JP2001049597A - Low density molded article using synthetic fiber as raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low density molded article which has an excellent cushioning property and excellent recyclability, by molding, dehydrating and drying a slurry containing recycled synthetic fibers as a raw material. SOLUTION: This low density molded article is obtained by injecting a slurry 16 comprising recycled synthetic fibers having a number-average fiber length of <=50 mm into a mold container 10 from an upper guide 15, simultaneously sucking water from the lower suction port 14 of the container to accumulate the raw material fibers, slightly compressing the accumulated fibers with the upper mold of a press machine to smoothen the upper surface of the molded article, blowing hot air to dry the molded article, and then taking out the molded article from the container mold 10. The recycled synthetic fibers comprises fibers obtained from synthetic fiber-containing wastes such as bedding or carpets, or fibers produced from synthetic resin wastes, such as pet bottles, except the fibers as a raw material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a low-density molded article made of synthetic fibers as a raw material and having excellent buffering properties and recyclability.

[0002]

2. Description of the Related Art Styrofoam conventionally used as a cushioning material has features such as excellent shock absorbing properties, easy processing into an arbitrary shape, low cost and light weight, and good appearance and appearance. Have. However, as interest in environmental issues has increased in recent years, there has been an increasing demand for treating post-use processability, as with other so-called plastic products. 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 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] In order to solve the problems in the processing of styrofoam, there has recently been a movement to dissolve and recover the styrofoam in a solvent and reuse it as a raw material.

[0004]

However, in this case, the resin is deteriorated during the regeneration, so that it is rarely used as a raw material for styrofoam, and is often used for low-grade resin products. It is a fact. An object of the present invention is to provide a low-density molded article having excellent buffering properties and recyclability.

[0005]

In view of the above situation, the present inventors have made intensive studies on a low-density molded article having excellent cushioning properties and recyclability using synthetic resin as a raw material. It has been found that this can be achieved by molding by a wet method, and the present invention has been completed. That is, the present invention is obtained by dewatering and drying a slurry using synthetic fibers as a raw material, and having a density of 0.02.
It is a low-density molded product characterized by being 〜0.30 g / cm ³ . In the present invention, the thickness of the deposited layer is 10 m
It is preferable that the molded article has a m or more. In the present invention, the number average fiber length of the synthetic fibers is preferably 50 mm or less. Further, it is preferable that the synthetic fiber is a fiber obtained from synthetic fiber-containing waste or a fiber made from synthetic resin waste other than fiber.

The first cause of the success of the present invention is that, instead of foaming a synthetic resin, it is first processed into a fiber shape and then formed into a raw material by a wet process, thereby obtaining a low-density molding having excellent buffering properties. I found that I could get my body.
The second reason for the success is that, by dispersing the obtained molded product in a medium such as water without any treatment or after lightly pulverizing it, the excellent recyclability that it can be reused as a raw material of the molded product is obtained. This is the point found in the molded product.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The synthetic fibers used in the present invention include, for example, polyester (PET) fibers, aliphatic polyester fibers, nylon 6 fibers, nylon 66 fibers,
Aramid fibers, polyethylene fibers, polypropylene fibers, polyethylene-polypropylene sheath-core fibers, acrylic fibers, acetylcellulose fibers, and the like. Among them, in order to stably obtain a low-density molded article of good quality, the number average fiber length is preferably 50 mm or less, particularly preferably 2 to 20 mm. 5
In the case of fibers exceeding 0 mm, the fibers are easily entangled with the stirrer during slurry preparation, causing difficulty in dispersion, or the density of the obtained molded body tends to be non-uniform, or the surface of the obtained molded body becomes rough, etc. Problems are likely to occur. Those having a size of 20 mm or less are particularly excellent in this respect. On the other hand, those having a thickness of less than 2 mm are not preferable because they can be used practically but have a low density. As a raw material of synthetic fibers, for example, products made from synthetic fibers as raw materials, for example, wastes of futons, carpets, blankets, clothing, automobile interior materials, chair parts, and the like, or synthetic resin wastes such as plastic bottles as a raw material Recycled fibers are preferred from the viewpoint of resource recycling. As the fiber, a fiber having a low water retention that can be easily dried after dehydration is preferable.

[0008] As a method of cutting a synthetic fiber having a number average fiber length exceeding 50 mm or a synthetic fiber processed product to obtain a fiber having a length of 50 mm or less, mechanical treatment using a pulverizer, a crusher, a cutter, a defibrating machine, or the like is effective. It is. Examples of the machine include grinders such as a pocket grinder, a chain grinder, and a ring grinder, refiners such as a single disc refiner, a double disc refiner, a conical type refiner, other beating machines such as a beater, and stirrers such as a blender and a deflaker. Defibrator, wood chip defibrator such as defibrillator, crusher, crusher such as granulator, hammer mill, pin mill, shredder and the like. Above all, it is preferable to use a dry processing machine capable of obtaining dry fibers that are easy to handle. Among the machines used for dry processing, a hammer mill, a pin mill, a disc refiner, a crusher, a granulator, and a cutting machine are preferable. Specifically, fiber risers manufactured by Sumikura Kogyo / Nishi Nippon R & D Co., Ltd., impact mills manufactured by Dalton, free mills manufactured by Nara Machinery Co., Ltd. V series crusher, BO series crusher, U series crusher, mesh mill, Gainax crusher,
Hard crushers, push-cut type hydraulic cutting machines, shear type hydraulic cutting machines, and the like can be given. These machines are used in combination as necessary. When it is desired to improve the interlayer strength and surface flexibility of the molded product, it is effective to perform a kneader treatment after the pulverization by the above machine.

The synthetic fibers may be used alone or in combination of two or more. In the case of a combined system, it is preferable to use fibers having different plasticizing temperatures and to perform a heat treatment such as drying at a temperature at which only one is plasticized, since a molded article having a strong interlayer strength can be obtained. The synthetic fiber is usually blended in a range of 50 to 100% by dry weight with respect to the slurry composition.

Although the desired low-density molded article can be obtained only from the above synthetic fibers, it is necessary to improve the physical properties such as the interlayer strength of the molded article, or to procure synthetic fibers as raw materials. Natural fibers can be added to the slurry composition according to the requirements.

Examples of natural fibers include: (1) unbleached or bleached chemical pulp obtained by kraft pulping, sulfite pulping, alkali pulping, etc. of coniferous or hardwood, GP, RMP, TMP, CTMP, etc. Mechanical pulp, cotton pulp, linter pulp, used paper pulp and liquid ammonia-treated pulp subjected to at least one of water repellency, water resistance, and curing described in Japanese Patent Application No. 10-0322920. , Mercerized pulp, curled fiber (product name: HBA-FF, NHB405, NHB416, manufactured by Warehauser, USA),
Cellulose fibers such as hemp fiber described in Japanese Patent Application No. 10-377923, (2) protein fibers such as wool, silk and collagen fibers, and (3) complex sugars such as chitin / chitosan fibers and alginic acid fibers. Chain-based fibers and the like. Among them, cellulosic fibers are particularly preferable because they are excellent in performance and easy to procure. When it is desired to particularly improve the interlayer strength of the molded product, the cellulose-based fine fibers having a number average fiber length of 0.01 to 0.80 mm obtained by wet-mechanical treatment of the cellulose-based fibers with a sand grinder, a beater or the like. Is particularly preferred. The amount of the natural fiber added to the slurry composition is not particularly limited, but is usually in the range of 1 to 50% by dry weight based on the composition.

In the slurry composition, inorganic fibers, metal fibers, dyes, pigments, adhesives, water-proofing agents, water-repelling agents, etc., may be used as necessary to improve the performance of the low-density body or impart functions. , Thickeners, surfactants, preservatives, antifungal agents, antibacterial agents, rodenticides, insect repellents, flame retardants, humectants, freshness preservatives, oxygen scavengers, foaming agents, electromagnetic shielding materials, antistatic agents, antistatic agents Rust agents, fragrances, deodorants, various microcapsules having foaming properties, fragrance 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 dispersion medium used for forming a slurry. The concentration of the slurry is usually adjusted so that the dry solid content is in the range of 0.03 to 10% by weight, but preferably in the range of 0.03 to 5% by weight in terms of the dispersed state.

[0014] The molding dies used for the production of molded articles include:
Although it is possible to use a normal pulp mold as it is, if a block-shaped molded product having better buffering properties is required, a deep-bottomed container having a large number of small holes, for example, A cylindrical container such as a cylinder or a square tube, or a split container is usually used. (Hereinafter, in the present invention, the mold is referred to as a mold container)

The small holes formed in the molding container may have any shape such as a circle, an ellipse, a square, and a rectangle. When using a mold with a fine mesh attached like a pulp mold, a rather large hole (for example, a circular hole having a diameter of 2 to 10 mm).
However, when a wire mesh is not used, it is preferable that the small holes have a size such that the dispersed component in the slurry hardly leaks, and a circular hole having a diameter of 0.5 to 2 mm is used. Is usually used. The wire mesh usually has 15 to 2
A 00 mesh thing is used. The size of the small holes can also be changed depending on the location of the forming container. The small holes need not necessarily be present on the entire surface of the molding container wall. However, considering the dewatering efficiency and the like, it is preferable that small holes are present in a portion of 40% or more of the wall of the molding container, more preferably 70% or more. The number of parts to in pores small pores there is preferably made present one or more per 1 cm ^2, more preferably 4 or more per 1 cm ^2.
In the case of a deeper molding die, in order to obtain a molded body with a good sedimentary layer, the opening ratio of the deepest portion of 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. Incidentally, the maximum value of the opening ratio is not particularly limited, but is usually 70%.

The slurry is injected into the molding container by injecting the slurry from the opening into the molding container with the opening facing upward by a pump. The slurry is immersed in a slurry tank with the opening facing downward as in a normal pulp mold. A method of sucking the slurry into the molding container from the downward opening port by sucking more, sucking the molding container with the opening port facing upward while sinking the molding container into the slurry tank, and sucking the slurry into the molding container from the opening port. Can be taken.

As a method for removing water as a 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, a centrifugal dehydration method and the like. You can also. The type of slurry used for injection is usually one type, but the slurry injection is divided into two or more stages, and by changing the composition of the slurry used at that time, a molded article in a state in which deposited layers of different compositions are sequentially laminated is obtained. You can also get.

The wet molded product formed in the molding container by dehydration may be subjected to a cutting treatment or a pressing treatment by a mold, if necessary.

The wet molded product is then taken out of the container or taken out of the container and dried. As the drying method,
For example, known methods such as hot air drying, infrared drying, and microwave drying can be used alone or in combination. Heating steam is also effective for drying halfway. Among hot-air drying methods, air-drying that improves the air flow in the inter-fiber space, such as injecting heated air into a wet molded product or sucking in while applying heated air from the opposite side of the molded product, is faster drying. Thus, the production efficiency of the molded body is extremely high, which is particularly preferable. Usually 40 to 2 for hot air drying
Hot air in the temperature range of 50 ° C. is used. The amount of ventilation in the through-air drying is preferably 2 liters / cm ² · min or more in the early stage of drying from the viewpoint of drying efficiency, and particularly preferably 5 liters / cm ² · min or more. In order to increase the drying speed of the molded article, besides, the surface of the molded article is intentionally made uneven to increase the surface area, or a hole is formed in the molded article to penetrate or non-penetrate so that air can easily enter the inter-fiber space. Ingenuity is also effective. Among the low-density molded products of the present invention, those having a deposited layer having a thickness of 10 mm or more have extremely excellent buffer characteristics and are particularly preferable.

Hereinafter, the molding method used in the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

1 to 4 are sectional views showing one molding method used in the present invention. The molding container 10 is shown in FIG.
As shown in the figure, a double-walled container having a cylindrical shape with an open top,
The inner wall has a large number of small holes 11 for dehydration, the inner wall has a convex lower mold 12 having a step at the inner periphery of the bottom, and a suction chamber 13 is formed by inner and outer double walls. Has a suction port 1
4 are attached. Although the shape of the lower mold 12 is schematically illustrated as a simple one with a stepped portion, the shape of the unevenness may be more complicated according to the shape of the product protected by the cushioning material.

FIG. 1 shows that the slurry 1 is
6 shows a state in which the fibers are deposited so as to swell on the open surface of the container by suction dehydration from the lower suction port 14 while injecting 6, and the filling into the container 10 is completed. Reference numeral 17 denotes water droplets that have oozed out by suction, and reference numeral 18 denotes a filling of wet fibers.

FIG. 2 shows a state in which an unnecessary portion which has been raised and deposited on the open surface of the molding container of FIG. The cutting is performed while moving the water jet nozzle. FIG. 3 shows a press machine 20 having a flat bottom and a large number of small holes 21 on the bottom, which is lightly compressed to make the surface smooth, and then hot air is sent from a hot air port 22 of the upper mold 20 to be dried. It shows the state where it is. At this time, if suction is performed from the suction port 14, drying proceeds more efficiently. FIG. 4 shows a final molded product 23 obtained by taking out from the molding container 10 after drying. By the way,
If the bottom of the press upper die 20 of FIG. 3 is used in a special shape, a molded product having a more complicated surface shape can be obtained.

The molding method is not limited to the above-mentioned method. While the slurry is poured under pressure into a split mold filled with water, the water in the split mold is gradually extruded to fill the fibers therein. Then, a method of blowing out hot air from a pipe inserted into the center of the split mold to dry the split mold is also effective.

An adhesive, a waterproofing agent, a water repellent, a dye, a pigment, a preservative, an antifungal agent, an antibacterial agent, a flame retardant, a rodenticide,
As a method for incorporating an insect repellent, a freshness preserving agent, a deoxygenating agent, an electromagnetic shielding material, an antistatic agent, a rust inhibitor, an aromatic agent, a deodorant, etc. In addition to the method, a method of applying a surface after producing a molded article, that is, an external addition method may be employed. Means such as impregnation, brushing, and spraying can be used for this surface application. Of course, both internal and external additions may be used. The external addition method has a feature that more additive components can be distributed on the surface than the internal addition method. In addition, high quality paper, cellophane paper, waterproof paper,
Other materials such as oil-resistant paper, vapor-deposited paper, coated paper, synthetic paper, non-woven fabric, cloth, synthetic film, metal foil, wood board, synthetic resin board, glass board, metal board, etc. can also be used by completely or partially pasting them. it can. Further, it can be used by sandwiching, sticking, fitting, or the like in a processed product such as a cardboard, paperboard, board, synthetic resin board, metal board or box. Further, the obtained molded bodies can be bonded together. Skin pack technology can also be used as a means for providing a film layer on the surface of the molded product. In addition, the molded body may be subjected to processing such as cutting and printing.

The molded article thus obtained can be widely applied to fields other than the packaging materials in which foamed resin molded articles are currently used, by taking advantage of characteristics such as low density, cushioning property, heat insulating property and soundproofing property. . In addition, it can be used in the field of filters by taking advantage of air permeability.

The most efficient method of obtaining a molded article is to use a molded container as described above, but another method is to first form a sheet or board and then post-process it to form it. Can also. Hereinafter, the present invention will be described more specifically with reference to Examples, but 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 After cutting a piece of polyester clothing into a 20 cm square with a cutting machine, a crusher (made by Horai,
V-360) to obtain a polyester fiber having a number average fiber length of 8 mm. In addition, a water slurry of bleached kraft pulp having a solid content of 1% was placed in a 1.5-liter sand grinder (manufactured by Shinmaru Enterprises, Dynomill KDL-PILOT) filled with 80% of glass beads having an average particle size of 2 mmΦ. By introducing and passing at a flow rate of 330 ml / min, fine fibers having a number average fiber length of 0.27 mm were obtained. Water is added to a mixture of 90 parts (dry weight) of hemp fiber and 10 parts (dry weight) of fine fiber obtained as described above to adjust the solid content concentration to 2%, and the slurry is sufficiently stirred to obtain a slurry. Obtained. Next, the slurry was put into a tank, and a pulp molding machine equipped with a disk-shaped female mold (suction from the bottom only) having an inner diameter of 200 mm and a depth of 20 mm was used under a vacuum pressure of -400 mHg. After suctioning for 2 seconds to deposit the fibers, the portion protruding from the female mold was cut off with a water jet to obtain a wet molded product. Subsequently, 80 ° C. pressurized to 1 kg / cm ² from the open part of the female mold
Was blown in for 3 minutes to dry the molded product. When the physical properties of the obtained molded body were measured, the density was found to be 0.
It was 10 g / cm ³ . In addition, as a result of examining the buffer characteristics, it was found that they were very good. Further, the molded product was placed in the above-mentioned pulverizer, and the obtained pulverized product was immersed in water and stirred and dispersed. As a result, it was found that the product exhibited a good dispersion state and could be used again as a raw material for the molded product.

[0029]

As described above, in the present invention, since synthetic fibers are used as raw materials and molded by a wet method, a material having a low density and excellent buffer properties can be obtained efficiently. Further, the obtained molded body can be used as a raw material without special treatment.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which a slurry is poured into a molding container to deposit a solid content.

FIG. 2 is a cross-sectional view showing a state where unnecessary portions accumulated on an open surface of a molding container are cut.

FIG. 3 is a cross-sectional view showing a state in which a wet deposit is being dried.

FIG. 4 is a cross-sectional view of a molded body taken out of a molding container after drying.

[Explanation of symbols]

10: Mold (molding container), 11: Small hole, 12: Lower mold,
13: suction chamber, 14: suction port, 15: guide, 16: fiber slurry, 17: water droplet, 18: fiber deposit, 19: water jet, 20: upper die, 21: small hole,
22: Hot air port, 23: Dry molded product with high surface temperature, 2
4: Spray nozzle, 25: Final product

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shunsuke Shioi 4-7-5 Ginza, Chuo-ku, Tokyo Oji Paper Co., Ltd. F-term (reference) 4L055 AF33 BF06 BF08 BG04 EA08 EA16 FA11 FA16 GA04 GA35 GA37

Claims (3)

[Claims] 1. A slurry obtained by dewatering and drying a slurry using synthetic fibers as a raw material, and having a density of 0.02 to 0.30 g.
/ Cm ³ . 2. The synthetic fiber has a number average fiber length of 50 mm.
The low-density molded product according to claim 1, which is: 3. The low-density molded article according to claim 1, wherein the synthetic fiber is a fiber obtained from a synthetic fiber-containing waste or a fiber made from synthetic resin waste other than the fiber. .