JP2022062334A - Transparent paper, packaging material, label, and transparentizing agent - Google Patents

Abstract

To provide: an environmentally friendly transparent paper having excellent transparency, useful as a replacement for plastic materials, and capable of suppressing generation of micro plastics derived from petrified resins; and an environmentally friendly transparentizing agent capable of, when used to a paper substrate, obtaining a transparent paper having excellent transparency and useful as a replacement for plastic materials, and capable of suppressing generation of micro plastics derived from petrified resins.SOLUTION: A transparent paper includes a transparent area where a non-petroleum component-derived resin component is impregnated into at least a part of an area of a paper substrate, wherein a coloring agent exists in the transparent area, and the transparent area has an opacity measured in accordance with JIS P 8149 of 4-25%. A transparentizing agent includes a non-petroleum component-derived resin component, a coloring agent, and an alcohol having a carbon number of 1-6.SELECTED DRAWING: None

Description

The present invention relates to transparent paper, packaging materials, labels, and transparent agents.

As a method for increasing the transparency of the paper, for example, there are a method for increasing the beating degree of the pulp fiber and a method for impregnating the space of the base paper with the resin. The method of increasing the beating degree of the pulp fiber is used in the production of glassine paper, tracing paper and the like, and the method of impregnating the resin is used in the production of oil paper, brazing paper and the like. Various methods for impregnating the resin have been proposed for the purpose of improving transparency (for example, Patent Documents 1 and 2).

Patent Document 1 proposes to obtain transparent paper by using a clearing agent in which paraffin wax is mixed with an organic solvent solution of a resin. Further, Patent Document 2 proposes a transparent paper to which a clearing agent containing a non-petrified alkali-soluble resin such as shellac is applied.

Japanese Unexamined Patent Publication No. 2-127599 Japanese Unexamined Patent Publication No. 8-109597

In recent years, with the progress of deplasticization in various products such as packaging materials, the inventors of the present invention have come up with the idea of substituting transparent paper for the transparent plastic material on the market. bottom. Transparent paper has the advantage that it can be dissociated after being collected as used paper and is easy to recycle.
However, the transparent papers of Patent Documents 1 and 2 have insufficient transparency to be used as a substitute for a plastic material. In addition, since the clearing agent of Patent Document 1 contains a resin derived from a petroleum component, microplastics may be generated, which makes it unsuitable for environmental protection.

INDUSTRIAL APPLICABILITY The present invention is an environmentally friendly transparent paper that has excellent transparency, is useful as a substitute for plastic materials, and can suppress the generation of microplastics derived from petrochemical resins; A transparent paper which is excellent and useful as a substitute for a plastic material can be obtained, and an environmentally friendly clearing agent capable of suppressing the generation of microplastic derived from a petrochemical resin is provided.

The present invention has the following aspects.
[1] A resin component derived from a non-petroleum component has a transparent region impregnated in at least a part of a paper substrate, and a colorant is present in the transparent region, which is measured according to JIS P 8149 of the transparent region. A transparent paper having an opacity of 4 to 25%.
[2] The transparent paper according to [1], wherein the hue b ^* measured using a light source containing ultraviolet rays according to JIS Z 8781-4 in the transparent region is -10 to +3.
[3] The transparent paper of [1] or [2], wherein the resin component contains at least one of shellac and rosin.
[4] The transparent paper according to any one of [1] to [3], wherein the colorant has a complementary color relationship with the color of the resin component.
[5] The transparent paper according to [4], wherein the colorant is at least one selected from the group consisting of a blue colorant, a purple colorant, and a black colorant.
[6] The transparent paper according to any one of [1] to [5], wherein the paper base material has a paper density of 20 to 70 g / cm ² .
[7] JAPAN TAPPI Paper / Pulp Test Method No. in the transparent region. The transparent paper according to any one of [1] to [6], wherein the smoothness measured according to 5-2 is 200 to 5000 sec.
[8] The transparent paper according to any one of [1] to [7], wherein the haze measured according to JIS-K7136 of the transparent region is 80% or less.
[9] A packaging material having the transparent paper according to any one of [1] to [8].
[10] A label having the transparent paper according to any one of [1] to [8].
[11] A clearing agent containing a resin component derived from a non-petroleum component, a colorant, and an alcohol having 1 to 6 carbon atoms.
[12] The clearing agent of [11], wherein the resin component contains at least one of shellac and rosin.
[13] The transparent agent according to [11] or [12], wherein the colorant has a complementary color relationship with the color of the resin component.
[14] The clearing agent according to [13], wherein the colorant is at least one selected from the group consisting of a blue colorant, a purple colorant, and a black colorant.
[15] The clearing agent according to any one of [11] to [14], wherein the content of the resin component is 10 to 50% by mass.

According to the present invention, an environmentally friendly transparent paper having excellent transparency, useful as a substitute for a plastic material, and capable of suppressing the generation of microplastic derived from a petrochemical resin; transparent when applied to a paper substrate. A transparent paper having an excellent feeling and useful as a substitute for a plastic material can be obtained, and an environmentally friendly clearing agent capable of suppressing the generation of microplastic derived from a petrochemical resin is provided.

<Transparent paper>
The transparent paper of the present invention is made of a paper base material, and has a transparent region in which at least a part of the paper base material is impregnated with a resin component.
The resin component is derived from a non-petroleum component. Here, the "resin derived from a non-petroleum component" means a resin manufactured from a raw material that does not contain a petroleum component. As the resin component, for example, one containing at least one of shellac and rosin is preferable.

Shellac is a natural resin contained in a resinous substance secreted by Kerria lacca. Kerria lacca is bred using twigs of plants, and Kerria lacca sucks sap and secretes resinous substances. Shellac can be obtained by purifying the solidified resinous substance secreted by Kerria lacca.
Shellac is a component that is impregnated between pulp fibers when applied to a paper substrate. The shellac is impregnated between the fibers of the paper base material, and the air layer is eliminated, so that the transparent feeling of the transparent paper is obtained. As described above, shellac is a component for obtaining a transparent feeling of transparent paper when applied to a paper base material. In addition, since shellac is a thermoplastic resin, the transparent paper can be bonded to the transparent paper by a method such as heat sealing, and the transparent paper can be imparted with heat-sealing properties.

The components of shellac differ depending on the purification method, product, etc., but for example, the main component is a resin acid such as aleuritinic acid, jalaric acid, or laxillaric acid. The color of shellac varies depending on the twigs and trees used for breeding the scale insects, but is, for example, orange. Here, the shade of "orange" varies depending on the degree of purification of shellac and the product, but includes dark orange to light orange as long as the effect of the present invention can be obtained.
Examples of commercially available products of shellac include products of Nippon Shellac Industry Co., Ltd., Koyo Chemical Co., Ltd., Gifu Shellac Manufacturing Co., Ltd. and the like.

Rosin is a natural resin contained in pine fat. Rosin can be obtained by purifying pine fat by distillation or the like.
Rosin is a component that is impregnated between pulp fibers when applied to a paper substrate. The rosin is impregnated between the fibers of the paper substrate and the air layer is eliminated, so that the transparent feeling of the transparent paper is obtained. As described above, rosin is a component for obtaining a transparent feeling of transparent paper when applied to a paper substrate. In addition, since rosin is a thermoplastic resin, heat-sealing properties can be imparted to transparent paper.

The components of rosin differ depending on the purification method, product, etc., but for example, rosin acid such as abietic acid, palastolic acid, and isopimalic acid is the main component. The color of rosin varies depending on the tree used for collecting pine fat, the degree of purification, the product, and the like, but is, for example, amber. Here, the shade of "amber" varies depending on the degree of purification of rosin and the product, but includes dark amber to light amber as long as the effect of the present invention can be obtained.
Examples of commercially available rosin products include products of Arakawa Chemical Industry Co., Ltd. and Harima Chemicals Group Co., Ltd.

There is a colorant in the transparent area. The colorant is, for example, a pigment or a dye. The present inventor has found that when a colorant such as a pigment or a dye is blended, the transparency of the transparent paper is improved even though the transparent region is colored by the pigment or the dye. Since the transparent region contains a colorant, the opacity of the transparent region becomes good, and an excellent transparency can be obtained.

In order to further improve the transparency, it is preferable that the colors of the pigment and the dye have a complementary color relationship with the color of the resin component impregnated in the transparent region. Here, the "color having a complementary color relationship" means, for example, a combination of colors located at opposite positions in the color wheel. However, within the range in which the effect of the present invention can be obtained, "colors having a complementary color relationship" are not only colors that are exactly opposite to each other in the color wheel, but also combinations of colors that are in continuous regions around the color wheel. But it may be.
For example, as the colorant, at least one selected from the group consisting of a blue colorant, a purple colorant, and a black colorant is preferable. In addition, one type of colorant may be used alone, or two or more types may be used in combination.

When the resin component contains either shellac or rosin, the color of the pigment or dye preferably has a complementary color relationship with the color of shellac or rosin in the resin component. For example, when the resin component contains orange shellac, the color of the pigment and the dye is preferably a color having a complementary color relationship with the orange color of shellac. When the resin component contains amber rosin, the color of the pigment and the dye is preferably a color having a complementary color relationship with the amber color of rosin.

When the resin component contains both shellac and rosin, it is preferable that the colors of the pigment and the dye have a complementary color relationship with the color of the mixture of shellac and rosin. The color of the mixture of cellac and rosin can be specified by the color of the solution in which cellac and rosin are dissolved in a solvent such as alcohol in a state without pigments and dyes.

The pigment is a colorant that is insoluble in alcohols having 1 to 6 carbon atoms, which will be described later. Examples of the pigment include products of DIC Corporation, Dainichiseika Kogyo Co., Ltd., Toyo Ink Co., Ltd., Sumika Color Co., Ltd. and the like. However, pigments are not specified in these examples.

The dye is a colorant that is soluble in alcohols having 1 to 6 carbon atoms, which will be described later. Examples of the dye include products of Sumika Chemtex Co., Ltd., Morishita Chemical Industry Co., Ltd., Nippon Kayaku Kogyosho Co., Ltd., Nippon Kayaku Co., Ltd. and the like. However, the dye is not limited to these examples.

The opacity of the transparent region is 4 to 25%, preferably 4 to 20%, more preferably 4 to 15%. Since the opacity of the transparent region is equal to or less than the upper limit value, an excellent transparency can be obtained. Since the opacity of the transparent region is equal to or higher than the lower limit, it is not necessary to extremely beat the pulp used for the paper substrate, and transparent paper can be produced.
The opacity of the transparent area is measured according to JIS P 8149.

The hue b ^* of the transparent region is preferably −10 to +3. When the hue b ^* in the transparent region is within the above numerical range, the color of the transparent paper is small, and it becomes easy to apply it as a substitute for transparent plastic.
The hue b ^* of the transparent region is measured using a light source containing ultraviolet rays according to JIS Z 8781-4.

The smoothness of the transparent region is preferably 200 to 5000 sec, more preferably 300 to 5000 sec, and even more preferably 500 to 5000 sec. When the smoothness of the transparent region is within the above numerical range, the transparency and printability of the transparent paper are improved.
The smoothness of the transparent region was determined by the JAPAN TAPPI Paper / Pulp Test Method No. It can be measured according to 5-2, JIS P8155.

The haze of the transparent region is preferably 80% or less, more preferably 50% or less, still more preferably 40% or less. When the haze of the transparent region is not more than the upper limit value, the transparent paper is more excellent in transparency. The lower limit of the haze of the transparent region is not particularly limited, but may be, for example, 10% or more. When the haze of the transparent region is 10% or more, it is not necessary to extremely advance the beating of the pulp used for the paper substrate, and the manufacturing cost is reduced.
The haze of the transparent area can be measured according to JIS-K7136.

The density of the transparent region is preferably 0.7 to 1.2 g / cm ³ , more preferably 0.8 to 1.2 g / cm ³ , and even more preferably 0.8 to 1.1 g / cm ³ . When the density of the transparent region is at least the above lower limit value, the air layer between the fibers is sufficiently eliminated by impregnation with the resin component, and the transparency of the transparent paper is further improved. When the density of the transparent region is not more than the upper limit value, the formability of the transparent paper is improved.
The density of the transparent area can be measured according to TAPPI UM-522.

The range of the transparent area is not particularly limited and can be appropriately set according to the use of the transparent paper. The transparent region may be a partial region in the plane direction of the paper substrate, or may be the entire region. When the transparent area is a part of the transparent paper, the number of transparent areas is not limited, and the size and shape of each transparent area are not limited. In the transparent region, it is preferable that the resin component is impregnated in the entire thickness direction of the paper base material in the transparent region, because the transparent feeling of the transparent paper can be further sufficiently obtained.

Examples of the pulp constituting the paper base material include wood pulp, mechanical pulp, cotton, linen, used paper pulp, non-wood pulp and the like. However, the pulp in the paper substrate is not limited to these examples.
Examples of wood pulp include softwood-derived pulp (NKP), hardwood-derived pulp (LKP), and the like. Examples of the 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 the 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).
These softwood-derived pulps and hardwood-derived pulps may be used alone or in combination of two or more.

Examples of the mechanical pulp include stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), thermogrand pulp (TGP), chemigrand pulp (CGP), crushed wood pulp (GP), and the like. Thermomechanical pulp (TMP) and the like can be mentioned.
Examples of the used paper pulp include desorbed used paper pulp, desorbed / deinked used paper pulp, and desorbed / deinked / bleached used paper pulp. Examples of used paper used as a raw material for used paper pulp include brown used paper, craft envelope used paper, magazine used paper, newspaper used paper, leaflet used paper, office used paper, cardboard used paper, upper white used paper, Kent used paper, imitation used paper, and ground ticket used paper. Will be.
Examples of non-wood pulp include various pulps such as pulp chemically or mechanically produced from non-wood fibers such as kenaf, hemp and reed.
These mechanical pulps, recycled paper pulps, and non-wood pulps may be used alone or in combination of two or more.

Wood pulp is preferable as the pulp constituting the paper base material. When wood pulp is used as the pulp, it is preferable to use softwood-derived pulp and hardwood-derived pulp in combination.
When used paper pulp is used as the pulp, the content of the used paper pulp is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total mass of the pulp constituting the paper base material. When the content of the used paper pulp is not more than the above upper limit value, the transparent paper can be suitably applied to the packaging material for food and drink. The lower limit of the content of used paper pulp is 0% by mass.

The dissociation freeness of the pulp constituting the paper substrate is preferably 50 to 600 ml, more preferably 100 to 500 ml, still more preferably 100 to 400 ml. When the dissociation freeness of the pulp is at least the above lower limit value, the strength of the transparent paper tends to be high. When the dissociation freeness of the pulp is not more than the above upper limit value, the fineness of the paper base material is improved, and the transparency of the transparent paper can be further sufficiently obtained.
The dissociation freeness of the paper substrate is measured by the following method. That is, the dissociated pulp obtained by dissociating the paper substrate in accordance with JIS-P8220: 2012 with a standard dissociation machine is filtered in accordance with JIS-P8121: 2012 with a Canadian standard drainage tester. The degree is measured, and the degree of drainage is defined as the dissociation freeness of the paper substrate.

The density of the paper substrate is preferably 0.5 to 1.2 g / cm ³ , more preferably 0.7 to 1.2 g / cm ³ , and even more preferably 0.8 to 1.2 g / cm ³ . When the density of the paper base material is not more than the upper limit value, the air layer between the fibers is sufficiently removed in advance, and it becomes easy to obtain an excellent transparency in the transparent region. When the density of the paper base material is at least the above lower limit value, it is easy to obtain transparent paper having excellent moldability.
The density of the paper substrate can be measured according to TAPPI UM-522.

The paper density of the paper base material is preferably 20 to 70 g / cm ² , more preferably 20 to 60 g / cm ² , and even more preferably 30 to 60 g / cm ² .
When the paper density of the paper base material is at least the above lower limit value, it becomes easy to obtain an excellent transparency. When the paper density of the paper base material is not more than the above upper limit, it is easy to obtain good paper strength.

The thickness of the paper substrate 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 above lower limit value, it is easy to obtain transparent paper having excellent strength. When the thickness of the paper base material is not more than the upper limit, it is easy to obtain transparent paper having excellent transparency. The thickness of the paper substrate can be an average value of values measured by observing a cross section of transparent paper with a scanning electron microscope (SEM).

The smoothness of the paper substrate is preferably 50 to 2000 sec, more preferably 100 to 2000 sec, and even more preferably 200 to 2000 sec. When the smoothness of the paper base material is within the above numerical range, it is easy to obtain transparent paper having excellent transparency and printability.
The smoothness of the paper substrate was determined by the JAPAN TAPPI Paper / Pulp Test Method No. It can be measured according to 5-2, JIS P8155.

The transparent paper of the present invention may have a coating layer containing an OP varnish provided on one surface of the transparent region. OP varnish is sometimes called overprint varnish. When the transparent paper has a coating layer containing OP varnish, the transparent paper can be glossed. The composition of the OP varnish varies depending on the product, the manufacturer, and the like, but an OP varnish containing at least one selected from the group consisting of flaxseed oil, tung oil, and nitrocellulose is preferable. Examples of commercially available OP varnish products include products of Toyo Ink Co., Ltd., T & K TOKA Co., Ltd., and Fuji Ink Manufacturing Co., Ltd.

(Manufacturing method of transparent paper)
In the transparent paper of the present invention, for example, the clearing agent of the present invention described later is applied to at least a part of at least one surface of the paper base material, and the clearing agent is impregnated into the paper base material to form a transparent region. It can be manufactured by doing. When a transparent paper is obtained by applying a transparent agent, a transparent region may be formed on a part of the paper substrate, or a transparent region may be formed on the entire paper substrate.
The surface to which the clearing agent is applied may be one side or both sides of the paper base material. The method of applying the clearing agent is not particularly limited. For example, various coating methods and coating methods such as spray coating, curtain coating, roll coating, bar coating, blade coating, gravure coating, and dip coating can be used.

When the coating layer containing OP varnish is provided in the transparent region, a clearing agent is applied to one surface of the paper base material, the paper base material is impregnated with the clearing agent, and then the other surface of the paper base material is impregnated. The OP varnish may be applied to the surface of the paper substrate to provide a coating layer containing the OP varnish, or the OP varnish may be applied to one surface of the paper substrate and the coating layer containing the OP varnish may be provided. A clearing agent may be applied to the other surface and the paper base material may be impregnated with the clearing agent. After impregnating with OP varnish, OP varnish may be applied to provide a coating layer containing OP varnish.
The method of applying the OP varnish is not particularly limited, and various coating methods such as gravure coating and dip coating can be used.

The method for producing the paper substrate is not particularly limited. For example, a method including a step of beating the pulp which is a raw material of the paper base material, a step of making a pulp slurry containing the beaten pulp, and a step of drying the wet sheet obtained by the papermaking can be mentioned.
In the beating step, it is preferable to beat the pulp of the raw material until the freeness of the finished paper becomes 30 to 550 ml, preferably 10 to 500 ml, so that the freeness of the paper substrate becomes 50 to 600 ml. .. The beating machine used in the beating process is not particularly limited. For example, a double disc refiner or the like can be mentioned.

The paper machine used in the paper making process is not particularly limited. For example, a long net paper machine, a short net paper machine, a circular net paper machine and the like can be mentioned.
The surface of the paper substrate obtained through the steps of papermaking and drying may be subjected to a smoothing treatment. By applying the smoothing treatment, the surface strength, printability and the like can be improved. Examples of the smoothing treatment include a method of pressurizing a paper substrate between reels that can be pressurized. The device for performing the smoothing process is not particularly limited. For example, the product is finished by passing it through a machine calendar, gloss calendar, soft nip calendar, etc. in front of the winder section. The machine calendar and the super calendar may be used together, or the super calendar may be used instead of the machine calendar.

(Mechanism of action)
In the transparent paper of the present invention described above, since the colorant is present in the transparent region impregnated with the resin component, the colorant that has entered between the fibers of the pulp can absorb the light incident on the transparent paper between the fibers of the pulp. Therefore, diffused reflection and scattering of light on the transparent paper are suppressed, the transparency when observed with the naked eye is improved, and the opacity is also lowered. The result is sufficient transparency to be used as a substitute for transparent plastic materials.
In addition, since the resin component impregnated in the transparent region is derived from a non-petroleum component, it is possible to suppress the generation of microplastic derived from petroleum resin, which is environmentally friendly.

(Use)
Applications of the transparent paper of the present invention include packaging materials, labels, envelopes, and the like. In particular, transparent paper having a transparent region impregnated with a resin component containing shellac can be suitably applied to applications such as packaging materials for foods and drinks because shellac is edible. When the transparent paper of the present invention is applied to a packaging material, a packaging container can be obtained by forming the transparent paper into, for example, a bag shape by adhering the transparent paper by a method such as heat sealing.
When the transparent paper of the present invention is applied to a label, it may be used as a transparent label by adhering the transparent paper to the surface of a container or the like by a method such as heat sealing, or to one surface of the transparent paper. It may be used as a transparent label by imparting adhesiveness and adhering to the surface of a container or the like. When used as a label, characters, figures, patterns, etc. may be printed on the surface opposite to the surface of the transparent paper to which the adhesive is imparted.

<Transparency agent>
The clearing agent of the present invention contains a resin component derived from a non-petroleum component, a colorant, and an alcohol having 1 to 6 carbon atoms. The details and preferred embodiments of the resin component derived from the non-petroleum component and the colorant are the same as those described in the above section <Transparent Paper>.
The clearing agent of the present invention may further contain other components other than these components.

Alcohol having 1 to 6 carbon atoms is a component that functions as a liquid medium for a clearing agent. By using an alcohol having 1 to 6 carbon atoms, it is possible to reduce the occurrence of curl, unevenness, and unevenness after applying the clearing agent and during drying.
Examples of the alcohol having 1 to 6 carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, n-pentanol, n-hexanol and the like. Among these, methanol, ethanol, n-propanol and isopropanol are preferable, ethanol and isopropanol are more preferable, and ethanol is particularly preferable, because the heat-sealing property of the transparent paper to which the clearing agent is applied is improved. However, alcohols having 1 to 6 carbon atoms are not limited to these examples.

The other components of the clearing agent are not particularly limited as long as the effects of the present invention can be obtained. Examples thereof include aqueous media such as water; basic substances such as ammonia, ethylenediamine and triethylamine; polyhydric alcohols such as glycerin and ethylene glycol; antifoaming agents; mold release agents and the like. However, other components are not limited to these examples.

The content of the resin component derived from the non-petroleum component is preferably 10 to 50% by mass, more preferably 20 to 50% by mass, still more preferably 25 to 50% by mass, based on the total mass of the clearing agent. When the content of the resin component is at least the above lower limit value, it becomes easy to obtain an excellent transparency when applied to a paper substrate. It also makes it easier to obtain transparent paper that is environmentally friendly. When the content of the resin component is not more than the upper limit value, the clearing agent easily permeates into the inside of the paper base material, and the impregnation property is improved.

The content of the colorant is preferably 0.02 to 0.5% by mass, more preferably 0.03 to 0.4% by mass, and 0.03 to 0.3% by mass with respect to the total mass of the clearing agent. Is even more preferable. When the content of the colorant is at least the above lower limit value, the reflection of light on the paper substrate is suppressed, and it becomes easy to obtain an excellent transparency. When the content of the colorant is not more than the upper limit value, it is possible to prevent the color tone of the paper base material from being significantly deviated while suppressing light reflection.

The content of the alcohol having 1 to 6 carbon atoms is preferably 40 to 80% by mass, more preferably 50 to 80% by mass, still more preferably 50 to 70% by mass, based on the total mass of the clearing agent. When the content of the alcohol having 1 to 6 carbon atoms is at least the above lower limit value, the resin component is sufficiently dissolved, the clearing agent easily permeates between the fibers of the pulp, and the impregnation property is improved. When the content of the alcohol having 1 to 6 carbon atoms is not more than the above upper limit value, it becomes easy to obtain an excellent transparency when applied to a paper substrate.

(Manufacturing method of transparent agent)
The clearing agent of the present invention can be produced, for example, by mixing a resin component, a colorant, and an alcohol having 1 to 6 carbon atoms. Other components may be added as needed during mixing. The temperature at the time of mixing can be appropriately set in consideration of the solubility of the resin component and the colorant in alcohol.

(Mechanism of action)
The clearing agent of the present invention described above contains a colorant in addition to a resin component and an alcohol having 1 to 6 carbon atoms. When the clearing agent of the present invention is applied to a paper base material, the resin component is impregnated between the fibers of the pulp and solidified, and the air layer is eliminated, so that the paper base material can be given a transparent feeling. In addition, the colorant can penetrate between the fibers of the pulp and absorb the light incident on the transparent paper between the fibers of the pulp. Therefore, diffused reflection and scattering of light on the transparent paper are suppressed, and the transparency when observed with the naked eye is improved.
Therefore, according to the transparent agent of the present invention, an excellent transparency can be obtained when applied to a paper substrate.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by the following description.

<Example 1>
(1) Preparation of clearing agent A 40% rosin sizing agent (product name: SPE, manufactured by Arakawa Chemical Industry Co., Ltd.) is diluted with absolute ethanol manufactured by Kenei Pharmaceutical Co., Ltd., and the solid rosin content is 23.5. An alcohol dilution of% by weight rosin was prepared. NAF5091 Black from Dainichiseika was dropped and added so as to be 0.2% by mass with respect to the total mass of this diluted solution, and a rotating / revolving mixer Awatori Rentaro ARE310 manufactured by Shinky Co., Ltd. was used. Dispersed to prepare a clearing agent.
(2) Preparation of transparent paper A commercially available glassine paper containing softwood kraft pulp and hardwood kraft pulp was used as a paper base material (separation freeness: 50 ml, basis weight: 35 g / m ² ). Dissolution freeness is based on JIS-P8121: 2012 in the Canadian standard drainage tester for the disintegrated pulp obtained by disintegrating the paper substrate in accordance with JIS-P8220: 2012 with a standard disintegrator. The degree of drainage was measured, and the degree of drainage was defined as the separation freeness of the paper substrate (the same applies hereinafter).
This paper substrate was impregnated with the clearing agent prepared in (1) using a hand K-Rox engraving roll (specification 100/18) manufactured by Laurent Co., Ltd. Specifically, by the rubber roll transfer method, a clearing agent is applied to each of the front and back surfaces of the paper substrate three times so that the amount of rosin is 10 g / m ² , dried at room temperature, and the transparent paper is made. Obtained.

<Example 2>
A transparent paper was obtained in the same manner as in Example 1 except that a clearing agent was prepared as shown in (1) below.
(1) Preparation of clearing agent 40% shellac (manufactured by Koyo Kagaku Co., Ltd.) is diluted with Kenei Pharmaceutical's absolute ethanol, and the solid content of shellac is 25.0% by mass. Was prepared. Navy 2G gran solution (indigo) of Sumifix HF manufactured by Sumika Chemtex Co., Ltd. was added dropwise so as to be 0.2% by mass with respect to the total mass of this diluted solution. A clearing agent was prepared by dispersing using a revolution mixer Awatori Rentaro ARE310.

<Example 3>
A transparent paper was obtained in the same manner as in Example 1 except that a clearing agent was prepared as shown in (1) below.
(1) Preparation of clearing agent Dilute a 40% rosin sizing agent (trademark: SPE Arakawa Chemical Industry Co., Ltd.) with isopropyl alcohol of Sankyo Chemical Co., Ltd., and the solid rosin content is 23.5% by mass. An alcohol diluent was prepared. NAF5091 Black from Dainichiseika was dropped and added so that it was 0.3% by mass with respect to the total mass of this diluted solution, and a rotating / revolving mixer Awatori Rentaro ARE310 manufactured by Shinky Co., Ltd. was used. Dispersed to prepare a clearing agent.

<Comparative Example 1>
A transparent paper was obtained in the same manner as in Example 1 except that a clearing agent was prepared as shown in (1) below.
(1) Preparation of clearing agent A 40% rosin sizing agent (product name: SPE manufactured by Arakawa Chemical Industry Co., Ltd.) is diluted with Kenei Pharmaceutical's absolute ethanol to make a rosin with a solid rosin content of 23.5% by mass. Alcohol diluted solution was prepared. This diluted solution was dispersed using the rotation / revolution mixer Awatori Rentaro ARE310 of Shinky Co., Ltd. to prepare a clearing agent.

<Comparative Example 2>
(1) Preparation of clearing agent A 10% starch paste solution (Ace C, manufactured by Oji Cornstarch) was used as a clearing agent.
(2) Preparation of transparent paper A commercially available glassine paper containing softwood kraft pulp and hardwood kraft pulp was used as a paper base material (separation freeness: 50 ml, basis weight 35 g / m ² ). This paper substrate was coated on each of the front and back surfaces of the paper substrate with a film applicator with a film thickness adjustment function manufactured by Allgood Co., Ltd. so that the amount of starch was 10 g / m ² . After each coating, the sheet was placed in a dryer DX302 room of Yamato Chemical Co., Ltd. at 110 ° C. for 30 seconds to dry the sheet, and double-sided coating was performed three times on each side to obtain transparent paper.

<Comparative Example 3>
(1) Preparation of Clearing Agent A 7% PVA (polyvinyl alcohol) solution (Denka Poval 103 manufactured by Denka) was used as a clearing agent.
(2) Preparation of transparent paper Commercially available glassine paper (dissolution freeness: 50 ml, basis weight 35 g / m ² ) containing softwood kraft pulp and hardwood kraft pulp was used as a paper base material. This paper substrate was coated on each of the front and back surfaces of the paper substrate with a film applicator with a film thickness adjusting function manufactured by Allgood Co., Ltd. so that the amount of PVA was 10 g / m ² . Here, the sheet was dried by putting it in a dryer DX302 room of Yamato Chemical Co., Ltd., which was heated to 110 ° C. after each coating for 30 seconds, and double-sided coating was performed three times on each side to obtain transparent paper.

<Evaluation method>
The transparent paper of each example was measured and evaluated by the following method. The results are shown in Table 1.

(Opacity of transparent area)
According to JIS P8149, it was measured with the color meter SC-WT of Suga Test Instruments.

(Haze of transparent area)
It was measured using Haze Meter NDH 5000 manufactured by Nippon Denshoku Kogyo Co., Ltd. according to ISO 147821 and JIS K7136. The haze is a numerical value of the ratio of the diffused light component to the total light transmittance.

(B ^* in the transparent area)
b ^* was measured with a Spectro Color Meter SE 2000 manufactured by Nippon Denshoku Kogyo Co., Ltd. according to JIS Z 8781-4.

(Smoothness of transparent area)
JAPAN TAPPI Paper and Pulp Test Method No. 5-2, Oken smoothness was measured by the method specified in JIS P8155 and used as the smoothness.

In Examples 1 to 3, the opacity was 10% or less, the haze was 80% or less, the transparency was high in terms of visual appearance, and a sufficient transparency was obtained. In addition, the hue b ^* was in the range of -10 to +3.0, the hue was low, and it could be used as a substitute for a transparent plastic material.
In Comparative Example 1, although it was transparent, it had a hue b ^* of +3.97, had a strong yellowish color, was difficult to use as a general packaging material, and could not be used as a substitute for a transparent plastic material. ..
In Comparative Examples 2 and 3, the opacity exceeded 25%, and sufficient transparency could not be obtained.

The transparent paper, packaging material, and label of the present invention are excellent in transparency, can suppress the generation of microplastic derived from petrochemical resin, and are environmentally friendly.
The clearing agent of the present invention has an excellent transparency when applied to a paper substrate, can suppress the generation of microplastics derived from petrochemical resins, and is environmentally friendly.

Claims (15)

The resin component derived from the non-petroleum component has a transparent region impregnated in at least a part of the paper substrate, and has a transparent region.
A colorant is present in the transparent region,
A transparent paper having an opacity of 4 to 25% as measured according to JIS P 8149 of the transparent region. The transparent paper according to claim 1, wherein the hue b ^* measured by using a light source containing ultraviolet rays according to JIS Z 8781-4 in the transparent region is -10 to +3. The transparent paper according to claim 1 or 2, wherein the resin component contains at least one of shellac and rosin. The transparent paper according to any one of claims 1 to 3, wherein the colorant has a complementary color relationship with the color of the resin component. The transparent paper according to claim 4, wherein the colorant is at least one selected from the group consisting of a blue colorant, a purple colorant, and a black colorant. The transparent paper according to any one of claims 1 to 5, wherein the paper base material has a paper density of 20 to 70 g / cm ² . JAPAN TAPPI Paper / Pulp Test Method No. in the transparent region. The transparent paper according to any one of claims 1 to 6, wherein the smoothness measured according to 5-2 is 200 to 5000 sec. The transparent paper according to any one of claims 1 to 7, wherein the haze measured according to JIS-K7136 of the transparent region is 80% or less. A packaging material having the transparent paper according to any one of claims 1 to 8. A label having the transparent paper according to any one of claims 1 to 8. A clearing agent containing a resin component derived from a non-petroleum component, a colorant, and an alcohol having 1 to 6 carbon atoms. The clearing agent according to claim 11, wherein the resin component contains at least one of shellac and rosin. The clearing agent according to claim 11 or 12, wherein the colorant has a complementary color relationship with the color of the resin component. The clearing agent according to claim 13, wherein the colorant is at least one selected from the group consisting of a blue colorant, a purple colorant, and a black colorant. The clearing agent according to any one of claims 11 to 14, wherein the content of the resin component is 10 to 50% by mass.