JP2024003813A - Packing material and packing bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packing material which is excellent in a total visible light transmittance, oxygen barrier property, water frictionality, antiblocking property, and heat sealability.

SOLUTION: A packing material sequentially has a heat seal layer, a paper base material (A), and a surface protective layer. The paper base material (A) includes a resin with an average fiber diameter or an average particle diameter below 10 μm. The surface protective layer includes a cellulose resin (a') with the average fiber diameter or the average particle diameter below 10 μm. The total visible light transmittance of the packing material measured by JIS K 7361-1 is equal to or more than 40%.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to packaging materials and packaging bags.

In recent years, it has become common for product packages and other packaging to be printed for decoration or surface protection. Furthermore, the quality of printing, such as the design, beauty, and luxury of printed matter, promotes consumers' desire to purchase the printed matter, and has great industrial value.

Generally, plastic films are mainly used to construct packages, and because they are transparent, the contents can be seen, and in particular, laminate packaging materials are often used. For example, Patent Document 1 describes an invention in which a laminate packaging material is composed of a base material, a printed layer, an adhesive layer, and a sealant layer, and a biomass resin is used in the printed layer and the adhesive layer. However, in the first place, laminated packaging materials use a large amount of petroleum-derived plastic film. Therefore, there is a need for a paper packaging material that is environmentally friendly, carbon neutral, and can further reduce the amount of plastic used, and technological development is underway.

Packaging materials using a paper base material are easily permeable to substances such as oxygen because the paper base material has voids. Furthermore, because the difference in refractive index between cellulose fibers and air is large, the contents cannot be visually recognized (total light transmittance is low), so its usage has been limited. In addition, packaging materials using paper base materials generally have a problem with water resistance, which has also been a factor limiting their uses.

For example, Patent Document 2 describes an invention related to a packaging material having a surface protective layer, a printed layer, a paper base material, and a resin layer in this order. However, since the above-mentioned paper-based packaging material uses a normal paper base material, the packaging material with the above-mentioned structure has poor visibility of contents (total light transmittance), water resistance, and oxygen barrier properties. There was an issue.

Japanese Patent Application Publication No. 2018-051796 Japanese Patent Application Publication No. 2020-55167

A packaging material using a paper base material that is satisfactory as a packaging material with excellent total light transmittance, water resistance, oxygen barrier properties, etc. has not yet been found. Furthermore, in order to provide practicality to packaging materials using paper base materials, in addition to solving the above problems, it is necessary to satisfy the requirements of water friction resistance, blocking resistance, and heat sealability for packaging materials.
As a result of extensive research into the above-mentioned problems, the present inventors have discovered that the above-mentioned problems can be solved by using the packaging material described below, and have accomplished the present invention.

That is, the present invention is a packaging material having a heat seal layer, a paper base material (A), and a surface protection layer in this order,
The paper base material (A) contains a resin (a) having an average fiber diameter or average particle diameter of less than 10 μm,
The surface protective layer contains a cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm,
The present invention relates to a packaging material whose total light transmittance measured according to JIS K 7361-1 is 40% or more.

Further, the present invention relates to the above-mentioned packaging material, wherein the heat-sealing layer contains at least one selected from the group consisting of acrylic resin and ethylene-vinyl acetate copolymer resin.

Further, the present invention relates to the above-mentioned packaging material, wherein the heat-sealing layer contains an acrylic resin, and the acrylic resin has a glass transition temperature of 10 to 90°C.

The present invention also relates to the above packaging material, wherein the heat-sealing layer contains an ethylene-vinyl acetate copolymer resin, and the minimum film forming temperature of the ethylene-vinyl acetate copolymer resin is 60 to 100°C.

The present invention also relates to the above packaging material, wherein the paper base material (A) contains a cellulose resin (a1) having an average fiber diameter or average particle diameter of less than 10 μm.

Further, the present invention provides a packaging material in which the total content of the cellulose resin (a1) having an average fiber diameter or average particle diameter of less than 10 μm and the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm is Regarding the above-mentioned packaging material, the amount is 0.5 to 50% by mass.

The present invention also relates to the above packaging material, wherein the cellulose resin (a1) having an average fiber diameter or average particle diameter of less than 10 μm is derived from viscose.

The present invention also relates to the above-mentioned packaging material, wherein the surface protective layer further contains a polyamide resin.

Further, the present invention relates to the above-mentioned packaging material, wherein the mass ratio of cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm and polyamide resin is 99:1 to 15:85.

The present invention also relates to the above-mentioned packaging material, wherein the surface protective layer further contains amide wax.

The present invention also relates to the above packaging material, wherein the surface protective layer further contains a plasticizer.

The present invention also relates to a packaging bag formed from the above packaging material.

The present invention has made it possible to provide a packaging material with excellent total light transmittance, oxygen barrier properties, water friction resistance, blocking resistance, and heat sealability.

The embodiments of the present invention will be described in detail below, but the explanation of the constituent elements described below is an example of the embodiment of the present invention, and the present invention is not limited to these contents unless it exceeds the gist thereof. .

In the following description, "part" means "part by mass" and "%" means "% by mass" unless otherwise specified. In addition, the packaging material may be simply abbreviated as a "laminate", but it has the same meaning.
Moreover, "printing ink" refers to ink containing pigments and other colorants for forming a printing layer. The term "overcoat agent" refers to a coating agent that does not contain pigments or other colorants to form a surface protective layer, but does not exclude unintentionally mixed traces of colorant.

[Packaging material]
A packaging material having a heat-sealing layer, a paper base material (A), and a surface protection layer in this order, wherein the paper base material (A) contains a resin (a) having an average fiber diameter or average particle diameter of less than 10 μm, The surface protective layer contains a cellulose resin (a') with an average fiber diameter or average particle diameter of less than 10 μm, and the total light transmittance of the packaging material measured according to JIS K 7361-1 is 40% or more. Regarding packaging materials.

<Total light transmittance of packaging material>
The total light transmittance of the packaging material of the present invention is determined in accordance with JIS K 7361-1. Measurement can be performed by inputting light from the protective layer side. The total light transmittance of the packaging material is preferably 40% or more, more preferably 60% or more, and particularly preferably 70 to 90%. When the content is within the above range, the visibility of the contents will be good when used as a package as described below.
In this configuration, it is preferable to use a paper base material (A) in which paper fibers are filled with resin, and since light refraction is reduced, the total light transmittance is excellent, and oxygen permeability is also reduced, so the oxygen barrier Excellent in sex. Furthermore, by including cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm in the surface protective layer, excellent water friction resistance can be achieved while maintaining total light transmittance.

[Heat seal layer]
The heat-sealing layer in the present invention is located on the surface of the paper base material (A) opposite to the surface provided with the surface protective layer. The thickness of the heat seal layer is preferably 1 to 20 μm, more preferably 3 to 10 μm. When it is in the above range, blocking resistance becomes good.

Examples of the resin contained in the heat-sealing layer include acrylic resin, ethylene-vinyl acetate copolymer resin, urethane resin, polyethylene resin, polypropylene resin, etc. From the viewpoint of heat-sealability and barrier properties, acrylic resin and/or ethylene-acetic acid Vinyl copolymer resins are preferred. These may be used alone or in combination of two or more. The content of the resin in the heat-sealing layer is preferably 80 to 100% by mass, more preferably 90 to 100% by mass based on 100% by mass of the heat-sealing layer. When it is within the above range, heat sealability becomes good.

<Acrylic resin>
Acrylic resin is a resin containing structural units derived from acrylic monomers. The acrylic resin preferably has a carboxyl group or other acidic group, and in this case, the acid value is preferably 20 to 100 mgKOH/g, more preferably 30 to 80 mgKOH/g. The glass transition temperature of the acrylic resin is preferably 10 to 90°C, more preferably 25 to 70°C. When the acid value and glass transition temperature of the acrylic resin are within the above ranges, the heat sealability will be good. Suitable examples of the acrylic resin include homopolymers of acrylic monomers, copolymers of acrylic monomers and acidic monomers, and copolymers of ethylene and acrylic monomers.

Examples of the monomer having an unsaturated double bond containing the (meth)acrylic monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n- Alkyl ester compounds of (meth)acrylic acid such as hexyl (meth)acrylate, n-octyl (meth)acrylate, decyl (meth)acrylate, and lauryl (meth)acrylate;
(meth)acrylic acid amide derivatives containing at least one N-substituted methylol group, such as N-methylol (meth)acrylamide;
Dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dipropylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, dipropylaminopropyl (meth)acrylate, etc. aminoalkyl ester of meth)acrylic acid,
(meth)acrylic acid mono- or diesters of glycols such as diethylene glycol and dipropylene glycol;
Styrene derivatives such as styrene and α-methylstyrene,
Hydroxyalkyl ester compounds of (meth)acrylic acid such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate,
acrylic acid, methacrylic acid,
Examples include vinyl compounds having acid groups such as maleic acid and itaconic acid.
From the viewpoint of heat sealability, the acrylic resin preferably has a carboxyl group and/or a hydroxyl group, and when the acrylic resin has a hydroxyl group, it contains a hydroxyalkyl ester compound of (meth)acrylic acid as a monomer constituting the acrylic resin. Preferably.

As the acrylic resin, commercially available products may be used, such as JONCRYL PDX7356, PDX-7326, PDX-7430 manufactured by BASF, and PE-1126, JE-1113, and KE1148 manufactured by Seiko PMC.

<Ethylene-vinyl acetate copolymer resin>
Ethylene-vinyl acetate copolymer resin is a copolymer consisting of ethylene and vinyl acetate. The vinyl acetate content in the ethylene-vinyl acetate copolymer resin is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, based on 100% by mass of the ethylene-vinyl acetate copolymer resin. Particularly preferably 20 to 30% by mass. The minimum film forming temperature of the ethylene-vinyl acetate copolymer resin is preferably 40 to 120°C, more preferably 60 to 100°C. When the vinyl acetate content and the minimum film forming temperature are within the above ranges, the heat sealability will be good.

Examples of the above ethylene-vinyl acetate copolymer resin include Aquatex EC series manufactured by Japan Coating Resin Co., Ltd., Sumikaflex S-201HQ, S-305, S-305HQ, S-400HQ, S-401HQ, and S- manufactured by Sumitomo Chemical Co., Ltd. 408HQE, S-450HQ, S-455HQ, S-456HQ, S-460HQ, S-467HQ, S-470HQ, S-480HQ, S-510HQ, S-520HQ, S-752, S-755 can be used. can.

(Measurement of acid value)
In this application, the acid value is the number of mg of potassium hydroxide required to neutralize the acidic groups contained in 1 g of resin solid content, and is measured in accordance with JIS K0070.

(Measurement of glass transition temperature)
In the present application, the glass transition temperature was measured by simultaneous thermogravimetric and differential thermal measurement (TG-DTA) using DTG-60A manufactured by Shimadzu Corporation. Specifically, the glass transition temperature was defined as the temperature at the inflection point in the baseline shift under conditions of a nitrogen atmosphere, a measurement temperature range of -100 to 200°C, and a temperature increase rate of 1°C/min.

(Measurement of weight average molecular weight)
In the present application, the weight average molecular weight (Mw) can be measured, for example, by GPC (gel permeation chromatography), and can be determined as a converted molecular weight using polyethylene glycol as a standard substance. Examples of the measuring device include a GPC device such as Shodex GPC-401 manufactured by Showa Denko, and examples of the column include Shodex OHpak LB-805 manufactured by Showa Denko. Examples of the detector include RI (differential refractometer), and the measurement temperature is preferably a column temperature of 20 to 50°C. As the eluent, a 0.1N NaNO ₃ aqueous solution may be used, and the flow rate is 0.2 to 5.0 mL/min.

(Measurement of minimum film forming temperature)
In the present application, the minimum film forming temperature is based on JIS K 6828-1:2003 and can be measured using a TP-801MFT tester manufactured by Tester Sangyo Co., Ltd. or the like.

<Formation of heat seal layer>
The heat-sealing layer is applied, for example, on the side of the paper base (A) opposite to the surface protection layer, so that the final packaging material has a heat-seal layer, a paper base (A), and a surface protection layer in this order. It can be formed by printing with a heat sealant and then drying and removing volatile components. As a printing method, a gravure printing method or a flexographic printing method is suitable. For example, the material is diluted with a diluting solvent to a viscosity and concentration suitable for gravure printing, and then supplied alone or in a mixture to each printing unit and applied. . Thereafter, a heat-sealing layer can be obtained by fixing the film by drying in an oven or the like.

(Gravure printing)
《Gravure version》
In gravure printing, the gravure plate is a cylindrical metal plate, and concave portions of each color are formed by engraving, etching, or laser. There are no restrictions on the use of engraving and lasers, and settings can be made to suit the pattern. A line number of 80 to 250 lines is appropriately used, and the larger the number of lines, the finer the print. The thickness of the printed layer is preferably 0.1 μm to 100 μm.

《Gravure printing machine》
In a gravure printing machine, one printing unit includes the above-mentioned gravure plate and a doctor blade. There are a large number of printing units, and printing units corresponding to organic solvent-based printing inks and pattern inks can be set up, and each unit has an oven drying unit. Printing is done using a rotary press and is a roll printing method. The type of plate and the type of doctor blade can be selected as appropriate, and one can be selected according to the specifications.

[Paper base material (A)]
The paper base material (A) of the present invention is a base material composed of paper fibers (cellulose fibers, which are plant-derived fibers with an average fiber diameter of 10 μm or more), but it is also a base material composed of paper fibers with an average fiber diameter or average particle diameter. It is preferred to contain less than 10 μm of resin (a), giving the packaging material a higher total light transmittance transparency. Note that the resin (a) having an average fiber diameter or average particle diameter of less than 10 μm is a fiber, particle, or colloid having an average fiber diameter or average particle diameter of less than 10 μm, or a resin that can be dissolved and dispersed in an organic solvent and/or water. The average fiber diameter or average particle diameter is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less.
The above average fiber diameter or average particle diameter can be calculated by taking the average of about 10 to 20 points at random using a scanning electron microscope (SEM) or the like.
In addition, if the resin is dissolved, it cannot be measured with a scanning electron microscope (SEM), but if there is a resin whose molecular weight can be measured by GPC etc., it is obvious that the resin is fibrous or particulate. This corresponds to resins with an average fiber diameter or average particle diameter of less than 10 μm. Furthermore, even if the dissolved resin dries up due to solvent volatilization, neither the average fiber diameter nor the average particle diameter can be measured with a scanning electron microscope (SEM), but the average fiber diameter or average particle diameter is less than 10 μm. Since it is derived from a solution of a resin, it corresponds to a resin with an average fiber diameter or average particle diameter of less than 10 μm. The purpose of this definition is to literally distinguish that the resin is different from paper fibers.
In an embodiment in which the paper base material contains a resin having an average fiber diameter or average particle diameter of less than 10 μm, it is preferable that the paper base material (A) contains the resin in the voids between the cellulose fibers of the paper base material.

<Ratio of paper base material (A) in packaging material>
Among the above packaging materials, the proportion of the paper base material (A) is preferably 50% by mass or more, and 60% by mass or more in 100% by mass of the packaging material from the viewpoints of recyclability, transparency, and barrier properties. It is more preferable that the amount is 70% by mass or more, and even more preferably 70% by mass or more.

<Paper fiber used for manufacturing paper base material (A)>
The paper fibers (hereinafter also simply referred to as "paper") used for the paper base material (A) are not particularly limited as long as they are made of plant-derived fibers (cellulose fibers) with an average fiber diameter of 10 μm or more. For example, Examples include kraft paper. The paper base material (A) preferably has a basis weight of 50 to 150 g/m ² , more preferably 60 to 120 g/m ² , and more preferably 60 to 90 g/m ² . More preferred. When it is within the above range, the total light transmittance becomes good.

<Resin (a) with an average fiber diameter or average particle diameter of less than 10 μm contained in the paper base material (A)>
The resin contained in the paper base material (A) is a resin in the form of fibers, particles, colloids, or solutions with an average fiber diameter or average particle diameter of less than 10 μm, and is a resin that can be dissolved and dispersed in organic solvents and/or water. be. Examples of the resin include cellulose resin (a1), paraffin resin, acrylic resin, rosin resin, and epoxy resin, and cellulose resin (a1) is preferable from the viewpoint of refractive index. These may be used alone or in combination of two or more. However, this does not exclude the inclusion of resin fibers and resin particles having an average fiber diameter or average particle diameter of 10 μm or more other than paper fibers.

The content of the resin (a) in the paper base material (A) is preferably 0.5 to 50 mass%, and preferably 10 to 40 mass%, based on 100 mass% of the paper base material (A). The content is more preferably 20 to 35% by mass. When it is within the above range, the total light transmittance and blocking resistance will be good.

<Cellulose resin (a1) with an average fiber diameter or average particle diameter of less than 10 μm>
Cellulose resins (a1) with an average fiber diameter or average particle diameter of less than 10 μm include cellulose acetate resin, cellulose acetate butyrate resin, cellulose acetate propionate resin, nitrocellulose resin, cellulose derived from sodium xanthate (derived from viscose). Examples include cellulose resin and other cellulose resins. More preferably, it is a cellulose resin derived from cellulose sodium xanthate (viscose).
The weight average molecular weight of the cellulose resin (a1) used in the present invention is preferably 20,000 to 900,000, more preferably 50,000 to 700,000, 100,000 to 500, More preferably, it is 000. Moreover, when the average particle diameter of the cellulose resin (a1) is within the above range, it becomes possible to achieve both light transmittance and oxygen permeability, and thus the total light transmittance and oxygen barrier properties become good.

As the cellulose resin (a1), from the viewpoint of dispersibility and transparency, it is preferable to use cellulose nanofibers or viscose (regenerated cellulose), and it is more preferable to use cellophane made of viscose.

Cellulose nanofibers can be obtained by treating cellulose resin (a1) with a known method such as crushing using a crusher or TEMPO oxidation method. The fiber width (fiber diameter) of the cellulose nanofibers is preferably 1 to 200 nm, more preferably 1 to 50 nm, and particularly preferably 1 to 20 nm.

In one embodiment, it is preferable to use cellulose sodium xanthate (viscose) obtained by reacting cellulose fibers with sodium hydroxide and carbon disulfide as the resin (a). By immersing the viscose in dilute sulfuric acid, cellulose (also referred to as regenerated cellulose or cellophane) can be obtained again. Since the viscose is a colloidal dispersion, it has excellent coating properties. Therefore, when paper contains regenerated cellulose as the resin (a), it is preferable to coat the paper with viscose and convert it into regenerated cellulose after coating. Alternatively, it is preferable to slurry viscose together with paper fibers and obtain the paper base material (A) as regenerated cellulose after coating and drying.

<Percentage of paper fiber in packaging material>
From the viewpoint of recyclability, the proportion of paper fibers in the above packaging material is preferably 50% by mass or more, more preferably 60% by mass or more, and 70% by mass or more based on 100% by mass of the packaging material. It is more preferable that

<Method for manufacturing paper base material (A)>
Methods for impregnating paper with resin include, for example, using a resin liquid containing resin (a) and applying the resin liquid to paper to produce the paper base material (A), and applying paper to the resin liquid. Examples include a method of manufacturing the paper base material (A) by dipping, and a method of manufacturing the paper base material (A) by making paper by sticking a mixture of plant fibers and the above-mentioned resin. Examples of the resin liquid include a resin solution in which the resin is dissolved in a medium, a resin dispersion in which fine resin particles are dispersed in a medium, and the like.

《Method for producing paper base material (A) by applying resin liquid to paper》
Examples of the method for applying the resin liquid to paper include a method in which the resin liquid is applied onto the paper surface and then volatile components are removed. As a coating method, gravure printing method and flexographic printing method are suitable. For example, the diluent is diluted with a diluting solvent to a viscosity and concentration suitable for flexographic printing, and it is supplied to each printing unit alone or in a mixture, and the coating is applied. be done. Thereafter, paper containing resin can be obtained by drying in an oven or the like.

<<Method of producing paper base material (A) by immersing paper in resin liquid>>
A method of immersing paper in a resin liquid is, for example, by immersing the paper in the resin liquid, squeezing out the excess resin liquid with a nip roll, etc., and then removing the volatile components by drying with an oven etc. You can get paper.

<<Method of manufacturing paper base material (A) by adhering a mixture of plant fibers and the above resin to paper>>
For example, a method may be used in which a slurry mixture of cellulose fibers, which are paper fibers, and resin (a) is coated and dried to obtain a sheet, and the resin is solidified by acid/alkali treatment to make transparent paper. .

In the following description, a heat seal layer, a paper base material (A), and a surface protective layer are sequentially provided, and oxygen and oxygen barrier properties are improved by making the surface protective layer and the heat seal layer have the following aspects, and This has the effect of making it possible to obtain a transparent packaging material.

[Surface protective layer]
In the present application, the surface protective layer contains a cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm. Note that the cellulose resin (a') with an average fiber diameter or average particle diameter of less than 10 μm is a resin in the form of fibers, particles, colloids, or solutions with an average fiber diameter or average particle diameter of less than 10 μm, and is It is a resin that can be dissolved and dispersed in water. The surface protective layer can be formed with an overcoat agent containing a cellulose resin (a') having an average fiber diameter or an average particle diameter of less than 10 μm, and can be formed by a known printing method such as a gravure printing method or a flexographic printing method. The printing method can be appropriately selected from among the methods, and the gravure printing method is preferable. The viscosity of the overcoat agent is preferably 20 to 200 mPa·s from the viewpoint of printability and the like.
The thickness of the surface protective layer is preferably 0.3 to 10 μm, more preferably 1 to 7 μm. When the thickness of the surface protective layer is 0.3 μm or more, the uniformity of the surface protective layer improves, resulting in good blocking resistance, and when the thickness is 10 μm or less, the amount of residual solvent in the surface protective layer decreases. Therefore, blocking resistance is improved.

<Cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm>
The cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm is a resin obtained by esterification or nitration of cellulose resin derived from non-edible plants such as wood fibers or cotton, such as acetic acid. Examples include cellulose resin, cellulose acetate butyrate resin, cellulose acetate resin, cellulose acetate butyrate resin, cellulose acetate propionate resin, and nitrocellulose resin, with nitrocellulose resin being preferred from the viewpoint of water friction resistance. These may be used alone or in combination of two or more. However, resin fibers and resin particles having an average fiber diameter or average particle diameter of 10 μm or more other than paper fibers are not excluded.
In addition, the cellulose resin (a') with an average fiber diameter or average particle diameter of less than 10 μm is the same as the cellulose resin (a1) with an average fiber diameter or average particle diameter of less than 10 μm contained in the paper base material (A). There may be one or they may be different.

The cellulose resin (a') with an average fiber diameter or average particle diameter of less than 10 μm has a viscosity measured in accordance with JIS K 6703-1995 that satisfies at least one of the following (1) to (3). It is preferable. The above viscosity is the time it takes for a steel ball to fall through an isopropanol solution of cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm (steel ball falling time (seconds)).
(1) The viscosity at a solution concentration of 12.2% is 1.5 to 16 seconds.
(2) The viscosity at a solution concentration of 20% is 3 to 40 seconds.
(3) The viscosity at a solution concentration of 25% is 0.1 to 22 seconds.
Among these, it is preferable that the viscosity of the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm satisfies (3) above. In (3) above, the viscosity at a solution concentration of 25% is preferably 0.5 to 15 seconds, more preferably 0.5 to 9 seconds. When the viscosity is within the above range, the surface protective layer has good water friction resistance and blocking resistance.

The weight average molecular weight (Mw) of the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm is preferably 5,000 to 200,000, more preferably 8,000 to 100,000, and more preferably Preferably it is 10,000 to 80,000. When it is within the above range, water friction resistance and blocking resistance will be good.
Further, the glass transition temperature of the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm is preferably 80°C to 160°C. When it is within the above range, water friction resistance and blocking resistance will be good.

When the cellulose resin (a') with an average fiber diameter or average particle diameter of less than 10 μm is a nitrocellulose resin, the nitrogen content of the nitrocellulose resin should be 10 to 13% by mass in the total solid content of the nitrocellulose resin. is preferable, and more preferably 10.7 to 12.2% by mass. When it is within the above range, water friction resistance and blocking resistance will be good.

The weight average molecular weight of the nitrocellulose resin is preferably 3,000 to 40,000, more preferably 4,000 to 25,000, and more preferably 5,000 to 15,000. When it is within the above range, water friction resistance and blocking resistance will be good.
Examples of commercially available nitrocellulose resins include those manufactured by NOBEL (DHX3-5, DHX5-10, DHX8-13).

From the viewpoint of blocking resistance, the surface protective layer may further contain a polyamide resin, a plasticizer, and/or an amide wax in addition to the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm. preferable.

<Content of cellulose resin (a1) with an average fiber diameter or average particle diameter of less than 10 μm and cellulose resin (a') with an average fiber diameter or average particle diameter of less than 10 μm in the packaging material>
Total content of cellulose resin (a1) with an average fiber diameter or average particle diameter of less than 10 μm, and cellulose resin (a') with an average fiber diameter or average particle diameter of less than 10 μm The amount is preferably 0.5 to 50% by weight, more preferably 10 to 40% by weight, and even more preferably 15 to 35% by weight based on 100% by weight of the packaging material. When it is within the above range, the total light transmittance and blocking resistance will be good.

<Polyamide resin>
As mentioned above, from the viewpoint of improving blocking resistance, the surface protective layer of the present invention may further contain a polyamide resin in addition to the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm. is preferred.
Although the polyamide resin is not particularly limited, it is preferably a thermoplastic polyamide soluble in an organic solvent, and a polycondensate of a polybasic acid and a polyvalent amine is preferably used.
Among these, polyamide resins containing a reaction product of an acid component containing a polymerized fatty acid and/or a dimer acid and an aliphatic and/or aromatic polyamine are preferred, and those containing a portion of primary and secondary monoamines are more preferred.

Examples of polybasic acids used as raw materials for polyamide resin include adipic acid, sebacic acid, azelaic acid, phthalic anhydride, isophthalic acid, suberic acid, glutaric acid, fumaric acid, pimelic acid, oxalic acid, malonic acid, Examples include succinic acid, maleic acid, terephthalic acid, 1,4-cyclohexyldicarboxylic acid, trimellitic acid, dimer acid, hydrogenated dimer acid, and polymerized fatty acids. Among them, dimer acids and polymerized fatty acids are preferably used.
It is preferable that the polyamide resin has a structure derived from a polymerized fatty acid, and it is preferable that the polyamide resin contains 50% by mass or more of a structure derived from a dimer acid and a polymerized fatty acid.
Here, the polymerized fatty acid is obtained by a cyclization reaction of unsaturated fatty acids, and includes monobasic fatty acids, dimerized fatty acids, trimerized fatty acids, and the like. When using polymerized fatty acids, monobasic fatty acids containing unsaturated fatty acids or those obtained by ester polymerization thereof are preferable, and those obtained by polymerization of unsaturated fatty acids having 16 to 22 carbon atoms or their esters are preferable. . One type of polymerized fatty acid may be used alone, or two or more types may be used in combination in any ratio.
The fatty acids constituting the dimer acid or polymerized fatty acid are preferably derived from natural oils such as soybean oil, palm oil, and rice bran oil, and more preferably oleic acid and linoleic acid.
In addition, a monocarboxylic acid can also be used in combination with the basic acid. Examples of monocarboxylic acids used in combination include acetic acid, propionic acid, lauric acid, palmitic acid, benzoic acid, and cyclohexanecarboxylic acid.

Examples of other amines include polyamines and primary or secondary monoamines.
The above polyamines include aliphatic diamines such as ethylene diamine, propylene diamine, hexamethylene diamine, and methylaminopropylamine; aliphatic polyamines such as diethylene triamine and triethylene tetramine; alicyclic polyamines such as cyclohexylene diamine and isophorone diamine; Examples include aromatic aliphatic polyamines such as amines; aromatic polyamines such as phenylene diamine and diaminodiphenylmethane.
Examples of primary and secondary monoamines include n-butylamine, octylamine, diethylamine, monoethanolamine, monopropanolamine, diethanolamine, dipropanolamine, and the like.
The polyamide resin preferably has a hydroxyl group in the molecule from the viewpoints of adhesiveness, blocking resistance, oil resistance, and heat resistance, and it is preferable to use an alkanolamine as the primary or secondary monoamine component.

As commercially available polyamide resins, for example, Vegechem Green series (manufactured by Tsukino Shokuhin Kogyo Co., Ltd.), Newmide series (manufactured by Harima Kasei Co., Ltd.), etc. can be used.

The polyamide resin preferably has a softening point of 80 to 140°C, more preferably 90 to 120°C. When the softening point is 80° C. or higher, the surface tack of the surface protective layer can be easily cut off, and blocking can be suppressed. When the softening point is 140° C. or lower, the surface protective layer becomes flexible and the adhesion between the surface protective layer and the printed layer is improved.
The weight average molecular weight of the polyamide resin is preferably in the range of 2,000 to 70,000, more preferably 5,000 to 30,000, from the viewpoint of solubility of the polyamide resin. When the weight average molecular weight is 2,000 or more, blocking resistance is improved. When the weight average molecular weight is 50,000 or less, the viscosity of the overcoat agent can be lowered and storage stability becomes good.
Note that the softening point can be measured in accordance with JIS K 2207 (ring and ball method).

In the surface protective layer, the mass ratio of the cellulose resin (a') with an average fiber diameter or average particle diameter of less than 10 μm and the polyamide resin is preferably 99:1 to 15:85, more preferably 50:50 to 15: 85, more preferably 30:70 to 15:85. Within the above range, blocking resistance and water friction resistance are excellent.

<Other resins>
The surface protective layer may contain other resins other than cellulose resin (a') and polyamide resin having an average fiber diameter or average particle diameter of less than 10 μm, as long as the effects of the present invention are not impaired. Examples of other resins include polylactic acid resin, urethane resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, rosin resin, vinyl acetate resin, and ethylene-vinyl acetate copolymer resin. Combined resin, vinyl acetate resin, acrylic resin, urethane-acrylic resin, styrene resin, styrene-acrylic acid resin, styrene-allyl alcohol resin, styrene-maleic acid resin, maleic anhydride resin, maleic acid resin, rosin-modified maleic acid resin , cycloolefin resin, dammar resin, polyester resin, alkyd resin, terpene resin, phenol-modified terpene resin, ketone resin, cyclized rubber, chlorinated rubber, butyral, polyacetal resin, silicone resin, and modified resins thereof.

<Additives>
The surface protective layer can contain any additives such as a plasticizer, amide wax, hydrocarbon wax, and chelate crosslinking agent, and may contain a plasticizer and/or amide wax from the viewpoint of blocking resistance. preferable.

《Plasticizer》
As mentioned above, the surface protective layer of the present invention preferably further contains a plasticizer in addition to the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm from the viewpoint of anti-blocking property. .
As the plasticizer, in addition to cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm, it is preferable to use one that has excellent compatibility with other resin components contained in the surface protective layer and has low volatility. For example, it is preferable to contain at least one selected from citric acid esters, phthalic acid esters, phosphoric acid esters, trimetic acid esters, aliphatic dibasic acid esters, glycol ethers, sulfonic acid amide systems, and castor oil.

Examples of citric acid esters include acetyl trialkyl citrates such as triethyl citrate, acetyl triethyl citrate, tri-n-butyl citrate, acetyl tri-n-butyl citrate, and 2-ethylhexyl acetyl citrate. The alkyl group preferably has 2 to 12 carbon atoms. Among these, acetyl tri-n-butyl citrate, acetyl triethyl citrate, and the like are more preferred.
Examples of phthalate esters include dialkyl phthalates such as bis(2-ethylhexyl) phthalate, diisononyl phthalate, diisodecyl phthalate, and diundecyl phthalate, and the alkyl group preferably has 2 to 12 carbon atoms. preferable. Among these, diisononyl phthalate, diisodecyl phthalate, and the like are more preferred.
As the phosphoric acid ester, phosphoric acid esters such as tricresyl phosphate, triphenyl phosphate, and tributyl phosphate are preferably mentioned, and tributyl phosphate is preferable.
Examples of the trimetate esters include trialkyl trimellitates such as tri-2-ethylhexyl trimetate, trioctyl trimetate, and triisononyl trimetate. The alkyl group preferably has 2 to 12 carbon atoms. Among these, tri-2-ethylhexyl trimetate and the like are more preferred.
The aliphatic dibasic acid ester is preferably a fatty acid dialkyl ester, and the alkyl group preferably has 2 to 12 carbon atoms. Examples of fatty acid dialkyl esters include adipic acid ester and sebacic acid ester, among which bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis(2-ethylhexyl) sebacate, diisononyl sebacate, and sebacin. More preferred is diisodecyl acid.
Preferred examples of the sulfonic acid amide include N-butylbenzenesulfonic acid amide and N-ethyltoluenesulfonic acid amide.
Further, examples of the glycol ether include diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, and the like.

The surface protective layer in the present invention preferably contains at least one plasticizer selected from the group consisting of castor oil, glycol ether, aliphatic dibasic acid ester, and citric acid ester, and glycol ether is more preferred.
The content of the plasticizer in the surface protective layer is preferably 0.1 to 15% by weight, more preferably 3 to 12% by weight, and particularly preferably 5 to 9% by weight. When it is within the above range, blocking resistance is improved.

《Amide Wax》
As mentioned above, from the viewpoint of blocking resistance, the surface protective layer of the present invention preferably further contains amide wax in addition to the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm. .
The amide wax is a fatty acid amide, and preferably has a fatty acid residue and an amide group. It is thought that the fatty acid amide is oriented on the surface of the surface protective layer after printing, develops slipperiness, and improves blocking resistance. Note that this explanation is based on technical considerations and does not limit the invention in any way.

Preferred fatty acid amides include, for example, monoamides, substituted amides, bisamides, methylolamides, and esteramides, and preferably at least one selected from the group consisting of monoamides, substituted amides, and bisamides.

The melting point of the fatty acid amide is preferably 50°C to 150°C.
Monoamides with a melting point of 50°C to 150°C include lauric acid amide (melting point 87°C), palmitic acid amide (melting point 100°C), stearic acid amide (melting point 101°C), behenic acid amide (melting point 110°C), and hydroxystearin. Examples include acid amide (melting point: 107°C), oleic acid amide (melting point: 75°C), and erucic acid amide (melting point: 81°C).
Examples of substituted amides with a melting point of 50°C to 150°C include N-oleyl palmitic acid amide (melting point 68°C), N-stearyl stearic acid amide (melting point 95°C), N-stearyl oleic acid amide (melting point 67°C), -oleyl stearic acid amide (melting point 74°C) and N-stearyl erucic acid amide (melting point 69°C).
Bisamides with a melting point of 50°C to 150°C include methylene bisstearamide (melting point 142°C), ethylene bisstearamide (melting point 145°C), ethylene bishydroxystearamide (melting point 145°C), and ethylene bisbehenic acid. amide (melting point 142°C), hexamethylene bisstearamide (melting point 140°C), hexamethylene bisbehenic acid amide (melting point 142°C), hexamethylene hydroxystearamide (melting point 135°C), ethylene bisoleic acid amide (melting point 119°C), ethylene biserucic acid amide (melting point 120°C), hexamethylenebisoleic acid amide (melting point 110°C), N,N'-distearyladipic acid amide (melting point 141°C), N,N'-distearyl Examples include sebacic acid amide (melting point 136°C), N,N'-dioleyladipic acid amide (melting point 118°C), and N,N'-dioleyl sebacic acid amide (melting point 113°C).
Examples of the methylolamide having a melting point of 50°C to 150°C include methylolstearamide (melting point of 110°C).
Examples of esteramides having a melting point of 50°C to 150°C include stearamide ethyl stearate (melting point 82°C).
Among these, from the viewpoint of improving blocking resistance, those having a molecular weight of 200 to 800 are preferred. More preferably, it is 250-700.

The fatty acids constituting the fatty acid amide are preferably saturated fatty acids with 12 to 22 carbon atoms and/or unsaturated fatty acids with 16 to 25 carbon atoms, and saturated fatty acids with 16 to 18 carbon atoms and/or unsaturated fatty acids with 18 to 22 carbon atoms. Saturated fatty acids are more preferred. Particularly preferred saturated fatty acids are lauric acid, palmitic acid, stearic acid, behenic acid, and hydroxystearic acid, and particularly preferred unsaturated fatty acids are oleic acid and erucic acid.
Among these, fatty acid amides consisting of at least one fatty acid selected from the group consisting of palmitic acid, stearic acid, behenic acid, hydroxystearic acid, oleic acid, and erucic acid are preferred, and palmitic acid amide, erucic acid amide, and ethylene bisolein are preferred. At least one fatty acid amide selected from the group consisting of acid amides is more preferred, and ethylenebisoleic acid amide is particularly preferred.

The content of amide wax contained in the surface protective layer is preferably 0.1 to 22.5% by mass, more preferably 0.1 to 15% by mass, and even more preferably 0.1 to 7.5% by mass. It is. When it is within the above range, blocking resistance is improved.

《Hydrocarbon wax》
Preferably, the surface protective layer contains hydrocarbon wax. Including the hydrocarbon wax improves the water friction resistance of the surface protective layer.
The hydrocarbon wax is preferably hydrocarbon wax particles having a hardness (penetration) of 0.5 to 12. Examples of the hydrocarbon wax include polyethylene wax, Fischer-Tropsch wax, paraffin wax, microstarine wax, and polypropylene wax. Among them, hydrocarbon waxes including polyethylene wax are preferred.
In the overcoat agent, the hydrocarbon wax can be used in either liquid or particulate form, and particulate form is preferred. The average particle diameter of the hydrocarbon wax particles is preferably 0.3 to 10 μm, more preferably 0.8 to 7 μm. The content of the hydrocarbon wax particles in the surface protective layer is preferably 0.1 to 10% by mass, more preferably 0.5 to 7% by mass.

《Chelate crosslinking agent》
The surface protective layer preferably contains a chelate crosslinking agent. Including the chelate crosslinking agent improves the water friction resistance of the surface protective layer. Examples of the chelate crosslinking agent include titanium chelate and zirconium chelate. Examples of titanium chelates include titanium alkoxides such as tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, tetramethyl titanate, and tetrastearyl titanate, triethanolamine titanate, titanium acetylacetetonate, and titanium. Tetraacetylacetonate, tetraisopropoxytitanium, titanium ethyl acetoacetate, titanium lactate, octylene glycol titanate, titanium n-butyl phosphate, propanediox titanium bis(ethyl acetylacetate), and the like can be mentioned. Examples of the zirconium chelate include zirconium propionate, zirconium acetylacetate, and the like. Among these, chelate crosslinking agents that do not generate acetylacetone after the crosslinking reaction are preferred from an environmental standpoint.

The content of the chelate crosslinking agent in the surface protective layer is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass. When the content is 0.1% by mass or more, heat resistance, oil resistance, and vinyl chloride blocking resistance are improved, and when the content is 5% by mass or less, the overcoat agent has excellent storage stability. The use of these chelate crosslinking agents has the effect of improving the water friction resistance of the formed film.

<Overcoat agent>
The overcoat agent contains a cellulose resin (a') having an average fiber diameter or an average particle diameter of less than 10 μm, and may further contain an organic solvent and the above-mentioned additives.

<Organic solvent>
The overcoat agent may contain an organic solvent. Examples of organic solvents include hydrocarbons such as methylcyclohexane and ethylcyclohexane; ketones such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone; esters such as ethyl acetate, n-propyl acetate, and butyl acetate; Alcohol-based non-aromatic organic solvents such as alcohol, ethanol, propanol, isopropanol (IPA), and butanol can be used. The organic solvent may be appropriately selected in consideration of reducing the amount of solvent remaining in the film after printing, and one type may be used alone or two or more types may be used in combination. The content of the organic solvent is preferably 30 to 95% by weight, more preferably 50 to 90% by weight, and particularly preferably 70 to 85% by weight based on 100% by weight of the overcoat agent.

In order to improve halftone dot reproducibility during printing, it is preferable to use a glycol ether solvent. The glycol ether solvent is not particularly limited, and examples thereof include ethylene glycol ether and propylene glycol ether.
Among them, propylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether are preferred, and diethylene glycol monoethyl ether is more preferred. The glycol ether solvent is preferably used in an amount of 5 to 25% by weight, particularly preferably 5 to 15% by weight, based on 100% by weight of the organic solvent.
<Formation of surface protective layer>
The surface protective layer can be formed by printing an overcoat agent on the paper base material (A) on the side opposite to the side on which the heat seal layer is provided, and then removing volatile components. Furthermore, when there is a printed layer on the paper base material (A) on the side opposite to the side on which the heat seal layer is provided, a surface protective layer can be formed on the printed layer in the same way as in the case where there is no printed layer. The overcoat agent printing method includes flexographic printing, for example, the overcoat agent is diluted with a diluting solvent to a viscosity and concentration suitable for gravure printing, and is supplied alone or in a mixture to each printing unit, and then applied. be done. Thereafter, a surface protective layer can be obtained by fixing the film by drying in an oven or the like.

It is preferable that the packaging material of the present invention further has a printed layer from the viewpoint of imparting decoration or beauty, contents, expiration date, and indication of the manufacturer or seller. Moreover, from the viewpoint of oxygen barrier properties, it is preferable to further include a barrier layer.

[Printing layer]
The printing layer in the present invention is a layer containing a pigment and a binder resin, and is formed by printing on the surface of the paper base material (A) opposite to the surface provided with the heat-sealing layer using a printing ink described below. can. The printing layer is formed using printing ink, and the printing method can be appropriately selected from known printing methods such as gravure printing and flexo printing, with gravure printing being preferred. The thickness of the printed layer is preferably 0.1 to 10 μm, more preferably 0.3 to 6 μm, and particularly preferably 0.5 to 3 μm.
In this specification, the term "printed layer" includes not only a single printed layer but also a layer in which a plurality of printed layers are laminated, and printed layers having different hues can be arbitrarily combined.

<Pigment>
Examples of pigments include organic pigments, inorganic pigments, and extender pigments.
《Organic pigment》
Examples of organic pigments include organic compounds and organometallic complexes, such as soluble azo, insoluble azo, azo, phthalocyanine, halogenated phthalocyanine, anthraquinone, anthurone, dianthraquinonyl, and anthraquinone. Pyrimidine series, perylene series, perinone series, quinacridone series, thioindigo series, dioxazine series, isoindolinone series, quinophthalone series, azomethine azo series, flavanthrone series, diketopyrrolopyrrole series, isoindoline series, indanthrone series, carbon black One example is the system.
Also, for example, Carmine 6B, Lake Red C, Permanent Red 2B, Disazo Yellow, Pyrazolone Orange, Carmine FB, Chromophthal Yellow, Chromophthal Red, Phthalocyanine Blue, Phthalocyanine Green, Dioxazine Violet, Quinacridone Magenta, Quinacridone Red, Indans Examples include lon blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, and daylight fluorescent pigments.

The hue of the organic pigment is preferably at least one selected from the group consisting of black pigment, indigo pigment, green pigment, red pigment, purple pigment, yellow pigment, orange pigment, and brown pigment. Furthermore, at least one selected from the group consisting of black pigments, indigo pigments, red pigments, and yellow pigments is more preferred.

Specific examples of organic pigments are listed in C.I. of Color Index International (abbreviated as C.I.). I. Indicate by number.
Preferably C. I. Pigment Red 57:1, C.I. I. Pigment Red 48:1, C.I. I. Pigment Red 48:2, C. I. Pigment Red 48:3, C.I. I. Pigment Red 146, C. I. Pigment Red 242, C. I. Pigment Yellow 83, C. I. Pigment Yellow 14, C. I. Pigment Orange 38, C. I. Pigment Orange 13, C. I. Pigment Yellow 180, C. I. Pigment Yellow 139, C. I. Pigment Red 185, C. I. Pigment Red 122, C. I. Pigment Red 178, C. I. Pigment Red 149, C. I. Pigment Red 144, C. I. Pigment Red 166, C. I. Pigment Violet 23, C. I. Pigment Violet 37, C. I. Pigment Blue 15, C. I. Pigment Blue 15:1, C. I. Pigment Blue 15:2, C. I. Pigment Blue 15:3, C. I. Pigment Blue 15:4, C. I. Pigment Blue 15:6, C. I. Pigment Green 7, C. I. Pigment Orange 34, C. I. Pigment Orange 64, C. I. Pigment Black 7, and it is preferable to use one kind or two or more kinds.

《Inorganic pigment》
Inorganic pigments include, for example, titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, aluminum particles, mica, bronze powder, chrome vermilion, chrome yellow, cadmium red. , ultramarine, navy blue, red iron oxide, yellow iron oxide, iron black, titanium oxide, zinc oxide, etc. Aluminum such as kaolin, clay, magnesium carbonate, etc. can be leafing type or non-leafing type, but non-leafing type is preferable.

<Binder resin>
The binder resin is not particularly limited and can be appropriately selected from known resins used in printing inks. Such binder resins include, for example, polylactic acid resin, urethane resin, cellulose resin (a'') with an average fiber diameter or average particle diameter of less than 10 μm, polyamide resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer. Resin, vinyl chloride-acrylic copolymer resin, castor oil-based resin, rosin resin, vinyl acetate resin, ethylene-vinyl acetate copolymer resin, acrylic resin, urethane-acrylic resin, styrene resin, styrene-acrylic acid resin, styrene - Allyl alcohol copolymer resin, styrene-maleic acid copolymer resin, maleic anhydride resin, maleic acid resin, rosin-modified maleic acid resin, cycloolefin resin, Dammar resin, polyester resin, alkyd resin, terpene resin, phenol-modified terpene resin , ketone resins, cyclized rubbers, chlorinated rubbers, butyral, polyacetal resins, silicone resins, and modified resins thereof, and one type can be used alone or two or more types can be used in combination.
The printing layer preferably contains a cellulose resin (a'') having an average fiber diameter or average particle diameter of less than 10 μm as a binder resin, and a cellulose resin (a'') having an average fiber diameter or average particle diameter of less than 10 μm. , polyamide resin, urethane resin, styrene-maleic acid copolymer resin, styrene-allyl alcohol copolymer resin, and acrylic resin, and the average fiber diameter or average particle diameter is 10 μm. It is more preferable to contain cellulose resin (a'') of less than It is particularly preferable that the resin contains a cellulose resin (a'') and a urethane resin.

<Cellulose resin (a'') with an average fiber diameter or average particle diameter of less than 10 μm>
The cellulose resin (a'') with an average fiber diameter or average particle diameter of less than 10 μm and its preferred embodiment are as explained in the above [Surface protective layer] (cellulose resin with an average fiber diameter or average particle diameter of less than 10 μm). The description in section (a')) can be cited.
In addition, the cellulose resin (a'') with an average fiber diameter or average particle diameter of less than 10 μm is a cellulose resin (a1) with an average fiber diameter or average particle diameter of less than 10 μm contained in the paper base material (A), or It may be the same as or different from the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm contained in the surface protective layer.

<Urethane resin>
The urethane resin preferably has a weight average molecular weight of 10,000 to 100,000, more preferably 20,000 to 80,000. The glass transition temperature is preferably 0°C or lower, more preferably -60 to 0°C, even more preferably -40 to -5°C. When it is within the above range, the total light transmittance becomes good.
In addition, the urethane resin preferably has an amine value and/or a hydroxyl value, and the amine value is determined in consideration of browning when mixed with cellulose resin (a'') having an average fiber diameter or average particle diameter of less than 10 μm. , preferably from 0 to 10 mgKOH/g, more preferably from 0 to 5 mgKOH/g, particularly preferably from 0 to 3 mgKOH/g. The hydroxyl value is preferably 0.5 to 30 mgKOH/g, more preferably 1 to 20 mgKOH/g. Within the above range, the total light transmittance will be good.

The above amine value is the number of mg of potassium hydroxide equivalent to the equivalent amount of hydrochloric acid required to neutralize the amino groups contained in 1 g of resin. The method for measuring the amine value is as follows.
[Method for measuring amine value]
Accurately weigh 5 to 10 g of the sample (solid mass of S sample in g)). Add 25 mL of toluene and 25 mL of n-butanol to the accurately weighed sample and dissolve thoroughly. Add 30 mL of methanol to this, and perform potentiometric titration with a 0.1 mol/L hydrochloric acid aqueous solution (potency: f). Using the titration amount (AmL) at this time, the amine value can be determined by the following (Formula 1).

(Formula 1)
Amine value = (A x f x 0.1 x 56.108)/S [mgKOH/g]

The above hydroxyl value is the value obtained by converting the amount of hydroxyl groups in 1 g of resin into mg of potassium hydroxide, which is calculated by acetylating the hydroxyl groups in the resin with an excess of acetylation reagent and back titrating the remaining acid with an alkali. In accordance with JIS K0070.

The urethane resin preferably contains structural units derived from polyether polyol and/or polyester polyol, and the total content thereof is preferably 10 to 50% by mass based on 100% by mass of the urethane resin solid content, and more preferably It is preferably 10 to 60% by weight, more preferably 5 to 80% by weight. When it is within the above range, the total light transmittance becomes good.
The urethane resin is not limited, but for example, a urethane resin obtained by reacting a polyamine as a chain extender with a urethane prepolymer having an isocyanate group at the end obtained by reacting a polyol and a polyisocyanate. Can be mentioned.

As the polyol, for example, various known polyester polyols, polyether polyols, etc. can be used, and one type or two or more types of each may be used in combination.
Examples of the polyester polyols include polyester polyols obtained by dehydration condensation or polymerization of saturated or unsaturated low-molecular-weight polyols and polyhydric carboxylic acids or their anhydrides; cyclic ester compounds such as polycaprolactone, polyvalerolactone, Examples include polyester polyols obtained by ring-opening polymerization of lactones such as poly(β-methyl-γ-valerolactone).
Examples of the saturated or unsaturated low molecular weight polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1, 3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5pentanediol, hexanediol, octanediol, 1,4-butanediol, 1 , 4-butylene diol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, pentaesritol can be mentioned. Examples of the polyhydric carboxylic acids include adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, speric acid, azelaic acid, and sebacic acid. Acids include trimellitic acid and pyromellitic acid.
Examples of polyether polyols include polymers or copolymers of methylene oxide, ethylene oxide, propylene oxide, and tetrahydrofuran.
Both the polyester polyol and the polyether polyol preferably have a branched structure.

Examples of the polyisocyanate include various known aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. that are commonly used in the production of urethane resins. These may form a trimer to form an isocyanurate ring structure.
Examples of the aromatic diisocyanate include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzylisocyanate, dialkyldiphenylmethane diisocyanate, Examples include tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, and tolylene diisocyanate.
Examples of the aliphatic diisocyanate include butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate.
Examples of the alicyclic diisocyanate include cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, Examples include norbornane diisocyanate, m-tetramethylxylylene diisocyanate, hydrogenated 4,4-diphenylmethane diisocyanate, and dimer diisocyanate obtained by converting the carboxyl group of dimer acid into an isocyanate group.
Among these, at least one selected from the group consisting of tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, bis(isocyanatomethyl)cyclohexane, hexamethylene diisocyanate, and a trimer of hexamethylene diisocyanate is preferred. These polyisocyanates can be used alone or in combination of two or more.

Examples of the polyamine as a chain extender include ethylene diamine, propylene diamine, hexamethylene diamine, isophorone diamine, dicyclohexylmethane-4,4'-diamine, and the like. Further, as the polyamine, a polyamine having a hydroxyl group in the molecule, such as 2-hydroxyethylethylenediamine or 2-hydroxyethylpropylenediamine, may be used. These chain extenders can be used alone or in combination of two or more, and isophorone diamine is particularly preferred.

<Polyamide resin>
Although the polyamide resin is not particularly limited, it is preferably a thermoplastic polyamide soluble in an organic solvent, and a polycondensate of a polybasic acid and a polyvalent amine is preferably used.
Among these, polyamide resins containing a reaction product of an acid component containing a polymerized fatty acid and/or a dimer acid and an aliphatic and/or aromatic polyamine are preferred, and those containing a portion of primary and secondary monoamines are more preferred.
As for the polyamide resin and its preferred embodiment, the description in the section <Polyamide resin> explained in the above [Surface protective layer] can be cited.

<Styrene-maleic acid copolymer resin>
The styrene-maleic acid copolymer resin can be obtained, for example, by radical copolymerization of a styrene monomer and a maleic acid monomer. The solid content mass ratio of styrene monomer and maleic acid monomer is preferably 1:9 to 6:4, more preferably 2:8 to 5:5.

The styrene-maleic acid copolymer resin preferably has an acid value of 150 to 300 mgKOH/g, more preferably 215 to 270 mgKOH/g. When it is within the above range, water friction resistance is excellent. Note that the acid value is the number of mg of potassium hydroxide required to neutralize the acidic groups contained in 1 g of resin solid content, and is based on JIS K 0070.

The glass transition temperature of the styrene-maleic acid copolymer resin is preferably 60 to 125°C, more preferably 70 to 105°C. The weight average molecular weight is preferably 6,000 to 16,000, more preferably 10,000 to 15,000. When the glass transition temperature and weight average molecular weight are within the above ranges, water friction resistance is excellent.

Commercially available styrene-maleic acid copolymer resins include, for example, the XIRAN series (manufactured by Kawasaki Kagaku Co., Ltd.) and the Alastair series (manufactured by Arakawa Chemical Co., Ltd.).

<Styrene-allyl alcohol copolymer resin>
The styrene-allylic alcohol copolymer resin can be obtained, for example, by radical copolymerization of a styrene monomer and an allyl alcohol monomer. The solid content mass ratio of styrene monomer and allyl alcohol monomer is preferably styrene monomer/allyl alcohol monomer = 1/9 to 6/4, more preferably 2/8 to 5/5.

The styrene-allyl alcohol copolymer resin preferably has a hydroxyl value of 150 to 300 mgKOH/g, more preferably 180 to 250 mgKOH/g. When it is within the above range, the blocking resistance is excellent.

The glass transition temperature of the styrene-allylic alcohol copolymer resin is preferably 40 to 100°C, more preferably 50 to 80°C. The weight average molecular weight is preferably 1,000 to 5,000, more preferably 2,000 to 4,000. When the glass transition temperature and weight average molecular weight are within the above ranges, water friction resistance is excellent. The acid value is preferably 50 to 300 mgKOH/g, more preferably 100 to 200 mgKOH/g. When it is within the above range, the blocking resistance is excellent.

Commercially available styrene-allyl alcohol resins include, for example, the SAA series (manufactured by Iondellbasell).

<Acrylic resin>
As for the acrylic resin in the printing layer, the description in the <acrylic resin> section described in the above-mentioned [heat seal layer] can be used.
The glass transition temperature of the acrylic resin in the printing layer is preferably 40 to 110°C, more preferably 60 to 90°C. The weight average molecular weight is preferably 5,000 to 100,000, more preferably 8,000 to 40,000. When the glass transition temperature and weight average molecular weight are within the above ranges, water friction resistance will be good.

Examples of commercially available acrylic resins for the printing layer include the DIANAL series (manufactured by Mitsubishi Rayon Co., Ltd.) and the ACRYDIC series (manufactured by DIC Co., Ltd.).

In the printing layer, the mass ratio of the cellulose resin (a'') to the binder resin other than the cellulose resin (a'') is preferably 99:1 to 30:70, more preferably 99:1 to 50: 50, more preferably 99:1 to 80:20. When it is within the above range, water friction resistance and blocking resistance will be good.

The content of the binder resin contained in the printing layer is preferably 20 to 80% by mass, more preferably 40 to 60% by mass. When it is within the above range, water friction resistance and blocking resistance will be good.

<Additives>
The printing ink and printing layer may further contain a pigment dispersant, an isocyanate curing agent, a chelate crosslinking agent, a hydrocarbon wax, a matting agent, a vapor phase silica, a wet silica, and an organic treatment to the extent that the effects of the present invention are not impaired. Additives such as silica, finely powdered silica such as alumina-treated silica, fatty acid amide wax, antifoaming agents, leveling agents, plasticizers, infrared absorbers, ultraviolet absorbers, and flame retardants can be used.

《Pigment dispersant》
As the pigment dispersant, anionic, nonionic, cationic, amphoteric, and other surfactants can be used.

《Isocyanate curing agent》
As the isocyanate curing agent, polyisocyanates and modified compounds thereof can be used. Specifically, biuret, isocyanurate, and adduct polyisocyanates are preferred, and diisocyanates are preferred as polyisocyanates; aromatic diisocyanates such as tolylene diisocyanate; 1,4-cyclohexane diisocyanate, isophorone diisocyanate, etc. Alicyclic diisocyanates; aliphatic diisocyanates such as hexamethylene diisocyanate; and araliphatic diisocyanates such as α, α, α', α'-tetramethylxylylene diisocyanate are preferably used.
Commercially available isocyanate curing agents include, for example, 24A-100, 22A-75, TPA-100, TSA-100, TSS-100, TAE-100, TKA-100, P301-75E, E402-808, E405- 70B, AE700-100, D101, D201, A101H (Asahi Kasei), My Tech Y260A (Mitsubishi Chemical), Coronate HX, Coronate Coronate HL, Coronate Coronate L (manufactured by Japan) Module N75MPA / X (manufactured by Bayer). Among these, isophorone diisocyanate and adducts and/or isocyanurates of isophorone diisocyanate are preferred.

《Chelate crosslinking agent》
Preferably, the printing ink and printing layer contain a chelate crosslinking agent. As the chelate crosslinking agent, the description in the <<Chelate crosslinking agent>> section explained in the above [Overcoat agent] can be cited.
The content of the chelate crosslinking agent in the printed layer is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight. When it is within the above range, the blocking resistance is excellent.

《Hydrocarbon wax》
Preferably, the printing ink and printing layer contain a hydrocarbon wax. By including the hydrocarbon wax, the adhesion to the paper base material (A) and the abrasion resistance of the printed layer are improved. As the hydrocarbon wax, the description in the section <<Hydrocarbon wax>> explained in the above [Surface protective layer] can be cited.
In the printing ink, the hydrocarbon wax can be used in either liquid or particulate form, and particulate form is preferred. The average particle diameter of the particles is preferably 0.3 to 10 μm, more preferably 0.8 to 7 μm. The content of the hydrocarbon wax particles in the printing layer is preferably 0.1 to 10% by mass, more preferably 0.5 to 7% by mass. When it is within the above range, the blocking resistance is excellent.

《Plasticizer》
It is preferable that the printing ink and the printing layer contain a plasticizer. The plasticizer, when added in a small amount, has the role of accelerating the volatility of the organic solvent, imparting flexibility to the printing layer, and increasing the adhesion to the paper base material (A). As the plasticizer, the description in the <<Plasticizer>> section explained in the above [Surface Protective Layer] can be cited.
The printing layer in the present invention preferably contains at least one plasticizer selected from the group consisting of castor oil, glycol ether, aliphatic dibasic acid ester, and tributyl acetyl citrate, and castor oil is more preferable.
The content of plasticizer in the printing layer is preferably 0.1 to 15% by weight, more preferably 5 to 15% by weight, and still more preferably 11 to 15% by weight. When it is within the above range, the blocking resistance is excellent.

<Printing ink>
The printing ink contains a pigment and a binder resin, and may further contain an organic solvent and optional additives. From the viewpoint of pigment dispersibility and workability, the printing ink preferably has a viscosity of 50 to 1,000 mPa·s at 25°C.

<Organic solvent>
As for the organic solvent and its preferred embodiment in the printing ink, the description in the section <Organic solvent> explained in the above-mentioned [Surface protective layer] can be cited.

<Formation of printing layer>
The printing layer can be formed, for example, by printing using printing ink on the side of the paper base material (A) opposite to the heat-sealing layer, and then removing volatile components. As a printing method, a gravure printing method is suitable; for example, the material is diluted with a diluting solvent to a viscosity and concentration suitable for gravure printing, and then supplied alone or in a mixture to each printing unit and applied. Thereafter, a printed layer can be obtained by fixing the film by drying in an oven or the like.

[Barrier layer]
It is preferable that the packaging material of the present invention further includes a barrier layer. When the packaging material has a barrier layer, the barrier layer is preferably located between the heat seal layer and the paper base material (A), or between the paper base material (A) and the surface protection layer, and the above packaging material is When a printed layer is included, it is also preferably located between the paper base material (A) and the printed layer. The barrier layer can be formed by a vacuum deposition method, a sputtering method, a T-die casting method, coating and drying of a barrier coating agent, etc. Components contained in the barrier layer include, for example, silica, alumina, polyvinylidene chloride, etc. Examples include resins, polyamide resins, polyvinyl alcohol resins, ethylene-vinyl alcohol copolymer resins, barrier nylon resins (MXD), and the like. The barrier layer may have a single layer structure or a multilayer structure, and may contain two or more types of compounds in one layer. The thickness of the barrier layer is preferably 10 to 300 nm from the viewpoint of oxygen barrier properties.

<Vacuum deposition method>
The vacuum deposition method is a method in which a metal such as aluminum is deposited under conditions of about 1200 to 1500° C. and 10 ⁻¹ to 10 ⁻² Pa by high-frequency induction heating, direct current heating, electron beam heating, or the like. The surface of the object to be deposited can be subjected to adhesion improvement treatment such as corona discharge treatment before vacuum deposition.

<Sputtering method>
The sputtering method is carried out by introducing an inert gas such as Ar and applying a voltage under conditions of about 10 ^-1 to 10 ^-2 Pa <Coating and drying of barrier coating agent>
The barrier coating agent can be applied and dried by, for example, printing the barrier coating agent on the surface of the paper base material (A) and then removing volatile components. As a printing method, a gravure printing method or a flexographic printing method is suitable. For example, the material is diluted with a diluting solvent to a viscosity and concentration suitable for gravure printing, and then supplied alone or in a mixture to each printing unit and applied. . Thereafter, the barrier layer can be obtained by fixing the film by drying in an oven or the like.

Preferred examples of the laminated structure of the packaging material include the following. In the examples below, "/" means the boundaries of each layer.
Heat seal layer/Paper base material (A)/Surface protective layer Heat seal layer/Barrier layer/Paper base material (A)/Surface protective layer Heat seal layer/Paper base material (A)/Barrier layer/Surface protective layer Heat seal Layer/Paper base material (A)/Print layer/Surface protective layer Heat seal layer/Barrier layer/Paper base material (A)/Print layer/Surface protective layer Heat seal layer/Paper base material (A)/Barrier layer/Printing Layer/Surface protection layer Heat seal layer/Paper base material (A)/Printing layer/Barrier layer/Surface protection layer

<Packaging bag>
The packaging material in the present invention is cut into a predetermined size, and the edges are heat-sealed with the heat-sealing layers aligned with each other to form a packaging bag. The heat sealing temperature is preferably 50 to 250°C, more preferably 80 to 180°C. The heat sealing pressure may be 1 to 5 kg/cm ² or the like. A packaging bag can be formed by folding a single packaging material and heat-sealing the edges, or by heat-sealing two or more packaging materials. Moreover, a packaging bag can also be formed by heat-sealing all openings after packaging the contents. This packaging bag can be widely used as a packaging bag for foods, medicines, etc.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples. Note that parts and % in the present invention represent parts by mass and % by mass unless otherwise noted. Moreover, "NV." represents the mass % of non-volatile content.

<Preparation Example 1> Preparation of nitrocellulose resin solution NC1 Nitrocellulose nc1 (manufactured by NOBEL, product name NC DHX 5-10, NV. 70% (solvent: isopropyl alcohol), weight average molecular weight: 10,000, solution concentration 25 Viscosity at 0%: 2 seconds) was mixed and dissolved in 33.6 parts of ethyl acetate and 33.6 parts of isopropyl alcohol to obtain a nitrocellulose resin solution (NC1) with a solid content of 30%.

<Preparation Examples 2-4> Preparation of Nitrocellulose Resin Solutions NC2-4 Nitrocellulose resin solutions NC2-4 were obtained in the same manner as in Preparation Example 1 except that the raw materials described below were used. Note that nc4 does not satisfy any of the above-mentioned preferred viscosity ranges (1) to (3).
・(NC2) Nitrocellulose nc2 (manufactured by NOBEL, product name NC DHX 4-6, NV.70% (solvent: isopropyl alcohol), viscosity at 25.0% solution concentration: 1.2 seconds)
・(NC3) Nitrocellulose nc3 (manufactured by NOBEL, product name NC DHX 30-50, NV.70% (solvent: isopropyl alcohol), viscosity at solution concentration 25.0%: 10 seconds)
・(NC4) Nitrocellulose nc4 (manufactured by NOBEL, product name NC DHL 120-170, NV.70% (solvent: isopropyl alcohol), viscosity at solution concentration 12.2%: 20 seconds,)

<Preparation Example 5> Preparation of cellulose acetate butyrate resin solution CAB1 Cellulose acetate butyrate (manufactured by EASTMAN CHEMICAL, product name CAB553-0.4, NV. 70% (solvent: isopropyl alcohol), glass transition temperature: 136 ° C. Weight average molecular weight 20,000, viscosity at 25.0% solution concentration: 5 seconds) was mixed and dissolved in 33.6 parts of ethyl acetate and 33.6 parts of isopropyl alcohol to obtain cellulose acetate butylene with a solid content of 30%. A rate resin solution (CAB1) was obtained.

<Preparation Example 6> Preparation of polyamide resin solution PA1 30 parts of polyamide resin pa1 (manufactured by Tsukino Shokuhin Kogyo Co., Ltd., product name Vegechem Green 725, NV. 100%, softening point 116°C, weight average molecular weight 8,000), and 70 parts of isopropyl alcohol was charged and dissolved at 50° C. for 2 hours under a nitrogen stream to obtain a polyamide resin solution (PA1) with a solid content of 30%.

<Adjustment Example 7> Adjustment of polyamide resin solutions PA2 and PA3)
Polyamide resin solutions PA2 and PA3 having a solid content of 30% were obtained in the same manner as in Preparation Example 4, except that the raw materials described below were used.
・(PA2) Polyamide resin pa2 (manufactured by Harima Kasei Co., Ltd., product name Newmide 846, NV. 100%, softening point 110°C)
・(PA3) Polyamide resin pa3 (manufactured by Harima Kasei Co., Ltd., product name Newmide 872, NV. 100%, softening point 112°C)

<Preparation Example 8> Preparation of urethane resin solution PU1 Poly(1,2-propylene glycol) with a number average molecular weight of 2,000 ( 257.86 parts of hydroxyl value 56.1 mgKOH/g), 18.01 parts of isophorone diisocyanate, 20.27 parts of diphenylmethane diisocyanate, 0.03 parts of tin(II) 2-ethylhexanoate, and 200 parts of ethyl acetate were charged, followed by a nitrogen stream. The mixture was reacted at 90° C. for 3 hours to obtain 496.14 parts of a solution of terminal isocyanate prepolymer. Next, a mixture of 3.86 parts of isophoronediamine, 280 parts of isopropyl alcohol, and 220 parts of ethyl acetate was gradually added to the obtained solution of the terminal isocyanate prepolymer at room temperature, and then reacted at 50 ° C. for 1 hour. A urethane resin solution (PU1) was obtained with a solid content of 30%, a weight average molecular weight of 78,000, and an amine value not detected (less than 0.1 mgKOH/g).

<Preparation Example 9> Preparation of chlorinated rubber resin solution CG1 30 parts of chlorinated rubber resin CG1 (manufactured by Sumika Bayer Urethane Co., Ltd., product name Pergood S20, NV. 100%) and 70 parts of ethyl acetate were charged and heated under a nitrogen stream. The mixture was dissolved at 50° C. for 2 hours to obtain a chlorinated rubber resin solution (CG1) with a solid content of 30%.

<Preparation Example 10> Preparation of polyethylene resin emulsion PE1 Flowene UF80 (manufactured by Sumitomo Seika Chemicals, polyethylene, density: 0.919, NV. = 100%) 50 parts of water/isopropyl alcohol mixed solvent (mass % ratio 1:1) 50 parts were added and mixed with stirring to obtain polyethylene resin emulsion PE1.

<Preparation Example 11> Preparation of rosin resin solution R1 Add 50 parts of ethyl acetate to 50 parts of Marquid No1 (manufactured by Arakawa Chemical Co., Ltd., maleic acid rosin, acid value: 25 mgKOH/g, weight average molecular weight: 300, NV. = 100%). The mixture was added, stirred and mixed to obtain a rosin resin solution R1.

<Adjustment Example 12> Adjustment of heat sealing agent HS1 Acrylic resin emulsion AC1 (BASF JONCRYL PDX7356, acid value: 78 mgKOH/g, glass transition temperature: 25°C, NV. = 50%) 91.7 parts, water/isopropyl 8.2 parts of an alcohol mixed solvent (mass ratio 1:1) and 0.1 part of BYK-024 (manufactured by BYK, antifoaming agent) were added and mixed by stirring to obtain a heat sealing agent HS1.
<Preparation Examples 13 to 19> Preparation of heat sealants HS2 to 8 Heat sealants HS2 to 8 were obtained in the same manner as in Preparation Example 12, except that the raw materials and compounding ratios listed in Table 1 were used. The properties of the raw materials used are as follows.
・Acrylic resin emulsion AC2 (manufactured by BASF, JONCRYL PDX-7430, acid value: 30 mgKOH/g, glass transition temperature: 34°C, NV. = 50%)
・Acrylic resin emulsion AC3 (manufactured by Seiko PMC, PE-1126, acid value: 50 mgKOH/g, glass transition temperature: -12°C, NV. = 50%)
・Ethylene-vinyl acetate copolymer resin emulsion EVA1 (manufactured by Japan Coating Resin Co., Ltd., Aquatex MC3800, minimum film forming temperature: 100°C, NV. = 50%)
・Ethylene-vinyl acetate copolymer resin emulsion EVA2 (manufactured by Japan Coating Resin Co., Ltd., Aquatex EC1200, minimum film forming temperature: 80°C, NV. = 50%)
・Ethylene-vinyl acetate copolymer resin emulsion EVA3 (manufactured by Sumitomo Chemical Co., Ltd., Sumikaflex 305HQ, minimum film forming temperature: 0°C, NV. = 50%)
・Urethane resin solution PU1 (weight average molecular weight: 38,000, NV.=50%)
・Polyethylene resin emulsion PE1 (NV.=50%)

<Preparation Example 20> Production of overcoat agent V1 13.5 parts of nitrocellulose resin solution NC1, 52.1 parts of polyamide resin solution PA1, 1.9 parts of diethylene glycol monobutyl ether, 3 parts of hexamenlene bisoleic acid amide, polyethylene Wax 8.3 parts, ethyl acetate/propyl acetate/isopropanol mixed solvent (mass ratio = 1/1/1) 14 parts, methylcyclohexane/methylpropylene glycol mixed solvent (mass ratio = 1/1) 6.3 parts, water 0.9 parts were stirred and mixed to obtain an overcoat agent V1.

<Preparation Examples 21 to 32> Production of Overcoat Agents V2 to 13 Overcoat Agents V2 to 13 were obtained in the same manner as Preparation Example 20, except that the raw materials and compounding ratios listed in Table 2 were used. The properties of the raw materials used are as follows.

<Comparative Preparation Examples 1 and 2> Production of Overcoat Agents V14 and 15 Overcoat Agents V14 and 15 were obtained in the same manner as Preparation Example 20, except that the raw materials and compounding ratios listed in Table 2 were used.

<Manufacture of paper base material (A)>
The method for producing the paper base material (A) will be shown below in production examples.

<Calculation of resin (a) content of paper base material (A)>
Regarding the obtained paper base material (A), the resin (a) content of the paper base material was calculated by the method shown below.
Five 10 cm square (100 cm ² ) samples were cut out from the kraft paper and the obtained paper base material, and the mass was measured, and the 5 sample average kraft paper mass and the 5 sample average paper base material (A) were measured. The mass was calculated for each, and the resin (a) content of the paper base material (A) was calculated using the following calculation formula. The kraft paper is kraft paper before being soaked.
(Formula 2)
Resin (a) content of paper base material (A) = (5 sample average weight of paper base material (A)) - (5 sample average weight of kraft paper) [mg]

<Production Example 1> Production of paper base material (A) S1 Kraft paper: unbleached kraft pulp was used for viscose liquid B1 (cellulose concentration: 25%, cellulose weight average molecular weight: 400,000, medium: water) Kraft paper (manufactured by Nippon Paper Industries Co., Ltd., Ryosara Kraft K, basis weight 70 g/m ² ) was soaked for 1 minute, squeezed at 100 KPa using nip rolls (manufactured by Tester Sangyo Co., Ltd.), and then soaked in an aqueous sulfuric acid solution with a concentration of 10% by mass. The paper base ( A) S1 was obtained. The average content of resin (a) in the 10 cm square sample cut out from S1 was 24 mg (resin amount ratio in the paper base material was 30%).
Furthermore, in scanning electron microscopy (SEM), the resin derived from viscose liquid B1 is derived from a resin solution with an average fiber diameter or average particle diameter of less than 10 μm, so the average fiber diameter or average particle diameter is less than 10 μm. This corresponds to resin.
<Production Examples 2 and 3> Production of paper base materials (A) S2 and 3 Paper base materials (A) S2 and 3 were produced respectively in the same manner as in Production Example 1, except that the following viscose liquid was used. did.
・Viscose liquid B2 (cellulose concentration: 25%, cellulose weight average molecular weight: 200,000, medium: water)
・Viscose liquid B3 (cellulose concentration: 25%, cellulose weight average molecular weight: 600,000, medium: water)
<Production Example 4> Production of paper base material (A) S4 Kraft paper is immersed in paraffin resin solution W1 (paraffin concentration: 25% by mass, paraffin melting point: 50°C, paraffin weight average molecular weight: 400, medium: isoparaffin) for 1 minute. Then, the paper base material (A) S4 was obtained by squeezing at 100 KPa using a nip roll (manufactured by Tester Sangyo Co., Ltd.) and drying.
<Production Examples 5 to 8> Production of paper base materials (A) S5 to 8. Paper base materials (A) S5 to 8 were produced in the same manner as in Production Example 1, except that R1 and the following viscose liquid were used. Each was produced.
・Viscose liquid B4 (cellulose concentration: 5%, cellulose weight average molecular weight: 400,000, medium: water)
・Viscose liquid B5 (cellulose concentration: 15%, cellulose weight average molecular weight: 400,000, medium: water)
・Viscose liquid B6 (cellulose concentration: 40%, cellulose weight average molecular weight: 400,000, medium: water)

Table 3 shows the resin (a) contents of S2 to S8.

<Manufacture of packaging materials>
A method for manufacturing the packaging material will be shown in Examples below.

<Calculation of the mass of the printing layer>
Regarding the obtained first intermediate laminate, the mass of the printed layer was calculated by the method shown below.
Five 10 cm square (100 cm ² ) samples were cut out from the obtained first intermediate laminate and the paper base material (A), and their mass was measured, and the average mass of the first intermediate laminate of the 5 samples was determined. , and the average mass of the paper base material (A) for five samples were calculated, respectively, and the mass of the printed layer was calculated using the following calculation formula.
(Formula 3)
Mass of printing layer = (first intermediate laminate mass of 5 samples average) - (paper base material (A) mass of 5 samples average) [mg]

<Calculation of mass of surface protective layer>
Regarding the obtained second intermediate laminate, the mass of the surface protective layer was calculated by the method shown below.
Five 10 cm square (100 cm ² ) samples were cut out from each of the obtained second intermediate laminate and first intermediate laminate, and their mass was measured, and the average mass of the 5 samples was determined. , and the average mass of the first intermediate laminate for five samples were calculated, respectively, and the mass of the surface protective layer was calculated using the following formula.
(Formula 4)
Mass of surface protective layer = (5-sample average second intermediate laminate mass) - (5-sample average first intermediate laminate mass) [mg]

<Resin (a) ratio in packaging material>
Cut out five 10 cm square (100 cm ² ) samples from the obtained packaging material, measure their mass, calculate the average mass of the packaging material for the five samples, and calculate the resin (a) ratio in the packaging material using the following formula: was calculated. Note that (resin content of paper base material (A)) used the value calculated in the above-mentioned <Calculation of resin content of paper base material (A)>.
(Formula 5)
Resin (a) ratio in packaging material = (resin content of paper base material (A)) / (5 sample average packaging material mass) [mass%]

<Example 1> Production of packaging material P1 Printing ink (Ecocolor HR23 Yellow, manufactured by Toyo Ink Co., Ltd., yellow ink, details of the contained resin will be described later) and overcoat agent V1 were mixed in ethyl acetate:isopropyl alcohol = 7:3 (mass) The viscosity was adjusted to 15 seconds at 25° C. (Zahn cup #3 (manufactured by Rigosha)).
Next, paper substrate (A) S1 was coated with diluted Ecocolor HR23 Yellow using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm under the conditions of a printing speed of 50 m/min and an inline oven of 60°C. was printed to form a printed layer, thereby obtaining a first intermediate laminate p'1 having a paper base material (A)/printed layer configuration. The mass of the printed layer of a 10 cm square sample cut out from the first intermediate laminate p'1 was 2.6 mg.
Next, on the printing layer of the first intermediate laminate p'1, using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm, under the conditions of a printing speed of 50 m/min and an in-line oven of 60° C. An overcoat agent V1 was printed to obtain a second intermediate laminate p''1 having a structure of paper base material (A)/printed layer/surface protective layer. The mass of the surface protective layer of a 10 cm square sample cut out from the second intermediate laminate p''1 was 4.9 mg.
On the opposite side of the printing layer of the paper base material (A) in the second intermediate laminate p''1, a printing speed of 50 m/min was applied in-line using a gravure printing machine equipped with a gravure plate with a plate depth of 50 μm. A heat sealing layer is formed by printing the heat sealing agent HS1 twice in an oven at 70° C. to form a packaging material P1 having a composition of heat sealing layer/paper base material (A)/printing layer/surface protection layer. I got it. The average mass of the 10 cm square samples cut out from the packaging material P1 was 83 mg.

The resins contained in the printing ink Ecocolor HR23 Yellow are as follows.
・Nitrocellulose resin solution NC5 (weight average molecular weight: 11,000, viscosity at 25.0% solution concentration: 3 seconds)
・Urethane resin solution PU2 (weight average molecular weight: 50,000, glass transition temperature: -20°C, amine value not detected (less than 0.1 mgKOH/g))
Note that the solid content ratio of NC5 and PU2 is NC5:PU2=90:10.

<Examples 2 to 33> Production of packaging materials P2 to 33 Follow the same procedure as in Example 1 except that the heat sealing agent, paper base material (A), printing ink, and overcoating agent shown in Table 4 were used. , packaging materials P2 to P33 having similar configurations were produced, respectively.
<Comparative Example 1> Production of packaging material P34 In Comparative Example 1, kraft paper was used as the paper base material (A). Since the kraft paper does not contain resin, it does not fall under the definition of paper base material (A) in the present invention, and therefore is hereinafter referred to as paper base material (A').
Printing ink (Ecocolor HR23 Yellow, manufactured by Toyo Ink Co., Ltd., yellow ink) and overcoat agent V1 were diluted with a mixed solvent of ethyl acetate:isopropyl alcohol = 7:3 (mass ratio), and each was prepared using Zahn Cup #3 (Rigosha). The viscosity was adjusted to 15 seconds at 25°C.
Next, diluted Ecocolor HR23 Yellow was applied to the paper base material (A') using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm under the conditions of a printing speed of 50 m/min and an inline oven of 60°C. was printed to form a printed layer, thereby obtaining a first intermediate laminate p'34 having a paper base material (A')/printed layer structure. The mass of the printed layer of a 10 cm square sample cut out from the first intermediate laminate p'34 was 2.6 mg.
Next, on the printing layer of the first intermediate laminate p'34, using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm, under the conditions of a printing speed of 50 m/min and an in-line oven of 60° C. The overcoat agent V1 was printed to obtain a second intermediate laminate p''34 having a structure of paper base material (A')/printed layer/surface protective layer. The mass of the surface protective layer of the 10 cm square sample cut out from the second intermediate laminate p''34 was 4.9 mg.
The surface opposite to the printing layer of the paper base material (A') in the intermediate laminate p''34 was printed using a gravure printing machine equipped with a gravure plate with a plate depth of 50 μm, at a printing speed of 50 m/min, and in an in-line oven 70. ℃ conditions, the heat sealing agent HS1 is printed twice to form a heat sealing layer, and packaging material P' having the composition of heat sealing layer/paper base material (A')/printing layer/surface protection layer is obtained. I got 1.
<Comparative Examples 2 to 5> Production of packaging materials P35 to 38 Follow the same procedure as Example 1 except that the heat sealing agent, paper base material (A), printing ink, and overcoating agent shown in Table 5 were used. , packaging materials P35 to P38 having similar configurations were produced, respectively.

[Evaluation of packaging materials]
The packaging materials P1 to 38 obtained in Examples 1 to 33 and Comparative Examples 1 to 5 were evaluated as described below. The results are shown in Tables 4 and 5.

<Total light transmittance>
The obtained packaging material was cut into 20 mm square pieces and measured in accordance with JIS K 7361-1 using Spectral haze meter SH7000 manufactured by Nippon Denshoku Kogyo Co., Ltd. by entering light from the surface protective layer side of the packaging material. The results were evaluated based on the following criteria. Note that A, B, and C are within a range that causes no practical problems.
"Evaluation criteria"
A. Total light transmittance is 70% or more.
B. Total light transmittance is 60% or more and less than 70%.
C. Total light transmittance is 40% or more and less than 60%.
D. Total light transmittance is less than 40%.

<Oxygen barrier evaluation>
The oxygen permeability of the obtained packaging material was measured in accordance with JIS K 7126-2:2006, and evaluated according to the following criteria. Note that A, B, and C are within a range that causes no practical problems.
"Evaluation criteria"
A. Oxygen permeability is less than 100g/m ² ·24h.
B. Oxygen permeability is 100 g/m ² ·24 h or more and less than 1000 g/m ² ·24 h.
C. Oxygen permeability is 1000 g/m ² ·24 h or more and less than 10000 g/m ² ·24 h.
D. Oxygen permeability is 10,000 g/m ² ·24 h or more.

<Water friction resistance>
The obtained packaging material was cut into a size of 25 mm x 150 mm, and the water abrasion resistance was evaluated using a Gakushin type abrasion fastness tester manufactured by Tester Sangyo Co., Ltd. according to the following criteria. Note that A, B, and C are within a range that causes no practical problems.
"Test condition"
Load: 200g, Number of reciprocations: 2 times, Paper: 5 drops of water dropped on Kanakin cloth《Evaluation criteria》
A. The printed layer is not removed and the exposed area ratio of the base paper is less than 1%.
B. A slight amount of ink adheres to this paper. The printed layer is slightly removed, and the exposed area ratio of the base paper is 1% or more and less than 5%.
C. A thin layer of ink adheres to the entire surface of the paper. The printed layer is slightly removed, and the exposed area ratio of the base paper is 5% or more and less than 10%.
D. A thin layer of ink adheres to the entire surface of the paper. Most of the printing layer has been removed and the exposed area ratio of the base paper is 10% or more.

<Blocking resistance evaluation>
The obtained packaging material was cut into two pieces of 40 mm square, and the heat seal layer surface of one packaging material piece was completely overlapped with the surface protection layer surface of the other packaging material piece, and the temperature was 40 ° C. and the humidity was 80% RH. Pressure bonding was carried out under a load of 100 N/cm ² . After standing still for 24 hours, the two overlapping packaging materials were peeled off, and the peeling state of the printed layer was visually observed and evaluated based on the following criteria. Note that A, B, and C are within a range that causes no practical problems.
"Evaluation criteria"
A. The amount of transfer of the printed layer to the surface of the heat seal layer is 0 area %.
B. The amount of transfer of the printed layer to the surface of the heat seal layer is more than 0 area % and less than 10 area %.
C. The amount of transfer of the printed layer to the surface of the heat seal layer is 10 area % or more and less than 30 area %.
D. The amount of transfer of the printed layer to the surface of the heat seal layer is 30 area % or more.

<Heat sealability evaluation>
The resulting packaging material was cut into a size of 15 mm x 100 mm, bent so that the heat-sealed layer surfaces overlapped, heat-sealed using the following equipment and conditions, and both unsealed ends were fixed to a small tensile testing machine. Heat seal strength was evaluated. Note that A, B, and C are within a range that causes no practical problems.
《Heat sealing conditions》
Equipment: Heat seal tester manufactured by Tester Sangyo Co., Ltd., seal width: 10 mm from the bending part, heater temperature: 160°C, seal pressure: 2 kg/cm ² ,
Seal time: 1sec
《Heat seal strength measurement conditions》
Equipment: Intesco small tensile tester (model: IM-20), specimen width: 15 mm,
Peeling mode: 90° peeling, tensile speed: 300mm/min
"Evaluation criteria"
A. Heat seal strength is 3.5N or more.
B. Heat seal strength is 2.5N or more and less than 3.5N.
C. Heat seal strength is 1.0N or more and less than 2.5N.
D. Heat seal strength is less than 1.0N.

From the above results, Comparative Example 1 did not satisfy the total light transmittance and oxygen barrier properties because the paper base material (A) was kraft paper that did not contain resin. Furthermore, Comparative Examples 2 and 3 did not satisfy water friction resistance because the surface protective layer contained a urethane resin and a chlorinated rubber resin, respectively.
On the other hand, in Examples, the paper base material (A) contains a resin, and the surface protective layer contains a cellulose resin (a') having an average fiber diameter or an average particle diameter of less than 10 μm, so the total light transmittance, oxygen barrier property, Good water friction resistance, blocking resistance, and heat sealability. For example, in Example 1, the heat seal layer contains an acrylic resin, the thickness of the heat seal layer is 15 μm, and the resin contained in the paper base material (A) is regenerated cellulose (weight average molecular weight: 400,000). The regenerated cellulose content in 100% by mass of the paper base material (A) is 33% by mass, and the surface protective layer is made of nitrocellulose resin (weight average molecular weight: 10,000, viscosity at 25.0% solution concentration). :2 seconds) and the thickness of the surface protective layer was 4 μm, so it had excellent total light transmittance, oxygen barrier properties, water friction resistance, blocking resistance, and heat sealability.

Claims (12)

A packaging material sequentially comprising a heat seal layer, a paper base material (A), and a surface protection layer,
The paper base material (A) contains a resin (a) having an average fiber diameter or average particle diameter of less than 10 μm,
The surface protective layer contains a cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm,
The packaging material has a total light transmittance of 40% or more as measured according to JIS K 7361-1. The packaging material according to claim 1, wherein the heat seal layer contains at least one selected from the group consisting of acrylic resin and ethylene-vinyl acetate copolymer resin. The packaging material according to claim 2, wherein the heat-sealing layer contains an acrylic resin, and the acrylic resin has a glass transition temperature of 10 to 90°C. The packaging material according to claim 2, wherein the heat-sealing layer contains an ethylene-vinyl acetate copolymer resin, and the minimum film-forming temperature of the ethylene-vinyl acetate copolymer resin is 60 to 100°C. The packaging material according to claim 1, wherein the paper base material (A) contains a cellulose resin (a1) having an average fiber diameter or an average particle diameter of less than 10 μm. The total content of the cellulose resin (a1) having an average fiber diameter or average particle diameter of less than 10 μm and the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm is 0.0% by mass in 100% by mass of the packaging material. The packaging material according to claim 5, which has a content of 5 to 50% by mass. The packaging material according to claim 5, wherein the cellulose resin (a1) having an average fiber diameter or an average particle diameter of less than 10 μm is derived from viscose. The packaging material according to claim 1, wherein the surface protective layer further contains a polyamide resin. The packaging material according to claim 8, wherein the mass ratio of the cellulose resin (a') having an average fiber diameter or average particle diameter of less than 10 μm and the polyamide resin is 99:1 to 15:85. The packaging material according to claim 1, wherein the surface protective layer further contains amide wax. The packaging material according to claim 1, wherein the surface protective layer further contains a plasticizer. A packaging bag formed from the packaging material according to any one of claims 1 to 11.