JP2001226900A - Molded article and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing a fine component- deposited type molded article, having excellent cushioning characteristics and extremely little deformation even when a heavy material is used as a material to be cushioned. SOLUTION: Grooves or holes are provided at arbitrary positions of air permeable low-density molded article having wall thickness and formed as aggregate of fine component and a reinforcing agent is injected into these grooves or holes and the reinforcing agent is immersed and solidified in spaces between fine components of 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 molded article having excellent characteristics as a cushioning material for packaging and an efficient method for producing the same.

[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, recently, products made from natural fibers such as pulp, specifically, pulp are filled into a molding die by a wet method. Thick low-density molded product (trade name: Green Pal: manufactured by Oji Bags), and thick low-density molded product (trade name: Cell Mold:
Rengo)) and the like.

[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 a fine component-deposited molded article having excellent buffering properties and having extremely little deformation even when a heavy object is used as an object to be buffered. Another object of the present invention is to provide a method for efficiently producing the molded article.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies in view of the present situation, and have found that after providing a groove or a hole in a gas permeable low density molded article, a reinforcing agent is injected from the groove or the hole. The present inventors have found that it is possible to efficiently improve a molded product having extremely small deformation under a load by a simple method, and have completed the present invention. That is, the present invention provides a groove or a hole at an arbitrary position of a thick gas-permeable low-density molded body formed as an aggregate of fine components, and injects a reinforcing agent into the groove or the hole to form a molded body. A molded article characterized in that the reinforcing agent is permeated and solidified into voids between fine components, and a method for producing the molded article. In the present invention, the reinforcing agent is preferably a heat-fusible substance. Further, the air-permeable low-density molded body supplies slurry into a mold having a large number of small holes on a wall surface, and removes water as a medium of the slurry from the small holes so that small holes in the slurry do not pass. Fine components are deposited in the mold,
It is preferable that the molded product is formed by a so-called wet method which is made by drying after that. Above all, 550 ml of a slurry composition used for producing the gas permeable low-density molded product is used.
It is preferable to have the above-mentioned Canadian Standard Freeness (CSF). In the present invention, it is preferable that the air-permeable low-density molded article has a portion of a deposited layer having a thickness of 10 mm or more. Further, it is preferable that the main raw material of the air permeable low density molded body is a fiber. Especially, it is preferable that the fiber is a natural organic polymer fiber. Further, the natural organic polymer fiber is preferably a cellulosic fiber.

The success of the present invention is based on the fact that voids between fine components constituting a gas-permeable low-density molded article are filled with a solid reinforcing agent to increase the density of the molded article. That is, it has been found that it becomes a molded article. Further, as a treatment method for filling the voids between the fine components of the molded body with a solid reinforcing agent, first, a groove or a hole is provided in the molded body, and then a method of injecting the reinforcing agent from the groove or the hole is adopted. The point is that it has been found that permeation into the inside of the molded article can be remarkably accelerated as compared with the case where the treatment is simply performed from the surface of the molded article without providing a groove or a hole.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the air-permeable low-density molded article used in the present invention include a low-density molded article formed by a dry process, such as a cell mold (made by Rengo). A low-density molded product obtained by a wet molding method is preferable in that a small and stable product is easily obtained. Further, as a low-density molded body, one having a location of a deposited layer having a thickness of 10 mm or more is more preferable because it exhibits extremely good buffer characteristics.

Hereinafter, a low-density molded article formed by a wet method will be described in detail as a specific example, but the present invention is not limited to this. A gas-permeable low-density molded article formed by a wet method supplies slurry into a mold having a large number of small holes on a wall surface, and removes water, which is a medium of the slurry, from the small holes. It is obtained by depositing a fine component in a mold to form a wet molded article, and then performing a drying treatment. As the mold, a concave mold having one open surface is usually used. As the small hole of the molding die, a circular hole having a diameter of 1 to 10 mm is usually used, and the molding die has a surface of 15 to 200 mesh on the surface of the mold having the small hole like a pulp mold. A mold with a wire mesh is usually used.

As a main raw material of the slurry composition, fibers, coarse powders and fine particles composed of environmentally friendly natural organic polymers 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, or mechanical pulp such as GP, TMP (thermomechanical pulp), cotton pulp, linter Pulp, pulp that has been subjected to at least one of water repellency, water resistance, and hardening treatment, waste paper pulp that has been subjected to the treatment (Japanese Patent Application No. 10-0322920), liquid ammonia-treated pulp, and mercerization Pulp, curled fiber (product name: HBA-FF, manufactured by Warehauser, USA)
NHB405, NHB416), Japanese Patent Application No. 10-3779.
Cellulose fiber such as hemp fiber described in specification 23,
(2) protein fibers such as wool, silk and collagen fibers;
(3) Complex sugar chain fibers such as chitin / chitosan fibers and alginic acid fibers. 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 natural fibers with a sand grinder or the like is a fine fiber having a range of 0.01 to 0.80 mm, or a polyethylene fiber or a polypropylene fiber. It is effective to mix thermoplastic synthetic fibers such as polyethylene-polypropylene sheath core fibers and biodegradable aliphatic polyester fibers. Above all, as the synthetic fiber, a short fiber having a number average fiber length in a range of 2 to 20 mm, which is easily dispersed at the time of slurry preparation, is particularly preferable. The fine fibers or synthetic fibers 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.

The slurry composition of the present invention is preferably a Canadian standard freeness of 550 ml or more, which can efficiently form a molded product of a thick sedimentary layer having excellent buffering properties, and has a good filterability. By the way, Canadian standard freeness is JIS-P
Although the value is usually a value indicating the drainage of pulp specified in -8121, in the present invention, the drainage of the slurry composition was determined by the same measuring method.

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. Methods for removing the medium of the slurry from the small holes include, for example, a suction dehydration method, a gas pressure dehydration method, a mechanical pressure dehydration method, and an electroosmotic dehydration method, and a combination thereof. 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.

The wet molded product formed in the mold by dehydration is thereafter taken out of the mold or taken out of the mold and subjected to a drying treatment, but is dried in the mold to obtain a molded product with high dimensional accuracy. Is more preferred. Further, it is more preferable to apply a compression treatment to the molded product during drying in the mold or before the drying treatment, since a molded product which is less deformed by a load is obtained. As a drying method, for example, a known method such as hot air drying, infrared drying, and microwave drying can be used. Above all, hot air ventilation drying, in which heated air is forcibly passed through the inside of a molded product by injecting heated air into a wet molded product or sucking in while applying heated air from the opposite side of the molded product, has a drying speed of Fast and efficient.

According to the present invention, after a groove or a hole is formed in a molded article, a reinforcing agent is injected into the groove or the hole, and the reinforcing agent penetrates and solidifies into a space between fine components to be deformed by a load. Reforms to very few compacts. As a method of providing a groove or a hole in the molded body, a method of processing a molded body after drying with a drill, or a method of processing a molded body in a wet state before drying with a drill, a water jet, or the like is used. be able to. In addition, by using a molding die to which a protruding or plate-like structure is attached, it can be provided simultaneously with molding. The groove and the hole are provided in a penetrating state or a non-penetrating state with respect to the molded product. In the case of non-penetration, the depth of the groove and the hole is desirably at least 1/3 of the thickness of the molded product from the viewpoint of the effect. The shape and size of the groove and the hole are not particularly limited, but a groove having a width of 1 cm or less and a hole having a cross-sectional area of 1 cm ² or less are usually provided.

As the reinforcing agent used in the present invention, any reinforcing agent can be used as long as it can penetrate and solidify voids, for example, starch, processed starch, carboxymethylcellulose, hydroxyethylcellulose, vegetable gum, gelatin , Casein, PVA, urea resin adhesive, melamine resin adhesive, phenol resin adhesive, epoxy resin adhesive, vinyl acetate resin adhesive,
Cyanoacrylate adhesive, polyurethane adhesive,
α-olefin-maleic anhydride resin adhesive, aqueous polymer-isocyanate adhesive, reactive acrylic resin adhesive, vinyl acetate resin emulsion adhesive, vinyl acetate copolymer resin emulsion adhesive, EVA resin Emulsion type adhesive, acrylic resin type emulsion type adhesive, reactive type hot melt type adhesive, EVA type hot melt type adhesive, elastomer type hot melt type adhesive,
Polyamide hot melt type adhesive, chloroprene rubber type solvent type adhesive, synthetic rubber type solvent type adhesive, synthetic rubber type latex type adhesive, paraffin wax, etc., can be used alone or in combination. it can. These are usually injected by dissolving in water or a solvent, or as an emulsion, or in a liquid state as it is, or in the case of a hot melt type, by heat melting. Among the reinforcing agents, those which are heat-meltable, such as wax and hot melt resin, are particularly preferable because they can be solidified without subsequent treatment and are efficient. In the case of a water or solvent system, it can be dried and solidified by blowing normal or high temperature air into the molded body. The injection is performed under normal pressure or pressurized conditions. The injection is desirably performed on a heated molded body in which penetration of the molded body between fibers is easily promoted.

The reinforcing agent can be permeated into the voids between the fine components from the surface of the molded article by means of spraying, impregnation, coating or the like simultaneously with the injection from the grooves and holes.

Further, 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 deoxygenating agent may be added to the molded article. Agents, electromagnetic shielding materials, antistatic agents, rust inhibitors, fragrances, deodorants and the like can be incorporated by means such as spraying, impregnation, coating and the like.

The molded product obtained by the present invention is laminated with other materials such as synthetic resin film, synthetic paper, synthetic resin plate, waterproof paper, water-repellent paper, metal foil such as aluminum, metal plate and glass plate. Can be used. Processing such as cutting and printing can be performed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, 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 of a molding die 10 used for wet molding, and FIG. 2 is a cross-sectional view of the molding die 10 taken along the line A-A. As shown in FIG. 1, the mold 10 to be used has a concave shape with an open top having a double wall, and a large number of small holes 1 for dehydration are formed on the inner wall.
1 and a bottom surface 12 having a convex portion. Further, a suction chamber 13 is formed by an inner and outer double wall, and a suction port 1 is provided at the bottom of the outer wall.
4 are attached. FIG. 3 to FIG.
FIG. 1 is a cross-sectional view of an embodiment of the present invention made by using FIG. In the present invention, first, a slurry storage enclosure 15 is set on the molding die 10 as shown in FIG. 3, and then, inside a cavity formed by the molding die 10 and the slurry storage enclosure 15, A pulp slurry 17 having good drainage is supplied from an upper guide 16. Next, as shown in FIG. 4, the pulp sediment 19 is sucked and dehydrated from the suction port 14 at the lower part of the mold 10 into the mold.
Is formed. 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.

Next, as shown in FIG. 5, unnecessary portions protruding from the open surface of the forming die and deposited are cut off with a tip saw (disk-shaped blade) 20. Subsequently, as shown in FIG. 6, on a press machine having a flat bottom surface and a large number of small holes 22 for hot air injection on the smooth surface of the wet molded product whose surface has been smoothed by cutting with the tip saw 20. After the mold 21 is brought into close contact with the mold 21, hot air is sent from the hot air injection port 23 of the upper mold 21 to be dried. At this time, when the wet molded product is pressed and compressed by using the upper die 21 of the press machine and dried, a more remarkable effect of improving deformation due to load can be obtained. Numeral 24 is a molded product during drying.

Next, the dry molded product 25 thus obtained is
Next, as shown in FIG.
Then, as shown in FIG. 8, a reinforcing agent is injected into the hole 27 by using a nozzle 28 as shown in FIG. 8, and the reinforcing agent permeates and solidifies in the space between the fibers. When the reinforcing agent has a medium such as water, a drying treatment is performed after the injection. FIG. 9 is a sectional view showing the reinforced molded body 29 thus obtained.

As a method of forming a groove or a hole in a molded article,
In addition to the method of post-processing the molded body using a cutting device as described above, by using a molding die 30 to which a projection 31 (or a plate-shaped structure) as shown in a perspective view of FIG. A method of providing at the same time as molding can be adopted. 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> A jute hemp bag was cut into 20 pieces by a cutting machine.
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. The Canadian standard freeness of this fiber was measured to be 748.
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 0.28 mm.
Water was added to a mixture of 92 parts (dry weight) of hemp fibers and 8 parts (dry weight) of fine fibers obtained as described above to adjust the solid content concentration to 2%, and the slurry was sufficiently stirred to obtain a slurry. Obtained. The slurry composition was found to have a Canadian standard freeness of 653 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 having a cavity and having a concave-convex portion on the bottom as shown by reference numeral 10 in FIG. 1 was prepared. Next, as shown in FIG. 3, a surrounding frame 15 for slurry storage is mounted on the mold.
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 was performed from the lower suction port 14 to deposit fibers so as to swell on the open surface of the mold. Next, as shown in FIG.
Is moved horizontally to cut off unnecessary portions of the deposit to form a smooth surface, and then, as shown in FIG. 6, a press upper die 21 having a flat bottom surface and a large number of small holes 22 in the bottom surface. After being brought into close contact with the smooth surface, hot air was sent from the hot air inlet 23 of the upper mold and dried to obtain a molded product. Next, a diameter of 8 mm was applied to the obtained dry molded product using a drill as shown in FIG.
Then, a plurality of circular non-through holes were formed, and then, as shown in FIG. 8, paraffin wax in a molten state was injected from the holes to infiltrate the voids between the fibers. As a result of packing and evaluating a heavy object with the obtained molded article, it was found that the molded article had excellent buffer characteristics and was hardly deformed.

[0027]

As described above, according to the present invention, a groove or a hole is formed in a thick air-permeable low-density molded body formed as an aggregate of fine components, and a reinforcing agent is injected into the groove or the hole. This is a method of permeating and solidifying the reinforcing agent into the voids between the fine components of the molded product, whereby a material having excellent properties as a cushioning material for packaging can be efficiently obtained.

[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 where hot air is injected into a wet pulp molded product in a molding die and dried.

FIG. 7 is a cross-sectional view showing a state in which a cylindrical hole is formed in a dry molded product using a drill.

FIG. 8 is a cross-sectional view showing a state in which a reinforcing agent is injected from a hole made by using a drill using a nozzle, and penetrates and solidifies into a gap between pulp.

FIG. 9 is a cross-sectional view of a molded body after a reinforcing process is completed.

FIG. 10 is a perspective view showing a molding die to which a projection is attached.

[Explanation of symbols]

10: concave mold, 11: small hole, 12: bottom of mold, 1
3: suction chamber, 14: suction port, 15: enclosure for slurry reservoir, 16: guide, 17: pulp slurry, 18: water drop, 19: wet pulp sediment, 20: chip saw, 21: press die , 22: small hole, 23: hot air inlet, 24: molded product during drying treatment, 25: dry molded product, 2
6: Drill, 27: Column-shaped hole, 28: Reinforcement injection nozzle, 29: Reinforced molded body, 30: Mold with projection attached, 31: Projection

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shunsuke Shioi 4-7-5 Ginza, Chuo-ku, Tokyo Oji Paper Co., Ltd. F term (reference) 3E066 AA01 BA01 CA01 CA05 CA08 CB04 DB10 MA01 4L055 AF09 AG51 AH50 BF08 EA05 GA05

Claims (5)

[Claims] 1. A groove or a hole is provided at an arbitrary position of a thick gas-permeable low-density molded body formed as an aggregate of fine components,
A molded article and a method for producing the molded article, wherein a reinforcing agent is injected into the groove or the hole to allow the reinforcing agent to permeate and solidify in a gap between fine components of the molded article. 2. The molded article according to claim 1, wherein the reinforcing agent is a heat-fusible substance, and a method for producing the molded article. 3. The air-permeable low-density compact supplies a slurry into a mold having a large number of small holes in a wall surface, and removes water as a medium of the slurry from the small holes, thereby reducing the size of the slurry. The molded article according to claim 1 or 2, wherein the non-porous fine component is obtained by depositing the fine component in a molding die and then drying. 4. The molded article according to claim 3, wherein the composition of the slurry used for producing the breathable low-density molded article has a Canadian Standard Freeness (CSF) of 550 ml or more. 5. The molded article according to claim 1, wherein a main raw material of the air-permeable low-density molded article is a cellulosic fiber.