JP2000327049A - Low density paper container and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a low density paper container inexpensively and stably without using any chemical foaming agent. SOLUTION: A method for manufacturing a low density paper container comprises the processes of adding bulged state holding material E as a part of raw material in raw material liquid A0 having a pulp fiber P as a main raw material, making the raw material from the raw material liquid A0 into a specified sheet form, thereafter heating it with a heating and molding die 3 having a bulging-out allowing space G, gasifying at once moisture contained, expanding pulp fiber space, and keeping this state by the bulged state-keeping material E. The surface of the low density paper container A manufactured by such a method is laminated with a resin layer or the like as required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-density paper container and a method for producing the same, and more particularly to a method for inexpensively and stably producing a low-density paper container having heat insulating properties.

[0002]

BACKGROUND OF THE INVENTION Since hot water is often injected into a disposable container such as a simple beverage container or a cup ramen, heat insulation is required in consideration of convenience of use. . For this reason, a container made of a synthetic resin such as styrene foam (PS), a double structure or the like, or a paper container having an air layer has been conventionally applied to such a container. Of these, synthetic resin containers such as polystyrene foam have excellent heat insulation properties, are inexpensive to manufacture, and are suitable for mass production.However, they cannot be recycled, and when incinerated as garbage, toxic gases may be generated. There is a demand for a heat-insulating paper container because it is one of the causes of destruction and concerns are raised about the release of environmental hormones.

However, in order to impart heat insulation to a paper container, the above-described double structure or a structure for forming an air layer is required, which inevitably increases the manufacturing cost. There were certain limitations in terms of the required cost reduction. Of course, as another method of providing heat insulation to a paper container, a method of reducing the density by foaming the paper itself is generally known.
In each case, the foaming agent is mixed into the raw material liquid, and the foaming agent itself may have an adverse effect on the subsequent treatment, and in practice, stable production is difficult, and there are trials at the research stage. Has not been put to practical use yet.

[0004]

[Technical Problems Attempted to Be Developed] The present invention has been made in view of such a background, and it is possible to manufacture low-density paper containers inexpensively and stably without using any chemical blowing agent. It attempted to develop a new method that could be used.

[0005]

That is, according to the method for manufacturing a low-density paper container according to the first aspect of the present invention, a raw material liquid containing pulp fibers as a main raw material contains a puffing maintaining material as a part of the raw material. After the raw material is extruded from the raw material liquid into a certain shape, the raw material is heated by a heating mold, and the contained water is vaporized at a stretch, thereby expanding the pulp fiber interval, and this state is expanded by the expansion maintaining material. It is characterized in that it is maintained. According to the present invention, the contained water is vaporized at a stroke, the pulp fiber interval is expanded, and the expanded state is maintained by the expanded maintenance material.
A low-density paper container having sufficient heat insulating properties can be manufactured without using any chemical blowing agent.

According to a second aspect of the present invention, there is provided a method for manufacturing a low-density paper container, wherein in addition to the requirements of the first aspect, the expanded maintenance material includes synthetic fibers such as rayon, biodegradable resin, polyester fiber, and polypropylene fiber. One or more of which are used. According to the present invention, the state of the expanded pulp fiber can be almost certainly maintained, and an appropriate expansion maintaining material can be selected according to the use conditions of the low density paperboard.

According to a third aspect of the present invention, in addition to the requirements of the first or second aspect, the mixing ratio of the expansion maintaining material is about 20% by volume of the whole raw material liquid.
About 80%.
ADVANTAGE OF THE INVENTION According to this invention, the state of the expanded pulp fiber can be maintained effectively.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a low-density paper container, wherein the method comprises the steps of:
The heat molding die has a swelling allowable space. According to the present invention, the container can be expanded to an appropriate thickness, and a low-density paper container having sufficient heat insulating properties can be stably manufactured at low cost.

Furthermore, a low-density paper container according to claim 5 is characterized by being manufactured by the method according to claim 1, 2, 3, or 4. According to the present invention, the moisture contained is vaporized at a time, the pulp fiber interval is widened, the expansion maintaining material enters between the pulp fibers, and the expanded state is almost certainly maintained, so that sufficient heat insulating property is obtained. Granted.

The low-density paper container according to claim 6 is characterized in that, in addition to the requirements described in claim 5, the low-density paper container has a resin layer laminated on the surface thereof. ADVANTAGE OF THE INVENTION According to this invention, the water resistance of a container surface, oil resistance, etc. can be improved as needed, a container can be protected positively, and various containers with various variations can be provided.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In the description, the low-density paper container A of the present invention will be described first, and then an example of an apparatus for manufacturing the low-density paper container A will be described. A method of manufacturing a density paper box will be described. First, the low density paper container A of the present invention will be described. This is a simple paper container, such as a cup-shaped container as shown in FIG. 2A, in which hot water is often poured when eating and drinking instant noodles, instant soups and the like. It is used as a tray-shaped container or the like as shown in FIG. 2 (b), which is packed with hot side dishes, lunch boxes, and the like, and is required to have heat insulation as a prerequisite. As shown in FIG. 1, the internal structure of the low-density paper container A is such that pulp fibers P as a main raw material are spread at substantially constant intervals, and a puffing maintenance material E described later enters between the pulp fibers P. The pulp fibers P are formed so as to maintain an expanded state, and as a result, are formed in a multilayer state having a so-called bulky property having many spaces between the pulp fibers P. The method of forming the paper container in a low-density state in this manner is based on the solution A
This is greatly different from the conventional method of mixing a foaming agent into the raw material and chemically foaming the raw material in that no chemical foaming agent is used.

Here, the pulp fibers P, which are the main raw materials of the low-density paper container A, include pulp fibers such as NBKP (softwood pulp), LBKP (hardwood pulp), and kenaf stalk pulp alone or in an appropriate combination in various ratios. Can be used.
For example, one or more of synthetic fibers such as rayon, biodegradable resin, polyester fiber, and polypropylene fiber are used as the expansion maintaining material E mixed in the raw material liquid A0. The biodegradable resin is a resin that can be decomposed in the natural world when it is literally discarded.
This includes a type in which the resin itself is completely decomposed by living organisms, and a type in which biodegradable substances (for example, starch etc.) are mixed with resin that is difficult to decompose to impart disintegration. In the form, as an example, the former type BI
ONOLLE "Bionore" (registered trademark sold by Showa Polymer Co., Ltd.) and the latter type of Mater-Bi "Matterby" (registered trademark sold by Nippon Synthetic Chemical Industry Co., Ltd.)
Etc. may be applied. The mixing ratio of the expansion maintaining material E is about 20% to 80% of the whole raw material liquid A0 in volume ratio.
It is about. A raw material liquid A containing pulp fiber P as a main raw material
In addition to the expansion maintaining material E described above, it is also possible to add a fluororesin or the like that improves the oil resistance and water resistance of the low-density paper container A itself.

Next, an example of an apparatus for manufacturing the above-described low-density paper container A will be described. The low-density paperboard manufacturing apparatus 1 includes:
As an example, as shown in FIG. 1, a papermaking apparatus 2 for papermaking an intermediate paper product A1 from the above-mentioned raw material liquid A0, and the residual water contained therein is vaporized at a stroke by heating this papermaking intermediate paper product A1. And a thermoforming mold 3 for enlarging the pulp fiber interval of the intermediate paper product A1.
Hereinafter, the outline of each component will be described.

The papermaking apparatus 2 converts the raw material liquid A0 to the liquid component L
And a pulp fiber P as the main component in the intermediate paper product A
1 is an apparatus for producing the same. The main component is a cylindrical paper-making cup 21 having an appropriate volume according to the specifications of the product to be paper-formed. Below the paper-making cup 21, a suction device such as a vacuum pump for extracting the liquid component L is appropriately connected. You. In the lower part of the papermaking cup 21, a number of drain holes 22 are provided.
a is provided, and the supporter 22
A carrier net 23, which is a mesh type of the intermediate paper product A1, is held on the upper part of the container.

The heat forming die 3 is a so-called expansion device, which evaporates the water contained in the intermediate paper product A1 at a stroke, widens the pulp fiber interval and lowers the density of the intermediate paper product A1, and is a so-called expansion device. It comprises a heating mold 31 for heating A1 and a steam removal mold 32 for releasing steam generated from the heated intermediate paper product A1 to the outside. The heat forming die 3 has, as an example, a steam release die 32 placed in a fixed state, and a heating die 31 provided above and below the vapor release die 32 so as to be movable up and down. The heating mold 31 includes a heater or the like that heats to about 150 ° C. to about 230 ° C. as an example at the time of heat molding. On the other hand, the steam removal mold 32 includes a plurality of pieces formed radially from substantially the center of the intermediate paper product A1. The steam vent hole 32a is provided so as to discharge water vapor uniformly and accurately.

The heating mold 31 and the steam release mold 32 which constitute the heating mold 3 are used for carrying out heat molding while maintaining a substantially constant space.
1 to expand to a desired thickness, and this space is hereinafter defined as expansion allowable space G. Incidentally, the expansion allowable space G is the final desired thickness of the low-density paper container A and the raw material liquid A.
Although it depends on various conditions such as a dispensing ratio of 0, a gap size of at least 2 mm is required, and in this embodiment, it is set to about 5 mm as an example. Further, in addition to the above-described embodiment, if necessary, for example, the steam removal mold 32 may be heated by a heater or the like, or the heating mold 31 may be heated.
Various forms, such as a form in which the steam vent hole 32a is formed, can also be adopted.

Next, a method for manufacturing a low-density paper container of the present invention will be described, while explaining a manufacturing mode of the low-density paper container manufacturing apparatus 1 configured as described above. (1) Intermediate Papermaking Step In papermaking the intermediate paper product A1, first, the raw material liquid A
0 is taken out by a fixed amount by a separately provided raw material supply device and put into the papermaking cup 21. Thereafter, suction is performed downward by the suction device, and the pulp fibers P in the raw material liquid A0 are sucked.
And an additive such as a swelling maintaining material E or a fluorine resin are formed on the carrier net 23 to form a web-like layer having a substantially constant thickness. It is withdrawn from the liquid drain hole 22a and further drained downward. When the outflow of the liquid component L is completed, the solid having a predetermined shape, that is, the intermediate paper product A1 is removed from the papermaking device 2, and is transferred to the next heat forming die 3 by an appropriate transfer device. Here, "the end of the flow of the liquid component L" does not mean that all the water contained in the intermediate paper product A1 flows out, but indicates a draining state including a certain amount of water. Accordingly, appropriate moisture remains between the pulp fibers P constituting the intermediate paper product A1.

(2) Heat Forming Step In the heat forming step, the intermediate paper product A1 produced in the intermediate paper forming step is first set in a steam release mold 32, and then, as an example, to about 150 ° C. to 230 ° C. The heated heating mold 31 is brought close to the steam removal mold 32 by a separately provided shifter device or the like, and heat molding is performed in a state where the heating mold 31 is finally fitted. This heat molding is performed by the heating mold 31.
And the steam release mold 32 are performed while maintaining the expansion allowable space G for expanding the intermediate paper product A1 to a desired thickness, and the residual moisture contained in the intermediate paper product A1 is heated. The pulp fibers P are vaporized at once by the heat applied from the mold 31 to increase the pulp fiber spacing, and the expansion maintaining material E enters between the pulp fibers P to maintain the expanded state of the pulp fibers P. Of course, the vaporized water vapor is discharged to the outside through a vapor vent hole 32a formed in the vapor vent mold 32. The expansion width of the pulp fiber interval does not always match the expansion allowable space G, but is regulated to the expansion allowable space G and is formed to be almost the same or somewhat smaller. The low-density paper container A thus obtained
As an example, as shown in FIG. 1, the internal structure of the pulp fiber P is formed in a multi-layered form, and the swelling maintaining material E enters between the layers of the pulp fiber P. Heat insulation is provided. The obtained low-density paper container A is further dried, if necessary, or for the purpose of improving water resistance, oil resistance, etc., as shown in FIG. The laminate processing of F is performed. Of course, this resin layer F is preferably a harmless material such as PET resin for the purpose of the product. In addition to such lamination, for example, a form in which persimmon astringent or the like is coated on the surface of a paper container, which is known as an effect as a natural preservative or waterproofing agent, may be used. Further, when the strength of the low-density paper container A itself is concerned, a form in which sack-attached paper a is applied as a shape-retaining strength member to almost the entire circumference of the container as shown in FIG. 2A is also possible. In this case, sufficient reinforcement can be achieved at low cost.

[0019]

According to the present invention, the moisture contained in the intermediate paper product A1 is vaporized all at once, thereby increasing the pulp fiber spacing,
Since this expanded state is almost certainly maintained by the expansion maintaining material E, a low-density paper container A having sufficient heat insulating properties can be manufactured inexpensively and stably without using any chemical foaming agent. Further, as the expansion maintaining material E, an appropriate material can be selected according to the use conditions of the low density paper container A and the like. Further, by performing lamination processing or the like on the surface of the completed low-density paper container A as required, water resistance, oil resistance, and the like can be improved, the paper container is actively protected, and variations are abundant.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing step by step a method for manufacturing a low-density paper container of the present invention.

FIG. 2 is a perspective view showing a low-density paper container of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Low density paperboard manufacturing apparatus 2 Papermaking apparatus 3 Heat forming mold 21 Papermaking cup 22 Supporter 22a Liquid drainage hole 23 Carrier net 31 Heating type 32 Steam drainage mold 32a Steam drainage hole A Low density paperboard A1 Intermediate paper product A0 Raw material liquid a Paper E Material F Resin layer G Swelling allowable space L Liquid component P Pulp fiber

Continuation of front page (72) Inventor Yukio Sugimoto 822-3 Sakamoto, Shimada-shi, Shizuoka F-term (reference) 3E067 AA03 AB01 BA07A BA10A BB01A BB14A BC02A BC03A CA18 FA01 FC01 GA11

Claims (6)

[Claims] 1. A raw material liquid containing pulp fiber as a main raw material, a puffing maintaining material is included as a part of the raw material, and the raw material is extracted from the raw material liquid into a predetermined shape, and then heated. A method for producing a low-density paper container, characterized in that the interval between pulp fibers is increased by heating the mixture in a molding die to vaporize moisture contained therein, and this state is maintained by the expansion maintaining material. 2. The method according to claim 1, wherein one or more of synthetic fibers such as rayon, biodegradable resin, polyester fiber and polypropylene fiber are used as the expansion maintaining material. Manufacturing method of low density paper box. 3. The method for manufacturing a low-density paper container according to claim 1, wherein the mixing ratio of the expansion maintaining material is about 20% to 80% of the whole raw material liquid by volume ratio. 4. The method for manufacturing a low-density paper container according to claim 1, wherein the heat-molding mold has an expansion-allowed space. 5. A low-density carton manufactured by the method according to claim 1, 2, 3 or 4. 6. The low-density paper container according to claim 5, wherein the low-density paper container has a resin layer laminated on a surface thereof.