JP6662386B2 - Inkjet precoat agent and image forming method using the same - Google Patents

Description

  The present invention relates to a precoat agent, a packaging film formed using the same, and an image forming method using the same.

  The image forming method using the ink jet method is a method of forming an image by causing ink droplets to adhere to a recording medium by flying small droplets of the ink. This method is characterized in that high-resolution, high-quality images can be printed at a high speed with a relatively simple configuration. Recently, there has been a strong demand for water-based inks as ink agents used for image formation by an ink jet method from the viewpoints of environment, occupational safety, food hygiene and the like. The water-based ink generally contains water and contains a coloring component and a solvent such as glycerin for the purpose of preventing clogging of the ink ejection holes.

  In Japanese Patent Application Laid-Open No. 2010-247528 (U.S. Patent Application Publication No. 2010/245508), even if ink droplets discharged at a high speed land on a substrate, the dot diameters are uniformed to form a uniform image. For this purpose, a method is described in which an aqueous pre-coating agent (aqueous treatment liquid) is applied to a recording medium and dried before ejecting ink to form an image on the recording medium. It is stated that the precoat agent can form an aggregate when it comes into contact with an aqueous ink by containing an organic acid or a cationic resin.

  In recent years, printers for ink jet recording have become widespread, and printing targets are not only paper but also recording media that do not absorb or hardly absorb water-based inks such as plastic films (hereinafter also referred to as non-absorbent recording media). Inkjet printing is widely performed.

  Since non-absorbent recording media do not absorb water-based inks, the use of water-based inks results in extremely poor drying properties, uneven spread of ink that has landed on the recording medium surface, and deformation of dots and color space. There have been problems such as disturbed images such as bleeding and the like, and good color development cannot be obtained and image quality is reduced. Regarding this problem, a pre-coating agent containing an organic acid or the like as disclosed in JP-A-2010-247528 (U.S. Patent Application Publication No. 2010/245508) is applied to the surface of a non-absorbing recording medium. It is known that the processing used is effective (see, for example, JP-A-2014-188675 (U.S. Patent Application Publication No. 2015/376440)).

  In image formation using an aqueous treatment liquid, adhesion of a coating film formed by a precoat agent to a non-absorbing recording medium, and smooth peeling of the film having a coating film formed on the non-absorbing recording medium It is required to have such properties as image resistance such as blocking resistance and rubbing resistance, and flexibility that can follow the deformation of the film.

  Nylon (Ny), polyethylene terephthalate (PET), polypropylene (PP), and the like are widely used as non-absorbable recording media, and one aqueous treatment solution can sufficiently adhere to each of these films. Was extremely difficult to obtain. For this reason, it is necessary to prepare a precoating agent for each material type of the non-absorbent recording medium, or to increase the number of processing steps, thereby reducing productivity.

  In addition, even if a coating film is formed on a non-absorbent recording medium in advance using a precoating agent, the formed image may be rough or the uniformity of the formed image may be reduced. Was not obtained in some cases.

  Therefore, the present invention provides a method for coating a non-absorbing recording medium such as nylon (Ny), polyethylene terephthalate (PET), and polypropylene (PP, particularly expanded polypropylene (OPP)) irrespective of the material of the recording medium. It is an object of the present invention to provide a precoating agent which has high durability of a film and an image formed thereafter and further has good image quality of the formed image.

  The precoat agent of the present invention is characterized in that it includes a cationic urethane resin, and further includes an organic acid and a crosslinking agent capable of forming a crosslinked structure with a functional group in the organic acid.

FIG. 9 is a schematic diagram illustrating a procedure of an image forming method according to a second embodiment. In FIG. 1, reference numeral 100 denotes a recording medium, 200 denotes a precoat layer, and 300 denotes an image. It is a cross section of a packaging film of a 3rd embodiment. In FIG. 2, reference numeral 20 denotes a packaging film, 21 denotes a base material, 22 denotes a precoat layer, 23 denotes an ink layer, 24 denotes an adhesive layer, and 25 denotes a laminate film. FIG. 2 is a schematic diagram illustrating a basic configuration of an inkjet recording apparatus used in an example. 3, reference numeral 11 denotes a head unit, 12 denotes a transport mechanism, 111, 112, 113, and 114 denote heads, and P denotes a recording medium. FIG. 4 is a bottom view illustrating a nozzle arrangement at the bottom of each head of the inkjet recording apparatus of FIG. 3. In FIG. 3, 111 and 112 indicate heads, and N indicates nozzles. FIG. 4 is a schematic diagram of a head unit configuration of the ink jet recording apparatus of FIG. 3. In FIG. 5, H indicates a head, and HU indicates a head unit.

  The first embodiment of the present invention relates to a precoating agent used to form a precoating layer for receiving an ink for forming an image by an ink jet method, comprising water, a cationic resin having a polyurethane structure (hereinafter referred to as cationic urethane). (Also referred to as a resin) is a precoating agent containing an organic acid having two or more identical functional groups and a crosslinking agent capable of reacting with the functional groups.

  When a binder resin is contained in an aqueous precoating agent containing an organic acid as an ink coagulant to improve the adhesion to a non-absorbing recording medium, the coating film strength is reduced, the adhesion is reduced, and the image quality is reduced. The present inventors have found that a decrease in the image quality occurs (see Comparative Example 2 and the like described later). The present inventors have considered that the organic acid which is an ink coagulant remains after forming the coating film by the precoat agent, so that the resin is plasticized to cause such a decrease in performance. As a result of various studies based on such an idea, the configuration of the first embodiment has been reached.

  The pre-coating agent of the first embodiment, even when an image is formed by inkjet ink using various non-absorbing recording media, regardless of the material of the recording medium, the formed coating film and the subsequently formed coating film The durability of the resulting image is high, and the image quality of the formed image is good.

  The detailed mechanism by which the precoat agent of the first embodiment exerts the above effects is unknown, but is presumed as follows.

  When the polyvalent organic acid that has entered the inside of the cationic urethane resin in the precoat agent causes a crosslinking reaction by a crosslinking agent capable of crosslinking the organic acid, for example, by drying after forming the ink layer, the cationic urethane resin and the ink The pigments in the layers become complicatedly entangled. As a result, it is considered that the precoat layer formed by the precoat agent and the ink layer have strong adhesion. Further, the organic acid is consumed by the crosslinking, and the acidity and hydrophilicity in the precoat layer are reduced, so that the water resistance is greatly improved. For example, in the case of a boil or retort application in a packaging laminate film, the laminate film is exposed to hot water, and a portion of the hot water may permeate into the inside of the laminate film from an end or the like. Even in such a case, it is considered that if the precoat agent of the first embodiment is used as a film for packaging, a decrease in adhesion between film layers can be suppressed by improving water resistance. Such an effect can be obtained by selecting a cationic urethane resin as the resin in the precoat agent (comparison between Examples described later and Comparative Example 1).

  Furthermore, the pre-coating agent of the first embodiment hardly inhibits the curing of the laminating adhesive, and greatly improves the laminating strength.

  Hereinafter, the components of the precoat agent will be described.

  In the present specification, unless otherwise specified, operations and measurements of physical properties and the like are performed at room temperature (25 ° C.) / Relative humidity of 40 to 50% RH. In this specification, “X to Y” indicating a range means “X or more and Y or less”.

[Cationic resin having polyurethane structure]
The precoating agent contains a cationic resin having a polyurethane structure. By using a cationic resin having a polyurethane structure, the adhesion to several types of ink non-absorbing recording media having different characteristics, for example, PP (especially OPP), PET, and Ny, which are widely used as packaging materials, is improved. I do.

  The cationic resin having a polyurethane structure is not particularly limited, and examples thereof include (A) a polyol (hereinafter also referred to as a component (A)), (B) a compound containing a cationic group and active hydrogen (hereinafter also referred to as a component (B)). And (C) a polyisocyanate (hereinafter also referred to as a component (C)).

  Examples of the polyol include aliphatic polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol and polyhexamethylene ether glycol; for example, an EO adduct of bisphenol A [2 mol of EO of bisphenol A, 4 mol of EO of bisphenol A] Adduct, bisphenol A EO 6 mol adduct, bisphenol A EO 8 mol adduct, bisphenol A EO 10 mol adduct, bisphenol A EO 20 mol adduct, etc.] and bisphenol A PO adduct [bisphenol A PO 2 mol addition Having a bisphenol skeleton, resorcinol EO or PO adducts, etc.] Aromatic polyether polyol; condensed polyester polyols, polylactone polyols, and polyester polyols and polycarbonate polyols and castor oil-based polyol.

  The condensation type polyester polyol is a polyester polyol obtained by reacting a polyhydric alcohol having the following low molecular weight (chemical formula weight or Mn is less than 300) with a polyvalent carboxylic acid having 2 to 10 carbon atoms or an ester-forming derivative thereof. . Examples of the low molecular weight (chemical formula weight or Mn less than 300) polyhydric alcohol used in the condensation type polyester polyol include dihydric or higher (preferably 2 to 8 valent) aliphatic polyhydric alcohols having a chemical formula weight or Mn of less than 300. And a low molar AO adduct of a phenol having a chemical formula amount or Mn of less than 300 and having a valence of 2 or more (preferably 2 to 8). Among them, ethylene glycol, propylene glycol, 1,4-butanediol, methylpentanediol, neopentyl glycol, 1,6-hexanediol, and a low-molecule EO or PO adduct of bisphenol A are preferred. Such polyhydric alcohols may be used alone or in combination of two or more. Examples of the polyvalent carboxylic acid having 2 to 10 carbon atoms or an ester-forming derivative thereof used in the condensation type polyester polyol include aliphatic dicarboxylic acids (such as succinic acid, adipic acid, azelaic acid, sebacic acid, fumaric acid, and maleic acid). , Alicyclic dicarboxylic acids (cyclohexane dicarboxylic acid, dimer diol, etc.), aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, phthalic acid, etc.), trivalent or higher polycarboxylic acids (trimellitic acid, pyromellitic acid, etc.) ), Their anhydrides (succinic anhydride, maleic anhydride, phthalic anhydride and trimellitic anhydride, etc.), their acid halides (adipate dichloride, etc.), their low molecular weight alkyl esters (dimethyl succinate and phthalate). Acid dimethyl and the like). Such polycarboxylic acids may be used alone or in combination of two or more.

  Specific examples of the condensation type polyester polyol include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butyl adipate diol, and polybutylene Hexamethylene adipate diol, polydiethylene adipate diol, poly (polytetramethylene ether) adipate diol, poly (3-methylpentylene adipate) diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene seba Kate diol, poly-3-methylpentamethylene isophthalate geo Le and polyneopentyl Rutere terephthalate diol.

  The polylactone polyol is a polyadduct of lactone to the low molecular weight (chemical formula weight or Mn is less than 300) polyhydric alcohol. As the lactone, a lactone having 4 to 12 carbon atoms (for example, γ-butyrolactone, γ- Valerolactone and ε-caprolactone).

  Specific examples of the polylactone polyol include, for example, polycaprolactone diol, polyvalerolactone diol, and polycaprolactone triol.

  Examples of the polycarbonate polyol include the above-mentioned polyhydric alcohol having a low molecular weight (chemical formula weight or Mn is less than 300) and a low-molecular carbonate compound (for example, a dialkyl carbonate having 1 to 6 carbon atoms of an alkyl group, an alkylene group having 2 to 6 carbon atoms). And a diaryl carbonate having an aryl group having 6 to 9 carbon atoms), and a polycondensate produced by condensing it with a dealcoholation reaction. Two or more low molecular weight polyhydric alcohols and two or more low molecular carbonate compounds may be used in combination.

  Specific examples of the polycarbonate polyol include polyhexamethylene carbonate diol, polypentamethylene carbonate diol, polytetramethylene carbonate diol, and poly (tetramethylene / hexamethylene) carbonate diol (for example, 1,4-butanediol and 1,6-hexane). A diol obtained by condensing a diol with a dialkyl carbonate while subjecting it to a dealcohol reaction) and poly [cyclohexylenebis (methylene) / hexamethylene] carbonate diol (e.g., dialkylation of 1,4-cyclohexanedimethanol and 1,6-hexanediol) A diol obtained by condensation with a carbonate and a dealcoholation reaction).

  Castor oil-based polyols include castor oil and modified castor oil modified with polyol or AO. Modified castor oil can be produced by transesterification of castor oil and polyol and / or AO addition, such as trimethylolpropane-modified castor oil, pentaerythritol-modified castor oil, and EO (4 to 30 mol) adduct of castor oil. .

  Commercially available polyols can also be used. Commercially available aliphatic polyether polyols include PTMG1000 [poly (oxytetramethylene) glycol with Mn = 1,000, manufactured by Mitsubishi Chemical Corporation] and PTMG2000 [Mn = 2 2,000 poly (oxytetramethylene) glycol, manufactured by Mitsubishi Chemical Corporation], PTMG3000 [poly (oxytetramethylene) glycol with Mn = 3,000, manufactured by Mitsubishi Chemical Corporation] and Sannics Triol GP-3000 [ Commercially available condensed polyester polyols such as poly (oxypropylene) triol with Mn = 3,000, manufactured by Sanyo Chemical Industry Co., Ltd. include Sanesta 2610 [polyethylene adipate diol with Mn = 1,000, Sanyo Chemical Industries Co., Ltd.], Sun Ester 2620 [Mn = 2 Commercially available polycarbonate polyols such as 000 polyethylene adipate diol, manufactured by Sanyo Chemical Industry Co., Ltd.] and Sanester 5620 [polyneopenthylene adipate diol of Mn = 2,000, manufactured by Sanyo Chemical Industry Co., Ltd.] Nipporan 980R [polyhexamethylene carbonate diol with Mn = 2,000, manufactured by Tosoh Corporation], Nipporan 981 [polyhexamethylene carbonate diol with Mn = 1,000, manufactured by Tosoh Corporation], Duranol (registered trademark) G4672 [Poly (tetramethylene / hexamethylene) carbonate diol with Mn = 2,000, manufactured by Asahi Kasei Chemicals Corporation] and Etanacol (registered trademark) UM-90 [poly [cyclohexylenebis (methylene) / hexamethylene with Mn = 900] ] Carbo Tojioru, Ube Industries, Ltd.], and the like.

  These polyols may be used alone or in combination of two or more.

  Examples of the compound containing a cationic group and active hydrogen include, for example, the following formula (1):

However, in the general formula (1), X and Y are each independently -NH- or -O-, and R ¹ is an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl having 1 to 4 carbon atoms. And R ² and R ³ are alkylene groups having 1 to 4 carbon atoms, respectively. Part or all of the compound represented by the formula: Compounds quaternized with a grading agent are exemplified.

In formula (1), examples of the diol compound in which X and Y are —O— and R ¹ is an alkyl group include N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine, and N-isobutyldiethanolamine. , N-methyldipropanolamine and the like. In the general formula (1), examples of the triol compound in which X and Y are —O— and R ¹ is a hydroxyalkyl group include, for example, triethanolamine. In the general formula (1), examples of the diamine compound in which X and Y are —NH— and R ¹ is an alkyl group include, for example, methyliminobispropylamine, butyliminobispropylamine, and the like. In the general formula (1), examples of the triamine compound in which X and Y are —NH— and R ¹ is an aminoalkyl group include, for example, tri (2-aminoethyl) amine.

  Examples of the quaternizing agent for the compound represented by the general formula (1) include epoxy compounds such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, dimethyl sulfate, diethyl sulfate, and paratoluene sulfone. Examples thereof include sulfates such as methyl acid, alkyl halides such as methyl chloride, ethyl chloride, benzyl chloride, methyl bromide and ethyl bromide. One quaternizing agent may be used alone, or two or more quaternizing agents may be used in combination.

  When the compound represented by the general formula (1) is neutralized with an acid, organic acids such as formic acid, acetic acid, propionic acid, butyric acid, lactic acid, malic acid, malonic acid, and adipic acid are used as neutralizing acids. And inorganic acids such as hydrochloric acid, phosphoric acid, and nitric acid. These acids can be used alone or in combination of two or more.

  The quaternizing agent or the acid used for neutralization is before the urethanization reaction, during the urethanization reaction, after the urethanization reaction, before the dispersion step in the aqueous medium, during the dispersion step in the aqueous medium or after the dispersion in the aqueous medium. It may be added at any time.

  These compounds containing a cationic group and active hydrogen may be used alone or in combination of two or more.

  Examples of the polyisocyanate include an aromatic polyisocyanate having 8 to 26 carbon atoms (b1) having 2 to 3 or more isocyanate groups, an aliphatic polyisocyanate having 4 to 22 carbon atoms (b2), and an 8 to 18 carbon atoms. Alicyclic polyisocyanate (b3), aromatic aliphatic polyisocyanate having 10 to 18 carbon atoms (b4), and modified products of these polyisocyanates (b5). The polyisocyanates may be used alone or in combination of two or more.

  Examples of the aromatic polyisocyanate (b1) having 8 to 26 carbon atoms include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (hereinafter abbreviated as TDI), crude TDI, 4,4′- or 2,4′-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), crude MDI, polyaryl polyisocyanate, 4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4, 4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4 ', 4 "-triphenylmethane triisocyanate and m- or p-Isocyanatophenylsulfonyl isocyanate.

  Examples of the aliphatic polyisocyanate (b2) having 4 to 22 carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter abbreviated as HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate and 2-isocyanatoethyl- 2,6-diisocyanatohexanoate.

  Examples of the alicyclic polyisocyanate (b3) having 8 to 18 carbon atoms include isophorone diisocyanate (hereinafter abbreviated as IPDI), 4,4-dicyclohexylmethane diisocyanate (hereinafter abbreviated as hydrogenated MDI), cyclohexylene diisocyanate, methyl Cyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexene-1,2-dicarboxylate and 2,5- or 2,6-norbornane diisocyanate.

  Examples of the araliphatic polyisocyanate (b4) having 10 to 18 carbon atoms include m- or p-xylylene diisocyanate and α, α, α ′, α′-tetramethylxylylene diisocyanate.

  Examples of the modified polyisocyanate (b5) of (b1) to (b4) include the modified polyisocyanate (urethane group, carbodiimide group, allohanate group, urea group, biuret group, uretdione group, uretoimine group, isocyanurate group) Or a modified product containing an oxazolidone group; the content of a free isocyanate group is usually 8 to 33% by mass, preferably 10 to 30% by mass, particularly 12 to 29% by mass), for example, modified MDI (urethane-modified MDI, carbodiimide-modified MDI) And trihydrocarbyl phosphate-modified MDI), urethane-modified TDI, biuret-modified HDI, isocyanurate-modified HDI, and isocyanurate-modified IPDI, and the like.

  The precoating agent is preferably an aqueous cationic urethane resin dispersion.

  The aqueous cationic urethane resin dispersion may be any of a forced emulsification type obtained by dispersing with an external emulsifier; and a self-emulsification type in which a hydrophilic component is introduced into the polyurethane main chain. A self-emulsifying type in which a hydrophilic component is introduced into the polymer is more preferable.

  The aqueous cationic urethane resin dispersion may be synthesized by a known synthesis method. For example, there is a method in which a urethane prepolymer having a hydrophilic group introduced therein is first synthesized in an organic solvent phase, the produced polyurethane prepolymer is phase-inverted and emulsified, and the chain is further extended in an aqueous phase.

  Specifically, a urethane prepolymer having an isocyanate group at a terminal is first prepared using the component (A), the component (B), the component (C) and, if necessary, a chain extender. Examples of the chain extender include low-molecular-weight polyhydric alcohols such as ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, and sorbitol; ethylenediamine; Examples thereof include low molecular weight polyamine compounds such as propanediamine, hexamethylenediamine, diaminocyclohexylmethane, piperazine, 2-methylpiperazine, isophoronediamine, diethylenetriamine, and triethylenetetramine. These chain extenders may be used alone or in combination of two or more.

  The urethane prepolymer can be prepared, for example, by a one-shot method (one-stage method) or a multi-stage isocyanate polyaddition reaction method at a reaction temperature of about 40 to 150 ° C. At this time, if necessary, a reaction catalyst such as dibutyltin dilaurate, stannas octoate, dibutyltin-2-ethylhexoate, triethylamine, triethylenediamine, N-methylmorpholine and the like can be added. One of these reaction catalysts can be used alone, or two or more can be used in combination. Further, an organic solvent which does not react with the isocyanate group can be added at the reaction stage or after the completion of the reaction. Examples of the organic solvent used include acetone, methyl ethyl ketone, toluene, tetrahydrofuran, dioxane, dimethylformamide, N-methylpyrrolidone, and the like.

  A part or all of the nitrilo group of the obtained isocyanate group-terminated prepolymer is quaternized with a quaternizing agent or neutralized with an acid, and then emulsified and dispersed in water to obtain the quaternized isocyanate group-terminated cationized prepolymer. The quaternized polymer is subjected to a chain extension reaction with a chain extender or water to increase the molecular weight. As the chain extender used in this case, in addition to the above-mentioned chain extender, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, Diamines having a hydroxyl group in the molecule such as hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine; alkylenedihydrazines such as methylenedihydrazine, ethylenedihydrazine, propylenedihydrazine, adipic dihydrazide, oxalic dihydrazide, and malon Saturated or unsaturated dihydrazines such as acid dihydrazide, succinic dihydrazide, phthalic acid dihydrazide, itaconic acid dihydrazide, etc .; dimer dimer having a carboxyl group of dimer acid converted to an amino group The emissions and the like. Further, these chain extenders can be used as chain terminators by using an excess of isocyanate groups in the prepolymer (B).

  As the cationic urethane resin, the adhesion, particularly the adhesion to PP is improved, so that the cationic urethane resin is derived from a (meth) acrylate ester having an aliphatic hydrocarbon group having 1 to 18 carbon atoms. Preferably, it contains a structure. Hereinafter, a cationic urethane resin containing a structure derived from a (meth) acrylate ester having an aliphatic hydrocarbon group having 1 to 18 carbon atoms is also referred to as a cationic urethane-acrylic resin. Furthermore, since the adhesion, particularly the adhesion to PP is improved, the cationic urethane resin may include a structure derived from a (meth) acrylate having an aliphatic hydrocarbon group having 6 to 18 carbon atoms. preferable. The reason why the adhesion is improved when the cationic urethane resin contains a structure derived from a (meth) acrylate having an aliphatic hydrocarbon group having 6 to 18 carbon atoms is considered as follows. As a general theory, the adhesion between those having close polarities, that is, those having so-called SP values (solubility parameters) becomes high. A substrate having a higher polarity (SP value) such as PET or Ny has a relatively wide range of material selection, but a substrate having a lower polarity (SP value) such as OPP is limited to materials having similar polarities. OPP is a so-called long-chain alkyl structure in which a propylene structure is connected, and has a similar structure and a structure derived from a (meth) acrylate ester having an aliphatic hydrocarbon group having 6 to 18 carbon atoms. Is considered to be improved. It is also considered that the alkyl chains are longer to some extent, so that the mobility of the resin is improved and the possibility of interaction with the recording medium is increased.

  The cationic urethane-acrylic resin includes (A) a polyol, (B) a cationic active hydrogen component (a compound containing a cationic group and an active hydrogen), (C) a polyisocyanate, and (D) a C1-18 carbon atom. It is obtained by reacting a (meth) acrylic ester having an aliphatic hydrocarbon group (preferably having 6 to 18 carbon atoms) (hereinafter also referred to as component (D)). Here, the components (A) to (C) are as described above. In the present specification, (meth) acrylate refers to acrylate or methacrylate. As described later, the component (D) can also serve as the polyol of the component (A) as an acrylic polyol.

  The (meth) acrylate (D) has an aliphatic hydrocarbon group having 1 to 18 carbon atoms. (D) Examples of the (meth) acrylate having an aliphatic hydrocarbon group having 1 to 18 carbon atoms include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, and n-acrylate. Butyl, i-butyl acrylate, sec-butyl acrylate, t-butyl acrylate, pentyl acrylate, isopentyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, dicyclo acrylate Acrylates such as pentanyl, lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate, stearyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate; Methacrylic I-butyl acrylate, sec-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, n-hexyl methacrylate, t-butyl methacrylate Examples thereof include methacrylates such as cyclohexyl, octyl methacrylate, dicyclopentanyl methacrylate, lauryl methacrylate, hexadecyl methacrylate, and stearyl methacrylate. These (meth) acrylates may be used alone or in combination of two or more.

  The cationic urethane resin can be obtained by reacting another copolymerizable unsaturated monomer in addition to the above (A) to (D). Other copolymerizable unsaturated monomers include styrene (ST), p-methylstyrene, α-methylstyrene, p-chlorostyrene, chloromethylstyrene, aromatic vinyl monomers such as vinyltoluene, acrylonitrile , Unsaturated nitriles such as methacrylonitrile, conjugated diolefins such as butadiene and isoprene, divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, allyl methacrylate, diallyl phthalate, trimethylolpropane triacrylate, Polyfunctional vinyl monomers such as glycerin diallyl ether, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, acrylamide, methacrylamide, n-methylol meth Rilamide, diacetone acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N-isopropylacrylamide, acryloylmorpholine, methacrylamide, N-methylol methacrylamide, diacetone methacrylamide, N, N-dimethylmethacrylamide, Amide monomers such as N, N-diethyl methacrylamide, N-isopropyl methacrylamide, methacryloyl morpholine, 2-hydroxyethyl acrylate (HEMA), 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate Such as hydroxy group-containing monomers, amino group-containing monomers such as dimethylaminoethyl acrylate and diethylaminoethyl acrylate, and (meth) acrylic acid Ether bond-containing monomers such as 2-methoxyethyl and 2- (2-ethoxyethoxy) ethyl (meth) acrylate, and glycidyl ether groups such as glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether Monomer, isocyanate group-containing monomer such as 2-isocyanatoethyl (meth) acrylate, acid monomer such as acrylic acid, methacrylic acid, itaconic acid, p-vinylbenzoic acid, vinyl acetate, vinyl chloride, chloride Vinyl monomers such as vinylidene; These other copolymerizable unsaturated monomers may be used alone or in combination of two or more.

  When the precoating agent contains a cationic urethane-acrylic resin, it is also preferably an aqueous resin dispersion. Such an aqueous resin dispersion is, for example, as described in JP-A-2004-256694, using a (polymer) polyol containing 5 to 50% by mass of an acrylic polyol as a polyol of the component (A), A method for producing an aqueous dispersion of a cationic urethane-acrylic resin is exemplified. The acrylic polyol preferably has a glass transition temperature of −50 to 100 ° C., more preferably −30 to 100 ° C., and still more preferably 0 to 80 ° C., from the viewpoint of adhesion and water resistance. The acrylic polyol preferably has a hydroxyl value of 10 to 100 mgKOH / g.

  The acrylic polyol to be used is a homopolymer or a copolymer obtained from an acrylic monomer having one ethylenically unsaturated group and a hydroxyl group by a bulk polymerization method, a solution polymerization method, or the like. Examples of the acrylic monomer having one ethylenically unsaturated group and a hydroxyl group include, for example, 2-hydroxyethyl acrylate, 3-chloro-2-hydroxybutyl acrylate, 2-hydroxybutyl acrylate, 6-hydroxyhexyl acrylate, Examples thereof include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 6-hydroxyhexyl methacrylate, and 5,6-dihydroxyhexyl methacrylate. These acrylic monomers having one ethylenically unsaturated group and a hydroxyl group can be used alone or in combination of two or more.

  As the acrylic polyol, another monomer copolymerizable with an acrylic monomer having one ethylenically unsaturated group and a hydroxyl group may be used. Examples of such a monomer include (D) a (meth) acrylate ester having an aliphatic hydrocarbon group having 1 to 18 carbon atoms; n-amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-n-butoxyethyl (meth) Acrylate, 2-methoxybutyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, trifluoroethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, hexafluoroisopropyl (meth) acrylate, 2-nitro-2- Methyl propyl (meth) acrylate, Lopentyl (meth) acrylate, cyclohexyl (meth) acrylate, furfuryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylethyl (meth) acrylate, 2-phenoxy Acrylic monomers such as ethyl (meth) acrylate, cinnamyl (meth) acrylate, and (meth) acrylic acid, acrylonitrile, vinyl acetate, vinylpyridine, vinylpyrrolidone, methylcrotonate, maleic anhydride, styrene, α-methylstyrene And the like. These other monomers copolymerizable with the acrylic monomer having one ethylenically unsaturated group and a hydroxyl group may be used alone or in combination of two or more.

(High molecular)
The content of the acrylic polyol in the polyol is preferably from 5 to 50% by mass, more preferably from 7 to 40% by mass, from the viewpoints of weather resistance, toughness, chemical resistance, gloss, abrasion resistance, elasticity, and the like. %, More preferably 10 to 30% by mass.

  Examples of other polymer polyols include, for example, polyester polyol, polyether polyol, polycarbonate polyol, polyacetal polyol, polyesteramide polyol, polythioether polyol, and the like. Among them, polyester polyol, polyether polyol and polycarbonate polyol can be particularly preferably used. These are the same as those described for the component (A).

  Further, dimer diol can be used as the polymer polyol. Dimer diol is a polyol containing a diol obtained by reducing a polymerized fatty acid as a main component. The polymerized fatty acid is obtained by treating an unsaturated fatty acid having 18 carbon atoms such as oleic acid, linoleic acid, etc., a drying oil fatty acid, a semi-dry oil fatty acid or a lower monoalcohol ester compound of these fatty acids in the presence or absence of a catalyst. It is obtained by a subalder type bimolecular polymerization reaction. Although various types of dimer diols are commercially available, typical examples are, for example, 0 to 5% by mass of a monocarboxylic acid having 18 carbon atoms, 70 to 98% by mass of a dimer acid having 36 carbon atoms, and 54% by mass of carbon atoms. Of a trimer acid of 0 to 30% by mass. The dimer diol is effective in improving the water resistance of the cationic acrylic-urethane copolymer due to the effect of suppressing hydrolysis by the aliphatic long-chain alkyl. The content of the dimer diol in the polymer polyol is preferably from 1 to 40% by mass, more preferably from 2 to 30% by mass, and still more preferably from 5 to 20% by mass. As the dimer diol, a commercially available product may be used, and Pripol (registered trademark) 2033 manufactured by Croda Japan, Sovermol (registered trademark) 908 manufactured by BASF, and the like are commercially available.

  Further, the aqueous dispersion containing a cationic urethane-acrylic resin includes the quaternized isocyanate group-terminated cationized prepolymer and (D) a (meth) acryl having an aliphatic hydrocarbon group having 1 to 18 carbon atoms. The urethane prepolymer obtained by reacting the acid ester with another monomer, if necessary, may be obtained by elongating the chain and increasing the molecular weight. In this case, as the other monomer, it is preferable to use an unsaturated monomer containing a hydroxyl group (for example, 2-hydroxyethyl acrylate (HEMA), 2-hydroxyethyl methacrylate, etc.) in combination. The reaction between the urethane prepolymer, (D) a (meth) acrylate having an aliphatic hydrocarbon group having 1 to 18 carbon atoms, and if necessary, other monomers can be carried out by a conventionally known method. For example, the method described in paragraphs “0015” to “0019” of JP-A-2002-302524 can be referred to. Part or all of the nitrile groups of the urethane prepolymer obtained by the above reaction is quaternized with a quaternizing agent as described above, or neutralized with an acid, and then emulsified in water and, if necessary, an alcohol solvent. After dispersion, the quaternized product can be subjected to a chain extension reaction with a chain extender or water. Thereafter, a higher molecular weight can be obtained by further performing a polymerization reaction. As the alcohol-based solvent used at this time, a solvent that does not particularly contain a reactive hydrogen for an isocyanate group (excluding an alcoholic hydroxyl group) in the molecule is preferable. Specific examples thereof include ethyl alcohol, n-propyl alcohol, and the like. Examples include isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, sec-amyl alcohol, diacetone alcohol and the like. The amount of the alcohol-based solvent is not particularly limited, but is usually about 3 to 70% by mass, and preferably 5 to 60% by mass, based on the urethane prepolymer. As the polymerization reaction, radical polymerization is preferable. As the polymerization initiator used in this case, persulfate, hydrogen peroxide and azo compounds (2,2-azobisisobutyronitrile, 2,2-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-amidinopropane) dihydrochloride, dimethyl-2,2′-azobisisobutyrate, etc.) can be used.

  Further, as an aqueous dispersion of a cationic urethane-acrylic resin, as described in JP-A-7-82456, (D) a carbon number in the presence of a prepolymer having a polymerizable unsaturated bond in a side chain. May be obtained by reacting a (meth) acrylic acid ester having an aliphatic hydrocarbon group of 1 to 18 with another monomer if necessary. The prepolymer having a polymerizable unsaturated bond in the side chain has, in addition to the above components (A) to (C), a polymerizable unsaturated group as described in paragraph [0012] of JP-A-7-82456. It can be obtained by subjecting the contained hydroxy compound to a urethanation reaction in an organic solvent. Examples of the hydroxyl compound containing a polymerizable unsaturated group include β-hydroxyethyl methacrylate (HEMA), β-hydroxyethyl acrylate, γ-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, glycerin monoallyl ether, and propylene glycol diglycidyl ether. And acrylic acid adducts. A commercially available hydroxyl compound containing a polymerizable unsaturated group may be used. Examples of the commercially available product include epoxy ester 70PA (manufactured by Kyoeisha Chemical Co., Ltd.). The prepolymer thus obtained is quaternized with a quaternizing agent in the same manner as described above, then emulsified and dispersed in water, and the quaternized product is subjected to a chain extension reaction with a chain extender or a water extender to form a cation. After obtaining the aqueous dispersion of the cationic urethane resin, the aqueous dispersion of the cationic urethane-acrylic resin can be obtained by polymerizing the component (D) and, if necessary, other monomers. The polymerization initiator used in the polymerization reaction is as described above.

  The content of the cationic urethane resin in the precoat agent is preferably 1 to 40% by mass, more preferably 10 to 30% by mass based on the precoat agent, from the viewpoint of aqueous dispersion and coatability. preferable.

[Organic acid having two or more identical functional groups (hereinafter, also simply referred to as organic acid)]
Organic acids have the function of aggregating ink.

Organic acids have two or more identical functional groups. The carbon number of the organic acid is preferably from 2 to 8, and more preferably from 2 to 6, from the viewpoint of water solubility. In addition, as long as the pKa is low as compared with the pigment, dispersant, or anionic group component in the resin present in the ink, any can be used. At least one of them has a pKa of preferably 4.5 or less, more preferably 3.5 or less. Note that the lower limit of pKa is preferably 1 or more. Here, pKa indicates pKa ₁ which is a dissociation index which is the logarithm of the reciprocal of the first acid dissociation constant when the organic acid emits protons in multiple stages. As the pKa, a literature value (pp. 338 to 342 of “Revised 3rd Edition Chemical Handbook Basic Edition II” (edited by The Chemical Society of Japan, Maruzen Co., Ltd., 1984)) can be used. Can also be used.

  The functional group in the two or more identical functional groups (hereinafter, also simply referred to as a functional group) is not particularly limited as long as it is a functional group capable of reacting with a crosslinking agent, and examples thereof include a carboxyl group, a hydroxyl group, an amino group, and a glycidyl group. No. The functional group is preferably a carboxyl group or a hydroxyl group in consideration of water solubility, compatibility with a resin, crosslinking reactivity, and the like, and is a carboxyl group in consideration of an action as a flocculant and improvement in water resistance (ie, And the organic acid contains two or more carboxyl groups). Further, since the same functional group is a carboxyl group (that is, the organic acid contains two or more carboxyl groups) and the cross-linking agent is a cross-linking agent capable of reacting with the carboxyl group, the abrasion resistance of the image recording medium, Bending resistance and strength are improved. This is because the crosslinking agent can crosslink both the organic acid and the anionic ink having a carboxyl group, and the crosslinking causes the resin in the precoat layer compatible with the organic acid and the crosslinking agent to form the ink layer. This is considered to be due to physical entanglement with the adhesive layer, thereby improving the adhesion between the precoat layer and the ink layer.

  The same number of functional groups is preferably 2 to 4, and more preferably 2 to 3, in consideration of water solubility, compatibility with a resin, crosslinking reactivity, and the like.

As the organic acid, specifically, an organic acid having two or more hydroxyl groups such as gluconic acid (pKa 3.86), ascorbic acid (pKa 4.03); oxalic acid (pKa ₁ 1.04), aspartic acid (pKa ₁ 1.93), glutamic acid (pKa ₁ 2.18), malic acid (pKa ₁ 3.24), malonic acid (pKa ₁ 2.65), glutaric acid (pKa ₁ 4.13), maleic acid (pKa ₁₁ ) .75), fumaric acid _(pKa 1 2.85), citric acid _(pKa 1 2.87), succinic acid _(pKa 1 4.00), d-tartaric acid _{(pKa 1 2.82), (R} , R) - tartaric acid _(pKa 1 2.99), an organic acid having 2 or more carboxyl groups, such as 1,2,3-propane tricarboxylic acid _(pKa 1 3.49) and the like.

  The organic acids may be used alone or in combination of two or more.

  It is preferable to include an organic acid having two carboxyl groups or an organic acid having three carboxyl groups as the organic acid, and to include an organic acid having at least two carboxyl groups, since the organic acid has a high function as a coagulant. More preferred.

  Further, since the pKa is low and the water solubility is high and it can be present in a high concentration in the precoat agent, the organic acid is malic acid, malonic acid, glutaric acid, succinic acid, tartaric acid, maleic acid, 1,2,3 -More preferably, it is at least one selected from the group consisting of propanetricarboxylic acid and citric acid.

  In addition, the precoat agent preferably contains an organic acid having two carboxyl groups and an organic acid having three carboxyl groups from the viewpoint of improving adhesion between the precoat layer and the ink layer and bending resistance. The details of the mechanism by which the organic acid having two carboxyl groups and the organic acid having three carboxyl groups are used in combination to improve the adhesion to the ink layer and the bending resistance are unknown. Organic acids having a linear cross-linking structure, while organic acids having three carboxyl groups can form a branched cross-linking structure. The reason is considered to be that the resin has an appropriate flexibility. The organic acids having two carboxyl groups may be used alone or in combination of two or more. The organic acids having three carboxyl groups may be used alone or in combination of two or more. When an organic acid having two carboxyl groups and an organic acid having three carboxyl groups are used in combination, the content ratio of both in the pre-coating agent is determined based on the cohesiveness and crosslinkability of the organic acid having two carboxyl groups. (Total): Organic acids having three carboxyl groups (Total) = 1: 0.01 to 3 are preferable, and 1: 0.1 to 1 are more preferable.

  The content of the organic acid in the precoat agent is preferably from 1 to 50% by mass, more preferably from 1 to 30% by mass, based on the cationic urethane resin, from the viewpoint of cohesiveness and crosslinkability. , And more preferably 5 to 20% by mass.

[Crosslinking agent]
The crosslinking agent is not particularly limited as long as it can react with the same functional group in the organic acid. For example, when the same functional group is a carboxyl group, the crosslinking agent is preferably a compound having two or more functional groups selected from the group consisting of a carbodiimide group, an epoxy group, an oxazoline group, and an azetidinium group. .

  As a compound having two or more carbodiimide groups (-N = C = N-), a known polycarbodiimide can be used. As a compound having two or more carbodiimide groups, a compound having two or more carbodiimide groups can be used in the presence of a carbodiimidization catalyst. A high molecular weight polycarbodiimide produced by subjecting a diisocyanate to a decarboxylation reaction can also be used.

  Examples of such compounds include those obtained by subjecting the following diisocyanates to a decarboxylation condensation reaction. As the diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3′-dimethyl-4,4′-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4′- One of dicyclohexylmethane diisocyanate and tetramethylxylylene diisocyanate, or a mixture of two or more thereof can be used. Examples of the carbodiimidization catalyst include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-3-methyl-2-phospholene-1-oxide, 1-ethyl- Phosphorene oxides such as 2-phospholene-1-oxide or 3-phospholene isomers thereof can be used. Such a high molecular weight polycarbodiimide may be synthesized or a commercially available product may be used. Examples of commercially available products include the Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Co., Ltd.

  Examples of the compound having two or more epoxy groups include N, N, N ′, N′-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane (Trade name: Tetrad (registered trademark) C, manufactured by Mitsubishi Gas Chemical Company), 1,6-hexanediol diglycidyl ether (trade name: Epolite 1600, manufactured by Kyoeisha Chemical Co., Ltd.), neopentyl glycol diglycidyl ether (trade name: Epolite 1500NP, manufactured by Kyoeisha Chemical Co., Ltd., ethylene glycol diglycidyl ether (trade name: Epolite 40E, manufactured by Kyoeisha Chemical Co., Ltd.), diethylene glycol diglycidyl ether (trade name: Epolite 100E, manufactured by Kyoeisha Chemical Co., Ltd.), propylene glycol diglycidyl ether ( Product Name: Epolite 0P, manufactured by Kyoeisha Chemical Co., Ltd.), polyethylene glycol diglycidyl ether (trade name: Epiol (registered trademark) E-400, manufactured by NOF Corporation, trade name: Epolite 200E, 400E, manufactured by Kyoeisha Chemical Co., Ltd.), polypropylene glycol diglycidyl ether (Trade name: Epiol P-200, manufactured by NOF CORPORATION), sorbitol polyglycidyl ether (trade name: Denacol (registered trademark) EX-611, manufactured by Nagase ChemteX Corporation), glycerol polyglycidyl ether (trade name: denacol (registered) Trademark) EX-314, manufactured by Nagase ChemteX Corporation), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (trade name: Denacol (registered trademark) EX-512, manufactured by Nagase ChemteX Corporation), sorbitan polyglycidyl ether, Limethylolpropane polyglycidyl ether, diglycidyl adipate, diglycidyl o-phthalate, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether, and the like. .

  As the compound having two or more oxazoline groups, for example, 2,2′-bis (2-oxazoline), 1,2-bis (2-oxazolin-2-yl) ethane, 1,4-bis (2-oxazoline) -2-yl) butane, 1,8-bis (2-oxazolin-2-yl) butane, 1,4-bis (2-oxazolin-2-yl) cyclohexane, 1,2-bis (2-oxazoline-2 Aliphatic or aromatic bisoxazoline compounds such as -yl) benzene, 1,3-bis (2-oxazolin-2-yl) benzene, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2 -Oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isoprop One or more polymers of addition polymerizable oxazoline such as propenyl-5-ethyl-2-oxazoline, and the like. Commercial products include Epocross (registered trademark) K-2010E (manufactured by Nippon Shokubai Co., Ltd.), Epocross (registered trademark) K-2020E (manufactured by Nippon Shokubai Co., Ltd.), Epocross (registered trademark) K-2030E (manufactured by Nippon Shokubai Co., Ltd.), Epocross (registered trademark) WS-300 (manufactured by Nippon Shokubai), Epocross (registered trademark) WS-500 (manufactured by Nippon Shokubai), Epocross (registered trademark) WS-700 (manufactured by Nippon Shokubai) can be used. .

  Examples of the compound having two or more azetidinium groups include polyazetidinium described in JP-T-2007-505189. As commercial products, WS4030 (manufactured by Seiko PMC Co., Ltd.), ALAFIX (registered trademark) 255 (manufactured by Arakawa Chemical Industries, Ltd.) and the like can be used.

  The content of the cross-linking agent in the precoat agent is preferably 1 to 100% by mass based on the organic acid in consideration of crosslinkability, coating liquid stability in the precoat liquid, coatability of the coating liquid, and the like. It is preferably from 10 to 50% by mass.

[Water and solvent]
The precoat agent contains water as a solvent. The content of water in the solvent is preferably from 1 to 100% by mass, and more preferably from 50 to 100% by mass.

  Further, in addition to water, the solvent may contain a water-soluble organic solvent for the purpose of improving the ejection property and adjusting the physical properties in the case of inkjet coating. The water-soluble organic solvent refers to an organic solvent that can be uniformly mixed in water at an arbitrary ratio. Here, the type of the water-soluble organic solvent is not particularly limited, and examples thereof include glycerin, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol. , Polyethylene glycol, decaglycerin, 1,4-butanediol, 1,3-butanediol, 1,2,6-hexanetriol, 2-pyrrolidinone, dimethylimidazolidinone, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol mono Ethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol Monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol Propylene glycol monoethyl ether, dipropylene glycol monopropyl ether, diethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, tetrapropylene glycol monomethyl ether Ter, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, tripropylene glycol dibutyl ether, 3-methyl-2,4-pentanediol, diethylene glycol monoethyl ether acetate Tart, 1,2-hexanediol, 1,2-pentanediol, 1,2-butanediol and the like can be mentioned. The water-soluble organic solvents may be used alone or in combination of two or more.

[Other ingredients]
The precoat agent may contain other components in addition to the above components. Other components include a foam inhibitor described in JP-A-2014-094494, cellulose derivatives such as polyvinyl alcohol, gelatin, polyvinylpyrrolidone, carboxymethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose, and acrylic acid-based polymers. Curing agents for various hydrophilic polymers, such as boric acid (salt), which is a curing agent for polyvinyl alcohol; coloring dyes, coloring pigments, ultraviolet absorbers, antioxidants, defoamers, leveling agents, interfaces Activators, preservatives, optical brighteners, viscosity stabilizers, pH regulators, matting agents and the like can be mentioned.

[ink]
The precoat agent of the first embodiment is used to form a precoat layer that receives an ink for forming an image by an inkjet method.

  The ink that forms an image by the inkjet method is an anionic ink. By using an anionic ink, the adhesion between the precoat layer and the ink layer is improved by ionic interaction with the cationic urethane resin. The anionic ink includes at least one of a colorant containing an anionic group, a colorant encapsulated with an anionic group-containing compound, a colorant dispersed with an anionic surfactant, and an anionic fixing resin. Refers to the ink to be applied.

  Here, the anionic group includes a carboxyl group, a sulfone group, a phosphoric acid group and the like, and is preferably a carboxyl group.

  The following are mentioned as a coloring agent containing an anionic group. Colorants for yellow or orange include C.I. I. Pigment yellow 62, C.I. I. Pigment Yellow 100, C.I. I. Pigment Yellow 104, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 168, C.I. I. Pigment Yellow 183, C.I. I. Pigment Yellow 191, C.I. I. Solvent Yellow 13, C.I. I. Solvent Yellow 19, C.I. I. Solvent Yellow 21, C.I. I. Solvent Yellow 57, C.I. I. Solvent Yellow 65, C.I. I. Solvent Yellow 82, C.I. I. Pigment Orange 18, C.I. I. Pigment Orange 19, C.I. I. Solvent Orange 6, C.I. I. Solvent Orange 49, C.I. I. Solvent Orange 56, magenta or red pigments include C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 48: 4, C.I. I. Pigment Red 49: 2, C.I. I. Pigment Red 52: 2, C.I. I. Pigment Red 53, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 193, C.I. I. Pigment Red 274, C.I. I. Pigment Red 632, C.I. I. Solvent Red 212, C.I. I. Solvent Red 141, blue or green colorants include C.I. I. Pigment Blue 19, C.I. I. Pigment Blue 24, C.I. I. Pigment Blue 29, C.I. I. Pigment Blue 57, C.I. I. Pigment Blue 61, C.I. I. Pigment Blue 63, C.I. I. Pigment Blue 78, C.I. I. Acid Blue 249, C.I. I. Solvent Blue 38, C.I. I. Solvent Blue 49, C.I. I. Solvent Blue 50, C.I. I. Solvent Blue 70, C.I. I. Solvent Blue 74, C.I. I. Solvent Blue 129, C.I. I. Acid Green 1, C.I. I. Acid Green 12, C.I. I. Solvent Green 7, C.I. I. Solvent Green 13, C.I. I. Solvent Green 15 and C.I. I. Acid Black 1, C.I. I. Acid Black 3, C.I. I. Acid Black 17, C.I. I. Acid Black 20, C.I. I. Acid Black 35, C.I. I. Solvent Black 46, C.I. I. Acid Black 52, C.I. I. Acid Black 54, C.I. I. Acid Black 94, C.I. I. Acid black 124, C.I. I. Acid Black 172, C.I. I. Acid Black 194, C.I. I. Acid Black 210, C.I. I. Acid Black 234.

  Sodium octanoate, sodium decanoate, sodium laurate, sodium myristate, sodium palmitate, sodium stearate, potassium caprate, potassium laurate, potassium myristate, sodium lauryl sulfate, sodium myristyl sulfate Sodium stearyl sulfate, sodium laureth sulfate, sodium polyoxyethylene alkylphenol sulfonate, sodium 1-hexanesulfonate, sodium 1-octanesulfonate, sodium 1-decanesulfonate, sodium 1-dodecanesulfonate, perfluorobutanesulfonic acid, Sodium toluene sulfonate, sodium cumene sulfonate, sodium octylbenzene sulfonate, tetradecenesulfonic acid Thorium, sodium dodecylbenzenesulfonate, perfluorononanoic acid, sodium N-lauroylsarcosine, sodium cocoylglutamate, sodium 2-sulfotetradecanoate 1-methyl ester sodium salt, 2-sulfohexadecanoic acid 1-methyl ester sodium salt, sodium lauryl phosphate And potassium lauryl phosphate.

  As the anionic fixing resin, a resin having an acid neutralized with an amine or a water-dispersible resin can be preferably used. A resin having an acid neutralized by an amine refers to a resin having an acid functional group such as a carboxyl group or a sulfo group in the resin, and the acid functional group in the resin being neutralized by an amine. It is. As a specific example, acrylic, styrene acrylic, acrylonitrile-acrylic, vinyl acetate acrylic, polyurethane, a part of the resin such as polyester, modified with an acid such as carboxyl group or sulfo group, the resin Is neutralized with an amine. Since the amine in the resin is easily evaporated by heating or heating during drying, when the resin having the acid neutralized by the amine attached to the recording medium is heated, only the resin having the acid remains. The amine used for neutralization is preferably ammonia, methylamine, ethylamine, dimethylamine, diethylamine, ethylmethylamine, etc., and ammonia is particularly preferred. A water-dispersible or water-soluble resin having an acid neutralized by an amine can be obtained by polymerizing a monomer. Examples of such a monomer include polymers of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and an acid derivative of styrene. Although there is no particular limitation on the polymerization method, it is preferable to carry out the polymerization by radical copolymerization. Moreover, you may copolymerize with another monomer as needed. The weight average molecular weight of the water-dispersible or water-soluble resin having an acid neutralized by an amine is preferably 1500 or more from the viewpoint of the image quality improving effect, and 100000 or less from the viewpoint of ejection properties and viscosity, and is preferably 3,000 to 3,000. It is more preferably 80,000 and more preferably 10,000 or more and 50,000 or less. Further, the acid value is preferably 5 mgKOH / g or more and less than 300 mgKOH / g. The content of the water-dispersible or water-soluble resin having the acid neutralized by the amine is preferably 2 to 15% by mass of the total mass of the ink. As the water-dispersible or water-soluble resin having an acid neutralized with an amine, a commercially available product may be used. Examples of the commercially available product include Joncryl (registered trademark) JDX6500 (manufactured by BASF) and Joncryl (registered trademark) 690. , Joncryl (registered trademark) 819, Joncryl (registered trademark) PDX-6124, and the like.

  The water-dispersible resin is a sulfonic acid group, a vinyl acetate type having a water-soluble functional group such as a carboxylic acid group, a styrene-butadiene type, a vinyl chloride type, an acryl-styrene type, a butadiene type, a styrene type resin. It is preferably one selected or a mixture thereof.

  From the viewpoint of imparting high-speed cohesion of the water-dispersible resin, those having a carboxylic acid group with a small degree of dissociation are more preferable. Since the carboxylic acid group is easily affected by a change in pH, the dispersion state is easily changed, and the cohesiveness is high. Examples of the resin component added as a water-dispersible resin to the ink include an acrylic resin, a vinyl acetate resin, a styrene-butadiene resin, a vinyl chloride resin, an acryl-styrene resin, a butadiene resin, and a styrene resin. Can be

  The change in the dispersion state with respect to the pH change of the water-dispersible resin has a carboxylic acid group such as an acrylate ester, and can be adjusted by the content ratio of the constituent components in the water-dispersible resin. It can also be adjusted by a surfactant.

  The resin component of the water-dispersible resin is preferably a polymer having both a hydrophilic part and a hydrophobic part. By having a hydrophobic portion, the hydrophobic portion is oriented inside the water-dispersible resin, the hydrophilic portion is efficiently oriented outside, and there is an effect that the change in the dispersion state with respect to the pH change of the liquid becomes larger, Agglomeration is performed more efficiently.

  Examples of commercially available water-dispersible resins include Joncryl (registered trademark) 537, 7640 (styrene-acrylic resin emulsion, manufactured by BASF), Microgel E-1002, E-5002 (styrene-acrylic). Resin emulsion, Nippon Paint Co., Ltd., Boncoat (registered trademark) 4001 (acrylic resin emulsion, manufactured by DIC), Boncoat (registered trademark) 5454 (styrene-acrylic resin emulsion, manufactured by DIC), SAE-1014 ( Styrene-acrylic resin emulsion, manufactured by Zeon Corporation), Julimer (registered trademark) ET-410, FC-30 (above, acrylic resin emulsion, manufactured by Toagosei Co., Ltd.), Alon HD-5, A-104 (above, Acrylic resin emulsion, manufactured by Toagosei Co., Ltd., Cybinol (registered) Mark) SK-200 (acrylic resin emulsion, manufactured by Saiden Chemical Co.), Zaikthene (TM) L (acrylic resin emulsion, manufactured by Sumitomo Seika Chemicals Co., Ltd.) and the like, not limited to this.

  The content of the water-dispersible resin is preferably from 2 to 40% by mass of the total mass of the ink, more preferably from 5 to 30% by mass, and still more preferably from 10 to 25% by mass.

  The weight average molecular weight of the water-dispersible resin to be added to the ink is preferably 5,000 or more in view of the adhesive strength when fused. When it is 5,000 or more, the effect of improving the internal cohesive force of the ink aggregate when agglomerated, the effect of improving the fixability of the image to the recording medium, and the effect of improving the image quality can be obtained.

  The volume average particle diameter of the water-dispersible resin is preferably in the range of 10 nm to 1 μm, more preferably in the range of 10 to 500 nm, still more preferably in the range of 20 to 200 nm, and particularly preferably in the range of 50 to 200 nm. When the thickness is 10 nm or more, the effect of improving the image quality can be exhibited even when the particles are aggregated, and when the thickness is 1 μm or less, the ejection property and storage stability of the ink from the head can be ensured. There is no particular limitation on the volume average particle size distribution of the polymer particles, and any of those having a wide volume average particle size distribution and those having a monodisperse volume average particle size distribution may be used. Further, two or more water-dispersible resins may be mixed and contained in the ink.

  In the preparation of the aqueous ink, a polymer dispersant or a surfactant can be used in the preparation of the pigment dispersion. Here, the polymer dispersant preferably has a polymer component having a weight average molecular weight of 5,000 to 200,000. The weight average molecular weight can be measured by gel permeation chromatography (GPC; standard substance polystyrene). In consideration of the reactivity with the organic acid, it is preferable to use an anionic polymer dispersant. As the polymer dispersant, a copolymer containing styrene as a hydrophobic monomer and acrylic acid as a monomer having an anionic group (hereinafter, referred to as a styrene-acrylic acid copolymer) is preferable. The weight average molecular weight (hereinafter abbreviated as MW) of the styrene-acrylic acid copolymer is preferably from 1,000 to 100,000, more preferably from 4,000 to 30,000. Further, the acid value is preferably from 50 to 500, and more preferably from 150 to 300. Specific examples of such a styrene-acrylic acid copolymer include Joncryl (registered trademark) 501J (29.5% aqueous solution, MW 12000, acid value 205), Joncryl (registered trademark) 678 (MW 8500, acid value 215) ), A high-loss series manufactured by Seiko PMC, and an ARUFON series manufactured by Toagosei Co., Ltd.

(solvent)
The water-based ink has a solvent containing at least water. The water content is preferably from 10 to 99% by mass, and more preferably from 10 to 80% by mass, based on the whole ink.

  The solvent includes a water-soluble organic solvent in addition to water for the purpose of improving ejection properties and adjusting ink physical properties. There is no particular limitation on the type of the water-soluble organic solvent, for example, glycerin, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol , Decaglycerin, 1,4-butanediol, 1,3-butanediol, 1,2,6-hexanetriol, 2-pyrrolidinone, dimethylimidazolidinone, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, Diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol Methyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol Monoethyl ether, dipropylene glycol monopropyl ether, diethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, tetrapropylene glycol monomethyl ether, Ethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, tripropylene glycol dibutyl ether, 3-methyl-2,4-pentanediol, diethylene glycol monoethyl ether acetate , 1,2-hexanediol, 1,2-pentanediol, 1,2-butanediol, and the like. The water-soluble organic solvents may be used alone or in combination of two or more.

  The content of the water-soluble organic solvent is not particularly limited, but is preferably 5% by mass or more and 80% by mass or less based on the total mass of the ink.

(Pigment)
As the pigment that can be used for the ink, conventionally known pigments can be used without particular limitation, and any of a water-dispersible pigment, a solvent-dispersible pigment, and the like can be used.For example, insoluble pigments, organic pigments such as lake pigments, and carbon Inorganic pigments such as black can be preferably used.

  Examples of the insoluble pigment include, but are not particularly limited to, for example, azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, Dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferred.

  Specific pigments that can be preferably used include the following pigments.

  Examples of magenta or red pigments include C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I. I. Pigment red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 222 and the like.

  Examples of orange or yellow pigments include C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 15: 3, C.I. I. Pigment Yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 128, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 138 and the like.

  Examples of green or cyan pigments include C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.

  When red, green, blue and intermediate colors are required in addition to the above, it is preferable to use the following pigments alone or in combination. I. Pigment Red; 209, 224, 177, 194, C.I. I. Pigment Orange; 43, C.I. I. Vat Violet; 3, C.I. I. Pigment Violet; 19, 23, 37, C.I. I. Pigment Green; 36, 7, C.I. I. Pigment Blue; 15: 6, and the like.

  Examples of black pigments include C.I. I. Pigment Black 1, C.I. I. Pigment Black 6, C.I. I. Pigment Black 7 and the like.

  As a method for dispersing the pigment, various dispersing means such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker can be used. It is also preferable to use a centrifugal separator or a filter for the purpose of removing the coarse particles of the pigment dispersion.

  Among them, a sharp particle size distribution of the ink produced by the dispersion by the sand mill is preferable. Further, the material of the beads used for the sand mill dispersion is preferably zirconia or zircon from the viewpoint of contamination of bead fragments and ionic components. Further, the bead diameter is preferably 0.01 mm to 3 mm.

(Other components)
In addition to the above-mentioned components, known surfactants, foam inhibitors, pH adjusters, preservatives, rust preventives, fungicides, and the like can be added to the ink, if necessary.

[Image forming method]
According to a second embodiment of the present invention, a step of forming a precoat layer on a recording medium using the precoat agent of the first embodiment, and forming an image by applying ink to the precoat layer forming surface of the recording medium by an inkjet method And an ink is an anionic ink containing a pigment, water, and a water-soluble organic solvent. In other words, the second embodiment of the present invention employs an ink-jet method on a pre-coat layer forming surface of a recording medium having a pre-coat layer formed using the pre-coat agent of the first embodiment on a base material, This is an image forming method in which an image is formed by applying an anionic ink containing water and a water-soluble organic solvent.

  In the above embodiment, it is preferable to form a precoat layer by applying and drying a precoat agent on the base material prior to image formation.

  Referring to FIG. 1, prior to image formation using ink, first, a precoat layer 200 is formed on the recording medium 100 using the precoat agent of the first embodiment (FIG. 1B). Thereafter, ink is applied to the surface of the recording medium on which the precoat layer is to be formed by an inkjet method to form an image 300 (FIG. 1C).

  The formation of the precoat layer is not particularly limited, and includes an air doctor coater, a blade coater, a lot coater, a knife coater, a squeeze coater, an impregnation coater, a reverse roll coater, a transfer roll coater, a gravure coater, a kiss roll coater, and a cast coater. It is formed by applying a precoat agent on a recording medium by a coating method such as roller coating, ink jet coating, curtain coating, bar coating, spray coating and the like, and then drying. As a method for drying the precoat agent, any method such as natural drying, a heater, a hot air dryer or a heating roller, infrared heating drying, induction heating drying, microwave drying, and vacuum drying can be preferably used. It is preferable to dry by heating with a hot air dryer or a heating roller. In the case of drying with a heater, it may be used alone as a drying means for the precoat agent, or may be used also as a heating means for a coated paper for printing described later. Further, after drying at room temperature (25 ° C.), drying may be performed by heat treatment. The heat treatment temperature at this time is preferably 30 to 120 ° C.

  In addition, if the precoat agent is strongly dried after being applied, the reactivity with the ink may be reduced. On the other hand, if the ink lands in a state where the precoat layer is completely wet, the ink droplets may be disturbed. Therefore, when the in-line continuous and high-speed linear speed (the interval between the application of the precoat agent and the application of the ink is within several seconds), the drying process may be performed such that the solvent is slightly volatilized after the application of the precoat agent.

  The application area of the precoat agent may be either the printing surface only or the entire surface which is both the printing surface and the non-printing surface.

The number of times of applying the precoat agent is not limited, and the precoating agent may be applied once or may be applied in two or more times. The applied amount of the precoat agent to the recording medium is preferably 0.1 to 10 μm as a dry film thickness, more preferably 0.5 to 5 μm, and 0.1 to 10 g / m ² as a coating weight. And more preferably 0.5 to 5 g / m ² .

(Inkjet method)
In the image recording method, an ink layer is formed using ink at least by an inkjet method. The ink used at this time is as described above.

  A method of forming an image by applying ink by an ink jet method can be formed by a conventionally known method. At this time, the printing method may be either a one-pass type or a scan type. The one-pass type ink jet recording method is an ink jet recording method in which, when a recording medium passes under one ink jet head unit, all dots for forming pixels are ejected in one pass. As means for achieving the one-pass type image forming method, it is preferable to use a line head type ink jet head. The line head type ink jet head refers to an ink jet head having a length equal to or larger than the width of the printing range. As a line head type ink jet head, one head may have a width equal to or more than the width of the printing range, or a plurality of heads may be combined to exceed the width of the printing range as disclosed in JP-A-2007-320278. You may comprise. The ink jet head may be of an on-demand type or a continuous type. In addition, as a discharge method, any discharge method such as a mechanical pressure pulse method (such as a piezo method) or an electric-heat conversion method (for example, a thermal inkjet type, a bubble jet (registered trademark) type, or the like) may be used. .

  As a one-pass type (line head type) ink jet recording apparatus applicable to the image forming method of the second embodiment, the apparatus shown in FIG. 1 of JP-A-2010-247528 can be used.

  In the image recording method of the second embodiment, in order to form an image with high image quality and high abrasion resistance and adhesion, and to be able to cope with printing conditions at a higher speed, the recording medium is set at 30 to 100 ° C. The printing may be performed while heating to the above temperature.

  In the second embodiment, even when the precoat agent of the first embodiment is used for a non-absorbing recording medium, the non-absorbing recording medium can be used because the performance is good. Further, as the non-absorbable recording medium, various non-absorbable plastics and films thereof used for flexible packaging are also preferable. Examples of various plastic films include polyethylene terephthalate (PET) film, stretched polystyrene (OPS) film, unstretched polypropylene (CPP) film, stretched polypropylene (OPP) film, nylon (Ny) film, stretched nylon (ONy) film, Examples thereof include a polyvinyl chloride (PVC) film, a polyethylene (PE) film, and a triacetyl cellulose (TAC) film. Other plastics include polycarbonate, acrylic resin, ABS, polyacetal, polyvinyl alcohol (PVA), rubbers and the like. In addition, the present invention can be applied to metals and glasses as a recording medium. Since the precoat layer formed by the precoat agent of the first embodiment has a crosslinked structure, it has high durability against hot water and high temperatures. For this reason, the configuration of the precoat agent of the first embodiment is particularly effective when an image is formed on a PET film, an OPS film, an OPP film, an ONy film, or a PVC film, which can be shrunk by heat.

  The surface of the film may be untreated, but preferably has been subjected to various treatments for improving adhesion, such as corona discharge treatment, ozone treatment, low-temperature plasma treatment, flame treatment, and glow discharge treatment.

  The thickness of the non-absorbent recording medium is not particularly limited, but is preferably 1 to 500 µm, more preferably 2 to 200 µm, and further preferably 5 to 100 µm. Usually, for example, in the case of soft packaging, the thickness is about 10 to 100 μm as having flexibility, durability and curling resistance.

[Packaging film]
The third embodiment of the present invention is a packaging film having a precoat layer formed on a substrate using the precoat agent of the first embodiment.

  FIG. 2 is a schematic cross-sectional view of the packaging film of the third embodiment. The packaging film 20 is formed by laminating a base material (non-absorbable recording medium) 21, a precoat layer 22, an ink layer 23, an adhesive layer 24, and a laminate film 25 in this order.

  The base material (non-ink-absorbing recording medium) 21, the precoat layer 22, and the ink layer 23 can be formed by the image forming method of the above-described second embodiment. The adhesive layer 24 can be formed using a known adhesive such as a polyurethane-based or polyethyleneimine-based adhesive, and if necessary, an isocyanate-based curing agent. The thickness of the adhesive layer is usually about 1 to 3 μm.

  The laminate film 25 is located on the innermost layer and serves as a surface in contact with contents such as food. As the innermost layer heat-sealable film constituting the laminate film, linear low-density polyethylene (hereinafter referred to as LL), low-density polyethylene, high-density polyethylene (hereinafter referred to as HD), unstretched polypropylene (hereinafter referred to as CPP) Etc. can be used. The packaging film may be required to have higher functions depending on the content to be packaged. For example, in the case of retort foods, since the food is packed in a packaging material and then subjected to retort sterilization (high pressure, hot water at 120 ° C. or more for several tens of minutes), higher heat resistance is required for the packaging material. . In addition, it is necessary that the film does not transmit light, does not transmit oxygen, and the like. To exhibit such a function, it is necessary to laminate a plurality of films having various characteristics. For this reason, the laminated film 15 becomes a laminate of a multilayer film (and an adhesive layer) in a high-performance packaging material. Examples of such a highly functional layer include biaxially stretched nylon, biaxially stretched polyethylene terephthalate (biaxially stretched PET), biaxially stretched polypropylene (OPP), and aluminum.

  As a method of laminating the packaging film, known laminations such as dry lamination, non-solvent lamination, and extrusion lamination can be used.

  In the dry lamination method, specifically, the adhesive is applied to one of the base films by a gravure roll method, and then the other base film is laminated and bonded by dry lamination (dry lamination method). In addition, the non-solvent lamination is performed by applying the adhesive previously heated to room temperature to about 120 ° C. on a base film by a roll such as a roll coater heated to room temperature to about 120 ° C., and immediately applying a new film material to the surface thereof. To obtain a laminated film. In the case of the extrusion lamination method, an organic solvent solution of the adhesive is applied as a bonding aid (anchor coating agent) to a base film by a roll such as a gravure roll, and the solvent is dried and cured at room temperature to 140 ° C. After that, a laminated film can be obtained by laminating the polymer material melted by an extruder. As the polymer material to be melted, polyolefin resins such as low-density polyethylene resin, linear low-density polyethylene resin, and ethylene-vinyl acetate copolymer resin are preferable.

  When the thus obtained laminate is used as a packaging material for food, the thickness of the plastic film, ink layer, and adhesive layer to be used is usually controlled so as to be 300 μm or less. Is preferred.

  Since the precoat agent of the first embodiment hardly inhibits the curing of the adhesive layer, the lamination strength of the packaging film using the precoat agent of the first embodiment is greatly improved.

  Specific examples of the present invention will be described together with comparative examples. In Examples, “parts” or “%” may be used, but unless otherwise specified, “parts” or “% by mass” is used. Each operation is performed at room temperature (25 ° C.) unless otherwise specified.

(Synthesis example of precoat resin)
<Synthesis example 1>
230 parts by mass of polycarbonate polyol (molecular weight 1000, trade name Nipporan 981, Tosoh Corporation), 19.2 parts by mass of polyethylene glycol (molecular weight 600), 6.0 parts by mass of trimethylolpropane, and N-methyl 59.6 parts by weight of diethanolamine, 260 parts by weight of 4,4'-dicyclohexylmethane diisocyanate, and 260 parts by weight of methyl ethyl ketone (MEK) were placed in a reaction vessel, and the reaction was carried out while maintaining the temperature at 70 to 75 ° C. A prepolymer was obtained. To this urethane prepolymer, 50.4 parts by mass of dimethyl sulfate was added and reacted at 50 to 60 ° C. for 30 to 60 minutes to obtain a cationic urethane prepolymer having an NCO content of 2.3%. After 1870 parts by mass of water is uniformly added to the obtained cationic urethane prepolymer and emulsified, MEK is recovered to obtain a 30% solids aqueous cationic urethane resin dispersion (dispersion 1). Obtained.

<Synthesis Example 2>
826 parts of a polyester polyol (molecular weight: 2,000) composed of neopentyl glycol and ethylene glycol, cyclohexanedicarboxylic acid and adipic acid (mass composition ratio: 1: 1: 1: 1) and 667 parts of methyl ethyl ketone were added and sufficiently stirred and dissolved. Then, 141 parts of isophorone diisocyanate was added and reacted at 75 ° C. for 1 hour. After completion of the reaction, the mixture was cooled to 60 ° C., 27 parts of N-methyldiethanolamine was added, and the mixture was reacted at 75 ° C. to obtain a prepolymer solution having an NCO content of 0.5% and having a terminal isocyanate group. To this urethane prepolymer, 22.4 parts by mass of dimethyl sulfate was added, and reacted at 50 to 60 ° C. for 30 to 60 minutes. Then, the prepolymer was cooled to 40 ° C., 1500 parts of water was added, and a homomixer was added. Emulsification was performed by high-speed stirring. Methyl ethyl ketone was distilled off from this emulsion under reduced pressure under heating to obtain an aqueous cationic urethane resin dispersion (dispersion 2) having a solid content of 340%.

<Synthesis Example 3>
591 parts of a polyester polyol (molecular weight: 2,000) composed of neopentyl glycol and ethylene glycol, terephthalic acid, isophthalic acid and adipic acid (mass composition ratio: 1: 1: 1: 1: 1), 15 parts of trimethylolpropane, methyl ethyl ketone 667 parts were added and sufficiently stirred and dissolved, and then 305 parts of isophorone diisocyanate was added and reacted at 75 ° C. for 1 hour. After completion of the reaction, the mixture was cooled to 60 ° C, 89 parts of N-methyldiethanolamine was added, and the mixture was reacted at 75 ° C to obtain a prepolymer solution having an NCO content of 1.0% and having a terminal isocyanate group. 65.9 parts by mass of dimethyl sulfate is added to the urethane prepolymer and reacted at 50 to 60 ° C. for 30 to 60 minutes. Then, the prepolymer is cooled to 40 ° C., 1857 parts of water is added, and a homomixer is used. High-speed stirring and emulsification were performed. Methyl ethyl ketone was distilled off from the resin solution under heating and reduced pressure to obtain an aqueous cationic urethane resin dispersion (dispersion 3) having a solid content of 30%.

<Synthesis example 4>
An acrylic polyol composed of methyl methacrylate, butyl methacrylate, 2-hydroxyethyl acrylate, and lauryl acrylate [nonvolatile content of 50% by mass] was placed in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube. 66 g (33 g of acrylic polyol solid content), 80 g of poly-3-methylpentamethylene isophthalate diol [weight average molecular weight 2,000], 80 g of dimer diol [Cropa, Pripol 2033, Number average molecular weight 540] 27 g, N-methyldiethanolamine 3.5 g, dibutyltin dilaurate 0.001 g and methyl ethyl ketone 60 g were charged and uniformly mixed, and then 44.4 g of isophorone diisocyanate was added, followed by reaction at 80 ° C. for 2 hours. Allowed, NCO content was obtained 2.1% prepolymer solution. The solution was cooled to 50 ° C., 3.7 g of dimethyl sulfuric acid was added, then the temperature was raised to 80 ° C., and the mixture was stirred at 80 ° C. for 2 hours. Then, after cooling to 30 ° C., 11.4 g of isophoronediamine was added to this solution, mixed, and 350 g of water was further added, followed by stirring and mixing. This mixed solution was transferred to a four-necked flask equipped with a stir bar and a thermometer, and reacted at 50 ° C. for 6 hours with stirring. The solvent was removed to obtain an aqueous cationic urethane-acrylic resin dispersion (dispersion 4).

<Synthesis example 5>
67.4 parts of N-methyldiethanolamine, 615.6 parts of polytetramethylene ether glycol having a number average molecular weight of 2000, and 540 parts of methyl ethyl ketone are added to a reaction vessel equipped with a stirrer, a thermometer, a cooling pipe, and a nitrogen gas introduction pipe, and sufficiently stirred. After dissolution, 250.0 parts of isophorone diisocyanate was added and reacted at 75 ° C. for 3 hours to obtain a urethane prepolymer having a terminal isocyanate group. Next, 6.3 parts of 2-hydroxyethyl acrylate was charged, and the reaction was further performed at 85 ° C. for 2 hours. Further, 190 parts of stearyl methacrylate was added, and a urethane prepolymer having a double bond in some of the molecules was obtained. Obtained. The urethane prepolymer was cooled to 70 ° C., the stirring was stopped, and the urethane prepolymer was allowed to stand. 69 parts by mass of dimethyl sulfate is added to the urethane prepolymer and reacted at 50 to 60 ° C. for 30 to 60 minutes. Then, the prepolymer is cooled to 40 ° C., and then 2410 parts of water and 100.0 parts of isopropyl alcohol After adding an aqueous solution consisting of 57.5 parts of isophorone diamine, stirring was started again, and the mixture was reacted at 50 ° C. for 3 hours. Methyl ethyl ketone was distilled off under reduced pressure while heating, and an aqueous dispersion of polyurethane resin was obtained. I got Thereafter, the temperature of the aqueous dispersion of the polyurethane resin was raised to 75 ° C., and a solution obtained by dissolving 0.2 part of dimethyl-2,2′-azobisisobutyrate in 40 parts of isopropyl alcohol as a polymerization initiator was applied for 30 minutes. Then, a radical polymerization reaction was started, and further kept at 75 ° C. for 2 hours to complete the radical polymerization reaction to obtain an aqueous cationic urethane-acrylic resin dispersion (dispersion 5).

<Synthesis example 6>
A raw material having the following composition was charged into a two-liter four-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and heated to 90 ° C. while stirring under a nitrogen atmosphere. went.

  90 g of polycaprolactone diol (trade name: Praxel (registered trademark) 220, molecular weight 2,000, manufactured by Daicel Chemical), polyester polyol (neopentyl glycol / terephthalic acid = 1/1 (mass ratio), number average molecular weight 2,000) 120 g, propylene glycol dicricidyl ether-acrylic acid adduct (Kyoeisha Chemical, epoxy ester 70PA) 3.0 g, N-methyldiethanolamine 26.7 g, isophorone diisocyanate 98.0 g, MEK 200 g, N-methylpyrrolidone 10 g.

  Thereafter, the mixture was cooled to 40 ° C. to obtain a prepolymer having a terminal isocyanate group. Next, 28.2 g of dimethyl sulfuric acid was added to the prepolymer, the temperature was raised to 80 ° C, and the mixture was stirred at 80 ° C for 2 hours. Next, after cooling to 30 ° C., 610 g of ion-exchanged water was added. Next, 9.0 g of adipic dihydrazide was added to the reaction system, and stirring was continued at 50 ° C. for 1 hour. Then, MEK was distilled off under reduced pressure to obtain an aqueous urethane having a hydrazide terminal.

  Then, 530 g of the aqueous urethane and 140 g of ion-exchanged water were charged into a 2 liter four-necked flask equipped with a reflux condenser, a nitrogen inlet tube, a thermometer, a dropping funnel and a stirrer, and required 80 minutes at room temperature over 30 minutes. Temperature. A mixture having the following composition was dropped from the dropping funnel over 4 hours.

  10 g of styrene, 40 g of methyl methacrylate, 120 g of 2-ethylhexyl acrylate, 5 g of glycidyl methacrylate, and 16 g of diacetone acrylamide.

  After completion of the dropwise addition, stirring was continued for 1 hour. Next, 5 g of aqueous hydrogen peroxide (35%) was added, and stirring was continued at 80 ° C. for 2 hours to complete the reaction, thereby obtaining an aqueous cationic urethane-acrylic resin dispersion (dispersion 6).

<Synthesis Example 7>
In a 1 L three-necked flask, 400 parts by weight of ion-exchanged water, 5 parts by weight of dimethylaminoethyl methyl methacrylate chloride, 70 parts by weight of methyl methacrylate, 15 parts by weight of butyl acrylate, and 10 parts by weight of 2-ethylhexyl acrylate. The mixture was supplied and heated to 70 ° C. while stirring at a stirring rotation speed of 250 rpm. Next, after supplying 0.5 part by weight of 2,2′-azobis (2-amidinopropane) dihydrochloride (V-50, manufactured by Wako Pure Chemical Industries, Ltd.), the mixture was stirred for 2 hours, and then at 80 ° C. The emulsion polymerization was carried out while stirring for 1 hour. Thereafter, the emulsion was cooled to room temperature to obtain an aqueous dispersion (dispersion 7) of cationic acrylic polymer particles.

(Example 1)
To the cationic urethane resin dispersion (dispersion 1), malonic acid and a carbodiimide-based crosslinking agent (trade name: Carbodilite SV-02 (manufactured by Nisshinbo Chemical Co., Ltd.)) were sequentially added, mixed and dissolved, and then this solution was # 3500. The mixture was filtered through a mesh metal filter and deaerated by a hollow fiber membrane to prepare a precoating agent.

  The amount of ion-exchanged water was adjusted so that the resin solid content in the precoat agent was 20% by mass. Malonic acid was added so as to be 20% by mass based on the solid content of the resin. The crosslinking agent was added so as to be 10% by mass with respect to the resin solid content.

(Examples 2 to 12 and Comparative Examples 1 to 3)
A precoat agent was prepared in the same manner as in Example 1, except that the resin, organic acid and crosslinking agent in the precoat agent were changed as shown in Table 1. Specifically, instead of Dispersion 1, in Examples 2 and 3, a cationic urethane resin dispersion (Dispersions 2 and 3) was used, and in Examples 4 to 6, the cationic urethane-acrylic resin dispersion was used. A precoating agent was prepared in the same procedure as in Example 1 except that the dispersions (dispersions 4 to 6) were used. In Examples 7 to 9, a cationic urethane-acrylic resin dispersion (dispersion 5) was used instead of the dispersion 1, and 1,2,3-propanetricarboxylic acid or malonic acid was used instead of malonic acid. A precoating agent was prepared in the same procedure as in Example 1 except that a mixture of malonic acid and citric acid or a mixture of malonic acid, malic acid and 1,2,3-propanetricarboxylic acid was used. In Examples 10 to 12, a cationic urethane-acrylic resin dispersion (dispersion 5) was used instead of the dispersion 1, and an epoxy-based crosslinking agent and an oxazoline-based crosslinking agent were used instead of the carbodiimide-based crosslinking agent. A precoating agent was prepared in the same procedure as in Example 1 except that an azetidinium-based crosslinking agent was used. In Comparative Example 1, an aqueous dispersion (dispersion 7) of cationic acrylic polymer particles was used in place of Dispersion 1. In Comparative Example 2, no crosslinking agent was added, and in Comparative Example 3, A precoat agent was prepared in the same procedure as in Example 1 except that lactic acid was used instead of malonic acid.

  In Table 1, the epoxy-based crosslinking agent was Epolite 400E (manufactured by Kyoeisha Chemical Co., Ltd.), the oxazoline-based crosslinking agent was Epocross® WS-500 (manufactured by Nippon Shokubai Co., Ltd.), and the azetidinium-based As the cross-linking agent, trade name: WS4030 (manufactured by Seiko PMC) was used.

  In Example 8, malonic acid and citric acid were added at a ratio of 1: 1 (mass ratio), and organic acids were added so that the total amount of organic acids was 20% by mass based on the resin solid content.

  Further, in Example 9, the ratio of malonic acid, malic acid, and 1,2,3-propanetricarboxylic acid was 1: 1: 1 (mass ratio), and the total amount of organic acids was 20% by mass based on the resin solid content. Was added as follows.

<< Preparation of pigment dispersion >>
(Preparation of magenta pigment dispersion)
After mixing 3 parts by mass of Joncryl (registered trademark) 678 (manufactured by BASF), 1.3 parts by mass of dimethylaminoethanol, and 80.7 parts by mass of ion-exchanged water as a pigment dispersant, the mixture was heated and stirred. This mixture was mixed with C.I. I. After 15 parts by mass of Pigment Red 122 was added and premixed, the mixture was dispersed using a sand grinder filled with 0.5% zirconia beads at a volume ratio of 50% to obtain a magenta pigment dispersion having a pigment solid content of 15%. .

(Preparation of cyan pigment dispersion)
After mixing 3 parts by mass of Joncryl (registered trademark) 678 (manufactured by BASF), 1.3 parts by mass of dimethylaminoethanol, and 80.7 parts by mass of ion-exchanged water as a pigment dispersant, the mixture was heated and stirred. This mixture was mixed with C.I. I. After adding 15 parts by mass of CI Pigment Blue 15: 3 and premixing, the mixture was dispersed using a sand grinder filled with 0.5% zirconia beads at a volume ratio of 50% to obtain a cyan pigment dispersion having a pigment solid content of 15%. Obtained.

《Preparation of ink》
(Preparation of Ink 1-M)
Among the additives described below, those excluding the magenta pigment dispersion were mixed at the following addition amounts, and after sufficiently stirring, 33 parts by mass of the magenta pigment dispersion were added with stirring. After sufficiently stirring, the mixture was filtered through a # 3500 mesh metal filter, and deaerated by a hollow fiber membrane to prepare Ink 1-M. Joncryl (registered trademark) JDX6500 is a water-soluble acrylic resin manufactured by BASF and neutralized with an amine, and has an acid value of 74 mgKOH / g, Tg of 65 ° C, and a weight average molecular weight of 10,000.

Magenta pigment dispersion 33 parts by mass Joncryl JDX (registered trademark) 6500 (manufactured by BASF) 7 parts by mass Surfactant: Olfin (registered trademark) E1010 (acetylene glycol-based surfactant, manufactured by Nissin Chemical Co., Ltd.) 0.5 Parts by mass Propylene glycol 15 parts by mass Triethylene glycol monobutyl ether 5 parts by mass Glycerin 14.5 parts by mass Water 25 parts by mass (Preparation of ink 1-C)
Ink 1-C was prepared in the same manner as in the preparation of Ink 1-M, except that the magenta pigment dispersion was changed to the same amount of cyan dispersion.

[Evaluation]
1. Evaluation of formed image [Evaluation of mottling resistance]
<< Preparation of recording medium for evaluation >>
As a recording medium for printing, a single-sided corona-treated biaxially oriented polypropylene film (FOS, manufactured by Futamura Chemical Co., 60 μm) and a single-sided corona-treated biaxially oriented polyethylene terephthalate film (FE2001, manufactured by Futamura Chemical Co., 50 μm) cut to A4 size are used. Was. The precoat agent prepared in each of the above Examples and Comparative Examples was applied to a printing recording medium using a wire bar. The application conditions were set so that the coating thickness of the dried pre-coating agent was in the range of 1 to 2 μm, and the pre-coating agent was air-dried at room temperature after application, thereby producing a recording medium for evaluation in each of Examples and Comparative Examples. .

《Formation of print image》
As shown in FIG. 3, a single-pass system having a basic configuration including a transport mechanism 12 for a recording medium P and a head unit 11 including a plurality of inkjet heads 111 to 114 facing the transported recording medium, as shown in FIG. A line head type) ink jet recording apparatus was used. While transporting the recording medium P to the head unit 11 at a transport speed of 300 mm / s, the ink set A (ink 1-M, ink 1-C) was ejected from the head unit 11. As shown in FIG. 4, each of the heads 111 to 114 constituting the head unit 11 has two heads of 360 dpi, and the two nozzles N are alternately arranged in a direction perpendicular to the feeding direction of the recording medium P. As shown in FIG. 5, a line head system in which a plurality of recording media P are arranged so as to cover the entire width of the recording medium P is used. An ink 1-M constituting the ink set A is ejected from the head 112, and an ink 1-C constituting the ink set A is ejected from the head 111 at a print resolution of 720 dpi × 720 dpi at an ink droplet amount of 16 pl. Each color patch image with a printing rate of １００100% was printed. Next, the recording medium was heated and dried so that the surface temperature of the recording medium became 80 ° C., to obtain a recording medium on which an image was formed.

  For each of the images created above, the occurrence of mottling (deviation of ink) was visually observed, and the mottling resistance was evaluated according to the following criteria.

A: No occurrence of mottling and occurrence of connection between dots are not observed in a patch image having a printing rate of 0 to 100%. B: No occurrence of mottling is observed in a solid image having a high printing rate, but in a medium density region. : Weak occurrence of mottle is observed. C: Clear occurrence of mottle is observed even in a solid image with a high printing ratio.

(Evaluation of bleeding resistance)
A cyan solid image having a printing rate of 100% was printed on a magenta solid image having a printing rate of 100%, and the occurrence of bleeding (image bleeding) was visually observed. The bleeding resistance was evaluated according to the following criteria.

A: Cyan image blur of less than 0.02 mm is observed. B: Cyan image blur of 0.02 mm or more and less than 0.05 mm is recognized. C: Cyan image blur of 0.05 mm or more is recognized.

  In the evaluation of the formed image, at least one of the mottling resistance and the bleeding resistance is preferably A, and more preferably both are A.

2. Precoat layer resistance or image resistance [Substrate adhesion of precoat agent]
One-sided corona-treated biaxially oriented polypropylene film (FOS, 60 μm, OPP manufactured by Futamura Chemical Co., Ltd.), one-sided corona-treated biaxially oriented polyethylene terephthalate film (FE2001, 50 μm, PET manufactured by Futamura Chemical Co., Ltd.) and one-sided corona-treated biaxially stretched nylon film ( It was applied to Toyobo N1102 (25 μm, ONy) using a wire bar, dried at room temperature (25 ° C.), and then heat-treated at 80 ° C. for 5 minutes to obtain an ink jet recording medium coated with a precoat agent. The coating conditions were set so that the pre-coated film thickness after drying was in the range of 1 to 2 μm. The adhesion of the coating film was evaluated according to the grid tape method of JIS K5400. 100 squares of 1 mm square were formed on the application surface in a grid pattern, an adhesive tape was attached, and a tape peeling test was performed. As the adhesive tape, an adhesive tape having an adhesive strength of 10 ± 1 N per 25 mm width (TQC ISO adhesive tape) was used. From the area ratio of the remaining portion of the coating film after the tape peeling test, 5 (100% remaining), 4 (80% to less than 100% remaining), 3 (60% to less than 80% remaining), 2 (20% or more) Five levels of 1 (less than 20% remaining) were determined.

  In addition, it is preferable that it is 4 or more in the evaluation of the substrate adhesion of the precoat agent.

(Blocking resistance of precoat agent)
The above-prepared ink-jet recording medium having an OPP film as a base material, the same OPP film was placed on each coating surface, and the film was allowed to stand at 50 ° C. for 15 hours under a load of 0.5 MPa. Each was peeled off, and the blocking resistance was determined according to the following criteria.

：: The films are peeled off without resistance. Δ: There is resistance when the films are peeled off, but the film is not taken. ×: There is resistance when the films are peeled off, and the film is overlaid with ink. Some are taken.

(Evaluation of scratching of drawn image)
With respect to the image having a printing ratio of 100%, a 9N load was applied to a cotton cloth (Kanakin No. 3) 10 to 30 times after forming the image and after one day at room temperature and normal humidity. Rubbing, ink peeling, and ink transfer to a cotton cloth were visually observed, and the rubbing property was evaluated according to the following criteria.

◎: Ink peeled even after rubbing 30 times, no ink transfer to cotton cloth was observed. ：: Ink peeled after rubbing 30 times, or slight ink transfer to cotton cloth was observed. Δ: Ink after rubbing 30 times. Peeling or ink transfer to cotton cloth was observed. ×: Ink peeling or ink transfer to cotton cloth was observed before rubbing 30 times.

[Evaluation of bending resistance]
With respect to the image having a printing rate of 100% created above, after forming the image, and after a lapse of one day under normal temperature and normal humidity conditions, the recording surface of each recorded image is wound around a stainless steel rod having a diameter of 3 mm at the time. The degree of occurrence of defects such as floating, peeling, and cracks of the generated image was visually observed, and the bending resistance was evaluated according to the following criteria.

◎: No lifting, peeling, or cracking occurred by bending (wrapping). ○: When bending (wrapping) 10 times or more, weak floating, peeling, or cracking was observed. Δ: 2 to 10 times. When bent (wrapped) less, weak floating, peeling, and cracking are observed. ×: Once bent (wrapped), floating, peeling, and cracking are apparently generated.

[Laminate strength]
Laminating adhesive (Takelac (registered trademark) A-525S (base agent) / Takenate (registered trademark) A-50 (curing agent) = 9/1 (mass ratio) on the corona-treated surface of the PET film with a wire bar, Mitsui Chemicals, Inc. Co., Ltd.) to a dry film thickness of 3 μm, and after drying at 70 ° C. for 3 minutes, using a laminator, a precoat and inkjet printing formed on PET prepared in the section of “Printing image formation evaluation of mottling resistance”. It was laminated with the coated surface of the image having a rate of 100%.

The lamination conditions were a temperature of 80 ° C., a pressure of 0.2 N / mm ² , and a pressing time of 90 seconds. After lamination, the laminate was stored at 40 ° C. for 3 days, then a peeling test was performed, and the laminate strength was evaluated according to the following criteria.

  Hold one base material of the non-adhesive part at the end of the laminate film with a jig, pull the other hand with your hand, and pull if there is no peeling, if there is partial peeling, if you can easily peel off Is indicated by x.

  Table 1 below shows the composition of the precoat agent and the evaluation results for each evaluation item.

  From the above results, the precoat layers formed using the precoat agents of Examples 1 to 12 have high adhesiveness to the base material and the ink layer, and have the durability of the recording medium and the image recording medium on which the precoat agent is formed. It was expensive. The quality of the obtained image was also good.

  In particular, the precoating agents of Examples 4 to 6 containing the aqueous urethane-acrylic resin dispersion had good adhesion to any of the substrates, and also improved the image bending resistance. Furthermore, when the precoating agents of Examples 8 and 9 in which an organic acid having two carboxyl groups and an organic acid having three carboxyl groups were used in combination, the abrasion resistance of images on various substrates was high, It had high durability.

  On the other hand, the pre-coating agent of Comparative Example 1 containing an acrylic resin deteriorates image quality, has low adhesion to OPP, and has low image scratch resistance, bending resistance, and lamination strength. Was. Further, the precoating agent of Comparative Example 2 in which no crosslinking agent was present had low adhesion to OPP, and was low in any of the items of blocking resistance, scratch resistance, folding resistance and lamination strength of the precoating agent. became. Furthermore, the precoating agent of Comparative Example 3 using lactic acid having no two or more identical functional groups had low image scratch resistance, bending resistance, and lamination strength.

  From the above, it can be seen that the precoating agents of Examples 1 to 12 are precoating agents that have high durability of the formed coating film and the subsequently formed image, and furthermore, have good image quality of the formed image. .

  This application is based on Japanese Patent Application No. 2015-145267 filed on July 22, 2015, the disclosure of which is referenced and incorporated in its entirety.

Claims (8)

A precoat agent used to form a precoat layer that receives an ink that forms an image by an inkjet method,
A precoat agent comprising water, a cationic resin having a polyurethane structure, an organic acid having two or more identical functional groups, and a crosslinking agent capable of reacting with the functional groups.   The precoating agent according to claim 1, wherein the cationic resin includes a structure derived from a (meth) acrylate having an aliphatic hydrocarbon group having 1 to 18 carbon atoms.   The precoat agent according to claim 1, comprising an organic acid having two carboxyl groups or an organic acid having three carboxyl groups.   4. The organic acid is at least one selected from the group consisting of malic acid, malonic acid, glutaric acid, succinic acid, tartaric acid, maleic acid, 1,2,3-propanetricarboxylic acid and citric acid. The precoat agent according to any one of the above.   The precoating agent according to claim 3, comprising an organic acid having two carboxyl groups and an organic acid having three carboxyl groups.   A packaging film having, on a substrate, a precoat layer formed using the precoat agent according to claim 1.   A pigment, water, and water-soluble ink jet system on a surface of the recording medium having a precoat layer formed using the precoat agent according to any one of claims 1 to 5 on a base material. An image forming method for forming an image by applying an anionic ink containing a neutral organic solvent.   The image forming method according to claim 7, wherein the precoat layer is formed by applying and drying the precoat agent on the base material before the image formation.