JP2023170851A - Packaging paper, package, and paper - Google Patents

Abstract

To provide: packaging paper capable of producing a package of excellent visibility even when a space or a gap is present between a translucent area and a content; and a package packed by the packaging paper.SOLUTION: The packaging paper according to the present invention comprises a translucent area satisfying the following requirements (1) and (2). The requirement (1): the following Δ(1) is 5.0 or less. The requirement (2): the following Δ(2) is 90 or more. Δ(1)=I2-I1. Δ(2)=(I2/I1)×100. I1: the visible light transmittance of transmitted light β transmitting the translucent area 4 detected at a position away from the incident position P by d1 mm when linear light α is made incident to the translucent area 4 of the packaging paper 1 from a visible light source 20. I2: the visible light transmittance of transmitted light β detected at a position away from the incident position P by d2 mm. d2-d1: 40 mm.SELECTED DRAWING: Figure 3

Description

TECHNICAL FIELD The present invention relates to packaging paper, packaging, and paper.

Packaging bodies such as envelopes and product packages sometimes have transparent areas for viewing addresses and contents from the outside. Although there is packaging paper that has a transparent resin film, from the viewpoint of resource reuse, etc., translucent paper or packaging paper that has a translucent area in which at least a portion of the paper is made transparent is preferable.

There are several ways to make paper transparent. For example, pulp fibers with increased beating are used in the production of translucent papers such as glassine paper and tracing paper. However, because the pulp fibers are ground and cut due to high beating, even though pulp fibers with increased beating are used for envelope windows, they are not suitable for applications such as packaging bags that require strength. is difficult to apply.
On the other hand, according to the method of impregnating the voids between cellulose fibers with a transparent resin, the paper strength can be maintained and the transparency of the translucent region impregnated with the transparent resin can be increased (for example, Patent Document 1, 2).

JP2021-91481A Japanese Unexamined Patent Publication No. 132699/1983

For example, if the main use is expected to be packaging thin contents such as documents, such as envelopes, visibility can be ensured by pressing the translucent area against the contents with your fingers. However, some packages are used to package products that have a deep three-dimensional shape. In addition, due to recent demands for environmental protection, the scope of application of paper packaging as an alternative to plastic packaging is expanding.

However, in conventional translucent paper, etc., it is difficult to clearly see the contents when there is a space or gap between the translucent area and the contents. Therefore, visibility when the contents are packaged with a deep space is insufficient.
One aspect of the present invention provides a packaging paper that provides a package with excellent visibility even when there is a space or gap between a translucent region and contents; and a package provided with the packaging paper.
A further aspect of the invention provides a paper having a basis weight of 40 g/m ² or more that has excellent visibility when viewed through the translucent area.

The present invention has the following aspects.
[1] Packaging paper having a translucent area that satisfies either or both of the following requirements (1) and (2).
Requirement (1): Δ(1) obtained by the following formula (1) is 5.0 or less.
Requirement (2): Δ(2) obtained by the following formula (2) is 90 or more.
Δ(1)=I ₂ −I ₁ ...Formula (1)
Δ(2)=(I ₂ /I ₁ )×100...Formula (2)
In the formula, _I1 is the amount of transmitted light β transmitted through the semi-transparent area when straight light α is incident on the semi-transparent area from a visible light source in parallel to the normal direction of the wrapping paper. _I2 is the visible light transmittance detected at a position d ₁ mm away from the incident position on the semi-transparent region in the traveling direction of the straight light α; This is the visible light transmittance detected at a position d ₂ mm away from the incident position on the transparent region in the traveling direction of the straight light α, where d ₂ is larger than d ₁ and d ₂ - _{d 1} is 40 mm.
[2] The packaging paper according to [1], further comprising a coating layer provided on at least a portion of the surface of the translucent region.
[3] The packaging paper according to [1] or [2], further comprising a hatched printed area in which a light-absorbing substance is attached to at least a portion of the translucent area.
[4] A package comprising the packaging paper according to any one of [1] to [3].
[5] Paper that has a translucent area that satisfies either or both of the following requirements (1) and (2), and has a basis weight of 40 g/m ² or more.
Requirement (1): Δ(1) obtained by the following formula (1) is 5.0 or less.
Requirement (2): Δ(2) obtained by the following formula (2) is 90 or more.
Δ(1)=I ₂ −I ₁ ...Formula (1)
Δ(2)=(I ₂ /I ₁ )×100...Formula (2)
In the formula, I ₁ is the amount of transmitted light β transmitted through the semi-transparent region when straight light α is incident on the semi-transparent region from a visible light source in parallel to the normal direction of the paper. _I2 is the visible light transmittance detected at a position d ₁ mm away from the incident position on the semi-transparent region in the traveling direction of the straight light α; This is the visible light transmittance detected at a position d ₂ mm apart in the traveling direction of the linear light α from the position of incidence on the area, where d ₂ is larger than d ₁ and d ₂ - _{d 1} is 40 mm.
[6] The paper according to [5], further comprising a coating layer provided on at least a portion of the surface of the translucent region.
[7] The paper according to [5] or [6], further comprising a hatched printed area in which a light-absorbing substance is attached to at least a portion of the translucent area.
[8] A package comprising the paper according to any one of [5] to [7].

According to one aspect of the present invention, there is provided a packaging paper that provides a packaging with excellent visibility even when there is a space or gap between a translucent region and contents; and a packaging that includes the packaging paper. Ru.
According to a further aspect of the present invention, there is provided a paper having a basis weight of 40 g/m ^{2 or} more that has excellent visibility when viewed through a translucent area.

FIG. 2 is an explanatory diagram schematically showing that a transparent resin film has excellent visibility. FIG. 2 is an explanatory diagram schematically showing that the visibility of conventional translucent paper or the like is insufficient. FIG. 2 is an explanatory diagram schematically showing an example of a method for measuring I ₁ and I ₂ . FIG. 2 is a plan view schematically showing an example of packaging paper. FIG. 5 is a diagram schematically showing a VV cross section of the packaging paper in FIG. 4. FIG. 2 is a plan view schematically showing an example of packaging paper. 7 is a diagram schematically showing a VII-VII cross section of the packaging paper of FIG. 6. FIG. FIG. 6 is an explanatory diagram schematically illustrating a presumed mechanism by which visibility is improved by a shaded printed portion. FIG. 2 is a cross-sectional view schematically showing an example of packaging paper. FIG. 2 is a cross-sectional view schematically showing an example of packaging paper.

In this specification, "~" indicating a numerical range means that the numerical values written before and after it are included as lower and upper limits.
The lower and upper limits of the numerical ranges disclosed herein can be arbitrarily combined to form a new numerical range.

Embodiments of the present invention will be described below with appropriate reference to the drawings. The dimensional ratios in the drawings are for convenience of explanation and may differ from the actual ones. Furthermore, in the following drawings, the same configurations are indicated using the same reference numerals, and the description of the overlapping configurations may be omitted.

[Visibility evaluation index]
A consumer or user views the contents of the package through the translucent area of the wrapping paper. The visibility (visual surface impression) of the semi-transparent region is judged based on how the visible image is perceived by the human eye.
When a transparent resin film F is placed above the content 10 on which the target image 11 is printed as shown in FIG. Proceed in a straight line. Therefore, the outline of the visible image 12A is clear, and the information on the target image 11 can be clearly seen through the resin film F.
On the other hand, as shown in FIG. 2, in the case of the conventional translucent paper 21, the light rays reflected from the target image 11 are easily refracted inside the translucent area 22, and there is also a lot of diffused light and scattered light. Therefore, the visible image 12B becomes an unclear image with unclear outline.

Conventionally, haze and opacity have been used to evaluate the visibility of semi-transparent regions. However, according to the studies of the present inventors, the numerical trends of haze and opacity often do not match the superiority or inferiority of visual recognition by human eyes. For example, when the whiteness of the sample is high, the visible light transmittance is high, but the visibility and visual appearance are not necessarily excellent.

The reason why the numerical trend of haze does not match the superiority or inferiority of visibility is considered to be as follows. Haze is calculated as the ratio of the diffuse transmittance to the total light transmittance of the light transmitted through the sample. Diffuse transmittance is the transmittance of diffused light that is obtained by making straight light incident on a sample and excluding parallel components of the light that passes through the sample. On the other hand, as shown in FIGS. 1 and 2, the human eye preferentially perceives light traveling in a straight line or light with a narrow diffusion angle, rather than diffused light or scattered light with a wide diffusion angle.
In this way, when calculating haze, the diffuse transmittance is calculated by excluding parallel component light that is easy to recognize with the human eye from the measurement target, and including diffuse light that is difficult to recognize with the human eye. . Since haze is calculated from such diffused transmittance, it is not suitable for evaluating human visual appearance or evaluating the superiority or inferiority of visibility in the depth direction.
Similarly, opacity is determined by including diffused light, which is difficult to perceive with the human eye, in the measurement target, so it is not suitable for evaluating human visual surface appearance or evaluating visibility in the depth direction.

[Δ(1), Δ(2)]
As a result of extensive studies, the inventors of the present invention came up with the idea of evaluating the visibility of a semi-transparent area based on the degree of blurring of the contents that can be seen through the semi-transparent area. The degree of blur is due to the diffusion pattern of light transmitted through the semi-transparent area. In the case of a semi-transparent area with a lot of blur, the transmitted light contains a relatively large amount of diffused light with a wide diffusion angle, resulting in a decrease in the visibility of the contents. On the other hand, in the case of a semi-transparent area with less blur, the transmitted light contains a relatively large amount of light traveling in a straight line or light with a narrow diffusion angle, so the visibility of the contents is good.
The present inventor has devised a method and index for quantitatively evaluating the degree of blur, and if the index of the degree of blur is within a specific numerical range, the visibility of the contents viewed through the semi-transparent area is improved. I found it to be excellent. The indicators are Δ(1) and Δ(2) defined below.

Δ(1) is determined by the following formula (1). Further, Δ(2) is obtained by the following formula (2).
Δ(1)=I ₂ −I ₁ ...Formula (1)
Δ(2)=(I ₂ /I ₁ )×100...Formula (2)

A measurement example of I 1 and I ₂ in equations ( ₁ ) and (2) will be described with reference to FIG. 3.
_I1 means that when straight light α is incident on the semi-transparent area 4 from the visible light source 20 in parallel to the normal direction of the packaging paper 1, the transmitted light β transmitted through the semi-transparent area 4 is converted into the straight light α from the incident position P. This is the visible light transmittance (%) detected at a position d ₁ mm away from the traveling direction.
I ₂ is the visible light transmittance (%) when the transmitted light β is detected at a position d ₂ mm away from the incident position P in the traveling direction of the straight light α. d ₂ is greater than d ₁ and d ₂ −d ₁ is 40 mm.

In the example shown in FIG. 3, the visible light transmittance of the transmitted light β at each position d ₁ mm and d ₂ mm away from the incident position P in the traveling direction of the straight light α is I ₁ and I ₂ . The visible light transmittance is the intensity ratio of transmitted light β to incident light (linear light α).
In the measurement of I ₁ and I ₂ , it is assumed that the distance between the incident position P of the straight light α into the semi-transparent region 4 and the visible light source 20, that is, d ₀ is constant. Although d ₀ is not particularly limited, it can be, for example, about 0 to 50 mm. Although _d1 is not particularly limited, it can be, for example, not less than paper thickness (thickness of packaging paper) and not more than 100 mm.

To measure I ₁ , a light receiving sensor may be placed at a position d ₁ mm away from the incident position P in the traveling direction of the straight light α. For example, if _d1 is equal to the paper thickness, measurement can be performed by applying a light receiving sensor to the surface of the target position opposite to the incident position P.
In order to measure I ₂ , a light receiving sensor may be placed at a position d ₂ mm away from the incident position P in the traveling direction of the straight light α. d ₂ is greater than d ₁ and d ₂ −d ₁ is 40 mm.
It is desirable to measure I ₁ and I ₂ under dark room conditions as much as possible. The measurement temperature is not particularly limited, but can be, for example, 10 to 30°C.

The visible light source 20 is not particularly limited as long as it emits linear light. The wavelength of visible light may be 380 to 780 nm, preferably 400 to 600 nm, and more preferably 520 to 570 nm. Further, the output intensity of the visible light source 20 is not particularly limited either.

As the measuring device equipped with the visible light source 20 and the light receiving sensor, for example, a visible light transmittance measuring device used for automobile window glass can be used. For example, Shenzhen Linshang Technology Co. , Ltd. ``WTM-1100'', the Kitagawa visible light transmittance meter ``old type PT-50'' and ``new type PT-500'' manufactured by Komei Rikagaku Kogyo Co., Ltd. However, the visible light source 20 and the light receiving sensor are not particularly limited as long as they can measure the visible light transmittance of transmitted light β transmitted through the semi-transparent region 4 under dark room conditions.

Δ(1) and Δ(2) are respectively indicators of the degree of blur when the contents are visually recognized from outside the package through the translucent area. As the degree of blur increases, the visible light transmittance I ₂ at the distance d ₂ becomes relatively low, Δ(1) increases, and Δ(2) decreases. On the other hand, if the degree of blurring decreases, the visible light transmittance I ₂ at the distance d ₂ becomes relatively high, Δ(1) becomes smaller, and Δ(2) becomes larger.
In other words, the larger Δ(1) or the smaller Δ(2), the lower the visible light transmittance I ₂ at the distance d ₂ , and the more blurred the visible image is formed. Conceivable. On the other hand, the smaller Δ(1) or the larger Δ(2), the higher the visible light transmittance I ₂ at the distance d ₂ , and the less blurred the visible image is formed. Conceivable.
In the present invention, since Δ(1) and Δ(2) satisfy predetermined requirements, it is possible to reduce blur when the contents are viewed from outside the package through the translucent region. As a result, visibility in the depth direction is excellent.

The packaging paper according to one aspect of the present invention has a translucent region that satisfies either or both of the following requirements (1) and (2). Therefore, the content viewed through the semi-transparent area is less blurred, the visibility of the content is excellent, and the visibility in the depth direction is also excellent.
Requirement (1): Δ(1) is 5.0 or less.
Requirement (2): Δ(2) is 90 or more.

Δ(1) is 5.0 or less, preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less. The smaller Δ(1) is, the better, and its lower limit is not particularly limited. The theoretical lower limit is 0. Regarding the guideline for the lower limit value, in the case of a transparent polyester resin film, Δ(1) may be within the range of 0 to 0.5.
Δ(2) is 90 or more, preferably 92 or more, more preferably 95 or more, and even more preferably 96 or more. The larger Δ(2) is, the better, and its upper limit is not particularly limited. The theoretical upper limit is 100. Regarding the guideline for the upper limit value, in the case of a transparent polyester resin film, Δ(2) may be within the range of 99 to 100.

In order to obtain a semi-transparent area where Δ(1) is a small value and a semi-transparent area where Δ(2) is a large value, it is necessary to It is a good idea to control the refraction and scattering of light on the surface of the paper.

[Example of packaging paper]
Some examples of packaging paper will be described below.
The packaging paper 1A illustrated in FIG. 4 and FIG. ;

As shown in FIG. 4, the translucent region 4 is formed in a part of the cellulose sheet 2 when viewed from above. When the packaging paper 1A is used as a package, the contents can be seen from the outside of the package through the translucent area 4.
The shape and area ratio of the semi-transparent region 4 in plan view are not limited at all. It can be set or changed as appropriate depending on the usage of the packaging paper and packaging body. In other examples, the translucent region may be the entire region of the cellulose sheet in the planar direction.
The number of semi-transparent areas is not particularly limited, and may be one or more. In the case of packaging paper with a plurality of translucent regions, it is not necessary that all the translucent regions satisfy the above requirement (1) or requirement (2), and it is sufficient that at least one translucent region satisfies the requirement (1) or (2). Depending on the consumer's or user's preference, semi-transparent areas with excellent visibility in the depth direction and semi-transparent areas with poor visibility may be mixed.

(coating layer)
The coating layer 5 is provided on the surface of the cellulose sheet 2 in the translucent region 4. The coating layer 5 is for increasing the smoothness of the surface of the semi-transparent region 4 and reducing irregularities.
Since the packaging paper 1A has the coating layer 5, its surface has few irregularities, and as a result, diffuse reflection of light on the surface of the translucent region 4 can be prevented. In addition, the coating layer 5 prevents the amount of incident light from decreasing due to reflection, while maintaining the amount of parallel component light. The reduction in the proportion of diffused light with a wide diffusion angle in the light transmitted through the semi-transparent region 4 due to the action of the coating layer 5 is one of the factors that reduces blur and improves visibility in the depth direction. It is believed that there is.

The material of the coating layer 5 is preferably a transparent material from the viewpoint of visibility. Examples of the material for the coating layer 5 include transparent materials and OP varnish. The specifics of the transparent material will be described later. When the coating layer 5 includes a transparent material, the transparent material of the coating layer 5 and the transparent material 3 of the semi-transparent region 4 may be the same or different types. Furthermore, the material for the coating layer 5 may be used alone or in combination of two or more.

OP varnish is sometimes called overprint varnish. The components of the OP varnish vary depending on the product, manufacturer, etc., but an OP varnish containing at least one selected from the group consisting of linseed oil, tung oil, and nitrified cotton is preferable. Commercially available OP varnishes include, for example, products from Toyo Ink Co., Ltd., T&K TOKA Co., Ltd., and Fuji Ink Manufacturing Co., Ltd.
One type of OP varnish may be used alone, or two or more types may be used in combination. As the drying method, a method using oxidative polymerization, a method using UV effect, etc. may be used.

The material for the coating layer 5 is selected from these materials with a refractive index of 1.4 to 1.6, preferably 1.45 to 1.60, more preferably 1.48 to 1.60, still more preferably 1.50. 1.60, particularly preferably 1.50 to 1.58. This is because the refractive index of cellulose fibers is generally said to be within the range of 1.4 to 1.6. By setting the refractive index of the coating layer 5 to a value close to the refractive index of cellulose fibers, refraction of light at the interface between the coating layer 5 and the cellulose sheet 2 can be reduced. Therefore, it becomes easier to obtain a semi-transparent region 4 with excellent visibility.
The refractive index of the coating layer 5 is measured according to JIS K 7142.

The smoothness of the coating layer 5 is preferably 50 to 1000 seconds, more preferably 50 to 500 seconds, and even more preferably 100 to 500 seconds. When the smoothness of the coating layer 5 is within the above numerical range, visibility is likely to be further improved.
The smoothness of the coating layer 5 was determined according to JAPAN TAPPI Paper/Pulp Test Method No. 5-2, measured according to JIS P8155.

The thickness of the coating layer 5 is preferably 0.5 to 2.5 μm, more preferably 0.5 to 2.0 μm, and even more preferably 0.7 to 2.0 μm. When the thickness of the coating layer 5 is at least the lower limit of the above numerical range, the surface has a glossy feel, and excellent visibility in the translucent region 4 is likely to be obtained. When the thickness of the coating layer 5 is less than or equal to the upper limit of the above numerical range, unevenness and curling of the paper sheet due to the difference in shrinkage after drying between the coated part and the non-coated part can be suppressed.
The thickness of the coating layer 5 is the value obtained by cutting out a cross section perpendicular to the plane and measuring the maximum value in the thickness direction when observing the cross section with an electron microscope.

In the packaging paper 1A, the coating layer 5 is provided on the entire surface of the translucent region 4 in the planar direction, but in other examples, the coating layer may be provided on a part of the translucent region in the planar direction. good. Further, the number of coating layers may be one or more.
A part of the material of the coating layer 5 may penetrate near the surface of the first surface 2a of the cellulose sheet 2. If the material of the coating layer 5 fills the voids between the fibers of the cellulose sheet 2, transparency can be easily increased.

(cellulose sheet)
Examples of the cellulose sheet 2 include paper base material, paperboard, and nonwoven fabric. Among these, a paper base material is preferable since excellent visibility is easily obtained in the translucent region 4.
The main component of the pulp contained in the paper base material is cellulose fiber. Examples of the pulp include chemical pulp, mechanical pulp, cotton, hemp, waste paper pulp, and non-wood pulp. However, the pulp in the paper base material is not limited to these examples.

Examples of the chemical pulp include softwood-derived pulp (NKP) and hardwood-derived pulp (LKP).
Examples of softwood-derived pulp include softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), softwood semi-bleached kraft pulp (NSBKP), and softwood sulfite pulp (NSP).
Examples of hardwood-derived pulp include hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), hardwood semi-bleached kraft pulp (LSBKP), and hardwood sulfite pulp (LSP).

Mechanical pulps include, for example, stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), thermoground pulp (TGP), chemical ground pulp (CGP), groundwood pulp (GP), Examples include thermomechanical pulp (TMP).

Examples of the waste paper pulp include defibrated waste paper pulp, defibrated/deinked waste paper pulp, and defibrated/deinked/bleached waste paper pulp. Examples of waste paper that can be used as raw materials for waste paper pulp include waste tea paper, waste paper for kraft envelopes, waste magazines, waste newspapers, waste leaflets, waste office paper, waste paper for cardboard, waste paper, waste paper for Kent, imitation waste paper, waste land certificates, etc. It will be done.
Non-wood pulps include various pulps such as those made chemically or mechanically from non-wood fibers such as kenaf, cotton, hemp, reed, etc.

Among these, chemical pulp is suitable for achieving both visibility and strength for packaging paper. Therefore, it is preferable that the cellulose sheet 2 has chemical pulp as a main component. Moreover, one type of various pulps may be used alone, or two or more types may be used in combination.

When waste paper pulp is used as the pulp, the content of the waste paper pulp is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total mass of pulp in the paper base material. When the content of waste paper pulp is below the upper limit value, the packaging paper 1A can be suitably applied to packaging for food and beverages. The lower limit of the content of waste paper pulp is 0% by mass.

In order to improve smoothness, whiteness, etc., the paper base material may contain fillers such as talc and calcium carbonate. However, the filler may affect the transparency and visibility of the translucent region 4. Therefore, the filler content is preferably within a range that does not impair visibility, and it is more preferable that the paper base material does not contain filler.

Paper base materials include, for example, kraft paper, single-gloss kraft paper, single-gloss paper, high-quality paper, electrophotographic paper, inkjet recording paper, thermal transfer recording paper, art paper, coated paper, cast coated paper, white paperboard, and colored paperboard. , corrugated board liners. Among these, high-quality paper, electrophotographic paper, kraft paper, single-gloss kraft paper, and single-gloss paper are preferred because they have a low pigment content and can easily provide excellent visibility in the translucent region 4. Paper and glossy paper are more preferable.

It is preferable that the paper base materials have different degrees of smoothness. For example, single gloss kraft paper and single gloss paper have a glossy surface with relatively high smoothness and a non-glossy surface with relatively low smoothness.
In the packaging paper 1A, the smoothness of the first surface 2a of the cellulose sheet 2 is higher than the smoothness of the second surface 2b. When the coating layer 5 is provided on the surface of the semi-transparent region 4 on the first surface 2a side, which has relatively high smoothness, the smoothness of the surface of the semi-transparent region 4 can be further improved.
However, in other examples, the coating layer 5 may be provided on the surface of the semi-transparent region 4 on the second surface 2b side where the smoothness is relatively low.

When the smoothness of the cellulose sheets 2 is different from each other, there may be a portion in the cellulose sheet where the transparent material 3 does not reach the first surface 2a in a cross-sectional view. If there is a part of the cellulose sheet 2 in which the transparent material 3 does not reach the first surface 2a, the surface condition of the first surface 2a, which has a relatively high degree of smoothness, is different from that of the transparent material 3 in that part. Easy to maintain in the state before impregnation. Furthermore, unevenness is less likely to occur on the surface of the semi-transparent region 4 on the first surface 2a side.
Therefore, it is considered that the diffused reflection of light is further suppressed, and the visibility of the semi-transparent region 4 is likely to be further improved.

The smoothness of the first surface 2a is preferably 10 seconds or more, more preferably 30 to 2000 seconds, even more preferably 30 to 1000 seconds. When the smoothness of the first surface 2a is at least the lower limit of the numerical range, excellent visibility is likely to be obtained in the semi-transparent region 4. When the smoothness of the first surface 2a is less than or equal to the upper limit of the numerical range, it is easy to obtain a cellulose sheet 2 suitable for manufacturing the packaging paper 1A.
The smoothness of the second surface 2b is preferably 1000 seconds or less, more preferably 20 to 1000 seconds, even more preferably 20 to 300 seconds. When the smoothness of the second surface 2b is equal to or higher than the lower limit of the numerical range, excellent visibility is likely to be obtained in the semi-transparent region 4. When the smoothness of the second surface 2b is less than or equal to the upper limit of the numerical range, it is easy to obtain a cellulose sheet 2 suitable for manufacturing the packaging paper 1A.
The smoothness of the first surface 2a and the second surface 2b is determined by JAPAN TAPPI Paper/Pulp Test Method No. 5-2, measured according to JIS P8155.

The pulp freeness in the paper base material is preferably 350 ml CSF or more, more preferably 400 to 700 ml CSF, and even more preferably 450 to 600 ml CSF.
When the freeness of the pulp in the paper base material is at least the lower limit of the above numerical range, the strength of the packaging paper can be easily maintained. When the freeness of the pulp in the paper base material is below the upper limit of the above numerical range, packaging paper having a translucent region with excellent transparency and visibility is easily obtained.
The pulp freeness (unit: mlCSF) in the paper base material is measured according to JIS 8121-2.

The basis weight of the paper base material is preferably 40 to 150 g/m ² , more preferably 45 to 100 g/m ² , even more preferably 50 to 85 g/m ² . When the basis weight of the paper base material is at least the lower limit of the above numerical range, it is easy to obtain good paper strength as packaging paper. When the basis weight of the paper base material is less than or equal to the upper limit of the above numerical range, the transparency of the translucent region can be easily enhanced.
The basis weight of the paper base material is measured according to JIS P8124.

The density of the paper base material is preferably 0.5 to 0.8 g/cm ³ , more preferably 0.55 to 0.75 g/cm ³ . When the density of the paper base material is equal to or higher than the lower limit of the above numerical range, it is easy to increase the strength of the packaging paper. When the density of the paper base material is less than or equal to the upper limit of the above numerical range, the amount of impregnation of the transparent material is likely to be increased.
The density of the paper base material is measured according to JIS P8118.

The porosity of the paper base material is preferably 30 to 80%, more preferably 40 to 70%, even more preferably 50 to 70%. When the porosity of the paper base material is equal to or higher than the lower limit of the above numerical range, the transparency of the translucent region can be easily enhanced. When the porosity of the paper base material is less than or equal to the upper limit of the above numerical range, the physical strength of the sheet is unlikely to decrease.
The porosity of the paper base material is calculated from the value obtained by dividing the density measured according to JIS P8118 by the true density of cellulose, 1.50.

The thickness of the paper base material is preferably 20 to 120 μm, more preferably 20 to 80 μm, and even more preferably 30 to 70 μm. When the thickness of the paper base material is at least the lower limit of the above numerical range, it is easy to increase the strength of the packaging paper. When the thickness of the paper base material is less than or equal to the upper limit of the above numerical range, excellent visibility is likely to be obtained in the translucent region.
The thickness of the paper base material is measured according to JIS P8118.

The method for producing the paper base material is not particularly limited. For example, there is a method in which pulp that is a raw material for a paper base material is beaten, a pulp slurry containing the beaten pulp is made into paper, and a wet sheet obtained by paper making is dried.
In pulp beating, it is preferable to beat the raw material pulp until the disintegration freeness of the paper base material falls within a desired range. The beating machine is not particularly limited. For example, a double disc refiner etc. can be mentioned.

The paper machine used for paper making is not particularly limited. Examples include a Fourdrinier paper machine, a short wire paper machine, a cylinder paper machine, and the like.
After papermaking, the surface of the paper base material obtained through a drying step may be subjected to a smoothing treatment.
Smoothing treatment can improve the surface strength, printability, etc. of packaging paper. Examples of the smoothing treatment include a method in which the paper base material is subjected to pressure treatment between reels that can be pressurized. The device for performing the smoothing process is not particularly limited. For example, the paper is smoothed by passing it through a machine calender, gloss calender, soft nip calender, etc. in front of the winder section. A machine calendar and a super calendar may be used together, or a super calendar may be used instead of a machine calendar.

(Transparent material)
The transparent material 3 is not particularly limited. Examples of the transparent material 3 include transparent resins such as acrylic resin, polyethylene resin, polyester resin, urethane resin, nitrocellulose, shellac, and rosin; tung oil, linseed oil, castor oil, hydrophilic castor oil, coconut oil, and soybean oil. , commercially available vegetable oils such as salad oil; waxes such as cownaba wax, palm wax, beeswax, spermaceti, and pixel wax; and waxes.
One type of transparent material 3 may be used alone, or two or more types may be used in combination.

Among these, transparent resins that are stable over time are preferred, and acrylic resins are more preferred. Among acrylic resins, UV-curable acrylic resins are particularly preferable because they have excellent surface coverage and the interface of the region impregnated with the transparent material 3 becomes clear in cross-sectional view.
Examples of the ultraviolet curable acrylic resin include those disclosed in paragraphs 0025 and 0026 of JP-A No. 2021-91481.

The transparent material 3 has a refractive index of 1.4 to 1.6, preferably 1.45 to 1.58, more preferably 1.50 to 1.58, still more preferably 1. It is preferable to select one within the range of 52 to 1.58. This is because the refractive index of cellulose fibers is generally said to be within the range of 1.4 to 1.6. When the refractive index of the transparent material 3 is within the above numerical range, the difference from the refractive index of the cellulose fibers is small, and the transparency and visibility of the semi-transparent region 4 can be easily improved.
The refractive index of the transparent material 3 is measured according to JIS K 7142.

By impregnating the cellulose fibers with the transparent material 3 having a refractive index close to that of the cellulose fibers and filling the gaps between the cellulose fibers, it is possible to reduce the refraction of light caused by the transparent material 3 in the cellulose sheet 2. . Therefore, it becomes easier to obtain a semi-transparent region 4 with excellent transparency and visibility. In order to adjust the refractive index, a high refractive index material such as zirconium or titanium may be used as necessary.

When the transparent material 3 is colored, it is preferable that a coloring agent (pigment, dye) having a complementary color to the color of the transparent material 3 be present in the cellulose sheet 2 in the translucent region 4. It is thought that the complementary coloring agent that has entered between the cellulose fibers absorbs the incident light, thereby suppressing diffused reflection and scattering of light, thereby improving visibility. Examples of the coloring agent include a blue coloring agent, a purple coloring agent, and a black coloring agent.
Here, "complementary colors" means, for example, a combination of colors that are exactly opposite on the hue wheel. However, within the range in which the effects of the present invention can be obtained, "complementary colors" are not only colors that are exactly opposite on the color wheel, but also combinations of colors that are in a continuous area around them. But that's fine.

For example, transparent resins derived from non-petroleum ingredients such as shellac and rosin are colored. In the case of shellac, a coloring agent that is complementary to the orange color is preferred. In the case of rosin, a colorant that is complementary to its amber color is preferred. If a colored transparent material derived from a non-petroleum component is preferred from an environmental standpoint, it is useful to use a colorant that is complementary to the color of the transparent material.

Since the transparent material 3 is impregnated into cellulose fibers, it is preferably a material that is liquid at room temperature or in a heated state. In addition, those that can be dissolved in a liquid medium such as an organic solvent at room temperature or in a heated state are also preferable from the viewpoint of permeability. That is, the transparent material 3 is preferably one that can be impregnated into the cellulose sheet 2 as a permeable liquid transparent agent during manufacturing. The clarifying agent will be described later.
The translucent region 4 within the cellulose sheet 2 primarily contains the transparentizing material 3, although other components derived from the transparentizing agent used during manufacture may be present. Other components will be described later.

The density of the translucent region having the transparent material is preferably 0.7 to 2.5 g/cm ³ , more preferably 0.7 to 2.0 g/cm ³ , and even more preferably 0.8 to 2.0 g/cm ³ preferable. When the density of the translucent region is equal to or higher than the lower limit of the above numerical range, it is considered that the air layer between the fibers is sufficiently eliminated by impregnation with the resin component. When the density of the translucent region is less than or equal to the upper limit of the above-mentioned numerical range, the processability when the packaging paper is made into a package or the like is improved.
The density of the semi-transparent region 4 is measured according to JIS P 8118.

The method for manufacturing the packaging paper 1A is not particularly limited. Examples include methods (1) and (2) below.
Method (1): A manufacturing method in which a coating layer 5 is formed on the surface of a cellulose sheet 2, and then a transparent material 3 is impregnated into the cellulose sheet 2.
Method (2): A manufacturing method in which the transparent material 3 is impregnated into the cellulose sheet 2, and then the coating layer 5 is formed on the surface of the cellulose sheet 2.

In forming the coating layer 5, a coating liquid containing the material for the coating layer 5 is applied to the first surface 2a of the cellulose sheet 2. Then, if necessary, the coating layer 5 is dried and provided on the first surface 2a side.

When the material of the coating layer 5 is solid at room temperature, a coating liquid is prepared using a liquid medium that can dissolve the material of the coating layer 5. When the material of the coating layer 5 is liquid at room temperature, the concentration of the coating liquid may be changed using a liquid medium, or the coating liquid may be used as it is without using a liquid medium. Details of the liquid medium will be described later.

The method of applying the coating liquid containing the material of the coating layer 5 is not particularly limited. Examples include various coating methods such as roll coating, bar coating, blade coating, dip coating, flexo printing, gravure printing, offset printing, gravure offset printing, and silk screen printing. Moreover, the drying method in the case of drying is not particularly limited. Natural drying or heat drying may be used.

In impregnating the transparent material 3, a liquid transparent agent is applied to the surface of the cellulose sheet 2. The transparentizing agent may be applied to the first surface 2a or the second surface 2b, but it is preferable to apply it to the first surface 2a, which has a higher degree of smoothness.
Since the first surface 2a has higher smoothness than the second surface 2b, the closer to the second surface 2a within the cellulose sheet 2, the higher the density of cellulose fibers. Therefore, the transparent material 3 is easily impregnated into the cellulose sheet 2 from the second surface 2b.
When the transparent material 3 is impregnated into the cellulose sheet 2 from the easily impregnated second surface 2b in this way, it is easy to form the translucent region 4, which has the advantage of being excellent in productivity.

A clarifying agent is a liquid containing a clarifying material. When the transparent material is solid at room temperature, a liquid medium that can dissolve the transparent material is used to prepare a liquid transparent agent. When the transparent material is liquid at room temperature, the concentration of the transparent material may be changed using a liquid medium, or it may be used as a transparent agent without using a liquid medium.

The liquid medium is not particularly limited. Both aqueous and organic solvents can be used. When the liquid medium contains water, the cellulose sheet 2 tends to swell due to the water. Moreover, the cellulose sheet 2 tends to shrink during subsequent drying. As a result, curls, bumps, and unevenness are likely to occur. Therefore, it is preferable that the liquid medium does not contain water, and an organic solvent is more preferable.

The organic solvent may be a polar solvent or a non-polar solvent.
Examples of polar solvents include alcohols, ethers, esters, and nonpolar solvents.
Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, n-pentanol, and n-hexanol.
Examples of ethers include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, and tetraethylene glycol monomethyl ether. Ethyl ether, ethylene glycol monopropyl ether, diethylene glycol monopropyl ether, triethylene glycol monopropyl ether, tetraethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monoisopropyl ether, Tetraethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, triethylene glycol monoisobutyl ether, tetraethylene glycol Monoisobutyl ether, ethylene glycol monotertiary butyl ether, diethylene glycol monotertiary butyl ether, triethylene glycol monotertiary butyl ether, tetraethylene glycol monotertiary butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, Propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monoethyl ether, tetrapropylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monopropyl ether, propylene glycol monoethyl ether Isopropyl ether, dipropylene glycol monoisopropyl ether, tripropylene glycol monoisopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, propylene glycol monoisobutyl ether, dipropylene glycol monoisobutyl ether, tripropylene glycol monoisobutyl ether, propylene Various glycol ethers can be mentioned, such as glycol monotertiary butyl ether, dipropylene glycol monotertiary butyl ether, and tripropylene glycol monotertiary butyl ether.
Examples of the esters include diethylene glycol monoethyl acetate, diethylene glycol monobutyl acetate, and the like.
Examples of non-polar solvents include paraffinic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, and dodecane; isoparaffinic hydrocarbons such as isohexane, isooctane, and isododecane; alkylnaphthenic hydrocarbons such as liquid paraffin; Examples include aromatic hydrocarbons such as benzene, toluene, xylene, alkylbenzene, and solvent naphtha; silicone oil; and the like.

The clarifying agent may further include other components besides the clarifying material and the liquid medium. Other components include, for example, basic substances such as ammonia, ethylenediamine, and triethylamine; viscosity modifiers such as glycerin and ethylene glycol; high refractive index substances such as zirconium and titanium; antifoaming agents; mold release agents; and colorants. Can be mentioned. However, other components are not limited to these examples.

During impregnation, a portion may be formed in the cross section of the cellulose sheet 2 in which the transparent material 3 does not reach a part of the first surface 2a. This is because, in this portion, the surface state of the first surface 2a having relatively high smoothness can be maintained in the state before being impregnated with the transparent material 3. The unevenness on the surface of the semi-transparent region 4 on the first surface 2a side can be easily reduced, and the visibility of the semi-transparent region 4 can be further improved.

The coating amount of the clarifying agent per unit area is preferably 10 to 70 g/m ² , more preferably 20 to 60 g/m ² , even more preferably 30 to 60 g/m ² . When the coating amount of the transparentizing agent per unit area is at least the lower limit of the numerical range, the transparency of the semi-transparent region 4 can be easily enhanced. If the coating amount of the transparentizing agent per unit area is below the upper limit of the numerical range, the transparentizing agent will be difficult to reach the inner part of the first surface 2a.

The viscosity of the clarifying agent is preferably 50 to 5000 mPa·s, more preferably 50 to 4000 mPa·s, even more preferably 50 to 3000 mPa·s. If the viscosity of the clarifying agent is greater than or equal to the upper limit of the numerical range, the clarifying agent will be difficult to reach the inner part of the first surface 2a. When the viscosity of the clarifying agent is less than or equal to the upper limit of the above numerical range, the transparentizing agent is likely to be impregnated into the cellulose sheet 2.
The viscosity of the clarifying agent is measured using a Brookfield viscometer at 30° C. and 60 rpm.

The method of applying the clarifying agent is not particularly limited. Examples of methods for applying the transparentizing agent include flexographic printing, inkjet printing, gravure printing, offset printing, gravure offset printing, silk screen printing, roll coating, bar coating, and blade coating.

By impregnating the cellulose sheet 2 with the transparentizing agent, the voids between the fibers in the cellulose sheet 2 can be filled with the transparent material 3. When using a transparentizing agent containing a transparentizing material with a refractive index within the range of 1.4 to 1.6, the voids in the cellulose sheet 2 can be filled with the transparentizing agent having a refractive index close to that of cellulose. Therefore, the refraction of light caused by the transparent material 3 within the cellulose sheet 2 can be reduced.

The application and impregnation of the transparentizing agent onto the cellulose sheet 2 may be performed at once, or may be performed in multiple steps. When performing the process in multiple times, the components and composition of the clarifying agent used in each of the multiple times may be the same or different.

When using an ultraviolet curing type transparentizing agent, various light sources such as a high pressure mercury lamp, a metal halide lamp, a xenon lamp, and an electrodeless discharge lamp can be used. The cumulative amount of light is not particularly limited. It may be changed as appropriate depending on the amount of the clarifying agent used and the type of the transparent resin.

Although the packaging paper 1A may be manufactured by method (1) or method (2), it is preferable to manufacture by method (1) for the following reasons.
According to method (1), the coating layer 5 can be formed on the first surface 2a of the cellulose sheet 2 before the transparent material 3 is impregnated into the cellulose sheet 2. Therefore, when the transparentizing agent is impregnated into the cellulose sheet 2 from the second surface 2b of the cellulose sheet 2, the coating layer 5 prevents the transparentizing agent from seeping out from within the cellulose sheet 2 to the first surface 2a. It can be prevented. Therefore, unevenness is less likely to occur on the surface of the semi-transparent region 4 on the first surface 2a side. As a result, the coating layer 5 can more reliably prevent the diffused reflection of light on the surface of the semi-transparent region 4 on the first surface 2a side, so that the visibility of the semi-transparent region 4 can be further improved.
In addition, according to method (1), it is possible to prevent the transparentizing agent from seeping out from within the cellulose sheet 2 to the first surface 2a, so that it is possible to suppress staining of the apparatus during manufacturing. Further, the coating layer 5 can prevent blocking when winding up or stacking the packaging paper 1A.

After forming the translucent paper region, Δ(1) and Δ(2) may be determined for the translucent region. The visibility of the semi-transparent area may be evaluated based on the obtained Δ(1) and Δ(2).

(shaded printed part)
Other examples of packaging paper will be explained. The packaging paper 1B shown in FIGS. 6 and 7 includes a cellulose sheet 2; a translucent area 4; and a hatched printed area 6.
The shaded printed area 6 has a plurality of dots of the light-absorbing material 7 attached thereto by shaded printing. That is, the hatched printed area 6 is a collection of dots of a plurality of light-absorbing substances 7.

The light-absorbing substance 7 of each dot of the hatched printing part 6 has a function of absorbing light scattered within the cellulose sheet 2. Therefore, although the amount of light transmitted through the cellulose sheet 2 is reduced, scattered light in the semi-transparent region 4 on the first surface 2a side is suppressed.
Since the wrapping paper 1B has the hatched printed portion 6, the scattered light generated within the cellulose sheet 2 can be absorbed by the hatched printed portion 6. Therefore, the proportion of diffused light with a wide diffusion angle in the light transmitted through the semi-transparent region 4 can be reduced, and the visibility of the semi-transparent region 4 is improved.

As shown in FIG. 8, the hatched printed portion 6 can absorb scattered light generated within the cellulose sheet 2. Therefore, among the light rays reflected from the target image 11, light that travels linearly toward the visual position or light that has a narrow diffusion angle tends to selectively pass through the semi-transparent region 4. Therefore, the outline of the visible image 12C is clearer than that of the visible image 12B (see FIG. 2).
The reduction in the proportion of diffused light with a wide diffusion angle in the light transmitted through the semi-transparent area 4 due to the effect of the shaded printed portion 6 is also one of the factors that reduces blur and improves visibility in the depth direction. it is conceivable that.

In the packaging paper 1B, the hatched printed portion 6 is formed by attaching a plurality of dots of light-absorbing substance 7 to the first surface 2a of the cellulose sheet 2. However, in other examples, the halftone printed portion 6 may be formed by attaching a plurality of dots of the light-absorbing substance 7 to the surface of the second surface 2b.
The shape of the dot pattern of the hatched printing portion 6 is not particularly limited. Examples include patterns of halftone dots, lattice, diagonal lines, circles, rings, and polygons, but the shapes are not limited to these examples. The shape of the dot pattern can be changed as appropriate depending on the setting conditions when performing halftone printing.

The size of each dot in the hatched printing area 6 is not particularly limited. For example, the thickness is preferably 40 to 100 μm, more preferably 50 to 80 μm. When the size of the dot is equal to or larger than the lower limit of the numerical range, scattered light is easily absorbed by the shaded printing portion 6. When the size of the dot is below the upper limit of the numerical range, it is considered that the tone and color feel of the semi-transparent area 4 are less likely to be affected by the halftone printing part 6.
The size of a dot is a value measured as the diameter of the circumscribed circle with the smallest area or the minor axis of the circumscribed ellipse with the smallest area among the circumscribed circles or circumscribed ellipses that include one dot. The size of the dots can be changed as appropriate depending on the setting conditions when performing halftone printing.

The area ratio of the hatched printed portion 6 is preferably 20 to 80%, more preferably 25 to 75%. When the area ratio is equal to or greater than the lower limit of the numerical range, the shaded printed portion 6 easily absorbs scattered light. When the area ratio is less than or equal to the upper limit of the numerical range, it is considered that the tone and color feel of the semi-transparent region 4 are less likely to be affected by the halftone printing portion 6.
The area ratio of the shaded printed area is a value expressed as a percentage of the area of dots per unit area. In the case of solid printing, the area ratio is 100%, and when there are no dots, the area ratio is 0%. The area ratio can be changed as appropriate depending on the setting conditions when performing halftone printing.

The light-absorbing substance 7 is not particularly limited as long as it has a high absorption coefficient. Since the light-absorbing substance 7 is formed by halftone printing, the ink for printing can be prepared and used. For example, a black component, particularly a black ink, is preferable because it has excellent light absorption. The black ink may be a single color black ink or a composite black in which a plurality of colors are used together. However, the color of the light-absorbing substance 7 is not limited to black.

It is preferable that the color of the light-absorbing substance 7 is changed as appropriate depending on the use of the packaging paper 1B, the contents when used as a package, the hue of the cellulose sheet, and the color of the contents. For example, this is because visibility and color sense can be changed according to the preferences of users and consumers. In commercialization, for example, a light-absorbing substance having a color similar to the color of the contents of the package may be used, or a light-absorbing substance having a color complementary to the color of the contents of the package may be used.
In addition, the shape of the dot pattern, the size of each dot, and the area ratio of the halftone printing part 6 can be changed as appropriate depending on the use of the packaging paper, the contents of the package, and the color of the contents. preferable. This is because the visibility and color sense can be changed according to the preferences of users and consumers.

In the example shown in FIGS. 6 and 7, the packaging paper 1B has a hatched printed portion 6 in which the light-absorbing substance 7 is adhered to almost the entire surface of the translucent region 4 on the first surface 2a side. In this example, the shaded printed portion may be formed by adhering the light-absorbing substance 7 to a part of the semi-transparent region 4 on the first surface 2a side. Even when the light-absorbing substance 7 adheres to at least a portion of the semi-transparent region 4 on the first surface 2a side, the effect of absorbing scattered light by the shaded printed portion can be obtained.

The method for manufacturing the packaging paper 1B is not particularly limited. The light-absorbing substance 7 may be attached to the surface of the cellulose sheet 2 by halftone printing. The cross-hatching may be performed before impregnating the transparent material into the cellulose sheet or after impregnating the transparent material into the cellulose sheet.

The method of shading printing is not particularly limited. Various printing methods can be used. Examples include offset printing, gravure printing, flexographic printing, screen printing, inkjet printing, and electrophotographic printing. Further, the halftone printing may be performed on the same printing machine as the application and impregnation of the transparentizing agent, or may be performed on separate printing machines.

In another example, the wrapping paper may have a coating layer and a cross-hatched print area in addition to the translucent area. In this case, the shaded printed area may or may not be covered with a coating layer.
The packaging paper 1C illustrated in FIG. 9 includes a cellulose sheet 2; a translucent region 4; a coating layer 5; and a hatched printed portion 6. In the packaging paper 1C, the hatched printed portion 6 is covered with the coating layer 5.

According to the packaging paper 1C having the hatched printed portion 6 covered with the coating layer 5, it is easy to obtain the effect of preventing diffused reflection of light on the outermost surface of the semi-transparent region 4 on the first surface 2a side. As a result, it is thought that, in combination with the effect of absorbing scattered light by the shaded printed portion 6, the visibility of the contents in the semi-transparent region 4 is likely to be further improved.

In the packaging paper 1C, all of the hatched printed areas 6 are covered with the coating layer 5, but in other examples, part of the hatched printed areas 6 may be covered with the coating layer 5. Even when a part of the hatched printed area 6 is covered with the coating layer 5, the effect of preventing diffuse reflection of light by the coating layer 5 can be obtained.
The method for manufacturing the packaging paper 1C is not particularly limited. For example, the hatched printed portion 6 may be formed before the coating layer 5 is formed, and then at least a portion of the hatched printed portion 6 may be covered with the coating layer 5.

In the packaging paper 1D illustrated in FIG. 10, the hatched printed portion 6 is not covered with the coating layer 5. A hatched printed portion 6 is formed on the surface of the coating layer 5.
In the packaging paper 1D as well, scattered light generated within the cellulose sheet 2 can be absorbed by the shaded printing portions 6. Further, since the halftone printing portion 6 is formed by attaching a plurality of dots of the light-absorbing substance 7 by halftone printing, the smoothness of the surface of the coating layer 5 is not likely to be impaired. Therefore, scattered light can be absorbed and diffused reflection on the surface can be prevented. As a result, it is easy to obtain excellent visibility.
The method for manufacturing the packaging paper 1D is also not particularly limited. After forming the coating layer 5, the light-absorbing substance 7 may be attached to the surface of the coating layer 5 by halftone printing.

The drawings used in the above illustrative description are schematic. Therefore, the boundary line between the cellulose sheet 2 and the semi-transparent region 4 in a plan view, and the boundary line between the cellulose sheet 2 and the coating layer 5 in a plan view do not necessarily exist clearly as shown schematically. Further, each interface in a cross-sectional view does not necessarily exist clearly as shown schematically.

[Mechanism of action]
The packaging paper of this embodiment, which has been described with reference to several examples above, has a translucent region that satisfies either or both of the following requirements (1) and (2).
Requirement (1): Δ(1) is 5.0 or less.
Requirement (2): Δ(2) is 90 or more.

According to the packaging paper of this embodiment, the contents are less blurred when viewed through the translucent region, and the visibility of the contents is excellent. Also, visibility is good even when there is a space or gap between the translucent area and the contents. Therefore, it is possible to obtain a package that has a good visual appearance in the depth direction and has excellent visibility even when the contents are packaged with a space in the depth.

[Uses of packaging paper]
Wrapping paper can be suitably used for packaging purposes. Examples of packaging bodies include envelopes and packages for various products.
For example, packaging paper can be shaped into a bag to form a packaging bag. The translucent area of the wrapping paper can be used as a window to see the contents of the packaging bag. When making a packaging bag, it may be produced by bonding packaging paper using various adhesives, heat sealants, etc. and processing it into a bag shape.
The shape of the packaging bag is not particularly limited. Examples include, but are not limited to, envelopes, flat bags, square-bottomed bags, gusseted bags, and carrier bags. It may be selected appropriately depending on the contents.

[Paper example]
The paper according to one aspect of the present invention has a basis weight of 40 g/m ² or more and has a translucent region that satisfies either or both of the following requirements (1) and (2). Therefore, the image (contents) viewed through the translucent area has less blurring, the visibility of the image (contents) is excellent, and the visibility in the depth direction is also excellent.
Requirement (1): Δ(1) is 5.0 or less.
Requirement (2): Δ(2) is 90 or more.

The paper of the present invention has excellent visibility despite having a basis weight of 40 g/m ² or more. The upper limit of the basis weight is not particularly limited, but is preferably 150 g/m ² or less. The basis weight is more preferably 45 to 100 g/m ² , even more preferably 50 to 85 g/m ² . The area where the basis weight is 40 g/m ² or more is the basis weight of the paper base excluding the translucent area. That is, the basis weight of the area of the paper base material not impregnated with the transparent material is 40 g/m ² or more.

In the paper of the present invention, details and preferred embodiments of Δ(1) and Δ(2) and their mechanism of action are as described above. Furthermore, the paper of the present invention may have either or both of a coating layer and a hatched printed area. The details and preferred embodiments of the paper base material, transparent material, coating layer, and hatched printing area are also as described above.

[Uses of paper]
The paper of the present invention has a basis weight of 40 g/m2 ^or more and has unprecedented transparency and visibility, so it can be used not only for packaging paper, but also for printing paper, book paper, copying paper, In information paper, label paper, etc., it can be used for various purposes to visually recognize images (characters, symbols, images, objects, etc.) on the opposite side of the paper through the paper base material.

Although several examples of one embodiment have been described above, the present invention is not limited to the embodiment disclosed in this specification, and can be implemented with appropriate modifications within the scope of the gist thereof. The embodiments disclosed in this specification can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following description.

[material]
(cellulose sheet)
In the following example, single gloss kraft paper (1) with a basis weight of 50 g/m ² was used. The glossy surface of the single gloss kraft paper (1) has a smoothness of 120 seconds, and the non-glossy surface has a smoothness of 10 seconds. The single gloss kraft paper (1) has a density of 0.75 g/cm ³ , a thickness of 67 μm, and a porosity of 50%.

(Clearing agent)
The following transparentizing agent (1) was used as a transparentizing agent for forming a semi-transparent region.
Clarifying agent (1): Acrylic paraffin solvent (trade name: Clariten DC, manufactured by Daiwa Chemical Industry Co., Ltd., refractive index of transparent material: 1.50, viscosity at 30°C, 60 rpm: 2000 mPa・s)

(coating layer)
The following coating liquid (1) was used as a coating liquid when forming a coating layer.
Coating liquid (1): DC AB OP varnish OJ3 (manufactured by DIC Graphics Co., Ltd.)

(light absorbing substance)
Black ink (trade name: NCP matte ink, manufactured by DIC Graphics) was used.

[Example 1]
Using a Matsuo Sangyo micrometer adjustable applicator, the transparentizing agent (1) was applied to the non-glossy surface of the single-gloss kraft paper (1) at a coating amount of 35 g/m ² . Thereafter, it was dried for 30 seconds using a hot air dryer at 120° C. to form a translucent region, thereby obtaining the paper of Example 1.

[Example 2]
Using a Matsuo Sangyo micrometer adjustable applicator, the transparentizing agent (1) was applied to the non-glossy surface of the single-gloss kraft paper (1) at a coating amount of 35 g/m ² to form a semi-transparent area. . Next, shading printing was performed with black ink on the glossy side of the single gloss kraft paper (1). The area ratio of the halftone printing was 25%, the size of the dots was 50 μm, and the shape of each dot was circular. After the halftone printing, the paper of Example 2 was dried for 30 seconds using a hot air dryer at 120°C.

[Example 3]
Using a Matsuo Sangyo micrometer adjustable applicator, the transparentizing agent (1) was applied to the non-glossy surface of the single-gloss kraft paper ( ¹ ) to form a translucent area at a coating amount of 35 g/m2. . The coating liquid (1) was applied to the glossy side of the single-gloss kraft paper (1) at a coating amount of 1.5 g/m ² without performing shading printing. Thereafter, the paper of Example 3 was obtained by UV curing using NPT-453 (4.8 kW, 2 lamps) manufactured by Nippon Bunka Seiko Co., Ltd.

[Example 4]
Using a Matsuo Sangyo micrometer adjustable applicator, the transparentizing agent (1) was applied to the non-glossy surface of the single-gloss kraft paper ( ¹ ) to form a translucent area at a coating amount of 35 g/m2. . Next, shading printing was performed with black ink on the glossy side of the single gloss kraft paper (1). The area ratio of the halftone printing was 25%, the size of the dots was 50 μm, and the shape of each dot was circular. After shading printing, it was dried for 30 seconds in a hot air dryer at 120°C, and then coating liquid (1) was applied so that the coating amount was 1.5 g/m ² . -453 (4.8kW, 2 lamps) was used to form a coating layer with a thickness of 1.0 μm (smoothness: 130 seconds) on the glossy surface of single gloss kraft paper (1), and the paper of Example 4 was Obtained.

[Comparative example 1]
Bleached packaging paper (Oji Materia product, 60 g/m ² ) was prepared as a base paper. The basis weight is 65 g/m ² , the smoothness of the glossy surface is 90 seconds, and the smoothness of the non-glossy surface is 8 seconds. The density is 0.78 g/cm ³ , the thickness is 78 μm, and the porosity is 47.8%. Other than that, semitransparent areas were formed on bleached packaging paper using the same method as in Example 1 to obtain paper of Comparative Example 1.

[Reference example 1]
A transparent polyester resin film (Toyobo Co., Ltd. product "Cosmoshine A4160") was prepared.

[sample]
The papers having translucent regions obtained in Examples 1 to 4 and Comparative Example 1, and the film of Reference Example 1 were used as samples.

[Calculation of Δ(1), Δ(2)]
Δ(1) was determined by the following formula (1), and Δ(2) was determined by the following formula (2).
Δ(1)=I ₂ −I ₁ ...Formula (1)
Δ(2)=(I ₂ /I ₁ )×100...Formula (2)

I ₁ and I ₂ in the formula were measured as follows. The units of I ₁ and I ₂ are both %.
Linear light (72.0 lx) from a visible light source (wavelength 380 to 780 nm) is incident on a semi-transparent area parallel to the normal direction of the sample, and the visible light transmittance of the transmitted light that has passed through the semi-transparent area is calculated as the incident position. It was detected at a position in contact with the surface of the sample on the opposite side, and _I1 was obtained. Thus, in this measurement example, _d1 was the thickness of each sample. In addition, the visible light transmittance of the transmitted light was detected at a position 40 mm away from the sample in the normal direction, and I ₂ was obtained. For the measurement of I ₁ and I ₂ , Shenzhen Linshang Technology Co. , Ltd. The product "WTM-1100" was used.

[Haze, opacity]
Haze was measured using "HZ-V3" (manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS-K7136.
Opacity was measured using "SC-WT" (manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS P8149.

[Evaluation of visibility in depth direction]
A 10.5-point word document printed on an A4 size was placed on a horizontal table, and the wrapping paper of each example was placed 5.0 cm above it. Furthermore, the visibility of the characters on the printed matter when viewed from a position 30 cm above the packaging paper through the translucent area of the packaging paper was evaluated based on the following criteria.
A: There are no missing characters and they can be clearly recognized.
B: There is a slight loss of characters, but the characters can be clearly recognized.
C: Some characters are missing, but the characters can be recognized.
D: Characters are missing in multiple places and are difficult to read.
E: Characters are missing everywhere and are extremely difficult to recognize as characters.

[result]
The results are shown in Table 1.

The packaging papers of Examples 1 to 4 had excellent visibility in the depth direction. On the other hand, the packaging paper of Comparative Example 1 having a translucent area in which both Δ(1) and Δ(2) did not satisfy the predetermined requirements had poor visibility evaluation results. Furthermore, the numerical trends of Δ(1) and Δ(2) generally coincided with the trends in visual recognition by humans.

According to one aspect of the present invention, there is provided a packaging paper that provides a packaging with excellent visibility even when there is a space or gap between a translucent region and contents; and a packaging that includes the packaging paper. Ru.
According to a further aspect of the present invention, there is provided a paper having a basis weight of 40 g/m ^{2 or} more that has excellent visibility when viewed through a translucent region.

1 (1A, 1B, 1C, 1D)...Wrapping paper, 2...Cellulose sheet, 3...Transparent material, 4...Semi-transparent area, 5...Coating layer, 6...Shaded printed area, 7...Light-absorbing substance, DESCRIPTION OF SYMBOLS 10... Package, 11... Target image, 12... Visible image, 20... Visible light source, α... Straight light, β... Transmitted light, F... Resin film, P... Incident position.

Claims (8)

A packaging paper having a translucent area that satisfies either or both of the following requirements (1) and (2).
Requirement (1): Δ(1) obtained by the following formula (1) is 5.0 or less.
Requirement (2): Δ(2) obtained by the following formula (2) is 90 or more.
Δ(1)=I ₂ −I ₁ ...Formula (1)
Δ(2)=(I ₂ /I ₁ )×100...Formula (2)
In the formula, _I1 is the amount of transmitted light β transmitted through the semi-transparent area when straight light α is incident on the semi-transparent area from a visible light source in parallel to the normal direction of the wrapping paper. visible light transmittance detected at a position d ₁ mm away from the incident position on the semi-transparent region in the traveling direction of the straight light α;
I ₂ is the visible light transmittance of the transmitted light β detected at a position d ₂ mm away from the incident position of the straight light α into the semi-transparent region in the traveling direction of the straight light α, and d ₂ is greater than d ₁ and d ₂ −d ₁ is 40 mm. The wrapping paper according to claim 1, further comprising a coating layer provided on at least a portion of the surface of the translucent region. The packaging paper according to claim 1, further comprising a hatched printed area in which a light-absorbing substance is attached to at least a portion of the translucent area. A packaging body comprising the packaging paper according to any one of claims 1 to 3. Paper that has a translucent area that satisfies either or both of the following requirements (1) and (2) and has a basis weight of 40 g/m ² or more.
Requirement (1): Δ(1) obtained by the following formula (1) is 5.0 or less.
Requirement (2): Δ(2) obtained by the following formula (2) is 90 or more.
Δ(1)=I ₂ −I ₁ ...Formula (1)
Δ(2)=(I ₂ /I ₁ )×100...Formula (2)
In the formula, I ₁ is the amount of transmitted light β transmitted through the semi-transparent region when straight light α is incident on the semi-transparent region from a visible light source in parallel to the normal direction of the paper. is the visible light transmittance detected at a position d ₁ mm away from the incident position on the semi-transparent region in the traveling direction of the straight light α,
I ₂ is the visible light transmittance of the transmitted light β detected at a position d ₂ mm away from the incident position of the straight light α into the semi-transparent region in the traveling direction of the straight light α, and d ₂ is greater than d ₁ and d ₂ −d ₁ is 40 mm. Paper according to claim 5, further comprising a coating layer provided on at least a portion of the surface of the translucent region. The paper according to claim 5, further comprising a hatched printed area in which a light-absorbing substance is attached to at least a portion of the translucent area. A packaging body comprising the paper according to any one of claims 5 to 7.

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