Paper transparentizing agent

Abstract

To provide environmentally friendly transparent paper with excellent transparency, useful as an alternative to a plastic material, and capable of suppressing the generation of microplastics derived from a petrochemical resin, and an environmentally friendly transparentizing agent capable of producing transparent paper excellent in transparency and useful as an alternative to a plastic material when applied to a paper substrate, and suppressing the generation of microplastics derived from the petrochemical resin.SOLUTION: Transparent paper has a transparent region in which at least a part of a paper substrate is impregnated with a resin component derived from a non-petroleum component, wherein a coloring agent is present in the transparent region, and an opacity of the transparent region measured according to JIS P8149 is 4 to 25%. A transparentizing agent includes the resin component derived from the non-petroleum component, the coloring agent, and alcohol having 1 to 6 carbon atoms.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to transparent paper, packaging materials, labels, and clarifying agents.

Background Art

[0002] As methods for increasing the transparency of paper, for example, there are a method of increasing the beating degree of pulp fibers and a method of impregnating the space of base paper with resin. The method of increasing the beating degree of pulp fibers is used in the production of glassine paper, tracing paper, etc., and the method of impregnating with resin is used in the production of oil paper, wax paper, etc. Regarding the method of impregnating with resin, various methods have been proposed for the purpose of improving transparency (for example, Patent Documents 1 and 2).

[0003] In Patent Document 1, it is proposed to obtain transparent paper using a clarifying agent in which paraffin wax is blended in an organic solvent solution of resin. Further, in Patent Document 2, transparent paper to which a clarifying agent containing a non-fossilized alkali-soluble resin such as shellac is applied has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, against the background of the promotion of plastic reduction in various products such as packaging materials, the inventors of the present invention have come up with the idea of substituting a transparent plastic material currently on the market with transparent paper. Transparent paper has the advantage that it can be recycled after being recovered as waste paper and subjected to defibration treatment. However, in the transparent papers of Patent Documents 1 and 2, the transparency is insufficient for use as a substitute for plastic materials. In addition, since the clarifying agent of Patent Document 1 contains a resin derived from petroleum components, microplastics may be generated, making it unsuitable from the perspective of environmental conservation.

[0006] The present invention provides 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; and an environmentally friendly clarifying agent that provides a transparent paper with excellent transparency, is useful as a substitute for plastic materials, and can suppress the generation of microplastics derived from petrochemical resins when applied to a paper substrate.

Means for Solving the Problems

[0007] The present invention has the following aspects. [1] A transparent paper having a transparent region in which a resin component derived from non-petroleum components is impregnated in at least a part of a paper substrate region, a colorant being present in the transparent region, and the opacity of the transparent region measured according to JIS P 8149 being 4 to 25%. [2] The b value of the hue of the transparent region measured using a light source including ultraviolet rays according to JIS Z 8781-4 * is -10 to +3, the transparent paper of [1]. [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 of [4], wherein the colorant is at least one selected from the group consisting of blue-based colorants, purple-based colorants, and black-based colorants. [6] The basis weight of the paper substrate is 20 to 70 g / m 2 The transparent paper according to any one of [1] to [5]. [7] The transparent paper according to any one of [1] to [6], wherein the smoothness of the transparent region measured according to JAPAN TAPPI Paper and Pulp Test Method No. 5-2 is 200 to 5000 sec. [8] The transparency 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 transparency paper according to any one of [1] to [8].

[10] A label having the transparency paper according to any one of [1] to [8].

[11] A clarifying agent containing a resin component derived from a non-petroleum component, a colorant, and an alcohol having 1 to 6 carbon atoms.

[12] The clarifying agent according to

[11] , wherein the resin component contains at least one of shellac and rosin.

[13] The clarifying agent according to

[11] or

[12] , wherein the colorant is in a complementary color relationship with the color of the resin component.

[14] The clarifying agent according to

[13] , wherein the colorant is at least one selected from the group consisting of blue-based colorants, purple-based colorants, and black-based colorants.

[15] The clarifying agent according to any one of

[11] to

[14] , wherein the content of the resin component is 10 to 50% by mass. [Effect of the Invention]

[0008] According to the present invention, there is provided an environmentally friendly transparency paper that is excellent in transparency, useful as a substitute for plastic materials, and can suppress the generation of microplastics derived from petrochemical resins; an environmentally friendly transparency paper that is excellent in transparency when applied to a paper substrate, useful as a substitute for plastic materials, and can suppress the generation of microplastics derived from petrochemical resins, and a clarifying agent are provided. [Embodiments for Carrying Out the Invention]

[0009] [Transparency Paper] The transparency paper of the present invention is composed of a paper substrate and has a transparent region in which a resin component is impregnated in at least a part of the region of the paper substrate. The resin component is derived from a non-petroleum component. Here, the "resin derived from a non-petroleum component" means a resin produced from a raw material that does not contain petroleum components. As the resin component, for example, those containing at least one of shellac and rosin are preferable.

[0010] Shellac is a natural resin contained in the resinous substance secreted by the lac insect. The lac insect is reared using plant twigs. The lac insect sucks the sap and secretes a resinous substance. Shellac can be obtained by purifying the solidified product of the resinous substance secreted by the lac insect. Shellac is a component that impregnates between the fibers of pulp when applied to a paper substrate. When shellac impregnates between the fibers of the paper substrate and the air layer is excluded, the transparency of the transparent paper is obtained. Thus, shellac is a component for obtaining the transparency of transparent paper when applied to a paper substrate. In addition, since shellac is a thermoplastic resin, the transparent paper can be adhered by means such as heat sealing, and heat sealability can be imparted to the transparent paper.

[0011] The components of shellac vary depending on the purification method, product, etc. For example, resin acids such as aleuritic acid, jalapinic acid, and laccijalaric acid are the main components. Also, the color of shellac varies depending on the twigs and trees used for rearing the lac insect. For example, it is orange. Here, the shade of "orange" varies depending on the purification degree and product of shellac, but as long as the effects of the present invention can be obtained, it includes those from dark orange to light orange. Examples of commercially available shellac products include those of Nippon Shellac Kogyo Co., Ltd., Koyo Chemical Co., Ltd., Gifu Shellac Manufacturing Co., Ltd., etc.

[0012] Rosin is a natural resin contained in pine resin. Rosin can be obtained by purifying pine resin by distillation or the like. Rosin is a component that impregnates between the fibers of pulp when applied to a paper substrate. When rosin impregnates between the fibers of the paper substrate and the air layer is excluded, the transparency of the transparent paper is obtained. Thus, rosin is a component for obtaining the transparency of transparent paper when applied to a paper substrate. In addition, since rosin is a thermoplastic resin, heat sealability can be imparted to the transparent paper.

[0013] The components of rosin vary depending on the purification method, product, etc. For example, rosin acids such as abietic acid, palustric acid, and isopimaric acid are the main components. Also, the color of rosin varies depending on the tree used for resin tapping, the degree of purification, the product, etc., and is, for example, amber. Here, the shade of "amber" varies depending on the degree of purification of rosin and the product, but as long as the effects of the present invention can be obtained, it includes those from a dark amber to a light amber. Examples of commercially available rosin products include those of Arakawa Chemical Industries, Ltd. and Harima Chemicals Group, Inc.

[0014] A colorant is present in the transparent region. 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 is obtained.

[0015] In order to further improve the transparency, it is preferable that the colors of the pigment and the dye are in a complementary color relationship with the color of the resin component impregnated in the transparent region. Here, the "colors in a complementary color relationship" means, for example, a combination of colors located exactly opposite each other on the color wheel. However, as long as the effects of the present invention can be obtained, the "colors in a complementary color relationship" may be not only the colors located exactly opposite each other on the color wheel but also a combination of colors in the continuous region around them. For example, as the colorant, at least one or more selected from the group consisting of blue-based colorants, purple-based colorants, and black-based colorants are preferable. Also, the colorant may be used alone or in combination of two or more.

[0016] When the resin component contains either shellac or rosin, it is preferable that the colors of the pigment and the dye are in 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 in a complementary color relationship with the orange of shellac. Also, when the resin component contains amber rosin, the color of the pigment and the dye is preferably a color in a complementary color relationship with the amber of rosin.

[0017] When the resin component contains both shellac and rosin, the colors of the pigment and the dye preferably have a complementary color relationship with the color of the mixture of shellac and rosin. The color of the mixture of shellac and rosin can be specified by the color of a solution in which shellac and rosin are dissolved in a solvent such as alcohol in a state without pigment and dye.

[0018] The pigment is a colorant insoluble in alcohols having 1 to 6 carbon atoms described later. Examples of the pigment include products of DIC Corporation, Dainichi Seika Chemicals Co., Ltd., Toyo Ink Co., Ltd., Sumika Color Co., Ltd., etc. However, the pigment is not limited to these examples.

[0019] The dye is a colorant soluble in alcohols having 1 to 6 carbon atoms described later. Examples of the dye include products of Sumika Chemtex Corporation, Morishita Chemical Industry Co., Ltd., Nippon Kasei Kogyosho Co., Ltd., Nippon Kayaku Co., Ltd., etc. However, the dye is not limited to these examples.

[0020] The opacity of the transparent region is 4 to 25%, preferably 4 to 20%, and more preferably 4 to 15%. Since the opacity of the transparent region is below the upper limit value, an excellent transparency can be obtained. Since the opacity of the transparent region is above the lower limit value, it is not necessary to extremely advance the beating of the pulp used for the paper base material, and it is possible to manufacture transparent paper. The opacity of the transparent region is measured according to JIS P 8149.

[0021] The b value of the hue of the transparent region * is preferably -10 to +3. When the b value of the hue of the transparent region * is within the above numerical range, the transparency of the transparent paper is low, and it is easy to apply to uses as a substitute for transparent plastics. The b value of the hue of the transparent region * is measured using a light source including ultraviolet rays according to JIS Z 8781-4.

[0022] The smoothness of the transparent area is preferably 200 to 5000 seconds, more preferably 300 to 5000 seconds, and even more preferably 500 to 5000 seconds. When the smoothness of the transparent area is within the above numerical range, the transparency and printability of the transparent paper are improved. The smoothness of the transparent area can be measured in accordance with JAPAN TAPPI Paper and Pulp Test Method No. 5-2, JIS P8155.

[0023] The haze of the transparent area is preferably 80% or less, more preferably 50% or less, and even more preferably 40% or less. When the haze of the transparent area is below the above upper limit value, the transparent paper is even more excellent in transparency. The lower limit value of the haze of the transparent area is not particularly limited, but for example, it can be 10% or more. When the haze of the transparent area is 10% or more, it is not necessary to extremely advance the beating of the pulp used for the paper base material, and the manufacturing cost is reduced. The haze of the transparent area can be measured in accordance with JIS-K7136.

[0024] The density of the transparent area is preferably 0.7 to 1.2 g / cm 3 more preferably 0.8 to 1.2 g / cm 3 even more preferably 0.8 to 1.1 g / cm 3 When the density of the transparent area is above the above lower limit value, the air layer between the fibers is sufficiently excluded by the impregnation of the resin component, and the transparency of the transparent paper is further improved. When the density of the transparent area is below the above upper limit value, the formability of the transparent paper is improved. The density of the transparent area can be measured in accordance with TAPPI UM-522.

[0025] 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 area may be a partial area in the plane direction of the paper base material or the entire area. When the transparent area is a partial area of the transparent paper, the number of transparent areas is not limited, and the size and shape of each transparent area are also not limited. Since the transparency of the transparent paper can be obtained more sufficiently, it is preferable that the resin component is impregnated throughout the thickness direction of the paper base material in the transparent area.

[0026] Examples of the pulp constituting the paper substrate include wood pulp, mechanical pulp, cotton, hemp, waste paper pulp, non-wood pulp, etc. However, the pulp in the paper substrate is not limited to these examples. Examples of the wood pulp include, for example, softwood-derived pulp (NKP), hardwood-derived pulp (LKP), etc. Examples of the softwood-derived pulp include, for example, unbleached softwood kraft pulp (NUKP), bleached softwood kraft pulp (NBKP), semi-bleached softwood kraft pulp (NSBKP), softwood sulfite pulp (NSP), etc. Examples of the hardwood-derived pulp include, for example, unbleached hardwood kraft pulp (LUKP), bleached hardwood kraft pulp (LBKP), semi-bleached hardwood kraft pulp (LSBKP), hardwood sulfite pulp (LSP), etc. These softwood-derived pulps and hardwood-derived pulps may be used alone or in combination of two or more.

[0027] Examples of the mechanical pulp include, for example, stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), thermomechanical ground pulp (TGP), chemiground pulp (CGP), groundwood pulp (GP), thermomechanical pulp (TMP), etc. Examples of the waste paper pulp include, for example, disintegrated waste paper pulp, disintegrated and deinked waste paper pulp, disintegrated, deinked and bleached waste paper pulp. Examples of the waste paper used as the raw material for the waste paper pulp include, for example, tea waste paper, kraft envelope waste paper, magazine waste paper, newspaper waste paper, flyer waste paper, office waste paper, cardboard waste paper, high-quality waste paper, Kent waste paper, imitation waste paper, deed waste paper, etc. Examples of the non-wood pulp include various pulps such as pulp chemically or mechanically manufactured from non-wood fibers such as kenaf, hemp, reed, etc. These mechanical pulps, waste paper pulps, and non-wood pulps may be used alone or in combination of two or more.

[0028] As the pulp constituting the paper substrate, wood pulp is preferred. When using wood pulp as the pulp, it is preferable to use a combination of softwood-derived pulp and hardwood-derived pulp. When using waste paper pulp 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 the pulp constituting the paper base material. When the content of the waste paper pulp is below the above upper limit value, the transparent paper can be suitably applied as a packaging material for food and beverages. The lower limit value of the content of the waste paper pulp is 0% by mass.

[0029] The freeness of the pulp constituting the paper base material is preferably 50 to 600 ml, more preferably 100 to 500 ml, and even more preferably 100 to 400 ml. When the freeness of the pulp is at or above the above lower limit value, the strength of the transparent paper tends to increase. When the freeness of the pulp is at or below the above upper limit value, the tightness of the paper base material is improved, and a more sufficient transparency of the transparent paper can be obtained. The freeness of the paper base material is measured by the following method. That is, for the pulp obtained by disintegrating the paper base material in accordance with JIS-P8220:2012 using a standard disintegrator, the drainage degree is measured in accordance with JIS-P8121:2012 using a Canadian standard drainage degree tester, and the drainage degree is taken as the freeness of the paper base material.

[0030] The density of the paper base material is preferably 0.5 to 1.2 g / cm 3 more preferably 0.7 to 1.2 g / cm 3 even more preferably 0.8 to 1.2 g / cm 3 When the density of the paper base material is at or below the above upper limit value, the air layer between the fibers is sufficiently excluded in advance, and it is easy to obtain an excellent transparency in the transparent region. When the density of the paper base material is at or above the above lower limit value, it is easy to obtain a transparent paper with excellent formability. The density of the paper base material can be measured in accordance with TAPPI UM-522.

[0031] The basis weight of the paper base material is preferably 20 to 70 g / m 2 more preferably 20 to 60 g / m 2 even more preferably 30 to 60 g / m 2 When the basis weight of the paper base material is at or above the above lower limit value, it is easy to obtain an excellent transparency. When the basis weight of the paper base material is at or below the above upper limit value, it is easy to obtain good paper strength. ​

[0032] 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 substrate is equal to or greater than the lower limit value, it is easy to obtain transparent paper with excellent strength. When the thickness of the paper substrate is equal to or less than the upper limit value, it is easy to obtain transparent paper with excellent transparency. The thickness of the paper substrate can be the average value of the values measured by observing the cross-section of the transparent paper with a scanning electron microscope (SEM).

[0033] 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 substrate is within the above numerical range, it is easy to obtain transparent paper with excellent transparency and printability. The smoothness of the paper substrate can be measured according to JAPAN TAPPI Paper and Pulp Test Method No. 5-2, JIS P8155.

[0034] The transparent paper of the present invention may have a coating layer containing 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, gloss can be imparted to the transparent paper. The components of OP varnish vary depending on products, manufacturers, etc., but OP varnish containing at least one selected from the group consisting of linseed oil, tung oil, and nitrocellulose is preferred. Examples of commercially available OP varnishes include products of Toyo Ink Co., Ltd., T&K TOKA Co., Ltd., and Fuji Ink Manufacturing Co., Ltd.

[0035] (Method for manufacturing transparent paper) The transparent paper of the present invention can be manufactured, for example, by applying the transparentizing agent of the present invention described below to at least a part of at least one surface of a paper substrate, impregnating the paper substrate with the transparentizing agent, and forming a transparent region. When obtaining transparent paper by applying the transparentizing 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 transparency agent is applied may be one side or both sides of the paper substrate. The method of applying the transparency agent is not particularly limited. For example, various coating methods such as spray coating, curtain coating, roll coating, bar coating, blade coating, gravure coating, dip coating, etc. can be used.

[0036] When providing a coating layer containing OP varnish in the transparent region, the transparency agent may be applied to one surface of the paper substrate, the paper substrate may be impregnated with the transparency agent, and then the OP varnish may be applied to the other surface of the paper substrate to provide a coating layer containing OP varnish. Alternatively, the OP varnish may be applied to one surface of the paper substrate to provide a coating layer containing OP varnish, and then the transparency agent may be applied to the other surface of the paper substrate to impregnate the paper substrate with the transparency agent. Or the transparency agent may be applied to both surfaces of the paper substrate, the paper substrate may be impregnated with the transparency agent from both surfaces inward, and then the 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.

[0037] The method for manufacturing the paper substrate is not particularly limited. For example, a method including a step of beating the pulp used as the raw material of the paper substrate, a step of papermaking the pulp slurry containing the beaten pulp, and a step of drying the wet sheet obtained by papermaking can be mentioned. In the beating step, it is preferable to beat the raw material pulp until the freeness of the finished product becomes 30 to 550 ml, preferably 10 to 500 ml, so that the freeness of the paper substrate for disintegration becomes 50 to 600 ml. The beater used in the beating step is not particularly limited. For example, a double disk refiner can be mentioned.

[0038] The paper machine used in the papermaking step is not particularly limited. For example, a fourdrinier paper machine, a cylinder paper machine, a vat paper machine, etc. can be mentioned. After papermaking and through the drying process, the surface of the paper base material obtained may be subjected to a smoothing treatment. By performing the smoothing treatment, the surface strength, printability, etc. can be enhanced. Examples of the smoothing treatment include a method of pressurizing the paper base material between reels capable of being pressurized. The apparatus for performing the smoothing treatment is not particularly limited. For example, the product is finished by passing the paper through a machine calender, a gloss calender, a soft nip calender, etc. in front of the winder section. A machine calender and a super calender may be used in combination, or a super calender may be used instead of the machine calender.

[0039] (Function mechanism) In the transparent paper of the present invention described above, since the colorant exists in the transparent region impregnated with the resin component, the colorant that has entered between the pulp fibers can absorb the light incident on the transparent paper between the pulp fibers. Therefore, the irregular reflection and scattering of light in the transparent paper are suppressed, the transparency when observed with the naked eye is improved, and the opacity is also reduced. As a result, sufficient transparency can be obtained for use as a substitute for transparent plastic materials. In addition, since the resin component impregnated in the transparent region is derived from non-petroleum components, the generation of microplastics derived from petrochemical resins can be suppressed, and it is environmentally friendly.

[0040] (Applications) Examples of the applications of the transparent paper of the present invention include packaging materials, labels, envelopes, etc. In particular, the transparent paper having a transparent region impregnated with a resin component containing shellac can be suitably applied to applications such as packaging materials for food and beverages because shellac is edible. When the transparent paper of the present invention is applied to the use of a packaging material, a packaging container can be obtained by adhering the transparent paper by a method such as heat sealing to form the transparent paper into, for example, a bag shape. When the transparent paper of the present invention is applied to the use of 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 adhesiveness may be imparted to one surface of the transparent paper and adhered to the surface of a container or the like to be used as a transparent label. 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 adhesiveness is imparted.

[0041] <Transparency agent> The transparency agent of the present invention contains a resin component derived from non-petroleum components, a colorant, and an alcohol having 1 to 6 carbon atoms. The details and preferred embodiments of the resin component and the colorant derived from non-petroleum components are the same as those described in the section of <Transparent paper> above. The transparency agent of the present invention may further contain other components other than these components.

[0042] The alcohol having 1 to 6 carbon atoms is a component that functions as a liquid medium of the transparency agent. By using an alcohol having 1 to 6 carbon atoms, it is possible to reduce the occurrence of curling, warping, and unevenness after coating and drying the transparency agent. Examples of the alcohol having 1 to 6 carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, n-pentanol, n-hexanol, etc. Among these, since the heat sealability of the transparent paper to which the transparency agent is applied is improved, methanol, ethanol, n-propanol, and isopropanol are preferred as the alcohol, ethanol and isopropanol are more preferred, and ethanol is particularly preferred. However, the alcohol having 1 to 6 carbon atoms is not limited to these examples.

[0043] Other components in the transparency agent are not particularly limited as long as the effects of the present invention can be obtained. For example, an aqueous medium such as water; basic substances such as ammonia, ethylenediamine, and triethylamine; polyhydric alcohols such as glycerin and ethylene glycol; defoaming agents; release agents, etc. can be mentioned. However, other components are not limited to these examples.

[0044] The content of the resin component derived from non-petroleum components is preferably 10 to 50% by mass, more preferably 20 to 50% by mass, and still more preferably 25 to 50% by mass based on the total mass of the clarifying agent. When the content of the resin component is at least the lower limit value, it is easy to obtain excellent transparency when applied to the paper substrate. Also, it is easy to obtain an environmentally friendly transparent paper. When the content of the resin component is at most the upper limit value, the clarifying agent easily penetrates into the paper substrate, and the impregnation property is improved.

[0045] The content of the colorant is preferably 0.02 to 0.5% by mass, more preferably 0.03 to 0.4% by mass, and still more preferably 0.03 to 0.3% by mass based on the total mass of the clarifying agent. When the content of the colorant is at least the lower limit value, the reflection of light by the paper substrate is suppressed, and it is easy to obtain excellent transparency. When the content of the colorant is at most the upper limit value, it is possible to prevent the color tone of the paper substrate from deviating significantly while suppressing light reflection.

[0046] 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, and still more preferably 50 to 70% by mass based on the total mass of the clarifying agent. When the content of the alcohol having 1 to 6 carbon atoms is at least the lower limit value, the resin component is sufficiently dissolved, the clarifying agent easily penetrates 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 at most the upper limit value, it is easy to obtain excellent transparency when applied to the paper substrate.

[0047] (Manufacturing method of clarifying agent) The clarifying 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 necessary during mixing. The temperature during mixing can be appropriately set in consideration of the solubility of the resin component and the colorant in the alcohol.

[0048] (Mechanism of action) The clarifying agent of the present invention described above contains a resin component, an alcohol having 1 to 6 carbon atoms, and a colorant. When the clarifying agent of the present invention is applied to a paper substrate, the resin component impregnates between the fibers of the pulp, solidifies, and the air layer is eliminated, thereby imparting a transparent feeling to the paper substrate. In addition, the colorant can enter between the fibers of the pulp and absorb the light incident on the transparent paper between the fibers of the pulp. Therefore, the irregular reflection and scattering of light in the transparent paper are suppressed, and the transparency when observed with the naked eye is improved. Therefore, according to the clarifying agent of the present invention, excellent transparency can be obtained when applied to a paper substrate.

Example

[0049] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited by the following description.

[0050] <Example 1> (1) Preparation of clarifying agent A 40% rosin sizing agent (product name: SPE, manufactured by Arakawa Chemical Industries) was diluted with absolute ethanol manufactured by Ken-ei Pharmaceutical Co., Ltd. to prepare an alcohol dilution of rosin with a solid content of rosin of 23.5% by mass. NAF5091 black from Dainichi Seika was added dropwise so as to be 0.2% by mass based on the total mass of this dilution, and dispersed using a rotation / revolution mixer Awa Tori Ren Tarou ARE310 manufactured by Shin-Kee Co., Ltd. to prepare a clarifying agent. (2) Production of transparent paper A commercially available glassine paper containing softwood kraft pulp and hardwood kraft pulp was used as the paper substrate (freeness: 50 ml, basis weight: 35 g / m 2 ). The freeness was measured for the pulp obtained by subjecting the paper substrate to a disintegration treatment in accordance with JIS-P8220:2012 using a standard disintegrator, using a Canadian standard drainage tester in accordance with JIS-P8121:2012, and the drainage was used as the freeness of the paper substrate (the same applies hereinafter). This paper substrate was impregnated with the clarifying agent prepared in (1) using a hand K locks engraving roll (specification 100 / 18) manufactured by Rollan Co., Ltd. Specifically, by the rubber roll transfer method, the rosin amount was 10 g / m 2So that it becomes like this, a sizing agent was applied three times to each of the front and back surfaces of the paper base material, dried at room temperature, and transparent paper was obtained.

[0051] <Example 2> Transparent paper was obtained in the same manner as in Example 1, except that the sizing agent was prepared as shown in (1) below. (1) Preparation of the sizing agent 40% shellac (manufactured by Koyo Chemical Co., Ltd.) was diluted with anhydrous ethanol from Ken-ei Pharmaceutical Co., Ltd. to prepare an alcohol dilution of shellac with a solid content of 25.0% by mass of shellac. To this dilution, Navy 2G gran liquid (blue) of Sumifix HF manufactured by Sumitomo Chemical Tex Co., Ltd. was added dropwise so as to be 0.2% by mass based on the total mass of this dilution, and dispersed using a rotation-revolution mixer Awatori Renjiro ARE310 manufactured by Shinki Co., Ltd. to prepare the sizing agent.

[0052] <Example 3> Transparent paper was obtained in the same manner as in Example 1, except that the sizing agent was prepared as shown in (1) below. (1) Preparation of the sizing agent 40% rosin sizing agent (trademark: SPE manufactured by Arakawa Chemical Industries, Ltd.) was diluted with isopropyl alcohol from Sankyo Chemical Co., Ltd. to prepare an alcohol dilution with a solid content of 23.5% by mass of rosin. To this dilution, NAF5091 black from Dainichi Seika Co., Ltd. was added dropwise so as to be 0.3% by mass based on the total mass of this dilution, and dispersed using a rotation-revolution mixer Awatori Renjiro ARE310 manufactured by Shinki Co., Ltd. to prepare the sizing agent.

[0053] <Comparative Example 1> Transparent paper was obtained in the same manner as in Example 1, except that the sizing agent was prepared as shown in (1) below. (1) Preparation of the sizing agent 40% rosin sizing agent (product name: SPE manufactured by Arakawa Chemical Industries, Ltd.) was diluted with anhydrous ethanol from Ken-ei Pharmaceutical Co., Ltd. to prepare an alcohol dilution of rosin with a solid content of 23.5% by mass of rosin. This dilution was dispersed using a rotation-revolution mixer Awatori Renjiro ARE310 manufactured by Shinki Co., Ltd. to prepare the sizing agent.

[0054] <Comparative Example 2> (1) Preparation of the clarifying agent A 10% starch paste solution (Ace C, manufactured by Oji Cornstarch Co., Ltd.) was used as the clarifying agent. (2) Preparation of the transparent paper A commercially available glassine paper containing a mixture of softwood kraft pulp and hardwood kraft pulp was used as the paper substrate (freeness: 50 ml, basis weight: 35 g / m 2 ²). Using a film applicator with a film thickness adjustment function manufactured by Allgood Co., Ltd., the paper substrate was coated on both the front and back surfaces so that the starch amount was 10 g / m 2 . After each coating, the sheet was dried by placing it in a dryer DX302 chamber of Yamato Chemical Co., Ltd. at 110 °C for 30 seconds. Double-sided coating was performed three times on each side to obtain the transparent paper.

[0055] <Comparative Example 3> (1) Preparation of the clarifying agent A 7% PVA (polyvinyl alcohol) solution (Denka Popar 103 manufactured by Denka Co., Ltd.) was used as the clarifying agent. (2) Preparation of the transparent paper A commercially available glassine paper containing a mixture of softwood kraft pulp and hardwood kraft pulp (freeness: 50 ml, basis weight: 35 g / m 2 ²) was used as the paper substrate. Using a film applicator with a film thickness adjustment function manufactured by Allgood Co., Ltd., the paper substrate was coated on both the front and back surfaces so that the PVA amount was 10 g / m 2 . Here, after each coating, the sheet was dried by placing it in a dryer DX302 chamber of Yamato Chemical Co., Ltd. at 110 °C for 30 seconds. Double-sided coating was performed three times on each side to obtain the transparent paper.

[0056] <Evaluation method> For the transparent papers of each example, measurement and evaluation were performed by the following methods. The results are shown in Table 1.

[0057] (Opacity of the transparent area) Measured with a colorimeter SC-WT of Suga Test Instruments Co., Ltd. in accordance with JIS P8149.

[0058] (Haze in transparent areas) It was measured using a Nippon Denshoku Industries Haze Meter NDH 5000 in accordance with ISO 14782-1 and JIS K7136. Haze is a numerical representation of the proportion of diffuse light components in the total light transmittance.

[0059] (Transparent area b * ) b * was measured using a Spectro Color Meter SE 2000 manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS Z 8781-4.

[0060] (Smoothness of transparent areas) The Oken smoothness was measured according to the method specified in JAPAN TAPPI paper pulp testing method No. 5-2 and JIS P8155, and was taken as the smoothness.

[0061] [Table 1]

[0062] In Examples 1 to 3, the opacity was 10% or less, and the haze was 80% or less, and the transparency was high and sufficient transparency was obtained when viewed visually. * The color was in the range of -10 to +3.0, and the material had little color and could be used as a substitute for transparent plastic materials. In Comparative Example 1, the transparency was good, but the color b * The rating was +3.97, which meant that the material was too yellowish and difficult to use as a general packaging material, and could not be used as a substitute for transparent plastic materials. In both Comparative Examples 2 and 3, the opacity exceeded 25%, and sufficient transparency was not obtained. [Industrial Applicability]

[0063] The transparent paper, packaging material, and label of the present invention have excellent transparency and are environmentally friendly as they can suppress the generation of microplastics derived from petrochemical resins. The clarifying agent of the present invention can provide excellent transparency when applied to a paper substrate, can suppress the generation of microplastics derived from petrochemical resins, and is environmentally friendly.

Claims

1. A transparent region is formed by impregnating at least a portion of a paper substrate with a resin component derived from a non-petroleum component, a colorant is present in the transparent region; A transparent paper, wherein the opacity of the transparent area is 4 to 25% as measured according to JIS P 8149.

2. The hue of the transparent area measured using a light source including ultraviolet light in accordance with JIS Z 8781-4 is b ＊ The transparent paper according to claim 1, wherein the transparency is -10 to +3.

3. The transparent paper according to claim 1 or 2, wherein the resin component includes at least one of shellac and rosin.

4. The transparent paper according to any one of claims 1 to 3, wherein the colorant has a complementary color to the color of the resin component.

5. 5. The transparent paper according to claim 4, wherein the colorant is at least one selected from the group consisting of a blue-based colorant, a violet-based colorant, and a black-based colorant.

6. The paper base material has a basis weight of 20 to 70 g / m ２ The transparent paper according to any one of claims 1 to 5,

7. 7. The transparent paper according to claim 1, wherein the smoothness of the transparent region is 200 to 5000 sec, as measured according to JAPAN TAPPI Paper and Pulp Test Method No. 5-2.

8. The transparent paper according to any one of claims 1 to 7, wherein the haze of the transparent region measured in accordance with JIS-K7136 is 80% or less.

9. A packaging material comprising the transparent paper according to any one of claims 1 to 8.

10. A label comprising the transparent paper according to any one of claims 1 to 8.

11. The clarifying agent comprises a resin component derived from a non-petroleum component, a colorant, and an alcohol having 1 to 6 carbon atoms.

12. The clarifying agent of claim 11 , wherein the resin component comprises at least one of shellac and rosin.

13. The clarifying agent according to claim 11 or 12, wherein the colorant has a complementary color to the color of the resin component.

14. The clarifying agent according to claim 13, wherein the colorant is at least one selected from the group consisting of blue-based colorants, violet-based colorants, and black-based colorants.

15. The clarifying agent according to any one of claims 11 to 14, wherein the content of the resin component is 10 to 50 mass%.

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