JP2001115399A - Method for producing molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a molded product having a complicated uneven shape and having the local irregularity of density by a wet method using a slurry. SOLUTION: This method for producing a molded product comprises accumulating a small hole-nonpassible fine component. Therein, an article (hereinafter referred as a sinking mold) capable of being pulled out and having a specific shape is disposed in the dented mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for wet production of a molded article having a complicated uneven shape.

[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.

[0003] As a solution to the problem in the processing of styrofoam, the inventors of the present invention removed water, which is a medium of slurry, from the pores of a mold having a large number of pores before filing the present application. A fine pore component in the slurry is deposited in a mold by using a slurry having a Canadian Standard Freeness (CSF) of 550 ml or more of the slurry composition, and then the wet molded product is formed. Various proposals have been made on a method for producing a molded article obtained by drying in or out of the mold, and a pulp-based low-density molded article having a large thickness and excellent buffering properties obtained by these methods.

[0004]

However, in the molding method using a slurry, when a concave mold having one open surface is used as a molding die, the open surface portion of the obtained molded body has an unintended shape. When it is pressed into the area by pressing an uneven mold to try to make it into the irregular shape of the intended shape, a large density difference occurs between the strongly compressed area and the weakly compressed area, resulting in a uniform density. There is a problem that a molded body cannot be obtained. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a good formed body having a complicated uneven shape and having no local density variation by a wet method using a slurry.

[0005]

In view of this situation, the present inventors have intensively studied a method for obtaining a good molded body having a complicated uneven shape by a wet method using a slurry. It has been found that this can be achieved by having an object of a specific shape that can be pulled out in a mold, and the present invention has been completed. That is, the present invention provides a method of forming a small hole in a slurry by supplying a slurry into a concave mold having a large number of small holes in a wall surface and opening the surface, and removing water as a medium of the slurry from the small hole. In a molding method in which the impervious fine component is deposited in the mold and then dried, when depositing the small-pore impervious fine component in the mold, an object having a specific shape that can be pulled out into the concave mold. Is a method for producing a molded article. In the present invention, a step of depositing the small-hole non-passing fine component in the slurry so as to have an unnecessary portion beyond the opening surface of the mold, and then cutting off the unnecessary portion in a dry or wet state during the molding Is preferred. In the present invention, the composition of the slurry is 550 m
Preferably, it has a Canadian Standard Freeness (CSF) of 1 or greater. In the present invention, it is preferred that the main component of the fine pore-impermeable fine component is a cellulosic fiber.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The mold used in the present invention includes a concave mold having a large number of small holes in a wall surface, one surface of which is open and which can be divided. As the mold, one having a depth of 10 mm or more is usually used to obtain a thick molded body, and one having a draft angle (taper) of 1 to 5 ° so that the molded body can be easily removed from the mold is usually used. Used. The small holes of the mold may have any shape such as a circle, an ellipse, a square, and a rectangle. As the size of the stoma,
When using a mold having a fine mesh attached to the surface thereof like a pulp mold, a considerably large one (for example, a circular hole having a diameter of 1 to 10 mm).
Can be used, but when wire mesh is not used,
The pores are preferably of such a size that almost no dispersed component in the slurry leaks, and circular pores having a diameter in the range of 0.5 to 2 mm are usually used. However, the present invention is not particularly limited. In addition, 15-
The one with 200 mesh is usually used. The size of the small holes can be changed depending on the location of the mold. Also, the small holes need not necessarily be present on the entire surface of the mold wall.
However, considering the dewatering efficiency etc., 40% of the mold wall
It is preferable that small holes are present in the above portions, and more preferably 70% or more. The number of small holes in the portion where the small holes are present is preferably 0.2 or more per cm ² , and more preferably 0.5 or more per cm ² . In the case of a deeper mold, in order to obtain a compact in a good deposited state, the opening ratio of the deepest part on the bottom surface (calculated as a value obtained by dividing the total area of the small holes by the wall area and multiplying by 100). It is preferable to make it the highest. By the way,
Although the maximum value of the porosity is not particularly limited, it is usually 70%.

In the present invention, while a sinking mold (a body of a specific shape that can be pulled out) is present in the concave mold, a pore impervious component in slurry is deposited and molded in the mold. As the sinking type, any material may be used as long as it is not deformed or deteriorated by the medium of the slurry. For example, metal, wood, plastic and the like can be used. The shape may be any shape as long as the shape can be pulled out from the molded body. Examples of the shape that can be easily pulled out include a rod shape. Among them, those having a taper for facilitating extraction are preferable. The hollow sinking die (16 in FIG. 7) having a small hole in the wall surface of the part below the open surface of the concave mold when set in the molding die is sucked from the suction opening of the sinking mold at the time of molding. The dewatering is more preferable because the deposition of the portion having the small holes on the surface is promoted and the smoothness of the portion is improved.

Injection of the slurry into the concave mold is performed by injecting the slurry using a pump from the open surface of the mold with the open surface facing upward, and into the slurry tank with the open surface facing downward as in a normal pulp mold. Soak the slurry into the mold from the downward open surface by immersing and sucking from the small holes.Suction while sinking the mold into the slurry tank with the open surface facing upward, and put the slurry into the mold from the open surface. Inhalation can be used. In the case of, in order to fill the small hole impervious component in the mold, the slurry must be injected by a pump while performing suction dehydration, so that the deposited layer is disturbed by the injected slurry, resulting in uneven density. However, as shown in FIG. 1, this problem can be ameliorated by mounting a slurry storage enclosure 15 on the mold 10 and storing the slurry in the enclosure, followed by suction dehydration.

As a method for removing the medium of the slurry from the small holes, there are a gas pressure dehydration method, a mechanical pressure dehydration method, an electroosmotic dehydration method and the like in addition to the suction dehydration method, and these can be combined. The dehydration conditions can be changed during the dehydration.

[0010] The sinking mold can be pulled out of the molded article in either a wet or dry state. However, the drawing after the drying treatment in which the unevenness formed by the sinking mold is likely to remain in a complete form is difficult. preferable. Above all, Japanese Patent Application Hei 10
As described in JP-A-49985, while pouring the slurry into the mold, the water, which is the medium of the slurry, is removed from the pores, so that the pore-impermeable fine components in the slurry are introduced into the mold. Depositing and forming with unwanted portions deposited beyond the mold open surface,
The molded article obtained by the method of cutting off the unnecessary portion of the molded article has a uniform density and is particularly preferable.However, when a sink mold is used in this method, it is formed by the sink mold when the sink mold is pulled out in a wet state. Since the uneven shape is easily disturbed in the cutting step, it is most desirable to extract the sinking mold after drying and then cut off the unnecessary portion.

Drying is usually carried out in a mold, but a known drying method such as hot air drying, infrared drying and microwave drying can be employed. For drying halfway, heated steam is also effective. To increase the drying speed, inject heated air into the wet molding,
Alternatively, it is effective to improve the flow of air in the voids between the small-hole non-passing components by, for example, sucking in the heated air from the opposite side of the molded article. Further, it is also effective to increase the surface area by intentionally forming irregularities on the surface of the molded product, or to improve the flow of air by forming a penetrating or non-penetrating hole in the molded product. As a method of forming irregularities or making holes in a molded product, there is a method of post-processing a wet molded product inside or outside a molding die by using a pressing press machine, a cutting machine, a water jet, or the like. A method of providing irregularities or protrusions on the bottom surface of the mold and imparting the shape to the molded product at the same time as molding is preferable in terms of productivity, aesthetic appearance, and the like. In addition, it is desirable to provide a draft angle (taper) as the projection so that the molded product can be easily taken out of the container. Also,
When drying in the mold, small holes are provided in the projections, and hot air is blown into the molded body using the holes, whereby the drying speed can be further increased. In addition, a method in which the mold is heated before pouring the slurry has an effect of increasing the drying speed.

Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. FIG.
6 to 6 are cross-sectional views showing an embodiment of the present invention. Here, description will be made using a pulp slurry as the slurry, but the raw material of the present invention is not limited to this. As shown in FIG. 1, the forming die 10 used is a concave shape having an open top having a double wall, having a large number of small holes 11 for dewatering on an inner wall, and a bottom surface 12 having a convex portion. Have. 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. In the step shown in FIG. 1, an enclosing frame 1 for storing slurry is further placed on the molding die 10.
5 is attached and the sinking type 1
The pulp slurry 18 having good drainage is supplied from the upper guide 17 in this state, and is filled up to the upper portion of the frame 15. Next, as shown in FIG.
The pulp deposit 20 is formed in the mold by performing suction dehydration from the suction port 14 at the lower part of the mold. At that time, the pulp is deposited so as to rise on the open surface of the mold. Reference numeral 19 denotes water droplets that have oozed out by suction.

Next, as shown in FIG. 3, the enclosing frame 15 for the slurry reservoir and the sinking die 16 are removed, and instead, FIG.
After the drying device 21 is set on the upper side, hot air is sent from the hot air port 23 and released from the small holes 22, thereby drying the wet pulp deposit 20. At this time, if suction is performed from the suction port 14, drying proceeds more efficiently.

Next, as shown in FIG. 5, an unnecessary portion of the dried pulp deposit 24 protruding from the mold opening surface is cut off with a tip saw 25. FIG. 6 shows the dry molded product 26 thus obtained. The removal of the sinking mold 16 can be performed after drying. In this case, the shape of the concave portion formed by the sinking type can be obtained with extremely high dimensional accuracy.

FIG. 7 shows a case in which a small hole 11 is formed in the wall surface of the tip portion.
Hollow submerged mold 16 with suction port 14 attached to the top
It is sectional drawing which shows the place where is used. The use of this type of sink mold is preferable because the slurry can be dewatered by suction from the tip wall surface during molding, and as a result, deposition on the surface is promoted and a denser surface can be obtained than in the case of the sink mold of FIG.

FIGS. 8 to 13 show a second embodiment of the present invention, which is different from the previous embodiment in that unnecessary portions are cut off before drying. This embodiment is efficient in terms of drying because unnecessary parts are removed before the drying step.However, since the cutting is performed before drying, the shape of the concave portion formed by the sinking mold tends to be distorted. is there.

The slurry composition used in the present invention is preferably a Canadian standard freeness of 550 ml or more, which can efficiently form a molded product having a thick sedimentary layer, and has good filterability. When a molded article is used as a buffer, a natural organic polymer fiber is usually preferably used as a main raw material. However, in the present invention, the present invention is not limited to this, and other synthetic organic polymer fibers, semi-synthetic organic polymer fibers,
Natural organic polymer coarse powder / fine particles, synthetic organic polymer coarse powder / fine particles, semi-synthetic organic polymer coarse powder / fine particles, inorganic fibers, inorganic coarse powder / fine particles, and fibers or coarse powders of organic-inorganic composite materials -Fine particles and the like can be mentioned, and can be appropriately selected according to the use. These may be used alone or in combination.

Incidentally, the Canadian standard freeness is based on JIS.
-P-8121 is usually a value indicating the drainage of pulp, but in the present invention, drainage of the slurry composition was determined by the same measurement method.

Hereinafter, the natural organic polymer fiber-containing system most suitable as a raw material of the buffer material will be described in more detail mainly, but the present invention is not particularly limited thereto. Examples of the natural organic polymer fiber include (1) unbleached or bleached chemical pulp obtained by kraft pulping, sulfite pulping, alkali pulping, etc. of softwood or hardwood, or GP, TMP (thermomechanical pulp) Mechanical pulp, cotton pulp, linter pulp, pulp that has been subjected to at least one of water-repellent, water-resistant, and hardening treatments, and waste paper pulp that has been subjected to the treatment (Japanese Patent Application No. Hei 10-1998).
032920 specification), liquid ammonia-treated pulp,
Mercerized pulp, curled fiber (product name: HBA-FF, NHB405, N, manufactured by Warehauser, USA)
HB416), cellulosic fibers such as hemp fibers 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. Natural organic polymer fibers typically have a dry weight of 35 to 100 relative to the composition.
%.

When it is desired to increase the interlayer strength of the molded product, it is effective to blend fine fibers having a number average fiber length of 0.01 to 0.80 mm obtained by fibrillating natural fibers with a sand grinder or the like. It is. The fine fibers are usually blended in a range of 2 to 40% by dry weight with respect to the composition.

When synthetic fibers having thermoplasticity such as polyethylene fiber, polypropylene fiber, polyethylene-polypropylene sheath core fiber, and biodegradable aliphatic polyester fiber are blended in the slurry composition, they are fused by heating to reduce the interlayer strength. Become stronger. The synthetic fiber is usually blended in a range of 5 to 60% 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,
Surfactants, preservatives, fungicides, antibacterial agents, flame retardants, rodenticides, insect repellents, moisturizers, freshness-retaining agents, oxygen absorbers, foaming agents,
Electromagnetic shielding materials, antistatic agents, rust inhibitors, fragrances, deodorants, various microcapsules having foaming properties, aromatic properties, and the like can be selected and blended. These can be used in combination of two or more.

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 the slurry, but other organic solvents such as alcohol, acetone, ethyl acetate, and glycerin, or a mixture of water and an alcohol (methanol or ethanol) can 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.
Are preferred.

The molded article of the present invention may contain an adhesive by means of spraying, impregnation, coating or the like in order to prevent fibers, coarse powder and fine particles from falling off and to increase the strength. Also,
If necessary, water-proofing agents, water-repellents, dyes, pigments, preservatives, fungicides, antibacterial agents, flame retardants, rodenticides, insect repellents, freshness-retaining agents, oxygen absorbers, electromagnetic shielding materials, electrification Inhibitors, rust inhibitors, fragrances, deodorants and the like can be included by similar means.

Examples of adhesives used for preventing fibers, coarse powder and fine particles from falling off and increasing the strength include, for example, starch,
Processed starch, carboxymethyl cellulose, hydroxyethyl cellulose, vegetable gum, gelatin, casein, PV
A, urea formaldehyde resin, melamine formaldehyde resin, polyamide urea formaldehyde resin, ketone resin, polyamide epichlorohydrin resin, polyamide polyamine epichlorohydrin resin, glycerol polyglycidyl ether resin, polyethylene imine resin,
SBR resin, acrylic resin, vinyl acetate resin, vinyl chloride resin, rosin-based resin, terpene-based resin, natural rubber, synthetic rubber, UV or EB cured resin, hot-melt resin, etc. can be used. They can be used in combination. These are usually applied 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 applying a hot melt. Above all, it is preferable to use an aqueous type, a UV or EB resin, or a hot melt resin in the working environment. The coating amount is usually 0.1% by dry weight.
1 to 30 g / m ² . After application, if necessary, hot air,
Drying and curing are performed using infrared rays, microwaves, ultraviolet rays, electron beams, or the like.

The obtained molded body can be made into a more complicated molded body by joining with another molded body obtained by using the same or a different molding die. The molded article can be used by sticking it on a corrugated cardboard or a cardboard box in the same manner as Styrofoam. In addition, a synthetic resin film, synthetic paper, a synthetic resin plate, water-resistant paper, water-repellent paper, metal foil such as aluminum, metal plate It can be used by bonding with materials such as glass plate. Further, the molded body may be subjected to processing such as cutting and printing. The method for producing a molded article using a sinking mold according to the present invention is particularly effective when applied to a concave mold having an open surface, but any method other than the above-mentioned concave mold is theoretically possible. Can be applied.

Hereinafter, the present invention will be described more specifically with reference to examples, but it is needless to say that 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 with a cutting machine for 20 times.
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 7 mm. The Canadian standard freeness of this fiber was measured to be 738.
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 0.30 mm.
The solid content concentration was adjusted to 2% by adding water to a mixture of 95 parts (dry weight) of hemp fibers and 5 parts (dry weight) of fine fibers obtained as above, and the slurry was sufficiently stirred to form a slurry. Obtained. The slurry composition was found to have a Canadian standard freeness of 692 ml. Next, one side is 25
With a 0 mm square, 50 mm deep cavities,
A convex portion was provided on the bottom surface, and round holes having a diameter of 0.5 mm were provided on the entire inner wall so that the opening ratio was 25%.
Is prepared, a surrounding frame 15 for slurry reservoir is mounted on the forming die, and a sinking die 16 is set in a form floating in the center of the forming die. The slurry was supplied as shown in FIG. Next, as shown in FIG. 2, suction dehydration was performed from the lower suction port 14 to deposit fibers so as to rise on the open surface of the mold. Next, as shown in FIG. 3, the enclosing frame 15 and the sinking mold 16 for the slurry reservoir are removed, and
After the drying device 21 was set on the upper side as shown in FIG. 7, hot air was sent from the hot air port 23 and released from the small holes 22, thereby drying the wet deposit 20. Subsequently, as shown in FIG. 5, an unnecessary portion of the dried deposit 24 protruding from the mold opening surface was cut off with a tip saw 25 to obtain a final molded product. When the physical properties of the final molded product were measured, the density was 0.11 g / cm ³ , and a product having almost no local variation in density was obtained. In addition, as a result of examining the buffer characteristics, it was found that they were very good.

[0029]

As described above, according to the present invention, the slurry is supplied into a concave mold having a large number of small holes on the wall and one side of which is open, and water as a medium of the slurry is removed from the small holes. Thus, in the method for producing a molded article in which the fine pore-impermeable fine components in the slurry are deposited in the mold to form a wet molded product and subsequently dried, the fine pore-impermeable fine components are placed in the mold. At the time of deposition, since a sinkable mold that can be pulled out is present in the concave mold, a molded body having a complicated uneven shape can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which an enclosing frame for a slurry reservoir is set on a forming die, a sinking die is set in a central portion, and the slurry is supplied and filled to the upper portion in this state.

FIG. 2 is a cross-sectional view showing a state in which pulp is deposited by suction dehydration from the state of FIG. 1 so that an unnecessary portion is formed on an open surface.

FIG. 3 is a cross-sectional view showing a state in which an enclosing frame for slurry storage and a sinking mold are removed from the state of FIG. 2;

FIG. 4 is a cross-sectional view showing a state in which a drying device is set on the mold shown in FIG. 3 and drying is being performed.

FIG. 5 is a cross-sectional view showing a state where unnecessary portions accumulated on the mold opening surface of the dried molded product in FIG. 4 are cut off.

FIG. 6 is a sectional view showing the final molded product thus obtained.

FIG. 7 is a cross-sectional view showing a state in which a sinking die that can be suction-dehydrated from the tip is set.

FIG. 8 is a cross-sectional view showing a state where an enclosing frame for slurry storage is set on a forming die, and a sinking die is set at two locations, and the slurry is supplied and filled up to the upper part in this state.

9 is a cross-sectional view showing a state in which pulp is deposited so that unnecessary portions are formed on an open surface by suction dehydration from the state of FIG.

FIG. 10 is a cross-sectional view showing a state in which an enclosing frame for a slurry reservoir and a sinking mold are removed from the state of FIG. 9;

FIG. 11 is a cross-sectional view showing a state where unnecessary portions accumulated on the mold opening surface of the molded article in the wet state in FIG. 10 are cut away.

FIG. 12 is a cross-sectional view showing a state in which a drying device is set on a molding die and drying is being performed.

FIG. 13 is a sectional view showing the final molded product thus obtained.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Concave mold 11 Small hole 12 Bottom of mold 13 Suction chamber 14 Suction port 15 Enclosure frame for slurry storage 16 Sinking mold 17 Guide 18 Pulp slurry 19 Water droplet 20 Pulp deposit 21 Drying device 22 Small hole 23 Hot air inlet 24 Dry pulp sediment 25 Tip saw 26 Final molded product

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shunsuke Shioi 4-7-5 Ginza, Chuo-ku, Tokyo F-term in Oji Paper Co., Ltd. 4L055 AF09 BF08 EA05 FA30 GA04

Claims (4)

[Claims] 1. A slurry is supplied into a concave mold having a large number of small holes on a wall surface, the surface of which is open, and water, which is a medium of the slurry, is removed from the small holes to reduce the small holes in the slurry. In a molding method of depositing a fine component passing therethrough in a mold and then performing a drying process, when depositing the fine component impervious to small holes in the molding die, an object having a specific shape that can be pulled out into the concave mold ( (Hereinafter referred to as a sinking mold). 2. During the molding, the small pore-impermeable fine components in the slurry are deposited so as to have an unnecessary portion exceeding the opening surface of the mold, and thereafter the unnecessary portion is cut off in a dry or wet state. The method for producing a molded article according to claim 1, which includes a step. 3. The method according to claim 1, wherein the composition of the slurry has a Canadian Standard Freeness (CSF) of 550 ml or more. 4. The method for producing a molded article according to claim 1, wherein a main component of the fine pore-impermeable fine component is a cellulosic fiber.