Filled packaging body and vinylidene chloride-based resin stretch film

Abstract

Provided are a filled packaging body that stably exhibits easy openability of a longitudinal seal portion, and a vinylidene chloride-based resin stretch film that provides the filled packaging body. The filled packaging body of the present invention is a filled packaging body in which contents are filled and enclosed in a cylindrical vinylidene chloride-based resin stretch film that has a longitudinal seal portion extending in a long dimension direction and both end portions in the long dimension direction are constricted, and the vinylidene chloride-based resin stretch film is formed from a resin composition containing a vinylidene chloride-based resin and an ethylene-based resin, the proportion of constituent units derived from ethylene in the ethylene-based resin is 50% by mass or more, the T-peel strength of the longitudinal seal portion is 7 to 13 N / 15 mm, and in the vinylidene chloride-based resin stretch film, the proportion of the number of dispersed phases having a length and width of 2 μm or more in the total number of dispersed phases of the ethylene-based resin is 20% to 50%.

Description

Technical Field

[0001] This invention relates to filler packaging and vinylidene chloride-based resin stretch film. Background Technology

[0002] In tubular packaging, which is made by filling the contents of solid or paste-like processed foods such as sausages, stick cheese, and fish cakes into a tubular film and tying both ends, a so-called envelope-style seal is often used, where the surface of one edge of the film, which is formed by rolling a strip of film into a tube, is overlapped with the back of the other edge and sealed.

[0003] As a strip film preform roll, most of the time, a tubular film formed by blowing vinylidene chloride resin is folded into two flat, overlapping layers, and then the two layers are cut and processed into strips of the required width.

[0004] In recent years, research has been conducted on improving the opening properties of cylindrical filled packaging. Patent document 1 describes an easy-open packaging that can be opened by pinching the outer ear of the cylindrical packaging, which consists of two overlapping layers of film, with fingers to cut off the sealing part. Patent document 2 describes an easy-open packaging that embodies the easy-open function of longitudinal sealing part peeling through a resin composition formed by vinylidene chloride resin and ethylene-vinyl acetate copolymer.

[0005] Furthermore, Patent Document 3 describes that, in the case of a vinylidene chloride-based resin film containing ultra-low density polyethylene resin and ionomer resin, and a filling package containing lipid contents, the problem of insufficient color retention period of the contents before and after cooking can be eliminated, but it does not describe the film composition that helps improve the opening performance or the opening mechanism of the tubular filling package.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2021-1027

[0009] Patent Document 2: International Publication No. 2023 / 032632

[0010] Patent Document 3: International Publication No. 2022 / 209039 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] Currently, the opening performance of the longitudinal seal (the cylindrical seal along its long dimension) in filled packaging exhibits many deviations. For example, ... Figure 1 and Figure 2As shown, when opening a cylindrical filler package consisting of two overlapping layers of film by pinching the outer ear with fingers, sometimes the sealing part of the inner radial layer of the outer ear does not peel off, or only the outer radial layer of the outer ear peels off, resulting in poor opening conditions (sometimes called single-layer peeling). It is difficult to say that the current filler package has achieved stable easy opening of the longitudinal seal, which may lead to a significant problem of reduced product value.

[0013] The present invention was made in view of the above-mentioned problems, and its object is to provide a filler packaging body that can stably embody the easy-opening property of the longitudinal seal, and a vinylidene chloride resin stretch film for providing the filler packaging body.

[0014] Solution for solving the problem

[0015] The inventors have discovered that in a vinylidene chloride-based resin stretch film containing ethylene-based resin, the dispersion state of the ethylene-based resin dispersed phase in the vinylidene chloride-based resin is closely related to the poor opening and unstable opening of the longitudinal sealing portion mentioned above.

[0016] Furthermore, it was discovered that in vinylidene chloride-based resin stretched films, by controlling the proportion of dispersed phases with a length and width of 2 μm or more in the total number of dispersed phases of the ethylene resin to 20% to 50%, and by controlling the T-shaped peel strength of the longitudinal sealing part to 7 to 13 N / 15 mm, the above-mentioned technical problems can be solved, thus completing the present invention.

[0017] Specifically, the present invention provides the following:

[0018] (1) A filler package is formed by filling and sealing contents into a cylindrical vinylidene chloride resin stretch film having a longitudinal sealing portion extending along the longitudinal dimension and being constricted at both ends in the longitudinal dimension, the vinylidene chloride resin stretch film being formed from a resin composition containing vinylidene chloride resin and ethylene resin, wherein the proportion of ethylene-derived constituent units in the ethylene resin is 50% by mass or more relative to all constituent units constituting the ethylene resin, the T-peel strength of the longitudinal sealing portion is 7 to 13 N / 15 mm, and the proportion of dispersed phases with a length and width of 2 μm or more in the total number of dispersed phases of the ethylene resin in the vinylidene chloride resin stretch film is 20% to 50%.

[0019] (2) The filling package according to (1), wherein the filling package has been subjected to a cooking process.

[0020] (3) A vinylidene chloride-based resin stretch film, wherein the vinylidene chloride-based resin stretch film is formed from a resin composition containing a vinylidene chloride-based resin and an ethylene-based resin, wherein the proportion of ethylene-derived constituent units in the ethylene-based resin is 50% by mass or more relative to all constituent units constituting the ethylene-based resin, the amount of the ethylene-based resin is 2.0 to 3.0 parts by mass relative to 100 parts by mass of the vinylidene chloride-based resin, the melt flow rate of the ethylene-based resin is 0.1 to 10 g / 10 min, and the melting peak temperature of the ethylene-based resin is 100 to 130 °C.

[0021] (4) The vinylidene chloride resin stretch film according to (3), wherein the vinylidene resin is an ethylene homopolymer.

[0022] Invention Effects

[0023] According to the present invention, the ease of opening of the longitudinal seal can be consistently maintained in a filled package containing refined processed food or similar contents. Furthermore, a vinylidene chloride-based resin stretch film for realizing this filled package can be provided. Attached Figure Description

[0024] Figure 1 This is an example of a schematic diagram of a filled package.

[0025] Figure 2 This is an example of a schematic cross-sectional view near the longitudinal seal of a tubular filler package consisting of two overlapping layers of film.

[0026] Figure 3 (a) is Figure 1 A-A' cross-sectional view. Figure 3 (b) is Figure 3 The enlarged view of region B in (a) is a diagram showing the dispersion state of the vinylidene chloride resin dispersed phase in a cross section perpendicular to the longitudinal dimension of the stretched film.

[0027] Figure 4 This is a schematic cross-sectional image of the vinylidene chloride-based resin stretched film of Example 3.

[0028] Figure 5 This is a schematic cross-sectional image of the vinylidene chloride-based resin stretched film of Comparative Example 9. Detailed Implementation

[0029] The present invention will be described in detail below. However, the following description is only one example of an embodiment of the present invention. As long as it does not depart from its spirit, the present invention is not limited to the following description and can be arbitrarily modified and implemented within the scope of the present invention. It should be noted that in this specification, when "~" is used to represent numerical or physical property values, the values ​​before and after it are included.

[0030] ≪Filled Packaging Body≫

[0031] The filled packaging is formed by filling and sealing the contents into a cylindrical vinylidene chloride-based resin stretched film, which has a longitudinal sealing portion extending along its length and is tapered at both ends along its length. The vinylidene chloride-based resin stretched film is formed from a resin composition containing vinylidene chloride resin and ethylene resin. The T-peel strength of the longitudinal sealing portion is 7–13 N / 15 mm. In the vinylidene chloride-based resin stretched film, the proportion of dispersed phases with a length and width of 2 μm or more out of the total dispersed phase of the ethylene resin is 20%–50%.

[0032] The mechanism by which the filled packaging can reliably achieve easy-openability is presumed as follows.

[0033] The inventors presume that in a filled package containing a vinylidene chloride-based resin stretch film comprising an ethylene-based resin, the mechanism by which the film peels off from the longitudinal seal is that the force of opening causes a point of destruction at the interface between the vinylidene chloride-based resin and the ethylene-based resin, and the cracks caused by the destruction propagate radially.

[0034] Furthermore, the inventors discovered that, as Figure 3 As shown in (b), the dispersion state of the vinylidene chloride resin in the cross-section perpendicular to the long dimension of the stretched film affects the generation of the initiation point of failure.

[0035] If the dispersed phase of an ethylene-based resin is relatively large, the number of dispersed phases decreases, thus the opening force causes stress concentration at the interface, making it easier to initiate damage. On the other hand, if the dispersed phase of an ethylene-based resin is too small, the number of dispersed phases increases, thus the opening force is dispersed across many interfaces, resulting in no stress concentration and making it difficult to initiate damage.

[0036] By controlling the proportion of dispersed phases with a length and width of 2 μm or more in the total number of dispersed phases of ethylene-based resins to 20% to 50%, the size and quantity of dispersed phases become appropriate, and easy-to-open properties can be stably achieved.

[0037] It should be noted that, in this specification, the "dispersed phase" of the vinylidene chloride resin refers to the structure in which the vinylidene chloride resin is separated into domains (dispersed islands) relative to the vinylidene chloride resin phase in a cross-section perpendicular to the longitudinal dimension of the vinylidene chloride resin stretched film. Furthermore, "length-width" refers to the maximum width of the dispersed phase in a cross-section perpendicular to the longitudinal dimension of the vinylidene chloride resin stretched film, in the direction perpendicular to the thickness direction of the vinylidene chloride resin stretched film (the radial direction of a cylindrical vinylidene chloride resin stretched film) (the shortest distance between two straight lines parallel to the thickness direction that enclose the dispersed phase).

[0038] <Venevinylidene chloride-based resin stretch film>

[0039] The vinylidene chloride-based resin stretch film that forms a cylindrical vinylidene chloride-based resin stretch film is formed from a resin composition containing vinylidene chloride-based resin and ethylene-based resin.

[0040] [Vinyl chloride-based resins]

[0041] Vinylidene chloride resins (hereinafter, sometimes referred to as "PVDC") can be homopolymers of vinylidene chloride or copolymers of vinylidene chloride in a ratio of 60% to 98% by mass with other monomers that can copolymerize with vinylidene chloride in a ratio of 2% to 40% by mass. Other monomers that can copolymerize with vinylidene chloride include, for example: vinyl chloride; alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, and lauryl acrylate (the alkyl group has 1 to 18 carbon atoms); alkyl methacrylates such as methyl methacrylate, butyl methacrylate, and lauryl methacrylate (the alkyl group has 1 to 18 carbon atoms); vinyl cyanide such as acrylonitrile; aromatic vinyl groups such as styrene; vinyl esters of aliphatic carboxylic acids such as vinyl acetate (the alkyl group has 1 to 18 carbon atoms); alkyl vinyl ethers with 1 to 18 carbon atoms; vinyl polymerizable unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid; alkyl esters of vinyl polymerizable unsaturated carboxylic acids such as maleic acid, fumaric acid, and itaconic acid (including esters, the alkyl group has 1 to 18 carbon atoms), etc. More preferably, at least one selected from vinyl chloride, methyl acrylate, and lauryl acrylate. Other monomers that can copolymerize with vinylidene chloride can be used alone or in combination of two or more. The copolymerization ratio of other monomers is more preferably 3% by mass or more and 35% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less. If the copolymerization ratio of other monomers is 3% by mass or more, melt processability is less likely to decrease; on the other hand, if the copolymerization ratio of other monomers is 35% by mass or less, gas barrier properties are less likely to decrease. Furthermore, to improve melt processability, two or more PVDCs can be blended. PVDCs can be synthesized by any polymerization method such as suspension polymerization, emulsion polymerization, or solution polymerization.

[0042] In particular, when the other monomer that can copolymerize with vinylidene chloride is vinyl chloride, from the viewpoint of melt processability and gas barrier properties, PVDC is preferably a copolymer of vinylidene chloride of 60% to 95% by mass and vinyl chloride of 5% to 40% by mass, more preferably a copolymer of vinylidene chloride of 63% to 90% by mass and vinyl chloride of 10% to 37% by mass, even more preferably a copolymer of vinylidene chloride of 66% to 85% by mass and vinyl chloride of 15% to 34% by mass, and particularly preferably a copolymer of vinylidene chloride of 69% to 83% by mass and vinyl chloride of 17% to 31% by mass.

[0043] [Ethylene-based resins]

[0044] In ethylene-based resins, the proportion of ethylene-derived constituent units is 50% by mass or more relative to all constituent units constituting the ethylene-based resin. The proportion of ethylene-derived constituent units in the ethylene-based resin is preferably 70% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, particularly preferably 97% by mass or more, and may also be 100% by mass. Examples of ethylene-based resins include ethylene homopolymers and copolymers of ethylene with other monomers capable of copolymerizing with ethylene. Among these, ethylene homopolymers are preferred because they have low affinity for vinylidene chloride-based resins and low interfacial strength with vinylidene chloride-based resins, thus easily initiating damage and promoting crack propagation; and they are not easily responsive to high-frequency heat sealers used in longitudinal sealing and their dispersion state is not easily changed during high-frequency heat sealer welding.

[0045] Other monomers that can copolymerize with ethylene include: vinyl esters of aliphatic carboxylic acids with 1 to 18 carbon atoms, such as vinyl acetate; vinyl polymerizable unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid; etc. Other monomers that can copolymerize with ethylene can be used alone or in combination of two or more.

[0046] The melt flow rate (MFR) of the vinyl resin is preferably 0.1–10 g / 10 min, more preferably 0.2–5 g / 10 min, even more preferably 0.3–2 g / 10 min, and particularly preferably 0.3–1 g / 10 min. If it is 0.1 g / 10 min or higher, the vinyl resin is easily dispersed in the vinylidene chloride resin during stretch film forming, reducing the likelihood of appearance defects such as fisheyes and foreign matter, and minimizing weaknesses in the film's physical properties. If it is 10 g / 10 min or lower, the vinyl resin is not sufficiently finely dispersed in the vinylidene chloride resin during stretch film forming, making it difficult to disperse the stress generated upon opening, easily creating a point of failure, and thus easily exhibiting easy-openability.

[0047] In this specification, the MFR of ethylene-based resins is determined by the methods described in the examples below.

[0048] The melting peak temperature (Tpm) of the vinyl resin is preferably 100–130°C, more preferably 103–125°C, and even more preferably 105–120°C. Vinyl resins with a Tpm above 100°C do not melt due to heat transfer from the heated vinylidene chloride resin during high-frequency heat sealing and are less prone to deformation, thus easily maintaining their original dispersed phase shape. As a result, the propagation direction of cracks generated during opening is easily stabilized, and opening is less likely to become incomplete. Vinyl resins with a Tpm below 130°C fully melt during stretch film forming, thus easily dispersing the vinyl resin within the vinylidene chloride resin, reducing the likelihood of appearance defects such as fisheyes and foreign matter, and minimizing vulnerabilities in the film's physical properties.

[0049] In this specification, the Tpm of ethylene-based resins is determined by the method described in the examples described later.

[0050] The density of ethylene-based resins is preferably greater than 885 kg / m³. 3 And less than 940 kg / m 3 More preferably, it is 900–930 kg / m³. 3 Further preferred is 918–928 kg / m³ 3 Density greater than 885 kg / m³ 3 When vinyl resins are used in stretch film forming, they are not dispersed too finely within vinylidene chloride resins. Therefore, the stress generated during opening is not easily dispersed, making it easier to create a point of failure and thus exhibiting easy-to-open properties. In particular, when the resin is a homopolymer of vinylidene chloride, it does not melt due to heat transfer from the heated vinylidene chloride resin during high-frequency heat sealing and is not easily deformed. Therefore, it easily maintains the original dispersed phase shape. As a result, the direction of crack propagation during opening is more stable, and opening is less likely to become incomplete. Density less than 940 kg / m³ 3 The ethylene-based resin is fully melted during stretch film forming, making it easy to disperse the ethylene-based resin in the vinylidene chloride-based resin. This reduces the likelihood of appearance defects such as fish eyes and foreign matter, as well as the vulnerability of the film as a physical property.

[0051] In this specification, the density of the ethylene-based resin was determined using the method described in the examples described later.

[0052] In the vinylidene chloride-based resin composition, the amount of ethylene resin relative to 100 parts by weight of vinylidene chloride-based resin is preferably 2.0 to 3.0 parts by weight, more preferably 2.3 to 2.8 parts by weight, and even more preferably 2.4 to 2.6 parts by weight. If it is 2.0 parts by weight or more, the number of dispersed phases of ethylene resin in the vinylidene chloride-based resin composition is sufficient, making it easier to expand the starting point of damage caused by the force of opening the seal. If it is 3.0 parts by weight or less, the proportion of ethylene resin in the vinylidene chloride-based resin composition is not large, so the weld strength in the high-frequency heat sealing process (high-frequency medium heating sealing process) does not weaken, and it is less likely to cause the problem of seal peeling during the cooking process after filling, thus failing to perform the function of the packaging.

[0053] [The proportion of dispersed phases with a length and width of 2 μm or more]

[0054] In the vinylidene chloride-based resin stretch film of the filled packaging after cooking, the proportion of dispersed phases with a length and width of 2 μm or more in the total number of dispersed phases of the vinylidene resin is 20% to 50%. Preferably, this proportion is 21% to 48%, more preferably 22% to 46%. If it is above 20%, the dispersed phase is relatively large and the number of dispersed phases is relatively small. Therefore, the force required to open the package will cause stress concentration at the interface between the dispersed phase and the vinylidene chloride resin, easily creating a point of failure. If it is below 50%, the dispersed phase is relatively small and the number of dispersed phases is relatively large. Therefore, it is less likely to be opened with minimal force, and the packaging can function more effectively.

[0055] In this specification, the proportion of dispersed phases with a length and width of 2 μm or more in the total number of dispersed phases of the ethylene-based resin is determined by the method described in the examples below.

[0056] The proportion of dispersed phases with a length and width of 2 μm or more in the total number of dispersed phases of ethylene-based resins can be adjusted, for example, by the type and amount of ethylene-based resin, MFR, melting peak temperature, screw diameter and draw ratio when melt-extruding the vinylidene chloride-based resin composition.

[0057] 〔additive〕

[0058] The vinylidene chloride-based resin composition may contain various additives, such as heat stabilizers, plasticizers, processing aids, colorants, UV absorbers, pH adjusters, and dispersants, which are conventionally added to tubular packaging films used in fillers to improve various properties and molding processability. For example, heat stabilizers include epoxidized vegetable oils, epoxidized animal oils, epoxidized fatty acid esters, epoxy resin prepolymers, and other epoxy compounds; epoxy-containing resins are also possible, with epoxidized vegetable oils being preferred. The type and amount of additives can be selected similarly to those used in conventional tubular packaging films. Additives can be used alone or in combination of two or more. Furthermore, additives can be included in the monomer composition in part or all of their amount during the PVDC polymerization process, or they can be blended with PVDC after polymerization.

[0059] <Filled Packaging and its Manufacturing Methods>

[0060] Filling the packaging, for example, Figure 1 As shown, a cylindrical polyvinylidene chloride (PVC) resin stretch film is formed by overlapping the two side edges of the PCC resin stretch film with the front and back sides facing each other, and sealing it longitudinally in the long dimension. The contents are then filled into the film, and both ends are sealed. The side edges of the PCC resin stretch film form external ears that extend outwards in a strip shape towards the outside of the cylindrical PCC resin stretch film. According to this filled packaging, when opening by pinching the external ears with fingers, even if the two films located radially inner and two films located radially outer are fused together, it is not easy to open incompletely.

[0061] [Manufacturing of strip-shaped vinylidene chloride-based resin stretched films]

[0062] The vinylidene chloride-based resin stretch film is formed from a vinylidene chloride-based resin composition. It can be composed of a single sheet with a thickness of 10 to 300 μm, or it can be composed of two overlapping sheets. Since single-sheet peeling and other opening defects are prone to occur, it is preferable to use two overlapping sheets to maximize the effectiveness of the invention.

[0063] There are no particular limitations on the manufacturing method of the strip-shaped vinylidene chloride (VCC) resin stretch film used to form the tubular VCC resin stretch film. Typically, sheet or tubular extruded films are manufactured by extrusion molding. After stretching to impart heat shrinkage, in the case of tubular extruded films, the inner sides are overlapped to obtain two overlapping (two-layer) strip-shaped VCC resin stretch films with a specified width. These are then further cut along the longitudinal direction as needed, thereby enabling the manufacture of strip-shaped VCC resin stretch films with a desired width.

[0064] The stretch ratio in the longitudinal direction (MD) is not particularly limited, but may be, for example, 2 to 4 times, 2.1 to 3.5 times, or 2.2 to 3 times. In addition, the stretch ratio in the transverse direction (TD) is preferably 2 to 5 times, more preferably 3 to 4.8 times, and even more preferably 3.5 to 4.5 times.

[0065] The thickness of a single sheet of vinylidene chloride-based resin stretch film is determined by considering the film strength and barrier properties corresponding to the contents being filled. It is in the range of 10 to 300 μm, with 12 to 100 μm being the most common and 15 to 80 μm being the most widely used range.

[0066] When printing is performed on a cylindrical vinylidene chloride-based resin stretch film, the resulting strip-shaped vinylidene chloride-based resin stretch film can also be printed.

[0067] [Longitudinal sealing portion extending in the longitudinal direction]

[0068] Regarding the longitudinal sealing portion extending along the length direction of the cylindrical vinylidene chloride-based resin stretch film, it is achieved by placing the back sides of the strip-shaped vinylidene chloride-based resin stretch film facing each other (clasp-type sealing) along the length direction, or as... Figure 1 and Figure 2 As shown, a tubular film is formed by rolling the two side edges together in a manner where the front and back sides face each other (envelope-style sealing). Then, the two side edges of the tubular film are continuously sealed (welded) along the longitudinal direction using conventional methods such as high-frequency dielectric heating, thereby forming a tubular vinylidene chloride (VDC) resin stretch film. The longitudinal sealing portion extends along the entire length of the tubular VDC resin stretch film, thus ensuring that the contents filled and sealed within the tubular VDC resin stretch film are kept in a sealed state. The width of the longitudinal sealing portion extending along the longitudinal direction of the tubular VDC resin stretch film can be appropriately determined.

[0069] In the retorted packaging, the T-peel strength of the longitudinal seal is 7–13 N / 15 mm, preferably 8–13 N / 15 mm, and more preferably 9–13 N / 15 mm. If it is 7 N / 15 mm or higher, the packaging is less likely to open due to small impacts during handling, sealing, and transportation. If it is 13 N / 15 mm or lower, it is easy to open.

[0070] In this specification, the T-shaped peel strength of the longitudinal seal is measured using the method described in the examples described later.

[0071] The T-peel strength of the longitudinal seal can be adjusted, for example, by the type, amount, and MFR of the vinyl resin.

[0072] [The outer ear extending along its longitudinal direction]

[0073] The cylindrical vinylidene chloride (VDC) resin stretch film has an outer ear extending along its longitudinal direction. This outer ear, extending along the longitudinal direction, refers to the non-sealed portion of the cylindrical VDC resin stretch film formed by sealing the ends of the side edges that are orthogonal to the longitudinal direction, which are not exposed on the outer surface, when the two side edges of the previously described cylindrical VDC resin stretch film are continuously sealed (welded) along the longitudinal direction using conventional methods. The width of the outer ear is not particularly limited, typically ranging from 1 to 10 mm, and in most cases from 2 to 6 mm. It should be noted that the outer ear (non-sealed portion) extending along the longitudinal direction usually covers the entire length of the cylindrical VDC resin stretch film and is formed with a uniform width, but it can also be formed with varying widths of the outer ear (non-sealed portion). Because the cylindrical VDC resin stretch film has an outer ear extending along the longitudinal direction and a longitudinal sealing portion, the longitudinal sealing portion can be peeled off and opened by pinching and stretching the outer ear.

[0074] In addition, the outer ear portion extending along the length direction can be printed, and may also have scratches, indentations, cuts, notches, through holes, non-through holes, etc.

[0075] [Convergence at both ends along the longitudinal direction]

[0076] The filler packaging includes a cylindrical vinylidene chloride (VDC) resin stretch film whose ends are constricted along its longitudinal direction. Specifically, the filler packaging is formed by filling processed food or other contents into the cylindrical VDC resin stretch film and then constricting the ends of the film along its longitudinal direction, thus preserving the contents in a sealed state. The constriction of the ends of the cylindrical VDC resin stretch film along its longitudinal direction can employ conventional methods for constricting the ends of the cylindrical VDC resin stretch film in filler packaging, such as using metal clamps like aluminum wire clips, transverse sealing films (clamps), or other constriction methods.

[0077] [The contents that are filled and sealed into a cylindrical vinylidene chloride-based resin stretch film]

[0078] There are no particular limitations on the contents that are filled and sealed into the cylindrical vinylidene chloride resin stretch film. Solid or paste-like processed foods such as sausages, cheese, butter, hamburger patties, roko, yokan, and jelly, which are traditionally used as fillings in filled packaging, can be used. Furthermore, other non-food items such as building materials, sealant, and cosmetics can also be used as contents.

[0079] The composition and shape of the contents can be appropriately selected. As particularly preferred contents, examples include fish sausages made by mixing minced fish meat with common additives such as oil, salt, and starch.

[0080] [Steaming / cooking treatment]

[0081] After the contents are filled, the packaged food is subjected to a cooking process. Cooking is a method of sterilizing food by applying pressure to kill microorganisms such as mold, yeast, and bacteria for preservation purposes. Typically, the packaged food is sterilized under pressure at 105–140°C and 0.15–0.3 MPa for 5–120 minutes. Cooking equipment includes steam-type equipment that uses heated steam and hot water-type equipment that uses pressurized superheated water; the appropriate type is used depending on the sterilization requirements of the food contained within.

[0082] [Sensory evaluation of Kaifeng]

[0083] The sensory evaluation value of the sealing strength of the filled packaging after cooking is preferably 2.5 to 3.5 points, more preferably 2.6 to 3.4 points, and even more preferably 2.7 to 3.3 points. If the value is 2.5 points or higher, the filled packaging is less likely to be opened by small impacts during handling, sealing, and transportation. If the value is below 3.5 points, it is easy to open.

[0084] In this specification, sensory evaluation of openability is performed using the methods described in the examples described later.

[0085] [Normal opening rate]

[0086] The normal opening rate of the filled packaging after the cooking treatment is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more. If it is 60% or more, the ease of opening becomes sufficient.

[0087] In this specification, the normal opening rate is determined by the method described in the examples below.

[0088] ≪Polyvinylidene chloride-based resin stretch film≫

[0089] The vinylidene chloride-based resin stretched film is formed from a resin composition containing vinylidene chloride-based resin and ethylene-based resin. The amount of ethylene-based resin is 2.0 to 3.0 parts by weight relative to 100 parts by weight of vinylidene chloride-based resin. The melt flow rate of the ethylene-based resin is 0.1 to 10 g / 10 min. The melting peak temperature of the ethylene-based resin is 100 to 130 °C.

[0090] The aforementioned filled packaging can be obtained by using such a vinylidene chloride-based resin stretch film.

[0091] The preferred method for vinylidene chloride-based resin stretch film is the same as that for vinylidene chloride-based resin stretch film in ≪filled packaging ≫.

[0092] Example

[0093] The present invention will be described in more detail below with examples and comparative examples, but the present invention is not limited to these examples.

[0094] Melt Flow Rate (MFR)

[0095] The MFR (g / 10min) of vinyl resins was determined according to ISO 1133:1997 Conditions M, at a temperature of 190℃, a load of 2.16 kg, and for 10 minutes. The results are shown in Table 1.

[0096] [Melting peak temperature (Tpm)]

[0097] The Tpm (°C) of vinyl resins was determined according to JIS K7121 using a differential scanning calorimeter (DSC) by the following method. The results are shown in Table 1.

[0098] After temporarily raising the temperature to 190℃ to eliminate the thermal history, the temperature was lowered to -10℃ at a cooling rate of 10℃ / min, and then raised again at a heating rate of 10℃ / min. The temperature of the endothermic peak at the time of measurement was set as Tpm.

[0099] [The proportion of dispersed phases with a length and width of 2 μm or more]

[0100] For the tubular membrane after removing the contents from the filled packaging following the cooking process, a sample was cut from the center of a cross-section perpendicular to the long dimension of the membrane. The sample was embedded in epoxy resin, trimmed using a cryo-microtome, and observed using a scanning electron microscope (Hitachi High Technology Co., Ltd., SU-8020) at an accelerating voltage of 0.8–1.0 keV and a magnification of 5000x.

[0101] Next, an arbitrary 22μm × 16μm region was selected from the obtained image, and color levels were adjusted using Photoshop to clearly define the boundaries of the dispersed phase of the ethylene-based resin. Image processing software (Mitani Corporation, WinROOF) was used to extract the length and width of the dispersed phase in this region. Schematic diagrams of the processed images obtained in Example 3 and Comparative Example 9 are shown below. Figure 4 and Figure 5 .

[0102] The total number of dispersed phases and the number of dispersed phases with a length and width greater than 2 μm were counted for the ethylene-based resins. The proportion of dispersed phases with a length and width greater than 2 μm in the total number of dispersed phases of the ethylene-based resins was calculated using the following formula. The results are shown in Table 1. Note that in the count of the total number of dispersed phases, those with a length and width less than 0.003 μm and an area of ​​0.009 μm were excluded. 2 The following are examples of dispersed phases with a short width of 0.001 μm or less. It should be noted that "short width" refers to the maximum width of the dispersed phase in the thickness direction of a vinylidene chloride-based resin stretched film in a cross-section perpendicular to its longitudinal dimension (the shortest distance between two straight lines parallel to the direction perpendicular to the thickness direction that enclose the dispersed phase). For example, for... Figure 4 The dispersed phase in the upper right corner has a length of l and a width of w.

[0103] The percentage (%) of dispersed phases with a length and width greater than 2 μm in the total number of dispersed phases of ethylene-based resins = (Number of dispersed phases with a length and width greater than 2 μm / Total number of dispersed phases) × 100

[0104] [Density of vinyl resins]

[0105] Density of vinyl resins (kg / m³) 3 According to JIS K7112, the determination was performed by water displacement method. The results are shown in Table 1.

[0106] [T-shaped peel strength]

[0107] The T-peel strength of the longitudinal seal in the filled packaging was determined according to JIS K6854 using a Tensilon universal testing machine manufactured by Orientec, and the results are shown in Table 1.

[0108] For a tubular film after the contents have been removed from a filled package following a cooking process, the strength of the film is measured by clamping it with the fixtures of a testing machine at a temperature of 23°C and a tensile speed of 300 mm / min. This measurement is performed on a portion 15 mm long along the longitudinal direction of the outer ear portion approximately in the center of the film and a portion 15 mm long along the longitudinal direction of the body portion (the portion of the tubular film excluding the longitudinal sealing portion).

[0109] [Sensory evaluation of Kaifeng]

[0110] The sealing strength of the filled packaging after retorting was evaluated using the following sensory methods. The results are shown in Table 1.

[0111] Ten subjects each had five stuffing packages. The strength of the resistance felt when peeling the longitudinal seal by pinching the outer edge of each stuffing package with their fingers was assigned a score (ranging from "1" to "5") according to the following criteria. The average score assigned to a total of 50 stuffing packages was calculated (expressed as a score to one decimal place).

[0112] (Judgment Criteria)

[0113] 5 points: Even with strong longitudinal sealing, it does not peel off, or the longitudinal sealing or outer ear breaks.

[0114] 4 points: If strong force is applied, the longitudinal seal will peel off.

[0115] 3 points: The seal is peeled off longitudinally with moderate force.

[0116] 2 points: The seal is peeled off longitudinally with weak force.

[0117] 1 point: It peels off with just a light touch to the longitudinal seal.

[0118] [Normal opening rate]

[0119] The openability of the filled packaging was evaluated using the following methods. The results are shown in Table 1.

[0120] Ten subjects each received five filler packages (total number: 50). When the package was opened by pinching the outer ear with their fingers, the proportion of the two outermost films peeling off from the longitudinal seal was taken as the opening rate and calculated by the following formula.

[0121] Opening rate (%) = ((number of two films placed on the radially outer side peeled off from the longitudinal seal) / 50) × 100 (where the first decimal place is rounded off).

[0122] [Ethylene-based resins]

[0123] LDPE1: UBE polyethylene R300 manufactured by Ube Maruzen Polyethylene Co., Ltd.

[0124] LDPE2: NUC-8350 manufactured by ENEOS NUC.

[0125] LDPE3: DNDJ-0405 manufactured by ENEOS NUC.

[0126] LDPE4: Novatec LD LF280 manufactured by Japan Polyethylene Co., Ltd.

[0127] EVA: Evaflex V5274 manufactured by Mitsui & Dow Polymer Chemicals.

[0128] VLDPE: Tafmer A4085S manufactured by Mitsui Chemicals.

[0129] Ionomer: Surlyn 1707 manufactured by Dow Company.

[0130] [Example 1]

[0131] (Manufacturing of vinylidene chloride-based resin stretched film)

[0132] Relative to 100 parts by weight of polyvinylidene chloride (PVDC) resin, this PVDC resin is formed by a mixture of 85 parts by weight of a copolymer polymerized with vinylidene chloride (VD) and vinyl chloride (VC) at a monomer input ratio (VD / VC) of 81 / 19, a polymerization temperature of 34°C to 49°C and a polymerization time of 44 hours, and 15 parts by weight of a copolymer polymerized with a VD / VC ratio of 71 / 29, a polymerization temperature of 43°C to 58°C and a polymerization time of 37 hours. It also includes a total of 5.4 parts by weight of acetylated tributyl citrate (ATBC), dibutyl sebacate (DBS), and epoxidized vegetable oil, plus a total of 1.83 parts by weight of an epoxy-containing polymer, antioxidant, surfactant, erucamide, and calcium carbonate, and finally 2.5 parts by weight of a polymer with a density of 920 kg / m³. 3 LDPE1, an ethylene homopolymer with a melt flow rate (MFR) of 0.35 g / 10 min and a melt peak temperature of 109 °C, was melt-extruded using an extrusion screw with a diameter of 40 mm to obtain a vinylidene chloride-based resin composition.

[0133] Next, at room temperature, the tubular film is blown and biaxially stretched under conditions of 2.5 times in the MD (longitudinal) and 4.1 times in the TD (transverse) direction, and then folded into two flat overlapping sheets (2 layers) to obtain a vinylidene chloride resin stretched film (2-layer laminated film) a with a total thickness of 40 μm (the thickness of two 20 μm films).

[0134] (Manufacturing of the filling packaging)

[0135] A base film (vinylidene chloride resin stretch film a) cut to a width of 84 mm is placed in an automatic filling and packaging machine (manufactured by Kureha Corporation, trade name: KAP8000 automatic filling and packaging machine). The base film is rolled into a cylindrical shape with the inner and outer surfaces facing each other on both sides extending in the longitudinal direction to form a cylindrical PVDC film. While the cylindrical PVDC film is moving downward, the overlapping sides of the cylindrical PVDC film are passed between a sealing electrode (an outer electrode with a semi-circular front end processed into a radius of 1 mm) of a high-frequency dielectric heating device that applies high-frequency electricity based on a specified voltage and current and a grounding electrode (inner electrode) (the force of the outer electrode pressing towards the inner electrode is set to 500 g). Two films arranged on the radially inner side of the two sides of the cylindrical PVDC film and two films arranged on the radially outer side are fused together to form a cylindrical PVDC film having an outer ear portion with a width of 8 mm extending in the longitudinal direction and a longitudinal sealing portion.

[0136] Next, minced fish sausage is fed into the longitudinally sealed PVDC film through a nozzle from the filling device. Two pairs of cylindrical feeding rollers, located downstream of the nozzles, continuously clamp and convey the film downwards while compressing the contents. The two pairs of feeding rollers completely compress the film, with each pair compressing approximately 16mm. 2 The area is then determined. Next, the two ends of the tubular PVDC film along its long dimension are secured with clips and cut to a specified length, thereby producing a filler package with a circumference of 72 mm and a length of 215 mm. It should be noted that when forming the base film into a tubular shape, the conditions are adjusted so that the fold width (half the circumference) is 36 mm, the cutting length (the length measured when the contents are removed from the filler package and the tubular PVDC film is flattened along its long dimension) is 215 mm, and the mass is 64 g.

[0137] The resulting filled packaging was subjected to a temperature of 120℃ and a pressure of 2.0 kg / cm². 2 After being placed in a (gauge pressure) cooking vessel for 10 minutes for cooking and sterilization, the samples were taken out to prepare evaluation samples.

[0138] [Example 2]

[0139] Except that the amount of ethylene homopolymer LDPE1 added was set to 2.0 parts by weight, the vinylidene chloride resin stretch film and the filled packaging were obtained in the same manner as in Example 1.

[0140] [Example 3]

[0141] Except for obtaining a vinylidene chloride-based resin composition by melt extrusion molding using an extrusion screw with a diameter of 90 mm, a vinylidene chloride-based resin stretch film and a filled package were obtained in the same manner as in Example 1.

[0142] [Example 4]

[0143] In addition to using a density of 928 kg / m³ 3 Except for LDPE4, an ethylene homopolymer with a melt flow rate of 0.7 g / 10 min and a melting peak temperature of 115 °C, which was used instead of LDPE1, vinylidene chloride-based resin stretch films and filled packaging bodies were obtained in the same manner as in Example 1.

[0144] [Comparative Example 1]

[0145] Except for the absence of ethylene homopolymer LDPE1, the same polyvinylidene chloride resin stretch film and filled packaging were obtained as in Example 1.

[0146] [Comparative Example 2]

[0147] In addition to using a density of 940kg / m³ 3 Except for ethylene-vinyl acetate copolymer EVA with a vinyl acetate content of 17% by mass, a melt flow rate of 0.8 g / 10 min, and a melting peak temperature of 89 °C, which replaces ethylene homopolymer LDPE1, vinylidene chloride-based resin stretch films and filled packaging bodies were obtained in the same manner as in Example 1.

[0148] [Comparative Example 3]

[0149] In addition to using a density of 885 kg / m³ 3 Except for replacing the ethylene homopolymer LDPE1 with ultra-low density linear polyethylene VLDPE with a melt flow rate of 3.6 g / 10 min and a melt peak temperature of 66 °C, vinylidene chloride-based resin stretch films and filled packaging bodies were obtained in the same manner as in Example 1.

[0150] [Comparative Example 4]

[0151] In addition to using a density of 950 kg / m³ 3 Except for replacing the ethylene homopolymer LDPE1 with a sodium ion neutralized ionomer of an ethylene-methacrylic acid copolymer with a melt flow rate of 0.9 g / 10 min and a melt peak temperature of 92 °C, vinylidene chloride-based resin stretch films and filled packaging bodies were obtained in the same manner as in Example 1.

[0152] [Comparative Example 5]

[0153] Except that the amount of ethylene homopolymer LDPE1 added was set to 1.5 parts by weight, the vinylidene chloride resin stretch film and the filled packaging were obtained in the same manner as in Example 1.

[0154] [Comparative Example 6]

[0155] Except that the amount of ethylene homopolymer LDPE1 added was set to 3.5 parts by weight, the vinylidene chloride resin stretch film and the filled packaging were obtained in the same manner as in Example 1.

[0156] [Comparative Example 7]

[0157] In addition to using a density of 916 kg / m³ 3 Except for LDPE2, an ethylene homopolymer with a melt flow rate of 17 g / 10 min and a melting peak temperature of 107 °C, which was used instead of LDPE1, vinylidene chloride-based resin stretch films and filled packaging bodies were obtained in the same manner as in Example 1.

[0158] [Comparative Example 8]

[0159] In addition to using a density of 915 kg / m³ 3 Except for LDPE3, an ethylene homopolymer with a melt flow rate of 25 g / 10 min and a melt peak temperature of 106 °C, which was used instead of LDPE1, vinylidene chloride-based resin stretch films and filled packaging bodies were obtained in the same manner as in Example 1.

[0160] [Comparative Example 9]

[0161] In addition to using a density of 915 kg / m³ 3 In addition to obtaining a vinylidene chloride-based resin composition, a vinylidene chloride-based resin stretch film and a filler packaging body were obtained in the same manner as in Example 1, except that a vinylidene chloride-based resin composition was obtained by using an extruder with a diameter of 90 mm for melt extrusion in the stretch film manufacturing.

[0162] [Table 1]

[0163]

[0164] As shown in Table 1, for the filled packaging of the embodiments where the T-shaped peel strength of the longitudinal seal and the proportion of dispersed phases with a length and width of 2 μm or more in the total number of dispersed phases of ethylene resin are within a specific range, the sensory evaluation of opening performance and normal opening rate are both good, and the easy-to-open performance can be consistently demonstrated.

[0165] Explanation of reference numerals in the attached figures

[0166] S: Filler packaging;

[0167] 1: Cylindrical polyvinylidene chloride resin stretched film;

[0168] 21: Longitudinal sealing section;

[0169] 22: External ear;

[0170] 3A, 3B: Both ends;

[0171] 41: Two membranes arranged radially on the outer side;

[0172] 41A: Surface portion (the outermost membrane in the radial direction);

[0173] 42: Two membranes arranged radially inside;

[0174] 51: Vinylidene chloride-based resins;

[0175] 52: Ethylene-based resins;

[0176] 9: Contents;

[0177] l: Length and width of the dispersed phase of the ethylene-based resin;

[0178] w: Short width of the dispersed phase in ethylene-based resins.

Claims

1. A filler package, said filler package being formed by filling and sealing contents into a cylindrical vinylidene chloride-based resin stretch film having a longitudinal sealing portion extending along its length direction and being constricted at both ends along its length direction. The vinylidene chloride-based resin stretched film is formed from a resin composition containing vinylidene chloride-based resin and ethylene-based resin. In the ethylene-based resin, the proportion of constituent units derived from ethylene is 50% by mass or more relative to all constituent units constituting the ethylene-based resin. The T-shaped peel strength of the longitudinal sealing part is 7-13 N / 15 mm. In the vinylidene chloride-based resin stretched film, the proportion of dispersed phases with a length and width of 2 μm or more in the total number of dispersed phases of the vinylidene resin is 20% to 50%.

2. The filled packaging body according to claim 1, wherein, The filling package has undergone a steaming or boiling process.

3. A vinylidene chloride-based resin stretch film, said vinylidene chloride-based resin stretch film being formed from a resin composition containing vinylidene chloride-based resin and ethylene-based resin, In the ethylene-based resin, the proportion of constituent units derived from ethylene is 50% by mass or more relative to all constituent units constituting the ethylene-based resin. The amount of the ethylene-based resin is 2.0 to 3.0 parts by weight relative to 100 parts by weight of the vinylidene chloride-based resin. The melt flow rate of the ethylene-based resin is 0.1–10 g / 10 min. The melting peak temperature of the ethylene-based resin is 100–130°C.

4. The vinylidene chloride-based resin stretch film according to claim 3, wherein, The ethylene-based resin is an ethylene homopolymer.

Images