CHECK VALVE, SEALING BAG, AND PRODUCTION METHODS FOR BOTH

FIELD OF THE ART

The present invention relates to a check valve, a sealing bag that includes the check valve, a method for producing the check valve, and a method for producing the sealing bag.

From before, there have been sealing bags with which an article containing portion that includes a space for containing clothing, food, or other article can be sealed in a gastight state. With such a sealing bag, a check valve connecting the article containing portion and an outside of a bag in a ventable manner is used to evacuate air and various other gases present in the article containing portion to the outside of the bag and maintain the evacuated state.

In the evacuation of gas, the check valve can allow passage of gas flow in one direction while blocking gas flow in another direction by opening and closing of a gas flow passage space that is a space through which the gas passes.

A conventional example of a check valve includes a check valve described in Patent Document 1. As shown in FIG. 10, with this check valve 100, respective lower edges of a plastic film 101 of rectangular shape and a shorter filtering film 102 of the same width are overlapped, and lower edges of plastic films 103 and 104 are overlapped with an upper edge of the filtering film 102 and further overlapped with one surface of the plastic film 101 to form a flat laminate, and both side edges and a lower edge of the laminate are adhered by heating. The upper edge of the filtering film 102 and a lower edge overlapped portion 100a of the plastic films 103 and 104 are then adhered by heating to form a gas release flow path 108 with respect to the plastic film 103 while providing an opening portion 106 at an upper end and providing a filtering surface 107 made of the filtering film 102 at one surface of a lower portion. A checking piece 103a is then formed with the plastic film 103, an actuating pocket portion 109 therefor is provided, and a low-viscosity inert liquid is coated onto an upper inner surface of the plastic film 101 or an inner surface of the check valve 103 to maintain close contact of the film surfaces.

PRIOR ART DOCUMENT
Patent Document

Patent Document 1: Japanese Published Unexamined Patent Application No. H9-112721

SUMMARY OF THE INVENTION
Objects of the Invention

However, with the check valve 100 of the conventional example described above, only a single checking piece 103a is provided, and a gas flow in a reverse direction is blocked by close contact of the plastic film 101 and the checking piece 103a. That is, the close contact is achieved only at a single location and certainty of the checking effect is thus lacking. Coating of the low-viscosity inert liquid was thus essential for improving the checking effect in the invention according to Patent Document 1.

Also obvious in improving the above, a structure must be arranged that would prevent increase of the production cost of the check valve as much as possible.

Also, as a desirable function of a check valve, minimizing of “initial pressure,” which is gas pressure inside a sealing bag at an instant at which evacuation is started, can be cited. This is because when the “initial pressure” is high, evacuation is not started readily and large external force must be applied to the sealing bag or gas may remain inside the bag without being evacuated readily so that the sealing bag swells in a clumsy manner.

The present invention has been made in view of the above and an object thereof is to provide a check valve that is improved in certainty of the checking effect, is prevented as much as possible from increasing in the production cost, and is small in “initial pressure,” and to provide a sealing bag that includes the check valve and methods for producing the check valve and the sealing bag.

Means for Achieving the Object

To achieve the above object, an aspect of the present invention according to claim 1 provides a check valve formed by overlapping a plurality of sheets, having a gas flow passage space 3a, which is a space through which gas passes, formed between the sheets, and being capable of allowing passage of gas flow in a positive direction from an inlet to an outlet and blocking gas flow in a reverse direction from the outlet to the inlet by opening and closing of the gas flow passage space, wherein the check valve is comprised of a plurality of base sheets 31 and 32 made of resin, and a plurality of flexible valve body sheets 4 made of resin;

- the plurality of base sheets 31 and 32 being disposed to face each other in a front/back direction,
- at least two sheets of the plurality of valve body sheets 4 forming a single set comprising an upstream valve body sheet 4a disposed at an upstream side and a downstream valve body sheet 4b disposed at a downstream side on a basis of the positive gas flow direction,
- each of the valve body sheets 4a and 4b that forms the single set being adhered to at least one base sheet 31,
- the adhesion being achieved so that the respective valve body sheets 4a and 4b are aligned in series in a gas flow direction during evacuation and so as not to be overlapped in the front/back direction,
- the adhesion of the upstream valve body sheet 4a to the one base sheet 31 being achieved at an upstream end 4a1 side with a downstream end 4a2 side being made movable with respect to the base sheets 31 and 32,
- the adhesion of the downstream valve body sheet 4b being achieved at a downstream end 4b2 side with an upstream end 4b1 side being movable with respect to one base sheets 31 and 32, and
- at least a portion of the single set of valve body sheets 4a and 4b being capable of contacting closely and separating with respect to another base sheet 32 or with respect to a valve body sheet 91 different from the single set of valve body sheets 4a and 4b and disposed on the opposite side of the one base sheet 31 across the single set of valve body sheets 4a and 4b, thereby allowing passage of gas flow in the positive direction and block gas flow in the reverse direction.

An aspect of the present invention according to claim 2 provides the check valve according to claim 1, wherein

- a portion of the one base sheet 31 is arranged as a gas flow passage portion 31a having gas permeability of allowing gas flow in the positive direction to pass through in the front/back direction,
- the gas flow passage portion 31a being an inlet through which the gas flow in the positive direction flows into the check valve, and
- the gas flow passage portion 31a being disposed at a position of the one base sheet 31 that is further upstream than a position matching the upstream end 4a1 of the upstream valve body sheet 4a in the front/back direction.

An aspect of the present invention according to claim 3 provides the check valve according to claim 2, wherein

- the one base sheet 31 comprises the gas flow passage portion 31a and another portion, the another portion having gastightness.

An aspect of the present invention according to claim 4 provides the check valve according to claim 1, wherein the outlet 32b through which gas flow in the positive direction flows out from the inside of the check valve is disposed at other exterior sheet 32 side,

- the outlet 32b being formed by making the other exterior sheet 32 smaller than the one exterior sheet 31 or by providing
- an opening in the other exterior sheet 32, and the outlet 32b being disposed at a position of the one base sheet 31 that is further downstream than a position matching the downstream end 4a2 of the upstream valve body sheet 4a in the front/back direction.

An aspect of the present invention according to claim 5 provides the check valve according to claim 4, wherein

- bent seals s4 and s5 are formed between the inlet 31a and the inlet 31a,
- the bent seals s4 and s5 being adhesion of the one base sheet 31, the valve body sheets 4, and the other base sheet 32 in the front/back direction, and
- the bent seals s4 and s5 shaping bent so that a flow path inside the check valve V from the inlet 31a to the inlet 31a becomes a zigzagging flow path in a plan view of the sheets.

An aspect of the present invention according to claim 6 provides the check valve according to claim 5, wherein

- a silicone liquid or other inert substance 8 is disposed inside a flow path, defined by the bent seals s4 and s5, between the valve body sheets 4 and the other base sheet 32.

An aspect of the present invention according to claim 7 provides the check valve according to claim 1, wherein

- the one base sheet 31 has gas permeability across its entire surface,
- a portion of the gas-permeable one base sheet 31 is arranged as a gas flow passage portion 31a through which gas flow in the positive direction passes in the front/back direction,
- the gas flow passage portion 31a being a portion of the one base sheet 31 that is further upstream than a position matching the upstream end 4a1 of the upstream valve body sheet 4a in the front/back direction.

An aspect of the present invention according to claim 8 provides the check valve according to claim 2, wherein

- the gas flow passage portion 31a of the one base sheet 31 is provided with a nonwoven fabric.

An aspect of the present invention according to claim 9 provides the check valve according to claim 1, wherein

- the one base sheet 31 is made of a nonwoven fabric having gas permeability across its entire surface,
- a portion of the gas-permeable one base sheet 31 is arranged as a gas flow passage portion 31a through which gas flow in the positive direction passes in the front/back direction,
- a portion of the one base sheet 31 except the gas flow passage portion 31a abeing covered by a covering sheet 92 having gastightness.

An aspect of the present invention according to claim 10 provides the check valve according to claim 1, wherein the check valve is used by being fixed to a sealing bag 1 having an article containing portion 2, the article containing portion 2 being capable of ventilation to the outside of the bag to evacuate gas present in the article containing portion 2 to the outside of the bag.

An aspect of the present invention according to claim 11 provides a sealing bag 1 having the check valve V according to claim 4 fixed thereto,

- wherein the sealing bag 1 is comprised of a flexible bag sheets 11 and 12 made of resin,
- the bag sheets 11 and 12 being adhered so that a portion except an article receiving opening 1a and a portion to which the check valve V is fixed is separated in a gastight manner from the outside of the bag, and
- a whole perimeter of the check valve V is adhered to an inner side or an outer side of the bag sheets 11 and 12.

An aspect of the present invention according to claim 12 provides a sealing bag 1 having the check valve V according to claim 7 fixed thereto,

- wherein the sealing bag 1 is comprised of a flexible bag sheets 11 and 12 made of resin,
- the bag sheets 11 and 12 being adhered so that a portion except an article receiving opening 1a and a portion to which the check valve V is fixed is separated in a gastight manner from the outside of the bag,
- the check valve V, sandwiched by the bag sheets 11 and 12, having an upstream end positioned inside the article containing portion 2 and a downstream end positioned outside the article containing portion 2 on a basis of a gas flow direction during evacuation,
- a portion at an upstream end side of the other base sheet 32 of the check valve V being adhered to a surface of the bag sheets 11 and 12 that is an inner surface facing the other base sheet 32,
- a gas flow passage portion 31a of the one base sheet 31 of the check valve V being exposed to a space in the article containing portion 2 that is capable of containing an article,
- a lateral direction seal 13 being formed by adhesion of the bag sheets 11 and 12,
- the lateral direction seal 13 being formed to traverse the check valve V in a width direction,
- a longitudinal direction seal 14 being formed additionally by the adhesion of the bag sheets 11 and 12,
- the longitudinal direction seal 14 being in a direction intersecting the lateral direction seal 13 and extended more to the upstream side than the lateral direction seal 14 on a basis of a gas flow direction during evacuation inside the check valve V,
- the longitudinal direction seal 14 being provided sandwiching the check valve V and being spaced by an interval wider than a width dimension of the check valve V to form a single set by two, and
- an upstream end 141 of the longitudinal direction seal 14 being positioned further upstream, on a basis of the gas flow direction during evacuation inside the check valve V, than a lower end 31a1 of a portion, of the gas flow passage portion 31a in the one base sheet 31, which is defined by the lateral direction seal 13 and through which air practically flows.

An aspect of the present invention according to claim 13 provides a method for producing the check valve according to claim 1, wherein elongate sheets supplied continuously in a longitudinal direction are used as the base sheets 31 and 32 and the valve body sheets 4, and

- the respective valve body sheets 4a and 4b forming a single set are supplied as a single elongate sheet that is thereafter cut in two in a width direction and overlapped with the one base sheet 31.

An aspect of the present invention according to claim 12 provides a method for producing a sealing bag 1 having a check valve V fixed thereto,

- wherein the check valve V is comprised of flexible base sheets 31 and 32 made of resin; and a plurality of valve body sheets 4,
- one base sheet 31 of the base sheets 31 and 32 has gas permeability across its entire surface,
- the base sheets 31 and 32 are disposed to face each other in a front/back direction,
- at least two sheets of the plurality of valve body sheets 4 forming a single set comprising an upstream valve body sheet 4a disposed at an upstream side and a downstream valve body sheet 4b disposed at a downstream side on a basis of a gas flow direction during evacuation,
- each of the valve body sheets 4a and 4b that forms the single set are adhered at least to the one base sheet 31,
- the adhesion is achieved so that the respective valve body sheets 4a and 4b are aligned in series in the gas flow direction during evacuation and so as not to be overlapped in the front/back direction,
- the adhesion of the upstream valve body sheet 4a to the one base sheet 31 is achieved at an upstream end 4a1 side with a downstream end 4a2 side being made movable with respect to the base sheets 31 and 32,
- the adhesion of the downstream valve body sheet 4b is achieved at a downstream end 4b2 side with an upstream end side 4b1 being movable with respect to the base sheets 31 and 32, and
- the respective ends 4a2 and 4b1 of the valve body sheets 4a and 4b that are made movable with respect to the base sheets 31 and 32 are capable of closely contacting the other base sheet 32 or a valve body sheet 4 that is different from the valve body sheets forming the single set and is adhered to the other base sheet 32; and
- a flexible elongate sheet made of resin and supplied continuously in a longitudinal direction is used as bag sheets 11 and 12,
- the method for producing a sealing bag comprising the steps of:
- sandwiching the check valve V by the bag sheet 11 and 12;
- forming a lateral direction seal 13 traversing the check valve V in a width direction by adhesion of the bag sheets 11 and 12; and
- forming a longitudinal direction seal 14 by adhesion of the bag sheets 11 and 12;
- the longitudinal direction seal 14 formed in the steps, being in a direction intersecting the lateral direction seal 13 and extended more to the upstream side on the basis of the gas flow direction during evacuation inside the check valve V than the lateral direction seal 14,
- the longitudinal direction seal 14 being provided sandwiching the check valve V and spaced by an interval wider than a width dimension of the check valve V to form a single set by two, and
- an upstream end 141 of the longitudinal direction seal 14 being positioned further upstream, on a basis of the gas flow direction during evacuation inside the check valve V, than a lower end of a portion 31a1, of the gas flow passage portion 31a in the one base sheet 31, which is defined by the lateral direction seal 13 and through which air practically flows.

Effects(s) of the Invention

The present invention can provide a check valve that is improved in certainty of the checking effect, is prevented as much as possible from increasing in the production cost, and is small in “initial pressure,” and provide a sealing bag that includes the check valve and methods for producing the check valve and the sealing bag.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a check valve according to an embodiment of the present invention with FIG. 1A being a plan view, FIG. 1B being an end view viewed in a direction of arrows X-X in FIG. 1A, and FIG. 1C being a bottom view.

FIG. 2 is a schematic view, with principal portions being exaggerated, of a relationship of another base sheet and valve body sheets in the check valve of the same embodiment and showing a state where a gas flow passage space is closed.

FIG. 3A is a plan view of a sealing bag of the same embodiment and FIG. 3B is a plan view of principal portions of an example where a shape of a longitudinal direction seal in the sealing bag of the same embodiment is changed.

FIG. 4 is a schematic view of a transverse section of a cul-de-sac portion during evacuation in the sealing bag of the same embodiment.

FIG. 5 shows schematic views of a state where the check valve according to the above embodiment is fixed to a sealing bag according to another embodiment of the present invention with FIG. 5A being a perspective of a back surface side of the bag, FIG. 5B being a longitudinal sectional view at the position of the check valve of the back surface side of the bag, and FIG. 5C being a transverse sectional view at the position indicated by arrows Y-Y of FIG. 5B of the back surface side of the bag.

FIG. 6A is a front view of a sealing bag according to another embodiment of the present invention, FIG. 6B is a front view of a sealing bag according to still another embodiment of the present invention, and FIG. 6C is a central longitudinal sectional view of the sealing bag of FIG. 6B.

FIG. 7A is a sectional view of a check valve according to another embodiment of the present invention, FIG. 7B is a plan view of the same check valve, FIG. 7C is a bottom view of the same check valve, FIG. 7D is a structural explanatory diagram of a state where the same check valve is fixed to an inside of a sealing bag, and FIG. 7E is a structural explanatory diagram of a state where the same check valve is fixed to an outside of a sealing bag.

FIG. 8A is a plan view of a check valve according to still another embodiment of the present invention, FIG. 8B is a bottom view of the same check valve, FIG. 8C is a sectional view of the same check valve, FIG. 8D is a structural explanatory diagram of a state where the same check valve is fixed to an inside of a sealing bag, and FIG. 8E is a sectional view of a check valve according to still another embodiment.

FIG. 9A is a sectional view of a check valve according to still another embodiment and FIG. 9B is a sectional view of a check valve according to still another embodiment.

FIG. 10 is a longitudinal sectional view taken along a longitudinal direction of a check valve according to a conventional example.

MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention shall now be described based on the drawings.

Expressions indicating positions and directions, such as “front and back,” “upper, lower, right, and left,” “longitudinal and lateral,” “one and other,” etc., written in the claims and specification of the present invention are used for the sake of description and specification and the applicant has no intention to limit the present invention to modes of the positional relationships as described.

Also, the expressions of “upstream and downstream” are based on a positive direction (direction of gas flow during evacuation along a longitudinal direction of a check valve V) .

A sealing bag 1 according to the present embodiment may be used as a deaeration bag that can be reduced in volume by evacuation of gas present in an article containing portion 2. Examples of specific applications of the deaeration bag include a food pack for food storage (that exert a freshness keeping effect in storage upon lessening of air inside a bag) and a compression bag for clothing (that can be reduced in volume by lessening of air inside a bag) that are used for evacuating the air present in the article containing portion 2. Implementation as a bag containing in the article containing portion 2, for example, coffee beans, powder detergent, or other article that generates gas and enabling evacuation of the gas generated from the article to an outside of a bag to suppress expansion of the bag is also possible.

In order to evacuate the gas present in the article containing portion 2 to the outside of the bag as described above, a check valve V that allows passage between the article containing portion 2 and an outside of a bag is fixed to the sealing bag 1. Although in the present example, a single check valve V is provided per single sealing bag 1, the present invention is not limited thereto and a plurality of check valves V may be provided per single sealing bag 1.

As shown in FIG. 3A, the sealing bag 1 of the present example includes a front bag sheet 11 and a back bag sheet 12 that are made of flexible resin and are overlapped and oriented in a front/back direction, and by the bag sheets 11 and 12 being adhered (heat sealed) together, a portion except an article receiving opening 1a and a portion to which the check valve V is fixed is separated from the outside of the bag in a gastight manner. The check valve V is fixed by being sandwiched by the bag sheets 11 and 12 in the front/back direction. The check valve V may also be sandwiched by only one of the bag sheets 11 and 12 by the one bag sheet between the bag sheets 11 and 12 being folded back, etc. Also, although in the present example, two resin sheets of the same rectangular shape in a plan view are overlapped in the front/back direction as bag sheets 11 and 12, the bag may be provided with a gusset at a side surface and the shape of the bag sheets may be a shape other than a rectangular. Also, a zipper of a known arrangement is provided at the article receiving opening 1a to enable opening and closing in a gastight manner. However, such a zipper enabling opening and closing is unnecessary with a bag that contains coffee beans or a sealing bag of a type that is finally closed by adhesion of the article receiving opening 1a by a heat sealer.

The check valve V allows passage of a gas flow in a positive direction and blocks a gas flow in a suctioning direction by opening and closing of a gas flow passage space 3a that is a space through which a gas passes during evacuation of the gas from the article containing portion 2 of the sealing bag 1.

As shown in FIGS. 1A and 1C, a shape in a plan view (bottom view) of the check valve V of the present example is a rectangular shape that is longer in a longitudinal direction dimension than a width dimension, and the gas flow passes in the longitudinal direction.

The check valve V includes one base sheet 31 and another base sheet 32 that are made of flexible resin and a plurality of valve body sheets 4.

Resin sheets with the same width dimension are used as the base sheets 31 and 32 and these are disposed to face each other in the front/back direction. In regard to the longitudinal direction dimension, the one base sheet 31 is longer than the other base sheet 32 (actions and effects thereof shall be described later). The base sheets 31 and 32 are overlapped in the front/back direction with upstream sides (left end sides in FIG. 1) being aligned.

The valve body sheets 4 are overlapped while being sandwiched by the base sheets 31 and 32. Both edges in the width direction and an upstream side edge in the longitudinal direction of the respective base sheets 31 and 32 are adhered (heat sealed) and closed in a gastight manner. The adhesion at both edges in the width direction is performed on all of the base sheets 31 and 32 and the valve body sheets 4. As shall be described below, in the present example, a nonwoven fabric is used as the one base sheet 31 and thus a gas flow inlet of the check valve V is a gas flow passage portion 31a (described below) of the one base sheet 31. As the nonwoven fabric, that which is without scuffing and is excellent in water resistance and durability, such as a spunbonded nonwoven fabric formed by melting a thermoplastic polymer and ejecting in a continuous, long fibrous form is preferable. Also, by using filaments with a core-sheath structure that uses a fiber with strength, such as polyester, inside and polyethylene, which is comparatively soft and can be subject to heat sealing and other forms of processing, outside, strength and processability can be realized at the same time. The gas flow passage portion 31a is an inlet 31a through which the gas flow in the positive direction flows into the check valve V. On the other hand, an outlet 32b is a downstream end portion in a longitudinal direction of the check valve V (more precisely, a portion between an edge of the other base sheet 32 and the one base sheet 31), wherein gas flow in the positive direction flows out from the check valve V.

In the present example, a point seal 5 is formed at a width direction center of the check valve V as shown in FIG. 1C and the base sheets 31 and 32 and the valve body sheets 4 are adhered thereat. In the present example, the point seal 5 is formed as a short heat seal extending in a longitudinal direction of the check valve V. The point seal 5 is provided for rectifying the gas flow during evacuation but is not essential to the present invention and does not have to be formed.

Among the plurality of valve body sheets 4, at least the two sheets of an upstream valve body sheet 4a disposed at an upstream side and a downstream valve body sheet 4b disposed at a downstream side form a single set.

In the present example, sheets (plastic films) of the same material and thickness are used as the other base sheet 32 and the valve body sheets 4. As the sheets 32 and 4, “self-close-contacting” sheets (films) are used that can readily be closely contacted with counterpart sheets that are facingly disposed. As shall be described below, a nonwoven fabric is used as the one base sheet 31. However, the arrangements of the respective sheets are not limited to those of the present example, and, for example, in a case where the base sheets 31 and 32 are exposed to the outside of the sealing bag 1, the base sheet 32 maybe arranged as a sheet that is thicker than the valve body sheets 4.

Both valve body sheets 4a and 4b forming the single set are adhered to only the one base sheet 31. In a case where three or more valve body sheets 4 are included, a valve body sheet 4 may also be adhered to the other base sheet 32. However, even in this case, adhesion of both of the valve body sheets 4a and 4b forming the single set to at least the one base sheet 31 is an essential condition of the present invention.

The adhesion of the respective valve body sheets 4a and 4b forming the single set to the one base sheet 31 is performed so that the valve body sheets 4a and 4b are disposed in series with respect to the gas flow direction inside the valve during evacuation and so that both valve body sheets do not overlap in the front/back direction.

The adhesion of the upstream valve body sheet 4a to the one base sheet 31 is achieved at an upstream end 4a1 side. The adhered portion is indicated as s1 in FIG. 1B. A downstream end 4a2 side of the upstream valve body sheet 4a is made movable with respect to the base sheets 31 and 32.

Also, the adhesion of the downstream valve body sheet 4b is achieved at a downstream end 4b2 side. The adhered portion is indicated as s2 in FIG. 1B. An upstream end 4b1 side of the downstream valve body sheet 4b is made movable with respect to the base sheets 31 and 32. In the present example, the downstream end 4b2 of the downstream valve body sheet 4b is matched with the downstream end 31b of the one base sheet 31.

That is, by the adhesion of the valve body sheets 4a and 4b being achieved as described above, respective free ends of the valve body sheets 4a and 4b are disposed in a mutually facing manner on the one base sheet 31.

An interval between the valve body sheets 4a and 4b is preferably an extremely small interval made by forming a slit by cutting a single sheet with a cutting blade as described later. By forming such an extremely small interval, a step is not present between the valve body sheets 4a and 4b, and even when a nozzle, etc., is inserted into the deaeration valve V during evacuation, catching of the nozzle, etc., will not occur.

The free ends, that is, the respective ends 4a2 and 4b1 of the valve body sheets 4a and 4b that are made movable with respect to the base sheets 31 and 32 are made closely contactable to the other base sheet 32. When the close contact is not achieved, gaps are formed between the respective valve body sheets 4a and 4b and the other base sheet 32 and the gas flow passage space 3a is open as shown in FIG. 1B.

The other base sheet 32 is flexible and thus when the gas flow passage space 3a is open as described above, the other base sheet 32 is moved to a lower side in FIG. 1B by evacuation pressure. Smooth evacuation without clogging of the gas flow passage space 3a in the middle is thus achieved.

In this process, even if the downstream valve body sheet 4b and the other base sheet 32 happen to be put in a difficult-to-separate state (due to such a cause as dew condensation, etc.), the evacuation is not made difficult because the evacuation gas flow can pass from between the respective ends 4a2 and 4b1 of the valve body sheets 4a and 4b and through an exposed portion 31c (a portion positioned at the outside of the article containing portion 2 when the check valve V is fixed to the sealing bag 1) of the one base sheet 31.

On the other hand, when the article containing portion 2 becomes lower in pressure in comparison to the outside of the bag, negative pressure f arises inside of the check valve V as shown in FIG. 2. The respective valve body sheets 4a and 4b are lifted away from the one base sheet 31 by the negative pressure f. “Self-close-contacting” sheets are used as the other base sheets 32 and the valve body sheets 4a and 4b as described above and thus by the lifting away, the mutually facing sheets become closely contacted reliably. When the close contact is achieved, the gaps between the respective valve body sheets 4a and 4b and the other base sheet 32 are eliminated and the gas flow passage space 3a is closed.

In this process, a gas flow s, tending to flow in reverse through the check valve V from the exposed portion 31c of the one base sheet 31, may flow in as indicated by arrows in FIG. 2. In this case, the respective valve body sheets 4a and 4b are pressed against the other base sheet 32 by the gas flow s tending to flow in reverse and the sheets are closely contacted even more reliably. The gas flow passage space 3a is thus closed even more reliably.

In the present example, the valve body sheets 4a and 4b are respectively closely contacted with the other base sheet 32 as shown in FIG. 2. That is, the close contact is achieved at two locations and certainty of the checking effect is thus improved in comparison to the arrangement of check valve described in Patent Document 1. Coating of a low-viscosity inert liquid is thus not essential as in the invention according to Patent Document 1. An advantage in terms of the production cost of the check valve is thus provided. However, a low-viscosity inert liquid (for example, silicone oil, etc.) may be coated for the purpose of further increasing the certainty of the checking effect.

In a case where a valve body sheet 4 is also adhered to the other base sheet 32, the valve body sheets 4a and 4b are respectively closely contacted with the valve body sheet 4 adhered to the other base sheet 32.

In the present example, the one base sheet 31 to which the valve body sheets 4a and 4b forming the single set are adhered has gas permeability across its entire surface. More specifically, in the present example, the one base sheet 31 having gas permeability is a nonwoven fabric.

A portion of the one base sheet 31 is arranged as the gas flow passage portion 31a through which the gas flow during evacuation passes in the front/back direction. The gas flow passage portion 31a is the portion of the one base sheet 31 that is further upstream than a position matching the upstream end 4a1 of the adhered upstream valve body sheet 4a in the front/back direction.

Although the one base sheet 31 has gas permeability across its entire surface, a valve supporting portion 31b that is a portion overlapped with the respective valve body sheets 4a and 4b in the front/back direction is not a portion through which a gas flows as in the gas flow passage portion 31a in the state where the check valve V is fixed to the sealing bag 1 (however, the gas flow passing between the ends 4a2 and 4b1 of the respective valve body sheets 4a and 4b can pass through as described above).

In the present example, the one base sheet 31 is a nonwoven fabric and thus even at the valve supporting portion 31b, the surface facing the valve body sheets 4a and 4b is a rough surface. Thus, even if the valve body sheets 4a and 4b are “self-close-contacting” sheets as described above, the sheets can detach readily from the one base sheet 31.

Although conventionally to make a valve body sheet detach readily in the above manner, a coating material is coated on the surface of the base sheet facing the valve body sheet, with the arrangement of the one base sheet 31 of the present example, the need to coat a coating material is eliminated. The present arrangement is advantageous in terms of the production cost of the check valve from this aspect as well.

However, it is not essential for the one base sheet 31 to have a gas permeability across its entire surface as in the present example. Only the gas flow passage portion 31a may be made gas permeable by using a sheet having gas permeability only at a portion or by attaching together a sheet with gas permeability and a sheet without gas permeability. Even in such cases, it is preferable, for making the valve body sheets 4a and 4b readily detachable from the one base sheet 31, to form a rough surface at the valve supporting portion 31b by corona discharge treatment, etc.

As described above, the downstream end 4b2 of the downstream valve body sheet 4b in the present example is matched with the downstream end 31b of the one base sheet 31. In the present example, the one base sheet 31 is longer in a longitudinal direction dimension than the other base sheet 32 and the upstream sides of the base sheets 31 and 32 are aligned. Thus, a portion of the downstream valve body sheet 4b that is further downstream than a position matching the downstream end 32a of the other base sheet 32 in the front/back direction is arranged as a non-contacting portion 4b3 that does not overlap with the other base sheet 32 in the front/back direction.

If such a non-contacting portion 4b3 is not provided and the downstream edges of the check valve V are matched in the front/back direction, the arrangement is readily influenced by distortions (waviness) occurring in the sheets and reverse flow due to capillary action occurs readily. The distortion tends to be more significant closer to an edge and thus in the present example, the position at which one sheet is closely contacted with another sheet is shifted so as to avoid an edge, and by arranging the other base sheet 32 and the downstream valve body sheet 4b to contact closely as shown in FIG. 2, the influence of the distortion is reduced. Thus, reverse flow can also be prevented effectively by providing the non-contacting portion 4b3.

The check valve V arranged as described above has an upstream end positioned inside the article containing portion 2 of the sealing bag 1 and a downstream end positioned outside the article containing portion 2. In regard to a positional relationship of the check valve V with respect to the sealing bag 1, although the downstream end of the check valve V may protrude out from an edge of the sealing bag 1, in the present example, the check valve V is fixed so that the downstream end of the check valve V is positioned closer to the article containing portion 2 than the edge of the sealing bag 1 as shown in FIGS. 3A and 3B. That is, with the check valve V in the present example, the entire valve is sandwiched by the bag sheets 11 and 12. The check valve V is thereby protected by the bag sheets 11 and 12 and thus comparatively thin sheets (plastic films) may be used as the base sheets 31 and 32. Also, the sealing bag 1 is good in appearance and an obstacle due to a protruded check valve V is not presented during storage of the sealing bag 1, etc., because the check valve V can be arranged so as not to protrude from the edge of the sealing bag 1. A point seal 15 shown in FIGS. 3A and 3B is formed by the bag sheets 11 and 12 being adhered to unify the bag sheets 11 and 12 at a downstream side of the check valve V and may be omitted.

In the present example, a heat seal for adhering the bag sheets 11 and 12 has a stepped shape as shown in FIGS. 3A and 3B. The article containing portion 2 is thereby formed so as to have a partially notched form. The check valve V is disposed at the notched portion. Although in the present example, the “notch” is formed at a corner portion of the sealing bag 1 that is rectangular in a plan view so as to enable use of a widest portion of the article containing portion 2 as possible, the present invention is not limited thereto and, for example, a “notch” may be formed at a center of an end portion of the sealing bag 1 if required by design.

Of the bag sheets 11 and 12, an inner surface of either bag sheet 11 or 12 at the side that faces the other side base sheet 32 is adhered to a portion at the upstream end of the other base sheet 32 of the check valve V. In the present example, adhesion to the back bag sheet 12 is achieved by forming of a valve fixing seal 6 as shown in FIG. 4, and the gas flow passage portion 31a of the one base sheet 31 of the check valve V is thereby exposed to a space in the article containing portion 2 that is capable of containing an article. Although in the present example, the valve fixing seal 6 is provided in a line-like form at both ends in the width direction of the check valve V as shown in FIG. 1C, it suffices that the check valve V is able to follow deformation of the back bag sheet 12 and the positional relationship, shape, and quantity may be changed variously as shown in FIG. 4. However, in order to make the check valve V be aligned effectively along an inner surface of a cul-de-sac portion 21 that takes on an arched form as shall be described later, it is preferable to provide the valve fixing seal 6 at a downstream side in the gas flow direction relative to the upstream end 141 of a longitudinal direction seal 14. By the gas flow passage portion 31a being exposed as described above, air that is present in the article containing portion 2 can be guided readily to the check valve V to enable evacuation to be performed smoothly.

Also, a lateral direction seal 13 is formed in the sealing bag 1 by the adhesion (heat sealing) of the bag sheets 11 and 12 to each other. The longitudinal direction seal 14 and the traversing seal 13 do not indicate longitudinal and lateral positions of the sealing bag 1 and the bag sheets 11 and 12, and simply a direction along the upstream/downstream direction of the check valve V is defined as the longitudinal direction and a direction intersecting this is defined as the lateral (traversing) direction.

The lateral direction seal 13 is formed to traverse the check valve V in the width direction and more specifically, is formed further downstream than the upstream end 4a1 of the upstream valve body sheet 4a. Although the lateral direction seal 13 is formed rectilinearly in a plan view in the present example as shown in FIGS. 3A and 3B, it may be formed to have a wavy shape instead. A wavy shape is advantageous in that in this case, evacuation pressure is applied non-uniformly in the width direction to the check valve V during the evacuation of air, thereby facilitating the opening of the gas flow passage space 3a.

Also with the present example, a release coating 7 is coated onto an inner surface of the other base sheet 32 at a portion at which the lateral direction seal 13 is formed, and a situation where the other base sheet 32 and the upstream valve body sheet 4a become lightly adhered due to heat during forming of the lateral direction seal 13, which is a heat seal, and disable smooth evacuation can thereby be avoided. As an alternative to the release coating 7, a nonwoven fabric may be attached to the inner surface of the other base sheet 32.

In addition to the lateral direction seal 13, the longitudinal direction seal 14 is formed in the sealing bag 1 by the adhesion (heat sealing) of the bag sheets 11 and 12 to each other. The longitudinal direction seal 14 extends in a direction intersecting (in the present example, a direction orthogonal to) the lateral direction seal 13 and extends further upstream than the lateral direction seal 14 on a basis of the gas flow direction during evacuation of the inside of the check valve V. The longitudinal direction seal 14 is formed as a single set of the two seals of an inner longitudinal direction seal 14a and an outer longitudinal direction seal 14b that are spaced by an interval wider than a width dimension of the check valve V so as to sandwich the check valve V. In the present example, the outer longitudinal direction seal 14b formed at a right side of the check valve V in FIGS. 3A and 3B serves in common as a side seal formed at an edge of the sealing bag. Also in the present example, the inner longitudinal direction seal 14a and the lateral direction seal 13 are formed at the same time by a single sealing bar (heat bar).

The upstream end 141 of the longitudinal direction seal 14 is positioned further upstream, on the basis of the gas flow direction during the evacuation of the inside of the check valve V, than a lower end 31a1 of a portion, of the gas flow passage portion 31a in the one base sheet 31, which is defined by the lateral direction seal 13 and through which air practically flows. In regard to the positional relationship of the upstream end of the check valve V and the upstream end 141 of the longitudinal direction seal 14, the upstream end 141 is preferably disposed at a position more downstream than the upstream end of the check valve V in the gas flow direction. In the present example, the upstream end 141 of the inner longitudinal direction seal 14a is disposed at substantially the same position as the upstream end of the check valve V in the gas flow direction as shown in FIG. 3A. Also, even in a case where the upstream end 141 is disposed further downstream than the upstream end of the check valve V, it is preferable to make a distance between the upstream end 141 and the upstream end of the check valve V as small as possible so that a larger portion of the gas flow passage portion 31a is overlapped with the cul-de-sac portion 21 that takes on the arched form as shall be described later.

Also, although in the present example, the inner longitudinal direction seal 14a is formed to be continuous in an up/down direction in the figures, for example, gas passing gaps 14c, indicated by a broken line in FIG. 3A may be provided or the inner longitudinal direction seal 14a may have a discontinuous form as shown in FIG. 3B. In such cases, the cul-de-sac portion 21 that is deformable to the arched form as shall be described later is formed and in the article containing portion 2, air present at a portion to the left of the inner longitudinal direction seal 14a in the figures can be guided to the check valve V through the gas passing gaps 14c to enable smooth evacuation.

The cul-de-sac portion 21 is formed by the lateral direction seal 13 and the longitudinal direction seal 14. The cul-de-sac portion 21 swells so that its transverse section takes on an arched form as shown in FIG. 4 when the article containing portion 2 is compressed with hands or when internal pressure increases due to generation of gas from the contained article. The check valve V is adhered to the back bag sheet 12 as described above and thus the check valve V is aligned with an inner surface of the cul-de-sac portion 21 that has taken on the arched form.

During evacuation, air in the article containing portion 2 is first guided to the cul-de-sac portion 21 and is thereafter successively evacuated out of the bag through the gas flow passage portion 31a. On the other hand, in a case where such a cul-de-sac portion 21 is not formed, an interval between the bag sheets 11 and 12 may not spread sufficiently during evacuation and an evacuation fault may occur. Such a problem does not occur when the cul-de-sac portion 21 is formed, and the evacuation can be performed more smoothly and the “initial pressure” can also be reduced thereby.

Here, with a conventional sealing bag, a check valve is difficult to open, and to reduce the “initial pressure,” the check valve is disposed at an end portion of the sealing bag and the base sheets and the valve body sheets of the check valve are distorted intentionally. Although the “initial pressure” can thereby be reduced, there is a problem that reverse flow also occurs readily. In contrast, the check valve V according to the present invention enables smooth evacuation on its own, is not limited in a position of fixing to the sealing bag 1, and can thus increase a degree of freedom of design of the sealing bag 1.

A method for producing the check valve V shall now be described. Elongate sheets supplied continuously in a longitudinal direction are used as the base sheets 31 and 32 and the valve body sheets 4. The respective valve body sheets 4a and 4b forming the single set are supplied as a single elongate sheet, which is then cut in two in a width direction by application of a cutting blade and then overlapped with and adhered to the one base sheet 31. By the cutting, a slit is formed in the single elongate sheet that is the material of the valve body sheets 4. The overlapping is performed immediately after the forming of the slit and the valve body sheets 4a and 4b are adhered while the interval therebetween is maintained as an extremely small interval. Thus, in comparison to a case where different sheets are supplied as the materials of the respective valve body sheets 4a and 4b, the check valve V can be produced more simply and with higher precision and the production cost also does not increase.

Due to convenience of design of a production apparatus, etc., in contrast to the above, the valve body sheet 4 supplied as a single elongate sheet may first be overlapped with the one base sheet 31 and a cutting blade may thereafter be applied to the valve body sheet 4 in the overlapped state to cut the sheet in two in the width direction to form the valve body sheets 4a and 4b.

The check valves V are produced in a state of being joined in the width direction and are cut individually in a process of fixing to the sealing bag 1. However, the valves may also be fixed to the sealing bag 1 as continuous valves in a state where a plurality of valves remain continuous in the width direction.

A method for producing the sealing bag 1 with the check valve V fixed shall now be described briefly. Elongate sheets made of a flexible resin and supplied continuously in a longitudinal direction are used as the bag sheets 11 and 12. The method for producing the sealing bag 1 includes the steps of sandwiching the check valve V by the bag sheets 11 and 12, forming the lateral direction seal 13 by adhering the bag sheets 11 and 12, and forming the longitudinal direction seal 14 likewise by adhering the bag sheets 11 and 12. Sealing bags with check valves can be produced continuously by the present production method.

As another embodiment, the check valve V may be fixed not restrictedly to a bag such as shown in FIG. 3A but may be fixed to a so-called “vertical pillow” type sealing bag 201 such as shown in FIG. 5A that is often used as packaging for coffee beans, etc. The respective figures of FIG. 5 show an article-contained state. In FIG. 5C, an inner side of the bag is drawn as an upper side in the figure and an outer side of the bag is drawn as a lower side in the figure.

In producing such a “vertical pillow” type sealing bag 201, a single bag sheet 211 is folded over at crease lines 212 and 212 at both right and left sides of the bag, edges of the bag sheet 211 are matched at a back surface side (to put the sheet in a folded state), and the check valve V is sandwiched and adhered between the facing edges, and a seal thereby formed is used as the lateral direction seal 13. Then as shown in FIGS. 5B and 5C, portions of the bag sheet 211 are made to enter further inward into the sealing bag 201 than the lateral direction seal 13 and adhered together to form a seal. The seal functions as the longitudinal direction seal 14. In the example shown in FIG. 5B, an auxiliary seal 16 extending parallel to the lateral direction seal 13 in an opposite direction to the check valve V is provided at an upstream end of the longitudinal direction seal 14 and gas inside the bag can thereby be guided effectively to the cul-de-sac portion 21.

Even with the “vertical pillow” type sealing bag 201, the cul-de-sac portion 21 is formed by the lateral direction seal 13 and the longitudinal direction seal 14 as in the bag shown in FIG. 3A, and in a case where the internal pressure of the bag increases, a transverse section of the cul-de-sac portion 21 swells so as to be an arched form (see FIG. 4). Thus, in the same manner as described above, evacuation can be performed smoothly and the “initial pressure” can be reduced with the sealing bag 201 as well. Thus, in a case where the contained article is coffee beans or other article that constantly generates gas (carbon dioxide, etc.), the sealing bag 201 does not swell clumsily due to the generated gas not being evacuated readily to the outside of the bag and remaining in the bag.

Although with the example shown in FIG. 3, the check valve V is disposed at a bottom portion of the sealing bag 1, the position at which the check valve V is disposed may be changed as suited and may be a side portion of the sealing bag 1 or a central portion (a front surface or a back surface) of the sealing bag 1.

In an example shown in FIG. 6A, the check valve V is disposed at a position close to the article receiving opening 1a at a side portion of the sealing bag 1. In this example, a recessed portion 211 is formed by recessing the bag sheets 11 and 12 in the lateral direction and the check valve V is sandwiched and fixed in a laterally extending manner at the position close to the article receiving opening 1a equipped with a zipper. The recessed portion 211 is, the bag sheets 11 and 12 are sealed, and

A seal at an inner side of the recessed portion 211 is the above-described lateral direction seal 13. With the present example, in a case where a liquid matter is contained or in a case where a food, etc., that releases a liquid is contained, the liquid matter stays at a bottom of the bag and thus by disposing the check valve V at the position close to the article receiving opening 1a, the liquid matter can be made to adversely affect the check valve V. The present embodiment may also be practiced with the longitudinal direction seal 14 in the examples described above being provided.

In an example shown in FIGS. 6B and 6C, the check valve V is disposed at a central portion (a front surface or a back surface) of the sealing bag 1. In this example, the one bag sheet 11 is divided into two sheets of a first sheet 11a and a second sheet b. The first sheet 11a and the second sheet b are made into a single bag seal by edges thereof being sealed together, and the check valve V is fixed by being sandwiched between the first sheet 11a and the second sheet 11b. The seal between the first sheet 11a and the second sheet 11b is the lateral direction seal 13 that traverses the check valve V. In this example, the downstream side of the check valve V is positioned at an outer surface (an outer side of the bag) of the one sheet (the second sheet 11b) and the upstream side of the check valve V is positioned at an inner surface (an inner side of the bag) of the other sheet (the second sheet 11b). The check valve V may be fixed regardless of its front and back sides, in the present example, the one base sheet 31 made of the nonwoven fabric, etc., is disposed at the inner surface side of the bag. Although in a case where the check valve V is fixed so that the one base sheet 31 is positioned at the side facing the first sheet 11a, when a food is contained in the sealing bag 1 and heating by a microwave oven is performed, the one base sheet 31 of the check valve V may be pressed against the first sheet 11a due to air expanded by heating and the air may not be evacuated satisfactorily, but by disposing the one base sheet 31 at the inner side of the bag, the expanded air inside the bag can be evacuated satisfactorily. In particular, in the present example, the heat sealed portion of the lateral direction seal 13 that was necessary for fixing the check valve V by adhesion to the sealing bag 1 in the previous examples is made unnecessary. As a result, evacuation with lower pressure is made possible, and in a case of practice, for example, as a bag that contains coffee beans, powder detergent, or other article that generates gas and is capable of suppressing expansion of the bag by evacuation of the gas generated from the article to the outside of the bag, the gas can be evacuated with the initial pressure of the evacuated gas being low.

Also, as the second sheet 11b, a sheet that is heat sealable at both surfaces is preferably adopted. Specifically, use of a coextruded film with both surfaces being made of polyethylene films is preferable. This is because the second sheet 11b is heat sealed at one surface (the outer surface in the figure) to the first sheet 11a that includes the lateral direction seal 13 and is sealed at the other surface (the inner surface in the figure) to the other bag sheet 12. In a case where sheet that can be heat sealed at only one side is used, heat sealing can be performed by folding back the edge to be sealed as in the example of FIG. 5. Also, by using a sheet with which both surfaces are made of polyethylene films, etc., and heat sealing can be performed at both surfaces, the folding back is made unnecessary in the example of FIG. 5 as well.

The present embodiment can also be practiced with the longitudinal direction seal 14 of the previous examples being provided.

Another embodiment shall now be described based on FIG. 7. In this example, a portion of the check valve V of FIG. 1 is changed and the changed portion shall mainly be described below with the portions not being described being the same as in the check valve V of FIG. 1.

In the present example, the one base sheet 31 is made of two types of sheets. In detail, of the one base sheet 31, a sheet 31a positioned at the upstream side is, as in the example of FIG. 1, the gas flow passage portion 31a and is made of the sheet of nonwoven fabric, etc., having gas permeability. Unlike the previous example, the downstream side sheet 31d is made of a gastight sheet 31d. End portions of the gas flow passage portion 31a and the gastight sheet 31d are adhered with the upstream end 4a1 of the upstream valve body sheet 4a at an adhered portion s1.

Although in the example of FIG. 1, the other base sheet 32 is made shorter than the one base sheet 31 to form an air passage, in the present example, the other base sheet 32 and the one base sheet 31 are made the same in size and whole perimeters thereof are adhered to form a whole perimeter adhered portion s3.

As in the example in FIG. 1, a sheet with gastightness is adopted as the other base sheet 32 and a slit or other outlet 32b of suitable shape is formed as the outlet at the downstream end side. The outlet 32b is disposed further downstream (to the right in the figure) than the downstream end 4a2 of the upstream valve body sheet 4a and the upstream end 4b1 of the downstream valve body sheet 4b.

As shown in FIG. 7D, the check valve V may be disposed inside of the sealing bag 1. This check valve V is disposed so as to cover, from an inner side, a bag vent hole 17 provided in the back bag sheet 12 of the sealing bag 1 and a whole perimeter thereof is adhered to the back bag sheet 12. The adhesion may be performed in common with the whole perimeter adhered portion s3 or be performed by sealing separately. Although the outlet 32b and the bag vent hole 17 are disposed at the same position in the figure, these may be disposed at different positions as long as these are within the range of the whole perimeter adhered portion s3.

In evacuating air inside the sealing bag 1, the air enters into the check valve V from the gas flow passage portion 31a and flows out to the outside from the bag vent hole 17 via the outlet 32b. When air tends to flow in from the outside, the inside of the check valve is put in a negative pressure state and the upstream valve body sheet 4a and the downstream valve body sheet 4b closely contact the other base sheet 32 to close the flow path.

Also, the check valve V may be disposed at an outside portion of the sealing bag 1 as shown in FIG. 7E. This check valve V is disposed so as to cover the bag vent hole 17, provided in the back bag sheet 12 of the sealing bag 1, from the outer side and the whole perimeter thereof is adhered to the back bag sheet 12 . The adhesion may be performed in common with the whole perimeter adhered portion s3 or be performed by sealing separately. Although the gas flow passage portion 31a and the bag vent hole 17 are disposed at the same position in the figure, these may be disposed at different positions as long as these are within the range of the whole perimeter adhered portion s3.

In evacuating air inside the sealing bag 1, the air enters into the check valve V from the bag vent hole 17 via the gas flow passage portion 31a and flows out to the outside from the outlet 32b. When air tends to flow in from the outside, the inside of the check valve is put in a negative pressure state and the upstream valve body sheet 4a and the downstream valve body sheet 4b closely contact the other base sheet 32 to close the flow path.

In either case of fixing the check valve V to the inside or outside of the sealing bag 1, the check valve V and the bag vent hole 17 may be disposed on the front bag sheet 11.

Although in FIG. 7, the vertical length is exaggerated, in actuality, the respective sheets are practically in contact constantly and merely a small gap opens only when air flows through.

In any of the embodiments, bent seals s4 and s5 may be applied to the check valve V of the present application so as to form a flow path of zigzag form in a plan view. A specific example is shown in FIG. 8. With this example, a portion of the example of FIG. 7 is changed and only the changed portion shall be described below with the portions not being described being the same as those in the example of FIG. 7.

As in the example of FIG. 1, with the check valve V of the present example, the other base sheet 32 is made shorter than the one base sheet 31 and a space between the other base sheet 32 and the whole perimeter adhered portion s3 is used as the outlet 32b. Needless to say, an outlet 32b such as that of the example of FIG. 7 may also be applied.

The bent seals s4 and s5 are formed across substantially an entire length of the check valve V from the upstream end to the downstream end and adhere the three components of the one base sheet 31, the valve body sheets 4, and the other base sheet 32 in the front/back direction. Although this check valve V adopts a nonwoven fabric or other sheet with gas permeability as in the gas flow passage portion 31a of FIG. 7B, unlike FIG. 7B, crosshatching is not applied in the plan view of FIG. 8A in order to show the bent seals s4 and s5 in a clear manner.

In the present example, the two bent seals s4 and s5 are formed, and in the gas flow passage portion 31a, an interval between the two bent seals s4 and s5 is increased gradually toward the upstream side (the left side in the figure) so as to spread in a funnel-like manner. Air is thereby made to enter satisfactorily into the check valve V from the gas flow passage portion 31a. At the portion with the valve body sheets 4, the two bent seals s4 and s5 are bent or curved while maintaining a narrow interval and extend toward the downstream side (the right side in the figure). The two bent seals s4 and s5 differ in length, and the one bent seal s4 disappears upon entering the downstream valve body sheet 4b beyond the upstream valve body sheet 4a. The other bent seal s5 extends to the downstream end of the other base sheet 32 and then disappears. The bent seals s4 and s5 are not formed at the outlet 32b between the downstream end of the other base sheet 32 and the whole perimeter adhered portion s3. This is done so that air is evacuated satisfactorily from the outlet 32b. Of course, the above description describes merely one example of the bent seals s4 and s5, and any arrangement that weakens a rectilinearly progressing property of air and narrows the flow path at the portion provided with the valve body sheets 4 and spreads the flow path near the upstream end and the downstream end to smoothen the flow of air into and out of the check valve V suffices. Also, although the two bent seals s4 and s5 are formed, only one may be formed instead. In this case, an interval between the single bent seal and the whole perimeter adhered portion s3 becomes the flow path. Oppositely, three or more bent seals maybe used and used in combination with a point seal, etc., is also possible. Also, the shapes of the one base sheet 31 and the other base sheet 32 may be cut along the shapes of the bent seals s4 and s5 so that the bent seals s4 and s5 serve in common as portions of the whole perimeter adhered portion s3.

Further in the present example, a small amount of a silicone liquid or other inert substance 8 is disposed between the valve body sheets 4 and the other base sheet 32 at an intermediate portion of the flow path between the two bent seals s4 and s5. Close contact of the upstream valve body sheet 4a and the other base sheet 32 is thereby increased when the two components contact closely to close the flow path to thereby prevent leakage of air. Although the silicone oil or other inert substance 8 is thus disposed only between the upstream valve body sheet 4a and the other base sheet 32 in the present example, it may also be disposed between the downstream valve body sheet 4b and the other base sheet 32.

As in the example of FIG. 7, the present check valve V may also be disposed either at the inside or the outside of the sealing bag 1 and prevents the reverse flow of a fluid and allows only the flow of the fluid in one direction (from the inner side to the outer side of the bag in the present example) by the same actions as those of the check valve V of FIG. 7. An example of fixing to the outer side of the bag sheet 12 of the sealing bag 1 is shown in FIG. 8D.

As described above, with the present check valve V, the flow path of air is arranged in a maze-like manner by providing the bent seals s4 and s5 and thus even in the case air flows in the positive direction, slight resistance arises. The degree of resistance can be changed variously by the shapes and sizes of the bent seals s4 and s5 and can be adjusted according to the application. For example, in a case where the check valve V is used in a sealing bag that contains a food, a vapor that is generated from the food during thawing or heating by a microwave oven can be released to the outside of the sealing bag by the check valve V and by providing the bent seals s4 and s5, resistance against the evacuation of air is provided so that the vapor is evacuated out of the bag gradually. The food can thereby be steamed, and a thawing procedure for preparing a more delicious meal can thus be performed with the microwave oven. The shapes and sizes (lengths, widths) of the bent seals s4 and s5 can thus be changed as suited according to an air evacuation rate that is required.

An example is shown in FIG. 9A, wherein a different valve body sheet 91 from the valve body sheets 4a and 4b is provided. The new valve body sheet 91 is disposed between the valve body sheets 4a and 4b and the other base sheet 32 inside of the check valve V and is made closely contactable with at least one of either the valve body sheet 4a or 4b and the new valve body sheet 91 cooperates with the valve body sheets 4a and 4b to perform passage and reverse flow prevention of a fluid. The new valve body sheet 91 may also be adopted in other embodiments of the present invention.

In the examples of FIG. 7 and FIG. 8, the one base sheet 31 is divided into the gas flow passage portion 31a such as a nonwoven fabric, etc. and the gastight sheet 31d, the entire one base sheet 31 may be made of a nonwoven fabric or other material with gas permeability and only a downstream portion thereof may be coated with a covering sheet 92 with gastightness as shown in FIG. 9B. By making the entire one base sheet 31 from the nonwoven fabric, etc., a situation where the valve body sheets 4a and 4b closely contacted unnecessarily with the one base sheet 31 and not providing the effect of the check valve can be prevented. The covering sheet 92 can be set freely in thickness, etc., and by using a hard sheet of comparatively large thickness, bending or twisting due to pressing of the check valve V by contents of the sealing bag can be prevented to protect the valve and make the functions thereof be exerted reliably.

By providing the check valve V such as those described above, the certainty of the checking effect can be improved while avoiding increase of the production cost of the check valve V as much as possible, and various sealing bags 1 with the check valve V fixed can be made better than conventional arrangements.

In particular, in a case where the object contained in the sealing bag 1 is a food or other readily degradable object, an effect of preventing oxidation of the contained object arises because the article containing portion 2 can be evacuated smoothly and a contribution can thus be made to maintenance of freshness.

DESCRIPTION OF THE REFERENCE NUMERALS

1 Sealing Bag

11 Front Bag Sheet

12 Back Bag Sheet

13 Lateral Direction Seal

14 Longitudinal Direction Seal

141 Upstream End of Longitudinal Direction Seal

2 Article Containing Portion

3
a Gas Flow Passage Space

31 One Base Sheet

31
a Gas Flow Passage Portion

32 Other Base Sheet

4 Valve Body Sheet

4
a Upstream Valve Body Sheet

4
a
1 Upstream End of Upstream Valve Body Sheet

4
a
2 Downstream End of Upstream Valve Body Sheet

4
b Downstream Valve Body Sheet

4
b
1 Upstream End of Downstream Valve Body Sheet

4
b
2 Downstream End of Downstream Valve Body Sheet

4
b
3 Non-contacting Portion of Downstream Valve Body Sheet

V Check Valve

CHECK VALVE, SEALING BAG, AND PRODUCTION METHODS FOR BOTH

Information

Publication Number

Date Filed

Date Published

Inventors

CPC

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International Classifications

Abstract

Description

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Priority Claims (1)

PCT Information