or low temperature (for example, 5 ° C.). The problem that it was difficult to suppress was found.

  The present invention has been made in view of the above problems. That is, the object of the present invention is when a change in humidity occurs immediately after the environmental temperature or humidity changes abruptly, particularly in a low temperature region or in a relatively low temperature environment such as room temperature or low temperature (eg 5 ° C.). It is an object of the present invention to provide an active energy ray-curable composition for an optical recording medium which gives a laminate having a small amount of warpage, a sufficient surface hardness and excellent wear resistance and load resistance. In particular, it is an object of the present invention to provide an active energy ray-curable composition for an optical recording medium, which has high recording film protection in an optical recording medium and is suitable for forming a protective layer.

  In addition, an object of the present invention is to provide a cured product obtained by curing such a composition, and a laminate suitable for an optical recording medium, in which a cured film made of the cured product is laminated on a substrate. To do.

  As a result of intensive studies to achieve the above object, the present inventor has found that an active energy ray-curable composition for optical recording media that satisfies specific characteristics when a laminate is obtained is cured to form a laminate. In this case, the present invention has found that there is little deformation immediately after the rapid change in environmental temperature and humidity, and that the laminate has a sufficient surface hardness and excellent wear resistance and load scar resistance. It came to.

That is, the present invention is an active energy ray-curable composition for an optical recording medium containing a monomer having an active energy ray-curable group and / or an oligomer thereof, a circular polycarbonate plate having a thickness of 1.1 mm and a diameter of 120 mm, A high pressure mercury lamp having an irradiance of 400 mW / cm ² at a wavelength of 254 nm under a condition of an oxygen concentration of 20% is applied to a coating film made of the active energy ray-curable composition for an optical recording medium and having a thickness of 100 ± 10 μm. A protective layer formed by irradiating ultraviolet rays with an integrated light amount of 500 mJ / cm ² , and a hard coat layer composition in which the pencil hardness of the cured film surface cured as a single layer on the substrate is HB. the coating film having a thickness of 4 ± 1 [mu] m, in the same conditions, the hard coat layer was formed by irradiating to the ultraviolet an integrated light quantity of 1000 mJ / cm ^2, but this In laminate is laminated comprising the concerns the following (1) and the optical recording medium for the active energy ray-curable composition satisfying (2).

(1) The pencil hardness of the hard coat layer surface of the laminate is H or more. (2) The laminate is warped at a point of 58 mm in the radial direction from the center of the laminate after being left for 24 hours at a temperature of 25 ° C. and a relative humidity of 50%. And the absolute value of the amount of displacement from the warp at the same point after standing for 24 hours at a temperature of 5 ° C. and a relative humidity of 45% is 0.0 ° to 0.6 °. An active energy ray-curable composition for an optical recording medium comprising a monomer having a linearly curable group and / or an oligomer thereof, comprising a circular polycarbonate plate having a thickness of 1.1 mm and a diameter of 120 mm, a recording / reproducing functional layer, the light A high-pressure mercury lamp having an irradiance of 400 mW / cm ² at a wavelength of 254 nm under a condition of an oxygen concentration of 20% is applied to a coating film made of an active energy ray-curable composition for a recording medium and having a thickness of 100 ± 10 μm. UV 500 mJ / cm ² of integrated quantity of light and the protective layer formed by irradiation so as thickness 4 ± consisting pencil hardness of the cured film surface was cured as a single layer on a base material from the hard coat layer composition is HB A laminate in which a hard coat layer formed by irradiating a 1 μm coating film with ultraviolet rays so as to have an integrated light quantity of 1000 mJ / cm ² under the same conditions as described above is laminated in the following order (3 ) And (4), the active energy ray-curable composition for optical recording media.

(3) The pencil hardness of the hard coat layer surface of the laminate is H or more. (4) The laminate is allowed to stand at a temperature of 25 ° C. and a relative humidity of 90% for 24 hours, and further at a temperature of 25 ° C. and a relative humidity of 50%. Displacement from the warp at the time of 0 hour among the warp at the point of 58 mm in the radial direction from the center of the laminate immediately after (0 hour) and the warp at the same point after 1, 2, 3, 5, 9 hours thereafter The absolute value of the displacement amount of the warp of the time when the absolute value of the amount becomes the maximum is 0.0 ° to 0.6 °. The present invention is also for the optical recording medium in which the laminate satisfies the following (5) The present invention relates to an active energy ray-curable composition.

(5) The laminate was allowed to stand at a temperature of 25 ° C. and a relative humidity of 50% for 24 hours and then warped at a point of 58 mm in the radial direction from the center of the laminate, and further allowed to stand at a temperature of 5 ° C. and a relative humidity of 45% for 24 hours. The absolute value of the displacement with respect to the subsequent warp at the same point is 0.0 ° to 0.6 °. In the present invention, the active energy ray for an optical recording medium having a viscosity at 25 ° C. of 500 to 3000 mPa · s. The present invention relates to a curable composition.

The present invention also relates to a cured product obtained by irradiating the active energy ray-curable composition for an optical recording medium with active energy rays.
Moreover, this invention relates also to the laminated body formed by laminating | stacking the cured film which consists of the said hardened | cured material on a base material.

  Since the active energy ray-curable composition for optical recording media of the present invention has a low viscosity, it is excellent in applicability in a coating method such as spin coating generally used in the production of optical recording media. In addition, when a laminate having a protective layer made of a cured product is cured, the pencil hardness of the surface of the hard coat layer formed on the protective layer is high, and the wear resistance is high. A laminate having good properties can be provided. Furthermore, the laminate can be a laminate with low warpage in which deformation due to environmental changes such as temperature and humidity is suppressed, and in particular, the humidity change under a low temperature environment that has a significant effect on the warp of the laminate. It is possible to give a laminate with very little deformation.

In the following, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of embodiments of the present invention, and the present invention is not limited to these contents. .
In this specification, (meth) acrylate is a general term for acrylate and methacrylate. The same applies to the (meth) acryloyl group and (meth) acrylic acid.

Further, in the present specification, “to” is used in the sense of including the numerical values described before and after it as a lower limit value and an upper limit value.
1. Active energy ray-curable composition for optical recording medium The active energy ray-curable composition for an optical recording medium of the present invention contains a monomer and / or oligomer having an active energy ray-curable group. The active energy ray-curable group is not particularly limited as long as it is a group that reacts with active energy rays, and examples thereof include a vinyl group and a (meth) acryloyl group. Among them, a (meth) acryloyl group is preferable from the viewpoint of reactivity. preferable.

The monomer having an active energy ray-curable group is not particularly limited as long as it has one or more active energy ray-curable groups, and includes a vinyl group-containing monomer such as styrene and methylstyrene, (meth) acrylic acid, And (meth) acryloyl group-containing monomers such as esters and (meth) acrylamides, among which one or more (
A (meth) acrylate having a (meth) acryloyl group (hereinafter sometimes referred to as a monofunctional (meth) acrylate), and a (meth) acrylate having two or more (meth) acryloyl groups in one molecule (hereinafter, many A functional (meth) acrylate).

  The oligomer having an active energy ray-curable group is not particularly limited as long as it has one or more active energy ray-curable groups, and an oligomer having one or more (meth) acryloyl groups in one molecule. There is. For example, epoxy (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, acrylic (meth) acrylate, unsaturated polyester, urethane (meth) acrylate, and the like can be given.

  The active energy ray-curable composition for optical recording media of the present invention may be referred to as the following laminate (hereinafter referred to as laminate (A)) using the active energy ray-curable composition for optical recording media. ), (1) the pencil hardness of the hard coat layer surface of the laminate is H or higher, and (2) the laminate is 24 hours at a temperature of 25 ° C. and a relative humidity of 50%. The absolute value of the displacement between the center of the laminate after standing and the warp at a point of 58 mm in the radial direction and the warp at the same point after standing for 24 hours at a temperature of 5 ° C. and a relative humidity of 45% is 0.0 °. ~ 0.6 °.

Such a laminate (A) is (i) a circular polycarbonate plate having a thickness of 1.1 mm and a diameter of 120 mm, and (ii) a thickness of 100 ± 10 μm comprising the active energy ray-curable composition for optical recording media. The coating film was formed by irradiating ultraviolet rays with an integrated light quantity of 500 mJ / cm ² using a high-pressure mercury lamp having an irradiance of 400 mW / cm ² at a wavelength of 254 nm under an oxygen concentration of 20%. Protective layer, (iii) On a coating film having a thickness of 4 ± 1 μm made of a composition for hard coat layer having a pencil hardness of HB of a cured film surface cured as a single layer on a substrate, under the same conditions as above, A hard coat layer formed by irradiating ultraviolet rays so as to obtain an integrated light quantity of 1000 mJ / cm ^{2 is} a laminate in which the layers are laminated in this order.

(I) Polycarbonate plate The polycarbonate plate used in (i) is not particularly limited as long as it is a polycarbonate circular plate having a thickness of 1.1 mm and a diameter of 120 mm.
(Ii) Protective layer (ii) As the protective layer of the layer, a coating film having a thickness of 100 ± 10 μm made of the active energy ray-curable composition for optical recording media of the present invention, under the condition of an oxygen concentration of 20%, This is a protective layer formed by irradiating ultraviolet rays with an integrated light quantity of 500 mJ / cm ² using a high-pressure mercury lamp having an irradiance of 400 mW / cm ² at a wavelength of 254 nm. In addition, the irradiance in this case is based on JIS (JIS-C 1609-1 2006), and the illuminometer Eye UV tester UV-PFA1 light receiving part PD-254 (Iwasaki Electric Co., Ltd.) having a sensor for wavelength 254 nm is used. To measure.

(Iii) Hard coat layer (iii) As the hard coat layer of the layer, a hard coat layer composition having a thickness of 4 ± 1 μm consisting of a hard film surface cured with a single layer on a substrate and having a pencil hardness of HB It is a hard coat layer formed by irradiating ultraviolet rays with an integrated light amount of 1000 mJ / cm ² under the same conditions as those for forming the (ii) layer on the coating film.

In the composition for hard coat layers used here, "the pencil hardness of the cured film surface cured as a single layer on the substrate is HB" means that the thickness is on a 0.1 mm thick polyethylene terephthalate (PET) film. A coating film made of the hard coat layer composition having a thickness of 8 ± 1 μm was formed, and ultraviolet rays were applied using a high-pressure mercury lamp having an irradiance of 400 mW / cm ² at a wavelength of 254 nm under the condition of an oxygen concentration of 20%. It means that the pencil hardness (JIS K5600-5-4) of the surface of the cured film obtained by irradiating with an integrated light quantity of 1000 mJ / cm ² is HB.

As a composition for hard-coat layers used here, if the said conditions are satisfied, the composition will not be specifically limited, A well-known thing can be used.
In the laminate (I), the pencil hardness of the hard coat layer surface of the laminate is H or higher, preferably 2H or higher, more preferably 3H or higher. It is preferable that it is 4H or less from the balance with the curvature of a laminated body.

  Further, after the above laminate (I) was allowed to stand at a temperature of 25 ° C. and a relative humidity of 50% for 24 hours, a warp at a point of 58 mm in the radial direction from the center of the laminate, and further at a temperature of 5 ° C. and a relative humidity of 45%, 24 The absolute value of the amount of displacement (hereinafter sometimes referred to as low temperature tilt) of warping at the same point after standing for a time is 0.0 ° to 0.6 °, preferably 0.4 ° or less, More preferably, it is 0.2 ° or less. It is preferable that the absolute value of the low temperature tilt is small because deformation of the laminate due to temperature change is small.

  Moreover, the active energy ray-curable composition for optical recording media of the present invention uses the active energy ray-curable composition for optical recording media and is referred to as the following laminate (hereinafter referred to as laminate (b)). (3) the hard coat layer surface of the laminate has a pencil hardness of H or higher, and (4) the laminate is at a temperature of 25 ° C. and a relative humidity of 90%. After standing for 24 hours, the warp at the point 58 mm in the radial direction from the center of the laminate immediately after placing it at a temperature of 25 ° C. and a relative humidity of 50% (0 hour), and the same after 1, 2, 3, 5, 9 hours. Among the warpages of the points, the absolute value of the displacement amount of the warp at the time when the absolute value of the displacement amount from the warp at the time of 0 hour is the maximum is 0.0 ° to 0.6 °.

Such a laminate (b) includes (i) a circular polycarbonate plate having a thickness of 1.1 mm and a diameter of 120 mm, (iv) a recording / reproducing functional layer, and (ii) the active energy ray curable composition for the optical recording medium. Using a high-pressure mercury lamp with an irradiance of 400 mW / cm ² at a wavelength of 254 nm under a condition of oxygen concentration of 20% on a coating film having a thickness of 100 ± 10 μm, ultraviolet light is applied with an integrated light quantity of 500 mJ / cm ^2. A protective layer formed by irradiation, and (iii) a coating film having a thickness of 4 ± 1 μm made of a composition for hard coat layer having a pencil hardness of HB on the surface of the cured film cured as a single layer on the substrate A hard coat layer formed by irradiating ultraviolet rays so as to obtain an integrated light quantity of 1000 mJ / cm ² under the same conditions as described above is a laminate obtained by laminating in this order.

In the laminate (b), (i) the polycarbonate plate, (ii) the protective layer, and (iii) the protective layer are the same as those in the above-described laminate (a).
(Iv) Recording / reproducing functional layer (iv) As the recording / reproducing functional layer, a reflective layer containing a metal such as aluminum, silver or gold and a recording layer containing an organic dye are usually laminated in this order. Or a reflective layer containing a metal such as aluminum, silver or gold, a dielectric layer, a recording layer containing an organic dye, and a dielectric layer are laminated in this order. The film thickness is not particularly limited, but is generally preferably 0.1 μm or less.

In the laminate (b), the pencil hardness of the hard coat layer surface of the laminate is H or higher, preferably 2H or higher, more preferably 3H or higher. It is preferable that it is 4H or less from the balance with the curvature of a laminated body.
In addition, after leaving the above laminate (b) at a temperature of 25 ° C. and a relative humidity of 90% for 24 hours, and immediately after placing the laminate at a temperature of 25 ° C. and a relative humidity of 50% (0 hour) in the radial direction of 58 mm. Displacement of the warp at the time when the absolute value of the amount of displacement from the warp at the time of 0 hour becomes the maximum among the warp of the point and the warp at the same point after 1, 2, 3, 5, 9 hours later The absolute value of the quantity (hereinafter sometimes referred to as humidity tilt) is 0.0 ° to 0.6 °, preferably 0.4 ° or less, more preferably 0.2 ° or less. It is preferable that the humidity tilt has a smaller absolute value because there is less deformation of the laminate due to a sudden change in humidity.

  In the laminated body (b), warpage at a point of 58 mm in the radial direction from the center of the laminated body after standing for 24 hours at a temperature of 25 ° C. and a relative humidity of 50%, and still standing for 24 hours at a temperature of 5 ° C. and a relative humidity of 45%. It is preferable that the absolute value of the amount of displacement (low temperature tilt) with the warp at the same point after the adjustment is 0.0 ° to 0.6 °, more preferably 0.4 ° or less, and still more preferably 0.2 °. It is as follows. Also in the laminated body (b), it is preferable that the absolute value of the low-temperature tilt is small because deformation of the laminated body due to temperature change is small.

In addition, since the low temperature tilt is not easily affected by the presence or absence of the recording / reproducing functional layer in the laminate, when the active energy ray-curable composition for optical recording media of the present invention is used, in the laminates (A) and (B) Similar effects can be obtained.
Here, the low temperature tilt or the humidity tilt is an index indicating a large deformation that the laminated body suddenly causes immediately after the temperature and humidity environment change. Such deformation that occurs immediately after the environmental change is reversible, and if left in a changed environment for a long time, the amount of deformation that is deformed to some extent decreases and becomes closer to the original laminate. Therefore, in general, the amount of deformation of the laminate that has been left standing for a long time after the environmental change is larger than the amount of displacement of the laminate that has just been changed immediately after the temperature and humidity environment changes. Becomes smaller.

The fact that the low temperature tilt or humidity tilt, which is an index of deformation immediately after the change of the humidity environment, is large, particularly when such a laminate is used as an optical recording medium, due to changes in the weather and usage environment, the temperature and humidity. It affects the stability of reading and writing information when the environment changes.
The active energy ray-curable composition for an optical recording medium of the present invention particularly satisfies the characteristics (1) and (2) or the characteristics (3) and (4) when used as the protective layer of the laminate as described above. Although it is not limited, since it gives a laminate having excellent surface hardness and low warpage, as an oligomer having an active energy ray-curable group, two or more urethane bonds and two or more (meth) acryloyl in one molecule. It is preferable to include a urethane (meth) acrylate oligomer having a group (hereinafter sometimes referred to as a urethane (meth) acrylate oligomer).

  As the active energy ray-curable composition for optical recording media satisfying the characteristic (2) and reducing warping at low temperature, the composition having a low content of a structure that solidifies at low temperature (for example, 5 ° C.) is used. preferable. In such a composition, when the composition is used as a cured product, the volume shrinkage of the cured product at a low temperature (for example, 5 ° C.) is small, and thus the warpage of the laminate at a low temperature can be reduced.

  In addition, as the active energy ray-curable composition for optical recording media that satisfies the characteristic (4) and reduces the warpage when the humidity changes, those having a slow moisture transmission rate when cured are preferable. By slowing the moisture transmission rate of the cured product, the elastic modulus recovery rate and dehydration / shrinkage rate become slow, and the deformation at the time of humidity change gradually occurs, so it is possible to reduce the warping of the laminate when the humidity changes become.

  In addition, when the hardened | cured material obtained by irradiating an active energy ray to the composition of this invention absorbs moisture, an elastic modulus will fall and a hardened | cured material will swell. When the cured product that has absorbed moisture in this way releases moisture, the elastic modulus recovers as the moisture content in the cured product decreases, and the cured product shrinks. Starting from the point at which the cured product swells due to moisture absorption, the rate at which the elastic modulus of the cured product recovers is called the elastic modulus recovery rate, and the rate at which the cured product shrinks is called the dehydration shrinkage rate. Usually, the cured product absorbs moisture by being placed under high humidity conditions, and the moisture-absorbed cured product is dehumidified by being placed under low humidity conditions.

As an example of a composition having a low elastic modulus recovery rate of a cured product, for example, in an environment at a temperature of 23 ° C.,
A cured product having a tensile modulus of elasticity at 45% relative humidity (hereinafter sometimes referred to as initial tensile modulus) of 1570 MPa is allowed to stand at a temperature of 23 ° C. and a relative humidity of 95% for 15 hours, and then at a temperature of 23 ° C. and a relative humidity. The tensile elastic modulus immediately after being placed under the condition of 45% is 660 MPa, and when this cured product is left to stand at a temperature of 23 ° C. and a humidity of 45%, the tensile elastic modulus is 1120 MPa after 1 hour and 2 hours later. Examples thereof include an active energy ray-curable composition for an optical recording medium, which is 1230 MPa, 1260 MPa after 3 hours, and 1600 MPa after 24 hours. Thus, after setting the tensile modulus of the cured product in an environment of a temperature of 23 ° C. and a relative humidity of 45% as an initial tensile modulus, the cured product was allowed to stand at a temperature of 23 ° C. and a relative humidity of 95% for 15 hours. The tensile modulus immediately after being placed at a temperature of 23 ° C. and a relative humidity of 45% was taken as the tensile modulus after absorption of moisture (0), and the cured product was allowed to stand at a temperature of 23 ° C. and a humidity of 45% for 1 hour. When the tensile modulus after the moisture absorption is the tensile modulus after the moisture absorption (1) and the tensile modulus after the 24 hours is the tensile modulus after the moisture absorption (24), the tensile modulus after the moisture absorption (1) is 95 of the initial tensile modulus. % Or less is preferable. More preferably, it is 90% or less, more preferably 85% or less, still more preferably 80% or less, particularly preferably 75% or less, and preferably 50% or more. Further, the tensile elastic modulus after moisture absorption (24) is preferably 97% or more of the initial tensile elastic modulus, more preferably 100% or more, and preferably 130% or less. Such a composition that gives a cured product exhibiting a change in tensile modulus during moisture release can be said to be a composition having a low elastic modulus recovery rate, and is preferable because it suppresses the humidity tilt of the laminate.

  In order to reduce the elastic recovery rate and dehydration shrinkage rate of the cured product, it is preferable to decrease the moisture release rate from the cured product. The moisture release rate from the cured product varies depending on the diffusion coefficient of water in the cured product and the interaction between the cured product and water (including the solubility of the cured product). The moisture release rate is considered to be slower when the interaction between the cured product and water is increased, and the elastic recovery rate and dehydration shrinkage rate can be changed by strengthening the interaction between water and the cured product.

  In order to strengthen the interaction with water, the cured product obtained by curing the active energy ray-curable composition for optical recording media preferably contains a structure that causes an interaction with water. It is not limited. More preferred is a structure that interacts with water by a hydrogen bond, and examples thereof include a urethane bond, a urea bond, an amide group, an amino group, a hydroxyl group, a carboxyl group, and other ion-binding functional groups. In particular, it is more preferable to use a urethane (meth) acrylate oligomer as the oligomer having an active energy ray-curable group because an appropriate hydrogen bond is obtained in the cured product.

Furthermore, it is preferable that the interaction with water can be strengthened by dispersing inorganic particles such as metal or metal oxide having a Lewis acid point on the surface in the composition.
Since the concept of diffusion coefficient and interaction is the same as the general concept of permeation rate, the rate at which water escapes from the moisture-absorbed cured product can be evaluated by measuring the moisture permeation rate of the cured product. That is, it is presumed that the elastic recovery rate and dehydration shrinkage rate of the cured product can be reduced by reducing the moisture transmission rate. Another method for slowing the moisture transmission rate is to reduce the diffusion coefficient of water in the cured product by densifying the molecular network of the cured product. In order to make the molecular network dense, for example, a crystalline component is included, the molecular chain of the cured product is oriented, the symmetry of the molecular chain of the cured product is increased, or the molecular chain of the cured product is greatly increased. Examples of the method include not having a side chain. However, if the molecular network is simply made dense, warpage of the laminate tends to occur, so care must be taken.

In addition, the elastic modulus after moisture absorbed from the moisture-absorbed cured product (hereinafter sometimes referred to as post-moisture elastic modulus) may be higher than the initial elastic modulus. This is presumably because molecular chain rearrangement occurs in the cured product due to moisture absorption. It is presumed that the elastic modulus increases due to the shrinkage of the cured product by this rearrangement. Therefore, as the active energy ray-curable composition for optical recording media in which the warp when the humidity changes is small, the difference between the initial elastic modulus of the cured product and the elastic modulus after moisture release is small, and the volume change is small. It is thought that it is a composition which gives hardened | cured material, and is preferable. In particular, the rate of change between the initial elastic modulus of the cured product and the elastic modulus after moisture release, that is, the numerical value obtained by dividing the elastic modulus after moisture release by the initial elastic modulus is more preferably in the range of 1.1 to 0.9.

1-1. Urethane (meth) acrylate oligomer
The urethane (meth) acrylate oligomer is not particularly limited as long as it is an oligomer having two or more urethane bonds and two or more (meth) acryloyl groups in one molecule, but is irradiated with a low irradiation dose of active energy rays. A urethane acrylate oligomer is preferable in the composition of the present invention because it is excellent in low-dose curability when cured, and tack (stickiness) hardly remains. Here, the low dose curable property means that the surface is less tacky and apparently hardened despite the fact that the irradiation dose is about 1/10 of the normal and the curing reaction is hardly progressing. The nature that can be seen.

Examples of urethane (meth) acrylate oligomers include polyisocyanates as raw materials, compounds containing two or more hydroxyl groups, and reactants obtained using (meth) acrylates containing one or more hydroxyl groups. Can be mentioned.
(1) Polyisocyanate Polyisocyanate may be a compound having two or more isocyanate groups in one molecule, for example, a diisocyanate having two isocyanate groups in one molecule or three isocyanate groups. A triisocyanate etc. are mentioned. Among them, a diisocyanate having a C 1-20 alkylene group which may contain an alicyclic structure and a C 1-15 cycloalkylene group which may have a substituent is particularly preferable. Aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, isophorone diisocyanate; Xylylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, α, α, α ′, α′-tetramethylxylylene diisocyanate, naphthalene diiso Aromatic diisocyanates such as cyanate; 1,3,5-triisocyanatecyclohexane, 1,3,5-trimethylisocyanatecyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatemethyl) -bicyclo [2. 2.1] Heptane, 2- (3-isocyanatopropyl) -2,6-di (isocyanatomethyl) -bicyclo [2.2.1] heptane, 3- (3-isocyanatopropyl) -2,5-di ( Isocyanatomethyl) -bicyclo [2.2.1] heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo [2.2.1] heptane, 6- ( 2-Isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanate propylene ) -Bicyclo [2.2.1] heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo [2.2.1] -heptane, 6- (2 -Triisocyanate such as -isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo [2.2.1] heptane, and multimers thereof. One of these may be used alone, or two or more may be used in combination.

Of these, aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate, bis (isocyanatomethyl) cyclohexane, cyclohexane Alicyclic diisocyanates such as diisocyanate, bis (isocyanatocyclohexyl) methane, and isophorone diisocyanate are preferred. Since the surface hardness of a cured product (hereinafter sometimes referred to as cured product) obtained by irradiating the composition with active energy rays is increased, bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) More preferred are alicyclic diisocyanates such as methane and isophorone diisocyanate.

(2) Compound containing two or more hydroxyl groups The compound containing two or more hydroxyl groups only needs to have two or more hydroxyl groups in one molecule. For example, two hydroxyl groups Glycolic alcohol, polyhydric alcohol having 3 or more hydroxyl groups, or polyol having 2 or more hydroxyl groups and having a repeating unit structure in the compound can be used.

  Among them, glycol is preferable because it is difficult to coagulate at a low temperature (for example, 5 ° C.) as a composition and the surface hardness of the resulting cured product is high, and particularly has 2 to 20 carbon atoms that may contain an alicyclic structure. An alkylene group, an alkenylene group, or a glycol having an optionally substituted cycloalkylene group having 2 to 20 carbon atoms is preferred. Specific examples include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -Pentanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,3,5-trimethyl-1,5-pentanediol, 1,6-hexane Diol, 2-ethyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, , 12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,2-dimethylolcyclohexane 1,3-dimethylol cyclohexane, alkylene glycols such as 1,4-dimethylol cyclohexane.

Among these, in order to increase the surface hardness of the cured product, glycol having 10 or less carbon atoms between hydroxyl groups is preferable. In order to reduce the viscosity of the composition of the present invention, a glycol having a side chain is preferred.
Specific examples of the polyhydric alcohol include glycerin, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, 1,2,4-butanetriol, erythritol, sorbitol, pentaerythritol, dipentaerythritol, mannitol, And alkylene polyhydric alcohols containing 3 or more hydroxyl groups.

  As the representative polyol, known ones such as polyether polyol, polyester polyol, polycarbonate polyol can be used. Since the polyol is added for the purpose of suppressing warpage of a laminate (hereinafter sometimes referred to as a laminate) formed by laminating a cured film made of a cured product, a polyol having a relatively flexible structure is preferable. Among these, when the composition of the present invention is used as a protective layer of an optical recording medium, a polyester polyol is preferred because the protective layer is in direct contact with the metal-containing layer and the metal-containing layer is unlikely to corrode.

The number average molecular weight of the polyol is preferably 500 or more because the viscosity of the composition of the present invention is easily adjusted to an appropriate range, and is preferably 5000 or less because the surface hardness of the cured product tends to increase.
Specific examples of the polyether polyol include polytetramethylene glycol as a ring-opening polymer of a cyclic ether such as tetrahydrofuran in addition to the glycol multimer, and the glycol, ethylene oxide, propylene oxide, 1, 2 Examples include adducts with alkylene oxides such as -butylene oxide, 1,3-butylene oxide, 2,3-butylene oxide, tetrahydrofuran, and epichlorohydrin.

Specific examples of the polyester polyol include a reaction product of the glycol and a polybasic acid such as maleic acid, fumaric acid, adipic acid, sebacic acid and phthalic acid, and a ring-opening polymer of a cyclic ester such as caprolactone. And polycaprolactone.
Specific examples of the polycarbonate polyol include the glycol and alkylene carbonate such as ethylene carbonate, 1,2-propylene carbonate, 1,2-butylene carbonate; or diphenyl carbonate, 4-methyldiphenyl carbonate, 4-ethyldiphenyl carbonate. 4-propyl diphenyl carbonate, 4,4′-dimethyl diphenyl carbonate, 2-tolyl-4-tolyl carbonate, 4,4′-diethyl diphenyl carbonate, 4,4′-dipropyl diphenyl carbonate, phenyl toluyl carbonate, bischlorophenyl Diaryl carbonates such as carbonate, phenylchlorophenyl carbonate, phenylnaphthyl carbonate, dinaphthyl carbonate; or dimethyl carbonate Reaction with dialkyl carbonates such as dicarbonate, di-n-propyl carbonate, diisopropyl carbonate, di-n-butyl carbonate, diisobutyl carbonate, di-t-butyl carbonate, di-n-amyl carbonate, diisoamyl carbonate, etc. Thing etc. are mentioned.

(3) (Meth) acrylates containing one or more hydroxyl groups (Meth) acrylates containing one or more hydroxyl groups are one or more hydroxyl groups and one or more (meth) acryloyl in one molecule. Any (meth) acrylate having a group may be used, and from the viewpoint of curability of the composition, the compound is preferably a compound represented by the following general formula (3), and preferably n in the general formula (3) is 1 to 30. More preferably, it is a compound that is an integer of, and more preferred are hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate. When n in the general formula (3) is small, the surface hardness of the cured product tends to be high, which is preferable.

(R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an alkylene group having 2 to 6 carbon atoms, and n represents an integer of 1 to 50.)
In addition, addition reaction products of glycidyl ether and (meth) acrylic acid, polyol mono (meth) acrylate, and the like can be used.
As the (meth) acrylate containing one or more hydroxyl groups, one of these may be used alone, or two or more may be used in combination.

The molecular weight of the (meth) acrylate containing one or more hydroxyl groups is preferably 40 or more, more preferably 80 or more, and preferably 800 or less, more preferably 400 or less.
(4) Properties of urethane (meth) acrylate oligomer The urethane (meth) acrylate oligomer is preferably highly transparent, for example, a compound having no aromatic ring. When the urethane (meth) acrylate oligomer has an aromatic ring, the active energy ray-curable composition and its cured product may be colored or may be colored during storage even if it is not initially colored. There is an increase in coloring (so-called yellowing).

  This is considered to be caused by the fact that the double bond part forming the aromatic ring irreversibly changes its structure by the active energy ray. For this reason, the urethane (meth) acrylate oligomer has an aromatic ring. By having a structure that does not have, there is an advantage that the hue is not deteriorated and the light transmittance is not lowered, and it is particularly suitable for application to an application requiring colorless and transparent such as an optical recording medium.

A urethane (meth) acrylate oligomer having no aromatic ring includes a polyisocyanate having no aromatic ring, a compound containing two or more hydroxyl groups having no aromatic ring, and one or more hydroxyl groups having no aromatic ring. It can manufacture by selecting (meth) acrylate containing as a raw material.
Specific examples of the polyisocyanate having no aromatic ring include alicyclic diisocyanates such as bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, and isophorone diisocyanate. Specific examples of the compound containing 2 or more hydroxyl groups that do not include alkylene polyol, alkylene polyester, each polyol of alkylene carbonate, etc., and also contains 1 or more hydroxyl groups that do not have an aromatic ring Specific examples of the (meth) acrylate to be used include hydroxyalkyl (meth) acrylate. In addition, these 1 type may be used independently and may be used in combination of 2 or more type.

The number average molecular weight of the urethane (meth) acrylate oligomer is preferably 700 or more, more preferably 800 or more from the viewpoint of the balance between the viscosity of the composition and the mechanical properties of the cured product. It is preferable that:
In addition, the weight average molecular weight of the urethane (meth) acrylate oligomer is preferably 1400 or more, more preferably 1500 or more, more preferably 10,000 or less, further from the viewpoint of the balance between the viscosity of the composition and the mechanical properties of the cured product. Is preferably 4000 or less.

  The active energy ray-curable composition for an optical recording medium of the present invention preferably contains urethane (meth) acrylate oligomers of the following compounds (A) and (B) as urethane (meth) acryl oligomers, and moreover, compounds (C) can include urethane (meth) acrylate oligomers other than the compounds (A) and (B). Hereinafter, the compounds (A), (B) and (C) may be collectively referred to as urethane (meth) acrylate oligomers.

The compounds (A), (B) and (C) will be described in detail below.
1-1-2. Compound (A)
The compound (A) in the present invention is a urethane (meth) acrylate oligomer represented by the following general formula (1). It is preferable that the composition of the present invention contains the compound (A) because the cured product has a high surface hardness and can be sufficiently cured even when the irradiation amount of active energy rays is low, and is excellent in curability.

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. A cycloalkylene group having 1 to 15 carbon atoms which may be present, and R ₄ is an alkylene group having 2 to 20 carbon atoms which may contain an alicyclic structure, an alkenylene group and a carbon number which may have a substituent. 2-20 cycloalkylene groups are represented, and n represents an integer of 1-50.)
The compound (A) is not particularly limited as long as it is represented by the general formula (1), but is usually a reaction product of the diisocyanate, the glycol, and the compound represented by the general formula (3). Is preferred.

R ₁ in the general formula (1) is a hydrogen atom or a methyl group, and is preferably a hydrogen atom because of excellent curability of the composition of the present invention.
R ₂ in the general formula (1) is an alkylene group having 2 to 6 carbon atoms, preferably an alkylene group having 2 to 4 carbon atoms.
R ₃ in the general formula (1) is usually a linking group derived from diisocyanate, an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, or a carbon which may have a substituent. A cycloalkylene group having a number of 1 to 15. The alkylene group may have a branched structure. Here, the case where R ₃ is a cycloalkylene group refers to a structure in which a nitrogen atom derived from an isocyanate group is directly bonded to an alicyclic structure and does not contain an alkylene group therebetween.

  Preferably, it is derived from a cycloalkylene group having 6 to 15 carbon atoms which may have a substituent derived from cyclohexane diisocyanate or the like, or bis (isocyanatomethyl) cyclohexane, bis (isocyanatocyclohexyl) methane, isophorone diisocyanate and the like. An alkylene group having 6 to 20 carbon atoms which may contain an alicyclic structure, particularly preferably derived from cyclohexane diisocyanate, bis (isocyanatomethyl) cyclohexane, bis (isocyanatocyclohexyl) methane, or isophorone diisocyanate. It is a linking group.

R ₄ in the general formula (1) is usually a linking group derived from glycol, and may have an alicyclic structure, an alkylene group having 2 to 20 carbon atoms, an alkenylene group, or a substituent. It is a good cycloalkylene group having 2 to 20 carbon atoms. The alkylene group and alkenylene group may have a branched structure.
Since the curability of the composition is good and the surface hardness of the resulting cured product is high, it is preferably an alkylene group having 3 to 9 carbon atoms. Specifically, 1,2-propanediol, 1,3 -Propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,5-pentanediol, neopentyl glycol 3-methyl-1,5-pentanediol, 2,3,5-trimethyl-1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,6-hexanediol, 2,2,4 -Trimethyl-1,6-hexanediol, 1,8
-An alkylene group which is a linking group derived from octanediol, 1,9-nonanediol or the like and an alkylene group having a branched structure are more preferable.

N in the general formula (1) is an integer of 1 to 50, preferably 1 to 30 because the surface hardness of the cured product is good.
1-1-3. Compound (B)
The compound (B) in the present invention is a urethane (meth) acrylate oligomer represented by the following general formula (2).

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. Represents an optionally substituted cycloalkylene group having 1 to 15 carbon atoms, and n represents an integer of 1 to 50.)
Although it will not specifically limit if a compound (B) is represented by General formula (2), Usually, it is preferable that it is a reaction material of the compound represented by the said diisocyanate and the said General formula (3).

In the general formula (2), R ₁ , R ₂ , R ₃ , and n are the same as the structure in the general formula (1).
1-1-4. Compound (C)
The compound (C) in the present invention is not particularly limited as long as it is a urethane (meth) acrylate oligomer other than the above compounds (A) and (B). For example, the above-mentioned polyisocyanate, a compound containing two or more hydroxyl groups And urethane (meth) acrylate oligomers other than compounds (A) and (B) among (meth) acrylate reactants containing one or more hydroxyl groups. Specifically, the reaction product of the polyol represented by the diisocyanate, polyether polyol, polyester polyol, polycarbonate polyol, and the compound represented by the general formula (3); the diisocyanate, the glycol, and the general formula (3) And a urethane (meth) acrylate oligomer represented by the following general formula (4).

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. A cycloalkylene group having 1 to 15 carbon atoms which may be present, and R ₄ is an alkylene group having 2 to 20 carbon atoms which may contain an alicyclic structure, an alkenylene group and a carbon number which may have a substituent. 2-20 cycloalkylene groups are represented, n is an integer of 1-50, m represents an integer of 2 or more.)
R ₁ , R ₂ , R ₃ , R ₄ and n in the general formula (4) are the same as the structure in the general formula (1).

  The active energy ray-curable composition for an optical recording medium of the present invention contains the compounds (A) and (B) at a ratio of (A) / (B) = 2.0 to 7.0 (weight ratio). preferable. If it is 2.0 or more, the warp of the laminate tends to be small, and if it is 7.0 or less, the hardness tends to increase, which is preferable. In order to increase the surface hardness of the cured product and reduce the viscosity of the composition, it is preferably 2.8 or more and more preferably 5.0 or less.

  In addition, content of a compound (A) and (B) can be measured by measuring molecular weight distribution of a composition. The molecular weight distribution is measured by size exclusion chromatography, particularly gel permeation chromatography (hereinafter sometimes abbreviated as GPC). Each content is obtained by calculating the peak area ratio of the peak corresponding to the molecular weight of the compound (A) or (B) from the molecular weight distribution measurement result. For example, the molecular weight of the obtained compounds (A) and (B) is calculated from the molecular weight of the raw material when producing the urethane (meth) acrylate oligomer, and the peak corresponding to this is specified.

  When the active energy ray-curable composition for optical recording media of the present invention contains the compound (C), a urethane (meth) acrylate oligomer is used as the sum of the compounds (A), (B), and (C). The total content is preferably 20% by weight or more, more preferably 30% by weight or more, still more preferably 40% by weight or more, and preferably 90% by weight or less, more preferably 80% by weight or less, More preferably, it is 70 weight% or less. When the amount is not less than the lower limit value, both the surface hardness of the cured product and the warpage suppression of the laminate tend to be compatible, and when the value is not more than the upper limit value, the viscosity of the composition tends to become a viscosity suitable for smooth application, which is preferable. .

  In addition, the number average molecular weight of the urethane (meth) acrylate oligomer mixture composed of the compounds (A), (B) and (C) is 700 or more from the viewpoint of the balance between the viscosity of the composition and the mechanical properties of the cured product. Is preferably 800 or more, and is preferably 4000 or less, more preferably 2000 or less. The weight average molecular weight is preferably 1400 or more, more preferably 1500 or more, and preferably 10,000 or less, more preferably 4000 or less, from the viewpoint of the balance between the viscosity of the composition and the mechanical properties of the cured product. preferable.

1-1-5. Production method of urethane (meth) acrylate oligomer The production method of the urethane (meth) acrylate oligomer used in the present invention is not particularly limited. For example, the polyisocyanate and the compound containing two or more hydroxyl groups, A urethane (meth) acrylate oligomer can be produced by addition reaction with the (meth) acrylate containing one or more hydroxyl groups. Specifically, one molecule of a compound having two or more isocyanate groups in a molecule obtained by addition reaction of a polyisocyanate or a polydiisocyanate and a compound containing two or more hydroxyl groups, and one or more hydroxyls A urethane (meth) acrylate oligomer having a (meth) acryloyl group at both ends can be produced by addition reaction of two (meth) acrylate molecules containing a group.

As the addition reaction catalyst at this time, for example, dibutyltin laurate, dibutyltin dioctoate, dioctyltin dilaurate, and dioctyltin dioctoate are preferable, and one of these may be used alone, You may use combining more than a seed.
This addition reaction is not particularly limited, and can be usually performed by any known method. For example, a mixture of a polyisocyanate, a compound containing two or more hydroxyl groups, a (meth) acrylate containing one hydroxyl group and an addition reaction catalyst is usually 40 ° C. or higher, preferably 50 ° C. or higher. The mixing is usually performed at 90 ° C. or lower, preferably 75 ° C. or lower. As a method of mixing, polyisocyanate, a compound containing two or more hydroxyl groups, a (meth) acrylate containing one hydroxyl group, and an addition reaction catalyst may be mixed and reacted together. First, a polyisocyanate and a compound containing two or more hydroxyl groups are subjected to addition reaction, and then a mixture of (meth) acrylate containing one or more hydroxyl groups and an addition reaction catalyst is added dropwise. The addition reaction can also be performed in stages. In order to reduce the content of the compound (B) and adjust the ratio of the compounds (A) and (B) ((A) / (B)) to a desired range, a method of performing an addition reaction in two stages Is preferred.

When the urethane (meth) acrylate oligomer is produced, it is not necessary to use a solvent in particular, but an organic solvent such as ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene may be used.
In addition, when manufacturing a urethane (meth) acrylate oligomer, unless the effect of this invention is impaired, the polyisocyanate, the compound containing 1 or more hydroxyl groups, and the (meth) acrylate containing 1 or more hydroxyl groups In addition, other components may be included.

  When two or more kinds of urethane (meth) acrylate oligomers are obtained using two or more kinds of compounds, for example, glycol and polyol, as a compound having two or more hydroxyl groups, and the mixture is used, glycol and polyol May be mixed together and reacted with polyisocyanate to obtain a mixture at once, or after reacting glycol and polyol separately with polyisocyanate, the resulting urethane (meth) acrylate oligomer is mixed as a mixture It doesn't matter.

Among them, the compounds (A) and (B) are an alkylene group having 1 to 20 carbon atoms which may include an alicyclic structure and a cycloalkylene group having 1 to 15 carbon atoms which may have a substituent. Having a diisocyanate (hereinafter sometimes referred to as diisocyanate (I)), an alicyclic structure, an alkylene group having 2 to 20 carbon atoms, an alkenylene group, and optionally having 2 substituents. Reaction of a glycol having -20 cycloalkylene groups (hereinafter sometimes referred to as glycol (II)) and a compound represented by the general formula (3) (hereinafter sometimes referred to as compound (III)) Can be manufactured. Specifically, for example, after reacting diisocyanate (I) and glycol (II), compound (III) is added and an addition reaction is performed, whereby compound (A), compound (B), and the above general formula Various urethane (meth) acrylate oligomers such as urethane (meth) acrylate oligomer corresponding to the compound (C) represented by (4) can be obtained.

  Here, compounds (A) and compounds in various urethane (meth) acrylate oligomers obtained by reacting polyisocyanate, a compound having two or more hydroxyl groups and a (meth) acrylate having one or more hydroxyl groups The ratio of (B) is the ratio of the number of isocyanate groups of the polyisocyanate used as a raw material to the number of hydroxyl groups of a compound having two or more hydroxyl groups (hereinafter sometimes referred to as NCO / OH ratio), 2 It can be controlled by the proportion of glycol in compounds having more than one hydroxyl group.

In general, when the ratio of glycol in a compound having two or more hydroxyl groups is high, the content of compound (A) increases when the NCO / OH ratio is large, and the compound increases as the NCO / OH ratio approaches 1. The content of (A) is close to 0%. On the other hand, when the glycol content of the compound having two or more hydroxyl groups is lowered, the content of the compound (A) is lowered.
Further, similarly to the compound (A), when the ratio of the glycol of the compound having two or more hydroxyl groups is high, the content of the compound (B) increases when the NCO / OH ratio is large. As the NCO / OH ratio approaches 1, the content of compound (B) approaches 0%.

  Furthermore, when the ratio of glycol of the compound having two or more hydroxyl groups is high, the ratio of the compound (A) and the compound (B) is large when the NCO / OH ratio is large (A) / (B) (weight ratio). The value of (A) / (B) (weight ratio) tends to increase as the NCO / OH ratio approaches 1. Further, when the glycol content of the compound having two or more hydroxyl groups is lowered, the value of (A) / (B) (weight ratio) tends to increase.

  Therefore, the NCO / OH ratio is preferably in the range of 1.2 to 1.8. When the NCO / OH ratio is greater than 1.2, the molecular weight of the resulting oligomer compound does not become too large, the viscosity of the composition can be easily adjusted to an appropriate range, and many other than the compounds (A) and (B) Since the ratio of the compound containing the urethane bond decreases, the rigidity is appropriate and the warp of the laminate is reduced, which is preferable. When NCO / OH is smaller than 1.8, the ratio of the compound (B) does not increase too much, and the warp when the laminate is formed and the warp when the temperature and humidity change are small, which is preferable.

1-2. Compound (D)
The active energy ray-curable composition for optical recording media of the present invention comprises a monomer having an active energy ray-curable group as the compound (D) and / or a urethane (meta) of the compounds (A), (B), and (C). ) An oligomer having an active energy ray-curable group other than the acrylate oligomer may be included.

The composition of the present invention preferably contains a compound (D) suitable for the purpose of adjusting the viscosity so that it can be easily applied in accordance with various application methods when it is used as a coating film.
The monomer having an active energy ray-curable group is not particularly limited as long as it has one or more active energy ray-curable groups, and a vinyl group-containing monomer such as styrene or methylstyrene, (meth) acrylic acid, And (meth) acryloyl group-containing monomers such as esters and (meth) acrylamides, among which monofunctional (meth) acrylates and polyfunctional (meth) acrylates are preferred.

Specific examples of the monofunctional (meth) acrylate include (meth) acrylamides such as N, N-dimethyl (meth) acrylamide; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) ) Hydroxyalkyl (meth) acrylates such as acrylate; (meth) acryloylmorpholine, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylate having a tricyclodecane skeleton, etc. Examples include alicyclic (meth) acrylates; aromatic (meth) acrylates such as phenoxyethyl (meth) acrylate, among which alicyclic (meth) acrylates and aromatic (meth) acrylates are preferred. Properly, among them, tetrahydrofurfuryl (meth) acrylate because it is good curability of the composition, cyclohexyl (meth) acrylate, tricyclodecane having a skeleton (meth) acrylate, phenoxyethyl (meth) acrylate are particularly preferred.

Examples of the polyfunctional (meth) acrylate include aliphatic poly (meth) acrylate, alicyclic poly (meth) acrylate, and aromatic poly (meth) acrylate. Specific examples include bisphenol A, bisphenol F, or Di (meth) acrylate of hydrogenated derivatives of bisphenol such as bisphenol S, hexanediol di (meth) acrylate, octanediol di (meth) acrylate, nonanediol di (meth) acrylate, decanediol 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 = di (meth) acrylate Bifunctional (meth) acrylates such as p-bis [β- (meth) acryloyloxyethylthio] xylylene, 4,4′-bis [β- (meth) acryloyloxyethylthio] diphenylsulfone; trimethylol Trifunctional (meth) acrylates such as propane tris (meth) acrylate, glycerin tris (meth) acrylate, pentaerythritol tris (meth) acrylate; tetrafunctional (meth) acrylates such as pentaerythritol tetrakis (meth) acrylate; dipenta (Meth) having 5 or more functional groups such as erythritol hexa (meth) acrylate is exemplified.

Of these, bifunctional (meth) acrylates are preferred because of the controllability of the cross-linking formation reaction when irradiated with active energy rays. Among them, as the bifunctional (meth) acrylate, aliphatic di (meth) acrylate and alicyclic di (meth) acrylate are preferable, and hexanediol di (meth) acrylate, nonanediol di (meth) acrylate, bis (Hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane = di (meth) acrylate is preferred. Further, from the viewpoint of load resistance as a cured product, a di (meth) acrylate of a diol having 6 to 20 carbon atoms, and further 8 to 12 carbon atoms, specifically, hexanediol di (meth) acrylate, octane. Diol di (meth) acrylate, nonanediol di (meth) acrylate and the like are particularly preferable.

  The oligomer having an active energy ray-curable group is not particularly limited as long as it has one or more active energy ray-curable groups, but one or two (meth) acryloyl groups in one molecule. It is possible to use an oligomer having For example, an epoxy (meth) acrylate, a polyester (meth) acrylate, an acrylic (meth) acrylate, an unsaturated polyester, an oligomer obtained by polymerizing the above monofunctional (meth) acrylate or polyfunctional (meth) acrylate, and the like can be given. .

The epoxy (meth) acrylate is not particularly limited as long as it is a compound having a bisphenol skeleton and containing a (meth) acryloyl group. Acrylic acid adduct and the like.
The polyester (meth) acrylate is not particularly limited as long as it has a polyester skeleton obtained from a glycol compound and a dicarboxylic acid and contains a (meth) acryloyl group. For example, 1,4-butanediol and adipine Acrylic acid adduct of polyester composed of acid, acrylic acid adduct of polyester composed of 1,6-hexanediol and adipic acid, acrylic acid adduct of polyester composed of 1,4-butanediol and terephthalic acid, 1,6- Examples include acrylic acid adducts of polyesters composed of hexanediol and terephthalic acid, and polycaprolactone acrylic acid adducts as ring-opening polymers of cyclic ester compounds such as caprolactone.

  The polyether (meth) acrylate is not particularly limited as long as it is a compound having a polyether skeleton and containing a (meth) acryloyl group. For example, polyethylene glycol, polypropylene glycol, polytrimethylene glycol, 1, 2-polybutylene glycol, polyisobutylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polytrimethylolpropane, polyglycerin, polypentaerythritol, polyalkylene oxide-added hydrogenated bifphenol A, polyalkylene oxide-added hydrogenated bisphenol F Polyalkylene oxide-added bisphenol A, polyalkylene oxide-added bisphenol F, ε-caprolactone-added bisphenol A, ε-caprolactone-added biphenol A Examples thereof include acrylic acid adducts of polyols such as Sphenol F, ε-caprolactone-added hydrogenated bisphenol A, and ε-caprolactone-added hydrogenated bisphenol F.

The molecular weight of the compound (D) is preferably 50 or more, more preferably 100 or more, and preferably 1,000 or less, more preferably 500, from the viewpoint of the balance between the viscosity and cure shrinkage of the resulting composition. It is preferable that:
These compounds (D) may be used alone or in combination of two or more. However, it is preferable to contain at least one polyfunctional (meth) acrylate from the point of hardness of the cured product.

  On the other hand, the content of the monofunctional (meth) acrylate when the monofunctional (meth) acrylate is contained in the compound (D) is preferably 70% by weight or less, more preferably 60%. % By weight or less. When the content of the monofunctional (meth) acrylate is 70% by weight or less, the surface of the cured product tends to hardly have a load mark, which is preferable. On the other hand, in order to reduce the content of the monofunctional (meth) acrylate, use a low-viscosity urethane (meth) acrylate oligomer or a polyfunctional (meth) acrylate having a relatively low viscosity. It is preferable to balance the viscosity as the active energy ray-curable composition for optical recording media and various physical properties as the cured product.

1-3. Content ratio of active energy ray-curable compound In the active energy ray-curable composition for an optical recording medium of the present invention, the compounds (A), (B), (C) and (D) (hereinafter collectively referred to as active energy) When the total content of the linear curing compound is 100 parts by weight, the total content of the compounds (A), (B) and (C) (urethane (meth) acrylate oligomer) is preferably Is 30 parts by weight or more, more preferably 40 parts by weight or more, preferably 70 parts by weight or less, more preferably 60 parts by weight or less. When it is 30 parts by weight or more, the strength of the cured product is increased, and when it is 70 parts by weight or less, the viscosity of the composition does not become excessively high and is easily adjusted to an appropriate range.

The content of the compound (D) in the active energy ray-curable composition for optical recording media of the present invention is preferably 30 parts by weight or more, more preferably 40 parts by weight or more with respect to 100 parts by weight of the active energy ray-curable compound. And, it is preferably 70 parts by weight or less, more preferably 60 parts by weight or less.
The content of the compound (A) is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, preferably 30 parts by weight or less, more preferably 100 parts by weight of the active energy ray-curable compound. Is 20 parts by weight or less. The amount of 5 parts by weight or more is preferable because the surface hardness of the cured product is increased and the curability is excellent. Further, if it is 30 parts by weight or less, it is preferable because the amount of displacement of the warp of the laminate when the humidity changes is small, and this is because the hydrophilicity of the urethane bond is high and the compound (A) has a rigid structure. it is conceivable that.

  The content of the compound (B) is preferably 0.1 parts by weight or more and 10 parts by weight or less, and more preferably 5 parts by weight or less with respect to 100 parts by weight of the active energy ray-curable compound. When it is 10 parts by weight or less, it is preferable that warpage when the laminate is used at room temperature (25 ° C., 50% RH) is small, and the amount of warpage displacement when temperature and humidity change is small.

1-4. Polymerization initiator The active energy ray-curable composition for optical recording media of the present invention may further contain a polymerization initiator for initiating a polymerization reaction that proceeds by active energy rays (for example, ultraviolet rays, electron beams, etc.). preferable. In particular, when the active energy ray is ultraviolet light, it is preferable to contain a polymerization initiator. As the polymerization initiator, a radical generator that is a compound having a property of generating radicals by light is generally used, and any radical generator can be used as long as the effects of the present invention are not significantly impaired. A known radical generator can be used.

  Specific examples of such radical generators include benzophenone, 2,4,6-trimethylbenzophenone, 4,4-bis (diethylamino) benzophenone, 4-phenylbenzophenone, methylorthobenzoylbenzoate, thioxanthone, diethylthioxanthone, and isopropylthioxanthone. Chlorothioxanthone, 2-ethylanthraquinone, t-butylanthraquinone, 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, methylbenzoyl formate, 2-methyl-1- [4 (Methylthio) phenyl] -2-morpholinopropan-1-one, 2,6-dimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4 , 4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, 2-hydroxy-1- [4- {4- (2-hydroxy-2-methyl-propionyl) benzyl} phenyl] -2-methyl-propan-1-one and the like. Among them, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 2-hydroxy-1- [4- {4- (2-hydroxy-2-methyl-propionyl) benzyl} phenyl] 2-methyl-propan-1-one.

  Among the above radical generators, benzophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 1-hydroxycyclohexyl are included in that the curing speed is high and the crosslinking density can be sufficiently increased. Phenylketone, 2-hydroxy-1- [4- {4- (2-hydroxy-2-methyl-propionyl) benzyl} phenyl] -2-methyl-propan-1-one, and 2,4,6-trimethyl Benzoyldiphenylphosphine oxide is preferred.

In addition, when the cured product of the active energy ray-curable composition for optical recording media of the present invention is used for an optical recording medium using a laser as a light source, the laser beam necessary for reading is sufficiently applied to the cured product layer. It is preferable to select and use the type and amount of the radical generator so as to pass through. In particular, when laser light having a wavelength of 380 to 800 nm is used as a light source, it is particularly preferable to use a short-wavelength photosensitive radical generator in which the obtained cured product layer hardly absorbs laser light.

  Among the above radical generators, such short wavelength photosensitive radical generators include benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, methylorthobenzoylbenzoate, diethoxyacetophenone, 2-hydroxy -2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, methyl benzoyl formate, etc. Among them, those having a hydroxyl group such as 1-hydroxycyclohexyl phenyl ketone are particularly preferable.

  In addition, these radical generators may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the radical generator is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, still more preferably 2 parts by weight or more, based on 100 parts by weight of the active energy ray-curable compound. Is 10 parts by weight or less, more preferably 9 parts by weight or less, more preferably 7 parts by weight or less, still more preferably 5 parts by weight or less, and particularly preferably 4 parts by weight or less. When the amount is 0.1 parts by weight or more, the active energy ray-curable composition for optical recording media can be sufficiently cured. On the other hand, when the amount is 10 parts by weight or less, the polymerization reaction proceeds at an appropriate rate. Distortion does not occur and the hue is favorable, which is preferable.

When a benzophenone polymerization initiator is used, the amount used is preferably 0.5 parts by weight or more, preferably 2 parts by weight or less, more preferably 1 part by weight or less. When the amount of the benzophenone-based polymerization initiator is large, the volatile components in the cured product of the active energy ray-curable composition for optical recording media increase, and the film thickness may decrease in a high temperature and high humidity environment.
In addition to these radical generators, for example, known sensitizers such as methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, amyl 4-dimethylaminobenzoate, 4-dimethylaminoacetophenone, etc. A sensitizer may be used in combination. A sensitizer may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of the polymerization initiator other than the radical generator include an oxidizing agent, and these polymerization initiators may be used alone or in combination of two or more. The polymerization initiator may contain impurities such as a chlorine atom, a sulfur atom, a phosphorus atom, and a sodium atom, but the content of these impurities is preferably small, and each content is preferably It is 100 ppm or less with respect to a polymerization initiator, More preferably, it is 50 ppm or less, More preferably, it is 30 ppm or less, Most preferably, it is 10 ppm or less.

In addition, when the polymerization reaction is initiated by an electron beam as an active energy ray, the above polymerization initiator can be used, but since it is sufficiently cured without using a polymerization initiator, a radical generator or other polymerization is used. It is preferable not to use an initiator.
1-5. Auxiliary component The active energy ray-curable composition for an optical recording medium of the present invention may contain an auxiliary component such as an additive, if necessary, as long as the effects of the present invention are not significantly impaired. Specific examples of the auxiliary components include stabilizers such as antioxidants, heat stabilizers, or light absorbers; glass fibers, glass beads, silica, alumina, zinc oxide, titanium oxide, mica, talc, kaolin, metal Fillers such as fibers and metal powders; carbon materials such as carbon fibers, carbon black, graphite, carbon nanotubes, fullerenes such as C60 (fillers and carbon materials may be collectively referred to as inorganic components); Antistatic agents, plasticizers, mold release agents, antifoaming agents, leveling agents, antisettling agents, surfactants, thixotropic agents, modifiers such as epoxy group-containing compounds; pigments, dyes, hue modifiers, etc. Coloring agents; Monomers other than the above-mentioned compounds (A) to (D) or / and oligomers thereof, or curing agents, catalysts, curing accelerators and the like necessary for the synthesis of inorganic components. These auxiliary components may be used alone or in combination of two or more. The content of these auxiliary components is usually 20% by weight or less, preferably 10% by weight or less, more preferably 5% by weight or less of the active energy ray-curable composition for optical recording media.

  Among these, silica as a filler that can be used in the active energy ray-curable composition for an optical recording medium of the present invention will be described in detail. Silica here refers to silicon oxide in general, regardless of the ratio of silicon and oxygen, and whether it is crystalline or amorphous. Examples of the silica particles include industrially produced silica particles dispersed in a solvent, or powdered silica particles; silica particles derived and synthesized from raw materials such as alkoxysilanes, and the like. Can be mentioned. Among these, when used in the active energy ray-curable composition for optical recording media of the present invention, it is derived from raw materials such as silica particles dispersed in a solvent, or alkoxysilane, for ease of mixing and dispersion. Synthesized silica particles are preferred.

  The particle diameter of the silica particles is arbitrary, but the number average particle diameter measured by morphological observation using a TEM (transmission electron microscope) is preferably 0.5 nm or more, more preferably 1 nm or more, The thickness is preferably 50 nm or less, more preferably 40 nm or less, still more preferably 30 nm or less, particularly preferably 15 nm or less, and most preferably 12 nm or less. The silica particles are preferably ultrafine particles, but if they are too small, the cohesiveness of the ultrafine particles is extremely increased, and the transparency and mechanical strength of the cured product tend to be extremely decreased.

1-6. Method for producing active energy ray-curable composition The active energy ray-curable composition for optical recording media of the present invention comprises a compound (A), a urethane (meth) acrylate oligomer of (B), and, if necessary, a compound (C ) Urethane (meth) acrylate oligomer, compound (D), polymerization initiator, or auxiliary component, etc. are prepared by stirring and mixing uniformly in a state of blocking active energy rays. The order of addition of each compound at that time is not particularly limited, but it is preferable to add a high viscosity liquid component and / or a solid component to a low viscosity liquid component and stir, and the polymerization initiator is Preferably added last.

In addition, the stirring conditions at that time are not particularly limited, and the stirring temperature is usually normal temperature. When heating, the temperature may be usually 90 ° C. or lower, preferably 70 ° C. or lower. .
1-7. Characteristics of Active Energy Ray Curable Composition for Optical Recording Medium The active energy ray curable composition for optical recording medium of the present invention is measured by an E type viscometer, a B type viscometer, a vibration type viscometer, or the like 25. The viscosity at ° C. is preferably 300 mPa · s or more, more preferably 500 mPa · s or more. Moreover, it is preferably 3000 mPa · s or less, more preferably 2,500 mPa · s or less, and further preferably 1,500 mPa · s or less. When the viscosity is less than or equal to the upper limit value, for example, it becomes easy to form a cured product having a film thickness of 50 μm or more.

  As a method for adjusting the viscosity of the active energy ray-curable composition for optical recording media, a method for adjusting each molecular weight and addition amount of the urethane (meth) acrylate oligomer and the compound (D), and a diluent for the composition , Solvents, thickeners, rheology control agents, and the like, among others, the method of adjusting the molecular weight and / or content of the urethane (meth) acrylate oligomer and the compound (D) is particularly preferable. preferable.

The active energy ray-curable composition for optical recording media of the present invention preferably contains substantially no solvent. This is to prevent bubbles from remaining when the cured film is formed, and to prevent troubles in reading and writing information when the optical information recording medium is formed. “Contains substantially no solvent” means a state in which the content of so-called organic solvent having volatility or a low boiling point is very low, and the content of the solvent in the active energy ray-curable composition for optical recording media is small. Usually, it is preferably 5% by weight or less, more preferably 3% by weight or less, still more preferably 1% by weight or less, and particularly preferably 0.1% by weight or less. For simplicity, it means a state in which no odor of the organic solvent is observed.

When the active energy ray-curable composition for optical recording media of the present invention contains water, the water content in the active energy ray-curable composition is preferably 1% by weight or less, more preferably 0.5% by weight. Hereinafter, it is more preferably 0.1% by weight or less.
2. Cured product The cured product of the present invention is a cured product obtained by irradiating an active energy ray-curable composition for optical recording media with active energy rays.

2-1. Manufacturing method of hardened | cured material The hardened | cured material of this invention is obtained by what is called "active energy ray hardening" which irradiates an active energy ray (electromagnetic wave and an electron beam), and starts a polymerization reaction. There is no restriction | limiting in particular in the form of a polymerization reaction, For example, well-known polymerization forms, such as radical polymerization, anionic polymerization, cationic polymerization, and coordination polymerization, can be used. Of these polymerization modes, radical polymerization is particularly preferable from the viewpoint of the homogeneity of the product and the like due to the initiation of the polymerization reaction proceeding homogeneously and in a short time within the polymerization system.

  Here, the active energy ray is an electromagnetic wave (gamma ray, X-ray, ultraviolet ray, visible ray, infrared ray) that acts on a polymerization initiator that initiates a necessary polymerization reaction to generate a chemical species that initiates the polymerization reaction. , A microwave, etc.), or an electron beam extracted from a particle accelerator of usually 20 to 2000 kV. An example of the active energy ray preferably used in the present invention is preferably an ultraviolet ray, a visible ray, and an electron beam, most preferably an ultraviolet ray, and an electron because an appropriate amount of energy is obtained and a general-purpose light source can be used. Is a line.

  When ultraviolet rays are used as the active energy rays, it is preferable to use as the polymerization initiator a photo radical generator that generates radicals by ultraviolet rays within the aforementioned polymerization initiation. At this time, a sensitizer may be used in combination as necessary. The wavelength of the ultraviolet rays used is preferably 200 nm or more, more preferably 240 nm or more, and preferably 400 nm or less, more preferably 350 nm or less.

The device for irradiating ultraviolet rays is not particularly limited, and known devices such as a xenon lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a metal halide lamp, and an ultraviolet lamp having a structure for generating ultraviolet rays by a microwave can be used. It can be preferably used.
The integrated light quantity of the active energy ray, preferably 100 mJ / cm ² or more, more preferably 500 mJ / cm ² or higher, preferably 5000 mJ / cm ² or less, more preferably irradiated with 2000 mJ / cm ² or less. If the integrated light quantity is within this range, it can be appropriately selected depending on the composition of the active energy ray-curable composition.

  The irradiation time of the active energy ray is preferably 1 second or longer, more preferably 10 seconds or longer, and preferably 3 hours or shorter, and more preferably 1 hour or shorter in terms of reaction promotion and productivity. When the irradiation energy or irradiation time of the active energy ray is extremely small, the heat resistance and mechanical properties of the cured product may not be sufficiently exhibited due to incomplete polymerization. On the other hand, when it is extremely excessive, deterioration such as deterioration of hue due to light such as yellowing may occur.

The irradiation with the active energy ray may be performed in one step or may be performed in a plurality of steps. As the radiation source, a diffusion radiation source in which active energy rays spread in all directions is usually used. The irradiation of active energy rays is usually performed by fixing the active energy ray source in a state where the active energy ray curable composition for an optical recording medium shaped in a mold is fixed or left standing or conveyed by a conveyor. Leave it stationary. Also, an active energy ray-curable composition for optical recording media is applied onto an appropriate substrate (for example, resin, metal, semiconductor, glass, paper, etc.) to form a coating film, which is irradiated with active energy rays. It is also possible to obtain a cured film by curing the coating film.

  In addition, when an electron beam is used as the active energy ray, the electron beam irradiation apparatus used for irradiation is not particularly limited, but examples thereof include a curtain type, an area beam type, a broad beam type, and a pulse beam type. The acceleration voltage at the time of irradiation is preferably 10 kV or more, more preferably 100 kV or more, and preferably 1,000 kV or less, more preferably 200 kV or less. Although the light source and irradiation device for electron beam irradiation are expensive, there are advantages that the use of a polymerization initiator can be omitted and that the polymerization is not hindered by oxygen and therefore the surface hardness is good. A cured product having excellent properties, particularly tensile elongation, can be obtained.

2-2. Characteristics of cured product The cured product of the active energy ray-curable composition for optical recording media of the present invention usually exhibits the property that it does not melt itself and is insoluble in a solvent, etc. However, it has properties advantageous for the use of optical members and is excellent in adhesion and surface hardness. Specifically, it exhibits low optical distortion (low birefringence), high light transmittance, mechanical strength, dimensional stability, high adhesion, high surface hardness, and a certain level of heat and humidity resistance, and cures. Shrinkage is small. However, the hardened | cured material of this invention should just obtain a desired characteristic among the above as needed, and does not necessarily need to satisfy | fill all the characteristics.

  The film thickness of the cured product of the present invention can be selected according to the purpose, but when used for applications such as optical recording media, it is preferably 10 μm or more, more preferably 20 μm or more, more preferably It is 30 μm or more, more preferably 70 μm or more, particularly preferably 85 μm or more, preferably 300 μm or less, more preferably 130 μm or less, and even more preferably 115 μm or less. The range described here is preferable because the balance between the influence on the reading and writing of information due to dust and the like and the transmittance is good.

The light transmittance of the cured product of the present invention is a light transmittance per optical path length of 0.1 mm at a wavelength of 550 nm when a cured product having a film thickness of 100 μm obtained by irradiating an active energy ray of 1000 mJ / cm ² as an integrated light amount. The rate is preferably 85% or more, more preferably 89% or more, and the upper limit is not limited. Further, the light transmittance per optical path length of 0.1 mm at a wavelength of 400 nm is preferably 85% or more, more preferably 89% or more, and the upper limit is not limited. When the light transmittance is high, transparency as a cured product is high, and it is preferable that no error occurs when the recorded information is read when used in an optical recording medium. The light transmittance can be measured at room temperature by a known method using, for example, an HP8453 type ultraviolet / visible absorptiometer manufactured by Hewlett-Packard Company.

  In order to set the light transmittance of the cured product of the present invention within the above range, it is preferable to use a component having a high light transmittance as each component constituting the active energy ray-curable composition for optical recording media. Furthermore, those having a small amount of impurities such as colored substances and decomposed substances in each component are preferred. Moreover, the thing with little catalyst amount at the time of manufacture is preferable. These are particularly effective for not reducing the light transmittance in the visible light region. Furthermore, it is preferable to select an aliphatic or alicyclic skeleton having no aromatic ring in each component. These are particularly effective for preventing the light transmittance in the ultraviolet region from being lowered.

Further, the cured product of the present invention preferably has a tensile elastic modulus at 25 ° C. of 500 MPa or more as a cured product having a film thickness of 100 μm obtained by irradiating an active energy ray of 1000 mJ / cm ² as an integrated light amount. The pressure is more preferably 1,000 MPa or more, more preferably 4,000 MPa or less, and still more preferably 3,000 MPa or less. When the tensile elastic modulus is 500 MPa or more, load resistance tends to be good. On the other hand, when the tensile elastic modulus is 4,000 MPa or less, deformation hardly occurs, warpage is small when a laminate is formed, and delamination between layers occurs. This is preferable because it tends to be less likely to occur.

The active energy ray-curable composition for optical recording media of the present invention is irradiated with ultraviolet rays of 500 mJ / cm ² using a high-pressure mercury lamp having an irradiance of 400 mW / cm ² at a wavelength of 254 nm under the condition of an oxygen concentration of 20%. In the cured film obtained by irradiating so as to obtain an integrated amount of light, the dynamic storage elastic modulus is preferably 2500 MPa or more at 25 ° C. and 100 MPa or less at 70 ° C. The dynamic storage elastic modulus is obtained by applying a strain or stress that changes (vibrates) with time to the cured film, thereby measuring the stress or strain generated in the cured film. The dynamic storage elastic modulus is more preferably 2700 MPa or more at 25 ° C., further preferably 3000 MPa or more, more preferably 5000 MPa or less, still more preferably 4000 MPa or less. More preferably, it is 100 MPa or less at 70 ° C., further preferably 50 MPa or less, and more preferably 10 MPa or more.

The surface hardness of the cured product of the present invention is a surface hardness according to a pencil hardness test according to JIS K5600-5-4, preferably 6B or more, more preferably 4B or more, still more preferably B or more, and particularly preferably HB. That's it.
Furthermore, the surface hardness of the hard coat layer when a general hard coat agent is laminated on the cured product of the present invention is preferably B or more, more preferably HB or more, and still more preferably H or more. Since the cured product of the present invention has a high surface hardness, it is effective to laminate a general hard coating agent because it has a particularly high surface height.

3. Laminated body The laminated body of this invention is a laminated body formed by laminating | stacking the cured film which consists of hardened | cured material of this invention on a base material.
Normally, a laminate with multiple layers made of different materials has different effects when subjected to an environment such as temperature and humidity in each layer. Warping occurs. In the laminated body of this invention, the deformation | transformation of such a laminated body can be suppressed and the curvature of the laminated body accompanying an environmental change can be made small.

Although it does not specifically limit as a base material of the laminated body of this invention unless the effect of this invention is impaired, A plastic base material or a transparent base material is mentioned.
Examples of the plastic substrate include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polymethyl methacrylate (PMMA), or methyl methacrylate (MMA) copolymer (for example, methyl methacrylate-styrene copolymer resin ( MS resin)), polycarbonate, special polycarbonate (for example, Teijin Pure Ace), triacetyl cellulose, acrylonitrile butadiene styrene copolymer resin (ABS resin), modified polyolefin resin, hydrogenated polystyrene resin, cycloolefin-based transparent resin (for example, ASR made by JSR, ZEONOR made by Nippon Zeon, etc.). Alternatively, as other examples of the transparent substrate, thermosetting or photocurable transparent resins (for example, transparent epoxy resins, transparent urethane resins, thermosetting acrylic resins, photocurable acrylic resins, thermosetting) Other cured organic / inorganic hybrid resins and cured products such as various photocurable organic / inorganic hybrid resins). Of these plastic substrates, polycarbonate and special polycarbonate are preferred for optical recording media.

These base materials may be in the form of molded articles (articles), or may be formed into desired articles after being formed into a laminate. Moreover, you may interpose another layer between a base material and an application surface.
The method for forming the cured film made of the cured product of the present invention is not particularly limited, and the cured film made of the composition of the present invention may be formed and then bonded to the substrate, or based on the composition of the present invention. A method may be used in which a coating film is formed by applying to a material and cured to form a cured film.

Preferred examples of the coating method include spin coating, dip coating, flow coating, spray coating, bar coating, gravure coating, roll coating, blade coating, and air knife coating.
After a coating film is formed on the substrate by the above coating method, a volatile component is removed by heating and drying, and then irradiation with active energy rays yields a cured film.

The type of active energy ray and the irradiation method are the same as those in the above-described method for producing a cured product. A cured film cured with such active energy rays is particularly preferable because of its excellent balance between productivity and physical properties.
4). Optical Recording Medium The active energy ray-curable composition for optical recording medium and the cured product and laminate of the present invention are suitable as a material for optical recording media described below, particularly as a material for forming a protective layer of an information recording layer. Used for

  Currently, optical recording media generally used include read-only media (ROM media), write-once media that can be recorded only once (WriteOnce media), and rewritable media that can repeatedly perform recording and erasure. The active energy ray-curable composition for an optical recording medium and the active energy ray-cured product of the present invention can be applied to any of these media (Rewriteable media).

  These optical recording media employ a layer structure according to their intended use. For example, in a read-only medium, a single layer containing a metal such as aluminum, silver, gold or the like is usually formed on a substrate on which unevenness for reproduction is formed. Further, in a write-once medium, a recording / reproducing functional layer in which a reflective layer containing a metal such as aluminum, silver or gold and a recording layer containing an organic dye are usually laminated on a substrate in this order. Is formed. In a rewritable medium, a reflective layer containing a metal such as aluminum, silver or gold, a dielectric layer, a recording layer containing an organic dye, and a dielectric layer are usually formed on a substrate. Are formed in this order. The active energy ray-curable composition for optical recording media and the cured product thereof according to the present invention are provided on a single layer in a read-only medium, on a recording / reproducing functional layer in a write-once medium, and in a rewritable medium. It is suitable for use as a protective layer formed on the recording / reproducing functional layer.

  On the other hand, the wavelength of the laser light as the recording / reproducing light for recording / reproducing of the optical recording medium uses light of the optimum wavelength according to the standard such as CD, DVD, Blu-ray disc, HDDVD and the like. In addition, with the recent popularization of rich contents, the demand for higher density and higher capacity of optical recording media is increasing, and research using a blue laser with a shorter wavelength has been actively conducted. This next-generation high-density optical recording medium using a blue laser is an optical recording in which a recording / reproducing functional layer including a dielectric layer, a recording layer, a reflective layer, etc. is formed on a substrate, and a protective layer is formed thereon. Recording / reproducing light having a wavelength of usually 350 nm or more, preferably 380 nm or more, and usually 450 nm or less, preferably 430 nm or less, which is a medium. For this next-generation high-density optical recording medium, the active energy ray-curable composition for optical recording medium of the present invention and the cured product thereof can be particularly suitably used.

  The active energy ray-curable composition for optical recording media of the present invention and the laminate or optical recording medium in which the cured product is used include, for example, a two-layer type having two recording layers and two reflective layers. A layer structure may be adopted. In the case of this two-layer type, one layer may be laminated on the substrate in order, or two layers obtained by laminating a pair of a recording layer and a reflective layer may be bonded together. Good. Further, a three-layer structure may be adopted, and the bonding may be performed through an adhesive layer. Furthermore, if necessary, a hub may be attached and incorporated in the cartridge.

  The thickness of the protective layer is usually 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, still more preferably 70 μm or more, particularly preferably 85 μm or more, and usually 300 μm or less, preferably 130 μm or less, more preferably 115 μm. It is as follows. If the film thickness is in such a range, the influence of dust and scratches attached to the surface of the protective layer can be reduced, and the thickness of the recording / reproducing functional layer is sufficient to protect the moisture from outside air and the like. be able to. Moreover, a uniform film thickness can be easily formed by a general coating method used in spin coating or the like.

Specific examples of the present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited by these examples unless it exceeds the gist.
<Evaluation method>
[Method of measuring molecular weight and content of compounds (A) and (B)]
Using gel permeation chromatography (HLC-8120GPC manufactured by Tosoh Corporation), column (TskGEL SuperH 1000, 2000, 3000), detector RI (refractive index), eluent tetrahydrofuran (THF), flow rate 0.5 ml / min. The molecular weight distribution was measured, the peak corresponding to the molecular weight of the compound (A) or (B) was determined from the molecular weight distribution measured in terms of standard polystyrene, the peak area ratio of those peaks was calculated, and the content was determined.

The sample for measurement was adjusted to be a THF solution in which the composition solution or active energy ray-curable composition was 0.2% by weight.
[viscosity]
According to JIS K5600-2-3, the viscosity at 25 ° C. was measured with an E-type viscometer.

[Pencil hardness]
According to JIS K5600-5-4, the pencil hardness on the surface of the laminate was measured. In addition, although the pencil hardness of the hard-coat layer surface of a laminated body was measured here, these values are values reflecting the surface hardness of the cured film which consists of hardened | cured material of this invention.
[Initial tilt]
The laminate was allowed to stand at 25 ° C. and 50% RH for 24 hours, and then the tilt at a point of 58 mm in the radial direction from the center of the laminate was measured using a displacement sensor LT-9010 (manufactured by KEYENCE).

Tilt expresses the warpage from the flat surface on the outermost periphery by an angle, and is a value indicating the warpage of the laminate. Each numerical value of the initial tilt represents the warpage of the substrate alone and the amount of warpage displacement when the laminate is formed.
The upward warping when the protective layer of the laminate was down was positive, and the downward warping was negative. The substrate used was originally warped by plus 0.3 °.

[Low temperature tilt]
The laminate at which the initial tilt was measured was left to stand at a temperature of 5 ° C. and a relative humidity of 45% for 24 hours, and the tilt at a point of 58 mm in the radial direction from the center of the laminate was measured. Each numerical value of the low temperature tilt represents an amount of displacement from the warp of the laminate in which the initial tilt is measured. It is preferable that the absolute value of the low temperature tilt is small because deformation of the laminated body due to temperature change is small.

[Humidity tilt]
The laminate whose initial tilt was measured was allowed to stand for 24 hours at a temperature of 25 ° C. and a relative humidity of 90%, and then at a point of 58 mm in the radial direction from the center of the laminate immediately after being placed at a temperature of 25 ° C. and a relative humidity of 50% (0 hour). Then, the change in tilt at the same point after 1, 2, 3, 5, 9 hours elapsed was measured. The displacement amount at the time when the absolute value of the displacement amount from the tilt at the time of 0 hour was the maximum was defined as the humidity tilt. It is preferable that the humidity tilt has a smaller absolute value because there is less deformation of the laminate due to a sudden change in humidity.

[Tensile modulus at humidity change]
Tensilon (RTC-1210A, manufactured by Orientec Co., Ltd.) was used to measure the tensile elastic modulus of the cured film cut to a width of 10 mm. When the distance between the marked lines is 50 mm and the tensile speed is 1 mm / min, the maximum value of the displacement of the stress when the elongation of the cured film is 0 to 1% (that is, the slope of the tangent in the relational curve of the elongation stress of the cured film) The maximum value was calculated as the tensile elastic modulus.

  The cured film was allowed to stand for 24 hours under conditions of a temperature of 23 ° C. and a relative humidity of 45%, and then the tensile elastic modulus was measured to obtain the initial tensile elastic modulus. Further, the cured film was allowed to stand at a temperature of 23 ° C. and a relative humidity of 95% for 15 hours, and then immediately after being placed in an environment of a temperature of 23 ° C. and a relative humidity of 45% (0 hour), and after 1 hour and after 24 hours. The elastic modulus was measured, and it was set as the tensile elastic modulus after moisture release (0), the tensile elastic modulus after moisture release (1), and the tensile elastic modulus after moisture release (24).

[Dehydration shrinkage]
The cured film having a strip shape of 25 × 5 mm was measured in a tensile mode using a thermomechanical analyzer (“TMA8310” manufactured by Rigaku Corporation) with a water vapor generator (“HUM-1B” manufactured by Rigaku Corporation). After mounting the cured film in a chamber set at a temperature of 25 ° C. and a relative humidity of 0% so that the distance between the marked lines becomes 20 mm, the chamber was kept at a temperature of 25 ° C. and a relative humidity of 90% for 5 hours. Thereafter, the inside of the chamber was changed to a temperature of 25 ° C. and a relative humidity of 45%, and the dimensional change of the cured film was measured over time. The dimensional change of the cured film was measured from 0 hours at a temperature of 25 ° C. and a relative humidity of 45%, and the dimensional change end point was 0 hours when the change for 1 second was 0.1% or less of the total change. The amount of change from the end point to the end point is taken as the final contraction amount. The amount of shrinkage at each time point after 0.5 hours, 0.75 hours, 1 hour, and 2 hours with respect to this final shrinkage amount is dehydration shrinkage rate (0.5), dehydration shrinkage rate (0.75), and dehydration shrinkage, respectively. The rate (1) and the dehydration shrinkage rate (2) were used.

<Production Example 1> Synthesis of urethane acrylate oligomer mixture (a) 222 g of isophorone diisocyanate was placed in a four-necked flask, heated to 70 to 80 ° C in an oil bath, and gently stirred until the temperature became constant. When the temperature became constant, 79 g of 1,6-hexanediol was added dropwise using a dropping funnel, and the mixture was stirred for 2 hours while maintaining the temperature at 80 ° C. After the temperature is lowered to 70 ° C., 0.1 g of p-methoxyhydroquinone and 0.04 g of dibutyltin dioctoate are added, and 81 g of hydroxyethyl acrylate is added dropwise using a dropping funnel. The mixture was stirred for a time to synthesize a urethane acrylate oligomer mixture (a). Next, 164 g of tetrahydrofurfuryl acrylate (THFA, manufactured by Osaka Organic Chemical Co., Ltd.) is added as a compound (D) and diluted so that the urethane acrylate oligomer mixture (a) becomes 70% by weight, and the urethane acrylate oligomer mixture (a) is contained. A composition solution was prepared.

At this time, the ratio of the isocyanate group of isophorone diisocyanate to the hydroxyl group of 1,6-hexanediol (NCO / OH ratio) is 1.5.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (a) in a composition liquid was measured by GPC, the number average molecular weight was 1300 and the weight average molecular weight was 2060. Moreover, content of the compound (A) in the obtained composition liquid is 15.0 weight%, content of a compound (B) is 5.0 weight%, (A) / (B) = 3.0 (weight) Ratio).

<Production Example 2> Synthesis of urethane acrylate oligomer mixture (b) A urethane acrylate oligomer mixture (b) was prepared in the same manner as in Production Example 1 except that 79 g of 1,6-hexanediol was changed to 107 g of 1,9-nonanediol. Synthesized. Next, 176 g of THFA was added as the compound (D) and diluted such that the urethane acrylate oligomer mixture (b) was 70% by weight to prepare a composition liquid containing the urethane acrylate oligomer mixture (b).

At this time, the NCO / OH ratio is 1.5.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (b) in a composition liquid was measured by GPC, the number average molecular weight was 1490 and the weight average molecular weight was 2360. Further, the content of the compound (A) in the obtained composition liquid is 17.1% by weight, the content of the compound (B) is 3.4% by weight, and (A) / (B) = 5.0 (weight) Ratio).

<Production Example 3> Synthesis of urethane acrylate oligomer mixture (c) A urethane acrylate oligomer mixture was prepared in the same manner as in Production Example 1 except that 79 g of 1,6-hexanediol was changed to 79 g of 3-methyl-1,5-pentanediol. (C) was synthesized. Next, 164 g of THFA was added as the compound (D) and diluted so that the urethane acrylate oligomer mixture (c) was 70% by weight to prepare a composition liquid containing the urethane acrylate oligomer mixture (c).

At this time, the NCO / OH ratio is 1.5.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (c) in a composition liquid was measured by GPC, the number average molecular weight was 1240 and the weight average molecular weight was 1970. Further, the content of the compound (A) in the obtained composition liquid was 14.1% by weight, the content of the compound (B) was 5.8% by weight, and (A) / (B) = 2.4 (weight) Ratio).

<Production Example 4> Synthesis of urethane acrylate oligomer mixture (d) Production Example except that 79 g of 1,6-hexanediol was changed to 89 g of 3-methyl-1,5-pentanediol and 81 g of hydroxyethyl acrylate was changed to 61 g. In the same manner as in 1, a urethane acrylate oligomer mixture (d) was synthesized. Next, 159 g of THFA was added as the compound (D) and diluted so that the urethane acrylate oligomer mixture (d) was 70% by weight to prepare a composition liquid containing the urethane acrylate oligomer mixture (d).

At this time, the NCO / OH ratio is 1.3.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (d) in a composition liquid was measured by GPC, the number average molecular weight was 1690 and the weight average molecular weight was 2820. Further, the content of the compound (A) in the obtained composition liquid is 8.5% by weight, the content of the compound (B) is 2.8% by weight, and (A) / (B) = 3.0 (weight) Ratio).

<Production Example 5> Synthesis of urethane acrylate oligomer mixture (e) 1,6-hexanediol 79 g was changed to 70 g, and hydroxyethyl acrylate 8
A urethane acrylate oligomer mixture (e) was synthesized in the same manner as in Production Example 1 except that 1 g was changed to 100 g. Next, 168 g of THFA was added as the compound (D), and the urethane acrylate oligomer mixture (e) was diluted to 70 wt% to prepare a composition liquid containing the urethane acrylate oligomer mixture (e).

At this time, the NCO / OH ratio is 1.7.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (e) in a composition liquid was measured by GPC, the number average molecular weight was 1050 and the weight average molecular weight was 1550. Further, the content of the compound (A) in the obtained composition liquid is 20.5% by weight, the content of the compound (B) is 8.4% by weight, and (A) / (B) = 2.4 (weight) Ratio).

<Comparative Production Example 1> Synthesis of urethane acrylate oligomer mixture (f) Urethane acrylate oligomer in the same manner as in Production Example 1 except that 79 g of 1,6-hexanediol was changed to 59 g and 81 g of hydroxyethyl acrylate was changed to 122 g. Mixture (f) was synthesized. Next, 173 g of THFA was added as the compound (D) and diluted such that the urethane acrylate oligomer mixture (f) was 70% by weight to prepare a composition liquid containing the urethane acrylate oligomer mixture (f).

At this time, the NCO / OH ratio is 2.0.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (f) in a composition liquid was measured by GPC, the number average molecular weight was 840 and the weight average molecular weight was 1180. Further, the content of the compound (A) in the obtained composition liquid is 25.0% by weight, the content of the compound (B) is 14.4% by weight, and (A) / (B) = 1.7 (weight) Ratio).

<Comparative Production Example 2> Synthesis of urethane acrylate oligomer mixture (g) 271.2 g of isophorone diisocyanate produced by the urea method was placed in a four-necked flask and heated to 70-80 ° C in an oil bath, and the temperature was kept constant. Gently stirred until When the temperature becomes constant, 64.5 g of 1,6-hexanediol, 32.5 g of polytetramethylene ether glycol having an average molecular weight of 650 (“PTMG650” manufactured by Mitsubishi Chemical Corporation), polytetramethylene ether glycol having an average molecular weight of 2000 (Mitsubishi) After mixing 55.0 g of “PTMG2000” manufactured by Kagaku Co., Ltd., this was added dropwise with a dropping funnel and stirred for 2 hours while maintaining the temperature at 90 ° C. After the temperature was lowered to 70 ° C., 0.2 g of p-methoxyhydroquinone and 0.03 g of dibutyltin dioctoate were added, and 148.4 g of hydroxyethyl acrylate was dropped with a dropping funnel. The absorption wavelength (2280 cm) of NCO group was measured by IR. ^The mixture was stirred at the same temperature until the ^-1 ) disappeared to synthesize a urethane acrylate oligomer mixture (g). Next, while lowering the temperature to 30 ° C., 342.7 g of tetrahydrofurfuryl acrylate (THFA, manufactured by Osaka Organic Chemicals) as a compound (D), 1,9-nonane diacrylate (“A-NOD” manufactured by Shin-Nakamura Chemical Co.) 49 0.03 g and α-hydroxycyclohexyl-phenyl ketone 33.7 g as a polymerization initiator were added, and the mixture was further stirred at room temperature for 3 hours to obtain a uniform liquid active energy ray-curable composition. In addition, let the part except the polymerization initiator in the obtained active energy ray-curable composition here be a composition liquid containing a urethane acrylate oligomer mixture (g).

At this time, the ratio of the isocyanate group of isophorone diisocyanate to the hydroxyl group of 1,6-hexanediol and polytetramethylene ether glycol (NCO / OH ratio) is 2.0.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (g) in the active energy ray-curable composition was measured by GPC, the number average molecular weight was 950 and the weight average molecular weight was 2000. The content of the compound (A) in the composition liquid containing the urethane acrylate oligomer mixture (g) is 16.9% by weight, the content of the compound (B) is 11.5% by weight, (A
) / (B) = 1.5 (weight ratio).

<Example 1>
In a 200 cc flask, 70 g of the composition liquid containing the urethane acrylate oligomer mixture (a) prepared above, 25 g of THFA, 5 g of 1,9-nonanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), 3 g of α-hydroxycyclohexyl-phenyl ketone Were weighed and mixed at room temperature using a stirring blade for 5 hours to obtain a uniform liquid active energy ray-curable composition. Table 2 shows the composition of the obtained active energy ray-curable composition.

Moreover, the viscosity of the obtained composition was 1010 m · Pa.
Next, the active energy ray-curable composition is coated on a substrate having a thickness of 1.1 mm and a diameter of 120 mm on a circular polycarbonate plate surface on which a 100 nm thick Ag reflective layer is formed by sputtering. After applying by spin coating so as to be 100 ± 10 μm, UV light is accumulated at 500 mJ / cm ² using a high-pressure mercury lamp with an irradiance of 400 mW / cm ² at a wavelength of 245 nm under the condition of an oxygen concentration of 20%. Then, a protective layer was formed by irradiation with a UV irradiation apparatus (JU-C1500, manufactured by JATEC). Further, a hard coat layer composition having the following composition was applied thereon as a hard coat layer by spin coating so that the thickness of the coating film was 4 ± 1 μm, and ultraviolet rays were applied at 1000 mJ / cm under the same conditions as described above. Irradiated so as to obtain an integrated light quantity of ² , and a cured laminate was created.

The obtained laminate was evaluated for pencil hardness, initial tilt, low temperature tilt and humidity tilt. The results are shown in Table 3.
<< Hard Coat Layer Composition >>
90 g of dipentaerythritol (hexa / penta) acrylate (“Kayarad DPHA” manufactured by Nippon Kayaku Co., Ltd.), methyl methacrylate, perfluorooctylethyl methacrylate, and mercapto groups at both ends as water / oil repellency / low friction agents Of polydimethylsiloxane (“X-22-167B” manufactured by Shin-Etsu Chemical Co., Ltd.) and glycidyl methacrylate copolymer (25/40/5/30 (weight ratio)) (35% propylene glycol monomethyl ether) Solution) 28.57 g and 1 g of 1-hydroxycyclohexyl phenyl ketone (“Irgacure-184” manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator in an amount of 40 wt% solid content of propylene glycol monomethyl ether acetate Only for 2 hours at room temperature in the dark They were prepared by.

In addition, it was as follows when the pencil hardness of the cured film surface which hardened the composition for hard-coat layers used here on the base material as a single layer was measured.
On a 0.1 mm-thick polyethylene terephthalate (PET) film, a coating film made of the obtained hard coat layer composition having a thickness of 8 ± 1 μm was formed. A cured film was formed by using a high-pressure mercury lamp having an irradiance of 400 mW / cm ² and irradiating ultraviolet rays so as to have an integrated light quantity of 1000 mJ / cm ² . It was HB when the pencil hardness of the surface of the cured film was measured according to JIS K5600-5-4.

<Examples 2 to 5, Comparative Example 1>
In the same manner as in Example 1, an active energy ray-curable composition was prepared so as to have the composition shown in Table 2. The viscosity of each composition is shown in Table 3.
A laminate was obtained in the same manner as in Example 1 except that the active energy ray-curable composition obtained in each example was used, and pencil hardness, initial tilt, low temperature tilt and humidity tilt were evaluated. It was shown to.

<Comparative example 2>
Except that the active energy ray-curable composition obtained in Comparative Production Example 2 was used, the viscosity of the composition, the pencil hardness of the laminate, the initial tilt, the low temperature tilt, and the humidity tilt were measured in the same manner as in Example 1. The results are shown in Table 3.

<Production Example 6>
Synthesis of urethane acrylate oligomer mixture (h) 270 g of hexamethylene diisocyanate trimer (manufactured by Mitsubishi Chemical Corporation, NY730S), 0.3 g of p-methoxyhydroquinone and 0.06 g of dibutyltin dioctoate are placed in a four-necked flask, and an oil bath The mixture was heated to 70-80 ° C. and gently stirred until the temperature became constant. When the temperature became constant, 690 g of Blemmer AP400 (polypropylene glycol acrylic acid adduct, manufactured by NOF Corporation) was dropped with a dropping funnel, and while maintaining the temperature at 80 ° C., the absorption wavelength of the isocyanate group (2280 cm ^{− The} mixture was stirred at the same temperature until ¹ ) disappeared to obtain a urethane acrylate oligomer mixture (h).

At this time, the NCO / OH ratio is 1.0.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (h) in a composition liquid was measured by GPC, the number average molecular weight was 2580 and the weight average molecular weight was 4470. Moreover, content of the compound (A) and the compound (B) in the obtained composition liquid was 0%.
<Example 6>
In a 200 cc flask, 71 g of the composition liquid containing the urethane acrylate oligomer mixture (c) prepared above, 5 g of the urethane acrylate oligomer mixture (h), 4 g of THFA, 1,9-nonanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) ) 10 g, 10 g of phenoxyethyl acrylate (produced by Osaka Organic Chemical Co., Ltd.), 3 g of α-hydroxycyclohexyl-phenyl ketone, and mixed for 5 hours using a stirring blade at room temperature to obtain a uniform liquid active energy ray-curable composition. Obtained. The composition of the obtained active energy ray-curable composition is shown in Table 4.

Moreover, the viscosity of the obtained composition was 2200 m · Pa.
Next, a laminate was obtained in the same manner as in Example 1 except that the active energy ray-curable composition obtained above was used, and pencil hardness, initial tilt, low temperature tilt and humidity tilt were evaluated, and the results were shown. This is shown in FIG.
Further, after applying the above active energy ray-curable composition on a 0.1 mm thick polyethylene terephthalate (PET) film by spin coating so that the thickness of the coating film becomes 100 ± 10 μm, the condition of oxygen concentration of 20% Under UV irradiation using a high-pressure mercury lamp with an irradiance of 400 mW / cm ² at a wavelength of 245 nm and irradiation with a UV irradiation device (JU-C1500, manufactured by JATEC) so as to obtain an integrated light quantity of 1500 mJ / cm 2, curing. A film was formed. The cured film was peeled from the PET film, and the tensile modulus at the time of humidity change was measured. The results are shown in Table 5.

<Reference Example 1>
In a 200 cc flask, 71 g of the composition liquid containing the urethane acrylate oligomer mixture (c) prepared above, 5 g of the urethane acrylate oligomer mixture (h), THF
Weigh 4 g of A, 10 g of 1,9-nonanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), 10 g of phenoxyethyl acrylate (manufactured by Osaka Organic Chemical Co., Ltd.), and 3 g of α-hydroxycyclohexyl-phenyl ketone, and use a stirring blade at room temperature. For 5 hours to obtain a uniform liquid active energy ray-curable composition. The composition of the obtained active energy ray-curable composition is shown in Table 4.

Moreover, the viscosity of the obtained composition was 2200 m · Pa.
Next, the active energy ray-curable composition is coated on a substrate having a thickness of 1.1 mm and a diameter of 120 mm on a circular polycarbonate plate surface on which a 100 nm thick Ag reflective layer is formed by sputtering. After applying by spin coating so as to be 100 ± 10 μm, using a pulse UV irradiation curing device (RC-801, manufactured by Xenon) under the condition of an oxygen concentration of 20%, after irradiation with 10 pulses UV, The hard coat layer composition having the composition described above was applied as a hard coat layer by spin coating so that the thickness of the coating film was 4 ± 1 μm, and a cured body was prepared under the same conditions as described above, and the pencil hardness The initial tilt, the low temperature tilt, and the humidity tilt were evaluated, and the results are shown in Table 5.

  Further, after applying the above active energy ray-curable composition on a 0.1 mm thick polyethylene terephthalate (PET) film by spin coating so that the thickness of the coating film becomes 100 ± 10 μm, the condition of oxygen concentration 20% A cured film was formed by irradiation with 10 pulses of UV using a pulsed UV irradiation curing device (RC-801, manufactured by Xenon). The cured film was peeled off from the PET film, and the tensile elastic modulus and dehydration shrinkage rate when the humidity was changed were measured. The results are shown in Table 5.

<Reference Example 2>
Except for using the active energy ray-curable composition obtained in Comparative Production Example 2, the pencil hardness, initial tilt, low temperature tilt, humidity tilt, and change in humidity of the cured film were the same as in Reference Example 1. The tensile modulus at the time was evaluated, and the results are shown in Table 5.

When the active energy ray-curable composition for optical recording media of the present invention is cured to form a laminate, there is little deformation immediately after a sudden change in environmental temperature and environmental humidity, and it has sufficient surface hardness. In addition, it is possible to provide a laminate having excellent wear resistance and load resistance. In particular, it is an active energy ray-curable composition for an optical recording medium suitable for obtaining a protective layer having high recording film protection in an optical recording medium.

  From this, the laminated body formed by laminating the cured product obtained from the active energy ray-curable composition for optical recording media of the present invention can stably read and write information even if the environment such as temperature and humidity changes. It can be effectively applied to optical recording media such as Blu-ray discs.

Claims (6)

An active energy ray-curable composition for an optical recording medium comprising a monomer having an active energy ray-curable group and / or an oligomer thereof,
A round polycarbonate plate with a thickness of 1.1 mm and a diameter of 120 mm,
A high-pressure mercury lamp having an irradiance of 400 mW / cm ² at a wavelength of 254 nm under a condition of an oxygen concentration of 20% is applied to a coating film made of the active energy ray-curable composition for an optical recording medium and having a thickness of 100 ± 10 μm. A protective layer formed by irradiating with ultraviolet rays so as to obtain an integrated light amount of 500 mJ / cm ² ;
An ultraviolet ray of 1000 mJ / cm ^{2 is applied} to a coating film having a thickness of 4 ± 1 μm made of a composition for a hard coat layer having a pencil hardness of HB, which is cured as a single layer on a substrate, under the same conditions as described above. A hard coat layer formed by irradiation so as to obtain an integrated light quantity of
An active energy ray-curable composition for an optical recording medium, wherein the laminate obtained by laminating the layers satisfies the following (1) and (2).
(1) The pencil hardness of the hard coat layer surface of the laminate is H or higher. (2) The laminate is warped at a point of 58 mm in the radial direction from the center of the laminate after being left for 24 hours at a temperature of 25 ° C. and a relative humidity of 50%. And the absolute value of the amount of displacement with the warpage at the same point after standing for 24 hours at a temperature of 5 ° C. and a relative humidity of 45% is 0.0 ° to 0.6 °. An active energy ray-curable composition for an optical recording medium comprising a monomer having an active energy ray-curable group and / or an oligomer thereof,
A round polycarbonate plate with a thickness of 1.1 mm and a diameter of 120 mm,
Recording / playback functional layer,
A high-pressure mercury lamp having an irradiance of 400 mW / cm ² at a wavelength of 254 nm under a condition of an oxygen concentration of 20% is applied to a coating film made of the active energy ray-curable composition for an optical recording medium and having a thickness of 100 ± 10 μm. A protective layer formed by irradiating with ultraviolet rays so as to obtain an integrated light amount of 500 mJ / cm ² ;
An ultraviolet ray of 1000 mJ / cm ^{2 is applied} to a coating film having a thickness of 4 ± 1 μm made of a composition for a hard coat layer having a pencil hardness of HB, which is cured as a single layer on a substrate, under the same conditions as described above. A hard coat layer formed by irradiation so as to obtain an integrated light quantity of
An active energy ray-curable composition for optical recording media, wherein the laminate in which the layers are laminated in this order satisfies the following (3) and (4).
(3) The pencil hardness of the hard coat layer surface of the laminate is H or more. (4) The laminate is allowed to stand at a temperature of 25 ° C. and a relative humidity of 90% for 24 hours, and further at a temperature of 25 ° C. and a relative humidity of 50%. Displacement from the warp at the time of 0 hour among the warp at the point of 58 mm in the radial direction from the center of the laminate immediately after (0 hour) and the warp at the same point after 1, 2, 3, 5, 9 hours thereafter The absolute value of the displacement amount of the warp of the time when the absolute value of the amount is maximum is 0.0 ° to 0.6 ° The active energy ray-curable composition for optical recording media according to claim 2, wherein the laminate satisfies the following (5).
(5) The laminate was allowed to stand at a temperature of 25 ° C. and a relative humidity of 50% for 24 hours and then warped at a point of 58 mm in the radial direction from the center of the laminate, and further allowed to stand at a temperature of 5 ° C. and a relative humidity of 45% for 24 hours. The absolute value of the amount of displacement with the subsequent warp at the same point is 0.0 ° to 0.6 °.   The active energy ray-curable composition for optical recording media according to any one of claims 1 to 3, wherein the viscosity at 25 ° C is 500 to 3000 mPa · s.   Hardened | cured material obtained by irradiating an active energy ray to the active energy ray curable composition for optical recording media in any one of Claims 1-4.   The laminated body formed by laminating | stacking the cured film which consists of hardened | cured material of Claim 5 on a base material.