JP2023171256A - Printed material - Google Patents

Abstract

To provide a printed material with sufficient gloss and excellent slipperiness.SOLUTION: A printed material 10 includes: a printed base 1 with a surface 1a subjected to printing; an ink layer 3 provided on the surface 1a; and a varnish layer 5 provided so as to cover the ink layer 3. The varnish layer 5 includes a dried product of aqueous varnish. The varnish layer 5 has a surface 5a with an arithmetical average height (Sa) and a maximum height (Sz), which respectively satisfy following conditions: 0.35 μm≤Sa≤0.52 μm and 0.4 μm≤Sz≤11.0 μm.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to printed matter.

A surface protective layer is often provided on the surface of printed matter in order to increase the glossiness of the surface. Conventionally, the surface protective layer was formed by curing a coating film made of a UV curable resin composition by UV irradiation, but due to the recent rise in environmental awareness, the surface protective layer is now formed using water-based varnish. Development of technology to do this is progressing (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2003-340357

However, the surface of the layer formed by the water-based varnish does not necessarily have sufficient surface gloss, and may lack gloss. Furthermore, in the manufacturing process of printed matter, it is required that the printed matter be suitably slippery, but when the surface protective layer is formed of a water-based varnish, the slipperiness of the printed matter tends to deteriorate.

Therefore, one aspect of the present disclosure aims to provide a printed matter having sufficient gloss and good slipperiness.

The present disclosure provides at least the following [1] to [4].

[1]
a printing substrate having a surface to be printed;
an ink layer provided on the surface;
a varnish layer provided to cover the ink layer,
The varnish layer contains a dried water-based varnish,
A printed matter in which the arithmetic mean height (Sa) and maximum height (Sz) of the surface of the varnish layer each satisfy the following.
0.35μm≦Sa≦0.52μm
0.4μm≦Sz≦11.0μm

[2]
The printed matter according to [1], wherein the water-based varnish is an emulsion-type water-based varnish that combines different resins.

[3]
The printed matter according to [2], wherein the water-based varnish contains a silicone resin and an acrylic resin.

[4]
The printed matter according to any one of [1] to [3], wherein the varnish layer has a surface kurtosis (Sku) of 4.0 or less.

According to one aspect of the present disclosure, it is possible to provide a printed matter with sufficient gloss and good slipperiness.

FIG. 1 is a cross-sectional view schematically showing an embodiment of a printed matter according to the present disclosure. FIG. 2 is a cross-sectional view schematically showing an embodiment of the method for manufacturing the printed matter of FIG.

In this specification, a numerical range indicated using "~" indicates a range that includes the numerical values written before and after "~" as the minimum and maximum values, respectively. Furthermore, unless specified otherwise, the units of numerical values written before and after "~" are the same. In the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with the value shown in the Examples. Moreover, the upper limit values and lower limit values described individually can be combined arbitrarily.

Embodiments of the present disclosure will be described in detail below. Note that the present disclosure is not limited to the following embodiments.

The printed material 10 shown in FIG. 1 includes a printed material 1 having a surface (printed surface) 1a to be printed, an ink layer 3 provided on the surface 1a, and a varnish provided to cover the ink layer 3. layer 5. The printed matter 10 has a pattern area 7 where the ink layer 3 exists between the printed material 1 and the varnish layer 5, and a non-picture region 8 where the ink layer 3 does not exist between the printed material 1 and the varnish layer 5. . However, the printed matter of the present disclosure does not need to have the non-picture area 8. The printed matter 10 is, for example, a container for packaging food or the like.

The printing material 1 is, for example, paper. When the printing material 1 is paper, a varnish layer having the desired surface properties (arithmetic mean height (Sa) and maximum height (Sz)) described later is likely to be formed using a water-based varnish. Specific examples of paper include high quality paper, special high quality paper, coated paper, art paper, cast coated paper, imitation paper, and kraft paper. The mass per unit area of paper is, for example, 20 to 500 g/m ² , and may be 25 to 400 g/m ² . The printing material 1 may be made of a composite material including paper and a resin material, for example.

The ink layer 3 is a layer formed of ink (eg, oil-based ink), and includes a cured product (eg, dried product) of the ink. The ink layer 3 may be a layer formed by an offset printing method.

The ink includes, for example, a colorant and a binder resin. As the ink, for example, vegetable oil ink can be used. Biomass ink may be used instead of vegetable oil ink. The biomass ink includes, for example, a colorant, a polyol compound, and an isocyanate compound (or a cured product thereof). In this case, at least one of the polyol compound and the isocyanate compound is a biomass-derived component. The biomass ink may be a UV-curable biomass ink. That is, the ink layer 3 may be a layer containing a cured product of UV-curable biomass ink.

The ink is preferably an oil-based ink from the viewpoint of easily forming a varnish layer having the desired surface properties (arithmetic mean height (Sa) and maximum height (Sz)) described below. The reason why such an effect is obtained is not clear, but when the ink is oil-based, the time required for forming an ink layer (for example, the drying process of the ink) becomes longer, which causes the oil-based ink to level out. Since the surface of the ink layer tends to become smoother, it is presumed that the surface condition of the varnish layer is influenced by the surface condition of the ink layer and becomes smoother.

The content of the colorant in the ink may be 10% by mass or more, 50% by mass or less, and 10 to 50% by mass, based on the total solid content of the ink. By using an ink with a coloring agent content within the above range, clear patterns can be easily obtained. In addition, since the above content is the content based on the total solid content of the ink, the range that the content of the colorant in the ink layer (based on the total solid content of the ink layer) can be is also within the same range as above. be.

Ink typically further contains a solvent in addition to the colorant and binder resin. The solvent is, for example, a volatile organic compound (VOC) such as toluene, ethyl acetate, xylene, n-butyl acetate, cyclohexanol, isobutyl alcohol, and the like. The ink may be a concrete ink from the viewpoint of easily obtaining a clear pattern. Container ink is an ink that has a smaller amount of solvent (for example, 60% by mass or less) than normal ink. The content of the solvent in the ink may be 60% by mass or less, 30% by mass or more, and 30 to 60% by mass, based on the total amount of the oil-based ink. In addition, the content of the above-mentioned solvent is the content of the solvent in the ink used for forming the ink layer, and it is preferable that the ink layer itself does not contain the solvent.

The thickness of the ink layer 3 is not particularly limited, but may be 0.1 to 1.8 μm, 0.2 to 1.5 μm, 0.4 to 1.3 μm, or 0.6 to 1.2 μm. There may be. The thickness of the ink layer 3 is the thickness of the portion indicated by _T3 in FIG. 1, and means the distance from the surface 1a of the printing material 1 to the surface 3a of the ink layer 3. The thickness of the ink layer 3 can be determined using an optical microscope by interference spectroscopy that utilizes light interference phenomena.

The varnish layer 5 contains a dried aqueous varnish. The varnish layer 5 can be formed by forming a coating film using an aqueous varnish and then drying the coating film. The varnish layer 5, like the ink layer 3, may be a layer formed by an offset printing method. Here, the term "aqueous varnish" refers to a varnish containing water and a resin (for example, an aqueous resin). The water-based varnish may further contain a surfactant or the like.

The varnish layer 5 has a substantially smooth surface, and the arithmetic mean height (Sa) and maximum height (Sz) of the surface 5a of the varnish layer 5 measured in accordance with ISO25178 each satisfy the following.
0.35μm≦Sa≦0.52μm
0.4μm≦Sz≦11.0μm

The arithmetic mean height (Sa) is the average height of the unevenness on the measurement surface, and the smaller the arithmetic mean height (Sa), the smaller the height of the unevenness on the surface on average and the higher the smoothness of the surface. It means that. In addition, the maximum height (Sz) is the maximum height of the unevenness on the measurement surface, and the smaller the maximum height (Sz), the smaller the height of the protruding protrusions that can become the starting point for catching. do.

The arithmetic mean height (Sa) may be different between the picture area 7 and the non-picture area 8, but in this case, if the arithmetic mean height (Sa) is less than or equal to the above upper limit value (or more than the above lower limit value). means that both the arithmetic mean height (Sa ₁ ) of the picture area 7 and the arithmetic mean height (Sa ₂ ) of the non-picture area 8 are less than or equal to the above upper limit value (or more than the above lower limit value). Similarly, the maximum height (Sz) may be different between the picture area 7 and the non-picture area 8, but in this case, the maximum height (Sz) is less than or equal to the above upper limit value (or more than the above lower limit value). This means that both the maximum height (Sz ₁ ) of the picture area 7 and the maximum height (Sz ₂ ) of the non-picture area 8 are less than or equal to the upper limit value (or greater than the lower limit value). The arithmetic mean heights (Sa ₁ ) and (Sa ₂ ) are each determined by averaging the arithmetic mean heights measured at three randomly selected locations. Similarly, the maximum heights (Sz ₁ ) and (Sz ₂ ) are each determined by averaging the maximum heights measured at three randomly selected locations.

The arithmetic mean heights (Sa), (Sa ₁ ), and (Sa ₂ ) are 0.50 μm or less, 0.48 μm or less, 0.46 μm or less, and 0.44 μm, respectively, from the viewpoint of further improving gloss and slipperiness. It may be less than or equal to 0.42 μm. The arithmetic mean heights (Sa), (Sa ₁ ), and (Sa ₂ ) may be 0.38 μm or more, 0.40 μm or more, 0.42 μm or more, or 0.44 μm or more, respectively.

The maximum height (Sz), (Sz ₁ ), and (Sz ₂ ) are 10.8 μm or less, 10.4 μm or less, 10.0 μm or less, and 9.6 μm or less, respectively, from the viewpoint of further improving gloss and slipperiness. Alternatively, it may be 9.2 μm or less. The maximum heights (Sz), (Sz ₁ ) and (Sz ₂ ) are respectively 6.0 μm or more, 8.0 μm, 9.0 μm or more, 9.5 μm or more, 10.0 μm or more, or 10.5 μm or more. It's okay.

From the viewpoint of suppressing the sharpness of the unevenness of the surface 5a of the varnish layer 5 and further improving the slipperiness, the kurtosis (Sku) of the surface 5a of the varnish layer 5 measured in accordance with ISO25178 is 4.0 or less. It's good. Kurtosis (Sku) may be, for example, 2.5 or more. The kurtosis (Sku) may be different between the picture area 7 and the non-picture area 8, but in this case, the kurtosis (Sku) being less than or equal to the above upper limit value (or more than the above lower limit value) means that the kurtosis (Sku) of the picture area 7 This means that both the kurtosis (Sku ₁ ) and the kurtosis (Sku ₂ ) of the non-picture area 8 are equal to or less than the upper limit value (or equal to or greater than the lower limit value). Kurtosis (Sku ₁ ) and (Sku ₂ ) are each determined by averaging the kurtosis measured at three randomly selected locations.

Kurtosis (Sku), (Sku ₁ ), and (Sku ₂ ) may be 2.8 or more, 3.0 or more, 3.2 or more, or 3.4 or more, respectively, from the viewpoint of further improving the slipperiness. good. Kurtosis (Sku), (Sku ₁ ) and (Sku ₂ ) may be 3.7 or less, 3.5 or less, 3.3 or less, or 3.1 or less, respectively.

The varnish layer 5 having the above-mentioned surface properties (Sa, Sz, Sku) can be formed by, for example, the composition of the ink, the composition of the water-based varnish (for example, the type and amount of resin contained in the water-based varnish), the coating of the varnish layer 5, etc. It can be produced by adjusting conditions etc. From the viewpoint of easily obtaining the varnish layer 5 having the above-mentioned surface properties, it is preferable to use an emulsion-type water-based varnish as the water-based varnish, and it is more preferable to use an emulsion-type water-based varnish in which different resins are combined. Here, the term "emulsion type aqueous varnish" means an aqueous varnish containing water and a resin emulsified and dispersed in the water.

Examples of resins contained in the water-based varnish include acrylic resins, urethane resins, silicone resins, and styrene resins. Acrylic resins include not only resins containing acrylic monomers as monomer units, but also resins containing methacrylic monomers as monomer units. These can be used alone or in combination of two or more. The water-based varnish is preferably a water-based varnish that is a combination of different resins, from the viewpoint that the varnish layer 5 having the above-mentioned surface properties is easily obtained, and better gloss and better slipperiness are easily obtained. It is more preferable to use an emulsion type water-based varnish in combination with the following. Combinations of resins include, for example, a combination of acrylic resin and urethane resin, a combination of acrylic resin and silicone resin, a combination of urethane resin and silicone resin, and a combination of styrene resin and acrylic resin. An example is a combination of Among these, a combination of an acrylic resin and a silicone resin makes it easy to obtain the varnish layer 5 having the above-mentioned surface properties. Note that the "combination of different resins" includes combinations of two or more resins combined, as well as combinations of two or more resins. Therefore, a water-based varnish that solely contains a copolymer composed of a combination of two or more resins, such as a styrene-acrylic copolymer, is also a "water-based varnish that combines different resins."

The thickness of the varnish layer 5 is not particularly limited, but may be 1.9 to 5.0 μm, 2.0 to 4.0 μm, or 2.5 to 3.0 μm. The thickness of the varnish layer 5 is the thickness of the portion indicated by _T5 in FIG. 1, and means the distance from the surface 3a of the ink layer 3 to the surface 5a of the varnish layer 5. The thickness of the varnish layer 5 can be determined using an optical microscope by interference spectroscopy that utilizes light interference phenomena.

It is preferable that no grooves with a depth of 1 μm or more exist on the surface 5a of the varnish layer 5. Grooves with a depth of 1 μm or more may occur due to cracks in the varnish layer 5, etc., but if such grooves do not exist, it is possible to avoid a decrease in slipperiness due to the edges of the grooves becoming caught and starting points. can. From the viewpoint of obtaining even better slipperiness, the total length of grooves with a depth of 1 μm or more observed within a range of 650 μm x 650 μm when observing the surface 5a of the varnish layer 5 may be 1500 μm or less, It may be 1000 μm or less or 600 μm or less. When the grooves are present on the surface 5a of the varnish layer 5, the lower limit of their total length is, for example, 10 μm.

The total thickness of the ink layer 3 and the varnish layer 5 is not particularly limited, but may be 2.0 to 6.8 μm, 2.1 to 4.5 μm, or 2.2 to 4.0 μm. It's okay.

The total thickness of the printed matter is not particularly limited, but may be 10 to 150 μm, 20 to 130 μm, or 25 to 100 μm.

The printed matter 10 described above has sufficient gloss (surface gloss) and good slip properties because the arithmetic mean height (Sa) and maximum height (Sz) of the surface 5a of the varnish layer 5 are within the above-mentioned ranges. has.

The glossiness of the surface 5a of the varnish layer 5 is, for example, 50 or more, preferably 60 or more, more preferably 65 or more, and still more preferably 70 or more. The upper limit of glossiness is, for example, 85. Therefore, the gloss level may be 50-85, 60-85, 65-85 or 70-85. The glossiness here means a value measured at an incident angle of 60 degrees in accordance with the method described in JIS Z8741-1997. The glossiness may differ between the pattern area 7 and the non-picture area 8, but in this case, the glossiness being equal to or higher than the above value means that the glossiness of both the white background part and the colored background area is equal to or higher than the above value. It means that.

The printed matter 10 can be obtained, for example, by a manufacturing method including at least the following steps (A), (B), and (C).
(A) Step of printing the ink-containing layer 13 on the printing substrate 1 (see (a) in FIG. 2).
(B) Step of forming a coating film 15 of water-based varnish on the printing substrate 1 and the ink-containing layer 13 so as to cover the ink-containing layer 13 (see (b) in FIG. 2).
(C) Step of forming a varnish layer 5 containing a dried water-based varnish by drying the water-based varnish coating 15 (see (c) in FIG. 2).

The ink-containing layer 13 may be the ink layer 3, and may be a layer that forms the ink layer 3 by drying or by a reaction caused by heating, UV irradiation, or the like. When a non-curable ink containing a solvent is used as the ink, the ink layer 3 is obtained by drying the ink-containing layer 13. When a thermosetting ink is used as the ink, the ink layer 3 is obtained by heating the ink-containing layer 13 and thermosetting it. When a UV-curable ink (for example, a UV-curable biomass ink) is used as the ink, the ink layer 3 is obtained by irradiating the ink-containing layer 13 with UV and curing it with UV light. If the ink-containing layer 13 is a layer that forms the ink layer 3 by drying or by a reaction caused by heating, UV irradiation, etc., for example, before drying the coating film 15 in step (C), the ink-containing A process for forming the layer 13 into the ink layer 3 (for example, a process of drying the ink-containing layer 13, a process of heating the ink-containing layer 13, or a process of irradiating the ink-containing layer 13 with UV) may be performed. When the ink-containing layer 13 is a layer that forms the ink layer 3 by drying, the ink-containing layer 13 may be formed into the ink layer 3 by drying the aqueous varnish in step (C). Drying of the ink and drying of the aqueous varnish may be carried out under conditions that do not inhibit the surface of the varnish layer 5 having the above-mentioned surface properties, and heating may be performed using a UV lamp or the like for drying. When the ink-containing layer 13 is a layer that forms the ink layer 3 through a reaction caused by heating, the water-based varnish in step (C) may be dried by heating, and the ink-containing layer 13 may be formed into the ink layer 3 by the heating.

When a concrete ink is used to print the ink-containing layer 13 in the step (A), an effect is achieved in that the drying time can be shortened.

In the above manufacturing method, the ink layer 3 and varnish layer 5 may be formed by a roll method, or the ink layer 3 and varnish layer 5 may be formed by a chamber method.

Hereinafter, the contents of the present disclosure will be explained in more detail using Examples and Comparative Examples, but the present disclosure is not limited to the following Examples.

The following materials were prepared in order to produce the printing parts according to Examples and Comparative Examples.
(1) Printing material/coated cardboard (manufactured by Rengo Co., Ltd., 310g/m ² )
(2) Ink/Oil-based ink: TOYO KING (registered trademark) NEX series (manufactured by Toyo Ink Co., Ltd.)
(3) Varnish / Water-based varnish A: Emulsion type water-based varnish containing acrylic resin and silicone resin as solid content / Water-based varnish B: Water-based varnish containing acrylic resin as solid content / Water-based varnish C: Acrylic as solid content Emulsion type water-based varnish containing styrene copolymer

<Example 1>
(Preparation of printed matter)
Printed matter was obtained by sequentially forming an ink layer and a varnish layer on the surface of coated cardboard using a roll method. At this time, the above oil-based ink was used to form the ink layer, and the above water-based varnish A was used to form the varnish layer. In addition, the ink layer is not formed over the entire surface of the coated cardboard, and the printed matter is between the pattern area where the ink layer exists between the coated cardboard and the varnish layer and the area between the coated cardboard and the varnish layer. and a non-picture area in which no ink layer is present. The designed thickness of the ink layer was 1.0 μm, and the thickness of the varnish layer was 2.5 μm.

<Comparative example 1>
A printed matter was obtained in the same manner as in Example 1 except that the water-based varnish B was used to form the varnish layer and the thickness of the varnish layer was 2.2 μm.

<Example 2>
A printed matter was obtained in the same manner as in Example 1, except that water-based varnish C was used instead of water-based varnish A.

<Example 3>
A printed matter was obtained in the same manner as in Example 1 except that the thickness of the varnish layer was 3.0 μm.

<Measurement/Evaluation>
The surface properties of the printed matter of Examples 1 to 3 and Comparative Example 1 were measured and evaluated (surface condition evaluation, slipperiness evaluation, and gloss evaluation) using the methods shown below. However, surface condition evaluation (measurement of total crack extension) was performed only on the printed matter of Example 1 and Comparative Example 1.

(1) Measurement of surface properties The printed matter of Examples 1 to 3 and Comparative Example 1 was cut into a size of 10 mm x 10 mm and used as evaluation samples. Next, the evaluation sample was fixed to the glass substrate from the coated cardboard side with tape. Next, three locations were randomly selected from each of the pattern and non-picture areas on the surface of the varnish layer of the evaluation sample, and each location was inspected using an Olympus laser microscope (LEXT OLS4100), which is an ISO 25178 compliant device. A surface observation image (650 μm x 650 μm) was acquired. Next, the arithmetic mean height (Sa), maximum height (Sz), and kurtosis (Sku) of the surface of each observation point were measured in accordance with ISO25178. The observation magnification was 200x (objective lens: 20x), the observation mode was "high precision", and the cutoff values were λc = 800.00 μm and λs = 0. Furthermore, during measurement, tilt correction was performed using three points randomly selected from within the observed area.

The arithmetic mean height (Sa ₁ ), maximum height (Sz ₁ ), and kurtosis (Sku ₁ ) of the surface of the pattern area were determined by averaging the measured values at three locations within the pattern area. Similarly, the arithmetic mean height (Sa ₂ ), maximum height (Sz ₂ ), and kurtosis (Sku ₂ ) of the surface of the non-picture area were determined by averaging the measured values at three locations within the non-picture area. . The results are shown in Table 1.

(2) Surface condition evaluation The surface observation image (650 μm x 650 μm) obtained in (1) above was enlarged to the maximum size that the image could not be completely cut off on a 21.5-inch display, and the length of the crack portion on the pattern area was The total length of the crack was calculated by measuring the length using a ruler. The results are shown in Table 1. According to the surface shape measurement results in (1) above, the depth of the crack was 1 to 2 μm.

(3) Evaluation of slipperiness AB-502 friction angle measuring machine (manufactured by Tester Sangyo Co., Ltd.) was used for measurement. Two prints of Examples 1 to 3 and Comparative Example 1 were prepared as evaluation samples. The surface of one coated cardboard of the evaluation sample of the same example was fixed with double-sided tape on the stand of a friction angle measuring machine to prevent it from moving. A 1000g thread was fixed to the coated cardboard side of the other evaluation sample with double-sided tape, and placed on the evaluation sample fixed on the friction angle measuring device so that the surfaces of the varnish layers were in contact with each other. . In this state, the table was gradually tilted, and the tilt angle (sliding angle) at which one evaluation sample began to slide on the other evaluation sample was measured. When the obtained measured value (sliding angle) was 20 degrees or less, it was judged that the slipping property was good. The measured values (slip angle) are shown in Table 1.

(4) Gloss Evaluation Using a gloss meter (trade name: Handy Gloss Meter) manufactured by Horiba, Ltd., the gloss in the pattern area and non-pattern area was measured at an incident angle of 60 degrees. The measurement was repeated 10 times, and the average value was calculated. The results are shown in Table 1.

1... Printed material, 1a... Surface of printed material, 3... Ink layer, 3a... Surface of ink layer, 5... Varnish layer, 5a... Surface of varnish layer, 7... Picture area, 8... Non-picture area, 10... Printed material .

Claims (4)

a printing substrate having a surface to be printed;
an ink layer provided on the surface;
a varnish layer provided to cover the ink layer,
The varnish layer contains a dried water-based varnish,
A printed matter in which the arithmetic mean height (Sa) and maximum height (Sz) of the surface of the varnish layer each satisfy the following.
0.35μm≦Sa≦0.52μm
0.4μm≦Sz≦11.0μm The printed matter according to claim 1, wherein the water-based varnish is an emulsion-type water-based varnish that combines different resins. The printed matter according to claim 2, wherein the water-based varnish contains a silicone resin and an acrylic resin. The printed matter according to any one of claims 1 to 3, wherein the varnish layer has a surface kurtosis (Sku) of 4.0 or less.

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