JP2020019550A - Base paper for container and paper container using the base paper for container - Google Patents

Abstract

To provide base paper for a container, which can improve openability without decreasing strength required for holding of a content, and which maintaining strength, and a paper container.SOLUTION: Base paper 1 for a paper pack container 100 includes a base layer 3 that is composed predominantly of paper, and surface layers 8 and 8 that are composed predominantly of a synthetic resin. The base layer 3 among them has an inner layer 4 that is in an approximately central position in a thickness direction, and outer layers 7 and 7 that are overlaid on both the sides of the inner layer 4, respectively. The inner layer 4 has a first inner layer 5, and second inner layers 6 and 6 that are overlaid on both the sides of the first inner layer 5, respectively. In an MD direction, Elmendorf tear strength of the base paper 1 is set to be in the range of 5.5 to 10.0 mN m/g.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a container base paper and a paper container using the container base paper.

BACKGROUND ART Conventionally, as a paper container for storing a liquid such as milk, a paper container formed by folding a plurality of layers of paper (container base paper) and bonding them together by heat sealing is known.
In such a paper container, first, a container having a substantially square-shaped accommodation portion whose upper part is opened is prepared. Next, the liquid as the content is filled into the inside of the cylindrical body, and thereafter, the panel located around the upper opening is bent, and the facing surface is sealed by heat sealing. The paper container whose opening is sealed by heat sealing has a certain strength. Thereby, the paper container can be held so that the contents do not leak during storage or transportation.
Then, when the liquid of the content is poured out from the paper container, the upper opposing surface is separated, and the spout is opened.

As such a paper container, for example, one described in Patent Document 1 is known. In the paper container of Patent Document 1, a rib panel is continuously provided on an upper panel of the opening. When the heat seal is opened, the force in the tearing direction is easily applied by gripping the rib panel.
Further, in the paper container of Patent Literature 2, an easily peelable region is provided in a part of the region to be heat-sealed.
Further, in the paper container disclosed in Patent Document 3, a reinforcing line is provided on a gable roof formed by bending a panel at an upper opening.

Japanese Patent No. 4515138 JP 2013-47119 A JP 2007-99391 A

However, the one described in Patent Literature 1 has a different outer shape from other paper containers, and thus requires a dedicated box-making machine for box-making. In addition, during transportation or display, the dimensions may not be adjusted with other paper containers, which may cause troubles such as troublesome work.
Further, in the technique described in Patent Document 2, it is necessary to provide an easy peeling area in a part of the area to be heat-sealed. The easy peeling area is partially formed at a predetermined location. In order to equalize the force required for unsealing, the area and shape of the easily peelable region must be properly adjusted. For this reason, there is a possibility that the box making process becomes complicated.
And in what is described in patent document 3, a reinforcement line must be formed in a gable roof part. An additional step is required to form such a reinforcing line. Further, when the reinforcing wire is provided on the outer surface of the gable roof portion, there is a problem that the design property is deteriorated.
Therefore, an object of the present invention is to provide a base paper for a container and a paper container using the base paper for a container, which can improve the opening property while securing the strength required for holding the contents. .

The present invention is a base paper for a container including a base layer mainly composed of paper, and a surface layer mainly covering a surface side of the base layer mainly composed of a thermoplastic resin. In the fiber orientation direction of the paper used for the base layer, the Elmendorf specific tear strength of the base paper is set to 5.5 mN · m ² / g or more and 10.0 mN · m ² / g or less.
In the direction orthogonal to the fiber orientation direction of the paper used for the base layer, the Elmendorf specific tear strength of the base paper is preferably set to 6.5 mN · m ² / g or more and 11.5 mN · m ² / g or less.
In the fiber orientation direction of the paper used for the base layer, the peel strength is preferably set to 3.5 N or more and 7.8 N or less.
In the fiber orientation direction of the paper used for the base layer, the Taber stiffness is preferably set to 10 mN · m or more and 30 mN · m or less.
In a direction orthogonal to the fiber orientation direction of the paper used for the base layer, the Taber stiffness is preferably set to 4 mN · m or more and 15 mN · m or less.
More preferably, a paper container having a pair of opposed surface layers each having a heat-sealed spout, and a fiber orientation direction of a base layer along a direction in which separation progresses when the spout is opened. Good.

According to the container base paper of the present invention, when the Elmendorf specific tear strength of the base paper in the fiber orientation direction of the paper used for the base layer is appropriately set, for example, when a paper container is formed using the container base paper In addition, the openability can be improved without impairing the strength required for holding the contents.
Further, according to the paper container of the present invention, when opening the spout of the container, the fiber orientation direction of the paper used for the base layer is along the direction in which the separation of the opening operation progresses. For this reason, the base layer is easily peeled, and the openability is good.

It is a perspective view showing signs that a container part was closed in a paper pack container of an embodiment of the present invention. It is a perspective view showing signs that the spout of the opening was opened in the paper pack container of an embodiment. FIG. 2 is a plan view in which the base paper is developed with container base paper used for the paper pack container of the embodiment. FIG. 4 is a cross-sectional view illustrating a configuration of the base paper of the paper pack container according to the embodiment, taken along a line IV-IV in FIG. 3. FIG. 5 is a cross-sectional view illustrating a configuration of the paper pack container according to the embodiment, taken along a line VV in FIG. 1. It is a figure which shows typically the test body used for a peeling test in order to measure peeling strength.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. The same components are denoted by the same reference numerals, and redundant description will be omitted.
As shown in FIGS. 1 and 2, a paper pack container 100 as a paper container is formed by folding a base paper (container base paper, hereinafter simply referred to as base paper) 1 made of a laminate into a substantially square shape. .
[Paper pack container]
The paper pack container 100 is formed by bending the base paper 1 shown in FIG. 3 and bonding the adhesive margin portion 1a by heat-sealing to form a rectangular tube. As a result, the paper pack container 100 becomes a sealed container capable of storing the content liquid in the storage section 101.
A gable roof-type (gable-top-shaped) crown 102 extends above the housing 101.
The top portion 102 has a mountain-shaped folded portion 103 formed by folding the upper portion of the facing base paper 1 inward, a pair of roof panel portions 104 facing each other with the mountain-shaped folded portion 103 interposed therebetween, and a top portion of each roof panel portion 104. And a joining surface 105 which is located at the edge and is joined by heat sealing (see FIG. 2).

[Container base paper]
As shown in FIG. 4, the base paper 1 of the paper pack container 100 includes a base layer 3 mainly composed of paper, and surface layers 8 mainly covering a surface side of the base layer 3 mainly composed of a thermoplastic resin. The base paper 1 of this embodiment has a plurality of layers, that is, five base layers 3 and two surface layers 8 and 8, and is laminated so as to have a total of seven layers.
Among these, the base layer 3 has an inner layer 4 located substantially at the center in the thickness direction, and outer layers 7, 7 laminated on both sides of the inner layer 4, respectively.
Further, the surface sides of the outer layers 7, 7 are covered with surface layers 8, 8, respectively. The surface layers 8, 8 are configured using a polyethylene material as a thermoplastic resin.
The surface layer 8 is formed by performing a laminating process on the base layer 3, and is laminated with at least a part of the outer layer 7 impregnated with polyethylene. At the periphery of the spout 106, the facing surface layers 8, 8 are bonded to each other by heat sealing.
The peel strength in the thickness direction in the base layer 3 made of paper is smaller than the peel strength between the outer layer 7 and the surface layer 8.

[pulp]
Paper is manufactured by a paper machine (machine for making paper) while pulp as a raw material is flowed in a certain direction. For this reason, in the base paper 1, the orientation of the fibers in the inner layer 4 and the outer layer 7 tends to be uniform in the traveling direction.
The fiber orientation direction MD of the paper used for the inner layer 4 of this embodiment (see FIG. 3, hereinafter referred to as the MD direction) is configured to match the MD direction used for the outer layers 7,7. The paper flow direction (fiber orientation direction) of the first inner layer 5 constituting the inner layer 4 is configured to be the same as the fiber orientation direction of the second inner layers 6 and 6.
Pulp, which is a raw material of the base layer 3 of the base paper 1, contains cellulose pulp as a main component. The cellulose pulp is not particularly limited, but preferably contains a chemical pulp from the viewpoint of strength. The chemical pulp is not particularly limited, but preferably contains hardwood kraft pulp (LKP) or softwood kraft pulp (NKP).

[Pulp ingredients]
The pulp component may include pulp other than NKP and LKP (hereinafter, referred to as other pulp). Other pulps include stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), thermo ground pulp (TGP), chemi ground pulp (CGP), groundwood pulp (GP), and thermo pulp. Disintegration manufactured from mechanical pulp such as mechanical pulp (TMP), tea waste paper, kraft envelope waste paper, magazine waste paper, newspaper waste paper, flyer waste paper, office waste paper, cardboard waste paper, Kamishiro waste paper, Kent waste paper, imitation waste paper, and ground ticket waste paper Waste paper pulp (DIP) or pulp chemically or mechanically made from non-wood fibers such as kenaf, hemp, reeds and the like. The content of the other pulp is preferably less than 3% by mass, more preferably less than 2% by mass, more preferably less than 1% by mass, based on the total mass of the pulp components by NKP and LKP. More preferred.

The pulp may be bleached pulp or unbleached pulp. Further, it is preferable to contain both LKP and NKP.
The bleached pulp is mainly classified into LBKP (leaf bleached kraft pulp: hardwood bleached kraft pulp) and NBKP (needle bleached kraft pulp: softwood bleached kraft pulp).
Generally, as the mass ratio of LBKP increases, the strength of the paper decreases, and as the mass ratio of NBKP increases, the strength of the paper increases.
In this embodiment, the mass ratio of NBKP in the pulp material constituting the outer layer 7 is equal to or less than the mass ratio of NBKP in the pulp material constituting the inner layer 4.
In the base paper 1 of this embodiment, the mass ratio of N / L of LBKP (L) and NBKP (N) is 30/70 in the inner layer 4 (the first inner layer 5 and the second inner layers 6 and 6) and 0 in the outer layer 7. / 100. In the inner layer 4, the ratio of NBKP in the pulp material may be 0% by mass, but is preferably 20% by mass or more and 50% by mass or less, more preferably 30% by mass or more and 40% by mass or less. In the outer layer 7, the proportion of NBKP in the pulp material is preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably 0% by mass.

[Degree of beating]
Generally, if the freeness of pulp is increased, the tear strength, peel strength and Taber stiffness of the paper-made product can be increased.
On the other hand, when the freeness is reduced, the tear strength, the peel strength, and the Taber stiffness are reduced. Then, the present inventors obtain a sufficiently small tear strength and peel strength for the base paper 1 thus formed, and at the same time, obtain the performance required for a liquid paper container (when the base paper 1 is made into a liquid paper container and a liquid is injected). In this study, the disintegration freeness that can obtain the Taber stiffness that does not impair the body part does not swell greatly was repeated. As a result, they have found that the disintegration freeness of the base layer 3 (the inner layer 4 and the outer layer 7) is preferably 400 to 550 mlcsf.
The disintegration freeness of the base layer 3 is more preferably 450 to 550 mlcsf, and further preferably 500 to 550 mlcsf.
Further, the freeness of the cellulose pulp before papermaking is more preferably 400 to 500 mlcsf, and further preferably 450 to 500 mlcsf.
Here, the defibration freeness refers to a value of Canadian standard freeness measured according to the method of JIS P 8121: 2012 using a pulp slurry obtained by defibrating the base paper according to the method of JIS P 8220: 2012.
The defibration freeness can be adjusted by adjusting the freeness of the cellulose pulp before papermaking.

[Basic weight]
The basis weight of the base paper 1 is preferably from 200 to 400 g / m ² . If the basis weight is less than 200 g / m ² , it may be difficult to obtain the strength required for the container. On the other hand, when the grammage exceeds 400 g / m ² , the rigidity of the paper is too high, the pliability is lost, and the opening property may be deteriorated. In addition, there is a possibility that the cost will increase.

[Paper thickness]
The thickness of the base paper 1 is preferably from 250 to 500 μm. If the paper thickness is larger than 500 μm, there is a possibility that the opening property may be impaired. On the other hand, if the paper thickness is less than 250 μm, it may be difficult to secure the necessary strength as a container.

[density]
The density of the base paper 1 is preferably 0.760~0.780g / cm ^3, more preferably if 0.762~0.778g / cm ^3, further is around 0.764 g / cm ³ Note Good. When the density is larger than 0.780 g / cm ³ , it is necessary to make the paper thickness extremely thin, and there is a possibility that productivity may be reduced. On the other hand, if the density is less than 0.760 g / cm ³ , it may be difficult to secure necessary strength as a container.

As a result of being constituted by the above-mentioned proper blending, a base paper 1 having the following characteristics was obtained.
[Elmendorf tear strength]
In the base paper 1 of this embodiment, the Elmendorf specific tear strength in the MD direction of the base layer 3 is set to 5.5 mN · m ² / g or more and 10.0 mN · m ² / g or less.
When the Elmendorf specific tear strength of the base paper 1 in the MD direction is less than 5.5 mN · m ² / g, it becomes difficult to obtain the strength required for a container. On the other hand, when the Elmendorf specific tear strength of the base paper 1 in the MD direction exceeds 10.0 mN · m ² / g, the strength of the paper is too high, it is difficult to peel off, and the opening property is deteriorated. The Elmendorf specific tear strength of the base paper 1 in the MD direction is more preferably 6.5 mN · m ² / g or more and 9.5 mN · m ² / g or less.

The base paper 1 has an Elmendorf specific tear strength of not less than 6.5 mN · m ² / g and not more than 11.5 mN · m ² / g in the CD direction orthogonal to the MD direction of the base layer 3. When the Elmendorf specific tear strength of the base paper 1 in the CD direction is less than 6.5 mN · m ² / g, it is difficult to obtain the strength required for a container. On the other hand, when the Elmendorf specific tear strength of the base paper 1 in the orthogonal CD direction exceeds 11.5 mN · m ² / g, the strength of the paper is too high, the paper is hardly peeled off, and the openability deteriorates.

[Peeling strength]
The base paper 1 of this embodiment is set so that the peel strength measured by a peel test described later is 3.5 N or more and 7.8 N or less in the MD direction. The peel strength is more preferably 4.0 N or more and 7.0 N or less.

[Taber stiffness]
Further, the base paper 1 is set so that the Taber stiffness (JIS P8125: 2000) is 10 mN · m or more and 30 mN · m or less in the MD direction. When the Taber stiffness in the MD direction is less than 10 mN · m, it becomes difficult to obtain the strength required for a container. On the other hand, when the Taber stiffness in the MD direction exceeds 30 mN · m, the rigidity of the paper is too high, the pliability is lost, and the openability deteriorates. More preferably, the Taber stiffness in the MD direction is not less than 24 mN · m and not more than 28 mN · m.
The base paper 1 is set so that the Taber stiffness is 4 mN · m or more and 15 mN · m or less in the CD direction of the base layer 3. When the Taber stiffness in the CD direction is less than 4 mN · m, it becomes difficult to obtain the strength required for a container. On the other hand, when the Taber stiffness in the CD direction exceeds 15 mN · m, the rigidity of the paper is too high, the pliability is lost, and the opening property is deteriorated. The Taber stiffness in the CD direction is more preferably 7 mN · m or more and 13 mN · m or less.

The spout 106 is sealed by heat sealing the surface layers 8, 8 of the pair of base papers 1, 1 facing each other.
The MD direction is configured to be along the peeling direction F2 (see FIG. 1) when the spout 106 is opened.

[Peeling test]
A conventionally known peel strength measuring method (JIS Z 0238: 1998 Test method for heat-sealed flexible packaging bags and rigid containers) is used as a method for measuring heat seal strength.

The openability can be evaluated by the method according to JIS Z 0238, but the measurement according to JIS Z 0238 is not suitable for the measurement of a rigid material such as a paper container because a bag is assumed as a non-inspection object. .
In view of this point, the present inventor has proposed a peeling test suitable for a specimen having rigidity such as a paper container.

FIG. 6 shows an example of a test body 200 used in the peel test.
First, a test body 200 in which a pair of strip-shaped base papers 1 and 1 are stuck together by heat sealing is prepared (step 1). In this peeling test, a sample of a pair of base papers 1 and 1 was superimposed, and a predetermined range including end portions 1d and 1d of base papers 1 and 1 (a range of distance b from one end) was bonded by heat sealing. Use 200.
Input portions 1b, 1b for applying a tearing force F11 to the other end portions 1e, 1e opposite to the one end portions 1d, 1d joined by heat sealing are set on the base papers 1, 1, respectively.
Next, a force for vertically separating the base papers 1 and 1 in and out of the paper surface is applied to the input units 1b and 1b (step 2).

Then, the force required when the pair of samples is separated, that is, the maximum load when the pair of base papers 1 and 1 are separated is measured as the peel strength (step 3).
Here, as the precondition, the extension length a of the sample, the length b of the heat seal, the grip width c, and the pulling speed d were defined. For example, the extension length a of the sample is 15 to 25 cm, the length b of the heat seal is 1.5 to 3.5 cm, the grip width c is 2.5 to 3.0 cm, and the sample is peeled in the separating direction. It is desirable to preset the pulling speed d = 1000 cm / min and the dimension (e = 4.5 to 10 cm) from the input section 1b to the heat seal.

  Table 1 shows the measurement results obtained by the Elmendorf specific tear strength test, the peel test, and the like, and is compared with the measurement results obtained for other paper pack containers. Here, the tear strength is the Elmendorf specific tear strength, and was measured for base paper 1 and base paper 1 in accordance with JIS P 8116: 2000. The peel strength was measured using the sample shown in FIG.

[Drop test]
In the drop test, the paper pack container 100 sealed with water was dropped twice from a height of 30 cm. Then, if there was no water leakage in the paper pack container 100, the result was evaluated as ○, and if there was water leakage, the result was evaluated as ×.
As a result, in the MD direction of the base paper 1, the Elmendorf specific tear strength is 5.5 mN · m ² / g or more, and in the CD direction perpendicular to the MD direction of the base paper 1, the Elmendorf specific tear strength is 6.5 mN · m ² / g. From the above, it is understood that the strength required for holding the contents of the paper pack container 100 is not impaired.
Further, it can be seen that if the peel strength in the MD direction of the paper is 3.5 N or more, preferably 4.0 N or more, the strength required for holding the contents of the paper pack container 100 is not impaired.

[Sensory evaluation test]
The sensory evaluation test of the opening property is a test in which the paper pack container 100 after box making is opened by the evaluator's hand. When the package could be easily opened, the openability was evaluated as good, and when the openability was not good, x was evaluated.
As a result, when the Elmendorf specific tear strength of the paper in the MD direction is 10.0 mN · m ² / g or less, preferably 9.5 mN · m ² / g or less, the evaluator evaluates the openability. Was good, and when it exceeded 11.4 mN · m ² / g, it was not good.
When the peel strength in the MD direction of the paper is 7.8 N or less, preferably 6.0 N or less, the evaluator has a good evaluation of the opening property. I knew it wasn't.
For this reason, the quality of the openability of the spout 106 of the paper pack container 100 can be evaluated as an objective numerical value by using the Elmendorf specific tear strength and the peel strength correlated with the evaluation of the openability by the evaluator. .
Further, when viewed in the CD direction, it was found that the openability was improved when the Elmendorf specific tear strength was 11.5 mN · m ² / g or less. Therefore, the Elmendorf ratio tear strength in the CD direction of the paper is preferably from 11.5mN · ^m 2 / g, more preferably at most 11.0mN · ^m 2 / g.
That is, the strength and the opening property can be compatible with each other by adjusting the Elmendorf specific tear strength of the base paper 1 to a value that can be easily opened within a range in which the strength required for transport or storage can be maintained.

Embodiment of a paper pack container 100, for example, as shown in Table 1 in Example 1, the Elmendorf ratio tear strength in the MD direction of the sheet 1 is 5.5mN · ^m 2 / g or more, 10.0mN · ^m 2 / The weight, paper thickness, and pulp composition (such as the ratio of LBKP to NBKP) are adjusted so as to be within the range of g or less.
As a result, the strength required for holding the contents is not impaired, and good openability is obtained even in a sensory evaluation test regarding openability.

When the paper pack container 100 is made from the base paper 1 and the spout at the top of the storage unit 101 is sealed by heat sealing, the contents can be held in a completely sealed state. In the paper pack container 100, it is not necessary to provide an easily peelable region in a part of the surface layers 8,8.
The pressure (side pressure) of the liquid acts on the side surface of the paper pack container 100 containing the liquid or the like. In order to obtain the paper pack container 100 that can withstand this pressure, the longitudinal direction h (FIG. It is desirable to make the Elmendorf specific tear strength of the reference example 2) larger than the Elmendorf specific tear strength in the lateral direction. In the base paper 1, since the Elmendorf specific tear strength in the CD direction is larger than the Elmendorf specific tear strength in the MD direction, the longitudinal direction h of the container and the CD direction of the base paper 1 may be matched as shown in FIG. preferable. In this way, in the paper pack container 100, a desired strength capable of holding the contents can be obtained.

Further, in the paper pack container 100, as shown in FIG. 5, the facing layers 8, 8 made of polyethylene material are bonded by heat sealing at opposing portions located at the periphery of the spout 106. The surface layers 8, 8 are joined in a state where at least a part of the outer layer 7 is impregnated. For this reason, the separation between the outer layer 7 and the surface layer 8 is less likely to be separated in the peeling direction HD than between the second inner layer 6 and the outer layer 7.
The MD direction of the base layer 3 is along the direction LD in which the separation of the paper proceeds during the opening operation. For this reason, the paper (base layer 3) can be easily separated between the second inner layer 6 and the outer layer 7 on the side bonded by heat sealing or at the outer layer 7 portion on the heat sealing side.

Since the inner layer 4 of this embodiment has a plurality of layers including the first inner layer 5 and the second inner layers 6 and 6, the base paper 1 is composed of five layers of paper including the outer layers 7 and 7. Have been. Therefore, in the paper pack container 100, even when the outer layer 7 on the heat seal side is separated from the base layer 3 by opening, the inner layer 4 composed of a plurality of layers remains in the base layer 3, so that the desired strength is obtained at the spout 106 after opening. Easy to get.
For example, as shown in FIG. 5, when the spout 106 of the paper pack container 100 is opened, the outer layer 7 on the heat seal side of one of the base papers 1 (the upper base paper 1 in FIG. 5) is separated from the second inner layer 6. As a result, the outer layer 7 and the surface layer 8 of one base paper 1 remain on the other base paper. Even in this case, the inner layer 4 composed of a plurality of layers and one outer layer 7 remain on one base paper 1. Therefore, the desired strength around the spout 106 can be maintained, and no reinforcement or the like is required. Therefore, the appearance quality is not reduced.

Furthermore, since the base layer 3 is formed by having five layers, a uniform base paper 1 can be formed even if any layer has uneven fiber density.
Therefore, the base paper 1 having stable quality is provided, and the surface layer 8 covering the outer layer 7 is smoothed, so that printing performed on the surface layer 8 can be improved.
Further, unlike the liquid container forming the rib panel, the paper pack container 100 does not require a dedicated box making machine adapted to the difference in shape and size. For this reason, if the base paper 1 of this embodiment is used, it can be manufactured as a paper pack container 100 of a standard specification in a general box making process, and the convenience in transportation or display is improved.

As described above, in the base paper 1 of this embodiment, the Elmendorf specific tear strength of the base paper 1 in the MD direction of the base layer 3 is appropriately set. Therefore, the paper pack container 100 formed using the base paper 1 can improve the opening property without impairing the strength.
Further, in the paper pack container 100 of the embodiment, the MD direction of the base layer 3 is aligned with the direction LD in which separation progresses. For this reason, when opening the spout 106 of the paper pack container 100, the base layer 3 is easily peeled off, and the openability is good.

In addition, the CD direction of the base layer 3 is made to coincide with the vertical direction in which the degree of contribution to the strength of the housing portion 101 shown in FIG. 1 is large. Further, the Elmendorf specific tear strength of the base paper 1 in the CD direction of the base layer 3 is set to be 6.5 mN · m ² / g or more and 11.5 mN · m ² / g or less, so as to be larger than the MD direction tear strength. I have.
As described above, when the Elmendorf specific tear strength of the base paper 1 in the CD direction of the base paper 1 is appropriately set, the openability can be improved without impairing the strength of the paper pack container 100.

  Further, in the MD direction of the base layer 3, the peel strength of the base paper 1 is set to be 3.5 N or more and 7.8 N or less. For this reason, when opening the spout 106 of the paper pack container 100, the base layer 3 can be more easily peeled off, and the opening property can be improved.

  Further, in the MD direction of the base layer 3, the Taber stiffness of the base paper 1 is set to be 10 mN · m or more and 30 mN · m or less. For this reason, when opening the spout 106 of the paper pack container 100, the base layer 3 can be easily peeled off, and the opening property can be improved.

  In addition, in the CD direction of the base layer 3, the Taber stiffness of the base paper 1 is set to be 4 mN · m or more and 15 mN · m or less. Therefore, the paper pack container 100 can have a desired strength.

  As described above, the paper pack container 100 formed by using the base paper 1 is formed by laminating a pair of outer layers 7 facing each other by heat sealing with the surface layers 8 interposed therebetween as shown in FIG. , The spout 106 is sealed. Then, the spout 106 is opened along the MD direction in which the Elmendorf specific tear strength is appropriately set in the separation and propagation directions LD1 and LD2 shown in FIGS. The opening property of the spout 106 can be improved.

  The present invention is not limited to the embodiments described above, and various modifications are possible. The above-described embodiments are exemplarily illustrated for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described above. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of one embodiment can be added to the configuration of another embodiment. Further, a part of the configuration of each embodiment can be deleted, or another configuration can be added or replaced. Possible modifications to the above embodiment are, for example, as follows.

  In this embodiment, the paper container 100 for a liquid beverage such as a milk pack has been described as a paper container. However, the type of the content is not limited. What kind of paper container can be used to store liquid contents such as soft drinks, seasonings such as mirin and soy sauce, liquid detergents such as kitchen detergents, or contents such as fluid powder having fluidity May be stored.

  Further, in the embodiment, the inner layer 4 is constituted by a total of three layers of the first inner layer 5 and the second inner layers 6 and 6. However, the present invention is not particularly limited to this, and the inner layer 4 may be composed of a single layer or a plurality of layers of two or more layers.

  In this embodiment, a single outer layer 7 is laminated on both sides of the inner layer 4. However, the present invention is not particularly limited to this, and the outer layer 7 may be formed on any one of the inner layers 4, or may be two or more layers, such that the number of layers differs on each side surface. It may be configured.

1 Base paper (base paper for containers)
3 Base layer 8 Surface layer 100 Paper pack container (paper container)
101 receiving part 105 joining surface 106 spout

Claims (6)

A base layer mainly made of paper;
A base paper for containers including a thermoplastic resin as a main component and a surface layer covering the surface side of the base layer,
The base paper for containers, characterized in that the Elmendorf specific tear strength is set to 5.5 mN · m ² / g or more and 10.0 mN · m ² / g or less in the fiber orientation direction of the paper used for the base layer. The Elmendorf specific tear strength is set to be 6.5 mN · m ² / g or more and 11.5 mN · m ² / g or less in a direction orthogonal to the fiber orientation direction of the paper used for the base layer. The container base paper according to claim 1.   The container base paper according to claim 1 or 2, wherein a peel strength in a fiber orientation direction of the paper used for the base layer is set to be 3.5 N or more and 7.8 N or less.   The fiber orientation direction of the paper used for the base layer is set so that the Taber stiffness is 10 mN · m or more and 30 mN · m or less, 4. The base paper for containers described in 1.   The direction which is orthogonal to the fiber orientation direction of the paper used for the base layer is set so that the Taber stiffness is 4 mN · m or more and 15 mN · m or less. The base paper for a container according to any one of the above. A paper container using the container base paper according to any one of claims 1 to 5,
A pair of opposed surface layers has a heat-sealed spout,
A paper container wherein the fiber orientation of the paper used for the base layer is aligned with the direction in which separation progresses when the spout is opened.

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