JP2015232191A - Coating material for paper, paper product, and method for producing paper product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating material for paper excellent in water resistance, oil resistance and antibacterial properties and also capable of being thinly, uniformly coating to the surface of paper.SOLUTION: Provided is a coating material for paper comprising: a liquid paraffin; sucrose fatty acid ester; a water soluble resin; and an antibacterial agent having the average particle diameter of 1.5 μm or lower. As the antibacterial agent, the use of a silver base antibacterial agent is preferable, and the viscosity at 23°C in the liquid paraffin is preferably 1.12×10Pa s or more. Further, the HLB value of the sucrose fatty acid ester is preferably 2 or lower, and, as the water-soluble resin, (meth)acrylic resin or the like are preferable. There is also provided a paper product in which a cured film of the coating material for paper is formed on the surface of paper, and the average film thickness of the cured film is 0.3 to 1 μm.

Description

  The present invention relates to a paint for paper, a paper product, a paper packaging container, and a method for manufacturing a paper product.

  Crustaceans such as salmon and shrimp are usually frozen after the shells are sufficiently wetted with water in order to suppress discoloration called freezing. For this reason, since the container for freezing crustaceans requires sufficient water resistance, the container made from a polystyrene foam is conventionally used (patent document 1). Laminated paper is used for fast food containers used in fast food stores and the like.

  However, the polystyrene foam container cannot be folded and transported, increasing the transport cost, and it is necessary to dispose as plastic waste. In addition, if you want to display some information on the container (for example, the design of the contents of shark and shrimp), it is technically difficult to print clearly on the surface of the expanded polystyrene, so the contents of the expanded polystyrene container Need to be transferred to a paper container (for example, a paper container for over-the-counter sales) on which clear printing is performed. Laminated paper has a structure in which a thin plastic film is laminated on the surface of the paper to give it water and oil resistance. When discarded, the paper and plastic film can be easily recycled (recycled like printed paper). It cannot be recycled as waste paper in large quantities using the device.

  From such a situation, it is desired to construct a container that replaces the polystyrene foam container with paper, but the paper product has a problem of low water resistance. In addition, paper products are required to have not only water resistance but also antibacterial properties. In addition to water resistance, paper products used in fast food stores are also required to have oil resistance and antibacterial properties (for takeout purposes).

  In order to solve this problem, a paper paint containing liquid paraffin, sucrose fatty acid ester, water-soluble resin and antibacterial agent has been proposed (Patent Document 2).

Japanese Patent Laid-Open No. 7-10179 Japanese Patent No. 4551992

  By the way, it is possible to shorten the drying time after coating paper paint on the surface of paper, save the amount of paper paint used, and widely used gravure printing machine without using a dedicated coating machine Therefore, it is preferable to thin the cured film of the paper paint formed on the paper surface. Especially for thin paper used in fast food stores and convenience stores, high-speed surface coating is required from the viewpoint of production cost, so high-speed coating by a gravure printing machine is essential. However, as shown in FIG. 1 (a), when attempting to further reduce the thickness of the cured film using the paper paint of Patent Document 2, relatively large bubbles are formed on the surface of the cured film of the paper paint. There is a possibility that the cured film is not uniformly formed on the entire surface of the paper. Therefore, the paper paint of Patent Document 2 still has room for improvement.

  The present invention has been made in view of the above circumstances, and its purpose is to provide a paper paint that is excellent in water resistance, oil resistance and antibacterial properties and can be applied thinly and uniformly on the paper surface. It is to be.

  The inventors of the present invention have made extensive studies in order to solve the above problems. As a result, it has been found that the above problem can be solved by using an antibacterial agent having a relatively small average particle diameter, and the present invention has been completed. The present invention specifically provides the following.

(1) The present invention is a paper paint applied to the surface of paper, which contains liquid paraffin, sucrose fatty acid ester, water-soluble resin, and antibacterial agent, and the liquid paraffin is JIS K 5600-2 -3, the viscosity at 23 ° C. measured according to the method -3 is 1.12 × 10 ⁻¹ Pa · s or more, and the antibacterial agent is an average particle diameter measured according to the JIS H 7804 method using a scanning electron microscope. Is a paper paint having a thickness of 0.3 μm or more and 1.5 μm or less.

  (2) Moreover, this invention is a coating material for paper as described in (1) whose said antibacterial agent is a silver type antibacterial agent.

  (3) Further, in the present invention, the content of the antibacterial agent is 0.5% by mass or more and 1.5% by mass or less based on the total mass of the paper coating material. It is a paint for paper as described.

  (4) Moreover, this invention is a paper coating material in any one of (1) to (3) whose HLB value of the said sucrose fatty acid ester is 2 or less.

  (5) In the present invention, the content of the sucrose fatty acid ester is from 0.35% by mass to 0.8% by mass with respect to the total mass of the paper coating material. ).

  (6) Further, according to the present invention, the water-soluble resin comprises a (meth) acrylic resin, a styrene-butadiene copolymer resin, an acrylonitrile-butadiene-styrene copolymer resin, and an acrylonitrile-styrene copolymer resin. The paper paint according to any one of (1) to (5), comprising one or more selected from

  (7) Moreover, this invention is a paper product by which the cured film of the paper coating material in any one of (1) to (6) is formed in the surface of paper.

  (8) Moreover, this invention is an average film thickness of the said cured film measured according to JIS H8690 appendix 1 "Thickness test method by a scanning electron microscope". 0.3 micrometer or more and 1 micrometer or less, (7) The paper product as described in 1.

  (9) Moreover, this invention is a paper packaging container formed with the paper product as described in (7) or (8).

  (10) The present invention also includes a paper product including an application procedure for applying the paper paint according to any one of (1) to (6) to a paper surface, and a curing procedure for curing the paper paint. It is a manufacturing method.

  (11) Further, according to the present invention, the average thickness of the cured film of the paper paint measured in accordance with JIS H8690 Annex 1 “Thickness Test Method Using Scanning Electron Microscope” is 0.3 μm or more. The method for producing a paper product according to (10), wherein the method is performed so as to be 1 μm or less.

(12) Moreover, this invention is a procedure in which the said application | coating procedure is a procedure which apply | coats the said paper coating material with the gravure printing machine to the paper surface whose basis weight per 1 m < ² > is 200 g or less. This is a method for manufacturing paper products.

  ADVANTAGE OF THE INVENTION According to this invention, the paper coating material which is excellent in water resistance, oil resistance, and antibacterial property, and can be apply | coated thinly and uniformly on the paper surface can be provided.

It is an enlarged photograph when the surface of the cured film of the coating material for paper is observed with the scanning electron microscope about the paper product which concerns on Example 1 and Comparative Example 3. FIG. It is an enlarged photograph when the surface of the cured film of the paper coating material is observed with a scanning electron microscope for the paper product according to Example 1. It is an enlarged photograph when the surface of the cured film of the coating material for paper is observed with a scanning electron microscope about the paper product which concerns on the comparative example 1. FIG. It is an enlarged photograph when the surface of the cured film of the coating material for paper is observed with the scanning electron microscope about the paper product which concerns on the comparative example 2. FIG. It is an enlarged photograph when the cross section in the direction perpendicular | vertical with respect to the surface of the film | membrane of the cured film of paper paint is observed with a scanning electron microscope about the paper product which concerns on Example 1. FIG. It is an enlarged photograph when the surface of the cured film of the paper coating material is observed with a scanning electron microscope for the paper product according to Example 2.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. can do.

<Paint paint>
The paper paint according to the present invention contains liquid paraffin, sucrose fatty acid ester, water-soluble resin, and antibacterial agent, and liquid paraffin has a viscosity at 23 ° C. measured according to JIS K 5600-2-3 method. 1.12 × 10 ⁻¹ Pa · s or more, and the antibacterial agent has an average particle size of 0.3 μm or more and 1.5 μm or less measured according to the JIS H 7804 method using a scanning electron microscope.

[Liquid paraffin]
The paper paint of the present invention contains liquid paraffin. The liquid paraffin according to the present invention is sufficiently mixed and dispersed with the water-soluble resin contained in the paper paint by the action of the sucrose fatty acid ester contained in the paper paint. Therefore, by applying the paper paint according to the present invention to paper, even if the cured film of the paper paint formed on the paper surface is thinned, a paper product having excellent water resistance, oil resistance and antibacterial properties can be provided. .

  Although the kind of liquid paraffin is not specifically limited, From a heat resistant viewpoint which can be endured as a container for foods, it is preferable that it is at least one of normal paraffin, isoparaffin and cycloparaffin.

The viscosity of liquid paraffin is not particularly limited as long as the viscosity at 23 ° C. measured according to JIS K 5600-2-3 method is 1.12 × 10 ⁻¹ Pa · s or more, but the viscosity at 23 ° C. Is preferably 1.20 × 10 ⁻¹ Pa · s or more, and more preferably 1.50 × 10 ⁻¹ Pa · s or more and 3.05 × 10 ⁻¹ Pa · s or less. In the present specification, the viscosity means a value measured by the following method.

(1) First, check the viscometer according to the procedure described in “5 Checking the viscometer” of JIS K 5600-2-3. As a viscometer, a Brookfield viscometer LVDV2TCP (cone plate type system) is used.
(2) The measurement sample is passed through a sieve having an aperture of 125 μm and transferred into a clean container.
(3) Adjust the measurement sample to 23 ° C. ± 0.2 ° C.
(4) An appropriate amount of a measurement sample is put into a sample cup (product name: CPA-44YZ, manufactured by Brookfield) of the above viscometer while taking care not to mix bubbles.
(5) The sample cup is adjusted to a regular determined position, and the viscosity of the measurement sample is measured under the conditions shown in Table 1. In Table 1, the cone spindle is CPA-40Z manufactured by Brookfield.

  When the viscosity of the liquid paraffin is within the above range, the viscosity is imparted to the paper coating material. For example, it becomes easy to get wet with the printing roll of the printing press, and the coating material is uniformly applied to the paper surface. Water resistance and the like can be sufficiently imparted. If the viscosity of the liquid paraffin is too low, it may not be evenly wet on the printing roll of the printing press, and the paper paint may not be uniformly applied to the paper surface. If the viscosity of the liquid paraffin is too high, the fluidity of the liquid paraffin may be greatly reduced. Furthermore, when the viscosity of liquid paraffin is within the above range, the amount and size of bubbles appearing on the film surface when the paper paint is thinly applied to the paper and the cured film of the paper paint is thinned. Therefore, the paint can be uniformly applied to the paper surface.

  The content of the liquid paraffin is not particularly limited, but if it is too small, it is difficult to sufficiently impart water resistance and oil resistance, and if it is too large, a film made of paint may be formed on a paper product. Have difficulty. Therefore, the lower limit of the content of liquid paraffin is preferably 1% by mass, more preferably 5% by mass, and most preferably 10% by mass with respect to the solid content of all resins contained in the paper paint. is there. The upper limit of the solid content of liquid paraffin is preferably 50% by mass, more preferably 45% by mass, and most preferably 35% by mass with respect to the solid content of all resins.

[Sucrose fatty acid ester]
The paper paint according to the present invention contains a sucrose fatty acid ester. Liquid paraffin has extremely low compatibility with water-soluble resins and has a characteristic that it is difficult to disperse in water-soluble resins. Therefore, in order to use liquid paraffin together with water-soluble resin, it is necessary to improve dispersibility of liquid paraffin in water-soluble resin. Therefore, the paper paint according to the present invention contains a sucrose fatty acid ester.

  When a general surfactant is mixed with liquid paraffin (usually by stirring at a rotational speed of about 10,000 rpm or more using a homogenizer), a large amount of foam is generated, and there is a concern about leakage from the stirring device to the outside. Therefore, it is essential to use an antifoaming agent in combination. However, since sucrose fatty acid ester suppresses foaming even when mixed with liquid paraffin, the required amount of antifoaming agent can be reduced (no need to use an antifoaming agent), and paper paints can be produced. Cost reduction and safety improvement can be expected. Moreover, since sucrose fatty acid ester itself is excellent in safety, it is particularly advantageous in the case of producing a paper packaging container for packaging food.

  Specific examples of sucrose fatty acid esters include sucrose dioleate, sucrose distearate, sucrose dipalmitate, sucrose dimyristate, sucrose dilaurate, sucrose monooleate, sucrose Sugar monostearic acid ester, sucrose monopalmitic acid ester, sucrose monomyristic acid ester, sucrose monolauric acid ester and the like can be mentioned, and these can be used alone or in combination of two or more. Among these, a sucrose fatty acid ester having an HLB value of 2 or less is preferable, and a sucrose fatty acid ester having an HLB value of 1 or less is more preferable in that the dispersibility of the liquid paraffin and the antibacterial agent can be further improved. As such sucrose fatty acid ester, sucrose stearate ester (Mitsubishi Chemical Foods), sucrose palmitate (Mitsubishi Chemical Foods), sucrose oleate (Mitsubishi Chemical Foods), DK ester (Daiichi Kogyo Seiyaku Co., Ltd.).

  The content of sucrose fatty acid ester may be appropriately set according to the characteristics of the sucrose fatty acid ester, antibacterial agent and liquid paraffin used, but from the viewpoint of improving the dispersibility of liquid paraffin and antibacterial agent, 0.35 mass% or more is preferable with respect to the total mass, and 0.35 mass% or more and 0.8 mass% or less is more preferable. In consideration of the dilution ratio of the aqueous solvent contained in the paper solvent, the content is preferably 5% by mass or more and 10% by mass or less with respect to the solid content of the liquid paraffin.

(Water-soluble resin)
The paper paint of the present invention contains a water-soluble resin. Since the water-soluble resin has a predetermined viscosity, viscosity is imparted to the paper paint, and for example, the water-soluble resin is easily wetted with a printing roll of a printing press. Thereby, since a coating material is uniformly apply | coated to the surface of paper, water resistance etc. can fully be provided to paper.

  The water-soluble resin may be any water-soluble resin conventionally used in paints, such as polyvinyl alcohol resin, (meth) acrylic resin, epoxy resin, vinyl acetate resin, water-soluble varnish, styrene-butadiene copolymer. Examples thereof include a coalesced resin (SB resin), an acrylonitrile-butadiene-styrene copolymer resin (ABS resin), and an acrylonitrile-styrene copolymer resin (AS resin). In particular, since it does not exhibit tackiness when cured on the paper surface, it is difficult for the papers to adhere to each other in the process of winding the paper into a roll after forming a film on the thin paper surface, and the film after film formation is transparent. For this reason, when paper paint is used for food wrapping paper, the water-soluble resin does not impair the printing or color tone of the underlying wrapping paper. It is preferably at least one selected from the group consisting of a polymer resin, an acrylonitrile-butadiene-styrene copolymer resin, and an acrylonitrile-styrene copolymer resin.

  The content of the water-soluble resin is not particularly limited, but the solid content of the water-soluble resin is 3% by mass or more to 50% by mass with respect to the whole paper paint in that the viscosity of the paper paint can be within a suitable range. It is preferable that it is mass% or less, and it is more preferable that it is 15 mass% or more and 40 mass% or less.

[Antimicrobial agent]
The paper paint according to the present invention contains an antibacterial agent having an average particle size of 0.3 μm or more and 1.5 μm or less measured according to the JIS H 7804 method using a scanning electron microscope.

  The average particle size of the antibacterial agent is not particularly limited as long as it is 0.3 μm or more and 1.5 μm or less, but is preferably 0.5 μm or more and 1.0 μm or less, and most preferably 0.6 μm to 1.0 μm. preferable. If the average particle size of the antibacterial agent is too small, the antibacterial agent does not appear on the surface of the cured film of the paper coating material, and there is a possibility that sufficient antibacterial properties may not be obtained. If the average particle size of the antibacterial agent is too large, the amount of antibacterial agent that sinks into the coating film becomes too small compared to the thickness of the coating film when applied thinly on paper. The antibacterial agent easily falls off. On the other hand, if the average particle size of the antibacterial agent is too large, the antibacterial agent tends to settle in the paper coating material when the viscosity of the whole paper coating material is lowered for thin coating.

  In this specification, an average particle diameter shall mean the value measured according to the JISH7804 method using the scanning electron microscope (henceforth "FE-SEM"). The observation conditions of FE-SEM are as follows.

Model: JSM-7001F (JEOL)
Acceleration voltage: 5 kV
Working distance: 4.0 mm
Irradiation current: Small Signal: Secondary electron image Pretreatment: Conduction by Pt deposition

  Regarding the preparation of the sample to be observed, the roll paper is cut to a size that fits into the FE-SEM apparatus in order to perform measurement on a film made of the paper paint of the present invention applied to the roll paper surface. Generally, it cuts out to about 3 mm square.

  The measurement condition of the particle diameter is performed according to JIS H7804. Specifically, the measurement is performed for five or more representative fields randomly extracted. One field of view means a range projected on one monitor screen of an electron microscope. Therefore, five visual fields refer to five screens that are measured five times with an electron microscope and appear on the monitor.

  The shooting magnification is performed in accordance with JIS H7804. However, JIS H 7804 specifies that “the minimum magnification is 5000 times, but preferably 10,000 times.” In this specification, an antibacterial agent having an average particle size of 2.5 μm or more is measured. In the case of an object, the imaging magnification is set to 3000 times, and when the antibacterial agent having an average particle diameter of 1 μm to 2.5 μm is measured, the imaging magnification is set to 5000 times and the average particle diameter is 1 μm or less. When an antibacterial agent is a measurement target, the photographing magnification is set to 15000 times.

  The particle diameter is calculated according to JIS H7804.

  The particle size and particle size distribution are measured according to JIS H7804.

  The type of antibacterial agent is not particularly limited, but it is preferable to use a silver-based antibacterial agent because it is excellent in antibacterial properties. Examples of the silver-based antibacterial agent include silver supported antibacterial agents in which zeolite particles, silica gel particles, alumina particles, phosphate particles and the like are used as carriers, and a silver compound is supported on these carrier particles, and silver carbonate. An antibacterial agent may be used individually by 1 type, and may use 2 or more types together.

  Examples of the silver-supported zeolite particles include “Zeomic” (manufactured by Sinanen Zeomic). “Zeomic” is approved by the US Food and Drug Administration (FDA) as a food contact substance notification (FCN000047), and has a track record of being applicable to all food packaging resins.

  The content of the antibacterial agent in the paper coating material of the present invention is not particularly limited, but is preferably 0.5% by mass or more and 1.5% by mass or less with respect to the total mass of the paper coating material. So far, in paper paint, since an antibacterial agent having an average particle size of about 10 to 2.5 μm has been used, in order to suitably disperse the antibacterial agent throughout the cured film of the paper paint, It was necessary to apply the paper paint so that the thickness of the cured film was at least 3 μm or more, and to make the content of the antibacterial agent at least 2% by mass based on the total mass of the paper paint. However, since the average particle diameter of the antibacterial agent contained in the paper paint of the present invention is as small as 1.5 μm or less, even if the content is 1.5% by mass or less, a suitable antibacterial action is exhibited. Therefore, in the present invention, the content of the antibacterial agent is not less than 0.5% by mass and not more than 1.5% by mass.

[Other ingredients]
The paper paint according to the present invention may contain other components such as a fungicide, a dispersant, a dispersion medium and the like.

[Anti-mold agent]
The paper paint of the present invention may further contain a fungicide. The type of the fungicide is not particularly limited, and examples thereof include benzoic acid ester, orthophenylphenol, and diphenyl. Among these, from the viewpoint of safety to the human body, the antifungal agent is preferably a benzoic acid ester. An antifungal agent may be used individually by 1 type, and may use 2 or more types together.

  When using a benzoic acid ester as an antifungal agent, the benzoic acid ester is dissolved in an alcohol having 2 or less carbon atoms (methanol, ethanol) into a paper paint, so that the benzoic acid ester is Easier to dissolve in water in paper paint. When an alcohol having 3 or more carbon atoms (such as propanol or butanol) is used as the solvent for the benzoic acid ester, the benzoic acid ester is difficult to dissolve in the water in the paper paint. Examples of the alcohol having 2 or less carbon atoms include ethanol and methanol. In consideration of safety to the human body, the alcohol is preferably ethanol.

[Dispersant]
When silver-supported zeolite particles are used as the antibacterial agent of the present invention, the paint for paper gels or solidifies in a short time due to the catalytic action of silver ions, so that the paint always flows or the paint is remanufactured frequently. Manufacturing costs are increased. Therefore, the paper coating material of the present invention preferably further contains a dispersant represented by the general formula (1).
(1)
(Wherein R ³ and R ⁶ are the same or different methyl group or ethyl group, R ⁴ and R ⁵ are the same or different linear or branched alkyl group, and m and n are A natural number of 100 or less, which may be the same or different.)

  A complex is formed by the polyethylene glycol structure in the molecule of the dispersant and the silver ions in the silver zeolite. Thereby, in the state disperse | distributed to the liquid, the resin hardening action which silver ion has is weakened. Moreover, the propylene glycol group acts as a hydrophilic group, and the water dispersibility of the silver zeolite itself is improved. Therefore, the lifetime of the paper coating material is prolonged, and the manufacturing cost can be reduced. Further, since it is not necessary to provide a mechanism such as a circulation device for flowing the paint, a conventional printing machine can be used.

  In addition, when the printing process is performed with ink or the like, the paper surface becomes hydrophobic, so that the wettability of the water-based paint to the paper surface is reduced. There is a concern that it is difficult to form a coating film. On the other hand, when only the wettability to the hydrophobic surface is pursued, there is a concern that the dispersibility of the silver zeolite in the aqueous system is lowered, which makes it difficult to form a homogeneous coating film. However, since the dispersant represented by the general formula (1) has a polyethylene glycol structure and an acetylene glycol structure in the molecule, the polyethylene glycol structure improves the compatibility between water and the hydrophobic paper surface. This improves the wettability of water-based paints on the paper surface. Further, the dispersibility of silver zeolite in water is improved by the acetylene glycol structure. Thereby, even if the paper surface is hydrophobic, a uniform and homogeneous coating film can be formed.

  In addition, when m or n in the general formula (1) is too small, the compatibility between water and the hydrophobic paper surface is not sufficiently improved, so that the wettability of the water-based paint to the hydrophobic paper surface is sufficiently increased. There is concern that it cannot be improved. Therefore, m or n is preferably 4 or more. Thereby, the wettability of the water-based paint to the hydrophobic paper surface can be sufficiently improved, and a more uniform coating film can be formed.

[Dispersion medium]
When the amount of low boiling alcohol such as ethanol is changed, the viscosity of the paper paint increases or decreases. Therefore, by appropriately setting the addition amount of ethanol, a paper paint having a desired viscosity is manufactured, and a uniform amount of paint can be easily printed on paper. Moreover, since low boiling point alcohols, such as ethanol, dries in a short time after application, it is possible to suppress paper products from being warped by prolonged drying.

  In addition, if the dispersion medium remains in the paper product to which the paper paint is applied, there is a concern that the characteristics of the packaging target (particularly the taste and aroma of the food) may be impaired. However, low-boiling alcohols such as ethanol have quick-drying properties and are not toxic to the human body, so that they can be suppressed from remaining on paper products and can be improved in safety.

[Viscosity of paper paint]
The viscosity of the paper coating material is not particularly limited, but considering the applicability to the coating machine, the viscosity at 23 ° C. is 2.5 × 10 ⁻³ Pa · s or more and 5.20 × 10 ⁻¹ Pa. · s is preferably ^{(520 × 10 -3 Pa · s} ) or less, 3.0 × ¹⁰ -3 Pa · s or more ^{3.00 × 10 -1 Pa · s (} 300 × 10 -3 Pa · s) The following is more preferable.

[Method for producing paint for paper]
The manufacturing method of the paper coating material which concerns on this invention is not specifically limited, For example, it can manufacture with the following methods. First, liquid paraffin is mixed with water, and a sucrose fatty acid ester is added to the mixed solution and mixed to obtain an emulsion. Mixing is usually performed by stirring with a homogenizer at a rotational speed of about 10,000 to 20,000 rpm or more. Then, the emulsion is mixed with a solution such as a water-soluble resin (which may be conventionally known stirring), and then an antibacterial agent is added to the solution to disperse each component, thereby obtaining a paper paint.

[Use]
The use of the “paper paint” according to the present invention is not particularly limited, but various applications that require water resistance, oil resistance and antibacterial properties, for example, direct or indirect contact with the human body. Can be suitably applied to paper products that are expected to. For example, it can be suitably applied to wrapping paper (particularly food) represented by cardboard and cardboard, construction-related wall materials, flooring materials, and the like.

<Paper products>
The present invention includes a paper product in which a cured film of the above paper paint is formed on the surface of the paper.

The type of paper is not particularly limited, and examples thereof include coated cardboard, Japanese paper, non-woven fabric, and cardboard paper. Among them, the present invention, even for thin paper wrapping paper etc. about basis weight per 1 m ² is 70G～35g, it has a feature in that the paper coating can be suitably coated with a conventional gravure printing machine.

Although the film thickness of the said cured film is not specifically limited, It is preferable that an average film thickness is 0.3 micrometer or more and 1 micrometer or less. As described above, the paper paint of the present invention has an average particle size of the antibacterial agent of 1.5 μm or less, and the viscosity of the liquid paraffin at 23 ° C. is 1.12 × 10 ⁻¹ Pa · s or more. Even if the average film thickness is reduced to 1 μm or less, sufficient water resistance, oil resistance and antibacterial properties can be obtained, and the generation state of bubbles formed on the surface of the cured film of paper paint can be improved.

  In addition, by reducing the average film thickness of the paper coating cured film to 1 μm or less, the unit cost of raw materials per unit area of the paper product can be reduced, and the dispersion medium such as ethanol contained in the paper coating can be dried. You can save time. By improving the drying property, the fusion (blocking) between the paper products can be suppressed, which leads to an improvement in productivity.

  In the present invention, the average film thickness is calculated by the following method. First, using a scanning electron microscope, a cross-sectional enlarged photograph of 5,000 times in a direction perpendicular to the film surface of a cured film of paper paint is taken for a paper product to be measured. This enlarged photograph is assumed to be at least 5 cm ± 1 cm in the vertical direction (thickness direction of the cured film) and 7 cm ± 1 cm in the horizontal direction (width direction of the cured film). Subsequently, the enlarged photograph is divided into 10 equal parts in the vertical direction, and the thickness of the cured film at the central axis is measured for each of the 10 divided rectangles. The average of the 10 obtained values is defined as “average film thickness”.

  The paper product according to the present invention is useful as a material for paper packaging containers and the like. When used as a material for a paper packaging container or the like, the paper product preferably has a fold. Thereby, it is easy to bend | fold a paper product along a crease | fold, and a packaging container can be manufactured easily. The arrangement of the folds may be appropriately selected according to the dimensions of the packaging container to be manufactured. The number of folds is not particularly limited and may be one or more. The folds may be continuous or intermittent.

  Also, the paper product according to the present invention is used as a wrapping paper to be placed on the bottom of a meat poly pack, a laying paper to be placed under a fish sashimi, a wrapping paper for a hamburger or a french fries, other than a paper packaging container can do. The paper product according to the present invention can also be used as a container for cupcakes, lunch box potato salads, and the like.

[Production method for paper products]
The paper product manufacturing method according to the present invention includes an application procedure for applying a paper paint to the paper surface and a curing procedure for curing the paper paint.

[Coating procedure]
The method of applying the paint for paper is not particularly limited as long as the antibacterial effect is imparted to the paper surface. For example, impregnation, transfer using a printing roll or the like, spraying and the like can be mentioned.

By the way, since the average particle diameter of the antibacterial agent contained in the paper paint of the present invention is 1.5 μm or less, the average film thickness of the cured film of the paper paint can be reduced to 1 μm or less as described above. Until now, when paper paint containing liquid paraffin, sucrose fatty acid ester, water-soluble resin and antibacterial agent is applied on the surface of paper, the paper should be such that the average thickness of the cured film of paper paint is 3 μm or more. In order to apply the paper paint to thin paper such as wrapping paper having a basis weight per 1 m ^{2 of} about 200 g to 21 g, a very long drying oven is used to dry the aqueous solvent. It is necessary to provide a dedicated drying oven with a weight of 200 g to 21 g. When the paper weight is 200 g to 21 g, the coating amount of the paper paint is large, so the tension for preventing the paper from breaking when the paint is sucked It was necessary to use a special coating machine, such as with controls. However, in the present invention, since the cured film of the paper paint can be thinned to 1 μm or less, if the dryer is compatible with the water-based paint, the paper paint is applied to the paper paint using a conventional gravure printing machine. Can be applied to thin paper. In addition, by reducing the thickness of the coating film, the stress due to the coating film is reduced, so that coating on thin paper can be easily performed.

[Curing procedure]
The paper coating material may be cured by various conventionally known methods such as hot air drying and active energy ray irradiation. Of these, irradiation with active energy rays (for example, far infrared rays) is preferable in that damage to paper products due to heat can be suppressed.

  Note that characters, patterns, and colors may be printed on the paper surface. Examples of the printed content include information on the contents to be packaged, and specifically include a picture of a packaged food, a product name, a production place, a distributor, and the like. Printing may be performed before coating so that the properties (particularly antibacterial properties) of the coating can be exhibited without coating, but is not limited thereto, and may be performed after curing of the paint. . In any embodiment, printing on paper can be easily performed, unlike printing on foamed polystyrene.

<Paper packaging container>
The present invention includes a paper packaging container formed of the above paper products. Here, the “paper packaging container” may have any shape such as a box shape or a bag shape. It should be noted that disassembling the paper packaging container (for example, returning part or all of the folding) to return it to a paper product, and reusing this paper product to produce a paper packaging container is related to the present invention. Corresponds to the manufacture of paper packaging containers.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

<Example 1>
Add 0.2 kg of sucrose fatty acid ester (product name: F-10, Daiichi Kogyo Seiyaku Co., Ltd.) to 2.27 kg of liquid paraffin (product name: paraffin oil consisting of normal paraffin and isoparaffin, manufactured by Kaneda) The mixture was stirred while heating to 80 ° C. Then, after cooling to room temperature, 10.22 kg of water was added, and after stirring well, 17 kg of an acrylic resin aqueous solution (product name: Aqua Pack Varnish F-2, acrylic resin emulsion, manufactured by T & K Toka) was added well. Stir. Thereafter, 0.4 kg of silver-supported zeolite particles (product name: Novalon, manufactured by Toagosei Co., Ltd.) having an average particle diameter of 0.9 μm are added as an antibacterial agent, and after thoroughly dispersing, 26 kg of water is further added and stirred. Thus, a paper paint according to Example 1 was obtained. In addition, the viscosity in 23 degreeC measured according to JISK5600-2-3 method of liquid paraffin is 1.81 * 10 < ^-1 > Pa * s, and JISK5600- of the paper paint which concerns on Example 1. FIG. The viscosity at 23 ° C. measured according to the 2-3 method was 3.97 × 10 ⁻³ Pa · s.

Using a roll with a flat printing surface as a printing roll of a gravure printing machine, the paper coating material according to Example 1 is attached to the roll surface, and this is applied to the surface of the paper having a basis weight of 23 g per 1 m ² . Transfer was performed so that the average film thickness of the cured film of the paper paint was 1 μm or less. Then, the paper product which concerns on Example 1 was obtained by drying a coated paper in 120 degreeC atmosphere over 10 second.

<Example 2>
Add 0.2 kg of sucrose fatty acid ester (product name: F-10, Daiichi Kogyo Seiyaku Co., Ltd.) to 2.27 kg of liquid paraffin (product name: paraffin oil consisting of normal paraffin and isoparaffin, manufactured by Kaneda) The mixture was stirred while heating to 80 ° C. Then, after cooling to room temperature, 10.22 kg of water was added, and after stirring well, 17 kg of an acrylic resin aqueous solution (product name: Aqua Pack Varnish F-2, acrylic resin emulsion, manufactured by T & K Toka) was added well. Stir. Thereafter, as an antibacterial agent, 0.4 kg of silver-supported zeolite particles (product name: Zeomic, manufactured by Sinanen Zeomic Co., Ltd.) having an average particle diameter of about 1.5 μm are added and dispersed well, and then 26 kg of water is further added. The paper paint according to Example 2 was obtained by stirring. In addition, the viscosity in 23 degreeC measured according to JISK5600-2-3 method of liquid paraffin is 3.05 * 10 < ^-1 > Pa * s, and JISK5600- of the paper paint which concerns on Example 2. FIG. The viscosity at 23 ° C. measured according to the 2-3 method was 3.99 × 10 ⁻³ Pa · s.

Using a roll with a flat printing surface as a printing roll of a gravure printing machine, the paper coating material according to Example 2 is attached to the surface of the roll, and this is applied to the surface of the paper having a basis weight of 23 g per 1 m ² . Transfer was performed so that the average film thickness of the cured film of the paper paint was 1 μm or less. Then, the paper product which concerns on Example 2 was obtained by making a coated paper dry in 120 degreeC atmosphere over 10 second.

<Comparative Example 1>
As an antibacterial agent, silver-supported zeolite particles having an average particle diameter of 2.5 μm (product name: Zeomic, manufactured by Sinanen Zeomic Co., Ltd.) and viscosity at 23 ° C. measured according to JIS K 5600-2-3 method as liquid paraffin Was a paper paint by the same method as in Example 1 except that liquid paraffin of 1.11 × 10 ⁻¹ Pa · s was used. A paper product according to Comparative Example 1 was obtained in the same manner as in Example 1 except that the average film thickness of the cured film of the paper paint was transferred to 7 μm. Moreover, the viscosity in 23 degreeC measured according to JISK5600-2-3 method of the paper coating material which concerns on the comparative example 1 was 3.90 * 10 < ^-3 > Pa * s.

<Comparative Example 2>
As an antibacterial agent, silver-supported zeolite particles having an average particle diameter of 2.5 μm (product name: Zeomic, manufactured by Sinanen Zeomic Co., Ltd.) and viscosity at 23 ° C. measured according to JIS K 5600-2-3 method as liquid paraffin Obtained a paper paint and a paper product according to Comparative Example 2 in the same manner as in Example 1 except that liquid paraffin of 1.11 × 10 ⁻¹ Pa · s was used. The viscosity at 23 ° C. of the paper paint according to Comparative Example 2 measured according to JIS K 5600-2-3 method was 3.92 × 10 ⁻³ Pa · s.

<Comparative Example 3>
As the liquid paraffin, the viscosity at 23 ° C. measured according to the JIS K 5600-2-3 method was the same as that of Example 1 except that liquid paraffin having 1.11 × 10 ⁻¹ Pa · s was used. Thus, a paper paint and a paper product according to Comparative Example 3 were obtained. Moreover, the viscosity in 23 degreeC measured according to JISK5600-2-3 method of the paper coating material which concerns on the comparative example 3 was 3.95 * 10 < ^-3 > Pa * s.

  Table 2 shows the average film thickness of the cured films of the paper paints of Examples 1-2 and Comparative Examples 1-3, the viscosity of liquid paraffin, and the average particle diameter of the antibacterial agent.

<Evaluation>
In order to compare the Examples and Comparative Examples, the surface and cross section of the cured film of the paper paint were observed for the paper products according to the Examples and Comparative Examples. The results are shown in FIGS. 1A is a 500 × magnified photograph of a scanning electron microscope showing the surface state of a cured film of a paper paint in a paper product according to Comparative Example 3, and FIG. 1B is a paper product according to Example 1. FIG. It is a 1,000 times magnified photograph of the scanning electron microscope which shows the surface state of the cured film of the paper coating material in FIG. FIG. 2 is a 300 × magnified photograph of a scanning electron microscope showing the surface state of the cured film of the paper paint in the paper product according to Example 1. FIG. 3 is a 450 × magnified photograph of a scanning electron microscope showing the surface state of the cured film of the paper paint in the paper product according to Comparative Example 1. FIG. 4 is a 300 × magnified photograph of a scanning electron microscope showing the surface state of the cured film of the paper paint in the paper product according to Comparative Example 2. FIG. 5 is a 5,000 times magnified photograph of a scanning electron microscope showing a cross-sectional state of a cured film of paper paint in the paper product according to Example 1. FIG. 6 is a 1500 times magnified photograph of a scanning electron microscope showing the surface state of the cured film of the paper paint in the paper product according to Example 2. The conditions of the scanning electron microscope were that the acceleration voltage was 10 kV for the cross sections of Comparative Example 3 and Example 1, and that the surface of Example 1 and Example 2 and Comparative Examples 1, 2, and 4 were 15 kV. Is the same as that described in the particle size measurement method.

From FIG. 1, it can be seen that the surface of the cured film of the paper paint according to Example 1 is smaller in the size of the bubbles and the number of bubbles is smaller than that of the cured film surface of the paper paint according to Comparative Example 3. confirmed. That is, it was confirmed that the state of generation of bubbles on the surface of the cured film of the paper paint was improved. This is because the viscosity of the liquid paraffin at 23 ° C. is 1.12 × 10 ⁻¹ Pa · s or more, which is larger than that of Comparative Example 3, so that the antibacterial agent in the cured film and the water-soluble resin are well known. As a result, it is surmised that fluid paraffin has been easily removed. Thereby, even if the average film thickness of a cured film is 1 micrometer or less, the generation | occurrence | production state of a bubble can be improved because the viscosity in 23 degreeC of a fluid paraffin is 1.12 * 10 < ^-1 > Pa * s or more. Indicated. Thus, according to the present invention, since the bubble generation state can be improved, the average film thickness of the cured film can be reduced to 1 μm or less, so that the raw material unit price per 1 m ^{2 of} paper products can be suppressed. Can do. In addition, by reducing the film thickness of the paper paint, the drying time when drying the dispersion medium such as ethanol contained in the paper paint can be shortened, and the drying property is further improved. By doing so, it is considered that productivity can be improved because the fusion (blocking) between paper products is suppressed.

  The paper product according to Example 1 was evaluated for antibacterial properties based on JIS Z 2801. Specifically, first, the paper product according to Example 1 was sterilized by moist heat (121 ° C., 15 minutes), and then the Escherichia coli, Staphylococcus aureus, and methicillin resistant yellow shown in Table 3 were formed on one side of the paper (4 cm × 4 cm). Predetermined amounts of staphylococci (MRSA) and Salmonella were inoculated and adhered with a film. Subsequently, after maintaining at 35 ° C. for 24 hours, the number of bacteria on each paper was measured. The measurement was performed on three samples, and the average of each was calculated. In addition, 1/500 normal bouillon (Eiken Chemical Co., Ltd.) was used for the preparation of bacteria.

In addition, untreated paper having a basis weight per 1 m ² of 23 g was prepared as a paper product according to the target example, and antibacterial evaluation was measured in the same procedure as the paper product according to Example 1.

  Table 4 shows the time-dependent change in the number of bacteria for the paper product according to Example 1, and Table 5 shows the time-dependent change in the number of bacteria for the paper product according to the target example.

  As shown in Tables 4 and 5, the paper product according to Example 1 detected all of Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Salmonella after 24 hours, unlike the paper product according to the target example. Was not. Thus, it was confirmed that the paper paint according to the present invention can impart excellent antibacterial properties to paper products even when the average film thickness of the cured film is 1 μm or less.

2 and 3, in Example 1 where the average film thickness of the cured film is 1 μm, the coating film is so thin that the underlying paper fiber is visible, but the average film thickness of the cured film is 7 μm. In Comparative Example 1, since the coating film was thick, it was confirmed that the underlying paper fiber was hardly visible. Moreover, both Example 1 and Comparative Example 1 were confirmed that Example 1 had comparable water resistance, oil resistance, and antibacterial performance, although the average thickness of the cured film was smaller. Further, the antibacterial agent has an average particle size of 0.9 μm, and the liquid paraffin used has a thickness of 231 ° C. and a thickness similar to that of Example 1 in which the viscosity is 1.81 × 10 ⁻¹ Pa · s. However, in Comparative Example 2 in which the average particle diameter of the antibacterial agent is 2.5 μm and the viscosity of the used liquid paraffin at 23 ° C. is 1.11 × 10 ⁻¹ Pa · s, compared with Example 1. Then, it was confirmed that the antibacterial agent was not fixed on the surface of the coating film and large bubbles remained in the film itself (see FIG. 4). On the other hand, in both Comparative Example 2 and Comparative Example 3, the average thickness of the cured film is 1.0 μm or less, and the viscosity of the used liquid paraffin at 23 ° C. is 1.11 × 10 ⁻¹ Pa · s. However, in Comparative Example 3 in which the average particle size of the antibacterial agent is 0.9 μm, the fixability of the antibacterial agent is improved and the size of the bubbles is larger than in Comparative Example 2 in which the average particle size of the antibacterial agent is 2.5 μm. It was confirmed that it became smaller (see FIGS. 4 and 1A). Moreover, it was confirmed from Comparative Examples 1 and 2 whose average particle diameter is 2.5 micrometers that the water resistance and oil resistance of the comparative example 3 whose average particle diameter is 0.9 micrometers are remarkably lowered. Accordingly, the average particle diameter of the antibacterial agent is 1.5 μm or less, and the viscosity of the liquid paraffin at 23 ° C. is 1.12 × 10 ⁻¹ Pa · s or more. It was shown that water resistance, oil resistance, and antibacterial properties are sufficiently exhibited even when the thickness is reduced to 1 μm or less.

Moreover, from the photograph of FIG. 6, the viscosity of the liquid paraffin at 23 ° C. is 3.05 × 10 ⁻¹ Pa · s, and in Example 2 in which the average particle size of the antibacterial agent is 1.5 μm, Although the average film thickness was as small as 1.0 μm or less, it was confirmed that the number of bubbles was small and the antibacterial agent was dispersed. That is, also in Example 2, the generation | occurrence | production condition of the bubble in the cured film surface of paper paint was improved, and it was shown that it has sufficient antibacterial property.

  As described above, FIG. 5 is a cross-sectional view of the cured film of Example 1. In the part where the paper surface is partially depressed, the film thickness is 1.5 μm, but it was confirmed that the film thickness was reduced to 1.0 μm or less as a whole.

In the conventional paper product manufacturing method using a paper paint with a film thickness of 3 μm or more, a special coating machine is used to coat thin paper (wrapping paper with a basis weight of about 70 g to 35 g per 1 m ² ). However, since it is possible to reduce the film thickness, it is considered that even a normal gravure printing machine can be applied if the dryer is compatible with water-based paint. Furthermore, since the stress of the coating film is reduced by reducing the thickness of the coating film, it is considered that coating on thin paper can be easily performed.

Claims (12)

A paper paint applied to the surface of paper,
Contains liquid paraffin, sucrose fatty acid ester, water-soluble resin, and antibacterial agent,
The liquid paraffin has a viscosity at 23 ° C. measured according to the JIS K 5600-2-3 method of 1.12 × 10 ⁻¹ Pa · s or more,
The antibacterial agent is a paper coating material having an average particle size of 0.3 μm or more and 1.5 μm or less measured according to JIS H7804 method using a scanning electron microscope.   The paper paint according to claim 1, wherein the antibacterial agent is a silver antibacterial agent.   The paper paint according to claim 1 or 2, wherein the content of the antibacterial agent is 0.5% by mass or more and 1.5% by mass or less with respect to the total mass of the paper paint.   The paper paint according to any one of claims 1 to 3, wherein the sucrose fatty acid ester has an HLB value of 2 or less.   The paper coating material according to any one of claims 1 to 4, wherein a content of the sucrose fatty acid ester is 0.35 mass% or more and 0.8 mass% or less with respect to a total mass of the paper coating material.   The water-soluble resin contains at least one selected from the group consisting of (meth) acrylic resins, styrene-butadiene copolymer resins, acrylonitrile-butadiene-styrene copolymer resins, and acrylonitrile-styrene copolymer resins. The paper paint according to any one of claims 1 to 5.   A paper product in which the cured film of the paper paint according to any one of claims 1 to 6 is formed on the surface of the paper.   The paper product according to claim 7, wherein the average film thickness of the cured film measured according to JIS H8690 Annex 1 "Thickness Test Method by Scanning Electron Microscope" is 0.3 µm or more and 1 µm or less.   A paper packaging container formed of the paper product according to claim 7 or 8. An application procedure for applying the paper paint according to claim 1 to the paper surface;
And a curing procedure for curing the paper paint.   The application is performed so that the average film thickness of the cured film of the paper paint measured according to JIS H8690 Annex 1 “Thickness Test Method by Scanning Electron Microscope” is 0.3 μm or more and 1 μm or less. Item 11. A method for producing a paper product according to Item 10. The said application | coating procedure is a manufacturing method of the paper product of Claim 11 which is a procedure which apply | coats the said coating material for paper with the gravure printing machine to the paper surface whose mass per 1 m < ² > is 200 g or less.