JP6992945B2 - Plastic film bag with gusset - Google Patents

Description

The present invention relates to a plastic film bag with a gusset, and more specifically, a bag body made of a plastic film having folds (hereinafter, also referred to as gussets) on both sides, and particularly accommodating a water-containing object. With respect to a plastic film bag with a gusset suitable for.

A bag with a gusset, also known as a gusset bag, can store a large amount of items as compared with a bag without a gusset, and is therefore widely used as a bag for household waste and mushroom cultivation.
A general plastic film bag with a gusset has an opening that expands in a substantially square shape at the top and a fold-out portion (hereinafter, also referred to as a gusset portion) that is folded to a predetermined depth on both sides below the opening. The bottom seal portion is provided with a bottom seal portion in the bottom portion in which the opening facing the opening is closed by a heat seal, and the bottom seal portion is formed of a substantially straight linear heat welded portion extending over the entire width of the bag.

In this linear heat welded portion, a four-layer film is welded at the gusset portions on both sides, a two-layer film is welded at the central portion, and there are four points where the inner end of the gusset portion of the folded portion and the linear heat welded portion intersect. It is a place where the layer film has changed to a double layer film.
In such a plastic film bag with a gusset, when a large amount of material is stored in the bag, a pinpoint hole (hereinafter referred to as a pinhole) in the linear heat welded portion where the intersection with the inner end of the gusset portion receives a strong traction force from the surroundings. There is a problem that the pinhole) opens or is damaged.

Various devised bags have been proposed to solve this problem.

For example, Patent Document 1 below describes two types of bags whose names are referred to as plastic film bags with side gussets. As shown in FIG. 9A, one bag body 1A is formed by folding both sides of the quadrilateral bag body of the upper opening 2a inward to form a gusset portion 3, and is substantially horizontal to the entire lower width. A heat-welded seal portion 4 is formed, and the heat-welded seal portion 4 is formed with a pair of concave seal portions 4b and 4b that detour downward at a position intersecting the inner end 5 of the gusset portion.

Further, the other bag body 1B inclines the outer heat welding seal portions 4a'4a' of the concave detour seal portions 4A and 4A in place of the linear outer heat welding seal portions 4a and 4a of the bag body 1A. It is formed by the inclined sides 4a'and 4a'(see FIGS. 9B and 9C).

Further, the packaging bag described in Patent Document 2 below is manufactured by heat-sealing a resin film flat tube with a gusset manufactured by an inflation method and then cutting it to the length of the bag with a cutting device. be.

The packaging bag has a single linear weld with a frontal profile profile that bulges below the bag, which linearly welds across the inner folded edges of the left and right gussets. The only extending deformed part is in the center of the width direction of the bag, and the deformed part is connected to the left and right curved parts gently curved from the straight part of the linear fusion part and the curved part between the left and right curved parts. The arcuate portion of the lower bulge crosses the inner folded edge of the left and right gussets, and is formed from the fusion of the four-layer film to two layers. A fused portion of the linear fused portion that changes to the fused portion of the film is formed at the intersection portion of the inner folded edge and the lower bulging portion. This intersection is also located closer to the bottom edge of the bag than the straight section, and is a downward bulge formed by welding a two-layer film to the central band of the bag formed between the inner folded edges. The arcuate fusion portion of is formed.

In the specification, this packaging bag is manufactured by using a continuous operation rotary device instead of this heat seal device because there is a problem in using the elevating heat seal device for intermittent operation. It is explained that there is.

Utility Model Registration No. 3073221 Japanese Patent No. 5400466 Japanese Unexamined Patent Publication No. 2013-189247 Japanese Unexamined Patent Publication No. 2010-15823

According to one of the two types of bag bodies described in Patent Document 1, when the bag body is filled with an object, the tensile force is not concentrated on one point as in the conventional case. Since it is dispersed at the upper end bonding point of the recess and other detours, it is possible to effectively avoid holes due to pulling, and according to the other bag body 1B, when waste or the like is stored in the bag body. It is explained that since the pull of the side gusset portion is from diagonally above, the tensile strength of the detour concave seal portions 4a', 4a' (see FIGS. 9B and 9C) of the bag body is further strengthened. ..

Further, according to the packaging bag described in Patent Document 2, the intersection portion between the inner folded edge and the linear fusion portion is formed in a downwardly curved downward bulging portion, and this intersection portion is linearly fused. Since it is arranged at a position displaced below the portion, the force transmitted from the linear fusion portion to the intersection portion is relaxed, and damage to the film fusion portion at the intersection portion can be effectively prevented. A linear fusion zone is not formed in the central band of the two-layer structure, and a linear fusion zone having a relatively large length continuous to the edge of the bag is formed on both sides of the downward bulge. Therefore, it is explained that the load acting on the bottom of the bag can be effectively distributed to the linear fusion portions on both sides.

The applicant of the present application is engaged in the bag making business of bags for mushroom cultivation, and using the bags described in the above Patent Documents 1 and 2 for mushrooms, several mushroom cultivation bags are prototyped, and water is added to them. When it was put in and a water leak test was conducted, some water leaked.

All of these water leaks are due to pinholes, and the causes are considered to be as follows.
(A) The bag body described in Patent Documents 1 and 2 and the prototype mushroom cultivation bag have different configurations.
That is, in the bag body of Patent Document 1, the point where the heat-welded seal portion and the inner end of the gusset portion intersect is at the linear bottom portion in the concave seal portion, and in Patent Document 2, the thickness of the film is described. Although it is not specified, it is thin (the thickness of the packaging bag described in Patent Document 3 of the same applicant is 13 μm or more and 20 μm or less), and it is heat-welded and sealed by a rotary heat-sealing device. The thickness of the film and the heat seal device are different from the prototype mushroom cultivation bag.

(B) Specifications that can withstand the mushroom cultivation process are required.
For example, in the cultivation of shiitake mushrooms, the cultivation process is generally a bagged step of packing a predetermined medium into a cultivation bag, a sterilization step of sterilizing the bagged medium at a predetermined temperature, and releasing the bagged medium. Inoculation process of inoculating shiitake mushrooms after cooling, culture process of culturing for a predetermined period by adjusting temperature / humidity and light, generation process of controlling temperature / moisture to generate mushrooms, and harvesting and shipping of generated mushrooms It is a harvesting and shipping process. Recently, medium bagging has come to be performed by an automatic medium filling machine.

Most of these cultivation bags are made of thin plastic film, and mechanical forces of various sizes are applied everywhere when packing the medium or moving the cultivation bag filled with the medium. Since it is used in harsh environments such as being exposed to high temperatures, being soaked in water, and having a long period of time, it must be able to withstand these usage environments. If, during these steps, the cultivation bag is torn and a small hole is opened and a so-called pinhole is generated, various germs invade or water leaks from the pinhole, resulting in poor mushroom cultivation. This would cost mushroom growers a great deal of damage. For this reason, mushroom cultivation bags are required to have specifications that do not cause tearing or pinholes, as compared with general garbage bags.

From the above, it can be said that none of the bags described in Patent Documents 1 and 2 is suitable for mushroom cultivation and cannot be used.

Hereinafter, the pinhole of the mushroom cultivation bag in the fungal bed cultivation will be additionally described. Pinholes often occur at the heat-sealed parts, but they may also occur in the process of bagged the culture medium. That is, since the base material of the medium is generally hardwoods such as oak, oak, and castanopsis in the form of chips or powder, the tips of these chips or the like are sharply pointed like needles or have horns. When the parts are standing, those sharp parts and corners break through the thin plastic film of the cultivation bag and generate pinholes.

Until now, in order to suppress the occurrence of such pinholes, water was sprinkled on the medium base material in a shower shape, or the medium base material and water were put in a mixer and stirred to infiltrate the base material. The needle-shaped protrusions and corners of the shower were made flexible to suppress the occurrence of pinholes. However, in such a flooding method, since the base material such as chips must be immersed in water for several days, the medium rots during that time, or the flooding takes time, and the mushroom cultivation is hindered or the efficiency is lowered. There are issues such as.

In order to solve this problem, in the pre-preparation of the medium base material of the mushroom bed, hot water (hot water of 80 ° C or higher) is poured into the wood chips and the like to soften the wood surface. A hot water treatment method for a mushroom bed medium substrate has been proposed, in which an appropriate amount of water is absorbed into the medium substrate and the needle-like protrusions and corners of the medium substrate are softened to suppress the generation of pinholes. (See Patent Document 4 above). According to this hot water treatment method, the injected hot water softens the corners and needle-like protrusions of the culture medium base material, so that it is possible to suppress the occurrence of pinholes in the cultivation bag and prevent the invasion of germs. can. However, the hot water treatment method for the mushroom bed medium substrate described in Patent Document 4 adds one more step to the normal mushroom cultivation step, and requires a hot water treatment device for that purpose, resulting in capital investment. There are problems such as becoming indispensable and troublesome management of the cultivation process.

Further, in the hot water treatment method described in Patent Document 4, the generation of pinholes is suppressed by the hot water treatment of the medium base material, but on the other hand, until now, the cultivation bag itself has needle-like protrusions on the medium base material. It was not possible to suppress the occurrence of pinholes due to the corners and corners. That is, the conventional cultivation bags have been discarded as losses, giving up as unavoidable and unavoidable if pinholes occur during filling of the medium. However, if the number of the loss bags increases, waste of resources and troublesome waste will be generated, so countermeasures are required. Further, since pinholes often occur not only in the bagging of the medium but also in the heat-sealed portion of the bag body, it is required to suppress the occurrence of pinholes in the cultivation bag including these.

The present inventors use a film having a blow ratio within a predetermined range because the tensile strength differs between the vertical direction and the horizontal direction depending on the blow ratio and the tensile speed in the inflation film manufacturing apparatus for the plastic film by the inflation method. Further, by providing a portion where the heat welding seal portion and the inner end of the gusset portion intersect within a predetermined angle range between the vertical and horizontal directions of this film, the heat welding at the intersection becomes firm and in the manufacturing process. The product defect rate is significantly reduced, and it is verified that it can be used as a bag for mushroom cultivation and such a cultivation environment. Furthermore, by using a plastic film thicker than the conventional thickness, the medium is used in the cultivation bag itself. The present invention was completed with the idea that pinholes that tend to occur during packing can be suppressed.

An object of the present invention is an object of the prior art, that is, when a large amount of material is contained in a bag, a cross-sealed portion intersecting the inner end of the gusset portion in the heat-welded seal portion receives a strong traction force from the surroundings. It eliminates pinpoint hole opening and damage, and also reliably prevents water leakage, allowing it to be used for moist materials such as mushroom cultivation and in such cultivation environments. Further, the present invention is to provide a plastic film bag with a gusset that can significantly reduce the product defect rate in the manufacturing process.

Another object of the present invention is to provide a plastic film bag with a gusset that makes it difficult for pinholes to occur in the bag body during the mushroom cultivation step, particularly in the bagging step of the culture medium.

In order to solve the above problems, the plastic film bag with a gusset according to the first aspect of the present invention has front and back films of a predetermined size and shape, and left and right side films connecting the front and back films. Then, heat welding is performed by heat-welding an opening that is widened in a substantially square shape at the upper top, a folding portion in which the side film is folded inward to a predetermined depth, and an opening at the lower bottom that faces the opening. It is a bag body made of a plastic film that has a sealing part and is made by the inflation method .
The plastic film is made of an inflation method having a blow ratio in the range of 2.5 to 3.45.
The heat-welded seal portion has a side seal portion extending inward from one side end in a predetermined length substantially parallel to the lower bottom portion, and an inclined side connected to the side seal and inclined substantially linearly toward the lower bottom portion. It has a bent seal portion and a continuous seal portion that connects the pair of bent seal portions .
The inclined side of the bent seal portion and the inner end of the gusset portion of the folded portion intersect, and the intersecting portion is heat-welded.
The inclined side is inclined at an angle θ with respect to the lower bottom portion, and the angle θ is in the range of 20 to 80 ° .

The gusseted plastic film bag of the second aspect is the gusseted plastic film bag of the first aspect, wherein the bent seal portion is formed in a shape bent into a mortar cross-sectional shape in a front view. And.

The gusseted plastic film bag of the third aspect is the gusseted plastic film bag of the first or second aspect, in which a sub-side seal portion is provided on the lower bottom side at a predetermined distance from the heat-welded seal portion . It is characterized by being.

The gusseted plastic film bag of the fourth aspect is the gusseted plastic film bag of any one of the first to third aspects, and the bag body has a filter attached to at least one film surface of the front and back film surfaces. It is characterized by that.

The gusseted plastic film bag according to the fifth aspect is the gusseted plastic film bag according to any one of the first to fourth aspects, wherein the plastic film has a thickness of 60 μm or more.

The gusseted plastic film bag according to the sixth aspect is the gusseted plastic film bag according to any one of the first to fifth aspects, wherein the plastic film is a polyethylene film.

The plastic film bag with a gusset according to the first aspect of the present invention is made of a plastic film bag having a blow ratio in the range of 2.5 to 3.45, and the heat-welded seal portion has a predetermined length from one side end to the inside. It has an extended side seal portion and a bent seal portion that is connected to the side seal and has an inclined side inclined toward the lower bottom side, and the inclined side of the bent seal portion and the inner end of the gusset portion of the folded portion intersect. However, since this intersecting portion is heat-welded, a problem of the prior art, that is, when a large amount of contained material is contained in the bag body, the cross-sealed portion intersecting the inner end of the gusset portion in the heat-welded seal portion becomes. Eliminates pinpoint holes and damage caused by strong traction from the surroundings, and also reliably prevents water leakage to contain moist containers such as mushroom cultivation and such cultivation. It is possible to provide a plastic film bag with a gusset that can be used in an environment and can significantly reduce the product defect rate in the manufacturing process.
Further, the inclined side is inclined at an angle θ with respect to the lower bottom portion, and since this angle θ is in the range of 20 to 80 °, the tensile strength of the cross-sealed portion on the inclined side can be increased.

In the plastic film bag with a gusset of the second aspect, since the bent seal portion is formed in a shape bent into a mortar cross-sectional shape when viewed from the front, the cross-seal portion can be easily formed.

The gusseted plastic film bag of the third aspect is provided with a sub-side seal portion on the lower bottom side at a predetermined distance from the heat-welded seal portion , so that the seal strength on the lower bottom portion side is increased.

The gusseted plastic film bag of the fourth aspect can be used for mushroom cultivation because the bag body has a filter attached to at least one film surface of the front and back film surfaces.

The plastic film bag with a gusset according to the fifth aspect is less likely to cause pinholes in the bag body during the mushroom cultivation step, particularly in the bagging step of the medium. Further, even if a large amount of medium is stored in the bag body and the cross-seal portion intersecting the inner end of the gusset in the heat-welded seal portion receives a strong traction force from the surroundings, pinholes, rupture, and water leakage can be reliably prevented. The thickness of the plastic film is preferably 70 μm or less from the viewpoint of ensuring flexibility and economy.

Since the gusseted plastic film bag of the sixth aspect is a polyethylene film, the bag can be manufactured at low cost.

A plastic film bag with a gusset according to the first embodiment of the present invention is shown, FIG. 1A is a front view, FIG. 1B is a schematic plan view of a top opening, and FIG. 1C is a schematic bottom view of a bottom. FIG. 2A is a schematic diagram of an inflation film manufacturing apparatus, FIG. 2B is a graph showing the relationship between the blow ratio and the tensile strength, and FIG. 2C is a graph showing the relationship between the take-up speed and the tensile strength. It is a top view of a part of a plastic film. It is an enlarged front view of the IV part of FIG. 5A is a front view of the bag of FIG. 1 filled with water, and FIG. 5B is a cross-sectional view taken along the line VV of FIG. 5A. 6A and 6B show a plastic film bag with a gusset according to the second embodiment of the present invention, FIG. 6A shows a front view, FIG. 6B shows a plastic film bag with a gusset according to a modified example, and FIG. 6A is a front view. 7A and 7B show a plastic film bag with a gusset according to the third embodiment of the present invention, FIG. 7A is a front view, FIG. 7B is a schematic plan view of a top opening, and FIG. 7C is a schematic bottom view of a bottom. FIG. 8A is a front view of the gusseted plastic film bag according to the fourth embodiment of the present invention, and FIG. 8B is a front view of the gusseted plastic film bag according to the fifth embodiment of the present invention. 9A and 9B show a plastic film bag body of the prior art, FIG. 9A is a perspective view, FIG. 9B is a perspective view of another embodiment, and FIG. 9C is a partially enlarged view of a state in which an object is put in the bag body of FIG. 9B. Is.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below exemplify a plastic film bag with a gusset for embodying the technical idea of the present invention, and are not intended to specify the present invention. It is equally applicable to those of other embodiments included in the scope of.

[Embodiment 1]
An outline of the plastic film bag with a gusset according to the first embodiment of the present invention will be described with reference to FIG. 1A and 1B show a plastic film bag with a gusset according to the first embodiment of the present invention, FIG. 1A is a front view, FIG. 1B is a schematic plan view of a top opening, and FIG. 1C is a schematic bottom view of a bottom.

The gusseted plastic film bag 10 according to the embodiment of the present invention has an opening 13 that is widened in a substantially square shape at the upper top and a fold-down portion that is folded inward to both sides below the opening to a predetermined depth. It consists of 12a and 12a, and a bag body 100 having a heat-welded seal portion 16 in which an opening facing the opening 13 is hot- _welded on the lower bottom side, and this bag body is a plastic manufactured by an inflation method. It is made of film ₁₁₀ .

The plastic film ₁₁₀ is manufactured in an inflation film manufacturing apparatus by an inflation method with a blow ratio within a predetermined range.

Further, the heat-welded seal portion 16 has a side seal portion 16a extending inward from one side end by a predetermined length and an inclined side 16 ₁ connected to the side seal portion and bent toward the lower bottom portion (see FIG. 4). It is formed by a bent seal portion 16b, an intermediate seal portion 16c having a predetermined length, a bent seal portion 16b, and a side seal portion 16a on the other end side. The inclined side 161 of each of the bent seal portions 16b and 16b is inclined at _a predetermined angle θ (see FIG. 4) with respect to the lower bottom side. These inclined sides 16 ₁ intersect with the inner ends 12a'and 12a' of the gusset portions of the folded portions 12a and 12a, and these intersecting portions are heat-welded. In the following description, this heat-welded intersection is referred to as an intersection seal, and the range of blow ratio and angle θ will be described later.

According to the plastic film bag 10 with a gusset, when a large amount of objects are contained in the bag body 100, the film heat-welded portion, that is, the cross-sealed portion _O in the portion where the number of film layers changes during use is from the surroundings. It is possible to prevent pinpoint holes (pinholes) from opening or being damaged even when the film is pulled. In particular, even when a product containing water is contained, water does not leak, making it suitable as household waste or a mushroom cultivation bag.

Hereinafter, the details of the gusseted plastic film bag 10 will be described. The bag body ₁₀₀ is manufactured by using a tubular tube manufactured by an inflation method.

First, with reference to FIG. 2, a film manufacturing apparatus by an inflation method will be described. 2A is a schematic view of the inflation film manufacturing apparatus, FIG. 2B is a graph showing the relationship between the blow ratio and the tensile strength, and FIG. 2C is a graph showing the relationship between the take-up speed and the tensile strength.

The inflation film manufacturing apparatus 20 includes an extruder 21 that extrudes the molten resin into a cylindrical tube by a circular die 22, and an air ring 23 that blows compressed air into the extruded tube and gradually expands it to a predetermined width. It is composed of a cooler 24 for cooling the film and a winder 26 for sandwiching and winding the film in the nipple roll 25.

In this film manufacturing equipment, the film thickness is determined by the elongation of the film in the take-up direction and the elongation due to the lateral expansion, and the vertical and horizontal strength is the ratio of the nozzle diameter of the die to the diameter of the cylindrical tube. (Hereinafter referred to as blow ratio). Therefore, in the present invention, the plastic film ₁₁₀ is manufactured by setting this blow ratio within a predetermined range. The film material is polyethylene, which is particularly effective among heat-softening plastics.

The film produced by the inflation film manufacturing apparatus 20 has the following characteristics. That is, with reference to FIGS. 2B and 2C, the tensile strength in the vertical direction "A" and the horizontal direction "B" has a large difference between the two when the blow ratio is small in relation to the blow ratio, and the blow ratio is large. The difference becomes smaller as the speed increases (see FIG. 2B), the difference becomes smaller when the speed is slower, and the difference becomes larger as the speed increases (see FIG. 2C).

The tensile strength was verified using a film having these characteristics. Note that FIG. 3 is a plan view of a part of the plastic film. In the plastic film 110, film pieces were cut out in the vertical and horizontal directions and diagonal directions with predetermined widths and lengths to prepare a plurality of vertical film pieces _{11 1} , diagonal film pieces ₁₁₂₂ , and horizontal film pieces 113 _, respectively. _The diagonal film piece 112 is inclined by approximately 60 ° with respect to the horizontal direction.

When these film pieces 11 ₁ to 11 ₃ were pulled from both ends in the length direction, the vertical film pieces 11 ₁ were difficult to cut even if they were stretched long, and the horizontal film pieces 11 ₃ were cut without being stretched long. _On the other hand, the diagonal film piece 112 was long and difficult to cut. The diagonal film piece was longer and harder to stretch than the vertical film piece. The reason is considered to be that the molecules of the vertical film piece are completely extended in the pulling direction in the manufacturing process. From these verifications, it was found that the film produced by the inflation method has high tensile strength in the diagonal direction.

The blow ratio in the inflation film manufacturing apparatus 20 is in the range of 2.5 to 3.45. If this blow ratio is less than 2.5, the rate of water leakage and rupture will increase, so it cannot be used for mushroom cultivation, and if it exceeds 3.45, water leakage and rupture will occur as well. The rate will be high.

Next, the bag body will be described with reference to FIGS. 1, 4, and 5. 1A and 1B show a plastic film bag with a gusset according to the first embodiment of the present invention, FIG. 1A is a front view, FIG. 1B is a schematic plan view of a top opening, FIG. 1C is a schematic bottom view of a bottom, and FIG. 1 is an enlarged front view of the IV portion, FIG. 5A is a front view of a bag filled with water in FIG. 1, and FIG. 5B is a cross-sectional view taken along the line VV of FIG. 5A.

The bag body ₁₀₀ is manufactured by cutting a tubular tube manufactured by an inflation method to a predetermined length. As shown in FIG. ₁ , the bag body 100 has front and back films 11a and 11b having predetermined sizes, and left and right side films connecting the front and back films, and has a substantially square shape on the upper top. The opening 13 to be widened, a pair of facing folding portions 12a and 12a in which both lower sides from the opening are folded inward to a predetermined depth, respectively, and facing the opening 13 on the lower bottom side. It has a heat-welded seal portion 16 in which the opening is heat-welded, and a space 14 having a predetermined size inside. The heat-welded seal portion 16 has a bent seal portion having an inclined side, and the inclined side intersects the inner ends 12a'and 12a' of the gusset portions of the folded portions 12a and 12a, and the intersecting portions are heat-welded. There is. The thermal welding of this intersection will be described in detail later. Reference numeral 15 is a lower bottom portion of the bag body, which is a cutting edge.

The plastic film material is a heat-softening plastic material, for example, a polyethylene film. The dimensions of the bag are, for example, 44 cm in height H, 20 cm in width W, 6.3 cm in W ₁ , 0.5 cm in H ₁ , and 50 μm in film thickness.

The heat-welded seal portion 16 includes a side seal portion 16a extending _inward from one side end of the bag body 100 by a predetermined length, a bent seal portion 16b extending from the side seal portion and bent into a predetermined shape, and the bent seal portion 16b. It has an intermediate seal portion 16c, a bent seal portion 16b, and a side seal portion 16a on the other end side, which are connected to the bent seal portion and extend to the other end side, and these seal portions are continuous. The intermediate seal portion 16c may be omitted and connected at the bottom side described later.

This heat welding seal portion is formed by an elevating heat seal device using a heat seal bar having a predetermined shape provided with a bar forming two bent seal portions. The bar is composed of upper and lower heat bars that abut on the front and back surfaces, and the seal width t is, for example, 1.5 to 2.5 mm. The two bent seal portions 16b and 16b have the same shape.

One bent seal portion 16b will be described with reference to FIG. The bent seal portion 16b has an inclined side 16 ₁ diagonally descending from the side seal 16a toward the lower bottom side, a bottom side 162 having a predetermined length, and the other inclined side 16 facing _{one inclined side 16 1 .} It is composed of ₃ and is formed by bending it into a mortar cross-sectional shape when viewed from the front. The cross-sectional shape of the mortar in front view represents the shape of the cut surface of the mortar cut in the vertical direction. _The inclined side 16 ₁ is inclined at a predetermined angle θ with the extension line of the bottom side 162. The bottom side ₂ is substantially parallel to the lower bottom side 15. Each inclined side 16 ₁ intersects with the inner end 12a'of the gusset portion of the folding portion 12a, and both are heat-welded at this intersection.

The cross-seal portion is indicated by the symbol O in FIGS. 1A, 4 and 5. The cross-sealed portion O is a heat-welded portion on which _a film of the inner end 12a'of the gusset portion of the folded portion 12a and the inclined side 161 is superimposed. That is, the cross-seal portion O is located on the inclined side 161 and is heat-welded in four layers by four films on which the front and back films 11a and 11b and the inner end _12a'of the gusset portion are superimposed. There is. The width W ₁ in FIG. 1C is a width in which four films are laminated. Further, the bottom side 162 and the other inclined side 163 _are heat-welded by _two -layer lamination of the front and back films 11a and 11b.

The inclination angle θ is set in relation to the difficulty of forming the cross-seal portion and the tensile strength within the range of more than 0 ° and less than 90 °. When the inclination angle θ is set to 90 °, it seems that the welded points between the inclined side 161 and the inner end _12a'of the gusset portion are welded in a multi-point or linear shape, but in reality, the welded points are multi-point or linear. Welding is uneven and uneven, and welding defects tend to occur, making it easy to peel off. Further, when the inclination angle θ is set to 0 °, the tensile strength in the horizontal direction of the film produced by the inflation method is weaker than that in the vertical direction, so that there is a risk that pinpoint holes may be opened or damaged at the cross-sealed portion ( Issues of the above-mentioned prior art). Further, except for these angles 0 ° and 90 °, even if the inclination angle θ is close to 90 ° even if it is within the range of more than 0 ° and less than 90 °, the inclined side 16 ₁ becomes steep and the inclined side 16 ₁ The horizontal spacing L at which the above is formed becomes shorter, and it becomes difficult to form the cross-seal portion. Furthermore, when the inclination angle θ is brought close to 0 °, the film strength is weakened, and there is a risk that pinpoint holes may be opened or damaged at the cross-sealed portion.

From these examination results, in the present invention, the range of the inclination angle θ is 20 ° to 80 °, and the optimum range within this range is preferably 40 ° to 70 °. The dimensions of the bent seal portion shown in FIG. 4 are, for example, a seal width t of 1.5 to 2.5 mm, a height a of 4 to 6 mm, and a width b of 15 to 25 mm.

The two bent seal portions 16b and 16b shown in FIG. 1A have the same shape, but the positions of the cross seal portions are different on the left and right sides of the figure. That is, the heat welding location is the inclined side 161 on the left side of the figure and the inclined side _{163 on} the right side of the figure.

A pressure resistance test of this bag was carried out.
(C) Test method-Bag body to be tested 100 Bag body of Embodiment ₁
The dimensions were illustrated in the bag body 100, and the blow ratio of the frothing film manufacturing apparatus was _3.0 , the inclination angle was θ45 °, the bar temperature of the heat sealing apparatus was 250 ° C., and the number of pieces was 10.
・ 2 liters of water at 4 ° C. was put into each of the 10 bags, and the upper opening was tightly tied and sealed.
・ These bags were placed on a scale and compressed with a drilling machine.
-The weight applied to the scale when compressed was measured.
・ The weight at which water leaked from the bag was measured.

(D) Test results-The average weight of 10 water leaks was 73.2 kg. Also, nothing was destroyed.
-The bag body of the prior art leaked at 9.6 kg.

(E) Evaluation-The bag body 100 weighed _73.2 kg and leaked, but since the conventional bag body for mushroom cultivation is approximately 10 _kg or less, this bag body 100 is more than 7 times that. The safety level of water leakage is much higher, and the defective rate of the product has decreased.
-This bag has a higher damage load than the conventional bag, the safety of water leakage is improved, and the defective rate of the heat welding seal can be significantly reduced. That is, the heat welding seal is carried out, for example, in the range of the film welding temperature of 250 ° ± 10 °, but the heat welding seal at this time is affected by the temperature of the season and the like, and may cause poor welding. However, since the damage load is higher than that of the bag body of the prior art, the defect rate can be significantly reduced.
-In addition, the pressure resistance of the bag body to which the sub heat welding seal part is added has a higher pressure resistance.

From the above, this bag body does not leak under normal usage conditions even if it contains water-containing items, making it ideal as a mushroom cultivation bag, and can be used for other bags, such as household waste. However, there is no water leakage and it can be used with confidence.

[Embodiment 2]
The gusseted plastic film bag according to the second embodiment of the present invention will be described with reference to FIG. 6A shows a plastic film bag with a gusset according to the second embodiment of the present invention, FIG. 6A shows a front view, FIG. 6B shows a plastic film bag with a gusset according to a modified example, and FIG. 6A is a front view.

The gusseted plastic film bag 10A according to the second embodiment of the present invention is provided with the heat-welded seal portion 16 provided on the bag body 100 of the _gusseted plastic film bag 10 of the first embodiment, and further, a sub-heat-welded seal portion ( Hereinafter, it is also referred to as a sub-seal portion.) 17 is added. Hereinafter, the same reference numerals are given to the configurations common to the plastic film bag 10, and the description thereof will be incorporated and omitted, and the different configurations will be described in detail below.

The gusseted plastic film bag 10A according to the second embodiment has a sub-seal portion 17 attached below each side seal portion 16a, 16a of the heat-welded seal portion 16 at a predetermined distance. By attaching the sub-seal portion 17, the height H ₁₁ is slightly higher than that of H ₁ .
By arranging each sub-seal portion 17 in each side seal portion 16a, the seal strength on the lower bottom portion side is increased. On the other hand, the positioning and formation of the heat welding seal portion 16 becomes easy.

In this bag 10A, each sub-seal portion 17 is provided side by side with each side seal portion 16a, but the sub-seal portion 17'may be provided over the entire width of the lower bottom portion. As a result, the sub-seal portion 17'is annexed to each side seal portion, the bent seal portion, and the intermediate seal portion, so that the seal strength on the lower bottom portion side is further increased.

[Embodiment 3]
The gusseted plastic film bag according to the third embodiment of the present invention will be described with reference to FIG. 7. 7A and 7B show a plastic film bag with a gusset according to the third embodiment of the present invention, FIG. 7A is a front view, FIG. 7B is a schematic plan view of a top opening, and FIG. 7C is a schematic bottom view of a bottom.

The gusseted plastic film bag 10B according to the third embodiment of the present invention is a miniaturized version of the two bent seal portions provided on the bag body 100 of the _gusseted plastic film bag 10 of the first embodiment. be. Due to this miniaturization, the bag body 100 of the _{first embodiment, the height H, and the widths W and W 1 are} lowered and shortened. Further, the bag 10B may be provided with sub heat welding seal portions 17, 17'attached to the bag 10A.

[Embodiments 3 and 4]
The gusseted plastic film bag according to the third and fourth embodiments of the present invention will be described with reference to FIG. 8A is a front view of the gusseted plastic film bag according to the third embodiment of the present invention, and FIG. 8B is a front view of the gusseted plastic film bag according to the fourth embodiment of the present invention.

The gusseted plastic film bags 10C and 10D according to the third and fourth embodiments of the present invention are the bag bodies of the gusseted plastic film bags 10 and 10B of the first and third embodiments, and the filter F is applied to at least one of the front and back films. Is attached. That is, the filter is mounted by perforating a ventilation hole in the film and covering it, and the ventilation hole may be any of the front and back films, and the ventilation hole may be provided in at least one of the films. A filter is attached to each of these ventilation holes. In addition, the size and shape of the filter and the ventilation holes are appropriately determined according to the size of the bag body.

By attaching the filter F, the bags 10C and 10D can be used for mushroom cultivation. That is, as described above, all of these bags 10C and 10D have a breaking load of 7 times or more that of the conventional mushroom cultivation bag, and mechanical shock, high temperature, or high temperature in the above-mentioned fungal bed shiitake cultivation step. It can withstand harsh cultivation environments such as water immersion and long periods. Further, these bags may be provided with sub heat welding seal portions 17, 17'attached to the bag 10A.

[Embodiment 5]
The gusseted plastic film bag according to the fifth embodiment of the present invention is different in that the gusseted plastic film bags of the third and fourth embodiments are made of plastic films having different thicknesses. In the following description, the drawings of the gusseted plastic film bags of the third and fourth embodiments are used as they are, and different configurations, that is, bags having different film thicknesses will be described.

The gusseted plastic film bag according to the fifth embodiment has a thickness of the plastic film of more than 50 μm, preferably 55 μm or more, and more preferably 60 μm or more. The range of the blow ratio is the same range of 2.5 to _3.45 as that of the bag body 100. The gusseted plastic film bags of the third and fourth embodiments are tested with a film thickness of 50 μm.

The breakage load of the heat welded seal is related to the film thickness. That is, as the thickness of the film is increased, the temperature of the heat bar in the heat sealing device must be increased and the heat time must be increased accordingly. For example, at a thickness of 40 μm, the heat time (timer) is 0.5 seconds at 250 ° C., similarly, at 55 μm, 260 ° C., 0.6 seconds, at 60 μm, 270 ° C., 0.7 seconds, at 65 μm, 270 ° C., 0.7. At 70 μm per second, the heat temperature and time slightly increase to 280 ° C. and 0.75 seconds. Nevertheless, all of these bags can achieve a breakage load of 30 kg or more.

As described in the bag body of the first embodiment, the gusseted plastic film bags of the third and fourth embodiments achieved 73.2 kg in the pressure resistance test, and the conventional bag body for mushroom cultivation was about 10 kg or less. Since it is more than 7 times as thick as the film, even if the film thickness is increased, the heat welding seal can be performed without raising the temperature of the heat bar of the heat sealing device so much and the heat time is not lengthened, and the film is thick. Therefore, the occurrence of pinholes due to medium filling can be significantly reduced.

Therefore, the gusseted plastic film bag and the bag body according to the fifth embodiment are made of a plastic film, and the thickness thereof is thicker than the thickness of the conventional plastic film (generally 50 μm or less), and is in the range of 60 μm or more. Since the blow ratio is in the range of 2.5 to 3.45, it becomes difficult for pinholes to occur in the bag during the mushroom cultivation process, especially in the bagging process of the medium, and as a result, the pinholes are formed. Outbreaks are much less than in conventional cultivation bags. Of course, even if a large amount of medium is stored in the bag and the cross-seal portion intersecting the inner end of the gusset in the heat-welded seal portion receives a strong traction force from the surroundings, pinholes, rupture, and water leakage can be reliably prevented. The thickness of the plastic film is preferably 70 μm or less in consideration of flexibility and economy.

10, 10A, 10B, 10C, 10D Plastic film bag with gusset _{100 Bag body 110 Inflation film 11 1 to} 11 ₃ Film piece 11a Front film 11b Back film 12a Folded part _12a'Machi part inner end 13 Opening part 15 Lower bottom Part 16 Heat-welded seal part 16a Side seal part 16b Folded seal part 16c Intermediate seal part 16 ₁ Inclined side 16 ₂ Bottom side 16 ₃ Inclined side 17 Sub-heat welded seal part 20 Inflation film manufacturing equipment O Cross-sealed part F Filter θ Inclined angle

Claims (6)

It has front and back films of a predetermined size and shape, left and right side films connecting these front and back films, an opening that expands in a substantially square shape at the upper top, and the side films are predetermined inward. A bag body made of a plastic film produced by an inflation method, provided with a fold-in portion folded to a depth and a heat-welded seal portion in which an opening facing the opening at the lower bottom is heat-welded.
The plastic film is made of an inflation method having a blow ratio in the range of 2.5 to 3.45.
The heat-welded seal portion has a side seal portion extending inward from one side end in a predetermined length substantially parallel to the lower bottom portion, and an inclined side connected to the side seal and inclined substantially linearly toward the lower bottom portion. It has a bent seal portion and a continuous seal portion that connects the pair of bent seal portions.
The inclined side of the bent seal portion and the inner end of the gusset portion of the folded portion intersect, and the intersecting portion is heat-welded.
A plastic film bag with a gusset, wherein the inclined side is inclined at an angle θ with respect to the lower bottom portion, and the angle θ is in the range of 20 to 80 °. The plastic film bag with a gusset according to claim 1, wherein the bent seal portion is formed in a shape bent into a mortar cross-sectional shape when viewed from the front. The plastic film bag with a gusset according to claim 1 or 2, wherein a sub-side seal portion is provided on the lower bottom side at a predetermined distance from the heat-welded seal portion. The plastic film bag with a gusset according to any one of claims 1 to 3, wherein the bag body has a filter mounted on at least one film surface of the front and back film surfaces. The plastic film bag with a gusset according to any one of claims 1 to 4, wherein the plastic film has a thickness of 60 μm or more. The gusseted plastic film bag according to any one of claims 1 to 5, wherein the plastic film is a polyethylene film.

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