JP2021062916A - Pouch - Google Patents

Abstract

To provide a pouch capable of suppressing breakage of the pouch and stably venting steam when heated in a microwave oven.SOLUTION: In a pouch 10, a wrapping material includes a first biaxially stretched plastic film, a second biaxially oriented plastic film, and a sealant film in this order. The sealant film has polypropylene as a main component. There are only two biaxially stretched plastic films in the wrapping material. A seal part 15 is provided with a steam vent seal part 24 configured so as to peel off by an increase in pressure of a storage space 10A. The pouch 10 is configured to peel off the steam vent seal part 24 and to vent steam. The wrapping material is held for one minute under a 100°C atmosphere and has uni-directional breaking strength when measured under the 100°C atmosphere is 33.0 MPa or above. Seal intensity of the seal part 15 when measured under the 100°C atmosphere after being held for one minute under the 100°C atmosphere is 20.0 N or below.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pouch.

Conventionally, standing type pouches that can be heated in a microwave oven and can accommodate contents such as retort foods and frozen foods have been widely used. Such a pouch is configured to be self-supporting in a microwave oven, and is provided with a steam venting mechanism that automatically releases the steam generated by heating in the microwave oven to the outside of the pouch (for example,). See Patent Document 1).

Patent No. 4029590

When such a pouch is heated in a microwave oven, excessive pressure is applied, steam cannot be removed from the steam bleeding mechanism, the pouch may break, and even if the pouch does not break, a part other than the steam bleeding mechanism May open.

The present invention has been made to solve the above problems. It is an object of the present invention to provide a pouch that can suppress the pouch from breaking when heated in a microwave oven and can stably remove steam.

The present invention includes the following inventions.
[1] A pouch containing a packaging material and having a storage space, wherein the packaging material includes a first biaxially stretched plastic film, a second biaxially stretched plastic film, and a sealant film in this order. The sealant film contains polypropylene as a main component, the packaging material contains only two biaxially stretched plastic films, and the pouch is provided with a sealing portion for sealing the pouch. The pouch is provided with a steam venting seal portion configured to be peeled off by an increase in pressure, and the pouch is configured so that the steam venting seal portion can be peeled off to release steam, and the packaging material is 100. The unidirectional breaking strength when measured in an environment of 100 ° C. after holding for 1 minute in an environment of ° C. is 33.0 MPa or more, and after holding for 1 minute in an environment of 100 ° C., 100 ° C. A pouch having a seal strength of 20.0 N or less when measured in an environment.

[2] The pouch according to the above [1], wherein the product of the tensile elongation (%) and the thickness (μm) of the sealant film in the one direction exceeds 50,000.

[3] The pouch according to the above [1] or [2], wherein the product of the tensile elongation (%) and the thickness (μm) of the sealant film in the direction orthogonal to the one direction exceeds 55,000.

[4] The pouch according to any one of the above [1] to [3], wherein the sealant film contains a propylene / ethylene block copolymer and an elastomer.

[5] The first biaxially stretched plastic film is a biaxially stretched polyethylene terephthalate film, and the second biaxially stretched plastic film is a biaxially stretched polyethylene terephthalate film or a biaxially stretched nylon film. ] To the pouch according to any one of [4].

[6] The packaging material further includes a transparent vapor-deposited layer provided between the first biaxially stretched plastic film and the second biaxially stretched plastic film, and the transparent vapor-deposited layer is a metal oxide or an inorganic substance. The pouch according to any one of the above [1] to [5], which contains an oxide.

[7] The pouch according to the above [6], wherein the packaging material further includes a transparent gas barrier coating film provided on the surface of the transparent vapor deposition layer.

[8] The packaging material further includes a light-shielding printing layer provided between the first biaxially stretched plastic film and the sealant film, and the total light transmittance of the packaging material is 25.0% or less. The pouch according to any one of the above [1] to [7].

[9] The pouch according to the above [8], wherein the ^{L * value in the L *} a ^* b ^* color system measured by the SCE method (specular reflection light removal method) of the packaging material is 65.0 or more.

[10] The pouch according to any one of the above [1] to [9], wherein the contents are housed in the storage space of the pouch.

According to one aspect of the present invention, it is possible to provide a pouch that can suppress bag breakage of the pouch and can stably remove steam when heated in a microwave oven.

FIG. 1 is a front view of the pouch according to the embodiment. FIG. 2 is a diagram for explaining the dimensions of each component of the pouch shown in FIG. FIG. 3 is a cross-sectional view of the packaging material used for the pouch. FIG. 4 is a view when a test piece for measuring the hot breaking strength of the packaging material is cut out from the front surface of the pouch. FIG. 5 is a view when a test piece for measuring the hot breaking strength of the packaging material is cut out from the back surface of the pouch. FIG. 6 is a diagram showing how the hot breaking strength is measured using the test piece. FIG. 7 is a diagram when a test piece for measuring the hot seal strength of the packaging material is cut out from the pouch. FIG. 8 is a diagram showing how the hot seal strength is measured using the test piece. FIG. 9 is a diagram for explaining the hot seal strength (maximum tensile strength). FIG. 10 is a cross-sectional view of another packaging material used for the pouch. FIG. 11 is a view when a test piece for measuring the total light transmittance of the packaging material is cut out from the front surface of the pouch. FIG. 12 is a view when a test piece for measuring the total light transmittance of the packaging material is cut out from the back surface of the pouch. ^{FIG. 13 is a diagram when a test piece for measuring the L *} value of the packaging material is cut out from the front surface of the pouch.

Hereinafter, the pouch according to the embodiment of the present invention will be described with reference to the drawings. In the present specification, terms such as "film" and "sheet" are not distinguished from each other based only on the difference in designation. Therefore, for example, "film" is used in the sense of including a member which is also called a sheet. FIG. 1 is a front view of the pouch according to the embodiment, FIG. 2 is a view for explaining the dimensions of each component of the pouch shown in FIG. 1, and FIG. 3 is a packaging material used for the pouch. It is a cross-sectional view of. FIG. 4 is a diagram when a test piece for measuring the hot breaking strength of the packaging material is cut out from the front surface of the pouch, and FIG. 5 is a test for measuring the hot breaking strength of the packaging material. It is a figure when a piece is cut out from the back surface of a pouch, and FIG. 6 is a figure which shows the state of measuring the hot breaking strength using a test piece. FIG. 7 is a diagram when a test piece for measuring the hot seal strength of the packaging material is cut out from the pouch, and FIG. 8 is a diagram showing how the test piece is used to measure the hot seal strength. , FIG. 9 is a diagram for explaining the hot seal strength (maximum tensile strength). FIG. 10 is a cross-sectional view of another packaging material used for the pouch, and FIG. 11 is a view when a test piece for measuring the total light transmittance of the packaging material is cut out from the front surface of the pouch. , FIG. 12 is a diagram when a test piece for measuring the total light transmittance of the packaging material is cut out from the front surface of the pouch, and FIG. 13 is a diagram ^{for measuring the L *} value of the packaging material. It is a figure when a piece is cut out from the front surface of a pouch.

<<< Pouch >>>
The pouch 10 shown in FIG. 1 is a standing type pouch and has a storage space 10A for accommodating the contents. The contents include, but are not limited to, solids, liquids, or mixtures thereof. Examples of the contents include cooked foods such as curry, stew, and soup. The cooked food may be subjected to a heat sterilization treatment such as a boiling treatment or a retort treatment. That is, heat sterilized foods and pressure heat sterilized foods may be contained as the contents. The "retort treatment" is a treatment in which the pouch is filled with the contents, the pouch is sealed, and then the pouch is heated in a pressurized state using steam or heated hot water. The temperature of the retort treatment is, for example, 120 ° C. or higher. The pouch is a concept that includes not only a pouch that is not filled with contents but also a pouch that is filled with contents.

The pouch 10 shown in FIG. 1 has a front surface film 11, a back surface film 12, and a bottom surface film 13. The front surface film 11 and the back surface film 12 have a rectangular contour. In the state shown in FIG. 1, the bottom film 13 is folded in half.

The pouch 10 has an upper portion 10B, a bottom portion 10C opposite to the upper portion 10B, a first side portion 10D and a second side portion 10E extending between the upper portion 10B and the bottom portion 10C. The second side portion 10E is a side portion opposite to the first side portion 10D. Further, the positions of "top", "bottom", "side", and "bottom" in the present specification mean the positions of the pouch in a self-supporting state.

The ratio (H / W1) of the height H (see FIG. 2) of the pouch 10 to the width W1 of the pouch 10 (see FIG. 2) is preferably 0.6 or more and 2.0 or less. If H / W1 is 0.6 or more, more contents can be accommodated, and if H / W1 is 2.0 or less, the pouch 10 can be stably made to stand on its own before opening. .. The height H of the pouch 10 is the length from the lower edge 10G of the pouch 10 to the upper edge 10F of the pouch 10 in the Y direction DRY parallel to the direction in which the first side seal portion 16 described later extends. If the length of the pouch is not constant, the height of the pouch shall be the largest value. The width W1 of the pouch 10 is the length from the side edge 10H on the first side portion 10D side of the pouch 10 to the side edge 10I of the second side portion 10E in the X direction DRX orthogonal to the Y direction DRY. If the pouch width W1 is not constant, the pouch width is set to the shortest value. The dimensions of the pouch and the dimensions of each component constituting the pouch in the present embodiment are all measured values in a state where the pouch is substantially flat without expanding the bottom gusset portion of the pouch. The lower limit of H / W1 may be 0.70 or more, 0.75 or more, 0.80 or more, 0.85 or more, or 0.90 or more, and the upper limit of H / W1 is 1.90. Hereinafter, it may be 1.80 or less, 1.70 or less, 1.60 or less, or 1.50 or less.

As shown in FIG. 1, the pouch 10 has a bottom gusset portion 14 folded in a gusset method on the bottom portion 10C side. The pouch 10 shown in FIG. 1 is a standing type pouch, but the pouch may be a flat pouch (flat pouch).

<Bottom gusset part>
The bottom gusset portion 14 is composed of a part of the front surface film 11, a part of the back surface film 12, and a bottom surface film 13. The bottom film 13 is divided into a first portion and a second portion via a folding line 14A. The first fold portion is formed by a part of the front surface film 11 and the first portion of the bottom surface film 13, and the second fold portion is formed by a part of the back surface film 12 and the second portion of the bottom surface film 13. .. By providing the bottom gusset portion 14, it is possible to accommodate a larger content, increase the capacity of the content, and make the pouch 10 self-supporting.

In the Y-direction DRY, the ratio (W2 / H) of the folding width W2 (see FIG. 2) of the bottom gusset portion 14 to the height H of the pouch 10 is preferably 0.1 or more and 0.5 or less. If the W2 / H is 0.1 or more, more contents can be accommodated. Further, when W2 / H is 0.5 or less, when the pouch 10 is made to stand on its own, the pouch can be made to stand on its own in a stable manner. The folding width W2 of the bottom gusset portion 14 is the length of the bottom gusset portion 14 in the Y direction DRY. Specifically, it is the length from the lower edge 10G of the bottom 10C to the folding line 14A. If the width of the bottom gusset is not constant, the width of the bottom gusset shall be the shortest value. The lower limit of W2 / H is more preferably 0.15 or more or 0.20 or more, and the upper limit of W2 / H is 0.45 or less, 0.40 or less, 0.35 or less, or 0. It is more preferably .30 or less. The folding width W2 of the bottom gusset portion 14 may be 20 mm or more and 50 mm or less. It is more preferable that the lower limit of the folding width W2 of the bottom gusset portion 14 is 25 mm or more, 30 mm or more, 35 mm or more, or 40 mm or more.

As shown in FIG. 1, the pouch 10 includes a sealing portion 15 for sealing the pouch 10. The seal portion 15 of the pouch 10 is formed on the first side seal portion 16 formed on the first side portion 10D, the second side seal portion 17 formed on the second side portion 10E, and the bottom portion 10C. The first bottom seal portion 18 and the second bottom seal portion 19, the bottom auxiliary seal portions 20 formed on the side edges 10H and 10I, respectively, and the pouch 10 are configured to be separated by increasing pressure in the accommodation space 10A. It is provided with a steam venting seal portion 24. Although the upper part of the pouch 10 is open in FIG. 1, the contents are filled in the accommodation space 10A and then heat-sealed to form an upper seal surrounded by the upper edge 10F and the alternate long and short dash line in FIG. An upper seal portion is formed in the planned portion R, and the pouch 10 is sealed. When the upper seal portion is formed, the width W5 (see FIG. 2) of the upper seal portion is preferably 2 mm or more and 15 mm or less, for example. The lower limit of the width W5 of the upper seal portion is more preferably 3 mm or more, 4 mm or more, or 5 mm or more, and the upper limit is more preferably 14 mm or less, 13 mm or less, or 12 mm or less.

<1st side seal part and 2nd side seal part>
The first side portion sealing portion 16 is a portion where the front surface film 11 and the back surface film 12 are joined to each other in the first side portion 10D, and is formed from the folding line 14A to the upper edge 10F. The second side seal portion 17 is a portion where the front surface film 11 and the back surface film 12 are joined to each other in the second side portion 10E, and is formed from the folding line 14A to the upper edge 10F of the pouch 10. There is. The front surface film 11 and the back surface film 12 are joined by heat sealing (heat fusion) when the first side sealing portion 16 and the second side sealing portion 17 are formed.

The width W3 (see FIG. 2) of the first side seal portion 16 and the second side seal portion 17 is preferably, for example, 2 mm or more and 15 mm or less, respectively. If the width W3 of the first side seal portion 16 and the second side seal portion 17 is 2 mm or more, the first side seal portion 16 and the second side seal portion 17 can be reliably sealed. Further, if it is 15 mm or less, a wider accommodation space 10A can be secured. In the present specification, the "width" in each seal portion means the length in the direction orthogonal to the extending direction of the seal portion. If the width of the seal portion is not constant, the width of the seal portion is set to the shortest value among the lengths in the direction orthogonal to the extending direction of the seal portion. The lower limit of the width W3 is more preferably 4 mm or more or 6 mm or more, and the upper limit is more preferably 12 mm or less, 10 mm or less, or 8 mm or less.

<1st bottom seal part and 2nd bottom seal part>
The first bottom sealing portion 18 is a portion where a part of the front surface film 11 and a part of the bottom film 13 are joined to each other, and the second bottom sealing portion 19 is a portion of the back surface film 12 and the bottom film 13. It is a part where a part of is joined to each other. The first bottom sealing portion 18 is formed by heat-sealing the front surface film 11 and the bottom film 13, and the second bottom sealing portion 19 heat-seals the back surface film 12 and the bottom film 13. It is formed by

<Bottom auxiliary seal part>
The bottom auxiliary seal portion 20 is formed below the folding line 14A and includes the side edges 10H and 10I of the pouch 10. The bottom auxiliary seal portion 20 is a portion where the front surface film 11 and the back surface film 12 are joined to each other. The bottom auxiliary seal portion 20 is formed by heat-sealing the front surface film 11 and the back surface film 12 through a notch provided in the bottom surface film 13. Therefore, when the contents are filled, the pouch 10 can be made to stand on its own without hindering the spread of the bottom film 13. Instead of the notch, a through hole may be provided in the bottom film 13.

As shown in FIG. 1, the first side sealing portion 16 and the second side sealing portion 17 are provided with opening starting means 21 which can serve as a starting point at the time of opening. The opening start means 21 may be provided on either the first side seal portion 16 or the second side seal portion 17.

<< Opening start means >>
The opening start means 21 can serve as a starting point when opening the pouch 10. The pouch 10 can be opened by grasping the first side seal portion 16 or the second side seal portion 17 above the one opening start means 21 and pulling it toward the front or pushing it toward the back side. Examples of the opening start means 21 include a notch, a notch, and the like. The opening start means 21 shown in FIG. 1 is a notch.

The first side portion 10D of the pouch 10 is provided with a steam venting mechanism 22 for releasing the steam in the pouch 10 to the outside when the pressure in the pouch 10 is increased by the steam generated by heating by the microwave oven. ing.

<< Steam removal mechanism >>
The steam venting mechanism 22 shown in FIG. 1 isolates the unsealed first unsealed portion 23 and the first unsealed portion 23 isolated from the accommodating space 10A from the accommodating space 10A, and seals the first side portion. It is composed of a steam venting seal portion 24 protruding from the portion 16 toward the accommodation space 10A.

<1st unsealed part>
The first unsealed portion 23 has an opening 23A that serves as a steam port that reaches the side edges of the front surface film 11 and the back surface film 12, and communicates with the outside through the opening 23A.

<Steam vent seal part>
The steam vent seal portion 24 is connected to the first side seal portion 16 in series. One end of the steam venting seal portion 24 shown in FIG. 1 is connected to the upper portion 16A of the first side portion sealing portion 16, and the other end is connected to the lower portion 16B. As a result, the first unsealed portion 23 is isolated from the accommodation space 10A. The width W4 (see FIG. 2) of the steam vent seal portion 24 is set to, for example, 2.5 mm or more and 6 mm or less. The lower limit of the width W4 of the steam vent seal portion 24 is more preferably 3.0 mm or more, 3.5 mm or more, or 4.0 mm or more, and the upper limit is 5.5 mm or less. preferable.

The steam venting seal portion 24 is peeled off when the pressure in the pouch 10 reaches a predetermined pressure due to heating, whereby the accommodating space 10A and the first unsealed portion 23 communicate with each other to form an accommodating space. The steam in 10A is automatically discharged to the outside of the pouch 10 via the first unsealed portion 23. Further, since the steam venting seal portion 24 projects closer to the accommodation space 10A than the first side sealing portion 16, the steam venting seal portion 24 when the pressure in the pouch 10 increases due to heating in the microwave oven. Stress tends to concentrate on 24. Further, since the peeling easily proceeds from the steam vent seal portion 24, it is possible to suppress the peeling from the first side seal portion 16 and the like.

The steam bleeding mechanism 22 may be configured so that the steam bleeding seal portion 24 can be peeled off to bleed steam, and is not limited to the above example.

Further, in the pouch 10, a second unsealed portion 25 is formed on the second side sealed portion 17, and this is because the first unsealed portion 23 is fronted when the pouch 10 is manufactured. It is provided to ensure that the opening 23A is formed on the side edges of the front surface film 11 and the back surface film 12. That is, the second unsealed portion 25 is provided to increase the manufacturing efficiency of the pouch 10. The second unsealed portion 25 reaches the side edges of the front surface film 11 and the back surface film 12 and is opened. The second unsealed portion 25 does not necessarily have to be provided.

<< Packaging material >>
The front surface film 11 and the back surface film 12 are composed of the packaging material 30 shown in FIG. Further, the bottom film 13 may be composed of the packaging material 30 shown in FIG. The packaging material 30 includes at least a first biaxially stretched plastic film 31, a second biaxially stretched plastic film 32, and a sealant film 33 in this order. The packaging material 30 does not include a metal leaf layer. The packaging material 30 has only two biaxially stretched plastic films in the packaging material 30. The sealant film 33 is a layer constituting the inner surface of the pouch 10. The packaging material 30 shown in FIG. 3 is, for example, a first biaxially stretched plastic film 31, a pattern printing layer 34, a first adhesive layer 35, a second biaxially stretched plastic film 32, and a second adhesive layer 36. And the sealant film 33 is provided in this order. The packaging material may further include a functional layer exhibiting a desired function between the first biaxially stretched plastic film 31 and the sealant film 33. Examples of the functional layer include a transparent thin-film deposition layer and a transparent gas barrier coating film. The pouch 10 can be manufactured while continuously transporting the packaging material 30 wound in a roll shape.

The packaging material 30 has a unidirectional breaking strength (hot breaking strength) of 33.0 MPa or more when measured in an environment of 100 ° C. after being held for 1 minute in an environment of 100 ° C. The unidirectional hot breaking strength of the packaging material 30 is preferably 36.0 MPa or more, more preferably 39.0 MPa or more, further preferably 42.0 or more, and 45.0 MPa or more. Is particularly preferable. The hot breaking strength of the packaging material 30 in the direction orthogonal to one direction is preferably 29.0 MPa or more, more preferably 32.0 MPa or more, still more preferably 35.0 MPa or more. Most preferably, it is 38.0 MPa or more. The hot breaking strength in the one direction of the packaging material 30 is preferably 50.0 MPa or less, and the hot breaking strength of the packaging material 30 in the direction orthogonal to the one direction is 45.0 MPa or less. Is preferable. One direction of the packaging material 30 may be, for example, the X-direction DRX in the pouch 10 (see FIG. 1), and the direction orthogonal to one direction of the packaging material 30 may be, for example, the Y-direction DRY in the pouch 10. Further, for example, the flow direction (MD) of the packaging material 30 may correspond to the X direction DRX of the pouch 10, and the width direction (TD) of the packaging material 30 may correspond to the Y direction DRY of the pouch 10. Further, for example, one direction of the packaging material 30 may correspond to the flow direction (MD), and for example, the direction orthogonal to one direction of the packaging material may correspond to the width direction (TD).

The hot breaking strength of the packaging material 30 shall be measured in accordance with JIS K7127 except for the lengths of the test pieces S1 and S2, which will be described later. First, from the front surface film 11 of the pouch 10, one side L1 (see FIG. 4) is 15 mm, and the other side L2 (see FIG. 4) extending in a direction orthogonal to one side L1 is formed so as not to include the seal portion 15. Cut out five 100 mm rectangular test pieces S1 (see FIG. 4). The test piece S1 is cut out so that the other side L2 is parallel to the X direction DRX (the direction orthogonal to the direction in which the first side seal portion 16 extends). Subsequently, from the back film 12 of the pouch 10, one side L1 (see FIG. 5) is 15 mm, and the other side L2 (see FIG. 5) extending in a direction orthogonal to one side L1 is 100 mm so as not to include the sealing portion 15. Cut out five rectangular test pieces S2 (see FIG. 5). The test piece S2 is cut out so that the other side L2 is parallel to the Y direction DRY (the direction parallel to the direction in which the first side seal portion 16 extends). Then, the hot breaking strength of the test piece S1 is measured using the Tencilon universal material testing machine RTC-1310A (manufactured by A & D Co., Ltd.). Specifically, first, as shown in FIG. 6, the grippers 51 and 52 grip both ends of the test piece S1 in the longitudinal direction. In FIG. 6, the layer structure of the test pieces S1 and S2 is partially omitted. Then, after holding the test piece S1 for 1 minute in an environment of a temperature of 100 ° C. and a relative humidity of 5%, the initial gripping tool distance D1 (see FIG. 6) is set to 50 mm in an environment of a temperature of 100 ° C. and a relative humidity of 5%. In this state, a tensile test is performed in which the test piece S1 is pulled in the longitudinal direction of the test piece S1 at a tensile speed of 300 mm / min, and the hot breaking strength of the test piece S1 is measured. The hot breaking strength of the test piece S2 is also measured under the same measurement conditions as the test piece S1. Then, the hot breaking strength of the five test pieces S1 is measured, and the average value thereof is taken as the hot breaking strength of the packaging material 30 in the X direction DRX. Further, the hot breaking strengths of the five test pieces S2 are measured, and the average value thereof is taken as the hot breaking strength of the packaging material 30 in the Y direction DRY.

The packaging material 30 has a sealing strength (hot sealing strength) of 20.0 N or less when measured in an environment of 100 ° C. after being held in an environment of 100 ° C. for 1 minute. The hot seal strength is preferably 15.0 N or less, more preferably 12.0 N or less, and further preferably 10.0 N or less. Further, if the hot seal strength is too low, it is considered that the steam venting seal portion 24 is peeled off before the contents are sufficiently heated and pressurized, and the pressure and temperature of the accommodation space 10A are lowered. Be done. Considering this point, the hot seal strength of the seal portion 15 of the pouch 10 is preferably 4 N or more, more preferably 5 N or more. The seal strength of the steam venting seal portion 24 may be changed by a sterilization treatment such as a retort treatment, but when the pouch 10 is subjected to the retort treatment, unless otherwise specified, the “seal strength of the seal portion”. Means the sealing strength of the sealing portion in the pouch after the retort treatment is applied.

In measuring the hot seal strength of the packaging material 30, first, one pouch is prepared. The pouch includes the first side seal portion 16 or the second side seal portion 17, and has a side L3 (see FIG. 7) of 15 mm and a side L3 in a state where the front surface film 11 and the back surface film 12 are joined. Five rectangular test pieces S3 (see FIG. 7) having an other side L4 (see FIG. 7) extending in the orthogonal direction and having a 70 mm diameter are cut out. For example, as shown in FIG. 7, three test pieces S3 are cut out so as to include the first side seal portion 16 and two test pieces S3 are cut so as to include the second side seal portion 17. The first test piece S3 is provided so that the other side L4 is parallel to the X direction DRX (the direction orthogonal to the direction in which the first side seal portion 16 extends) and does not include the steam vent seal portion 24. Cut out three from the side seal portion 16 side and two from the second side seal portion 17 side. The hot seal strength is measured using this test piece S3. The hot seal strength is measured using a Tencilon universal material tester RTC-1310A (manufactured by A & D Co., Ltd.) in accordance with JIS Z1707: 1997 7.5. First, the two packaging materials 30 in the unsealed portion of the test piece S3 are gripped by the gripping tools 53 and 54 (see FIG. 8) of the testing machine, respectively. In FIG. 8, the layer structure of the test piece S3 is partially omitted. Then, the grippers 53 and 54 are pulled in opposite directions in the direction orthogonal to the surface direction of the seal portion of the test piece S3 at a speed of 300 mm / min, and the maximum value of the tensile stress is measured. Then, the average value of the maximum values is taken as the seal strength (see FIG. 9). The measurement of the hot seal strength is performed in an environment of 100 ° C. and a relative humidity of 5% after holding the test piece S3 in an environment of a temperature of 100 ° C. and a relative humidity of 5% for 1 minute. The hot seal strength of the five test pieces S3 is measured, and the average value is taken as the hot seal strength of the pouch.

<Biaxially stretched plastic film>
The biaxially stretched plastic film is a plastic film that has been intentionally stretched in order to improve the mechanical strength of the plastic film. In the present invention, the biaxially stretched plastic film refers to a film that satisfies at least one of the following (a) and (b).
(A) Young's modulus is 1000 MPa or more in one direction and in the direction orthogonal to one direction (b) 200% or less in the direction where tensile elongation is orthogonal to one direction and one direction

The Young's modulus and tensile elongation of the biaxially stretched plastic film shall be measured in accordance with JIS K7127. Using the Tencilon universal material tester RTC-1310A (manufactured by A & D Co., Ltd.), the test piece was held for 1 minute in an environment with a temperature of 25 ° C and a relative humidity of 50%, and then the temperature was 25 ° C and the relative humidity was 50. The Young ratio and tensile elongation of the test piece are measured in an environment of%. The measurement is performed using a rectangular test piece having a side of 15 mm and an other side extending in a direction orthogonal to one side of 150 mm, and the initial distance between the gripping tools is 100 mm and the tensile speed is 300 mm / min. As long as the distance between the initial grippers can be measured as 100 mm, the length in the direction orthogonal to one side can be adjusted.

(First biaxially stretched plastic film)
The first biaxially stretched plastic film 31 is a plastic film stretched in two predetermined directions. The first biaxially stretched plastic film 31 functions as a base film for imparting a predetermined strength to the packaging material 30. The stretching direction of the first biaxially stretched plastic film 31 is not particularly limited. For example, the first biaxially stretched plastic film 31 may be stretched in the direction in which the side edge 10H extends and in the direction orthogonal to this direction. The draw ratio of the first biaxially stretched plastic film 31 is, for example, 1.05 times or more.

The first biaxially stretched plastic film 31 preferably contains polyester as a main component. By "containing polyester as a main component" in the present specification, it means that the biaxially stretched plastic film contains more than 50% by mass of polyester. Examples of polyester include polyethylene terephthalate (hereinafter, also referred to as PET), polybutylene terephthalate (hereinafter, also referred to as PBT) and the like. The polyester exceeding 50% by mass in the first biaxially stretched plastic film 31 may be composed of one kind of polyester or two or more kinds of polyester. As the first biaxially stretched plastic film, a biaxially stretched PET film can be used. The biaxially stretched PET film preferably contains 80% by mass or more of PET. Further, the biaxially stretched PET film more preferably contains 90% by mass or more of PET, and further preferably contains 95% or more of PET.

The thickness of the first biaxially stretched plastic film 31 is preferably 8 μm or more, more preferably 9 μm or more, and further preferably 12 μm or more. The thickness of the first biaxially stretched plastic film 31 is preferably 30 μm or less, more preferably 25 μm or less, and further preferably 20 μm or less. By making the thickness of the first biaxially stretched plastic film 31 8 μm or more, the first biaxially stretched plastic film 31 has sufficient strength. Further, by reducing the thickness of the first biaxially stretched plastic film 31 to 30 μm or less, the first biaxially stretched plastic film 31 exhibits excellent moldability. Therefore, the step of processing the packaging material 30 to manufacture the pouch 10 can be efficiently performed.

(Second biaxially stretched plastic film)
The second biaxially stretched plastic film 32 is, for example, a base film that is stretched in predetermined two directions, similarly to the first biaxially stretched plastic film 31. For example, the second biaxially stretched plastic film 32 may be stretched in the direction in which the side edge 10H extends and in the direction orthogonal to this direction. The second biaxially stretched plastic film 32 also functions as a base film for giving the packaging material 30 a predetermined strength, like the first biaxially stretched plastic film 31. The stretching direction of the second biaxially stretched plastic film 32 is also not particularly limited as in the case of the first biaxially stretched plastic film 31.

The second biaxially stretched plastic film 32 is preferably a biaxially stretched plastic film containing polyamide as a main component or a biaxially stretched plastic containing polyester as a main component. By "containing polyamide as a main component" in the present specification, it means that the second biaxially stretched plastic film contains more than 50% by mass of polyamide. Examples of polyamides include aliphatic polyamides and aromatic polyamides. Examples of the aliphatic polyamide include nylon such as nylon-6, nylon-6,6, and a copolymer of nylon 6 and nylon 6,6, and examples of the aromatic polyamide include polymethoxylen adipamide (polymethoxylen adipamide). MXD6) and the like. Since the second biaxially stretched plastic film 32 contains polyamide as a main component, the piercing strength of the packaging material 30 including the second biaxially stretched plastic film 32 can be increased. Examples of polyesters include the polyesters listed in the column for the first biaxially stretched plastic film. As the second biaxially stretched plastic film, a biaxially stretched nylon film or a biaxially stretched polyethylene terephthalate film can be used. The biaxially stretched nylon film preferably contains 80% by mass or more of polyamide. Further, the biaxially stretched nylon film more preferably contains 90% by mass or more of polyamide, and further preferably contains 95% or more of polyamide.

The thickness of the second biaxially stretched plastic film 32 is preferably 12 μm or more, more preferably 15 μm or more. The thickness of the second biaxially stretched plastic film 32 is preferably 30 μm or less, more preferably 25 μm or less, and further preferably 20 μm or less.

The second biaxially stretched plastic film 32 may be configured to have tearability in the flow direction (MD). In the following description, a biaxially stretched plastic film having tearability in the flow direction (MD) is also referred to as a biaxially stretched straight sheet film. By using the biaxially stretched straight-line cut film, the packaging material 30 can be provided with tearability in the flow direction (MD). The tensile strength of the biaxially stretched straight sheet film in the flow direction (MD) is larger than the tensile strength of the biaxially stretched straight sheet film in the width direction (TD). The tensile strength of the biaxially stretched straight sheet film in the flow direction (MD) is preferably 1.05 times or more, more preferably 1.10 times the tensile strength of the biaxially stretched straight sheet film in the width direction (TD). It is more than double, more preferably 1.20 times or more. Further, the tensile strength of the biaxially stretched straight-line cut film in the flow direction (MD) is, for example, 200 MPa or more and 300 MPa or less.

<Sealant film>
Next, the sealant film 33 will be described. The sealant film 33 may be a single layer or a multilayer. The sealant film 33 is preferably made of an unstretched film. The term "unstretched" is a concept that includes not only a film that is not stretched at all but also a film that is slightly stretched due to the tension applied during film formation.

The sealant film refers to a film that satisfies at least one of the following (c) and (d).
(C) Young's modulus is less than 1000 MPa in one direction and in the direction orthogonal to one direction (d) 300% or more in the direction in which tensile elongation is orthogonal to one direction and one direction

The Young's modulus and tensile elongation of the sealant film shall be measured in accordance with JIS K7127. Using the Tencilon universal material tester RTC-1310A (manufactured by A & D Co., Ltd.), the test piece was held for 1 minute in an environment with a temperature of 25 ° C and a relative humidity of 50%, and then the temperature was 25 ° C and the relative humidity was 50. The Young ratio and tensile elongation of the test piece are measured in an environment of%. The measurement is performed using a rectangular test piece having a side of 15 mm and an other side extending in a direction orthogonal to one side of 150 mm, and the initial distance between the gripping tools is 100 mm and the tensile speed is 300 mm / min. As long as the distance between the initial grippers can be measured as 100 mm, the length in the direction orthogonal to one side can be adjusted.

The pouch 10 made of the packaging material 30 is subjected to a sterilization treatment such as a retort treatment at a high temperature. Therefore, as the sealant film 33, one having heat resistance to withstand these treatments at high temperatures is used.

The melting point of the material constituting the sealant film 33 is preferably 150 ° C. or higher, more preferably 160 ° C. or higher. By increasing the melting point of the sealant film 33, the retort treatment of the pouch 10 can be performed at a high temperature, and therefore the time required for the retort treatment can be shortened. The melting point of the material constituting the sealant film 33 is lower than the melting point of the resin constituting the first biaxially stretched plastic film 31 and the second biaxially stretched plastic film 32.

The sealant film 33 contains polypropylene as a main component. As used herein, "containing polypropylene as a main component" means that the sealant film contains more than 50% by mass of polypropylene. Specific examples of the material containing propylene as a main component include a propylene / ethylene block copolymer, a propylene / ethylene random copolymer, polypropylene such as homopolypropylene, or a mixture of polypropylene and polyethylene. Can be done. Here, the "propylene / ethylene block copolymer" means a material having a structural formula represented by the following formula (1). Further, the "propylene / ethylene random copolymer" means a material having a structural formula represented by the following formula (2). Further, "homopolypropylene" means a material having a structural formula represented by the following formula (3).

上記式（１）中、ｍ１、ｍ２、ｍ３は、１以上の整数を表す。

In the above equation (1), m1, m2, and m3 represent integers of 1 or more.

上記式（２）中、ｍ、ｎは、１以上の整数を表す。

In the above equation (2), m and n represent integers of 1 or more.

上記式（３）中、ｍは、１以上の整数を表す。

In the above equation (3), m represents an integer of 1 or more.

When a mixture of polypropylene and polyethylene is used as the material containing propylene as a main component, the material may have a sea-island structure. Here, the "sea island structure" refers to a structure in which polyethylene is discontinuously dispersed in a region in which polypropylene is continuous.

Preferably, the sealant film 33 is a monolayer film containing a propylene / ethylene block copolymer. For example, the sealant film 33 is a single-layer unstretched film containing a propylene / ethylene block copolymer as a main component. By using the propylene / ethylene block copolymer, the impact resistance of the sealant film 33 can be enhanced, and thereby it is possible to prevent the pouch 10 from breaking due to the impact at the time of dropping. In addition, the puncture resistance of the packaging material 30 can be improved.

Further, by using the propylene / ethylene block copolymer, the strength of the seal portion composed of the sealant film 33 at a high temperature, for example, 100 ° C., that is, the above-mentioned hot seal strength becomes low, for example, at room temperature. It is extremely small compared to the seal strength. Due to the low hot seal strength, when the pouch 10 is heated using a microwave oven, the steam venting seal portion 24 is easily peeled off, and the steam in the accommodation space 10A is easily released to the outside of the pouch 10. Therefore, it is possible to prevent the internal pressure of the accommodation space 10A from becoming excessive, and thereby it is possible to prevent damage to the packaging material 30 during heating.

The propylene / ethylene block copolymer includes, for example, a sea component made of polypropylene and an island component made of an ethylene / propylene copolymer rubber component. The sea component can contribute to increasing the blocking resistance, heat resistance, rigidity, seal strength, etc. of the propylene / ethylene block copolymer. In addition, the island component can contribute to enhancing the impact resistance of the propylene / ethylene block copolymer. Therefore, by adjusting the ratio of the sea component and the island component, the mechanical properties of the sealant film 33 containing the propylene / ethylene block copolymer can be adjusted.

In the propylene / ethylene block copolymer, the mass ratio of the sea component composed of polypropylene is higher than the mass ratio of the island component composed of the ethylene / propylene copolymer rubber component. For example, in a propylene / ethylene block copolymer, the mass ratio of the sea component composed of polypropylene is at least 51% by mass or more, preferably 60% by mass or more, and further preferably 70% by mass or more.

The single-layer sealant film 33 further contains a second thermoplastic resin in addition to the first thermoplastic resin made of a propylene / ethylene block copolymer. Examples of the second thermoplastic resin include α-olefin copolymers and polyethylene. The α-olefin copolymer is, for example, linear low density polyethylene. Examples of polyethylene include low density polyethylene, medium density polyethylene, and high density polyethylene. The second thermoplastic resin can contribute to increasing the impact resistance of the sealant film 33. Further, by using the second thermoplastic resin, the above-mentioned hot seal strength can be further reduced at a low temperature, for example, as compared with the normal temperature seal strength.

The low-density polyethylene, density of 0.910 g / cm ³ or more 0.925 g / cm ³ or less of polyethylene. The medium density polyethylene is polyethylene having a density of 0.926 g / cm ³ or more and 0.940 g / cm ³ or less. The high-density polyethylene is polyethylene having a density of 0.941 g / cm ³ or more and 0.965 g / cm ³ or less. Low-density polyethylene can be obtained, for example, by polymerizing ethylene at a high pressure of 1000 atm or more and less than 2000 atm. Medium-density polyethylene and high-density polyethylene can be obtained, for example, by polymerizing ethylene at medium pressure or low pressure of 1 atm or more and less than 1000 atm.

The medium-density polyethylene and the high-density polyethylene may partially contain a copolymer of ethylene and α-olefin. Further, even when ethylene is polymerized at medium pressure or low pressure, medium density or low density polyethylene can be produced when a copolymer of ethylene and α-olefin is contained. Such polyethylene is referred to as the above-mentioned linear low-density polyethylene. The linear low-density polyethylene is obtained by copolymerizing an α-olefin with a linear polymer obtained by polymerizing ethylene at medium pressure or low pressure to introduce a short chain branch. Examples of α-olefins include 1-butene (C ₄ ), 1-hexene (C ₆ ), 4-methylpentene (C ₆ ), 1-octene (C ₈ ) and the like. The density of the linear low-density polyethylene is, for example, 0.915 g / cm ³ or more and 0.945 g / cm ³ or less.

The α-olefin copolymer constituting the second thermoplastic resin of the propylene / ethylene block copolymer is not limited to the above-mentioned linear low-density polyethylene. The α-olefin copolymer means a material having a structural formula represented by the following formula (4).

Ｒ^１、Ｒ^２はいずれも、Ｈ（水素原子）、またはＣＨ_３、Ｃ_２Ｈ_５などのアルキル基である。また、ｊおよびｋはいずれも、１以上の整数である。また、ｊはｋよりも大きい。すなわち、式（４）に示すα−オレフィン共重合体においては、Ｒ^１を含む左側の構造がベースとなる。Ｒ^１は例えばＨであり、Ｒ^２は例えばＣ_２Ｈ_５である。

Both R ¹ and R ² are H (hydrogen atom) or alkyl groups such as _{CH 3} and C ₂ H _5. Further, both j and k are integers of 1 or more. Also, j is larger than k. That is, in the shown α- olefin copolymer equation (4), the structure of the left, including the R ¹ is a base. R ¹ is, for example, H, and R ² is, for example, C ₂ H ₅ .

In the sealant film 33, the mass ratio of the first thermoplastic resin made of the propylene / ethylene block copolymer is higher than the mass ratio of the second thermoplastic resin containing at least the α-olefin copolymer or polyethylene. For example, in the single-layer sealant film 33, the mass ratio of the first thermoplastic resin made of the propylene / ethylene block copolymer is at least 51% by mass or more, preferably 60% by mass or more, and more preferably 60% by mass or more. It is 70% by mass or more.

As described above, the second thermoplastic resin can contribute to increasing the impact resistance of the sealant film 33. Therefore, the mechanical properties of the sealant film 33 can be adjusted by adjusting the mass ratio of the second thermoplastic resin containing at least the α-olefin copolymer or polyethylene in the single-layer sealant film 33.

Further, the sealant film 33 may further contain an elastomer such as a thermoplastic elastomer. By using the thermoplastic elastomer, the impact resistance and the puncture resistance of the sealant film 33 can be further improved. Further, by using the thermoplastic elastomer, the above-mentioned hot seal strength can be further reduced at a low temperature, for example, as compared with the normal temperature seal strength.

The thermoplastic elastomer is, for example, a hydrogenated styrene-based thermoplastic elastomer. The hydrogenated styrene-based thermoplastic elastomer has a structure composed of a polymer block A mainly composed of at least one vinyl aromatic compound and a polymer block B mainly composed of at least one hydrogenated conjugated diene compound. .. Further, the thermoplastic elastomer may be an ethylene / α-olefin elastomer. The ethylene / α-olefin elastomer is a low-crystalline or amorphous copolymer elastomer, which is a random copolymer of 50 to 90% by mass of ethylene as a main component and α-olefin as a copolymerization monomer. is there.

The content of the propylene / ethylene block copolymer in the sealant film 33 is, for example, 80% by mass or more, preferably 90% by mass or more.

Examples of the method for producing a propylene / ethylene block copolymer include a method of polymerizing raw materials such as propylene and ethylene using a catalyst. As the catalyst, a Ziegler-Natta type, a metallocene catalyst, or the like can be used.

The thickness of the sealant film 33 is preferably 30 μm or more, more preferably 40 μm or more, still more preferably 50 μm or more, and most preferably 60 μm or more. The thickness of the sealant film 33 is preferably 100 μm or less, more preferably 80 μm or less.

As the single-layer sealant film 33 containing a propylene / ethylene block copolymer, there is a type having high tensile elongation and impact resistance, such as ZK500, which will be described later. This type of sealant film 33 preferably further comprises the property of having low hot seal strength. As a result, it is possible to prevent the internal pressure of the accommodation space 10A from becoming excessive when the pouch 10 is heated.

The tensile elongation (%) of the sealant film 33 in the flow direction (MD) measured in an environment of 25 ° C. after being held for 1 minute in an environment of 25 ° C. is preferably 800% or more, more preferably 900. % Or more, 1000% or more, or 1100% or more. The product of the tensile elongation (%) of the sealant film 33 and the thickness (μm) of the sealant film 33 in the flow direction (MD) is preferably more than 50,000, more preferably 55,000 or more, or 60,000 or more. You may.

The tensile elongation of the sealant film 33 in the width direction (TD) measured in an environment of 25 ° C. after being held for 1 minute in an environment of 25 ° C. is preferably 1050% or more, more preferably 1100% or less. is there. The product of the tensile elongation (%) of the sealant film and the thickness (μm) of the sealant film in the width direction (TD) preferably exceeds 55,000, and more preferably 60,000 or more. Since the sealant film 33 has a high tensile elongation, it is possible to prevent the pouch 10 from breaking due to an impact when dropped or the like.

The tensile elastic modulus of the sealant film 33 in the flow direction (MD) measured in an environment of 25 ° C. after being held for 1 minute in an environment of 25 ° C. is preferably 670 MPa or less, more preferably 650 MPa or less. The product of the tensile elastic modulus (MPa) of the sealant film 33 and the thickness (μm) of the sealant film 33 in the flow direction (MD) is preferably less than 35,000, more preferably 34,000 or less.

The tensile elastic modulus of the sealant film 33 in the width direction (TD) measured in an environment of 25 ° C. after being held for 1 minute in an environment of 25 ° C. is preferably 550 MPa or less, more preferably 500 MPa or less. The product of the tensile elastic modulus (MPa) of the sealant film 33 and the thickness (μm) of the sealant film 33 in the width direction (TD) is preferably less than 28,000, more preferably 25,000 or less.

The tensile elastic modulus of the sealant film 33 shall be measured by the same measuring method and the same measuring conditions as the tensile elongation of the sealant film 33.

<Pattern print layer>
The pattern printing layer 34 is a layer for imparting information on the contents and packaged products, or imparting an aesthetic appearance to the pouch, and includes, for example, a coloring material and a binder resin. By forming the pattern printing layer 34, a pattern can be formed on the pouch 10. The "picture" in the present specification is not particularly limited, and includes, for example, a figure, a character, a pattern, a pattern, a symbol, a pattern, a mark, and the like. As the ink for gravure printing, a finale manufactured by DIC Graphics Corporation can be used.

The pattern printing layer 34 may contain any other additives. Additives include, for example, lubricants, antiblocking agents, fillers, hardeners, pigment dispersants, defoamers, leveling agents, waxes, silane coupling agents, preservatives, antioxidants, UV absorbers, rust inhibitors. Examples thereof include agents, plasticizers, flame retardants, and color-developing agents. These additives are used for the purpose of improving printing suitability, printing effect, etc., and the type and amount of these additives can be appropriately selected depending on the printing method, printing substrate, and printing conditions. The pattern printing layer 34 can be formed on the first biaxially stretched plastic film 31 by a printing method such as gravure printing.

(Color material)
The coloring material is not particularly limited, and known pigments and dyes can be used, and are appropriately selected according to a desired color.

(Binder resin)
Examples of the binder resin include linseed oil, cutting oil, soybean oil, hydrocarbon oil, rosin, rosin ester, rosin-modified resin, shelac, alkyd resin, phenolic resin, maleic acid resin, natural resin, and hydrocarbon resin. Polyvinyl chloride resin, polyacetic acid resin, polystyrene resin, polyvinyl butyral resin, (meth) acrylic resin, polyamide resin, polyester resin, polyurethane resin, epoxy resin, urea resin, melamine resin, amino alkyd Examples thereof include based resins, nitrocellulose, ethyl cellulose, rubber chloride, cyclized rubber, polymers of (meth) acrylate compounds, or mixtures thereof.

<First adhesive layer>
The first adhesive layer 35 contains an adhesive for adhering the first biaxially stretched plastic film 31 and the second biaxially stretched plastic film 32 by a dry laminating method. The adhesive constituting the first adhesive layer 35 is produced from an adhesive composition prepared by mixing a first composition containing a main agent and a solvent and a second composition containing a curing agent and a solvent. Specifically, the adhesive contains a cured product produced by the reaction of the main agent and the solvent in the adhesive composition.

Examples of the adhesive include polyurethane and the like. Polyurethane is a cured product of a polyol and an isocyanate compound produced by reacting a polyol as a main agent with an isocyanate compound as a curing agent. Examples of polyurethane include polyether polyurethane, polyester polyurethane and the like. The polyether polyurethane is a cured product produced by reacting a polyether polyol as a main agent with an isocyanate compound as a curing agent. Polyester polyurethane is a cured product produced by the reaction of a polyester polyol as a main agent and an isocyanate compound as a curing agent.

Examples of the isocyanate compound include aromatic isocyanate compounds such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). The aliphatic isocyanate compound of the above, or an adduct or multimer of the above-mentioned various isocyanate compounds can be used.

The thickness of the first adhesive layer 35 is preferably 2 μm or more, more preferably 3 μm or more. The thickness of the first adhesive layer 35 is preferably 6 μm or less, more preferably 5 μm or less.

<Second adhesive layer>
The second adhesive layer 36 contains an adhesive for adhering the second biaxially stretched plastic film 32 and the sealant film 33 by a dry laminating method. As an example of the adhesive of the second adhesive layer 36, polyurethane and the like can be mentioned as in the case of the first adhesive layer 35. In addition to the configurations, materials and properties described below, the same configurations, materials and properties as those of the first adhesive layer 35 can be adopted as the configurations, materials and properties of the second adhesive layer 36.

The thickness of the second adhesive layer 36 is preferably 2 μm or more, more preferably 3 μm or more. The thickness of the second adhesive layer 36 is preferably 6 μm or less, more preferably 5 μm or less.

By the way, as the isocyanate compound constituting the curing agent of the adhesive, as described above, there are an aromatic isocyanate compound and an aliphatic isocyanate compound. Of these, aromatic isocyanate compounds elute components that cannot be used in food applications in a high-temperature environment such as heat sterilization. By the way, the second adhesive layer 36 is in contact with the sealant film 33. Therefore, when the second adhesive layer 36 contains an aromatic isocyanate compound, the components eluted from the aromatic isocyanate compound adhere to the contents contained in the accommodation space 10A in contact with the sealant film 33. There is. In consideration of such problems, a cured product produced by reacting a polyol as a main agent and an aliphatic isocyanate compound as a curing agent as an adhesive constituting the second adhesive layer 36 is preferable. Is used. This makes it possible to prevent components that cannot be used for food purposes from adhering to the contents due to the second adhesive layer 36.

<Transparent vapor deposition layer>
The transparent vapor deposition layer is formed on the surface of the first biaxially stretched plastic film 31 or the second biaxially stretched plastic film 32.

The transparent thin-film deposition layer functions as a layer having a gas barrier function of blocking the permeation of oxygen gas, water vapor, and the like. Two or more transparent vapor deposition layers may be provided. When two or more transparent vapor-deposited layers are provided, they may have the same composition or different compositions. Examples of the method for forming the transparent vapor deposition layer include a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, and an ion plating method, or a plasma chemical vapor deposition method and heat. Examples thereof include a chemical vapor deposition method, a chemical vapor deposition method such as a photochemical vapor deposition method, and a CVD method. Specifically, a thin-film deposition film film forming apparatus can be used to form a thin-film deposition layer on the film-forming roller.

The transparent thin-film deposition layer is composed of a transparent inorganic material. Examples of inorganic materials include metal oxides and inorganic oxides. Examples of metal oxides include aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), and lead (Pb). , Zirconium (Zr), yttrium (Y) and other metal oxides. Examples of the inorganic oxide include an oxide of silicon (Si). As the inorganic material constituting the transparent thin-film deposition layer, aluminum oxide (aluminum oxide) or silicon oxide is preferable.

The thickness of the transparent thin-film deposition layer is preferably 40 Å (4 nm) or more and 130 Å (13 nm) or less. The lower limit of the thickness of the transparent thin-film deposition layer is more preferably 50 Å (5 nm) or more, 60 Å (6 nm) or more, 70 Å (7 nm) or more, and the upper limit is more preferably 120 Å (12 nm) or less, 110 Å (11 nm). It is as follows.

<Transparent gas barrier coating film>
The transparent gas barrier coating film has transparency and is formed on the surface of the transparent thin-film deposition layer. The transparent gas barrier coating film is a layer that functions as a layer that suppresses the permeation of oxygen gas, water vapor, and the like. The transparent gas barrier coating film has a general formula of R ³ _n M (OR ⁴ ) _m (however, in the formula, R ³ and R ⁴ represent organic groups having 1 to 8 carbon atoms, and M represents a metal atom. n represents an integer of 0 or more, m represents an integer of 1 or more, and n + m represents the valence of M.) At least one kind of alkoxide and the polyvinyl alcohol as described above. Obtained by a transparent gas barrier composition containing a based resin and / or an ethylene / vinyl alcohol copolymer and further polycondensing by the solgel method in the presence of a solgel method catalyst, acid, water, and an organic solvent. Be done.

As the alkoxide represented by the above general formula R ³ _n M (OR ⁴ ) _m , at least one or more of a partial hydrolyzate of the alkoxide and a condensate of the hydrolysis of the alkoxide can be used. Further, the partial hydrolyzate of the alkoxide may be one in which all of the alkoxy groups are hydrolyzed, one or more hydrolyzed, and a mixture thereof. As the condensate of hydrolysis of the alkoxide, one having a dimer or more of the partially hydrolyzed alkoxide, specifically, one having a dimer of 2 to 6 is used.

In the above-mentioned ^{alkoxide represented by the general formula R 3} _n M (OR ⁴ ) _m , silicon, zirconium, titanium, aluminum, or the like can be used as the metal atom represented by M. In the present embodiment, preferred metals include, for example, silicon and titanium. Further, in the present embodiment, the alkoxide may be used alone or by mixing alkoxides of two or more different metal atoms in the same solution.

Further, in the alkoxide represented by the above general formula R ³ _n M (OR ⁴ ) _m ^{, specific examples of the organic group represented by R 3} include, for example, a methyl group, an ethyl group, an n-propyl group, and i. Alkyl groups such as −propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-hexyl group, n-octyl group and others can be mentioned. Further, in the alkoxide represented by the above general formula R ³ _n M (OR ⁴ ) _m ^{, specific examples of the organic group represented by R 4} include, for example, a methyl group, an ethyl group, an n-propyl group, and i. -Propyl group, n-butyl group, sec-butyl group, etc. can be mentioned. In addition, these alkyl groups may be the same or different in the same molecule.

When preparing the above gas barrier composition, for example, a silane coupling agent or the like may be added. As the above-mentioned silane coupling agent, known organic reactive group-containing organoalkoxysilanes can be used. In this embodiment, an organoalkoxysilane having an epoxy group is particularly preferably used. Specifically, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β − (3,4-epoxycyclohexyl) ethyltrimethoxysilane and the like can be used. The above-mentioned silane coupling agent may be used alone or in combination of two or more.

The thickness of the transparent gas barrier coating film is preferably 100 nm or more and 500 nm or less. When the thickness of the transparent gas barrier coating film is 100 nm or more, stable gas barrier property can be obtained, and when it is 500 nm or less, a good coating film can be obtained. The lower limit of the thickness of the transparent gas barrier coating film is more preferably 125 nm or more, 150 nm or more, or 200 nm or more, and the upper limit is preferably 450 nm or less, 400 nm or less, or 300 nm or less.

Specific examples of the packaging material 30 include the following packaging materials. In addition, "/" is used as a notation indicating the boundary between layers when listing layers. Layers shall be described from the outside to the inside of the pouch. That is, the layer described on the far right is the sealant film.
Biaxially stretched PET film / Pattern printing layer / Adhesive layer / Biaxially stretched nylon film / Adhesive layer / Sealant film Biaxially stretched PET film / Pattern printing layer / Adhesive layer / Biaxially stretched PET film / Adhesive layer / Sealant film Biaxially stretched PET film / Pattern printing layer / Adhesive layer / Biaxially stretched straight cut Nylon film / Adhesive layer / Sealant film Biaxially stretched PET film / Pattern printing layer / Adhesive layer / Biaxially stretched straight cut PET Film / Adhesive layer / Sealant film Biaxially stretched PET film / Transparent vapor deposition layer / Transparent gas barrier coating film / Pattern printing layer / Adhesive layer / Biaxially stretched nylon film / Adhesive layer / Sealant film Biaxially stretched PET film / Transparent vapor deposition layer / transparent gas barrier coating film / picture printing layer / adhesive layer / biaxially stretched PET film / adhesive layer / sealant film biaxially stretched PET film / picture printing layer / adhesive layer / transparent gas barrier coating film / Transparent vapor deposition layer / biaxially stretched PET film / adhesive layer / sealant film

<< Other packaging materials >>
It is also possible to use the packaging material 40 shown in FIG. 10 instead of the packaging material 30. Unless otherwise specified, the physical characteristics of the packaging material 40 (for example, hot breaking strength, hot sealing strength, etc.) are the same as those of the packaging material 30, and thus the description thereof will be omitted here.

Similar to the packaging material 30, the packaging material 40 includes at least a first biaxially stretched plastic film 31, a second biaxially stretched plastic film 32, and a sealant film 33 in this order. Reference numeral 40 denotes a light-shielding printing layer 41 provided between the first biaxially stretched plastic film 31 and the sealant film 33. The packaging material 40 does not include a metal leaf layer. The packaging material 40 has only two biaxially stretched plastic films in the packaging material 40. The packaging material 40 shown in FIG. 10 includes, for example, a first biaxially stretched plastic film 31, a transparent vapor-deposited layer 42, a transparent gas barrier coating film 43, a pattern printing layer 34, a light-shielding printing layer 41, and a first adhesive layer 35. , A second biaxially stretched plastic film 32, a second adhesive layer 36, and a sealant film 33 are provided in this order. The packaging material may further include another functional layer exhibiting a desired function between the first biaxially stretched plastic film 31 and the sealant film 33. Further, at least one of the transparent vapor deposition layer 42, the transparent gas barrier coating film 43, and the pattern printing layer 34 may not be provided.

In FIG. 10, the members having the same reference numerals as those in FIG. 3 are the same as the members shown in FIG. 3, and therefore the description thereof will be omitted. Further, the transparent vapor-deposited layer 42 is the same as the transparent vapor-deposited layer described in the column of the packaging material 30, and the transparent gas barrier coating film 43 is the same as the transparent gas barrier coating film described in the column of the packaging material 30. , The description shall be omitted.

The light-shielding printing layer 41 may be provided between the first biaxially stretched plastic film 31 and the sealant film 33. For example, the light-shielding printing layer 41 may be provided between the first biaxially stretched plastic film 31 and the second. It may be provided between the biaxially stretched plastic film 32 of the above, or between the second biaxially stretched plastic film 32 and the sealant film 33.

The light-shielding printing layer 41 is preferably provided on the sealant film 33 side of the pattern printing layer 34. As a result, the pattern of the pattern printing layer 34 can be visually recognized from the outside of the pouch 10.

The total light transmittance of the packaging material 40 is preferably 25.0% or less. Thereby, a pouch having a good light-shielding property can be obtained. The total light transmittance is preferably 23.0% or less, 20.0% or less, 18.0% or less, or 16.0% or less from the viewpoint of obtaining a pouch having better light-shielding property. From the viewpoint of obtaining a pouch having excellent light-shielding properties, it is more preferably 10.0% or less, 5.0% or less, or 3.0% or less.

The total light transmittance can be measured using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Laboratory Co., Ltd., measuring diameter 20 mmφ) in accordance with JIS K7361-1: 1997. Specifically, first, as shown in FIG. 11, from the front surface of the pouch 10, one side L5 is 50 mm and the other side L6 extending in a direction orthogonal to one side L1 is formed so as not to include the seal portion 15. Three 50 mm square test pieces S4 are cut out, and as shown in FIG. 12, the side L5 extends in a direction orthogonal to the side L1 and 50 mm from the back surface of the pouch 10 so as not to include the seal portion 15. Two square test pieces S4 having a side L6 of 50 mm are cut out. The test piece S4 may include a pattern printing layer. The test piece S4 is cut out so that the other side L6 is parallel to the X direction (the direction orthogonal to the direction in which the first side seal portion 16 extends). After that, the test piece S4 was placed on the haze meter so that the first biaxially stretched plastic film 31 was on the light source side without curls or wrinkles, and the test piece was placed in an environment of a temperature of 25 ° C. and a relative humidity of 50%. After holding S4 for 1 minute, the total light transmittance of the test piece S4 is measured in an environment of a temperature of 25 ° C. and a relative humidity of 50%. The total light transmittance of the five test pieces S4 is measured, and the average value is taken as the total light transmittance of the packaging material.

The appearance of the pouch may be required to be bright white in order to give a feeling of cleanliness and coolness, or to enhance the pattern of the pattern printing layer. On the other hand, in order to reduce the total light transmittance, it is preferable to provide a layer (dark color layer) having a darker color than the white layer inside the white layer. However, when such a dark color layer is provided, even though the white layer exists outside the dark color layer, when the pouch is viewed from the outside, it becomes dull white due to the influence of the color of the dark color layer. There is a risk that bright white will not be obtained. Therefore, in order to obtain a pouch having bright whiteness, the L ^{* value in the L *} a ^* b ^* color system measured by the SCE method (specular reflection light removal method) of the packaging material 40 is 65.0 or more. It is preferable to have. The L ^* value substantially represents the whiteness, and the closer to 100, the higher the whiteness, and the closer to 0, the lower the whiteness. The SCE method is used for measurement because the SCE method is a measurement method that is close to the sensation seen by the human eye. The L ^* value is more preferably 68.0 or more or 70.0 or more from the viewpoint of obtaining a pouch having better whiteness, and from the viewpoint of obtaining a pouch having more vivid whiteness, 72. It is more preferably 0 or more or 75.0 or more.

The L ^* value conforms to JIS Z8781-4: 2013 ( ^{color measurement-part 4: CIE 1976L *} a ^* b ^* color space), and is a spectrophotometer (product name "SpectroEye", manufactured by X-Rite). It can be measured using a measurement diameter of 2 mmφ). Specifically, first, as shown in FIG. 13, from the front surface of the pouch 10, the pattern printing layer 34 and the seal portion 15 are not included, and the side L7 is 5 mm and the side is orthogonal to the side L1. Cut out five square test pieces S5 having an extending other side L8 of 5 mm. Although the test piece S5 has a square shape, it may have any shape as long as it is larger than the area of the measurement diameter of 2 mm. The test piece S5 may be cut out from the back surface of the pouch 10. The test piece S5 is cut out so that the other side L8 is parallel to the X direction (the direction orthogonal to the direction in which the first side seal portion 16 extends). Then, the test piece S5 is arranged on a white plate (material: paper, size A4 size (210 mm × 297 mm), thickness: 0.3 mm) so that the first biaxially stretched plastic film 31 faces the upper surface. Then, after holding the test piece S5 for 1 minute in an environment of a temperature of 25 ° C. and a relative humidity of 50%, the L ^* value of the test piece S5 is set by the SCE method (specular reflected light) in an environment of a temperature of 25 ° C. and a relative humidity of 50%. Measure by removal method). When measuring the L ^* value, the light source is D50 and the viewing angle is 2 °. ^{The L *} value is measured for the five test pieces S5, and the average value is taken as the L ^* value of the packaging material.

<Light-shielding printing layer>
The light-shielding printing layer 41 is a layer for obtaining light-shielding properties. By forming the light-shielding printing layer 41, it is possible to prevent the contents from being seen through, and it is possible to suppress photodegradation such as fading of the contents during long-term storage.

The thickness of the light-shielding printing layer 41 is preferably 2.0 μm or more and 6.0 μm or less. When this thickness is 2.0 μm or more, the total light transmittance of the packaging material 40 is likely to be 25.0% or less. When the thickness of the light-shielding printing layer 41 is 6.0 μm or less, it is possible to suppress the thickening of the entire packaging material 40 and to improve the production effect and processability. The lower limit of the thickness of the light-shielding printing layer 41 is preferably 3.0 μm or more, 3.5 μm or more, or 4.0 μm or more, and the upper limit is preferably 5.5 μm or less and 5.0 μm or less. The "thickness of the light-shielding printing layer" in the present specification means that the light-shielding printing layer has a multilayer structure such as a laminated structure of a white layer and a gray layer or a laminated structure of a white layer and a metal flake-containing layer as described later. Means the total thickness of each layer constituting the light-shielding printing layer.

The light-shielding printing layer 41 is known on, for example, on the first biaxially stretched plastic film 31 and the second biaxially stretched plastic film 32, such as a gravure printing method, an offset printing method, a letterpress printing method, and a silk screen printing method. It can be formed by a printing method.

The light-shielding printing layer 41 is preferably provided on substantially the entire surface of the packaging material 40. The substantially entire surface means that it is 80% or more in the plane of the packaging material, preferably 90% or more, more preferably 95% or more, still more preferably 99% or more, and most preferably 100%.

The light-shielding printing layer 41 includes (1) a layer containing a white pigment (hereinafter, this layer may be referred to as a "white layer") and a layer containing a white pigment and a black pigment (hereinafter, this layer is referred to as "gray"). (Sometimes referred to as a "layer"), or (2) a layer containing a white pigment and a layer containing metal flakes (hereinafter, this layer may also be referred to as a "metal flake-containing layer"). It is preferable that the laminate is provided with. Among these, the laminate of (2) above is more preferable as the light-shielding printing layer 41 because a lower total light transmittance (for example, 10.0% or less) can be obtained.

(White layer)
The white layer may have a single-layer structure, or may have a multi-layer structure in which two or more white layers having the same composition or different compositions are laminated. The white layer is preferably located closer to the first biaxially stretched plastic film 31 side (visual side) than the gray layer or the metal flake-containing layer. When the packaging material 40 contains a metal flake-containing layer, the metal flake-containing layer has a large proportion of diffusing components, but the proportion of diffusing components is still smaller than that of the white layer. People feel glare, albeit to some extent. That is, by locating the white layer on the side (visual side) of the first biaxially stretched plastic film 31 with respect to the metal flake-containing layer, the specular reflection of the metal-containing layer flake layer is softened, and the design of the packaging material 40 is improved. It can be calm. Further, the white layer can improve the light-shielding property of the packaging material 40, but its contribution to the light-shielding property is lower than that of the gray layer or the metal flake-containing layer.

The thickness of the white layer is preferably 0.5 μm or more and 5.0 μm or less. When the thickness of the white layer is 0.5 μm or more, the total light transmittance of the packaging material 40 can be easily reduced to 25.0% or less, and the white layer can easily sufficiently soften the specular reflection of external light, so that the packaging material can be used. The design can be made calm and easy. Further, when the thickness of the white layer is 5.0 μm or less, the thickening of the entire packaging material 40 can be suppressed, and the production efficiency and processability can be improved. The lower limit of the thickness of the white layer is preferably 0.7 μm or more, 1.0 μm or more, or 1.5 μm or more, and the upper limit is 4.5 μm or less, 4.0 μm or less, or 3.5 μm or less. Is preferable. In the present specification, the "thickness of the white layer" means the total thickness of each layer constituting the white layer when the white layer has a multi-layer structure.

Examples of the white pigment contained in the white layer include titanium oxide, barium sulfate, magnesium oxide, calcium carbonate, zinc oxide, white lead and the like. Among these, titanium oxide having excellent hiding power is preferable.

Examples of titanium oxide include anatase type, rutile type and brookite type depending on the crystal structure. Among these, the rutile type and the brookite type having low photocatalytic activity are preferable, and the rutile type having versatility is more preferable.

The white pigment preferably has an average primary particle size of 150 nm or more and 500 nm or less from the viewpoint of strengthening diffusion and enhancing hiding power. The lower limit of the average primary particle size of the white pigment is more preferably 250 nm or more, and the upper limit is more preferably 450 nm or less. In the present specification, the average primary particle size of various pigments such as white pigments is photographed at a magnification of 40,000 to 200,000 times using, for example, a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM). The primary particle diameters of 20 white pigments are measured from the image of the cross section of the white layer, and the primary particle diameters of the 20 white pigments are taken as the arithmetic average value.

The white layer preferably contains a binder resin. Examples of the binder resin include polyolefin resins such as polyethylene resins and chlorinated polypropylene resins, poly (meth) acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, and vinyl chloride-vinyl acetate copolymers. , Polystyrene resin, styrene-butadiene copolymer, vinylidene fluoride resin, polyvinyl alcohol resin, polyvinyl acetal resin, polyvinyl butyral resin, polybutadiene resin, polyester resin, polyamide resin, alkyd resin, epoxy Based resin, unsaturated polyester based resin, thermocurable poly (meth) acrylic resin, melamine based resin, urea resin, polyurethane resin, phenol resin, xylene resin, maleic acid resin, nitrocellulose, ethyl cellulose, acetyl Examples thereof include fibrous resins such as butyl cellulose and ethyloxyethyl cellulose, rubber resins such as rubber chloride and cyclized rubber, petroleum resins, and natural resins such as rosin and casein. These may be used alone or in combination of two or more. From the viewpoint of the global environment, it is preferable that the binder resin contains a resin derived from plants such as trees, rice bran and seeds.

The content of the white pigment is preferably 3% by mass or more and 50% by mass or less of the total solid content of the white layer. When the content of the white pigment is 3% by mass or more, the total light transmittance of the packaging material 40 can be easily reduced to 25.0% or less, and when the content of the white pigment is 50% by mass or less, the white layer is formed. Adhesion between the adjacent layer and the white layer is improved, and retort resistance can be easily improved. The lower limit of the content of the white pigment is more preferably 5% by mass or more or 7% by mass or more of the total solid content of the white layer, and the upper limit of the content of the white pigment is 30% by mass of the total solid content of the white layer. More preferably, it is% or less or 20% by mass or less.

The white layer preferably contains inorganic particles having an average primary particle diameter of 1 nm or more and 100 nm or less. By including such inorganic particles having an average primary particle size in the white layer, the white pigment is suppressed from sinking below the white layer, and the adhesion between the layer coated with the white layer and the white layer is good. Can be made easy. The lower limit of the average primary particle size of the inorganic particles is more preferably 2 nm or more or 5 nm or more, and the upper limit is more preferably 50 nm or less or 30 nm or less.

The content of the inorganic particles in the white layer is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 2 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the white pigment. It is more preferably more than 10 parts by mass and less than 10 parts by mass.

Examples of the inorganic particles include silica, alumina and zirconia. Among these, silica having excellent transparency is preferable. Further, since silica and alumina are excellent in insulating properties, they are also preferable in that they can improve microwave oven resistance.

For the white layer, for example, a light stabilizer such as a filler, a stabilizer, a plasticizer, an antioxidant, an ultraviolet absorber, a dispersant, a thickener, a desiccant, a lubricant, an antistatic agent, etc. Any additive such as a cross-linking agent can be added.

(Gray layer)
The gray layer may have a single-layer structure, or may have a multi-layer structure in which two or more gray layers having the same composition or different compositions are laminated. The gray layer can be formed from gray ink, even if the gray ink is produced, for example, by mixing a white ink containing a white pigment and a black ink containing a black pigment (black ink). Good.

The thickness of the gray layer is preferably 0.5 μm or more and 5.0 μm or less. When the thickness of the gray layer is 0.5 μm or more, the total light transmittance of the packaging material 40 can be easily reduced to 25.0% or less. Further, when the thickness of the gray layer is 5.0 μm or less, the thickening of the entire packaging material 40 can be suppressed, and the production efficiency and processability can be improved. The lower limit of the thickness of the gray layer is more preferably 0.7 μm or more, 1.0 μm or more, or 1.5 μm or more, and the upper limit is 4.5 μm or less, 4.0 μm or less, or 3.5 μm or less. Is more preferable. The term "thickness of the gray layer" as used herein means the total thickness of each layer constituting the gray layer when the gray layer has a multi-layer structure.

Since the white pigment contained in the gray layer is the same as the white pigment contained in the white layer, the description thereof will be omitted here. Examples of the black pigment contained in the gray layer include carbon black, titanium black, iron black and the like. Among these, carbon black is more preferable because it is versatile and it is easy to obtain a desired color.

The ratio of the content of the black pigment to the content of the white pigment in the gray layer ((content of black pigment / content of white pigment) × 100) is preferably 0.1% or more and 10% or less. When this ratio is 0.1% or more, the total light transmittance of the packaging material 40 is likely to be 25.0% or less. Further, when this ratio is 10% or less, it is possible to suppress the packaging material 40 from becoming grayish. The lower limit of this ratio is more preferably 0.5% or more, 1.0% or more, or 1.5% or more, and the upper limit of this ratio is 8.0% or less, 7.0% or less, or More preferably, it is 5.0% or less.

The content of the white pigment in the gray layer is preferably 18.0% by mass or more and 29.7% by mass or less of the total solid content of the gray layer. When the content of the white pigment is 18.0% by mass or more, it is possible to suppress the packaging material 40 from becoming grayish, and when it is 29.7% by mass or less, the light-shielding property can be improved. The lower limit of the content of the white pigment in the gray layer is more preferably 18.2% by mass or more, 18.4% by mass or more, or 19.0% by mass or more, and the upper limit is 29.4% by mass or less. , 29.1% by mass or less, or 28.8% by mass or less, more preferably.

The content of the black pigment in the gray layer is preferably 0.2% by mass or more and 3.0% by mass or less of the total solid content of the gray layer. When the content of the black pigment is 0.2% by mass or more, the total light transmittance is likely to be 25.0% or less, and when it is 3.0% by mass or less, the packaging material 40 is grayish. Can be suppressed. The lower limit of the content of the black pigment in the gray layer is more preferably 0.3% by mass or more, 0.4% by mass or more, or 0.6% by mass or more, and the upper limit is 2.4% by mass or less. , 2.0% by mass or less, or more preferably 1.5% by mass or less.

The gray layer preferably contains a binder resin. Examples of the binder resin include those similar to the binder resin described in the section on the white layer.

For the gray layer, for example, a light stabilizer such as a filler, a stabilizer, a plasticizer, an antioxidant, an ultraviolet absorber, a dispersant, a thickener, a desiccant, a lubricant, an antistatic agent, etc. Any additive such as a cross-linking agent can be added.

(Metal flake-containing layer)
It is possible to reduce the total light transmittance of the packaging material to 25.0% or less with only the white layer, but in that case, since the thickness of the white layer needs to be extremely thick, odor due to the residual solvent is likely to occur. Further, the processing suitability of the packaging material is lowered. Therefore, in addition to the white layer, a metal flake-containing layer is provided.

The metal flake-containing layer may have a multi-layer structure in which a plurality of metal flake-containing layers having the same composition or different compositions are laminated. By laminating a plurality of metal flake-containing layers, the metal flakes are easily laminated in the thickness direction, and the total light transmittance can be reduced.

The thickness of the metal flake-containing layer is preferably 0.5 μm or more and 5.0 μm or less. When the thickness of the metal flake-containing layer is 0.5 μm or more, the total light transmittance of the packaging material 40 can be easily reduced to 25.0% or less. Further, when the thickness of the metal flake-containing layer is 5.0 μm or less, the thickening of the entire packaging material 40 can be suppressed, and the production efficiency and processability can be improved. The lower limit of the thickness of the metal flake-containing layer is more preferably 0.7 μm or more, 1.0 μm or more, or 1.5 μm or more, and the upper limit is 4.5 μm or less, 4.0 μm or less, 3.5 μm or less, Alternatively, it is more preferably 3.0 μm or less. In the present specification, the "thickness of the metal flake-containing layer" means the total thickness of each layer constituting the metal flake-containing layer when the metal flake-containing layer has a multi-layer structure.

When the thickness of the white layer is t1 and the thickness of the metal flake-containing layer is t2, t1 / t2 is preferably 0.2 or more and 2.0 or less. When t1 / t2 is 0.2 or more, the white layer makes it easy to sufficiently soften the specular reflection, and makes it easy to make the design of the packaging material calm. Further, when t1 / t2 is 2.0 or less, the light-shielding property can be easily imparted by the metal flake-containing layer. The lower limit of t1 / t2 is more preferably 0.3 or more, and the upper limit is more preferably 1.8 or less.

Examples of the material of the metal flakes include metals and alloys such as aluminum, gold, silver, brass, titanium, chrome, nickel, nickel chrome and stainless steel. Among these, aluminum and silver are preferable from the viewpoint of easily obtaining a color tone close to white, and aluminum is more preferable from the viewpoint of suppressing cost increase.

Metal flakes can be obtained, for example, by mixing the above metal or alloy powder with a solvent and spreading and / or pulverizing the powder with a medium stirring mill, a ball mill, an attritor or the like. Since the metal flakes thus obtained are formed into flakes by stretching the metal powder, the surface of the metal flakes has undulating irregularities, and the diffusibility can be improved.

When the metal flakes are produced by the above method, the length, thickness and aspect ratio of the metal flakes can be adjusted according to the size of the bearing balls, the time and strength of spreading and / or crushing, and the like. For example, by increasing the spreading and crushing time and increasing the spreading and crushing strength, the average length becomes smaller and the thickness becomes thinner.

The average length of the metal flakes is preferably 1 μm or more and 10 μm. When this average length is 1 μm or more, the diffusivity is improved and the feeling of brightness is improved. Further, when the average length is 10 μm or less, the density of the metal flakes in the metal flake-containing layer can be increased. The lower limit of the average length of the metal flakes is more preferably 2 μm or more or 3 μm or more, and the upper limit is more preferably 7 μm or less or 5 μm or less. As described above, the metal flakes having a relatively short length are laminated in the thickness direction in the metal flake-containing layer, so that multiple reflections occur at many points in the plane of the metal flake-containing layer, and the total light transmittance is increased. Can be lowered.

The average length of the metal flakes is determined as the average value of the lengths of any 20 metal flakes observed with an optical microscope or an electron microscope from the plane direction of the packaging material. The length of one metal flake means the maximum length of one metal flake in the plane direction.

The average thickness of the metal flakes is preferably 0.01 μm or more and 0.50 μm or less. By setting the average thickness of the metal flakes to 0.01 μm or more, the hiding power of individual metal flakes can be enhanced, and the total light transmittance can be easily reduced to 25.0% or less. Further, by setting the average thickness of the metal flakes to 0.50 μm or less, the metal flakes are easily laminated in the thickness direction in the metal flake-containing layer, and multiple reflections can be generated between the metal flakes. The light transmittance can be reduced. The lower limit of the average thickness of the metal flakes is more preferably 0.03 μm or more or 0.05 μm or more, and the upper limit is more preferably 0.30 μm or less or 0.15 μm or less.

The average thickness of the metal flakes is determined as the average value of the thicknesses of any 20 metal flakes obtained by observing the cross section of the packaging material with an optical microscope or an electron microscope. The thickness of one metal flake is obtained by dividing the cross-sectional image of one metal flake into five regions having equal lengths in the length direction, and the thickness of the central portion of each region (t ₁ , t ₂ , _{t 3, t 4, t 5} ) were _measured, means an average of the t 1 ~t _5.

The aspect ratio (average length / average thickness) of the metal flakes is preferably 25 or more and 100 or less. By setting the aspect ratio of the metal flakes to 25 or more, the metal flakes are less likely to tilt in the metal flake-containing layer, so that the metal flakes are easily laminated in the thickness direction in the metal flake-containing layer. As a result, multiple reflections can occur between the metal flakes and the total light transmittance can be reduced. Further, by setting the aspect ratio of the metal flakes to 100 or less, when the metal flakes are tilted, the adjacent metal flakes are less likely to come into contact with each other, and the microwave oven resistance can be improved. The lower limit of the aspect ratio of the metal flakes is more preferably 27 or more or 30 or more, and the upper limit is further preferably 70 or less or 50 or less.

The metal flakes are preferably non-leaving type. In the non-leaving type metal flakes, since the metal flakes are suppressed from floating near the surface of the coating film in the process of forming the metal flake-containing layer, the metal flakes are easily laminated in the thickness direction in the metal flake-containing layer. As a result, multiple reflections can be generated between the metal flakes, so that the optical path length of the light passing through the metal flakes-containing layer becomes extremely long, and the total light transmittance can be reduced. As a result, the total light transmittance can be lowered as compared with the leafing type metal flakes.

Furthermore, in non-leaving type metal flakes, the metal flakes are uniformly dispersed in the layer during the formation process of the metal flakes-containing layer, so even if the metal flakes are tilted, the spacing between the metal flakes is so narrow that sparks and overheating occur. Therefore, it is possible to prevent the packaging material from deteriorating when the microwave oven is used.

When a plurality of metal flake-containing layers are laminated, the metal flakes can be laminated as a whole of the plurality of metal flake-containing layers even if a leafing type metal flake is used. However, in the case of the leafing type, a large amount of light is specularly reflected by the metal flakes arranged on the coating surface of the metal flake-containing layer that the light first reaches, and it is difficult for the light to reach the next metal flake-containing layer. , It is difficult to cause multiple reflections. Therefore, even when a plurality of metal flake-containing layers are laminated, the non-leaving type metal flakes are more likely to reduce the total light transmittance. The non-leaving type metal flakes are also useful in that the residual solvent can be easily reduced.

Non-leafing type metal flakes are metal flakes that have not been surface-treated with long-chain saturated fatty acids such as palmitic acid, stearic acid and behenic acid, and are, for example, metal flakes that have been surface-treated with unsaturated fatty acids such as linoleic acid. Examples include metal flakes that have not been surface-treated.

From the viewpoint of microwave oven resistance, the metal flakes are preferably those in which the surface of the metal flakes is resin-coated. The resin-coated metal flakes can be produced, for example, by the methods described in JP-A-62-253668, JP-A-64-450566, JP-A-2003-213157, and JP-A-2012-241039. ..

The content of the metal flakes in the metal flake-containing layer is preferably 20% by mass or more and 60% by mass or less of the total solid content of the metal flake-containing layer. By setting the content of the metal flakes to 20% by mass or more, the total light transmittance of the packaging material can be easily set to 25.0% or less. Further, by setting the content of the metal flakes to 60% by mass or less, the microwave oven resistance can be easily improved, and the adhesion between the layer adjacent to the metal flake-containing layer and the metal flake-containing layer becomes good, and the resistance is improved. It is possible to easily improve the retort property. The lower limit of the content of the metal flakes is more preferably 30% by mass or more or 35% by mass or more, and the upper limit is further preferably 55% by mass or less or 50% by mass or less.

The metal flake-containing layer preferably contains a binder resin. Examples of the binder resin of the metal flake-containing layer include those similar to the binder resin of the white layer. When the metal flake-containing layer has a multi-layer structure, the binder resin of the plurality of metal flake-containing layers preferably has a refractive index difference of 0.03 or less, preferably 0.01 or less, in order to suppress interfacial reflection. It is more preferable to do so.

The metal flake-containing layer may contain, for example, a light stabilizer such as a filler, a stabilizer, a plasticizer, an antioxidant, an ultraviolet absorber, a dispersant, a thickener, a desiccant, a lubricant, and an antistatic agent. Any additive such as an agent and a cross-linking agent can be added.

Specific examples of the packaging material 40 include the following packaging materials. As in the above, "/" is used as a notation indicating the boundary between layers when listing the layers. Layers shall be described from the outside to the inside of the pouch. That is, the layer described on the far right is the sealant film.
Biaxially stretched PET film / transparent vapor deposition layer / transparent gas barrier coating film / pattern printing layer / light-shielding printing layer / adhesive layer / biaxially stretched PET film / adhesive layer / sealant film biaxially stretched PET film / transparent vapor deposition layer / Transparent gas barrier coating film / light-shielding printing layer / adhesive layer / biaxially stretched PET film / adhesive layer / sealant film biaxially stretched PET film / pattern printing layer / light-shielding printing layer / adhesive layer / transparent gas barrier coating film / Transparent vapor deposition layer / Biaxially stretched PET film / Adhesive layer / Sealant film Biaxially stretched PET film / Light-shielding printing layer / Adhesive layer / Transparent gas barrier coating film / Transparent vapor deposition layer / Biaxially stretched PET film / Adhesive layer / Sealant film Biaxially stretched PET film / Pattern printing layer / Light-shielding printing layer / Adhesive layer / Biaxially stretched PET film / Adhesive layer / Sealant film Biaxially stretched PET film / Light-shielding printing layer / Adhesive layer / Biaxially stretched PET Film / Adhesive layer / Sealant film Biaxially stretched PET film / Pattern printing layer / Light-shielding printing layer / Adhesive layer / Biaxially stretched straight cut PET film / Adhesive layer / Sealant film Biaxially stretched PET film / Light-shielding printing layer / Adhesive layer / Biaxially stretched straight cut PET film / Adhesive layer / Sealant film

According to this embodiment, after holding for 1 minute in an environment of 100 ° C., the hot breaking strength in one direction (for example, the flow direction (MD)) when measured in an environment of 100 ° C. is 33.0 MPa. As described above, the hot breaking strength is high. As a result, it is possible to prevent the pouch from breaking when it is heated in the microwave oven.

If the sealing strength of the steam venting seal part in the pouch heated by the microwave oven becomes a moderately low value, the steam venting seal part is likely to peel off based on the force received from the pressure of the steam generated in the accommodation space. Become. That is, the steam vent seal portion is peeled off at a lower pressure. According to the present embodiment, the hot seal strength of the pouch 10 when measured in an environment of 100 ° C. is 20.0 N or less, so that the hot seal strength is low, and thereby steam from the steam vent seal portion 24. It is possible to easily remove the steam, and it is possible to stably remove the steam.

Normally, when trying to obtain light-shielding properties in a pouch, a packaging material containing a metal foil layer such as aluminum foil is used, but if such a packaging material is used, there is a risk of sparking when heated in a microwave oven. Therefore, the metal foil layer cannot be used as the packaging material for the pouch used in the microwave oven. On the other hand, in the present embodiment, when a packaging material 40 having a light-shielding printing layer 41 and having a total light transmittance of 25.0% or less is used as the packaging material as shown in FIG. 10, light-shielding property can be obtained. It is possible to suppress sparks when heating in a microwave oven. This makes it possible to obtain a pouch that can be heated in a microwave oven and can suppress photodegradation of the contents.

If the contents contained in the pouch have a high viscosity or a large amount of oil, the packaging material constituting the pouch may be punctured due to overheating when heated in a microwave oven. On the other hand, when a biaxially stretched polyethylene terephthalate film is used as the first biaxially stretched plastic film 31 and the second biaxially stretched plastic film 32 of the packaging materials 30 and 40, the heat resistance is excellent. Therefore, it is possible to prevent holes in the packaging materials 30 and 40 from being formed during heating in a microwave oven.

In order to explain the present invention in detail, examples will be given below, but the present invention is not limited to these descriptions.

<Example 1>
First, as the first biaxially stretched plastic film, a biaxially stretched polyethylene terephthalate film having a thickness of 12 μm (product name “E5100”, manufactured by Toyobo Co., Ltd.) was prepared. Subsequently, a pattern printing layer was formed on this film. The thickness of the pattern printing layer was 1.0 μm. Further, as a second biaxially stretched plastic film, a biaxially stretched nylon film (product name "Bonil QC", Kojin Film & Chemicals Co., Ltd.) having a thickness of 15 μm was prepared. Further, as a sealant film, an unstretched polypropylene film having a thickness of 60 μm (product name “ZK500”, manufactured by Toray Film Processing Co., Ltd.) was prepared. ZK500 contained the above-mentioned propylene / ethylene block copolymer and elastomer.

ZK500 has a higher tensile elongation than a general unstretched polypropylene film. Specifically, the tensile elongation of ZK500 in the flow direction (MD) is 1180% when the thickness is 50 μm and 1100% when the thickness is 60 μm. The tensile elongation of ZK500 in the width direction (TD) is 1240% when the thickness is 50 μm and 1150% when the thickness is 60 μm. Therefore, the product of the tensile elongation (%) and the thickness (μm) of ZK500 in the flow direction is 59000 when the thickness is 50 μm and 66000 when the thickness is 60 μm. The product of the tensile elongation (%) and the thickness (μm) of ZK500 in the width direction is 62000 when the thickness is 50 μm and 69000 when the thickness is 60 μm.

Subsequently, a biaxially stretched polyethylene terephthalate film, a pattern printing layer, a first adhesive layer, a biaxially stretched nylon film, a second adhesive layer, and an unstretched polypropylene film are laminated in this order by a dry laminating method to prepare a packaging material. Made. As the first adhesive layer and the second adhesive layer, a two-component polyurethane adhesive (main agent: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used. The main agent, RU-40, is a polyester polyol. The thickness of the first adhesive layer and the second adhesive layer was 3.0 μm.

Then, using the three packaging materials prepared above, 200 ml of water was filled in, and a standing pouch shown in FIG. 1 was prepared. Specifically, first, in the packaging material to be the bottom surface, the unstretched polypropylene film which is the sealant film is folded in half so as to be on the outside, and the first portion and the second portion which are continuously provided via the fold line are formed. A through hole was formed by punching a portion near the lower end of both lateral edges of the bottom surface in a circular shape having a diameter of 10 mm when the pouch was formed after cutting in the state of being folded in half.

Then, the packaging material to be the bottom film folded in half is placed at a predetermined position between the packaging material to be the front surface film and the packaging material to be the back surface film, and heat-sealed under the following conditions. A first side seal portion, a second side seal portion, a first bottom seal portion, a second bottom seal portion, and a steam vent seal portion were formed. As a result, a pouch with an open top was obtained. Since there is no packaging material that becomes the bottom film folded in half in the through hole portion, the packaging material that becomes the front surface film and the packaging material that becomes the back surface film are directly fused to seal the auxiliary bottom. The part was formed.
(Heat fusion conditions)
-Heat fusion device: Heat sealer TP-701-A (manufactured by Tester Sangyo Co., Ltd.)
・ Heat fusion temperature: 220 ℃
・ Heat fusion pressure: 0.1 MPa
・ Heat fusion time: 1 second

Then, after filling each pouch with 200 ml of water from the opening, heat fusion was performed under the same conditions as the above heat fusion conditions to form an upper seal portion, and the pouch was sealed. Then, each pouch was retorted under the following conditions to prepare a pouch according to Example 1 to which the retort treatment was performed. In the first embodiment, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.
(Retort processing)
・ Method: Spray type ・ Retort temperature: 121 ℃
・ Retort time: 30 minutes

In the manufactured pouch according to the first embodiment, the height H of the pouch is 160 mm, the width W1 of the pouch is 147 mm, the folding width W2 of the bottom gusset portion is 46 mm, the first side seal portion and the second side seal portion. The width W3 was 7.0 mm, the width W4 of the steam vent seal portion was 5 mm, and the width W5 of the upper seal portion was 10.0 mm.

<Example 2>
In Example 2, instead of the 15 μm-thick biaxially stretched nylon film (product name “Bonil QC”, Kojin Film & Chemicals Co., Ltd.), a second biaxially stretched plastic film having a thickness of 12 μm was used. A packaging material was produced in the same manner as in Example 1 except that an axially stretched polyethylene terephthalate film (product name "E5200", manufactured by Toyobo Co., Ltd.) was used. Then, using these three packaging materials, the pouch according to Example 2 was produced in the same manner as in Example 1. In the second embodiment, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

<Example 3>
In Example 3, instead of the 15 μm-thick biaxially stretched nylon film (product name “Bonil QC”, Kojin Film & Chemicals Co., Ltd.), a second biaxially stretched plastic film is used as a straight-ahead 12 μm thick film. A packaging material was produced in the same manner as in Example 1 except that a cuttable biaxially stretched polyethylene terephthalate film (product name "Emblet (registered trademark) PCBC", manufactured by Unitica Co., Ltd.) was used. Then, using these three packaging materials, the pouch according to Example 3 was produced in the same manner as in Example 1. In the third embodiment, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

<Example 4>
First, as the first biaxially stretched plastic film, a biaxially stretched polyethylene terephthalate film having a thickness of 12 μm (product name “E5100”, manufactured by Toyobo Co., Ltd.) was prepared. Subsequently, one surface of this film was subjected to a corona discharge treatment, and then a transparent vapor-deposited layer made of a silicon oxide having a thickness of 10 nm was formed.

Next, the transparent vapor-deposited layer is subjected to plasma treatment with a mixed gas of oxygen and argon, and then a coating liquid containing ethyl silicate and polyvinyl alcohol as main components is applied with a gravure roll coater, and the thickness after drying is 300 nm. A transparent gas barrier coating film was formed.

Then, a pattern printing layer was formed on a part of the surface of the transparent gas barrier coating film. The thickness of the pattern printing layer was 1.0 μm. After forming the pattern printing layer, a light-shielding printing layer having a thickness of 5 μm was formed on the surface of the pattern printing layer. The light-shielding printing layer was composed of two white layers and one gray layer. Specifically, first, a white ink containing titanium oxide (product name "Rio Alpha (registered trademark) R631 white", manufactured by Toyo Ink Co., Ltd.) is applied to the surface of the pattern printing layer, dried at 50 ° C., and then dried. A white layer having a thickness of 1.0 μm was formed. Further, a white ink containing titanium oxide (product name "NKFS series R69K", manufactured by Toyo Ink Co., Ltd.) is applied to the surface of this white layer and dried at 60 ° C. to form a white layer having a thickness of 2.0 μm. did. Then, a gray ink containing titanium oxide and carbon black was applied to the surface of the white layer and dried at 60 ° C. to form a gray layer having a thickness of 2.0 μm. The gray ink is obtained by adding 5% by mass of black ink containing carbon black and polyurethane resin to white ink containing titanium oxide and polyurethane resin (product name "NKFS series R69K", manufactured by Toyo Ink Co., Ltd.). Made.

Further, as the second biaxially stretched plastic film, a biaxially stretched polyethylene terephthalate film having a thickness of 12 μm (product name “E5100”, manufactured by Toyobo Co., Ltd.) was prepared. Further, as a sealant film, an unstretched polypropylene film having a thickness of 60 μm (product name “ZK500”, manufactured by Toray Film Processing Co., Ltd.) was prepared.

Then, by the dry laminating method, a biaxially stretched polyethylene terephthalate film, a transparent vapor-deposited layer, a transparent barrier coating film, a pattern printing layer, a light-shielding printing layer, a first adhesive layer, a biaxially stretched polyethylene terephthalate film, and a second adhesive layer. , And an unstretched polypropylene film were laminated in this order to prepare a packaging material. As the first adhesive layer and the second adhesive layer, a two-component polyurethane adhesive (main agent: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used. The thickness of the first adhesive layer and the second adhesive layer was 3.0 μm.

Then, using these three packaging materials, the pouch according to Example 4 was produced in the same manner as in Example 1. In the fourth embodiment, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

<Example 5>
In Example 5, instead of the light-shielding printing layer composed of the white layer having a thickness of 1 μm, the white layer having a thickness of 2 μm, and the gray layer having a thickness of 2 μm, the following white layer having a thickness of 2 μm and the following thickness of 2 μm have been used. A packaging material was produced in the same manner as in Example 4 except that a light-shielding printing layer composed of the aluminum flake-containing layer was formed. Then, using these three packaging materials, the pouch according to Example 5 was produced in the same manner as in Example 1. In the fifth embodiment, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

The white layer according to Example 5 was formed by applying a white ink containing titanium oxide (product name "LG-FK690R White C", manufactured by Tokyo Ink Co., Ltd.) and drying at 60 ° C. For the aluminum flake-containing layer, an aluminum flake-containing ink containing non-leaving type aluminum flakes (product name "LG-FK High Concealment Silver D", manufactured by Tokyo Ink Co., Ltd.) is applied to the surface of the white layer, and 60 It was formed by drying at ° C.

<Example 6>
First, as the first biaxially stretched plastic film, a biaxially stretched polyethylene terephthalate film having a thickness of 12 μm (product name “E5100”, manufactured by Toyobo Co., Ltd.) was prepared. Subsequently, a pattern printing layer having a thickness of 1.0 μm is formed on one surface of this film in the same manner as in Example 4, and then light-shielding printing having a thickness of 5 μm is performed on the surface of the pattern printing layer in the same manner as in Example 4. A layer was formed.

Further, as the second biaxially stretched plastic film, a biaxially stretched polyethylene terephthalate film having a thickness of 12 μm (product name “E5100”, manufactured by Toyobo Co., Ltd.) was prepared. A transparent vapor-deposited layer made of silicon oxide having a thickness of 10 nm and a transparent gas barrier coating film having a thickness of 300 nm after drying were formed on one surface of this film in the same manner as in Example 4.

Further, as a sealant film, an unstretched polypropylene film having a thickness of 60 μm (product name “ZK500”, manufactured by Toray Film Processing Co., Ltd.) was prepared.

Then, by the dry laminating method, a biaxially stretched polyethylene terephthalate film, a pattern printing layer, a light-shielding printing layer, a first adhesive layer, a barrier coating film, a transparent vapor deposition layer, a biaxially stretched polyethylene terephthalate film, a second adhesive layer, And unstretched polypropylene film were laminated in order to prepare a packaging material. As the first adhesive layer and the second adhesive layer, a two-component polyurethane adhesive (main agent: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used. The thickness of the first adhesive layer and the second adhesive layer was 3.0 μm.

Then, using these three packaging materials, the pouch according to Example 6 was produced in the same manner as in Example 1. In the sixth embodiment, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

<Example 7>
In Example 7, instead of the light-shielding printing layer consisting of a white layer having a thickness of 1 μm, a white layer having a thickness of 2 μm, and a gray layer having a thickness of 2 μm, a white layer having a thickness of 2 μm and a thickness similar to those in Example 5 have been used. A packaging material was produced in the same manner as in Example 6 except that a light-shielding printing layer composed of a 2 μm aluminum flake-containing layer was formed. Then, using these three packaging materials, the pouch according to Example 6 was produced in the same manner as in Example 1. In Example 7, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

<Example 8>
In Example 8, a packaging material was produced in the same manner as in Example 4 except that the transparent vapor deposition layer and the transparent barrier coating film were not provided. Then, using these three packaging materials, the pouch according to Example 8 was produced in the same manner as in Example 1. In Example 8, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

<Example 9>
In Example 9, a packaging material was produced in the same manner as in Example 5, except that the transparent vapor deposition layer and the transparent barrier coating film were not provided. Then, using these three packaging materials, the pouch according to Example 9 was produced in the same manner as in Example 1. In the ninth embodiment, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

<Example 10>
In Example 10, a packaging material was produced in the same manner as in Example 4 except that the light-shielding printing layer was composed of a laminated structure of a white layer having a thickness of 1 μm and a white layer having a thickness of 1 μm. Then, using these three packaging materials, the pouch according to Example 10 was produced in the same manner as in Example 1. In Example 10, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

<Example 11>
In Example 11, instead of the biaxially stretched polyethylene terephthalate film (product name "E5100", manufactured by Toyo Boseki Co., Ltd.) as the second biaxially stretched plastic film, a biaxially stretched nylon film having a thickness of 15 μm (product name). A packaging material was produced in the same manner as in Example 10 except that "Bonyl QC" (Kojin Film & Chemicals Co., Ltd.) was used. Then, using these three packaging materials, the pouch according to Example 11 was produced in the same manner as in Example 1. In the eleventh embodiment, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

<Comparative example 1>
In Comparative Example 1, instead of the unstretched polypropylene film having a thickness of 60 μm (product name “ZK500”, manufactured by Toray Film Processing Co., Ltd.), the unstretched polypropylene film having a thickness of 70 μm (product name “ZK99S”) was used as a sealant film. , Toray Film Processing Co., Ltd.), a packaging material was produced in the same manner as in Example 1. Then, using these three packaging materials, the pouch according to Comparative Example 1 was produced in the same manner as in Example 1. In Comparative Example 1, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

<Measurement of hot breaking strength>
The breaking strength (hot breaking strength) at 100 ° C. of the packaging material constituting the pouch after the retort treatment according to Examples 1 to 11 and Comparative Example 1 was measured. First, one pouch after the retort treatment according to Examples 1 to 11 and Comparative Example 1 was prepared. As shown in FIG. 4, a rectangular test piece S1 having a side L1 of 15 mm and an other side L2 extending in a direction orthogonal to one side L1 of 100 mm so as not to include a seal portion from the front surface of each pouch. Was cut out. The test piece S1 was cut out so that the other side L2 was parallel to the X direction DRX (the direction orthogonal to the direction in which the first side seal portion extends). Subsequently, as shown in FIG. 5, a rectangular test piece S2 having a side L1 of 15 mm and an other side L2 extending in a direction orthogonal to the side L1 of 100 mm so as not to include the seal portion from the back surface of each pouch. Was cut out. The test piece S2 was cut out so that the other side L2 was parallel to the Y direction DRY (the direction parallel to the direction in which the first side seal portion extends). Then, using the Tensilon universal material tester RTC-1310A (manufactured by A & D Co., Ltd.), each test piece S1 was held for 1 minute in an environment of a temperature of 100 ° C. and a relative humidity of 5%, and then the temperature was 100 ° C. A tensile test was conducted so that the initial gripping tool distance D1 was 50 mm and the tensile speed was 300 mm / min in an environment of 5% relative humidity, and the hot breaking strength of the test piece S1 was measured. In the same manner, the hot breaking strength of the test piece S2 was measured. The hot breaking strength of the five test pieces S1 was measured, and the average value was taken as the hot breaking strength of the packaging material in the X direction. The hot breaking strength of the five test pieces S2 was measured, and the average value was taken as the hot breaking strength of the packaging material in the Y direction.

<Measurement of hot seal strength>
The seal strength (hot seal strength) of the pouches after the retort treatment according to Examples 1 to 11 and Comparative Example 1 at 100 ° C. was measured. First, one pouch after the retort treatment according to Examples 1 to 11 and Comparative Example 1 was prepared. For each pouch, a rectangular test including the first side seal portion, with one side L3 of 15 mm and the other side L4 extending in a direction orthogonal to one side L3 of 70 mm in a state where the front surface film and the back surface film are joined. Five pieces S3 were cut out. Specifically, as shown in FIG. 7, three test pieces S3 were cut out so as to include the first side seal portion, and two test pieces S3 were cut out so as to include the second side seal portion. The test piece S3 was cut out so that the other side L4 was parallel to the X direction DRX (the direction orthogonal to the direction in which the first side seal portion extends) and did not include the steam vent seal portion. The hot seal strength was measured using this test piece S3. The hot seal strength was measured using a Tencilon universal material tester RTC-1310A (manufactured by A & D Co., Ltd.) in accordance with JIS Z1707: 1997 7.5. First, each of the two packaging materials in the unsealed portion of the test piece was gripped by the gripper of the tensile tester. Further, the grippers were pulled in opposite directions in the direction orthogonal to the surface direction of the seal portion of the test piece S3 at a speed of 300 mm / min, and the maximum value of the tensile stress was measured. Then, the average value of the maximum values was taken as the seal strength. The hot seal strength was measured in an environment of 100 ° C. and 5% relative humidity after holding for 1 minute in an environment of 100 ° C. and 5% relative humidity. The hot seal strength of 5 or more test pieces S3 was measured, and the average value was taken as the hot seal strength of the pouch. L3, L4, and S3 are as shown in FIGS. 7 and 8.

<Measurement of total light transmittance>
The total light transmittance of the packaging material constituting the pouch after the retort treatment according to Examples 4 to 11 is measured in accordance with JIS K7361-1: 1997 with a haze meter (product name "HM-150", Murakami Color Co., Ltd.). It was measured using a measurement diameter of 20 mmφ) manufactured by the Institute of Technology. Specifically, first, as shown in FIG. 11, from the front surface of the pouch, one side L5 is 50 mm and the other side L6 extending in a direction orthogonal to one side L5 is 50 mm so as not to include the seal portion. Three square test pieces S4 are cut out, and as shown in FIG. 12, one side L5 is 50 mm and the other side L6 extending in a direction orthogonal to one side L1 is 50 mm from the back surface of the pouch so as not to include the seal portion. Two square-shaped test pieces S4 were cut out. The test piece S4 was cut out so that the other side L6 was parallel to the X direction (the direction orthogonal to the direction in which the first side seal portion extends). After that, the test piece S4 was placed on the haze meter so that the biaxially stretched polyethylene terephthalate film as the first biaxially stretched plastic film was on the light source side without curls or wrinkles, and the temperature was 25 ° C. and the relative humidity was 50. After holding the test piece S4 in an environment of% for 1 minute, the total light transmittance of the test piece S4 was measured in an environment of a temperature of 25 ° C. and a relative humidity of 50%. The total light transmittance of the five test pieces S4 was measured, and the average value was taken as the total light transmittance of the packaging material. L5, L6, and S4 are as shown in FIGS. 11 and 12.

<L ^* value measurement>
The the ^{L *} value packaging material constituting the pouch after the retort processing according to Embodiment 4~11, JIS Z8781-4: 2013 -: complies with (colorimetric Part 4 CIE 1976L ^* a ^* b ^* color space) , Measured using a spectrophotometer (product name "SpectroEye", manufactured by X-Rite). Specifically, first, as shown in FIG. 13, the other side extending from the front surface of the pouch in a direction orthogonal to the side L7 with a side L7 of 5 mm so as not to include the pattern printing layer and the seal portion. Five square test pieces S5 having an L8 of 5 mm were cut out. The test piece S5 was cut out so that the other side L8 was parallel to the X direction (the direction orthogonal to the direction in which the first side seal portion extends). After that, a biaxially stretched polyethylene terephthalate film as a first biaxially stretched plastic film on the test piece S5 is placed on a white plate (material: paper, size: A4 size (210 mm × 297 mm), thickness: 0.3 mm) on the upper surface. It was arranged so as to be. Then, after holding the test piece S5 for 1 minute in an environment of a temperature of 25 ° C. and a relative humidity of 50%, the test piece S5 is subjected to an SCE method (specular reflection light removal method) in an environment of a temperature of 25 ° C. and a relative humidity of 50%. The L ^* value was measured. In the SpectoroEye, the light source was D50 and the viewing angle was 2 °. ^{The L *} value was measured for the five test pieces S5, and the average value was taken as the L ^* value of the packaging material. L7, L8, and S5 are as shown in FIG.

<Light-shielding property>
In the pouch before the retort treatment according to Examples 4 to 9, 200 g of cream stew was added as the content instead of water, the pouch was sealed under the same conditions as in Example 1, and described in the column of Example 1. After performing the retort treatment under the above conditions, the cream stew was visually confirmed to be discolored after being left to stand for 60 days in an environment of a temperature of 25 ° C. and a relative humidity of 50% and under a fluorescent lamp (D65 light source). The evaluation criteria were as follows.
◯: No discoloration of the cream stew was confirmed.
Δ: Some discoloration of the cream stew was confirmed, but it was at a level where there was no problem in the product.
X: A clear discoloration of the cream stew was confirmed.

<Heat resistance>
In the pouches according to Examples 4 to 11, 150 g of minced meat sauce was added as the content instead of water, the pouch was heated in a microwave oven, and holes were confirmed in the packaging material of the pouch after heating, and holes were found. If not confirmed, wrinkles are confirmed. Specifically, first, 150 g of minced meat sauce was put into the pouch before the retort treatment, the pouch was sealed under the same conditions as in Example 1, and the retort treatment was performed under the conditions described in the column of Example 1. .. Then, the pouch after the retort treatment was placed in a microwave oven (model number "NE-MS264", manufactured by Panasonic Corporation) with an output of 600 W in a self-supporting state, and heated for 3 minutes. Then, in the pouch after heating, it was evaluated whether holes were confirmed in the packaging material, and if no holes were confirmed in the packaging material, wrinkles were confirmed. The evaluation criteria were as follows.
◯: No holes were confirmed in the packaging material, and no wrinkles were confirmed.
Δ: No holes were confirmed in the packaging material, but some wrinkles at a level that did not cause any practical problems were confirmed.
X: A hole was confirmed in the packaging material.

Tables 1 to 4 show the composition of the packaging material and the evaluation results.

The results will be described below. As shown in Tables 1 to 3, the packaging materials constituting the pouches according to Examples 1 to 11 have higher hot breaking strength in the X direction than the packaging materials constituting the pouches according to Comparative Example 1. Since it is expensive, even if the pouch swells due to steam when heated in a microwave oven, it is possible to prevent the pouch from breaking. Further, since the packaging material constituting the pouch according to Examples 1 to 11 has a lower hot seal strength than the packaging material constituting the pouch according to Comparative Example 1, it is easy for steam to escape from the steam venting seal portion. It can and can stably remove steam.

As shown in Table 4, in the pouches according to Examples 4 to 9, since a packaging material having a light-shielding printing layer and having a total light transmittance of 25.0% or less is used, photodegradation of the contents is suppressed. did it.

In the pouches according to Examples 4 to 10, a packaging material including a biaxially stretched polyethylene terephthalate film as a first biaxially stretched plastic film and a biaxially stretched polyethylene terephthalate film as a second biaxially stretched plastic film is used. Therefore, from the pouch according to Example 11 using a packaging material provided with a biaxially stretched polyethylene terephthalate film as a first biaxially stretched plastic film and a biaxially stretched nylon film as a second biaxially stretched plastic film. However, it was excellent in heat resistance.

10 ... Pouch 10A ... Storage space 11 ... Front surface film 12 ... Back surface film 13 ... Bottom film 15 ... Sealing part 24 ... Steam vent sealing part 30, 40 ... Packaging material 31 ... First biaxially stretched plastic film 32 ... Second biaxially stretched plastic film 33 ... Sealant film 41 ... Light-shielding printing layer

Claims (10)

A pouch that contains packaging material and has a storage space.
The packaging material includes a first biaxially stretched plastic film, a second biaxially stretched plastic film, and a sealant film in this order.
The sealant film contains polypropylene as a main component.
There are only two biaxially stretched plastic films in the packaging material.
A seal portion for sealing the pouch is provided.
The seal portion includes a steam vent seal portion configured to be peeled off by an increase in pressure in the accommodation space.
The pouch is configured so that the steam venting seal portion can be peeled off to allow steam to escape.
The packaging material has a unidirectional breaking strength of 33.0 MPa or more when measured in an environment of 100 ° C. after being held for 1 minute in an environment of 100 ° C.
A pouch having a seal strength of 20.0 N or less when measured in an environment of 100 ° C after being held for 1 minute in an environment of 100 ° C. The pouch according to claim 1, wherein the product of the tensile elongation (%) and the thickness (μm) of the sealant film in one direction exceeds 50,000. The pouch according to claim 1 or 2, wherein the product of the tensile elongation (%) and the thickness (μm) of the sealant film in a direction orthogonal to the one direction exceeds 55,000. The pouch according to any one of claims 1 to 3, wherein the sealant film contains a propylene / ethylene block copolymer and an elastomer. Claims 1 to 4, wherein the first biaxially stretched plastic film is a biaxially stretched polyethylene terephthalate film, and the second biaxially stretched plastic film is a biaxially stretched polyethylene terephthalate film or a biaxially stretched nylon film. The pouch according to any one item. The packaging material further comprises a transparent vapor-deposited layer provided between the first biaxially stretched plastic film and the second biaxially stretched plastic film, and the transparent vapor-deposited layer comprises a metal oxide or an inorganic oxide. The pouch according to any one of claims 1 to 5, including the pouch according to any one of claims 1 to 5. The pouch according to claim 6, wherein the packaging material further includes a transparent gas barrier coating film provided on the surface of the transparent vapor deposition layer. Claimed that the packaging material further comprises a light-shielding printing layer provided between the first biaxially stretched plastic film and the sealant film, and the total light transmittance of the packaging material is 25.0% or less. Item 5. The pouch according to any one of Items 1 to 7. The pouch according to claim 8, wherein the ^{L * value in the L *} a ^* b ^* color system measured by the SCE method (specular light removal method) of the packaging material is 65.0 or more. The pouch according to any one of claims 1 to 9, wherein the contents are housed in the storage space of the pouch.

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