JP2002200726A - Molding processed base paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide molding processed base paper having a low environmental load at a discarding time in the base paper used for a food packaging container, an industrial product packaging container or the like. SOLUTION: The molding processed base paper comprises multilayer paper obtained by laminating a paper sheet having an elongation at breakage (JIS P 8113) of 5% or more as an outer layer laminated on at least one surface of a paper support. A basis weight of the overall multilayer paper is in a range of 100 to 500 g/m2 and a density of a range of 0.4 to 0.7 g/cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded base paper used for food packaging containers, industrial product packaging containers, etc., and more particularly, to a molding material having a low environmental load at the time of disposal and excellent moldability and productivity. It is related to processed base paper.

[0002]

2. Description of the Related Art Conventionally, plastic containers have been used as food packaging containers such as lunch boxes and food trays, and industrial product packaging containers such as CD cases and electric component cases. These plastic containers include those obtained by press-molding expanded polystyrene sheets, those obtained by molding foamed polystyrene beads, and those obtained by pressing polypropylene and polyvinyl chloride sheets. Can be produced,
It has been used in large quantities so far because it can be manufactured at low cost. However, the plastic container is
When landfilling, it is not decomposed semi-permanently and remains in the ground, and when incinerated, burning calories are high and it is easy to damage the incinerator, and it is difficult to completely burn,
In particular, those using polyvinyl chloride have a problem that hydrogen chloride gas which is highly corrosive is easily generated during incineration.

[0003] On the other hand, natural pulp can be cited as a raw material that has a low calorie burning during incineration and does not generate corrosive gas during incineration. A pulp mold method is conventionally known as a method for producing a molded body using such pulp as a raw material.The pulp mold method is known in which pulp is used as a raw material and then dispersed in water. After the paper is removed, the pulp component is suction-dehydrated to form a wet molded product having a predetermined shape, and then dried by heat to produce a molded product. The pulp mold method has good moldability because the pulp component is formed into a predetermined shape, but has a problem in that drying of the wet molded product requires energy and time, resulting in low productivity.

In addition to the above-mentioned pulp mold method, as a method of obtaining a molded body from natural pulp as a raw material, a method of press-molding a paperboard under heating is known. This press molding method has a very high productivity because a molded product can be obtained by one press. However, when ordinary paperboard is used, the stretchability is low and a crack is easily generated at the time of pressing. Only compacts, such as, for example, shallow dishes, could be produced. For this reason, it was not possible to produce a molded body having a drawing depth (deep drawing), and the shape of the obtained molded body was very limited.

As a method for solving such a problem, Japanese Unexamined Patent Publication No. Hei 5-28623 discloses a method in which a corrugated paper provided with a large number of corrugated bent portions in a paper material and given stretchability is heated and pressed in a mold. Japanese Patent Application Laid-Open No. Hei 6-134898 discloses a method of press-forming while heating after humidifying a paper material provided with stretchability by forming irregularities over the entire surface.
No. 14,705 discloses a method in which a plurality of humidified base papers are superposed via an adhesive, then corrugated to impart stretchability, and then press-formed. Also, in JP-A-7-315358, a corrugated cardboard sheet (micro flute) having a step height of 2 mm or less is used.
Press molding while heating in a metal mold is disclosed, but in this method, the sheet is made bulky to improve the formability. Japanese Patent Application Laid-Open No. Hei 6-239334 discloses a method of press-molding a sheet obtained by adding an olefin resin such as polyethylene or polypropylene to pulp fiber and imparting stretchability. There is disclosed a method of press-forming a sheet improved in stretchability by mixing a thermoplastic resin fiber such as a polypropylene fiber and a pulp fiber with heating in a metal mold. However, when the molded body has a curved surface portion having a large distortion, it is necessary to form a fold wrinkle in the curved surface portion during press molding to absorb the distortion of the curved surface portion. The unevenness of the wrinkled portion was large and the moldability was not good.

The inventors of the present invention have filed a multi-layer structure base paper (Japanese Patent Application No. 2001-163109) having a low-density layer and a high-density layer as a method for solving such a problem. Although it is enough to form a material with a shallow drawing depth, when the drawing speed of a cup or other material with a large drawing depth is increased, the forming speed, that is, the pressing speed, is increased. It was easy to occur and was insufficient.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to press-mold a compact having a large drawing depth such as a cup.
An object of the present invention is to provide a molded base paper having good moldability in which cracks, tears, and irregularities in creases do not occur, and high productivity.

[0008]

The present invention has the following arrangement to solve the above-mentioned problems. That is, the first of the present invention
Is the elongation at break on at least one side of the paper support (JIS-P
8113) is a multilayer paper obtained by laminating a paper sheet having 5% or more as an outer layer.
The molded base paper has a density of 500 g / m ² and a density of 0.4 to 0.7 g / cm ³ .

A second aspect of the present invention is a multilayer paper having at least a low-density layer and a higher-density outer layer, and has a rice tsubo of 100 to 500 g / m ² and a density of 0.4 to 0.4 g / m ² .
0.7 g / cm ³ and the elongation at break of the outer layer (JIS-P
8113) is 5% or more.

A third aspect of the present invention is the first and second base papers of the present invention, wherein the paper support or the low-density layer is mainly composed of mechanical pulp.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Outer layer paper sheet] Generally, a molded article having a large drawing depth, such as a cup, is stretched more at the time of molding than a sheet having a small drawing depth. The paper layer on the side to be stretched is stretched more than the inside at the time of drawing, so that it is easily cut. In order to prevent breakage, the elongation at break of the paper sheet used for the outer layer in the present invention is 5
%, More preferably 7% or more. Examples of natural pulp fibers constituting the paper sheet for the outer layer include wood fibers (chemical pulp and mechanical pulp) and non-wood fibers. Among wood fibers, chemical pulp
Kraft pulp using caustic soda and sodium sulfide at the time of wood chip digestion, sulfite pulp using sulfurous acid and bisulfite, and the like may be used. These pulp may be unbleached or bleached. As mechanical pulp, ground wood pulp (GP) obtained by grinding logs with a grinder, refiner ground wood pulp (RGP) obtained by grinding (refining) waste wood from a sawmill, and wood chips are used. Thermomechanical pulp (TMP) obtained by heating and refining treatment is exemplified. In addition to the above, C-TMP, which is obtained by chemically treating wood chips and then refining under pressure, and BC-T which has been subjected to bleaching
There are also MPs and the like. Among such wood fiber pulp, pulp having a long fiber length obtained from conifers such as pine, larch, cedar, fir, cypress and the like is suitably used for improving the stretchability and strength of a paper sheet. Further, pulp having a short fiber length obtained from hardwood such as hippo, beech, maple, elm, chestnut and the like can be used in combination as long as the effects of the present invention are not impaired. Examples of non-wood fibers that can be used in the outer layer paper sheet of the present invention include bast fibers such as mulberry, mitsumata, ganpi, flax, timer, kenaf, choma, jute, sun hemp, and seed hair fibers such as cotton and cotton linter. And leaf fibers such as manila hemp, sisal hemp, and esparto; and stem fibers such as bamboo, rice straw, wheat straw, and sugarcane bagasse. In particular, mulberry, mitsumata, kenaf, manila hemp, sisal hemp, cotton, cotton linter, and the like have a long fiber length and can improve the stretchability and strength of a paper sheet and are preferably used. Such non-wood fibers are used after being digested and pulped by a conventional method. Examples of the cooking method include a soda cooking method using caustic soda, a kraft cooking method using caustic soda and sodium sulfide, and a sodium sulfite cooking method using caustic soda and sodium sulfite. The non-wood fiber pulp obtained by the cooking method may be unbleached or bleached. Non-wood fibers can be pulped by grinding (refining) under pressure and heat using a refiner, similarly to wood fibers. These pulp fibers can be used alone or in combination of two or more. Also, used paper pulp such as used cardboard paper, used magazine paper and the like can be mixed within a range that does not impair the effects of the present invention.

[0012] Examples of papermaking chemicals include sizing agents, paper strength agents, and retention aids used in ordinary papermaking. As the sizing agent, there are internal sizing agents such as alkyl ketene dimer, styrene acrylic resin, and rosin. Examples of paper strength agents and retention aids include polyacrylamide resins, polyamide epichlorohydrin resins, polyethyleneimines and derivatives thereof, polyethylene oxides, polyamines, polyamides, polyamide polyamines and derivatives thereof, cationic and amphoteric starches, oxidized starches, carboxymethylated starches , Plant gums, organic compounds such as polyvinyl alcohol, and inorganic compounds such as sulfate band, alumina sol, colloidal silica, bentonite and the like are used in appropriate combination. Examples of fillers include mineral fillers such as talc, kaolin, calcined kaolin, clay, diatomaceous earth, heavy calcium carbonate, magnesium carbonate, aluminum hydroxide, titanium dioxide, magnesium sulfate, silica, aluminosilicate, bentonite, and polystyrene particles. Organic synthetic fillers such as urea formalin resin particles and the like can be appropriately selected and used in combination. Further, papermaking additive aids such as dyes, pH adjusters, slime control agents, defoamers, and tackifiers can be used as appropriate depending on the application.

An outer layer paper sheet having a high breaking elongation can be made by the following paper making process using a slurry of the raw materials and chemicals made of the above materials. That is, in a wet paper machine, a device for pressing and rotating an endless thick rubber belt is attached to a part of a dryer roll via a nip roll, and a wet paper is passed between the dryer and the belt, and a belt that has been stretched in advance is used. And a creping method in which the paper is peeled from a press roll of a paper machine or a processing machine or a cylinder drier or a Yankee drier by a doctor to give crease-like wrinkles. Regarding the creping method, there are various devices and methods at the doctor device and the position where creping is performed, for example, creping is performed by a doctor at a press part of a paper machine called a duostress method, and further through a grooved roll in the middle part of the dryer. There is a method of giving elongation in the vertical and horizontal directions of the paper. Further, in the present invention, the outer layer paper sheet obtained from the above-mentioned paper making step may be not only a single layer but also a laminated paper having two or more layers. The range of the basis weight of the outer layer paper sheet is 40 to 30
The range is preferably 0 g / m ² , more preferably 50 to 1 g / m ^2.
It is in the range of 50 g / m ² . The outer layer paper sheet has a basis weight of 4
If it is lower than 0 g / m ^2, the tensile strength of the sheet is insufficient and the sheet is easily broken at the time of molding. If it exceeds 300 g / m ² , the density of the forming base paper on which the outer layer paper sheet is laminated becomes high, and the molded article is folded. The moldability of the wrinkled portion is unfavorably reduced.

The outer layer paper sheet obtained by the above method can be bonded to a paper support via an adhesive to produce a molded base paper. Examples of the bonding method include a wet lamination method in which a water-based adhesive such as a synthetic resin emulsion, starch, and PVA is applied to paper and then pressed and dried with a nip roll, or a hot-melt adhesive that is hot-melted is applied to the paper and the nip roll is used. The method is not particularly limited, and may be a hot melt lamination method in which pressure is applied, or an extrusion lamination method in which a thermoplastic resin such as polyethylene or polypropylene melted into heat is formed into a film and spread on paper, and then pressure-bonded with a nip roll.

[Paper Support] As the natural pulp fibers constituting the paper support of the present invention, wood fibers (chemical pulp, mechanical pulp), non-wood fibers, waste paper pulp and the like can be mentioned. Among wood fibers, chemical pulp includes kraft pulp that uses caustic soda and sodium sulfide during wood chip digestion, and sulfite pulp that uses sulfurous acid and bisulfite, and these pulp are bleached even if they are unbleached. It may be processed. As mechanical pulp, ground wood pulp (GP) obtained by grinding logs with a grinder, refiner ground wood pulp (RGP) obtained by grinding (refining) waste wood from a sawmill, and wood chips are used. heating,
Thermomechanical pulp (TMP) obtained by refining treatment is exemplified. Among these mechanical pulp, TMP is most suitable in terms of bulkiness and strength of the sheet. Other than the above, there are C-TMP in which wood chips are chemically treated and then refined under pressure, and BC-TMP which has been subjected to bleaching. Of these wood fiber pulp, pine, larch, cedar, fir,
Pulp with a long fiber length obtained from conifers such as hinoki is preferably used for improving the stretchability and strength of a paper sheet. Further, pulp having a short fiber length obtained from hardwoods such as hippo, beech, maple, elm, chestnut and the like can be used in combination within a range not to impair the effects of the present invention.

The non-wood fibers usable for the paper support of the present invention include bast fibers such as mulberry, mitsumata, ganpi, flax, thyme, kenaf, choma, jute, sun hemp, and seed hairs such as cotton and cotton linter. Fiber, leaf fiber such as Manila hemp, sisal, esparto, bamboo,
Stem fibers such as rice straw, wheat straw, sugarcane bagasse and the like. In particular, mulberry, mitsumata, kenaf, manila hemp, sisal hemp, cotton, cotton linter, and the like have a long fiber length and can improve the stretchability and strength of a paper sheet and are preferably used. Such non-wood fibers are used after being digested and pulped by a conventional method. Examples of the cooking method include a soda cooking method using caustic soda, a kraft cooking method using caustic soda and sodium sulfide, and a sodium sulfite cooking method using caustic soda and sodium sulfite. The non-wood fiber pulp obtained by the cooking method may be unbleached or bleached. Non-wood fibers can be pulped by grinding (refining) under pressure and heat using a refiner, similarly to wood fibers.
Examples of the waste paper pulp that can be used as the paper support of the present invention include waste cardboard, waste magazine, and the like. Particularly, waste cardboard is preferably used because it can improve the stretchability and strength of a paper sheet. These pulp fibers can be used alone or in combination of two or more. Further, synthetic resin fibers can be mixed as long as the effects of the present invention are not impaired. Examples of the synthetic resin fibers that can be used include polyethylene fibers, polypropylene fibers, polyamide fibers, polyethylene terephthalate fibers, and polybutylene terephthalate fibers.

In general, when the drawn compact has a curved surface portion with large distortion, it is necessary to absorb the distortion by forming a fold wrinkle in the curved surface portion during molding. At this time, the crease portion is folded in a plane direction like an accordion to form irregularities, and then the irregularities are compressed in the thickness direction. For this reason, in order to obtain good moldability, it is necessary to lower the density of the paper support. For this purpose, it is preferable to use rigid pulp fibers. Generally, a pulp fiber is beaten (a mechanical external force is applied to the pulp fiber to fibrillate a part of the cell wall of the fiber) to obtain a paper sheet having a uniform formation. It is necessary to keep beating lightly in order to maintain rigidity. As the degree of beating, for example, in the case of chemical pulp, freeness (Tappi T-22)
(7 Canadian standard type) is preferably 500 mlcsf or more for mechanical pulp, 180 mlcsf or more for hemp pulp and kenaf pulp, and 500 mlcsf or more for waste cardboard pulp. A beater, a conical-type refiner, a drum-type refiner, a disk-type refiner, or the like is used for beating pulp fibers.

Further, within a range that does not impair the effects of the present invention,
It is also possible to lower the sheet density by mixing a foaming agent into the sheet. As the foaming agent, a heat-expandable microcapsule in which a low-boiling-point solvent is sealed in a microcapsule can be used. This capsule is about 4 to 5 times in diameter and 50 to 50 in volume by heating at a relatively low temperature of 80 to 200 ° C. for a short time.
These particles have an average particle diameter of 10 to 30 μm that expands 100 times. Isobutane, pentane, petroleum ether, hexane,
A volatile organic solvent (swelling agent) such as a low-boiling halogenated hydrocarbon or methylsilane is wrapped in a thermoplastic resin consisting of a copolymer such as vinylidene chloride, acrylonitrile, or acrylate, and the capsule is softened. When heated above the point, the membrane polymer begins to soften, the vapor pressure of the contained swelling agent increases, the membrane expands, and the capsule expands. Such a foaming agent is added to the pulp slurry, and foams by heating and drying during paper sheet making, or foams by passing a sheet containing the foaming agent through high-temperature water. Further, a hollow capsule such as a shirasu balloon may be added to the pulp slurry during paper sheet making to reduce the sheet density.

Examples of papermaking chemicals include sizing agents, paper-strengthening agents, and retention-improving agents used in ordinary papermaking. As the sizing agent, there are internal sizing agents such as alkyl ketene dimer, styrene acrylic resin, and rosin. Examples of paper strength agents and retention aids include polyacrylamide resins, polyamide epichlorohydrin resins, polyethyleneimines and derivatives thereof, polyethylene oxides, polyamines, polyamides, polyamide polyamines and derivatives thereof, cationic and amphoteric starches, oxidized starches, carboxymethylated starches , Plant gums, organic compounds such as polyvinyl alcohol, and inorganic compounds such as sulfate band, alumina sol, colloidal silica, bentonite and the like are used in appropriate combination. Examples of fillers include mineral fillers such as talc, kaolin, calcined kaolin, clay, diatomaceous earth, heavy calcium carbonate, magnesium carbonate, aluminum hydroxide, titanium dioxide, magnesium sulfate, silica, aluminosilicate, bentonite, and polystyrene particles. Organic synthetic fillers such as urea formalin resin particles and the like can be appropriately selected and used in combination. Further, papermaking additive aids such as dyes, pH adjusters, slime control agents, defoamers, and tackifiers can be used as appropriate depending on the application.

A slurry of the raw materials and chemicals made of the above-mentioned materials is made by a conventional method. The papermaking may be any of ordinary fourdrinier paper machine, circular net paper machine, short net paper machine, inclined paper machine, various combination paper machine, and the like, and is not particularly limited. Drying may be performed by any of ordinary multi-cylinder dryers, Yankee dryers, through dryers, etc., and is not particularly limited. In the present invention, the paper support obtained from the papermaking step may be not only a single layer but also two or more layers of laminated paper. It is also possible to apply starch, polyvinyl alcohol, various surface sizing agents, pigments and the like to the surface of the sheet by a coating method such as a size press or a gate roll.

[About Multilayer Paper Obtained by Multilayer Papermaking] The multilayer paper of the present invention may be formed by laminating a paper sheet as an outer layer and a paper support as described above. It may be a multilayer paper having a low-density layer obtained by lamination and an outer layer having a higher density. In this case, the density of the low density layer is less than 0.7 g / cm ³ , more preferably 0.2 to 0.6 g / cm ³ , and most preferably 0.3 to 0.5 g / cm ³ . 0.2 g / cm ³
If it is less than 1, the interlayer strength of the obtained multilayer paper may not be sufficient. When the density exceeds 0.7 g / cm ³ , the density of the whole formed base paper is 0.4 to 0.7 g / c 3.
m ³ becomes difficult. The outer layer has a density of 0.
It is preferably in the range of 7 to 0.9 g / cm ³ .
If it is less than 0.7 g / cm ³ , it may be difficult to obtain a molded container having high rigidity during drawing. Also,
When it exceeds 0.9 g / cm ³ , the outer layer becomes too tight, so that press formability is not accompanied. It is also substantially difficult to obtain a higher density layer at the papermaking stage.

The various conditions such as the type or freeness of the pulp fibers constituting the low density layer and the foaming agents, papermaking chemicals, fillers and other additives preferably used as pulp slurry during papermaking are described above. These are exactly the same as those preferably used for the paper support.
Also, various conditions such as the type or freeness of the pulp fiber constituting the outer layer having a higher density than the low-density layer, and chemicals for papermaking, fillers, and other additives preferably used as various additives added to the pulp slurry during papermaking are described above. It is exactly the same as that preferably used for the outer layer paper sheet, but the elongation at break of the outer layer having a high density is set to 5% or more.
For that purpose, the raw material to be the outer layer is preferably made of N having a particularly long fiber length.
BKP is added, and the degree of beating is further increased to 400 to 550.
It is preferred that the papermaking be performed while paying attention to the point of adjusting the fiber orientation to mlcsf and reducing the aspect ratio of the fiber orientation so as to approach 1. Further, the range of the basis weight of the outer layer is 15 to 100.
range of g / ^{m 2} by weight, more preferably in the range of 40 and 80 g / ^{m 2.} If it is less than 15 g / m ² , it is difficult to obtain a high-density paper layer, and it is also difficult to make paper itself. On the other hand, if it exceeds 100 g / m ² , since the basis weight of the low-density layer is reduced as a whole, the overall density of the base paper for forming is increased, and the density may be in the range of 0.4 to 0.7 g / cm ^3. Have difficulty. In addition, the elongation at break and the basis weight of the outer layer of the multilayer paper obtained by lamination as described above can be measured by peeling the paper layer again after the papermaking.

[Regarding Forming Base Paper] As described above, the basis weight of the forming base paper obtained by lamination or multi-layer papermaking is preferably in the range of 100 to 500 g / m ² , more preferably 200 to 400 g / m 2. ² range. If the basis weight is less than 100 g / m ^{2, the} molded article obtained after drawing does not have sufficient strength, and 500 g
/ M ² is not preferred because the moldability of the folded wrinkles is reduced. 0.4-0.7 for density of forming base paper
g / cm ³ is preferred. The density is 0.4 g / cm ³
If it is lower, the molded article obtained after drawing does not have sufficient strength for practical use, and if it exceeds 0.7 g / cm ³ , the moldability of the folded wrinkles is undesirably reduced.

In order to impart water resistance to the surface of the base paper for forming as required, emulsions of waxes such as microcrystalline wax and paraffin wax, latexes such as SBR latex and polyvinylidene chloride latex may be used as coating materials. Acrylic emulsions,
Each of synthetic resin emulsions such as self-emulsifying polyolefins and polyethylene copolymer resin emulsions can be applied. As coating equipment for these water-resistant paints,
Any of a commonly used bar coater, air knife coater, roll coater, blade coater, gate roll, size press, etc. may be used, and is not particularly limited.

If necessary, a synthetic resin layer can be provided on the surface of the forming base paper. Examples of the synthetic resin used include polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; saturated polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamide resins such as nylon; ethylene-vinyl alcohol copolymer; and polystyrene. resin,
A polyacrylonitrile resin and the like are mentioned, and these synthetic resins are coated with a single substance or a mixture of two or more kinds or laminated to form a water-resistant coating. The method for laminating the synthetic resin layer may be any of commonly used wet lamination, hot melt lamination, extrusion lamination, dry lamination, thermal lamination and the like, and is not particularly limited.

[Drawing] With regard to drawing,
Generally, a blank sheet is formed by punching a formed base paper into a predetermined shape before forming. In the drawing, the blank sheet is pressed to obtain a molded body. In particular, when the molded body has a curved surface portion with a large distortion, it is necessary to form a ruled line on the molding base paper in advance. At the time of drawing, a fold wrinkle is formed around the ruled line to absorb the distortion of the curved surface portion. To form the ruled line, as in a general paper box, the thickness is 1 m.
A wooden plate or a metal plate (ruled line type) having a plurality of metal blades of about m is used, and the ruled line type metal blade is pressed against a forming base paper to form a ruled line. The formation of such ruled lines can be performed simultaneously with the blank sheet punching. One or two or more blank sheets thus obtained can be press-molded. At this time, the formed base paper can be conditioned in advance to adjust the base paper moisture. The moisture content of the base paper is preferably in the range of 10 to 20%, particularly preferably 11 to 17%. The term “base paper moisture” as used herein refers to the mass% of moisture based on the absolute dry mass of all pulp in the processed base paper. When the moisture content of the base paper is in this preferred range, plasticization of the formed base paper occurs, thereby improving the formability and reducing the destruction of the paper layer during forming.
As a result, it is possible to obtain a drawn molded container having a greater depth, a smooth and beautiful appearance, and a high rigidity. If the base paper moisture is less than 10%, sufficient rigidity cannot be obtained in the molded article, and if it is 20% or more, blisters are generated in the formed base paper and the paper layer of the base paper is peeled off. Therefore, it takes a long time for drying, and a problem such as a decrease in productivity occurs, which is not preferable. In addition, as a method for preparing the base paper moisture, a method of supplying water to the base paper immediately before press molding, a method of transporting and storing in a state where the moisture is maintained in a state where paper is humidified after leaving the dryer during papermaking, and the like is maintained. No.

The press forming apparatus used in the drawing is not particularly limited, but a metal forming die composed of a male type and a female type used in general press forming can be used. The temperature during drawing is preferably in the range of 100 to 200 ° C, more preferably 110 to 150 ° C, from the viewpoints of moldability, deterioration of pulp fibers, and the like. If the molding temperature is lower than 100 ° C., the pulp fibers do not sufficiently soften, so that good moldability cannot be obtained, and if it exceeds 200 ° C., the pulp fibers deteriorate, which is not preferable. The heating method at this time is preferably performed by heating the metal mold for molding from the viewpoint of workability. Means for heating the metal mold for molding include a heating method using an electric heater, a steam heating method, a hot air heating method, an oil circulation method, and the like, and an electric heating method with a simple apparatus is preferable. For the press pressure during drawing,
10-100 kgf / cm ^{2 in} terms of moldability and paper layer destruction
Is preferable. If the pressing pressure is lower than 10 kgf / cm ² , the compression deformation of the ruled line portion becomes insufficient, and
If it exceeds gf / cm ² , the paper layer at the folded wrinkle portion is broken, which is not preferable. The press time at the time of drawing is preferably in the range of 2 to 10 seconds from the viewpoint of moldability and workability. The base paper for forming according to the present invention contains natural pulp as a main component and has better moldability and remarkable productivity as compared with conventional forming base paper. Furthermore, compared to the conventional plastic molded body, the calorie burned is lower and no corrosive gas is generated during incineration.

[0028]

The present invention will be described in detail below with reference to examples. The following examples do not limit the present invention. Unless otherwise specified, parts by mass are indicated by mass of solid content.

<Example 1> Commercially available NBKP was converted to 550 mlcsf (TappiT-2) using a disc refiner.
27 Canadian standard type) and 30 radiata pine TMP
Beated to 0 mlcsf. Using these as stock, a paper support having a two-layer structure of a first layer NBKP 40 g / m ² and a second layer TMP 250 g / m ² was formed using a multi-layer paper machine. A bleached kraft stretched paper (manufactured by Oji Paper, basis weight 75 g / m ² ) was bonded to the paper support as an outer layer sheet to obtain a molded base paper. Lamination was performed in the following procedure. Immediately after applying 20 g / m ^{2 in} terms of solid content of an EVA-based emulsion type adhesive (trade name: Vinizol 1412, manufactured by Daido Kasei Co., Ltd.) on the surface of the TMP layer of the paperboard with a Meyer bar, the wet coating layer is exposed. The kraft stretched paper was pressed with a hand roll and dried at 110 ° C. for 20 seconds with a hot air drier. The molded base paper thus obtained was evaluated for elongation at break and moldability by a test method described later.

<Example 2> An unbleached kraft stretched paper for cement bags (Oji Paper,
A molded base paper was produced and evaluated in the same manner as in Example 1 except that the basis weight was 83 g / m ² ).

Example 3 The second layer of the paper support was TMP1
A molded base paper was produced and evaluated in the same manner as in Example 1, except that the paper was 80 g / m ² and the outer layer sheet to be bonded to the paper support was kraft stretched paper for adhesive tape.

Example 4 Using a disc refiner, commercially available NBKP was beaten to 550 mlcsf and radiator pine TMP was beaten to 300 mlcsf. These were used as stock, and the first layer NBKP4 was used using a multi-layer paper machine.
0 g / ^{m 2,} was the second layer TMP220g / ^{m 2,} the paper support consisting of two layers of and papermaking. A bleached kraft stretched paper (manufactured by Oji Paper, basis weight 75 g /
m ² ) to obtain a molded base paper. Lamination was performed in the following procedure. Using an extrusion laminating machine, a stretched paper is laminated to the paper support while laminating a 15 μm-thick low-density polyethylene layer to form a sand laminating paper, and further on one side (NBKP layer side) of 40 μm thick by extrusion laminating. The base paper provided with the above polypropylene layer was used as a forming base paper, and this base paper was evaluated in the same manner as in Example 1. However,
The drawing was performed so that the polypropylene layer was inside the container.

Example 5 Using a multi-layer paper machine
First layer NBKP 40 g / m^Two, Second layer TMP250g / m
^Two, Third layer NBKP 60 g / m²Multi-layer consisting of three layers
Layer paper was formed and used as a forming base paper. However, the third layer is outside
Layer, and the stock of the outer layer is a commercially available NBKP disc
Use the one obtained by beating to 480mlcsf with inner
Was. At this time, the density of the second layer is 0.48 g / cm.³,number 3
The density of the layer is 0.7 g / cm ³, The density of the entire multilayer paper is 0.
53g / cm³Met. The obtained third layer is formed
After making the processed base paper, the paper layer is peeled off again and the breaking elongation (J
IS-P8113) was measured to be 5.8 in MD.
% And 6.0% by CD.

<Comparative Example 1> Unbleached kraft paper for light packaging (made by Oji Paper, basis weight 70) was bonded to a paper support.
g / m ² ), and a molded base paper was produced and evaluated in the same manner as in Example 1.

<Comparative Example 2> A paper having a basis weight of 70 g / m ² was made from a stock obtained by beating a commercially available NBKP to 640 mlcsf with a disc refiner and dried at 110 ° C. with a rotary dryer. . A molded base paper was manufactured and evaluated in the same manner as in Example 1 except that this handmade paper was used as an outer layer sheet to be bonded to a paper support.

<Evaluation method> (1) Elongation at break 15 mm in width and 250 m in length in each of the flow direction and the width direction
m at 24 ° C. under the conditions of 23 ° C. and 50% RH.
After humidity control for more than an hour, JIS-P81 was used using a Strograph M2 tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.).
The measurement was performed at a tensile speed of 20 mm / min in accordance with No. 13.

(2) Formability By applying steam to the forming base paper and adjusting the humidity, the water content in the paper is adjusted to 12%, punched out in a circular shape and radially engraved ruled lines from the center to form a blank sheet. . The blank sheet was molded at 130 ° C. by a test press molding machine (manufactured by Daiichi Koki Co., Ltd.) using a male and female concave and convex cup container molding die
And heating and pressurizing treatment at 35 kg / cm ^2, it is in 7cm height,
The opening is circular with a diameter of 12 cm and the bottom is 6 cm in diameter
A cup-shaped draw-formed body having a circular shape, a flange portion having a width of 0.8 cm, and a curved surface extending from the side wall to the bottom surface was formed (FIG. 1). At this time, molding was performed such that the outer layer sheet bonding side or the outer layer side was outside the molded body. The moldability at this time was evaluated as follows. ：: Moldable into a cup shape, the outer layer of the molded body was not broken, and the surface of the molded body was smooth. C: Moldable into a cup shape, but the outer layer of the molded body was broken. ×: The blank sheet was broken at the time of molding and could not be molded into a cup shape. Tables 1 and 2 show the above evaluation results.

[0038]

[Table 1]

[0039]

[Table 2]

According to Tables 1 and 2, the molded base paper according to the present invention is excellent in moldability even when a deep drawing depth such as a cup does not cause cracks or tears on the outer paper layer surface during molding. You can see that there is.

[0041]

According to the present invention, when a compact having a large drawing depth such as a cup is formed by drawing, good formability without cracking, tearing, and unevenness of the folded portion, and high productivity are obtained. It is now possible to obtain a molded base paper.

[Brief description of the drawings]

FIG. 1 is a perspective view of a drawn compact.

FIG. 2 is a cross-sectional view of a drawn compact.

[Explanation of symbols]

 1: paper support of formed base paper 2: outer layer paper sheet of formed base paper

 ──────────────────────────────────────────────────の Continued on front page F term (reference) 3E033 AA10 BA10 BB08 FA01 GA03 4F100 BA02 BA03 BA10A BA10B DG10A DG10B DG10C GB16 JK08B JL01 YY00B 4L055 AA02 AC03 AC06 AG59 AG64 AG89 AG97 AH37 AJ07 FA17 FA14 EA17

Claims (3)

[Claims] (1) At least one surface of a paper support has a breaking elongation (J
IS-P8113) is a multilayer sheet having a sheet of paper is 5% or more are laminated so that the outer layer, a basis weight is 100 to 500 g / ^{m 2} of the total multilayer sheet, density 0.4 to 0.7 g / c
molding base paper, characterized in that the range of m ^3. 2. A multilayer paper having at least a low-density layer and an outer layer having a higher density.
0 g / m ² , a density of 0.4 to 0.7 g / cm ³ ,
Molded base paper characterized in that the elongation at break of the outer layer (JIS-P8113) is 5% or more. 3. The molded base paper according to claim 1, wherein the paper support or the low-density layer is mainly composed of mechanical pulp.