Paper packaging material, method for manufacturing paper-made package, and paper-made package

Abstract

To provide a paper packaging material having both sufficient strength and easy openability of a heat seal part.SOLUTION: A paper packaging material 100 includes a substrate layer 130 comprising a paper substrate, a barrier layer 141 comprising a barrier agent, an interposed layer 142, and a heat seal layer 143 comprising a heat seal agent in this order. The interposed layer 142 comprises a material containing at least one of the barrier agent and the heat seal agent. The proportion of the barrier agent in the total amount of the barrier agent and the heat seal agent in the interposed layer 142 is 35 mass% or less or 80 mass% or more by mass ratio after drying.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a paper packaging material, a method for manufacturing a paper package using the paper packaging material, and a paper package. [Background technology]

[0002] In recent years, paper packaging materials have been attracting attention as an alternative to plastic packaging materials due to environmental considerations. One such paper packaging material is one in which a sealant film, an anchor coat layer, a barrier layer, an adhesive layer, and a paper base material layer made of a base material mainly composed of paper are laminated in this order (see, for example, Patent Document 1). In the above configuration, the paper packaging material of Patent Document 1 is said to obtain excellent gas barrier properties while reducing the amount of application of the barrier coating agent that constitutes the barrier layer.

[0003] In such a package, when an external force is applied in a direction to peel the two base layers bonded together at the heat seal portion, the strength of the heat seal portion may be too high, making it difficult to open easily.

[0004] Therefore, Patent Document 2 proposes a packaging material with improved openability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-006393 A [Patent Document 2] JP 2001-071429 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, if too much emphasis is placed on ease of opening, the strength of the heat-sealed portion may decrease.

[0007] Therefore, the present disclosure has an object to provide a paper packaging material that combines sufficient strength and easy opening of the heat-sealed portion by adjusting the adhesion of each layer, and a method for manufacturing a paper package using the paper packaging material, and a paper package. [Means for solving the problem]

[0008] In order to solve the above problems, in the present disclosure, an intervening layer is provided between the heat seal layer and the layer of the other component, and the components of the intervening layer are devised.

[0009] That is, one embodiment of the paper packaging material disclosed herein comprises, in this order, a base layer made of a paper base material, a barrier layer made of a barrier agent, an intervening layer, and a heat-sealing layer made of a heat-sealing agent, the intervening layer being made of a material containing at least one of the barrier agent and the heat-sealing agent, and the proportion of the barrier agent in the total amount of the barrier agent and the heat-sealing agent in the intervening layer is 35 mass% or less, or 80 mass% or more, in terms of mass ratio after drying. Effect of the Invention

[0010] According to the above-mentioned configuration, a paper packaging material having sufficient strength in the heat-sealed portion and easy opening can be obtained. Also, a paper package using this paper packaging material can be obtained. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1A is a cross-sectional view showing an example of a paper packaging material according to the present disclosure, and FIG. 1B is a cross-sectional view showing an example of a paper packaging body, and is also a diagram for explaining a method for manufacturing a paper packaging body using the paper packaging material. [Diagram 2] FIG. 1 is a plan view showing an example of a paper packaging body according to the present disclosure. [Diagram 3] FIG. 2 is a diagram showing a laminated structure used in an experimental example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present disclosure, its application, or its uses.

[0013] <Embodiment> <Paper packaging material> 1(a) shows the configuration of a paper packaging material 100 according to this embodiment. The paper packaging material 100 is used to obtain a paper package 101, which will be described later.

[0014] 1(a), the paper packaging material 100 includes, in this order, a base layer 130, a barrier layer 141, an intervening layer 142, and a heat seal layer 143. Note that the paper packaging material 100 may include layers other than the barrier layer 141, the intervening layer 142, and the heat seal layer 143, as necessary. For example, the paper packaging material 100 may include a layer having a water resistance function or a layer having an oil resistance function.

[0015] In addition, Fig. 1(a) shows two paper packaging materials 100 arranged so that their heat seal layers 143 face each other. In other words, the paper packaging material 100 shown on the upper side and the paper packaging material 100 shown on the lower side in Fig. 1(a) have exactly the same configuration except that they are oriented in different directions. This is shown to explain an example of a paper packaging body 101, which will be described later with reference to Fig. 1(b).

[0016] The base material layer 130 is made of a paper base material, which is a base material mainly composed of paper. The base material layer 130 may have a single-layer structure made of one layer, or may have a multi-layer structure made of multiple layers stacked together.

[0017] The raw material of the paper base material is not particularly limited, and examples thereof include commonly known materials such as pulp. Examples of pulp include one or more types of chemical pulp such as bleached hardwood kraft pulp (LBKP), mechanical pulp, wood fibers such as recycled paper pulp, and non-wood fibers such as bamboo.

[0018] The paper base material may also contain known fillers such as white carbon, talc, and kaolin, as well as auxiliary agents such as retention aids, drainage aids, dyes, and pH adjusters.

[0019] The method for producing the paper base material (papermaking) is not particularly limited, and any generally known method can be used.

[0020] The base layer 130 may have other configurations as long as it is mainly composed of paper. Specifically, for example, a functional layer may be provided on the surface of the paper to impart various functions such as water resistance, oil resistance, and water vapor barrier properties. These functional layers are not particularly limited, and can be formed from generally known materials depending on the application of the paper packaging material 100 and the paper packaging body 101.

[0021] The thickness of the base material layer 130 is not particularly limited, and is determined appropriately depending on the intended use of the paper packaging material 100 and the paper packaging body 101 described below, the required strength, and the like.

[0022] [Barrier layer] The barrier layer 141 is a layer for reducing the permeability of, for example, a specific gas component such as oxygen, water vapor, etc. The barrier layer 141 is formed, for example, by directly or indirectly applying a known barrier agent to the surface of the base layer 130.

[0023] The barrier agent is not particularly limited, and a generally known barrier agent can be used. Specific examples of the barrier agent include an aqueous barrier agent containing polyvinylidene chloride (PVDC) as a main component, an aqueous barrier agent containing an ethylene-based copolymer as a main component, an aqueous barrier agent containing an ethylene-vinyl acetate copolymer as a main component, an aqueous barrier agent containing a polyvinyl alcohol (PVA)-silica composite as a main component, an aqueous barrier agent containing a styrene-acrylic resin as a main component, an aqueous barrier agent containing a styrene-butadiene rubber as a main component, an aqueous barrier agent containing an acrylic resin as a main component, an aqueous barrier agent containing an acrylonitrile-butadiene rubber as a main component, an aqueous barrier agent containing polybutylene succinate adipate as a main component, an aqueous barrier agent containing an acrylic urethane composite as a main component, an aqueous barrier agent containing a polyolefin copolymer neutralization salt as a main component, and inorganic materials such as clay. As the barrier agent, one of these may be used alone, or two or more may be used in combination. From the viewpoint of imparting excellent oxygen barrier properties and water vapor barrier properties to the base layer 130, it is preferable to employ a water-based barrier agent containing PVDC as a main component.

[0024] The solids concentration of the barrier agent is not intended to be limited, but from the viewpoint of ensuring good physical properties of the barrier layer, it can be, for example, from 30% by mass to 60% by mass, and preferably from 47% by mass to 51% by mass.

[0025] The pH of the barrier agent is not intended to be limited, but is appropriately adjusted from the viewpoint of ensuring good physical properties of the barrier layer.

[0026] The viscosity of the barrier agent is not intended to be limited, but may be, for example, 5 mPa·s or more and 40 mPa·s or less at 20° C. in order to ensure good physical properties of the barrier layer.

[0027] The thickness of the barrier layer 141, i.e., the coating amount of the barrier agent, is appropriately determined depending on the application of the paper packaging material 100 and the paper packaging body 101, but from the viewpoint of suppressing high costs while ensuring sufficient barrier properties, for example, a coating amount of 1 g / m after drying is set. 2More than 20g / m 2 It can be less than 3 g / m 2 More than 15g / m 2 It is preferable that:

[0028] [Heat seal layer] The heat seal layer 143 is a layer for bonding the paper packaging material 100 to other materials by heat sealing. The heat seal layer 143 is formed by applying a heat sealant to the surface of the barrier layer 141 opposite to the side on which the base material layer 130 is present, via the intermediate layer 142.

[0029] The heat sealing agent is not particularly limited, and generally known heat sealing agents can be used. Specific examples of the heat sealing agent include an aqueous heat sealing agent containing an olefin dispersion as a main component, an aqueous heat sealing agent containing an ethylene copolymer as a main component, an aqueous heat sealing agent containing an ethylene copolymer as a main component, an aqueous heat sealing agent containing an ethylene-acrylic acid copolymer as a main component, an aqueous heat sealing agent containing a styrene-acrylic resin as a main component, an aqueous heat sealing agent containing an acrylic resin as a main component, an aqueous heat sealing agent containing a polyolefin copolymer neutralization salt as a main component, an aqueous heat sealing agent containing a polylactic acid as a main component, an aqueous heat sealing agent containing an ethylene-vinyl acetate copolymer as a main component, an aqueous heat sealing agent containing polybutylene succinate adipate as a main component, and the like. As the heat sealing agent, one of these may be used alone, or two or more may be used in combination. In addition, from the viewpoint of imparting excellent oil resistance, water resistance, and heat sealability to the base layer 130, it is preferable to use an aqueous heat sealing agent containing an olefin dispersion.

[0030] The solid content concentration of the heat-sealing agent is not intended to be limited, but may be, for example, from 15% by mass to 30% by mass in terms of ensuring good physical properties of the heat-sealing layer.

[0031] The pH of the heat-sealing agent is appropriately adjusted from the viewpoint of ensuring good physical properties of the heat-sealing layer, although there is no intention to limit the pH.

[0032] The viscosity of the heat-sealing agent can be, for example, 500 mPa·s or less, or even 50 mPa·s or more and 500 mPa·s or less at 30°C, from the viewpoint of ensuring good physical properties of the heat-sealing layer, although this is not intended to be limiting.

[0033] The thickness of the heat seal layer 143, i.e., the amount of the heat sealant applied, is determined appropriately depending on the application of the paper packaging material 100 and the paper packaging body 101, but from the viewpoint of preventing high costs while ensuring sufficient heat seal strength, it is preferable to use a coating amount of 1 g / m2 after drying. 2 More than 20g / m 2 It can be less than 3 g / m 2 More than 15g / m 2 It is preferable that:

[0034] [Intervening layer] The paper packaging material 100 according to this embodiment is characterized in that it includes an intervening layer 142 between a barrier layer 141 and a heat seal layer 143 .

[0035] The intermediate layer 142 is made of a material containing at least one of a barrier agent which is a material of the barrier layer 141 and a heat seal agent which is a material of the heat seal layer 143. The intermediate layer 142 is preferably a mixed layer made of a mixture of the barrier agent and the heat seal agent.

[0036] By adjusting the ratio of the barrier agent to the total amount of the barrier agent and heat seal agent in the intervening layer 142, the degree of adhesion between the two layers can be adjusted. This makes it possible to achieve both sufficient strength and easy opening of the heat seal portion 110 in the paper package 101 obtained using the paper packaging material 100 (the paper package 101 and the heat seal portion 110 will be described later using FIG. 2). For the sake of convenience in this specification, the term "heat seal strength" refers to the peel strength in the heat seal portion 110 measured by the test method described later.

[0037] From the viewpoint of effectively improving the adhesion between the barrier layer 141 and the heat seal layer 142, the proportion of the barrier agent in the total amount of the barrier agent and the heat seal agent in the intervening layer 142 is preferably 35% by mass or less or 80% by mass or more, more preferably 5% by mass or more and 30% by mass or less or 85% by mass or more and 95% by mass or less, and particularly preferably 10% by mass or more and 30% by mass or less or 85% by mass or more and 90% by mass or less.

[0038] In addition, in relation to the heat sealing temperature described later, when the heat sealing temperature is 140° C. or higher and 150° C. or lower, the above-mentioned ratio is preferably 20% by mass or higher and 30% by mass or lower.

[0039] <Manufacturing method of paper packaging material> The paper packaging material 100 is manufactured by applying, in this order, a coating liquid containing a barrier agent, a coating liquid containing at least one of a barrier agent and a heat-sealing agent (preferably a mixed liquid of a barrier agent and a heat-sealing agent), and a coating liquid containing a heat-sealing agent to at least one surface of the base layer 130, and then drying.

[0040] In addition, if there is another functional layer (for example, a layer that exhibits oil resistance or water resistance) between the base layer 130 and the barrier layer 141, the coating liquid that constitutes the functional layer can be applied to the surface of the base layer 130 before applying the barrier agent.

[0041] The method for applying each coating liquid is not particularly limited, and generally known methods such as gravure, flexography, bar, curtain, air knife, etc. Drying conditions for each layer are not particularly limited, and are appropriately determined depending on each coating liquid.

[0042] <Paper packaging and method for manufacturing paper packaging> Fig. 2 is a diagram showing an example of a paper packaging body 101 according to this embodiment. In Fig. 2, the shape of the paper packaging body 101 is shown as a rectangle in a plan view, but the shape of the paper packaging body 101 is not limited to this rectangle and is appropriately determined depending on the application, etc.

[0043] The paper packaging body 101 shown in FIG. 2 is formed using the paper packaging material 100 described above. The paper packaging body 101 includes a heat-sealed portion 110 and a main body portion 120. Such a paper packaging body 101 is formed from two sheets of paper packaging material 100 shown in FIG. 1(a). Note that the two sheets of paper packaging material 100 shown in FIG. 1(a) have exactly the same configuration except for the different orientations as described above, but the paper packaging body 101 of the present disclosure is not limited to this configuration. Specifically, for example, the two base material layers 130 (first base material layer, second base material layer) constituting the paper packaging body 101 may each be made of a different paper base material.

[0044] A manufacturing method of the paper packaging body 101 will be described. As shown in Fig. 1(a), the lower paper packaging material 100 is placed in the opposite direction (upside down) to the upper paper packaging material 100. Then, as shown in Fig. 1(b), the heat seal layers 143 of the two paper packaging materials 100 are overlapped, and the overlapped portion (the heat seal layers 143 of the two paper packaging materials 100) is heat sealed to form the paper packaging body 101 shown in Fig. 2.

[0045] The article to be packaged is contained in the main body 120 of the paper packaging body 101 formed as described above.

[0046] More specifically, two sheets of paper packaging material 100 are overlapped with their heat-sealed layers 143 facing each other, and then heat-sealed, that is, a predetermined pressure is applied in the direction of the arrow B at a predetermined temperature for a predetermined time. This causes the heat-sealed layer 143 to melt and solidify, forming the heat-sealed portion 110. In this way, the paper packaging body 101 shown in Fig. 1(b) is obtained.

[0047] Here, for example, as shown in FIG. 2, a sheet of paper packaging material 100 having a rectangular shape in plan view is folded in half at a position that will become the bottom side 102 so that the heat seal layer 143 is on the inside, and the side parts 103 other than the bottom side 102 are heat sealed with the packaged item (not shown) housed inside the main body 120. In this way, a paper package 101 is obtained with the packaged item housed in the main body 120. Note that the paper package 101 may be supplied to the market with, for example, one of the side parts 103 not heat sealed and left as an opening. In this case, the user simply places the desired packaged item in the main body 120 and closes the side part 103 that is the opening by a method such as heat sealing.

[0048] The heat sealing conditions are appropriately determined depending on the type of heat sealing agent.

[0049] The heat sealing temperature can be, for example, 120°C or higher and 170°C or lower, and preferably 140°C or higher and 170°C or lower, although there is no intention to limit the same.

[0050] The heat seal pressure is, but is not limited to, for example, 1.0 kgf / cm 2 It can be as follows:

[0051] The heat sealing time can be, for example, not limited to, 0.5 seconds or more and 2 seconds or less.

[0052] <Heat seal strength and peeling behavior> Next, we will explain the strength of the heat-sealed portion 110 of the paper packaging body 101. For example, the strength of the heat-sealed portion 110 (heat seal strength) can be evaluated by carrying out a T-peel test described in Adhesion Evaluation Test 1 described later.

[0053] Here, the inventors of the present application have found that by providing an intervening layer 142 in the paper packaging material 100 and adjusting its components, it is possible to adjust the adhesion between the barrier layer 141 and the heat seal layer 143. And, they have found that when the intervening layer 142 is provided, it is possible to achieve both sufficient strength and easy opening of the heat seal portion 110 of the paper package 101 formed from the paper packaging material 100.

[0054] Specifically, the heat seal strength K1 of the heat seal portion 110 is preferably 5.1 N / 10 mm or less, more preferably 0.5 N / 10 mm or more and 5.0 N / 10 mm or less, and particularly preferably 2.0 N / 10 mm or more and 4.9 N / 10 mm or less, from the viewpoint of achieving both the strength of the heat seal portion and ease of opening.

[0055] Next, the peeling mode will be described. Consider the case where an external force acts in a direction in which the upper paper packaging material 100 and the lower paper packaging material 100 are separated from each other, as indicated by the symbol C in Fig. 1(b).

[0056] When the strength of the heat-sealed portion 110 is high, the adhesion between the intermediate layer 142 and the barrier layer 141, and between the intermediate layer 142 and the heat-sealed layer 143 is high. Therefore, when such an external force is applied, the base material layer 130 is destroyed as shown by the dashed line of symbol P1 (base material destruction). Note that the base material destruction also includes the destruction of the base material layer 130 of the upper paper packaging material 100 in FIG. 1(b).

[0057] On the other hand, when the strength of the heat-sealed portion 110 is low, the adhesion between the intervening layer 142 and the barrier layer 141, and between the intervening layer 142 and the heat-sealed layer 143 is low. Therefore, when such an external force is applied, peeling occurs between the heat-sealed layer 143 and the intervening layer 142 in the lower paper packaging material 100, for example, as shown by the dashed line of symbol P3 (interlayer peeling). This can also occur in the upper paper packaging material 100 in FIG. 1(b).

[0058] Furthermore, when the strength of the heat-sealed portion 110 is somewhere between the strength in which the substrate breaks and the strength in which delamination occurs, both delamination and substrate breakage may occur, as shown by the dashed line P2 in Fig. 1(b). Fig. 1(b) illustrates delamination and substrate breakage occurring in the lower paper packaging material 100, but the same can occur in the upper paper packaging material 100.

[0059] Therefore, in addition to the above-mentioned heat seal strength, peeling morphology (substrate destruction, substrate destruction and delamination, delamination) can be used when evaluating the strength and ease of opening of the heat seal portion 110. The peeling morphology of the heat seal portion 110 is preferably delamination + substrate destruction (P2) or delamination (P3), and more preferably delamination + substrate destruction (P2).

[0060] <Uses of paper packaging materials and paper packaging bodies> The uses of the paper packaging material 100 and the paper packaging body 101 are not particularly limited, and they can be widely used for packaging various items such as food, medicines, daily necessities, electronic parts, industrial parts, etc.

[0061] In addition, in order to be classified as "paper containers and packaging" under the Container and Packaging Recycling Law and to be able to be given a paper mark, it is preferable that the paper content of the paper packaging material 100 and the paper packaging body 101 is 51 mass % or more.

[0062] <Experiment> Next, the concrete experiments carried out will be described.

[0063] Details of the barrier agent (A), heat seal agent (B), and paper substrate (C) used in the experiment are shown below. Also, Figure 3 shows the laminated structures of the barrier layer, heat seal layer, and substrate layer. In this experiment, one of five types of laminated structures (S1 to S5) was adopted depending on each test. In addition, in Figure 3, the barrier layer, heat seal layer, and substrate layer contain the barrier agent (A), heat seal agent (B), and paper substrate (C), respectively, so each layer is represented as "A," "B," and "C." Also, the numbers on the right side of the laminated structures of S1 to S5 indicate the coating amount of the barrier agent (A), heat seal agent (B), and paper substrate (C) after drying.

[0064] <Barrier layer> For the barrier layer, the following barrier agent (A) was used. (A-1) Barrier agent Main component: Polyvinylidene chloride (PVDC) Solid content concentration (mass%): 47 or more and 51 or less pH: 2.0 or more and 4.0 or less Viscosity (mPa s at 20℃): 5 or more and 40 or less (A-2) Barrier agent Main component: Ethylene copolymer Solid content concentration (mass%): 40 or more and 50 or less pH: 5.0 or more and 7.0 or less Viscosity (mPa s at 30℃): 150 or more and 400 or less (A-3) Barrier agent Main component: styrene acrylic Solid content concentration (mass%): 38 pH:8.0 Viscosity (mPa s): 50 (A-4) Barrier agent Main component: styrene acrylic Solid content concentration (mass%): 46.5±1.5 pH: 8.5±1.0 Viscosity (mPa s, below 30℃): 700±500 (A-5) Barrier agent Main component: styrene acrylic Solid content concentration (mass%): 30±1 pH: 8.5±1 Viscosity (mPa s): 100 or less (A-6) Barrier agent Main component: styrene butadiene rubber Solid content concentration (mass%): 54 pH: 11.5 Viscosity (mPa s): 23 (A-7) Barrier agent Main component: styrene acrylic Solid content concentration (mass%): 33 pH: 7.5 or more and 9.5 or less Viscosity (mPa s): 600 (A-8) Barrier agent Main component: Acrylic Solid content concentration (mass%): 40 pH: 7.5 or more and 9.5 or less Viscosity (mPa s): 800 (A-9) Barrier agent Main component: Acrylic resin Solid content concentration (mass%): 39 or more and 40 or less pH: 8 or more and 9 or less Viscosity (mPa s, 60rpm): 200 or more and 300 or less (A-10) Barrier agent Main component: styrene acrylic Solid content concentration (mass%): 45.5±1.0 pH: 8.2±0.5 Viscosity (mPa s, 30rpm): 210±70 <Heat seal layer> For the heat seal layer, the following heat seal agent (B) was used. (B-1) Heat sealant Main component: Olefin dispersion Solid content concentration (mass%): 20 or more and 25 or less pH: 7.5 or more and 9.0 or less Viscosity (mPa s below 30℃): 500 or less (B-2) Heat sealant Main component: Ethylene-vinyl acetate copolymer Solid content concentration (mass%): 40 pH:8.0 Viscosity (mPa s 6rpm): 7000 <Base material layer> (C) Paper base material Main component: Cellulose Thickness: 85μm Basis weight: 60g / m 2

[0065] <Adhesion evaluation test 1> In adhesion evaluation test 1, a sample (paper packaging material) of the laminated structure S1 shown in Fig. 3 was prepared using the above-mentioned barrier agent (A-1), heat seal agent (B-1), and paper base material (C). Two of these samples were bonded together with the heat seal layers of each sample facing each other as described with reference to Fig. 1(a), and heat sealed using the device and conditions shown below to prepare a test piece of the laminated structure shown in Fig. 1(b).

[0066] Heat Sealing Equipment Heat gradient tester manufactured by Toyo Seiki Co., Ltd. Heat sealing conditions Pressure: 1.0kgf / cm 2 , time: 1 second, temperature: 120~170℃

[0067] Next, the above test pieces were subjected to T-peel at a speed of 300 mm / min using a Tensilon universal material testing machine RTC-1210A manufactured by Orientec Co., Ltd., to measure the peel strength (heat seal strength). In addition, the peel morphology after T-peel was observed visually and by FT-IR (Fourier transform infrared spectrophotometer FT / IR-6100 manufactured by JASCO Corporation). The compounding ratio of the coating liquid forming the intervening layer was changed from barrier agent (A-1): heat seal agent (B-1) (mass ratio after drying) = 0:20 to 20:0. The results are shown in Table 1.

[0068] [Table 1]

[0069] It has been found that the degree of adhesion between the barrier layer and the heat seal layer can be adjusted by providing an intervening layer between the barrier layer and the heat seal layer, the intervening layer being made of a material containing at least one of the barrier agent (A-1) and the heat seal agent (B-1), preferably a mixture of the barrier agent (A-1) and the heat seal agent (B-1) in a predetermined blending ratio.

[0070] In particular, when the compounding ratios were 0:20 to 6:14 and 17:3 to 20:0, all test pieces experienced delamination + substrate failure (P2) or delamination (P3) within the above heat sealing temperature ranges, indicating that it is possible to adjust the strength and openability of the heat seal portion by adjusting the compounding ratio.

[0071] In addition, for the experimental examples including the test pieces in which the peeling mode was interlayer peeling of P2 and P3 (see FIG. 2), it was found from the FT-IR spectrum that peeling occurred between the barrier layer (barrier agent (A)) and the intervening layer in experimental examples 1-2 to 1-8 (mixing ratio A-1:B-1 = 1:19 to 7:13), between the heat seal layer (heat seal agent (B)) and the intervening layer in experimental examples 1-17 to 1-20 (mixing ratio A-1:B-1 = 16:4 to 19:1), and between the barrier layer (barrier agent (A)) and the heat seal layer (heat seal agent (B)) in experimental examples 1-1 and 1-21 (mixing ratio A-1:B-1 = 0:20 and 20:0).

[0072] <Adhesion evaluation test 2> In adhesion evaluation test 2, the above-mentioned barrier agent (A-1), heat seal agent (B-1), and paper substrate (C) were used to prepare a sample (paper packaging material) of the laminated structure S2 shown in Fig. 3. Except for this, the heat seal strength was measured and the peeling morphology was observed in the same manner as in adhesion evaluation test 1. The results are shown in Table 2.

[0073] [Table 2]

[0074] In this evaluation test 2, the coating amount of each material was reduced compared to the above-mentioned evaluation test 1. As a result, at a blending ratio of 0:20 to 2:18 or 18:2 to 20:0, in the above-mentioned heat sealing temperature range, delamination + substrate destruction (P2) or delamination (P3) occurred in all test pieces, demonstrating that it is possible to adjust the strength of the heat seal part and the ease of opening by adjusting the blending ratio.

[0075] Compared with the results of Evaluation Test 1, in Evaluation Test 2, when the blending ratio of A-1 was in a smaller range, delamination and substrate failure (P2) or delamination (P3) occurred.

[0076] In addition, for the experimental examples including the test pieces in which the peeling mode was interlayer peeling of P2 and P3, it was found from the FT-IR spectrum that peeling occurred between the barrier layer (barrier agent (A)) and the intervening layer in experimental examples 2-2 and 2-3 (mixing ratio A-1:B-1 = 2:18, 4:16), between the heat seal layer (heat seal agent (B)) and the intervening layer in experimental example 2-10 (mixing ratio A-1:B-1 = 18:2), and between the barrier layer (barrier agent (A)) and the heat seal layer (heat seal agent (B)) in experimental examples 2-1 and 2-11 (mixing ratio A-1:B-1 = 0:20 and 20:0).

[0077] <Adhesion evaluation test 3> In the adhesion evaluation test 3, samples (paper packaging materials) of the laminated structures S2 to S4 shown in FIG. 3 were prepared using the combination of the above barrier agent (A-2) and the heat seal agent (B-1) or heat seal agent (B-2) and the paper substrate (C). The compounding ratio (mass ratio after drying) of the barrier agent (A) and the heat seal agent (B) in the mixed layer of the laminated structure S2 was set to 1:1. Other than this, test pieces were prepared in the same manner as in the adhesion evaluation test 1, and the heat seal strength of each test piece was measured and the peeling form was observed. The results are shown in Table 3.

[0078] [Table 3]

[0079] It was found that the strength of the heat-sealed portion changes depending on the presence or absence of an intervening layer when the barrier agent (A-2) and the heat-sealing agents (B-1 and B-2) are used. This suggests that the strength and openability of the heat-sealed portion can be adjusted by adjusting the compounding ratio of the barrier agent and the heat-sealing agent in the intervening layer in this configuration as well.

[0080] <Adhesion evaluation test 4> In adhesion evaluation test 4, the heat seal strength was measured and the peeling morphology was observed in the same manner as in adhesion evaluation test 1, except that the combination of the above barrier agents (A-3) to (A-8) and the heat seal agent (B-1) and the paper base material (C) were used to form the laminate structure S5 shown in Figure 3. The results are shown in Table 4.

[0081] [Table 4]

[0082] It was also found that interlayer peeling (P3) occurred when no intervening layer was provided in the combination of the barrier agents (A-3) to (A-8) and the heat seal agent (B-1) in Adhesion Evaluation Test 4. This suggests that, in this configuration, it is possible to adjust the strength and openability of the heat seal part by providing an intervening layer and adjusting the compounding ratio of the barrier agent and the heat seal agent in the intervening layer. [Industrial Applicability]

[0083] INDUSTRIAL APPLICABILITY The technology disclosed herein is extremely useful since it can provide a paper packaging material that combines sufficient strength in the heat-sealed portion with ease of opening. [Explanation of symbols]

[0084] 100 Paper packaging material 101 Paper packaging 102 Bottom 103 Side 110 Heat seal section 120 Main body 130 Base material layer (first base material layer, second base material layer) 141 Barrier layer (first barrier layer, second barrier layer) 142 Intervening layer (mixed layer, first intervening layer, second intervening layer) 143 Heat seal layer

Claims

1. The present invention provides a sheet-type adhesive having a base layer made of a paper base material, a barrier layer made of a barrier agent, an intervening layer, and a heat seal layer made of a heat seal agent, in this order; the intermediate layer is made of a material containing at least one of the barrier agent and the heat seal agent, The proportion of the barrier agent in the total amount of the barrier agent and the heat sealing agent in the intervening layer is 35% by mass or less, or 80% by mass or more, in terms of mass ratio after drying. A paper packaging material characterized by:

2. The barrier agent is an aqueous barrier agent containing polyvinylidene chloride as a main component, The solid content concentration of the barrier agent is 40% by mass or more and 55% by mass or less, The viscosity (20° C.) of the barrier agent is 5 mPa·s or more and 40 mPa·s or less.

2. The paper packaging material according to claim 1.

3. The heat-sealing agent is an aqueous heat-sealing agent containing an olefin-based dispersion as a main component, The solid content concentration of the heat-sealing agent is 15% by mass or more and 30% by mass or less, The viscosity of the heat sealing agent (at 30° C.) is 500 mPa·s or less.

2. The paper packaging material according to claim 1.

4. The intermediate layer is a mixed layer made of a mixture of the barrier agent and the heat seal agent.

2. The paper packaging material according to claim 1.

5. The proportion of the barrier agent in the total amount of the barrier agent and the heat sealing agent in the mixed layer is 5% by mass or more and 30% by mass or less, or 85% by mass or more and 95% by mass or less, in terms of mass ratio after drying.

5. The paper packaging material according to claim 4.

6. A method for producing a paper packaging body using the paper packaging material according to any one of claims 1 to 5 as a raw material, The paper packaging body is obtained by heat-sealing a part of the paper packaging material and another part of the paper packaging material or two sheets of the paper packaging material in a state where the heat-seal layers of each paper packaging material face each other. A method for producing a paper packaging body comprising the steps of:

7. A paper packaging body having a heat seal portion, the heat seal portion has a laminated structure including, in this order, a first base material layer made of a paper base material, a first barrier layer made of a barrier agent, a first intermediate layer, a heat seal layer made of a heat seal agent, a second intermediate layer, a second barrier layer made of the barrier agent, and a second base material layer made of the paper base material or another paper base material; the first intermediate layer and the second intermediate layer are made of a material containing at least one of the barrier agent and the heat seal agent, The proportion of the barrier agent in the total amount of the barrier agent and the heat sealing agent in the first and second intermediate layers is 35% by mass or less, or 80% by mass or more, in terms of mass ratio after drying. A paper packaging material characterized by:

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