JP2001038835A - Surface-coated natural fiber molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a surface-coated natural fiber molding excellent in recyclability by making a water-soluble film plasticized by water adhere to the surface of the molding containing natural fibers mainly while the film is stretched. SOLUTION: An upper part film 24 plasticized by water and heat is arranged above a molding 10 containing natural fibers as a main component. While the film 24 is made to approach the molding 10, air is sucked from the bottom surface of the molding 10 by using a suction means to suck the film to the molding 10, the film 24 is made to adhere to the upper surface of the molding 10 while being stretched on an uneven surface contacting an object to be cushioned, and the upper surface is coated with the film 24. Next, an lower part film is placed under the molding 10 the upper surface of which is coated with the film 24, the film 24 of the peripheral part of the molding 10 and the lower part film are laid to overlap each other and adhered to each other by being added with heat and water, and protruded films are cut off to obtain a coated low density molding easy of recycling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated natural fiber molded article whose surface is closely adhered and covered with a film and which can be easily recycled.

[0002]

2. Description of the Related Art In recent years, as concerns about environmental problems have increased, there has been an increasing demand for styrene foam to be treated after use. In other words, it has been pointed out that in the case of incineration after use, damage to the furnace and generation of toxic gas due to generation of high temperature. 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. Recently, as a solution to the problem of styrofoam processing, products made from natural fibers such as pulp have been developed.Specifically, pulp molds have been formed by thinly depositing pulp on a mold surface in a wet process. Thick molded body (product name: Green Pal: manufactured by Oji Bag) which is filled with pulp in a molding container in a wet process, and thick molded product (trade name) in which a pulp is filled in a molding container and molded in a dry process Cell mold: made by Rengo), and the like.

[0003] However, these molded products obtained mainly from natural fibers such as pulp are weakly bonded to each other due to entanglement of the fibers and the like, and thus have no surface strength such as styrene foam and fall off. (For example, paper powder when pulp is a raw material), and has problems such as contamination of wrapped goods when used as a packaging material, and contamination of air and workers at a manufacturing site or a handling work site. ing.

[0004]

SUMMARY OF THE INVENTION
The present inventors have proposed in Japanese Patent Application No. 10-290310 to coat the molded body with a film-like base material. Among them, as a film, a water-soluble film such as polyvinyl alcohol is given as a specific example, and in the case of a coated molded article obtained using a water-soluble film, the film and the molded article are simply put into water without separation and stirred. As a result, the film is dissolved and the cellulose fibers easily disperse, so that it can be reused as a raw material as it is, and recycling is easier than a molded article covered with a water-insoluble film. However, since the water-soluble film has a high plasticizing temperature and is inferior in stretchability, the film plasticized by heat as in the skin-pack method is stretched and adhered to a molded article having irregularities to cover it. However, there is also a problem that a portion where the molded product and the film do not come into contact partially occurs, and it is difficult to obtain a product having good adhesion. In particular, this problem was remarkable in the case of a molded article having large irregularities. An object of the present invention is to provide a surface-coated natural fiber-based molded article in which a film and a molded article are in good contact with each other and excellent in recyclability.

[0005]

Means for Solving the Problems The present inventors have studied in view of the present situation, and found that a water-soluble film is plasticized in advance with moisture and then stretched by applying force to cover the surface of a molded article. The present inventors have found that a close contact state can be obtained, and have completed the present invention. That is, the surface-coated natural fiber molded article of the present invention is characterized in that a water-soluble film plasticized with moisture is adhered to the surface of a molded article containing natural fibers as a main component while being stretched. In particular, it is preferable that the water-soluble film is plasticized by moisture and heat. It is preferable that the plasticization of the water-soluble film is performed by heated steam. It is preferable that the plasticization of the water-soluble film is performed by a heater and heated steam. The stretching of the film is preferably performed by air pressure or vacuum pressure. The molded product has a density of 0.2 when a slurry having a Canadian Standard Freeness (CSF) of 550 ml or more of the slurry composition is dehydrated using a mesh and then dried.
It is preferable that the low density body is 5 g / cm ³ or less. Preferably, the natural fibers are cellulose fibers.

A first cause of the success of the present invention is that a water-soluble film having poor thermoplasticity and stretchability under normal conditions can be made to have sufficient stretchability as a covering film by imparting moisture. It is in the point that found.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A molded article mainly composed of natural fibers to be surface-coated in the present invention is a pulp mold in which pulp is thinly deposited on a mold surface and molded by a wet method, and a pulp is molded in a molded container by a wet method. Thick compacts (filled green pal: made by Oji bags) to be filled and molded, thick molded compacts (trade name cell mold: made by Rengo) filled and molded by dry pulp in molding containers, etc. Specific examples include Canadian Standard Freeness (CSF) of 550.
The slurry obtained by dehydrating the slurry comprising the composition of not less than 0.1 ml using a mesh and then drying the slurry has a density of 0.25 g / cm.
^In the case of a low-density molded product of ³ or less, the surface modification effect is most remarkable and is particularly preferable.

The Canadian Standard Freeness (CSF), which is the most remarkable system of the present invention, is 550 ml.
The slurry comprising the above composition is dehydrated using a mesh and then dried, and then dried to obtain a low-density molded article having a density of 0.25 g / cm ³ or less, which will be described more specifically. It is not limited.

The natural fiber used as a raw material of the slurry includes, for example, (1) unbleached or bleached chemical pulp obtained by kraft pulping, sulfite pulping, alkali pulping or the like of softwood or hardwood, or GP, RM
Waste paper that has been subjected to at least one of mechanical pulp such as P, TMP, and CTMP, or cotton pulp, linter pulp, and water repellency, water resistance, and curing described in Japanese Patent Application No. 10-0322920. Pulp, liquid ammonia-treated pulp, mercerized pulp, curled fiber (product name: HBA-FF, NHB manufactured by Warehauser, USA)
405, NHB416), 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 alginate fibers. And the like. Among them, cellulosic fibers are particularly preferable because they are excellent in performance and easy to procure. Further, in terms of buffer characteristics and the like of the obtained molded article, those having a Canadian standard freeness of 550 ml or more are preferable, and 600 m
Those having l or more are particularly preferred. The natural fiber is usually blended in a range of 35 to 100% by dry weight based on the slurry composition.

Incidentally, the Canadian standard freeness is JIS-
It is specified in P-8121 and usually indicates the drainage of pulp. In the present invention, the drainage of the slurry composition was determined by the same measurement method.

When it is desired to improve the interlayer strength of the molded product, it is effective to add an interlayer strength enhancing material. Examples of the interlayer strength enhancing material include cellulosic fine fibers and heat-fusible synthetic fibers (synthetic pulp and the like). Is mentioned. As the cellulosic fine fibers, a number average fiber length of 0.01 obtained by wet mechanical treatment of natural pulp fibers with a sand grinder, a beater, or the like.
Those having a range of 0.80 mm to 0.80 mm are exemplified. As heat-fusible synthetic fibers, for example, polyethylene fibers, polypropylene fibers, polyethylene-polypropylene sheath core fibers,
Polystyrene fiber, polylactic acid fiber, polyester fiber,
Examples thereof include aliphatic polyester fibers and acetylcellulose fibers.

Among the interlaminar strength enhancing materials, cellulosic fine fibers are particularly preferable because they are environmentally friendly materials and have a large effect on improving interlaminar strength. The amount of the interlayer strength enhancer to be added to the composition is not particularly limited, but is usually in the range of 1 to 40% by dry weight with respect to the composition.

Other materials to be added to the slurry composition include, in addition to the above-mentioned interlayer strength-enhancing material, a paper strength enhancer, a water-proofing agent, a water-repellent, a sizing agent, a dye, a pigment, an inorganic fiber, an organic fiber, Molecular coarse powder, drainage improver, PH regulator, slime control agent, thickener, preservative, fungicide, antibacterial, flame retardant, rodenticide, insect repellent, moisturizer, freshness preservative, deoxidizer,
Examples include foaming agents, surfactants, electromagnetic shielding materials, antistatic agents, rust inhibitors, fragrances, deodorants, and various types of microcapsules having foaming and aromatic properties.

The above materials are blended so that the Canadian standard freeness of the composition is 550 ml or more. The slurry is usually prepared batchwise or continuously using a device having a stirrer. Water is usually used as a medium used for slurry formation. 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 5% by weight in terms of the dispersed state.

As the molding die, a concave molding die having a large number of small holes in the inner wall (for example, having a concave-convex bottom surface, a depth of 5 m)
A cylindrical molding die such as a cylinder or a square cylinder having a size of m to 20 cm), or a split molding die is usually used.

The injection of the slurry into the mold is performed by, for example, immersing the slurry into a slurry tank with the open surface of the mold facing downward, and sucking the slurry into the mold from the downward open surface by sucking through the small holes. Can be taken. As a method for removing the medium of the slurry from the small holes, there are 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. If necessary, a cutting process or a pressing process using a mold can be applied to the wet molded product formed in the molding die after dehydration.

The wet molded product is then taken out of the mold or taken out of the mold and dried. As a drying method, a known method such as hot air drying, infrared drying, and microwave drying can be used. To increase the drying speed,
It is effective to inject heated air into a wet molded product. It is also effective to form a through hole or a non-through hole in the molded product to improve the air flow.

Hereinafter, the method for forming a low-density molded product used in the present invention will be described in detail with reference to the drawings in order to more specifically show the method, but the present invention is not limited thereto. FIG.
FIG. 1 is a perspective view of a natural fiber-based low-density molded product 10 (hereinafter, referred to as a molded product) used in the coating treatment of the present invention. FIG.
FIG. 5 to FIG. 5 are sectional views showing one forming method of the formed body. As shown in FIG. 2, the molding container 11 is a double-walled container having a cylindrical shape with an open top and a large number of small holes 1 for dehydration on the inner wall.
2, a convex lower mold 13 having steps at the bottom four corners of the inner wall, a suction chamber 14 formed by inner and outer double walls, and a suction port 15 attached to the bottom of the outer wall. I have.

FIG. 2 shows the slurry 1 from the upper guide 16.
7 shows a state in which the fibers are piled up on the open surface of the container by suction dehydration through the lower suction port 15 while filling the container 11 and the filling into the container 11 is completed. Numeral 18 indicates water droplets oozing out by suction, and numeral 19 indicates a filling of wet fibers.

FIG. 3 shows a state in which an unnecessary portion raised and deposited on the open surface of the molding container of FIG. The cutting is performed while moving the water jet nozzle. FIG. 4 shows a press machine 21 having a flat bottom and a small number of small holes 22 on the bottom, which is lightly compressed by a press machine 21 to make the surface smooth and then dried by sending hot air through a hot air port 23 of the upper mold 21. It shows the state where it is. At this time, if suction is performed from the suction port 15, drying proceeds more efficiently. FIG. 5 shows a dried molded product 10 (cross-sectional view taken along the line AA in FIG. 1) obtained by taking out from the molded container 11, and the molded product is subjected to a coating process in the next step. You.

In the present invention, a water-soluble film plasticized with water is stretched and adhered to the surface of the natural fiber-based molded article thus obtained to cover it.

Examples of the water-soluble film include polyvinyl alcohol (manufactured by Nippon Synthetic Chemical: Vinylon 2500,
High cello C-200, high cello H-211), starch and the like. Usually, a particle having a range of 3 to 200 μm is selected, but is not particularly limited. The film may be an air-permeable film having holes. Further, the molded body may be partially covered with a different film.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. 6 to 10 are cross-sectional views showing a film covering step. As shown in FIG. 6, an upper film 24 is disposed above the molded body 10, and the film 24 is plasticized by moisture and heat supplied from a suitable device (not shown). Next, while the film 24 is being brought close to the molded body 10, the molded body 10 is
When the air is sucked from the bottom surface of the film, the film 24 is attracted to the molded body 10 as shown in FIG. 7, and as shown in FIG. 8, the film 24 is stretched to the upper surface of the molded body 10, that is, the uneven surface in contact with the buffer. The surface is tightly covered with a film 24.

Subsequently, as shown in FIG. 9, a lower film 25 is laid below the molded body 10 whose upper surface is already covered with the film 24, and the upper film 24 on the periphery of the molded body 10 is formed.
1 and the lower film 25 are overlapped with each other by applying heat and moisture, and the protruding film is cut off.
Thus, a coated low-density molded body 26 as shown in FIG.

Further, a breathable film is selected as the lower film 25, and the lower film 25 is brought into contact with the bottom surface of the molded body 10 when coating with the upper film 24, and air in the molded body is passed through the lower film. If the suction is performed, the covering of the molded body 10 with the upper film 24 and the lower film 25 and the adhesion of the film on the periphery of the molded body can be performed without time loss.

The plasticization of the water-soluble film can be carried out only with water. However, in order to ideally stretch the film and to achieve good adhesion with the molded product, the plasticization is carried out by applying water and heat. Is preferred. At that time, a method of exposing the film to heated steam while heating the film with a heater or the like is preferable. When the adhesion between the molded body and the film is weak, an adhesive is preferably applied to the molded body in advance.

When the film is stretched and brought into close contact with the molded body, a means for applying pressure by air pressure or the like can be used in addition to using the vacuum pressure as described above.

The coated molded article of the present invention produced as described above can be widely used not only as a cushioning material for protecting an object to be buffered but also in a field where a foamed resin such as styrene foam is used. . Hereinafter, the present invention will be described in detail with reference to Examples, but it should be understood that the present invention is not limited thereto. 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)
The mixture was pulverized at 0) and kneaded at a solid concentration of 30% to obtain hemp fibers having a number average fiber length of 8 mm. The Canadian Standard Freeness of this fiber was measured to be 720 ml. In addition, a 1.5-liter sand grinder (Shinmaru Co., Ltd.) filled with 80% glass beads having an average particle diameter of 2 mm was filled with an aqueous slurry of used newspaper pulp having a solid content of 1%.
Dynomill KDL-PILO manufactured by Enterprises
T) was introduced and passed at 350 ml / min to obtain a number average fiber length of 0.28 mm and a binding reinforcing factor of 0.40.
Was obtained. Hemp fiber 9 obtained as above
Water was added to a mixture of 8 parts (dry weight) and 2 parts (dry weight) of fine fibers to adjust the solid concentration to 2%, and the mixture was sufficiently stirred to obtain a slurry. Next, after the slurry was put into a tank, fibers were deposited by suction for 6 seconds under a vacuum pressure of -400 mHg using a pulp molding machine, and then the fiber was pulled out of the tank and the portion protruding from the female mold was jetted with a water jet. Excision gave a wet molded product. Subsequently, 150 ° C. hot air pressurized to 1 kg / cm ² was sent from the open part of the female mold for 3 minutes to obtain a dry molded product having the shape shown in FIG.
When the physical properties of the obtained molded body were measured, the density was 0.10.
g / cm ³ . 25 for Spiemer 2800-H
After setting a μm polyvinyl alcohol film (Nippon Synthetic Chemical Co., Vinylon 2500), place a boiling water bath underneath to plasticize the film, then remove the bath, and immediately set the molded body in its place. Then, it was sucked from below and brought into close contact with the surface. Next, vinylon 2500 is laid under the molded body, and thereafter, heat and moisture are applied to the periphery of the molded body to bond them, and then the protruding portion of the film is cut off to form a coating type low density as shown in FIG. A molded article was obtained.

[0030]

According to the present invention, a water-soluble film plasticized with water is stretched to coat a natural fiber-based molded article.
A natural fiber-based molded article in which the surface of the molded article and the film are in good contact with each other is obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a natural fiber-based low-density molded product used for a coating treatment of the present invention.

FIG. 2 is a cross-sectional view showing a state where a slurry is poured into a molding container used for manufacturing the molded body of FIG. 1 and natural fibers are deposited.

FIG. 3 is a cross-sectional view showing a state where an unnecessary portion deposited on an open surface of a molding container is cut.

FIG. 4 is a cross-sectional view showing a state in which a wet deposit is being dried.

FIG. 5 is a sectional view of a natural fiber-based low-density molded product taken out of a molding container after drying.

FIG. 6 is a cross-sectional view showing a state where a film plasticized with moisture is arranged above a molded body.

FIG. 7 is a cross-sectional view showing a state where a film is being sucked by a molded body.

FIG. 8 is a cross-sectional view showing a state where the upper surface of a molded body is covered with a film.

FIG. 9 is a cross-sectional view showing a state in which a film is laid below a molded body whose upper surface is covered with a film.

FIG. 10 is a cross-sectional view showing a molded article of the present invention completed by cutting off a protruding film after bonding a film on a peripheral portion of the molded article.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Natural fiber type low-density molded object 11 Mold (molding container) 12 Small hole 13 Lower mold 14 Suction chamber 15 Suction port 16 Guide 17 Fiber slurry 18 Water drop 19 Fiber deposit 20 Water jet 21 Upper die for press machine 22 Small hole 23 Hot air port 24 Upper film 25 Lower film 26 Coated low density molded product

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shunsuke Shioi 4-7 100 Ginza, Chuo-ku, Tokyo Oji Paper Co., Ltd. F term (reference) 4F100 AJ00A AK21 AR00B AR00C BA02 BA03 BA07 BA10B BA10C BA13 DG01A JA15A JB09B JB09C JK06 YY00A 4L055 AA07 AA11 AC09 AG64 AJ02 BE14 BF07 BF08 BF09 EA05 EA25 FA11 FA30 GA04 GA05

Claims (4)

[Claims] 1. A surface-coated natural fiber-based molded article characterized in that a water-soluble film plasticized with moisture is stretched and adhered to the surface of a molded article mainly composed of natural fibers. 2. The surface-coated natural fiber molded article according to claim 1, wherein the water-soluble film is plasticized with moisture and heat. 3. The surface-coated natural fiber molded article according to claim 1, wherein the water-soluble film is stretched by air pressure or vacuum pressure. 4. The Canadian Standard Freeness (CSF) of a slurry composition, wherein the molded article containing the natural fiber as a main component is used.
The surface coating according to any one of claims 1 to 3, wherein the slurry is a low-density body having a density of 0.25 g / cm ³ or less, obtained by dehydrating a slurry of 550 ml or more using a mesh and then drying the slurry. Natural fiber molding.