Packaging method, packaging device, heat-sealable inkjet ink, and packaging material

Abstract

Provided is a packaging method or the like with which it is possible to partially adjust the adhesive strength of adhesive parts in a packaging material.　The packaging method involves packaging an object to be packaged by using a packaging material that has heat-seal regions on a base material. The packaging method comprises: a heat-seal-region-forming step for forming the heat-seal regions on the base material; and a bonding step for heating and bonding the formed heat-seal regions. The heat-seal-region-forming step includes: an ink-ejecting step for ejecting a heat-sealable inkjet ink onto the base material; and an ink-drying step for drying the base material onto which the heat-sealable inkjet ink has been ejected.

Description

Packaging method, packaging apparatus, heat-sealable inkjet ink, and packaging material

[0001] This disclosure relates to a packaging method, a packaging apparatus, a heat-sealable inkjet ink, and a packaging material.

[0002] As a method for bonding packaging materials, heat sealing (heat welding) is known, and the heat-sealed area is partially provided only at the bonding points of the packaging material (Patent Documents 1-3).

[0003] JP 7-246674 JP 2003-053902 JP 6-312751

[0004] In packaging materials, the required adhesive strength differs depending on the bonding point. For example, in a bag-shaped packaging material formed by bonding the edges, the bag is opened from a specific bonded point to remove the packaged items inside. In this case, it is necessary to make it somewhat easy to open, so the adhesive strength at the opening point should not be too high. On the other hand, it is desirable for the bonded points other than the opening point to have high adhesive strength.

[0005] However, Patent Documents 1 to 3 do not address the issue of varying the adhesive strength depending on the bonding location. For example, if the adhesive strength of the entire bonding area is adjusted to match the adhesive strength of the opening area, the adhesive strength of areas other than the opening area will be lower. Also, if the adhesive strength of the entire bonding area is adjusted to match the adhesive strength of areas other than the opening area, there is a problem in that the opening area becomes difficult to open.

[0006] The problem addressed by this disclosure is to provide a packaging method, etc., that allows for partial adjustment of the adhesive strength of the bonded areas in the packaging material.

[0007] The Disclosing Party investigated the causes of the above-mentioned problems in order to solve them. They discovered that by using an inkjet method in the formation of the heat-sealed area, the adhesive strength of the bonded areas in the packaging material can be partially adjusted, leading to this disclosure. In other words, the above-mentioned problems related to this disclosure are solved by the following means.

[0008] 1. A packaging method for packaging an object to be packaged using a packaging material having a heat-seal region on a base material, comprising: a heat-seal region formation step of forming the heat-seal region on the base material; and an adhesion step of heating and bonding the formed heat-seal region, wherein the heat-seal region formation step comprises: an ink ejection step of ejecting heat-sealable inkjet ink onto the base material; and an ink drying step of drying the base material from which the heat-sealable inkjet ink has been ejected.

[0009] 2. The packaging method according to paragraph 1, wherein the amount of heat-sealable inkjet ink ejected in the ink ejection step is changed according to the packaging form.

[0010] 3. The packaging method according to paragraph 1 or 2, wherein in the ink ejection step, the ejection area of ​​the heat-sealable inkjet ink on the substrate is changed according to the packaging form.

[0011] 4. The packaging method according to paragraph 1 or 2, wherein the amount of heat-sealable inkjet ink ejected in the ink ejection step is changed to form heat-seal regions on the same substrate with different amounts of ink per unit area, and the difference in peel strength in the formed heat-seal regions with different amounts of ink per unit area is in the range of 0.1 to 10 N / 15 mm.

[0012] 5. The packaging method according to paragraph 1 or 2, wherein the bonding step comprises a center sealing step of bonding the packaging material along the longitudinal direction and an end sealing step of bonding the packaging material along the width direction.

[0013] 6. The packaging method according to paragraph 1 or 2, wherein the bonding step comprises a top-sealing step of bonding the packaging material to the opening of the container to seal the container.

[0014] 7. The packaging method according to paragraph 1 or 2, wherein, when the substrate is absorbent, the static surface tension of the heat-sealable inkjet ink at 25°C is in the range of 30 to 55 mN / m.

[0015] 8. The packaging method according to paragraph 1 or 2, wherein, when the substrate is non-absorbent, the static surface tension of the heat-sealable inkjet ink at 25°C is in the range of 20 to 40 mN / m.

[0016] 9. The packaging method according to paragraph 1 or 2, comprising, between the heat-seal region formation step and the bonding step, a packaging material transport step for transporting the packaging material on which the heat-seal region has been formed, and a packaged object supply step for supplying the packaged object to the vicinity of the packaging material so that the packaged object is covered by the packaging material.

[0017] 10. A packaging apparatus for packaging an object to be packaged using a packaging material having a heat-seal region on a base material, comprising: a heat-seal region forming unit for forming a heat-seal region on the base material; and an adhesive unit for heating and bonding the formed heat-seal region, wherein the heat-seal region forming unit comprises: an ink dispensing unit for dispensing heat-sealable inkjet ink onto the base material; and an ink drying unit for drying the base material on which the heat-sealable inkjet ink has been dispensed.

[0018] 11. A heat-sealable inkjet ink comprising resin particles and a solvent, wherein the resin particles contain a resin having a melting point in the range of 50 to 200°C, the average particle size of the resin particles is in the range of 30 to 300 nm, the solvent comprises an organic solvent having a boiling point in the range of 120 to 250°C and water, and the viscosity at 25°C is in the range of 1 to 80 mPa·s.

[0019] 12. The heat-sealable inkjet ink according to paragraph 11, wherein the dispersion form of the resin particles is self-emulsifying.

[0020] 13. The heat-sealable inkjet ink according to item 11, wherein the resin particles contain polyolefin.

[0021] 14. A packaging material having heat-sealed regions on a substrate with different amounts of adhesive per unit area, wherein the difference in peel strength between the heat-sealed regions with different amounts of adhesive per unit area is within the range of 0.1 to 10 N / 15 mm.

[0022] According to this disclosure, the adhesive strength of the bonded areas in the packaging material can be partially adjusted.

[0023] This is a schematic diagram showing an example of the configuration in a packaging device. This is a schematic diagram showing an example of a packaging material. This is a schematic cross-sectional diagram along line III-III in Figure 2. This is a schematic diagram showing an example of a package. This is a schematic cross-sectional diagram of the quadruple seal region. This is a schematic diagram showing an example of a package in top-seal packaging. This is a schematic diagram showing an example of a lid. This is a flowchart explaining the packaging method. This is a flowchart explaining the heat seal region formation process. This is a diagram explaining the adhesive strength in the heat seal region. This is a diagram explaining the heat seal region in Example [1]. This is a diagram explaining the three-side seal packaging in Example [1]. This is a diagram explaining the heat seal region in Example [3]. This is a diagram explaining the heat seal region in Example [4].

[0024] The packaging method of this disclosure is a packaging method for packaging an object to be packaged using a packaging material having a heat-seal region on a substrate. The packaging method of this disclosure comprises a heat-seal region formation step of forming a heat-seal region on a substrate, and an adhesion step of heating and bonding the formed heat-seal region. The heat-seal region formation step comprises an ink ejection step of ejecting heat-sealable inkjet ink onto a substrate, and an ink drying step of drying the substrate on which the heat-sealable inkjet ink has been ejected. The above is the characteristic feature. This feature is a technical feature common to or corresponding to the following embodiments.

[0025] In this embodiment, it is preferable to vary the amount of heat-sealable inkjet ink dispensed during the ink ejection process according to the packaging form. This allows for partial adjustment of the adhesive strength.

[0026] In this embodiment, it is preferable to change the ejection area of ​​the heat-sealable inkjet ink on the substrate according to the packaging form during the ink ejection process. This allows the heat-seal area to be formed only at the bonding location, and the bonding strength to be partially adjusted.

[0027] In this embodiment, by changing the discharge amount of the heat-sealable inkjet ink in the ink discharge process, heat-sealing regions with different amounts per unit area are formed on the same substrate. In the formed heat-sealing regions with different amounts per unit area, it is preferable that the difference in peel strength is within the range of 0.1 to 10 N / 15 mm. Thereby, airtightness, easy-opening property, etc. can be improved.

[0028] In this embodiment, the adhesion step may include a center seal step of adhering the packaging material along the longitudinal direction and an end seal step of adhering the packaging material along the width direction. Thereby, this embodiment can be applied to pillow packaging.

[0029] In this embodiment, the adhesion step may include a top seal step of adhering the packaging material to the opening of the container to seal the container. Thereby, this embodiment can be applied to top seal packaging.

[0030] In this embodiment, when the substrate has absorbency, the static surface tension of the heat-sealable inkjet ink at 25°C is preferably within the range of 30 to 55 mN / m. Thereby, the adhesion strength when the substrate has absorbency can be improved.

[0031] In this embodiment, when the substrate has non-absorbency, the static surface tension of the heat-sealable inkjet ink at 25°C is preferably within the range of 20 to 40 mN / m. Thereby, the adhesion strength when the substrate has non-absorbency can be improved.

[0032] In this embodiment, it is preferable to have a packaging material conveyance step of conveying the packaging material in which the heat-sealing region is formed and a packaged article supply step of supplying the packaged article near the packaging material so that the packaged article is covered with the packaging material, between the heat-sealing region forming step and the adhesion step. Thereby, the packaged article can be packaged using the packaging material.

[0033] The packaging device of the present embodiment is a packaging device that packages an object to be packaged using a packaging material having a heat-sealing region on a base material. The packaging device of the present embodiment includes a heat-sealing region forming unit that forms a heat-sealing region on the base material, and an adhesion unit that heats and adheres the formed heat-sealing region. The heat-sealing region forming unit includes an ink ejection unit that ejects a heat-sealing inkjet ink onto the base material, and an ink drying unit that dries the base material onto which the heat-sealing inkjet ink has been ejected.

[0034] The heat-sealing inkjet ink of the present embodiment is a heat-sealing inkjet ink containing resin particles and a solvent. The resin particles contain a resin having a melting point within the range of 50 to 200°C. The average particle diameter of the resin particles is within the range of 30 to 300 nm. The solvent includes an organic solvent having a boiling point within the range of 120 to 250°C and water. The viscosity of the heat-sealing inkjet ink of the present embodiment at 25°C is within the range of 1 to 80 mPa·s.

[0035] As the present embodiment, the dispersion form of the resin particles is preferably a self-emulsifying type. Thereby, the ejection property of the heat-sealing inkjet ink can be improved.

[0036] As the present embodiment, the resin particles preferably contain a polyolefin. Thereby, the adhesion strength can be improved.

[0037] The packaging material of the present embodiment has heat-sealing regions with different amounts per unit area on the base material. In the heat-sealing regions with different amounts per unit area, the difference in peel strength is within the range of 0.1 to 10 N / 15 mm. Thereby, the airtightness, easy-openability, etc. can be improved.

[0038] Hereinafter, one or more embodiments of the present disclosure will be described with reference to the drawings. However, the scope of the present disclosure is not limited to the disclosed embodiments.

[0039] 1. Packaging device Figure 1 is a schematic diagram showing an example of the configuration of the packaging device 1 of this embodiment. In the packaging device 1, as the items to be packaged 6 are supplied sequentially, a long roll 2 is unwound to supply the base material 3. A heat-seal area 4 is formed on the supplied base material 3, and the packaging material 5 is formed. The packaging material 5 is bonded together to form a cylindrical bag, and the items to be packaged 6 are placed inside. Thereafter, bonding and cutting are performed in the width direction of the packaging material 5 at predetermined intervals to obtain a package 7.

[0040] The packaging device 1 shown in Figure 1 is an example of a horizontal bag-making and filling machine (horizontal pillow packaging machine), but this embodiment is not limited to this. Examples of packaging devices 1 include vertical pillow packaging machines, three-side seal packaging machines, four-side seal packaging machines, stick packaging machines, top seal packaging machines, etc. Furthermore, the packaging device 1 shown in Figure 1 is a standard pillow packaging machine that wraps the item to be packaged 6 with packaging material 5 from above, but it may also be an inverted pillow packaging machine that wraps from below.

[0041] The packaging device 1 comprises a base material transport section, a heat seal area forming section, a packaging material transport section, a packaged object supply section, an adhesive section, and an unloading section. In the packaging device 1, the side closer to the long roll 2 is the upstream side, and the side further away is the downstream side. In the packaging device 1, the long roll 2 winds the base material 3 in the longitudinal direction, and the base material 3 and packaging material 5 unloaded from the long roll 2 are transported in the longitudinal direction. In the base material 3 and packaging material 5, the direction perpendicular to the longitudinal direction is the width direction.

[0042] The substrate transport unit includes a first transport roller 11 and a motor (not shown) that drives it. The first transport roller 11 rotates around the width direction of the substrate 3 as its central axis. As a result, the substrate 3 is sequentially fed out from the long roll 2 and transported downstream.

[0043] The heat seal area forming section includes an ink ejection section 20 and an ink drying section 30. Specifically, the ink ejection section 20 is an inkjet head.

[0044] The inkjet head ejects ink onto the transported substrate 3. In this specification, "heat-sealable inkjet ink" is also simply referred to as "ink." Details of the ink will be described later. The inkjet head has nozzles for ejecting ink. The nozzles have ejection ports on their nozzle surfaces, and the nozzle surfaces are positioned to face the substrate 3. The nozzles eject ink from their ejection ports onto the substrate 3 transported by the substrate transport unit.

[0045] The ink ejection method from the inkjet head may be either on-demand or continuous. Examples of on-demand inkjet heads include single-cavity, double-cavity, bender, and piston types. Examples of on-demand inkjet heads include electromechanical conversion methods such as shear-mode and shared-wall types. Examples of electromechanical conversion methods such as thermal inkjet and bubble jet (registered trademark) types. In addition, the inkjet head may be either a scanning or line type.

[0046] The inkjet head may be equipped with a device to regulate the ink temperature. By regulating the ink temperature, the viscosity of the ink can be lowered, and the ink ejection performance can be improved.

[0047] The ink drying unit 30 heats and dries the area on the substrate 3 where the ink has been ejected, forming a heat-sealed area 4. Examples of the ink drying unit 30 include a device that generates temperature-controllable air or hot air, a hot plate, a device that irradiates visible light or far-infrared light, a heat roller, a device that irradiates microwaves, etc. When such a drying device is provided, it is preferable to provide an exhaust pipe or fan to remove the steam generated by drying from inside the device.

[0048] The packaging material conveying unit includes a second conveying roller 41, a motor (not shown) that drives it, and the like. The second conveying roller 41 rotates with the width direction of the packaging material 5 as its central axis, conveying the formed packaging material 5 to near the packaged object 6 supplied by the packaged object supply unit.

[0049] The packaged material supply unit is located upstream of the adhesive unit and supplies the packaged material 6 to the adhesive unit at predetermined intervals. The packaged material supply unit includes a third conveyor roller 51, a fourth conveyor roller 53, a motor (not shown) that drives them, a first conveyor belt 52, etc. The third conveyor roller 51 rotates with the width direction of the packaging material 5 as its central axis, and the first conveyor belt 52 moves in a circular motion around the third conveyor roller 51. As the first conveyor belt 52 moves in a circular motion with the packaged material 6 placed on its conveying surface, the packaged material 6 is conveyed in the direction of movement of the first conveyor belt 52, i.e., downstream. The fourth conveyor roller 53 is located downstream of the first conveyor belt 52. On the fourth conveyor roller 53, the packaged material 6 is covered with the packaging material 5.

[0050] The adhesive portion is formed by overlapping and bonding heat-sealed areas on the packaging material 5. The adhesive portion includes a bag-making machine 61, a center seal portion 62, and an end seal portion 65.

[0051] The bag maker 61 passes the packaging material 5, which has been conveyed by the second conveyor roller 41, through it, overlapping the edges on both sides in the width direction of the packaging material 5 to form a cylindrical bag. The bag maker 61 is open at the bottom in Figure 1, with the edges on both sides in the width direction of the packaging material 5 located at the bottom. Heat seal areas 4 are formed on the overlapping edges on both sides.

[0052] The items to be packaged 6, supplied from the packaged item supply unit, are inserted into the bag maker 61 and then housed in the cylindrical packaging material 5. The items to be packaged 6 supplied into the bag maker 61 are positioned at predetermined intervals within the cylindrical packaging material 5. A belt conveyor (not shown) transports the cylindrical packaging material 5 containing the items to be packaged 6.

[0053] The center seal section 62 heat-seals the overlapping edges of the cylindrical packaging material 5 in the width direction by heating them while sandwiching them from both outer sides. The heat sealing of the edges in the width direction is also called the "center seal". In the center seal section 62, the edges of the packaging material 5 in the width direction are bonded together along the longitudinal direction.

[0054] The center seal section 62 includes a pair of left and right pinch rollers 63, a bar-shaped sealer (not shown), and a pair of left and right pressure rollers 64. The pinch rollers 63 grip the two side edges of the cylindrical packaging material 5 in the width direction with a predetermined pressure and rotate synchronously to transport the cylindrical packaging material 5. The sealer heats and welds the two side edges in the width direction. The pressure rollers 64 grip and press the two side edges in the width direction with a predetermined pressure to fix the adhesion between the two side edges in the width direction. This creates a center seal. The pressure rollers 64 also function as pinch rollers 63 and transport the center-sealed cylindrical packaging material 5.

[0055] The end seal section 65 adheres to the center-sealed cylindrical packaging material 5 in the width direction and then cuts it. Heat sealing in the width direction relative to the center seal is also called an "end seal". The end seal section 65 may be rotary or box-motion type. A pair of top sealers, positioned vertically, clamp the cylindrical packaging material 5 according to the length of the item to be packaged 6, heat and pressurize it, and adhere it in the width direction. After that, the end-sealed packaging material 5 is cut according to the length of the item to be packaged 6. This results in a package 7 in which the item to be packaged 6 is wrapped in the packaging material 5.

[0056] The discharge unit discharges the obtained packaged body 7 to the downstream side of the packaging device 1. The discharge unit includes a fifth conveyor roller 71, a motor (not shown) that drives it, a second conveyor belt 72, etc. The fifth conveyor roller 71 rotates with the width direction of the packaging material 5 as its central axis, and the second conveyor belt 72 moves in a circular motion around the fifth conveyor roller 71. As the second conveyor belt 72 moves in a circular motion with the packaged body 7 placed on its conveying surface, the packaged body 7 is conveyed in the direction of movement of the second conveyor belt 72, i.e., to the downstream side.

[0057] The above describes an example of the horizontal bag-making and filling machine (horizontal pillow packaging machine) of this embodiment using Figure 1. However, as mentioned above, it can also be applied to three-side seal packaging machines, top seal packaging machines, etc., and the configuration of the adhesive part will differ according to the various packaging forms. In addition, parts other than the adhesive part may also be modified as appropriate according to the packaging form.

[0058] 2. Figure 2 is a schematic diagram showing an example of packaging material 5. Figure 2 shows a schematic diagram of packaging material 5 viewed from above, with the width direction being the X-axis direction and the length direction being the Y-axis direction.

[0059] The shape of the heat-seal area 4 on the base material 3 is not particularly limited. In the packaging material 5 corresponding to the packaging device 1, the heat-seal area 4 is formed, for example, in the shape of a square frame. The size of the heat-seal area 4 is adjusted according to the size of the packaged item. The width W of the heat-seal area 4 is adjusted according to the desired adhesive strength. The heat-seal area 4 has two first edges 4A and two second edges 4B. The first edges 4A are the side edges in the width direction and are provided in a strip shape along the longitudinal direction (Y-axis direction). The second edges 4B correspond to the side edges in the longitudinal direction after they have been bonded and cut, and are provided in a strip shape along the width direction (X-axis direction).

[0060] Figure 3 is a schematic cross-sectional view along the line III-III in Figure 2, with the width direction being the X-axis and the thickness (height) direction being the Z-axis. The thickness D of the heat-sealed region 4 is adjusted according to the desired adhesive strength.

[0061] The base material 3 in the packaging material 5 is not particularly limited and includes resin film, metal film, paper, cloth, etc. The base material 3 may also be a laminate formed by laminating these materials.

[0062] The base material 3 may be absorbent or non-absorbent. Specifically, the base material 3 is considered "absorbent" if, in the Bristow method, it absorbs 30 msec from the start of contact. １／２ The water absorption capacity up to 10 mL / m³ is 10 mL / m³. ２ This refers to being extremely absorbent. The Bristow method is the most widely used method for measuring liquid absorption in a short time and is also adopted by the Japan Paper & Pulp Technology Association (JAPAN TAPPI). Details of the test method are described in standard No. 51 "Paper and cardboard - Liquid absorbency test method - Bristow method" of the "JAPAN TAPPI Paper & Pulp Test Methods 2000 Edition". In contrast, "non-absorbent" means not having "absorbency", that is, from the start of contact for 30 msec. １／２ The water absorption capacity up to 10 mL / m³ is 10 mL / m³. ２This refers to the following:

[0063] Examples of absorbent base materials 3 include paper and cloth.

[0064] Among the non-absorbent substrates 3, a substrate with relatively high absorbency is one in which a receptive layer for water-based ink is provided on the surface of a non-absorbent resin film. Specifically, this includes a resin film surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc., coated with a hydrophilic polymer. The hydrophilic polymer may be coated together with particles such as silica and titanium. In addition, a substrate with relatively high absorbency is one in which the surface of absorbent paper is coated with resin. Specifically, this includes art paper, coated paper, matte paper, etc.

[0065] Among the non-absorbent substrates 3, examples of substrates with relatively low absorbency include the resin film and metal film mentioned above.

[0066] From the perspective that the heat-seal region 4 is applied to the substrate 3 in the form of ink, it is preferable to adjust the surface tension of the ink according to the absorption performance of the substrate 3. This makes it possible to form a heat-seal region 4 with sufficient adhesive strength regardless of the absorption performance of the substrate 3. Further details will be described later.

[0067] The heat-sealed regions 4 on the base material 3 may have their adhesive strength partially adjusted depending on the packaging form, application, etc. Specifically, this can be adjusted by varying the amount of adhesive applied per unit area. Packaging materials 5 used in pillow packaging and the like preferably have heat-sealed regions 4 on the base material 3 with different amounts of adhesive applied per unit area. In the heat-sealed regions 4 with different amounts of adhesive applied per unit area, it is preferable that the difference in peel strength is within the range of 0.1 to 10 N / 15 mm. Further details will be explained in the discharge conditions described later.

[0068] 3. Figure 4 is a schematic diagram showing an example of a package 7. The packaging device 1 described above adheres and cuts the packaging material 5 to obtain a package 7 containing the packaged item 6. Note that the packaged item 6 is not shown in Figure 4.

[0069] The center seal region 7A is obtained by overlapping the two first edge portions 4A and heat sealing them, that is, it is a region formed by the center seal portion 62 in the packaging device 1.

[0070] The end seal region 7B is obtained by overlapping and heat-sealing the two second edge portions 4B, that is, it is a region formed by the end seal portion 65 in the packaging device 1. The end seal region 7B may also function as an opening portion when opening the package 7 to remove the packaged item 6. In this case, it is preferable that the end seal region 7B has sufficient adhesive strength while being moderately easy to open, that is, easy to open.

[0071] In Figure 4, the center seal region 7A is folded down in the positive direction of the X-axis after being center-sealed. The quadruple seal region 7C is the region that is end-sealed after being center-sealed, and is the region where the packaging material 5 overlaps four times.

[0072] Figure 5 is a schematic cross-sectional view of the quadruple seal region 7C. In the quadruple seal region 7C, holes 7D are likely to occur because the packaging material 5 is bonded four times. When holes 7D occur, the inside of the package 7 cannot be completely sealed, and the airtightness tends to decrease. In this embodiment, the adhesive strength can be partially improved only in the quadruple seal region 7C, making it less likely for holes 7D to occur. As a result, the airtightness of the package 7 can be improved.

[0073] Figure 6 is a schematic diagram showing an example of a packaging body 8 in top-seal packaging. In packaging body 8, a container 82 having an opening is sealed with a lid 81. Examples of items packaged using top-seal packaging include instant foods such as instant noodles, and some instant foods are cooked using packaging body 8. In this case, first, only the front part of the lid 81 is opened, then hot water or the like is poured into the container 82, and the front part of the lid 81 is placed back on top to cover the opening of the container 82. Therefore, it is preferable that the lid 81 is relatively easy to open at the front and relatively difficult to open at the rear.

[0074] Figure 7 is a schematic diagram showing an example of a lid 81. In Figure 7, the back surface of the lid 81, i.e., the surface facing the opening of the container 82, is shown. It is preferable to increase the adhesive strength of the rear portion 81B compared to the front portion 81A. The adhesive strength can be adjusted using the same method as for pillow packaging, which will be described in detail later.

[0075] In forming the packaging 7, heat-seal areas may be formed on both of the two parts to be bonded, or on only one of them. In the example of pillow packaging described above, heat-seal areas are formed on both of the two parts to be bonded, while in the example of top-seal packaging, a heat-seal area is formed on only one of the two parts to be bonded (the lid). Furthermore, the packaging does not necessarily have to completely seal the inside containing the packaged items.

[0076] 4. Packaging Method Figure 8 is a flowchart illustrating the packaging method of this embodiment. In the packaging method of this embodiment, a packaging material 5 having a heat-seal area 4 on a base material 3 is used. In the packaging method of this embodiment, first, a heat-seal area 4 is formed on the base material 3 (S1: heat-seal area formation step), and then the formed heat-seal area 4 is heated and bonded (S4: bonding step). This gives rise to a package 7.

[0077] The process may include a packaging material transport step S2 between the heat seal region formation step S1 and the bonding step S4 for transporting the packaging material 5 on which the heat seal region 4 has been formed. Alternatively, the process may include a packaging material supply step S3 between the heat seal region formation step S1 and the bonding step S4 for supplying the packaged object 6 to the vicinity of the packaging material 5 so that the packaged object 6 is covered by the packaging material 5.

[0078] The packaging material transport process S2 is performed by the packaging material transport unit, and its details are as described above. The packaged material supply process S3 is performed by the packaged material supply unit, and its details are as described above. The bonding process S4 is performed by the bonding unit, and its details are as described above. In the case of pillow packaging, the bonding process S4 includes a center seal process in which the packaging material 5 is bonded along the longitudinal direction, and an end seal process in which the packaging material 5 is bonded along the width direction. In the case of top seal packaging, the bonding process S4 further includes a top seal process in which the packaging material 5 is bonded to the opening of the container to seal the container.

[0079] The details of the heat seal region formation process S1 are described below.

[0080] Figure 9 is a flowchart illustrating the heat seal region formation process S1. In the heat seal region formation process S1, first, ink is ejected onto the substrate 3 (ink ejection process S11), and then the substrate 3 from which the ink has been ejected is dried (ink drying process S12).

[0081] The following describes each step.

[0082] (1) Heat seal area formation process (1.1) Ink ejection process In the ink ejection process S11, heat sealable inkjet ink is ejected onto the substrate 3 using an inkjet method (inkjet head).

[0083] In the inkjet method, the thickness D of the formed heat-sealed area 4 can be adjusted by changing the ejection amount according to the packaging form, thereby adjusting the adhesive strength. In the inkjet method, by changing the ejection area according to the packaging form, the heat-sealed area can be formed only on a part of the substrate 3. Also, by changing the ejection area according to the packaging form, the width W of the heat-sealed area 4 can be adjusted, thereby adjusting the adhesive strength. In the inkjet method, the amount of ink ejected per unit area can be adjusted by adjusting the ejection pattern, thereby adjusting the adhesive strength. In short, by using the inkjet method, the adhesive strength of the heat-sealed area 4 can be adjusted.

[0084] The inkjet method allows for on-demand printing, meaning that only the necessary amount (quantity) can be printed when and where needed. Therefore, by using the inkjet method, packaging material 5 can be manufactured only when and in the necessary quantity, eliminating the need for excessive preparation of packaging material. Furthermore, because the formation conditions of the heat seal area can be freely adjusted, it can accommodate changes in the size, shape, etc., of the packaged object 6.

[0085] The inkjet heads and drying equipment required for inkjet printing are relatively small. Therefore, in conventional packaging equipment, instead of the packaging material with a heat-sealed area, a long roll of substrate material may be installed, and the inkjet heads and drying equipment may be mounted along the path through which the substrate material is transported.

[0086] Conventional technologies, such as co-embossed films and laminate films with heat-sealing capabilities, sometimes applied heat-sealing functionality to areas where it wasn't necessary. However, with the inkjet method, heat-sealing functionality can be applied only to the areas where it's needed, thus eliminating material waste. Furthermore, while lamination of multiple materials makes sorting difficult and prevents recycling, the heat-sealed area is minimized, resulting in fewer areas where multiple materials are laminated, thus improving recycling efficiency.

[0087] Furthermore, while the texture of the original substrate is easily lost in areas where a heat-sealed region is formed, even without adhesion, the heat-sealed region is formed to a minimum extent, so the texture of the original substrate is easily retained in areas that are not adhered. For example, when using a highly transparent substrate, the transparency of the substrate is maintained in areas that are not adhered, resulting in a highly transparent packaging 7.

[0088] (1.1.1) Heat-sealable inkjet ink In this embodiment, "heat-sealable inkjet ink" refers to an inkjet ink used to form a heat-seal area. "Heat-sealable" refers to the property of a resin to melt when heated, and then solidify when the heating is stopped and it cools, resulting in adhesion. The ink is not particularly limited as long as it has heat-sealable properties, but it is preferably one of the inks shown below.

[0089] The ink preferably contains resin particles and a solvent. The resin particles preferably contain a resin having a melting point in the range of 50 to 200°C. The average particle size of the resin particles is preferably in the range of 30 to 300 nm. The solvent preferably contains an organic solvent having a boiling point in the range of 120 to 250°C and water. The viscosity at 25°C is preferably in the range of 1 to 80 mPa·s.

[0090] <Resin Particles> The resin, having a melting point in the range of 50 to 200°C, is not particularly limited, but examples include polyolefins, acrylic resins, polyesters, and polyurethanes. These may be used individually or in combination of two or more. Among these, polyolefins are preferred from the viewpoint of obtaining high adhesive strength in the heat-seal region of polypropylene (PP) substrates, which are commonly used in general packaging. The adhesive strength in the heat-seal region differs depending on the combination of the type of resin contained in the resin particles and the type of substrate, so it is preferable to select the type of resin according to the type of substrate. Furthermore, when used as food packaging material, it is preferable to select a resin that complies with the Food Sanitation Law.

[0091] Examples of polyolefins include polyethylene, polypropylene, and ethylene-propylene copolymers. Copolymers of these with other comonomers may also be used. The copolymers may be random copolymers or block copolymers. These may be used individually or in combination of two or more.

[0092] Other comonomers include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 1-nonene, which have two or more carbon atoms, and α-olefin comonomers with two to six carbon atoms. These may be used individually or in combination of two or more.

[0093] Commercially available polyolefins may be used. Examples of commercially available polyolefins include "Arrowbase® SB-1030N", "Arrowbase® SE-1030N", "Arrowbase® DA-1010", "Arrowbase® YA-6005N", and "Arrowbase® SB-1200" (all manufactured by Unitika Ltd.), "Chemipearl® ET300H" (manufactured by Mitsui Chemicals, Inc.), "Aurolene® 150A" and "Aurolene® AE-301" (both manufactured by Nippon Paper Industries Ltd.), "Superclon® E-415" (manufactured by Nippon Paper Industries Ltd.), and "Hardlen® Na-100" (manufactured by Toyobo Co., Ltd.).

[0094] Since self-emulsifying resin particles can be dispersed in solvents (water-soluble solvents and water) without the use of dispersants, the ink does not need to contain a dispersant, thus suppressing the decrease in heat sealability that can occur due to the inclusion of dispersants.

[0095] The average particle size of the resin particles is not particularly limited, as long as it is within the range of 30 to 300 nm.

[0096] The average particle size of resin particles can be measured using commercially available particle size measuring instruments that employ methods such as dynamic light scattering and electrophoresis. In particular, dynamic light scattering is a convenient method that can accurately measure the particle size range. Specifically, the average particle size can be measured using the D50 (median diameter) of the scattering intensity distribution, for example, with "nanoSAQLA" (manufactured by Otsuka Electronics Co., Ltd.).

[0097] The resin particles may include resin particles containing resins other than polyolefin. For example, the ink may contain acrylic resin particles in addition to polyolefin particles.

[0098] Acrylic resin may be a commercially available product. Examples of commercially available products include "NeoCryl (registered trademark) A-1127" (manufactured by Kusumoto Chemicals, Ltd.), "Mobinyl (registered trademark) 6899D", "Mobinyl (registered trademark) 6969D", "Mobinyl (registered trademark) 6800", "Mobinyl (registered trademark) 6810" (manufactured by Japan Coating Resin Co., Ltd. for all of the above), "TOCryl (registered trademark) W-7146", "TOCryl (registered trademark) W-7150", "TOCryl (registered trademark) W-7152" (manufactured by Toyo Kchem Co., Ltd. for all of the above), and the like.

[0099] The content of the resin particles is preferably within the range of 1 to 20% by mass with respect to the total mass of the ink.

[0100] <Solvent> From the perspective that the ink contains water, the organic solvent is preferably water-soluble. Examples of high-boiling water-soluble solvents having a boiling point within the range of 120 to 250°C include alcohols, polyhydric alcohols, amines, amides, glycol ethers, 1,2-alkanediols having 4 or more carbon atoms, and the like.

[0101] The water-soluble solvent preferably has an SP value of 24 (J / cm ３ ) １／２ or more. When the SP value is 24 (J / cm ３ ) １／２ or more, the cloud point of the ink decreases. Here, the "cloud point" refers to the temperature at which phase separation occurs due to temperature change and as a result, the ink becomes opaque. By reducing the cloud point, the ink can be heated at a temperature above the cloud point in the ink drying process, so that phase separation can be suppressed, and in particular, the adhesion of the ink to a non-absorbent substrate can be improved.

[0102] The "SP value" refers to the solubility parameter, which is calculated by the Fedors method. The SP value is obtained from the molar heat of vaporization and the molar volume at 25°C. Although it is common to use cal as the unit of the SP value, when converting to the SI unit system, (cal / cm ３ ) １／２ = 2.046×10 ３ (J / m ３ ) １／２You can use the following relationship. Below, the unit of the SP value may be omitted, but the SP value is (J / cm²). ３ ) １／２ It is a value expressed in units of [unit].

[0103] SP value is 24 (J / cm ３ ) １／２ Examples of water-soluble solvents that meet the above criteria and have a boiling point in the range of 120 to 250°C include polyhydric alcohols having 2 to 8 carbon atoms, glycol ethers, polyalkylene glycols, and the like.

[0104] Polyhydric alcohols with 2 to 8 carbon atoms include 1,2-ethanediol (SP value: 30.3, boiling point: 197°C), 1,2-propanediol (SP value: 28.0, boiling point: 188°C), 1,3-propanediol (SP value: 32.9, boiling point: 213°C), 1,2-butanediol (SP value: 26.1, boiling point: 192°C), 1,3-butanediol (SP value: 30.3, boiling point: 207°C), 1,4-butanediol (SP value: 30.7, boiling point: 230°C), and 2,3-butanediol (SP value: 2 Examples include 9.9 (boiling point: 177°C), 2-methyl-1,3-propanediol (SP value: 30.3, boiling point: 214°C), 1,2-pentanediol (SP value: 25.0, boiling point: 210°C), 1,5-pentanediol (SP value: 29.0, boiling point: 242°C), 1,2-hexanediol (SP value: 24.1, boiling point: 223°C), 1,6-hexanediol (SP value: 27.7, boiling point: 249°C), and 2-methylpentane-2,4-diol (SP value: 26.8, boiling point: 197°C).

[0105] Examples of glycol ethers include propylene glycol monoethyl ether (SP value: 23.2, boiling point: 132°C), propylene glycol monopropyl ether (SP value: 25.7, boiling point: 150°C), and 2-methoxyethanol (SP value: 26.0, boiling point: 124°C).

[0106] Examples of polyalkylene glycols include diethylene glycol (SP value: 30.6, boiling point 244°C) and dipropylene glycol (SP value: 27.2, boiling point 230°C).

[0107] These water-soluble solvents may be used individually or in combination of two or more.

[0108] In addition to high-boiling-point water-soluble solvents, other solvents may be used in combination. Examples of other solvents include glycerin (SP value: 33.5, boiling point: 290°C), trimethylolpropane (SP value: 32.5, boiling point: 295°C), triethylene glycol (SP value: 27.8, boiling point: 287°C), tetraethylene glycol (SP value: 26.1, boiling point: 275°C), ethanol (SP value: 12.7, boiling point: 78°C), and isopropanol (SP value: 11.4, boiling point: 82°C).

[0109] The content of the water-soluble solvent is not particularly limited, but it is preferably in the range of 5 to 60% by mass relative to the total mass of the ink.

[0110] The water contained in the ink is not particularly limited and may include deionized water, distilled water, or pure water. The water content is not particularly limited, but it is preferably in the range of 10 to 60% by mass relative to the total mass of the ink.

[0111] <Additives> The ink may contain other additives as needed. Examples of additives include surfactants, waxes, polysaccharides, viscosity modifiers, resistivity modifiers, film-forming agents, UV absorbers, antioxidants, fade inhibitors, antifouling agents, rust inhibitors, etc. Examples of additives include liquid paraffin, dioctyl phthalate, tricresyl phosphate, oil droplets such as silicone oil, ultraviolet absorbers described in Japanese Patent Publication Nos. 57-74193, 57-87988, and 62-261476, anti-fading agents described in Japanese Patent Publication Nos. 57-74192, 57-87989, 60-72785, 61-146591, 1-95091, and 3-13376, fluorescent whitening agents described in Japanese Patent Publication Nos. 59-42993, 59-52689, 62-280069, 61-242871, and 4-219266. By including additives, ejection stability, compatibility with print heads and ink cartridges, storage stability, image preservation, and other performance aspects can be improved.

[0112] <Viscosity> The viscosity of the ink at 25°C is preferably in the range of 1 to 80 mPa·s, more preferably in the range of 1 to 40 mPa·s, and even more preferably in the range of 2 to 10 mPa·s. This ensures that the dispensed ink has appropriate pinning properties on the substrate.

[0113] The viscosity of the ink can be measured, for example, using a rotational viscometer "TP-200E" manufactured by Toki Sangyo Co., Ltd., under the following measurement conditions: 25°C, standard cone rotor (1°34′ × R24), sample volume of 1.1 mL, rotation speed of 50 rpm, and 1 minute.

[0114] <Static Surface Tension> The static surface tension of the ink at 25°C preferably satisfies the following conditions: When the substrate is absorbent, the static surface tension of the ink at 25°C preferably is in the range of 30 to 55 mN / m. When the substrate is non-absorbent, the static surface tension of the ink at 25°C preferably is in the range of 20 to 40 mN / m. By being within the above range, high adhesive strength can be obtained in the heat-seal region regardless of the absorption performance of the substrate.

[0115] For absorbent substrates, the ink is absorbed by the substrate and spreads easily, so a relatively high static surface tension is preferable. For non-absorbent substrates, the ink is not easily absorbed by the substrate and does not spread easily, so a relatively low static surface tension is preferable.

[0116] In this embodiment, the static surface tension is the static surface tension measured by the Wilhelmy method. Specifically, the static surface tension of the ink at 25°C can be measured in accordance with JIS K2241 using, for example, an automatic surface tension meter "DY-300" (manufactured by Kyowa Interface Science Co., Ltd.).

[0117] <Dispensing Conditions> As described above, it is preferable that the adhesive strength of the heat-sealed area 4 be adjusted as needed for each part. Figure 10 is a diagram illustrating the adhesive strength in the heat-sealed area 4. The first edge portion 4A, which corresponds to the center seal area, is preferably given a higher adhesive strength from the viewpoint of improving the airtightness of the package 7. The second edge portion 4B, which corresponds to the end seal area, is preferably given a slightly weaker adhesive strength than the first edge portion 4A from the viewpoint of providing easy opening. However, it is preferable to give a higher adhesive strength to the central portion 4E of the second edge portion 4B, which corresponds to the quadruple seal area.

[0118] Methods for changing the adhesive strength in the heat-sealed area 4 include changing the discharge volume, discharge area, or discharge pattern. These methods may also be combined.

[0119] When changing the discharge rate, it is preferable to satisfy the following conditions: By changing the discharge rate on the same substrate, heat-sealed areas with different amounts of adhesive per unit area can be formed. In the heat-sealed areas with different amounts of adhesive per unit area, it is preferable that the difference in peel strength is within the range of 0.1 to 10 N / 15 mm. As a result, the packaging material formed on the same substrate using the same ink has sufficient adhesive strength and also has excellent airtightness, ease of opening, etc.

[0120] In other words, in Figure 10, it is preferable to make the width WA of the first edge 4A, the width WB of the second edge 4B, and the width WE of the central part 4E the same, and to adjust the adhesive strength by changing the amount of ink ejected in each region. In this case, it is preferable that the difference in peel strength between the first edge 4A, the second edge 4B, and the central part 4E be within the range of 0.1 to 10 N / 15 mm. Furthermore, it is preferable to adjust the ink composition to satisfy this condition.

[0121] The peel strength in each region can be confirmed by the following procedure. Apply ink to a predetermined substrate in a shape of 15 mm wide x 100 mm long at a discharge amount corresponding to a predetermined region, forming a heat-seal region of 15 mm wide x 100 mm long. Prepare two of these samples. Overlap the two samples so that the heat-seal layers face each other, and heat-seal them using a tabletop sealer "NL-103J" (manufactured by Ishizaki Electric Works) at a setting of 4.5.

[0122] The peel strength of the bonded samples will be measured under the following conditions. For example, a benchtop tensile and compression testing machine "MCT-1150" (manufactured by AND Co., Ltd.) will be used as the measuring instrument. In accordance with JIS Z1707:2019, the two substrates to be bonded will be peeled apart under the conditions of initial chuck distance: 100 mm, peel angle: 180 degrees, and test speed: 300 mm / min, and the peel strength will be measured.

[0123] <Manufacturing Method> The ink is obtained by mixing the above materials.

[0124] (1.2) Ink drying process In the ink drying process S12, the ink discharged onto the substrate 3 is heated and dried using the drying apparatus described above. This yields the packaging material 5. The heating temperature is not particularly limited, but it is preferable to set the surface temperature of the substrate 3 within the range of 30 to 150°C. This allows for sufficient removal of the solvent (water-soluble solvent and water) from the ink.

[0125] Furthermore, the detailed configuration of each part constituting the packaging device can also be modified as appropriate, without departing from the spirit of this disclosure.

[0126] The present disclosure will now be described in more detail by examples, but this disclosure is not limited to these examples. In the examples, the units "parts" or "%" are used, and unless otherwise specified, they represent "parts by mass" or "mass%". In addition, in the following examples, the operations were carried out at room temperature (25°C) unless otherwise specified.

[0127] 1. Preparation of Ink (1) Preparation of Ink [1] Ink [1] was prepared by mixing the following components: Water-based special modified polyolefin "Aurolene (registered trademark) AE-301" (manufactured by Nippon Paper Industries Co., Ltd.) 10.0 parts by mass Propylene glycol 5.0 parts by mass Water 85.0 parts by mass

[0128] The prepared ink [1] had a viscosity of 2.1 mPa·s (2.1 cP) at 25°C, an average particle size of 77.9 nm, and a static surface tension of 33.9 mN / m at 25°C.

[0129] (2) Preparation of Ink [2] Ink [2] was prepared by mixing the following components: Polyolefin aqueous dispersion "Chemipearl (registered trademark) ET300H" (manufactured by Mitsui Chemicals, Inc.) 10.0 parts by mass Propylene glycol 10.0 parts by mass Water 80.0 parts by mass

[0130] The prepared ink [2] had a viscosity of 2.1 mPa·s (2.1 cP) at 25°C, an average particle size of 275.1 nm for the resin particles, and a static surface tension of 38.2 mN / m at 25°C.

[0131] (3) Preparation of Ink [3] Ink [3] was prepared by mixing the following components: Modified polyolefin resin aqueous dispersion "Arrowbase (registered trademark) SB-1030N" (manufactured by Unitika Ltd.) 10.0 parts by mass Propylene glycol 30.0 parts by mass Water 60.0 parts by mass

[0132] The prepared ink [3] had a viscosity of 6.6 mPa·s (6.6 cP) at 25°C, an average particle size of 132.0 nm for the resin particles, and a static surface tension of 45.8 mN / m at 25°C.

[0133] (4) Preparation of Ink [4] Ink [4] was prepared by mixing the following components: Modified polyolefin resin aqueous dispersion "Arrowbase (registered trademark) SE-1030N" (manufactured by Unitika Ltd.) 10.0 parts by mass Propylene glycol 30.0 parts by mass Water 60.0 parts by mass

[0134] The prepared ink [4] had a viscosity of 6.6 mPa·s (6.6 cP) at 25°C, an average particle size of 125 nm for the resin particles, and a static surface tension of 45.5 mN / m at 25°C.

[0135] (5) Preparation of Ink [5] Ink [5] was prepared by mixing the following components: Modified polyolefin resin aqueous dispersion "Arrowbase (registered trademark) DA-1010" (manufactured by Unitika Ltd.) 10.0 parts by mass Propylene glycol 25.0 parts by mass Water 65.0 parts by mass

[0136] The prepared ink [5] had a viscosity of 5.15 mPa·s (5.15 cP) at 25°C, an average particle size of 48.3 nm, and a static surface tension of 53.1 mN / m at 25°C.

[0137] (6) Preparation of Ink [6] Ink [6] was prepared by mixing the following components: Modified polyolefin resin aqueous dispersion "Arrowbase (registered trademark) YA-6005N" (manufactured by Unitika Ltd.) 10.0 parts by mass Propylene glycol 35.0 parts by mass Water 55.0 parts by mass

[0138] The prepared ink [6] had a viscosity of 6.0 mPa·s (6.0 cP) at 25°C, an average particle size of 201.3 nm, and a static surface tension of 43.7 mN / m at 25°C.

[0139] (7) Preparation of Ink [7] Ink [7] was prepared by mixing the following components: Polyurethane aqueous dispersion "Superflex (registered trademark) 210" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 10.0 parts by mass Propylene glycol 30.0 parts by mass Water 60.0 parts by mass

[0140] The prepared ink [7] had a viscosity of 5.1 mPa·s (5.1 cP) at 25°C, an average particle size of 47.9 nm, and a static surface tension of 43.6 mN / m at 25°C.

[0141] (8) Preparation of Ink [8] Ink [8] was prepared by mixing the following components: Wetting agent "SURFYNOL (registered trademark) 440" (manufactured by Nisshin Chemical Industry Co., Ltd.) 1.0 part by mass Modified polyolefin resin aqueous dispersion "Arrowbase (registered trademark) SE-1030N" (manufactured by Unitika Ltd.) 10.0 parts by mass Propylene glycol 30.0 parts by mass Water 59.0 parts by mass

[0142] The prepared ink [8] had a viscosity of 7.3 mPa·s (7.3 cP) at 25°C, an average particle size of 137 nm for the resin particles, and a static surface tension of 33.2 mN / m at 25°C.

[0143] (9) Preparation of Ink [9] Ink [9] was prepared by mixing the following components: Wetting agent "SURFYNOL (registered trademark) 440" (manufactured by Nisshin Chemical Industry Co., Ltd.) 0.5 parts by mass Modified polyolefin resin aqueous dispersion "Arrowbase (registered trademark) SE-1030N" (manufactured by Unitika Ltd.) 10.0 parts by mass Propylene glycol 30.0 parts by mass Water 59.5 parts by mass

[0144] The prepared ink [9] had a viscosity of 7.0 mPa·s (7.0 cP) at 25°C, an average particle size of 128 nm for the resin particles, and a static surface tension of 36.4 mN / m at 25°C.

[0145] (10) Preparation of Ink

[10] Ink

[10] was prepared by mixing the following components: Modified polyolefin resin aqueous dispersion "Arrowbase (registered trademark) SD-1010" (manufactured by Unitika Ltd.) 10.0 parts by mass Propylene glycol 30.0 parts by mass Water 60.0 parts by mass

[0146] The prepared ink

[10] had a viscosity of 9.7 mPa·s (9.7 cP) at 25°C, an average particle size of 96.7 nm, and a static surface tension of 49.7 mN / m at 25°C.

[0147] (11) Preparation of ink

[11] Ink

[11] was prepared by mixing the following components: Polyurethane aqueous dispersion "Superflex (registered trademark) 150" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 10.0 parts by mass Propylene glycol 30.0 parts by mass Water 60.0 parts by mass

[0148] The prepared ink

[11] had a viscosity of 4.8 mPa·s (4.8 cP) at 25°C, an average particle size of 55.6 nm, and a static surface tension of 42.7 mN / m at 25°C.

[0149] 2. Example I (1) Example [1] (1.1) Preparation of packaging material As shown in Figure 11, the ink [4] was applied in a solid coat on the OPP film used as the base material in the shape of a 1 cm wide, 10 x 20 cm square frame. The amount of ink [4] discharged in the heat seal area was 6 g / m ２ , the amount of ink [4] ejected in the non-heat-sealed area is 0 g / m ２The following was done. The OPP film was then heated and dried in an oven set to 80°C for 10 minutes to remove the solvent from the ink [4] and obtain packaging material [1-1]. The following OPP film and inkjet printer were used. OPP film: Biaxially oriented polypropylene film "FOS-AQ #50" (manufactured by Futamura Chemical Co., Ltd.) Inkjet printer: A scan-type printer equipped with an independently driven inkjet head (360 npi, 1024 nozzles) manufactured by Konica Minolta was prepared.

[0150] (1.2) Preparation of the packaging The obtained packaging material [1-1] was folded in the Y-axis direction so that the heat-seal area was on the inside, and heat-sealed using a tabletop sealer "NL-103J" (manufactured by Ishizaki Electric Works Co., Ltd.) at setting 4.5. This resulted in the packaging [1-1] with a three-sided seal, as shown in Figure 12. In the packaging [1-1], three sides were bonded by heat sealing.

[0151] (2) Examples [2] to [4] and Comparative Examples [1] to [2] In Example [2], when preparing the packaging material [1-2], the amount of ink [4] discharged in the heat seal area was 12 g / m ２ , the amount of ink [4] ejected in the non-heat-sealed area is 0 g / m ２ In other words, compared to packaging material [1-1], the amount of material discharged in the heat-seal area was increased, and the heat-seal area was made thicker. Otherwise, the same procedure as for packaging material [1-1] was followed to obtain a package [1-2] with a three-side seal.

[0152] In Example [3], as shown in Figure 13, when preparing the packaging material [1-3], ink [4] was applied as a solid coat in the shape of a 1 cm wide, 10 x 20 cm square frame. The amount of ink [4] discharged in the central part 4E of the heat seal area was 12 g / m². ２ The amount of ink [4] ejected in the heat-sealed area other than the central part 4E is 6 g / m². ２ , the amount of ink [4] ejected in the non-heat-sealed area is 0 g / m ２The rest was prepared using the same procedure as for packaging material [1-1], and a pillow-packed package [1-4] was obtained. In example [4], the central part 4E was defined as the area 4 to 6 cm from the end in the X-axis direction.

[0153] In Example [4], as shown in Figure 14, when preparing the packaging material [1-4], ink [4] was applied as a solid coat in the shape of a 1 cm wide, 10 x 10 cm square frame. The amount of ink [4] discharged in the heat-seal area was 6 g / m². ２ , the amount of ink [4] ejected in the non-heat-sealed area is 0 g / m ２ The OPP film was then heated and dried in an oven to remove the solvent from the ink [4] and obtain packaging material [1-4].

[0154] A container with a 9.5 x 9.5 cm square opening was prepared. The heat-sealed area of ​​the obtained packaging material [1-4] was placed on top of the container so that it was in contact with the opening, and it was sealed using a tabletop sealer "NL-103J" (manufactured by Ishizaki Electric Works) at a setting of 4.5. This resulted in a package [1-4] with a top-seal packaging that sealed the opening of the container with a lid.

[0155] In Comparative Example [1], a 50 μm thick heat-sealable biaxially oriented polypropylene film "HC-OP" (manufactured by Tosello Co., Ltd.) was used as the packaging material [2-1] to obtain a package [2-1] by pillow packaging. In packaging material [2-1], a heat-sealed area was formed across the entire film surface by co-extrusion. The areas bonded by heat sealing, the heat sealer used, and the operating conditions were the same as those for package [1-1].

[0156] In comparative example [2], a heat-sealable film was laminated to the above OPP film to produce packaging material [2-2]. Using the produced packaging material [2-2], a pillow-packaged package [2-2] was obtained. In packaging material [2-2], a heat-sealable area was formed over the entire film surface, and the heat-sealable area (laminate film) was thicker compared to package [2-1]. The area bonded by heat sealing, the heat sealer used, and the usage conditions were the same as for package [1-1].

[0157] (3) Evaluation (3.1) Adhesion (Peel Strength) The peel strength of the obtained packaging was measured under the following conditions. A benchtop tensile and compression testing machine "MCT-1150" (manufactured by AND Co., Ltd.) was used as the measuring instrument. In accordance with JIS Z1707:2019, the two substrates (OPP film) to be bonded were peeled off under the conditions of initial chuck distance: 100 mm, peel angle: 180 degrees, and test speed: 300 mm / min, and the peel strength was measured. In the case of three-side seal packaging, peeling occurred from the corner where two adjacent sides were bonded by heat seal. In the case of pillow packaging, peeling occurred from the center of the side bonded by end seal. In the case of top seal packaging, peeling occurred from the corner where the container and packaging material were bonded by heat seal. The measured values ​​were evaluated according to the following criteria. A score of B or higher (A to B) was considered acceptable as there were no practical problems.

[0158] A: The peel strength is 3 N / 15 mm or more. B: The peel strength is 1 N / 15 mm or more, and less than 3 N / 15 mm. C: The peel strength is less than 1 N / 15 mm.

[0159] (3.2) For the packaging in which the seal had come loose, the sealed space was pressed from above by hand. Specifically, in the packaging [1-1] shown in Figure 12, the inside of the bonded heat-sealed area 4 was pressed by hand in a direction perpendicular to the paper plane. When pressing by hand, a new piece of the above OPP film cut to an appropriate size was prepared and held near the bonded heat-sealed area 4 to check whether the film fluttered. If the film did not flutter, i.e., there was no seal coming loose, it was considered acceptable as there was no practical problem.

[0160] No seal defects: The film did not flap, and no air leaks were observed. Seal defects present: The film flap, and air leaks were observed.

[0161] (3.3) Ease of opening (peel strength) Peel strength was measured using the same procedure as for adhesion evaluation. The measured values ​​were evaluated according to the following criteria. A score of B or higher (A to B) was considered acceptable as there were no practical problems.

[0162] A: The peel strength is 10 N / 15 mm or less. B: The peel strength is greater than 10 N / 15 mm and 15 N / 15 mm or less. C: The peel strength is greater than 15 N / 15 mm.

[0163] Table I below shows the packaging structure and evaluation results for Examples [1] to [4] and Comparative Examples [1] to [2].

[0164]

[0165] From the examples and comparative examples, it can be seen that in this embodiment, the desired adhesive strength can be provided to each region, thus achieving both airtightness and ease of opening of the packaging. In all of the obtained packaging materials, the weight per unit area of ​​the heat-sealed region was 2 g / m². ２ The results were as follows, indicating a relatively low environmental impact. Furthermore, in all of the obtained packaging materials, the proportion of the heat-sealed area to the total mass of the packaging material was 5% by mass or less, indicating high recyclability.

[0166] In Example [3], the central portion 4E of the bonded heat-sealed area had higher adhesive strength compared to the other areas (first edge 4A and second edge 4B), and the difference in peel strength was within the range of 0.1 to 10 N / 15 mm. By adjusting the adhesive strength of the packaging material within a predetermined range according to the packaging form, it can be seen that, for example, when used in a pillow-package, it is possible to have sufficient adhesive strength to bond even in the quadruple-sealed area while also having a certain degree of ease of opening.

[0167] 3. Example II (1) Examples [5] to [8] Using the inks listed in Table II, heat-seal regions were formed on the absorbent and non-absorbent substrates described below using the same procedure as for packaging material [1-1] to produce packaging materials [1-5] to [1-8]. From the produced packaging materials, packaging bodies [1-5] to [1-8] were obtained using the same procedure as for packaging body [1-1], with three-sided seal packaging. The non-absorbent substrate used was the OPP film described above. Absorbent substrate: high-quality paper Non-absorbent substrate: the OPP film described above

[0168] (2) The adhesive properties (peel strength) of the evaluated packaging materials were measured using the same method as above and evaluated according to the following criteria. A rating of B or higher (AA to B) was considered acceptable as there were no practical problems. Table II below shows the evaluation results of the packaging materials in Examples [5] to [8]. The peel strength was compared when the base material of the packaging material was absorbent and when it was non-absorbent.

[0169] AA: Peel strength is 5 N / 15 mm or more. A: Peel strength is 3 N / 15 mm or more and less than 5 N / 15 mm. B: Peel strength is 1 N / 15 mm or more and less than 3 N / 15 mm. C: Peel strength is less than 1 N / 15 mm.

[0170]

[0171] When the substrate is absorbent, the peel strength can be improved by having the static surface tension of the ink at 25°C in the range of 30 to 55 mN / m. When the substrate is non-absorbent, the peel strength can be improved by having the static surface tension of the ink at 25°C in the range of 20 to 40 mN / m. In other words, the peel strength can be adjusted by adjusting the static surface tension of the ink according to the absorbency of the substrate.

[0172] 4. Example III (1) Examples [9] to

[15] and Comparative Example [3] Using the inks listed in Table III, heat-seal regions were formed on the OPP film in the same procedure as for packaging material [1-1] to produce packaging materials [1-9] to [1-15] and [2-3]. From the produced packaging materials, packaging bodies [1-9] to [1-15] and [2-3] were obtained by three-side sealing packaging in the same procedure as for packaging body [1-1].

[0173] (2) Evaluation (2.1) Using the inkjet printer head used to form the inkjet ejectable heat seal area, continuous ejection (driving) was performed under conditions of droplet velocity of 6 m / sec, ejection frequency of 20 kHz, and print coverage of 100%. After 10 minutes from the start of driving, the number of non-ejecting nozzles was counted and evaluated according to the following criteria. A rating of B or higher (A to B) was considered acceptable as there were no practical problems.

[0174] A: The number of defective nozzles is 0. B: The number of defective nozzles is between 1 and 9. C: The number of defective nozzles is 10 or more.

[0175] (2.2) Adhesion (Peel Strength) The adhesion (peel strength) was measured using the same method as above and evaluated according to the following criteria. Grades B or higher (AA to B) were considered acceptable as there were no practical problems. AA: Peel strength is 5 N / 15 mm or more. A: Peel strength is 3 N / 15 mm or more and less than 5 N / 15 mm. B: Peel strength is 1 N / 15 mm or more and less than 3 N / 15 mm. C: Peel strength is less than 1 N / 15 mm.

[0176] The evaluation results are shown in Table III below. Note that the ink

[11] used in Comparative Example 3 had a resin melting point exceeding 200°C and was an ink that did not possess the heat-sealing properties defined in this embodiment.

[0177]

[0178] From the examples and comparative examples, it can be seen that the heat-sealed areas formed using the ink of this embodiment have sufficient adhesive strength, i.e., they have heat-seal properties. Furthermore, it can be seen that the ink of this embodiment has high ejection properties in inkjet printing.

[0179] Examples 9 to 14 show that the discharge performance is improved when the dispersion form of the resin particles is self-emulsifying.

[0180] Examples 9 to 15 show that the adhesion is improved when the resin particles contain polyolefin.

[0181] This disclosure makes it possible to partially adjust the adhesive strength of the bonded areas in the packaging material, thereby achieving both airtightness and ease of opening in the package.

[0182] 1 Packaging device 2 Long roll 3 Base material 4 Heat seal area 5 Packaging material 6 Packaged item 7 Package body 8 Package body 11 First conveyor roller 20 Ink ejection section 30 Ink drying section 41 Second conveyor roller 51 Third conveyor roller 52 First conveyor belt 53 Fourth conveyor roller 61 Bag maker 62 Center seal section 63 Pinch roller 64 Pressure roller 65 End seal section 71 Fifth conveyor roller 72 Second conveyor belt 4A First edge 4B Second edge 4E Center section 7A Center seal area 7B End seal area 7C Quadruple seal area 7D Hole W Width

Claims

1. A packaging method for packaging an object to be packaged using a packaging material having a heat-seal region on a base material, comprising: a heat-seal region forming step of forming the heat-seal region on the base material; and an adhesion step of heating and bonding the formed heat-seal region, wherein the heat-seal region forming step comprises: an ink ejection step of ejecting heat-sealable inkjet ink onto the base material; and an ink drying step of drying the base material on which the heat-sealable inkjet ink has been ejected.

2. The packaging method according to claim 1, wherein the amount of heat-sealable inkjet ink ejected in the ink ejection step is changed according to the packaging form.

3. The packaging method according to claim 1 or 2, wherein in the ink ejection step, the ejection area of ​​the heat-sealable inkjet ink on the substrate is changed according to the packaging form.

4. The packaging method according to claim 1 or claim 2, wherein the amount of heat-sealable inkjet ink ejected in the ink ejection step is changed to form heat-seal regions on the same substrate with different amounts of ink per unit area, and the difference in peel strength in the formed heat-seal regions with different amounts of ink per unit area is within the range of 0.1 to 10 N / 15 mm.

5. The packaging method according to claim 1 or claim 2, wherein the bonding step comprises a center sealing step of bonding the packaging material along the longitudinal direction and an end sealing step of bonding the packaging material along the width direction.

6. The packaging method according to claim 1 or claim 2, wherein the bonding step comprises a top sealing step of bonding the packaging material to the opening of the container to seal the container.

7. The packaging method according to claim 1 or 2, wherein, when the substrate is absorbent, the static surface tension of the heat-sealable inkjet ink at 25°C is in the range of 30 to 55 mN / m.

8. The packaging method according to claim 1 or 2, wherein, when the substrate is non-absorbent, the static surface tension of the heat-sealable inkjet ink at 25°C is in the range of 20 to 40 mN / m.

9. The packaging method according to claim 1 or 2, comprising, between the heat-seal region formation step and the bonding step, a packaging material transport step for transporting the packaging material on which the heat-seal region has been formed, and a packaged object supply step for supplying the packaged object to the vicinity of the packaging material so that the packaged object is covered by the packaging material.

10. A packaging apparatus for packaging an object to be packaged using a packaging material having a heat-seal region on a base material, comprising: a heat-seal region forming unit for forming a heat-seal region on the base material; and an adhesive unit for heating and bonding the formed heat-seal region, wherein the heat-seal region forming unit comprises: an ink dispensing unit for dispensing heat-sealable inkjet ink onto the base material; and an ink drying unit for drying the base material on which the heat-sealable inkjet ink has been dispensed.

11. A heat-sealable inkjet ink comprising resin particles and a solvent, wherein the resin particles contain a resin having a melting point in the range of 50 to 200°C, the average particle size of the resin particles is in the range of 30 to 300 nm, the solvent comprises an organic solvent having a boiling point in the range of 120 to 250°C and water, and the viscosity at 25°C is in the range of 1 to 80 mPa·s.

12. The heat-sealable inkjet ink according to claim 11, wherein the dispersion form of the resin particles is self-emulsifying.

13. The heat-sealable inkjet ink according to claim 11, wherein the resin particles contain polyolefin.

14. A packaging material having heat-sealed regions on a substrate with different amounts of adhesive per unit area, wherein the difference in peel strength between the heat-sealed regions with different amounts of adhesive per unit area is within the range of 0.1 to 10 N / 15 mm.

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