JP2001234500A - Method for producing molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing a molded article which has excellent shock absorbing characteristics and is scarcely deformed, even when a heavy article to be used as an article to be shock-absorbed is loaded on the molded article. SOLUTION: This method for producing the molded article, characterized by supplying a slurry comprising a composition having a Canada standard freeness(CSF) of >=550 ml into a mold having many small holes in the walls, removing water used as the medium of the slurry from the small holes, depositing small-impermeable fine components in the slurry on the inside of the mold to form the wet molded article, pressing the wet molded article in the mold to enhance the density of the maximum compressed place to >=1.1 times that of the non-compressed wet molded article, and then allowing heated air to flow in the deposition layer of the molded article to dry the molded article.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a molded article exhibiting excellent characteristics with respect to a heavy buffer (enclosed product).

[0002]

2. Description of the Related Art Styrofoam conventionally used as a cushioning material for packaging has excellent shock absorbing properties, can be easily processed into an arbitrary shape, is inexpensive, lightweight, and has a good appearance. It has the following characteristics. However, in recent years,
As interest in environmental issues has increased, there has been an increasing demand for disposability after use, as with other so-called plastic products. In other words, it has been pointed out that when incinerated after use, damage to the furnace and generation of toxic gas due to generation of high temperature are pointed out. Further, when the landfill treatment is performed, it is considered to be one of the causes of shortage of the treatment plant because it is not decomposable and is bulky.

As a solution to the problem in the processing of styrofoam, the inventors of the present invention have proposed, before the filing of the present application, that “water, which is a medium of slurry, is passed through a small hole of a mold having a large number of small holes on a wall surface. Removing the porosity impervious component of the slurry into the mold by removing the slurry, forming a wet molded article using the slurry having a Canadian Standard Freeness (CSF) of 550 ml or more; Then, a method for producing a molded article obtained by drying the molded article in or out of the mold "and a pulp-based low-density molded article obtained by the wet method and having excellent thickness and cushioning property (trade name: Green Pal: manufactured by Oji) Various proposals have been made.

[0004]

However, the low-density molded article having a high air permeability obtained by depositing fine components such as pulp like the above-mentioned low-density molded article has a comparative advantage in terms of an object to be buffered (a product to be wrapped). If it is light and lightweight, it can exhibit excellent cushioning properties and be an excellent packaging material.
If is a heavy object, because the deformation of the molded body gradually progresses with the passage of time due to the load, when the packaged goods are stored in several stacked layers, so-called stacked storage, There is a problem that the cargo may fall down. SUMMARY OF THE INVENTION An object of the present invention is to provide an efficient method for producing a molded article having excellent buffer characteristics and having less deformation even when a heavy object is used as a buffer.

[0005]

Means for Solving the Problems As a result of intensive studies in view of the present situation, the inventors of the present invention have performed a pressurizing process on a molded product in a wet state in a molding die to a certain degree or more, and then a specific method. The present inventors have found that a buffering material with little deformation under a load can be obtained while maintaining excellent buffering properties without substantially lowering the production efficiency by drying with, and the present invention has been completed. That is, the present invention
A slurry comprising a composition having a Canadian Standard Freeness (CSF) of 550 ml or more is supplied into a mold having a large number of small holes in a wall surface, and water, which is a medium of the slurry, is removed from the small holes. The fine components that do not pass through the small holes are deposited in a mold to form a wet molded article, and then the wet molded article is subjected to a pressure treatment in the mold so that the density at the maximum compression point is reduced before the pressurization. And then drying by flowing heated air into the deposited layer of the molded article after increasing to 1.1 times or more of the molded article. In particular, it is preferable to dry under the condition that the heated air flows at a flow rate of 1 liter / cm ² · min or more in the deposited layer of the molded product. Further, it is preferable that the molded body has a portion of the deposited layer having a thickness of 10 mm or more. Further, it is preferable that the main raw material of the slurry composition is a fiber. Especially, it is preferable that the fiber is a cellulosic fiber.
The slurry composition preferably contains thermoplastic synthetic fibers and cellulosic fine fibers as components.

A cause of the success of the present invention is that when wet molding is performed using a highly drainable slurry composed of a composition of 550 ml or more of Canadian Standard Freeness (CSF), a certain amount or more of compression treatment is performed in a wet state and dried. Thus, it has been found that a molded article having very little deformation can be obtained even when a heavy object is used as an object to be buffered, without impairing the buffer characteristics. Further, in the case of a wet molded product obtained from this highly drainable slurry, even if compression treatment is performed before drying, and since it has an unexpectedly high air permeability, the wet molded product is deposited in the deposited layer of the wet molded product. The point is that it has been found that drying can be performed very efficiently by a method of flowing heated air.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings to specifically show the present invention, but the present invention is not limited thereto. In addition, here, description will be made using pulp slurry, but the raw material of the present invention is not limited to this. FIG. 1 is a perspective view showing a concave mold 10 used for manufacturing a molded article of the present invention, and FIG. 2 is a cross-sectional view of the concave mold 10 shown in FIG. As shown in FIG. 2, the forming die used is a concave type having an open top having a double wall, and has a convex portion on a bottom surface 12 and a large number of small holes 11 for dehydration on an inner wall. Further, a suction chamber 13 is formed by the inner and outer double walls, and a suction port 14 is attached to the bottom of the outer wall.

FIGS. 3 to 6 are cross-sectional views showing steps of forming a pulp-based molded body of the present invention using the concave mold 10 shown in FIG. In the present invention, after the surrounding frame 15 for slurry storage is mounted on the upper part of the forming die 10, as shown in FIG.
The pulp slurry 17 having good drainage is supplied from the guide 16 into the cavity formed by the above. next,
As shown in FIG. 4, suction port 1 at the bottom of mold 10
The pulp deposit 19 is formed in the mold by suction dehydration from Step 4. At that time, the pulp is deposited so as to protrude from the open surface of the mold as shown in the figure and rise. Numeral 18 denotes a water droplet that has oozed out by suction.

[0009] Next, as shown in FIG.
Resection at 0 and trim the surface. At this time, the suction from the suction port 14 is continued. Subsequently, as shown in FIG.
By pressing the upper die 21 having a plurality of small holes 22 for injecting hot air having a convex portion 23 for pushing into the bottom surface and pressing it, the density of the maximum compression portion 26 becomes 1.1 before pressing. Then, the hot air is sent from the hot air inlet 24 of the upper die 21 while being sucked from the suction port 14 and dried. Drying is extremely fast. Reference numeral 25 denotes a molded body during drying. The thus obtained pulp-based molded body 27 shown in FIG. 7 is a molded body having a maximum compression portion 26 at the center, has excellent buffer characteristics, and has a small deformation even when a heavy object is used as a buffered object. .

The present invention will be described in more detail. As the mold, a concave mold having one surface open as described above is usually used. As the small holes of the mold, usually a diameter of 1 to 10
mm is used, and the mold is formed on the surface of a mold having small holes like a pulp mold.
A mold having a wire mesh of 5 to 200 mesh is usually used.

As the main raw material of the slurry composition, fibers, coarse powders and fine particles composed of an environmentally friendly natural organic polymer are usually used. In addition, synthetic organic polymers, semi-synthetic organic polymers, inorganic substances and The effect of the present invention can also be expected in the case of a molded article mainly composed of fibers, coarse powder, fine particles, etc. made of an organic-inorganic composite material. These raw materials are used alone or in combination. Among them, preferred as a main raw material are fibers from which a molded article with good performance can be obtained, and among them, natural organic polymer fibers are particularly preferred because they are also excellent in environmental aspects.

As natural organic polymer fibers, for example,
(1) Unbleached or bleached chemical pulp obtained by kraft pulping, sulfite pulping, alkali pulping of coniferous or hardwood, mechanical pulp such as GP, TMP (thermomechanical pulp), cotton pulp, linter Pulp, used paper pulp, liquid ammonia-treated pulp, mercerized pulp, and curled fiber which have been subjected to at least one of water repellency, water resistance, and curing described in Japanese Patent Application No. 10-0322920. Product name: HBA-FF, NHB405, NH, manufactured by Warehauser, USA
B416), cellulosic fibers such as hemp fiber described in Japanese Patent Application No. 10-377923, (2) protein fibers such as wool, silk, and collagen fibers, (3) chitin / chitosan fibers and alginic acid fibers. And the like. Among them, cellulosic fibers are particularly preferable because they are excellent in performance and easy to procure.

In the slurry composition, materials are appropriately selected and blended according to the required characteristics of the molded article. When it is desired to increase the interlaminar strength of the molded body, the number average fiber length obtained by fibrillating the cellulose fibers with a sand grinder or the like is a cellulose-based fine fiber in the range of 0.01 to 0.80 mm, or a polyethylene fiber, Polypropylene fiber,
It is effective to mix thermoplastic synthetic fibers such as polyethylene-polypropylene sheath core fibers and biodegradable aliphatic polyester fibers. Above all, a combination of cellulose-based fine fibers and thermoplastic synthetic fibers is particularly preferable because a molded article having less deformation and excellent surface smoothness can be obtained. In addition, as the thermoplastic synthetic fiber, a short fiber having a number average fiber length in a range of 2 to 20 mm, which is easily dispersed in preparing a slurry, is particularly preferable. These cellulosic fine fibers or thermoplastic synthetic fibers are used alone or in combination of two or more, and are usually blended in a range of 2 to 40% by dry weight with respect to the composition.

The slurry composition may further contain an adhesive, a waterproofing agent, a water repellent, a dye, a pigment, a drainage improver, a pH adjuster, a slime control agent, a thickener, and the like, if necessary.
Preservatives, fungicides, antibacterial agents, flame retardants, rodenticides, insecticides, humectants, freshness preservatives, oxygen scavengers, foaming agents, surfactants, electromagnetic shielding materials, antistatic agents, rust inhibitors, fragrances ,Deodorants,
Various microcapsules having foaming properties and aromatic properties can be selected and blended. These may be used in combination of two or more.

As the slurry composition of the present invention, a Canadian Standard Freeness (CSF) having good drainage of 550 ml or more is used. Incidentally, in the present invention, JIS-P-8 is used.
The Canadian Standard Freeness of the slurry composition was measured by the method based on No. 121.

The slurry is usually prepared batchwise or continuously by using an apparatus having a stirrer. Water is usually used as a medium used for forming a slurry, but a mixture of water and an alcohol (such as methanol or ethanol) can also be used. The concentration of the slurry is usually adjusted so that the dry solid content is in the range of 0.05 to 10% by weight, but preferably in the range of 0.05 to 3% by weight in terms of the dispersed state.

The injection of the slurry into the concave mold is performed by a known method. Examples of the method for removing the medium of the slurry from the small holes include a suction dehydration method, a gas pressure dehydration method, a mechanical pressure dehydration method, an electroosmotic dehydration method, and the like, and these can be combined. The dehydration conditions can be changed during the dehydration. The type of slurry used for injection is usually one type, but the injection of slurry is divided into two or more stages, and by changing the composition of the slurry used at that time, a state in which deposited layers of different compositions are sequentially laminated. Molded articles can also be obtained.

In the present invention, the molded article in the wet state after the dehydration treatment is subjected to a pressure treatment in a mold so as to increase the density at the maximum compression point so as to be 1.1 times or more that before the pressure. After drying, the molded body of the present invention is dried by 10%.
In the case of an object to be buffered (wrapped product) that generates a place where a load of 0 g / cm ² or more is applied, pressurize it so that the density of the maximum compression place is 1.5 times or more that before pressurization. Is desirable.

In the case of the wet molded product obtained from the highly drainable slurry of the present invention, even if it is subjected to a compression treatment before drying, it still has an unexpectedly high air permeability. It is much more efficient to flow heated air into the deposited layer of the wet molded product than to dry the surface by irradiating infrared rays or microwaves from the surface. Specifically, inject heating air into a wet molded product, suction while supplying heating air from the opposite side of the molded product, and inject heating air into the wet molded product from the opposite side of the molded product. For example, a method of suctioning can be used. Further, it is also possible to adopt a method of irradiating the molded article with microwaves at the same time as supplying the heated air by the above method. As a method of increasing the drying efficiency, a method of improving the flow of air by piercing or non-penetrating a hole in the molded article at the time of the through-air drying is effective. In the present invention, in consideration of the production efficiency of the molded product, it is preferable that the drying be performed under the condition that the heated air flows in the deposition layer of the molded product at a flow rate of 1 liter / cm ² · min or more. Particularly preferably, it is 5 liter / cm ² · min or more.

The molded article of the present invention can contain the above-mentioned adhesive by means of spraying, impregnation, coating or the like in order to prevent the fibers from falling off and to increase the strength. In addition, if necessary, a water-resistant agent, a water-repellent agent, a dye, a pigment, a preservative, a fungicide, an antibacterial agent, a flame retardant, a rodenticide, an insect repellent, a freshness-retaining agent, a deoxidizer, an electromagnetic shielding material , An antistatic agent, a rust preventive, a fragrance, a deodorant and the like can be incorporated by the same means.

Among the molded articles of the present invention, those having a portion of the deposited layer having a thickness of 10 mm or more are more preferable because they exhibit extremely good buffer characteristics.

The molded article of the present invention may be a paper tube (square paper tube, hollow L paper tube, round paper tube, paper ring mat), corrugated cardboard, laminated corrugated cardboard, paper honeycomb structure, waste paper board, fiber board, if necessary. It is used in combination with other materials such as particle board, wood, synthetic resin film, synthetic paper, water-resistant paper, water-repellent paper, and metal foil such as aluminum.

The molded product of the present invention can be used not only as a cushioning material but also in other fields. Hereinafter, the present invention will be described more specifically with reference to examples. However, needless to say, the present invention is not limited to these examples. In Examples and Comparative Examples, “parts” and “%” indicate “parts by weight” and “% by weight” unless otherwise specified.

<Example 1> Jute hemp bags were cut with a cutting machine for 20 minutes.
After cutting to a cm square, a crusher (V-36, manufactured by Horai)
0), followed by a treatment for softening the fibers with a grinder mill (manufactured by Glow Engineering, GM4-25) to obtain hemp fibers having a number average fiber length of 6 mm. When the Canadian standard freeness of this fiber was measured, it was 758.
ml. Further, a water slurry of used newspaper pulp having a solid content of 1% was mixed with glass beads having an average particle size of 2 mmΦ by 8%.
Sand grinder for 1.5 liters filled with 0% (Dynomill KDL manufactured by Shinmaru Enterprises)
-PILOT) at a flow rate of 350 ml / min to obtain fine fibers having a number average fiber length of 0.26 mm.
Next, 90 parts of the hemp fiber (dry weight) and 3 parts of the fine fiber (dry weight) were further combined with a polyolefin fiber (manufactured by Chisso,
ESC-055) was mixed with 7 parts of water, water was added to adjust the solid content concentration to 1.5%, and the mixture was sufficiently stirred to obtain a slurry. The slurry composition was found to have a Canadian standard freeness of 695 ml. Next, a circular small hole having a diameter of 2 mm was provided on the entire inner wall so as to have an opening ratio of 10%, and a wire mesh of 40 mesh was further adhered to the entire inner wall. The square was 250 mm on a side and had a depth of 50 mm. A concave mold as shown by reference numeral 10 in FIG. 1 having cavities and having a square with a side of 150 mm and a height of 20 mm at the center of the bottom was prepared. Next, as shown in FIG. 3, a slurry storage enclosure 15 is mounted on the molding die 10,
The slurry was supplied from a guide 16 into a cavity formed by the mold 10 and a slurry storage enclosure 15. Subsequently, as shown in FIG. 4, suction dehydration is performed from a lower suction port 14 with a Nash pump set to a condition of a vacuum degree of 250 mmHg to deposit fibers so as to swell on the open surface of the mold. As described above, the tip saw 20 was moved horizontally to remove unnecessary portions of the deposits to form a smooth surface. Then, as shown in FIG.
The bottom that can be pushed to the depth of m has a flat convex part,
The density of the maximum compression point 26 is increased to 1.5 times that before pressurization by pressing and pressing a press upper die 21 having a large number of small holes 22 on the bottom surface. Hot air of 180 ° C. was fed from the hot air inlet 24 of the mold 21 and dried to obtain a molded body 27. The drying time was 4 minutes and 30 seconds. As a result of packing and evaluating a heavy object with the obtained molded body, it was found that the molded article had excellent buffer characteristics and was hardly deformed.

[0025]

As described above, according to the present invention, a molded product is formed by using a slurry composed of a composition having good drainage, and then the molded product in a wet state is subjected to a pressure treatment in a mold to determine the maximum compression point. After increasing the density to 1.1 times or more than before pressurization, it is a method of drying by flowing heated air into the deposited layer of the molded product, which has excellent properties as a cushioning material for packaging. Can be obtained efficiently.

[Brief description of the drawings]

FIG. 1 is a perspective view of a mold used for wet molding.

FIG. 2 is a cross-sectional view of the mold of FIG. 1 taken along the line AA.

FIG. 3 is a cross-sectional view showing a state in which a slurry storage enclosure is set on a mold, and then a slurry is supplied from a guide to fill the upper part.

FIG. 4 is a cross-sectional view showing a state in which the slurry is sucked and dehydrated from the state of FIG. 3 and pulp is deposited on a molding die.

FIG. 5 is a cross-sectional view showing a state in which an unnecessary portion deposited on an open surface of a mold is cut off with a tip saw.

FIG. 6 is a cross-sectional view showing a state in which a wet pulp molded product in a molding die is compressed by an upper die, and thereafter hot air is injected and dried.

FIG. 7 is a sectional view showing a pulp molded product after drying.

[Explanation of symbols]

10: concave mold, 11: small hole, 12: bottom of mold, 1
3: suction chamber, 14: suction port, 15: enclosure for slurry storage, 16: guide, 17: pulp slurry, 18: water drop, 19: wet pulp sediment, 20: chip saw, 21: press die , 22: small hole, 23: upper mold projection, 24: hot air injection port, 25: molded product during drying treatment, 2
6: Maximum compression point, 27: Dry molded product

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tomoyuki Fukuda 3-6-4 Sotokanda, Chiyoda-ku, Tokyo Inside Oji Bag Co., Ltd. F-term (reference) 3E066 AA01 BA01 CA05 KA08 MA01 4L055 BF07 BF08 EA05 EA25 EA26 EA40

Claims (4)

[Claims] The Canadian Standard Freeness (CSF) is 55
A slurry composed of 0 ml or more of the composition is supplied into a mold having a large number of small holes on a wall surface, and water as a medium of the slurry is removed from the small holes to remove small pore non-passing fine components in the slurry. It is deposited in a mold to form a wet molded article, and then the wet molded article is subjected to a pressure treatment in the mold so that the density of the maximum compression point is 1.1 times or more that before the press. A method for producing a molded article, characterized in that the molded article is dried by flowing heated air into a deposited layer of the molded article. 2. A heating air flow rate of 1 in the deposited layer of the molded product.
The method for producing a molded article according to claim 1, wherein the molded article is dried under a condition of flowing at a rate of liter / cm ² · min or more. 3. The method for producing a molded article according to claim 1, wherein the molded article has a location of a deposited layer having a thickness of 10 mm or more. 4. The method according to claim 1, wherein the main raw material of the slurry composition is a fiber.