JP5294533B2 - Curable composition and article having the cured product - Google Patents

Description

  The present invention relates to a curable composition having low viscosity and good workability, which has good curability, has a low cure shrinkage during polymerization, and can form a cured product layer excellent in dimensional stability.

  The active energy ray-curable composition does not use an organic solvent, and is cured in a short time by irradiating active energy rays such as ultraviolet rays and electron beams, toughness, flexibility, scratch resistance, weather resistance, It is a material that can form a cured product layer with excellent properties such as chemical resistance on the surface of various substrates.

  Therefore, the active energy ray curable composition is suitable for many industrial applications such as woodwork, PVC flooring, ink, plastic molding, plastic film, optical fiber coating, optical disk coating, cast molding, etc. It is used as a protective layer forming material.

  As such a curable composition, a curable composition composed of an acrylic oligomer, a monomer, and a photopolymerization initiator is known. Examples of the acrylic oligomer as the main component include urethane acrylate, epoxy acrylate, and polyester acrylate.

  Among them, urethane acrylate has many kinds of isocyanate components, polyol components and hydroxyl group-containing (meth) acrylic acid ester components which are raw materials, and can be designed widely according to the purpose, and is used in various fields.

  A urethane acrylate curable composition using polycarbonate diol as a raw material is known as a curable composition having excellent wear resistance and excellent adhesion to a polycarbonate resin or the like (for example, Patent Document 1). reference).

  In addition, urethane acrylate curable compositions comprising alicyclic polyisocyanates and hydroxyl group-containing (meth) acrylates have been developed as curable compositions having low viscosity and excellent curability and stain resistance (for example, patents). Reference 2).

  However, the urethane acrylate described in Patent Document 1 has a very high viscosity. Therefore, it is necessary to dilute the curable composition with a solvent.

Further, the urethane acrylate described in Patent Document 2 is preferable because it has a low viscosity, but a curable composition using the same greatly shrinks upon curing. For example, when a surface hardened layer having a thickness of about 100 μm is formed, surface hardening is achieved. There is a problem that the article tends to warp on the layer side and the dimensional accuracy is not sufficient.
JP 2002-179953 A. JP 2002-226519 A.

  That is, an object of the present invention is to provide a curable composition that can form a cured product layer having excellent curability and dimensional stability, has a low cure shrinkage during polymerization, and has a low viscosity and good workability. It is in.

  The present inventors have intensively studied to solve the above problems, and if a specific urethane (meth) acrylate is used together with other (meth) acrylic acid esters, good curability, workability, and excellent The inventors have found that dimensional stability is achieved and the cure shrinkage ratio is small, and the present invention has been achieved.

That is, this invention is a curable composition containing (meth) acrylic acid ester (B) other than urethane (meth) acrylate (A) and urethane (meth) acrylate (A), and urethane (meth) acrylate ( A) is a molar ratio ((a1) / (a2)) of diol (a1) selected from polybutadiene glycol having a number average molecular weight of 500 to 3000 and (meth) acryloyloxyalkyl isocyanate (a2). It is a curable composition that is a product reacted at 8 to 1 / 2.1 .

  The curable composition of the present invention has a low viscosity, has a very low curing shrinkage rate, can form a cured product layer having excellent adhesion to a substrate, and an optical disc or Fresnel lens in which dimensional stability is important, It can be particularly preferably used for optical articles such as prism sheets.

  Hereinafter, the present invention will be described in detail.

  The curable composition of the present invention comprises a specific urethane (meth) acrylate (A) (hereinafter abbreviated as “component (A)”) and a (meth) acrylic acid ester (B) other than component (A) (hereinafter referred to as “component (A)”). , Abbreviated as “component (B)”).

Component (A) used in the present invention, a diol selected from Po Li olefin glycol (a1) (hereinafter, abbreviated as "component (a1)") and (meth) acryloyloxy alkyl isocyanate (a2) (hereinafter, "component ( a2) ”), and obtained by reacting.

  This component (a1) contributes to low shrinkage when the curable composition of the present invention is polymerized and cured, and is useful for improving the adhesion of the formed cured product layer to the substrate. It is.

As component (a1), if hydroxyl groups is two Yusuke Lupo Li olefin glycol in the molecule is not particularly limited. Specific preferred examples are shown below.

The polyolefin glycol used in the present invention is synthesized from, for example, homopolymers or copolymers of olefins such as butadiene, isoprene, ethylene, propylene, 1-butene, isobutylene, 1-hexene, 4-methyl-pentene, and 1-octene. Polyolefin glycols can be used, and these polyolefin glycols preferably have a number average molecular weight of 500 to 3,000. When the number average molecular weight is 500 or more, the flexibility of the cured product layer is improved. Moreover, when the number average molecular weight is 3000 or less, the viscosity of the curable composition does not become too high, and workability does not deteriorate. A more preferred number average molecular weight range is 500-2000.

  These polyolefin glycols can be used alone or in combination of two or more.

  Component (a2) is an essential component in the synthesis of urethane (meth) acrylate for introducing a (meth) acryloyloxy group into component (a1) via a urethane bond.

  Examples of the component (a2) include (meth) acryloyloxyethyl isocyanate, (meth) acryloyloxypropyl isocyanate, (meth) acryloyloxybutyl isocyanate, (meth) acryloyloxypentyl isocyanate, (meth) acryloyloxyhexyl isocyanate, bis ((Meth) acryloyloxy) ethyl isocyanate, bis ((meth) acryloyloxy) propyl isocyanate, bis ((meth) acryloyloxy) butyl isocyanate and the like. Among them, it is preferable to use (meth) acryloyloxyethyl isocyanate because a curable composition having a low viscosity can be obtained, and it is preferable to use acryloyloxyethyl isocyanate because it has good curability. These (meth) acryloyloxyalkyl isocyanates can be used alone or in combination of two or more.

  In addition to component (a2), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenylmethane diisocyanate Diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, bis (4-isocyanatocyclohexyl) methane, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, norbornane diisocyanate 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) Acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, cyclohexanedimethanol mono (meth) acrylate, 2-hydroxy Caprolactone adduct to ethyl (meth) acrylate, caprolactone adduct to 4-hydroxybutyl (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate It is also possible to synthesize a urethane (meth) acrylate using a compound to which a hydroxy group-containing (meth) acrylic ester such as the above is added.

  The method for synthesizing the component (A) used in the present invention is not particularly limited, and a known synthesis method can be used.

  For example, the component (a2) and dilaurin are reacted by dropping the component (a2) in a mixture of the component (a1) and a catalyst such as di-n-butyltin dilaurate under the condition of 0 to 90 ° C. Synthesis by dropping component (a1) in a mixture with a catalyst such as di-n-butyltin acid, or dropping catalyst in a mixture of component (a1) and component (a2) It may be allowed to.

  Here, the use ratio of the component (a1) and the component (a2) constituting the component (A) is not particularly limited, but the molar ratio ((a1) / (a2)) is 1 / 1.8 to 1/1 /. 2.1 is preferable, and 1 / 1.9 to 1 / 2.0 is more preferable.

  In the curable composition of the present invention, the content of the component (A) is not particularly limited, but the lower limit is preferably 20% by mass in the total of the component (A) and the component (B). Moreover, it is preferable that the upper limit is 90 mass%.

  When content of a component (A) is 20 mass% or more, the cure shrinkage rate (after-mentioned) of a curable composition becomes small, and the flexibility of the hardened | cured material layer obtained becomes favorable. Moreover, when the content is 90 mass% or less, the liquid viscosity of the obtained curable composition becomes low, and the coating workability | operativity to a base material becomes favorable. As for content of this component (A), it is more preferable that it is 30-70 mass%.

  Component (B) used in the present invention is a component that adjusts the crosslink density of the curable composition obtained by diluting component (A) to a viscosity suitable for the application and further together with component (A).

As this component (B), for example,
Trimethylolpropane tri (meth) acrylate, trisethoxylated trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (Meth) acrylic acid ester, ethoxylated pentaerythritol tri (meth) acrylic acid ester, ethoxylated pentaerythritol tetra (meth) acrylic acid ester, tris (2- (meth) acryloyloxyethyl) isocyanurate, dipentaerythritol Penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol penta Acrylic acid ester, caprolactone-modified dipentaerythritol hexa (meth) acrylic acid ester, C2-C5 aliphatic hydrocarbon-modified trimethylolpropane tri (meth) acrylate, C2-C5 aliphatic hydrocarbon-modified dipenta Polyfunctional (meth) acrylic acid esters such as erythritol penta (meth) acrylate and aliphatic hydrocarbon-modified dipentaerythritol tetra (meth) acrylate having 2 to 5 carbon atoms;

  Ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, di ( (Meth) acrylic acid nonanediol, di (meth) acrylic acid neopentyl glycol, di (meth) acrylic acid methylpentanediol, di (meth) acrylic acid diethylpentanediol, hydroxypivalic acid neopentyl glycol di (meth) acrylic acid ester , Tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, bis (2- (meth) Acryloyloxyethyl) -2-hydroxyethyl Isocyanurate, Di (meth) acrylic acid cyclohexanedimethanol, Di (meth) acrylic acid polyethoxylated cyclohexanedimethanol, Di (meth) acrylic acid polypropoxylated cyclohexanedimethanol, Di (meth) acrylic acid polyethoxylate Ted bisphenol A, di (meth) acrylic acid polypropoxylated bisphenol A, di (meth) acrylic acid hydrogenated bisphenol A, di (meth) acrylic acid polyethoxylated hydrogenated bisphenol A, di (meth) acrylic acid poly Propoxylated hydrogenated bisphenol A, bisphenoxyfluorene ethanol di (meth) acrylate, neopentyl glycol modified trimethylolpropane di (meth) acrylate, neopentyl hydroxypivalate Di (meth) acrylic acid ester of ε-caprolactone adduct (n + m = 2 to 5) of recall, γ-butyrolactone adduct (n + m = 2 to 5) of neopentyl glycol hydroxypivalate, di (meth) acrylic acid ester Di (meth) acrylic acid ester of caprolactone adduct of neopentyl glycol (n + m = 2 to 5), di (meth) acrylic acid ester of caprolactone adduct of butylene glycol (n + m = 2 to 5), cyclohexanedimethanol Di (meth) acrylic acid ester of caprolactone adduct (n + m = 2 to 5), di (meth) acrylic acid ester of caprolactone adduct of dicyclopentanediol (n + m = 2 to 5), caprolactone adduct of bisphenol A ( di (meth) acrylic acid ester of n + m = 2 to 5) Di (meth) acrylic acid ester of caprolactone adduct of hydrogenated bisphenol A (n + m = 2 to 5), di (meth) acrylic acid ester of caprolactone adduct of bisphenol F (n + m = 2 to 5), bis (meth) Di (meth) acrylic acid esters such as acryloyloxyethyl phosphate and caprolactone-modified bis (meth) acryloyloxyethyl phosphate;

  2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, (meth) Cyclohexyl acrylate, isobornyl (meth) acrylate, norbornyl (meth) acrylate, 2- (meth) acryloyloxymethyl-2-methylbicycloheptane, adamantyl (meth) acrylate, benzyl (meth) acrylate, (meth) Phenyl acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, tetracyclododecanyl (meth) acrylate, cyclohexanedimethanol mono (meth) acrylate, 2-methoxyethyl (meth) acrylate , 3- Toxibutyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, butoxyethyl (meth) acrylate, methoxydipropylene glycol (meth) acrylate, 4- (meth) acryloyloxymethyl-2-methyl-2-ethyl-1, 3-dioxolane, 4- (meth) acryloyloxymethyl-2-methyl-2-isobutyl-1,3-dioxolane, trimethylolpropane formal (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, caprolactone modified phosphoric acid Monofunctional (meth) acrylates such as (meth) acrylates;

  (Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, Nt-butyl (meth) acrylamide (Meth) acrylamides such as, (meth) acryloylmorpholine, hydroxyethyl (meth) acrylamide, methylenebis (meth) acrylamide;

  Polybasic acids such as phthalic acid, succinic acid, hexahydrophthalic acid, tetrahydrophthalic acid, terephthalic acid, azelaic acid, adipic acid, polyhydric alcohols such as ethylene glycol, hexanediol, polyethylene glycol, polytetramethylene glycol and (meta ) Polyester poly (meth) acrylates obtained by reaction with acrylic acid or its derivatives;

  Epoxy (meth) acrylates obtained by reacting bisphenol type epoxy resins obtained by condensation reaction of bisphenols such as bisphenol A, bisphenol F, bisphenol S, tetrabromobisphenol A and epichlorohydrin with (meth) acrylic acid or derivatives thereof;

A diisocyanate compound is added to the hydroxyl group of an alcohol consisting of one or a mixture of two or more of alkanediol, polycarbonate diol, polyether diol, polyester diol, polyolefin glycol, spiroglycol compound, etc. And urethane poly (meth) acrylates other than the component (A) obtained by reacting a hydroxy group-containing (meth) acrylic acid ester having one or more (meth) acryloyloxy groups and one hydroxy group. It is done.

  Although these can be used individually by 1 type or in combination of 2 or more types, since sclerosis | hardenability is favorable, it is more preferable to use an acrylic compound rather than a methacrylic compound.

  Among these, a compound having a cyclic structure in the molecule is preferable since the resulting curable composition has a small curing shrinkage ratio and excellent surface hardness.

  Examples of the compound having a cyclic structure in the molecule include tris (2- (meth) acryloyloxyethyl) isocyanurate, bis (2- (meth) acryloyloxyethyl) -2-hydroxyethyl isocyanurate, di (meth) ) Acrylic acid tricyclodecane dimethanol, di (meth) acrylic acid polyethoxylated bisphenol A, di (meth) acrylic acid polypropoxylated bisphenol A, di (meth) acrylic acid polyethoxylated hydrogenated bisphenol A, Di (meth) acrylic acid polypropoxylated hydrogenated bisphenol A, di (meth) acrylic acid polyethoxylated cyclohexanedimethanol, di (meth) acrylic acid polypropoxylated cyclohexanedimethanol, (meth) acrylic acid tetrahi Rofurfuryl, phenoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, norbornyl (meth) acrylate, 2- (meth) acryloyloxymethyl-2-methylbicycloheptane, (meth) acrylic Adamantyl acid, benzyl (meth) acrylate, phenyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, tetracyclododecanyl (meth) acrylate, 4- (meta ) Acryloyloxymethyl-2-methyl-2-ethyl-1,3-dioxolane, 4- (meth) acryloyloxymethyl-2-methyl-2-isobutyl-1,3-dioxolane, trimethylolpropane formal (meth) acrylate , Bisphenol A type Epoxy (meth) acrylate.

  In this invention, although content of a component (B) is not specifically limited, The range of 10-80 mass% is preferable in the sum total of a component (A) and a component (B).

  The lower limit of the content of component (B) is preferably 10% by mass because the viscosity of the resulting curable composition is lowered and the coating workability to the substrate is improved. Moreover, since the cure shrinkage rate of a curable composition is low, it is preferable that an upper limit is 80 mass%. As for content of a component (B), it is more preferable that it is 20-70 mass%.

  As long as the performance is not impaired, the curable composition is further added to vinyl esters such as vinyl acetate, vinyl butyrate and divinyl adipate; N-vinylformamide, N-vinylacetamide, N-vinyl-2-pyrrolidone, N-vinyl compounds such as N-vinylcaprolactam; vinyl ethers such as ethyl vinyl ether and phenyl vinyl ether can be contained.

  The above are the constituent components of the curable composition of the present invention, and, if necessary, within a range that does not impair the performance, for example, a polymerization initiator, a thermoplastic polymer, a slip agent, a leveling agent, an oxidation agent A known additive such as an inhibitor, a light stabilizer, an ultraviolet absorber, a polymerization inhibitor, a silane coupling agent, an inorganic filler, an organic filler, or a surface-organized inorganic filler is appropriately mixed and used. In addition, it is preferable to add an antioxidant or a light stabilizer in order to improve the storage stability of the curable composition and to prevent discoloration or alteration of the cured product layer.

  When the photopolymerization initiator (C) (hereinafter abbreviated as “component (C)”) is added to the curable composition of the present invention, a cured product can be efficiently obtained by irradiation with active energy.

  Examples of the component (C) include benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophenone, methylorthobenzoylbenzoate, 4-phenylbenzophenone, t-butylanthraquinone, 2-ethylanthraquinone, Diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2 -Methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone- , Diethylthioxanthone, isopropylthioxanthone, 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-methylpropionyl) benzyl] phenyl] -2-methylpropan-1-one, methylbenzoylformate, and the like can be used. These are used alone or in combination of two or more.

  In this invention, although content of a component (C) is not specifically limited, It is preferable to use in 0.001-10 mass parts with respect to a total of 100 mass parts of a component (A) and a component (B).

  This component (C) is preferably 0.001 part by mass or more with respect to a total of 100 parts by mass of the component (A) and the component (B) from the viewpoint of curability, and from the viewpoint of deep curability and non-yellowing To 10 parts by mass or less. As for the addition amount of a component (C), it is more preferable that it is 0.01-7 mass parts.

  Furthermore, in the curable composition of the present invention, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, 4-amyl dimethylaminobenzoate, A known photosensitizer such as dimethylaminoacetophenone can also be added.

  The commercially available antioxidants and light stabilizers are, for example, Sumitomo Chemical Co., Ltd., Sumitizer BHT, Sumilizer S, Summarizer BP-76, Summarizer MDP-S, Summarizer GM, Summarizer BBM-S, and Summarizer WX. -R, Sumilizer NW, Sumilizer BP-179, Sumilizer BP-101, Sumilizer GA-80, Sumilizer TNP, Sumilizer TPP-R, Sumilizer P-16; Asahi Denka Kogyo Co., Ltd. ADK STAB AO-20, ADK STAB AO-30 , ADK STAB AO-40, ADK STAB AO-50, ADK STAB AO-60, ADK STAB AO-70, ADK STAB AO-80, ADK STAB AO-330, ADK STAB PEP-4C, ADK STAB PEP-8, ADK STAB PEP-2 G, ADK STAB PEP-36, ADK STAB HP-10, ADK STAB 2112, ADK STAB 260, ADK STAB 522A, ADK STAB 329K, ADK STAB 1500, ADK STAB 135A, ADK STAB 13510; Tinuvin 144, Tinuvin 622, Tinuvin 111, Tinuvin 123, Tinuvin 292; Hitachi Chemical Co., Ltd. FANCLIL FA-711M, FA-712HM, etc. (all are trade names).

  Although the addition amount of these antioxidants and light stabilizers is not particularly limited, it is preferably 0.001 to 5 parts by mass, more preferably 0 to 100 parts by mass in total of the component (A) and the component (B), respectively. Add in the range of 0.01 to 3 parts by mass.

  The viscosity of the curable composition of the present invention may be appropriately selected according to the coating method and the thickness of the cured product layer to be obtained, and is not particularly limited.

  For example, when using the curable composition of this invention as a coating material, it is preferable that it is the range of 50-10000 mPa * s in 25 degreeC as a viscosity from a viewpoint of workability | operativity. If it is such a viscosity range, the hardened | cured material layer with a cured film thickness of 3-500 micrometers can be easily formed on a base material. More preferably, it is the range of 100-8000 mPa * s.

  When the cured product layer of the article of the present invention is formed, the curable composition of the present invention is applied and cured by a known method such as a spin coating method, a roll coating method, or a flow coating method.

  In the present invention, when the thickness of the cured product layer is 3 μm or more, the surface of the article can be sufficiently protected, and when it is 500 μm or less, it is easy to suppress warping of the obtained article. More preferably, it is the range of 30-300 micrometers.

  The curable composition of the present invention can be easily cured by irradiating with known active energy rays such as α rays, β rays, and γ rays.

  The atmosphere in which the active energy rays are irradiated when the curable composition of the present invention is cured may be air or an inert gas such as nitrogen or argon.

  The curable composition of the present invention can form a cured product layer that has a very low cure shrinkage and is excellent in adhesion to a substrate.

  Therefore, the curable composition of the present invention can be particularly suitably used for the production of optical articles such as optical disks, Fresnel lenses, and prism sheets in which dimensional stability is important.

  In particular, in an optical disk or the like, since an error is likely to occur during reading and writing, the curing shrinkage rate of the curable composition of the present invention is less than 7.5% so that the optical disk substrate does not warp during curing shrinkage. It is preferable to use an ionic composition.

  When the curing shrinkage of the curable composition of the present invention is less than 7.5%, the adhesion to the substrate is also good. Further, when the curable composition is cured, there is no occurrence of a problem such as a large warp of the substrate due to shrinkage.

  In the present invention, the curing shrinkage rate (%) means a value calculated by the following method.

The liquid density (X1) before curing at 20 ° C. of the curable composition of the present invention and the density (X2) at 20 ° C. of the cured product after curing of the composition are respectively measured and determined by the following formula (1). Is the cure shrinkage percentage (%).
Curing shrinkage (%) = [(X2-X1) / X2] × 100 Formula (1)

  Next, the substrate to which the curable composition of the present invention can be applied will be described below.

  The material of the substrate is not particularly limited, and examples thereof include ABS, polyethylene, polypropylene, cyclic cycloolefin polymer, polyvinyl chloride, polymethyl methacrylate, polystyrene, polycarbonate, nylon, polyoxymethylene, polyurethane, and polyethylene terephthalate. Known plastics; glass; ceramics; wood; metal and the like.

  In order to obtain an article for optical use, a transparent plastic such as a cyclic cycloolefin polymer, polymethyl methacrylate, polystyrene, polycarbonate, polyethylene terephthalate, or a base material such as transparent glass is used.

  Moreover, the shape of a base material is not specifically limited, It selects suitably as desired.

  In general, warping, deformation, and the like of a substrate are more susceptible to the effects of curing shrinkage of the curable composition as the thickness of the substrate is thinner. Since the curable composition of the present invention has a very low curing shrinkage rate, it can be suitably used for a substrate having a thin thickness that is likely to cause warpage of the substrate.

  From such a viewpoint, in the article of the present invention, the thickness of the substrate may be less than 1.5 mm, particularly less than 1.2 mm.

  These substrates to which the curable composition of the present invention can be applied can be pretreated depending on the application. Examples of the surface treatment method include ultraviolet cleaning, degreasing, frame treatment, metal or ceramic sputtering or vapor deposition treatment, silane coupling treatment, and primer coating.

  Hereinafter, the present invention will be described in detail with reference to examples.

Synthesis Example 1 [Production of urethane acrylate UA1]
To a four-necked flask having an internal volume of 5 liters equipped with a stirrer, a temperature controller, a thermometer, a condenser and a dropping funnel, polycarbonate diol (trade name; T5650J, 1,5-pentanediol, manufactured by Asahi Kasei Kogyo Co., Ltd.) Polycarbonate diol produced using 1,6 hexanediol as a raw material, number average molecular weight 800) 2000 g, 0.5 g of 2,6-di-tert-butyl-4-methylphenol and 0.5 g of dibutyltin dilaurate were put in a water bath. While stirring and heating so that the flask internal temperature becomes 70 ° C., 705 g of acryloyloxyethyl isocyanate is dropped from the dropping funnel at a constant rate for 4 hours while maintaining the flask internal temperature at 70 ° C. After stirring for 2 hours, the temperature in the flask was raised to 75 ° C and reacted at the same temperature for 4 hours. , To produce a urethane acrylate UA1. The reaction rate calculated from the remaining isocyanate equivalent was 99%.

Synthesis Example 2 [Production of urethane acrylate UA2]
Urethane acrylate UA2 was produced in the same manner as in Synthesis Example 1 except that 1325 g of polycaprolactone diol (manufactured by Daicel Chemical Industries, Ltd., trade name: Plaxel 205U, number average molecular weight 530) was used instead of polycarbonate diol. The reaction rate calculated from the remaining isocyanate equivalent was 99%.

Synthesis Example 3 [Production of urethane acrylate UA3]
Urethane acrylate UA3 was produced in the same manner as in Synthesis Example 1 except that 2500 g of polybutadiene glycol (trade name; G-1000, number average molecular weight 1000) manufactured by Nippon Soda Co., Ltd. was used instead of 2000 g of polycarbonate diol. The reaction rate calculated from the remaining isocyanate equivalent was 99%.

Synthesis Example 4 [Production of urethane acrylate UB1]
1110 g of isophorone diisocyanate (manufactured by Sumitomo Bayer Eletan, trade name: Desmodur I) was added to a 5 liter four-necked flask equipped with a stirrer, temperature controller, thermometer, condenser and dropping funnel with side tube. And 0.5 g of dibutyltin dilaurate are added and stirred and heated in a water bath so that the internal temperature becomes 70 ° C., and 2000 g of polycarbonate diol (trade name: T5650J) is added from the dropping funnel to a flask internal temperature of 65 to 65 ° C. While maintaining at 75 ° C., the solution was added dropwise at a constant speed for 4 hours, and further stirred at the same temperature for 2 hours. Next, the temperature in the flask is lowered to 60 ° C., and the dropping funnel is uniformly mixed and dissolved with 592 g of 2-hydroxyethyl acrylate, 0.75 g of hydroquinone monomethyl ether and 0.75 g of 2,6-ditertiarybutyl-4-methylphenol. The contents of the dropping funnel were dropped at a constant rate for 2 hours while maintaining the flask internal temperature at 55 to 65 ° C., and then the temperature of the flask contents was 75 to 85 ° C. The reaction was carried out for 4 hours while maintaining that temperature range to produce urethane acrylate UB1. The reaction was judged by measuring the residual isocyanate equivalent, and the reaction was completed after confirming that the reaction rate was 99% or more.

Synthesis Example 5 [Production of urethane acrylate UB2]
Urethane acrylate UB2 was produced in the same manner as in Synthesis Example 4 except that 1325 g of polycaprolactone diol (trade name; Plaxel 205U) was used instead of polycarbonate diol.

Reference example 1
(1) Preparation of curable composition 70 parts by mass of UA1 produced in Synthesis Example 1 as component (A), 10 parts by mass of tris (2-acryloyloxyethyl) isocyanurate and 20 parts by mass of tetrahydrofurfuryl acrylate as component (B) As a part and component (C), 1 part of 1-hydroxy-cyclohexyl phenyl ketone was mixed and dissolved to obtain a curable composition.

  This curable composition had a viscosity (25 ° C.) of 4500 mPa · s and was a pale yellow transparent and viscous liquid. Further, the curing shrinkage was 6.7%, which was in an allowable range (less than 7.5%).

(2) Production of optical disk having cured product layer and production of optical disk for adhesion evaluation:
On the transparent disk-shaped substrate (diameter 12 cm, plate thickness 1.1 mm, warp angle 0 degree) obtained by injection molding of polycarbonate resin and having a center hole with a diameter of 1.5 cm, the curable composition prepared above was used. The film was applied by spin coating so as to have a cured film thickness of 100 μm, irradiated with ultraviolet rays using a metal halide lamp (120 W / cm) having a lamp height of 10 cm, and cured with an integrated light quantity of 1000 mJ / cm ² .
・ Production of optical disk for dimensional stability evaluation:
On a transparent disc-shaped substrate (diameter 12 cm, plate thickness 1.1 mm, warp angle 0 degree) obtained by injection molding of polycarbonate resin and having a center hole with a diameter of 1.5 cm, sputtering apparatus CDI- manufactured by Balzers Co., Ltd. 900, an Ag alloy containing Pd and Cu was sputtered to a film thickness of 40 nm to obtain an optical disk having a silver alloy reflective film. On this reflective film, the curable composition prepared in the above (1) is applied by a spin coating method so as to have a cured film thickness of 100 μm, and ultraviolet light is applied using a metal halide lamp (120 W / cm) having a lamp height of 10 cm. And cured with an integrated light quantity of 1000 mJ / cm ² .

Reference Example 2, Examples 1-3 , Comparative Examples 1-4
A curable composition was prepared in the same manner as in Reference Example 1 except that the compositions shown in Tables 1 and 2 were used, and the optical disk for adhesion evaluation and the obtained curable composition were used in the same manner as in Reference Example 1. An optical disk for dimensional stability evaluation was produced.

Using the optical disks for evaluation manufactured in Reference Examples 1 and 2, Examples 1 to 3 and Comparative Examples 1 to 4, adhesion and dimensional stability were evaluated. The curable composition was also examined for viscosity (25 ° C.), cure shrinkage, and curability. The obtained evaluation results are shown in the evaluation result columns of Tables 1 and 2.

  It shows about the said evaluation method and evaluation criteria.

<Viscosity>
The viscosity at 25 ° C. is measured for the curable composition using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., TVE-20). Evaluation was as follows.
○: Viscosity (25 ° C.) is 10000 mPa · s or less, coating workability is good ×: Viscosity (25 ° C.) exceeds 10,000 mPa · s, and coating workability is poor

<Curing shrinkage>
The density of the curable composition before and after curing is measured, and the curing shrinkage rate (%) is calculated based on the formula (1). Evaluation was as follows.
○: Less than 7.5% ×: 7.5% or more

<Curing property>
The curable composition is coated on a glass plate with a bar coater so that the cured film thickness is 100 μm, irradiated with ultraviolet rays using a metal halide lamp (120 W / cm) with a lamp height of 10 cm, and tack-free by finger touch. Find the minimum amount of irradiation light. Evaluation was as follows.
○: Good at 500 mJ / cm ² or less ×: Defect exceeding 500 mJ / cm ²

<Hardened film layer adhesion>
With respect to the optical disk that has been subjected to the endurance test at 80 ° C. and 85% RH for 96 hours, a cross-cut tape test is performed on the coating film on the polycarbonate surface in accordance with JIS K-5400. Evaluation was as follows.
○: More than 90/100 Δ: 90/100 to 50/100
X: Less than 50/100

<Dimensional stability>
For the optical disk immediately after production, the initial warp angle was measured in an environment of 20 ° C. and 50% RH using a DLD-3000 optical disk optical mechanical property measuring apparatus manufactured by Japan EM Co., Ltd. The optical disk is allowed to stand for 96 hours in an environment of 80 ° C. and 85% RH, and further left for 96 hours in an environment of 20 ° C. and 50% RH. taking measurement. The evaluation was as follows in both the initial stage and after the environmental test.
○: Warpage angle is within ± 0.3 degrees, and dimensional stability is good.
X: Exceeding ± 0.3 degree, poor dimensional stability.

  The warp angle of the optical disc means the maximum warp angle in the radial direction at a radius of 55 mm, where positive (+) warps toward the cured product layer and negative (-) warps in reverse. Show the case.

Abbreviations in Table 1 are as follows.
UA1: Urethane acrylate UA1 produced in Synthesis Example 1 ( not equivalent to component (A))
UA2: Urethane acrylate UA2 produced in Synthesis Example 2 ( not equivalent to component (A))
UA3: Urethane acrylate UA3 produced in Synthesis Example 3 (corresponding to component (A))
UB1: Urethane acrylate UB1 produced in Synthesis Example 4 (outside the range of component (A))
UB2: Urethane acrylate UB2 produced in Synthesis Example 5 (outside the range of component (A))
TE2000: Urethane methacrylate manufactured by Nippon Soda Co., Ltd. (urethane methacrylate synthesized from polybutadiene having a number average molecular weight of 2000, tolylene diisocyanate and 2-hydroxyethyl methacrylate) (outside the range of component (A))
U2PPA: Shin-Nakamura Chemical Co., Ltd. urethane acrylate (urethane acrylate synthesized from isophorone diisocyanate and 2-hydroxypropyl acrylate) (outside the scope of component (A))
TAIC: tris (2-acryloyloxyethyl) isocyanurate TCDA: tricyclodecane dimethanol diacrylate C9DA: 1,9-nonanediol diacrylate THFA: tetrahydrofurfuryl acrylate MEDOL: 4-acryloyloxymethyl-2-methyl-2 -Ethyl-1,3-dioxolane PM21: caprolactone-modified bis (meth) acryloyloxyethyl phosphate,
Nippon Kayaku Co., Ltd., trade name: Kayamar PM-21
HCPK: 1-hydroxy-cyclohexyl phenyl ketone IRG127: 2-hydroxy-1- [4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl] -2-methylpropan-1-one IRG819: Bis ( 2,4,6-trimethylbenzoyl) phenylphosphine oxide

Claims (4)

A curable composition containing (meth) acrylic acid ester (B) other than urethane (meth) acrylate (A) and urethane (meth) acrylate (A),
Urethane (meth) acrylate (A) is a molar ratio ((a1) / (a2) of diol (a1) selected from polybutadiene glycol having a number average molecular weight of 500 to 3000 and (meth) acryloyloxyalkyl isocyanate (a2). )) Is a product obtained by reaction at 1 / 1.8 to 1 / 2.1 .   An optical disc having a cured product of the curable composition according to claim 1.   A Fresnel lens having a cured product of the curable composition according to claim 1.   A prism lens having a cured product of the curable composition according to claim 1.