JP2012250416A - Method for forming image into laminated body for flexible packaging using aqueous ink jet recording ink and laminated body for flexible packaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method for performing printing with high image quality on a non-absorbable base material which is a flexible packaging material by using a printing process using ink jet recording ink without damaging flexibility of the flexible packaging material.SOLUTION: In the image forming method, a printing layer is formed on an ink jet receiving layer formed on the surface of the flexible packaging material by using aqueous ink jet recording ink including a pigment and resin, and an adhesive layer is formed on the printing layer. Then, by laminate processing for laminating molten or film-shaped polymer, a sealant film layer is formed. Film thickness of the flexible packaging material and film thickness of the receiving layer are defined within a specific range.

Description

  The present invention relates to a method for forming an image on a soft packaging material using an ink jet recording ink and a laminating method, a laminate for soft packaging having a printed layer formed by the image forming method, and a laminate for the soft packaging It relates to a manufacturing method.

Currently, printing in a laminate for soft packaging used in soft packaging bags such as food packages is performed by gravure printing or flexographic printing on soft packaging materials. In both cases, a plate for printing is prepared in advance when an image is formed, and printing is performed by bringing ink into contact therewith, which is a printing method suitable for high-speed printing and mass production.
On the other hand, in recent years, in the market of flexible packaging materials such as flexible packaging material films, with the change and diversification of consumer needs, various types of products and the shortening of product cycles are progressing. The existing printing method has taken into consideration environmental issues and occupational safety due to water-based printing ink (see Patent Document 1), but it requires a plate for printing, so it is profitable for small-scale production. Often does not fit. Also, since it takes time to create a plate, it is difficult to meet short delivery times.
In order to cope with this in the printing industry, a printing method capable of on-demand printing that does not require a plate is desired, and one of them is inkjet printing. Inkjet printing does not require a plate and is suitable for printing in small quantities. The time required for the plate making process can be shortened, and the delivery time can be shortened. Also, inventory can be reduced by on-demand printing.

Inkjet recording can easily produce images, so it can be used not only for creating images on absorbent substrates such as plain paper used in homes and offices, but also for creating photo-like images on glossy paper, advertising, posters, etc. The range of use is expanding to image preparation on an absorbent substrate.
However, when printing with a water-based inkjet ink on a non-absorbing substrate such as a soft packaging material, the ink does not permeate, and thus it is necessary to fix the ink in order to avoid mixing and bleeding between the inks. For this reason, an ink fixing method using a receiving layer has been studied (see Patent Document 2). However, in the ink fixing method for an inkjet recording sheet described in Patent Document 2, the substrate is thick and the receiving layer is applied. Since the work thickness is also thick, the texture as a soft packaging material is impaired. Moreover, since it has inorganic fillers, such as a silica and clay, transparency is bad and it is not suitable for a soft packaging material use. Thus, although the water-based inkjet ink is printed on the non-absorbing substrate, a printing method and printed matter suitable for flexible packaging have not been obtained.

Japanese Patent Laid-Open No. 5-171091 (Japanese Patent No. 3255953) JP2007-160746

  An object of the present invention is to form an image on a non-absorbing substrate, which is a soft packaging material, by using a printing process using an ink for ink jet recording, and to improve the image quality without impairing the flexibility of the soft packaging material. It is to provide an image forming method capable of high printing, a laminate for soft packaging by the image forming method, and a method for producing the same.

In order to replace an image forming method on a non-absorbing substrate such as a soft packaging material, which has been conventionally performed by gravure printing, flexographic printing, etc., with various image forming methods using printing by inkjet recording, The present invention was reached through examination and optimization of conditions.
That is, the present invention is a method for forming an image on a soft packaging material, wherein (a) an aqueous inkjet recording ink containing a pigment and a resin is formed on (b) the inkjet receiving layer formed on the surface of the flexible packaging material. (C) forming a printed layer, forming an adhesive layer (d) on the printed layer, and then laminating a molten or film-like polymer (e) forming a sealant film layer, (A) Provided is an image forming method characterized in that the soft packaging material has a thickness of 10 to 100 μm and the receiving layer has a thickness of 2 to 20 μm.
Furthermore, the present invention provides a laminate for soft packaging, wherein the laminate has a printed layer and a sealant film layer formed by the image forming method described above in the laminate. provide.
Furthermore, the present invention is a method for producing a laminate for soft packaging, which is one of the constituent materials of the laminate (a) formed on the surface of the soft packaging material (b) on the inkjet receiving layer, a pigment, And (c) a printing layer is formed using an aqueous inkjet recording ink containing a resin, an adhesive layer (d) is formed on the printing layer, and then a molten or film-like polymer for soft packaging is laminated. And (e) a step of forming a sealant film layer by laminating, wherein the flexible packaging material has a thickness of 10 to 100 μm and the receiving layer has a thickness of 2 to 20 μm. A method for producing the laminate is provided.

In the printing method of the present invention, a printing layer is formed by printing with an ink jet recording method on a receiving layer having a specific thin film thickness range, which is formed on a non-absorbent substrate that is a soft packaging material, and the printing layer Laminated or melted or film-like polymer for soft packaging is laminated on the adhesive layer. Therefore, it is possible to improve the durability of the image formed by protecting the printing layer and to form a high-quality image by inkjet recording on the flexible packaging material without impairing the flexibility of the flexible packaging material. it can.
Furthermore, since the printing method uses printing by the ink jet recording method, compared with the conventional gravure printing method and flexographic printing method, there is no need for a plate making process, and it is possible to cope with various kinds of printing very quickly. is there.

  The raw materials used in the image forming method using ink jet printing according to the present invention and each part of the laminate for soft packaging formed using the same will be described in detail below. In addition, a method for forming an image on a soft packaging material using these raw materials, a laminate for soft packaging having a printed layer on which an image has been formed, and a method for producing the laminate will be described in detail.

As a non-absorbable base material which is a soft packaging material used in the present invention, a base film is preferable, a polyester film such as polyethylene terephthalate or polyethylene naphthalate, a polyolefin film such as polyethylene or polypropylene, or a polyamide film such as nylon. And biodegradable films such as polystyrene film, polyvinyl alcohol film, polyvinyl chloride film, polycarbonate film, polyacrylonitrile film, and polylactic acid film. In particular, a polyester film, a polyolefin film, and a polyamide film are preferable, and polyethylene terephthalate, polypropylene, and nylon are more preferable. The above-mentioned film coated with polyvinylidene chloride or the like for imparting barrier properties may also be used.
The base film, which is a flexible packaging material, may be an unstretched film, but is preferably stretched in a uniaxial or biaxial direction. Further, the surface of the film may be untreated, but those subjected to various treatments for improving adhesive properties such as corona discharge treatment, ozone treatment, low temperature plasma treatment, flame treatment, glow discharge treatment and the like are preferable. The film thickness of the substrate is 10 μm to 100 μm, more preferably 10 μm to 30 μm, as having flexibility, durability and curl resistance suitable for soft packaging applications.

The receiving layer formed on the flexible packaging material in the present invention is used to perform an image by ink jet recording on a non-absorbent substrate so as to satisfy the high drying and fixing properties without bleeding. . As the receiving layer, a receiving layer for ink-jet recording formed on a non-absorbing substrate is used without particular limitation. For example, the following types can be used.
The ink-jet receiving layer contains a microporous type containing porous inorganic fine particles such as silica and alumina compounds and absorbing a solvent in the ink in countless fine voids, and a water-soluble polymer such as polyvinyl alcohol And a swelling type characterized in that the water-soluble polymer absorbs the solvent in the ink by swelling.

  Among the receiving layers as described above, both of them can be used without limitation in the present invention, but the receiving performance of the ink for ink jet recording is good even with a thin film, and the transparency of the film is excellent. The latter swelling-type receiving layer, particularly the one containing an aqueous polyurethane resin in the receiving layer, is preferred as the laminating suitability and does not impair the flexibility of the flexible packaging material itself, and the urethane resin is cationic. More preferably, those having substantially no white inorganic pigment such as silica and clay are preferable because of high transparency.

  The thickness of the receiving layer is 2 to 20 μm, preferably 4 to 15 μm, more preferably 5 to 12 μm. When the film thickness of the receiving layer is too small, a sufficient amount of ink cannot be retained, and the image quality tends to deteriorate. If the film thickness of the receiving layer is too large, the occurrence of curling is observed when a thin substrate is used, and the flexibility of the printed matter itself is lost, and the performance as a flexible packaging material tends not to be satisfied. That is, it is necessary to adjust the film thickness of the receiving layer so that both the image quality, the curl characteristics, and the flexibility are good. In particular, there is a significant trade-off relationship between image quality and curl characteristics when using a thin substrate.

  A known printing or coating method can be used to form the receiving layer on a non-absorbable substrate that is a flexible packaging material. Specifically, printing methods such as gravure printing, offset printing, flexographic printing, screen printing and ink jet printing, and coating of gravure coater, gravure reverse coater, flexo coater, blanket coater, roll coater, knife coater, kiss coater and comma coater A scheme can be used.

  The printing layer formed on the receiving layer by the image forming method of the present invention is produced using an aqueous inkjet recording ink containing a pigment and a resin. Cyan, magenta, yellow, and black are mainly used as the hue of the water-based inkjet recording ink used for forming the printing layer, but may include white, green, and orange. The print layer for flexible packaging is preferably an ink set containing at least white ink, and the white ink pigment is more preferably titanium oxide.

The pigment used in the water-based inkjet recording ink is not particularly limited as long as it can be dispersed in water and a water-soluble organic solvent, and known inorganic and organic pigments can be used. Specifically, examples of the inorganic pigment include titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, and a thermal method.
Specific examples of the organic pigment include an azo pigment, a phthalocyanine pigment, a thioindigo pigment, an isoindolinone pigment, a quinophthalone pigment, a nitro pigment, a nitroso pigment, and aniline black.

  Specific examples of the pigment include carbon black, No. manufactured by Mitsubishi Chemical Corporation. 2300, no. 2200B, no. 900, no. 980, no. 33, no. 40, No, 45, No. 45L, no. 52, HCF88, MA7, MA8, MA100, etc. are Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc. manufactured by Columbia, Regal 400R, Regal 330R, Regal 660R, Mull 660R, Mull 660R Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. are Color Black FW1, FW2, FW2V, FW18, FW200, S170, U , V, 1400U, Special Bla k 6, the 5, 4, 4A, NIPEX150, NIPEX160, NIPEX170, NIPEX180 and the like.

Specific examples of pigments used in yellow ink include C.I. I. Pigment Yellow 1, 2, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 174, 180, 185 and the like.
Specific examples of pigments used in magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 146, 168, 176, 184, 185, 202, 209, etc. It is done.
Specific examples of pigments used for cyan ink include C.I. I. Pigment blue 1, 2, 3, 15, 15: 3, 15: 4, 16, 22, 60, 63, 66, and the like.

In the image forming method of the present invention, it is preferable to have a layer formed of white ink at the bottom layer of the printing layer in order to improve the color of the ink.
Particularly for white pigments, as inorganic pigments, zinc oxide (CI Pigment White 4), ritbon (CI Pigment White 5), titanium oxide (CI Pigment White 6), zinc sulfide ( CI Pigment White 7), Zirconium Oxide (CI Pigment White 12), Calcium Carbonate (CI Pigment White 18), Hydrous Aluminum Silicate (CI Pigment White 19), Barium Sulfate (C Pigment White 21, 22), Alumina White (CI Pigment White 24), Talc (CI Pigment White 26), anhydrous / hydrous silicic acid (Pigment White 27), hydrous calcium silicate (Pigment White 28) ) And the like. Examples of organic pigments include acrylic resin-based, urethane resin-based, styrene resin-based, urea resin-based, benzoguanamine-based, and hollow particle white pigments disclosed in JP-A-2-140271 and JP-A-1-1704. In addition, there are organic-inorganic white pigments in which the above inorganic pigment and organic resin are combined.
In the present invention, any of the above pigments can be used without particular limitation, but it is preferable to use titanium oxide as a pigment having high hiding properties and dispersion stability in water-based ink.

  As the titanium oxide, known rutile type / anatase type titanium dioxide can be used, but rutile type titanium dioxide is preferably used. As an average particle diameter of the titanium oxide used by this invention, it is preferable to use a 100-500 nm thing, and it is more preferable to use a 150-400 nm thing. When the average particle size is 100 nm or less, non-sedimentation and dispersion stability in an aqueous medium are more easily realized, but the whiteness and hiding properties are inferior and the practicality as an original white ink is lowered. When the particle size is 500 nm or more, there is no problem in terms of whiteness and hiding properties, but it is very easy to settle and it is difficult to obtain a stable dispersion in an aqueous medium. In addition, since the size and weight adversely affects the ink ejection properties, it becomes extremely difficult to use as ink for inkjet recording. For these reasons, the practical particle size is more preferably 200 to 300 nm.

As the surface treatment method of titanium oxide, aqueous treatment, gas phase treatment, etc. are performed. For the above reasons, alumina and silica are generally used as the surface treatment agent. Are untreated, treated with alumina, and treated with alumina / silica. As for the pigments treated with alumina / silica, varieties having a higher silica treatment amount than the alumina treatment amount and varieties having a larger alumina treatment amount than the silica treatment amount are commercially available.
The surface treatment of the titanium oxide used in the present invention is preferably such that the ratio of the alumina treatment amount is 35% by mass or more and 80% by mass or less in the total surface treatment amount by the alumina and silica. The amount of these inorganic substances for treating titanium oxide is not necessarily limited, but is generally 30 parts or less with respect to 100 parts of titanium oxide. Further, the titanium oxide that has been surface-treated with a specific amount of alumina and silica may be further surface-treated with a silane coupling agent.

  In the present invention, the pigment may be a so-called self-dispersing pigment (surface-treated pigment) having a water dispersibility-imparting group on its surface and capable of stably maintaining a dispersed state even without a dispersant, or the entire pigment surface. So-called capsule pigments (water-dispersible polymer-containing pigments) that can be coated with a polymer and can stably maintain a dispersed state without a dispersant, or pigments dispersed with a dispersant may be used.

The resin used in the water-based inkjet recording ink used in the present invention includes a dispersion resin and a binder resin. Acrylic, styrene-acrylic, styrene-maleic acid, polyurethane, polyester, polyolefin, vinyl acetate System, polyamide system, silicon system and the like. As the dispersion resin, acrylic resin, styrene-acrylic resin, styrene-maleic acid resin, and polyurethane resin are preferable as those having excellent dispersion stability and pigment dispersion stability.
As the binder resin, an acrylic resin, a styrene-acrylic resin, and a polyurethane resin are preferable, and a urethane resin is preferable among them because the ink jet discharge stability is good, and the adhesiveness to the soft packaging substrate and the laminate suitability are excellent. Further, the resin preferably has a dispersion type having an acid value and no emulsifier, and the Tg of the resin is more preferably 0 ° C. or lower.
The dispersion resin and the binder resin do not necessarily function separately, and one or a plurality of resins may perform both functions. In any case, the ink preferably contains an aqueous polyurethane resin.

Examples of the water-soluble organic solvent used in the water-based inkjet recording ink used in the present invention include those described below as being miscible with water and capable of preventing clogging of the head of an inkjet printer. It is not limited to. For example, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol having a molecular weight of 2000 or less, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butane Examples include diol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, mesoerythritol, pentaerythritol, and the like.
Among them, the inclusion of propylene glycol and 1,3-butyl glycol has safety and excellent effects in ink drying properties and ejection performance.

  As the surfactant used in the aqueous inkjet recording ink used in the present invention, various known surfactants such as nonionic, cationic, or anionic can be used, and acetylene-based surfactants are mainly exemplified. Preferably 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl-1-hexyne-3 -In addition to ol, commercially available products include Surfinol 104, 82, 440, 465, 485, or TG (available from Air Products and Chemicals. Inc.), Olphine STG, Olphine E1004, Olphine E1010 (Nisshin Chemical) Kogyo Co., Ltd.).

  The method for producing the water-based inkjet ink used in the image forming method of the present invention using each of the above components is first a water-based resin varnish containing a pigment and a dispersion resin (including a water-miscible solvent and a basic compound). Disperse a mixture containing an aqueous medium using various dispersing / stirring machines such as a bead mill, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, an ultra high pressure homogenizer, a pearl mill, etc.・ Mixed to prepare a pigment dispersion, and in addition to the binder resin, the remaining materials including surfactant, pigment dispersant, viscosity modifier, antifoaming agent, preservative, etc. are added and mixed as necessary. And a filtering method.

  The ink jet printing method for water-based ink jet produced in this way includes a shuttle method (multi-pass type) in which printing is performed while scanning the head in the width direction of the printing substrate, and a print head having the same dimensions as the width of the printing substrate. An arrayed line system (single pass type) is known, but the printing system for forming the printing layer of the present invention is not limited to either one. As a printing method for flexible packaging where high productivity is desired, a line method (single pass type) capable of high-speed printing is preferable.

  The adhesive layer in the laminate used in the present invention includes acrylic resin, urethane resin, urethane-modified polyester resin, polyester resin, epoxy resin, ethylene-vinyl acetate copolymer resin (EVA), vinyl chloride resin, vinyl chloride-vinyl acetate. Examples thereof include adhesives such as copolymer resins, natural rubber, synthetic rubber such as SBR, NBR, and silicone rubber. Particularly preferable examples of the adhesive for dry laminating include a one-component or two-component curable polyether-polyurethane adhesive, polyester-polyurethane adhesive, and polyester-based adhesive. Preferred examples of the adhesive for extrusion lamination include polyethyleneimine, alkyl titanate, polyurethane resin, and urethane adhesive.

In the image forming method of the present invention, an anchor coat layer can be formed between the non-absorbent substrate, which is a soft packaging material, and the receiving layer in order to improve adhesion. The anchor coat layer in the laminate used in the present invention is made of acrylic resin, urethane resin, urethane-modified polyester resin, polyester resin, epoxy resin, ethylene-vinyl acetate copolymer resin (EVA), vinyl chloride resin, vinyl chloride-vinyl acetate. Adhesives such as copolymer resins, natural rubber, SBR, NBR, and synthetic rubber such as silicone rubber can be mentioned, and polyethyleneimine, alkyl titanate, polyurethane resin, two-component curable polyurethane adhesive and the like are preferable. More preferably, a two-component curable polyurethane adhesive is used for the polyester film, and a polyurethane-based resin is used for the polyolefin film.
In order to form these anchor layers, a known printing or coating method can be used. Specifically, printing methods such as gravure printing, offset printing, flexographic printing, screen printing and ink jet printing, and coating of gravure coater, gravure reverse coater, flexo coater, blanket coater, roll coater, knife coater, kiss coater and comma coater A scheme can be used.

  In the image forming method of the present invention, a melt or film-like polymer for a soft packaging material is laminated on the surface of the printing layer formed on the receiving layer (e) to form a sealant film layer. As the sealant film layer, polyester film such as polyethylene terephthalate and polyethylene naphthalate, polyolefin film such as polyethylene and polypropylene, polyamide film such as nylon, polystyrene film, polyvinyl alcohol film, ethylene vinyl acetate copolymer film, polyvinyl chloride Examples thereof include biodegradable films such as films, polycarbonate films, polyacrylonitrile films, and polylactic acid films. As the sealant film, a film excellent in heat sealability is good, and low density polyethylene, linear low density polyethylene, unstretched polypropylene, and ethylene vinyl acetate copolymer are more preferable.

  The sealant film layer in the image forming method of the present invention is (e) formed by laminating through the adhesive layer (d). The laminating method is not particularly limited, but is a dry laminating method in which a film and a film are bonded by bonding through an adhesive, a non-solvent dry laminating method, an extrusion laminating method in which a molten resin is extruded and formed into a film, Polysand laminating method, hot melt laminating method to apply adhesive that has been melted by heating, wax laminating method, wet laminating method using aqueous adhesive, thermal laminating method by applying heat to the film itself, etc. It is done. Preferably, a dry laminating method, a non-solvent dry laminating method, an extrusion laminating method, or a polysand laminating method is preferable.

  A laminate in which a printed layer is formed on a flexible packaging material using the image forming method of the present invention, and the laminate is laminated can be used as it is as a laminate for flexible packaging, but it is more durable between each layer. A laminate having functions such as heat resistance, water resistance, moisture resistance, light resistance, puncture resistance, and gas barrier properties may be formed. Specifically, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyolefin films such as polyethylene and polypropylene, polyamide-based films such as nylon, polystyrene films, polyvinyl alcohol films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, A biodegradable film such as a polylactic acid film, an ethylene-vinyl alcohol copolymer, an ethylene vinyl acetate copolymer, vinylidene chloride, an aluminum vapor deposition layer, an alumina and silica vapor deposition layer, an aluminum foil, or the like is used. The laminate having these functionalities is laminated with the laminate having the soft packaging material on which the printed layer is formed and laminated, and is used for a flexible packaging bag for foods and the like.

  Hereinafter, although the effect of the present invention is concretely explained using an example and a comparative example, the present invention is not limited to these examples. In the following description, parts indicate parts by weight.

(Resin production example 1)
1000 parts of polytetramethylene ether glycol (PTMG-1000, molecular weight = 1000, manufactured by Mitsubishi Chemical Corporation) was dehydrated at 100 ° C. under reduced pressure, then cooled to 80 ° C., and then 1000 parts of ethyl acetate was added and sufficiently stirred to dissolve. Then, 100 parts of 2,2′-dimethylolpropionic acid was added, and then 400 parts of tolylene diisocyanate was added and reacted at 75 ° C. for 5 hours to carry out a prepolymerization step.
After confirming that the isocyanate value became 1.80 to 1.90%, the mixture was cooled to 40 ° C., neutralized by adding 75 parts of triethylamine, and then water-solubilized by adding 7000 parts of water. Subsequently, chain extension reaction was carried out by adding 36 parts of 80% hydrazine as a chain extender.
Ethyl acetate was removed from the obtained translucent reaction product under reduced pressure at 30 to 60 ° C., water was added to adjust the concentration, and water dispersion of a stable translucent polyurethane resin having a nonvolatile content of 20% was performed. A liquid was obtained.

(Example of pigment dispersion production)
(Cyan pigment dispersion)
Cyan pigment (DIC Corporation FANTOGEN BLUE FSJ-SD) 20 parts, pigment dispersion resin (Big Chemie Japan Co., Ltd. Disperbyk-190) 30 parts, isopropyl alcohol 5 parts, pure water 45 parts are stirred and mixed, and a bead mill is used. After the kneaded meat dispersion, the kneaded meat dispersion was centrifuged to remove coarse particles, and pure water was added to obtain a cyan pigment dispersion adjusted to a solid content of 15%.

(Magenta pigment dispersion)
20 parts of magenta pigment (Fastogen Super Magenta RTS manufactured by DIC Corporation), 30 parts of pigment dispersion resin (Disperbyk-190 manufactured by Big Chemie Japan Co., Ltd.), 5 parts of isopropyl alcohol, and 45 parts of pure water are stirred and mixed using a bead mill. After the kneaded meat dispersion, the kneaded meat dispersion was centrifuged to remove coarse particles, and pure water was added to obtain a magenta dispersion in which the solid content was adjusted to 15%.

(Yellow pigment dispersion)
20 parts of yellow pigment (Fast Yellow 7413 manufactured by Sanyo Dye Co., Ltd.), 30 parts of pigment dispersion resin (Disperbyk-190 manufactured by Big Chemie Japan Co., Ltd.), 5 parts of isopropyl alcohol, and 45 parts of pure water were mixed and stirred using a bead mill. After the kneaded meat dispersion, the kneaded meat dispersion was centrifuged to remove coarse particles, and pure water was added to obtain a yellow pigment dispersion adjusted to a solid content of 15%.

(Black pigment dispersion)
20 parts of black pigment (Carbon Black # 960, manufactured by Mitsubishi Chemical Corporation), 30 parts of pigment dispersion resin (Disperbyk-190, manufactured by Big Chemie Japan Co., Ltd.), 5 parts of isopropyl alcohol, and 45 parts of pure water are stirred and mixed, and a bead mill is used. After the kneaded meat was dispersed, the kneaded meat dispersion was centrifuged to remove coarse particles, and pure water was added to obtain a black pigment dispersion adjusted to a solid content of 15%.

(White pigment dispersion)
40 parts of white pigment (JR-804 manufactured by Teika Co., Ltd.), 10 parts of pigment dispersion resin (Disperbyk-190 manufactured by Big Chemie Japan Co., Ltd.), 5 parts of isopropyl alcohol, and 46 parts of pure water are stirred and mixed using a bead mill. After the meat was dispersed, pure water was added to obtain a white pigment dispersion adjusted to a pigment concentration of 38%.

(Method for measuring solid content of pigment dispersion)
The weight of the evaporating dish (A), the total weight after dropping the pigment dispersion on the evaporating dish (B), and the evaporating dish on which the pigment dispersion was dripped were allowed to stand in a dryer heated to 100 ° C. for 2 hours for moisture. The total amount (C) of the pigment dispersion solidified by evaporating and the evaporation dish is measured, and the solid content is obtained by the following formula.
Solid content (%) = ((C) − (A)) / ((B) − (A)) × 100

(Inkjet ink production example)
(Cyan ink)
26.7 parts of a cyan pigment dispersion, 8.6 parts of the resin composition of Production Example 1, 10 parts of propylene glycol, 10 parts of 1,3-butylene glycol, 0.5 part of a surfactant (Surfinol 440), pure water 44.2 parts were added, and this liquid was filtered through a 0.5 μm glass filter to prepare a cyan ink.

(Magenta ink)
46.7 parts of magenta pigment dispersion, 8.6 parts of the resin composition of Production Example 1, 10 parts of propylene glycol, 10 parts of 1,3-butylene glycol, 0.5 part of surfactant (Surfinol 440), pure water 24.2 parts were added, and this liquid was filtered through a 0.5 μm glass filter to prepare a magenta ink.

(Yellow ink)
33.3 parts of yellow pigment dispersion, 8.6 parts of resin composition of Production Example 1, 10 parts of propylene glycol, 10 parts of 1,3-butylene glycol, 0.5 part of surfactant (Surfinol 440), pure water 37.6 parts were added, and this liquid was filtered through a 0.5 μm glass filter to prepare a yellow ink.

(Black ink)
33.3 parts of black pigment dispersion, 8.6 parts of resin composition of Production Example 1, 10 parts of propylene glycol, 10 parts of 1,3-butylene glycol, 0.5 part of surfactant (Surfinol 440), pure water 37.6 parts was added, and this liquid was filtered through a 0.5 μm glass filter to prepare a black ink.

(White ink)
39.5 parts of white pigment dispersion, 14.2 parts of resin composition of Production Example 1, 10 parts of propylene glycol, 10 parts of 1,3-butylene glycol, 0.5 part of surfactant (Surfinol 440), pure water After mixing 25.8 parts, this liquid was filtered through a 1 μm glass filter to prepare a white ink.

  Table 1 below summarizes the composition of each ink.

(Inkjet layer paint production example)
(Coating composition for receiving layer 1)
10 parts of magnesium chloride, Bondic 2250 [manufactured by Dainippon Ink & Chemicals, Inc., aqueous dispersion of polyurethane having a polycarbonate chain, average particle size 0.2 micron] and WS535 [epichlorohydrin polyamide manufactured by Nippon PMC Co., Ltd.] Resin] 50 parts, Z200 [Nippon Synthetic Chemical Co., Ltd. acetoacetylated polyvinyl alcohol] 50 parts of a solid composition containing a swollen receiving layer coating composition 1 was obtained.

Receiving layer coating composition 2
An aqueous dispersion of a cationic polyurethane resin (Hydran CP-7020 manufactured by DIC), an 8% by mass aqueous solution of PVA145H (manufactured by Kuraray Co., Ltd., polyvinyl alcohol having a saponification degree of 99.5% and a polymerization degree of 4500), and magnesium chloride A 53.5% by mass aqueous solution of hexahydrate was blended so that the mass ratio was 28.6: 66.7: 4.7 to obtain a swelling type ink-jet receiving layer coating composition 2.

Receiving layer coating composition 3
4.4 parts of polyvinyl alcohol (PVAR1130, manufactured by Kuraray Co., Ltd.), 7.7 parts of silica (Mizukasil P-78F, manufactured by Mizusawa Chemical Co., Ltd.), 1.9 parts of calcined kaolin (Alto White TE, manufactured by Showa Chemical Industry Co., Ltd.), Ink fixing agent (Holifix 700, manufactured by Showa Polymer Co., Ltd.) 4.1 parts, Alumina sol (Alumina sol 200, solid content 10%, manufactured by Nissan Chemical Industries, Ltd.) 8.6 parts, Optical brightener (Brangofer UW Liquid, A microporous type compounded with 0.3 part of solid content (manufactured by Bayer) 0.3 part, 0.2 part of nonionic surfactant (SN deformer 480, solid content 100%, made by San Nopco), 72.3 parts of water A receiving layer coating composition 3 was obtained.

(Adhesive adjustment)
10 parts of Dick Dry LX-401 (manufactured by DIC Graphics), 10 parts of curing agent SP-60 (manufactured by DIC Graphics), and 60 parts of ethyl acetate were mixed and stirred for adjustment.

(Example of manufacturing a coating for an anchor coat layer)
(Anchor coat layer paint 1)
Pure water was added to the resin composition of Production Example 1 to obtain a solid content of 10%, thereby obtaining an anchor coat layer coating material 1 (AC agent 1).
(Anchor coat layer paint 2)
Dick Dry LX-500 (manufactured by DIC Graphics) 15 parts, Curing Agent KR-90S (manufactured by DIC Graphics) 1 part, 164 parts of ethyl acetate are mixed and stirred, and paint 2 for anchor coat layer (AC agent 2) )

Example 1
An anchor coat layer coating material (AC agent 1) was applied to a PET film (Ester E-5100, manufactured by Toyobo Co., Ltd.) used for food packaging, to obtain an anchor coat layer. Further, the receiving layer coating composition 1 was applied with a bar coater and dried to obtain an inkjet receiving layer having a thickness of 10 μm. Next, cyan, magenta, yellow, and black ink jet inks were ejected by an ink jet printer having a maximum driving frequency of 7.6 KHz and a resolution of 360 DPI (360 dots per 25.4 mm), and then white ink was ejected, and then 100 ° C. And left in a drier heated for 3 minutes to obtain a printing layer as an ink coating film. Bar coater no. 10 is applied with the adhesive adjusted as described above, the whole is applied with warm air of a dryer for 10 seconds to dry the adhesive, and a CPP film (Pyrene P-1128 manufactured by Toyobo Co., Ltd.) is applied as a sealant film and rolled. Lamination was performed with a laminator set at a temperature of 40 ° C. The laminated product was left in a constant temperature bath at 40 ° C. for 48 hours to obtain a laminate of Example 1.

(Example 2)
A laminate of Example 2 was obtained in the same manner as in Example 1 except that the receiving layer coating composition 2 was used as the receiving layer coating of Example 1.
(Example 3)
A laminate of Example 3 was obtained in the same manner as in Example 1 except that the receiving layer coating composition 3 was used as the receiving layer coating of Example 1.
Example 4
A laminate of Example 4 was obtained in the same manner as in Example 2 except that a PET film (Ester E-5100 manufactured by Toyobo Co., Ltd.) was used as the base film of Example 2.

(Example 5)
A laminate of Example 5 was obtained in the same manner as in Example 2 except that the thickness of the coating material for the receiving layer in Example 2 was changed to 5 μm.
(Example 6)
Except that an anchor coat layer obtained by applying and drying the coating 1 for anchor coat layer with a bar coater # 4 is provided between the base film and the receiving layer in Example 2, and the same as in Example 2 above. A laminate of Example 6 was obtained.
(Example 7)
A laminate of Example 7 was obtained in the same manner as in Example 6 except that the anchor coat layer paint 2 was used as the anchor coat layer paint of Example 6.

(Example 8)
A laminated body of Example 8 was obtained in the same manner as in Example 2 except that an OPP film (film thickness: 20 μm, FOR # 20 manufactured by Futamura Chemical Co., Ltd.) was used as the base film of Example 2.
Example 9
Except that the anchor coat layer obtained by applying and drying the anchor coat layer paint 1 with a bar coater # 4 is provided between the base film and the receiving layer of Example 8, and the same as in Example 8 above. A laminate of Example 9 was obtained.
(Example 10)
A laminate of Example 10 was obtained in the same manner as in Example 9 except that the anchor coat layer paint 2 was used as the anchor coat layer paint of Example 9.

(Comparative Example 1)
A laminate of Comparative Example 1 was obtained in the same manner as in Example 1 except that the coating material for the receiving layer of Example 3 was not used.
(Comparative Example 2)
A laminate of Comparative Example 2 was obtained in the same manner as in Example 3 except that the thickness of the ink-jet receiving layer composition 3 of Example 1 was 35 μm.
(Comparative Example 3)
A laminate of Comparative Example 3 was obtained in the same manner as Comparative Example 2 except that a PET film (Ester E-5100 manufactured by Toyobo Co., Ltd.) was used as the base film of Comparative Example 2.

  The following evaluation items were measured using the laminates produced in Examples 1 to 10 and Comparative Examples 1 to 3. The results are shown in Table 2.

(Evaluation of the physical properties)
(Lamination strength test)
The laminate processed product (2) in which the adhesive is sufficiently cured is cut into a length of 200 mm and a width of 15 mm, and the bonded portion is peeled off by about 30 mm. The peeled portion is subjected to a tensile tester to measure the strength of the laminate adhesion.
A: Strength when peeling a laminated product is 2 N / 15 mm or more B: Strength when peeling a laminated product is 1 N / 15 mm or more to less than 2 N / 15 mm Δ: Strength when peeling a laminated product is 0 .5N / 15mm or more to less than 1N / 15mm x: Strength when peeling a laminated product is less than 0.5N / 15mm (ink jet printability)
After printing with an inkjet printer, the ink repelling and bleeding are visually evaluated.
○: Ink repellency or blemishes △: Ink repellency or bleed is observed ×: Ink repellency or bleed is remarkable

(Adhesion)
A cellophane tape (adhesive tape manufactured by Nichiban Co., Ltd.) was applied to the ink coating film obtained by the above method, and the state of the ink coating film when visually peeled off in the vertical direction was visually observed and evaluated.
○: Ink peeling area less than 10% Δ: Ink peeling area 10% to 50% ×: Ink peeling area 50% or more (flexibility)
The printed laminate obtained by the above method is folded in half at 180 ° to evaluate the flexibility of the laminate.
◯: The laminate is not damaged or deformed by folding in half. Δ: The laminate is slightly deformed by folding in half.
X: The laminate is clearly broken or deformed by folding in half

(Curl resistance)
The ink coating film obtained by the above method was allowed to stand at room temperature for 24 hours, and then the curl property of the printed matter was visually evaluated.
○: No curling is seen Δ: Slight curling is seen ×: Clear curling is seen (transparency)
The transparency of the printed material laminate obtained by the above method was visually evaluated.
○: Transparent △: Slightly opaque ×: Opaque

From the results shown in the above table, the printing method of the present invention produces a high-quality printed layer by printing with an inkjet recording method on a receiving layer having a specific thin film thickness range formed on a non-absorbent substrate. A laminate containing these layers can be formed on a film for a soft packaging material having a specific thin film thickness range, and a high quality image by ink jet recording can be obtained. It can be formed without impairing the flexibility of the flexible packaging material.
As is apparent from Examples 1 to 10, according to the image forming method of the present invention, a good image is formed on a soft packaging substrate film having a film thickness of 100 μm or less for use in a soft packaging material. A suitable laminate can be produced. In addition, the use of an anchor coat layer can further improve the suitability for laminating when both PET and OPP film substrates are used. Both the receiving layer coatings 1 and 2 have better laminating properties and ink jet printing characteristics than the receiving layer coating 3, but the receiving layer coating 2 is better in terms of ink jet printing characteristics. Furthermore, a clearer image could be formed.
As shown in Comparative Example 3, when a receiving layer having a high ink receiving capacity and a large film thickness is used, the ink jet printing characteristics are good, and if the substrate film is made thicker, the curl resistance is good, but the flexibility is improved. In view of properties and transparency, it is not suitable for soft packaging materials. Even if only the film thickness of the base film is reduced or the flexibility is improved by itself, the transparency having a great influence of the receiving layer is not improved, while the curl resistance is greatly reduced. Therefore, as shown in Example 3, the thickness of the base film and the receiving layer are both reduced within the numerical range defined in the present invention, and the flexibility, transparency and curl resistance are maintained while maintaining the ink jet printing characteristics. It is necessary to improve the performance.
Thus, the laminated body in which the image was formed with the image forming method by this invention has the performance excellent in the softness | flexibility and durability as a flexible packaging use.

  The laminated body for soft packaging produced by printing an image on a soft packaging material by the image forming method of the present invention and laminating is suitably used for various soft packaging bags including soft packaging bags for foods. be able to.

Claims (8)

A method for forming an image on a flexible packaging material, wherein (a) an aqueous inkjet recording ink containing a pigment and a resin is used on (b) an inkjet receiving layer formed on the surface of the flexible packaging material (c) A printed layer is formed, (d) an adhesive layer is formed on the printed layer, and then (e) a sealant film layer is formed by laminating by laminating a melted or film-like polymer. An image forming method, wherein the material has a thickness of 10 to 100 μm, and the inkjet receiving layer has a thickness of 2 to 20 μm. The image forming method according to claim 1, wherein the (b) inkjet receiving layer contains an aqueous polyurethane resin. The image forming method according to claim 1, wherein the (b) inkjet receiving layer does not substantially contain a white inorganic pigment. The image forming method according to any one of claims 1 to 3, wherein the water-based inkjet recording ink used for forming the printing layer (c) contains at least a water-based polyurethane resin in the ink. . The image forming method according to any one of claims 1 to 4, wherein an (f) anchor coat layer is formed between the surface of the soft packaging material (b) and the ink jet receiving layer. The image forming method according to claim 1, wherein a white ink containing titanium oxide as a colorant is used as the water-based inkjet recording ink. A laminate for soft packaging, comprising a printed layer and a sealant film layer formed by the image forming method according to any one of claims 1 to 6 in the laminate. Laminated body. A method for producing a laminate for soft packaging, which is one of the constituent materials of the laminate (a) formed on the surface of the soft packaging material (b) containing a pigment and a resin on the inkjet receiving layer (C) A printing layer is formed using the water-based inkjet recording ink, and an adhesive layer (d) is formed on the printing layer, and then laminated by laminating a molten or film-like polymer for soft packaging. (E) comprising a step of forming a sealant film layer, wherein the flexible packaging material has a thickness of 10 to 100 μm and the receiving layer has a thickness of 2 to 20 μm. Production method.