JPH11229289A - Low-density material using waste paper as raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low-density material excellent in low-density and cushioning properties and productivity by dehydrating and drying a slurry comprising waste paper fibers undergoing at least any one kind of pretreatment of water repelling, water resisting and hardening treatments. SOLUTION: This low-density material is obtained by introducing a slurry comprising curly fibers prepared by applying at least one kind of a treating agent selected from the group of a water repelling agent, a water resisting agent and a hardener to waste paper fibers and then keeping the resultant waste paper fibers in a dry state at >=90 wt.% solid matter concentration at least once and having >=550 mL Canadian standard freeness and >=0.4 curl factor and containing a coarse powder having >=550 mL Canadian standard freeness into a prescribed mold and dehydrating and drying the slurry. The resultant low-density material comprises a three-dimensional molded product having unevennesses and has 0.02-0.30 g/cm<3> density.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a low-density body such as a low-density sheet or a low-density molded article used as a cushioning material. In particular, the present invention relates to a low-density body using waste paper as a raw material and having excellent low-density, buffering properties, and productivity.

[0002]

2. Description of the Related Art Styrofoam conventionally used as a cushioning material has features such as excellent cushioning properties, easy processing into an arbitrary shape, low cost, light weight, and good appearance and appearance. have. However, in recent years, as the interest in environmental issues has increased, as with other plastic products, the processability after use has become a problem. That is,
It has been pointed out that in the case of incineration after use, damage to the furnace and generation of toxic gas due to the generation of high temperatures. 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.

In order to solve the problems in the processing of styrofoam, recently, pulp has been manufactured as a raw material and can be given a cushioning property and strength by devising its shape. Pulp molds, which are also easy to use, have attracted attention and are increasingly used as substitutes for styrene. In particular, waste paper such as newspapers and magazines is discharged in large quantities in recent years, but due to the performance and poor appearance of the fibers obtained by defibration, the range of use is narrow, demand is not growing, and inventory is in excess. Pulp molds used as raw materials are ideal when viewed from environmental issues.

[0004]

However, in the case of a pulp molding method in which pulp in a slurry is deposited on a mold having many small holes while sucking and dewatering, and then dried to obtain a molded product. However, if ordinary pulp raw material is used, the adhesion of pulp fibers will progress as the pulp accumulation in the mold progresses, and the water drainage will worsen.・ As long as the dehydration process takes time and production efficiency is not neglected,
Those exceeding 0 mm could not be obtained. For this reason, the obtained product was inferior in buffering properties, was not sufficiently strong, and lacked suitability as a packaging material. In particular, when the raw material of the pulp is waste paper, the fibers are keratinized and brittle, so many fine parts are generated in the defibration process, the drainage is extremely poor, and almost all of the above points are inferior to virgin pulp in the above points . An object of the present invention is to provide a low-density body made of waste paper as a raw material and having excellent low-density, buffering properties, and productivity.

[0005]

In order to solve the above problems, the present invention employs the following constitution. That is, the present invention
"Water-repellent treatment, water-resistant treatment, obtained by dehydrating and drying a slurry containing waste paper fibers that have been subjected to at least one treatment selected from curing treatment, the density is 0.02 to
Low-density body characterized by being 0.30 g / cm ³ "
It is.

In the present invention, the composition for forming the slurry preferably has a Canadian Standard Freeness (CSF) of 550 ml or more. Further, it is preferable that Canadian standard freeness (CSF) of the used paper fiber subjected to the treatment is 550 ml or more.

Further, in the present invention, a water repellent, a water resistant agent and a curing agent are brought into contact with waste paper or waste paper fibers in at least one of the treatment steps selected from water repellency treatment, water resistance treatment and curing treatment. Later, at least once at a solids concentration of 9
It is preferable to use waste paper fibers in a dry state of 0% by weight or more.

In the present invention, the treated waste paper fiber is
When the curl fiber has a curl factor of 0.4 or more, the density can be particularly reduced. In the present invention, the slurry has a Canadian Standard Freeness (CSF) of 550.
It can contain more than ml of coarse powder. The low-density body of the present invention can be formed as a three-dimensional formed body having irregularities.

A first feature of the present invention is that in using waste paper fiber, it is treated in advance to obtain the rigidity of the fiber,
By increasing the water repellency and water resistance, adhesion between fibers is suppressed even by the suction / dehydration method of the slurry, and the resulting molded article has a lower density than expected. Also, the second
The feature of this treatment is that the adhesion between fibers is suppressed by the treatment, the water drainage is improved, the water retention of the fibers is also reduced, the drainage is dramatically improved, and the slurry suction / dehydration molding method is sufficient. The point is that a molded product having a thickness and excellent cushioning properties can be efficiently obtained in a short time.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As used paper used in the present invention, there can be used those known in the art such as used newspaper, corrugated cardboard, used magazine and the like discharged from homes, factories and business establishments. Specifically, used newspapers, books,
Magazines, telephone directories, catalogs, high-quality paper, packaging boxes, cardboard boxes, pulp molds, paper cushioning materials, or paper-cutting, printing, bookbinding, box-making, cardboard manufacturing, etc. And waste paper.

In the present invention, each of the processes of water resistance, water repellency, and curing is performed using a water resistance agent, a water repellent, and a curing agent. Hereinafter, these treatments are abbreviated as the treatment of the present invention, and these treatment agents may be abbreviated as the treatment agent of the invention. The treatment of the present invention is performed on waste paper before fibrillation or on waste paper fibers during or after fibrillation.
The treatment of the present invention may be performed in a dry state of waste paper or waste fiber, or in a wet state. When the treatment is performed in a wet state, in order to strengthen the bond between the waste paper fiber and the treatment agent, it is desirable that the treatment agent be brought into contact with the waste paper fiber and then be dried at least once at a solid content concentration of 90% by weight or more. As a method for bringing the used paper fiber into contact with the treating agent of the present invention, for example, impregnation, coating, spraying, mixing, or the like can be used.

[0012] The defibration of waste paper or the like can be performed by a dry method or a wet method. Examples of machines used for defibration include, for example, grinders such as a pocket grinder, a chain grinder, and a ring grinder, refiners such as a single disc refiner, a double disc refiner, and a conical type refiner, beaters and other beating machines, and blenders and deflakers. Stirrers, wood chip defibration machines such as defibrator and defibrillator, and other facilities such as fluffer and other flash-dried pulp manufacturing equipment. Among them, a machine having a mechanism capable of forcibly supplying a raw material, such as a pressurizing method or a screw method, is preferable because the fibrillation can be performed continuously and efficiently. These are generally of various types, such as a machine for processing wet fibers and a machine for processing dry fibers. However, if they can be used regardless of wet or dry, they can be appropriately used as a defibrating machine. However, dry defibration using no water or using only a small amount of water is preferable in terms of easy water repellency, water resistance, hardening treatment, and drainage treatment. In the case of the wet method, the defibration efficiency and the load of the subsequent dehydration and drying step can be suppressed,
Fibrillation in a state where the solid content is high is more preferable. The defibration of the used paper is preferably performed so that the Canadian Standard Freeness (CSF) of the used paper fibers after the treatment of the present invention is 550 ml or more.

Next, the treating agent of the present invention will be described.
As the curing agent, a fibrin-reaction-type chemical that performs a cross-linking reaction between fibers or a cross-linking reaction between fibers and a chemical can be used. Examples of the fibrin reaction type chemical include fiber cross-linking agents described in US Pat. No. 2,971,815, and more specifically, aldehydes (formaldehyde and glyoxal, glutar Dialdehydes such as aldehydes), N-hydroxymethyl compounds (formaldehyde, urea, cyclic urea, triazine,
Reaction products with amides, acrylamides, carbamates and the like, such as dimethylolurea, dimethylolethyleneurea, trimethylolmelamine, N-methylolamide,
N-methylolacrylamide, ethylene-bis-
(N-methylol carbamate, etc.), divinyl compound (divinyl sulfone, etc.), halogen compound (dichloroacetone, 1,3-dichloropropanol-2, chloromuconic acid, cyanuric chloride, dichloroacetic acid, etc.), epoxy compound (halohydrin such as epichlorohydrin, Polyepoxides such as butadiene diepoxide and polyglycidyl ether, aziridinyl compounds (Tris- (aziridinyl) phosphine oxide, Tris- (aziridinyl) phosphine sulfide, carbonyl-bis-aziridine, etc.), polycarboxylic acids (maleic acid, citric acid) , Tricarballylic acid, melitic acid, cyclopentanetetracarboxylic acid, etc.), acid anhydrides (phthalic anhydride, maleic anhydride, succinic anhydride, etc.), polyvalent isocyanates (hexamethylene diisocyanate, 2,4-tri Quaternary ammonium salts (such as quaternary ammonium derivatives of Bis-chloromethyl ether),
And the like.

Examples of the water repellent include acid chloride type water repellent, isocyanate type water repellent, ketene dimer type water repellent, pyridine condensation type water repellent, ethylene urea type water repellent, and methylol compound type repellent. Water agent, ethylene oxide type water repellent, silicon compound type water repellent, chromium complex compound type water repellent, titanium containing compound type water repellent, zirconium containing compound type water repellent, fluorine compound type water repellent, silicon compound Mold water repellent and the like. Other water repellents include oils and fats (vegetable oils, animal oils, vegetable fats, animal fats), higher aliphatic compounds (saturated or unsaturated acids, alcohols, esters, amines, amides, salts), waxes (vegetable waxes, Animal wax, mineral wax, petroleum wax, modified wax) and the like.

As the water-proofing agent, the above-mentioned fibrous reaction type chemicals and waxes can be used, and further, water-insoluble resins can be used. Examples thereof include rosin-based resins, terpene-based resins, natural rubber, synthetic rubber, thermoplastic synthetic resins, thermosetting resins, and the like. As a thermoplastic resin,
Examples include hydrocarbon resins, acrylic resins, vinyl acetate resins, vinyl chloride resins, polyamide resins, polyester resins, and the like. Examples of the thermosetting resin include an epoxy resin, a urethane resin, a melamine resin, a urea resin, a formalin resin, and a phenol resin.

Further, any one of water resistance, water repellency, and curing,
Alternatively, in addition to those described above, sizing agents, waterproofing agents, waterproofing agents, and the like generally used for paper or fiber sizing and waterproofing can be used as those having a plurality of functions.

The above-mentioned treating agents of the present invention can be used alone or in appropriate combination of two or more kinds. In addition, these can be used as they are, in a molten state, or in a form dissolved, mixed, emulsified, or dispersed in a medium.
Further, some chemicals can be used after being further modified. The amount of the treatment agent is not particularly limited,
Usually, it is added in the range of 0.2 to 50 parts (solid content) based on 100 parts of dried waste paper. Among the above treatment agents, a fiber crosslinking agent is particularly preferred in terms of the effect.

Next, a curled waste paper fiber obtained by performing a curl treatment at the same time as the treatment of the present invention as a treatment particularly effective for reducing the density will be described. As the curl treatment, for example, during or after the treatment agent such as a cross-linking agent or a resin is added to the waste paper fiber during or after the defibration treatment, mechanical stirring is performed to deform the fiber,
Then, fluffing and heat treatment are performed to fix the deformation. More specifically, a crosslinked fiber having an average water retention of 28% to 50% obtained by crosslinking the inside of a cellulosic fiber using a C2 to C8 dialdehyde and a C2 to C8 monoaldehyde having an acid functional group (particularly, Fairness 5-7
No. 1702) and a water retention of 25% to 6 obtained by internally crosslinking cellulosic fibers using C2 to C9 polycarboxylic acids.
Examples thereof include fibers obtained by treating waste paper fibers by a method such as 0% crosslinked fiber (see JP-A-3-206174, JP-A-3-206175, and JP-A-3-206176).

As the machine used for the curl treatment, any machine can be used as long as it can mechanically apply a shearing force to the fiber. For example, a machine such as a kneader, a refiner, and a fluffer can be used. Can be mentioned.

Among the curled waste paper fibers, those having a curl factor of 0.4 or more are preferable because the effect of improving the low density property is particularly excellent. Above all, those having a wet curl factor in the range of 0.4 to 1.0 have the property that the curl shape is well maintained even in a state where they are wet for a long time, and even when manufactured for a long time. It is particularly preferable because a molded product having stable quality can be obtained. If the wet curl factor is less than 0.4, the effect of lowering the density becomes slightly inferior, while if it exceeds 1.0, the pulp fiber produced by strengthening the mechanical treatment when deforming the pulp fiber is produced. Due to the decrease in fiber strength due to the damage, paper powder is likely to be generated, which is practical but not preferable.

Incidentally, the curl factor is an index indicating the degree of deformation of the fiber in a dry state, and the actual length (LA) of the curled waste paper fiber and the maximum projected length of the fiber (the longest length of the rectangle surrounding the fiber). The length of the side (LB) is measured using a microscope, and the value calculated by [(LA / LB) -1] is used to quantify how much the original fiber length is curved. It was done. Also, the wet curl factor is
It is an index indicating the degree of deformation of the fiber in a wet state. The actual length (LA) of the fiber after immersing the curled waste paper fiber in pure water at room temperature for 24 hours and the maximum projected length of the fiber (the fiber The length of the longest side of the surrounding rectangle (LB) is measured using a microscope, and the value calculated by [(LA / LB) -1] is used to calculate how much a curve is formed from the linear original fiber length. Is a numerical representation of the

As the curled waste paper fiber, those having a water retention of 70% or less, which has good drainage and good drying properties, are preferable. By the way, the water retention was set to 300 minutes for the fibers in the wet state.
The amount of water held by the fiber after dehydration by the centrifugal force of 0 G is defined as a value (%) expressed as an amount per unit weight of absolute dryness, and the measuring method is JAPAN TAPP.
I No. 26-78.

Although a low-density body can be obtained by using the waste paper fiber treated alone according to the present invention alone, if it is necessary to improve the low-density property and the interlayer strength, other fiber components may be added to the slurry composition. Alternatively, it is preferable to add a granular, flake or needle component. Examples of other fibers include natural polymer fibers, synthetic polymer fibers, semi-synthetic polymer fibers, and fibers obtained by treating them. Among them, the bond reinforcing factor 0 Fine fibers of .15 or more are preferred. or,
Curled fibers are preferred in that the effect of improving the low density property is large.

Examples of the natural polymer fiber include unbleached or bleached chemical pulp obtained by kraft pulping, sulfite pulping, alkali pulping, etc. of coniferous or hardwood, GP, RMP, TMP, CTMP and the like. Mechanical pulp, or cellulosic fibers such as cotton pulp, linter pulp, liquid ammonia-treated pulp and mercerized pulp, protein fibers such as wool, silk and collagen fibers, chitin / chitosan fibers and alginic acid fibers And the like. As synthetic polymer fibers,
For example, aromatic polyester fiber, aliphatic polyester fiber, polyethylene fiber, polypropylene fiber, polyethylene-polypropylene sheath core fiber, polyacrylonitrile fiber, acrylic fiber, polyamide fiber and the like can be mentioned. Examples of the semi-synthetic polymer fibers include fibers obtained by chemically modifying natural products, such as acetyl cellulose fibers.

Among these, those having biodegradability such as cellulosic fibers, aliphatic polyester fibers, and acetylcellulose fibers are preferably used.
Specific examples include fibers such as Bionole (Showa Kobunshi), Lacia (Mitsui Chemicals), Lunar ZT (Nippon Shokubai), and general-purpose pulp. Above all, from the viewpoints of stability of raw material supply and cost, cellulose fibers or those obtained by treating the same are preferred.

Although the size of the fiber is not particularly limited, the number average fiber length is usually 0.01 to 50 m.
In the range of m, a fiber width of 0.1 to 500 μm is preferably used. The amount of the fiber in the composition is
Although not particularly limited, it is usually 1% by dry weight with respect to the composition.
It is blended in the range of 70%.

Among the fine fibers having a bond reinforcing factor of 0.15 or more, fine fibers obtained by subjecting fibers to mechanical treatment are more preferable. Those subjected to mechanical treatment tend to have a branched shape, and the effect of increasing the interlayer strength is extremely large. Among them, unbleached or bleached chemical pulp obtained by kraft pulping, sulfite pulping, alkali pulping, etc. of coniferous or hardwood, or GP, in view of the effect of increasing the interlayer strength and the ease of production RMP, T
Mechanical pulp such as MP, CTMP, etc., or cellulosic fiber known as a papermaking raw material such as cotton pulp, linter pulp, waste paper pulp, etc. is mixed with a medium stirring mill (Japanese Patent Laid-Open No. 4-1).
No. 8186), a vibrating mill (JP-A-6-10286), a high-pressure homogenizer, a colloid mill, a beating machine or the like obtained by wet mechanical treatment are particularly preferable.

The binding enhancement factor (BF) referred to in the present invention
Is calculated by (E2−E1) / E1. However, E1
Is a mixture of bleached hardwood kraft pulp 50% by weight and softwood bleached kraft pulp 50% by weight to form an aqueous slurry,
After beaten to 500 ml of Canadian Standard Freeness (CSF), dewatered and air-dried with a hand making machine according to JIS-P-8209 to prepare a sheet having a basis weight of 60 g / m ² ,
The figure shows the ultrasonic elastic modulus measured after heat treatment at 30 ° C. for 2 minutes and humidity control at 20 ° C. and 65% RH. E2 indicates the ultrasonic elastic modulus when an aqueous slurry was prepared by replacing 50% of the pulp fibers with fine fibers, and a sheet was prepared and measured in the same manner as in the measurement of E1.

In the present invention, when a fine fiber having a bond reinforcing factor of less than 0.15 is used, the effect of improving the interlayer strength is slightly weak when blended in a small amount, and the interlayer strength is increased but the low density is slightly lowered when blended in a large amount. There is a tendency.

The size of the fine fibers is not particularly limited, but usually the number average fiber length is 0.01 to 0.5.
Those having a fiber width in the range of 80 mm and 0.1 to 30 μm are preferably used. The amount of the fine fibers to be added to the composition is not particularly limited, but is usually 1 to 40% by dry weight of the composition.

As the curled fiber, the above natural polymer fiber, synthetic polymer fiber, or semi-synthetic polymer fiber is subjected to a chemical treatment, a mechanical treatment, a thermal treatment, or the like, and the fiber is curled or twisted. Can be given. Among them, those obtained by curling biodegradable fibers such as cellulose fibers, aliphatic polyester fibers, and acetylcellulose fibers are preferably used. Specific examples include curled synthetic fibers and curled cellulosic fibers made from bionole (Showa Kobunshi), Lasia (Mitsui Chemicals), Lunare ZT (Nippon Shokubai) and the like. Among them, curled cellulosic fibers are preferred from the viewpoints of stability of raw material supply and price.

The curled cellulosic fiber is obtained by adding a cross-linking agent to the cellulosic fiber, subjecting the fiber to mechanical agitation to deform the fiber, followed by fluffing and heat treatment to fix the deformation. So, for example,
Product name: HBA-FF, NH, manufactured by Warehauser, USA
B405, NHB416 and the like. As the cellulosic fiber used as a raw material, for example, softwood,
Unbleached or bleached chemical pulp obtained by hardwood kraft pulping, sulfite pulping, alkali pulping, etc.
Alternatively, mechanical pulp such as GP, RMP, TMP, and CTMP, or cotton pulp, linter pulp, and the like may be used.

Among the curled cellulosic fibers, those having a wet curl factor in the range of 0.4 to 1.0 are excellent in the effect of improving the low density property and, when they are wet in water for a long time. This is particularly preferable because it has the property of maintaining a good curl shape and can provide a molded product of stable quality even in a wet state in a manufacturing process for a long time.

As the curled cellulosic fiber, those having a water retention of 70% or less, which has good drainage and good drying properties, are preferable. The amount of the curled fiber to be added to the composition is usually 5 to 60% by dry weight of the composition. Two or more curled fibers may be used in combination.

As other fibers, besides the above, fibrous wastes other than waste paper can also be used.
Examples of the garment include used products of used clothing made from natural fibers such as hemp, silk, and wool. They are,
In some cases, the treatment of the present invention can be performed to replace used paper.

The granular, flake or needle-like components that can be added to the slurry composition include the following coarse powders. For example, wood, bagasse, rice straw, cellulosic coarse powder obtained by coarsely pulverizing cellulosic material such as coconut shell fiber, sawdust, rice husk, soybean meal, etc., natural organic polymer coarse powder, such as polyethylene and polystyrene. Examples include synthetic organic beads such as synthetic resin beads, foamed resin such as polystyrene foam, and crushed old tires; and coarse particles such as semi-synthetic organic polymers such as acetylcellulose coarsely pulverized products.
These meals have a Canadian Standard Freeness (CSF) of 5
Those showing 50 ml or more are preferred. Among them, coarsely ground natural organic polymer coarse powder and acetyl cellulose are preferable because they have biodegradability and are environmentally friendly. Among them, cellulosic coarse powder obtained by mechanically fibrillating wood and used as a raw material for fiberboard is particularly excellent in the effect of improving low-density, and it is particularly preferable because raw material can be easily procured. Examples of the defibration method include those known in the fiberboard industry, such as the asplund method. Among them, those that are defibrated at a high temperature of 110 ° C or more and 130 ° C or more are more than those processed at a lower temperature. Easy to become high rigidity,
For this reason, it is easy to obtain an excellent effect of improving the low density property and the buffer property, which is preferable. In addition, as a means for increasing the rigidity, a method of performing a crosslinking reaction treatment, a hydrophobic treatment, and a surface resin treatment after the defibration treatment of the wood chips is effective. Further, the above-mentioned pulverized product or a product obtained by further performing a curling treatment with a kneader or the like is particularly preferable because the effect of improving the buffering property is more remarkable. Also, among coarse powders, 3
The one obtained by removing fine regions by passing through 0 to 200 meshes is preferable because the wastewater treatment at the time of manufacturing a compact is easy and the raw material yield is good. The amount of the coarse powder blended into the composition is not limited to this range, but is usually blended in a range of 10 to 60% by dry weight with respect to the composition.

Incidentally, the Canadian standard freeness is based on JIS.
-P-8121 and usually indicates the drainage of pulp. In the present invention, the drainage of the cellulosic coarse powder and the cellulosic coarse powder-containing composition was determined based on the same measurement method.

In the slurry composition, inorganic fibers, metal fibers, paper strength agents, water-proofing agents, water-repelling agents, foamable microcapsules, etc. may be appropriately added as necessary for improving performance or imparting functions. Sizing agent, dye, pigment, retention aid, filler, P
H regulator, slime control agent, thickener, preservative,
Antifungal agent, antibacterial agent, flame retardant, preservative, rodenticide, insecticide, moisturizer, freshness preservative, oxygen absorber, microcapsule, foaming agent, surfactant, electromagnetic shielding material, antistatic agent, rust inhibitor , A fragrance, a deodorant and the like can be selected and blended.
These may be used in combination of two or more.

Examples of the inorganic fiber and the metal fiber include glass fiber, carbon fiber, activated carbon fiber, alumina fiber, silicon carbide fiber, silica / alumina silicate fiber, rock wool fiber, and stainless steel fiber.

Examples of the paper strength agent include starch, processed starch, vegetable gum, dry paper strength agent such as PVA, urea formaldehyde resin, melamine formaldehyde resin, polyamide urea formaldehyde resin, ketone resin, polyamide epichlorohydrin resin, polyamide Examples include wet paper strength agents such as polyamine epichlorohydrin resin, glycerol polyglycidyl ether resin, and polyethyleneimine resin.

As the water-proofing agent, the above-mentioned wet paper strength enhancer can be used as a water-proofing agent, and formaldehyde having an aldehyde group, glyoxal, dialdehyde starch,
Examples thereof include ammonium zirconium carbonate, which is a polyvalent metal compound. Examples of water repellents include various waxes (natural wax, petroleum wax, chlorinated paraffin, wax emulsion, etc.), higher fatty acid derivatives, synthetic resins,
Chromium complex salts, zirconium salts, silicon resins and the like can be mentioned.

As foamable microcapsules, for example, isobutane, pentane, hexane, and the like are contained in thermoplastic resin fine particles made of a copolymer such as vinylidene chloride, acrylonitrile, acrylate, and methacrylate.
Particles containing low-boiling solvents such as low-boiling halogenated hydrocarbons and having an average particle diameter of 5 to 50 μm that expands 3 to 5 times in diameter and 30 to 120 times in volume at a temperature of 70 to 150 ° C. Is mentioned. Although the foamable microcapsules have an effect of further reducing the density of the molded body, the same effect can be expected from particles obtained by pulverizing a thermoplastic resin mixed with a foaming agent. The thermoplastic resin is preferably an environmentally biodegradable resin.

The slurry of the composition is usually prepared batchwise or continuously using an apparatus having a stirrer. Fibers that have been treated for water repellency, water resistance, and curing tend to lose their stiffness due to long-term wetting, or have a tendency to decrease their water repellency and water resistance and increase their water retention. It is preferable not to leave it for 24 hours or more, and it is particularly preferable to leave it within 5 hours. In addition, a continuous preparation method in which the slurry is prepared in conjunction with the molding step is preferable because the quality of the low-density body in which the wet time is kept almost constant is easily stabilized.

Water is usually used as a dispersion medium used for forming a slurry. In addition, an alcohol such as methanol or ethanol, an organic solvent such as acetone, ethyl acetate or glycerin, or a mixture of water and an alcohol is used. be able to. When using a mixture of water and alcohol,
There are advantages such as good drying properties and increased productivity. Heating the medium also has the effect of increasing the drying rate. The concentration of the slurry is usually 0.05 to 10% by weight of dry solid content.
, But is preferably in the range of 0.05 to 5% by weight in terms of the dispersion state.

As the composition used for forming the slurry, those having a Canadian Standard Freeness (CSF) of 550 ml or more are preferred because of their excellent low-density productivity and low-density.

Hereinafter, the production of a molded product in which the effects of the present invention are particularly remarkable will be mainly described. As a molding die used for the production of a molded product, a normal pulp molding die can be used as it is, but when a block-shaped molded product having better cushioning properties is required, a large number of A deep-bottomed container having a small hole, 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. The size of the small holes may be such that the pulp fiber hardly leaks, and usually has a diameter or a side of 30 μm to 3 μm.
A circular or square shape in the range of mm is used, but is not particularly limited in the present invention. Usually, when the fiber or the like is large, a large one is used, and when the fiber is small, a small one is used. It is also possible to use a molding container wall having relatively large holes, such as a mold used for pulp molding, with a fine mesh attached to the wall. Also, the size of the small holes can be changed in each part of the molding container.
Also, the small holes need not necessarily be present on the entire surface of the molded container wall, and may be present only on the bottom in the case of a cylindrical container. In consideration of the dehydration efficiency and the like, it is preferable that small holes are present in a portion of 20% or more of the wall of the molding container, more preferably 35% 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 cylindrical container, the slurry is injected into the molding container having an open port with an upward opening by a pump from the opening, and the slurry is opened with the opening downward as in a normal pulp mold. The slurry is immersed in the tank and sucked into the forming container from the downward opening by sucking through the small hole. In the case of a split container, a method such as press-fitting into a molding container by using a slurry injection tube can be used. 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 and the like, and these can be combined.

The wet molded product formed in the forming container by removing the water of the dispersion medium from the small holes is then taken out of the container or taken out of the container and dried. In the case of drying in a container, a molded product having high dimensional accuracy can be obtained, but the productivity is poor. On the other hand, in the case of drying outside the container, the dimensional accuracy is slightly inferior, but the productivity is excellent. As an intermediate proposal, a method may be employed in which after drying in a container is performed halfway, the container is taken out and dried outside the container.

As a 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 can be used instead of hot air for drying halfway. Among them, the hot air drying method is preferred because the apparatus is inexpensive and the molded product is less likely to burn. Above all, air drying in which the flow of air in the inter-fiber voids is improved by injecting heated air (gas) into a wet molded product or by suction while inserting heated air from the opposite side of the molded product,
Drying is quick and the production efficiency of the molded product is extremely high, which is particularly preferable. In hot air drying, hot air in a temperature range of usually 80 to 400 ° C. is used. The amount of airflow for through-air drying was 2 at the beginning of drying.
The liter / (cm ² · min) or more is preferable from the viewpoint of drying efficiency, and the liter / (cm ² · min) or more is particularly preferable.
This through drying is particularly effective when drying a molded product having a thickness of 10 mm or more, particularly 40 mm or more. In order to increase the drying speed of the molded body, the surface of the molded body is intentionally made uneven to increase the surface area, or a hole is formed in the molded body to penetrate or non-penetrate so that air can easily enter the interfiber space. Is also effective. As a preferable method for drying a molded body having a thickness of 40 mm or more, non-through holes are provided at intervals of 10 to 30 mm at a thickness of the molded body of 30 mm or more. ~ 300 ° C hot air,
A method of injecting at a pressure of 1 to ³ kg / cm ² can be given. As a method of intentionally forming irregularities on the surface of the molded body, a method of providing an irregular pattern on a molding die is effective, and a method of providing a through hole or a non-through hole in a molded body is effective using a water flow such as a water jet. It is. In addition, a method in which the forming container is heated before pouring the slurry has an effect of increasing the drying speed.

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 supplied from the upper guide 15.
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 density of the molded product is set at 0.
Those having a range of 02 to 0.30 g / cm ³ are preferable. The molding method is not limited to the one described above, while injecting the slurry under pressure into a split mold filled with water, gradually extruding the water in the split mold to fill it with fibers, and thereafter A method in which hot air is blown out from a pipe inserted into the center of the split mold and dried is also effective.

The molded product may be provided with a paper strength enhancer, a waterproofing agent, a water repellent, a dye, a pigment, a preservative, an antifungal agent, an antibacterial agent, a flame retardant, a rodenticide, an insect repellent, a freshness preserving agent, a deoxidizing agent, As a method of incorporating an electromagnetic shielding material, an antistatic agent, a rust preventive, an aromatic agent, a deodorant, etc., other than the internal addition method of adding and mixing these in a slurry as described above, the surface of the molded body may be prepared after manufacturing. A coating method, that is, an external addition method can also be used. Means such as impregnation, brushing, and spraying can be used for this surface application. Of course, both internal and external additions may be used. In the case of external addition, the above fine fibers can also 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, water resistant paper, oil resistant paper, vapor-deposited paper, coated paper, cardboard, paperboard, synthetic paper, nonwoven fabric, cloth, synthetic film, metal foil, wood board, synthetic resin board Another material such as a glass plate, a metal plate, or the like can be used by being completely or partially adhered. Further, the obtained molded bodies can be bonded together. As a means for providing a film layer on the surface of the molded product, shrink packaging technology can be used. As materials used in combination, environmentally friendly materials such as biodegradable materials are preferable. In addition, the molded body may be subjected to processing such as cutting and printing.

The molded article thus obtained is characterized by its low density, cushioning property, heat insulation, sound insulation, moisture absorption, biodegradability, etc. It can be widely applied to the field. In addition, it can be used in the field of filters by taking advantage of air permeability. In addition, fields such as mannequins are also promising because of their low density.

The most remarkable effect of the present invention is a molded product, but it is also effective for sheets and boards.
This is briefly described below. When a sheet is obtained by the present invention, the sheet can be produced using a paper machine known in the papermaking industry such as a round paper machine, a fourdrinier paper machine, an inclined wire paper machine, and a twin wire paper machine. The thickness of the sheet is usually 30 μm to 5 m
m. The density of the obtained sheet is affected by the raw material and composition of the slurry composition. In addition, the pressure applied to the sheet during the production stage is important. It is necessary to keep the dewatering pressure of the wire part low and the press pressure of the wet press part low. The press linear pressure at that time is 30 kgf / cm or less, and in particular 20 kf / cm.
gf / cm or less is preferable. In view of the range of application development, those having a density in the range of 0.02 to 0.30 g / cm ³ are preferable. For the drying step, any method known in the art can be used. Among them, hot-air ventilation drying in which a heated air jet is blown on the paper surface is preferable because the drying speed is increased.

The resulting low-density sheet is made of a high-quality paper or fine-coated paper as it is, or is subjected to post-processing such as surface coating or impregnation, making use of features such as light weight, heat insulation, cushioning and air permeability. Base paper, art paper, coated paper, base paper for thermal recording, base paper for thermal transfer receiving paper, base paper for sublimation transfer receiving paper, base paper for pressure-sensitive copying paper,
Base paper for paper cups, base paper for lamination, base paper for vapor deposition,
It can be used as electrophotographic copying paper, wrapping paper, heat insulating paper, filters, fancy paper and the like. In the field where surface smoothness, stiffness and whiteness are required, it is effective to use a Yankee machine, or to make a multi-layer papermaking using fibers that easily produce surface smoothness or fibers having high whiteness as a surface layer forming material. is there.
Also, an ultra-lightweight coated paper can be obtained by applying a hollow plastic pigment-containing paint or a bubble-containing paint on the low-density sheet. In addition, other materials can be attached and used according to the purpose.

The board usually has a thickness of 5 mm to several cm, and is a paper machine known in the paper industry, a machine known in the board industry, and a relative rotary twin mesh for making thick materials such as an inclined wire paper machine and a twin wire paper machine. It can be manufactured by an apparatus having a cylinder partially. The density of the resulting board is affected by the raw material and formulation of the slurry composition,
Besides that, the pressure on the board during the manufacturing stage is important,
In order to keep the density as low as possible, the degree of vacuum of the suction roll is suppressed to keep the dehydration pressure of the wire part low.
Alternatively, it is necessary to keep the press pressure of the wet press part low. The press linear pressure at that time is 30 kgf /
cm or less, especially 20 kgf / cm or less.
Density is 0.02 to 0.30 g, considering the breadth of applications.
/ Cm ³ is preferable. Water cutting is effective for cutting off the edge or cutting the wafer into a single sheet. For the drying step, any method known in the art can be used. Among them, a method of injecting heated air (gas) into a wet board, or suctioning while injecting heated air from the opposite side of the board, is used. The through-flow drying in which the air flow in the inter-fiber voids is improved is particularly preferable because the drying is quick and the production efficiency of the molded product is extremely high. In hot air drying, hot air in a temperature range of usually 80 to 400 ° 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. This through-air drying is more than 10mm thick, especially 40m
This is particularly effective when drying a board of m or more. In order to increase the drying speed of the board, it is also effective to intentionally make unevenness on the board surface to increase the surface area, or to make a hole that penetrates or non-penetrates the board so that air can easily enter the inter-fiber space. is there. As a method of providing the unevenness, the through hole, or the non-through hole in the board, a method using a device having an uneven wire is effective.

The obtained low-density board is unprocessed or is bonded, surface-coated, impregnated, cut, etc., taking advantage of its features such as light weight, heat insulation, cushioning, soundproofing, moisture absorption and air permeability. It can be used in fields where foamed resins have been used so far, for example, building materials, packaging materials, automotive ceiling materials, etc., and filters.

[0062]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but it should be understood 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 50 g of used newspaper (absolute dry weight)
Is cut by a press cutter into small pieces of about 50 mm × 50 mm, and then an imidazolidone-based cross-linking agent (trade name: Sumitex NF-500K, manufactured by Sumitomo Chemical Co., Ltd.) and its cross-linking assistant (trade name: Sumitex ACCELERATE)
R MX (manufactured by Sumitomo Chemical Co., Ltd.) was impregnated into 50 g of an aqueous solution containing 1.50 g and 0.75 g in terms of active ingredients, respectively. This impregnated waste paper was placed in a Warburg blender in a wet state and fibrillated. Next, the fiber was taken out of the bag, placed in a stainless steel vat, and heated in a blow dryer at 150 ° C. for 30 minutes to complete the crosslinking reaction. When the freeness of the fiber subjected to the crosslinking agent treatment was measured, it was 695 ml.
Next, 16 g (absolute dry weight) of this treated waste paper fiber was fractionated, water was added to adjust the solid content concentration to 2%, and the resulting slurry was stirred well. A 52 mmφ aluminum circular punching plate and a 52 mmφ 80 mesh circular stainless steel wire were sandwiched between two types of alloy pipe fittings (50 mm inner diameter, 100 mm long nipple, 50 mm × 25 mm inner diameter socket). The mixture was poured into a metal container while sucking it from the side of the reduced-diameter socket with a water ring vacuum pump to form a wet molded product in the long nipple. Then, while suctioning from below with a vacuum pump, a hot air generator (trade name: Hot Gale, model: HT2-10, Co., Ltd.) from above
(Miyamoto Seisakusho)) and dried by blowing hot air at 250 ° C. The time required for drying was 5.8 minutes. When the physical properties of the obtained molded body were measured, the density was 0.13 g / cm ³ and the cushioning property was good.

<Example 2> A 1-liter double-arm kneader (model: S1-
1, Moriyama Seisakusho), 6 arms each at room temperature
The rotation was performed at 0 rpm and 100 rpm, and a kneading treatment was performed for 40 minutes. Next, the used paper subjected to the kneading treatment was put into a Warburg blender in a wet state in the same manner as in Example 1, and was fibrillated. further,
The fibers were taken out of the bag, placed in a stainless steel vat, and heated in a blow dryer at 150 ° C. for 30 minutes to complete the crosslinking reaction, thereby obtaining curled fibers. The curl factor and wet curl factor of the used paper fiber which was curled at the same time as the crosslinking agent treatment were 0.98 and 0.53, respectively. When the freeness of this fiber was measured, it was 705 ml. Next, 16 g (absolute dry weight) of this treated wastepaper fiber was fractionated, and a slurry was prepared in the same manner as in Example 1 to produce a molded body. The time required for drying was 2.5 minutes. When the physical properties of the obtained molded body were measured, the density was 0.10 g.
/ Cm ³ , and the buffering property was good. The methods for measuring the curl factor, wet curl factor and freeness are described below.

<Evaluation method> [Measurement method of curl factor] 100 fibers were placed on a microscope slide glass, and an image analysis device was used.
The actual (linear) length LA (μm) and the maximum projected length (equal to the length of the longest side of the rectangle surrounding the fiber) LB (μm) of each fiber are measured, and the wet curl factor is calculated as follows. The average value was obtained from the equation. Curl factor = (LA / LB) -1

[Measurement Method of Wet Curl Factor] After immersion in distilled water at room temperature for 24 hours, 100 fibers were placed on a microscope slide glass, and the curl factor in a wet state was measured according to the above-described curl factor measurement method. Was done.

[Measurement Method of Freeness]
The measurement was performed according to the Canadian Standard Freeness Measurement Method specified in IS-P-8121. However, the freeness of the pulp in a dry state was prepared by preparing a sample of 3 g of absolutely dry, disintegrating with a disintegrator for 1 minute, and adding water to make the total volume 1 liter, which was immediately subjected to measurement.

<Embodiment 3> A used newspaper was cut into a small piece of about 50 mm x 50 mm by cutting it with a press cutter.
A clearance of 0. 2 inch is used using a 2 inch refiner (manufactured by Kumagai Riki Kogyo Co., Ltd., model: BR30-300HB).
Dry defibration treatment was performed at room temperature at 70 mm, and furthermore, waste paper (small pieces of uncrushed waste paper) was removed to obtain waste fiber. Subsequently, 50 g (absolute dry weight) of the waste paper fiber was dispensed into a plastic bag, and then a styrene / butadiene latex (trade name: Nipol LX432A, manufactured by Zeon Corporation) was diluted with water to obtain a solid content of 5%. % Of the waste paper fiber was sprayed onto the waste paper fiber using a spray. Next, the fiber was taken out of the bag, put in a stainless steel vat, and dried by heating in a blow dryer at 150 ° C. for 30 minutes. When the freeness of this fiber was measured, it was 7
It was 20 ml. Next, 16 g (absolute dry weight) of this treated wastepaper fiber was fractionated, and a slurry was prepared in the same manner as in Example 1 to produce a molded body. The time required for drying was 7.6 minutes. When the physical properties of the obtained molded body were measured, the density was 0.14 g / cm ³ and the cushioning property was good.

Example 4 Approximately 50 g of a commercially available fluororesin-based water repellent (trade name: Rainguard, manufactured by Lion Corporation, active ingredient: about 2%) per 100 g of used newspaper (absolute dry weight)
Was spray-coated one by one and then completely dried in a blow dryer at 105 ° C. Then, after cutting into small pieces of about 50 mm × 50 mm using a push cutter, a 12-inch refiner (manufactured by Kumagaya Riki Kogyo Co., Ltd., model: BR3)
(0-300HB) with a clearance of 0.70 mm at room temperature and dry defibration at room temperature and further removal of waste paper (small pieces of uncrushed waste paper) to obtain waste paper fibers subjected to a water-repellent treatment. . When this freeness was measured, it was 73
It was 5 ml. Next, 16 g (absolute dry weight) of this treated wastepaper fiber was fractionated, and a slurry was prepared in the same manner as in Example 1 to produce a molded body. The time required for drying was 8.2 minutes. When the physical properties of the obtained molded body were measured, the density was 0.16 g / cm ³ and the cushioning property was good.

<Example 5> 50 g (absolute dry weight) of used newspaper fiber obtained in the same manner as in Example 3 except that the refiner treatment and the removal of the used paper were carried out were taken out into a plastic bag, and then the wax emulsion was water-repellent. (Trademark: Size Pine W-10)
9, Arakawa Chemical Industry Co., Ltd.) was diluted with water, and a liquid having an active ingredient concentration of 5% was sprayed onto the waste paper fiber with stirring using a spray. Next, the fiber was taken out of the bag, put in a stainless steel vat, and dried by heating in a blow dryer at 150 ° C. for 30 minutes. When the freeness of this fiber was measured, it was 740 ml. Next, 16 g (absolute dry weight) of the waste paper fiber subjected to the water repellent treatment was fractionated,
A slurry was prepared in the same manner as in Example 1 to produce a molded body. The time required for drying was 6.8 minutes. When the physical properties of the obtained molded body were measured, the density was 0.15 g / c.
m ³ and the buffering property was good.

Example 6 8 g (absolute dry weight) of a water-repellent waste paper fiber obtained in the same manner as in Example 5 was fractionated.
Then, 8 g (absolute dry weight) of a commercially available curled fiber (trade name: NHB405, manufactured by Warehauser, USA) having a wet curl factor of 0.65 and a water retention of 58% and water are added so that the solid content concentration becomes 2%. , And stirred well to obtain a slurry. Next, a molded article was produced in the same manner as in Example 1 except that this slurry was used. The time required for drying was 3.6 minutes. When the physical properties of the obtained molded body were measured, the density was 0.11 g / cm ³ ,
The buffering property was good.

Example 7 A 1.5-liter Dynomill (model: KDL-PILOT, filled with 80% glass beads having an average particle size of 2 mmφ) was prepared by mixing a water slurry of bleached hardwood kraft pulp having a solid content of 1%. Fine fibers having a number-average fiber length of 0.28 mm and a bond reinforcing factor of 0.53 were obtained by introducing and passing through a device (manufactured by Shinmaru Enterprises) at 350 ml / min. The water retention of the fine fibers was measured and found to be 285%. 1.6 g (absolute dry weight) of the fine fiber obtained as described above was added to 14.4 g (absolute dry weight) of a waste paper fiber curled at the same time as the crosslinking agent treatment obtained in the same manner as in Example 2. ) And water were added to adjust the solid content concentration to 2%, followed by thorough stirring to obtain a slurry. Next, a molded article was produced in the same manner as in Example 1 except that this slurry was used. The time required for drying was 3.5 minutes. When the physical properties of the obtained molded body were measured, the density was 0.11 g / cm ³ and the cushioning property was good. Further, as compared with the molded body of Example 2, the generation of paper dust was small and the molding was good. Hereinafter, a method for evaluating the used fine fibers will be described.

<Evaluation Method> [Measurement Method of Bond Enhancement Factor] 50 parts of bleached hardwood kraft pulp (dry weight) and bleached softwood kraft pulp 50
Parts (absolute dry weight) were mixed, adjusted to a concentration of 2% with water, and beaten with a laboratory Niagara beater (23 L capacity) until the Canadian Standard Freeness (CSF) reached 500 ml. Subsequently, 3.7 g (absolute dry weight) of this stock was taken and a sheet was formed using a 150-mesh wire using a square (25 cm × 25 cm) hand making machine without adding chemicals, and a sheet was formed. Then, 3.5 according to a conventional method.
After performing wet press for 5 minutes (first press) and 2 minutes (second press) at a pressure of kg / cm ² , drying was performed at room temperature by a blast dryer between frames. Then 13
The sheet 1 having a basis weight of 60 g / m ² was prepared by heat treatment at 0 ° C. for 2 minutes, and was conditioned at 20 ° C. and 65% RH. On the other hand, N
50 parts of L-mixed beaten pulp and 50 parts of fine fiber were mixed, and 3.7 g (absolute dry weight) of the stock obtained by adjusting the concentration to 2% with water was taken, and sheet 2 was prepared in the same manner. 20 ° C, 65
% RH. After measuring the densities of the sheets 1 and 2, a dynamic Young's modulus measuring device (manufactured by Nomura Shoji Co., Ltd., model: S
The elastic modulus (GPa) of the sheets 1 and 2 was measured by measuring the ultrasonic wave propagation velocity using ST-210A). The elastic modulus (E) was calculated by the following equation. E (GPa) = ρ (g / cm ³ ) × {S (km / s)} ² where ρ is the density (g / cm ³ ) of the sheet after humidity control, and S is the ultrasonic wave propagation velocity (km / s). ). The elastic modulus of the sheet 1 is E1 (GPa), and the elastic modulus of the sheet 2 is E2 (GPa).
, The bond strengthening factor is ｛(E2 / E1) −
It is represented by 1｝.

[Measurement Method of Number Average Fiber Length] The measurement was carried out using a Kayani fiber length measuring instrument (model: FS-200).

[Measurement method of water retention] Water retention was measured by JAPAN
TAPPI No. It measured according to 26-78. 0.7 g (absolute dry weight) of the stock was dispensed, sufficiently dispersed in 100 ml of distilled water, and allowed to stand at room temperature for 24 hours to be sufficiently impregnated with water. Thereafter, the stock was collected on a filter, and then put into a centrifuge tube of a centrifuge (model: H-103N, manufactured by Domestic Centrifuge) having a G3 glass filter.
The mixture was centrifuged and dehydrated at 3000 G for 15 minutes. The sample subjected to the centrifugal dehydration treatment was taken out from the centrifuge tube, and the weight in a wet state was measured. Thereafter, the sample was dried to a constant weight with a dryer at 105 ° C., the dry weight was measured, and the water retention was calculated by the following equation. Water retention (%) = {(WD) / D} × 100 where W is the wet weight (g) of the sample after centrifugal dehydration, and D is the dry weight (g) of the sample.

<Comparative Example 1> 30 g of used newspaper (absolute dry weight)
Was cut into small pieces of about 50 mm x 50 mm by a push cutter, and water was added to adjust the solid content concentration to 2%. Then, the mixture was put into a 2 liter disintegrator and defibrated for 5 minutes. went. When the freeness of the obtained fiber was measured, it was 290 ml. Next, 16 g (absolute dry weight) of waste paper fiber was fractionated from this slurry, and a slurry was prepared in the same manner as in Example 1 to produce a molded body. The time required for drying was 15.8 minutes.
When the physical properties of the obtained molded body were measured, the density was 0.3
It was 8 g / cm ³ , and the cushioning properties were clearly inferior to those of the molded articles of Examples 1 to 7.

[0077]

According to the present invention, the following effects can be obtained. A molded article applicable to heavy objects is obtained. A molded article exhibiting excellent shock-absorbing properties against the second or subsequent drop impact is obtained. In addition, since there is no need to devise structural measures such as the rib structure, complicated molds such as the conventional pulp molding method are not required, and the time required for mold design and manufacturing can be greatly reduced. The mold can be manufactured at low cost. Since it can be manufactured with an inexpensive mold, the productivity can be increased by preparing many molds, and the production cost can be suppressed to a relatively low production cost even for a small lot and a wide variety of products. As described above, according to the present invention, it is possible to provide a molded article that is biodegradable and that is excellent in low density, buffer properties, and productivity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a molding container used for manufacturing a molded article of the present invention, in a state where solids in a slurry are deposited on the molding container.

FIG. 2 is a cross-sectional view showing a state in which unnecessary portions accumulated on the open surface of the molding container of FIG. 1 are cut.

FIG. 3 is a cross-sectional view of a state in which the wet deposit of FIG. 2 is dried.

FIG. 4 is a cross-sectional view of the final product obtained according to FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 Mold (molding container) 11 Small hole 12 Lower mold 13 Suction chamber 14 Suction port 15 Guide 16 Fiber slurry 17 Water drop 18 Fiber deposit 19 Water jet 20 Press machine upper die 21 Small hole 22 Hot air port 23 Final molded product

Claims (7)

[Claims] 1. A slurry containing waste paper fibers that has been subjected to at least one treatment selected from a water repellency treatment, a water resistance treatment, and a curing treatment, which is obtained by dehydrating and drying the slurry, and having a density of 0.02 to 0. A low-density body characterized by being 30 g / cm ³ . 2. The low density body according to claim 1, wherein the composition forming the slurry has a Canadian Standard Freeness (CSF) of 550 ml or more. 3. The treated waste paper fiber has a Canadian Standard Freeness (CSF) of 550 ml or more.
The low-density body according to 1. 4. In at least one treatment step selected from a water-repellent treatment, a water-resistant treatment, and a curing treatment, at least once after contacting a water-repellent agent, a water-resistant agent, and a curing agent with waste paper or waste paper fibers. 2. The low-density body according to claim 1, wherein waste paper fibers in a dry state having a solid concentration of 90% by weight or more are used. 5. The waste paper fiber has a curl factor of 0.5.
The low-density body according to claim 1, which is four or more curled fibers. 6. The slurry of claim 1, wherein the slurry contains a coarse powder having a Canadian Standard Freeness (CSF) of 550 ml or more.
The low-density body according to 1. 7. The low-density body according to claim 1, wherein the low-density body is a three-dimensional formed body having irregularities.