JPWO2017013984A1 - Inkjet precoat agent and image forming method using the same - Google Patents

Abstract

For non-absorbing recording media such as nylon (Ny), polyethylene terephthalate (PET), polypropylene (PP, especially OPP), the formed coating film and the image formed thereafter Provided is a precoat agent which is highly durable and has a good image quality of a formed image. A precoat agent used to form a precoat layer that receives ink for forming an image by an inkjet method, comprising water, a cationic resin having a polyurethane structure, two or more organic acids having the same functional group, and A precoat agent comprising a crosslinking agent capable of reacting with a functional group.

Description

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

  An image forming method using an ink jet method is a method in which an ink agent is attached to a recording medium by flying small droplets of the ink agent to form an image. This method is characterized in that a high-resolution and high-quality image can be printed at a high speed with a relatively simple configuration. Recently, there has been a strong demand for water-based ink as an ink agent used for image formation by an ink jet method because of problems such as environment, occupational safety, and food hygiene. The water-based ink generally contains water as a main component, and contains a coloring component and a solvent such as glycerin for the purpose of preventing clogging of ink discharge holes.

  In JP 2010-247528 A (US Patent Application Publication No. 2010/245508), even when ink droplets ejected at high speed land on a substrate, the dot diameters are aligned and a uniform image is formed. For this purpose, a method is described in which an aqueous precoat agent (aqueous processing liquid) is applied onto a recording medium and dried before ink is ejected to form an image on the recording medium. The pre-coating agent contains an organic acid or a cationic resin, so that it can form an aggregate when it comes into contact with water-based ink.

  By the way, in recent years, printers for inkjet recording have become widespread, and not only on paper but also on a recording medium (hereinafter also referred to as a non-absorbing recording medium) that does not absorb or hardly absorb water-based ink such as a plastic film. Ink-jet printing is widely performed.

  Since non-absorbent recording media do not have water-based ink absorbability, when water-based ink is used, the drying property is remarkably inferior, the spread of ink landed on the surface of the recording medium becomes non-uniform, deformation of the dots, There have been problems such as blurring of the image such as blurring, and good coloration cannot be obtained, resulting in a decrease in image quality. Regarding this problem, a precoat agent containing an organic acid or the like as disclosed in JP 2010-247528 A (US Patent Application Publication No. 2010/245508) is applied to the surface of a non-absorbable recording medium. It is known that the treatment used is effective (see, for example, Japanese Patent Application Laid-Open No. 2014-188675 (US Patent Application Publication No. 2015/376440)).

  In image formation using an aqueous processing solution, the adhesion of the coating film formed by the precoat agent to the non-absorbent recording medium, and the films with the coating film formed on the non-absorbing recording medium are smoothly peeled off. Performance such as blocking resistance, image resistance such as scratch resistance and flexibility capable of following deformation of the film is required.

  Nylon (Ny), polyethylene terephthalate (PET), polypropylene (PP), and the like are widely used as non-absorbent recording media, but sufficient adhesion to each of these films with a single aqueous processing solution. It was extremely difficult to obtain. For this reason, it is necessary to prepare a precoat agent for each material type of the non-absorbent recording medium, increase the number of processing steps, etc., and productivity has been reduced.

  Also, even if a coating film is previously formed on a non-absorbent recording medium using a pre-coating agent, the formed image may be roughened or the uniformity of the formed image may be reduced. May not be obtained.

  Therefore, the present invention is applied to a non-absorbent recording medium such as nylon (Ny), polyethylene terephthalate (PET), polypropylene (PP, particularly oriented polypropylene (OPP)), regardless of the material of the recording medium. An object of the present invention is to provide a precoat agent in which the film and the image formed thereafter have high durability and the image quality of the formed image is good.

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

It is a schematic diagram which shows the procedure of the image forming method of 2nd Embodiment. In FIG. 1, 100 is a recording medium, 200 is a precoat layer, and 300 is an image. It is a cross-sectional schematic diagram of the film for packaging of 3rd Embodiment. In FIG. 2, 20 is a packaging film, 21 is a substrate, 22 is a precoat layer, 23 is an ink layer, 24 is an adhesive layer, and 25 is a laminate film. It is a schematic diagram which shows the basic composition of the inkjet recording device used in the Example. In FIG. 3, 11 is a head unit, 12 is a transport mechanism, 111, 112, 113, and 114 are heads, and P is a recording medium. FIG. 4 is a bottom view showing nozzle arrangement at each head bottom portion of the ink jet recording apparatus of FIG. 3. In FIG. 3, 111 and 112 are heads, and N is a nozzle. It is a schematic diagram of the head unit structure of the inkjet recording device of FIG. In FIG. 5, H indicates a head, and HU indicates a head unit.

  1st Embodiment of this invention is a precoat agent used in order to form the precoat layer which receives the ink which forms the image by an inkjet system, Comprising: Water and the cationic resin (henceforth, cationic urethane which has a polyurethane structure) A pre-coating agent comprising an organic acid having two or more identical functional groups and a crosslinking agent capable of reacting with the functional groups.

  When a water-based precoat agent containing an organic acid that is an ink aggregating agent is added with a binder resin in order to improve adhesion to a non-absorbent recording medium, the coating strength decreases, adhesion decreases, image quality The present inventors have found that a decrease in the above occurs (see Comparative Example 2 and the like described later). The present inventors considered that the organic acid, which is an ink aggregating agent, remains after forming a coating film with a pre-coating agent, thereby plasticizing the resin and causing such a decrease in performance. As a result of various studies under such an idea, the configuration of the first embodiment has been achieved.

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

  Although the detailed mechanism by which the precoat agent of the first embodiment exhibits the above effects is unknown, it is estimated as follows.

  When the polyhydric organic acid that has entered 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 layer become intricately entangled. As a result, it is considered that the precoat layer formed of the precoat agent and the ink layer have strong adhesion. In addition, since the organic acid is consumed by crosslinking and the acidity and hydrophilicity in the precoat layer are lowered, the water resistance is greatly improved. For example, in the case of boiled or retort use in a packaging laminate film, it may be exposed to hot water, and part of the hot water may permeate into the laminate film from the end or the like. Even in such a case, if the precoat agent of the first embodiment is used as a packaging film, it is considered that a decrease in adhesion between the 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 precoat agent of the first embodiment has little inhibition of curing of the laminate adhesive and greatly improves the laminate strength.

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

  In this specification, unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (25 ° C.) / Relative humidity 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 precoat agent contains a cationic resin having a polyurethane structure. Use of a cationic resin having a polyurethane structure improves adhesion to PP (particularly OPP), PET, and Ny, which are widely used as a non-ink-absorbing recording medium, for example, as a packaging material. To do.

  The cationic resin having a polyurethane structure is not particularly limited. For example, (A) a polyol (hereinafter also referred to as (A) component), (B) a compound containing a cationic group and active hydrogen (hereinafter referred to as (B) component). And a polyurethane resin obtained by reacting (C) polyisocyanate (hereinafter also referred to as 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, EO addition product of bisphenol A [EO2 mol addition product of bisphenol A, EO4 mol of bisphenol A] Additives, EO 6 mol adduct of bisphenol A, EO 8 mol adduct of bisphenol A, EO 10 mol adduct of bisphenol A, EO 20 mol adduct of bisphenol A, etc. and PO adduct of bisphenol A [PO 2 mol addition of bisphenol A , PO3 mol adduct of bisphenol A, PO5 mol adduct of bisphenol A, etc.] and the like, EO or PO adduct of resorcin, etc. Aromatic polyether polyol; condensed polyester polyols, polylactone polyols, and polyester polyols and polycarbonate polyols and castor oil-based polyol.

  The condensed polyester polyol is a polyester polyol obtained by reacting a polyhydric alcohol having the following low molecular weight (chemical formula amount or Mn is less than 300) with a polyvalent carboxylic acid having 2 to 10 carbon atoms or an ester-forming derivative thereof. . The polyhydric alcohol having a low molecular weight (chemical formula amount or Mn is less than 300) used for the condensed polyester polyol is a dihydric or higher (preferably 2 to 8 valent) aliphatic polyhydric alcohol having a chemical formula amount or Mn of less than 300. And AO low-mole adducts of divalent or higher (preferably 2 to 8) phenols with a chemical formula amount or Mn of less than 300. Among them, ethylene glycol, propylene glycol, 1,4-butanediol, methylpentanediol, neopentyl glycol, 1,6-hexanediol, bisphenol A EO or PO low-mole adduct is preferable. Such polyhydric alcohols may be used alone or in combination of two or more. Examples of polyvalent carboxylic acids having 2 to 10 carbon atoms or ester-forming derivatives thereof used in condensed polyester polyols include aliphatic dicarboxylic acids (succinic acid, adipic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, etc.) , Alicyclic dicarboxylic acids (cyclohexanedicarboxylic 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 (such as succinic anhydride, maleic anhydride, phthalic anhydride and trimellitic anhydride), their acid halides (such as adipic acid dichloride), their low molecular weight alkyl esters (dimethyl succinate and phthalate) Acid dimethyl, etc.). Such polyvalent carboxylic acids may be used alone or in combination of two or more.

  Specific examples of the condensed polyester polyol include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, 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 dio Le and polyneopentyl Rutere terephthalate diol.

  A polylactone polyol is a polyadduct of a lactone to a polyhydric alcohol having the above low molecular weight (chemical formula or Mn is less than 300). 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 polycaprolactone diol, polyvalerolactone diol, and polycaprolactone triol.

  As the polycarbonate polyol, the low molecular weight (chemical formula amount or Mn is less than 300) polyhydric alcohol, a low molecular carbonate compound (for example, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 2 to 6 carbon atoms). And a polycarbonate polyol produced by condensing a dialkyl carbonate having 6 to 9 carbon atoms and a diaryl carbonate having an aryl group having 6 to 9 carbon atoms with a dealcoholization reaction. Two or more low molecular weight polyhydric alcohols and 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, poly (tetramethylene / hexamethylene) carbonate diol (for example, 1,4-butanediol and 1,6-hexane). Diol obtained by condensing a diol with a dialkyl carbonate while subjecting to a dealcoholization reaction) and poly [cyclohexylenebis (methylene) / hexamethylene] carbonate diol (for example, 1,4-cyclohexanedimethanol and 1,6-hexanediol are dialkyl) And a diol obtained by condensation while causing a dealcoholization reaction with carbonate).

  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, for example, trimethylolpropane modified castor oil, pentaerythritol modified castor oil and EO (4-30 mol) adducts of castor oil. .

  As the polyol, a commercially available product can be used, and examples of the commercially available aliphatic polyether polyol include PTMG1000 [poly (oxytetramethylene) glycol with Mn = 1,000, manufactured by Mitsubishi Chemical Corporation], PTMG2000 [Mn = 2. , 1,000 poly (oxytetramethylene) glycol, manufactured by Mitsubishi Chemical Corporation], PTMG3000 [Mn = 3,000 poly (oxytetramethylene) glycol, manufactured by Mitsubishi Chemical Corporation], and Sanniks Triol GP-3000 [ As a commercially available product of condensed polyester polyol such as poly (oxypropylene) triol with Mn = 3,000, manufactured by Sanyo Chemical Industries, Ltd., Sanester 2610 [polyethylene adipate diol with Mn = 1,000, Sanyo Chemical Industries, Ltd.] Manufactured by Co., Ltd.], Sanester 2620 [Mn = 2 Commercially available polycarbonate polyols such as 000 polyethylene adipate diol, manufactured by Sanyo Chemical Industries, Ltd.] and San Ester 5620 [polyneopentylene adipate diol of Mn = 2,000, manufactured by Sanyo Chemical Industries, Ltd.] Nipponran 980R [polyhexamethylene carbonate diol with Mn = 2,000, manufactured by Tosoh Corporation], Nipponran 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 Co., Ltd.] 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 the following formula (1):

However, in the general formula (1), X and Y are each independently -NH- or -O-, ^{R 1} is an alkyl group having 1 to 4 carbon atoms, hydroxyalkyl of 1 to 4 carbon atoms Or an aminoalkyl group having 1 to 4 carbon atoms, and R ² and R ³ are each an alkylene group having 1 to 4 carbon atoms: a part or all of a compound represented by: Examples thereof include compounds quaternized with a classifier.

Examples of the diol compound in which X and Y are —O— in the general formula (1) 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 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 methyliminobispropylamine and butyliminobispropylamine. 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 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, and 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. A quaternizing agent may be used individually by 1 type, or may use 2 or more types together.

  When neutralizing the compound represented by the general formula (1) 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 used 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 having 2 to 3 or more isocyanate groups (b1), an aliphatic polyisocyanate having 4 to 22 carbon atoms (b2), and 8 to 18 carbon atoms. Alicyclic polyisocyanate (b3), araliphatic polyisocyanate (b4) having 10 to 18 carbon atoms and modified product (b5) of these polyisocyanates. Polyisocyanate may be used individually by 1 type, or may be used together 2 or more types.

  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), 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 is mentioned.

  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 is mentioned.

  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, and methyl. Examples include 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.

  As the modified polyisocyanate (b5) of (b1) to (b4), the modified polyisocyanate (urethane group, carbodiimide group, allophanate group, urea group, biuret group, uretdione group, uretoimine group, isocyanurate group) Or modified product containing oxazolidone group, etc .; free isocyanate group content is usually 8 to 33% by mass, preferably 10 to 30% by mass, especially 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.

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

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

  The aqueous cationic urethane resin dispersion may be synthesized by a known synthesis method. For example, a method of first synthesizing a urethane prepolymer having a hydrophilic group introduced therein in an organic solvent phase, phase-inverting and emulsifying the produced polyurethane prepolymer, and further extending the chain in an aqueous phase can be mentioned.

  Specifically, first, a urethane prepolymer having an isocyanate group at the terminal is prepared using a component (A), a component (B), a component (C) and a chain extender as required. 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, sorbitol, ethylenediamine, 1,3- And 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 under a reaction temperature of about 40 to 150 ° C. At this time, a reaction catalyst such as dibutyltin dilaurate, stannous octoate, dibutyltin-2-ethylhexoate, triethylamine, triethylenediamine, N-methylmorpholine can be added as necessary. These reaction catalysts can be used individually by 1 type, or can also be used in combination of 2 or more type. Further, an organic solvent that does not react with an isocyanate group can be added in the reaction step or after the reaction is completed. Examples of the organic solvent to be 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, and the quaternized isocyanate group-terminated cationized prepolymer is obtained. The polymer quaternized product is subjected to 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 chain extender, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2- Diamines having a hydroxyl group in the molecule such as hydroxypropylethylenediamine and di-2-hydroxypropylethylenediamine; alkylenedihydrazines such as methylenedihydrazine, ethylenedihydrazine and propylenedihydrazine, adipic acid dihydrazide, oxalic acid dihydrazide, and malon Saturated or unsaturated dihydrazines such as acid dihydrazide, succinic acid dihydrazide, phthalic acid dihydrazide, and itaconic acid dihydrazide; dimeria obtained by converting the carboxyl group of dimer acid to amino group The emissions and the like. Moreover, these chain extenders can be used as a chain length terminator by using excessively with respect to the isocyanate group in a prepolymer (B).

  As a cationic urethane resin, since adhesiveness, especially adhesiveness to PP is improved, the cationic urethane resin is derived from a (meth) acrylic acid ester having an aliphatic hydrocarbon group having 1 to 18 carbon atoms. It preferably includes a structure. Hereinafter, a cationic urethane resin including a structure derived from a (meth) acrylic acid ester having an aliphatic hydrocarbon group having 1 to 18 carbon atoms is also referred to as a cationic urethane-acrylic resin. Furthermore, since adhesiveness, especially adhesiveness to PP is improved, the cationic urethane resin may contain a structure derived from a (meth) acrylic acid ester having an aliphatic hydrocarbon group having 6 to 18 carbon atoms. preferable. It is considered as follows that the adhesion is improved when the cationic urethane resin contains a structure derived from a (meth) acrylic acid ester having an aliphatic hydrocarbon group having 6 to 18 carbon atoms. In general terms, the closeness of the polarities, the closeness of the so-called SP values (solubility parameters) are increased. Substrates with a high polarity (SP value) such as PET and Ny have a relatively wide range of material selection, but substrates with a low polarity (SP value) such as OPP are limited to materials with similar polarities. OPP has a propylene structure, a so-called long-chain alkyl structure, and has a structure derived from a (meth) acrylic acid ester having an aliphatic hydrocarbon group having 6 to 18 carbon atoms having a similar structure. Is thought to improve. In addition, since the alkyl chain is long to some extent, it is considered that the mobility of the resin is improved and the possibility of interaction with the recording medium is increased.

  The cationic urethane-acrylic resin has (A) polyol, (B) cationic active hydrogen component (a compound containing a cationic group and active hydrogen), (C) polyisocyanate, and (D) 1 to 18 carbon atoms. It is obtained by reacting (meth) acrylic acid ester (preferably also referred to as component (D)) having an aliphatic hydrocarbon group (preferably having 6 to 18 carbon atoms). Here, the components (A) to (C) are as described above. In this specification, (meth) acrylic acid ester refers to acrylic acid ester or methacrylic acid ester. The component (D) can also serve as the polyol of the component (A) as an acrylic polyol, as will be described later.

  The (meth) acrylic ester of (D) has an aliphatic hydrocarbon group having 1 to 18 carbon atoms. (D) As a (meth) acrylic acid ester having an aliphatic hydrocarbon group having 1 to 18 carbon atoms, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, 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, dicycloacrylate Acrylic esters such as pentanyl, lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate, stearyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, Metacri I-butyl acid, sec-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, n-hexyl methacrylate, t-butyl methacrylate And methacrylic acid esters such as cyclohexyl, octyl methacrylate, dicyclopentanyl methacrylate, lauryl methacrylate, hexadecyl methacrylate and stearyl methacrylate. These (meth) acrylic acid esters may be used alone or in combination of two or more.

  The cationic urethane resin can be obtained by reacting other copolymerizable unsaturated monomers in addition to the above (A) to (D). Other copolymerizable unsaturated monomers include styrene (ST), aromatic vinyl monomers such as p-methylstyrene, α-methylstyrene, p-chlorostyrene, chloromethylstyrene, vinyltoluene, and 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, Multifunctional vinyl monomers such as glyceryl diallyl ether, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, acrylamide, methacrylamide, n-methylol meta Rilamide, diacetone acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N-isopropylacrylamide, acryloylmorpholine, methacrylamide, N-methylolmethacrylamide, diacetone methacrylamide, N, N-dimethylmethacrylamide, Amide monomers such as N, N-diethylmethacrylamide, N-isopropylmethacrylamide, methacryloylmorpholine, 2-hydroxyethyl acrylate (HEMA), 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate Hydroxy group-containing monomers such as dimethylaminoethyl acrylate, amino group-containing monomers such as diethylaminoethyl acrylate, (meth) acrylic acid Ether bond-containing monomers such as 2-methoxyethyl and 2- (2-ethoxyethoxy) ethyl (meth) acrylate, glycidyl ether groups such as glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether -Containing 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 And vinyl monomers such as vinylidene. These other copolymerizable unsaturated monomers may be used alone or in combination of two or more.

  Also when a precoat agent contains cationic urethane-acrylic resin, it is preferable that it is a water-based resin dispersion. Such an aqueous resin dispersion, for example, as described in JP-A No. 2004-256694 uses a (polymer) polyol containing 5 to 50% by mass of an acrylic polyol as a polyol of the component (A), The method of manufacturing the aqueous dispersion of a cationic urethane-acrylic resin is mentioned. 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 viewpoints of adhesion and water resistance. The acrylic polyol preferably has a hydroxyl value of 10 to 100 mgKOH / g.

  The acrylic polyol used is a homopolymer or copolymer obtained from an acrylic monomer having one ethylenically unsaturated group and a hydroxyl group by a bulk polymerization method or a solution polymerization method. Examples of the acrylic monomer having one ethylenically unsaturated group and a hydroxyl group include 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) (meth) acrylic acid 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- Methylpropyl (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, (meth) acrylic acid, acrylonitrile, vinyl acetate, vinylpyridine, vinylpyrrolidone, methylcrotonate, maleic anhydride, styrene, α-methylstyrene And ethylenic monomers. These other monomers copolymerizable with an 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 5 to 50% by mass, more preferably 7 to 40% by mass from the viewpoints of weather resistance, toughness, chemical resistance, gloss, wear resistance, elasticity, and the like. %, And more preferably 10 to 30% by mass.

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

  Moreover, dimer diol can be used as a polymer polyol. Dimer diol is a polyol mainly composed of diol obtained by reducing polymerized fatty acid. The polymerized fatty acid is an unsaturated fatty acid having 18 carbon atoms such as oleic acid and linoleic acid, a dry oil fatty acid, a semidry oil fatty acid or a lower monoalcohol ester compound of these fatty acids in the presence or absence of a catalyst. This is a Zulder type bimolecular polymerization reaction. Various types of dimer diols are commercially available. Representative examples include, for example, 0 to 5% by mass of monocarboxylic acid having 18 carbon atoms, 70 to 98% by mass of dimer acid having 36 carbon atoms, and 54 carbon atoms. Some of them consist of 0-30% by weight of trimer acid. The dimer diol is effective in improving the water resistance of the cationic acrylic-urethane copolymer due to the effect of inhibiting hydrolysis by the aliphatic long-chain alkyl. The content of the dimer diol in the polymer polyol is preferably 1 to 40% by mass, more preferably 2 to 30% by mass, and further preferably 5 to 20% by mass. Commercial products may be used as the dimer diol, such as Pripol (registered trademark) 2033 of Croda Japan, and Sovermol (registered trademark) 908 of BASF.

  Moreover, as an aqueous dispersion containing a cationic urethane-acrylic resin, the above-mentioned quaternized isocyanate group-terminated cationized prepolymer and (D) a (meth) acryl having an aliphatic hydrocarbon group having 1 to 18 carbon atoms. A urethane prepolymer obtained by reacting an acid ester with other monomers as necessary may be obtained by chain extension / high molecular weight. At this time, it is preferable to use an unsaturated monomer containing a hydroxyl group (for example, 2-hydroxyethyl acrylate (HEMA), 2-hydroxyethyl methacrylate, etc.) as the other monomer. The reaction between the urethane prepolymer, (D) a (meth) acrylic acid ester 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 nitrilo group of the urethane prepolymer obtained by the above reaction is quaternized with a quaternizing agent or neutralized with an acid in the same manner as described above, 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, the molecular weight can be increased by further conducting a polymerization reaction. As the alcohol solvent used at this time, those which do not contain reactive hydrogen for isocyanate groups (except for alcoholic hydroxyl groups) in the molecule are preferred. Specific examples include ethyl alcohol, n-propyl alcohol, Examples include isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, sec-amyl alcohol, diacetone alcohol and the like. Moreover, the usage-amount of this alcohol solvent is although it does not restrict | limit in particular, Usually, about 3-70 mass% with respect to a urethane prepolymer, Preferably it is 5-60 mass%. The polymerization reaction is preferably radical polymerization, and polymerization initiators used at this time include 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.

  Furthermore, as an aqueous dispersion of a cationic urethane-acrylic resin, as described in JP-A-7-82456, in the presence of a prepolymer having a polymerizable unsaturated bond in the side chain, (D) carbon number May be obtained by reacting a (meth) acrylic acid ester having an aliphatic hydrocarbon group of 1 to 18 with another monomer if necessary. In addition to the above components (A) to (C), the prepolymer having a polymerizable unsaturated bond in the side chain has a polymerizable unsaturated group as described in paragraph “0012” of JP-A-7-82456. The hydroxy compound can be obtained by urethanation reaction in an organic solvent. Examples of hydroxyl compounds containing a polymerizable unsaturated group include β-hydroxyethyl methacrylate (HEMA), β-hydroxyethyl acrylate, γ-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, glycerin monoallyl ether, propylene glycol diglycidyl ether- An acrylic acid adduct etc. are mentioned. A commercially available product may be used as the hydroxyl compound containing a polymerizable unsaturated group, and 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 an aqueous dispersion of a cationic urethane resin, an aqueous dispersion of a cationic urethane-acrylic resin can be obtained by polymerizing the component (D) and other monomers as required. 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 from 1 to 40% by mass, more preferably from 10 to 30% by mass, based on the precoat agent, from the viewpoint of aqueous dispersion and coating film formation. preferable.

[Organic acid having two or more identical functional groups (hereinafter also simply referred to as organic acid)]
The organic acid has an action of aggregating the ink.

The organic acid has two or more identical functional groups. As carbon number of organic acid, it is preferable that it is 2-8 from a water-soluble viewpoint, and it is more preferable that it is 2-6. Also, any pigment, dispersant, or anionic group component in the resin can be used as long as the pKa is low, but since the cohesiveness of the ink is high, the organic acid contained Among them, at least one pKa is preferably 4.5 or less, and more preferably 3.5 or less. The lower limit of pKa is preferably 1 or more. Here, pKa refers to pKa ₁ which is a dissociation index which is a logarithm of the reciprocal of the first acid dissociation constant when the organic acid performs proton release in multiple stages. Moreover, pKa can use the literature value ("Revised 3rd edition Chemical Handbook basic edition II" (The Chemical Society of Japan, Maruzen Co., Ltd., 1984) pp. 342 to 342), and further in an aqueous solution at 25 ° C. The measured value can also be used.

  The functional group in 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 cross-linking agent, and examples thereof include a carboxyl group, a hydroxyl group, an amino group, and a glycidyl group. Can be mentioned. In consideration of water solubility, compatibility with resin, cross-linking reactivity, etc., the functional group is preferably a carboxyl group or a hydroxyl group, and is a carboxyl group in consideration of the action as a flocculant and improvement in water resistance (that is, It is preferable that the organic acid contains two or more carboxyl groups). Further, the same functional group is a carboxyl group (that is, the organic acid contains two or more carboxyl groups), and the crosslinking agent is a crosslinking agent capable of reacting with the carboxyl group, whereby the scratch resistance of the image recording material is obtained. Bending resistance and strength are improved. This is because the cross-linking agent can cross-link both the organic acid and the anionic ink having a carboxyl group, and the resin in the precoat layer that is compatible with the organic acid and the cross-linking agent by the cross-linking becomes the ink layer. This is considered to be because the adhesiveness between the precoat layer and the ink layer is improved.

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

Specific examples of organic acids include organic acids having two or more hydroxyl groups such as gluconic acid (pKa 3.86) and 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 ₁ 1 .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) -Organic acids having two or more carboxyl groups such as tartaric acid (pKa ₁ 2.99) and 1,2,3-propanetricarboxylic acid (pKa ₁ 3.49).

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

  Since the function as a flocculant is high, it is preferable that the organic acid includes an organic acid having two carboxyl groups or an organic acid having three carboxyl groups, and includes an organic acid having at least two carboxyl groups. More preferred.

  Moreover, since pKa is low and it is highly water-soluble, it can be present at a high concentration in the precoat agent, so that 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 that improves the adhesion and folding resistance with the ink layer by using an organic acid having two carboxyl groups and an organic acid having three carboxyl groups are unclear. The organic acid having an organic acid forms a linear cross-linked structure, whereas the organic acid having three carboxyl groups can form a branched cross-linked structure. This is considered to be because the obtained resin has appropriate flexibility. The organic acids having two carboxyl groups may be used alone or in combination of two or more. Moreover, the organic acid which has three carboxyl groups may be used individually by 1 type, or may be used together 2 or more types. In the case where an organic acid having two carboxyl groups and an organic acid having three carboxyl groups are used in combination, the mass ratio in the precoat agent is determined from the viewpoint of cohesiveness and crosslinkability. (Total): Organic acids having three carboxyl groups (total) = 1: 0.01-3 are preferable, and 1: 0.1-1 are more preferable.

  The content of the organic acid in the precoat agent is preferably 1 to 50% by mass and more preferably 1 to 30% by mass with respect to the cationic urethane resin from the viewpoints of cohesiveness and crosslinkability. 5 to 20% by mass is more preferable.

[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—), known polycarbodiimides can be used, and as a compound having two or more carbodiimide groups, in the presence of a carbodiimidization catalyst. High molecular weight polycarbodiimide produced by decarboxylation condensation reaction of diisocyanate 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. As the carbodiimidization catalyst, 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 their 3-phospholene isomers 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 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, and 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.) 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, product names: 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), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (trade name: Denacol (registered trademark) EX-512, manufactured by Nagase ChemteX), sorbitan polyglycidyl ether, Limethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether, etc. .

  Examples of the compound having two or more oxazoline groups include 2,2′-bis (2-oxazoline), 1,2-bis (2-oxazolin-2-yl) ethane, and 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) -Yl) bisoxazoline compounds containing aliphatic or aromatic such as 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-isopropyl One or more polymers of addition polymerizable oxazoline such as propenyl-5-ethyl-2-oxazoline, and the like. As commercially available products, 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.), Epocros (registered trademark) WS-300 (manufactured by Nippon Shokubai Co., Ltd.), Epocros (registered trademark) WS-500 (manufactured by Nippon Shokubai Co., Ltd.), Epocros (registered trademark) WS-700 (manufactured by Nippon Shokubai Co., Ltd.), etc. 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.), Arafix (registered trademark) 255 (manufactured by Arakawa Chemical Industries, Ltd.) or the like can be used.

  The content of the crosslinking agent in the precoat agent is preferably 1 to 100% by mass with respect to the organic acid in consideration of crosslinkability, coating solution stability in the precoat solution, coatability of the coating solution, and the like. It is preferable that it is 10-50 mass%.

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

  In addition to water, the solvent may contain a water-soluble organic solvent for the purpose of improving ejection properties and adjusting 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. 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 mono Ethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol Monoethyl 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, diethylene 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 Examples thereof include tart, 1,2-hexanediol, 1,2-pentanediol, and 1,2-butanediol. The water-soluble organic solvent 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. Examples of other components include foam suppressants described in JP-A No. 2014-094494, cellulose derivatives such as polyvinyl alcohol, gelatin, polyvinyl pyrrolidone, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, and acrylic acid polymers. Various hydrophilic polymers, and curing agents for polymers such as boric acid (salt) that is a curing agent for polyvinyl alcohol; coloring dyes, coloring pigments, ultraviolet absorbers, antioxidants, antifoaming agents, leveling agents, interfaces Activators, preservatives, optical brighteners, viscosity stabilizers, pH adjusters, 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 ink for forming an image by an inkjet method.

  The ink that forms an image by the ink jet method is an anionic ink. By using the anionic ink, the adhesion between the precoat layer and the ink layer is improved by ionic interaction with the cationic urethane resin. Anionic ink contains at least one of an anionic group-containing colorant, 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 used.

  Here, examples of the anionic group include a carboxyl group, a sulfone group, and a phosphate group, and a carboxyl group is preferable.

  Examples of the anionic group-containing colorant include the following. Examples of 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. Examples of the pigment for Solvent Orange 56, magenta or red 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. As a coloring agent for Solvent Green 15 and Black, 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 is exemplified.

  Anionic surfactants include sodium octanoate, sodium decanoate, sodium laurate, sodium myristate, sodium palmitate, sodium stearate, potassium caprate, potassium laurate, potassium myristylate, 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, cumene sulfonate sodium, octylbenzene sulfonate sodium, tetradecene sulfonic acid Thorium, sodium dodecylbenzenesulfonate, perfluorononanoic acid, sodium N-lauroyl sarcosine, sodium cocoyl glutamate, 2-sulfotetradecanoic acid 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 is a resin having a functional group of an acid such as a carboxyl group or a sulfo group in the resin, and the functional group of the acid in the resin is neutralized by an amine. It is. As specific examples, some resins such as acrylic, styrene acrylic, acrylonitrile-acrylic, vinyl acetate acrylic, polyurethane, and polyester are modified with an acid such as a carboxyl group or a sulfo group, and the resin. Can be obtained by neutralization with an amine. Since the amine in the resin is easily evaporated by heating or heating during drying, if the resin having an acid neutralized by the amine attached to the recording medium is heated, only the resin having an acid remains. The amine used for neutralization is preferably ammonia, methylamine, ethylamine, dimethylamine, diethylamine, ethylmethylamine or the like, and particularly preferably ammonia. A water-dispersible or water-soluble resin having an acid neutralized with an amine can be obtained by polymerizing monomers. Examples of such a monomer include polymers of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and acid derivatives of styrene. Although there is no restriction | limiting in particular in the polymerization method, It is preferable to superpose | polymerize 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 with an amine is preferably 1500 or more from the viewpoint of image quality improvement effect, and preferably 100,000 or less from the viewpoint of injection property and viscosity. 80000 is more preferable, and 10,000 or more and 50000 or less are more preferable. Moreover, it is preferable that an acid value is 5 mgKOH / g or more and less than 300 mgKOH / g. The content of the water-dispersible or water-soluble resin having an acid neutralized with an amine is preferably 2 to 15% by mass of the total mass of the ink. A commercially available product may be used as the water-dispersible or water-soluble resin having an acid neutralized with an amine. Examples of commercially available products include Jonkrill (registered trademark) JDX6500 (manufactured by BASF), Jonkrill (registered trademark) 690. Jonkrill (registered trademark) 819, Jonkrill (registered trademark) PDX-6124, and the like.

  Water-dispersible resins include vinyl acetate-based, styrene-butadiene-based, vinyl chloride-based, acrylic-styrene-based, butadiene-based, styrene-based resins having functional groups soluble in water such as sulfonic acid groups and carboxylic acid groups. One selected or a mixture thereof is preferred.

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

  The change of the dispersion state with respect to the pH change of the water-dispersible resin can be adjusted by the content ratio of the constituent component in the water-dispersible resin having a carboxylic acid group such as an acrylate ester, and an anionic property used as a dispersant. 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 the hydrophobic portion, the hydrophobic portion is oriented inside the water-dispersible resin, the hydrophilic portion is efficiently oriented outside, and the effect of increasing the dispersion state with respect to the pH change of the liquid is greater. Aggregation is performed more efficiently.

  Examples of commercially available water-dispersible resins include Jonkrill (registered trademark) 537, 7640 (above, styrene-acrylic resin emulsion, manufactured by BASF), Microgel E-1002, E-5002 (above, styrene-acrylic). Resin emulsion, manufactured by 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 Nippon Zeon Co., Ltd., Julimer (registered trademark) ET-410, FC-30 (above, acrylic resin emulsion, manufactured by Toagosei Co., Ltd.), Aron 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 2 to 40% by mass of the total mass of the ink, more preferably 5 to 30% by mass, and still more preferably 10 to 25% by mass.

  The weight average molecular weight of the water-dispersible resin added to the ink is preferably 5,000 or more in view of the adhesive strength when fused. If it is 5,000 or more, the effect of improving the internal cohesion of the ink aggregate when aggregated and the effect of improving the fixability of the image on the recording medium are sufficient, 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. If the thickness is 10 nm or more, the effect of improving the image quality can be exerted even if the particles are aggregated. If the thickness is 1 μm or less, the ejection property from the ink head and the storage stability can be ensured. Further, the volume average particle size distribution of the polymer particles is not particularly limited, and may be any one having a wide volume average particle size distribution or a monodispersed volume average particle size distribution. Further, two or more kinds of water dispersible resins may be mixed and contained in the ink.

  In preparing the water-based ink, a polymer dispersant or a surfactant can be used in preparing the pigment dispersion. Here, the polymer dispersant preferably has a polymer component having a weight average molecular weight of 5000 or more and 200000 or less. The weight average molecular weight can be measured by gel permeation chromatography (GPC; standard material polystyrene). In view 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 an anionic group-containing monomer (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 1000 to 100,000, more preferably 4000 to 30000. The acid value is preferably 50 to 500, and more preferably 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). Etc.) BASF Jonkrill (registered trademark) series, Seiko PMC high loss series, Toagosei Co., Ltd. ARUFON series, etc. can be used.

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

  As the solvent, in addition to water, a water-soluble organic solvent is included for the purpose of improving ejection properties and adjusting ink physical properties. There are no particular restrictions on the type of 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 mono 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 solvent 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 with respect to the total mass of the ink.

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

  The insoluble pigment is not particularly limited, 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 preferable.

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

  Examples of the magenta or red pigment 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. And CI Pigment Red 222.

  Examples of the pigment for orange or yellow 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. And CI Pigment Yellow 138.

  Examples of the pigment for green or cyan 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. And CI Pigment Green 7.

  In addition to the above, when red, green, blue and intermediate colors are required, the following pigments are preferably used 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, etc. are used.

  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 centrifuge or a filter for the purpose of removing coarse particles from the pigment dispersion.

  Among these, the particle size distribution of the ink produced by the dispersion by the sand mill is sharp and preferable. The material of the beads used for 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 ingredients)
In addition to the above-mentioned components, known surfactants, foam suppressors, pH adjusters, antiseptic and rust preventives, antifungal agents and the like can be added to the ink as necessary.

[Image forming method]
In the second embodiment of the present invention, a precoat layer is formed on the recording medium using the precoat agent of the first embodiment, and an ink is applied to the precoat layer forming surface of the recording medium by an ink jet method to form an image. And an image forming method in which the ink is an anionic ink containing a pigment, water, and a water-soluble organic solvent. In other words, according to the second embodiment of the present invention, a pigment, on a precoat layer forming surface of a recording medium having a precoat layer formed using the precoat agent of the first embodiment on a substrate, by an inkjet method, An image forming method in which an anionic ink containing water and a water-soluble organic solvent is applied to form an image.

  In the said embodiment, it is preferable to form a precoat layer by apply | coating a precoat agent and drying on a base material prior to image formation.

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

  The formation of the precoat layer is not particularly limited, and is an air doctor coater, blade coater, lot coater, knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, 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 and spray coating, and then drying. As a drying method of the precoat agent, any method such as natural drying, heater, hot air dryer or heating roller, infrared heating drying, induction heating drying, microwave drying, vacuum drying, etc. can be preferably used. It is preferable to dry by heating with a hot air dryer or a heating roller. When drying with a heater, it may be used alone as a pre-coating agent drying means, or may also be used as a heating means for printing coated paper described later. Furthermore, after drying at room temperature (25 ° C.), drying may be performed by heat treatment. As heat processing temperature in this case, it is preferable that it is 30-120 degreeC.

  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 precoat layer is completely wet, ink droplets may be disturbed. Therefore, in the case of a continuous and high-speed linear speed inline (the interval between the precoat agent application and the ink application is within several seconds), the drying process may be performed so that the solvent is slightly volatilized after the precoat agent application.

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

There is no restriction | limiting in the frequency | count of apply | coating a precoat agent, You may apply | coat once and may apply | coat in 2 steps or more. The amount of the precoat agent applied to the recording medium is preferably 0.1 to 10 μm as the dry film thickness, more preferably 0.5 to 5 μm, and 0.1 to 10 g / m ² as the coating weight. It is preferable that it is 0.5-5 g / m < ² >.

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

  A method of forming an image by applying ink by an inkjet method can be formed by a conventionally known method. In this case, 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 a 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 greater than the width of the printing range. As a line head type inkjet head, one head may be larger than the width of the printing range, or a combination of a plurality of heads as disclosed in JP 2007-320278 may exceed the width of the printing range. It may be configured. The inkjet head may be an on-demand system or a continuous system. Further, as a discharge method, any discharge method such as a mechanical pressure pulse method (piezo type, etc.), an electric-heat conversion method (for example, thermal ink jet type, bubble jet (registered trademark) type, etc.) 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 2010-247528 A can be used.

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

  In the second embodiment, since the performance is good even when the precoat agent of the first embodiment is used for a non-absorbent recording medium, a non-absorbable recording medium can be used. Further, various non-absorbing plastics and films thereof used for soft packaging are also preferable as non-absorbing recording media. As various plastic films, for example, polyethylene terephthalate (PET) film, stretched polystyrene (OPS) film, unstretched polypropylene (CPP) film, stretched polypropylene (OPP) film, nylon (Ny) film, stretched nylon (ONy) film, A polyvinyl chloride (PVC) film, a polyethylene (PE) film, a triacetyl cellulose (TAC) film, etc. can be mentioned. Examples of other plastics include polycarbonate, acrylic resin, ABS, polyacetal, polyvinyl alcohol (PVA), and rubbers. Further, the present invention can be applied to metals and glass 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 structure of the precoat agent of the first embodiment is effective particularly when an image is formed on a PET film, an OPS film, an OPP film, an ONy film, or a PVC film that can be shrunk by heat.

  The surface of the film may be untreated, but is preferably subjected to various treatments for improving adhesive properties such as corona discharge treatment, ozone treatment, low temperature plasma treatment, flame treatment, glow discharge treatment and the like.

  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 still more preferably 5 to 100 μm. Usually, for example, in the case of soft packaging, it is about 10 to 100 μm as having flexibility, durability and curl resistance.

[Packaging film]
3rd Embodiment of this invention is a film for packaging which has the precoat layer formed using the precoat agent of 1st Embodiment on the base material.

  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-absorbent recording medium) 21, a precoat layer 22, an ink layer 23, an adhesive layer 24, and a laminate film 25 in this order.

  The substrate (ink non-absorbing recording medium) 21, the precoat layer 22, and the ink layer 23 can be formed by the image forming method of the second embodiment described above. The adhesive layer 24 can be formed using a known adhesive such as polyurethane-based or polyethyleneimine-based 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 in the innermost layer and becomes 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 a higher function depending on the contents to be packaged. For example, in retort foods and the like, since the food is packed in a packaging material, it is sterilized by retort (high pressure, 120 ° C or higher for several tens of minutes with hot water), so the packaging material requires higher heat resistance. . In addition, it is necessary not to transmit light or oxygen, and in order to exhibit such a function, it is necessary to laminate a plurality of films having various characteristics. For this reason, the laminate film 15 becomes a laminated body of a multilayer film (and adhesive layer) in a highly functional packaging material. Examples of such highly functional layers include biaxially stretched nylon, biaxially stretched polyethylene terephthalate (biaxially stretched PET), biaxially stretched polypropylene (OPP), and aluminum.

  As a method for laminating a packaging film, known lamination such as dry lamination, non-solvent lamination, extrusion lamination, etc. can be used.

  Specifically, in the dry lamination method, the adhesive is applied to one of the base films by the gravure roll method, and the other base film is stacked and bonded by dry lamination (dry lamination method). In addition, non-solvent lamination is a new film material on the surface immediately after applying the adhesive previously heated to room temperature to 120 ° C on a base film with a roll such as a roll coater heated to room temperature to 120 ° C. A laminated film can be obtained by laminating. In the case of the extrusion laminating method, the organic solvent solution of the adhesive is applied to the base film as an adhesion assistant (anchor coating agent) with a roll such as a gravure roll, and the solvent is dried and cured at room temperature to 140 ° C. After being performed, a laminate film can be obtained by laminating the polymer material melted by the extruder. The polymer material to be melted is preferably a polyolefin resin such as a low density polyethylene resin, a linear low density polyethylene resin, or an ethylene-vinyl acetate copolymer resin.

  When the laminate obtained in this way 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 to be 300 μm or less. Is preferred.

  Since the precoat agent of the first embodiment has little inhibition of curing of the adhesive layer, the laminate 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 the examples, “parts” or “%” may be used, but “parts by mass” or “% by mass” is indicated unless otherwise specified. Unless otherwise specified, each operation is performed at room temperature (25 ° C.).

(Synthesis example of precoat resin)
<Synthesis Example 1>
230 parts by weight of polycarbonate polyol (molecular weight 1000, trade name NIPPOLAN 981, Tosoh Corporation), 19.2 parts by weight of polyethylene glycol (molecular weight 600), 6.0 parts by weight of trimethylolpropane, and N-methyl 59.6 parts by mass of diethanolamine, 260 parts by mass of 4,4′-dicyclohexylmethane diisocyanate, and 260 parts by mass 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. 50.4 parts by mass of dimethyl sulfate was added to this urethane prepolymer 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 uniformly adding 1870 parts by weight of water to the obtained cationic urethane prepolymer and emulsifying it, MEK is recovered to obtain an aqueous cationic urethane resin dispersion (dispersion 1) having a solid content of 30%. Obtained.

<Synthesis Example 2>
Add 826 parts of polyester polyol (molecular weight 2000) consisting 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, and dissolve well with stirring. Subsequently, 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 reacted at 75 ° C. to obtain a prepolymer solution having a terminal isocyanate group having an NCO content of 0.5%. To this urethane prepolymer, 22.4 parts by mass of dimethyl sulfate is added and reacted at 50 to 60 ° C. for 30 to 60 minutes, then the prepolymer is cooled to 40 ° C., 1500 parts of water is added, and a homomixer is used. Emulsification was performed by stirring at high speed. Methyl ethyl ketone was distilled off from the emulsion under reduced pressure by heating to obtain an aqueous cationic urethane resin dispersion (dispersion 2) having a solid content of 340%.

<Synthesis Example 3>
591 parts polyester polyol (molecular weight 2000) composed of neopentyl glycol and ethylene glycol, terephthalic acid, isophthalic acid and adipic acid (mass composition ratio 1: 1: 1: 1: 1), 15 parts trimethylolpropane, methyl ethyl ketone 667 parts were added and sufficiently dissolved by stirring, 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 a terminal isocyanate group having an NCO content of 1.0%. Add 65.9 parts by weight of dimethyl sulfate to this urethane prepolymer, react at 50-60 ° C. for 30-60 minutes, then cool the prepolymer to 40 ° C., add 1857 parts of water, Stir at high speed and emulsify. Methyl ethyl ketone was distilled off from the resin solution while heating under reduced pressure to obtain an aqueous cationic urethane resin dispersion (dispersion 3) having a solid content of 30%.

<Synthesis Example 4>
A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube was charged with acrylic polyol [non-volatile content: 50% by mass of methyl methacrylate, butyl methacrylate, 2-hydroxyethyl acrylate, lauryl acrylate. , Hydroxyl value 17 mg KOH / g, glass transition temperature 19 ° C.] 66 g (acryl polyol solid content 33 g), poly-3-methylpentamethylene isophthalate diol [weight average molecular weight 2,000] 80 g, dimer diol [Croda, Pripol 2033, Number average molecular weight 540] 27 g, N-methyldiethanolamine 3.5 g, dibutyltin dilaurate 0.001 g and methylethylketone 60 g were added and mixed uniformly. Then, 44.4 g of isophorone diisocyanate was added and reacted 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 sulfate was added, the temperature was raised to 80 ° C., and the mixture was stirred at 80 ° C. for 2 hours. Next, after cooling to 30 ° C., 11.4 g of isophoronediamine was added to and mixed with this solution, and 350 g of water was further added and stirred. This mixed solution is transferred to a four-necked flask equipped with a stir bar and a thermometer, reacted at 50 ° C. for 6 hours with stirring, and then degassed while raising the temperature to 60 ° C. over about 2 hours under reduced pressure. Solvent was used to obtain an aqueous cationic urethane-acrylic resin dispersion (dispersion 4).

<Synthesis Example 5>
Add 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 to a reaction vessel equipped with a stirrer, a thermometer, a cooling pipe, and a nitrogen gas introduction pipe, and sufficiently stir. Then, 250.0 parts of isophorone diisocyanate was added and reacted at 75 ° C. for 3 hours to obtain a urethane prepolymer having an isocyanate group at the end. Next, 6.3 parts of 2-hydroxyethyl acrylate was added, the reaction was further performed at 85 ° C. for 2 hours, 190 parts of stearyl methacrylate was further added, and a urethane prepolymer having a double bond in a part of the molecule was added. Obtained. The urethane prepolymer was cooled to 70 ° C., stopped stirring, and allowed to stand. 69 parts by mass of dimethyl sulfuric acid is added to this urethane prepolymer and reacted at 50-60 ° C. for 30-60 minutes, then the prepolymer is cooled to 40 ° C., then 2410 parts of water, 100.0 parts of isopropyl alcohol After adding an aqueous solution consisting of 57.5 parts of isophoronediamine, stirring was started again, and the mixture was reacted at 50 ° C. for 3 hours. This resin solution was heated under reduced pressure to distill off methyl ethyl ketone, and an aqueous dispersion of polyurethane resin. Got. Thereafter, the polyurethane resin aqueous dispersion was heated to 75 ° C., and a polymerization initiator prepared by dissolving 0.2 part of dimethyl-2,2′-azobisisobutyrate in 40 parts of isopropyl alcohol over 30 minutes. In addition, the radical polymerization reaction was started, and further maintained at 75 ° C. for 2 hours to complete the radical polymerization reaction, thereby obtaining an aqueous cationic urethane-acrylic resin dispersion (dispersion 5).

<Synthesis Example 6>
A raw material having the following composition was charged into a 2 liter four-necked flask equipped with a reflux condenser, a thermometer and a stirrer, and the temperature was raised to 90 ° C. while stirring in a nitrogen atmosphere. went.

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

  Then, it cooled to 40 degreeC and the prepolymer which has a terminal isocyanate group was obtained. Next, 28.2 g of dimethyl sulfate 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 acid dihydrazide was added to the reaction system, and stirring was continued at 50 ° C. for 1 hour, and then MEK was distilled off under reduced pressure to obtain hydrazide-terminated aqueous urethane.

  Next, 530 g of the above 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 30 minutes from room temperature to 80 ° C. The temperature was raised to. 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.

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

<Synthesis Example 7>
In a 1 L three-necked flask container, 400 parts by weight of ion exchange water, 5 parts by weight of dimethylaminoethylmethyl chloride chloride, 70 parts by weight of methyl methacrylate, 15 parts by weight of butyl acrylate, 10 parts by weight of 2-ethylhexyl acrylate The mixture was supplied and heated to 70 ° C. while stirring at a stirring rotational speed of 250 rpm. Subsequently, 0.5 part by weight of 2,2′-azobis (2-amidinopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd .; V-50) was supplied, stirred for 2 hours, and then 80 ° C. The emulsion polymerization was carried out with continued 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
After sequentially adding, mixing and dissolving malonic acid and a carbodiimide-based crosslinking agent (trade name: Carbodilite SV-02 (manufactured by Nisshinbo Chemical Co., Ltd.)) to the cationic urethane resin dispersion (dispersion 1), this solution was treated with # 3500. The mixture was filtered with a mesh metal filter and deaerated with a hollow fiber membrane to prepare a precoat 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 that it might become 20 mass% with respect to resin solid content. The crosslinking agent was added so that it might become 10 mass% with respect to resin solid content.

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

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

  In Example 8, malonic acid and citric acid were 1: 1 (mass ratio), and the total organic acid was added so as to be 20 mass% with respect to the resin solid content.

  Furthermore, in Example 9, malonic acid, malic acid, and 1,2,3-propanetricarboxylic acid are 1: 1: 1 (mass ratio), and the total organic acid is 20% by mass with respect to the resin solid content. Was added as follows.

<< Preparation of pigment dispersion >>
(Preparation of magenta pigment dispersion)
As a pigment dispersant, 3 parts by mass of Jonkrill (registered trademark) 678 (manufactured by BASF), 1.3 parts by mass of dimethylaminoethanol, and 80.7 parts by mass of ion-exchanged water were mixed and then heated and stirred. To this mixture, C.I. I. After adding 15 parts by mass of Pigment Red 122 and premixing, the mixture was dispersed using a sand grinder filled with 50% by volume of 0.5 mm zirconia beads to obtain a magenta pigment dispersion having a pigment solid content of 15%. .

(Preparation of cyan pigment dispersion)
As a pigment dispersant, 3 parts by mass of Jonkrill (registered trademark) 678 (manufactured by BASF), 1.3 parts by mass of dimethylaminoethanol, and 80.7 parts by mass of ion-exchanged water were mixed, followed by heating and stirring. C.I. I. 15 parts by weight of Pigment Blue 15: 3 was added and premixed, and then dispersed using a sand grinder filled with 50% by volume of 0.5 mm zirconia beads 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 in the following addition amount and sufficiently stirred, and then 33 parts by mass of the magenta pigment dispersion was added with stirring. After sufficiently stirring, the mixture was filtered through a # 3500 mesh metal filter and deaerated with a hollow fiber membrane to prepare ink 1-M. Jonkrill (registered trademark) JDX6500 is a water-soluble acrylic resin manufactured by BASF, which has been 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 Joncrill JDX (registered trademark) 6500 (manufactured by BASF) 7 parts by mass Surfactant: Orphine (registered trademark) E1010 (acetylene glycol surfactant, manufactured by Nisshin Chemical Co., Ltd.) 0.5 Part 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 >>
A single-sided corona-treated biaxially stretched polypropylene film (FOS, manufactured by Futamura Chemical Co., Ltd., 60 μm) and a single-sided corona-treated biaxially stretched polyethylene terephthalate film (FE2001, 50 μm, manufactured by Futamura Chemical Co., Ltd.) are used as recording media for printing. It was. A wire bar was used as a recording medium for printing, and the precoat agent prepared in each of the above Examples and Comparative Examples was applied. The application conditions were set so that the coating film thickness of the precoat agent after drying was in the range of 1 to 2 μm, and the precoat agent was air-dried at room temperature after application, thereby producing recording media for evaluation of each example and comparative example. .

<Formation of printed image>
As shown in FIG. 3, the inkjet recording apparatus has 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 recording medium to be transported ( A line head type inkjet recording apparatus was used. The ink set A (ink 1-M, ink 1-C) was ejected from the head unit 11 while the recording medium P was being conveyed to the head unit 11 at a conveyance speed of 300 mm / s. As shown in FIG. 4, each of the heads 111 to 114 constituting the head unit 11 is configured such that two nozzles of 360 dpi are arranged alternately in the 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 was adopted. The ink 1-M constituting the ink set A from the head 112 and the ink 1-C constituting the ink set A from the head 111 are ejected at an ink droplet amount of 16 pl at a printing resolution of 720 dpi × 720 dpi. Each color patch image with a printing rate of ˜100% was printed. Next, the recording medium was heated to a surface temperature of 80 ° C. and dried to obtain a recording medium on which an image was formed.

  About each created said image, the presence or absence of generation | occurrence | production of the mottling (liquid side of an ink) was observed visually, and the mottling tolerance was evaluated according to the following reference | standard.

A: Generation of mottling and connection of dots are not observed in a patch image with a printing rate of 0 to 100%. B: Generation of mottling is not observed in a solid image with a high printing rate, but a medium density region. C: The occurrence of weak mottling is recognized. C: The occurrence of clear mottling is recognized even in a solid image with a high printing rate.

[Evaluation of bleeding resistance]
A cyan solid image with a printing rate of 100% was printed on a magenta solid image with a printing rate of 100%, the presence or absence of bleeding (image bleeding) was visually observed, and bleeding resistance was evaluated according to the following criteria.

A: Bleeding of less than 0.02 mm of cyan image is observed B: Bleeding of 0.02 mm or more and less than 0.05 mm of cyan image is observed C: Bleeding of 0.05 mm or more of cyan image is observed

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

2. Precoat layer resistance or image resistance [Precoat agent substrate adhesion]
Single-sided corona-treated biaxially stretched polypropylene film (Futamura Chemical FOS, 60 μm, OPP), single-sided corona-treated biaxially stretched polyethylene terephthalate film (Futamura Chemical FE2001, 50 μm, PET) and single-sided corona-treated biaxially stretched nylon film ( Toyobo N1102, 25 μm, ONy) was coated 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 precoat coating 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 eye tape method of JIS K5400. A 100 mm square of 1 mm square was formed on the coated surface, an adhesive tape was attached, and a tape peeling test was performed. As the adhesive tape, an adhesive tape (TQC ISO adhesive tape) having an adhesion strength of 10 ± 1 N per 25 mm width was used. 5 (100% remaining), 4 (80% or more, less than 100% remaining), 3 (60% or more, less than 80% remaining), 2 (20% or more) A five-step judgment was made: 1 (less than 60% remaining) and 1 (less than 20% remaining).

  In addition, in evaluation of the base-material adhesiveness of a precoat agent, it is preferable that it is 4 or more.

[Blocking resistance of precoat agent]
The above-prepared inkjet recording medium having an OPP film as a base material is placed on each coating film surface, and the OPP film is placed on top of each other and left at 50 ° C. for 15 hours under a load of 0.5 MPa. They were peeled apart and the blocking resistance was determined according to the following criteria.

○: Films peel off without resistance Δ: There is resistance when peeling films, but they cannot be taken on stacked films ×: There is resistance when peeling films, and there is a film with ink overlaid Take part.

[Evaluation of scratching of drawn images]
With respect to an image having a printing rate of 100% created as described above, after image formation and after one day under normal temperature and humidity conditions, the surface of each image was applied 10 to 30 times by applying a 9N load to a cotton cloth (Kanakin No. 3). Rubbing, ink peeling, and ink transfer to the cotton cloth were visually observed, and scratch resistance was evaluated according to the following criteria.

◎: Ink peeled off even after being rubbed 30 times, and no ink transfer to the cotton cloth was observed. ○: After ink was rubbed 30 times, ink peeling or slight ink transfer to the cotton cloth was observed. △: Ink after rubbed 30 times. Peeling or ink transfer to cotton cloth was observed x: Ink peeling or ink transfer to cotton cloth was recognized before rubbing 30 times.

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

◎: Floating, peeling, and cracking are not generated by bending (winding) ○: Weak floating, peeling, and cracking are observed after bending (winding) 10 times or more △: 2 times or more 10 times When it is bent (wrapped) less, the occurrence of weak floating, peeling, and cracking is observed. ×: When it is bent (winding) once, it clearly floats, peels, and cracks.

[Lamination strength]
Laminate adhesive (Takelac (registered trademark) A-525S (main agent) / Takenate (registered trademark) A-50 (curing agent)) = 9/1 (mass ratio) on a corona-treated surface of a PET film with a wire bar, Mitsui Chemicals Co., Ltd.) was applied to a dry film thickness of 3 μm, dried at 70 ° C. for 3 minutes, and then a precoat and ink jet print formed on the PET created in the section of print image formation for evaluation of mottling resistance with a laminator 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 pressurization time of 90 seconds. After lamination, the laminate was stored at 40 ° C. for 3 days, and then a peel test was performed to evaluate the laminate strength according to the following criteria.

  Hold the base material of the non-adhesive part at the end of the laminate film with a jig and pull it with the other hand. Yes, if there is no peeling, △ if there is some peeling, easy peeling Was marked with 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 layer formed using the precoat agent of Examples 1 to 12 has high adhesion to the base material and the ink layer, and the durability of the recording medium and the image recording body on which the precoat agent is formed. It was expensive. The image quality of the obtained image was also good.

  In particular, the precoat agents of Examples 4 to 6 containing a water-based urethane-acrylic resin dispersion had good adhesion to any substrate, and also improved image folding resistance. Furthermore, when the pre-coating agents of Examples 8 and 9 in which an organic acid having two carboxyl groups and an organic acid having three carboxyl groups are used in combination, the abrasion resistance of images on various substrates is high. It was highly durable.

  On the other hand, the precoat agent of Comparative Example 1 containing an acrylic resin has low image quality, low adhesion to OPP, and low in any of the items of image scratch resistance, bending resistance and laminate strength. It was. Further, the precoat agent of Comparative Example 2 in which no cross-linking agent is present has low adhesion to OPP, and is low in any of the items of blocking resistance of the precoat agent, scratch resistance of the image, bending resistance and laminate strength. became. Furthermore, the precoat agent of Comparative Example 3 using lactic acid having no two or more identical functional groups was low in any of the items of image scratch resistance, bending resistance, and laminate strength.

  As mentioned above, it turns out that the precoat agent of Examples 1-12 is a precoat agent with which the durability of the formed coating film and the image formed after that is high, and also the image quality of the formed image becomes favorable. .

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

Claims (8)

A precoat agent used to form a precoat layer that receives ink for forming an image by an inkjet method,
A precoat agent comprising water, a cationic resin having a polyurethane structure, two or more organic acids having the same functional group, and a crosslinking agent capable of reacting with the functional group.   The precoat agent according to claim 1, wherein the cationic resin includes a structure derived from a (meth) acrylic acid ester having an aliphatic hydrocarbon group having 1 to 18 carbon atoms.   The precoat agent according to claim 1 or 2, comprising an organic acid having two carboxyl groups or an organic acid having three carboxyl groups.   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 described in 1.   The precoat agent according to claim 3 or 4, comprising an organic acid having two carboxyl groups and an organic acid having three carboxyl groups.   The packaging film which has the precoat layer formed using the precoat agent of any one of Claims 1-5 on a base material.   A pigment, water, and water-solubility are formed on the surface of the recording medium having a precoat layer formed using the precoat agent according to any one of claims 1 to 5 by an inkjet method on a substrate. An image forming method for forming an image by applying an anionic ink containing a conductive 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 substrate prior to the image formation.