WO2020203845A1

WO2020203845A1 - Printing paper and printed matter

Info

Publication number: WO2020203845A1
Application number: PCT/JP2020/014211
Authority: WO
Inventors: 李香渡邉; 暢洋岩谷; 鈴木　達也; 秀幸今井
Original assignee: 株式会社ユポ・コーポレーション
Priority date: 2019-04-02
Filing date: 2020-03-27
Publication date: 2020-10-08
Also published as: JPWO2020203845A1; JP7142153B2

Abstract

Provided are a printing paper and printed matter, which have excellent versatility and drying properties of ink and can suppress the occurrence of chemical ghosts.　The printing paper has a thermoplastic resin film including a porous layer, and an antistatic layer provided on the porous layer of the thermoplastic resin film, wherein the oil absorption amount of the printing paper is 1.0 g/m² or more, and when the surface of the antistatic layer of the printing paper is measured by X-ray photoemission spectroscopy, the ratio of the atomic concentration of nitrogen atoms with respect to the total of the respective atomic concentrations of nitrogen atoms and carbon atoms is 3.0% or less.

Description

Printing paper and printed matter

The present invention relates to printing paper and printed matter.

Conventionally, not only pulp paper but also synthetic paper using a resin film has been used as printing paper. An antistatic agent may be applied to the outermost surface of the synthetic paper for stable printing (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2000-131870

Among the inks used for offset printing of printing paper, there is an oxidative polymerization type ink that dries by reacting with oxygen in the air. The oxidative polymerization type ink dries when the solvent in the ink evaporates or penetrates into the pulp paper and the oxidative polymerization of the remaining components proceeds. Oxidative polymerization type inks used for pulp paper generally contain a relatively large amount of solvent with respect to the components to be oxidatively polymerized so as to accelerate the start of oxidative polymerization and shorten the drying time. On the other hand, if the same ink as pulp paper is used for synthetic paper, which is less susceptible to solvent penetration than pulp paper, the drying time is not sufficient for the same drying time as pulp paper, and the printed surface is printed when the synthetic papers after printing are stacked. In some cases, the ink was transferred to other synthetic paper.

For this reason, measures such as using ink with a smaller amount of solvent than the ink used for pulp paper as ink for synthetic paper, or selecting an image with a small amount of ink and easy drying as an image to be printed on synthetic paper. Was required, and the printing conditions were limited.

In addition, printing paper may be stacked and stored after printing. At this time, the ink on the printing surface may affect the printing paper stacked on the printing paper. For example, when printing is performed on the front surface of printing paper and stacked, and then printing is also performed on the back surface of each printing paper, the ink on the front surface (derived component) is applied to the ink on the back surface of the printing paper. A phenomenon that inhibits transcription may occur. This phenomenon is called chemical ghost. When chemical ghosts occur, the reproducibility of color, density, etc. differs between the area printed on the printed portion on the front surface and the area not overlapped on the printed portion on the back surface.

An object of the present invention is to provide a printing paper and a printed matter which are excellent in versatility and dryness of ink and can suppress the generation of chemical ghosts.

As a result of diligent studies by the present inventors to solve the above problems, the ratio of the atomic concentration of nitrogen atoms on the surface of the antistatic layer side, or the primary or secondary level of the nitrogen compound in the antistatic layer. The present invention has been completed by finding that the above problems can be solved if the printing paper has a nitrogen content as small as a specific value or less and an oil absorption as a specific value or more.
That is, the present invention is as follows.

(1) A printing paper having a thermoplastic resin film containing a porous layer and an antistatic layer provided on the porous layer of the thermoplastic resin film.
The oil absorption of the printing paper is 1.0 g / m ² or more.
When the surface of the printing paper on the antistatic layer side is measured by X-ray photoelectron spectroscopy, the ratio of the atomic concentration of nitrogen atom to the total atomic concentration of nitrogen atom and carbon atom is 3.0% or less. ,
Printing paper.

(2) The antistatic layer contains a nitrogen-containing compound and
The nitrogen-containing compound contains a quaternary nitrogen-containing compound.
The content of the quaternary nitrogen-containing compound in the nitrogen-containing compound is 50% by mass or more.
The printing paper according to (1) above.

(3) The nitrogen-containing compound contains a primary nitrogen-containing compound or a secondary nitrogen-containing compound.
The content of the primary nitrogen-containing compound and the secondary nitrogen-containing compound in the nitrogen-containing compound is 20% by mass or less.
The printing paper according to (1) above.

(4) The antistatic layer contains a nitrogen-containing compound and a cross-linking agent.
The nitrogen-containing compound contains a primary nitrogen-containing compound or a secondary nitrogen-containing compound.
The printing paper according to claim 1.

(5) A printing paper having a thermoplastic resin film containing a porous layer and an antistatic layer provided on the porous layer of the thermoplastic resin film.
The oil absorption of the printing paper is 1.0 g / m ² or more.
The antistatic layer contains a nitrogen-containing compound, and the total content of primary or secondary nitrogen in the total nitrogen contained in the nitrogen-containing compound is 10% or less.
Printing paper.

(6) The porous layer contains a thermoplastic resin and a filler, and the porous layer contains a thermoplastic resin and a filler.
The particle size distribution D10-D90 of the filler is 4 μm or less.
The printing paper according to any one of (1) to (5) above.

(7) The porous layer contains a soft polyolefin resin as the thermoplastic resin.
The printing paper according to any one of claims (1) to (6).

(8) An intermediate layer is provided between the base material layer and the porous layer.
The intermediate layer contains a filler having an average particle size larger than the thickness of the intermediate layer.
The printing paper according to any one of (1) to (7) above.

(9) The porous layer is a stretched film stretched in at least one axial direction.
The printing paper according to any one of (1) to (8) above.

(10) The printing paper according to any one of (1) to (9) above,
The printing layer provided on the printing paper and
Have a printed matter.

(11) The print layer is formed by an oxidative polymerization type ink.
The printed matter according to (10) above.

According to the present invention, it is possible to provide a printing paper and a printed matter which are excellent in versatility and dryness of ink and can suppress the generation of chemical ghosts.

It is sectional drawing which shows the structural example of the printing paper of one Embodiment of this invention. It is a top view which shows each print surface of the printed matter A and printed matter B to be superposed. It is sectional drawing which shows the filler contained in the intermediate layer.

Hereinafter, the printing paper and the printed matter of the present invention will be described in detail, but the description of the constituent requirements described below is an example (representative example) as an embodiment of the present invention, and is specified in these contents. is not.
In the following description, the description of "(meth) acrylic" refers to both acrylic and methacrylic. Further, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.

(Printing paper)
The printing paper of the present invention has a thermoplastic resin film including a porous layer and an antistatic layer provided on the porous layer of the thermoplastic resin film.

<Oil absorption>
The oil absorption of the printing paper of the present invention is 1.0 g / m ² or more. When the oil absorption amount is 1.0 g / m ² or more, when the ink is transferred to the printing paper, a large amount of the solvent in the ink can be absorbed in a short time. In the oxidative polymerization type ink, after the solvent is evaporated from the ink or absorbed by the printing paper, the oxidative polymerization of the remaining oxidative polymerization components proceeds and the ink dries. Therefore, even if the ink for pulp paper contains a relatively large amount of solvent than the ink for synthetic paper using a resin film, the printing paper of the present invention absorbs a large amount of solvent in a short time to dry the ink. The time required can be shortened. That is, the printing paper of the present invention is excellent in drying property regardless of whether it is an ink for pulp paper or an ink for synthetic paper, and since either ink can be used, the versatility of the ink is also excellent. ..

Preferably the oil absorption is 1.5 g / ^{m 2} or more, more preferably 1.8 g / ^{m 2} or more, more preferably 2.0 g / ^{m 2} or more, 3.0 g / m It is particularly preferable that the number is ² or more. The larger the amount of oil absorbed, the faster the drying rate can be increased by absorbing a larger amount of solvent from the ink in a shorter time. It is easy to prevent show-through of ink, and it is possible to quickly move to the next process, which improves printing work efficiency.
Since it is sufficient to absorb the solvent in the ink, the oil absorption amount can be, for example, 10.0 g / m ² or less, and 5.0 g / m ² or less.

The above oil absorption is the mass and oil absorption of the printing paper before and after contact with Mineral Oil (manufactured by Wako Pure Chemical Industries, Ltd .: density 0.84) for 5 seconds on the surface on which printing paper cut out to a certain size is printed. The area is measured and calculated by the following formula.
Oil absorption (g / m ² ) =
{(Mass after oil absorption (g))-(Mass before oil absorption (g))} / (Area absorbed oil (m ² ))

<Ratio of atomic concentration of nitrogen atom>
When the surface of the printing paper of the present invention on the antistatic layer side is measured by X-ray Photoelectron Spectroscopy (XPS), the nitrogen atom with respect to the total atomic concentration (atom%) of the nitrogen atom and the carbon atom. The ratio of the atomic concentration (atom%) of is 3.0% or less.
When the ratio of the atomic concentration of the nitrogen atom is as small as 3.0% or less, the generation of chemical ghost can be effectively suppressed. The mechanism by which chemical ghosts are generated is not always clear, but the present inventors have found that nitrogen-containing compounds on the surface of printing paper come into contact with the gas generated during oxidative polymerization of ink and deteriorate, thereby inhibiting ink transfer. I'm guessing that it may cause. The present inventors focused on reducing the nitrogen-containing compound presumed to be the causative substance of this chemical ghost, and controlled the ratio of nitrogen atoms on the surface of the printing paper to 3.0% or less, and found that the chemical ghost. It turned out that it can suppress. As described above, even when the oil absorption of the printing paper is more than the specific value and the oxidative polymerization proceeds rapidly, if the ratio of the atomic concentration of nitrogen atoms is less than the specific value, the chemical ghost is effectively suppressed. , Ink transferability can be improved.

From the viewpoint of further suppressing chemical ghosts, the above ratio is preferably 2.8% or less, more preferably 2.6% or less, still more preferably 2.4% or less. It is particularly preferably 0% or less. The smaller the ratio is, the higher the suppressing effect is, and it may be 0%, but when the antistatic layer contains a nitrogen-containing compound described later, it is larger than 0%, for example, 0.01% or more.

The ratio (%) of the atomic concentration of the nitrogen atom is the peak area of the N1s peak of the nitrogen atom with respect to the sum of the peak area of the C1s peak of the carbon atom and the peak area of the N1s peak of the nitrogen atom measured by XPS. Obtained as a percentage.

The printing paper of the present invention may have a porous layer and an antistatic layer on only one side as long as it has a porous layer and an antistatic layer on at least one side, and the printing paper may have a porous layer and an antistatic layer on both sides. It may have a quality layer and an antistatic layer. When the porous layer and the antistatic layer are provided on only one side, it is suitable to print on the front surface of the antistatic layer side first and then on the back surface. Further, the thermoplastic resin film may have a single-layer structure having only a porous layer, or may have a multi-layer structure having a layer other than the porous layer.

FIG. 1 is a cross-sectional view showing a configuration example of printing paper as an embodiment of the present invention.
As shown in FIG. 1, the printing paper 10 has a thermoplastic resin film 1 including a porous layer 2 provided on one surface side, and an antistatic layer 3 provided on the porous layer 2. In the example of the printing paper 10, the porous layer 2a is also provided on the other surface side of the thermoplastic resin film 1, and the antistatic layer 3a is provided on the porous layer 2a. Further, in the example of the printing paper 10, the thermoplastic resin film 1 has a multilayer structure, and has a base material layer 4 and

intermediate layers

5 and 5a provided on both sides of the base material layer 4, respectively. The

porous layers

2 and 2a are provided on the

intermediate layers

5 and 5a, respectively, and form the outermost layer of the thermoplastic resin film 1. The two

porous layers

2, 2a, the

antistatic layers

3, 3a, and the

intermediate layers

5, 5a may have the same composition, thickness, or the like, or may be different.

Hereinafter, each layer constituting the printing paper of the present invention will be described.

<Antistatic layer>
The antistatic layer can suppress adhesion of foreign matter to the printing paper due to static electricity, deterioration of transportability due to blocking, and the like. The antistatic layer is preferably provided as the outermost layer of the printing paper from the viewpoint of reducing the influence of static electricity such as blocking. The antistatic layer can be formed, for example, by applying an antistatic agent-containing coating liquid onto the porous layer.

<< Antistatic agent >>
The antistatic agent is not particularly limited, and known antistatic agents such as polymer type and metal oxide type antistatic agents can be used. As the polymer type antistatic agent, a cationic type, an anion type, an amphoteric type, a nonionic type and the like are known, and any of them can be used. Examples of the cationic type include compounds having an ammonium salt structure or a phosphonium salt structure. Examples of the anion type include alkali metal salts such as sulfonic acid, phosphoric acid and carboxylic acid, specifically alkali metal salts such as acrylic acid, methacrylic acid and (anhydrous) maleic acid (for example, lithium salt, sodium salt and potassium salt). Etc.) Examples include compounds having a structure in the molecular structure. Examples of the amphoteric type include compounds containing both the above-mentioned cationic type and anion type structures in the same molecule, specifically, 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. Examples of the metal oxide type antistatic agent include fine particles having a metal oxide, for example, a colloidal silica sol having a metal oxide layer on the surface of colloidal silica. In addition, a polymer-type antistatic agent having boron in its molecular structure can be mentioned as an example. One of these may be used alone or in combination of two or more.

Among them, a cationic polymer type antistatic agent is preferable because of its good antistatic performance, and a nitrogen-containing polymer type antistatic agent, for example, a tertiary nitrogen or a quaternary nitrogen (ammonium salt structure) -containing acrylic type is preferable. Polymers are more preferred.
Commercially available products can also be used as the antistatic agent. Commercially available products of tertiary or quaternary nitrogen-containing acrylic polymers include, for example, Saftmer ST-1000, Saftmer ST-1100, Saftmer ST-1300, and Saftmer ST-3200, which are water-soluble and easy to prepare a coating solution. (Made by Mitsubishi Chemical Corporation), etc.

<< Anchor >>
The antistatic layer preferably contains an anchoring agent from the viewpoint of obtaining more stable adhesion to the ink. The anchoring agent is not particularly limited, and a known anchoring agent can be appropriately used. Examples of the anchoring agent that can be used include a polyimine-based polymer, an ethyleneimine adduct of a polyamine polyamide, and a mixture thereof. Examples of the ethyleneimine adduct of the polyimine polymer or the polyamine polyamide include polyethyleneimine, poly (ethyleneimine-urea) and the ethyleneimine adduct of the polyamine polyamide; these alkyl modified products, cycloalkyl modified products and aryl modified products. Examples thereof include allyl-modified products, aralkyl-modified products, alkylal-modified products, benzyl-modified products, cyclopentyl-modified products, and aliphatic cyclic hydrocarbon-modified products; hydroxides thereof; and the above-mentioned complexes. One of these may be used alone or in combination of two or more.

When an antistatic agent and an anchor agent are used in combination, their content ratios can be appropriately set according to the required performance and are not particularly limited. From the viewpoint of fully exerting the performance of each component, the content of the anchoring agent is preferably 0 to 200 parts by mass, more preferably 0 to 150 parts by mass with respect to 100 parts by mass of the antistatic agent in terms of solid content ratio. , More preferably 0 to 100 parts by mass, and particularly preferably 0 to 50 parts by mass.

<< Crosslinking agent >>
The antistatic layer may contain a cross-linking agent from the viewpoint of water resistance, stability over time, improvement of layer strength, and the like.
Examples of the cross-linking agent include epoxy compounds such as glycidyl ether and glycidyl ester, and water-dispersible resins such as epoxy resins, isocyanates, oxazolines, formalins, and hydrazides.
The content of the cross-linking agent in the antistatic layer is preferably 1 to 200 parts by mass, more preferably 1 to 200 parts by mass, based on 100 parts by mass of the total of the primary and secondary nitrogen-containing compounds from the viewpoint of the stability of the solution over time. It is 10 to 170 parts by mass, more preferably 20 to 140 parts by mass.

The coating liquid used to form the antistatic layer can be obtained by dissolving or dispersing various components such as an antistatic agent in a solvent. As the solvent, water, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, ethyl acetate, toluene, xylene and the like are generally used. From the viewpoint of handleability at the time of coating, the coating liquid is preferably an aqueous solution. The solid content concentration of the coating liquid is preferably about 0.1 to 20% by mass, more preferably 0.3 to 15% by mass, and further preferably 0.5 to 10% by mass.

As the coating device, various known coating devices can be used and are not particularly limited. For example, a coating device such as a die coater, a bar coater, a lip coater, a roll coater, a gravure coater, a spray coater, a blade coater, an air knife coater, and a size press coater can be used.

<< Nitrogen-containing compound >>
The antistatic layer may contain nitrogen-containing compounds.
Examples of the nitrogen-containing compound include amine compounds, imine compounds, amide compounds, imide compounds, isocyanate compounds, urethane compounds, and nitrile compounds. Among them, the nitrogen-containing compound is preferably an amide compound, an imide compound, an isocyanate compound, a urethane compound or a nitrile compound from the viewpoint of suppressing chemical ghosts. However, even an amine compound or an imine compound can be used without any problem by controlling the substitution of the amino group or the imino group.
The nitrogen-containing compound can be blended as the above-mentioned antistatic agent, anchoring agent, etc., but the antistatic layer can contain an antistatic agent, anchoring agent, etc. other than the above-mentioned nitrogen compound.

The nitrogen-containing compound can contain any of primary to quaternary nitrogen-containing compounds, but it is preferable to include a quaternary nitrogen-containing compound because it has a high effect of suppressing chemical ghosts.
When the nitrogen compound contains a quaternary nitrogen-containing compound, the content of the quaternary nitrogen compound in the nitrogen compound is preferably 50% by mass or more, more preferably 70% by mass or more, and 90% by mass. The above is more preferable, and 95% by mass or more is particularly preferable. The higher the content of the quaternary nitrogen compound in the nitrogen compound, the easier it is to suppress chemical ghosts.

When the nitrogen-containing compound contains a primary nitrogen-containing compound or a secondary nitrogen-containing compound, the total content of each of the primary nitrogen-containing compound and the secondary nitrogen-containing compound in the nitrogen compound is 20% by mass or less. It is preferably 15% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less. The lower the content of the primary and secondary nitrogen-containing compounds in the nitrogen compound, the easier it is to suppress chemical ghosts.

The total content (pieces) of primary to tertiary nitrogen in the total nitrogen (pieces) contained in the nitrogen-containing compound is preferably 35% or less, more preferably 30% or less, and 25. It is more preferably% or less. The total content of the primary or secondary nitrogen in the total nitrogen contained in the nitrogen-containing compound is preferably 10% or less, more preferably 9% or less, and more preferably 7% or less. It is more preferable, and it is particularly preferable that it is 5% or less. The lower the content of primary to tertiary nitrogen, particularly primary to secondary nitrogen, the easier it is to suppress chemical ghosts. The content of primary to quaternary nitrogen in the total nitrogen contained in the nitrogen-containing compound can be measured by, for example, a nuclear magnetic resonance apparatus, an X-ray optical spectrometer, or the like.

The printing paper of the present invention is primary or primary in total nitrogen contained in the nitrogen-containing compound even when the ratio of the atomic concentration (atom%) of nitrogen atoms does not satisfy the condition of 3.0% or less. When the total content of the secondary nitrogen is 10% or less, the generation of chemical ghosts can be effectively suppressed as in the case where the ratio of the atomic concentration of nitrogen atoms is 3.0% or less. According to the studies by the present inventors, among the nitrogen-containing compounds presumed to be the causative substances of chemical ghosts, lower nitrogen-containing compounds containing primary or secondary nitrogen, which are particularly easily deteriorated by contact with gas, are specified. It was found that the chemical ghost can be suppressed by controlling the following.

When the nitrogen-containing compound contains a primary to tertiary nitrogen-containing compound, the antistatic layer preferably further contains a cross-linking agent. By coordinating or covalently bonding the cross-linking agent to the nitrogen atom of the primary to tertiary nitrogen-containing compounds, the primary to tertiary nitrogen-containing compounds, especially the highly reactive lower amine compounds, are reduced. It is presumed that even if the ink comes into contact with gas generated when the ink is oxidatively polymerized and dried, there is little deterioration and it is easy to suppress chemical ghosts. If the antistatic agent contains a cross-linking agent and the total content of each of the primary to tertiary nitrogen-containing compounds in the nitrogen-containing compound is within the above range, chemical ghosts are more effectively suppressed. be able to. When the cross-linking agent is a nitrogen-containing compound (particularly a primary nitrogen-containing compound or a secondary nitrogen-containing compound), self-cross-linking also contains a group (epoxy group, etc.) capable of reacting with an amine or the like in the molecule. It is preferable that it is possible.

The ratio (%) of the atomic concentration of nitrogen atoms on the surface of the printing paper on the antistatic layer side, or the total content of primary or secondary nitrogen in the total nitrogen contained in the nitrogen-containing compound is charged. It can be controlled to a specific value or less by adjusting the solid content of a component containing a nitrogen-containing compound in the coating liquid for forming the preventive layer, for example, an antistatic agent, an anchor agent, and the like.

<Thermoplastic resin film>
The thermoplastic resin film may be a single-layer film having only a porous layer as described above, as long as it contains a porous layer on the outermost surface, or includes other layers such as a base material layer and an intermediate layer. It may be a multilayer film.
Further, each layer of the thermoplastic resin film may be a non-stretched film, but if it is a stretched film stretched in at least one axial direction, it is easy to obtain a thickness, stiffness, etc. excellent in printability as printing paper. Moreover, it is preferable because it is easy to flatten the surface or the interface between layers.

<< Porous layer >>
The porous layer has a large number of pores and absorbs the solvent in the ink to improve the drying property of the ink. The greater the proportion of the pores in the porous layer communicating with each other, the greater the amount of oil absorbed by the printing paper and the better the dryness of the ink. On the other hand, if the proportion of independent pores in the porous layer is large, the amount of oil absorbed becomes small and the drying property of the ink decreases. In this way, since the degree of communication of the holes is proportional to the oil absorption of the printing paper, it is possible to judge whether or not there are sufficient pores communicating with each other in the porous layer based on the oil absorption of the printing paper. it can.

The porous layer preferably contains a thermoplastic resin and a filler from the viewpoint of forming pores that communicate with each other.

<<< Thermoplastic Resin >>>
Examples of the thermoplastic resin include polyolefin resins, polyester resins, polyamide resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins and the like. One of these thermoplastic resins can be used alone or in combination of two or more. From the viewpoint of improving the layer strength, the thermoplastic resin is preferably a polyolefin resin or a polyester resin, and more preferably a polypropylene resin or a polyethylene resin.

The thermoplastic resin preferably contains a hydrophobic or non-polar resin. This makes it possible to improve the amount of oil absorption when the pores in the porous layer are in communication with each other. In the present specification, the hydrophobic or non-polar resin refers to a resin having a solubility parameter (SP value) of, for example, 10 or less. The SP value is preferably 9.5 or less, more preferably 9.0 or less, and even more preferably 8.0 or less. Further, the SP value can be 6.5 or more, and may be 7.0 or more. The SP value is a value calculated by the method proposed by Small.

Examples of the hydrophobic or non-polar thermoplastic resin include polyolefin-based resins and polystyrene-based resins. The content of the hydrophobic or non-polar resin is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, based on the total mass of the thermoplastic resin. The content of the hydrophobic or non-polar resin may be, for example, 99% by mass or less, 98% by mass or less, or 97% by mass or less based on the total mass of the thermoplastic resin. It does not matter if all of the thermoplastic resins are composed of hydrophobic or non-polar resins.

From the viewpoint of suppressing the occurrence of edge picking, the porous layer preferably contains a soft polyolefin-based resin as the thermoplastic resin. The soft polyolefin resin refers to a polyolefin resin having a melting energy of 75 J / g or less as measured by differential scanning calorimetry (DSC). The melting energy is calculated from the peak area of the endothermic peak observed in DSC. Edge picking is a phenomenon in which deformation such as fluffing on the paper surface or peeling such as peeling occurs during printing.

The content of the soft polyolefin resin in the porous layer is preferably 1% by mass or more, more preferably 3% by mass or more, and further preferably 4% by mass or more. Further, the content is preferably 15% by mass or less, more preferably 10% by mass or less, and further preferably 8% by mass or less. When the content is 1% by mass or more, pores are excessively generated during stretching, and the occurrence of edge picking due to this tends to be suppressed. On the other hand, when the content is 15% by mass or less, a decrease in the proportion of independent pores is suppressed, and high dryness tends to be obtained.

From the viewpoint of suppressing edge picking, the tensile elastic modulus of the soft polyolefin resin is preferably 1.2 GPa or less. The tensile elastic modulus is measured at a temperature of 23 ° C. in accordance with JIS K7161-1: 2014 and JIS K7161-2: 2014.

The porous layer may further contain an acid-modified resin as the thermoplastic resin from the viewpoint of preventing the filler from falling off. Examples of the acid-modified resin include maleic acid-modified polyolefin and the like. The content of the acid-modified resin is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less, based on the total mass of the thermoplastic resin. The content of the acid-modified resin may be, for example, 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, based on the total mass of the thermoplastic resin.

<<< Filler >>
Examples of the filler include an inorganic filler and an organic filler, and either of them can be used alone or in combination of both. When the thermoplastic resin containing the filler is stretched, it becomes easy to form a large number of fine pores with the filler as the core.

Examples of the inorganic filler include heavy calcium carbonate, light calcium carbonate, calcined clay, talc, diatomaceous earth, barium sulfate, magnesium oxide, zinc oxide, titanium dioxide, silicon dioxide and the like.
Organic fillers include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyamide, polycarbonate, polyethylene sulfide, polyphenylene sulfide, polyimide, polyetherketone, polyetheretherketone, polymethylmethacrylate, and poly-4-methyl-1. -Pentene, homopolymers of cyclic olefins, copolymers of cyclic olefins and ethylene, and the like can be mentioned.
The inorganic filler or the organic filler may be surface-treated with a fatty acid or the like from the viewpoint of dispersing the filler having a relatively small particle size in the resin.

One of the above inorganic fillers or organic fillers can be used alone or in combination of two or more. Of these, an inorganic filler is preferable from the viewpoint of ease of adjusting the particle size distribution. Among the inorganic fillers, heavy calcium carbonate or light calcium carbonate is preferable from the viewpoint of pore formation, cost and the like, and titanium dioxide is preferable from the viewpoint of weather resistance.

The particle size of the filler is the median diameter (D50), and is preferably 0.01 μm or more, more preferably 0.1 μm or more, from the viewpoint of uniformly dispersing in the porous layer. The median diameter of the filler is preferably 10 μm or less, more preferably 3 μm, from the viewpoint of facilitating the separation of components such as pigments and binders in the ink and the solvent component and preventing color sinking or drying failure of the ink. It is less than or equal to, more preferably 1.5 μm or less, and particularly preferably 1.3 μm or less.
The particle size of the filler can also be determined as the average dispersed particle size when dispersed in the thermoplastic resin by melt-kneading and dispersion. Specifically, the cut surface of the film is observed with an electron microscope, the maximum diameters of at least 10 particles of the filler are measured, and the average value thereof is taken as the average dispersed particle diameter.

The particle size distribution D10-D90 of the filler is preferably 4 μm or less, more preferably 3.5 μm or less, and further preferably 3 μm or less. When the particle size distribution D10-D90 is within the above range, the pores generated in the porous layer during stretching are easily communicated with each other, and the oil absorption amount is easily increased to a specific value of 1.0 g / m ^2. .. The particle size distribution D10-D90 of the filler is usually 0.01 μm or more, may be 0.1 μm or more, and is preferably 0.3 μm or more from the viewpoint of cost.

The particle size distribution D10-D90 of the filler can be determined as follows.
The following D10, D50 and D90 are measured with a laser diffraction type particle size distribution measuring machine. The absolute value of the difference between the measured D90 and D10 is obtained as the particle size distribution D10-D90. Water, methanol, ethanol, ethylene glycol, etc. are appropriately used as the solvent used for the measurement, and the ultrasonic disperser Model US-300T manufactured by Nippon Seiki Co., Ltd. is used as the pretreatment for the measurement for 60 seconds under the condition of 300 μA. Perform ultrasonic dispersion.
D10: Cumulative total of filler particles 10% by volume particle diameter (μm)
D50: Integrated filler particles 50% by volume particle diameter (μm)
D90: Accumulation of filler particles 90% by volume particle diameter (μm)

The content of the filler in the porous layer is preferably 45 parts by mass or more, more preferably 60 parts by mass or more, and further, with respect to 100 parts by mass of the thermoplastic resin, from the viewpoint of forming pores. It is preferably 75 parts by mass or more, and particularly preferably 100 parts by mass or more. On the other hand, the content of the filler in the porous layer is preferably 250 parts by mass or less, more preferably 200 parts by mass, with respect to 100 parts by mass of the thermoplastic resin from the viewpoint of maintaining the strength of the multilayer layer appropriately. It is 5 parts or less, more preferably 150 parts by mass or less, and particularly preferably 125 parts by mass or less.

<<< Pore rate >>
The pore ratio, which represents the ratio of pores in the porous layer, is preferably 10% or more, more preferably 15% or more, and further preferably 20% or more, from the viewpoint of increasing communication holes. It is preferably 25% or more, and particularly preferably 25% or more. From the viewpoint of increasing the surface strength and reducing printing defects such as edge picking, the pore ratio is preferably 50% or less, more preferably 45% or less, still more preferably 40% or less. ..

The vacancy rate is an index showing the number of vacancy, and is not necessarily linked to the amount of oil absorbed. For example, even when a large number of pores are formed and the pore ratio is large, the amount of oil absorption is small if the degree of communication between the pores is small. As described above, the pore ratio and the oil absorption amount are independent index values, and even if the pore ratio of the porous layer of the printing paper is the same, the oil absorption amount is not necessarily the same.

The pore ratio can be obtained from the ratio of the area occupied by the pores in a certain region of the cross section of the printing paper observed with an electron microscope. Specifically, an arbitrary part of the printing paper is cut out, embedded in epoxy resin and solidified, and then cut perpendicularly to the surface direction of the printing paper using a microtome, and the cut surface becomes an observation surface. Attach it to the observation sample table as shown. Gold or gold-palladium or the like is deposited on the observation surface, the pores are observed at an arbitrary magnification (for example, a magnification of 500 to 3000 times) that is easy to observe with an electron microscope, and the observed area is captured as image data. The obtained image data can be subjected to image processing by an image analysis device to obtain the area ratio of the vacancy portion, and the vacancy ratio can be obtained. In this case, the vacancy rate can be obtained by averaging the measured values at any 10 or more observation points.

<< Base material layer >>
The base material layer functions as a support for the thermoplastic resin film and imparts strength, elasticity, etc. to the printing paper.
The base material layer preferably contains a thermoplastic resin and a filler from the viewpoint of imparting opacity. This makes it easier to prevent the pattern printed on one side from being seen through the other side.

As the thermoplastic resin of the base material layer, the same thermoplastic resin as that of the porous layer can be used, and for example, polyolefin resins, polyester resins, polyamide resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins and the like can be used. Can be mentioned. These resins may be used alone or in combination of two or more. The thermoplastic resin is preferably a polyolefin resin or a polyester resin, and more preferably a polypropylene resin or a polyethylene resin.

As for the filler of the base material layer, the same filler as the porous layer can be used. Examples of the inorganic filler include heavy calcium carbonate, light calcium carbonate, calcined clay, talc, diatomaceous earth, barium sulfate, magnesium oxide, zinc oxide, titanium dioxide, silicon dioxide and the like. Examples of the organic filler include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyamide, polycarbonate, polyethylene sulfide, polyphenylene sulfide, polyimide, polyetherketone, polyetheretherketone, polymethylmethacrylate, and poly-4-methyl-. Examples thereof include 1-pentene, a homopolymer of cyclic olefin, and a copolymer of cyclic olefin and ethylene. These inorganic fillers or organic fillers can be used alone or in combination of two or more.

The average particle size of the filler is preferably 0.01 μm or more, more preferably 0.1 μm or more, from the viewpoint of pore formation. Further, when the opacity or printability is improved by generating pores inside by stretching, the average particle size of the filler is preferably set from the viewpoint of suppressing sheet breakage during stretching and a decrease in strength of the base material layer. It is 30 μm or less, more preferably 20 μm or less, and more preferably 10 μm or less.

The "average particle size" of the filler in this specification is calculated by the following procedure. First, the printing paper is cut out and its cross section is exposed. The cross section is magnified to an appropriate magnification (for example, 1,000 times) using a scanning electron microscope, and a photographic image is taken. From the captured image, the average value of 100 randomly selected particle diameters (major diameters) present in the sample is calculated. The average particle size is calculated from this.

The content of the filler in the base material layer is preferably 1% by mass or more, more preferably 3% by mass or more, and particularly preferably 5% by mass or more. On the other hand, the content of the filler in the base material layer is preferably 45% by mass or less, more preferably 40% by mass or less, and particularly preferably 35% by mass or less. When the content is within the above range, the printing paper has an appropriate strength and is easy to handle.

From the viewpoint of improving the film strength, the base material layer is preferably stretched in at least one axial direction, and more preferably a stretched film stretched in two axial directions.

<< Intermediate layer >>
The intermediate layer is provided between the base material layer and the porous layer, and suppresses deformation such as waviness of the printing paper when the solvent component of the ink absorbed by the porous layer reaches the base material layer. Such a deformation is called a solvent attack.

From the viewpoint of suppressing solvent attack, the intermediate layer preferably contains a thermoplastic resin, and more preferably contains an amorphous resin as the thermoplastic resin.
As the thermoplastic resin, the same one as the thermoplastic resin in the porous layer can be used.

As the amorphous resin, an amorphous resin having a glass transition temperature of 140 ° C. or lower is preferable, and an amorphous resin having a glass transition temperature of 70 to 140 ° C. is more preferable. When the glass transition temperature of the amorphous resin is 70 ° C. or higher, sticking to the roll is reduced and the moldability is likely to be improved. When the glass transition temperature is 140 ° C. or lower, the amorphous resin is sufficient for the solvent. It absorbs and retains amorphous material, prevents solvent from penetrating into the base material layer, and easily suppresses solvent attack. When producing printing paper having an intermediate layer, it is preferable that the temperature during stretching is 10 ° C. or higher higher than the glass transition temperature of the amorphous resin.

Examples of the amorphous resin include cyclic olefin resin, atactic polystyrene, petroleum resin, polycarbonate, acrylic resin and the like. The amorphous resin is preferably a cyclic olefin resin, more preferably an ethylene-cyclic olefin copolymer. Among them, the intermediate layer preferably contains an ethylene-cyclic olefin copolymer as an amorphous resin together with a polypropylene resin as a thermoplastic resin.

The mixing ratio of the thermoplastic resin other than the amorphous resin and the amorphous resin in the intermediate layer is 0 to 80% by mass of the thermoplastic resin from the viewpoint of sufficiently suppressing the solvent attack, and the amorphous resin. Is preferably 20 to 100% by mass, the thermoplastic resin is 20 to 70% by mass, the amorphous resin is more preferably 30 to 80% by mass, and the thermoplastic resin is 30 to 60% by mass. It is more preferable that the amount of the amorphous resin is 40 to 70% by mass.

The porosity of the intermediate layer is preferably 5% or less from the viewpoint of reducing the solvent (particularly high boiling point petroleum solvent such as mineral oil) in the ink that passes through the pores and reaches the base material layer. % Or less is more preferable. The intermediate layer may contain a filler as long as the porosity is in the range of 5% or less.

When the intermediate layer contains a filler, from the viewpoint of suppressing chemical ghosts, the filler contained in the intermediate layer is a filler having an average particle size larger than the thickness of the intermediate layer (hereinafter, also referred to as a coarse filler). Is preferable. The coarse filler facilitates imparting roughness to the surface of the porous layer on the intermediate layer. If the surface is rough, gaps are generated between the printed matter when the printed matter after printing is stacked and stored. The gas generated by the oxidative polymerization of the ink is discharged to the outside through the voids, and the retention on the surface of the printed matter is suppressed, so that the chemical ghost is more easily suppressed.

The content of the coarse filler in the intermediate layer is preferably 1% by mass or more, more preferably 3% by mass or more, and further preferably 5% by mass or more. Further, the content is preferably 25% by mass or less, more preferably 20% by mass or less, and further preferably 15% by mass or less. When the content is 1% by mass or more, the above-mentioned effect of suppressing chemical ghosts can be easily obtained. Further, when the content is 25% by mass or less, the formation of pores in the intermediate layer is suppressed, and the arrival of the solvent in the base material layer is likely to be suppressed.

The distance (K) from the surface of the coarse filler to the surface of the porous layer when the center of the coarse filler is located at the center in the thickness direction of the intermediate layer preferably exceeds 0 μm. When the distance (K) exceeds 0 μm, it is easy to prevent the coarse filler from being exposed to the surface of the printing paper beyond the porous layer. In addition, it is easy to prevent the coarse filler from falling off from the printing paper and the generation of paper dust due to the falling off.

As shown in FIG. 3, the distance (K) is calculated by the following formula when the thickness of the porous layer is M1, the thickness of the intermediate layer is M2, and the average particle size of the coarse filler is φ. In addition, M1 and M2 refer to the thickness of the porous layer and the intermediate layer at the position where the coarse particles do not exist.
K = M1- (φ-M2) / 2

The distance (K) is preferably 10 μm or less, more preferably 9 μm or less, and even more preferably 6 μm or less. When the distance (K) is 10 μm or less, the surface of the porous layer described above is likely to be roughened, and chemical ghosts are more likely to be suppressed.

<<< Other Additives >>>
Each layer of the thermoplastic resin film can contain additives such as a heat stabilizer (antioxidant), a light stabilizer, a dispersant, and a lubricant, if necessary. When a heat stabilizer is used, each layer usually contains 0.001 to 1% by weight of the heat stabilizer. Examples of the heat stabilizer include steric hindrance phenol-based, phosphorus-based, amine-based and the like stabilizers. When a light stabilizer is used, each layer usually contains 0.001 to 1% by weight of the light stabilizer. Examples of the light stabilizer include steric hindrance amine-based, benzotriazole-based, and benzophenone-based light stabilizers. Dispersants or lubricants can be used, for example, for the purpose of dispersing inorganic fillers. The amount of dispersant or lubricant used is usually in the range of 0.01-4% by mass. Examples of the dispersant or lubricant include silane coupling agents, higher fatty acids such as oleic acid and stearic acid, metal soaps, polyacrylic acid, polymethacrylic acid, and salts thereof.

(Manufacturing method of printing paper)
The method for producing the printing paper of the present invention is not particularly limited, but it can be produced, for example, by applying a coating liquid for forming an antistatic layer on a thermoplastic resin film.

For the thermoplastic resin film, for example, cast molding, calendar molding, rolling molding, inflation molding, etc., in which the molten resin is extruded into a sheet by a single-layer or multi-layer T-die, I-die, etc. connected to a screw type extruder is used. It can be molded into a film. A thermoplastic resin film may be formed by cast molding or calendar molding a mixture of a thermoplastic resin and an organic solvent or oil, and then removing the solvent or oil. The material of each layer of the thermoplastic resin film is selected and blended so that each layer has the above-mentioned composition.

Examples of the method for laminating each layer of the thermoplastic resin film include a feed block, a multi-layer die method using a multi-manifold, an extrusion lamination method using a plurality of dies, and the like, and each method can be combined.

When the thermoplastic resin film contains a plurality of stretched layers, each layer may be stretched individually before being laminated, or may be stretched together after being laminated. Further, it may be laminated on the stretched layer and then stretched again.

As the stretching method, for example, a longitudinal stretching method using the peripheral speed difference of the roll group, a transverse stretching method using a tenter oven, a sequential biaxial stretching method combining these, a rolling method, and a simultaneous 2 stretching method using a combination of a tenter oven and a pantograph. Examples thereof include a shaft stretching method or a simultaneous biaxial stretching method using a combination of a tenter oven and a linear motor. Further, a simultaneous biaxial stretching (inflation molding) method in which the molten resin is extruded into a tube shape using a circular die connected to a screw type extruder and then air is blown into the molten resin can also be used.

The stretching temperature at the time of stretching can be set in consideration of the composition of each layer, for example, the melting point of the thermoplastic resin. For example, the stretching temperature is preferably equal to or lower than the melting point of the thermoplastic resin, and more preferably in the temperature range of 2 to 20 ° C. lower than the melting point. When the thermoplastic resin used is a non-crystalline resin, the stretching temperature is preferably in the range of the glass transition temperature or higher of the thermoplastic resin. Further, when the thermoplastic resin is a crystalline resin, the stretching temperature is at least the glass transition point of the non-crystalline portion of the thermoplastic resin and within the range of the melting point of the crystalline portion of the thermoplastic resin or less. Specifically, a temperature 2 to 60 ° C. lower than the melting point of the thermoplastic resin is preferable.

The stretching speed is not particularly limited, but is preferably in the range of 20 to 350 m / min from the viewpoint of stable stretch molding.
Further, the draw ratio can also be appropriately determined in consideration of the characteristics of the thermoplastic resin used. For example, when a thermoplastic resin film containing a homopolymer of propylene or a copolymer thereof is stretched in one direction, the draw ratio is usually about 1.2 times or more, preferably 2 times or more, more preferably. Is 5 times or more, while is usually 12 times or less, preferably 10 times or less. On the other hand, the draw ratio in the case of biaxial stretching is the area stretch ratio, which is usually 1.5 times or more, preferably 10 times or more, while usually 60 times or less, preferably 50 times or less. is there.

When a thermoplastic resin film containing a polyester resin is stretched in one direction, the draw ratio is usually 1.2 times or more, preferably 2 times or more, and usually 10 times or less. , Preferably 5 times or less. The draw ratio in the case of biaxial stretching is the area stretch ratio, which is usually 1.5 times or more, preferably 4 times or more, while usually 20 times or less, preferably 12 times or less.
If it is within the range of the draw ratio, the desired porosity can be obtained and the opacity can be easily improved. In addition, the thermoplastic resin film is less likely to break, and stable stretch molding tends to be possible.

<Surface treatment>
The thermoplastic resin film is preferably subjected to an oxidation treatment. By the oxidation treatment, the abundance ratio of polar groups on the film surface can be adjusted, and the atomic concentration of oxygen atoms can be adjusted. As a result, it is easy to obtain a chemical bond with the ink, and it is easy to improve the adhesion between the printing paper and the ink.
Examples of the oxidation treatment include corona discharge treatment, frame treatment, plasma treatment, glow discharge treatment, ozone treatment and the like, and these treatments can be combined. Of these, corona discharge treatment or frame treatment is preferable, and corona treatment is more preferable.

The amount of discharge when the corona discharge treatment is carried out is preferably 600 J / m ² (10 W / min / m ² ) or more, and more preferably 1,200 J / m ² (20 W / min / m ² ) or more. .. The discharge amount is preferably 12,000 J / m ² (200 W / min / m ² ) or less, and more preferably 10,800 J / m ² (180 W / min / m ² ) or less. The amount of discharge when the frame processing is performed is preferably 8,000 J / m ² or more, and more preferably 20,000 J / m ² or more. The discharge amount is preferably 200,000 J / m ² or less, and more preferably 100,000 J / m ² or less.

The antistatic layer is prepared by mixing an antistatic agent, an anchoring agent, a solvent, or the like to prepare the above-mentioned coating liquid for forming the antistatic layer, and using a coating device, a porous layer of a thermoplastic resin film. It can be formed by applying a coating liquid on top.

(Characteristics of printing paper)
<Thickness>
The thickness (total thickness) of the printing paper may be appropriately set according to the application or the required performance. The total thickness of the printing paper means the total thickness of each layer constituting the printing paper. The total thickness of the printing paper is preferably 51 μm or more, more preferably 63 μm or more, still more preferably 75 μm or more, preferably 550 μm or less, more preferably 400 μm or less, still more preferably 300 μm or less. If the printing paper has a total thickness in the above range, problems are unlikely to occur in offset printing, and the utility value as printing paper tends to increase.

The thickness of each layer constituting the printing paper is designed so that the total thickness is within the above range.
When the intermediate layer, the porous layer and the antistatic layer are provided on both sides of the base material layer, the thickness of each layer provided on both sides may be the same or different.

When the pores in the porous layer communicate with each other, it is possible to control the amount of oil absorption by changing the thickness of the porous layer. In this case, the thickness of the porous layer is preferably 3 μm or more, more preferably 5 μm or more, still more preferably 7 μm or more, preferably 20 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less. When the thickness of the porous layer is within the above range, picking is less likely to occur and a high oil absorption amount can be easily obtained.

The thickness of the intermediate layer is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 2 μm or more, preferably 20 μm or less, more preferably 10 μm or less, still more preferably 5 μm or less. When the thickness of the intermediate layer is within the above range, it becomes easy to prevent solvent attack and the like while obtaining good moldability.

The thickness of the antistatic layer can be controlled by the amount of the coating liquid for forming the antistatic layer. From the viewpoint of suppressing production cost or stickiness, or stabilizing the adhesion of ink over time, the coating amount is preferably 0.01 g / m ² or more in terms of solid content, and 0.02 g / m ² or more. More preferably, 3 g / m ² or less is preferable, 1 g / m ² or less is more preferable, and 0.5 g / m ² or less is further preferable.

<Surface specific resistance>
The surface intrinsic resistance of the printing paper is preferably 14 (logΩ) or less. When the surface specific resistance is within the above range, it is possible to improve the transportability in lithographic printing and reduce troubles due to static electricity in post-processing such as folding and bookbinding.

(Use of printing paper)
According to the printing paper of the present invention, it is possible to obtain a printed matter having high gloss and excellent weather resistance by printing. Therefore, it is useful as, for example, posters, pamphlets, catalogs, commercial printed matter such as signboards and menus, publications such as books, maps, book covers and bookmarks, and wrapping paper. Among these uses, the printing paper of the present invention is used outdoors under the influence of sunlight and rainwater, such as posters for elections and posters for signboards, and bathrooms such as posters, because of its high basic performance. It is useful in applications such as public baths, bathrooms, and other environments that are exposed to water, and in restaurants and other menus that may come into contact with water. Moreover, since it is possible to handle both the ink for pulp paper and the ink for synthetic paper, it is not necessary to replace the ink, and the workability of the printing process can be improved.

(Printed matter)
The printing paper of the present invention is not limited to printing methods such as offset printing, letterpress printing, flexo printing, and screen printing, and can be used for various printing methods, but is particularly suitable for offset printing. Further, various inks such as offset printing ink, letterpress printing ink, flexo printing ink, screen printing ink and the like can be used for the printing paper of the present invention, and in particular, offset printing ink can be used. preferable. The viscosity of the ink varies depending on the type of ink, the printing method, and the like, and is not particularly limited.

Although it was difficult to apply to synthetic paper, the printing paper of the present invention has excellent printability and ink even for oxidative polymerization type ink containing a relatively large amount of solvent, which has been widely used for pulp paper. Has dryness. Therefore, even when the printing paper of the present invention is used instead of the pulp paper, it is not necessary to replace the ink. Further, the printing paper of the present invention also has excellent printability and ink drying property with respect to inks for synthetic papers having few evaporative drying type components, penetration drying type components and the like, ultraviolet curable inks and the like. That is, the printing paper of the present invention can be applied to any of the above-mentioned inks of various printing methods, and the versatility of the ink is high. Therefore, according to the present invention, there is provided a printed matter including the above-mentioned printing paper and a printing layer provided on the above-mentioned printing paper. The print layer can be formed by printing with an ink such as the above-mentioned oxidation polymerization type ink.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. In addition, the description of "part", "%", etc. in the Examples means the description of the mass standard unless otherwise specified.

(Preparation of coating liquid)
Coating liquids 1 to 5 for forming an antistatic layer were prepared as follows.

<Coating liquid 1>
An antistatic agent (trade name: Saftmer ST-3200, manufactured by Mitsubishi Chemical Corporation, quaternary ammonium salt) was diluted by adding pure water so that the solid content was 1.2% by mass to obtain a coating liquid 1. ..

<Coating liquid 2>
Antistatic agent (trade name: Saftmer ST-3200, manufactured by Mitsubishi Chemical Co., Ltd., quaternary ammonium salt) has a solid content of 1.2% by mass, modified polyethyleneimine (trade name: Saftmer AC-2000, manufactured by Mitsubishi Chemical Co., Ltd.) Pure water was added and diluted so that the solid content of the secondary and tertiary amine-containing compounds) was 0.23% by mass to obtain a coating liquid 2.

<

Coating liquids

3 and 4>
In the coating liquid 2, the solid content of modified polyethyleneimine (trade name: Saftmer AC-2000, manufactured by Mitsubishi Chemical Corporation, secondary and tertiary amine-containing compounds) was 0.38% by mass and 0.5% by mass, respectively. Pure water was added to dilute the

coating liquids

3 and 4 to obtain the

respective coating liquids

3 and 4.

<Coating liquid 5>
Antistatic agent (trade name: Saftmer ST-3200, manufactured by Mitsubishi Chemical Co., Ltd., quaternary ammonium salt) has a solid content of 1.2% by mass, modified polyethyleneimine (trade name: Polymin SK, manufactured by BASF, manufactured by BASF), grade 3 The solid content of the amine-containing compound) is 0.25% by mass, and the solid content of the self-crosslinkable cross-linking agent (trade name: WS4082, manufactured by Seikou PMC, secondary amine and epoxy group-containing compound) is 0.3% by mass. Pure water was added and diluted to obtain a coating liquid 5.

Table 1 shows the compositions of the coating liquids 1 to 5.

(Example 1)
(I) Polypropylene resin (trade name: Novatec PP MA3, manufactured by Nippon Polypro Co., Ltd., MFR (230 ° C, 2.16 kg load): 11 g / 10 minutes, melting energy: 95 J / g) 80 parts by mass, heavy calcium carbonate particles (Product name: Softon 1800, manufactured by Bihoku Powder Industry Co., Ltd., average particle size: 1.25 μm) 19.5 parts by mass, and titanium dioxide particles (trade name: Typake CR-60, manufactured by Ishihara Sangyo Co., Ltd., average particle size: The resin composition (5) mixed with 0.21 μm) 0.5 parts by mass was melt-kneaded with an extruder set at 270 ° C. This was extruded into a sheet and cooled by a cooling roll to obtain an unstretched sheet. Next, the unstretched sheet was heated again to 150 ° C., and then stretched 4.8 times in the sheet flow direction by utilizing the speed difference between the rolls to obtain a longitudinally stretched resin film.

(II) Polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation) 46 parts by mass, maleic anhydride-modified polypropylene resin (trade name: Modic P928, manufactured by Mitsubishi Chemical Corporation, melting point: 155 to 165 ° C., specific gravity: 0 . 89-0.91 g / m ³ , melting energy: 89 J / g) 1 part by mass, light calcium carbonate particles surface-treated with fatty acids (particle size distribution D10-D90: 0.6 μm, D50: 0.5 μm) 52. The resin composition (1), which was a mixture of 5 parts by mass and 0.5 parts by mass of titanium dioxide particles (trade name: Taipei CR-60, manufactured by Ishihara Sangyo Co., Ltd.), was mixed with a high-speed mixer. Then, using a twin-screw kneading extruder in which the cylinder temperature was set to 210 ° C., melt kneading was performed at a rotation speed of 600 rpm while degassing at the vent holes.

On the other hand, polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation) 48.5 parts by mass, ethylene-cyclic olefin copolymer (trade name: Apel 6011T, manufactured by Mitsui Chemicals, Inc., MFR (230 ° C, 2.16 kg) Load): 26 g / 10 minutes, melting energy: 0 J / g) 48.5 parts by mass, and 3 parts by mass of heavy calcium carbonate particles (trade name: Softon 1800, manufactured by Bihoku Powder Industry Co., Ltd.) (4) was melt-kneaded with an extruder set at 270 ° C.
Next, these resin compositions were supplied to one multilayer die and laminated inside the die. This laminated body is co-extruded from a die into a sheet, and laminated on one surface of the vertically stretched resin film obtained in the step (I) above so that the layer of the resin composition (1) is on the outside. A laminated sheet having a three-layer structure was obtained.

(III) The resin composition (1) and the resin composition (4) are melt-kneaded using two extruders different from the above (II) in the same procedure as the above (II), and then the above (III). It was supplied to a multilayer die different from II) and laminated inside the die. This laminated body is co-extruded from the die into a sheet, and is placed on the surface of the vertically stretched resin film side (layer side of the resin composition (5)) of the three-layer structure laminated sheet obtained in the step (II) above. , The resin composition (1) was laminated so that the layer was on the outside. As a result, the porous layer (layer of the resin composition (1)) / intermediate layer (layer of the resin composition (4)) / base material layer (layer of the resin composition (5)) / intermediate layer (resin composition). A laminated sheet having a five-layer structure was obtained in which the layer (4)) / the porous layer (the layer of the resin composition (1)) was laminated in this order.

(IV) The obtained 5-layer laminated sheet was cooled to 60 ° C., reheated to 150 ° C., stretched 9 times in the sheet width direction using a tenter, and then annealed at 165 ° C. did. Then, after cooling to 60 ° C. again, the selvage portion is slit, and a thermoplastic resin film having a five-layer structure (number of stretching axes of each layer: 1-axis stretching / 1-axis stretching / 2-axis stretching / 1-axis stretching / 1). Axial stretching), total thickness: 130 μm, thickness of each layer: (1) / (4) / (5) / (4) / (1) = 8 μm / 3 μm / 108 μm / 3 μm / 8 μm) was obtained.

(V) A high-frequency power supply (device name: AGF-B10, manufactured by Kasuga Denki Co., Ltd.), an aluminum electrode with a length of 0.8 m, and a silicone film roll as a treater roll are used, and the gap between the electrode and the roll is 5 mm. While passing the thermoplastic resin film obtained in (IV) at a line processing speed of 25 m / min, corona discharge was performed on both surfaces of the film under the condition of an applied energy density of 1800 J / m ² (30 W / min / m ² ). Processing was performed.

(VI) Apply the coating liquid 1 to both surfaces of the thermoplastic resin film after the corona discharge treatment using a roll coater so that the solid content of the coating film after drying is 0.02 g / m ² per side. did. The coating film was dried and solidified to obtain the printing paper of Example 1.

(Example 2)
In Example 1, the discharge amount of the resin composition of each layer was changed to increase the total thickness to 130 μm (thickness of each layer: (1) / (4) / (5) / (4) / (1) = 5 μm / 3 μm / The printing paper of Example 2 was obtained in the same procedure as in Example 1 except that it was set to 114 μm / 3 μm / 5 μm).

(Examples 3 and 4)
The printing papers of Examples 3 and 4 were obtained in the same procedure as in Example 1 except that the coating liquids in (VI) of Example 1 were changed to

coating liquids

2 and 5, respectively.

(Example 5)
39 parts by mass of polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation), maleic anhydride-modified polypropylene resin (trade name: Modic P928, manufactured by Mitsubishi Chemical Corporation) 1 of the resin composition (1) of Example 1. Parts by mass, light calcium carbonate particles surface-treated with fatty acids (particle size distribution D10-D90: 0.6 μm, D50: 0.5 μm) 59.5 parts by mass, and titanium dioxide particles (trade name: Taipei CR-60, Ishihara Sangyo) The printing paper of Example 5 was obtained in the same procedure as in Example 1 except that the resin composition (2) was mixed with 0.5 parts by mass.

(Example 6)
The resin composition (1) of Example 1 is a polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation), 44 parts by mass, maleic anhydride-modified polypropylene resin (trade name: Modic P928, manufactured by Mitsubishi Chemical Corporation) 1 Parts by mass, heavy calcium carbonate particles (particle size distribution D10-D90: 2.4 μm, D50: 1.2 μm) 54.5 parts by mass, and titanium dioxide particles (trade name: Typake CR-60, manufactured by Ishihara Sangyo Co., Ltd.) 0 The printing paper of Example 6 was obtained in the same procedure as in Example 1 except that 5 parts by mass was changed to the mixed resin composition (3).

(Example 7)
The printing paper of Example 7 was obtained in the same procedure as in Example 1 except that the resin composition (1) was replaced with the resin composition (8) to form a porous layer in Example 1.
The resin composition (8) contains 42.5 parts by mass of polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation) and 1 part by mass of polypropylene resin (trade name: Modic P928, manufactured by Mitsubishi Chemical Corporation) modified with maleic anhydride. , Soft polypropylene (trade name: Toughmer PN2060, manufactured by Mitsui Chemicals, Ltd., melting energy 10 J / g) 3.5 parts by mass, light calcium carbonate particles surface-treated with fatty acids (particle size distribution D10-D90: 0.6 μm, D50: Includes 52.5 parts by mass (0.5 μm) and 0.5 parts by mass of titanium dioxide particles (trade name: Typake CR-60, manufactured by Ishihara Sangyo Co., Ltd.).

(Example 8)
The printing paper of Example 8 was obtained in the same procedure as in Example 1 except that the resin composition (1) was replaced with the resin composition (9) to form a porous layer in Example 1.
The resin composition (9) is a polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation) 38 parts by mass, a maleic anhydride-modified polypropylene resin (trade name: Modic P928, manufactured by Mitsubishi Chemical Corporation), 1 part by mass, soft. Polypropylene (trade name: Toughmer PN2060, manufactured by Mitsui Chemicals, Inc.) 8 parts by mass, light calcium carbonate particles surface-treated with fatty acids (particle size distribution D10-D90: 0.6 μm, D50: 0.5 μm) 52.5 parts by mass, And titanium dioxide particles (trade name: Typake CR-60, manufactured by Ishihara Sangyo Co., Ltd.) containing 0.5 parts by mass.

(Example 9)
The printing paper of Example 9 was obtained in the same procedure as in Example 1 except that the resin composition (1) was replaced with the resin composition (10) to form a porous layer in Example 1.
The resin composition (10) is a polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation), 36 parts by mass, a maleic anhydride-modified polypropylene resin (trade name: Modic P928, manufactured by Mitsubishi Chemical Corporation), 1 part by mass, soft. Polypropylene (trade name: Toughmer PN2060, manufactured by Mitsui Chemicals, Inc.) 10 parts by mass, light calcium carbonate particles surface-treated with fatty acids (particle size distribution D10-D90: 0.6 μm, D50: 0.5 μm) 52.5 parts by mass, And titanium dioxide particles (trade name: Typake CR-60, manufactured by Ishihara Sangyo Co., Ltd.) containing 0.5 parts by mass.

(Example 10)
The printing paper of Example 10 was obtained in the same procedure as in Example 1 except that the resin composition (4) was replaced with the resin composition (11) to form an intermediate layer in Example 1.
The resin composition (11) is a polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation) 48.5 parts by mass, an ethylene-cyclic olefin copolymer (trade name: Appel 6011T, manufactured by Mitsui Chemicals, Inc.) 48. Includes 5 parts by mass and 3 parts by mass of calcium carbonate particles (trade name: cube80KAS, manufactured by Maruo Calcium Co., Ltd., average particle diameter 8 μm).

(Example 11)
The printing paper of Example 11 was obtained in the same procedure as in Example 1 except that the resin composition (4) was replaced with the resin composition (12) to form an intermediate layer in Example 1.
The resin composition (12) contains 45 parts by mass of a polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation), 45 parts by mass of an ethylene-cyclic olefin copolymer (trade name: Apel 6011T, manufactured by Mitsui Chemicals, Inc.). And 10 parts by mass of calcium carbonate particles (trade name: cube80KAS, manufactured by Maruo Calcium Co., Ltd.).

(Example 12)
The printing paper of Example 12 was obtained in the same procedure as in Example 11 except that the thickness of the intermediate layer was changed to 6 μm in Example 11.

(Example 13)
The printing paper of Example 13 was obtained in the same procedure as in Example 1 except that the resin composition (4) was replaced with the resin composition (13) to form an intermediate layer in Example 1.
The resin composition (13) contains 40 parts by mass of a polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation), 40 parts by mass of an ethylene-cyclic olefin copolymer (trade name: Apel 6011T, manufactured by Mitsui Chemicals, Inc.). And 20 parts by mass of calcium carbonate particles (trade name: cube80KAS, manufactured by Maruo Calcium Co., Ltd.).

(Example 14)
The printing paper of Example 14 was obtained in the same procedure as in Example 1 except that the resin composition (4) was replaced with the resin composition (14) to form an intermediate layer in Example 1.
The resin composition (14) is a polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation), 45 parts by mass, an ethylene-cyclic olefin copolymer (trade name: Apel 6011T, manufactured by Mitsui Chemicals, Inc.), 45 parts by mass. And 10 parts by mass of heavy calcium carbonate (trade name: Softon 1800, manufactured by Bihoku Powder Industry Co., Ltd.).

(Example 15)
The printing paper of Example 15 was obtained in the same procedure as in Example 1 except that the resin composition (4) was replaced with the resin composition (15) to form an intermediate layer in Example 1.
The resin composition (15) contains 45 parts by mass of a polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation), 45 parts by mass of an ethylene-cyclic olefin copolymer (trade name: Apel 6011T, manufactured by Mitsui Chemicals, Inc.). And 10 parts by mass of heavy calcium carbonate (trade name: R50A, manufactured by Maruo Calcium Co., Ltd., average particle size: 15 μm).

(Comparative Examples 1 and 2)
The printing papers of Comparative Examples 1 and 2 were obtained by performing the same procedure as in Example 1 except that the

coating liquids

3 and 4 were used as the coating liquid in the step (VI) of Example 1. It was.

(Comparative Example 3)
Instead of the resin composition (1) of Example 1, 51.5 parts by mass of a propylene homopolymer (manufactured by Japan Polypropylene Corporation, trade name Novatec PP MA-3), high-density polyethylene (manufactured by Japan Polychem Corporation, trade name HJ580) Density 0.950 g / cm ³ ) 3.5 parts by mass, heavy calcium carbonate (particle size distribution D10-D90: 5.1 μm, D50: 1.5 μm) 42 parts by mass, titanium dioxide particles (trade name: Typek CR- 60, manufactured by Ishihara Sangyo Co., Ltd.) After mixing the resin composition (6) consisting of 3 parts by mass with a high-speed mixer, while degassing at the vent hole using a twin-screw kneading extruder with the cylinder temperature set to 240 ° C. The printing paper of Comparative Example 3 was obtained in the same procedure as in Example 1 except that the mixture was melt-kneaded at a rotation speed of 600 rpm. The printing paper of Comparative Example 3 has a five-layer structure (number of stretched axes of each layer: 1-axis stretch / 1-axis stretch / 2-axis stretch / 1-axis stretch / 1-axis stretch), total thickness: 130 μm (thickness of each layer: (6). ) / (4) / (5) / (4) / (6) = 8 μm / 3 μm / 108 μm / 3 μm / 8 μm)).

(Comparative Example 4)
Instead of the resin composition (1) of Example 1, a polypropylene resin (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation), 46 parts by mass, a maleic anhydride-modified polypropylene resin (trade name: Modic P928, manufactured by Mitsubishi Chemical Corporation) ) 1 part by mass, heavy calcium carbonate (particle size distribution D10-D90: 5.1 μm, D50: 1.5 μm) 52.5 parts by mass, and titanium dioxide particles (trade name: Typake CR-60, manufactured by Ishihara) 0 The printing paper of Comparative Example 4 was obtained in the same procedure as in Example 1 except that the resin composition (7) in which 5 parts by mass was mixed was melt-kneaded at a rotation speed of 600 rpm while degassing at the vent holes. It was. The printing paper of Comparative Example 4 has a five-layer structure (number of stretched axes of each layer: 1-axis stretch / 1-axis stretch / 2-axis stretch / 1-axis stretch / 1-axis stretch, total thickness: 130 μm (thickness of each layer: (6)). / (4) / (5) / (4) / (6) = 8 μm / 3 μm / 108 μm / 3 μm / 8 μm)).

(Comparative Example 5)
In Example 1, the discharge amount of the resin in each layer was changed to increase the total thickness to 130 μm (thickness of each layer: (1) / (4) / (5) / (4) / (1) = 3 μm / 3 μm / 118 μm / The printing paper of Comparative Example 5 was obtained in the same procedure as in Example 1 except that the thickness was 3 μm / 3 μm).

Table 2A and Table 2B show the composition of the resin composition.

Table 3 shows the composition of the printing paper of each example and each comparative example. Each printing paper has a layer structure of an antistatic layer / a porous layer / an intermediate layer / a base material layer / an intermediate layer / a porous layer / an antistatic layer, but one surface side of the base material layer and the other Since the composition of the antistatic layer / porous layer / intermediate layer does not change from that of the surface side, Table 3 shows only the composition of the antistatic layer / porous layer / intermediate layer provided on one surface of the base material layer. ..

Various measurements were carried out on the printing papers of each Example and Comparative Example under the following measurement conditions.
<Vacancy rate>
The porosity of the porous layer was determined from the ratio of the area occupied by the pores in a certain region of the cross section of the printing paper observed with an electron microscope. Specifically, an arbitrary part of the printing paper to be measured is cut out, embedded in epoxy resin and solidified, and then cut perpendicularly to the surface direction of the printing paper to be measured using a microtome, and the cutting is performed. It was attached to the observation sample table so that the surface became the observation surface. Gold or gold-palladium is deposited on the observation surface, and the pores of the printing paper are observed at an arbitrary magnification (for example, 500 to 3000 times magnification) that is easy to observe with an electron microscope, and the observed area is imaged. Imported as data. The obtained image data was subjected to image processing by an image analyzer, and the porous layer was discriminated from the boundary between the layers to determine the area ratio (%) of the pore portion in a certain region of the porous layer. The vacancy rate (%) was obtained by averaging the measured values at any 10 or more observation points.

<Surface specific resistance>
In accordance with JIS-K-6911: 1995, the printing paper is left in an atmosphere of a temperature of 23 ° C. and a relative humidity of 50 RH% for 2 hours or more to adjust the state to a constant value, and then the surface specific resistance value of the surface on the antistatic layer side. (LogΩ) was measured using an insulation resistance tester (model number: DSM-8103, manufactured by Toa Denpa Kogyo Co., Ltd.).

<Oil absorption>
A sample was prepared by cutting out a printing paper into a square having a length and width of 100 mm, and the mass thereof was measured. Mineral Oil (manufactured by Wako Pure Chemical Industries, Ltd .: density 0.84) was placed in a container, adjusted to a liquid temperature of 20 ° C., and floated so that only one side of the cut-out sample was attached to Mineral Oil to absorb oil. After floating for 5 seconds, the excess Mineral Oil adhering to the oil-absorbed surface was thoroughly wiped off. After wiping, the mass of the sample was measured again, and the oil absorption amount was calculated by the following formula from the area where the oil was absorbed, that is, the area of the entire surface of the cut out sample.
Oil absorption (g / m ² ) =
{(Mass after oil absorption (g))-(Mass before oil absorption (g))} / (Area absorbed oil (m ² ))

<Atomic concentration ratio of nitrogen atoms on the surface>
The ratio (%) of the atomic concentration (atom%) of nitrogen atoms to the total atomic concentrations (atom%) of carbon atoms and nitrogen atoms on the surface of the printing paper was measured by XPS under the following measurement conditions.
Equipment: K-Alpha
Excited X-ray: AlKα
X-ray output: 72W
X-ray diameter: 400 μm
Photoelectron escape angle: 45 °

Specifically, the measurement is performed by a narrow scan, and the ratio of the peak area of the N1s peak of the nitrogen atom to the sum of the peak area of the C1s peak of the carbon atom and the peak area of the N1s peak of the nitrogen atom is determined by the atom of the nitrogen atom. It was calculated as a concentration ratio.

(Evaluation)
The printing papers of each Example and Comparative Example were printed by the following methods, and the obtained printed matter was evaluated for the effect of suppressing chemical ghosts, ink drying property, and edge picking.

<Suppressive effect of chemical ghost>
Two sheets of printing paper were prepared. Printing was performed on one side of one of the printing sheets using the following printing machine and ink so that the transfer amount of the ink was 1.5 g / m ² . For printing, a printing roll was used, which prints only on both ends of the printing paper in the width direction.
Printing machine: RI tester (manufactured by Kokubo Precision Co., Ltd.)
Ink: Fusion-G MK ink (DIC, oxidative polymerization type oil-based ink for pulp paper (solvent 5 to 15%))

After placing the obtained printed matter A on the bat with the printed side facing up, another printing paper is immediately placed on the printed side of the printed matter A, and the mass is the same as the paper size from the printed matter A. A 1 kg weight was placed on it. After placing the vat in a room with a temperature of 35 ° C. and a relative humidity of 80 RH% for 72 hours, the weight is removed and printing is performed on the lower surface of the top printing paper (the surface overlapped with the printed surface of printed matter A) for 24 hours. It was dried. The second sheet was printed in the same manner as the printed matter A except that a printing roll for printing in the entire width direction was used.

FIG. 2 shows the printed surface A1 of the printed matter A and the printed surface B2 of the printed matter B.
As shown in FIG. 2, the print surface A1 of the printed matter A includes two print areas Ra located on both end sides in the width direction with an interval of 2 cm. The size of each print area Ra from one end to the other end in the width direction is 24 cm. On the other hand, the print surface B1 of the printed matter B includes one print area Rb having a size of 24 cm in the width direction. The positions of both ends of the print area Rb in the width direction are the same as the positions of both ends of each print area Ra in the width direction.

Among the print areas Rb of the printed matter B, the ink density D1 of the print area Rb1 that was in contact with each print area Ra of the printed matter A and the ink density D2 of the print area Rb2 that was not in contact were measured. At the time of measurement, the ink densities D1 and D2 were measured at a position 5 to 10 mm away from the boundary of the print area Rb2 that was in contact with the print area Ra of the printed matter A and not in contact with the print area Rb2 of the printed matter B. did. The ink density was measured using X-Rite 530 (manufactured by X-Rite Co., Ltd.). The density difference Δ between the measured ink densities D1 and D2 was calculated by the following formula.
Concentration difference Δ = D2-D1

The effect of suppressing chemical ghosts was evaluated based on the obtained concentration difference Δ according to the following criteria.
⊚: Δ ≦ 0.05, and the ink is transferred well. No difference can be confirmed visually, and chemical ghosts are sufficiently suppressed.
〇: 0.05 <Δ≤0.2, the ink is transferred well, and chemical ghosts are suppressed. ×: 0.2 <Δ, and the ink is not sufficiently transferred. , Chemical ghost suppression is not enough

<Ink drying property>
Kiku four-dimensional extension 4-color offset printing machine (device name: Ryobi 524GX, manufactured by Ryobi MHI Graphic Technology Co., Ltd.), and oxidation polymerization type oil-based offset ink (trade name: Fusion-GMK ink, indigo, red, transparent yellow, DIC The printing papers of each Example and Comparative Example were subjected to oil-based offset printing. The oil-based offset ink used is commercially available as an ink for pulp paper. The solvent amount of each oil-based offset ink is 5 to 15% for black ink, 15 to 25% for indigo, 15 to 25% for red, and 20 to 30% for transparent yellow.

The printing conditions include PS version (product name: XP-F, manufactured by Fuji Film Co., Ltd.), blanket (product name: D-3000, manufactured by T & K TOKA), powder (product name: Nikka Rico AS-100S, manufactured by Nikka Co., Ltd.). ), Sampling water (H solution (trade name: Astromark 3, manufactured by Nikken Kagaku Kenkyusho) 1.0% and IPA 5.0% added, water temperature 10 ° C.) was used.
As printing conditions, the temperature in the printing room is adjusted to 20 to 25 ° C., the relative humidity is adjusted to 40 to 60 RH%, the color order is black, indigo, red, and transparent yellow, and the printing speed is 8000 sheets / hour. And said. At this time, a pattern was printed in which a solid printing part of each color of black, indigo, red, and transparent yellow and a 400% solid printing part on which all colors of black, indigo, red, and transparent yellow were printed were arranged in the printing flow direction. ..
The amount of ink transfer is adjusted so that the densities of the single color solid parts of black, indigo, red, and transparent yellow are 1.85, 1.55, 1.45, and 1.00, respectively, and the dampening water does not cause background stains. More than 200 sheets were printed under the condition that the level was reduced as much as possible, and after printing, the sheets were sequentially stored from the bottom.

The ink drying property was evaluated as follows for the printed matter extracted from the portion about 50 sheets below the upper part of the stacked printed matter every hour after printing.
〇: 400% solid printing part was set and dried within 6 hours Δ: 400% solid printing part was set and dried within 12 hours over 6 hours ×: 400% solid printing part was set and dried within 12 hours Did not

<Edge picking>
Oil-based offset printing was performed on the printing papers of the respective examples and comparative examples under the same printing conditions as the above <ink dryness>. Edge picking was evaluated as follows for the printed matter extracted from the portion about 50 sheets below the top of the stacked printed matter.
⊚: There is no blank part at the end of the 400% solid printing part, and it is as the pattern of the printing plate. 〇: 400% solid There are very few blank parts at the end of the printing part. △: 400% solid Blanks are scattered at the edges of the printed part ×: 400% solid Blanks are continuously generated at the edges of the printed part

Table 4 shows the evaluation results. In addition, "-" in Table 4 indicates that the papers were stuck to each other and the chemical ghost suppressing effect could not be evaluated.

As shown in Table 4, it can be seen that the printing papers of Examples 1 to 6 and 14 are all excellent in ink drying property and that chemical ghosts are effectively suppressed. Further, the printing papers of Examples 7 to 9 have less edge picking, and the printing papers of Examples 10 to 13 and 15 have a more excellent effect of suppressing chemical ghosts.

On the other hand, in the printing papers of Comparative Examples 1 to 5, the ink was not sufficiently dried, and chemical ghosts were generated, resulting in a difference in density. Further, according to Comparative Example 4, it can be seen that even if the pore ratio is high, the amount of oil absorbed is not sufficient, so that the ink is not sufficiently dried.

This application claims priority based on Japanese Patent Application No. 2019-70505, which is a Japanese patent application filed on April 2, 2019, and incorporates all the contents of the Japanese patent application.

10 ... Printing paper, 1 ... Thermoplastic resin film, 2,2a ... Porous layer, 3,3a ... Antistatic layer, 4 ... Base material layer, 5,5a ... Middle layer

Claims

A printing paper having a thermoplastic resin film including a porous layer and an antistatic layer provided on the porous layer of the thermoplastic resin film.
The oil absorption of the printing paper is 1.0 g / m 2 or more.
When the surface of the printing paper on the antistatic layer side is measured by X-ray photoelectron spectroscopy, the ratio of the atomic concentration of nitrogen atom to the total atomic concentration of nitrogen atom and carbon atom is 3.0% or less. ,
Printing paper.
The antistatic layer contains a nitrogen-containing compound and
The nitrogen-containing compound contains a quaternary nitrogen-containing compound.
The content of the quaternary nitrogen-containing compound in the nitrogen-containing compound is 50% by mass or more.
The printing paper according to claim 1.
The nitrogen-containing compound contains a primary nitrogen-containing compound or a secondary nitrogen-containing compound.
The content of the primary nitrogen-containing compound and the secondary nitrogen-containing compound in the nitrogen-containing compound is 20% by mass or less.
The printing paper according to claim 1.
The antistatic layer contains a nitrogen-containing compound and a cross-linking agent.
The nitrogen-containing compound contains a primary nitrogen-containing compound or a secondary nitrogen-containing compound.
The printing paper according to claim 1.
A printing paper having a thermoplastic resin film including a porous layer and an antistatic layer provided on the porous layer of the thermoplastic resin film.
The oil absorption of the printing paper is 1.0 g / m 2 or more.
The antistatic layer contains a nitrogen-containing compound, and the total content of primary or secondary nitrogen in the total nitrogen contained in the nitrogen-containing compound is 10% or less.
Printing paper.
The porous layer contains a thermoplastic resin and a filler, and the porous layer contains a thermoplastic resin and a filler.
The particle size distribution D10-D90 of the filler is 4 μm or less.
The printing paper according to any one of claims 1 to 5.
The porous layer contains a soft polyolefin resin as the thermoplastic resin.
The printing paper according to any one of claims 1 to 6.
It has an intermediate layer between the base material layer and the porous layer,
The intermediate layer contains a filler having an average particle size larger than the thickness of the intermediate layer.
The printing paper according to any one of claims 1 to 7.
The porous layer is a stretched film stretched in at least one axial direction.
The printing paper according to any one of claims 1 to 8.
The printing paper according to any one of claims 1 to 9 and
The printing layer provided on the printing paper and
Have a printed matter.
The print layer is formed by an oxidative polymerization type ink.
The printed matter according to claim 10.