WO2017110600A1

WO2017110600A1 - Printing medium, manufacturing method for printing medium, and printed matter

Info

Publication number: WO2017110600A1
Application number: PCT/JP2016/087131
Authority: WO
Inventors: 高広座間; 卓哉五十嵐
Original assignee: 株式会社ユポ・コーポレーション
Priority date: 2015-12-21
Filing date: 2016-12-14
Publication date: 2017-06-29

Abstract

Provided is a printing medium having a resin layer that contains an anionic polyurethane resin (a), a nonionic or anionic binder resin (b), and a basic pH adjusting agent (c) on at least one surface of a supporting body containing a thermoplastic resin as the main component, wherein the basic pH adjusting agent (c) contains a base having a pKa of 9.5-13.0 as a free base. The printing medium has few surface streaks, has an excellent ink transferability and ink adhesion after storage in a high-temperature, high-humidity environment when general printing is carried out using an ultraviolet-curable ink, and has an excellent water-resistant adhesion after storage in a high-temperature, high-humidity environment when inkjet recording is carried out using an ultraviolet-curable ink.

Description

Print medium, print medium manufacturing method and printed matter

The present invention relates to a printing medium, a printing medium manufacturing method, and a printed matter. Specifically, the present invention uses an anionic resin, has few surface streaks, and performs ink transfer and ink adhesion after storage in a high-temperature and high-humidity environment when performing general printing using an ultraviolet curable ink. The present invention relates to a printing medium having excellent water resistance and excellent water-resistant adhesion after being stored in a high-temperature and high-humidity environment when ink-jet recording is performed using an ultraviolet curable ink. 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 types of data are recorded on a printing medium using ink, and printed materials such as product quotations, price bills, and price tags may be created.
Conventionally, standard data such as background patterns and ruled line frames on the same print medium is recorded by general printing (plate printing) such as offset printing or seal printing using oxidative polymerization type ink or ultraviolet curable ink, Fine characters such as product names and prices, and variable data such as barcodes were recorded by an information recording method (printless printing) such as a thermal transfer recording method or an electrophotographic recording method.
Therefore, the print medium is required to have excellent printability in both general printing and information recording methods. For example, printing media used in the field of business form printing include ink transferability for recording variable data such as product names and barcodes in an information recording method in addition to printability for multicolor printing in normal printing. It is preferable that printability such as ink adhesion is also imparted.
As a method for improving the printability of a print medium, it is known to devise the composition of a resin layer provided on the surface of a support (see Patent Documents 1 to 3).

General printing media and label paper are given printing suitability and processing suitability such as surface strength and ink setting properties as necessary. Especially for paper used in the field of business form printing, in addition to the suitability for normal multicolor printing, the transferability and adhesion of ink and toner to record variable data such as product names and barcodes by the information recording method Suitability such as (fixing property) is also given.

JP 2002-113959 A WO2014 / 087670 JP 2011-116125 A JP 2002-080767 A

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

Regarding improvement in printability of a print medium, Patent Document 1 discloses that a primer layer coated with a water-soluble primer of a nitrogen-containing polymer compound absorbs moisture in a high-temperature and high-humidity environment. It has been pointed out that the ink transfer is hindered by the fact that it has the property and contains a large amount of moisture, and it becomes difficult to transfer the ink.
Further, Patent Document 1 discloses that a printing medium provided with a resin layer containing a nitrogen-containing polymer compound on the surface of a support has a moisture absorption of the resin layer that becomes an ink printing surface when left in a high temperature and high humidity environment for a long time. It has been pointed out that the ink is easily peeled off when the printed surface is peeled off with an adhesive tape in a high-temperature and high-humidity environment for a long time.
As described above, in general printing, it is required that the ink transfer property and the ink adhesion to the printing medium after being stored in a high temperature and high humidity environment are high.

On the other hand, the printability required for the information recording method differs depending on the recording method. 2. Description of the Related Art In recent years, inkjet printers, which are one of recording apparatuses used for information recording systems, have been improved in definition, high-speed printing, and low prices. Therefore, in recent years, there has been an increasing demand for recording variable data using an ink jet recording method among information recording methods. In such an ink jet recording system, water-resistant adhesion is required when the printed matter after printing is exposed to moisture. For example, Patent Documents 2 and 3 disclose ink jet recording paper using an aqueous cationic polyurethane resin.
In recent years, a method has been proposed for improving the water-resistant adhesion of an ink jet recording system by using an ultraviolet curable ink instead of a water-based ink. However, after storing in a high-temperature and high-humidity environment, the moisture absorption of the resin layer, which is the printed surface, increases as described above. There was a need to further improve the sex.

Here, in Patent Documents 1 to 3, a cationic resin is used for the coating layer of the printing medium. From the viewpoint of mastering materials suitable for various printing conditions, it has been required to use an anionic resin for the coating layer of the printing medium instead of the cationic resin. However, there have been few known examples in which an anionic resin is used for the coating layer of the printing medium and both the printing suitability for general printing and inkjet recording is compatible.
In the printing field, an anionic polyurethane resin may be used for an ink composition. For example, Patent Document 4 discloses that an aqueous compound having a carboxyl group neutralized with a basic compound and a group having an unsaturated double bond in the molecule is used as an active energy ray-curable component in the ink. In addition, it is described that an active energy ray-curable water-based ink composition for ink jet recording can be obtained which is excellent in abrasion resistance, water resistance and the like, has less odor and skin irritation, and has excellent ejection stability.

The problem to be solved by the present invention is that the ink transferability and ink after storage in a high-temperature and high-humidity environment when an anionic resin is used, surface printing is small, and general printing is performed using an ultraviolet curable ink It is an object of the present invention to provide a printing medium that has excellent adhesion and water resistance after storage in a high-temperature and high-humidity environment when inkjet recording is performed using an ultraviolet curable ink.

The present inventors have earnestly studied a print medium that achieves the above-mentioned object. As a result, an anionic polyurethane resin (a), a nonionic or anionic binder resin (b), and a basic pH adjuster (c) are contained on at least one surface of a support containing a thermoplastic resin as a main component. It has been found that having a resin layer can provide a print medium that can solve the above-mentioned problems, and the present invention has been completed.

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 at least one surface of a support containing a thermoplastic resin as a main component,
Having a resin layer containing an anionic polyurethane resin (a), a nonionic or anionic binder resin (b) and a basic pH adjuster (c);
A printing medium wherein the basic pH adjusting agent (c) contains a free base and a pKa of 9.5 to 13.0.
[2] In the printing medium according to [1], the resin layer preferably has a solid content of 0.01 g / m ² to 5 g / m ² .
[3] In the printing medium according to [1] or [2], the basic pH adjuster (c) is preferably in a gas state or a solid state at 20 ° C. and 1 atm.
[4] In the printing medium according to any one of [1] to [3], the basic pH adjuster (c) includes a base having a pKa of 9.9 to 13.0 as a free base. preferable.
[5] In the printing medium according to any one of [1] to [4], the basic pH adjuster (c) is an alkylamine having 1 or 2 carbon atoms, triethanolamine, and a side chain has carbon atoms. 1 selected from quaternary ammonium consisting of 1 to 4 alkyl groups or phenyl groups, tertiary sulfonium, hydroxide of secondary iodonium, guanidine, amino acids having an isoelectric point of 9.5 or more, polyvinylamine, and polyallylamine It is preferable to contain the above base.
[6] In the printing medium according to any one of [1] to [5], the resin layer is preferably a coating layer formed from a coating solution.
[7] On at least one surface of a support containing a thermoplastic resin as a main component,
A step of applying a coating liquid containing an anionic polyurethane resin (a), a nonionic or anionic binder resin (b) and a basic pH adjuster (c) to form a resin layer;
A method for producing a printing medium, wherein the basic pH adjusting agent (c) comprises a free base and a pKa of 9.5 to 13.0.
[8] In the method for producing a printing medium according to [7], it is preferable that the basic pH adjuster (c) contains a free base and a pKa of 9.9 to 13.0.
[9] In the method for producing a print medium according to [7] or [8], the pH of the coating liquid is preferably 6.5 to 13.0.
[10] 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, an anionic resin is used, there are few surface streaks, and excellent in ink transferability and ink adhesion after storage in a high temperature and high humidity environment when performing general printing using an ultraviolet curable ink. In addition, when ink jet recording using an ultraviolet curable ink is performed, it is possible to provide a printing medium having excellent water resistance adhesion after storage in a high temperature and high humidity environment.

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

[Print media]
The printing medium of the present invention has an anionic polyurethane resin (a), a nonionic or anionic binder resin (b) and a basic pH adjuster (on the surface of at least one surface of a support containing a thermoplastic resin as a main component. A printing medium having a resin layer containing c).
When the basic pH adjuster (c) contains a free base and a pKa of 9.5 to 13.0, the water-resistant adhesion after storage in a high-temperature and high-humidity environment when ink jet recording is performed. Excellent.
With such a configuration, the printing medium of the present invention uses an anionic resin, has few surface streaks, and performs ink transfer after storage in a high-temperature and high-humidity environment when performing general printing using an ultraviolet curable ink. In addition, it is excellent in water resistance and ink adhesion, and is excellent in water adhesion after storage in a high-temperature and high-humidity environment when ink jet recording using an ultraviolet curable ink is performed. The inclusion of an anionic polyurethane resin (a) in the resin layer is expected to contribute to the improvement of ink transferability after storage in a high temperature and high humidity environment when general printing using an ultraviolet curable ink is performed. . When the non-ionic or anionic binder resin (b) is contained in the resin layer, when the general printing using the ultraviolet curable ink is performed, the ink adhesion after storage in a high-temperature and high-humidity environment is improved. When ink jet recording using an ultraviolet curable ink is performed, it is expected to contribute to improvement of water-resistant adhesion after storage in a high temperature and high humidity environment. The inclusion of the basic pH adjuster (c) in the resin layer is expected to contribute to the improvement of surface stripes.
The print medium of the present invention is a print medium suitable for general printing methods such as offset printing and seal printing using ultraviolet curable ink and ink jet recording using ultraviolet curable ink. Note that the print medium of the present invention is preferably adapted to an information recording system such as a thermal transfer recording system, an electrophotographic system, and an ink jet recording system. Further, the printing medium of the present invention is suitable for various printing methods using ultraviolet curable ink, and is particularly preferably a printing medium having excellent printing quality in ink jet recording and excellent water resistance of printing and images. . Further, it is more preferable that the print medium has high print quality in terms of less ink bleeding in ink jet recording.
The print medium is preferably printing paper. However, the printing medium may be other than printing paper (for example, a poster, calendar, map, tag, label, sticker, etc.).
Hereinafter, details of preferred embodiments of the print medium of the present invention will be described.

<Support>
The support includes a thermoplastic resin as a main component. When the support includes a thermoplastic resin as a main component, the water-resistant adhesion of the printed material can be improved. The main component of the support means 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, more preferably 80% by mass or more of the thermoplastic resin.

(Thermoplastic resin)
The kind of thermoplastic resin used for the support is not particularly limited. For example, polyolefin resins such as ethylene resins such as high density polyethylene and medium density polyethylene, propylene resins, polymethyl-1-pentene, and ethylene-cycloolefin copolymers; polyamides such as nylon-6 and nylon-6,6 Resin: Polyethylene terephthalate and its copolymer, Polyethylene naphthalate, Polybutylene terephthalate, Polybutylene succinate, Polyester of aliphatic polyester such as polylactic acid; Polycarbonate, Atactic polystyrene, Syndiotactic polystyrene, etc. These thermoplastic resins can be mentioned. Of these, from the viewpoint of water adhesion, chemical resistance and cost, it is preferable to use a polyolefin resin or a polyester resin, and it is more preferable to use a polyolefin resin.

Among polyolefin-based resins, it is preferable to use a propylene-based resin from the viewpoint of easily imparting appropriate stiffness to the printing medium. Propylene resins include propylene homopolymers and copolymers of propylene as a main component and α-olefins such as ethylene, 1-butene, 1-hexene, 1-heptene, 4-methyl-1-pentene. Can be used. The stereoregularity is not particularly limited, and isotactic or syndiotactic and those showing various degrees of stereoregularity can be used. The copolymer may be a binary system or a ternary or higher multi-element system, and may be a random copolymer or a block copolymer. The propylene resin is preferably used by blending 2 to 25% by mass of a resin having a melting point lower than that of the propylene homopolymer. Examples of such a resin having a low melting point include high-density or low-density polyethylene.

As the thermoplastic resin used for the support, one of the above thermoplastic resins may be selected and used alone, or two or more may be selected and used in combination. If necessary, an inorganic fine powder, an organic filler, a heat stabilizer (antioxidant), a light stabilizer, a dispersant, a lubricant and the like can be added to the thermoplastic resin used for the support.

(Inorganic fine powder)
The support may include an inorganic fine powder. When the support contains an inorganic fine powder, the support can be whitened, opaque, and further concealed, making it easy to visually recognize printing as a print medium, 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. Moreover, the surface treatment goods by the various surface treatment agent of the said inorganic fine powder can also be illustrated. Among these, heavy calcium carbonate, precipitated calcium carbonate and their surface-treated products, clay, and diatomaceous earth are preferable because they are inexpensive and have good pore forming properties during stretching.

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

Examples of the fatty acid 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, eleostearic acid. An acid etc. are mentioned. 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 a polyethylene glycol ester type surfactant. 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 surface treatment methods for inorganic fine powders using these surface treatment agents include, for example, JP-A-5-43815, JP-A-5-139728, JP-A-7-300568, and JP-A-10-176079. 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. Can be used.

(Organic filler)
The support may contain an organic filler. Even when the support includes an organic filler, the support can be whitened and opaque, and printing can be easily viewed as a printing medium.
As a specific example of the organic filler, a resin having a melting point or glass transition point higher than that of the main thermoplastic resin constituting the support (eg, 120 to 300 ° C.) can be preferably used. For example, as the organic filler when a propylene resin is used as the main thermoplastic resin constituting the support, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyamide, polycarbonate, polystyrene, cyclic olefin homopolymer, ethylene- Examples thereof include cyclic olefin copolymers, polyethylene sulfide, polyimide, polymethacrylate, polyethyl ether ketone, polyphenylene sulfide, and melamine resin. These have a higher melting point or glass transition temperature than the propylene resin, which is the main thermoplastic resin constituting the support, and are incompatible with the propylene resin. Is preferable because it is good.

For the support, one kind selected from inorganic fine powder or organic filler may be used alone, or two or more kinds may be selected and used in combination. When using in combination of 2 or more types, you may mix and use an inorganic fine powder and an organic filler.
When an inorganic fine powder or an organic filler is used for the support, the support preferably contains 5 to 75% by mass, more preferably 8 to 65% by mass of the fine powder or filler. More preferably, 55% by mass is contained. If the content of these in the support is 5% by mass or more, the desired pores are easily obtained and the printing medium tends to be opaque. Conversely, if it is 75 mass% or less, there exists a tendency for the intensity | strength of a support body to fall easily.

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. More preferably, it is in the range of 1 to 1.3 μm.
If a fine powder or filler having an average particle diameter or an average dispersed particle diameter of 0.05 μm or more is used, pores are likely to be obtained by stretch molding, and the printing medium tends to be opaque. 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 cumulative values measured by a particle measuring device such as a laser diffraction particle measuring device “Microtrack” (trade name, manufactured by Microtrack Bell Co., Ltd.). 50% particle diameter (cumulative 50% particle diameter), observation of primary particle diameter with a scanning electron microscope (in the present invention, the average value of 100 particles is an average particle diameter), conversion from specific surface area (the present invention Then, the specific surface area was measured using a powder specific surface area measuring device SS-100 manufactured by Shimadzu Corporation).

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

(Method for forming support)
The method for forming the support is not particularly limited. The support can be molded by appropriately selecting from various known methods. For example, cast molding, calender molding, rolling molding, inflation molding, thermoplasticity that extrudes a molten thermoplastic resin composition into a sheet using a single-layer or multilayer T-die or I-die connected to a screw-type extruder A mixture of a resin, an organic solvent, and an oil can be cast or calendered and then molded using a method of removing the solvent or oil. Moreover, the molten thermoplastic resin composition can also be extruded and laminated on the base material of paper or a thermoplastic resin film.
The support (particularly the thermoplastic resin film layer on the support surface) may be unstretched or stretched. Stretching can be performed by any of a variety of commonly used methods. Specific examples include longitudinal stretching using the difference in peripheral speed between rolls, 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 do.

In the case of an amorphous resin, the stretching temperature is higher than the glass transition temperature of the thermoplastic resin used, and in the case of a crystalline resin, the thermoplasticity is higher than the glass transition temperature of the amorphous portion to the melting point of the crystalline portion. It can be performed 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 to be used. When the resin is a propylene homopolymer (melting point 155 to 167 ° C.), 152 to 164 ° C., high density polyethylene ( When the melting point is 121 to 134 ° C., it is preferably 110 to 120 ° C., and when polyethylene terephthalate (melting point 246 to 252 ° C.) is used, it is preferably 104 to 115 ° C. The stretching speed is preferably 20 to 350 m / min.

The stretching ratio at the time of the 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 biaxially stretched. The area magnification is 1.5 to 60 times, preferably 10 to 50 times. When using other thermoplastic resins, it is 1.2 to 10 times, preferably 2 to 5 times when stretched in one direction, and 1.5 to 20 times in area magnification when biaxially stretched. Preferably 4 to 12 times.

(Structure of support)
The support may be a single layer or a layered structure.
An example is shown about the manufacturing method of a single layer support. For example, a single-layer support including a polyolefin resin film includes a resin film comprising a resin composition containing 40 to 99.5% by mass of a polyolefin resin and 60 to 0.5% by mass of an inorganic fine powder. It can be prepared by stretching in a uniaxial or biaxial direction at a temperature lower than the melting point of the resin (preferably a temperature lower by 3 to 60 ° C.).
An example is shown about the manufacturing method of the support body which has a laminated structure. For example, a support having a laminated structure of layers containing a polyolefin resin film is a resin film comprising a resin composition containing 40 to 100% by mass of a polyolefin resin and 60 to 0% by mass of an inorganic fine powder. Stretched in the machine direction at a temperature lower than the melting point of the resin (preferably a temperature lower by 3 to 60 ° C.), and contains 25 to 100% by mass of polyolefin resin and 75 to 0% by mass of inorganic fine powder on at least one side of the stretched film. It can prepare by laminating | stacking the resin film which consists of a resin composition to do. Further, the laminated film may be stretched in the transverse direction at a temperature lower than the melting point of the polyolefin resin (preferably a temperature lower by 3 to 60 ° C.), and the resin layer laminated on the stretched film may be stretched in the transverse direction. Good.
Moreover, the example of the support body which has a polyolefin resin film on both surfaces of natural pulp paper is shown. Beating hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), or a mixture thereof, and papermaking a slurry containing a dry paper strength enhancer, wet paper strength enhancer, sizing agent, filler, etc. Paper having an amount of 50 to 200 g / m ² and a density adjusted to 0.90 to 1.15 g / cm ³ can be used as a base material. 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 the base material to form a support, or a support having the above single-layer structure or laminated structure. It is good also as a support body by bonding the resin film demonstrated as a body.

(Physical properties of the support)
For the purpose of use as a printing medium, the support preferably has a thickness 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.
The support (particularly the thermoplastic resin film layer on the support surface) may be stretched as described above. If a thermoplastic resin film containing an inorganic fine powder or an organic filler is stretched, a stretched porous resin film having a large number of fine pores inside can be obtained. Such a stretched porous resin film is suitable as a support for a printing medium from the viewpoints of lightness and opacity. 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 porosity measured by the following method in the range of 5 to 60%, more preferably in the range of 10 to 50%.
The porosity of each layer of the support is cut while cooling so as not to crush the holes of the support, creating a cross section in the thickness direction (observation surface), pasting it on the observation sample stage, and applying gold to the observation surface Evaporate and observe the vacancies in each layer at an arbitrary magnification that is easy to observe using a scanning electron microscope, capture the observed area as image data, and image-process the image to determine the vacancy area ratio. This is determined as the porosity.

Further, the physical properties of the stretched support are preferably 50% or more, more preferably 60% or more. If the opacity of the support is 50% or more, printing is easy to see when used as a printing medium, and when used as label paper, barcode printing is affected by the background and reading errors occur. There is almost no fear. Similarly, the stretched support preferably has a whiteness of 80% or more, more preferably 90% or more. Such whiteness can contribute to the sharpness of the printed matter.

(Surface oxidation treatment of support)
Before forming the resin layer on the surface of the above support, corona discharge treatment, flame 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, corona discharge treatment and flame treatment are preferable, and corona discharge treatment is more preferable. In the case of corona discharge treatment, the treatment amount is preferably 600 to 12,000 J / m ² (10 to 200 W · min / m ² ), and 1,200 to 10,800 J / m ² (20 to 180 W · min). / M ² ) is more preferable. In the case of frame processing, it is preferably performed at 8,000 to 200,000 J / m ² , and more preferably at 20,000 to 100,000 J / m ² .

<Resin layer>
The resin layer used in the present invention is located on at least one surface of the support and contains an anionic polyurethane resin (a), a nonionic or anionic binder resin (b), and a basic 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 only on one surface of the support, or may have the resin layer on both surfaces of the support.

(Anionic polyurethane resin (a))
By using the anionic polyurethane resin (a) for the resin layer, it is possible to contribute to improvement of water resistance after storage in a high-temperature and high-humidity environment when ink-jet recording using an ultraviolet curable ink is performed. it can. Although this mechanism is unclear, this effect can be read from a comparison of examples, reference examples, and comparative examples described later. Note that the improvement in print quality and water-resistant adhesion after storage in a high-temperature and high-humidity environment is expected to have a correlation with the balance of hydrophilicity and hydrophobicity of the urethane resin.
The anionic polyurethane resin (a) used for the resin layer can form a coating layer having excellent adhesion to the support. In addition, the anionic polyurethane resin (a) can form a coating layer rich in elasticity due to urethane bonds, and can improve ink adhesion by following volume shrinkage at the time of curing of ultraviolet curable ink. .
Moreover, since anionic polyurethane resin (a) is anionic, it is rich in miscibility with nonionic or anionic binder resin (b). Therefore, the anionic polyurethane resin (a) and the nonionic or anionic binder resin (b) are less likely to aggregate in the resin layer having the configuration of the present invention, and surface streaking before printing is less likely to occur.
The anionic polyurethane resin (a) in the present invention is an anionic group (for example, a carboxyl group, a sulfonic acid group and a salt thereof) in the main chain and / or side chain of a urethane resin based on a polyol and a polyisocyanate compound. It means a urethane resin having a functional group or the like.

Here, examples of the “polyol” used for forming the anionic polyurethane resin (a) include polyester polyol, polyether polyol, polycarbonate polyol, polybutadiene polyol, polyolefin polyol, polyacrylate polyol and castor oil derivative. .

Examples of the “polyester polyol” include polyethylene adipate, polybutylene adipate, polyethylene butylene adipate, polyhexamethylene isophthalate adipate, polyethylene succinate, polybutylene succinate, polyethylene sebacate, polybutylene sebacate, poly-ε- Caprolactone diol, poly-3-methylpentane adipate, 1,6-hexanediol and dimer acid polycondensate, 1,6-hexanediol, adipic acid and dimer acid copolycondensate, nonanediol and dimer acid polycondensate Examples include condensates, polycondensates of ethylene glycol and dimer acid, and copolycondensates of ethylene glycol, adipic acid and dimer acid.
Examples of the “polyether polyol” include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, random copolymer and block copolymer of ethylene oxide and propylene oxide, random copolymer and block of ethylene oxide and butylene oxide A copolymer can be illustrated.
Examples of the “polycarbonate polyol” include polytetramethylene carbonate diol, polyhexamethylene carbonate diol, poly-1,4-cyclohexane dimethylene carbonate diol, and polyhexamethylene-1,4-cyclohexane dimethylene carbonate diol.
Examples of the “polybutadiene polyol” include a polyol composed of a homopolymer having a polybutadiene skeleton (1,2 adduct and 1,4 adduct), a polyol composed of a polybutadiene copolymer obtained by polymerizing butadiene, styrene and acrylonitrile, and the like. Examples of the hydrogenated product can be given.
Examples of the “polyolefin polyol” include a polyhydroxy polymer.
As the “polyacrylate ester polyol”, for example, an acrylic polyol obtained by copolymerizing an acrylic monomer such as hydroxyethyl methacrylate (HEMA) with an acrylic ester, methacrylic ester, styrene or the like, a polyacrylic ester polyol, and Examples thereof include polymethacrylate polyols.
Examples of the “castor oil derivative” include refined castor oil, dehydrated castor oil, polymerized dehydrated castor oil, and castor oil polyol.
These polyols can be used alone or in combination.

Examples of the “polyisocyanate compound” used for forming the anionic polyurethane resin (a) include aliphatic diisocyanate compounds such as ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 1,6-hexamethylene diisocyanate. Hydrogenated 4,4′-diphenylmethane diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, isophorone diisocyanate, norbornane diisocyanate, etc., 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, toluene Examples thereof include aromatic diisocyanates such as diisocyanate and naphthalene diisocyanate.
These polyisocyanate compounds can be used alone or in combination.

In order to obtain the anionic urethane resin (a), it is preferable to use a compound having two or more functional groups having active hydrogen capable of reacting with the isocyanate group of the isocyanate compound and having an anionic group.
Examples of anionic groups include functional groups in the form of carboxyl groups, sulfonic acid groups, and salts thereof.
Examples of the “compound having an anionic group” include 3,4-diaminobutanesulfonic acid, 3,6-diamino-2-toluenesulfonic acid, 2,6-diaminobenzenesulfonic acid, N- (2-aminoethyl)- Examples include sulfonic acid group-containing compounds such as 2-aminoethylsulfonic acid, and carboxyl group-containing compounds such as 2,2-dimethylollactic acid, 2,2-dimethylolpropionic acid, and 2,2-dimethylolvaleric acid.
The compounds having an anionic group can be used alone or in combination.

The “anionic polyurethane resin emulsion” is a combination of the above-mentioned polyol, polyisocyanate compound and compound having an anionic group as appropriate, using other monomers, a chain extender, a catalyst, etc. as necessary, using conventional methods. Obtainable. For example, the anionic urethane resin (a) can be synthesized by reacting the above-mentioned polyol, polyisocyanate compound and compound having an anion group in the presence of a hydrophilic volatile solvent such as acetone, methyl ethyl ketone, isopropanol and the like. .

Furthermore, the anionic polyurethane resin (a) preferably has an emulsion form. An anionic polyurethane resin (a) is an aqueous medium from the viewpoint of facilitating coating when the coating liquid described later is prepared, reducing surface streaks before printing, and enhancing the water-resistant adhesion of the obtained resin layer. More preferably, it is in the form of an emulsion dispersed therein and is not redissolved after drying. Further, from the viewpoint of enhancing the transparency of the resin layer, the average particle diameter of the anionic polyurethane resin (a) emulsion can be, for example, 0.01 to 1 μm, and preferably 0.05 to 0.5 μm. The average dispersed particle size of the emulsion is 50% of the cumulative particle size measured by a particle measuring device such as a laser diffraction particle measuring device “Microtrack” (trade name, manufactured by Microtrack Bell Co., Ltd.). Diameter), observation of primary particle diameter with a scanning electron microscope (for example, average value of 100 particles), conversion from specific surface area (for example, a powder specific surface area measuring device SS-100 manufactured by Shimadzu Corporation) The specific surface area can be measured).
From the anionic urethane resin (a), an emulsion of the anionic 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.
As an emulsion of an anionic polyurethane resin (a), for example, Hydran AP20 (trade name, Hydran is a registered trademark), which is a sulfonic acid group-containing anionic polyurethane resin aqueous dispersion manufactured by Dainippon Ink and Chemicals, Inc. Hydran AP40F (trade name) which is an aqueous dispersion of anionic polyurethane resin containing carboxylic acid groups, manufactured by Dainippon Ink & Chemicals, Inc., Superflex 150 (tradename) and Superflex 500M from Daiichi Kogyo Seiyaku Co., Ltd. Upren UXA3004 (trade name) and Uprene UXA3005 (trade name) manufactured by Sanyo Chemical Industries, Ltd. are commercially available and can be used in the present invention.

(Nonionic or anionic binder resin (b))
Since the nonionic or anionic binder resin (b) used in the resin layer has a strong affinity with the ultraviolet curable ink, the ink adhesion with the ultraviolet curable ink can be improved.
In addition, the nonionic or anionic binder resin (b) used for the resin layer improves water adhesion after storage in a high-temperature and high-humidity environment when inkjet recording is performed using an ultraviolet curable ink. Can contribute. Although this mechanism is unclear, this effect can be read from a comparison of examples, reference examples, and comparative examples described later.
The nonionic or anionic binder resin (b) used for the resin layer is preferably capable of enhancing the adhesion to various supports.
Specific examples of the nonionic or anionic binder resin (b) include acid-modified polyolefin resins, acid-modified ethylene / acrylic acid copolymers, acid-modified ethylene / ethyl acrylate copolymers, acid-modified LLDPE (Linear). Low density Polyethylene; acid-modified VLDPE (Very Low Density Polyethylene), ethylene / vinyl acetate copolymer, polyvinyl alcohol, polyvinyl acetal, butadiene, styrene / butadiene copolymer, Examples thereof include an isobutylene / maleic anhydride copolymer, a carboxylic acid-modified polyester, a hydroxyl group-modified polyolefin resin, and a hydroxyl group-modified polyester resin. These can be used in the form of an emulsion or an aqueous solution, and can be used alone or in combination.
Among these, anionic binder resins are preferable, and acid-modified polyolefin resins, acid-modified ethylene / acrylic acid copolymers, acid-modified ethylene / ethyl acrylate copolymers, acid-modified LLDPE, and acid-modified VLDPE are more preferable. A modified polyolefin resin is particularly preferred.
Examples of such nonionic or anionic binder resin (b) include EL-452 (trade name) manufactured by Toyo Morton Co., Ltd., A-3804 (trade name) manufactured by Asahi Kasei Latex, and Kuraray Co., Ltd. PVA-117 (trade name) and Isovan-04 (trade name), Arrow Base SB-1010 and Arrow Base SB-1030 (trade name) manufactured by Unitika Ltd. are commercially available and can be used. .

(Basic pH adjuster (c))
The anionic polyurethane resin (a) suitably used in the present invention is designed to have high water resistance after drying, and has a property of being easily aggregated in a solution because it is an emulsion having a small average particle size. . Generally, when the absolute value of the surface potential (zeta potential) of nano-sized particles is 20 mV or more, the electric double layer is hardly broken and the dispersibility of the particles is good. In the present invention, the zeta potential of the anionic polyurethane resin (a) is preferably set to −20 mV or less in the state where the basic pH adjuster (c) is added to the aqueous dispersion of the anionic polyurethane resin (a). More preferably, it is −30 mV or less. Thereby, the dispersibility of an anionic polyurethane resin improves, and it becomes difficult to aggregate when mixing with a nonionic or anionic binder resin (b), and the coating liquid which is hard to aggregate and thicken is obtained. As a result, coating is facilitated, and there is a tendency to obtain the resin layer with less foreign matter and less surface stripes before printing. On the other hand, the zeta potential of the anionic polyurethane resin is preferably −70 mV or more, and more preferably −60 mV or more. Thereby, there exists a tendency which can improve the water-resistant adhesiveness of the said resin layer, or can reduce the bad influence by addition of a basic pH adjuster (c) or an anionic polyurethane resin (a).
In order to make the zeta potential of the anionic polyurethane resin in the state of the coating liquid within the above range, the basic pH adjuster (c) needs to be basic. The basic pH adjuster (c) preferably has a pKa as a free base of 7.5 to 13.0, more preferably 8.0 to 13.0, and preferably 9.5 to 13. It is particularly preferably 0, more particularly preferably 9.9 to 13.0, and even more particularly preferably 9.9 to 12.0.
The pH in the state of the coating solution is preferably 6.5 to 13.0, more preferably 6.5 to 10.5, and particularly preferably 7.5 to 9.5. 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 anionic polyurethane resin (a) in the state of the coating liquid is decreased (the absolute value of the zeta potential is increased) and controlled to a preferable range. And the anionic polyurethane resin (a) is less likely to aggregate. When using a base having a high pKa as the free base, the pH in the state of the coating solution can be adjusted to the above range by adding an acid. Usable acids include hydrochloric acid, sulfuric acid, carbonic acid, acetic acid and the like.
Further, if the basic pH adjuster (c) is in a solid state or a gas state under normal use conditions, the basic pH adjuster (c) moves in the resin layer and oozes out on the surface of the resin layer. Inferior transfer of printing ink due to migration (migration) is unlikely to occur. In particular, the tendency for migration to hardly occur in plate printing is remarkable. Further, if migration is difficult to occur, it tends to be difficult to repel inkjet ink. The basic pH adjuster (c) is preferably in a gas state or a solid state at 20 ° C. and 1 atmosphere, more preferably in a gas state or a solid state at 40 ° C. and 1 atmosphere, and at 60 ° C. and 1 atmosphere. A gas state or a solid state is particularly preferable. Accordingly, the basic pH adjuster (c) is a solid under normal use conditions, and migration with time can be prevented, so that there is a tendency not to inhibit the ink transferability after long-term storage of the print medium. When the basic pH adjuster (c) is a gas under normal use conditions, the concentration in the coating layer after drying is preferably 100 ppm or less in order to prevent migration over time, and is 50 ppm or less. More preferably, it is more preferably 30 ppm or less.
Further, among basic pH adjusters (c) that are in a solid state at 20 ° C. and 1 atm, those having no deliquescence are more preferable.

In the printing medium of the present invention, the basic pH adjuster (c) is composed of ammonia, an alkylamine having 1 or 2 carbon atoms, diethanolamine, triethanolamine, a side chain having 4 to 4 carbon atoms or a phenyl group. It preferably contains one or more bases selected from tertiary ammonium, tertiary sulfonium, secondary iodonium hydroxide, guanidine, amino acids having an isoelectric point of 7.5 or more, polyvinylamine, and polyallylamine.
In the printing medium of the present invention, the basic pH adjuster (c) is an alkylamine having 1 or 2 carbon atoms, triethanolamine, a quaternary ammonium whose side chain is an alkyl group having 1 to 4 carbon atoms or a phenyl group, It is more preferable to include one or more bases selected from tertiary sulfonium, secondary iodonium hydroxide, guanidine, amino acids having an isoelectric point of 9.5 or more, polyvinylamine, and polyallylamine.
Examples of the basic pH adjuster (c) that is in a gaseous state at 20 ° C. and 1 atm include ammonia, alkylamines having 1 or 2 carbon atoms, and diethanolamine. Among these, ammonia is preferable. Of these, alkylamines having 1 or 2 carbon atoms are also preferred.
In addition, as a basic pH adjuster (c) that is in a solid state at 20 ° C. and 1 atm, triethanolamine, quaternary ammonium, tertiary sulfonium whose side chain is an alkyl group having 1 to 4 carbon atoms or a phenyl group, Examples include secondary iodonium hydroxide, guanidine, amino acids having an isoelectric point of 7.5 or more, polyvinylamine, and polyallylamine. As an amino acid having an isoelectric point of 7.5 or more, an amino acid having an isoelectric point of 9.5 or more is preferable. Among these, tetraethylammonium hydroxide, guanidine, polyvinylamine, polyallylamine, and those obtained by neutralizing some of them with acid, arginine, histidine, and lysine are preferable.

(Mixing amount ratio)
The blending ratio of each component in the resin layer as a solid content after drying is 1 to 40 parts by mass of the nonionic or anionic binder resin (b) with respect to 100 parts by mass of the anionic polyurethane resin (a). It is preferable to include 10 to 20 parts by mass.
Further, in order to adjust the pH to the above range, the basic pH adjuster (c) is preferably contained in an amount of 0.01 to 5 parts by mass with respect to 100 parts by mass of the anionic polyurethane resin (a). It is more preferable to include 3 parts by mass. Thus, it is more preferable to apply the coating liquid by adjusting the pH of the coating liquid to the above-mentioned preferable range.
When the amount ratio of each component in the resin layer is within this range, high printing quality and water-resistant 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 with a crosslinking 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 a range.

-Crosslinking agent (d)-
The coating layer of the present invention may contain a crosslinking agent (d). From the viewpoint of further improving the water-resistant adhesion of the resin layer, the crosslinking agent (d) is preferably a substance that crosslinks by reacting with the nonionic or anionic binder resin (b). Moreover, since the coating material which comprises the said resin layer is provided with the form of aqueous solution or aqueous dispersion, it is preferable that a crosslinking agent (d) is a water-soluble substance. In order to give flexibility to the resin layer, the cross-linking agent (d) is preferably a bifunctional substance or a polymer substance. On the other hand, it is preferable that the crosslinking agent (d) is a trimolecular or higher functional low molecular substance in order to give the resin layer water resistance adhesion and wear resistance. A bifunctional substance and a trifunctional or higher functional substance may be used in combination as the crosslinking agent (d).
Examples of the crosslinking agent (d) include epoxy-based, carbodiimide-based, isocyanate-based, formalin-based, and oxazoline-based crosslinking agents. Among these, an epoxy system, a carbodiimide system, and an oxazoline system are preferable. Among them, diglycidyl ether compounds and carbodiimide compounds, which are epoxy crosslinking agents, are particularly preferable because they are polyfunctional and provide a highly flexible coating film and are water-soluble.
The crosslinking agent (d) is preferably contained in an amount of 3 to 20 parts by mass, more preferably 10 to 20 parts by mass, based on 100 parts by mass of the anionic polyurethane resin (a) as a solid content.

(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 troubles due to dust adhering to the print medium and static electricity during printing and printing. The antistatic agent (e) is preferably a polymer-type antistatic agent that oozes out on the surface of the resin layer under long-term storage and hardly causes a decrease in ink adhesion. As the antistatic agent (e), anion type, amphoteric type, nonionic type and the like can be used. Anionic types include alkali metal salts such as sulfonic acid, phosphoric acid and carboxylic acid, for example, alkali metal salts such as fatty acid having 1 to 12 carbon atoms, acrylic acid, methacrylic acid and (anhydrous) maleic acid (lithium salt, sodium salt). Salt, potassium salt, etc.) having a structure in the molecular structure. The amphoteric type contains both the cation type and the anion type structures in the same molecule, and examples thereof include a betaine type. Nonionic types include fatty acid amides, ethylene oxide polymers having an alkylene oxide structure, and polymers having an ethylene oxide polymerization component in the molecular chain. In addition, a polymer type antistatic agent having boron in the molecular structure can be given as an example. Among these, polyoxyalkylene ether phosphates that are anionic and polymer are preferable, and tertiary nitrogen or quaternary nitrogen-containing acrylic resins are more preferable.

(Solvent and solid concentration)
The resin layer is preferably a coating layer formed by coating a coating solution. Since the coating liquid for forming the coating layer is easy to manage the process, the above components are homogeneous 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 use it as a solution or dispersion by dissolving or dispersing in the solution. Among these, 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 compatible with water as a cosolvent.
0.1 mass% or more is preferable and, as for the solid content concentration in the coating liquid which forms a resin layer, 0.2 mass% or more is more preferable. 20 mass% or less is preferable and, as for the solid content concentration in the coating liquid which forms a resin layer, 10 mass% or less is more preferable.

(Solid content)
In the printing medium of the present invention, the resin layer preferably has a solid content of 0.01 g / m ² to 7 g / m ² , more preferably 0.01 g / m ² to 5 g / m ² , 0.05 g / m ² to 3 g / m ² is particularly preferable. The solid content of the resin layer in this specification means the solid content after drying per one side. In order to practically express the adhesiveness of the ultraviolet curable ink, it is preferable that the solid content (coating amount) of the resin layer is not less than the lower limit of the preferred range. The solid content (coating amount) of the resin layer is preferably not more than the upper limit of the preferred range from the viewpoint of preventing the adhesion due to cohesive failure of the resin layer and reducing the material cost.

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

[Method of manufacturing print medium]
The method for producing a printing medium of the present invention comprises an anionic polyurethane resin (a), a nonionic or anionic binder resin (b) and a basic pH on at least one surface of a support containing a thermoplastic resin as a main component. It includes a step of forming a resin layer by coating (also referred to as coating) a coating liquid containing the adjusting agent (c). When the basic pH adjuster (c) contains a free base and a pKa of 9.5 to 13.0, the water-resistant adhesion after storage in a high-temperature and high-humidity environment when ink jet recording is performed. Excellent.
That is, in the printing medium of the present invention, the resin layer is preferably a coating layer formed from a coating liquid. According to the addition of pH, zeta potential and basic pH adjuster (c) in the state of the coating liquid, the state of the surface streaks before printing of the printing medium differs, so it is technical to specify the structure of the resin layer Implicating work that is impossible or specific in nature. Further, when a crosslinking agent is added to the coating solution, it is technically impossible to specify the structure in which the resin component crosslinks, or it involves an operation that is almost impractical to specify. Therefore, it is also preferable that one of the preferred embodiments of the print medium of the present invention is described in a product-by-process claim.

(Coating)
In the coating step, a coating liquid containing an anionic polyurethane resin (a), a nonionic or anionic binder resin (b) and a basic pH adjuster (c) is applied to at least one surface of the support. Thus, a resin layer is formed.
In the method for producing a printing medium of the present invention, the anionic polyurethane resin (a) in the state of the coating liquid preferably has a zeta potential of −70 mV to −20 mV. In the method for producing a printing medium of the present invention, the pH of the coating liquid is preferably 6.5 to 13.0, and more preferably 6.5 to 10.5. More preferable ranges of the zeta potential of the anionic polyurethane resin (a) in the state of the coating liquid and the pH of the coating liquid in the method for producing a printing medium of the present invention are described in the description of the printing medium of the present invention. This is the same as the preferred range.

The resin layer is preferably formed by applying a coating solution 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 solution on both surfaces of the support.
The coating process may be performed in combination with support molding in a support molding line, or may be performed in a separate line using an already molded support. When the support is formed by a stretching method, the coating may be performed before the stretching step or may be performed after the stretching step.
You may remove an excess solvent through the drying process using oven etc. before or after the coating process as needed.
A general coating apparatus can be used to apply the coating liquid to the support. The solid content after drying (coating amount), the viscosity of the coating liquid, and the solids of the chemical in the coating liquid It chooses suitably according to a partial concentration etc. Examples of the coating apparatus 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, in a preferred embodiment of the blending ratio of the anionic polyurethane resin (a), the nonionic or anionic binder resin (b) and the basic pH adjuster (c), a roll coater, a bar coater, a size press coater, a gravure It is preferable to use a coater or a spray coater, and it is more preferable to use a roll coater, a size press coater, or a gravure coater.

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

<UV curable ink>
For printing, a solution or dispersion containing an arbitrary colorant can be used. A solution or dispersion containing a colorant is referred to as “ink” or “ink”. In general, “ink” is used for plate printing performed using a plate, and “ink” is used for plateless printing such as printer output without using a plate. In this specification, “ink” and “ink” will be described as “ink” without any 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 ultraviolet curable ink, the ultraviolet curable ink is solidified by ultraviolet irradiation. The ultraviolet irradiation method is not particularly limited as long as the ultraviolet curable ink is cured. 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), a black light (350 ~ 360nm), the ultraviolet rays irradiated from UV-LED lamp (355 ~ 375nm), 300 ~ 3000mJ / cm 2, is preferably exemplified by irradiating such that the dose of 400 ~ 1000mJ / cm ² .
The ultraviolet curable ink is not particularly limited, and a known ultraviolet curable ink can be used. The ultraviolet curable ink preferably includes at least a diluent, a compound having a bifunctional or higher functional radical polymerizable group, and a colorant.
As materials used for the ultraviolet curable ink, materials described in [0016] to [0097] of JP-T-2004-526016 (particularly aliphatic urethane acrylate), and [0010] to [0010] of JP-A-2002-080767 are disclosed. Materials described in [0062] (especially anionic aqueous polyurethane compounds), materials described in JP-A-2010-530922 [0004] to [0026] (especially chlorinated polyolefin excellent in adhesion to polyolefin film) Etc. can be preferably used. The contents of these publications are incorporated herein by reference.
As the ultraviolet curable ink, an ink further containing acryloylmorpholine as a diluent can be preferably used.

In inkjet recording using ultraviolet curable ink, if ink droplets flow between the time when ink droplets land on the outermost layer of the print medium and solidify by ultraviolet irradiation, the image blurs or the line drawing becomes thicker. The print quality (image quality) is affected.
From the viewpoint of improving the printing quality of ink jet recording using ultraviolet curable ink, it is preferable that the pH of the coating liquid for forming the resin layer is 3.0 or more. If 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 preferred coating liquid, the ink droplets are deformed so that the ink droplets are repelled and the line drawing is less likely to fade. Since the pigment in the inside is less likely to aggregate to form a metallic gloss film, the print quality can be improved.

The present invention will be described more specifically with reference to the following examples. The following materials, amounts used, ratios, processing details, processing procedures, and the like can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the examples shown below. Unless otherwise specified, “part” 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%”.

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

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

(3) Next, after cooling this three-layer laminated film to a temperature of 60 ° C., it was again heated to a temperature of 155 ° C., stretched 7.5 times in the transverse direction using a tenter, and 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.
In the obtained laminated stretched film having a three-layer structure, the number of stretching axes of each layer (B layer / A layer / B layer) is uniaxial stretching / biaxial stretching / uniaxial stretching, and the thickness is 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 treater roll on one surface of a laminated stretched film having a three-layer structure. Using a roll, the gap between the discharge electrode and the treater roll was 5 mm, and a corona discharge treatment was performed at a line treatment speed of 15 m / min and an applied energy density of 4,200 J / m ² . The obtained support was used as the support in Production Example 1. In addition, the support body of the manufacture example 1 contains a thermoplastic resin as a main component.

[Production Example 2]
The support of Production Example 2 was produced by the following method.
The same corona discharge treatment as in Production Example 1 was performed on one side of a commercially available polyester film (trade name “Lumirror E20”, manufactured by Toray Industries, Inc., thickness 100 μm). The obtained support was used as the support in Production Example 2. In addition, the support body of the manufacture example 2 contains a thermoplastic resin as a main component.

[Production Example 101]
The coating liquid of Production Example 101 was produced by the following method.
Anionic polyurethane resin (a) as an anionic polyurethane resin aqueous dispersion (trade name: Hydran AP20, manufactured by DIC Corporation) as a solid content of 6% by mass, nonionic or anionic binder resin (b) as an acid-modified polyolefin A resin water dispersion (trade name: Arrow Base SB-1030, Unitika Ltd.) was added to a solid content of 1.0 mass%, and aqueous ammonia was added to a basic pH adjuster (c) to a pH of 8.0. Thus, a coating solution was obtained. 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 wt% in the aqueous dispersion). In Table 2 below, “◯” described in the column of basic pH adjuster (c) means that the pH of the coating solution was adjusted using the corresponding type of basic pH adjuster (c). means. The basic pH adjuster (c) added to the coating solution in each example, reference example and comparative example was 0.5 to 3 parts by mass with respect to 100 parts by mass of the anionic polyurethane resin (a). It was a range.

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

[Reference Examples 2 and 6, Examples 3 to 5 and 7 to 10, Comparative Examples 2 and 3]
The materials shown in Table 1 above were prepared at the blending ratios shown in Table 2 below, and the basic pH adjuster (c) was added to adjust the pH to the values shown in Table 2, and Production Examples 102 to 110, 112 And 113 coating solutions were produced.
Reference Examples 2 and 6, Examples, except that the coating liquid described in Table 2 below was used as the coating liquid, and the coating amount (solid content) described in Table 2 below was used. Print media of 3 to 5 and 7 to 10 and Comparative Examples 2 and 3 were obtained.

[Comparative Example 1]
The materials listed in Table 1 above were prepared at the blending ratios listed in Table 2 below, and the coating liquid of Production Example 111 was produced.
A printing medium of Comparative Example 1 was obtained in the same manner as Reference Example 1 except that the coating liquid of Production Example 111 was used as the coating liquid and the coating amount (solid content) shown in Table 2 below was used.

[Example 11]
In Example 4, the printing medium of Example 11 was obtained in the same manner as in Example 4 except that the coating liquid obtained in Manufacturing Example 104 of the coating liquid was applied to the surface of the support in Manufacturing Example 2. It was.

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

(Measurement of zeta potential)
The sample for measurement was obtained by diluting with distilled water so that the solid content concentration of the anionic polyurethane resin (a) in the coating liquid of each production example was 1.0%. Using a zeta potential meter / particle size measurement system ELSZ-2 (manufactured by Otsuka Electronics Co., Ltd.), the zeta potential was measured while appropriately diluting the measurement sample. The obtained results are shown in Table 2 below.

<Solid content of resin layer>
The solid content (coating amount) of the resin layer of the printing media of each Example, Reference Example and Comparative Example is shown in Table 2 below. The solid content of the resin layer of the printing medium of each example, reference example and comparative example can be measured by peeling the resin layer. The solid content of the resin layer of the printing medium of each Example, Reference Example, and Comparative Example coincides 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 of the examples, reference examples and comparative examples were evaluated for (1) physical properties before printing, (2) general printability, and (3) inkjet suitability, as described below. The results are summarized in Table 3 below.
In addition, (2) General print suitability and (3) Inkjet suitability were evaluated for print media after storage in a high humidity environment.

(1) Physical properties before printing (also called blank paper properties)
(Surface streaks)
The print medium was cut to a width of 210 mm, the surface was visually observed, and the frequency of surface stripes parallel to the coating flow direction (coating stripes resulting from coating) was visually observed and evaluated in the following five stages. .
5: No streak is found (good)
4: One streak can be seen (possible)
3: 2 to 3 streaks can be seen (possible)
2: 4 to 10 streaks are seen (impossible)
1: More than 10 muscles are seen (impossible)

(Surface resistivity)
The print medium was cut into 10 cm × 10 cm and allowed to pass for 2 hours in an atmosphere at a temperature of 23 ° C. and a relative humidity of 50%. Thereafter, the surface resistivity on the resin layer side of the print medium is based on JIS K 6911: 1995, using an insulation meter (trade name: DSM-8103, manufactured by Toa Denpa Kogyo Co., Ltd.) and a double ring method electrode. It was measured. JIS is an abbreviation for Japan Industrial Standards.
When the measured surface resistivity is 1 × 10 ¹³ Ω or more, it is determined 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 feeding and discharging properties during printing and printing are good, and it is suitable as a printing medium.

(2) General printability (blank yellowing)
The print medium was stored in an atmosphere of 40 ° C. and 80% relative humidity for 7 days, and then the presence or absence of yellowing was evaluated by visual observation.
In Example 5, yellowing occurred at the paper edge of the printing medium of Example 5 that is printing paper.

(Ink transfer)
The print media of each Example, Reference Example and Comparative Example were stored for 7 days in an atmosphere at a temperature of 40 ° C. and a relative humidity of 80%.
Printing machine (trade name: RI-III type print aptitude tester, manufactured by Akira Seisakusho Co., Ltd.) and UV curable printing ink (trade name: Best Cure 161 (black), manufactured by T & K TOKA Co., Ltd.) The above ink was solid printed on the surface of the print medium on the resin layer side so as to have a thickness of 1.5 g / m ² . The solid printing referred to here means that the entire surface is printed with a single ink in a specific range of the printing medium. The solid-printed area is called the color display. Next, under a single ultraviolet lamp (metal halide lamp, output 80 W / cm, manufactured by Eye Graphics Co., Ltd.), a distance of 10 cm from the lamp is passed once at a speed of 10 m / min, and the printing surface is irradiated with ultraviolet rays. A printed matter obtained by drying and solidifying the ink was obtained. Thereafter, the light reflection density (Macbeth density) of the printed material was measured with a Macbeth densitometer (made by Colmogen, USA), and the unevenness of the color-exposed surface (coating streaks, transfer defects such as white spots) was visually observed. 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: The optical density is less than 1.5, but unevenness is not noticeable (impossible)
1: Optical density is less than 1.5, and unevenness is conspicuous (impossible)

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

(3) Inkjet suitability (print quality)
For printing, an ultraviolet curable inkjet printer (trade name “OceArizona250GT”, manufactured by Oce) and an ultraviolet curable inkjet printing ink (trade name: Best Cure 161 (black), manufactured by T & K TOKA) were used. .
The print medium after storage for 7 days in an atmosphere of 40 ° C. and 80% relative humidity was aged for another 3 days in an atmosphere of 23 ° C. and 50% relative humidity. Thereafter, 100% solid and characters (ruled line thickness: 5 pt) were printed on the surface of the resin layer of the printing medium using the above-described printing machine. After printing, the characters 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: The ink blur is not clear visually, but the dot area is widened by the observation with the loupe 3: The ink blur is slightly recognized visually (possible)
2: Ink bleeding is observed 1: Ink bleeding is remarkable

(Water resistant adhesion)
The ink-jet printed printing medium was soaked in water at 23 ° C. for 24 hours, then taken out and wiped with a waste cloth to remove moisture on the surface. Next, cellophane tape (trade name: Cellotape (registered trademark) CT-18, manufactured by Nichiban Co., Ltd.) was affixed to the printed surface, and the cellophane tape was quickly peeled off after sufficient adhesion. Next, from the visual observation of the state of the printed surface after peeling the tape, the water-resistant adhesion of the ink was evaluated in five levels according to the following criteria.
5: Ink does not peel at all (good)
4: The ink of a slight part (peeling part is less than 5%) was peeled off (possible).
3: The peeled portion was 5% or more and less than 25% (reference)
2: The peeled portion was 25% or more and less than 50% (impossible)
1: The peeled portion was 50% or more (impossible)

From Table 3 above, the printing media of Reference Examples 1, 2 and 6, and Examples 3 to 5 and 7 to 11 were made of anionic resin, had few surface streaks, and were subjected to general printing using ultraviolet curable ink. Excellent ink transfer and ink adhesion after storage in a high temperature and high humidity environment, and water resistance adhesion after storage in a high temperature and high humidity environment when ink-jet recording using UV curable ink is performed. It was an excellent print medium. Among them, the printing media of Examples 3 to 5 and 7 to 11 containing the basic pH adjuster (c) as a free base and a base having a pKa of 9.5 to 13.0 are the same as those of Reference Examples 1, 2, and 6. It was a print medium that was superior in water-resistant adhesion after being stored in a high-temperature and high-humidity environment when inkjet recording was performed. In particular, the coating liquid used in each Example to which the basic pH adjuster (c) was added was an anionic urethane resin (in the coating liquid) compared to Comparative Example 1 in which the basic pH adjuster (c) was not added. The absolute value of the zeta potential in a) was increased. As a result, it was found that the effect of suppressing the surface streaks after coating can be obtained by increasing the electric repulsive force between the emulsion particles of the anionic urethane resin (a) in the coating liquid to improve the dispersibility.
On the other hand, the printing medium of Comparative Example 1 not containing the basic pH adjuster (c) had many surface streaks. The printing medium of Comparative Example 2 that does not contain the nonionic or anionic binder resin (b) has ink adhesion after storage in a high-temperature and high-humidity environment when performing general printing using an ultraviolet curable ink. Inferior, when performing ink jet recording using an ultraviolet curable ink, the water adhesion after storage in a high temperature and high humidity environment was also poor. The print medium of Comparative Example 3 that does not contain an anionic urethane resin (a) has poor ink transferability after storage in a high-temperature and high-humidity environment when general printing using an ultraviolet curable ink is performed. It was.
From the relationship between Examples and Reference Examples, the following tendencies can be read. In contrast to Reference Example 2 in which the solid content (coating amount) of the resin layer is excessive, Reference Example 1 in which the solid content (coating amount) of the resin layer is preferable is that the ink adhesion of general printing and the print quality of inkjet are high. It was good. In addition, the addition of the antistatic agent decreased the surface resistivity and exhibited antistatic properties (Example 3). In addition, B1, which is an acid-modified nonionic or anionic binder resin (b), easily reacts with a carbodiimide crosslinking agent (Examples 3 to 5), and other nonionic or anionic binder resins (b) were used. Compared to Examples 8 to 10, the water-resistant adhesion of the ink-jet printed material was improved (Examples 3 to 5). Among the basic pH adjusters (c), the gas state type (Reference Example 1) and the solid state type (Reference Examples 2 and 6, Examples 3 to 5, In the case of using 8 to 11), the ink adhesion in general printing was higher than in the case of using the liquid state type (Example 7) at room temperature. In addition, when the basic pH adjusting agent (c) having a pKa in an appropriate range was added, no blank yellowing was observed on the printing medium after storage for 7 days in an atmosphere at a temperature of 40 ° C. and a relative humidity of 80% ( Reference Examples 1, 2, 6 and Examples 3, 4, 7 to 11).

It can be confirmed by infrared absorption analysis (IR) that the anionic polyurethane resin (a) is contained in the printing medium of each example, reference example and comparative example and in the resin layer. It can be confirmed by infrared absorption analysis that the nonionic or anionic binder resin (b) is contained in the printing media of each Example, Reference Example and Comparative Example. The basic pH adjuster (c) is contained in the printing medium of each example, reference example and comparative example and in the resin layer. The basic pH adjuster (c) is extracted by immersing the printing medium in water. Can be confirmed.

The printing medium of the present invention uses an anionic resin, has few surface streaks, and has excellent ink transferability and ink adhesion after storage in a high-temperature and high-humidity environment when performing general printing using an ultraviolet curable ink. It excels in water-resistant adhesion after storage in a high-temperature and high-humidity environment when performing ink jet recording using an ultraviolet curable ink. Therefore, it is suitable as a print medium, a label print medium, and an on-demand print medium in applications requiring water resistance.

Claims

On at least one surface of a support containing a thermoplastic resin as a main component,
Having a resin layer containing an anionic polyurethane resin (a), a nonionic or anionic binder resin (b) and a basic pH adjuster (c);
A printing medium wherein the basic pH adjusting agent (c) contains a free base and a pKa of 9.5 to 13.0.
The printing medium according to claim 1, wherein the resin layer has a solid content of 0.01 g / m 2 to 5 g / m 2 .
The printing medium according to claim 1 or 2, wherein the basic pH adjusting agent (c) is in a gaseous state or a solid state at 20 ° C and 1 atm.
The printing medium according to any one of claims 1 to 3, wherein the basic pH adjusting agent (c) includes a free base and a base having a pKa of 9.9 to 13.0.
The basic pH adjusting agent (c) is an alkylamine having 1 or 2 carbon atoms, triethanolamine, a quaternary ammonium, a tertiary sulfonium, or a secondary iodonium having a side chain consisting of an alkyl group having 1 to 4 carbon atoms or a phenyl group. The printing medium according to any one of claims 1 to 4, which comprises one or more bases selected from hydroxides, guanidines, amino acids having an isoelectric point of 9.5 or more, polyvinylamine, and polyallylamine.
The printing medium according to any one of claims 1 to 5, wherein the resin layer is a coating layer formed from a coating liquid.
On at least one surface of a support containing a thermoplastic resin as a main component,
A step of applying a coating liquid containing an anionic polyurethane resin (a), a nonionic or anionic binder resin (b) and a basic pH adjuster (c) to form a resin layer;
A method for producing a printing medium, wherein the basic pH adjusting agent (c) comprises a free base and a pKa of 9.5 to 13.0.
The method for producing a printing medium according to claim 7, wherein the basic pH adjuster (c) contains a free base and a pKa of 9.9 to 13.0.
The method for producing a print medium according to claim 7 or 8, wherein the pH of the coating liquid is 6.5 to 13.0.
A printed matter having an ultraviolet curable ink on the resin layer of the printing medium according to any one of claims 1 to 6.