JP2015027893A - Packaging material for paper container and paper container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide packaging material for a paper container having an excellent gas barrier property and manufactured at a low cost, and the paper container using the same.SOLUTION: A packaging material for a paper container is made of layered material 10. The layered material 10 includes: an outermost layer 11 made of polyethylene; a paper-made base material layer 12 having a rough surface on both sides; a smoothed layer 13 provided on the paper-made base material layer 12; an adhesive layer 14 provided on the smoothed layer 13; and an innermost layer 15 made of polyethylene and provided on the adhesive layer 14. The smoothed layer 13 smooths the rough surfaces of the paper-made base material layer 12. The adhesive layer 14 consists mainly of an epoxy resin composition made of epoxy resin and an epoxy resin hardening agent, and has a gas barrier property.

Description

  The present invention relates to a paper container packaging material and a paper container, and more particularly to a paper container packaging material and a paper container that are excellent in gas barrier properties and can achieve cost reduction.

  Conventionally, packaging materials for paper containers have been used for producing paper containers. Such a packaging material for a paper container is made of, for example, the following laminated material.

(1) PE / paper / PE
(2) PE / paper / LLDPE / PE
(3) PE / paper / PE / gas barrier layer / PE
Among these, the packaging material using the laminated material (1) can be produced at a relatively low cost, but has a problem in gas barrier properties and transport resistance.

  In addition, the packaging material using the laminate (2) can also reduce the cost, and since LLDPE is laminated, the transport resistance is improved, but there is a problem in the gas barrier property.

  Further, the packaging material using the laminate (3) has MXNy or EVOH as a barrier layer. For this reason, the packaging material using a laminated material (3) is increasing in cost.

JP 2006-117267 A Patent No. 3007408

  The present invention has been made in consideration of the problems of the conventional packaging materials for paper containers as described above, and can be used for paper containers that can have excellent gas barrier properties and can reduce manufacturing costs. It aims at providing a packaging material and a paper container produced using the same.

  The present invention relates to a packaging material for paper containers made of a laminate material, wherein the laminate material is provided on the outermost layer, the paper base layer having a rough surface on both sides, and the outermost layer of the base material layer. A gas barrier property mainly composed of an epoxy resin composition which is provided on the side surface and which is provided on the smoothing layer for smoothing the rough surface of the surface, and which is provided on the smoothing layer and comprising an epoxy resin and an epoxy resin curing agent. A packaging material for paper containers, comprising: an adhesive layer having an innermost layer; and an innermost layer provided on the adhesive layer.

  The present invention provides the packaging material for paper containers, wherein the smoothing layer comprises an LDPE layer or an LLDPE layer.

  The present invention is the paper container packaging material characterized in that the smoothing layer comprises a clay coat layer.

  The present invention provides the packaging material for paper containers, wherein the epoxy resin of the adhesive layer is made of an epoxy resin containing an aromatic moiety in the molecule.

  The present invention is the paper container packaging material characterized in that the epoxy resin of the adhesive layer is made of an epoxy resin derived from metaxylenediamine.

  The present invention provides the packaging material for paper containers, wherein the surface of the smoothing layer has a surface roughness PPS of 3 μm or less when measured according to JIS P8151.

  The present invention is a paper container using the packaging material for a paper container described above.

  As described above, according to the present invention, the gas barrier property of a paper container packaging material and a paper container using the same can be improved. Further, since the packaging material includes an adhesive layer having a gas barrier property, it is not necessary to separately provide a barrier material having a gas barrier property, and thus the cost for producing the packaging material can be reduced.

FIG. 1 is a side sectional view showing a layer structure constituting a laminated material of paper container packaging material according to the present invention. The perspective view which shows the paper container produced using the packaging material for paper containers. The top view which shows the blank material for producing the paper container shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 3 are views showing an embodiment of a paper container packaging material and a paper container using the same according to the present invention.

  First, the paper container will be described with reference to FIGS.

  For example, conventionally, a paperbell-type paper container 1 is used to store milk, alcohol, soft drinks, and the like (FIG. 2).

  Such a gable-top type paper container 1 has a trunk portion 2, a roof portion 3, and a sealing portion 4 that seals the roof portion 3. And the paper container 1 is produced by folding the blank material 5 shown in FIG. 3, and adhere | attaching it by the margin part 5a of an edge part.

  A blank material 5 for producing the paper container 1 is composed of a laminated material 10 having a layer structure shown in FIG.

  That is, the laminated material 10 includes the following layers that are sequentially arranged from the outer surface side toward the inner surface side.

Polyethylene layer (PE) 11 / paper base layer 12 / smoothing layer 13 / adhesive layer 14 / polyethylene layer (PE) 15
Next, each layer will be described below.

(Polyethylene layer 11)
The polyethylene layer 11 which is the outermost layer mainly contains polyethylene, protects the outside of the paper base material layer 12, and is heated at the end of the packaging material 10 for liquid paper containers to become the innermost layer described later. Laminated with layer 15.

  Specific examples of the polyethylene used here include low density polyethylene (LDPE), medium density polyethylene (MDPE), and linear low density polyethylene (LLDPE). Low density polyethylene is preferred from the viewpoint of sealing properties, processing suitability, and the like. As the low density polyethylene, a polymer of ethylene is preferable, and specifically, a high pressure ethylene homopolymer is suitably used.

  The density of the low-density polyethylene constituting the outermost layer is not particularly limited as long as it is generally referred to as low-density polyethylene, but it is 0.90 to 0.925 g / cm 3. I. Is not particularly limited, and is usually from 1 to 20, and the melting point is from 100 ° C to 120 ° C.

  Although the formation method of the polyethylene layer 11 which is the outermost layer is not specifically limited, For example, it forms by carrying out extrusion coating to one side of the paper base material layer 12. FIG. As processing conditions for extrusion coating, an extrusion temperature of 280 to 330 ° C. and a line speed of 100 to 300 m / min. It is set in the range. The thickness of the polyethylene layer 11 is not particularly limited, but is usually 10 to 60 μm.

  The outermost polyethylene layer 11 is a layer that becomes the outer surface of the liquid paper container, but a printing layer may be further provided thereon. In order to improve the adhesion of the printing ink used for the printing layer, it is preferable to subject the surface of the polyethylene layer 11 to surface treatment (for example, corona treatment).

(Paper base material layer 12)
Since the paper base material layer 12 is a basic material constituting the liquid paper container of the present invention, a material having formability, bending resistance, rigidity, waist, strength and the like can be used. As the paper, it is a main strength material, and it is possible to use various sized paper substrates such as a strong sized bleached or unbleached paper substrate, or pure white roll paper, kraft paper, paperboard, processed paper, and milk base paper. .

The paper base layer 12 may be a stack of these papers. The paper to be used can be one having a basis weight of 80 to 600 g / m2, preferably a basis weight of 100 to 450 g / m2. The paper having a thickness of 110 to 860 μm, preferably 140 to 640 μm can be used.
The basis weight of the paper base layer 12 is, for example, 300 g / m ² .

  Since paper used for the paper base layer 12 generally has fibrous burrs on both sides thereof, the paper base layer has rough surfaces on both sides. When the degree of the rough surface is measured based on JIS P8151, the surface roughness PPS (Parker Print Surf) is preferably 7 μm or less.

(Smoothing layer)
The smoothing layer 13 is provided on the surface of the paper base material layer 12 opposite to the outermost layer 11, and smoothes the rough surface of the paper base material layer 12.

  For example, the smoothing layer 13 is made of LDPE (Low Density Polyethylene) or LLDPE (Linear Low Density Polyethylene), and is formed by extrusion coating on the surface opposite to the outermost layer 11 of the paper substrate layer 12. As processing conditions for extrusion coating, an extrusion temperature of 280 to 330 ° C. and a line speed of 100 to 300 m / min. It is set in the range. The thickness of the smoothing layer 13 is not particularly limited, but is usually 10 to 60 μm.

  The chill roll used in this case is a mirror-type or semi-mirror-type roll that has been subjected to wet blasting and drive blast treatment after chrome plating on the roll. By using this chill roll, a smoothing layer The smoothness of 13 can be increased.

  Specifically, a KRH type mirror or a semi-mirror type chill roll is preferable. Furthermore, in addition to the surface roughness of the smoothing layer 13, by increasing the smoothness of the paper substrate layer 12 itself, the adhesive layer 14 described later can be applied more uniformly, and the film of the adhesive layer 14 It is possible to improve the barrier property by eliminating the defects.

  By providing such a smoothing layer 13 on the paper base layer 12, the surface roughness PPS of the smoothing layer 13 is 3 μm or less when measured according to JIS P8151.

  As the smoothing layer 13, a clay coat layer may be provided instead of LDPE or LLDPE.

  By providing the clay coat layer, the pinhole generated by hot air at the time of sealing with a filling machine is improved, and the total thickness of the polyethylene layer 15 can be reduced.

  In addition, since the clay coat layer surface is usually smooth, the adhesion with the extruded and laminated resin tends to be inferior. However, as will be described later, an epoxy resin composed of an epoxy resin and an epoxy resin curing agent is used as the adhesive layer 14. By using the composition, the adhesion to the polyethylene layer 15 is also improved. When further lamination strength is required, ozone treatment or the like may be used as appropriate when the polyethylene layer 15 is extruded and laminated.

  The clay layer includes clay, and this clay can be used without particular limitation as long as it is generally called clay, clay, kaolin, talc, bentonite, smectite, vermiculite, mica, chlorite. Kibushi clay, gyrome clay, halloysite, mica, etc. can be used. Of these, kaolin and talc are preferably used as the clay. Kaolin has excellent concealability and water absorption, and talc has low hardness (Mohs hardness 1) and excellent heat resistance. Improvement in dimensional stability can be expected.

  The clay coat layer preferably contains calcium carbonate, titanium dioxide, amorphous silica, expandable barium sulfate, satin white and the like as a pigment in addition to clay. By using calcium carbonate or titanium dioxide as the pigment, the smoothness of the surface of the clay coat layer can be increased and the concealability can be increased. Furthermore, calcium carbonate is preferably used because it is inexpensive.

  A coating liquid (clay coating layer coating liquid) for coating the clay coat layer contains the clay, a binder, and, if necessary, other pigments and additives in a solvent. As the solvent, water, alcohol or the like is usually used. As the binder, latex binders (eg, styrene butadiene latex, acrylic latex vinyl acetate latex), water-soluble binders (eg, starch (modified starch, oxidized starch, hydroxyethyl etherified starch, phosphate ester) Modified starch), polyvinyl alcohol, casein, and the like. Examples of additives that can be used include pigment dispersants, antifoaming agents, antifoaming agents, viscosity modifiers, lubricants, water resistance agents, water retention agents, coloring materials, and printability improvers.

  The blending ratio of the clay coating layer coating solution is not particularly limited, but is preferably about clay: pigment: binder = 1-20%: 50-90%: 10-30%.

  The coating method of the clay coat layer is not particularly limited, and a conventionally known coating method is used, but a coating method such as air knife coating, blade coating, short dwell coating, cast coating or the like is used.

Although the coating amount and thickness of a clay coat layer are not specifically limited, Usually, the basic weight after drying is 5-40 g / m < ² >, and 10-40 g / m < ² > is preferable. When the basis weight after drying is less than 5 g / m ² , the smoothness may be inferior, and when the basis weight after drying exceeds 40 g / m ² , the container becomes too thick and the production suitability may be deteriorated. Moreover, since the adhesive strength tends to decrease, it is not preferable.

(Adhesive layer 14)
The adhesive layer 14 is provided on the smoothing layer 13 and is mainly composed of an epoxy resin composition composed of an epoxy resin and an epoxy resin curing agent, and an anchor coat layer (AC layer) having excellent gas barrier properties. ).

  Such an adhesive layer 14 adheres the innermost layer 15 made of polyethylene and the smoothing layer 13 on the paper base material layer 12, and examples of the adhesive layer 14 include Japanese Patent Application Laid-Open Nos. 2003-155465 and 2007. It has Maxive (anchor coat agent) manufactured by Mitsubishi Gas Co., Ltd., shown in -126627.

  By providing such an adhesive layer 14 between the smoothing layer 13 and the polyethylene layer 15, the gas barrier property can be improved. Furthermore, by laminating LLDPE as the smoothing layer 13, the transport resistance can be improved.

  Hereinafter, Maxieve will be described in detail.

Makushibu of coating ^{weight: 1g / m 2 ~5g / m} 2 ( does not appear gas barrier properties that it 1g / ^{m 2} or less.
If it is 5 g / m ² or more, the solid content concentration must be increased. Maxive's coating solution has a short pot life, so increasing the solids concentration significantly reduces workability)
Maxive solid content concentration: 20% or less By smoothing the Maxive coating surface (smoothing layer 13), the Maxive coating solution is uniformly applied to improve the gas barrier, that is, the Maxive film is not damaged. Can be.

  The coating method is not particularly limited, and conventionally known coating methods can be used. Specifically, coating such as gravure coating, roll coating, air knife coating, blade coating, short dwell, cast coating, etc. A construction method is used.

  After coating, it is desirable to laminate the polyethylene layer 15 after passing through a dry hood at 80 ° C. or higher in order to promote the crosslinking reaction of MAXIVE.

(Polyethylene layer 15)
As the polyethylene layer 15 that is the innermost layer, the same layer as the polyethylene layer 11 that is the outermost layer described above can be used. Among these, it is preferable to use low density polyethylene (LDPE) or medium density polyethylene (MDPE). The thickness of the polyethylene layer 15 is not particularly limited, but is usually 10 to 60 μm.

  When medium density polyethylene or low density polyethylene is used for the polyethylene layer 15 which is the innermost layer, the innermost layer is highly slippery, the mechanical suitability is improved, and can be manufactured at low cost. Further, by using these resins, the possible range of the sealing temperature is widened, and the time and cost for creating the packaging container can be reduced.

  Next, specific examples of the present invention will be described below.

Example 1
A low density polyethylene resin (density: 0.923 g / cm ³ , melt index MI; 3.8) is formed on one surface of a paper base material layer 12 made of a base paper for liquid paper containers having a basis weight of 320 g / m ^2. The outermost layer 11 having a thickness of 17 μm was formed by extrusion coating. Further, a linear low density polyethylene resin (density: 0.913 g / cm ³ , melt index M.I; 8.0) was extrusion-coated with a chill roll of KRH120-1.5 on the reverse side of the base paper surface to obtain a thick A smoothing layer 13 having a thickness of 20 μm was formed. Subsequently, the smoothing layer 13 is coated with a gravure roll using an epoxy resin composition composed of an epoxy resin and an epoxy resin curing agent as a main component so as to be 2.0 g / m ² in dry conversion. And dried to form an adhesive layer 14. Further, an additive-free low-density polyethylene resin (density: 0.923 g / cm ³ , melt index MI; 3.8) is extrusion coated on the adhesive layer 14 to form an innermost layer 15 having a thickness of 20 μm and packaged. Material 10 was obtained.

(Example 2)
A paper base layer 12 made of base paper for a liquid paper container having a basis weight of 320 g / m ² is coated with a clay coating layer coating solution (kaolin clay 10 mass%, calcium carbonate 70 mass%, styrene butadiene latex 9 mass%, A clay coat layer (smoothing layer) 13 made of vinyl acetate latex 9% by mass, sodium polyacrylate 0.4% by mass, and other 1.6% by mass) was formed by an air knife coating method. The clay coat layer had a basis weight of 12 g / m ² .

Next, a low-density polyethylene resin (density: 0.923 g / cm ³ , melt index MI; 3.8) is extrusion coated on the other surface of the paper base material layer 12 to form an outermost layer 11 having a thickness of 17 μm. Formed. Furthermore, using a gravure roll for the smoothing layer 13, a laminating adhesive mainly composed of an epoxy resin composition composed of an epoxy resin and an epoxy resin curing agent is coated to a dry conversion of 2.0 g / m ^2. And dried to form an adhesive layer 14. Further, the adhesive layer 14 has a linear low density polyethylene resin (density: 0.913 g / cm ³ , melt index MI; 8.0) 15 μm and an additive-free low density polyethylene resin (density: 0.923 g / cm ³ , melt index MI; 3.8) 15μ was laminated by coextrusion while performing ozone treatment to form the innermost layer 15 to obtain a packaging material 10.

Example 3
A low-density polyethylene resin (density: 0.923 g / cm3, melt index MI; 3.8) is extruded on one surface of a paper base layer 12 made of base paper for liquid paper containers having a basis weight of 320 g / m2. The outermost layer 11 having a thickness of 17 μm was formed by coating. Furthermore, a low-density polyethylene resin (density: 0.923 g / cm 3, melt index MI; 3.8) was extrusion-coated with a KRH120-1.5 chill roll on the reverse side of the base paper, and a smoothness of 20 μm in thickness was obtained. The formation layer 13 was formed. Subsequently, the smoothing layer 13 is coated with a gravure roll using an epoxy resin composition composed of an epoxy resin and an epoxy resin curing agent as a main component so as to be 2.0 g / m ² in dry conversion. And dried to form an adhesive layer 14. Further, an additive-free low-density polyethylene resin (density: 0.923 g / cm 3, melt index MI; 3.8) is extrusion coated on the adhesive layer 14 to form an innermost layer 15 having a thickness of 20 μm, and a packaging material. 10 was obtained.

Example 4
A low density polyethylene resin (density: 0.923 g / cm3, melt index MI; 3.8) was extrusion coated on one surface of a base material layer made of a base paper for liquid paper containers having a basis weight of 320 g / m2. An outermost layer 11 having a thickness of 17 μm was formed. Further, a low-density polyethylene resin (density: 0.923 g / cm 3, melt index MI; 3.8) is extrusion-coated with a KRS80-2 chill roll on the reverse side of the base paper, and a smoothing layer having a thickness of 20 μm. 13 was formed. Subsequently, the smoothing layer 13 is coated with a gravure roll using an epoxy resin composition composed of an epoxy resin and an epoxy resin curing agent as a main component so as to have a dry conversion of 2.0 g / m2. And dried to form an adhesive 14. Further, an additive-free low-density polyethylene resin (density: 0.923 g / cm 3, melt index MI; 3.8) is extrusion-coated to form an innermost layer 15 having a thickness of 40 μm and packaging material. 10 was obtained.

(Comparative Examples 1-2)
The packaging materials of Comparative Examples 1 and 2 were the same as in Examples 1 and 2, except that the adhesive layer 14 for laminating mainly composed of an epoxy resin composition composed of an epoxy resin and an epoxy resin curing agent was not formed. Produced.

(Comparative Examples 3-4)
Except that the smoothing layer 13 was not formed, packaging materials of Comparative Examples 3 to 4 were produced in the same manner as in Examples 1 and 2.

  Using the packaging material 10 shown in Example 1-4 and Comparative Example 1-4, a Gobeltop paper container 1 is prepared, and orange juice is filled into the Gobeltop paper container 1, and vitamins in the orange juice are prepared. The residual amount of C was measured.

＊平滑化層が無い為、紙製基材層と最内層との剥離強度を示した。 The measurement results are shown in Table 1.

* Because there was no smoothing layer, the peel strength between the paper base layer and the innermost layer was shown.

  As shown in Table 1, when the packaging material 10 shown in Example 1-4 is used, the peel strength between the smoothing layer 13 and the innermost layer 15 is improved, and the gas barrier property is not peeled off. It has improved.

  When the packaging material 10 shown in Comparative Example 1-2 is used, there is no gas barrier property because the adhesive layer 14 having the barrier property is lacking.

  When the packaging material 10 shown in Comparative Example 3-4 is used, since the smoothing layer 13 is lacking, it is difficult to uniformly form the adhesive layer 14 on the paper base layer 12. Since 14 has a portion where the gas barrier property is lowered, the gas barrier property of the adhesive layer 14 as a whole is lowered.

DESCRIPTION OF SYMBOLS 1 Paper container 5 Blank material 10 Laminate material 11 Polyethylene layer 12 Paper base material layer 13 Smoothing layer 14 Adhesive layer 15 Polyethylene layer

Claims (7)

In packaging materials for paper containers made of laminated materials,
Laminate is the outermost layer,
A paper base layer provided on the outermost layer and having a rough surface on both sides;
A smoothing layer which is provided on the surface opposite to the outermost layer of the base material layer and smoothes the rough surface of the surface;
An adhesive layer having a gas barrier property, the main component of which is an epoxy resin composition comprising an epoxy resin and an epoxy resin curing agent, provided on the smoothing layer;
A packaging material for paper containers, comprising an innermost layer provided on an adhesive layer.   The paper container packaging material according to claim 1, wherein the smoothing layer comprises an LDPE layer or an LLDPE layer.   The paper container packaging material according to claim 1, wherein the smoothing layer comprises a clay coat layer.   The packaging material for a paper container according to any one of claims 1 to 3, wherein the epoxy resin of the adhesive layer is made of an epoxy resin containing an aromatic moiety in the molecule.   The packaging material for paper containers according to any one of claims 1 to 4, wherein the epoxy resin of the adhesive layer is made of an epoxy resin derived from meta-xylenediamine.   The packaging material for paper containers according to any one of claims 1 to 5, wherein the surface of the smoothing layer has a surface roughness PPS of 3 µm or less when measured according to JIS P8151.   A paper container using the packaging material for a paper container according to any one of claims 1 to 6.

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