JP6824904B2 - Print media, manufacturing methods of print media and printed matter - Google Patents

Description

The present invention relates to a print medium, a method for producing a print medium, and a printed matter. Specifically, the present invention uses an ultraviolet curable ink because it has few surface streaks and is excellent in ink adhesion after being stored in a high temperature and high humidity environment when general printing is performed using an ultraviolet curable ink. The present invention relates to a printing medium having excellent print quality and water-resistant adhesion after being stored in a high-temperature and high-humidity environment in the case of performing inkjet recording. The present invention also relates to a method for producing the print medium and a printed matter using the print medium.

In the printing field, various data may be recorded using ink on a printing medium to create printed matter such as product quotations, price invoices, and price tags.
Conventionally, standard data such as background patterns and ruled line frames are recorded by general printing (plate printing) such as offset printing and sticker printing using oxidation polymerization type ink and ultraviolet curable ink on the same printing medium. Fine characters such as product names and prices and variable data such as bar codes were recorded by information recording methods (offset printing) such as thermal transfer recording method and electrophotographic recording method.
Therefore, the print medium is required to have excellent printability in both general printing and information recording methods. For example, in addition to printability for multicolor printing in normal printing, print media used in the field of business form printing is also given printability for recording variable data such as product names and barcodes in an information recording method. It is preferable to be printed.
As a method for improving the printability of the print medium, it is known to devise the composition of the resin layer provided on the surface of the support (see Patent Documents 1 to 4).

JP-A-2002-113959 WO2014 / 087670 Japanese Unexamined Patent Publication No. 2011-116125 Japanese Unexamined Patent Publication No. 2013-199574

In a printing medium in which a resin layer is provided on the surface of such a support, it is required to reduce surface streaks such as coating streaks on the surface of the printing medium.

Further, regarding the improvement of printability of the print medium, Patent Document 1 states that the print medium provided with the resin layer containing the nitrogen-containing polymer compound on the surface of the support is left in a high temperature and high humidity environment for a long time. It has been pointed out that the moisture absorption of the resin layer, which is the printing surface of the ink, becomes high, and the ink is easily peeled off when the printed matter is peeled off with an adhesive tape in a printed matter placed in a high temperature and high humidity environment for a long time. As described above, in general printing, high ink adhesion to the printing medium after storage in a high temperature and high humidity environment has been required.

On the other hand, in the information recording method, the printability required depends on the recording method. In recent years, high-definition, high-speed printing, and low-priced inkjet printers, which are one of the recording devices used in information recording methods, have been progressing. Therefore, in recent years, there has been an increasing demand for recording variable data by the inkjet recording method among the information recording methods. In such an inkjet recording method, high print quality in that there is little ink bleeding and water resistance and adhesion when the printed matter after printing is exposed to moisture are required. In recent years, a method for improving the water resistance and adhesion of an inkjet recording method by using an ultraviolet curable ink instead of a water-based ink has been proposed. However, after storage in a high temperature and high humidity environment, the moisture absorption of the resin layer on the printing surface becomes high as described above, so when UV curable ink is used, water resistance adhesion after storage in a high temperature and high humidity environment There was a need to further improve the properties and ink bleeding.

The problem to be solved by the present invention is that there are few surface streaks, and when general printing using an ultraviolet curable ink is performed, the ink adhesion after storage in a high temperature and high humidity environment is excellent, and an ultraviolet curable ink can be obtained. It is an object of the present invention to provide a printing medium having excellent print quality and water-resistant adhesion after being stored in a high-temperature and high-humidity environment when the inkjet recording used is performed.

The present inventors have diligently studied a print medium that can solve the above problems. As a result, a resin layer containing a cationic polyurethane resin (a), an ethyleneimine-based resin (b), and an acidic pH adjuster (c) is provided on at least one surface of a support containing a thermoplastic resin as a main component. We have found that we can provide a print medium that can solve the above problems, and have completed the present invention.

It was not known that the above problems could be solved by the above configuration. Further, a print medium capable of solving the above problems has not been known conventionally. It was a remarkable effect that those skilled in the art could not predict that the above problems could be solved by the above configuration. In the following, each document will be described in comparison with the constitution of the present invention.
For example, Patent Document 1 describes a print medium suitable for a thermal transfer recording method among information recording methods. Specifically, an image receiving film for printing and thermal transfer is described in which a coating layer composed of the following components (A) and (B) is provided on the surface of a support made of a thermoplastic resin film.
(A) An olefin copolymer (a) to which an unsaturated carboxylic acid or an anhydride thereof is bonded is obtained from a nonionic surfactant, a nonionic water-soluble polymer, a cationic surfactant, and a cationic water-soluble polymer. An aqueous dispersion dispersed in water using at least one selected from the group (b) as a dispersant (b), wherein the weight ratio of (a) / (b) per solid content is 100/1 to 100. A resin aqueous dispersion having an average particle size of 5 μm or less, which is / 30.
(B) An ethyleneimine adduct of a specific polyimine polymer or polyamine polyamide.
Patent Document 1 describes a thermal transfer film, particularly a molten thermal transfer film, which has excellent ink transferability, adhesion and water resistance in a high temperature and high humidity environment in a thermal transfer type print and can obtain a clear image. It is described that a thermoplastic resin film having excellent ink transferability, adhesion, and water resistance is provided in various printing methods.
However, when the present inventors performed inkjet recording using an ultraviolet curable ink using the image receiving film for thermal transfer using the cationic polyolefin resin described in Patent Document 1, ink bleeding occurred in the printed matter and printing was performed. It was found that there is a problem that the readability of fine characters and bar codes is poor due to the poor quality.

Patent Document 2 describes a composition for a printing medium containing (a) a cationic urethane resin, (b) an olefin copolymer emulsion, and (c) an ethyleneimine resin. Further, Patent Document 2 describes a printing medium in which a coating layer containing the above composition for a printing medium is provided on at least one surface of the support.
Patent Document 2 describes that such a configuration provides a print medium having excellent printability in both a plate printing method and a plateless printing method.
However, when the present inventors examined the physical characteristics of the printing medium containing no acidic pH regulator (c) described in Patent Document 2 before printing, there was a problem that the surface of the printing medium had many surface streaks such as coating streaks. It turned out that there was a point.

Patent Document 3 describes a recording medium having an ink receiving layer containing an alumina hydrate and a binder on a support, and the surface of the ink receiving layer is a portion formed by a plurality of films containing cationic polyurethane. A recording medium is described in which the ink receiving layer is coated with a film, the average major axis of the plurality of films is 0.03 μm or more and less than 1.00 μm, and the coverage of the surface of the ink receiving layer by the partial film is 10% or more and less than 70%. ing.
According to Patent Document 3, it is described that such a configuration provides a recording medium having excellent surface glossiness, scratch resistance and color development while maintaining excellent ink absorbency of the ink receiving layer. There is.
However, the recording medium described in Patent Document 3 is a dedicated printing medium specialized for an inkjet recording method using a water-based ink, which needs to improve the ink absorbency of the ink receiving layer. When performing inkjet recording using an ultraviolet curable ink, the ink absorbency of the ink receiving layer is not so important. The configuration in which the surface of the ink receiving layer described in Patent Document 3 is covered with a partial film does not contribute to the improvement of printability when the ultraviolet curable ink is used.

Patent Document 4 describes a polyurethane resin (A) containing a compound obtained by quaternizing a tertiary amino group of a chain extender having a tertiary amino group in the molecule and a polycarbonate polyol as constituent units, and a carbon-carbon double. A laminate having a coating layer on at least one side after applying a coating solution containing a polyurethane resin (B) having a bond, a cationic polymer antistatic agent (C), and an oxazoline compound (D). A polyester film is described.
According to Patent Document 4, it is described that such a configuration provides a polyester film having a coating layer having both antistatic properties and easy adhesiveness at a high level.
However, the recording medium containing neither the acidic pH regulator (c) nor the ethyleneimine-based resin (b) described in Patent Document 4 has many surface streaks such as coating streaks on the surface of the printing medium, and UV curable ink is used. It was also found that there is a problem that there are many surface streaks such as coating streaks on the surface of the print medium when the conventional inkjet recording is performed.

The present invention, which is a specific means for solving the above problems, and preferred embodiments of the present invention are as follows.
[1] On the surface of at least one of the supports containing a thermoplastic resin as a main component,
A printing medium having a resin layer containing a cationic polyurethane resin (a), an ethyleneimine-based resin (b), and an acidic pH adjuster (c).
[2] Printing medium according to [1], the resin layer is preferably a 0.01g ^{/ m 2} ~5g ^/ m 2 as solids.
[3] The printing medium according to [1] or [2] is preferably in a solid state when the acidic pH adjuster (c) is at 20 ° C. and 1 atm.
[4] The printing medium according to any one of [1] to [3] may contain an acid having a pKa of −0.2 to 6.8 as a free acid of the acidic pH adjuster (c). preferable.
[5] In the printing medium according to any one of [1] to [4], the acidic pH adjuster (c) is a monovalent aliphatic carboxylic acid having 9 to 18 carbon atoms and 3 to 12 carbon atoms. It is preferable to contain one or more acids selected from the divalent or higher valent aliphatic carboxylic acid, aromatic carboxylic acid, boric acid and phosphoric acid.
[6] The printing medium according to any one of [1] to [5] is preferably a coating layer in which the resin layer is formed from a coating liquid.
[7] On the surface of at least one of the supports containing the thermoplastic resin as a main component,
A method for producing a printing medium, which comprises a step of forming a resin layer by applying a coating liquid containing a cationic polyurethane resin (a), an ethyleneimine resin (b) and an acidic pH adjuster (c).
[8] In the method for producing a printing medium according to [7], the pH of the coating liquid is preferably 1.0 to 7.4.
[9] A printed matter having an ultraviolet curable ink on the resin layer of the printing medium according to any one of [1] to [6].

According to the present invention, there are few surface streaks, excellent ink adhesion after storage in a high temperature and high humidity environment when general printing using an ultraviolet curable ink is performed, and inkjet recording using an ultraviolet curable ink. It is possible to provide a printing medium having excellent print quality and water-resistant adhesion after being stored in a high-temperature and high-humidity environment.

The present invention will be described in detail below. The description of the constituent elements described below may be based on typical embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. The numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

[Print medium]
The printing medium of the present invention is a resin containing a cationic polyurethane resin (a), an ethyleneimine resin (b) and an acidic pH adjuster (c) on at least one surface of a support containing a thermoplastic resin as a main component. It is a print medium having layers.
With such a configuration, the printing medium of the present invention has few surface streaks, and when general printing using an ultraviolet curable ink is performed, it has excellent ink adhesion after being stored in a high temperature and high humidity environment, and is ultraviolet curable. Excellent print quality and water-resistant adhesion after storage in a high-temperature and high-humidity environment when performing inkjet recording using mold ink. It is said that the inclusion of the cationic polyurethane resin (a) in the resin layer contributes to the improvement of print quality and water resistance after storage in a high temperature and high humidity environment when performing inkjet recording using an ultraviolet curable ink. is expected. It is expected that the inclusion of the ethyleneimine resin (b) in the resin layer will contribute to the improvement of ink adhesion after storage in a high temperature and high humidity environment when general printing using ultraviolet curable ink is performed. .. It is expected that the inclusion of the acidic pH adjuster (c) in the resin layer contributes to the improvement of surface streaks after storage in a high temperature and high humidity environment.
The printing medium of the present invention is a printing medium suitable for general printing methods such as offset printing and sticker printing using ultraviolet curable ink, and inkjet recording using ultraviolet curable ink. The print medium of the present invention is preferably adapted to information recording methods such as a thermal transfer recording method, an electrophotographic method, and an inkjet recording method.
Moreover, it is preferable that the printing medium is printing paper. However, the printing medium may be other than printing paper (for example, posters, calendars, maps, tags, labels, stickers, etc.).
The details of the preferred embodiment of the print medium of the present invention will be described below.

<Support>
The support contains a thermoplastic resin as a main component. When the support contains a thermoplastic resin as a main component, the water resistance and adhesion of the printed matter can be improved. The main component of the support is a component contained in an amount of 50% by mass or more of the total mass of the support. The support preferably contains 70% by mass or more of the thermoplastic resin, and more preferably 80% by mass or more.

(Thermoplastic resin)
The type of thermoplastic resin used for the support is not particularly limited. For example, ethylene resins such as high density polyethylene and medium density polyethylene, propylene resins, polyolefin resins such as polymethyl-1-pentene and ethylene-cyclic olefin copolymers; polyamides such as nylon-6 and nylon-6,6. Resins: Thermoplastic polyester resins such as polyethylene terephthalate and its copolymers, polyethylene naphthalate, polybutylene terephthalate, polybutylene succinate and aliphatic polyesters such as polylactic acid; polycarbonate, atactic polystyrene, syndiotactic polystyrene, etc. Thermoplastic resin can be mentioned. Among them, it is preferable to use a polyolefin resin or a polyester resin, and it is more preferable to use a polyolefin resin from the viewpoints of water adhesion resistance, chemical resistance, cost and the like.

Among the polyolefin-based resins, it is preferable to use a propylene-based resin because it is easy to impart appropriate rigidity (stiffness) to the printing medium. As the propylene-based resin, a propylene homopolymer or a copolymer of propylene as a main component and an α-olefin such as ethylene, 1-butene, 1-hexene, 1-hexene, 4-methyl-1-pentene, etc. Can be used. The stereoregularity is not particularly limited, and isotactic or syndiotactic and those exhibiting various degrees of stereoregularity can be used. Further, the copolymer may be a binary system or a plural system of ternary system or more, and may be a random copolymer or a block copolymer. As the propylene-based resin, it is preferable to use a resin having a melting point lower than that of the propylene homopolymer in an amount of 2 to 25% by mass. As such a resin having a low melting point, high-density or low-density polyethylene can be exemplified.

As the thermoplastic resin used for the support, one type may be selected from the above-mentioned thermoplastic resins and used alone, or two or more types may be selected and used in combination. Inorganic fine powder, organic filler, thermal stabilizer (antioxidant), light stabilizer, dispersant, lubricant and the like can be added to the thermoplastic resin used for the support, if necessary.

(Inorganic fine powder)
The support may contain inorganic fine powder. By containing the inorganic fine powder in the support, the support can be whitened and opaque, and further concealment can be imparted, facilitating the visibility of printing as a printing medium, and strike-through of printing (from the back side). It is possible to prevent (see through).
Specific examples of the inorganic fine powder include heavy calcium carbonate, light calcium carbonate, calcined clay, talc, diatomaceous earth, titanium oxide, barium sulfate, alumina, silica, zinc oxide, magnesium oxide, diatomaceous earth and the like. Further, a surface-treated product of the inorganic fine powder with various surface-treating agents can also be exemplified. Among them, it is preferable to use heavy calcium carbonate, precipitated calcium carbonate and their surface-treated products, clay, and diatomaceous earth because they are inexpensive and have good pore-forming property at the time of stretching.

Examples of the surface treatment agent for the inorganic fine powder include resin acids, fatty acids, organic acids, sulfate ester-type anionic surfactants, sulfonic acid-type anionic surfactants, petroleum resin acids, and sodium, potassium, and ammonium thereof. Salts or these fatty acid esters, resin acid esters, waxes, paraffins, etc. are preferable, and nonionic surfactants, diene-based polymers, titanate-based coupling agents, silane-based coupling agents, phosphoric acid-based coupling agents, non-salts are preferable. Active inorganic oxides and the like are also preferred. Examples of the sulfate ester-type anionic surfactant include long-chain alcohol sulfate esters, polyoxyethylene alkyl ether sulfate esters, sulfated oils, and salts thereof such as sodium and potassium, and examples thereof include sulfonic acid-type anionic surfactants. Examples of the activator include alkylbenzene sulfonic acid, alkylnaphthalene sulfonic acid, paraffin sulfonic acid, α-olefin sulfonic acid, alkylsulfosuccinic acid and the like, or salts thereof such as sodium and potassium.

Examples of the fatty acids include caproic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, hebenic acid, oleic acid, linoleic acid, linolenic acid, and eleostear. Examples include acid. Examples of the organic acid include maleic acid and sorbic acid. Examples of the diene polymer include polybutadiene and isoprene. Examples of the nonionic surfactant include polyethylene glycol ester type surfactants. Examples of the inert inorganic oxide include alumina and silica. These surface treatment agents can be used alone or in combination of two or more. Examples of the surface treatment method for the inorganic fine powder using these surface treatment agents include JP-A-5-43815, JP-A-5-139728, JP-A-7-300568, and JP-A-10-176079. JP, JP-A-11-256144, JP-A-11-349846, JP-A-2001-158863, JP-A-2002-220547, JP-A-2002-363443, JP-A-2010-66512, etc. The method described in can be used.

(Organic filler)
The support may include an organic filler. Even if the support contains an organic filler, the support can be whitened and opaque, and printing can be easily visually recognized as a printing medium.
As a specific example of the organic filler, a resin having its own melting point or glass transition point higher than the melting point or glass transition point of the main thermoplastic resin constituting the support (for example, 120 to 300 ° C.) can be preferably used. For example, when a propylene resin is used as the main thermoplastic resin constituting the support, the organic fillers include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyamide, polycarbonate, polystyrene, cyclic olefin homopolymer, and ethylene-. Examples thereof include cyclic olefin copolymers, polyethylene sulfides, polyimides, polymethacrylates, polyethyl ether ketones, polyphenylene sulfides, and melamine resins. Since these have a higher melting point or glass transition temperature than the propylene-based resin, which is the main thermoplastic resin constituting the support, and are incompatible with the propylene-based resin, they have a porosity-forming property during stretching. Is preferable because it is good.

For the support, one type may be selected from the inorganic fine powder or the organic filler and used alone, or two or more types may be selected and used in combination. When two or more kinds are used in combination, the inorganic fine powder and the organic filler may be mixed and used.
When an inorganic fine powder or an organic filler is used for the support, the support preferably contains the above-mentioned fine powder or filler in a total amount of 5 to 75% by mass, more preferably 8 to 65% by mass, and 10 to 10% by mass. It is more preferably contained in an amount of 55% by mass. When these contents in the support are 5% by mass or more, it is easy to obtain the desired pores, and it tends to be easy to achieve opacity of the print medium. On the contrary, when it is 75% by mass or less, the strength of the support tends to be difficult to decrease.

The average particle size of the inorganic fine powder used and the average dispersed particle size of the organic filler are preferably in the range of 0.01 to 15 μm, more preferably in the range of 0.05 to 1.5 μm, and 0. It is more preferably in the range of 1 to 1.3 μm.
When a fine powder or filler having an average particle size or an average dispersed particle size of 0.05 μm or more is used, pores are easily obtained by stretch molding, and opacity of the print medium tends to be easily achieved. Further, if a fine powder or filler having an average particle diameter or an average dispersed particle diameter of 15 μm or less is used, the strength of the support tends to be increased.
The average particle size of the inorganic fine powder used and the average dispersed particle size of the organic filler are cumulatively measured by a particle measuring device, for example, a laser diffraction type particle measuring device "Microtrack" (manufactured by Microtrack Bell Co., Ltd., trade name). Observation of particle size corresponding to 50% (cumulative 50% particle size) and primary particle size with a scanning electron microscope (in the present invention, the average value of 100 particles was taken as the average particle size), conversion from specific surface area (the present invention). Then, the specific surface area was measured using the powder specific surface area measuring device SS-100 manufactured by Shimadzu Corporation).

(Other additives)
When adding a heat stabilizer, usually use a heat stabilizer such as a steric hindrance phenolic antioxidant, a phosphorus-based antioxidant, or an amine-based antioxidant within the range of 0.001 to 1% by mass. Can be done. When a light stabilizer is added, a steric hindrance amine-based light stabilizer, a benzotriazole-based light stabilizer, a benzophenone-based light stabilizer, a sulfur-based light stabilizer, etc. are usually used within the range of 0.001 to 1% by mass. can do. The dispersant is used, for example, for the purpose of dispersing inorganic fine powder. Specifically, a silane coupling agent, higher fatty acids such as oleic acid and stearic acid, metal soap, polyacrylic acid, polymethacrylic acid and salts thereof are usually used in the range of 0.01 to 4% by mass. be able to.

(Molding method of support)
The molding method of the support is not particularly limited. The support can be appropriately selected and molded from various known methods. For example, cast molding, calendar molding, rolling molding, inflation molding, thermoplastic extruding a molten thermoplastic resin composition into a sheet using a single-layer or multi-layer T-die or I-die connected to a screw-type extruder. A mixture of a resin and an organic solvent or oil can be cast-molded or calendar-molded and then molded by a method of removing the solvent or oil. Further, the molten thermoplastic resin composition can be extruded and laminated on a base material of paper or a thermoplastic resin film.
The support (particularly the thermoplastic resin film layer on the surface of the support) may be unstretched or stretched. Stretching can be performed by any of the various commonly used methods. Specific examples include longitudinal stretching using the difference in peripheral speed of the roll group, transverse stretching using a tenter oven, rolling, a combination of a tenter oven and a linear motor, or simultaneous biaxial stretching using a combination of a tenter and a pantograph. Can be done.

In the case of a non-crystalline resin, the temperature of the stretching is equal to or higher than the glass transition temperature of the thermoplastic resin used, and in the case of a crystalline resin, the temperature is equal to or higher than the glass transition temperature of the non-crystalline portion to lower than the melting point of the crystalline portion. It can be carried out within a known temperature range suitable for the resin. Specifically, the stretching temperature is preferably 2 to 60 ° C. lower than the melting point of the thermoplastic resin used, and when the resin is a propylene homopolymer (melting point 155 to 167 ° C.), 152 to 164 ° C., high density polyethylene (high density polyethylene). It is preferably set to 110 to 120 ° C. when the melting point is 121 to 134 ° C., and 104 to 115 ° C. when the polyethylene terephthalate (melting point is 246 to 252 ° C.). The stretching speed is preferably 20 to 350 m / min.

The draw ratio at the time of the above stretching is not particularly limited, and is appropriately determined in consideration of the characteristics of the thermoplastic resin used. For example, when a propylene homopolymer or a copolymer thereof is used as the thermoplastic resin, it is about 1.2 to 12 times, preferably 2 to 10 times when stretched in one direction, and in the case of biaxial stretching. The area magnification is 1.5 to 60 times, preferably 10 to 50 times. When other thermoplastic resins are used, the area magnification is 1.2 to 10 times, preferably 2 to 5 times when stretched in one direction, and 1.5 to 20 times in the case of biaxial stretching. It is preferably 4 to 12 times.

(Structure of support)
The support may be a single layer or may have a laminated structure.
An example of a method for manufacturing a single-layer support is shown. For example, the single-layer support containing the polyolefin-based resin film is a resin film composed of a resin composition containing 40 to 99.5% by mass of the polyolefin-based resin and 60 to 0.5% by mass of the inorganic fine powder. It can be prepared by stretching in the uniaxial or biaxial direction at a temperature lower than the melting point of the based resin (preferably a temperature lower than 3 to 60 ° C.).
An example of a method for manufacturing a support having a laminated structure is shown. For example, the support having a laminated structure of layers containing a polyolefin-based resin film is a resin film composed of a resin composition containing 40 to 100% by mass of a polyolefin-based resin and 60 to 0% by mass of an inorganic fine powder. It is stretched in the longitudinal direction at a temperature lower than the melting point of the resin (preferably a temperature lower than 3 to 60 ° C.), and at least one side of the stretched film contains 25 to 100% by mass of the polyolefin resin and 75 to 0% by mass of the inorganic fine powder. It can be prepared by laminating a resin film made of the resin composition to be used. Further, the laminated film may be stretched laterally at a temperature lower than the melting point of the polyolefin resin (preferably a temperature lower than 3 to 60 ° C.), and the resin layer laminated on the stretched film may be stretched laterally. Good.
Further, an example of a support having a polyolefin resin film on both sides of natural pulp paper will be shown. Hardwood bleached kraft pulp (LBKP), coniferous bleached kraft pulp (NBKP), or a mixture thereof is beaten, and a slurry containing a dry paper strength enhancer, a wet paper strength enhancer, a sizing agent, a filler, etc. is made into paper. The base material can be paper adjusted to an amount of 50 to 200 g / m ² and a density of 0.99 to 1.15 g / cm ³ . A resin composition containing 40 to 80% by mass of a polyolefin resin and 20 to 60% by mass of an inorganic fine powder may be extruded and laminated on both sides of this base material to form a support, and the support having the above-mentioned single-layer structure or laminated structure. The resin film described as the body may be attached to form a support.

(Physical characteristics of the support)
For the purpose of using the support as a printing medium, the thickness thereof is preferably in the range of 30 to 500 μm, more preferably in the range of 40 to 400 μm, and further preferably in the range of 50 to 300 μm. preferable.
Further, the support (particularly the thermoplastic resin film layer on the surface of the support) may be stretched as described above. By stretching a thermoplastic resin film containing an inorganic fine powder or an organic filler, a porous resin stretched film having a large number of fine pores inside can be obtained. Such a porous resin stretched film is suitable as a support for a printing medium from the viewpoints of light weight, opacity and the like. From the viewpoint of ease of handling, the stretched support preferably has a density in the range of 0.65 to 1.2 g / cm ³ , and preferably in the range of 0.7 to 1 g / cm ^3. More preferred.

Further, the stretched support preferably has a pore ratio in the range of 5 to 60%, more preferably in the range of 10 to 50%, as measured by the following method.
The vacancy ratio in each layer of the support is determined by cutting while cooling so as not to crush the vacancy of the support to create a cross section (observation surface) in the thickness direction, attaching it to the observation sample table, and applying gold to the observation surface. After vapor deposition, observe the pores of each layer at an arbitrary magnification that is easy to observe using a scanning electron microscope, capture the observed area as image data, and process the image to determine the area ratio of the pores. Find it and use this as the vacancy rate.

Further, the physical properties of the stretched support preferably have an opacity of 50% or more, and more preferably 60% or more. If the opacity of the support is 50% or more, the print can be easily visually recognized when used as a printing medium, and when used as a label paper, the barcode printing is affected by the background and a reading error occurs. There is almost no fear of doing it. Similarly, the whiteness of the stretched support is preferably 80% or more, and more preferably 90% or more. Such whiteness can contribute to the sharpness of printed matter.

(Surface oxidation treatment of support)
Before forming a resin layer on the surface of the support, corona discharge treatment, frame treatment, plasma treatment, glow discharge treatment, ozone treatment, etc., which are generally used as surface oxidation treatment, are used alone or in combination. It is preferable to use it. Among these, the corona discharge treatment and the frame treatment are preferable, and the corona discharge treatment is more preferable. When the processing amount of the corona discharge treatment, preferably carried out at 600~12,000J ^/ m 2 (10~200W · min ^{/ m 2), 1,200~10,800J / m} 2 (20~180W · min It is more preferable to carry out at / m ² ). For flame treatment, preferably carried out at 8,000~200,000J / ^{m 2,} and more preferably carried out in 20,000~100,000J / ^{m 2.}

<Resin layer>
The resin layer used in the present invention is located on at least one surface of the support and contains a cationic polyurethane resin (a), an ethyleneimine resin (b) and an acidic pH adjuster (c).
The resin layer is preferably a coating layer. However, the resin layer may be a layer formed by a method other than coating.
The print medium may have the resin layer on only one surface of the support, or may have the resin layer on both surfaces of the support.

(Cationic polyurethane resin (a))
By using the cationic polyurethane resin (a) for the resin layer, it contributes to the improvement of print quality and water resistance after storage in a high temperature and high humidity environment when performing inkjet recording using an ultraviolet curable ink. can do. Although this mechanism is unknown, this effect can be read from the comparison between Examples and Comparative Examples described later. It is expected that the improvement of print quality and water resistance after storage in a high temperature and high humidity environment also correlates with the balance of hydrophilicity and hydrophobicity of urethane resin.
The cationic polyurethane resin (a) used for the resin layer can form a coating layer having excellent adhesion to the support. Further, the cationic polyurethane resin (a) used for the resin layer can form the resin layer having abundant elasticity due to the urethane bond, and adheres to the ink by following the volume shrinkage during curing of the ultraviolet curable ink. Can be enhanced.
Further, since the cationic polyurethane resin (a) is cationic, it is highly miscible with the ethyleneimine resin (b). Therefore, in the resin layer having the structure of the present invention, the cationic polyurethane resin (a) and the ethyleneimine-based resin (b) are less likely to aggregate, and surface streaks before printing are less likely to occur.

The cationic polyurethane resin preferably has a structural unit represented by the following formula (1) in the molecule.

（上記式（１）中、Ｒ^１は、脂肪族環式構造を含んでいてもよいアルキレン基、２価フェノール類の残基、又はポリオキシアルキレン基を表し、Ｒ^２及びＲ^３は、互いに独立して脂肪族環式構造を含んでいてもよいアルキル基を表し、Ｒ^４は、水素原子又は４級化反応により導入された４級化剤の有機残基を、Ｘ⁻はアニオン性の対イオンを表す）

(In the above formula (1), R ¹ represents an alkylene group which may contain an aliphatic cyclic structure, a residue of divalent phenols, or a polyoxyalkylene group, and R ² and R ³ represent each other. Represents an alkyl group that may independently contain an aliphatic cyclic structure, R ⁴ is a hydrogen atom or an organic residue of a quaternizing agent introduced by a quaternization reaction, and X ⁻ is an anionic. Represents a pair ion)

The structural unit represented by the formula (1) is obtained by introducing a cationic hydrophilic group into a urethane resin skeleton and reacting a compound having two epoxy groups in one molecule with a secondary amine. A tertiary amino group-containing polyol can be obtained by reacting with polyisocyanate.
Examples of the compound having two epoxy groups in one molecule include a compound represented by the following formula (2).

上記式（２）中、Ｒ^１は脂肪族環式構造を含んでいてもよいアルキレン基、２価フェノール類の残基、又はポリオキシアルキレン基を表す。

In the above formula (2), R ¹ represents an alkylene group which may contain an aliphatic cyclic structure, a residue of divalent phenols, or a polyoxyalkylene group.

In the above formula, when R ¹ is an alkylene group which may contain an aliphatic ring structure, specific examples of the compound represented by the above formula include ethanediol-1,2-diglycidyl ether and propanediol. -1,2-Diglycidyl ether, Propanediol-1,3-Diglycidyl ether, Butanediol-1,4-Diglycidyl ether, Pentandiol-1,5-Diglycidyl ether, 3-Methyl-pentanediol-1 , 5-Diglycidyl ether, neopentyl glycol-diglycidyl ether, hexanediol-1,6-diglycidyl ether, polybutadiene-diglycidyl ether, cyclohexane-1,4-diglycidyl ether, 2,2-bis (4-) Examples thereof include diglycidyl ether of hydroxycyclohexyl) -propane (hydrogenated bisphenol A) and diglycidyl ether of an isomer mixture of hydrogenated dihydroxydiphenylmethane (hydrogenated bisphenol F).

When R ¹ is a residue of dihydric phenols in the above formula, specific examples of the compound represented by the above formula include resorcinol-diglycidyl ether, hydroquinone-diglycidyl ether, and 2,2-bis (). 4-Hydroxyphenyl) -propane (bisphenol A) diglycidyl ether, dihydroxydiphenylmethane isomer mixture (bisphenol F) diglycidyl ether, 4,4-dihydroxy-3-3'-dimethyldiphenyl propane diglycidyl ether, Diglycidyl ether of 4,4-dihydroxydiphenylcyclohexane, diglycidyl ether of 4,4-dihydroxydiphenyl, diglycidyl ether of 4,4-dihydroxydibenzophenone, diglycidyl of bis (4-hydroxyphenyl) -1,1-ethane Diglycidyl ether, bis (4-hydroxyphenyl) -1,1-isobutane diglycidyl ether, bis (4-hydroxy-3-t-butylphenyl) -2,2-propane diglycidyl ether, bis (2-hydroxy) Examples thereof include diglycidyl ether of naphthyl) methane and diglycidyl ether of bis (4-hydroxyphenyl) sulfone (bisphenol S).

When R ¹ is a polyoxyalkylene group in the above formula, specific examples of the compound represented by the above formula include diethylene glycol-diglycidyl ether, dipropylene glycol-diglycidyl ether, and the number of repeating units of oxyalkylene. 3 to 60 polyoxyalkylene glycol-diglycidyl ethers, such as polyoxyethylene glycol-diglycidyl ethers and polyoxypropylene glycol-diglycidyl ethers, ethylene oxide-propylene oxide copolymer diglycidyl ethers, polyoxytetraethylene Glycol-diglycidyl ether and the like can be mentioned.

As the secondary amine, a known compound can be used, but a branched or linear aliphatic secondary amine is preferable from the viewpoint of ease of reaction control.
Specific examples of those that can be used as such secondary amines are dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, di-t-butylamine, di-sec-butylamine, and di. -N-pentylamine, di-n-peptylamine, di-n-octylamine, diisooctylamine, dinonylamine, diisononylamine, di-n-decylamine, di-n-undecylamine, di-n-dodecylamine, Examples thereof include di-n-pentadecylamine, di-n-octadecylamine, di-n-nonadecilamine, and di-n-eicosylamine.
Among these, when it is difficult to volatilize when producing a tertiary amino group-containing polyol, or when some or all of the contained tertiary amino groups are neutralized with an acid or quaternized with a quaternizing agent. Aliphatic secondary amines in the range of 2 to 18 carbon atoms are more preferable, and aliphatic secondary amines in the range of 3 to 8 carbon atoms are even more preferable because steric hindrance can be alleviated.

Known compounds can also be used as the polyisocyanate. Specific examples of such polyisocyanates include organic polyisocyanates used in the production of urethane-based resins such as aromatic polyisocyanates, alicyclic polyisocyanates, and aliphatic polyisocyanates.

Further, the cationic polyurethane resin (a) preferably has an emulsion form. The cationic polyurethane resin (a) is an aqueous medium from the viewpoint of facilitating coating when a coating liquid described later is prepared, reducing surface streaks before printing, and enhancing the water resistance and adhesion of the obtained resin layer. It is more preferably in the form of an emulsion dispersed therein and not redissolved after drying. Further, from the viewpoint of enhancing the transparency of the resin layer, the average dispersed particle size of the cationic polyurethane resin (a) emulsion can be, for example, 0.005 to 0.10 μm, preferably 0.005 to 0.05 μm. .. The average dispersed particle size of the emulsion is a cumulative particle size (cumulative 50% particles) measured by a particle measuring device, for example, a laser diffraction type particle measuring device "Microtrack" (manufactured by Microtrac Bell Co., Ltd., trade name). Diameter), observation of primary particle size with a scanning electron microscope (for example, average value of 100 particles), conversion from specific surface area (for example, using powder specific surface area measuring device SS-100 manufactured by Shimadzu Corporation) The specific surface area can be measured).
The minimum film-forming temperature of the cationic polyurethane resin (a) is preferably 0 to 40 ° C, more preferably 0 to 5 ° C.
From the cationic urethane resin (a), an emulsion of the cationic urethane resin (a) can be obtained by using a known method such as an acetone method, a prepolymer mixing method, a ketimine method, or a hot melt dispersion method.
Examples of the cationic polyurethane resin emulsion include Superflex 600, 610, 620, 650 (trade name) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. and Hydran CP-7030, 7050, 7060 (trade name) manufactured by DIC Corporation. Name), Neo Sticker made by Nikka Kagaku Co., Ltd., etc. are commercially available and can be used.

(Ethethylene imine resin (b))
Since the ethyleneimine-based resin (b) has a strong affinity with the ultraviolet curable ink, it is possible to improve the ink adhesion with the ultraviolet curable ink.
Types of ethyleneimine-based resin (b) include polyethyleneimine, poly (ethyleneimine-urea), and ethyleneimine adducts of polyamine polyamide, or alkyl-modified, cycloalkyl-modified, aryl-modified, and allyl-modified of these. Examples include the body, aralkyl modified product, benzyl modified product, cyclopentyl modified product, modified product, or aliphatic cyclic hydrocarbon modified product, or hydroxides thereof. These can be used alone or in combination of two or more.

Among these, modified products obtained by modifying the ethyleneimine adduct of polyethyleneimine or polyamine polyamide with a modifier such as alkyl halide, alkenyl halide, cycloalkyl halide or benzyl halide having 1 to 24 carbon atoms are used as ink. It is preferable from the viewpoint of improving the adhesion of.
Specific examples of the halide used as the modifier include methyl chloride, methyl bromide, n-butyl chloride, lauryl chloride, stearyl iodide, oleyl chloride, cyclohexyl chloride, benzyl chloride, allyl chloride, cyclopentyl chloride and the like. ..
Examples of such ethyleneimine-based resins include Epomin P-1000 (trade name) manufactured by Nippon Catalyst Co., Ltd., Polymin SK (trade name) manufactured by BASF, and Saftmer AC- manufactured by Mitsubishi Chemical Corporation. 72 (trade name) and the like are commercially available and can be used.

(Acid pH regulator (c))
The cationic polyurethane resin (a) preferably used in the present invention is an emulsion designed to have high water resistance and adhesion after drying and has a small average particle size, so that it easily aggregates in the coating liquid. Has properties. Generally, when the absolute value of the surface potential (zeta potential, or interfacial electrokinetic potential) of nano-sized particles is 20 mV or more, the electric double layer is hard to break and the dispersibility of the particles is good. To. In the present invention, it is preferable that the zeta potential of the cationic polyurethane resin (a) in the state of the coating liquid in which the acidic pH adjuster (c) is added to the aqueous dispersion of the cationic polyurethane resin (a) is 20 mV or more. , 30 mV or more is more preferable. As a result, the dispersibility of the cationic polyurethane resin is improved, aggregation is less likely to occur when mixed with the ethyleneimine resin (b), and a coating liquid that is less likely to aggregate or thicken can be obtained. As a result, the coating is facilitated, the amount of foreign matter is small, and the resin layer with few surface streaks before printing tends to be obtained. On the other hand, the zeta potential of the cationic polyurethane resin in the state of the coating liquid is preferably 80 mV or less, more preferably 70 mV or less, and particularly preferably 60 mV or less. As a result, the water resistance of the resin layer tends to be improved, and the adverse effects of the addition of the acidic pH adjuster (c) and the cationic polyurethane resin (a) tend to be reduced.
In order to keep the zeta potential of the cationic polyurethane resin (a) in the state of the coating liquid within the above range, the acidic pH adjuster (c) needs to be acidic. The acidic pH adjuster (c) preferably has a pKa as a free acid of −0.2 to 6.8, and more preferably 0.5 to 6.0. It is preferable that all pKa of the acid having 2 or more pKa is within the above range.
Further, it is preferable that the pH of the coating liquid for forming the resin layer is 1.0 to 7.4 by adding the acidic pH adjuster (c), and 3.0 to 7.2 is more preferable. It is preferable, and 4.0 to 6.5 is particularly preferable. When the pH of the coating liquid is not more than the upper limit of the above preferable range, the zeta potential of the cationic polyurethane resin (a) in the state of the coating liquid can be easily controlled within the preferable range, and the cationic polyurethane resin (a) becomes easy to control. It becomes difficult to aggregate. When an acid having a low pKa as a free acid is used, a base may be added to adjust the pH of the coating liquid and the zeta potential of the cationic polyurethane resin (a) in the state of the coating liquid within the above range. it can. Examples of the base that can be used include sodium hydroxide, potassium hydroxide, ammonia and the like. The ethyleneimine resin (b) also has a function as a base. For example, when sulfonic acids such as paratoluenesulfonic acid having a low pKa are used, it is preferable to use a base such as ammonia.
Further, if the acidic pH adjusting agent (c) is in a solid state or a gaseous state under normal use conditions, the acidic pH adjusting agent (c) moves in the resin layer and seeps out to the surface of the resin layer. It is unlikely that printing ink transfer defects will occur due to migration. Especially in plate printing, the tendency that migration is unlikely to occur is remarkable. Further, if migration is unlikely to occur, it tends to be difficult to repel the inkjet ink. The acidic pH adjuster (c) is preferably in a solid state at 20 ° C. and 1 atm, more preferably in a solid state at 40 ° C. and 1 atm, and particularly preferably in a solid state at 60 ° C. and 1 atm. preferable. As a result, the acidic pH adjuster (c) is a solid under normal use conditions, and migration over time can be prevented, so that the ink transfer property of the print medium after long-term storage tends not to be impaired. The acidic pH adjuster (c) may be in a gaseous state at 20 ° C. and 1 atm, and examples of the gaseous acidic pH adjuster (c) include hydrochloric acid. When the acidic pH adjuster (c) is a gas under normal use conditions, the concentration in the resin layer after drying is preferably 100 ppm or less, preferably 50 ppm or less, in order to prevent migration over time. Is more preferable, and 30 ppm or less is further preferable.

In the printing medium of the present invention, the acidic pH adjuster (c) contains a monovalent aliphatic carboxylic acid having 9 to 18 carbon atoms, a divalent or higher aliphatic carboxylic acid having 3 to 12 carbon atoms, and an aromatic carboxylic acid. It is preferable to contain one or more acids selected from boric acids and phosphoric acids from the viewpoint of easy preparation of a coating liquid having the above properties. The acidic pH adjuster (c) is composed of a monovalent aliphatic carboxylic acid having 9 to 18 carbon atoms, a divalent or higher aliphatic carboxylic acid having 3 to 12 carbon atoms, an aromatic carboxylic acid, boric acids and phosphoric acids. It may be an acid consisting of one or more residues selected. As used herein, the "acid consisting of residues" of an acid refers to the rest of the acid's liberable ions.
The divalent or higher carboxylic acid having 3 to 12 carbon atoms includes a divalent or higher hydroxycarboxylic acid having 3 to 8 carbon atoms, and a divalent or higher carboxylic acid having 3 to 8 carbon atoms is one of the preferred embodiments. It is one. The aromatic carboxylic acid includes an aromatic hydroxycarboxylic acid. Boric acids include orthoboric acid and metaboric acid. Phosphoric acids include orthophosphoric acid, metaphosphoric acid and polyphosphoric acid.
The acidic pH adjuster (c) is selected from monovalent aliphatic carboxylic acids having 9 to 18 carbon atoms, divalent or higher aliphatic carboxylic acids having 3 to 12 carbon atoms, aromatic carboxylic acids and phosphoric acids 1 It is more preferable to contain the above acids, and it is particularly preferable to contain one or more acids selected from divalent or higher aliphatic carboxylic acids having 3 to 12 carbon atoms, aromatic carboxylic acids and phosphoric acids. Among the acidic pH adjusters (c), citric acid, ortholic acid, metaphosphate, citric acid, itaconic acid, tartaric acid, L-lactic acid, and malic acid are more preferable, and citric acid, itaconic acid, tartaric acid, L-lactic acid, and malic acid are used. Acids are particularly preferred, and citric acid is even more preferred.

(Mixing amount ratio)
The blending amount ratio of each component in the resin layer as a solid content after drying is preferably 1 to 60 parts by mass of the ethyleneimine resin (b) with respect to 100 parts by mass of the cationic polyurethane resin (a). , 1 to 40 parts by mass is more preferable, and 10 to 20 parts by mass is particularly preferable.
Further, in order to adjust the pH within the above range, the acidic pH adjuster (c) is preferably contained in an amount of 0.01 to 5 parts by mass, preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the cationic polyurethane resin (a). It is more preferable to include parts by mass. It is more preferable to adjust the pH of the coating liquid to the above-mentioned preferable range for coating.
When the amount ratio of each component in the resin layer is within this range, high print quality and water resistance and adhesion of printed matter can be obtained in various printing methods and information recording methods.

(Other ingredients)
The resin layer does not contradict the gist of the present invention by using a cross-linking agent (d), an antistatic agent (e), an antifoaming agent, other auxiliary agents, etc. as necessary to improve coating suitability and printability. Can be included in the range.

-Crosslinking agent (d)-
The resin layer may contain a cross-linking agent (d). From the viewpoint of further enhancing the water resistance and adhesion of the resin layer, the cross-linking agent (d) is preferably a substance that reacts with the ethyleneimine resin (b) to cross-link. Further, since the coating material constituting the resin layer is provided in the form of an aqueous solution or an aqueous dispersion, the cross-linking agent (d) is preferably a water-soluble substance. Further, in order to give flexibility to the resin layer, it is preferable that the cross-linking agent (d) is a bifunctional substance or a polymer-based substance. On the other hand, in order to impart water adhesion resistance and abrasion resistance to the resin layer, it is preferable that the cross-linking agent (d) is a low molecular weight substance having trifunctionality or higher. A bifunctional substance and a trifunctional or higher functional substance may be used in combination as the cross-linking agent (d).
Examples of the cross-linking agent (d) include epoxy-based, isocyanate-based, formalin-based, and oxazoline-based resins. Among these, bisphenol A-epichlorohydrin resin, epichlorohydrin resin of polyamine polyamide, aliphatic epoxy resin, epoxy novolac resin, alicyclic epoxy resin, brominated epoxy resin are preferable, epichlorohydrin adduct of polyamine polyamide, or monofunctional to polyfunctional. Glysidyl ethers and glycidyl esters are more preferable. Among them, the epichlorohydrin adduct of polyamine polyamide is particularly preferable because it can obtain a highly flexible coating film while being polyfunctional and is water-soluble.
The cross-linking agent (d) preferably contains 5 to 30 parts by mass, more preferably 10 to 20 parts by mass, as a solid content with respect to 100 parts by mass of the cationic polyurethane resin (a).

-Antistatic agent (e)-
The resin layer may contain an antistatic agent (e). By adding an antistatic agent to the resin layer, it is possible to reduce the adhesion of dust to the printing medium and troubles caused by static electricity during printing and printing. The antistatic agent (e) is preferably a polymer-type antistatic agent that does not easily seep out to the surface of the resin layer under long-term storage and cause deterioration of ink adhesion. On the other hand, as the antistatic agent (e), a cationic type, an anionic type, an amphoteric type, a nonionic type and the like can be used, but even if mixed with the cationic polyurethane resin (a) and the ethyleneimine resin (b), they aggregate. The cationic type or nonionic type, which is less likely to cause a problem, is preferable, and the cationic type, which can obtain high antistatic properties with a small amount of addition, is more preferable. Examples of the cationic type include those having an ammonium salt structure and a phosphonium salt structure. Examples of the anion type include alkali metal salts such as sulfonic acid, phosphoric acid and carboxylic acid, for example, alkali metal salts such as acrylic acid, methacrylic acid and (anhydrous) maleic acid (eg, lithium salt, sodium salt, potassium salt and the like). ) Those having a structure in the molecular structure can be mentioned. The amphoteric type contains both the above-mentioned cationic type and anionic type structures in the same molecule, and examples thereof include the betaine type. Examples of the nonionic type include an ethylene oxide polymer having an alkylene oxide structure and a polymer having an ethylene oxide polymerization component in the molecular chain. In addition, a polymer-type antistatic agent having boron in its molecular structure can be mentioned as an example. Among these, a nitrogen-containing polymer-type antistatic agent which is a cationic type and a polymer type is preferable, and a tertiary nitrogen or a quaternary nitrogen-containing acrylic resin is more preferable.

(Solvent and solid content concentration)
The resin layer is preferably a coating layer formed by applying a coating liquid. Since the coating liquid forming the coating layer is easy to control the process, the above components are homogenized in a solvent such as water, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, ethyl acetate, toluene, or xylene. It is preferable to dissolve or disperse it in a solution or a dispersion. Above all, from the viewpoint of safety and odor, it is more preferable to use any of the above components as a water-soluble or water-dispersible substance in the form of an aqueous solution or an aqueous dispersion. The aqueous solution may contain alcohols and ketones that are compatible with water as co-solvents.
The solid content concentration in the coating liquid forming the resin layer is preferably 0.1% by mass or more, more preferably 0.2% by mass or more. The solid content concentration in the coating liquid forming the resin layer is preferably 20% by mass or less, more preferably 10% by mass or less.

(Solid content)
Printing medium of the present invention, the resin layer is preferably from 0.01g ^{/ m 2} ~7g ^/ m 2 as a solid content, more preferably from ^{0.01g / m 2 ~5g / m 2} , 0.05 g / m ² to ³ g / m ² is particularly preferable. The solid content of the resin layer in the present specification means the amount of solid content after drying per one side. In order to practically develop the adhesion of the ultraviolet curable ink, the solid content (coating amount) of the resin layer is preferably at least the lower limit of the preferable range. It is preferable that the solid content (coating amount) of the resin layer is not more than the upper limit of the preferable range from the viewpoint of preventing the adhesion force due to the cohesive failure of the resin layer from occurring and reducing the material cost.

<Printing method on print media>
Printing on the printing medium of the present invention includes various known printing methods such as offset printing, gravure printing, flexo printing, letter press printing, screen printing, inkjet recording method, thermal transfer recording method, pressure sensitive transfer recording method, and electrophotographic recording method. It is possible to use the method. From the viewpoint of print fineness, gravure printing, an inkjet recording method, and an electrophotographic recording method are preferable, and from the viewpoint of being able to handle small lots, letter press printing and flexographic printing are preferable.
If the surface of the print medium does not have enough voids to absorb a large amount of ink (generally 1 g / m ² or more), the inkjet recording method using ultraviolet curable ink (so-called UV inkjet method) is one of the inkjet recording methods. ) Is preferable.

[Manufacturing method of print media]
In the method for producing a printing medium of the present invention, a cationic polyurethane resin (a), an ethyleneimine resin (b) and an acidic pH adjuster (c) are formed on at least one surface of a support containing a thermoplastic resin as a main component. Including a step of forming a resin layer by applying a coating liquid containing. That is, in the printing medium of the present invention, it is preferable that the resin layer is a coating layer formed from a coating liquid. Since the state of the surface streaks of the printing medium before printing differs depending on the pH, zeta potential, and addition of the acidic pH adjuster (c) in the state of the coating liquid, it is technically technical to specify the structure of the resin layer. It involves work that is almost impossible or impractical to identify. Furthermore, it is technically impossible or practically impractical to specify the structure in which a resin component such as an ethyleneimine resin is crosslinked when a cross-linking agent is added to the coating liquid. It involves work. Therefore, one of the preferred embodiments of the print medium of the present invention is also preferably described in a product-by-process claim.

(Coating)
In the coating step, a coating liquid containing a cationic polyurethane resin (a), an ethyleneimine-based resin (b) and an acidic pH adjuster (c) is applied to at least one surface of the support to form a resin layer. Form.
In the method for producing a printing medium of the present invention, the zeta potential of the cationic polyurethane resin (a) in the state of the coating liquid is preferably 20 mV or more, and more preferably 20 mV to 70 mV. Further, in the method for producing a printing medium of the present invention, the pH of the coating liquid is preferably 1.0 to 7.4, more preferably 3.0 to 7.2. The zeta potential of the cationic polyurethane resin (a) in the state of the coating liquid in the method for producing a printing medium of the present invention and a more preferable range of the pH of the coating liquid are described in the description of the printing medium of the present invention. Similar to the preferred range.

The formation of the resin layer is preferably performed by applying a coating liquid to at least one surface of the outermost layer of the support. From the viewpoint of antistatic performance, it is preferable to apply a coating liquid on both surfaces of the support.
The coating step may be carried out together with the support molding in the support molding line, or may be carried out on a separate line using the already molded support. When the molding of the support is performed by the stretching method, the coating may be performed before the stretching step, or may be performed after the stretching step.
Excess solvent may be removed before or after the coating step, if necessary, through a drying step using an oven or the like.
A general coating device can be used to apply the coating liquid to the support, and the solid content (coating amount) after drying, the viscosity of the coating liquid, and the solids of the chemicals in the coating liquid can be used. Select as appropriate according to the component concentration and the like. Examples of the coating device include a roll coater, a blade coater, a bar coater, an air knife coater, a size press coater, a gravure coater, a die coater, a lip coater, and a spray coater. Among them, a roll coater, a bar coater, a size press coater, a gravure coater, and a spray coater are used in a preferred embodiment of the compounding amount ratio of the cationic polyurethane resin (a), the ethyleneimine resin (b), and the acidic pH adjuster (c). It is preferable to use, and it is more preferable to use a roll coater, a size press coater, and a gravure coater.

[Printed matter]
The printed matter of the present invention has an ultraviolet curable ink on the resin layer of the printing medium of the present invention.

<UV curable ink>
A solution or dispersion containing any colorant can be used for printing. A solution or dispersion containing a colorant is called "ink" or "ink". In general, those used for plated printing performed using a plate may be distinguished from "ink", and those used for non-plate printing such as printer output without using a plate may be used separately from "ink". In the present specification, "ink" and "ink" are described as "ink" without particular distinction.
The ink used for these printings is preferably an ultraviolet curable ink from the viewpoint of ink adhesion (fixability) and scratch resistance.
When printing with UV curable ink, the UV curable ink is solidified by UV irradiation. The ultraviolet irradiation method is not particularly limited as long as it cures the ultraviolet curable ink, and for example, a metal halide lamp (200 to 400 nm), a low pressure mercury lamp (180 to 250 nm), a high pressure mercury lamp (250 to 365 nm), and a black light. (350 to 360 nm), ultraviolet rays emitted from a UV-LED lamp (355 to 375 nm) may be irradiated so as to have an irradiation amount of 300 to 3000 mJ / cm ² , preferably 400 to 1000 mJ / cm ^2. ..
The ultraviolet curable ink is not particularly limited, and known ultraviolet curable inks can be used. The UV curable ink preferably contains at least a diluent, a compound having a bifunctional or higher functional group, and a colorant.
Examples of the material used for the ultraviolet curable ink include the materials (particularly aliphatic urethane acrylates) described in Japanese Patent Application Laid-Open No. 2004-526016, [0016] to [097], and JP-A-2002-080767 [0010] to Materials described in [0062] (particularly anionic aqueous polyurethane compounds) and materials described in [0004] to [0026] of JP-A-2010-530922 (particularly chlorinated polyolefins having excellent adhesion to polyolefin films). Etc. can be preferably used. The contents of these publications are incorporated herein by reference.
As the ultraviolet curable ink, one containing acryloyl morpholine as a diluent can also be preferably used.

In inkjet recording using ultraviolet curable ink, if the ink droplets flow between the time when the ink droplets land on the outermost layer of the print medium and the time when the ink droplets are solidified by ultraviolet irradiation, the image becomes blurred or the line art becomes thick. As a result, the print quality (image quality) is affected.
From the viewpoint of improving the print quality of the inkjet recording using the ultraviolet curable ink, it is preferable that the pH of the coating liquid forming the resin layer is 3.0 or more. When the pH of the surface of the resin layer of the printing medium is equal to or higher than the lower limit of the pH of the coating liquid, which is preferable, the ink droplets are less likely to be deformed and the line art is blurred so that the ink droplets are repelled after the ink droplets land. Since the pigments inside are less likely to aggregate to form a metallic glossy film, the print quality can be improved.

Hereinafter, the present invention will be described in more detail with reference to examples. The materials, amounts used, proportions, treatment contents, treatment procedures, etc. shown below can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention is not limited to the examples shown below. Unless otherwise specified, "parts" and "%" are based on mass. "Parts by weight" and "% by weight" are synonymous with "parts by mass" and "% by mass". “Wt%” is synonymous with “mass%”. Examples 10 and 11 are reference examples.

The materials used in Examples and Comparative Examples are shown in Table 1 below.

[Manufacturing Example 1]
The support of Production Example 1 was produced by the following method.
(1) 81% by mass of a propylene homopolymer (melting point 164 ° C.) of 0.8 g / 10 min MFR (melt flow rate), 3% by mass of high-density polyethylene, and 16% by mass of heavy calcium carbonate having an average particle diameter of 1.5 μm. The resin composition (A) mixed with% was kneaded in an extruder set at a temperature of 270 ° C., extruded into a sheet, and further cooled by a cooling device to obtain an unstretched sheet. Next, this sheet was heated again to a temperature of 150 ° C., and then stretched 5 times in the vertical direction by utilizing the difference in peripheral speeds of the roll groups to obtain a vertically stretched 5 times film.
(2) Separately, a resin composition (B) in which 55% by mass of a propylene homopolymer (melting point 164 ° C.) of MFR 4 g / 10 minutes and 45% by mass of heavy calcium carbonate having an average particle diameter of 1.5 μm was mixed was 270. After kneading with two other extruders set to a temperature of ℃, it was extruded into a sheet, which was laminated on both sides of the vertically 5 times stretched film obtained in the step (1) above to form a three-layer structure. A laminated film was obtained.

(3) Next, the laminated film having this three-layer structure was cooled to a temperature of 60 ° C., then heated to a temperature of 155 ° C. again, stretched 7.5 times in the lateral direction using a tenter, and heated to 165 ° C. After annealing at a temperature and cooling to a temperature of 60 ° C., the ears were slit to obtain a laminated stretched film having a three-layer structure.
The obtained three-layer structure laminated stretch film has a number of stretch axes of each layer (B layer / A layer / B layer) of uniaxial stretching / biaxial stretching / uniaxial stretching, and a thickness of 80 μm (B layer / A layer / B). The thickness of each layer was 15 μm / 50 μm / 15 μm), the density was 0.79 g / cm ³ , the porosity was 29%, the opacity was 90%, and the whiteness was 95%. .. Density, porosity, opacity and whiteness were measured by known methods.
(4) A corona discharge treatment device (trade name: HF400F, manufactured by Kasuga Electric Co., Ltd.), a 0.8 m long aluminum discharge electrode, and a silicone coating on a treater roll on one surface of a three-layer structure laminated stretch film. Using a roll, the gap between the discharge electrode and the treater roll was set to 5 mm, and corona discharge treatment was performed at a line processing speed of 15 m / min and an applied energy density of 4,200 J / m ² . The obtained support was used as the support of Production Example 1. The support of Production Example 1 contains a thermoplastic resin as a main component.

[Manufacturing Example 2]
The support of Production Example 2 was produced by the following method.
One side of a commercially available polyester film (trade name "Lumilar E20", manufactured by Toray Industries, Inc., thickness 100 μm) was subjected to the same corona discharge treatment as in Production Example 1. The obtained support was used as the support of Production Example 2. The support of Production Example 2 contains a thermoplastic resin as a main component.

[Manufacturing Example 101]
The coating liquid of Production Example 101 was produced by the following method.
Cationic polyurethane resin aqueous dispersion (trade name: Superflex 650, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as the cationic polyurethane resin (a) has a solid content of 6% by mass, and polyethyleneimine as the ethyleneimine resin (b). (Product name: Epomin P-1000, manufactured by Nippon Catalyst Co., Ltd.) is added as a solid content of 0.8% by mass, and orthophosphoric acid as an acidic pH adjuster (c) is added so as to have a pH of 5.5. I got the liquid. The obtained coating liquid was used as the coating liquid of Production Example 101.
Table 2 below shows the blending ratio of the coating liquid of each production example (solid content concentration in aqueous dispersion wt%). In Table 2 below, "○" described in the column of the acidic pH adjusting agent (c) means that the pH of the coating liquid was adjusted by using the corresponding type of acidic pH adjusting agent (c). .. The acidic pH adjuster (c) added to the coating liquid in each example was in the range of 0.5 to 3 parts by mass with respect to 100 parts by mass of the cationic polyurethane resin (a).

[Example 1]
On the surface of the support of Production Example 1 on the corona discharge treatment side, the coating liquid of Production Example 101 is applied so that the solid content after drying is 0.5 g (0.5 / m ² ) per unit area (m ² ). The coating was performed using a bar coater with a large coating amount (solid content). Next, the supported support after coating was placed in an oven at 60 ° C., the coating liquid was dried to form a resin layer (coating layer), and finally wound into a roll with a winder to obtain a printing medium. .. The obtained print medium was used as the print medium of Example 1.

[Examples 2 to 11 and Comparative Examples 2 to 4]
The materials shown in Table 1 above are prepared at the blending ratios shown in Table 2 below, and the pH is adjusted to the pH shown in Table 2 by adding an acidic pH adjuster (c) to prepare Examples 102 to 111 and 113 to 113. 115 coating solutions were produced. The coating liquid of Production Example 104 was produced so that the pH of the coating liquid was 3.2 by using ammonia water in combination when adjusting the pH of the coating liquid with the acidic pH adjuster (c). The coating liquid of Production Example 107 was produced so that the pH of the coating liquid was 7.0 by using sodium hydroxide in combination when adjusting the pH of the coating liquid with the acidic pH adjuster (c).
Examples 2 to 11 and Comparative Examples were the same as in Example 1 except that the coating liquids listed in Table 2 below were used as the coating liquid and the coating amount (solid content) shown in Table 2 below was used. 2-4 print media were obtained.

[Comparative Example 1]
The coating liquid of Production Example 112 was produced in the same manner as in Production Example 105 except that the acidic pH adjuster (c) was not added in the production of the coating liquid of Production Example 105.
A printing medium of Comparative Example 1 was obtained in the same manner as in Example 1 except that the coating liquid of Production Example 112 was used as the coating liquid and the coating amount (solid content) shown in Table 2 below was used.

[Example 12]
In Example 5, the printing medium of Example 12 was obtained in the same manner as in Example 5 except that the coating liquid obtained in Production Example 105 of the coating liquid was applied to the surface of the support of Production Example 2. It was.

<Physical characteristics of coating liquid>
(Measurement of pH)
The pH of the coating liquid of each production example was measured using a portable pH meter D71 manufactured by HORIBA, Ltd. The results obtained are shown in Table 2 below.

(Measurement of zeta potential)
A sample for measurement was obtained by diluting the cationic polyurethane resin (a) in the coating liquid of each production example with distilled water so that the solid content concentration was 1.0%. The zeta potential was measured using a zeta potential meter / particle size measurement system ELSZ-2 (manufactured by Otsuka Electronics Co., Ltd.) while appropriately diluting the measurement sample. The results obtained are shown in Table 2 below.
When the above CU1 was used as the cationic polyurethane resin (a) in the measurement of the zeta potential, the average dispersed particle size of the CU1 was small and sufficient light scattering intensity could not be obtained, so that the zeta potential could be obtained. There wasn't. In this case, "-" is described in the column of zeta potential in Table 2 below.
In Table 2 below, when the measured value of the zeta potential is positive, a “+” sign is added for clarification.

<Solid content of resin layer>
The solid content (coating amount) of the resin layer of the printing medium of each Example and Comparative Example is shown in Table 2 below. The solid content of the resin layer of the printing medium of each Example and Comparative Example can be measured by peeling off the resin layer. The solid content of the resin layer of the printing medium of each Example and Comparative Example is in agreement with the value calculated from the solid content of the coating liquid of each production example.

[Evaluation of print media]
The print media obtained in each Example and Comparative Example were evaluated for (1) physical properties before printing, (2) general printability, and (3) inkjet suitability, respectively, as follows. The results are summarized in Table 3 below.
Regarding (2) general printability and (3) inkjet suitability, the print medium was evaluated after storage in a high humidity environment.

(1) Physical characteristics before printing (also called blank paper physical characteristics)
(Surface streaks)
The print medium was cut to a width of 210 mm, the surface was visually observed, and the frequency of surface streaks (coating streaks caused by coating) parallel to the coating flow direction was visually observed and evaluated in the following five stages. ..
5: No streaks are seen (good)
4: One streak can be seen (possible)
3: Two or three streaks can be seen (possible)
2: 4 to 10 streaks can be seen (impossible)
1: 10 or more streaks can be seen (impossible)

(Surface resistivity)
The print medium was cut into 10 cm × 10 cm and allowed to elapse for 2 hours in an atmosphere of a temperature of 23 ° C. and a relative humidity of 50%. After that, the surface resistivity of the resin layer side of the print medium conforms to JIS K 6911: 1995, and an insulation meter (trade name: DSM-8103, manufactured by Toa Denpa Kogyo Co., Ltd.) and a double ring method electrode are used. It was measured. JIS is an abbreviation for Japanese Industrial Standards.
When the measured surface resistivity is 1 × 10 ¹³ Ω or more, it is judged that there is no antistatic property. When the measured surface resistivity is less than 1 × 10 ¹³ Ω, the antistatic property is good, the paper supply / output property at the time of printing and printing is good, and it is suitable as a printing medium.

(2) General printability (ink transferability)
The print media of each Example and Comparative Example were stored for 7 days in an atmosphere having a temperature of 40 ° C. and a relative humidity of 80%.
Printing machine (trade name: RI-III type printing aptitude tester, manufactured by Akira Seisakusho Co., Ltd.) and UV curable printing ink (trade name: Best Cure 161 (indigo), manufactured by T & K TOKA Co., Ltd.) The above ink was solidly printed on the surface of the printing medium on the resin layer side so as to have a thickness of 1.5 g / m ² . The term "solid printing" as used herein means printing the entire surface with a single ink on a specific range of a printing medium. The solid printed area is called the color exhibition surface. Next, under one ultraviolet lamp (metal halide lamp, output 80 W / cm, manufactured by Eye Graphics Co., Ltd.), the printed surface is irradiated with ultraviolet rays by passing it once at a speed of 10 m / min at a distance of 10 cm from the lamp. , A printed matter obtained by drying and solidifying the ink was obtained. After that, the light reflection density (Macbeth density) of the printed matter was measured with a Macbeth densitometer (manufactured by Colmogen, USA), and unevenness of the color-developed surface (impaired transfer such as coated streaks and white spots) was visually observed. It was evaluated in stages.
5: Optical density is 2.0 or more (good)
4: Optical density is 1.7 or more and less than 2.0 (possible)
3: Optical density is 1.5 or more and less than 1.7 (possible)
2: Optical density is less than 1.5, but unevenness is not noticeable 1: Optical density is less than 1.5, and unevenness is noticeable

(Ink adhesion)
Cellophane tape (trade name: Cellotape (registered trademark) CT-18, manufactured by Nichiban Co., Ltd.) was attached to the printed surface of the printed matter obtained in the above evaluation of ink transferability, and after sufficient adhesion, the cellophane tape was quickly peeled off. .. Next, the ink adhesion was evaluated on a 5-point scale based on the following criteria from the visual observation of the state of the printed surface after the tape was peeled off.
5: Ink does not peel off at all (good)
4: A small part of the ink peeled off (possible)
3: The peeled part was less than 25% (possible)
2: The peeled part was 25% or more and less than 50% (impossible)
1: The peeled part was 50% or more (impossible)

(Actual machine printing test: ground stain)
The print media of each Example and Comparative Example were stored for 7 days in an atmosphere having a temperature of 40 ° C. and a relative humidity of 80%.
After printing 2000 sheets with a high-speed compact offset printing machine (Hamada 612CD; manufactured by Hamada Printing Machine Co., Ltd.), visually observe the state of the printing plate and the blank printing surface of the film, and perform the following three steps. evaluated. Ground stain refers to ink adhesion on a blank sheet of paper.
3; No background stains on both printing plate and film (good).
2; Only the printing plate has a background stain on the blank sheet (possible).
1; There is ground stain on both the printing plate and the film.

(3) Ink suitability (ink contact angle)
The print media of each Example and Comparative Example were stored for 7 days in an atmosphere having a temperature of 40 ° C. and a relative humidity of 80%.
After allowing the print medium to elapse for 2 hours in an atmosphere of a temperature of 23 ° C. and a relative humidity of 50%, 0.5 using a portable contact angle meter PG-X + (manufactured by FIBRO system ab) and an ultraviolet curable inkjet printing ink. The contact angle after seconds was measured. The contact angle was evaluated according to the following criteria.
The larger the contact angle of the UV curable ink, the less likely the ink bleeds to occur in the print medium. Therefore, when inkjet recording is performed using the UV curable ink, the print quality after storage in a high temperature and high humidity environment is improved. It will be good.
3: 20 ° or more (good)
2: 15 ° or more and less than 20 ° (possible)
Less than 1: 15 °

(Print quality)
For printing, an ultraviolet curable inkjet printing machine (trade name "OceArizona250GT", manufactured by Oce) and an ultraviolet curable inkjet printing ink (trade name: Best Cure 161 (ink), manufactured by T & K TOKA Co., Ltd.) were used. ..
After storing for 7 days in an atmosphere of a temperature of 40 ° C. and a relative humidity of 80%, the print medium was allowed to elapse for another 3 days in an atmosphere of a temperature of 23 ° C. and a relative humidity of 50%. Then, using the above-mentioned printing machine, 100% solid and characters (ruled line thickness: 5 pt) were inkjet-printed on the surface of the resin layer of the printing medium. The characters after printing were visually observed and observed with a magnifying glass, and the print quality was evaluated from the ink bleeding according to the following criteria.
5: No ink bleeding (good)
4: Ink bleeding is not clear visually, but the dot area is widened when observed with a magnifying glass 3: Ink bleeding is slightly observed visually (possible)
2: Ink bleeding is visually observed (possible)
1: Ink bleeding is remarkable visually (impossible)

(Water resistance)
The printing medium after the above-mentioned inkjet printing was immersed in water at 23 ° C. for 24 hours, then taken out and the surface moisture was wiped off with a light cloth. Next, cellophane tape (trade name: cellophane tape (registered trademark) CT-18, manufactured by Nichiban Co., Ltd.) was attached to the printed surface, and the cellophane tape was quickly peeled off after being sufficiently adhered. Next, the water resistance and adhesion of the ink were evaluated on a 5-point scale based on the following criteria from the visual observation of the state of the printed surface after the tape was peeled off.
5: Ink does not peel off at all (good)
4: A small part of the ink peeled off (possible)
3: The peeled part was less than 25% (possible)
2: The peeled part was 25% or more and less than 50% (impossible)
1: The peeled part was 50% or more (impossible)

From Table 3 above, the printing media of Examples 1 to 12 have few surface streaks and are excellent in ink adhesion after being stored in a high temperature and high humidity environment when general printing using an ultraviolet curable ink is performed. It was a printing medium having excellent print quality and water-resistant adhesion after being stored in a high-temperature and high-humidity environment when inkjet recording was performed using an ultraviolet curable ink.
On the other hand, the printing medium of Comparative Example 1 containing no acidic pH adjuster (c) such as WO2014 / 087670 had many surface streaks. The printing medium of Comparative Example 2 that does not contain the ethyleneimine resin (b) has poor ink adhesion after being stored in a high temperature and high humidity environment when general printing is performed using an ultraviolet curable ink. It was. The printing medium of Comparative Example 3 that does not contain the cationic urethane resin (a) is inferior in print quality and water resistance after being stored in a high temperature and high humidity environment when performing inkjet recording using an ultraviolet curable ink. It was a thing. The printing medium of Comparative Example 4 produced by using a cationic polyolefin resin instead of the cationic urethane resin (a) and using a coating liquid having a blending ratio similar to that of JP-A-2002-113959 is an ultraviolet curable type. When inkjet recording using ink was performed, the print quality after storage in a high temperature and high humidity environment was inferior.
The following trends can be read from the relationships between the examples. Compared with the printing media of Examples 10 and 11 using the liquid acid pH adjuster (c) at 20 ° C. and 1 atm, the printing media of the other examples were particularly excellent in ink transfer property for general printing. Further, in Examples 4 and 7, in comparison with Example 3, an acidic pH adjuster (c) and a base can be used in combination so that the pH of the coating liquid does not become too low, especially with an inkjet. It shows that the print quality of the is improved. Further, in Examples 5 and 6, if the zeta potential of the cationic urethane resin (a) in the coating liquid is adjusted to 30 to 60 mV, ink adhesion and background stains in general printing can be improved, and printing in inkjet printing can be performed. It is shown to be effective in improving quality and water resistance.

The inclusion of the cationic polyurethane resin (a) and the ethyleneimine-based resin (b) in the printing media and the resin layer of each Example and Comparative Example can be confirmed by infrared absorption analysis (IR). The inclusion of the acidic pH adjuster (c) in the print media and the resin layer of each Example and Comparative Example can be confirmed by immersing the print medium in water and extracting the acidic pH adjuster (c).

The printing medium of the present invention has few surface streaks, is excellent in ink adhesion after being stored in a high temperature and high humidity environment when general printing is performed using an ultraviolet curable ink, and is an inkjet using an ultraviolet curable ink. It is a printing medium that is excellent in print quality and water resistance after being stored in a high temperature and high humidity environment when recording is performed. Therefore, it is suitable as a printing medium for applications requiring water resistance, a printing medium for labels, and a printing medium for on-demand.

Claims (8)

On the surface of at least one of the supports containing the thermoplastic resin as the main component,
It has a resin layer containing a cationic polyurethane resin (a), an ethyleneimine resin (b), and an acidic pH adjuster (c).
Including the acidic pH adjusting agent (c) is a divalent or more aliphatic carboxylic acids having a carbon number of 3-12, parametric toluenesulfonic acid, orthophosphoric acid, one or more acids or we selected metaphosphoric acid and polyphosphoric acid Print medium. The resin layer is, print medium of claim 1 which is 0.01g ^{/ m 2} ~5g ^/ m 2 as solids. The printing medium according to claim 1 or 2, wherein the acidic pH adjuster (c) contains an acid having a pKa of −0.2 to 6.8 as a free acid. The acidic pH adjuster (c) is selected from monovalent aliphatic carboxylic acids having 9 to 18 carbon atoms, divalent or higher aliphatic carboxylic acids having 3 to 12 carbon atoms, aromatic carboxylic acids, boric acids and phosphoric acids. The printing medium according to any one of claims 1 to 3, which contains one or more acids. The printing medium according to any one of claims 1 to 4, wherein the resin layer is a coating layer formed from a coating liquid. On the surface of at least one of the supports containing the thermoplastic resin as the main component,
A step of forming a resin layer by applying a coating liquid containing a cationic polyurethane resin (a), an ethyleneimine resin (b) and an acidic pH adjuster (c) is included.
Including the acidic pH adjusting agent (c) is a divalent or more aliphatic carboxylic acids having a carbon number of 3-12, parametric toluenesulfonic acid, orthophosphoric acid, one or more acids or we selected metaphosphoric acid and polyphosphoric acid A method for manufacturing a print medium. The method for producing a printing medium according to claim 6, wherein the pH of the coating liquid is 1.0 to 7.4. A printed matter having a cured product of an ultraviolet curable ink on the resin layer of the printing medium according to any one of claims 1 to 5.