JPH10218245A - Pulp mold packaging material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a pulp mold packaging material having a soft surface and showing a superior shock-absorbing characteristics by a method wherein a specified rate of curled fiber of a specific wet curling factor is contained in all pulp substances. SOLUTION: A pulp mold having a desired surface softness is attained with a curled fiber having a wet curling factor in a range of 4 to 1.0 being applied. An amount of mixing the curled fiber is in a range of 25 to 100wt.% in all the pulp substances. Some fine fibers with a moisture holding factor of 170 to 500% may be contained with a rate of 3 to 300wt.% in respect to the curled fiber. Organic synthetic fibers, non-organic fibers, paper thickening agents, sizing agents and pigments other than the pulp fibers are mixed in compliance with the object. The mixing amount of these substances is normally added in a range of 0 to 50wt.% in all the solid substances. The curled fiber and each of the materials are added to adjust suspended liquid of molding raw material. It is preferable that a concentration of solid substances in the suspension liquid is in a range of 0.1 to 5wt.% in view of dispersing characteristics of materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulp mold packaging material having a soft surface and excellent cushioning performance.

[0002]

2. Description of the Related Art Foams of synthetic resins such as polystyrene and polyethylene are excellent in strength, impact buffering property and workability, and are used in large quantities as packaging materials by taking advantage of their features. However, on the other hand, this material is not biodegradable, and has a problem that it loses its aesthetic appearance for a long period of time and contaminates the environment for a long period of time in order to keep its shape when left in a natural environment. Further, when the waste is treated by landfill, the lack of biodegradability and the fact that the waste is bulky are also troubled, which causes the life of the landfill disposal site to be shortened. Also, because this material has a high calorie burn, when disposed in an incinerator,
There is a problem that the combustion temperature becomes high and the incinerator is damaged, shortening the life of the furnace.

On the other hand, a pulp mold packaging material obtained by disintegrating waste paper such as newspaper, flyer, magazine, cardboard, etc. with water and then carefully selecting and removing foreign matter as a raw material, and wet-suction-molding the pulp slurry of the pulp slurry. Can be reused as a raw material for pulp if disintegrated with water.Also, even if it is discarded, there is no problem like synthetic resin, and it is not found in synthetic resin foam such as excellent in moisture permeability and air permeability. Has features. Therefore, in recent years, pulp mold packaging materials have attracted attention as non-polluting packaging materials replacing synthetic resin materials, and it is expected that demand will increase further in the future.

However, conventional pulp mold packaging materials lack surface softness compared to the synthetic resin packaging materials described above.
There was a problem that the surface of the inclusion and the mold were rubbed during unpacking, and the surface was scratched, and could not be easily replaced depending on the application field. Further, the conventional pulp mold packaging material has a problem in buffering property as compared with the synthetic resin packaging material, and cannot be used when a high level of buffering property is required.

[0005]

SUMMARY OF THE INVENTION In view of such circumstances, the present inventors have made intensive studies to increase the versatility of pulp molds, and as a result, by using curled fiber as a pulp component of pulp mold packaging materials, The inventors have found that the cushioning property and surface flexibility are greatly improved, and have completed the present invention. An object of the present invention is to provide a pulp mold packaging material having a flexible surface and excellent cushioning properties.

[0006]

The pulp mold packaging material of the present invention is a pulp mold packaging material manufactured by a wet suction molding method using pulp as a raw material, wherein the wet curl factor is in the range of 0.4 to 1.0. The present invention is characterized in that a certain curled fiber is contained in an amount of 25 to 100% by weight in all pulp components. The pulp mold packaging material of the present invention further comprises fine fibers having a water retention of 170 to 500% in a range of 3 to 30 with respect to the curled fibers.
It is preferably contained at 0% by weight.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The curled fiber used in the present invention has an apparent length smaller than that of the original fiber, in which deformation such as curling or twisting is fixed by chemical bonding by a crosslinking reaction. The pulp fiber is usually obtained by adding a crosslinking agent such as epichlorohydrin to the pulp fiber, performing mechanical stirring, and then performing fluffing and heat treatment. As the curled fiber, for example, a C2 to C8 dialdehyde and a C2 to C8 monoaldehyde having an acid functional group are used to crosslink the inside of the cellulosic fiber to obtain an average water retention of 28.
% To 50% cross-linked fiber (Japanese Patent Publication No. 5-71702) and a cross-linked fiber having a water retention of 25% to 60% obtained by cross-linking a cellulosic fiber using a C2 to C9 polycarboxylic acid (Japanese Unexamined Patent Publication No. -206174, JP-A-3-20
No. 6175, JP-A-3-206176) and commercially available products (for example, trade names: HBA-FF, NHB405, NHB4, manufactured by Warehauser, USA)
16 etc.).

In the present invention, the wet curl factor is 0.4
A curled fiber in a range of from 1.0 to 1.0 is appropriately selected and used, and a pulp mold having desired surface flexibility can be easily obtained. When a material having a wet curl factor of less than 0.4 is used, the surface softness becomes insufficient. On the other hand, if it exceeds 1.0, it is necessary to strengthen the mechanical treatment when imparting deformation to the pulp fiber in order to obtain it, and as a result, the pulp fiber is damaged and the fiber strength is reduced. Because
The resulting pulp mold generates more paper powder.

Incidentally, the wet curl factor is an index indicating the degree of change of the fiber in a wet state, and the actual length (LA) of the fiber after immersing the curled fiber in pure water at room temperature for 24 hours. And the maximum projected length of the fiber (the length of the longest side of the rectangle surrounding the fiber, LB) is measured using a microscope,
This is a value calculated by [(LA / LB) -1], which is a numerical value indicating how much the fiber is curved from the original length of the linear fiber.

In the present invention, the amount of the curled fiber is in the range of 25 to 100% by weight, preferably 40 to 100% by weight, based on the total pulp component. If the amount is less than 25% by weight, the desired effect cannot be obtained in terms of surface softness. As long as the effects of the present invention are not impaired, generally known pulp is used in combination for improving interlayer strength and the like, if necessary. For example, used paper such as newsprint, flyers, medium-quality paper, and high-quality paper is wet-pulverized and wet-disintegrated, selected waste paper pulp, and deinked waste paper pulp obtained by deinking and bleaching, and coniferous and hardwood kraft pulping. Pulp fibers such as unbleached or bleached chemical pulp, cotton pulp, linter pulp, etc., obtained by the treatment of pulp, sulfite pulping or alkali pulping. These may be used alone or in combination of two or more kinds as appropriate.

Further, fine fiber pulp obtained by mechanically treating the above pulp fibers in a wet manner with a medium stirring mill, a vibration mill or the like (JP-A-4-18186, JP-A-6-18186)
-10286), a refiner, a beater, a beating machine such as a PFI mill or the like which is generally used in the pulping step, or a mechanical treatment using the above-mentioned mill or the like, and an acid, an alkali,
Fine fibers obtained by combination with a chemical treatment with cellulase, xylase or the like, and fine fibers such as bacterial cellulose can be added. Above all, fine fiber pulp (JP-A-4-18186, JP-A-6-10286) obtained by mechanically treating pulp fibers in a wet medium such as a medium stirring mill and a vibration mill has a strong entanglement property. Since the carded fibers can be strongly bonded to each other, the effect of improving the interlayer strength is large even if added in a small amount, and is preferably used. The amount of the fine fibers varies depending on the use of the packaging material, and is not particularly limited.
A range of 0% by weight is preferable, and a range of 3 to 100% by weight is more preferable.

Regarding the water retention of fine fiber pulp, 17
A range of 0 to 500% is preferable, and a range of 210 to 450% is more preferable. When the water retention is less than 170%, the entanglement property is weakened, and the force for bonding the curled fibers is also weakened. On the other hand, the water retention of the fine fibers is 500
%, The production cost tends to increase.
Incidentally, the degree of water retention was determined by JAPAN TAPPI No. 2
6-78, which is a value (%) in which the amount of water retained after dewatering a wet fiber with a centrifugal force of 3000 G for 15 minutes is expressed as an amount per gram of absolute fiber dryness (%). Is defined as

In the present invention, in addition to the above-mentioned pulp fibers, organic synthetic fibers, inorganic fibers, paper strength enhancers, expandable microcapsules, sizing agents, softeners, dyes, pigments, retention aids, etc. , Fillers, PH regulators, slime control agents, thickeners, preservatives, fungicides, flame retardants, antibacterial agents, rodenticides, insect repellents, moisturizers, freshness preservatives, deoxidizers,
Microcapsules, foaming agents, surfactants, electromagnetic shielding materials, antistatic agents, rust inhibitors, fragrances, deodorants, softeners, and the like can be appropriately selected and blended. These may be used in combination of two or more. The amount of these components varies depending on the use of the packaging material and is not particularly limited, but is usually added in the range of 0 to 50% by weight based on the total solid content.

Examples of the organic synthetic fibers include core / sheath made of two materials such as polyethylene fiber, polypropylene fiber, polyacrylonitrile fiber, acrylic fiber, rayon fiber, polyester fiber, polyamide fiber, acetylcellulose fiber, polyethylene and polypropylene. Structural fibers and the like can be mentioned, and these additions are generally effective in improving the strength in a wet state of water. Among them, aliphatic polyesters, biodegradable fibers such as acetyl cellulose,
It is particularly preferable because the obtained pulp mold can be easily discarded. Further, as the shape of the fiber, a fiber having a bend such as a curl is preferable to a linear fiber because it is superior in the effect of improving the buffering property.

As the inorganic fiber, for example, glass fiber,
Carbon fiber, activated carbon fiber, alumina fiber, silicon carbide fiber,
Examples thereof include silica / alumina silicate fibers and rock wool fibers. This addition is generally effective in improving heat resistance and imparting various functions such as deodorization, deodorization, and conductivity.

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, polyethylene A wet paper strength enhancer such as an imine resin may be mentioned, but the addition of these additives is generally effective in improving the strength. In particular, the use of a wet paper strength enhancer is effective in improving the strength in a wet state of water.

As the water-proofing agent, the above-mentioned wet paper strength enhancer can be used as a water-proofing agent, and examples thereof include formaldehyde, glyoxal, dialdehyde starch, and ammonium zirconium carbonate. Examples of the water repellent include various waxes (natural wax, petroleum wax, chlorinated paraffin), higher fatty acid derivatives, synthetic resins, chromium complexes, silicone resins, and the like. Addition of a water-proofing agent and a water-repellent agent is effective in improving water resistance. The foamable microcapsules are foamed at the temperature at the time of drying, and are effective in reducing the weight of the mold.

In the present invention, a raw material suspension for molding is prepared by appropriately adding the above-mentioned materials together with the curled fiber. In terms of dispersibility of the materials, the suspension has a solid content of 0.1%. A range of from 5 to 5% by weight is preferred. Above all, it is preferable to use the one having a concentration in the range of 0.1 to 1% by weight, because a better surface smoothness can be obtained.

In order to obtain a material having more flexibility and excellent buffering properties, it is desirable that the curled fiber is not left in a wet state for a long time, but is disintegrated as soon as possible before production. The reason is that although the curled fiber is more hydrophobic than ordinary pulp, if it is immersed in water for a long time, the fiber becomes soft including water, and the voids between the fibers of the resulting pulp mold are reduced. This is because the flexibility is reduced. Therefore, when the production is performed over a long period of time, the slurry is preferably prepared by a continuous method capable of preparing the slurry in accordance with the production of the pulp mold, rather than the vat method.

In the wet suction molding method, a metal net-coated mold having a vacuum water-permeable structure is immersed in a pulp suspension and sucked, water is discharged and, at the same time, pulp fibers are adsorbed on the surface of the mold.
The molding die is pulled up from the pulp suspension, suction dehydration, pressure dehydration and the like are performed to obtain a molded product in a wet paper state, and then this is naturally or forcibly dried. Any method can be used as long as it is a wet suction molding method, and the method is not particularly limited.

As a molding method in the present invention, a method in which pulp suspensions having different compositions are successively adsorbed on the mold surface to obtain a pulp mold having a multilayer structure is also possible, and the hardness and strength of the inner and outer surfaces differ. A pulp mold is obtained. For example, (1) First, after a curled fiber-containing suspension is sucked into a mold, a pulp suspension containing no curled fiber is sucked from above, and pulp layers having different compositions are sequentially deposited to obtain a pulp layer. (This makes it possible to obtain a mold having a soft inner surface in contact with inclusions and a harder outer surface, and (2) a curled fiber-free suspension. After sucking into the mold,
A laminated mold obtained by suctioning a pulp suspension containing curled fiber from above and sequentially depositing pulp layers of different compositions (this makes it possible to obtain a type having a hard inner surface and a soft outer surface) ), (3) First, the high-curled fiber suspension is sucked into a mold, and then the low-curled-fiber suspension is sucked from above, and pulp layers having different compositions are sequentially deposited. The resulting laminated mold (this allows a type having an inner surface that is softer than the outer surface). (4) First, a suspension containing a low content of curled fiber is suctioned into a mold, and then the suspension is drawn from above. A laminated mold obtained by suctioning a high blend of carded fiber and successively depositing pulp layers of different compositions (this provides a type in which the outer surface is softer than the inner surface) It is possible.), And the like. In addition, this method can also be used to obtain one having three or more layers of different compositions. In addition to the pulp component, the above-mentioned materials can of course be added to the suspension for producing the multilayer mold.

In general, any known method can be used for drying a wet-paper molded article having a water content of about 70 to 80%, and is not particularly limited. A far-infrared ray drying method, a hot air drying method, or a combination of these methods is used. Among them, a method of drying with far infrared rays until the moisture content of the pulp mold reaches about 50% (Japanese Patent Application No. 5-57867).
Is preferred. The far infrared rays penetrate into the pulp mold and heat it, so that the pulp mold can be dried quickly. In addition, since the temperature difference between the surface and the inside of the pulp mold is small and drying occurs uniformly, deformation such as warpage and distortion of the pulp mold during drying is small. In addition, since it is uniformly dried, a product having a small difference in shade of color can be obtained when coloring is performed using a dye, a pigment, or the like. After drying to a water content of about 50% by far infrared rays, it is usually dried to a water content of about 10% using a high-temperature gas stream or the like.

The shape and surface of the pulp mold can be adjusted by pressing the wet pulp mold in a wet state or in a dry state, if necessary. At that time, press the mold at room temperature or 1
It is performed at a high temperature of around 00 ° C.

On the surface of the pulp mold obtained as described above, if necessary, an antistatic agent, a volatile rust preventive, a paper strength enhancer, a water resistant agent, a dye, a pigment, a preservative, A fungicide, a flame retardant, an antibacterial agent, a rodenticide, an insect repellent, a humectant, a freshness-retaining agent, a deoxidizer, a surfactant, an aromatic agent, a deodorant, a water repellent, an oil repellent, etc. The solution can be applied using a spray device or a brush.

Further, by attaching a synthetic resin film, paper, nonwoven fabric, or cloth to the surface of the pulp mold obtained as described above, and planting natural or synthetic fibers on the surface, water resistance and gas resistance are improved. Processing such as improvement of barrier properties, surface strength, etc., and giving a sense of quality can be performed. Alternatively, the fine fiber pulp suspension can be sprayed on the surface of the pulp mold to improve the surface strength. Above all, biodegradable materials are preferable as the material of the synthetic resin film, synthetic fiber, natural fiber, nonwoven fabric, cloth, paper and the like when performing the surface treatment.

The use of the pulp mold obtained by the present invention is not limited to the field of packaging, and the properties of the product of the present invention, such as heat insulation, soundproofing, moisture absorption, transmission, etc., are utilized to make use of heat insulating materials, building materials, soundproofing materials, and the like. It can also be used in fields such as filters. The product of the present invention is not limited by the shape, and naturally includes a sheet or a board.

[0027]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted thereto. In Examples and Comparative Examples, “parts” and “%” indicate “parts by weight of solid content” and “% by weight” unless otherwise specified.

EXAMPLE 1 To 50 g of bleached softwood bleached kraft pulp was added 2 g of epichlorohydrin (manufactured by Wako Pure Chemical Industries, Ltd.) in isopropanol 20.
The solution was added to 20 ml of a 5% strength sodium hydroxide solution and water to make the total amount 250 g, and then mixed well. This mixture was placed in a double-arm kneader having a capacity of 1 liter (model: S1-1, manufactured by Moriyama Seisakusho), and the double arm was rotated at room temperature at 60 rpm and 100 rpm, respectively, and subjected to a stirring treatment for 30 minutes. Subsequently, the mixture was placed in a heat-resistant plastic bag and sealed at 80 ° C. for 2 hours.
Heat treatment was carried out for a time to cause a crosslinking reaction. Next, the alkali remaining in the pulp is thoroughly washed and removed with water, and then concentrated to a solid content of 20% with a Buchner funnel.
C. for 2 hours in a hot air drier for drying. After being taken out of the dryer and cooled, the pulp mass was deflocculated and fluffed using a laboratory Warburg blender. The wet curl factor of the curled fiber thus obtained was 0.80. Separately, an uninked and bleached wastepaper pulp (whiteness: 50.4%, freeness: 282 ml CSF) composed of 55% waste newspaper and 45% flyer (high quality, coated paper) waste paper was prepared.

Water was added to a mixture of 90 parts of the curled fiber obtained as described above and 10 parts of waste paper pulp, and the mixture was adjusted to a solid content concentration of 1.0% and then sufficiently stirred. It was dispersed to obtain a pulp slurry. continue,
While the pulp slurry is being stirred, a flat-bottom tray molding die having an outer width of 180 mm x a total length of 150 mm x a depth of 40 mm is immersed in the slurry by a small pulp mold molding machine (model: SDM type, manufactured by Noritake Company), and vacuum suction is performed. Then, the pulp was stacked and adsorbed on the molding die, and then the die was pulled up from the slurry and inverted 180 degrees. After that, while continuing to suck the pulp mold that has been stacked and adsorbed upward, the mold that has been vacuum-sucked is then placed on the pulp mold from above, and at the same time, the vacuum pressure of the molding die is set to zero, and the positive pressure is set. Thereby, the pulp mold was transferred to the mold. Next, the pulp mold was removed from the mold, and drying was performed with a far-infrared heater and hot air to obtain a flat bottom tray having a water content of 9% and a thickness of 7 mm. The softness of the surface of the pulp mold was evaluated, as shown in Table 1. The method for measuring the wet curl factor and the method for evaluating the softness of the pulp mold surface are described below.

Evaluation method [Measurement method of wet curl factor]
After 100 hours of immersion, the curled fibers are placed on a microscope slide glass, and the actual (linear) length LA (μ) of each fiber is measured using an image analyzer.
m) and the maximum projected length (equal to the length of the longest side of the rectangle surrounding the fiber) LB (μm) were measured, the wet curl factor was determined from the following equation, and the average value was used. Wet curl factor = (LA / LB) -1

[Evaluation of softness of pulp mold surface]
The surface of the pulp mold was touched with a palm and evaluated according to the following criteria. 1 ... The surface is hard and rough. 2 ... The surface is slightly soft, but there is a rough feeling. 3: The surface is soft. 4 ... The surface is excellent in softness. 5 ... The surface softness is extremely excellent. Also, in order to evaluate the buffer performance of the material, using the same slurry as that used to make the pulp mold, a die-shaped molded body was made by the following method,
A compression test was performed to evaluate the cushioning property.

[Evaluation Method of Buffering Property] A raw material slurry having a solid content of 1% was concentrated to a solid content of about 5% with a Buchner funnel having a diameter of 120 mm. Is 2cm x 2cm
Fill into a cubic-shaped container with a size of × 2 cm open in one direction while pushing it loosely and evenly by hand.
It was placed in a hot air circulating dryer at 5 ° C. and dried until the weight became constant. Thereafter, after the molded body was taken out from the wire, the molded body was conditioned at 20 ° C. and 65% RH until the weight became constant. Further, this dice-shaped test piece is subjected to a straw graph tensile tester (model: M2, manufactured by Toyo Seiki Seisakusho).
, Using a load cell of 100 kg
It was compressed at a compression rate of 0 mm / min until the strain was 75% (15 mm) and then released. The test piece was allowed to stand in a constant temperature and constant humidity environment of 20 ° C. and 65% RH for 24 hours, and the height (mm) of the test piece was measured, and the permanent strain (%) was obtained according to the following equation. Permanent strain (%) = {strain (mm) / original height (mm)}
× 100 The results are shown in Table 1.

Example 2 Curled fiber 75 obtained in the same manner as in Example 1
And 25 parts of waste paper pulp as in Example 1, water was added to adjust the solid content concentration to 1.0%, and then sufficiently stirred and dispersed to obtain a pulp slurry.
Except that this slurry was used, a flat-bottomed tray having a thickness of 7 mm and a water content of 9 mm in outer width of 180 mm × length of 150 mm × depth of 40 mm was produced in the same manner as in Example 1, and the softness of the surface was evaluated. Further, a compression test was performed in the same manner as in Example 1. Table 1 shows the results.

Example 3 Curled fiber 50 obtained in the same manner as in Example 1
And 50 parts of waste paper pulp as in Example 1, water was added thereto, and the mixture was adjusted to a solid content concentration of 1.0%, and then sufficiently stirred and dispersed to obtain a pulp slurry.
Except that this slurry was used, a flat-bottomed tray having a thickness of 7 mm and a water content of 9 mm in outer width of 180 mm × length of 150 mm × depth of 40 mm was produced in the same manner as in Example 1, and the softness of the surface was evaluated. Further, a compression test was performed in the same manner as in Example 1. Table 1 shows the results.

Example 4 Curled fiber 30 obtained in the same manner as in Example 1
And 70 parts of waste paper pulp as in Example 1, water was added to adjust the solid content concentration to 1.0%, and then sufficiently stirred and dispersed to obtain a pulp slurry.
Except that this slurry was used, a flat-bottomed tray having a thickness of 7 mm and a water content of 9 mm in outer width of 180 mm × length of 150 mm × depth of 40 mm was produced in the same manner as in Example 1, and the softness of the surface was evaluated. Further, a compression test was performed in the same manner as in Example 1. Table 1 shows the results.

Example 5 Instead of using waste paper pulp, the freeness was 713 m.
A slurry was prepared in exactly the same manner as in Example 2 except that 25 parts of un-beaten softwood bleached kraft pulp of 1CSF was used, a flat bottom tray was prepared, and the softness of the surface was evaluated. Further, a compression test was performed in the same manner as in Example 1. Table 1 shows the results.

Example 6 Instead of using waste paper pulp, 450 ml freeness
A slurry was prepared in exactly the same manner as in Example 2 except that 25 parts of bleached hardwood bleached kraft pulp beaten with a laboratory Niagara beater (23 liter capacity) up to the CSF was used to prepare a flat bottom tray, and the surface was softened. Was evaluated. Further, a compression test was performed in the same manner as in Example 1. Table 1 shows the results.

Example 7 A 1.5-liter dynomill apparatus (model: KDL-P) filled with 80% of glass beads having an average particle diameter of 2 mm was filled with an aqueous slurry of bleached hardwood kraft pulp having a solid content of 1%.
ILOT type, manufactured by Shinmaru Enterprises)
Introduced and passed at 50 ml / min, water retention 28
0% of fine fiber pulp was obtained. 5 parts of the fine fiber pulp,
Water was added to a mixture of 95 parts of the curled fiber obtained in the same manner as in Example 1, and the solid content was adjusted to 1.0.
%, And then sufficiently stirred and dispersed to obtain a pulp slurry. Example 1 except that this slurry was used
In exactly the same way, the outer width 180mm × total length 150mm ×
A flat bottom tray having a depth of 40 mm and a water content of 9% and a thickness of 7 mm was prepared, and the softness of the surface was evaluated. Further, a compression test was performed in the same manner as in Example 1. Table 1 shows the results.

The water retention was measured by JAPAN TAPPI N
o. It measured as follows according to 26-78. The solid content concentration of the fine fiber is adjusted to 6 to 9%, and the stock is collected so as to have an absolute dry weight of 0.7 g, placed in a centrifuge tube having a G3 glass filter, and centrifuged. (Model: H-103N, manufactured by Domestic Centrifuge Co., Ltd.) and centrifugally dehydrated at 3000 G for 15 minutes. The sample subjected to the centrifugal dehydration treatment was taken out of the centrifuge tube, and its weight (wet weight) was measured. Thereafter, the sample was dried at 105 ° C. until the weight became constant, and the weight (dry weight) was measured. The water retention was calculated by the following equation. Water retention (%) = {(WD) / D} × 100 where W is the wet weight (g) of the sample and D is the dry weight (g)
It is.

Example 8 The procedure was carried out except that 90 parts of a commercially available curled fiber (trade name: HBAFF, manufactured by Wehrhauser, USA, wet curl factor 0.65) was used instead of the curled fiber of Example 1. A slurry was prepared exactly in the same manner as in Example 1, a flat bottom tray was prepared, and the softness of the surface was evaluated. Further, a compression test was performed in the same manner as in Example 1. Table 1 shows the results.

Example 9 A solution prepared by dissolving 1.0 g of epichlorohydrin (manufactured by Wako Pure Chemical Industries, Ltd.) in 20 ml of isopropanol and 50 ml of a 5% strength sodium hydroxide solution were added to 50 g of absolutely dried softwood bleached kraft pulp. After making the total amount 250 g, the mixture was mixed well. This mixture was placed in a double-arm kneader having a capacity of 1 liter (model: S1-1, manufactured by Moriyama Seisakusho), and the double arms were rotated at room temperature at 60 rpm and 100 rpm, respectively, and subjected to a stirring treatment for 10 minutes. Subsequently, this mixture was heat-treated at 80 ° C. for 30 minutes while being sealed in a heat-resistant plastic bag to cause a crosslinking reaction. Next, the alkali remaining in the pulp is thoroughly washed with water and removed, and then concentrated to a solid content of 20% using a Buchner funnel.
It was put in a hot air dryer at 50 ° C. for 2 hours and dried. After being taken out of the dryer and cooled, the pulp mass was deflocculated and fluffed with a laboratory Warburg blender. The curled fiber thus obtained had a wet curl factor of 0.42. A slurry was prepared in exactly the same manner as in Example 3 except that 50 parts of the curled fiber having a wet curl factor of 0.42 was used instead of the curled fiber of Example 1, and a flat bottom tray was prepared. The softness of the surface was evaluated. Also,
A compression test was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 Water was added to 100 parts of waste paper pulp (wet curl factor: 0.18) similar to that in Example 1, and the solid content was adjusted to 1.0.
%, And then sufficiently stirred and dispersed to obtain a pulp slurry. Example 1 except that this slurry was used
A flat-bottomed tray was prepared in exactly the same manner as described above, and the softness of the surface was evaluated. Further, a compression test was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 Unbeaten softwood bleached kraft pulp (freeness 713 ml)
Water was added to 100 parts of CSF, wet curl factor 0.31) to adjust the solid content concentration to 1.0%, and then sufficiently stirred and dispersed to obtain a pulp slurry. Except that this slurry was used, a flat-bottomed tray was produced in the same manner as in Example 1, and the softness of the surface was evaluated. Further, a compression test was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 Freeness of 450 ml C using an experimental Niagara beater
Water was added to 100 parts of hardwood bleached kraft pulp (wet curl factor 0.24) beaten to SF to adjust the solid concentration to 1.0%, and then sufficiently stirred and dispersed to obtain a pulp slurry. . Except that this slurry was used, a flat-bottomed tray was produced in the same manner as in Example 1, and the softness of the surface was evaluated. Further, a compression test was performed in the same manner as in Example 1. Table 1 shows the results.

As can be seen from Table 1, the pulp molds using curled fibers as the pulp component (Examples 1 to 9) were all 3 or more as evaluated by the feel of the palm. Permanent distortion due to 3
It was 5% or less, which proved to be excellent in flexibility and cushioning. Also, by changing the content of the curled fiber and the waste paper pulp, pulp molds having various touches and cushioning properties can be manufactured (Example 1).
4). Pulp other than waste paper pulp such as NBKP (Example 5), LBKP (Example 6), and fine fibers (Example 7) can also be blended. Further, a commercially available curled fiber can be used (Example 8).

On the other hand, a pulp mold (Comparative Example 1) made of only used paper pulp, NBKP (Comparative Example 2), LBK
The pulp mold produced only with P (Comparative Example 3) had a surface texture evaluation of 2 or less, and a permanent set due to compression of 40% or more, and had a harder surface and less cushioning than those of Examples. Becomes

[0047]

[Table 1]

[0048]

The present invention has the effect of providing a pulp mold packaging material having excellent surface flexibility and cushioning properties.

Claims (2)

[Claims] In a pulp mold packaging material produced by a wet suction molding method using pulp as a raw material, a curled fiber having a wet curl factor in a range of 0.4 to 1.0 is contained in a total pulp component of 25 to 100%. A pulp mold packaging material containing 100% by weight. 2. The method according to claim 1, wherein fine fibers having a water retention of 170 to 500% are added to the curled fibers in an amount of 3 to 3%.
The pulp mold packaging material according to claim 1, which contains 00% by weight.