JP2000120000A - Low density article using waste paper as raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain a low density article having a density lower than former waste fibers obtained from wet opening by using a slurry in which dry-opened waste paper fibers are dispersed in water. SOLUTION: This low density article having >=10 mm thickness and 0.02-0.30 g/cm3 density is obtained by dispersing waste paper fibers obtained by supplying waste paper such as waste newspaper or waste magazine, etc., discharged from human's home to a dry opener into water to obtain a slurry having 0.5-5 wt.% of concentration, supplying to a mold shaping machine having a prescribed female mold, aspirating, dehydrating and drying.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a low-density body made of waste paper and having excellent low-density, buffering properties and productivity.

[0002]

2. Description of the Related Art Styrofoam conventionally used as a cushioning material has excellent characteristics such as excellent shock absorption, easy processing into an arbitrary shape, low cost, light weight, and good appearance. have. However, in recent years, as interest in environmental issues has increased, like other so-called plastic products, there has been an increasing demand for treating the processability 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.

In order to solve the problems in the processing of styrofoam, recently, pulp has been manufactured as a raw material, and a cushioning property and strength can be given by devising the shape. Pulp molds that can be easily treated 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, the pulp in the slurry is deposited in a mold having a large number of small holes while sucking and dewatering, and then dried to obtain a molded product. When the fiber obtained by wet defibration is molded as a raw material, as the accumulation of pulp in the mold progresses, the adhesion between the pulp fibers progresses, and the water drainage worsens. In this case, a long time was required for the suction / dehydration step, and unless the production efficiency was neglected, it was not possible to obtain a deposit having a thickness exceeding 10 mm.
For this reason, the obtained product was inferior in buffering properties, was not sufficiently strong, and lacked suitability as a packaging material. An object of the present invention is to provide a low-density body that is made of waste paper and has excellent low-density, buffering properties, and productivity.

[0005]

In view of the above situation, the present inventors have conducted intensive studies on molded articles made of waste paper, which have excellent low density and cushioning properties, and have high productivity. Instead of using waste paper fibers obtained by wet defibration as raw materials, they found that it could be achieved by using waste paper fibers defibrated in advance by dry method as a slurry raw material,
The present invention has been completed. That is, the present invention is obtained by dewatering and drying a slurry prepared by dispersing waste paper fibers obtained by dry defibration in water, and having a density of 0.02 to 0.30 g / cm. ³ is a low-density body. Especially, it is preferable that the thickness of the low density body is 10 mm or more. Further, it is preferable that other fibers are further added to the slurry. In particular, the other fiber is preferably a fiber having a bond reinforcing factor of 0.15 or more, or a fiber having a Canadian Standard Freeness (CSF) of 550 ml or more. Further, it is preferable that a non-fiber material of 550 ml or more of Canadian Standard Freeness (CSF) is added to the slurry. Further, the used paper fiber obtained by the dry defibration treatment is preferably used for manufacturing a molded article within 2 hours after being dispersed in water.

[0006] The first cause of the success of the present invention is that when the slurry is prepared by defibrating waste paper in a dry process, the wetness of the fiber is suppressed more than that obtained by wet defibration, and the stiffness of the fiber is therefore reduced. Is higher than that obtained by wet defibration, the adhesion between fibers during suction and dehydration is suppressed, and the obtained molded product has a lower density than expected. In addition, the second cause is that, because the adhesion between fibers is suppressed and water drainage is improved, it is found that a molded article having a sufficient thickness and excellent cushioning property can be efficiently obtained.
The following advantages are found. 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.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As used paper used in the present invention, recycled paper such as used newspaper, corrugated cardboard, used magazine and the like discharged from homes, factories, business establishments and the like can be used as recyclable products known in the art or normally unrecyclable. Those that are discarded can be mentioned. Specifically, used newspapers, books, magazines, telephone directories, catalogs, high-quality paper, packaging boxes, cardboard boxes, pulp molds, paper cushioning materials, or papermaking, printing, bookbinding, boxmaking, cardboard manufacturing Such as factories
The paper cut, waste paper, etc., discharged from the business site are mentioned. These can be used alone or in combination of two or more.

[0008] Examples of the dry defibrating machine used for defibrating used paper include a hammer type, a pin mill type, and a disc refiner type.
Examples include a fiber riser manufactured by West Japan Technical Development Co., Ltd., an impact mill manufactured by Dalton, a free crusher manufactured by Nara Machinery Works, a hammer mill, a cage mill, and an MK hammer mill manufactured by Masuyuki Sangyo.

[0009] The defibration of the present invention is usually carried out in a state where the used paper contains only equilibrium moisture. However, in order to facilitate defibration or to suppress fiber damage at the time of defibration, a certain amount of water is contained. You may let it. Water used for this purpose is added in a range of 75% by weight or less based on the solid content of the fiber.

The waste paper fibers obtained by the dry defibration treatment as described above are mixed in advance with thermoplastic resin particles, thermoplastic resin fibers, latex, or the like (heat treatment if necessary) to a predetermined size. Granulated materials are also effective as raw materials.

The slurry of the present invention is usually prepared batchwise or continuously using an apparatus having a stirrer. Dry defibrated fibers tend to lose their stiffness as the wetting time becomes longer, lowering their density, cushioning and productivity, so they can be dispersed in water and molded within 2 hours. It is preferred to use. In particular, it is preferably within one hour. In addition, the continuous preparation method in which the slurry preparation is performed in conjunction with the molding step is preferable because the wet time is always kept almost constant and the quality of the low-density body is easily stabilized. Water is usually used as a dispersion medium used for forming a slurry, but a mixture of water and an alcohol may be used. When a mixed solution of water and alcohol is used, 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 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.

In the present invention, a low-density body can be obtained by using only the used paper fibers obtained by the above-mentioned dry defibration, but if improvement of the interlayer strength or low-density property is required, the slurry composition may be used. Means can be taken to add other materials to the vessel. As a material having a large effect of improving the interlayer strength, a fibrous material having a bond reinforcing factor of 0.15 or more can be given. As a material having a large effect of improving the low density property, a fiber material and a non-fiber material having a Canadian Standard Freeness (CSF) of 550 ml or more can be mentioned.

The fibrous material having a bond reinforcing factor of 0.15 or more is a natural polymer fiber, a synthetic polymer fiber, a semi-synthetic polymer fiber, or a material obtained by treating them, and has a bond reinforcing factor of 0.15. 15 or more.

Examples of natural polymer fibers include unbleached or bleached chemical pulp obtained by kraft pulping, sulfite pulping, alkali pulping, etc. of softwood or hardwood, or GP, RMP, TMP, CTMP or the like. Examples thereof include mechanical fibers, cellulosic fibers such as cotton pulp and linter pulp, protein fibers such as wool, silk, and collagen fibers, and complex sugar chain fibers such as chitin / chitosan fibers and alginic acid fibers. As the synthetic polymer fiber, 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 are included. Examples of the semi-synthetic polymer fiber include a fiber obtained by chemically modifying a natural product, such as an acetylcellulose fiber. Incidentally, a recycled product can be used as the fibrous material.

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.

Among 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.
Above all, from the size of the effect of increasing the interlayer strength and the ease of manufacture, coniferous and hardwood are made into kraft pulp,
Unbleached or bleached chemical pulp obtained by sulfite pulping, alkali pulping, etc., GP, RMP, TM
Mechanical pulp such as P, CTMP, or cotton pulp,
A cellulosic fiber known as a papermaking raw material such as linter pulp or waste paper pulp is mixed with a medium stirring mill (JP-A-4-181).
No. 86), a vibration mill (Japanese Patent Application Laid-Open No. 6-10286), a high-pressure homogenizer, a colloid mill, a beating machine and the like obtained by wet mechanical treatment are particularly preferable. The size of the fine fibers is not particularly limited, but usually, those having a number average fiber length in the range of 0.01 to 0.80 mm and a fiber width in the range of 0.1 to 30 μm are preferably used.

[0017] 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 produce 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.

When fibers having a bond reinforcing factor of less than 0.15 are used in the present invention, the effect of improving the interlaminar strength is weak when a small amount is blended, and the interlaminar strength is increased when a large amount is blended, but the low density property is slightly inferior. Become.

The amount of the fibrous material having a bond reinforcing factor of 0.15 or more in the composition is not particularly limited, but is usually in the range of 1 to 40% by dry weight with respect to the composition.

The fibrous material having a large effect of improving the low density property and having a Canadian Standard Freeness (CSF) of 550 ml or more can be obtained by treating natural polymer fibers, synthetic polymer fibers, semi-synthetic polymer fibers, or those. And 550 ml or more of Canadian Standard Freeness (CSF).

Examples of natural polymer fibers include unbleached or bleached chemical pulp obtained by kraft pulping, sulfite pulping, alkali pulping, etc. of coniferous or hardwood, or GP, RMP, TMP, CTMP, etc. Mechanical pulp, cotton pulp, linter pulp, liquid ammonia-treated pulp, mercerized pulp, pulp that has been subjected to at least one of water-repellent, water-resistant, hardened, and curled treatments, and hemp fiber and bamboo fiber And cellulose-based fibers such as wool, silk and collagen fibers, and complex sugar chain fibers such as chitin / chitosan fibers and alginic acid fibers. Examples of the synthetic polymer fiber include an aromatic polyester fiber, an aliphatic polyester fiber, a polyethylene fiber, a polypropylene fiber, a polyethylene-polypropylene sheath core fiber, a polyacrylonitrile fiber, an acrylic fiber, and a polyamide fiber.
Examples of the semi-synthetic polymer fiber include a fiber obtained by chemically modifying a natural product, such as an acetylcellulose fiber. Incidentally, a recycled product can be used as the fibrous material.

Among them, 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. From the viewpoint of the effect of improving the low density property, curled fibers obtained by subjecting fibers to a deformation treatment are preferable, and examples thereof include HBA-FF, NHB405, and NHB416 (trade names, manufactured by Warehauser, USA).

[0023] Canadian Standard Freeness (CSF) 550m
The amount of the fibrous material of at least 1 in the composition is not particularly limited, but is usually in the range of 5 to 60% by dry weight with respect to the composition.

Canadian Standard Freeness (CSF) 550 m
l or more non-fibrous materials include, for example, natural organic materials such as cellulosic coarse powder, sawdust, chaff, soybean meal, etc. obtained by coarsely pulverizing cellulosic materials such as wood, bagasse, rice straw, and coconut shell fibers. Synthetic organic polymers such as coarse polymer powder, synthetic resin beads such as polyethylene and polystyrene, coarsely crushed foamed resin such as expanded polystyrene, crushed old tires, etc. 550ml of Canadian Standard Freeness (CSF)
Those showing the above are mentioned. Among them, coarsely ground natural organic polymer coarse powder and acetyl cellulose are preferable because they have biodegradability and are environmentally friendly. Above all, a cellulose-based coarse powder obtained by mechanically defibrating wood and used as a raw material for fiberboard is particularly excellent in the effect of improving the low-density property, and the raw material is 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, particularly 130 ° C or more, are better than those processed at a lower temperature. This is preferable because it tends to have high rigidity, and therefore tends to have excellent effects of improving low density and cushioning property. 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 curling the processed product with a kneader or the like is particularly preferable because the effect of improving the buffering property is more remarkable. The amount of the above components in the composition is not limited to this range, but is usually in the range of 10 to 60% by dry weight with respect to the composition.

Incidentally, the Canadian standard freeness is based on JIS.
It is a value indicating the drainage of pulp usually specified in -P-8121. In the present invention, the drainage of the non-fibrous material was determined based on the same measuring method.

The slurry composition may further contain an inorganic fiber, a metal fiber, a paper strength agent, a water-proofing agent, a water-repellent, a foaming microcapsule, if necessary, for improving the performance or imparting a function. 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.

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

Hereinafter, the production of a molded product in which the effect of the present invention is 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 pulp fiber is large, a large one is used, and when it 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.

The slurry is injected into the molding container by injecting the slurry into the molding container with the opening facing upward by a pump from the opening, and immersing the slurry in the slurry tank with the opening facing downward as in a normal pulp mold. By sucking more, the slurry is sucked into the molding container from the downward opening port, suction is performed while sinking the molding container into the slurry tank with the opening port facing upward, and the slurry is sucked into the molding container from the opening port. You can take the method. 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 molding 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 air flow rate of air drying is 2
Liter / cm ² min or more is preferable in terms of drying efficiency,
Particularly preferred is 5 liters / cm ² · min or more. 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 good drying method for a molded body having a portion having a thickness of 40 mm or more, specifically, a molded body having a thickness of 30 m
m or more, non-through holes are provided at intervals of 10 to 30 mm, and hot air at a temperature of 200 to 300 ° C. is
A method of injecting at a pressure of g / 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
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 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 into a split mold filled with water under pressure, the water in the split mold is gradually extruded to fill the split mold with fibers. 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.

[0038] A molded product is provided with a paper strength enhancer, a waterproofing agent, a water repellent, a dye, a pigment, a preservative, a fungicide, 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, evaporated paper, coated paper, synthetic paper, nonwoven fabric, cloth,
Synthetic film, metal foil, wood board, synthetic resin board, glass board,
Other materials, such as a metal plate, can also be used by being completely or partially pasted. Also, cardboard, paperboard, board, synthetic resin board,
It can also be used by sandwiching, affixing, fitting, and the like on a processed product such as a metal plate or a box. 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 insulating property, soundproofing property, moisture absorption, biodegradability and the like. 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. 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 obtained low-density sheet takes advantage of its features such as light weight, heat insulating properties, cushioning properties, air permeability, etc., and is unprocessed or subjected to post-processing such as surface coating or impregnation to produce high quality paper, fine coated paper. 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 a fiber having a higher surface smoothness or a fiber having a higher whiteness. 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 capable of 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.
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. 80-400 for hot air drying
Hot air in the temperature range of ° 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 drying is particularly effective when drying a board having a thickness of 10 mm or more, especially 40 mm or more. In order to increase the drying speed of the board, it is also effective to intentionally make unevenness on the surface of the board to increase the surface area, or to make a hole that penetrates or non-penetrates the board to make it easier for air to enter the interfiber space. is there. As a method of providing the board with irregularities or through holes or non-through holes, it is effective to use a device having an irregular wire.

The resulting low-density board is used as it is, or is unprocessed, or is bonded, surface coated, impregnated, cut, etc., by making use of 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.

[0044]

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.

<Examples> Waste paper fibers obtained by defibrating newspaper waste paper with a fiber riser (dry fiber defibrillator manufactured by Sumitomo Kogyo Co., Ltd., West Japan Technology Development Co., Ltd.) are dispersed in water so that the solid content concentration becomes 2%. A raw material slurry was prepared. After the above slurry is put into the tank, wet molding is performed by suctioning at -300 mHg for 30 seconds using a molding machine equipped with a disk-shaped female mold (suction only from the bottom) having an inner diameter of 200 mm and a depth of 30 mm. I got something. Suction was performed 30 minutes after slurry preparation. Subsequently, the molded product was dried by sending hot air at 150 ° C. pressurized to 1 kg / cm ² from the opening of the female mold. When physical properties of the obtained molded body were measured, the thickness was 23 mm and the density was 0.162 g / cm3.

<Comparative Example> A used newspaper was wet-laid using a pulper to adjust the solid content to 2% to obtain a raw material slurry. Molding was performed in the same manner as in Example 1 except that the above slurry was used. When the physical properties of the obtained molded body were measured, it was 4 mm in thickness and 0.263 g / cm ³ in density. Further, the suction dehydration time was extended to 1 minute, but only a product having a thickness of 6 mm and a density of 0.272 g / cm ³ was obtained.

[0047]

As described above, according to the present invention, waste paper fibers obtained by dry defibration are formed by using a slurry prepared by dispersing in water as a raw material. A low-density material can be obtained more efficiently than a material using the raw material obtained as a result.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a molding container used for producing a molded article of the present invention, in which a solid content of a slurry is deposited on the molding container.

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

FIG. 3 is a cross-sectional view illustrating a state where a wet deposit in FIG. 2 is dried.

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

[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: final molded product

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hisao Ishikawa 4-7-5 Ginza, Chuo-ku, Tokyo Oji Paper Co., Ltd. F term (reference) 3E075 BA92 GA07 4L055 AA11 BF07 EA08 EA15 FA13 FA16 FA22

Claims (2)

[Claims] 1. A waste paper fiber obtained by dry defibration treatment,
A low-density body obtained by dehydrating and drying a slurry prepared by dispersing in water, and having a density of 0.02 to 0.30 g / cm ³ . 2. The low-density body according to claim 1, wherein the thickness of the low-density body is 10 mm or more.