JP2006213844A - Active energy ray-curable screen ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy ray-curable screen ink composition which can be printed on the surface of a substrate such as compact disk by a jet ink method to form a recording layer, gives the smooth surface, can quickly be set by the jet ink method, hardly blots the jet ink printed on the recording layer, even after stored under the environments of high temperature and high humidity, does not cause tackiness in the recording layer itself by moisture to block the recording layer, and can form the recording layer not causing the warp of the disk due to the change of the humidity, when the environment is rapidly changed from a high humidity environment to a low humidity environment. <P>SOLUTION: This active energy ray-curable screen ink composition is characterized by comprising a hydroxy group-having water-soluble monofunctional monomer, a water-soluble polymer, a dye-fixing agent and silica, wherein the silica has an average particle diameter of 6 to 18 μm, the maximum particle diameter of ≤30 μm, and is contained in an amount of 10 to 25 pts. per 100 pts. of the ink composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an energy beam curable screen ink composition for forming a recording layer that can be satisfactorily recorded with a water jet ink such as an inkjet printer on a substrate such as an optical disk.

  Optical information recording media such as compact discs (hereinafter also referred to as CDs) and digital video discs (hereinafter also referred to as DVDs) are one of the main media when selling contents such as music and movies. In addition, CD-R, CD-RW, DVD-R, DVD-RW, etc., which are optical information recording media used for recording computer-related data, video, images, and music, are widely used by general personal consumers. It has become widespread.

  On the surface of the optical information recording medium, character information such as titles and song titles, patterns and designs are printed by methods such as screen printing, offset printing, waterless lithographic printing, and many of them are active such as ultraviolet rays. Ink compositions that are cured by energy rays are used. Recently, CD-Rs, CD-RWs, DVD-Rs, DVD-RWs, and the like having a recording layer that can be printed with an inkjet printer on design images, photographic images, text information, and the like created by a personal computer have been sold. Yes.

  An active energy ray curable ink composition as a method for forming a recording layer on a disk surface, the cured film having a property of receiving ink of an ink jet printer (hereinafter referred to as jet ink). There is a method in which a product is applied to the optical information recording medium by screen printing.

  As an active energy ray-curable ink composition suitable for forming the recording layer, in order to increase the setting (fixing) speed of jet ink, for example, particles of an inorganic substance such as silica may be included. It is considered effective.

  However, the particle size of silica (hereinafter, this particle size refers to the secondary agglomerated particles of silica contained in the ink when the ink composition is prepared by a dispersing device such as a dispersion stirrer, three-roll mill, or bead mill. If the average particle diameter is too small, there is a problem in practicality because the setting of the printed jet ink is slow or easy to bleed. On the other hand, when silica having an excessively large particle size is included, the thickness of the screen printing layer of the optical disk is generally 20 μm or less, and the large silica may cause scratches on the recording surface. This scratch may be an obstacle to optical reading. Silica having a too large particle diameter causes clogging of the screen printing plate.

  As described above, it is important to select the particle size of the silica to be used. At the same time, it is essential to add a specific water-soluble monomer, water-soluble polymer, dye fixing agent, etc. as a binder component. A photoinitiator is also required.

  Regarding the water-soluble monomer, it is important to speed up the setting (fixing) of the jet ink to the recording layer and at the same time to increase the strength of recording as a cured film. For this purpose, conventionally, 50 parts or more of a water-soluble monomer typified by acryloylmorpholine or the like is used in 100 parts (mass basis) of ink.

  However, a plastic film or disk on which the active energy ray-curable ink composition having the above monomer structure (a structure using acryloyl morpholine) is printed on the surface can be used in a short time from a very high humidity environment (humidity of 90% or more). In severe conditions such as moving to an environment (humidity of 30% or less), there may be a problem that the printed matter (film, disk, etc.) is warped within a few minutes after the transfer. When a recording layer using jet ink is formed on the surface of a card, various tickets, or the like with such an ink composition, if the warpage is severe, adverse effects are exerted on processes such as post-processing and packaging.

  Optical information recording media such as CDs and DVDs are thicker and more durable than paper for packaging, plastic films, etc., and warpage is unlikely to occur. However, once warping occurs, even a slight amount may cause a problem. For example, in the case of a DVD, there is a possibility that the optical reading is affected only when the warping angle exceeds 0.5 degrees, and when it exceeds 1 degree, a failure occurs almost certainly. Note that the warp angle in the case of CD, DVD, etc. generally represents the angle θ shown in FIG.

  Patent Document 1 describes an ultraviolet curable resin composition for forming an ink jet receiving layer. Along with the use of a cationic copolymer having a specific structure, many of the examples follow acryloylmorpholine according to claim 8 of the document. It is characterized by including. Further, the claims do not limit the types of inorganic fillers, organic fillers, etc., and at the same time, do not use a water-soluble polymer, and use a solvent together.

  However, as described above, the examination of the filler type is very important for improving the setting property of the jet ink, and in order to improve the screen printing suitability or the coating suitability by the coater, a specific water-soluble high The addition of molecules is extremely effective. Furthermore, the active energy ray curable composition does not contain a VOC component or has a very low content in that the content is very low, and various solvents as listed in paragraph 34 of Patent Document 1 are used in combination. Is not preferable in terms of environmental protection. In order to form a good ink-jet recording layer with the resin composition of this document, it is considered that a more detailed design is required.

JP 2001-213908 A

As a typical required quality of a recording layer formed on the surface of a CD or DVD using an active energy ray curable screen ink composition,
(1) The recording layer forms a clean ink film with good leveling by screen printing.
(2) forming a highly reproducible image, character information, etc. without jet ink printed from a jet printer being repelled or scattered on the surface of the recording layer;
(3) Printed jet ink is set as fast as possible (the ink is fixed or fixed on the recording layer and does not adhere even if it touches the surroundings. Usually, it is preferably within a few minutes) Finish, and the printed jet ink should not adhere to other substrates.
(4) The printed matter printed by the ink jet printer does not bleed ink even if it is stored for a long time under heating and humidification conditions.
(5) A number of discs having a recording layer after curing are piled up, a load is applied, and even when heated and humidified, the discs do not block each other;
(6) Even when the disc having the recording layer after curing is sufficiently humidified and then suddenly moved to a low humidity environment, the volume of the recording layer is changed due to a sudden change in humidity, and the warp of the disc is caused. Not occur,
Etc.

  In order to improve the leveling of the active energy ray curable screen ink composition of (1), selection of a filler, selection of a monomer having good wettability to a substrate, addition of a polymer component, etc. are effective. In general, when a material that improves leveling is used, the acceptability of the jet ink is lowered and the setting speed is lowered.

  The reproduction of the jet ink printing described in (2) does not necessarily correlate with the leveling property of the recording layer described in (1). In general, since the jet ink is a water-based ink, it is necessary to form a recording layer that is highly polar and wet with the water-based ink and is less likely to cause scattering and bleeding.

  Regarding the setting speed of (3), selection of the porous filler is important, but as described above, when the leveling property of (1) is improved, it tends to be slow.

  Regarding bleeding after heating and humidification of jet ink printing described in (4), there are large factors depending on the performance of the dye fixing agent. However, a highly effective dye fixing agent may not be dissolved in a specific monomer.

  In order to prevent the recording layer from blocking after the heating and humidification described in (5), it is essential to combine both a monomer and a filler having excellent physical properties.

  Regarding the warpage of the disk described in (6), the constitution of the monomer and the filler has a strong influence as in (5).

  This invention makes it a subject to provide the active energy ray hardening-type screen ink composition which satisfy | filled all the required quality of said (1)-(6). It is another object of the present invention to provide an information recording medium having an ink jet recording layer formed using the ink composition.

  The inventors of the present invention designed an ink composition for forming a jet ink receptive recording layer film on the basis of a combination of a specific inorganic filler and a monofunctional monomer having a hydroxyl group. The present invention has been completed by finding that the above-mentioned problems can be solved by combining an adhesive polymer and a dye fixing agent.

  The active energy ray-curable screen ink composition of the present invention contains a water-soluble monofunctional monomer having a hydroxyl group, a water-soluble polymer, a dye fixing agent and silica, and the silica has an average particle size of 6 to 18 μm, and The maximum particle size is 30 μm or less, and 10 to 25 parts of the silica is contained in 100 parts of the ink composition.

  A disk having a recording layer formed on the surface of an information recording medium such as a CD or a DVD by the active energy ray-curable screen ink composition of the present invention has a smooth and smooth leveling surface on which the ink is applied. With the printer, it is possible to print beautifully with good reproducibility and to obtain a recording layer on which the printed jet ink is set quickly.

In addition, even after the disc is printed with jet ink and stored in a high-temperature, high-humidity environment, the jet ink printed on the recording layer is less likely to bleed and the recording layer itself is exposed to moisture. Do not block due to stickiness.
In addition, when it suddenly moves from a high-humidity environment to a low-humidity environment, it is difficult for the disc to warp due to humidity changes.

  The active energy ray-curable screen ink composition of the present invention can be printed or applied to a substrate such as paper, synthetic paper, or plastic by a method other than screen printing, such as a coater. In addition to recording with jet ink, the formed recording layer can be written with a water-based pen or printed with water-based vermilion, and does not repel or smear such water-based ink.

  Hereinafter, embodiments of the present invention will be described in detail. In the present specification, unless otherwise specified, all parts or% are based on mass.

  The active energy ray-curable screen ink composition of the present invention contains a water-soluble monofunctional monomer having a hydroxyl group, a water-soluble polymer, a dye fixing agent and silica, and the silica has an average particle size of 6 to 18 μm, and The maximum particle size is 30 μm or less, and the content is 10 to 25 parts in 100 parts of the ink composition.

  In order to improve the speed of setting the jet ink on the recording layer, selection of the filler to be added is important. Here, the setting of the ink means that the ink is fixed or fixed on the recording layer and the ink is not applied to the finger as much as it is rubbed with the finger. Since the disk on which the ink is set can be stacked or packaged, fast setting is an important characteristic in printing workability.

Porous silica (SiO ₂ · nH ₂ O) is a typical example of a porous and highly hydrophilic filler, but a small particle size generally used for fluidity and emulsification regulators for printing inks. In the case of silica having an average particle size of 0.1 μm or less, such as Aerosil 200 manufactured by Nippon Aerosil Co., Ltd., it is difficult to add 8% or more at a concentration in the ink due to the large surface area. is there. In addition, when silica having an average particle size significantly smaller than 6 μm is used, there is a problem that the setting of the jet ink that is printed is slow or the bleeding becomes easy.

  Therefore, in order to increase the setting (fixing) speed of the jet ink, the average particle diameter is preferably in the range of 6 to 18 μm, more preferably in the range of 12 to 18 μm.

  Although the silica itself having a small average particle size may be difficult to absorb moisture, silica having a small particle size is not suitable for the active energy ray-curable screen ink composition of the present invention due to the low addition amount. Although various types of silica having different particle diameters were compared and studied, basically, the larger the particle diameter, the higher the jet ink setting speed.

  Currently, screen printing of CD, DVD, etc. is generally performed with a thickness of about 10 to 20 μm, and the powder raw material such as silica to be mixed is fixed so that the average particle diameter does not exceed 20 μm. It is desirable that the thickness be 30 μm or less at the maximum. If the silica greatly exceeds 30 μm, the sharp tip of the silica may protrude from the coating surface, or the silica itself may not be fixed in the cured screen ink coating. When the base material is a disc, if the discs are piled up and subjected to weak vibrations, silica powder that is not fixed to the tip of the silica or the coating may damage the disc surface. There is a possibility.

  From the above examination, the silica used in the present invention is preferably porous silica having an average particle diameter of 6 to 18 μm, more preferably 10 to 18 μm, and a maximum particle diameter of 30 μm or less. The particle size distribution is preferably sharp.

  One of the main raw materials of the present invention is a low-viscosity active energy ray-curable monomer. Jet inks are generally aqueous and many contain more than 70% moisture. Therefore, the recording layer on which the jet ink is printed with good reproducibility without being repelled needs to have a highly polar surface, and the monomer used is preferably water-soluble.

  There are many types of water-soluble monomers, but the strength of the cured film is strong enough to withstand practical use, the adhesion to the substrate is good, and at the same time, the jet ink itself or the absorption of moisture in the jet ink is fast It is important to choose Also, when absorbing moisture in the air as well as moisture in the jet ink, if the tack (adhesiveness) of the surface of the recording layer increases, it may cause blocking to other substrates, etc., so store it with warming and humidification In this case, it is important that the surface tack hardly rises.

  In addition, when the humidity changes abruptly, for example, when the humidity changes from 90% to 30%, a composition that causes volume shrinkage due to a sudden release of moisture in the film becomes a problem. In particular, in the case of DVD, if the volume shrinkage is large, the disk itself warps, and in the worst case, the optical reading is disturbed. This volume shrinkage is caused by the fact that the moisture retained inside the recording layer suddenly scatters to the outside when the atmospheric humidity drops sharply and the volume corresponding to the water originally absorbed shrinks. Conceivable. Therefore, it is required that the recording layer does not suddenly scatter moisture, and even if it scatters, the molecular structure is changed to relieve internal cohesive force, thereby reducing the volume change of the recording layer due to increase or decrease of water.

  More than half of the composition forming the recording layer is a polymer in which monomers are polymerized. In order to form a film that absorbs and retains moisture, it is desirable that a required amount of hydroxyl groups be present in the polymer portion, and the monomer that is a constituent unit of the film may contain hydroxyl groups in a certain ratio or more. Necessary.

  On the other hand, a polymer formed from a polyfunctional monomer has a three-dimensional structure and is strong because of its high crosslink density, and is desirable for durability. However, the harder the film (the higher the degree of crosslinking), the denser the polymer chains, and at the same time, the degree of freedom of the hydroxyl group itself is deprived, so the water absorption of the film formed decreases. That is, the setting property of the jet ink is lowered.

  As a result of intensive studies, it was found that the active energy ray-curable monomer suitable for the present invention is water-soluble and a monofunctional monomer having a hydroxyl group is suitable. Of course, it is possible to use other monofunctional monomers and polyfunctional monomers in combination for the purpose of improving the film strength or dissolving a raw material of a type that cannot be dissolved by the above-mentioned monomers.

  Also, screen printing aptitude cannot be ignored. The selection of the type of silica and water-soluble monomer is important for obtaining an ink that is easy to screen print and has good leveling, but at the same time, the addition of a water-soluble polymer is essential.

  When the filler used as the raw material is silica, the dye is not fixed because there is no charge. A monomer does not chemically react with a dye unless it contains a functional group such as an amino group. Therefore, it is important that the jet ink does not bleed when heated and humidified, but it is also essential to include a dye fixing agent that fixes (fixes) the dye in the jet ink.

  As described above, the water-soluble monofunctional monomer having a hydroxyl group is excellent in various performances, but in order to ensure a low viscosity necessary for obtaining sufficient fluidity as a screen ink composition, it is linear, and The molecular weight is not so high. It is also important for practical use that the raw material cost for synthesizing the monomer is not expensive. Considering this, hydroxyalkyl acrylate is suitable as the water-soluble monofunctional monomer having a hydroxyl group.

  Furthermore, the lower the molecular weight of the alkyl moiety, the lower the viscosity and the higher the curability by active energy rays, while the toxicity and skin irritation may deteriorate. On the contrary, when the alkyl portion is longer, the toxicity is lowered, but the acryloyl concentration per unit volume and mass is lowered, and the curability by active energy rays is lowered. On the other hand, if the alkyl group is too long, it is of course impossible to ensure water solubility, which adversely affects the acceptability of the jet ink. From the above, 4-hydroxybutyl acrylate is preferably used among the hydroxyalkyl acrylates as a more suitable monomer for the present invention.

  Thus, 4-hydroxybutyl acrylate is an optimal monomer for use in the present invention, but there may be problems when the monomer is used alone. Although the use of a dye fixing agent is essential as described above, for example, it has been confirmed that 4-hydroxybutyl acrylate alone cannot dissolve some cationic polyamine resins having a high dye fixing effect. Needless to say, the dye fixing agent should be uniformly present in the recording layer in a dissolved state.

  As an improvement measure regarding this point, the inventors use a hydroxyalkyl acrylate typified by the above-mentioned 4-hydroxybutyl acrylate and N-vinylformamide in order to dissolve a dye fixing agent that cannot be dissolved only by 4-hydroxybutyl acrylate. I found a way to do it.

  When one kind of N-vinylformamide is used as a monomer in an active energy ray-curable composition, the active energy ray of the level generally used has low curability and may not even form a film. However, when combined with 4-hydroxybutyl acrylate, it was found that the specific dye fixing agent was dissolved, and at the same time the jet ink set was improved as compared with the case where only 4-hydroxybutyl acrylate was used as a raw material.

  In conclusion, the optimum addition ratio of each monomer is 20 to 60 parts, more preferably 25 to 50 parts of 4-hydroxybutyl acrylate with respect to 100 parts of active energy ray-curable ink, and at the same time 20 to 50 parts of N-vinylformamide. 60 parts, more preferably 25 to 50 parts are mixed.

  As the dye fixing agent, a cationic polyamine resin is suitable for the present invention, and those having dicyandiamide in the resin skeleton are particularly suitable. In the case of some cationic polyamine resins having dicyandiamide in the resin skeleton, it has been confirmed that they are not completely dissolved in 4-hydroxybutyl acrylate, and in this case, N-vinyl is used as described above. It is necessary to mix at least 10% formamide.

  The addition of the water-soluble polymer is effective for improving the fluidity of the screen ink and improving the leveling and screen printing suitability. If necessary, viscosity is given together with fluidity to prevent sedimentation of powder raw materials such as organic and inorganic fillers, thereby improving on-machine stability and storage stability. There are various water-soluble polymers, but those that give high effects such as imparting fluidity and improving viscosity by adding as little as possible are effective without impairing the setting properties of the jet ink.

  Naturally derived raw materials may have problems with stability. The inventors have intensively studied these points and found that a cellulose derivative in which cellulose is water-soluble by chemical modification is useful as a water-soluble polymer. In particular, for jet ink bleed during warming and humidification as described above, hydroxypropylmethylcellulose that dissolves in water and absorbs water at a certain high temperature (over 40 ° C) (solidifies) is used at low temperatures. The case is best.

  Moreover, although the optimal addition rate of hydroxypropyl methylcellulose was also verified, in the case of the active energy ray-curable screen ink composition of the present invention, it is preferable to use 0.3 to 3 parts of hydroxypropylmethylcellulose in 100 parts of ink. is there. Although depending on the type of silica to be selected, even when hydroxypropylmethylcellulose is added at 0.3% or less, improvement in screen printability and leveling on the surface of the recording layer are hardly confirmed.

  On the other hand, when hydroxypropylmethylcellulose is used in an amount exceeding 3 parts, screen printing suitability and leveling of the recording layer surface are improved, but it may be easily blocked when heated and humidified, and jet ink setting properties. May decrease drastically.

  For silica, the particle size range is most important. However, if the particle size distribution is in the same range, the setting property of the jet ink is higher in the case of amorphous silica produced by a wet synthesis method than that produced by other production methods (for example, dry method). Is confirmed to be suitable. In addition, active energy ray screen ink compositions prepared from silica by a wet synthesis method are more stable and stable on screen printers in operation than ink compositions using silica derived from natural raw materials. Excellent in properties.

  The wet synthesis method is a production method in a liquid phase in which silica particles are obtained by reacting sodium silicate (water glass) with sulfuric acid, neutralizing and pulverizing after washing. On the other hand, the dry synthesis method refers to a method by a gas phase reaction in which silica particles are obtained by heating silicon tetrachloride with oxygen and hydrogen at 1000 ° C. or higher.

  In the wet synthesis method, primary particles are aggregated to easily form large secondary particles (secondary particles having a strength that is difficult to be pulverized into primary particles by a normal dispersion apparatus) and are relatively liquid phase reactions. The hydroxyl group on the silanol group is easily oriented on the particle surface. In addition, the wet-process silica has a feature that it easily takes a network structure and easily forms a capillary. Due to this oriented hydroxyl group and the formation of capillaries, wet-process silica has the property of easily absorbing water (jet ink).

  On the other hand, silica by a dry process is a method suitable for producing fine particles of several tens of nm, and it is difficult to form secondary aggregates, and it is difficult to produce large-diameter silica of several μm or more. It is also characterized by fewer hydroxyl groups on the silica surface than in the wet method because of the gas phase reaction. For this reason, the water absorption of the dry process silica tends to be inferior to the wet process.

  Examples of the active energy ray used for curing the ink in the present invention include ultraviolet rays and electron rays. When ultraviolet rays are used, it is necessary to contain a photopolymerization initiator in the screen ink. In general, an apparatus that generates an electron beam is expensive and requires specialized knowledge about maintenance. Therefore, in the active energy ray curable ink market, ultraviolet curable ink is used more frequently.

  Specific examples of the photopolymerization initiator and sensitizer used include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy- 2-methyl-1-phenyl-propan-1-one, benzophenone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-propan-1-one, 2-methyl-1 -[4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, bis (2,6-dimethoxy) Benzoyl) -2,4,4-trimethyl-pentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxy Id, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzyldimethyl ketal, 2,4,6-trimethylbenzophenone, oligo [2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl ) Propanone], 2-isopropylthioxanthone, 2,4-diethylthioxanthone, [4- (methylphenylthio) phenyl] phenylmethanone, ethyl anthraquinone, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester However, it is not limited to this.

  These photopolymerization initiators are used in an amount of 1 to 10 parts, more preferably 2 to 6 parts, in 100 parts of the screen ink of the present invention. When the amount of the initiator exceeds 10 parts, the excess initiator and the formed product after generation of radicals may adversely affect the adhesion and hardness. When the amount is less than 1 part, the required photocurability cannot be obtained.

  The active energy ray-curable screen ink composition of the present invention includes a non-reactive compound, an antifoaming agent, a leveling agent, a lubricant, a plasticizer, an antioxidant, a polymerization inhibitor, an ultraviolet absorber, Flame retardants, pigments, dyes, rheology adjusters, etc. can be used in combination as appropriate.

  The components used for the active energy ray-curable screen ink composition of the present invention are preferably selected in consideration of safety. Further, as a method for applying the active energy ray-curable curable screen ink of the present invention onto an optical recording medium or other paper or plastic, a screen printing method is suitable for the purpose of increasing the film thickness, but is not limited thereto. Instead, a bar coating method, a blade coating method, an air knife coating method, a roll coating method, or the like can be used.

  In addition, by combining printing using ordinary printing ink by ordinary offset printing or flexographic printing and printing or coating (application process) with the active energy ray-curable screen ink composition of the present invention, ordinary patterns, characters, etc. An area that can be recorded with jet ink can be partially formed on a substrate such as paper or plastic on which is printed.

  Oil-based ink can be used for offset printing, and water-based flexographic ink can be used for flexographic printing. Further, when the active energy ray screen ink composition of the present invention is used in combination with an active energy ray curable offset ink or an active energy ray curable flexo ink, a printed matter having a portion that can be recorded by inkjet in one pass by an inline process ( Cards, disks, etc.) can be produced.

  For example, it has an offset printing unit or flexographic printing unit for UV ink, has a rotary screen unit, a roll coater unit, or a flexo coater unit in the subsequent process, and then has an activity such as an ultraviolet irradiation device or an electron beam irradiation device. By using a printing apparatus having an energy ray irradiation unit, a printed matter having a recording layer can be produced using the active energy ray curable screen ink composition of the present invention in one step. According to this method, it is possible to provide, on a non-absorbing substrate such as a plastic film, a portion that can be recorded by ink jet in addition to a normal printed portion of a picture or character.

  EXAMPLES Next, although an Example demonstrates this invention, these are examples and this invention is not limited to this.

  Examples 1 and 2 and Comparative Examples 1 to 8 of the active energy ray-curable screen ink composition for forming the recording layer were prepared according to the formulation shown in Table 1.

In Table 1, no. 1 and 2 use commercially available wet synthesized silica.
No. 3 uses Sirisia 250 manufactured by Fuji Silysia Chemical Co., Ltd.
No. No. 4 uses Tokuyama Co., Ltd. fine seal X-45.
No. 5 uses Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.
No. 6 is a commercially available dye fixing agent, which uses a cationic polyamine resin containing dicyandiamide as a skeleton.
No. 7 uses Jurimer APO600N manufactured by Nippon Pure Chemical Co., Ltd.
No. 8 uses a commercially available 4-hydroxybutyl acrylate as a water-soluble monofunctional monomer having a hydroxyl group.
No. 9 is a commercially available N-vinylformamide, which is a water-soluble monomer capable of dissolving the dye fixing agent of N0.6 as described above.
No. No. 10 uses acryloylmorpholine manufactured by Kojin Co., Ltd.
N0.11 and 12 are commercially available cellulose derivatives. 12 uses L-20 made by Daicel Chemical Industries.
No. The PI compound No. 13 was prepared by mixing a plurality of photopolymerization initiators or the like. In this experiment, 50 parts of Ciba Specialty Chemicals Irgacure 184 and 50 parts of Darocur 1173 were mixed at 80 ° C. A heat-mixed product is prepared and used.
No. Stabilizer No. 14 is added for the purpose of preventing gelation due to heating during production or heating due to long-term storage. In this experiment, 5 parts of aluminum N-nitrosophenylhydroxylamine was added to EO (ethylene oxide) modified bisphenol. A solution dissolved in 95 parts of A diacrylate is prepared and used.
Furthermore, since the generation of bubbles during screen printing causes pinholes and leveling defects, silicon oil (No. 15) having a high defoaming effect is also added in order to prevent them.

  Cellulose derivatives such as hydroxypropylmethylcellulose and cellulose acetate are generally in the form of powder, and it takes time to completely dissolve in a water-soluble monomer. Therefore, the water-soluble polymer was first completely dissolved in the water-soluble monomer using a dispersion stirrer, and after confirming that there was no powdery polymer remaining undissolved, other raw materials were added. After all the raw materials had been charged, each sample was stirred for at least 10 minutes at a rotational speed of 3000 rpm or higher. After completion of the stirring, the degree of dispersion was confirmed with a grindometer manufactured by Toyosei Seiko. When the degree of dispersion was not less than 30 μm, stirring was continued.

  Table 2 shows the evaluation results of the ink compositions of Examples and Comparative Examples. (6) Except for the evaluation test of the warp of the recording layer, each ink of Examples and Comparative Examples was screen-printed on a protective film of an unused compact disk using a 300-mesh screen, and then immediately A cured film (recording layer) having a thickness of about 20 μm was produced by irradiating ultraviolet rays with an ultraviolet irradiator photocure manufactured by company. The protective film for the compact disc described above refers to a resin layer (generally an ultraviolet curable resin composition) coated on a recording layer that is optically read.

  Each evaluation method and evaluation criteria are as follows, where ◎ is excellent, ○ is a practical level, Δ is difficult to put into practice, and × is a judgment that is not practical at all. Therefore, practical use is impossible if there is at least one of Δ and ×.

(1) Leveling of the recording layer It is determined whether the leveling of the ink film cured after screen printing and by irradiation with ultraviolet rays is uniform and clean. ◎ When the leveling is very uniform and good, ◎ Slightly glossy and transparent, but poorer than ◎, but when it is a level that can be established as a product, poor printing and transfer failure within 1% of the entire screen printing surface △ was evaluated when the above was confirmed, and x was evaluated when defective printing or transfer was confirmed in a range exceeding 1% with respect to the entire screen printing surface.

(2) IJ set test The set of jet ink printed on the recording layer is evaluated. Printing with jet ink is performed on the sample surface screen-printed by the PRIMERA TECHNOLOGY, INC. Inkjet printer Signature3. Coated paper was placed every 30 seconds on the pattern portion printed with the three-color overlap of the printing surface, and pressure was applied so that a load of 1 kg was applied to an area of 3 cm × 3 cm. The ink transfer to the coated paper at that time was confirmed, and the time when the ink was hardly adhered to the paper was recorded as the set end time. Within 1 minute was evaluated as 、 ３, within 3 minutes was evaluated as ◯, within 10 minutes was evaluated as △, and beyond it was evaluated as ×.

(3) IJ print reproducibility Visually check whether there is a problem in the reproduction of printed images or text information due to the scattering or repelling of printing immediately after printing on the recording layer with the above-described inkjet printer. It was evaluated with. Check if there is any scatter in the place where multiple colors overlap. When there is no problem with the printed image, ◎, large scattering and repellency are hardly confirmed with the naked eye, but with a microscope, the level at which the blur can be clearly confirmed is ◯. The level that can be confirmed was evaluated as Δ, and the level that could not be used as a product at all because of jet ink scattering and bleeding was judged as x.

(4) Bleeding of IJ printing surface The disc printed on the recording layer ink film surface by the ink jet printer was allowed to stand for 24 hours in an environment of a temperature of 43 ° C. and a humidity of 95%, and then ink bleeding was confirmed. The degree to which slight ink bleeding within 2 mm in width is confirmed along the outline of the portion where the jet ink is overprinted is ◎, the case where the same ink bleeding remains within 5 mm in width, ○, the same ink bleeding is 5 mm A case where a blur exceeding 5 mm is generated along the printed portion in the same manner for a single color portion, and a case where a blot exceeding 5 mm is generated in various portions of the jet printing is indicated by ×. Judged.

(5) Blocking property of recording layer A disk on which a cured recording layer is formed is prepared and a PP film is placed on it, and a load of 5 kg is applied to the entire surface and stored at 43 ° C. and 95% humidity for 24 hours. The disk is taken out from the thermostat and left for 10 minutes or longer, and then the force when the film is peeled off from the disk is measured with a spring balance. If there is almost no resistance or if the scale detects 1 g or less, ◎ if a weak resistance of 10 g or less is detected, ◯ if there is a resistance of 50 g or less, △, if it is stronger When resistance was detected, it was determined as x.

(6) Warpage of recording layer Immediately after each screen ink sample is stretched on a very thin PET film by an applicator, an ultraviolet ray is irradiated to produce a PET film having a recording layer with a thickness of about 50 μm. . The produced film is stored for 24 hours at 25 ° C. and 60% humidity. The film taken out from the thermostat is transferred to a desiccator within 10 seconds and stored in a low humidity environment. If the film does not change at all even after 10 minutes, ◎ If a warp that can barely be confirmed with the naked eye within 5 minutes occurs ○ If a clear warp of 10 ° or more occurs within 5 minutes Δ, and when the film warped as much as possible, it was judged as x.

  For the inks of Examples 1 and 2, good evaluation results without Δ and X were obtained, indicating that each sample is at a practically good level. Examples 1 and 2 are silicas within the particle size distribution range of the present invention, but the surface smoothness of these recording layers is not the same. In general, the smoothness of the recording layer is better, but depending on the user, a surface with a high matte effect may be required due to the design, and a combination of multiple types that have a large particle size but a different particle shape The degree of surface smoothness can be adjusted.

  Comparative Examples 1 to 3 are cases of samples using silica having a small average particle size. In general, the leveling of the surface of the recording layer improves as the particle size decreases. In the case of Comparative Example 3 in which the particle size is extremely small, a beautiful leveling surface having a high surface gloss can be obtained. However, in any of the samples, the setting property of the jet ink is remarkably lowered, and the ink jet printing portion is not set for several minutes to several tens of minutes (the jet ink is deposited when touched with a finger). It has also been confirmed that the smaller particle diameter tends to be inferior in blocking properties after heating and humidifying the recording layer.

  Comparative Example 4 showed the experimental results when the dye fixing agent was changed. If the cationic polyamine resin that dicyandiamide has in the skeleton is changed to a more general type of dye fixing agent such as a quaternary ammonium salt of polyacrylic acid, the bleeding after heating and humidification is remarkably worsened.

  Comparative Examples 5 to 7 are examples in which the composition was changed as a water-soluble monomer. Comparative Example 5 is a system that uses only N-vinylformamide as a water-soluble monomer. However, UV curable screen inks composed only of this monomer have extremely low curing efficiency with UV rays, and can be used under the same UV irradiation conditions. The film could not be formed to a sufficient hardness, and the evaluation experiment itself could not be performed.

  Comparative Example 6 is an example in which only ACMO (acryloylmorpholine) is used alone as a monomer, and Comparative Example 7 is an example in which ACMO and N-vinylformamide are mixed and used. In any case, when the humidity change is large, it causes warping of the base material, and when used for a disk for optical reading, there is a high possibility that it becomes a big problem.

  Comparative Example 8 is an example in which the water-soluble polymer is switched from hydroxypropyl methylcellulose to cellulose acetate. Although it is a water-soluble polymer with a small addition ratio, even with the same cellulose derivative, there was a difference in the bleeding after warming and humidification due to the difference in structure.

  On the recording layer formed on the surface of CD, DVD or the like by the active energy ray curable screen ink composition of the present invention, it is possible to print / print clear characters and images having good storability by the ink jet method. Further, if the active energy ray-curable screen ink composition of the present invention is printed and coated in combination with offset printing or screen printing, an ink jet printed portion can be produced even on a substrate that hardly absorbs water.

It is a figure which shows the curvature angle (theta) of discs, such as CD.

Explanation of symbols

1 Disc warped 2 Reference horizontal plane

Claims (12)

  A water-soluble monofunctional monomer having a hydroxyl group, a water-soluble polymer, a dye fixing agent and silica, wherein the silica has an average particle size of 6 to 18 μm and a maximum particle size of 30 μm or less, An active energy ray-curable screen ink composition containing 10 to 25 parts in 100 parts of the ink composition.   The active energy ray-curable screen ink composition according to claim 1, wherein the water-soluble monofunctional monomer having a hydroxyl group is hydroxyalkyl acrylate.   The active energy ray-curable screen ink composition according to claim 2, comprising 20 to 60% of 4-hydroxybutyl acrylate as the hydroxyalkyl acrylate.   The active energy ray-curable screen ink composition according to claim 3, wherein 20 to 60 parts of 4-hydroxybutyl acrylate as hydroxyalkyl acrylate and 20 to 60 parts of N-vinylformamide are contained in 100 parts of ink. object.   2. The active energy ray-curable screen ink composition according to claim 1, wherein the dye fixing agent is a cationic polyamine resin containing dicyandiamide as a skeleton.   The active energy ray-curable screen ink composition according to claim 1, comprising at least hydroxypropylmethylcellulose as the water-soluble polymer.   The active energy ray-curable screen ink composition according to claim 6, wherein 0.3 to 3 parts of hydroxypropylmethylcellulose is contained in 100 parts of the ink composition.   2. The active energy ray-curable screen ink composition according to claim 1, wherein the silica to be used is produced by a wet synthesis method.   An ultraviolet curable screen ink composition for forming an ink-jet recording layer, which is obtained by adding a photopolymerization initiator to the screen ink composition according to claim 1.   An information recording medium having an ink jet recording layer formed on the surface of the active energy ray-curable screen ink composition according to claim 1.   The active energy ray-curable screen ink composition according to any one of claims 1 to 9, wherein an inkjet recording layer is formed on a part of the surface, and offset printing, screen printing or flexographic printing is formed on the other part. An information recording medium on which a printing layer is formed. An inkjet recording layer is formed on a part of the surface of the active energy ray-curable screen ink composition according to claim 1, and printing is performed on the other part by offset printing, screen printing, or flexographic printing. The method for producing an information recording medium according to claim 11, wherein a layer is formed.

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