JP2010243699A - Optical article, printed matter, and method of manufacturing optical article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat resistance and durability of an optical article having a fine irregular pattern having a light diffraction function formed therein. <P>SOLUTION: The optical article is formed of a cured product of a radiation curable resin composition essentially comprising a urethane resin, and has a fine irregular pattern having a light-diffracting function formed on the surface. The urethane resin used has a number average molecular weight of 6,000 to 10,000, average 6 or more functional groups that are activated by irradiation with radiation per one molecule, and contains at least one isocyanate group in one molecule. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical article having heat resistance and durability. Examples of suitable optical articles include diffraction gratings and holograms having a light diffraction function. In addition, the present invention relates to a printed matter on which the optical article is fixed. As a printed matter, for example, a printed matter (for example, banknote) that needs to be distinguished from its authenticity can be exemplified. In addition to this, the present invention relates to a method for producing the optical article.

  An article having fine irregularities having a light diffraction function on its surface exhibits a visual effect different from that of a normal printed matter. According to this optical article, for example, it is possible to display an image that changes according to the observation conditions, or to display a stereoscopic image. Further, the spectral color shining in rainbow colors expressed by the fine concavo-convex pattern cannot be expressed by a normal printing technique. For this reason, optical articles having a fine uneven pattern formed on the surface are widely used for articles that require anti-counterfeiting measures.

  As a method for producing such an optical article, a method is generally used in which a metal plate having a corresponding concavo-convex pattern is prepared and the metal plate is duplicated and produced as a matrix. Specifically, the following method is known.

(1) Pressing method In this method, a thermoplastic resin is pressed using a heated matrix and the irregularities are replicated on the surface. However, since the press method uses a thermoplastic resin, the heat resistance of the molded product is generally low. In addition, in the case of a concavo-convex shape with a corner, the corner is often not accurately replicated and is often rounded.

(2) Casting method In this method, a melted and softened thermoplastic resin is applied or injected onto the concave / convex forming surface of the matrix, and the resin is solidified to produce a molded product. However, the casting method has local temperature deviation, and the molded product is likely to be distorted or curled. Moreover, since the thermoplastic resin is used, the heat resistance of the molded product is low.

(3) Photo-curable resin method A molded product is produced using a resin that is cured by irradiation with ionizing radiation typified by light or an electron beam, instead of a thermoplastic resin such as a pressing method or a casting method. Is the method. For example, after injecting a liquid ultraviolet curable resin composition into a mold, the resin composition is molded by irradiating ultraviolet rays and curing the resin composition (2P method). The fine shape of the matrix can be reproduced from the liquid UV-curable resin composition. However, since it is liquid, large irregularities that are not desired to be transferred, such as the distortion of the mother mold and the seam of the mother mold, are transferred, and the microscopic quality is good, but it is often poor when viewed macroscopically. In addition, since the uncured resin is liquid, handling is difficult, and if uncured portions due to oxygen inhibition remain due to bubbles or the like, blocking or contamination may be caused in a subsequent process. As a method for solving such a problem, a method of molding using a photocurable resin that is solid or highly viscous at room temperature has been proposed (for example, Patent Documents 1 and 2).

Japanese Examined Patent Publication No. 6-85103 JP 2000-63459 A

  By the way, the optical article manufactured in this way has strength, hardness, heat resistance, durability (abrasion resistance, scratch resistance, chemical resistance, water resistance, etc.) as an optical component, depending on its use. Adhesiveness to the substrate, and further, flexibility of the substrate and followability to expansion and contraction are required.

  For example, such an optical article may be used as a proof means for certifying the authenticity of an article attached to the article or its packaging because of its unique optical performance based on its light diffraction function. A typical example of such an article is a card such as a credit card. In recent years, the optical article is sometimes used while being fixed to a bill. Various fixing methods are used. For example, there is a method of bonding and fixing to the banknote surface using an adhesive. Moreover, an optical article may be processed into a thin strip shape, and this strip-shaped optical article may be inserted into a paper base of a bill and fixed.

  In any of these cases, since these articles are used over a long period of time, high durability is required along with their optical performance.

  For example, in the case of the optical article used for banknotes, the photocurable resin composition is cured even when heat-treated at a temperature of about 160 ° C. (contact with an iron) or in an environment where heat and pressure are applied simultaneously. It is required that the fine concavo-convex pattern thus formed does not deform or disappear.

  As for durability, for example, in the case of the optical article used for a card, for example, when a load is applied due to an impact from the outside, or when dirt adhered to the surface is scraped with an organic solvent such as alcohol or acetone, It is assumed that the card is left under high temperature and high humidity or is put on water. Therefore, the fine uneven pattern on the surface of the optical article is required to have wear resistance or scratch resistance so that it is not damaged or scraped even if mechanical external force such as friction is applied in an environment where it is easily worn. In addition, chemical resistance that does not elute by an organic solvent and durability such as water resistance that does not deform due to the influence of moisture are required.

  According to the techniques described in Patent Documents 1 and 2, the physical properties required as a product can be satisfied to some extent when the concave / convex pattern is replicated. However, even with these techniques, the durability could not be satisfied.

  Therefore, an object of the present invention is to provide the optical article excellent in heat resistance and durability.

That is, the invention according to claim 1 is composed of a cured product of a radiation curable resin composition mainly composed of a urethane resin, and an optical article in which a fine uneven pattern having a light diffraction function is formed on the surface thereof.
The urethane resin has a number average molecular weight of 6,000 to 10,000, has an average of 6 or more functional groups per molecule activated by irradiation with radiation, and at least one isocyanate group in one molecule. It is an optical article characterized by being a urethane resin containing.

As can be seen from the examples to be described later, according to the present invention, excellent optical performance is exhibited by accurately reflecting the concave / convex pattern of the matrix, and durability such as heat resistance, scratch resistance, chemical resistance, etc. is excellent. An optical article is obtained. In addition, when a number average molecular weight is less than 6,000, it results in inferior heat resistance and chemical resistance. Moreover, when a number average molecular weight exceeds 10,000, it is inferior to heat resistance. Moreover, even if a number average molecular weight is 6,000-10,000, when it does not contain an isocyanate group, it is inferior in heat resistance. As radiation, ultraviolet rays or electron beams can be used.

  Next, the invention according to claim 2 is the optical article according to claim 1, wherein the radiation curable resin composition is solid in a state before curing, and fine irregularities of a matrix. It is possible to accurately reflect the pattern, and to suppress duplication of large uneven defects such as matrix distortion and matrix seam.

  Next, the invention according to claim 3 is the optical article according to claim 1 or 2, wherein the radiation curable resin composition contains a release agent, and the release property from the matrix. And the printing durability of the matrix can be improved.

  The invention according to claim 4 is the optical article according to claim 3, wherein the release agent is reactive, and the reactive release agent is applied to the resin along with the curing of the resin layer. Since it reacts and couple | bonds, it does not bleed out on the surface of the resin layer in which the uneven | corrugated pattern was formed later. Further, when the concave / convex pattern is duplicated, the fine concave / convex pattern of the matrix is not damaged, so that the printing durability can be further improved.

Next, the invention according to claim 5 relates to a printed matter including the optical article, and in a printed matter composed of a printed matter main body and an optical article fixed to the printed matter,
The optical article is an optical article according to any one of claims 1 to 5, and is a printed matter.

The invention according to claim 5 relates to a method for producing the optical article, wherein a radiation curable resin composition mainly composed of a urethane resin is applied to a substrate and dried to form a radiation curable resin layer. Forming and embossing the surface of the radiation curable resin layer, and exposing the resin layer to cure the resin,
The urethane resin has a number average molecular weight of 6,000 to 10,000, has an average of 6 or more functional groups per molecule activated by irradiation with radiation, and at least one isocyanate group in one molecule. A method for producing an optical article, which is a urethane resin containing

  According to the present invention, an optical article excellent in durability such as heat resistance, scratch resistance, chemical resistance and the like can be obtained while exhibiting excellent optical performance by accurately reflecting the uneven pattern of the matrix. Play.

  The optical article according to the present invention is composed of a cured product of a radiation curable resin composition containing a urethane resin as a main component, and a fine uneven pattern having a light diffraction function is formed on the surface thereof.

  The urethane resin can be produced by reacting an organic isocyanate having two or more isocyanate groups with a compound having a substituent that reacts with the isocyanate groups. In addition, this compound needs to have a functional group that is activated by irradiation with radiation together with the substituent. Here, examples of the radiation include ultraviolet rays and electron beams.

  Examples of functional groups activated by irradiation with radiation include vinyl groups such as acryloyl groups, methacryloyl groups, and allyl groups. Such a vinyl group exhibits radical polymerization reactivity upon irradiation. Further, the amount of the functional group needs to be an amount having an average of 6 or more per molecule of the urethane resin when the urethane resin is synthesized.

  Examples of the compound having a substituent that reacts with an isocyanate group include (meth) acrylic compounds. For example, hydroxyalkyl (meth) acrylates, hydroxyl group-containing acrylates, acrylic compounds containing acidic functional groups, alkyl acrylates, alkoxyalkoxyalkyl acrylates, dialkylaminoalkyl (meth) acrylates, dialkylaminoalkyl (meth) acrylates, acrylonitrile, Examples include dimethylacrylamide. Moreover, the epsilon-caprolactone condensate of the said hydroxyalkyl (meth) acrylates can also be used.

  Examples of hydroxyalkyl (meth) acrylates include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like.

  Examples of the hydroxyl group-containing acrylate include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 2-hydroxyphenoxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol penta (meth). ) Acrylate and the like.

  Moreover, as an acryl-type compound containing an acidic functional group, (meth) acrylic acid etc. can be illustrated, for example.

  Examples of the alkyl acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate.

  Examples of the alkoxyalkoxyalkyl acrylate include alkoxyalkyl acrylates such as ethoxyethyl (meth) acrylate; 2-methoxyethoxyethyl (meth) acrylate and the like.

  Moreover, methoxydiethylene glycol (meth) acrylate etc. can be illustrated.

  Examples of the dialkylaminoalkyl (meth) acrylate include N, N-dimethylaminoethyl (meth) acrylate and N, N-diethylaminoethyl (meth) acrylate.

  In addition, polycarbonate diol of 1,5-pentanediol and 1,6-hexanediol can also be used as the compound having a substituent that reacts with an isocyanate group. This compound is commercially available from Asahi Kasei Chemicals Corporation under the trade name “PCDLT-5562”.

  Moreover, as said organic isocyanate, diisocyanate compounds, such as an aliphatic diisocyanate compound, an alicyclic diisocyanate compound, an aromatic diisocyanate compound, can be used preferably, for example. Specifically, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6) -diisocyanate, 1,3- (isocyanatomethyl) cyclohexane, isophorone diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, dianisidine diisocyanate, phenyl diisocyanate, halogenated phenyl diisocyanate, methylene diisocyanate, ethylene diisocyanate, butylene diisocyanate, Propylene diisocyanate, octadecile Diisocyanate, 1,5-naphthalene diisocyanate, polymethylene polyphenylene diisocyanate, triphenylmethane triisocyanate, naphthalene diisocyanate, tolylene diisocyanate polymer, polymer of diphenylmethane diisocyanate, polymer of hexamethylene diisocyanate, 3-phenyl-2-ethylene diisocyanate , Cumene-2,4-diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-ethoxy-1,3-phenylene diisocyanate, 2,4′-diisocyanate diphenyl ether, 5,6-dimethyl-1,3-phenylene Diisocyanate, 4,4'-diisocyanate diphenyl ether, benzidine diisocyanate, 9,10-anthracene diisocyanate 4,4'-diisocyanate benzyl, 3,3'-dimethyl-4,4'-diisocyanate diphenylmethane, 2,6-dimethyl-4,4'-diisocyanate diphenyl, 3,3'-dimethoxy-4,4 ' -Diisocyanate diphenyl, 1,4-anthracene diisocyanate, phenylene diisocyanate, 2,4,6-tolylene triisocyanate, 2,4,4'-triisocyanate diphenyl ether, 1,4-tetramethylene diisocyanate, 1,6-hexa Examples include methylene diisocyanate, 1,10-decamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, and 4,4′-methylene-bis (cyclohexyl isocyanate).

  The organic isocyanate may be triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, 4,4′- Polyisocyanate compounds having three or more isocyanate groups such as dimethyldiphenylmethane-2,2 ′, 5,5′-tetraisocyanate; ethylene glycol, propylene glycol, 1,4-butylene glycol, polyalkylene glycol, trimethylo- Adducts obtained by reacting an excess amount of polyisocyanate compounds with hydroxyl groups of polyols such as rupropane and hexanetriol; hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate , 4,4′-diphenylmethane diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate) and other burette type adducts, isocyanuric ring type adducts, etc. Even if one compound is used alone. Two or more kinds may be used in combination.

  Next, both of these can be dissolved in an organic solvent and reacted by heating. The reaction temperature may be 20 to 250 ° C, and is preferably in the range of 50 to 150 ° C. As the organic solvent, for example, various solvents such as hydrocarbon, ketone, ether and ester can be used. Further, during the reaction, a reaction catalyst of an isocyanate group and a hydroxyl group can be added as necessary. Examples of such a reaction catalyst include lead oleate, tetrabutyltin, antimony trichloride, triphenylaluminum, and trioctylaluminum. , Zinc naphthenate, zirconium naphthenate, dibutyltin dilaurate, tetra-n-butyl-1,3-diacetyloxydistanoxane, 1,4-diaza [2,2,2] bicyclooctane, N-ethylmorpholine, etc. be able to.

  Moreover, the number average molecular weight of the urethane resin obtained and the content of isocyanate groups per molecule of the urethane resin can be controlled by the reaction time. That is, the number average molecular weight of the urethane resin applicable to the present invention needs to be 6,000 to 10,000, and it is necessary to contain at least one isocyanate group in one molecule. Although reaction time is 10 minutes-24 hours, it is necessary to select reaction time according to the specific material and mixing ratio of the said compound and organic isocyanate which have a substituent which reacts with an isocyanate group.

The mixing ratio of the compound having a substituent that reacts with an isocyanate group and the organic isocyanate is 30 to 60 mol% in terms of the ratio of the amount of the organic isocyanate to the total amount of the reaction compound used (total amount charged). Is preferred. The same applies to the compound having a substituent that reacts with an isocyanate group. If the amount of the compound having a substituent that reacts with an isocyanate group is too small, the amount of the radiation-reactive functional group that is finally introduced into the radiation-curable resin is reduced, so that the crosslinking density tends to be insufficient. Since the amount of the urethane bond structure formed with the introduction of the radiation-reactive functional group is also reduced, the radiation-curable resin tends to have insufficient thermoplasticity before curing and flexibility after curing.

  The urethane resin thus obtained has the functional group activated by radiation irradiation due to the compound having a substituent that reacts with an isocyanate group.

  And as above-mentioned, a urethane resin needs to be the quantity which has 6 or more on an average per functional group activated by radiation irradiation. In addition, when mixing and using several types of urethane resin, it can calculate using the average molecular weight of each urethane resin. For example, when there are two types of urethane resins, the average molecular weight of the urethane resin is Ma and Mb, the use weights are Wa and Wb, and the average number of functional groups per molecule is Na and Nb. The average functional group number N can be calculated by the formula N = {(Wa / Ma) · Na + (Wb / Mb) · Nb} / {(Wa / Ma) + (Wb / Mb)}.

  A radiation curable resin composition containing as a main component by adding necessary additives to the urethane resin thus obtained is applied to a substrate, dried and solidified, and the solid radiation curable resin composition is obtained. After replicating the irregularities by overlaying the matrix on the surface of the material coating, when the surface of the uncured coating is irradiated with radiation, it is cured by the crosslinking reaction of the isocyanate group in addition to curing by the functional group activated by radiation irradiation. . Furthermore, the fine concavo-convex pattern forming layer made of the cured product is excellent in various physical properties such as heat resistance and durability (abrasion resistance, scratch resistance, chemical resistance, water resistance, etc.). Moreover, since the average molecular weight of the radiation curable resin to be cured is 6,000 to 10,000 and the number of functional groups is 6 or more, the crosslink density upon curing becomes very large, and various physical properties after curing are improved. High effect. In particular, since an isocyanate group is included as a functional group before curing, the heat resistance after curing can be further improved.

  For example, even if the fine uneven pattern is exposed to a high temperature environment, particularly a severe environment where heat and pressure are applied simultaneously, due to the improvement in heat resistance, deformation of the shaped shape and alteration of the material are difficult to occur. In addition, by improving the wear resistance and scratch resistance, even when a fine uneven pattern such as a hologram is provided in a place that is easily exposed to a mechanical external force, such as the surface of a credit card, wear and scratches are less likely to occur. Furthermore, due to the improvement in chemical resistance, even when the surface of a fine concavo-convex pattern such as a hologram is wiped with a solvent, it becomes difficult to elute.

  Next, as an additive added to the said radiation-curable resin composition, a photosensitizer, a sensitizing dye, a mold release agent, a polymerization inhibitor etc. can be illustrated, for example. If necessary, non-reactive resins, crosslinking agents (for example, epoxy resins), dyes, pigments, leveling agents, antifoaming agents, anti-sagging agents, adhesion improvers, coating surface modifiers, plasticizers , Nitrogen-containing compounds, accelerators, viscosity modifiers, surfactants, silane coupling agents, and the like can also be blended.

  The photosensitizer is necessary when the radiation curable resin composition is cured by ultraviolet irradiation, and is unnecessary when electron beam irradiation is used. A sensitizing dye is not necessary when electron beam irradiation is used.

Examples of the photosensitizer include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1- Hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone, 2,4,6 -Trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, benzophenone, methyl o-benzoylbenzoate, hydroxybenzophenone, 2-isopropylthioxanthone 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6-bis (trichloro)- S-triazine, 2- (4-methoxyphenyl) -4,6-bis (trichloromethyl) -S-triazine, iron-allene complex, titanocene compound and the like can be mentioned, and one or more of these can be used. The photosensitizer is preferably used in the range of about 0.5 to 10 parts by weight per 100 parts by weight of the urethane-modified acrylic resin.

  Next, the release agent facilitates release from the mother die. By facilitating release from the mother die, damage to the mother die can be prevented and its printing durability can be improved. As the release agent, conventionally known release agents such as polyethylene wax, amide wax, solid wax such as Teflon (registered trademark) powder, fluorine-based surfactant, phosphate-based surfactant, silicone, modified Silicone or the like can be used.

  Examples of the modified silicone include modified silicone oil side chain type, modified silicone oil one end type, modified silicone oil side chain both end type, methylpolysiloxane containing trimethylsiloxysilicate, silicone graft acrylic resin, methylphenyl silicone oil, etc. Can be used.

  Among them, the release agent having a group that is reactive with the radiation curable resin composition reacts and bonds with the curing of the resin composition, and therefore bleeds out to the surface of the resin composition on which the uneven pattern is formed later. In addition, even when the embossing process is repeated a number of times, the fine uneven pattern of the mold is not damaged, so that particularly excellent printing durability can be obtained.

  An example of such a reactive release agent is a reactive silicone oil. As reactive silicone oils, amino-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, carbinol-modified silicone oil, (meth) acryl-modified silicone oil, mercapto-modified silicone oil, phenol-modified silicone oil, one-end reactive Examples thereof include silicone oil and different functional group-modified silicone oil. Non-reactive silicone oils include polyether modified silicone oil, methylstyryl modified silicone oil, alkyl modified silicone oil, higher fatty ester modified silicone oil, hydrophilic special modified silicone oil, higher alkoxy modified silicone oil, higher fatty acid. Examples thereof include modified silicone oil and fluorine-modified silicone oil.

  Moreover, a polymerization inhibitor is added in order to improve the storage stability of the radiation curable resin composition. Examples of the polymerization inhibitor include phenols, quinones, phenothiazines, coppers and the like. Examples of phenols include hydroquinone, t-butyl hydroquinone, catechol, hydroquinone monomethyl ether, and the like. Examples of quinones include benzoquinone and diphenylbenzoquinone.

The non-reactive resin serves as a binder that adheres the radiation curable resin composition onto the substrate. Examples of such non-reactive resins include polyester resins, alkyd resins, phenol resins, polyurethanes, polybutadienes, polyethers, epoxy resins, and styrene-containing polymers. Also, styrene / butadiene rubber may be used.

  In addition, this radiation-curable resin composition can be dissolved or dispersed in a solvent and applied to a substrate. The solvent is not particularly limited and known ones can be used, but considering solubility and drying speed, for example, ethanol, isopropyl alcohol, methyl ethyl ketone, ethyl acetate, butyl acetate, toluene, xylene and the like can be used. preferable.

  Next, a method for producing an optical article according to the present invention using the radiation curable resin composition will be described.

  That is, first, a matrix having a fine uneven pattern on the surface is prepared. The fine concavo-convex pattern is, for example, a concavo-convex pattern constituting a diffraction grating or hologram having a light diffraction function, and the height of the convex portion or the depth of the concave portion and the pitch thereof are both about 0.1 to 5 μm. . It is desirable that the height of the convex portion or the depth of the concave portion is 1/2 or more of the pitch. And as will be described later, this fine uneven pattern is replicated on the surface of the radiation curable resin composition.

  Such a matrix can be manufactured by, for example, forming a concavo-convex pattern by applying a photoresist on a substrate, exposing according to a two-beam interference method, and developing. Moreover, it can also be manufactured by applying an electron beam resist on a substrate, drawing an electron beam, and developing to form the concavo-convex pattern. It can also be manufactured by a method of etching silicon.

  In addition, the mother die can be manufactured by repeating the inversion using the uneven pattern thus obtained as an original plate. That is, a metal matrix can be manufactured by electroforming a metal such as nickel or iron on the surface of the concavo-convex pattern as an original plate and then peeling it off. In addition, the master can be molded with a resin to produce a resin matrix.

  Although the mother mold manufactured in this way can be used as it is, it is desirable to use it by winding it around a roll. By winding around the roll, the optical article can be continuously produced and the production efficiency is improved.

  Next, a film to be a base material for an optical article is prepared. Examples of such a film include plastic sheets such as plastic sheets such as polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polymethyl methacrylate (PMMA), and polyethylene (PE). The thickness may be 10 to 100 μm.

  And the said radiation-curable resin composition is apply | coated to the surface of this base film, and it dries. The film thickness after drying may be any thickness that allows the concave / convex pattern to be accurately replicated. desirable. Generally, it may be 0.5-5 μm.

  Then, the matrix is overlaid on the coating of the radiation curable resin composition and pressed to replicate the uneven pattern of the matrix on the coating of the radiation curable resin composition. For example, while continuously running the base film on which the coating of the radiation curable resin composition is formed, the roll around which the matrix is wound and the paper roll are passed through and pressed with both of these rolls, The uneven pattern can be transferred to the film of the radiation curable resin composition and replicated.

When pressing, the temperature and pressure of the roll around which the master die is wound are relatively high from the viewpoint of reproducing the embossed shape, and it is better to emboss at a relatively high pressure, thus preventing adhesion to the embossed plate. For this purpose, the relationship is completely opposite. For this reason, it is desirable to press on the conditions of the temperature of 50-150 degreeC, and the pressure of 10-50 kg / cm < ² >.

  Next, the coating of the radiation curable resin composition having the concavo-convex pattern replicated on the surface is cured by irradiation with radiation. As described above, ultraviolet rays and electron beams can be used as the radiation. Examples of the ultraviolet light source include an ultraviolet fluorescent lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a carbon arc lamp, and a solar lamp.

  The optical article according to the present invention can be manufactured in this way, but other layers can be added to the optical article to improve its function. For example, a reflective layer, a pattern printing layer, a concealing layer, an adhesive layer, and the like.

  For example, when the concavo-convex pattern is a concavo-convex pattern constituting a diffraction grating or a hologram, the optical article is a transmissive relief diffraction grating or a transmissive relief hologram. As is well known, the reflection-type relief hologram has a clearer image than the transmission-type relief hologram. Therefore, by providing a reflective layer on the uneven surface, a reflective relief diffraction grating or hologram can be obtained.

  As the reflective layer, either a metal reflective layer or a transparent reflective layer can be applied. Further, as the reflective layer, a laminate of dielectric layers having different refractive indexes between adjacent ones, that is, a dielectric multilayer film may be used. Moreover, these reflective layers do not need to be provided on the entire surface of the concavo-convex pattern, and can be provided in a pattern.

  Examples of the metal reflective layer include aluminum, chromium, nickel, silver, gold, and tin. Aluminum, chromium, nickel, silver, gold and the like are particularly preferable, and the film thickness is in the range of 1 to 10 nm, desirably 20 to 200 nm.

  The transparent reflective layer is a transparent dielectric having a refractive index different from the refractive index of the radiation curable resin composition, and reflects light at the interface between the two based on the difference in refractive index. Examples of the transparent reflective layer include zinc sulfide and titanium dioxide.

  Any of these reflective layers can be formed by a vapor deposition method such as a vacuum deposition method or a sputtering method.

  Next, the pattern printing layer and the hiding layer can be provided at an arbitrary position. For example, on the coating of a radiation curable resin composition. Moreover, it can also provide between a base film and the said coating film. Moreover, it is also possible to provide in the back side of a base film, ie, the other side of the said film. As a printing method, general printing methods such as gravure printing, flexographic printing, screen printing, and offset printing can be used.

  Next, an adhesive layer can be provided on the coating of the radiation curable resin composition or on the back side of the base film, that is, on the opposite side of the coating. With this adhesive layer, the optical article can be adhered to a card, bill or the like. Of course, not only cards and banknotes but also various products and their packaging can be attached to prove the authenticity of these products.

Polycarbonate diol of 1,5-pentanediol and 1,6-hexanediol (PCDLT-5562 manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight: 2000) in a 1 L four-necked flask equipped with a thermometer, a condenser, and a stirring device 300 g, 200 g of isophorone diisocyanate, 0.2 g of dibutyltin dilaurate (reaction catalyst) and 400 g of methyl ethyl ketone (organic solvent) were added and reacted at 70 ° C. to produce a urethane resin. At this time, the reaction time was varied and the infrared absorption spectrum was measured each time, and the compound was synthesized with the reaction time at several points of the portion where the isocyanate residue was observed and the portion where the isocyanate residue was not observed. In this way, resin liquids having a number average molecular weight of 3,000 to 15,000 (changed with each reaction time) and different in average functional group number and isocyanate content were obtained.

  Next, 1.5 parts by mass of a photopolymerization initiator (Irgacure 184, 1-hydroxycyclohexyl-phenylketone manufactured by Ciba Specialty Chemicals) is added to 100 parts by mass of the resin (solid content) in these urethane resin liquids. Further, 3 parts by weight of a release agent (BYK-3700 manufactured by Big Chemie, acrylic modified silicone) is added, a polyethylene terephthalate film is used as a base material, and a dry film thickness of 2 μm is further formed thereon. The liquid material was applied by a gravure method.

Thereafter, a nickel stamper (matrix) having a fine concavo-convex pattern of a diffraction grating pattern with a pitch of 1 μm and a depth of 100 nm and the film were heated and pressed at a linear pressure of 50 kg / cm at 130 ° C., and in this state from the substrate side The film of the resin composition was cured by irradiating a light amount of 200 mJ / cm ² using a metahalide lamp. And this film was peeled from the nickel stamper (matrix), and the film which has a fine uneven | corrugated pattern was obtained. In order to further increase the surface hardness, a light amount of 300 mJ / cm ² was additionally exposed from the coating side with a high-pressure mercury lamp in a nitrogen atmosphere.

  The heat resistance, scratch resistance, and chemical resistance of each sample were evaluated by the following methods.

<Evaluation method>
(1) Heat resistance The embossed film was put on a 160 degreeC hotplate, the load of 98 Pa was hold | maintained for 10 second, and the surface state was visually inspected.
(2) Scratch resistance The concavo-convex structure surface of the sample was evaluated for scratch resistance based on JIS K5600-5-4 scratch hardness (pencil method).
(3) Chemical resistance The sample was immersed in water, acetone, and ethanol for 24 hours, and the surface condition was visually inspected.

  As a result of the evaluation, it was found that the sample whose number average molecular weight did not reach 6,000 was not excellent in heat resistance and chemical resistance, and when the number average molecular weight exceeded 10,000, it was not excellent in heat resistance. It was also found that when the average number of functional groups is less than 6, the heat resistance and scratch resistance are not excellent, and when the isocyanate group is not included in the molecule, the heat resistance is not excellent. In summary, a cured product of a sample having a number average molecular weight of 6,000 to 10,000, an average number of functional groups per molecule of 6 or more, and containing at least one isocyanate group in one molecule is: It was found to be excellent in heat resistance, scratch resistance and chemical resistance.

Claims (6)

In an optical article composed of a cured product of a radiation curable resin composition mainly composed of a urethane resin, and having a fine uneven pattern having a light diffraction function on the surface thereof,
The urethane resin has a number average molecular weight of 6,000 to 10,000, has an average of 6 or more functional groups per molecule activated by irradiation with radiation, and at least one isocyanate group in one molecule. An optical article comprising a urethane resin containing   The optical article according to claim 1, wherein the radiation curable resin composition is solid in a state before being cured.   The optical article according to claim 1 or 2, wherein the radiation curable resin composition contains a release agent.   The optical article according to claim 3, wherein the release agent is reactive. In a printed material composed of a printed material main body and an optical article fixed to the printed material,
A printed matter, wherein the optical article is the optical article according to any one of claims 1 to 4. A radiation curable resin composition mainly composed of a urethane resin is applied to a substrate, dried to form a radiation curable resin layer, and the surface of the radiation curable resin layer is embossed. In the method of manufacturing an optical article that cures the resin by exposure,
The urethane resin has a number average molecular weight of 6,000 to 10,000, has an average of 6 or more functional groups per molecule activated by irradiation with radiation, and at least one isocyanate group in one molecule. A method for producing an optical article, which is a urethane resin containing