JP6958755B1 - Base paper for thin-film paper and thin-film paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base paper for a thin-film deposition paper which is excellent in recyclability and can realize a thin-film deposition paper having high oxygen barrier property and water vapor barrier property. SOLUTION: The base paper for vapor-deposited paper having a clay coat layer and a resin layer on at least one surface of the paper base material in this order, and the ratio of broadleaf tree pulp to the pulp constituting the paper base material is 65% by mass. As described above, the base paper for vapor-deposited paper has a resin content of less than 9.0% by mass in the base paper for vapor-deposited paper. A vapor-deposited paper having a vapor-deposited layer on the surface of the base paper for the vapor-deposited paper on which a resin layer is provided. [Selection diagram] None

Description

The present invention relates to a base paper for a vapor-deposited paper and a vapor-deposited paper.

Conventionally, packaging materials in which a paper base material is provided with a water vapor barrier property that barriers water vapor and a gas barrier property that barriers gases other than water vapor, particularly an oxygen barrier property that barriers oxygen, are used for foods, medical products, electronic parts, etc. It is used in packaging to prevent deterioration of the quality of the contents.

Deposited paper is made by providing a vapor-deposited layer made of metal or the like on a paper base material, and by taking advantage of its glossiness, it is a label paper with excellent design such as sake and soft drinks, and a wrapping paper for confectionery. It is widely used for such purposes.

For example, in Patent Document 1, in an aluminum-deposited paper in which an aluminum-deposited layer is provided on a base paper, aluminum-deposited using a base paper whose back surface is treated so that the natural polarization potential value of the front surface of the vapor-deposited layer is within a specific range. The paper is disclosed. Further, for example, in Patent Document 2, a sealing coating layer with a polyolefin-based aqueous dispersion liquid, a thin-film film layer of an inorganic oxide, and a heat-sealing resin layer are provided on one side of thin paper having a basis weight of a specific value or less. The sequentially formed sealing sheets for PTP packaging are disclosed.

Japanese Unexamined Patent Publication No. 4-65599 Japanese Unexamined Patent Publication No. 7-223686

Although attempts have been made to form a vapor-deposited layer to improve the barrier property of the paper substrate against oxygen and water vapor as in Patent Documents 1 and 2, the aluminum-deposited paper described in Patent Document 1 and Patent Document 2 The sealed sheet for PTP packaging described in the above has a problem of poor recyclability.

Therefore, it is an object of the present invention to provide a base paper for thin-film deposition paper which is excellent in recyclability and can realize a thin-film deposition paper having high oxygen barrier property and water vapor barrier property.

The present inventors have solved the above problems by the fact that the ratio of hardwood pulp to the pulp constituting the paper base material is equal to or more than a specific value and the resin content in the base paper for vapor deposition paper is less than a specific value. I found out what I could do.
That is, the present invention relates to the following <1> to <13>.
<1> A base paper for vapor-deposited paper having a clay coat layer and a resin layer on at least one surface of the paper base material in this order, and the ratio of broadleaf tree pulp to the pulp constituting the paper base material is 65% by mass or more. The base paper for vapor-deposited paper, wherein the resin content in the base paper for vapor-deposited paper is less than 9.0% by mass.
<2> The base paper for vapor-deposited paper according to <1>, wherein the resin layer contains a water-suspendable polymer.
<3> The base paper for vapor-deposited paper according to <2>, wherein the water-suspendable polymer contained in the resin layer is a polyurethane-based resin.
<4> The polyurethane resin has an oxygen permeability of 100 mL / (m ² · day · atm) or less at 23 ° C. and 50% RH when converted into a 25 μm thick sheet, as described in <3>. Base paper for vapor-deposited paper.
<5> The polyurethane resin contains at least one selected from the group consisting of a constituent unit derived from metaxylylene diisocyanate and a constituent unit derived from hydrogenated metaxylylene diisocyanate, according to <3> or <4>. Base paper for vapor deposition paper.
<6> The base paper for vapor-deposited paper according to any one of <3> to <5>, wherein the polyurethane-based resin has a hydroxy group and the hydroxyl value of the polyurethane-based resin is 50 mgKOH / g or more.
<7> The polyurethane resin has a total content of 50 mol% or more of the constituent units derived from metaxylylene diisocyanate and the constituent units derived from hydrogenated metaxylylene diisocyanate with respect to the total amount of the constituent units derived from polyisocyanate. The base paper for vapor-deposited paper according to any one of <3> to <6>.
<8> Any one of <1> to <7>, wherein the clay coat layer contains an inorganic pigment and a binder, and the inorganic pigment has an aspect ratio of 50 or less and an average particle size of 5 μm or less. The base paper for vapor-deposited paper described in 1.
<9> The base paper for thin-film deposition paper according to <8>, wherein the inorganic pigment is kaolin.
<10> The binder contained in the clay coat layer is one or more selected from the group consisting of a styrene-butadiene resin, a styrene- (meth) acrylic resin, and an olefin-unsaturated carboxylic acid copolymer. , <8> or <9>.
<11> The base paper for thin-film deposition paper according to any one of <1> to <10>, wherein the clay coat layer and the resin layer are formed by using an aqueous medium.
<12> A vapor-deposited paper having a vapor-deposited layer on a surface provided with a resin layer of the base paper for the vapor-deposited paper according to any one of <1> to <11>.
<13> The vapor-deposited paper according to <12>, which has a base paper for thin-film deposition paper, a thin-film deposition layer, and an overcoat layer in this order.

According to the present invention, it is possible to provide a base paper for thin-film deposition paper which is excellent in recyclability and can realize a thin-film deposition paper having high oxygen barrier property and water vapor barrier property.

[Base paper for thin-film deposition paper]
The base paper for vapor-deposited paper of the present embodiment is a base paper for vapor-deposited paper having a clay coat layer and a resin layer on at least one surface of the paper base material in this order, and is a broad-leaved pulp occupying the pulp constituting the paper base material. Is 65% by mass or more, and the resin content in the base paper for vapor-deposited paper is less than 9.0% by mass. The vapor-deposited paper using the base paper for the vapor-deposited paper has a high pulp recovery rate after disintegration, excellent recyclability, and high oxygen barrier property and water vapor barrier property.

The base paper for thin-film deposition paper of the present embodiment may have a clay coat layer and a resin layer on one side of the paper base material in this order, or may have a clay coat layer and a resin layer on both sides in this order. However, from the viewpoint of production efficiency, it is preferable to have a clay coat layer and a resin layer on one side in this order.

<Paper base material>
The pulp constituting the paper base material in the present embodiment preferably contains plant-derived pulp as the main component, and wood pulp as the main component. Examples of wood pulp include hardwood pulp and softwood pulp. Examples of non-wood pulp include cotton pulp, hemp pulp, kenaf pulp, and bamboo pulp. Materials other than pulp fibers such as synthetic fibers such as rayon fibers and nylon fibers may also be blended as auxiliary paper materials as long as the effects of the present invention are not impaired.

The ratio of hardwood pulp to the pulp constituting the paper base material is 65% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and 100% by mass. It may be. When the proportion of pulp hardwood pulp constituting the paper base material is within the above range, the recyclability is excellent.

Specific examples of the paper base material used for the base paper for vapor-deposited paper of the present embodiment include bleached kraft paper, unbleached kraft paper, high-quality paper, paperboard, liner paper, coated paper, single-gloss paper, and glassin paper. Examples include Grafan paper. Among these, bleached kraft paper, unbleached kraft paper, high-quality paper, and single-gloss paper are preferable.

(Size degree)
The size of the paper base material is not particularly limited, but from the viewpoint of improving the barrier property, it is preferable to set the sizing human size according to JIS P 8122: 2004 to 1 second or more. The upper limit is not particularly limited, but is preferably 100 seconds or less, more preferably 30 seconds or less. The size of the paper substrate can be controlled by the type and content of the internal sizing agent, the type of pulp, the smoothing treatment, and the like.

Examples of the internal sizing agent include rosin type, alkyl ketene dimer type, alkenyl succinic anhydride type, styrene-unsaturated carboxylic acid type, higher fatty acid type, petroleum resin type and the like. The content of the internal sizing agent is not particularly limited, but is preferably 0 parts by mass or more and preferably 3 parts by mass or less with respect to 100 parts by mass of the pulp of the paper base material.

In addition to the internal sizing agent, other known internal additives may be added to the paper substrate. Examples of the internal additive include a filler, a paper strength enhancer, a yield improver, a pH adjuster, a drainage improver, a water resistant agent, a softener, an antistatic agent, an antifoaming agent, a slime control agent, a dye, and a pigment. And so on.

As fillers, for example, titanium dioxide, kaolin, talc, calcium carbonate (heavy calcium carbonate, light calcium carbonate), calcium sulfite, gypsum, calcined kaolin, white carbon, amorphous silica, delaminated kaolin, diatomaceous soil, carbonic acid. Examples thereof include magnesium, aluminum hydroxide, calcium hydroxide, magnesium hydroxide and zinc hydroxide.

The paper base material is obtained by making a papermaking material containing a pulp slurry as a main component.
The pulp slurry is obtained from wood or non-wood raw material chips through steps such as cooking, washing, and bleaching. The method in the cooking step, the washing step, the bleaching step, etc. is not particularly limited. The pulp slurry obtained through these steps is further beaten in the presence of water.

For paper making on a paper base material, a known wet paper machine can be appropriately selected and used.
Examples of the paper machine include a long net type paper machine, a gap former type paper machine, a circular net type paper machine, and a short net type paper machine.
The paper layer formed by the paper machine is preferably conveyed by, for example, felt and dried by a dryer. A multi-stage cylinder dryer may be used as a pre-dryer before drying the dryer.

Further, the paper base material obtained as described above may be surface-treated with a calendar to make the paper thickness and gloss profile uniform. As the calendar processing, a known calendar processing machine can be appropriately selected and used.

(Basis weight)
The basis weight of the paper substrate is not particularly limited, ^{but is preferably 20 g / m 2} or more, more preferably 30 g / m ² or more, further preferably 40 g / m ² or more, and. It is preferably 500 g / m ² or less, more preferably 400 g / m ² or less, further preferably 200 g / m ² or less, and even more preferably 100 g / m ² or less. The basis weight of the paper base material is measured in accordance with JIS P 8124: 2011.

(thickness)
The thickness of the paper substrate is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 20 μm or more, and preferably 150 μm or less, more preferably 100 μm or less, still more preferably 75 μm or less. Is. The thickness of the paper base material is measured in accordance with JIS P 8118: 2014.

(density)
From the viewpoint of moldability, the paper substrate preferably has a density of 0.5 g / cm ³ or more, more preferably 0.6 g / cm ³ or more, and 1.2 g / cm ³ or less. It is preferably 1.0 g / cm ³ or less, and more preferably 1.0 g / cm 3. The density of the paper base material is calculated from the basis weight and thickness of the paper base material measured by the above method.

(Oken type smoothness)
From the viewpoint of obtaining a uniform vapor-deposited layer, the paper substrate preferably has at least the Oken-type smoothness of the surface on which the vapor-deposited layer is provided, which is 5 seconds or longer, and more preferably 10 seconds or longer. The upper limit is not particularly limited, but is preferably 1000 seconds or less, for example. The Oken-type smoothness of the paper substrate is measured in accordance with JIS P 8155: 2010.

(75 ° gloss)
From the viewpoint of printability, the paper base material preferably has a 75 ° glossiness of 5% or more, more preferably 10% or more, and preferably 80% or less. The 75 ° glossiness of the paper substrate is measured in accordance with JIS P 8142: 2005.

(Canada Standard Water Separation (CSF))
The Canadian standard freshness (CSF) of the pulp constituting the dissociated paper base material is preferably 800 mL or less, more preferably 500 mL or less, from the viewpoint of improving the barrier property. The lower limit is not particularly limited, but from the viewpoint of ease of papermaking, it is preferably 150 mL or more, more preferably 250 mL or more. The CSF (dissociated CSF) of the pulp constituting the dissociated paper base material is measured in accordance with JIS P 8220: 2012, and the pulp slurry obtained by dissociation is measured in accordance with JIS P 811-2: 2012. Will be done. As a method for beating the pulp to adjust the disaggregation CSF, a known method can be used.

<Clay coat layer>
The base paper for vapor-deposited paper of the present embodiment has a clay coat layer between the paper base material and a resin layer described later. As a result, the paper base material can be sealed and smoothed, and a flatter resin layer is formed. ..

The clay coat layer preferably contains an inorganic pigment and a binder, and more preferably is mainly composed of an inorganic pigment and a binder. In addition, "the clay coat layer is mainly composed of an inorganic pigment and a binder" means that the total content of the inorganic pigment and the binder in the clay coat layer is, for example, 50% by mass or more, preferably 60% by mass or more. It means that it is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The upper limit is not particularly limited, but is 100% by mass or less. The clay coat layer may further contain any component in addition to the inorganic pigment and the binder.

(Inorganic pigment)
The inorganic pigment contained in the clay coat layer is not particularly limited, and examples thereof include kaolin, talc, and mica, and kaolin is preferable.
The content of the inorganic pigment in the clay coat layer is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, and 98% by mass or less. Is more preferable, 90% by mass or less is more preferable, and 85% by mass or less is further preferable.

≪Aspect ratio≫
The aspect ratio of the inorganic pigment is preferably 50 or less from the viewpoint of forming a uniform and smooth resin layer and from the viewpoint of finely scattering the inorganic pigment in the clay coat layer to improve the dissociation property of the base paper for vapor-deposited paper at the time of recovery. The lower limit is not particularly limited, but is preferably 1 or more. The aspect ratio can be measured by observation with an electron microscope or X-ray diffraction measurement.

≪Average particle size≫
The average particle size of the inorganic pigment is preferably 5 μm or less, preferably 3 μm or less, from the viewpoint of forming a uniform and smooth resin layer and finely scattered in the clay coat layer to improve the dissociation property of the base paper for vapor-deposited paper at the time of recovery. The following is more preferable, and 1 μm or less is further preferable. The lower limit is not particularly limited, but is preferably 0.05 μm or more. The average particle size means the median size (d50) measured by the laser diffraction / scattering type particle size distribution measurement.

(binder)
The binder contained in the clay coat layer is not particularly limited, but is styrene-butadiene resin; (meth) acrylic (co) polymer; styrene- (meth) acrylic resin; ethylene-acrylic acid copolymer, ethylene. -Olefin-unsaturated carboxylic acid-based copolymers such as methacrylic acid copolymers; and the like; and are composed of styrene-butadiene-based resins, styrene- (meth) acrylic-based resins, and olefin-unsaturated carboxylic acid-based copolymers. It is preferably one or more selected from the group, and more preferably one or more selected from the group consisting of styrene- (meth) acrylic resin and ethylene- (meth) acrylic acid copolymer. It is more preferable that the amount is one or more selected from the based resin and the ethylene-acrylic acid copolymer.
The (meth) acrylic (co) polymer is a (co) polymer of one or more monomers selected from (meth) acrylic acid and (meth) acrylic acid ester. The (meth) acrylic acid ester is not particularly limited, but is preferably an alkyl ester having 1 to 12 carbon atoms of the (meth) acrylic acid.
The styrene- (meth) acrylic resin is a copolymer of styrene and at least one monomer selected from (meth) acrylic acid and (meth) acrylic acid ester, and is preferably styrene-acrylic. It is a based resin, more preferably a styrene-acrylic acid copolymer or a styrene-acrylic acid ester copolymer.
The content of the binder in the clay coat layer is preferably 2% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, and 50% by mass or less. It is preferably 40% by mass or less, and more preferably 30% by mass or less.

The amount of the clay coat layer applied is not particularly limited, but the solid content ^{is preferably 5 g / m 2} or more, more preferably 7 g / m ² or more, and 30 g / m ² or less. It is preferably 20 g / m ² or less, and more preferably 20 g / m 2 or less.
The method for forming the clay coat layer is not particularly limited, but a method of forming the clay coat layer by applying a dispersion liquid containing an inorganic pigment and a resin binder onto a paper base material and drying it is preferable. As the dispersion liquid containing the inorganic pigment and the resin binder, those using an aqueous medium such as an aqueous dispersion liquid as a solvent are preferable.

<Resin layer>
The base paper for thin-film deposition paper of the present embodiment has a resin layer arranged on the clay coat layer. By providing the resin layer, the adhesion between the vapor-deposited layer of the vapor-deposited paper and the paper base material is improved, and the barrier property is improved. Further, since the resin layer has an oxygen barrier property and a water vapor barrier property, it also has a function of improving the barrier property when it is made into a vapor-deposited paper.

The resin layer preferably contains a water-suspendable polymer, and more preferably mainly contains a water-suspendable polymer. In addition, "the resin layer mainly contains a water-suspendable polymer" means that the content of the water-suspendable polymer in the resin layer is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably. It means that it is 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The upper limit is not particularly limited, but is 100% by mass or less. The resin layer may further contain any component in addition to the water-suspendable polymer.

(Water-suspendable polymer)
The water-suspendable polymer contained in the resin layer is not particularly limited, but is an alkyd resin; (meth) acrylic (co) polymer, styrene- (meth) acrylic resin; ethylene-acrylic acid copolymer, Olefin-unsaturated carboxylic acid-based copolymers such as ethylene-methacrylic acid copolymer; vinyl alcohol-based resins such as polyvinyl alcohol and ethylene vinyl alcohol copolymers (ethylene-modified polyvinyl alcohol); cellulose-based resins; polyurethane-based resins; Examples include polyester resins. Among these, one or more selected from vinyl alcohol-based resin, polyurethane-based resin and polyester-based resin is preferable, and one or more selected from polyvinyl alcohol-based resin and polyurethane-based resin from the viewpoint of further improving oxygen barrier properties. Is more preferable, and a polyurethane-based resin is further preferable.

≪Polyurethane resin≫
The polyurethane-based resin contained in the resin layer is not particularly limited, and for example, it is more preferable that the polyurethane-based resin can be prepared into one or more selected from the group consisting of polyurethane-based resin dispersions and emulsions, and polyurethane-based resin dispersions. It is more preferable that it can be prepared into an emulsion or an emulsion, and even more preferably it can be prepared into a polyurethane-based resin dispersion.
The polyurethane-based resin contained in the resin layer preferably contains at least one selected from the group consisting of a structural unit derived from metaxylylene diisocyanate and a structural unit derived from hydrogenated metaxylylene diisocyanate. When the polyurethane resin contains at least one of the constituent units derived from metaxylylene diisocyanate and the constituent units derived from hydrogenated metaxylylene diisocyanate, the constituent units derived from metaxylylene diisocyanate and the constituent units derived from metaxylylene diisocyanate with respect to the total amount of the constituent units derived from polyisocyanate. The total content of the constituent units derived from hydrogenated metaxylylene diisocyanate is preferably 50 mol% or more. Such a polyurethane-based resin exhibits a high cohesive force due to a hydrogen bond and a stacking effect between xylylene groups, and thus has an excellent gas barrier property. The above content can be identified using a known analytical method such as ^{1 H-NMR.}
The polyurethane resin may have a hydroxy group, and the hydroxyl value of the polyurethane resin is preferably 50 mgKOH / g or more, more preferably 100 mgKOH / g or more, still more preferably 150 mgKOH / g or more. The upper limit is not particularly limited, but is preferably 1000 mgKOH / g or less, more preferably 800 mgKOH / g or less, and further preferably 600 mgKOH / g or less. When the hydroxyl value of the polyurethane resin is within the above range, the oxygen barrier property is excellent, which is preferable.

-Oxygen permeability-
The polyurethane resin contained in the resin layer preferably has an oxygen permeability of 100 mL / (m ² · day · atm) or less at 23 ° C. and 50% RH when converted into a sheet having a thickness of 25 μm, preferably 50 mL. It is more preferably less than / (m ² · day · atm), more preferably 25 mL / (m ² · day · atm) or less, and more preferably 10 mL / (m ² · day · atm) or less. Even more preferable. In the present specification, the oxygen permeability is measured using an oxygen permeability measuring device (OX-TRAN2 / 20 manufactured by MOCON) under the conditions of 23 ° C. and 50% RH.

-Glass transition temperature-
The glass transition temperature of the polyurethane resin contained in the resin layer is important to have high film forming property from the viewpoint of protecting the vapor-deposited layer of the vapor-deposited paper described later, and is preferably 150 ° C. or lower, preferably 140 ° C. The temperature is more preferably 135 ° C. or lower, and particularly preferably 135 ° C. or lower. The lower limit of the glass transition temperature of the polyurethane resin is not particularly limited, but is preferably 50 ° C. or higher. The glass transition temperature is measured according to JIS K 7122: 2012.

As the polyurethane-based resin, a synthetic product may be used, and examples thereof include the polyurethane-based resin described in International Publication No. 2015/016069.
As the polyurethane-based resin, a commercially available product may be used. For example, "Takelac W-based (trade name)", "Takelac WPB-based (trade name)", and "Takelac WS-based (trade name)" manufactured by Mitsui Chemicals, Inc. may be used. ) ”, And specifically, Takelac WPB-341 is exemplified. Other commercially available products include "HPU W-003" (hydroxyl value 235 mgKOH / g) manufactured by Dainichiseika Kogyo Co., Ltd.

The coating amount of the resin layer is not particularly limited, but the solid content ^{is more preferably 0.1 g / m 2} or more, more preferably 1 g / m ² or more, and 10 g / m ² or less. It is preferably 5 g / m ² or less, and more preferably 5 g / m 2.
The method for forming the resin layer is not particularly limited, but it is preferable to apply an aqueous solution of a water-suspendable polymer or an aqueous medium such as an aqueous dispersion and dry it to form the resin layer.

[Characteristics of base paper for thin-film deposition paper]
<Resin content>
The resin content in the base paper for vapor-deposited paper of the present embodiment is less than 9.0% by mass and 8.5% by mass or less from the viewpoint of realizing a vapor-deposited paper having excellent recyclability and high oxygen barrier property. Is preferable, 8.0% by mass or less is more preferable, and 7.5% by mass or less is further preferable. The lower limit is not particularly limited, but is preferably 1.0% by mass or more. The resin content of the base paper for vapor-deposited paper is the resin content including the binder of the clay coat layer and the resin of the resin layer.

<Thickness>
The thickness of the base paper for thin-film deposition paper of the present embodiment is preferably 10 μm or more, more preferably 30 μm or more, preferably 100 μm or less, and more preferably 80 μm or less.

The base paper for vapor-deposited paper of the present embodiment has a ratio of broad-leaved tree pulp in the pulp constituting the paper base material to a specific value or more, and the resin content in the base paper for vapor-deposited paper is less than a specific value. It is possible to realize a vapor-deposited paper having excellent recyclability and a high oxygen barrier property.

The method for producing the base paper for vapor-deposited paper of the present embodiment is not limited, but the clay coat layer containing an inorganic pigment and a binder so as to have a clay coat layer and a resin layer on at least one surface of the paper base material in this order. It is preferable that the coating liquid for a resin layer containing a water-suspendable polymer is applied and dried after the coating liquid for coating is applied and dried.

[Thin-film deposition paper]
The vapor-deposited paper of the present embodiment has a vapor-deposited layer on the surface of the base paper for vapor-deposited paper on which the resin layer is provided.

<Thin-film deposition layer>
The vapor-deposited layer is at least one of a layer made of metal and a layer made of ceramic. That is, the vapor deposition layer may be any of a metal layer, a ceramic layer, and a laminate of a metal layer and a ceramic layer. When the vapor deposition layer is a laminate of a metal layer and a ceramic layer, the metal layer may be on the resin layer side of the base paper for vapor deposition paper, and the ceramic layer is on the resin layer side of the base paper for vapor deposition paper. It may be, and is not particularly limited.

The vapor-deposited layer may be a layer made of metal, a layer made of ceramic, or a laminate thereof, but a layer made of metal is preferable.
When the vapor-deposited layer is a layer made of metal, specific examples of the metal include aluminum and titanium. These may be used individually by 1 type, and may be used in combination of 2 or more type. Among these, aluminum is preferable.
When the vapor-deposited layer is a layer made of ceramic, specific examples of the ceramic include silicon oxide, titanium oxide, aluminum oxide and the like. These may be used individually by 1 type, and may be used in combination of 2 or more type. Among these, silicon oxide and aluminum oxide are preferable.
That is, the vapor-deposited layer is more preferably any of a layer made of aluminum, a layer made of silicon oxide, a layer made of titanium oxide, a layer made of aluminum oxide, and a laminate thereof, and the layer made of aluminum and oxidation. Any of a layer made of silicon, a layer made of aluminum oxide, and a laminate thereof is more preferable, and a layer made of aluminum is particularly preferable.

(thickness)
The thickness of the thin-film deposition layer is preferably 1 nm or more, more preferably 2 nm or more, further preferably 3 nm or more, preferably 1000 nm or less, and more preferably 500 nm or less. It is preferably 100 nm or less, and more preferably 100 nm or less.
From the viewpoint of barrier properties, the thickness of the thin-film deposition layer is preferably 10 nm or more, more preferably 25 nm or more, and more preferably 80 nm or less, more preferably 70 nm. ..
Further, the thickness of the thin-film deposition layer is preferably 4 nm or more, more preferably 5 nm or more, and preferably 100 nm or less, preferably 70 nm, from the viewpoint of adhesion to other layers and cost. It is more preferably less than or equal to, and particularly preferably 60 nm or less.

<Overcoat layer>
The vapor-deposited paper of the present embodiment preferably has an overcoat layer containing a polyurethane-based resin on the vapor-deposited layer. The thin-film vapor deposition paper of the present embodiment has a certain barrier property by having a thin-film deposition layer, but the oxygen barrier property can be further improved by having an overcoat layer containing a polyurethane resin on the thin-film deposition layer. Further, the vapor deposition layer is not easily damaged by processing such as bending, and even if it is damaged, the oxygen barrier property can be ensured by the overcoat layer, and excellent oxygen barrier property can be maintained.

Examples of the polyurethane-based resin as the binder contained in the overcoat layer include those exemplified as the polyurethane-based resin of the resin layer, and for example, one or more kinds selected from the group consisting of polyurethane-based resin dispersions and emulsions can be prepared. It is more preferable that it can be prepared into a polyurethane-based resin dispersion or an emulsion, and it is even more preferable that it can be prepared into a polyurethane-based resin dispersion.
The polyurethane resin contained in the overcoat layer preferably contains at least one selected from the group consisting of a constituent unit derived from metaxylylene diisocyanate and a constituent unit derived from hydrogenated metaxylylene diisocyanate. When the polyurethane resin contains at least one of the constituent units derived from metaxylylene diisocyanate and the constituent units derived from hydrogenated metaxylylene diisocyanate, the constituent units derived from metaxylylene diisocyanate and the constituent units derived from metaxylylene diisocyanate with respect to the total amount of the constituent units derived from polyisocyanate. The total content of the constituent units derived from hydrogenated metaxylylene diisocyanate is preferably 50 mol% or more. Such a polyurethane-based resin exhibits a high cohesive force due to a hydrogen bond and a stacking effect between xylylene groups, and thus has an excellent gas barrier property.
The polyurethane resin may have a hydroxy group, and the hydroxyl value of the polyurethane resin is preferably 50 mgKOH / g or more, more preferably 100 mgKOH / g or more, still more preferably 150 mgKOH / g or more. The upper limit is not particularly limited, but is preferably 1000 mgKOH / g or less, more preferably 800 mgKOH / g or less, and further preferably 600 mgKOH / g or less. When the hydroxyl value of the polyurethane resin is within the above range, the oxygen barrier property is excellent, which is preferable.

(Oxygen permeability)
The polyurethane resin contained in the overcoat layer preferably has an oxygen permeability of 100 mL / (m ² · day · atm) or less at 23 ° C. and 50% RH when converted into a 25 μm thick sheet, preferably 50 mL. It is more preferably less than / (m ² · day · atm), more preferably 25 mL / (m ² · day · atm) or less, and more preferably 10 mL / (m ² · day · atm) or less. Even more preferable.

The polyurethane-based resin as the binder contained in the overcoat layer may be the same type as the polyurethane-based resin contained in the resin layer of the base paper for vapor-deposited paper described above, or may be of a different type, but is the same. It is preferable that the type is. Further, as the resin layer of the base paper for the vapor-deposited paper, a synthetic product or a commercially available product listed as usable may be used.

The content of the polyurethane resin in the overcoat layer is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 99% by mass or more. Is. The upper limit is not particularly limited, but is 100% by mass or less.

The overcoat layer may contain other resins and additives as long as the effects of the present invention are not impaired.
Examples of the additive include surfactants, pigments, antioxidants, antistatic agents, dyes, plasticizers, lubricants, mold release agents and the like. When the polyurethane resin is used as the aqueous dispersion, it is preferable to use a dispersant in order to disperse the polyurethane resin in an aqueous medium and obtain a uniform overcoat layer film.

The coating amount of the overcoat layer ^{is preferably 0.1 g / m 2} or more, more preferably 0.2 g / m ² or more, and 0.3 g / m ² or more in terms of solid content. it is particularly preferred and preferably at 10 g / ^{m 2} or less, and particularly preferably more preferably 7 g / ^{m 2} or less, 4g / ^{m 2} or less.

The thickness of the overcoat layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, particularly preferably 0.3 μm or more, and preferably 10 μm or less. It is more preferably 7 μm or less, and particularly preferably 4 μm or less. When the thickness of the overcoat layer is 0.1 μm or more and 10 μm or less, the protection against the vapor-deposited layer is improved, the paper is excellent in dissociation during recycling, and the recyclability is also excellent.

The method for forming the overcoat layer is not particularly limited, but it is preferable to apply an aqueous solution of a polyurethane resin or an aqueous medium such as an aqueous dispersion and dry it to form the overcoat layer.

In the vapor-deposited paper of the present embodiment, the overcoat layer may be the outermost layer. Even if the overcoat layer is the outermost layer, it does not impair the design of the vapor-deposited layer having a glossy feeling.
When the vapor deposition layer is provided on both sides, an overcoat layer may be provided on one side or both sides thereof. Among these, it is preferable to have an overcoat layer on one side. By having an overcoat layer on one side, production efficiency is excellent.

[Manufacturing method of thin-film deposition paper]
The method for producing the vapor-deposited paper of the present embodiment is not limited, but the surface on which the resin layer of the base paper for the vapor-deposited paper having the clay coat layer and the resin layer in this order is provided on at least one surface of the paper base material. , A step of depositing at least one of metal and ceramic to form a vapor deposition layer, and a step of applying a coating liquid for an overcoat layer on the vapor deposition layer and drying it to form an overcoat layer. It is preferable to include it.

As a method for depositing metal or ceramic, a method of vacuum-depositing metal or ceramic directly on the surface of the resin layer of the base paper for vapor deposition paper is preferable.

It is preferable to form the overcoat layer directly on the vapor-deposited layer from the viewpoint of efficiently protecting the vapor-deposited layer and enhancing the barrier property.
As a method for forming the overcoat layer, it is preferable to apply a liquid for the overcoat layer and dry the overcoat layer.
By applying a coating liquid for an overcoat layer to form an overcoat layer, an overcoat layer having a relatively thin film of 10 μm or less can be formed. By forming such a relatively thin overcoat layer, excellent dissociation property can be imparted, and a vapor-deposited paper having excellent recyclability can be obtained.

Examples of the coating liquid for the overcoat layer used here include a solution using an organic solvent that dissolves the polyurethane-based resin, a dispersion liquid that uses an organic solvent that disperses the polyurethane-based resin, and a dispersion liquid that uses an aqueous medium. Therefore, a dispersion liquid using an aqueous medium is preferable from the viewpoint of coatability and environmental load.

Examples of the method for applying the coating liquid for the overcoat layer include a bar coating method, a blade coating method, a squeeze coating method, an air knife coating method, a roll coating method, a gravure coating method, a transfer coating method, and the like. Or a coating machine such as a slit die coater may be used.
The coated vapor-deposited paper coated with the coating liquid for the overcoat layer can be dried to remove the organic solvent or the aqueous medium, and a vapor-deposited paper having the overcoat layer on the vapor-deposited layer can be obtained.

Further, a heat seal layer containing a thermoplastic resin may be formed on the overcoat layer.
Examples of the method for forming the heat seal layer include coating a thermoplastic resin solution or a thermoplastic resin dispersion liquid and drying the mixture, extruding and laminating the layers. Among these, it is preferable to apply a thermoplastic resin solution or a thermoplastic resin dispersion liquid and dry the obtained product.

The thermoplastic resin solution or thermoplastic resin dispersion used here is a solution using an organic solvent that dissolves the thermoplastic resin, a dispersion liquid that uses an organic solvent that disperses the thermoplastic resin, or a dispersion liquid that uses an aqueous medium. From the viewpoint of coatability and environmental load, a dispersion using an aqueous medium is preferable.

Examples of the method for applying the thermoplastic resin solution or the thermoplastic resin dispersion include a bar coating method, a blade coating method, a squeeze coating method, an air knife coating method, a roll coating method, a gravure coating method, and a transfer coating method. , A coating machine such as a fountain coater or a slit die coater may be used.
The coated vapor-deposited paper coated with the thermoplastic resin solution or the thermoplastic resin dispersion is dried to remove the organic solvent or the aqueous medium, and a coated vapor-deposited paper having a heat-sealing layer on the overcoat layer is obtained. Can be done.
The thickness of the heat seal layer is not particularly limited, but is preferably 1 μm or more and less than 15 μm. If it is 1 μm or more, sufficient heat sealability can be ensured. Further, if it is less than 15 μm, dissociability can be imparted, and a vapor-deposited paper having excellent recyclability can be obtained.

<Physical characteristics of thin-film deposition paper>
(thickness)
The thickness of the vapor-deposited paper of the present embodiment is preferably 20 μm or more, more preferably 50 μm or more, preferably 200 μm or less, and more preferably 150 μm or less. The thickness of the vapor-deposited paper is measured in accordance with JIS P 8118: 2014.

(Oxygen permeability)
The oxygen permeability of the vapor-deposited paper of the present embodiment at 23 ° C. and 50% RH ^{is preferably 1.0 mL / (m 2} · day · atm) or less, and 0.5 mL / (m ² · day · atm). by more preferably less (the lower ^{limit: 0mL / (m 2 · day} · atm)). The oxygen permeability of the vapor-deposited paper is measured by the method described in Examples.

(Moisture vapor transmission rate)
The water vapor transmission rate of the vapor-deposited paper of the present embodiment at 40 ° C. and 90% RH ^{is preferably 1.0 g / (m 2} · day) or less, and is 0.7 g / (m ² · day) or less. Is more preferable (lower limit: 0 g / (m ² · day)). The water vapor transmission rate of the vapor-deposited paper is measured by the method described in the examples.

(Pulp recovery rate after re-dissolution)
The pulp recovery rate of the vapor-deposited paper of the present embodiment after re-dissolution is preferably 72% or more, more preferably 75% or more, and further preferably 77% or more. The pulp recovery rate after re-dissolution of the vapor-deposited paper is measured by the method described in Examples.

The vapor-deposited paper of the present embodiment can be suitably used as a packaging material for foods such as coffee, confectionery, milk, pharmaceuticals, medical products, electronic parts, etc. by utilizing the above-mentioned excellent oxygen barrier property, and is recyclable. Also excellent.

The features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limited by the specific examples shown below.

[Analysis and evaluation]
The following analysis and evaluation were performed on the base paper and the vapor-deposited paper for the vapor-deposited paper of Examples and Comparative Examples.

<Basis weight>
The basis weight of the paper substrate was measured according to JIS P 8124: 2011.

<Thickness>
The thicknesses of the paper substrate, the base paper for the vapor-deposited paper, the vapor-deposited layer, and the overcoat layer were measured according to JIS P 8118: 2014.

<Density>
The density of the paper substrate was calculated from the basis weight and thickness of the paper substrate measured by the method described above.

<Oken type smoothness>
The Oken-type smoothness of the paper substrate was measured according to JIS P 8155: 2010.

<75 ° glossiness>
The 75 ° glossiness of the paper substrate was measured according to JIS P 8142: 2005.

<Canada Standard Water Separation (CSF)>
The CSF of the pulp constituting the dissociated paper base material was measured according to JIS P 8220: 2012, and the pulp slurry obtained by dissociation was measured according to JIS P 811-2: 2012.

<Aspect ratio>
The aspect ratio of the inorganic pigment was set to a magnification in which about 20 to 30 inorganic pigments were contained in the screen using an electron microscope, and the thickness and length of each inorganic pigment in the screen were measured. Then, with n = 20, the average value of the obtained thickness is calculated to be the thickness (average thickness) and length (average length) of the inorganic pigment, and the average length is divided by the average thickness. Asked by doing.

<Average particle size>
The average particle size of the inorganic pigment was measured with a laser diffraction / scattering type particle size distribution measuring device (Microtrac EX3300II manufactured by Microtrac Bell Co., Ltd.).

<Oxygen permeability>
(Polyurethane resin)
The oxygen permeability at 23 ° C. and 50% RH when converted to a 25 μm thick sheet of polyurethane resin was 23 ° C. and 50% using an oxygen permeability measuring device (OX-TRAN2 / 20 manufactured by MOCON). It was measured under the condition of RH.
(Thin-film deposition paper)
The oxygen permeability of the vapor-deposited paper was measured under the conditions of 23 ° C. and 50% RH using an oxygen permeability measuring device (OX-TRAN2 / 20 manufactured by MOCON). The lower the oxygen permeability value, the better the oxygen barrier property.

<Glass transition temperature>
The glass transition temperature of the polyurethane resin was measured according to JIS K 7122: 2012.

<Moisture vapor transmission rate>
According to JIS Z 0208: 1976 (cup method) B method (temperature 40 ° C ± 0.5 ° C, relative humidity 90% ± 2%), the overcoat layer of the vapor-deposited paper or the vapor-deposited layer of the vapor-deposited paper is inside (low). The vapor permeability was measured by arranging it so as to come to the humidity side). The lower the value of water vapor transmission rate, the better the water vapor barrier property.

<Pulp recovery rate after re-dissolution>
A thin-film film having an absolute dry mass of 30 g was manually torn into 3 to 4 cm squares and immersed in tap water at 20 ° C. overnight. After diluting the vapor-deposited paper to a concentration of 2.5%, it was disintegrated for 20 minutes at a rotation speed of 3000 rpm using a TAPPI standard disintegrator (manufactured by Kumagai Riki Co., Ltd.). The obtained pulp slurry was applied to a flat screen (manufactured by Kumagai Riki Co., Ltd.) on which a screen plate of 6 cuts (slit width: 0.15 mm) was set, and was carefully selected in a water stream of 8.3 L / min. The undissociated material remaining on the screen plate was recovered, dried in an oven at 105 ° C., and the mass was measured, and the pulp recovery rate was calculated from the following formula.
Pulp recovery rate (%) = [absolute dry mass (g) of vapor-deposited paper used for the test-absolute dry mass (g) of undissolved material] / absolute dry mass (g) x 100 of the vapor-deposited paper used for the test

[Example 1]
<Base paper for thin-film deposition paper>
80 parts by mass (solid content) of kaolin (manufactured by IMERYS, Contour Xtreme, aspect ratio: 33, average particle size: 0.26 μm) dispersed in water so as to have a solid content concentration of 40% as an inorganic pigment, and styrene as a binder. -A water-based emulsion of an acrylic resin (JONCRYL HSL-9012 manufactured by BASF) was mixed with 20 parts by mass (solid content) to prepare a coating liquid for a clay coat layer having a solid content concentration of 40% by mass. Single gloss paper (manufactured by Oji Ftex Co., Ltd., broadleaf pulp compounding ratio: 100% by mass, basis weight: 50 g / m ² , thickness: 60 μm, density: 0.83 g / m ³ , size degree: 9 seconds, one The coating liquid for clay coat layer is applied to the glossy surface of the Oken type smoothness of the surface: 499 seconds and the Oken type smoothness of the other surface: 15 seconds) using a Mayer bar, and 1 at 120 ° C. It was dried for a minute to form a clay coat layer (coating amount: 12 g / m ² , thickness 4.6 μm). Next, on the clay coat layer, a polyurethane resin dispersion (manufactured by Mitsui Chemicals, Inc., Takelac WPB-341, oxygen permeability at 23 ° C. and 50% RH when converted to a 25 μm thick sheet: 2.0 mL ^{/ (m 2 · day · atm} ), the glass transition temperature of the 130 ° C.) was applied by means of a Mayer bar and dried for 1 minute at 120 ° C., the resin layer (coating amount: 2 g / ^{m 2,} thickness 2 μm) was formed, and a base paper for vapor deposition paper having a thickness of 67 μm was obtained. ^{When 1} H-NMR measurement was performed on the polyurethane resin, the content of the constituent units derived from metaxylylene diisocyanate was 50 mol% or more with respect to the total amount of the constituent units derived from polyisocyanate.
<Thin-film deposition paper>
An aluminum vapor deposition layer (thickness: 50 nm) is formed on the resin layer of the base paper for vapor deposition paper, and a polyurethane resin dispersion (Mitsui Chemicals Co., Ltd., Takelac WPB-341, 25 μm thickness) is further formed on the vapor deposition layer. oxygen permeability at 23 ° C. and 50% RH when converted to ^{sheet: 2.0mL / (m 2 · day} · atm), the glass transition temperature of the 130 ° C.) was applied by means of a Meyer bar, 120 ° C. To form an overcoat layer (coating amount: 0.5 g / m ² , thickness: 0.5 μm) for 1 minute, a thin-film film was obtained.

[Example 2]
Paper base material is single gloss paper (manufactured by Oji Materia Co., Ltd., broadleaf pulp compounding ratio: 70% by mass, basis weight: 60 g / m ² , thickness: 74 μm, density: 0.81 g / m ³ , size degree: 6 seconds , Oken-type smoothness on one surface: 163 seconds, Oken-type smoothness on the other side: 10 seconds), and a base paper for vapor deposition and a vapor-deposited paper were obtained in the same manner as in Example 1.

[Example 3]
Paper base material is single gloss paper (manufactured by Oji F-Tex Co., Ltd., broadleaf pulp compounding ratio: 100% by mass, basis weight: 40 g / m ² , thickness: 48 μm, density: 0.83 g / m ³ , size degree: 3 A base paper for vapor deposition and a vapor-deposited paper were obtained in the same manner as in Example 1 except that the smoothness of one surface was set to 386 seconds and the smoothness of the other surface was set to 12 seconds. ..

[Comparative Example 1]
Exposed paper base material Kraft paper (manufactured by Oji Materia Co., Ltd., broadleaf pulp compounding ratio: 60% by mass, basis weight: 50 g / m ² , thickness: 67 μm, density: 0.78 g / m ³ , size degree: 15 seconds , Oken-type smoothness on one side: 70 seconds, Oken-type smoothness on the other side: 75 seconds), and a base paper for vapor-deposited paper and a vapor-deposited paper were obtained in the same manner as in Example 1.

[Comparative Example 2]
A base paper for vapor-deposited paper and a vapor-deposited paper were obtained in the same manner as in Example 1 except that the coating amount of the resin layer was 5 g / m ^2.

[Comparative Example 3]
67 parts by mass of kaolin (IMERYS, BARRISURF HX, aspect ratio: 100, average particle size: 9.0 μm) as an inorganic pigment, and an ethylene-acrylic acid copolymer as a binder (Zyxen AC, manufactured by Sumitomo Seika Co., Ltd.) A coating liquid for a clay coat layer having a solid content concentration of 40% by mass was prepared by mixing with 33 parts by mass, and an ethylene-modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., EXCEVAL AQ-4104) was added to the water-suspendable polymer of the resin layer. ), And a base paper for vapor-deposited paper and a vapor-deposited paper were obtained in the same manner as in Example 1 except that the coating amount of the resin layer was 3 g / m ^2.

[Comparative Example 4]
Exposed paper base material Kraft paper (manufactured by Oji Materia Co., Ltd., broadleaf pulp compounding ratio: 60% by mass, basis weight: 50 g / m ² , thickness: 67 μm, density: 0.78 g / m ³ , size degree: 15 seconds , Oken-type smoothness on one side: 70 seconds, Oken-type smoothness on the other side: 75 seconds), and a base paper for vapor-deposited paper and a vapor-deposited paper were obtained in the same manner as in Comparative Example 3.

It can be seen that the vapor-deposited papers of Examples 1 to 3 have a higher pulp recovery rate after re-dissolution as compared with the vapor-filmed papers of Comparative Examples 1 to 4, and are excellent in recyclability. Further, it can be seen that the vapor-deposited papers of Examples 1 to 3 have lower oxygen permeability and water vapor permeability than the vapor-deposited papers of Comparative Examples 1 to 4, and have high oxygen barrier property and water vapor barrier property.

The base paper for vapor-deposited paper of the present invention can be suitably used as a packaging material for foods such as coffee, confectionery, milk, pharmaceuticals, medical products, electronic parts, etc. by utilizing its excellent oxygen barrier property and water vapor barrier property. It is also excellent in recyclability and is very useful.

Claims (12)

A base paper for thin-film deposition paper, which has a clay coat layer and a resin layer in this order on at least one surface of a paper substrate, for forming a thin-film deposition layer by vapor deposition.
The ratio of hardwood pulp to the pulp constituting the paper base material is 65% by mass or more.
The resin content in the base paper for deposition paper Ri der less than 9.0 wt%,
The clay coat layer comprises an inorganic pigment and a binder, wherein the inorganic pigment is an aspect ratio of 50 or less, and an average particle diameter of Ru der following 1 [mu] m, a base paper for metallized paper. The base paper for vapor-deposited paper according to claim 1, wherein the resin layer contains a water-suspendable polymer. The base paper for vapor-deposited paper according to claim 2, wherein the water-suspendable polymer contained in the resin layer is a polyurethane-based resin. The vapor-deposited paper according to claim 3, ^{wherein the polyurethane-based resin has an oxygen permeability of 100 mL / (m 2} · day · atm) or less at 23 ° C. and 50% RH when converted into a sheet having a thickness of 25 μm. Base paper. The base paper for vapor-deposited paper according to claim 3 or 4, wherein the polyurethane-based resin contains at least one selected from the group consisting of a structural unit derived from metaxylylene diisocyanate and a structural unit derived from hydrogenated metaxylylene diisocyanate. .. The base paper for vapor-deposited paper according to any one of claims 3 to 5, wherein the polyurethane-based resin has a hydroxy group and the hydroxyl value of the polyurethane-based resin is 50 mgKOH / g or more. 3. The polyurethane resin has a total content of 50 mol% or more of the constituent units derived from metaxylylene diisocyanate and the constituent units derived from hydrogenated metaxylylene diisocyanate with respect to the total amount of the constituent units derived from polyisocyanate. The base paper for vapor-deposited paper according to any one of Items to 6. The base paper for thin-film deposition paper according to any one of claims 1 to 7, wherein the inorganic pigment is kaolin. The claim that the binder contained in the clay coat layer is at least one selected from the group consisting of a styrene-butadiene resin, a styrene- (meth) acrylic resin, and an olefin-unsaturated carboxylic acid copolymer. The base paper for vapor-deposited paper according to any one of 1 to 8. The base paper for thin-film deposition paper according to any one of claims 1 to 9 , wherein the clay coat layer and the resin layer are formed by using an aqueous medium. A vapor-deposited paper having a vapor-deposited layer on a surface provided with a resin layer of the base paper for the vapor-deposited paper according to any one of claims 1 to 10. The vapor-deposited paper according to claim 11 , which has a base paper for a vapor-deposited paper, a vapor-deposited layer, and an overcoat layer in this order.