JP2000096499A - Production of pulp-molded vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce pulp-molded vessel having a uniform wall thickness without unevenness in the product shape and dimensional accuracy. SOLUTION: An air-feeding pipe 40 is inserted into the cavity 4 of the mold for molding 1 from the outside of the vessel via the pulp slurry flow inlet 6, and the mold 1 is dipped in the pulp slurry 21, as the flow inlet 6 is directed downward. The slurry 21 is sucked through the flow inlet 6 to form the pulp- molded body 22 on the inner face of the cavity. The flow inlet 6 is sealed to stop the slurry flow, then the inside of the cavity 4 is sucked, as the air is fed upward to the upper part of the cavity by the air-feeding pipe 40, to dehydrate the pulp molded body 22. Then, the air-feeding pipe 40 is pulled out, and simultaneously, the mold for molding 1 is opened to take out the pulp- molded product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a pulp mold container having a uniform thickness.

[0002]

2. Description of the Related Art Plastic containers are generally used for packaging containers such as containers and bottles having a lid because they have excellent moldability and are advantageous in terms of productivity. . However, since plastic containers have various problems in terms of disposal treatment, a pulp mold container molded by a pulp mold method may be considered as an alternative. The pulp mold container can be manufactured at low cost because it can be manufactured using recycled paper in addition to easy disposal.

As one method of manufacturing a pulp mold container, for example, Japanese Patent Application Laid-Open No.
A method is described in which pulp slurry is injected from a special nozzle into a mesh-shaped mold, high-pressure air is further blown to remove a considerable amount of water, the mold is released, and drying is performed using hot air, infrared rays, or the like.

However, in the above method, since the pulp fibers do not adhere sufficiently to the surface of the mold, complicated shapes cannot be provided, the product shape and the dimensional accuracy vary greatly, and the pulp inside the mold is blown by blowing high-pressure air. The fibers are disturbed and it is not easy to produce a pulp mold container having a uniform thickness.

An object of the present invention is to provide a method capable of manufacturing a pulp mold container having a uniform thickness without variation in product shape and dimensional accuracy.

[0006]

SUMMARY OF THE INVENTION The present invention comprises a pair of split dies having a communication passage communicating from the inside to the outside, and abutting the split dies, the cavity is formed inside and the cavity is formed. An air supply pipe is inserted into the cavity from the outside through the pulp slurry inflow port into the molding die in which the pulp slurry inflow port opening to the outside is formed. The pulp molded body is formed by immersing the pulp slurry in the state where the inlet is directed downward, sucking the pulp slurry through the pulp slurry inlet and depositing pulp fibers on the inner surface of the cavity,
The pulp slurry inflow port was sealed to stop the inflow of the pulp slurry, and the air was supplied to the upper portion of the cavity by the air supply pipe while sucking the inside of the cavity to dehydrate the pulp molded body. Thereafter, the above object has been achieved by providing a method of manufacturing a pulp mold container in which the air supply pipe is pulled out and the molding die is opened to take out the pulp molded body.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a preferred embodiment of a method for producing a pulp mold container of the present invention will be described with reference to the drawings, taking the production of a bottomed hollow container having a mouth and a neck as an example. Here, FIG. 1 is a diagram showing a molding die preferably used in the first embodiment of the method for producing a pulp mold container of the present invention.

A molding die 1 shown in FIG.
2, a cavity 4 having a shape corresponding to the outer shape of the container having the mouth and neck portion to be molded is formed therein, and the pulp opened to the outside from the mouth and neck corresponding cavity portion 5 in the cavity 4. The slurry inlet 6 is formed.

A plurality of communication holes 3 are regularly formed in the inner surface of the cavity 4 over the entire surface. On the other hand, no communication hole is formed in the pulp slurry inlet 6.
The communication holes 3 communicate with respective manifold portions 7 formed inside the split mold 2. The manifold 7 communicates with a suction port 8 provided on a side of the molding die 1 opposite to the side where the pulp slurry inlet 6 is formed. The suction port 8 is connected to a suction device (not shown). As a result, a communication path in which the cavity 4, the communication hole 3, the manifold 7, and the suction port 8 communicate with each other is formed in each of the split dies 2, 2.
Then, as described later, suction is performed from the inside of the cavity 4 to the outside of the molding die 1 through this communication path, and pulp fibers are deposited on the inner surface of the cavity 4 and dewatered of the deposited pulp fibers. Is performed. The formation of the communication hole 3 and the manifold portion 7 in the split mold 2 can be easily performed by means known to those skilled in the art.

In the molding die 1, the cross-sectional area of the pulp slurry inlet 6 formed by abutting the two split dies is smaller than the cross-sectional area of the mouth-and-neck cavity 5. Thus, when the pulp slurry is sucked to form a pulp fiber layer, the pulp slurry is turbulent due to the inflow of the pulp slurry into the cavity 4 due to the suction of the pulp slurry. This has the advantage that the turbulence of the pulp fiber layer is effectively prevented and the thickness of the mouth and neck in the resulting container is uniform.

A cross-sectional area of the pulp slurry inlet 6;
The ratio to the cross-sectional area of the mouth-and-neck cavity 5 depends on the size and shape of the container to be molded or the degree to which the pulp slurry is sucked.
0.99, particularly preferably 0.30 to 0.70, is preferable because the thickness of the entire container obtained can be made uniform and the papermaking efficiency can be increased.

In the molding die 1, a papermaking net 20 is disposed along the inner surface of the cavity 4 as shown in FIG. Thus, the cross-sectional area of each communication hole 3 formed in the manifold section 7 can be increased, and the number thereof can be reduced. This is advantageous in that the split mold 2 can be manufactured at low cost.

In particular, the papermaking net is constituted by a first net layer and a second net layer finer than the first net layer, and the cavity of the cavity 4 is oriented so that the first net layer faces the inner side of the cavity 4. It is preferable to adhere along the inner surface. As the first net layer and the second net layer, for example,
A net made of a natural material, a synthetic resin or a metal, or a net made of a combination thereof is used. Plant fibers, animal fibers and the like are used as natural materials, and thermoplastic resins, thermosetting resins, recycled resins, and semi-synthetic resins are used as synthetic resins. Further, in order to improve the slipperiness, heat resistance and durability of these net layers, these net layers may be subjected to a surface modification coating.

The first net layer has an average maximum opening width of 1 to 50 mm, particularly 5 to 5 mm when disposed on the inner surface of the cavity 4.
It is preferably 10 mm. Average maximum opening width is 1m
If it is less than m, the suction efficiency will be poor, and pulp fibers may not be easily deposited on the surface of the papermaking net. 50m
If it is more than m, the second net layer may pass through the line between the first net layers and adhere to the inner surface of the cavity 4, as a result, the suction efficiency may be locally deteriorated, and the thickness of the pulp fiber layer may be reduced. May be uneven. In addition, in this specification, the opening width of the net layer refers to a distance between lines of a linear body constituting the net layer.

The first net layer includes a cavity 4
Has an average open area ratio of 30 to 95 when arranged on the inner surface of
%, Particularly preferably 75 to 90%. When the average open area ratio is less than 30%, the suction efficiency is deteriorated, and a pulp fiber layer is hardly formed. When the average hole area ratio is more than 95%, the second net layer may adhere to the inner surface of the cavity 4 in some cases. As a result, the suction efficiency is locally deteriorated, and the thickness of the pulp fiber layer may be uneven.

On the other hand, the second net layer has an average maximum opening width of 0.05 to 1.0 when arranged on the inner surface of the cavity 4.
mm, particularly preferably 0.2 to 0.5 mm.
When the average maximum opening width is less than 0.05 mm, the suction efficiency is deteriorated, so that the pulp fiber layer may not be easily formed. When the average maximum opening width is more than 1.0 mm, the pulp fiber may easily pass through. In some cases, it may be difficult to form a pulp fiber layer.

Further, the second net layer preferably has an average open area ratio of 30 to 90%, particularly preferably 50 to 80%, when disposed on the inner surface of the cavity 4. If the average open area ratio is less than 30%, the suction efficiency becomes poor, so that a pulp fiber layer may not be easily formed. If it is more than 90%, the pulp fiber may easily pass through.
It may be difficult to form a pulp fiber layer.

Next, a method for manufacturing a pulp mold hollow container having a mouth and a neck and having a bottom using the molding die 1 will be described with reference to FIGS. Here, FIG.
FIGS. 3A and 3B are process diagrams sequentially showing the first half of a process of manufacturing a pulp mold container, wherein FIG. 3A is a process of inserting an air supply pipe into a mold and immersing the mold, and FIG.・ Paper making process, (c) is a process of supplying air into the cavity and dewatering the pulp molded body, (d) is a process of pulling up the forming die and drawing out the air supply pipe, and (e) is opening the forming die and pulp forming. This is the process of removing the body. Also,
FIGS. 3A and 3B are process diagrams sequentially showing the latter half of the process of manufacturing the pulp mold container, wherein FIG. 3A is a process of putting a pulp molded body into a drying mold, and FIG. , (C) is a pressurization / dehydration / drying step of the pulp molded body,
(D) is a step of opening the drying mold, and (e) is a step of removing the pulp mold container.

First, as shown in FIG. 2 (a), a pair of split molds 2, 2 are butted against each other, and a papermaking net 20 is arranged along the inner surface of the cavity 4. An air supply pipe 40 having a flange 41 is inserted into the cavity 4 from outside through the pulp slurry inflow port 6, and then the molding die 1 into which the air supply pipe 40 is inserted is moved to the pulp slurry inflow port 6. It is immersed in the pulp slurry 21 in a state facing downward. The air supply pipe 40 has a disc-shaped flange 41 near one end 43 and has a structure in which an air supply hose 42 is connected to the end 43. The area of the flange 41 is equal to or larger than the cross-sectional area of the pulp slurry inlet 6 in the molding die 1. The air supply hose 42 is connected to an air supply source (not shown). Then, the air supply pipe 40 is inserted into the cavity 4 from the direction of the other end 44. The length of the air supply pipe 40 from the other end 44 to the flange 41 is such that when the flange 41 is brought into contact with the pulp slurry inlet 6, the other end 44 corresponds to the bottom of the cavity 4. The length is such that it does not contact the cavity 5 ′.

The papermaking net 20 is composed of the above-mentioned first net layer and a second net layer finer than the first net layer, and the first net layer is in close contact with the inner surface of the cavity 4. I have. In this embodiment, the first net layer has an average maximum opening width of 3 to 6 mm and an average opening area ratio of 80 to 9 when arranged on the inner surface of the cavity 4.
A net having a line width of 2% and a line width of 0.3 mm was used. on the other hand,
As the second net layer, the average maximum opening width in a state of being arranged on the inner surface of the cavity 4 is 0.22 to 0.35 mm;
The average open area ratio is 58 to 69%, and the line width is 0.06 to 0.
A net having a length of 07 mm was used.

Next, as shown in FIG. 2B, the pulp slurry inlet 6 and the flange 4 in the air supply pipe 40 are formed.
Under a state where a gap 45 is provided between the suction port 8 and the suction port 8, the suction port (not shown) is used.
The pulp slurry 21 is sucked through 5 and the pulp fibers are deposited on the papermaking net 20 arranged along the inner surface of the cavity 4. Thereby, the pulp molded body 22 is formed on the papermaking net 20. The degree of suction depends on the size and shape of the container to be molded, but is generally from -0.13 to-
101.3 kPa, especially -13.3 to -80.0 kPa
It is preferred that

When a pulp compact 22 having a predetermined thickness is formed, as shown in FIG. 2C, the pulp slurry inflow port 6 is sealed with a flange 41 of the air supply pipe 40 to remove the pulp slurry 21. Stop the inflow of water. Then, under a sealed state by the flange portion 41, an air supply source (not shown) is used to move the air supply pipe 40 to an upper portion in the cavity 4 to be used.
That is, the inside of the cavity 4 is sucked while air is forcibly supplied to the vicinity of the bottom corresponding cavity portion 5 ′, the pulp slurry 21 existing in the cavity 4 is discharged to the outside, and the pulp compact 22 is dehydrated. By performing suction while supplying air to the upper part in the cavity 4 filled with the pulp slurry 21, the accumulated pulp fibers are effectively prevented from being disturbed by suction, and are formed. Thus, the thickness of the container becomes uniform, and the disadvantage which has been a problem in the conventional manufacturing method is eliminated. In addition, since the cross-sectional area of the pulp slurry inlet 6 is smaller than the cross-sectional area of the mouth-and-neck cavity 5 as the molding die, the mouth-and-neck cavity 5 is used. Pulp fibers deposited on the pulp slurry 2
1 is effectively prevented from being disturbed by the inflow of 1, and the thickness of the mouth and neck in the container to be molded becomes more uniform. It should be noted that the degree of the dehydration is such that the moisture content of the pulp molded body 22 is 10 to 95% by weight of the pulp molded body 22, particularly 4% by weight.
It is preferable that the pulp molded body 22 has a degree of 0 to 80% by weight from the viewpoints of shape retention and productivity.

When the pulp compact 22 has been dehydrated to a predetermined moisture content, the mold 1 is pulled up from the pulp slurry 21 as shown in FIG. 2D, and the air inserted into the mold 1 is further removed. The supply pipe 40 is pulled downward. Subsequently, as shown in FIG. 2E, the molding die 1 is opened and the pulp molded body 22 is taken out. In this case, the pulp compact 2
2 is dehydrated to a sufficient degree of shape retention,
There is no danger of mold collapse upon removal.

The pulp molded body 22 taken out is shown in FIG.
As shown in (a), a cavity 32 having a shape corresponding to the outer shape of the container to be molded is formed in the interior thereof by abutting. It is placed in the cavity 32.
The drying mold 30 may be heated or at room temperature, but is preferably heated from the viewpoint of increasing the molding cycle. When the drying mold 30 is heated, its temperature is preferably from 20 to 300C, particularly preferably from 100 to 250C.

Next, as shown in FIG. 3 (b), a bag-shaped core 33 having elasticity and elasticity is inserted into the pulp molded body 22. The core 33 is inflated like a balloon in the pulp molded body 22, and presses the pulp molded body 22 against the inner surface of the cavity 32 to give the inner surface shape of the cavity 32 and dewater the pulp molded body 22.
Used to dry. Therefore, the core 33 is made of urethane, fluorine, and the like having excellent tensile strength, rebound resilience, and elasticity.
It is preferably formed of a silicone rubber, an elastomer or the like.

Next, as shown in FIG.
A fluid (preferably a heating fluid) is supplied into the
Is expanded, and the pulp molded body 2 is expanded by the expanded core 33.
2 is pressed against the inner surface of the cavity 32. As a result, the pulp molded body 22 is pressed against the inner surface of the cavity 32 by the expanded core 33, and the shape of the inner surface of the cavity 32 is transferred and dehydrated and dried. The pressing time by the core 33 depends on the pressure and temperature of the fluid, the temperature of the drying mold 30, and the like.
Seconds, particularly preferably 5 to 60 seconds. As the fluid, for example, compressed air, oil, and other various liquids are used. The supply pressure of the fluid is between 9.8 kPa and 4.9 MPa.
Is preferable because the core 33 can sufficiently press the pulp molded body 22 against the inner surface of the cavity 32 and the core 33 does not cause the pulp molded body 22 to be crushed. When a heating fluid is used, the temperature is preferably from 20 to 300 ° C, particularly preferably from 100 to 250 ° C.

When the drying of the pulp compact 22 is completed, the fluid in the core 33 is drained as shown in FIG. Then, the core 33 contracts due to the elastic force. Next, the contracted core 33 is taken out from the pulp molded body 22 and the split mold 3 is removed.
The pulp mold container 34 formed as shown in FIG. In addition, depending on the material of the core 33, it may be used as an inner layer of the pulp molded body 22 without taking out the core 33. Thereby, a highly waterproof container can be obtained.

The container 34 thus obtained is shown in FIG.
(E) As shown in (e), a bottomed hollow container having a mouth-neck portion, wherein the thickness of each of the mouth-neck portion 35, the body portion 36, and the bottom portion 37, particularly the thickness of the mouth-neck portion 35, is uniform. Becomes Further, the inner and outer surfaces of the container have good surface properties, and the inner and outer surfaces are beautiful.

Further, according to the method for manufacturing a pulp mold container using the above-described molding die, the container height is high (60 m).
m), a hollow container having a complicated shape, such as one having a cubic curved surface, one having a bottomed or no bottom, as well as one having no draft angle.
For example, a straight shape with no taper angle and a height of 6
Forming a hollow container without a bottom as high as 0 mm or more, a hollow container without a bottom having a tertiary curved surface with a concave body, and a hollow container without a bottom having a tertiary curved surface with a plurality of projections formed on the outer surface of the lower end of the container. Can be. Further, a straight bottomed hollow container having a mouth and neck diameter substantially equal to the bottom diameter and having no taper angle, and a bowl-shaped bottomed hollow container having a mouth and neck diameter larger than the bottom diameter. Can also be formed. Furthermore, a bottomed or non-bottomed container in which the diameter of the mouth and neck is smaller than the diameter of the trunk, a bottomed hollow container having a cylindrical shape with a convex pattern formed on the surface, and a bottomed hollow container in which the trunk is concave , Forming a bottomed hollow container having an outer diameter gradually decreasing toward the bottom side from the mouth and neck side, and a bottomed hollow container having an outer diameter gradually increasing toward the bottom side from the mouth and neck side. Can also.

Next, a second embodiment of the present invention will be described with reference to FIG. Here, FIG. 4 is a process chart sequentially showing the first half of the process of manufacturing the pulp mold container.
FIGS. 3A to 3D are views corresponding to FIGS. 2A to 2D, in which FIG. 2A is a process of inserting an air supply pipe into a molding die and dipping the molding die, and FIG. (C) pulling up the mold, supplying air into the cavity and dewatering the pulp compact,
(D) is a process of extracting the air supply pipe. In the second embodiment, only the points different from the above-described first embodiment will be described, and the same points will not be particularly described. However, the detailed description of the first embodiment is appropriately applied. In FIG. 4, the same members as those in FIG. 2 are denoted by the same reference numerals.

The air supply pipe 40 used in the present embodiment
As shown in FIG. 4 (a), similar to the air supply pipe used in the first embodiment, a disc-shaped flange 41 is provided near one end 43, Supply hose not connected. Instead, the end 43 is sealed by a sealing means 46 to prevent liquid from entering the air supply pipe 40. Then, the air supply pipe 40 is inserted into the cavity 4 from the direction of the other end 44. Next, the molding die 1 into which the air supply pipe 40 has been inserted is immersed in the pulp slurry 21 with the pulp slurry inlet 6 facing downward.

Next, as shown in FIG. 4B, the pulp slurry inlet 6 and the flange 4 in the air supply pipe 40 are formed.
While the space 45 is provided between the pulp slurry 2 and the pulp slurry 2 through the space 45, the inside of the cavity 4 is degassed.
1 is sucked and pulp fibers are deposited on a papermaking net 20 arranged along the inner surface of the cavity 4, whereby
A pulp compact 22 is formed on the papermaking net 20.

When a pulp compact 22 having a predetermined thickness is formed, as shown in FIG. 4C, the pulp slurry inflow port 6 is sealed with a flange 41 of the air supply pipe 40 to remove the pulp slurry 21. And stop the suction once. Then, the molding die 1 is pulled up from the pulp slurry 21 under the state of being sealed by the flange portion 41. Subsequently, as shown in the figure, the sealing means 46 that has sealed one end 43 of the air supply pipe 40 is removed, and the air supply pipe 40 moves the air to the vicinity of the bottom corresponding cavity 5 ′ in the cavity 4. Supply naturally. At the same time, the suction is restarted, the pulp slurry 21 existing in the cavity 4 is discharged to the outside, and the pulp compact 22 is dehydrated. Thereby, similarly to the case of the first embodiment,
The deposited pulp fibers are effectively prevented from being disturbed by suction, and the thickness of the container to be formed becomes uniform.

When the pulp compact 22 has been dehydrated to a predetermined moisture content, the air supply pipe 40 inserted into the molding die 1 is pulled downward as shown in FIG. Thereafter, FIG. 2E and FIG. 5A in the first embodiment
A hollow container with a bottom having a mouth and a neck is obtained by the same operations as those shown in FIGS.

Although the present invention has been described based on the preferred embodiments, the present invention is not limited to the above embodiments.
For example, depending on the size and number of the communication holes 3 formed in the split mold 2, a papermaking net may not be used. Further, the core 33 may be inserted into the pulp molded body 22 without removing the formed pulp molded body 22 from the papermaking mold 1, and the pulp molded body 22 may be dehydrated and dried. In addition, as each split mold 2 in the molding die, one in which the manifold part 7 is divided into a plurality of independent areas is used, and the degree of suction of the pulp slurry is adjusted for each manifold part, so that the pulp molded body 22 is formed. The thickness may be made more uniform. Further, as the molding die, one having the same cross-sectional shape of the pulp slurry inflow portion and the cavity portion corresponding to the mouth and neck portion, that is, the same cross-sectional area may be used.

[0036]

According to the present invention, a pulp mold container having a uniform thickness without variation in product shape and dimensional accuracy can be obtained. In addition, a pulp mold container having good inner and outer surface properties and excellent appearance can be obtained. Further, a container having a complicated shape such as a tall container, a container having no draft angle, a container having a cubic curved surface, a container with or without a bottom can be formed.

[Brief description of the drawings]

FIG. 1 shows the first method of the present invention for producing a pulp mold container.
It is a figure which shows the shaping | molding die preferably used for embodiment.

FIGS. 2A and 2B are process diagrams sequentially showing a first half of a process of manufacturing a pulp mold container, wherein FIG. 2A is a process of inserting an air supply pipe into a molding die and immersing the molding die, and FIG. (C) is a process of supplying air into the cavity and dewatering the pulp molded body, (d) is a process of pulling up the mold and pulling out the air supply pipe, and (e) is opening the mold. This is the step of removing the pulp compact.

FIG. 3 is a process diagram sequentially showing the latter half of a process of manufacturing a pulp mold container, wherein (a) is a process of putting a pulp compact into a drying mold, and (b) is a core inserting process into a pulp compact. , (C) is a pressurization / dehydration / drying step of the pulp molded body,
(D) is a step of opening the drying mold, and (e) is a step of removing the pulp mold container.

FIG. 4 is a process chart sequentially showing a first half of a process of manufacturing a pulp mold container according to a second embodiment of the present invention,
FIGS. 3A to 3D are views corresponding to FIGS. 2A to 2D, in which FIG. 2A is a process of inserting an air supply pipe into a molding die and dipping the molding die, and FIG. (C) pulling up the mold, supplying air into the cavity and dewatering the pulp compact,
(D) is a process of extracting the air supply pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molding die 20 Split mold 3 Communication hole 4 Cavity 5 Mouth part corresponding to mouth and neck part 6 Pulp slurry inflow part 7 Manifold part 21 Pulp slurry 22 Pulp molded body 40 Air supply pipe 41 Flange part 45 Void

Claims (5)

[Claims] 1. A pulp slurry flow comprising a pair of split dies having a communication passage communicating from the inside to the outside, and abutting the split dies to form a cavity therein and open to the outside from the cavity. An air supply pipe is inserted into the cavity through the pulp slurry inlet from the outside of the molding die in which the inlet is formed, and the mold is oriented with the pulp slurry inlet facing downward. The pulp slurry is immersed in the pulp slurry inlet, the pulp slurry is sucked through the pulp slurry inlet, and pulp fibers are deposited on the inner surface of the cavity to form a pulp molded body, and the pulp slurry inlet is sealed. To stop the inflow of the pulp slurry, and supply air to the upper part of the cavity through the air supply pipe. After by suction the tee and dewatering the pulp molded article production method of molded pulp container to take out the pulp molded article by opening the mold along with pulling the air supply pipe. 2. The air supply pipe according to claim 1, wherein the air supply pipe has a flange.
A method for producing the pulp mold container according to the above. 3. The air supply pipe according to claim 2, wherein the air supply pipe communicates with the air supply section, and air is forcibly supplied from the air supply section into the cavity under a sealing state by the flange. Manufacturing method of pulp mold container. 4. The pulp mold container according to claim 2, wherein after the molding die is pulled up from the pulp slurry under a state sealed by the flange portion, air is supplied into the cavity by the air supply pipe. Production method. 5. The pulp mold container has a mouth-and-neck portion, and the pulp slurry inflow portion is formed outward from a mouth-and-neck portion corresponding cavity portion in the cavity of the molding die, and The method for producing a pulp mold container according to any one of claims 1 to 4, wherein a cross-sectional area of the pulp slurry inlet is smaller than a cross-sectional area of the mouth-and-neck cavity.