JP2009154372A - Laminated sheet and optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminating sheet having a favorable film forming property and excellent thickness accuracy, not causing problems of being brittle, easily damaged, difficult to be handled due to the existence of weak body and so forth even if processed in a film shape, and having excellent secondary workability and reduced in antifouling property to a body to be coated, solvent crack resistance or the like and an optical recording medium obtained by laminating the laminating sheets. <P>SOLUTION: The laminating sheet provided with a structure obtained by laminating a hard coat layer at least on one surface of a base material layer is formed. Each layer is formed of a hardened active energy curing type resin composition. The residual solvent is volatilized under a heating condition of 80°C and 30 min is <100 ppm/g in the laminated sheet. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In recent years, plastic films with small optical distortion have been frequently used and applied in optical products such as displays, electronic devices, information recording members, and the like. The required performance for such a film includes not only the property of optically less distortion, but also resistance to moist heat deformation, adhesion to an adherend, and non-contamination. In particular, in the field of advanced technology such as high-precision parts and optical discs, reliability under severe environmental conditions such as high temperature and high humidity is almost always required, but there is not always satisfactory.

  For example, Patent Document 1 proposes a polycarbonate resin film that is melt-cast with an organic solvent as an optically less distorted film.

  Patent Document 2 discloses the superiority of a coating method, particularly a spin coater method, as a method for processing an active energy ray-curable resin composition.

  Patent Document 3 discloses a sheet with a pressure-sensitive adhesive using a UV curable acrylic resin.

  Furthermore, Patent Document 4 can impart excellent scratch resistance, water resistance and chemical resistance to image paper such as photographs output by a printer and the surface of a display, etc., and has little distortion and image sharpness. The adhesive sheet with a hard coat which hardened urethane acrylate which can improve thickness and can further reduce thickness is described.

JP 2002-309015 A JP 2003-231725 A JP 2006-330714 A International Publication No. 2004/083330 Pamphlet

  In the field of advanced technology such as optical products such as displays, electronic equipment, information recording members, etc., adherends are often oxidative and corrosive, and conventional plastic films with low optical distortion are low in organic materials. A molecular weight component, a residual solvent, etc. may transfer to a to-be-adhered body, and may cause corrosion of a member, or may cause a solvent crack in the film or to-be-attached body.

  In the invention described in Patent Document 1, a methylene chloride solvent is used at the time of film formation, which has a large environmental load and is concerned about residual solvent in the film. The film is provided with a hard coat layer in a separate process. It is necessary and the process is complicated and it is difficult to say that it is practical.

  In addition, in the invention described in Patent Document 2, when a film having a thickness of about 50 to 100 μm is obtained, the thickness accuracy is not sufficient by these methods, and the active energy ray-curable resin composition used is scattered, etc. The loss due to is large and it is hard to say that it is practical.

  The sheet with a pressure-sensitive adhesive described in Patent Document 3 is not designed in consideration of surface hardness and contamination resistance in the embodiment, and is not practical.

  Furthermore, since the adhesive sheet with a hard coat described in Patent Document 4 is diluted with an organic solvent in the embodiment, the composition of each layer is not only negligible in terms of the complexity of the process and the burden on the environment. The total thickness of the sheet is as thin as 50 μm or less and lacks self-supporting properties. Therefore, it is necessary to provide a protective film on both sides, and it is difficult to say that the productivity is good and practical.

  Therefore, the present invention has good film forming properties and thickness accuracy, and even when processed into a film shape, it does not cause problems such as brittleness and breakage, lack of waist and difficulty in handling, and has excellent secondary processability. It is an object of the present invention to provide a laminated sheet with reduced contamination and solvent cracks on the adherend and an optical recording medium obtained by laminating the laminated sheet.

  As a result of intensive studies to solve the above problems, the present inventor uses an active energy ray-curable resin composition, and the amount of residual solvent that volatilizes under heating conditions of 80 ° C. for 30 minutes is 100 ppm / g. It is found that a laminated sheet that includes a base material layer and a hard coat layer made of a cured product of the active energy ray-curable resin composition, and that can prevent solvent cracks and the like on the adherend can be provided. The present invention has been completed. The viscosity at 25 ° C. of the active energy ray-curable resin composition forming the base material layer is 1000 to 10,000 mPa · s, and the viscosity of the active energy ray-curable resin composition forming the hard coat layer at 25 ° C. By adjusting the sheet thickness to 300 mPa · s or less, the laminated sheet can be formed with good thickness accuracy, and even when processed into a film shape, problems such as brittle and fragile, lack of waist and difficulty in handling are not caused. Excellent in next processability, can be both self-supporting and flexible as a sheet, and by setting the viscosity of the base material layer and the hard coat layer in the above range, the layers can be laminated sequentially or collectively. Even when laminating, each layer will not be mixed with other layers more than necessary and will not be contaminated, so each function of the hard coat layer and base material layer constituting the laminated sheet Found that can effectively separated.

  That is, the present invention is (1) a laminated sheet comprising a cured product of an active energy ray-curable resin composition, comprising a structure in which a hard coat layer is laminated on at least one side of a base material layer, The laminated sheet characterized in that the amount of residual solvent volatilized under heating conditions for 30 minutes is less than 100 ppm / g, and (2) the active energy ray-curable resin composition forming the base material layer is at 25 ° C. The active energy ray-curable resin composition having a viscosity of 1000 to 10,000 mPa · s and forming the hard coat layer has a viscosity at 25 ° C. of 300 mPa · s or less. The active energy ray-curable resin composition forming the sheet and (3) the base material layer contains a urethane acrylate having a weight average molecular weight of 1000 or more. (4) The protective sheet for optical discs comprising the laminated sheet according to any one of (1) to (3), (5) The (1) To an optical recording medium formed by laminating at least one laminated sheet according to any one of (3) to (3).

  In addition, the present invention comprises (6) a base material layer and a hard coat layer made of an active energy ray-curable resin composition applied sequentially or collectively on a release film, belt, roll for process, It is a method for producing a laminated sheet that is molded into a film and cured to form each layer by curing the active energy ray-curable resin composition, and the active energy ray-curable resin composition that forms the base layer is The viscosity at 25 ° C. is 1000 to 10,000 mPa · s, and the active energy ray-curable resin composition forming the hard coat layer has a viscosity at 25 ° C. of 300 mPa · s and is heated at 80 ° C. for 30 minutes. It is related with the manufacturing method of the lamination sheet whose residual solvent amount volatilized below is less than 100 ppm / g.

  According to the present invention, the film forming property and the thickness accuracy are good, and even when processed into a film shape, problems such as brittleness and breakage, lack of waist and difficulty in handling do not occur, and excellent in secondary workability. The drying process at the time of film is not required, the burden on the environment is small, and the productivity is not only excellent, but also the concern about contamination and solvent cracks when the film is laminated on the adherend can be reduced. A laminated sheet can be provided, and an optical recording medium obtained by laminating the laminated sheet is excellent in simplicity of lamination, thickness accuracy, and excellent in corrosion resistance to an adherend. Effective in the field of advanced technology such as high-precision parts and optical disks.

  The laminated sheet of the present invention has a structure in which a hard coat layer is laminated on at least one side of a base material layer, and is composed of a cured product of an active energy ray-curable resin composition, heated at 80 ° C. for 30 minutes. If the amount of the residual solvent that volatilizes is less than 100 ppm, it is not particularly limited, and the laminated sheet composed of the cured product of the active energy ray-curable resin composition of the present invention has a drying step during film formation. It becomes unnecessary, the load on the environment is small, and it becomes possible to reduce the concern about contamination and solvent cracks when the laminated sheet is laminated on the adherend. In addition, residual solvent amount is GC-MS (Corporation | Co., Ltd.) as the amount of volatile components per 1g of laminated sheets collected on 80 degreeC and the heating conditions for 30 minutes so that it may describe also in the Example. It is a value measured with Shimadzu Corporation QP-5050A).

  The laminated sheet of the present invention requires that the amount of residual solvent volatilized under heating conditions of 80 ° C. for 30 minutes is less than 100 ppm, preferably less than 80 ppm, and more preferably less than 60 ppm. Is more preferable. By setting it as such a range, generation | occurrence | production of the solvent crack to a to-be-adhered body can be suppressed effectively.

  The active energy ray-curable resin composition is not particularly limited. For example, urethane (meth) acrylate type, epoxy (meth) acrylate type, polyester (meth) acrylate type, which is cured with active energy ray, Examples include polybutadiene (meth) acrylate-based and polyol poly (meth) acrylate-based monomer-type and oligomer-type active energy ray-curable resins as main components, and other photopolymerizable monomers and compositions containing photopolymerization initiators. It is done. Specifically, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, 2- (N, N-dimethylamino) ethyl acrylate, 2 -(N, N-diethylamino) ethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, hydroxyethyl methacrylate, 2- (N, N-dimethylamino) ethyl methacrylate , Monofunctional group type monomers such as 2- (N, N-diethylamino) ethyl methacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, pentaerythritol tetramethacrylate, Multi-functional monomer such as dimethylolpropane trimethacrylate, adipic acid / 1,6 hexanediol oligomer diacrylate, phthalic anhydride / propylene oxide oligomer diacrylate, trimellitic acid diethylene glycol oligomer triacrylate, adipic acid / 1, Polyfunctional polyester acrylate oligomers such as 6-hexanediol oligomer dimethacrylate, phthalic anhydride / propylene oxide oligomer dimethacrylate, trimellitic acid diethylene glycol oligomer trimethacrylate, bisphenol A / epichlorohydrin oligomer acrylate, phenol novolac / epichlorohydrin oligomer Addition type of acrylate, cycloaliphatic epoxide and acrylic acid, bisphenol A / epichlorohydrin type oligomer methacrylate, phenol novolak / epichlorohydrin type oligomer methacrylate, polyfunctional epoxy acrylate such as addition type of cycloaliphatic epoxide and methacrylic acid, tolylene diisocyanate, hexamethylene diisocyanate, methylene diphenyl diisocyanate, Examples thereof include acrylic acid derivatives such as urethane (meth) acrylate relates derived from urethane oligomers obtained by reacting diisocyanates such as xylylene diisocyanate and isophorone diisocyanate with polyfunctional alcohols. These may be used alone or in combination of two or more. It is preferable to use these active energy ray-curable resin compositions by adjusting the nonvolatile component concentration to 95% or more, and in particular, use 100% by mass, that is, use a solvent or a volatile component in the composition formulation. It is more preferable that the solvent residue and the photoinitiator residue are negligible due to low adverse effects on the actual performance in the contents removed under predetermined conditions.

  The active energy ray-curable resin composition forming the base material layer has a viscosity at 25 ° C. of 1000 to 10,000 mPa · s, and the active energy ray-curable resin composition forming the hard coat layer is at 25 ° C. The viscosity is preferably 300 mPa · s or less. The viscosity at 25 ° C. of the active energy ray-curable resin composition for forming the base material layer is 1000 to 10,000 mPa · s, and the active energy ray curable resin composition for forming the hard coat layer has a viscosity at 25 ° C. of 300 mPa · s. By adjusting to s or less, it is possible to form a laminated sheet with good film thickness and good thickness accuracy without being affected by the coating processability associated with the increase in viscosity due to the solvent-free composition. It becomes.

  The active energy ray-curable resin composition having a viscosity of 1000 to 10,000 mPa · s at 25 ° C. for forming the base material layer is not particularly limited. For example, a main component is urethane (meth) acrylate, and (meth) A composition obtained by containing a reactive diluent such as an acrylate monomer and adjusting the viscosity to be within the above range can be mentioned. By setting the upper limit of the viscosity at 25 ° C. of the active energy ray-curable resin composition forming the base material layer to 10000 mPa · s or less, coating unevenness such as discharge unevenness and die streak is difficult to occur, and the film has smoothness. It becomes good, and the surface state of the film becomes good. Further, by setting the lower limit of the viscosity at 25 ° C. of the active energy ray-curable resin composition forming the base material layer to 1000 mPa · s or more, the formed pre-curing resin composition is prevented from flowing and thick film coating is performed. Is possible. Furthermore, among the urethane (meth) acrylates, it is preferable to use a urethane acrylate having a weight average molecular weight of 1000 or more, more preferably 1000 to 4000. Thus, toughness can be provided to a base material layer by containing urethane acrylate with comparatively high molecular weight. Of these, the structure represented by the following formula 1 obtained by reacting 4-hydroxybutyl acrylate at the end of the structure having about 4 to 20 urethane bonds in the molecule is most preferred. If the viscosity of the composition is adjusted to the above range, an active energy ray-curable resin composition having a nonvolatile component concentration of 95% or more can be used effectively, and the generation of residual solvent can be reduced. Become. In addition, the viscosity here is the value measured based on JISK7117-1 (rotary viscometer method).

（但し、式中ｍは１〜４の整数を表わし、ｎは１〜１０の整数を表わす。）

(In the formula, m represents an integer of 1 to 4, and n represents an integer of 1 to 10.)

  The reactive diluent such as a (meth) acrylate monomer is not particularly limited, and various diluents can be appropriately combined to be within the above viscosity range. Examples of combinations including these diluents include (1) urethane (meth) acrylate, (2) a monomer having an alkylene oxide group and at least two (meth) acryloyl groups, and (3) one (meth) ) A monomer having an acryloyl group and an aromatic ring structure, (4) a monomer having one (meth) acryloyl group and an alicyclic structure in the molecule, (5) an epoxy acrylate oligomer, and (6) a photopolymerization initiator. Can be mentioned.

  Although the thickness of the base material layer is not necessarily limited, it is preferably 70 to 200 μm, more preferably 75 to 100 μm, in consideration of the self-supporting property of the laminated sheet. .

  The active energy ray-curable resin composition having a viscosity at 25 ° C. of 300 mPa · s or less for forming the hard coat layer is not particularly limited, and examples thereof include various active energy ray-curable silicone additives, A composition obtained by adding a reactive diluent such as a (meth) acrylate monomer to the fluorine-based additive and adjusting the viscosity to be within the above range can be mentioned. By setting the upper limit of the viscosity at 25 ° C. of the active energy ray-curable resin composition forming the hard coat layer to 300 mPa · s or less, thin film coating becomes possible, so that the entire laminated sheet becomes too hard and brittle. There is no concern that the heart coat agent is difficult to effectively tilt on the surface. If the viscosity of the composition is adjusted to the above range, an active energy ray-curable resin composition having a nonvolatile component concentration of 95% or more can be used effectively, and the generation of residual solvent can be reduced. Become.

The reactive diluent such as a (meth) acrylate monomer is not particularly limited, and various diluents can be appropriately combined to be within the above viscosity range. Examples of combinations including these diluents include (1) a polymer containing at least one (meth) acryloyloxy group in the side chain and a structure represented by the following formula 2, and (2) at least one ( A polymer having a (meth) acryloyloxy group and a fluoroalkylene oxide group, (3) a monomer containing at least three (meth) acryloyl groups in the molecule, (4) one (meth) acryloyl group in the molecule, and Examples thereof include a composition comprising a monomer having a ring structure and (5) a photopolymerization initiator in a predetermined ratio.

（但し、ｎは５〜１００の整数を表す。）

(However, n represents an integer of 5 to 100.)

  The thickness of the hard coat layer is not necessarily limited, but in the case where various hard coat agents existing in a tilted manner on the surface after the lamination sheet is formed are effectively tilted on the surface, the thickness is 0.5 to 10 μm. Moreover, it is preferable to set it as 1-5 micrometers.

  Examples of the photopolymerization initiator include benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophene, methylorthobenzoylbenzoate, 4-phenylbenzophenone, t-butylanthraquinone, 2- Ethylanthraquinone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-hydroxy-1- [4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] Phenyl] -2-methyl-propan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-methyl- [4- (methylthio ) Phenyl] 2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, diethylthioxanthone, isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis ( Examples include 2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, methylbenzoylformate, and the like. These can be used alone or in combination of two or more. Among these, acetophenone derivatives whose decomposition products after generation of radicals do not become volatile components, specifically 2-hydroxy-1- [4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl] -2-Methyl-propan-1-one and the like, and benzophenone derivatives that do not generate decomposition products after radical generation are suitable in terms of transparency and durability. Although the quantity of a photoinitiator is suitably adjusted according to sclerosis | hardenability etc. of a composition, it is 1-10 weight part typically with respect to 100 weight part of active energy ray-curable compositions of this invention. .

  The structure of the laminated sheet of the present invention is not particularly limited as long as it has a structure formed by laminating a hard coat layer on at least one surface of the base material layer. For example, active energy is provided on the opposite surface of the hard coat layer. An adhesive layer made of a wire curable resin composition can also be laminated.

  The pressure-sensitive adhesive layer is not particularly limited, and is composed of an active energy ray-curable resin composition containing a (meth) acrylate monomer, oligomer, polymer, or a mixture thereof, and active energy such as ultraviolet rays and electron beams. It is formed by curing with a wire.

  Components other than the above as the active energy ray curable resin composition constituting each layer include other photocurable oligomers / monomers, sensitizers, crosslinking agents, ultraviolet absorbers, polymerization inhibitors, fillers, heat Colorants such as plastic resins, dyes, and pigments can be added within a range that is effective and does not hinder physical properties such as curing, transparency, and heat resistance.

The method for producing the laminated sheet of the present invention is not necessarily limited. For example, the active energy ray-curable resin is sufficiently mixed and dispersed on a release film, belt, and roll for a process that is continuously driven at a constant speed. A base layer component comprising the composition is quantitatively supplied, shaped into a film by the effect of surface tension, heating, and pressure, cured by irradiation with active energy rays, a base layer is formed, and continued thereon In the same manner, the hard coat layer is sequentially formed and laminated, or the base material layer and the hard coat layer are collectively applied, and irradiated with active energy rays to be cured, and the base material layer and the hard coat are laminated. You can list how to do it. Among them, the following production method of A or B is preferable, and according to such a production method, since the viscosity of the base material layer and the hard coat layer is in a specific range, when each layer is formed sequentially, Of course, even when laminating together, each layer is not mixed with other layers more than necessary and is not contaminated, so that the functions of the hard coat layer and the base material layer constituting the laminated sheet can be effectively separated. . In the case of further laminating other layers, for example, an adhesive material layer, an adhesive material layer is formed on the release film, and the base material layer and the hard coat layer are laminated on the adhesive material layer by the above method. Just do it.
(Manufacturing method A: Sequential coating of each layer)
A base material layer made of an active energy ray-curable resin composition 1 having a viscosity at 25 ° C. of 1000 to 10,000 mPa · s is applied, shaped into a film, and the composition 1 is cured to form a base material. Forming a layer, applying a hard coat layer made of the active energy ray-curable resin composition 2 having a viscosity at 25 ° C. of 300 mPa · s on the base material layer, and shaping the film into a film, The manufacturing method of the lamination sheet provided with the process of hardening the composition 2 and forming a hard-coat layer.
(Production method B: two-layer coating)
The base material layer which consists of the active energy ray-curable resin composition 1 whose viscosity in 25 degreeC is 1000-10000 mPa * s, and the hard which consists of the active energy ray-curable resin composition 2 whose viscosity in 25 degreeC is 300 mPa * s. The manufacturing method of a laminated sheet provided with the process of forming a base material layer and a hard-coat layer by apply | coating a coating layer collectively, shape | molding in a film form, hardening this composition 1 and the composition 2. FIG.

  Gravure coating, roll coating, rod coating, knife coating, blade coating, screen coating, die coating, curtain flow coating, etc. can be used for quantitative supply of the active energy ray-curable resin composition constituting each layer of the present invention. it can. An appropriate method may be selected from these according to the thickness of the sheet when the composition of the present invention is formed into a sheet. For example, when a laminated sheet having a thickness of 70 to 200 μm is obtained, these thicknesses are in a thick region as the thickness of the sheet obtained by coating processing, and in consideration of thickness accuracy, processing effort, appearance, etc. A combination in which the composition is a solvent-free system in which the curing component is substantially 100% is preferable.

  Process release films include polyethylene film, biaxially stretched polypropylene film, poly-4-methylpentene-1 film, biaxially stretched polyethylene terephthalate film, biaxially stretched polyethylene naphthalate film, fluororesin film, etc., and dimensional stability A film excellent in properties and smoothness can be used, preferably a biaxially stretched polyethylene terephthalate film excellent in optical smoothness, and more preferably excellent in optical smoothness that has been subjected to mold release treatment with a silicone coating. It is a biaxially stretched polyethylene terephthalate film. The degree of releasability is adjusted by the balance between the releasability after curing the composition, the wetting stability of the film form when coated, and the adhesion. The thickness of the release film is adjusted mainly by the balance of stability when coating the composition of the present invention, suppression of warpage due to curing shrinkage after curing, active energy ray permeability related to curing, and release film cost. Practically, it is 50 to 250 μm.

  The process release belt is seamlessly joined to a sheet material excellent in smoothness and dimensional stability such as stainless steel and surface-plated steel, and is applied to two or more rolls and used for continuous constant speed machining by driving the rolls. The surface can be further coated with a fluororesin or ceramic to increase the mold release. The process release roll is further released by coating the surface-plated steel with a fluororesin or ceramic. In forming a sheet, the composition can be shaped while only one side is in contact, and the other side can be processed in an atmospheric contact state, or can be processed by bringing the double-sided process release material into contact with various combinations. . However, when ultraviolet rays are applied as active energy rays, at least air or (transparent plastic) film is essential on one side due to the low transmittance, and energy irradiation is limited to the air or (transparent plastic) film side. Is done.

  When a process release film is not used, a single laminated sheet can be obtained, so that it can be used for specific applications such as forming a film for optical function adjustment in a form such as winding it into a roll and cutting it into sheets. It will be. On the other hand, if a process release film is used, it can be obtained as a laminate sheet with a release film between it and a laminate sheet. It is also within the scope of the present invention that the process release film is used as a protective film or a process release film for a specific application in a form that is laminated as it is for a specific application.

The active energy ray for irradiating and curing the mixture of each compound raw material is not particularly limited and can be applied industrially, and includes ultraviolet rays, electron rays, γ rays, X rays, etc. When comprehensively judging thickness, energy, equipment cost, cost and quality of additives such as photoinitiators and sensitizers, ultraviolet rays are particularly easy to use. As the ultraviolet light source, various light emitting characteristics such as a low pressure mercury lamp, a high pressure mercury lamp, a xenon lamp and the like can be used without particular limitation, and can be appropriately adjusted according to the film thickness and the curing condition. Moreover, it can adjust similarly regarding energy, and it is about 0.1-5 J / cm < ² > as illuminance. Furthermore, in order to improve irradiation efficiency, it is also possible to irradiate while making irradiation atmosphere into inert gas, such as nitrogen, or heating the shape | molded composition.

  The optical recording medium of the present invention, for example, is provided with a light transmissive layer that also serves as a protective film on a disk substrate that has a concave and convex pattern such as pits and grooves formed on the surface and serves as a signal recording surface. The optical disk is configured to record and reproduce information by irradiating laser light from the above, and the laminated sheet of the present invention is used as the light transmission layer. In order to form a light transmission layer on a disk substrate, for example, an adhesive layer or the like is laminated on the laminated sheet of the present invention on the surface of a recording film (signal recording surface) formed on the disk substrate. After adhering the material layer surface, the laminated sheet may be irradiated with active energy rays and cured.

  In this case, in order to prevent deterioration of the optical signal, the higher the light transmittance of the laminated sheet, the better, and the light transmittance in the wavelength range of 380 to 800 nm is 88% or more, particularly 400 to 410 nm. The light transmittance in the wavelength range is preferably 90% or more. The wavelength of the optical signal applied to the optical recording medium of the present invention is not particularly limited, but may be laser light having a wavelength in the range of 380 to 800 nm generally used for reading and writing of an optical disc, A blue-violet laser beam of around 400 nm capable of increasing the recording capacity is extremely preferable because the transmittance in this wavelength region is 90% or more as described above.

<Production Example 1>
(Synthesis of hard coat layer components)
[Synthesis of Polymer A Containing Silicone and Methacryloyl Group in Side Chain]
In a reactor equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet, 500 parts by mass of toluene, 300 parts by mass of ethyl acrylate, and 300 parts by mass of 2-hydroxyethyl acrylate were added up to 80 ° C. in a nitrogen atmosphere. The temperature was raised. A mixture of 180 parts by mass of a silicone oil containing a methacryloyl group at one end (X-22-174DX: manufactured by Shin-Etsu Silicone) and 10 parts by mass of azobisisobutyronitrile as a polymerization catalyst was dropped therein over 30 minutes. After the polymerization treatment for 2 hours while preventing overheating with the heating medium, the polymerization treatment was carried out for 2 hours while dropping a mixture of 220 parts by mass of isocyanate acrylate (Karenz MOI: Showa Denko) and 1 part by mass of dibutyltin dilaurate as a polymerization catalyst. An acrylic copolymer having a weight average molecular weight of 20,000 (polystyrene conversion by gel permeation chromatography) and a methacryloyl group in the side chain was obtained.

(Preparation of curable resin composition for hard coat layer)
After mixing to 8% by mass of the acrylic copolymer obtained in Production Example 1, 50% by mass of pentaerythritol tetraacrylate, 20% by mass of ethoxyphenyl acrylate, and 20% by mass of tetrahydrofurfuryl acrylate, and then concentrated under reduced pressure. After removing the solvent so that the volatile component was 5% or less, 2% by mass of bisacylphosphine oxide was mixed and dissolved to obtain a curable resin composition for the hard coat layer. With the temperature kept at 25 ° C., an H2 rotor was attached to a Toki Sangyo B-type viscometer (TVB-10), and the viscosity of the composition was measured at a rotational speed of 100 rpm. The result was 250 mPa · s. It was.

(Preparation of curable resin composition for substrate layer)
As urethane (meth) acrylate relate, urethane (meth) acrylate relate shown in the following formula 1 (urethane (meth) acrylate obtained by adding 4-hydroxybutyl acrylate to the end of urethane condensation of isophorone diisocyanate and tetramethylene glycol 40% by weight of relate (weight average molecule; 1000 to 4000), 30% by weight of ethylene oxide (4 mol) modified bisphenol A diacrylate, 20% by weight of 2-hydroxy-3-phenoxypropyl acrylate, 8% by weight of isobornyl acrylate, and 2-Hydroxy-1- {4- [4- (hydroxy-2-methyl-propionyl) benzyl] phenyl} -2-methyl-propan-1-one 2% by mass is mixed and dissolved to cure the base material layer. A resin composition was obtained at a temperature of 2. ℃ while keeping the attaching a H3 shape rotor Toki Sangyo Co. B-type viscometer (TVB-10), at a rotational speed 20 rpm, was 2500 mPa · s was measured the viscosity of the composition.

<Example 1>
After forming a curable resin composition of a base material layer with a thickness of 78 μm on a smooth polyethylene terephthalate film having a releasability of 100 μm with a die coater, an irradiation intensity of 200 mW / cm ^{2 with} a high-pressure mercury lamp. After irradiating the active energy ray so that the integrated light quantity becomes 600 mJ, the hard coat layer is applied on the base material layer with a gravure coater so that the coating thickness becomes 2 μm, and the active energy ray is applied with a metal halide lamp. Was applied so that the irradiation intensity was 200 mW / cm ² and the cumulative irradiation amount was 400 mJ / cm ² , thereby obtaining a laminated sheet 1.

<Example 2>
Two layers of a curable resin composition / hard coat layer of a base material layer are formed on a smooth polyethylene terephthalate film having a releasability of 100 μm in a two-layer die, and a hard coat layer is formed at a thickness of 77 μm / 3 μm. The laminated sheet 2 was obtained by applying the active energy ray so that the accumulated light amount was 800 mJ / cm ² with a high-pressure mercury lamp.

<Comparative Example 1>
A curable resin composition of the base material layer was applied to a smooth polyethylene terephthalate film having a releasability of 100 μm with a die coater to a thickness of 78 μm after drying, and an irradiation intensity of 200 mW / second with a high-pressure mercury lamp. The active energy ray was irradiated so that it might become cm < ² > and the integrated light quantity 600mJ. A mixture of a hard coat layer composition and ethanol (solid content concentration of 40%) is applied onto the substrate layer formed as described above on the substrate layer so that the thickness after drying with a die coater is 2 μm. After drying at 3 ° C. for 3 minutes, an active energy ray was irradiated with an irradiation energy of 200 mW / cm ² and an integrated irradiation amount of 400 mJ / cm ² with a high-pressure mercury lamp to obtain a laminated sheet 3.

<Comparative example 2>
After forming a curable resin composition of a base material layer with a thickness of 80 μm with a die coater onto a smooth polyethylene terephthalate film with a thickness of 100 μm having releasability, an irradiation intensity of 200 mW / cm ^{2 with} a high-pressure mercury lamp. The laminated sheet 4 was obtained by irradiating active energy rays so as to obtain an integrated light amount of 600 mJ.

<Thickness accuracy>
The release film for process was peeled and removed from the obtained laminated sheets 1 to 4, and measured with a 20-point micrometer according to the JIS K7130A-1 method with a uniform width in the width direction of the film 250 mm, and the following determination was performed.
○: Measurement value range is less than 0.005 mm and standard deviation is less than 0.0020 mm. Δ: Measurement value range is less than 0.005 mm or standard deviation is less than 0.0020 mm. X: Measurement value range is 0.005 mm or more. Standard deviation is 0.0020mm or more

<Secondary workability>
Ten sheets were cut with a Thomson blade at 20 ° C. with the film surface as the moving blade side in the obtained laminated sheets 1 to 4, and the following determination was made according to the state of the cut surface of the film.
○: All were cleanly cut without problems ×: Some cracks were observed on the cut surface

<Evaluation of outgas generation amount>
After peeling off the process release film from the obtained laminated sheets 1 to 4, the amount of volatile components collected when the film was placed in an 80 ° C. environment for 30 minutes was measured using GC-MS (Shimadzu Corporation). QP-5050A), the outgas amount (residual solvent amount) generated per gram of the laminated sheet was determined to be less than 100 ppm, and 100 ppm or more was determined to be x.

<Production and evaluation of optical disc having cured product layer>
An inorganic layer was laminated in the order of an Ag reflection film, a ZnS—SiO ₂ dielectric layer, an Sb / Te phase change recording film, and a ZnS—SiO ₂ dielectric layer on a 1.1 mm thick polycarbonate molded into a disk shape. On the substrate, the 100 μm stroke release film of the above laminated sheets 1 to 8 is peeled off, and an acrylic pressure-sensitive adhesive sheet is laminated so that the total thickness becomes 100 μm, and is laminated to the inorganic layer laminated side of the substrate. 4 was produced and the following evaluation was performed.

<Surface performance evaluation>
(Pencil hardness)
About the obtained disk sample, the pencil hardness of the laminated sheet side surface was measured, and HB or more was determined to be ◯, and B or less was determined to be ×.
(Abrasion resistance)
# 0000 steel wool was reciprocated 10 times at a load of 250 g to the obtained disk sample, and it was determined that the scratched one was ◯ and the one with scratch was ×.

<Durability evaluation>
(Damp heat durability test)
The disk sample was allowed to stand for 500 hours in a constant temperature and humidity chamber at a temperature of 80 ° C. and a humidity of 85% RH, and then the appearance of the disk sample was visually determined to make the following determinations.
○: Corrosion of the deposited layer, peeling of the protective film, cracking, etc. were not observed.
X: Corrosion of the deposited layer or peeling or cracking of the protective film was observed.

(War endurance test)
The following judgment was performed about the curvature after putting the obtained optical disk on 80 degreeC85% relative humidity for 500 hours.
A: The difference between the initial warp angle and the warp angle after 500 hours at 80 ° C. and 85% relative humidity is less than 0.4 °.
X: The difference between the initial warp angle and the warp angle after 500 hours at 80 ° C. and 85% relative humidity is 0.4 ° or more.

(Heat shock test)
The following determination was made regarding the amount of warpage change when the obtained optical disk was suddenly changed from 25 ° C. to 55 ° C.
○: The difference between the warp angle in the 25 ° C temperature environment and the warp angle when the environment is suddenly changed to 55 ° C is less than 0.6 ° ×: When the environment is suddenly changed to the warp angle under the 25 ° C temperature environment and 55 ° C Difference of warp angle is 0.6 ° or more

  As described above, in Examples 1 and 2, the film forming property and thickness accuracy are good, and even when processed into a film, problems such as brittleness and breakage, lack of waist and difficulty in handling are not caused. Since the amount of outgas generation was extremely small, it was possible to obtain a laminated sheet in which corrosion of the adherend due to volatile components and solvent cracks on the adherend were prevented. On the other hand, in the laminated sheet processed into a film shape using a solvent as in Comparative Example 1, the amount of outgas generation is large, and in the wet heat durability evaluation, solvent cracks occur due to volatile components, and the laminated sheet breaks. Occurred.

Claims (6)

A laminated sheet comprising a cured product of an active energy ray-curable resin composition,
A laminated sheet comprising a structure in which a hard coat layer is laminated on at least one surface of a base material layer, and a residual solvent amount that volatilizes under a heating condition of 80 ° C. for 30 minutes is less than 100 ppm / g. The active energy ray-curable resin composition forming the base material layer has a viscosity at 25 ° C. of 1000 to 10,000 mPa · s, and the active energy ray-curable resin composition forming the hard coat layer is a viscosity at 25 ° C. Is 300 mPa · s or less, the laminated sheet according to claim 1. The laminated sheet according to claim 1 or 2, wherein the active energy ray-curable resin composition forming the base material layer contains urethane acrylate having a weight average molecular weight of 1000 or more. The protective film for optical disks which consists of a lamination sheet in any one of Claims 1-3. An optical recording medium obtained by laminating at least one layer of the laminated sheet according to claim 1. On release film, belt, roll for process,
A base material layer and a hard coat layer made of an active energy ray-curable resin composition are sequentially or collectively applied, shaped into a film, and the active energy ray-curable resin composition is cured, A method for producing a laminated sheet for forming each layer,
The active energy ray-curable resin composition forming the base material layer has a viscosity at 25 ° C. of 1000 to 10,000 mPa · s, and the active energy ray-curable resin composition forming the hard coat layer is a viscosity at 25 ° C. Of 300 mPa · s, and the amount of residual solvent that volatilizes under heating conditions of 80 ° C. for 30 minutes is less than 100 ppm / g.