JP3970272B2 - Dry mold for fiber molded body production - Google Patents

Description

  The present invention relates to a dry mold for use in the production of a fiber molded body containing pulp.

  Various techniques have been proposed in which a fiber laminate is manufactured from a slurry containing a fiber material such as pulp by a wet papermaking method, and press-molded with a dry mold to manufacture a fiber molded body. In this technique, it is important to efficiently discharge steam in order to shorten the dry molding time and improve the surface finish. As a technique in view of such steam discharge and drying efficiency, a technique described in Patent Document 1 has been proposed. In this technique, a slit groove that leads to the outside is formed on the molding surface of a hot press mold, and steam generated during dry molding is discharged from the slit groove.

  On the other hand, the applicant has so far proposed a technique related to a composite container in which a plurality of paper-making containers are made from a slurry containing fiber materials such as pulp, and these are superposed and combined (for example, see Patent Document 2 below). ).

  By the way, when manufacturing such a composite container, in order to improve the drying efficiency as described above, when a slit groove is formed in a drying mold and dry molding is performed, an attempt is subsequently made to cover the inner surface of the container with a resin film. Then, there was a problem that pinholes were generated in the resin film due to the slit marks transferred to the inner surface of the inner container. In addition, there is also a problem that the protrusions of the slit traces in the opening of the container obtained are conspicuous and the container has a poor appearance.

JP 2000-34699 A Japanese Patent Laid-Open No. 2002-321776

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a dry mold for manufacturing a fiber molded body that hardly transfers the exhaust slit marks accompanying the dry molding to the surface of the fiber molded body. .

  The present invention is a dry mold for use in the production of a fiber molded body containing pulp, having a convex molded portion, extending in a protruding direction on a side surface portion of the molded portion, and a protruding base portion of the molded portion The object is achieved by providing a drying mold for producing a fiber molded body having a narrow width on the side and a wide slit on the tip side.

  When the drying mold for producing the fiber molded body of the present invention is used, it is difficult to transfer the exhaust slit marks accompanying the dry molding to the surface of the fiber molded body. When coating with a resin film by a method, the generation of pinholes in the resin film can be suppressed. In addition, a container having a good appearance with no noticeable slit marks can be obtained.

  The present invention will be described below based on preferred embodiments with reference to the drawings.

  FIG. 1 shows an embodiment in which the dry mold for producing a fiber molded body of the present invention is applied to a dry mold for use in dry molding (manufacturing) of a cup-shaped container (a fiber molded body containing pulp) made of pulp mold. The form is shown. In FIG. 1, reference numeral 1 denotes a dry mold. Moreover, the code | symbol 10 has shown the container represented with the virtual line.

  As shown in FIG. 1 (a), the drying mold 1 has a so-called male mold-shaped convex molding portion 11. As shown in FIG. The molding part 11 is made of a material having rigidity. The molding part 11 is provided with a flange part 12 that contacts the flange part 100 of the container 10. At the tip of the molding part 11, there is provided a thin molding part 13 whose diameter is reduced with the stacking step of the container 10 as a boundary.

  The side surface portion (molded portion of the container body portion) 110 of the molded portion 11 excluding the flange portion 12 extends in the protruding direction (the depth direction of the container), and has a width on the flange portion 12 side (projected base side) of the molded portion 11. The slits 14 having a narrow width and a wide width on the narrow molding portion 13 side (tip portion side) are provided at predetermined intervals. In the present embodiment, the molding part 11 can be divided into a block 11A on the flange part 12 side and a block 11B on the thin molding part 13 side at the division position D, and will be described later with the division position D as a boundary. The width of the exhaust slit (hereinafter simply referred to as a slit) 14 is changed. Considering the effect of suppressing the occurrence of pinholes by changing the slit width, the dividing position D is provided at a position 30 to 70% from the tip with respect to the protruding length L in the protruding direction of the molded part 11. preferable.

  The width of the slit 14 in the block 11A on the flange portion 12 side from the division position D is preferably 0.1 to 0.4 mm, and more preferably 0.15 to 0.3 mm. Moreover, 0.2-1.0 mm is preferable and, as for the width | variety of the slit 14 in the thin molding part 13 side from the division position D, 0.25-0.8 mm is more preferable. Thus, by reducing the width of the slit 14 in the block 11A and increasing the width of the slit 14 in the block 11B, the slit trace transferred to the vicinity of the opening on the inner surface of the body portion of the container 10 obtained after dry molding is obtained. The height of the ridge can be suppressed to 0.01 mm or less. For this reason, when the inner surface of the container 10 is covered with a resin film by vacuum molding or the like after drying, it is possible to prevent pinholes from being generated in the resin film at the tops of the protrusions of the slit marks. In addition, since the slit width is wide on the bottom side of the body portion of the container 10, it is possible to increase the efficiency of discharging steam generated during dry molding and shorten the drying time. Even with this wide slit, the slit trace is transferred to the bottom side of the body 10 of the container, but since this slit trace is also low in the height of the protrusion of the slit trace, Such a resin film is not so affected as to cause pinholes. Moreover, since it is a back part in the container 10, the external appearance property of a container is not impaired significantly. In particular, in the case of dry-molding a container containing a bulky treated pulp as will be described later, even if the slit width is wide, the density on the bottom side of the body 10 of the container 10 can be lowered. Even if it is wide, the height of the slit marks can be kept low. In addition, the density of the protrusions on the slit marks is reduced, the rigidity is lowered, and pinholes are less likely to occur. Here, the slit width refers to the opening width of the slit 14 on the surface side of the molded part 11.

  On the flange 12 side, the slit width is reduced to suppress the occurrence of pinholes in the film, and the slit width on the thin molding part 13 side is increased to increase the drying efficiency. Considering the balance of improvement in efficiency, the difference in the width of the slit 14 on the flange portion 12 side and the thin molding portion 13 side is preferably 0.1 to 0.6 mm. Here, the difference in the widths of the slits 14 is the average of the slit widths on the flange 12 side and the thin molding part 13 side when there is a distribution in the widths of the slits 14 on the flange part 12 side and the thin molding part 13 side. The difference between.

  It is preferable that the slit 14 is provided with a predetermined length L12, L13 from the rear surface (protruding base) of the flange portion 12 and the tip portion. The length of L12 is preferably 3 to 30% and more preferably 5 to 15% with respect to the protruding length L in the protruding direction of the side surface portion 110 of the molded portion 11. 3-30% is preferable with respect to the protrusion length L of the protrusion direction in the side part 110 of the shaping | molding part 11, and, as for the length of L13, 5-15% is more preferable. By providing the slit 14 in such a range, it is possible to suppress the transfer of the slit marks to the flange portion 100, the opening portion, and the bottom portion of the container 10 obtained. For this reason, as described above, the occurrence of pinholes when covered with the resin film can be further prevented, and the slit mark is not transferred to the surface of the flange portion 100 of the container. The sealing performance when sealing with is improved. Since the slit marks transferred in this range are also aligned in the protruding direction, even when the container 10 is used as an inner layer of a food container, there is no problem in the operation of chopsticks and spoons.

  As shown in FIG.1 (b), the front-end surface part (part which shape | molds the bottom part of the container 10) of the shaping | molding part 11 is provided with the some slit 15 opened in circular arc shape. A gas-liquid flow passage 16 that leads to the slits 14 and 15 is provided in the central portion of the molding portion 11. Then, dehydration and exhaustion are performed when the container 10 is dry-formed through the slits 14 and 15 and the gas-liquid flow passage 16.

  Inside the molding part 11, a cartridge type heater (heating means) is provided so that the block 11A on the flange part 12 side and the block 11B on the thin molding part 13 side of the division position D can be set to desired temperatures. 17 and 18 are arranged. These heaters are arranged at predetermined intervals in the circumferential direction so as to be alternately positioned when viewed from above, and the molded part 11 is heated by the heaters 17 and 18 for each of the blocks 11A and 11B. . For this reason, since each block can be heated and set to different temperatures, the drying speed according to the part of the container to be molded can be adjusted, and scorching due to partial overdrying of the container can also be prevented. For example, dry molding can be performed with a uniform temperature distribution by increasing the temperature in a narrow slit width portion and decreasing the temperature in a wide slit width portion.

  The taper angle θ of the portion corresponding to the body portion of the container 10 of the side surface portion 110 of the molded portion 11 is determined by the application of the molded product. So far, in the pulp mold method, it is usually preferred that the taper angle is 15 ° or more in order to perform stable dry molding, and molding is difficult at an angle below 15 °. In the production of the container having, it is not a papermaking method but, for example, a method of paperboard processing (cutting and rounding paperboard) has been adopted. However, if the dry mold of the present invention is used, it is possible to suppress the entry of pulp into the slit even when dry forming a container having a taper angle of less than 15 °, particularly 10 ° or less (θ = 0 to 10 °). In addition, since the molded body can be smoothly detached from the dry mold, it is possible to perform dry molding of such a container without any trouble.

  Next, a method for manufacturing the container 10 using the dry mold 1 will be described. In the following description, the dry mold 1 is also referred to as a male mold 1.

  As shown in FIG. 2A, the male mold 1 is used together with the female mold 2 having a concave molding portion 21 corresponding to the outer shape of the container 10. Between the molding part 11 of the male mold 1 and the surface of the molding part 21 of the female mold 2, when the dry mold 1 and the female mold 2 are brought into contact with each other, it corresponds to the thickness of the container 10 finally obtained. It is preferable that a predetermined clearance is provided.

  First, a container-shaped wet fiber laminate 10 ′ provided corresponding to the container 10 after drying was placed in the female mold 2.

  The wet fiber laminate 10 ′ can be used without particular limitation what is made by a wet paper making method from a raw material containing fibers such as pulp fibers, but includes bulky treated pulp as described below. In the dry molding of the fiber molded body, the high effect of the dry mold of the present invention is exhibited.

  The amount of the bulky treated pulp contained in the fiber laminate 10 ′ is preferably 10 to 90% by weight, more preferably 20 to 80% by weight, and further 30 to 70% by weight in the pulp components constituting the fiber laminate 10 ′. preferable. When the blending amount of the bulky treated pulp in the pulp component is within such a range, the bulky effect is sufficiently exhibited, and the cushioning property and heat insulating property of the flange portion 100 of the resulting container are also improved. Further, the amount of the binder used for securing the strength of the container 10 and the flange portion 100 can be suppressed to an appropriate amount. Here, the bulky treated pulp used in the container 10 refers to a pulp fiber that has been curled or hydrophobized by a bulky treatment such as a crosslinking treatment or mercerization treatment, or the rigidity of the fiber itself has been improved. As the cross-linked pulp, commercially available curd fibers (for example, “HBA” manufactured by U.S. Warehauser), and as the mercerized pulp, commercially available mercerized pulp (for example, “POROSAUIE”, “ULTRANIER,” manufactured by Rayonnia) are used. “SULFATE” can be mentioned.

The cross-linked pulp, mercerized pulp or bulky treated pulp can be used alone or in combination of two or more.
The mercerized pulp can be used by mixing with the crosslinked pulp at an appropriate ratio. Mercerized pulp is less bulky than crosslinked pulp, but by adjusting the mixing ratio of mercerized pulp to crosslinked pulp, the strength of the fiber molded body and the moldability of the inner surface of the fiber molded body (transferability) ) Is improved. Moreover, flocs of pulp fibers can be suppressed, and the occurrence of papermaking unevenness can be prevented.

When the crosslinked pulp is used among the bulky treated pulp, the wet curled factor is preferably 0.1 to 1.0, particularly preferably 0.1 to 0.6. By setting the wet curled factor within such a range, desired bulkiness can be easily obtained. Further, the dispersibility in the raw material slurry is also good, the papermaking unevenness can be suppressed and uneven thickness can be prevented from occurring in the compact, and the strength and surface properties of the compact can be improved. Here, the wet curled factor, using the FQA (Fiber Quality Analyzer) was dipped in pure water at room temperature of pulp fibers, measuring the number 1000 or more, the measurement range 0.5~10mm, ((L _A / L _B ) is a value obtained by the arithmetic average of -1) and is a numerical value indicating the degree of fiber curving. However, L _A is the actual pulp fibers length, L _B is the maximum dimension of the rectangle surrounding the pulp fibers bent state.

  The fiber laminate 10 ′ can contain, as the pulp component, pulp fibers that are not subjected to bulk treatment, in addition to the bulk treatment pulp. The pulp fiber is preferably contained in the pulp component in an amount of 10 to 90% by weight, particularly 20 to 80% by weight. When the pulp fiber is contained in such a range, the strength reduction of the flange portion and the container and the generation of paper dust can be suppressed, and the amount of binder added for obtaining strength and preventing paper dust can be suppressed. . Moreover, bulkiness is also obtained and the cushioning property of the flange portion and the heat insulating property of the container are improved. Examples of the pulp fibers include unbleached or bleached kraft pulp, sulfite pulp, alkali pulp, ground pulp, or thermomechanical pulp of softwood or hardwood. These pulp fibers can be used alone or in admixture of two or more at an appropriate ratio. In particular, by mixing two or more kinds, pulp fibers having various fiber length distributions can be prepared.

  The pulp fiber preferably has a Canadian Standard Freeness (CSF) of 500 to 800 ml, particularly 600 to 750 ml. When the CSF is within this range, the drainage is good and the paper making time and drying time can be shortened. Further, papermaking unevenness can be suppressed, and uneven thickness can be prevented from being obtained in the obtained molded body, and the surface property of the molded body can be prevented from being deteriorated. Furthermore, desired heat insulation can be obtained.

  The average fiber length of the pulp fibers not subjected to bulky treatment is preferably 0.4 to 5 mm, particularly preferably 0.5 to 3 mm. When the average fiber length of the pulp fibers is within such a range, moderate entanglement with the bulky treated pulp can be obtained, and the resulting molded article can be prevented from strength reduction and paper dust generation. Moreover, since flocs (aggregation of pulp fibers) do not increase and papermaking unevenness is unlikely to occur, it is possible to prevent uneven thickness from occurring and deterioration of surface properties.

  Any of the pulp fibers of wood pulp or non-wood pulp can be used for the bulky treated pulp and the pulp fiber used as the pulp component of the container 10 (fiber laminate 10 '). Further, any pulp fiber of virgin pulp and waste paper pulp can be used. These pulp fibers can be used alone or in admixture of two or more at an appropriate ratio.

  In the container 10 (fiber laminate 10 ′), additives such as fiber materials other than pulp fibers, dispersants, pigments, fixing agents, fungicides, sizing agents, adhesives, paper strength reinforcing agents, and the like are added as necessary. What was included in an appropriate ratio can be used.

  Next, the female mold 2 containing the fiber laminate 10 ′ is lowered from above the male mold 1. Then, as shown in FIG. 2 (b), the male mold 1 and the female mold 2 are brought into contact with each other, and the fiber laminate 10 'is sandwiched between them with a predetermined pressing force to be dry-molded.

  The male mold 1 and the female mold 2 are preferably heated to a predetermined temperature in advance. The temperature of these molds when dry-molding the fiber laminate 10 ′ is 110 to 110 in consideration of prevention of scorching of the fiber laminate 10 ′ during dry molding, improvement of drying efficiency, improvement of surface smoothness, and the like. It is preferable that it is 250 degreeC, especially 120-230 degreeC.

  In the dry molding process of the container 10, the molding part 11 heated by the heaters 17 and 18 of the male mold 1 comes into contact with the container 10, and the liquid component (vapor) in the container 10 passes through the slits 14 and 15 and the gas-liquid passage 16. It is discharged outside.

  After the container 10 is dried, as shown in FIG. 2 (c), the female mold 2 is pulled up to expose the container 10, and is removed from the male mold 1 to finish the dry molding of the container 10. When the inner surface of the container 10 thus dry-molded is covered with a resin film, slit marks that cause pinholes are hardly transferred. Moreover, when the pulp fiber containing the above-mentioned bulky treated pulp is used, it is excellent in heat insulation, and it becomes a suitable container for use as an inner layer of a heat insulation composite container in view of the point that slit marks are difficult to be transferred. .

  As described above, according to the drying mold 1 of the present embodiment, it is difficult to transfer the exhaust slit marks accompanying the dry molding to the surface of the obtained fiber molded body. When the molding surface is covered with a resin film by a method such as that described above, the occurrence of pinholes in the resin film can be suppressed.

  The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

  In the present invention, it is preferable that the molded part is constituted by a plurality of blocks that can be divided as in the above embodiment, but the molded part can also be constituted by one block.

  The dry mold according to the present invention is a cylindrical shaped fiber molded body having a flange portion in addition to a cup-shaped container such as a bowl (flange for bonding the inner layer container and the outer layer container together after molding them) The present invention can also be applied to drying (manufacturing) of a fiber molded body having a portion.

Hereinafter, the present invention will be described more specifically with reference to examples.
[Example 1]
A heat-insulating composite container having the following dimensions and shape in the form shown in FIG. 3 was produced as follows.

<Insulated composite container dimensions>
Height H: 106mm
Mouth inner diameter φ10: 90mm
Flange thickness T11: 2mm
Flange outer diameter φ11: 96mm
Body thickness T121: 1.69 mm (position 100 mm from the bottom)
Body thickness T122: 1.36 mm (position 40 mm from the bottom)
Body thickness T123: 1.87 mm (position 15 mm from the bottom)
Body angle θ1: 6.5 degrees Body angle θ2: 4 degrees Bottom thickness T14: 0.95 mm
Bottom outer diameter φ14: 68.5mm
Raised bottom height H14: 3mm
Raised bottom outer diameter φ141: 40mm
Inner diameter of bottom contact surface φ142: 55mm
Corner radius of curvature Ro: 2 mm
Corner radius of curvature Ri: 2 mm

<Making paper laminate for inner layer container (container 10) / outer layer container>
Using a papermaking mold in which a perforated plate is bent and welded into a male shape, and a metal net is welded and processed in the same manner, water is injected first, then the following raw material slurry is supplied, and wet fibers A laminate was formed.
Raw material slurry for inner layer container;
Formulation: (pulp fiber (HBA (made by Warehauser)) / pulp for outer layer = 5/5: mass ratio, CSF = 720 ml), pulp fiber concentration in the pulp slurry is 0.5% by mass, 0.25 mass%)
Sizing agent: 2% by weight of pulp
Raw material slurry for outer layer container;
Formulation: (pulp fiber (trade name Hinton / trade name Cenibra = 3/7: mass ratio, CSF = 450 ml), the pulp fiber concentration in the pulp slurry is 0.5 mass%, and the concentration after water is added is 0.25 mass %)
Sizing agent (2% by weight of pulp)

<Production of inner layer container (container 10)>
The obtained fiber laminate for the inner layer was dry-molded under the following conditions using a male mold 1 and a female mold 2 as shown in FIG. 2 to produce a container 10, which was used as an inner layer container.
Slit width of male mold 1: 0.2 mm on the block 11A side, 0.3 mm on the block 11B side
Number of slits: 16, equidistant male projection length L: 105.6 mm
Male mold 1 split position L14: 45mm
L12: 14mm
L13: 8.5mm
Male mold 1 temperature: 200 ° C, female mold 2 temperature 200 ° C, drying time 25 seconds.

<Preparation of outer layer container>
The obtained outer layer fiber laminate was placed in an outer layer drying mold (not shown), and dry molded under the following conditions.
Mold temperature: 170 ° C
Pressing force: 9800N (pressing continues for 50 seconds)

<Formation of coating layer>
After the inner layer container (container 10) and the outer layer container were combined, the following resin film was placed in contact with the inner layer container and laminated under the following molding conditions.
Resin film (two-layer structure);
Outer layer / inner layer = high density polyethylene / low density polyethylene Resin film total thickness: 200 μm (before molding)
Molding condition;
Vacuum forming machine: PLAVAC-FE36PHS, manufactured by Sanwa Kogyo Co., Ltd. Film heating method: Infrared heater (space between heater and resin film 110 mm)
Film heating temperature: 300 ° C (molding machine display temperature)
Film heating time: 26 seconds Plug dimensions: Diameter 60 mm x length 110 mm
Plug material: Aluminum alloy (Fluoro resin processing on the surface)
Plug temperature: 110 ° C (plug actual surface temperature)
Mold temperature for vacuum forming: 110 ° C (actual surface temperature inside the mold)
Molding time: 10 seconds

[Comparative Example]
A composite container was produced in the same manner as in Example 1 except that the male slit width was changed as follows.
Slit width of male mold 1: block 11A side 0.3mm, block 11B side 0.3mm

[Measurement of the height of the protrusion on the slit trace]
A measurement sample was cut out from the molded body before vacuum forming, the cross section was observed at a magnification of 50 times using a tool microscope, and the height of the ridges by the transfer of the slits was measured.

In the heat-insulated composite container obtained in the examples, no pinholes were seen in the resin film of the coating layer. Further, the height of the protrusions in the vicinity of the opening was 60 μm, and the appearance was hardly noticeable. Furthermore, when a lid made of a film having a three-layer structure of paper layer / aluminum layer / synthetic resin layer was joined to the flange portion by hot pressing, the opening of the container could be sealed with high sealing performance. In addition, the slit marks seen on a part of the torso did not hinder the operation of chopsticks and spoons.
On the other hand, in the heat insulating composite container obtained by the comparative example, many pinholes were observed at the end of the slit mark on the opening side. Moreover, the height of the protrusions in the vicinity of the opening was 110 μm, which was conspicuous in appearance.

It is a figure which shows typically one Embodiment of the dry type | mold of this invention, (a) is an elevation view, (b) is sectional drawing seen in cross section in the heater arrangement position of two places. It is sectional drawing which shows typically the manufacturing process of the fiber molded object using the dry type | mold of the said embodiment, (a) shows the state which distribute | arranged the female type | mold which arranged the fiber laminated body of the wet state on the male type | mold. FIG. 4B is a diagram illustrating a dry-molded state of the fiber laminate, and FIG. 5C is a diagram illustrating a state where the fiber-molded body is separated from the dry mold. It is a figure which shows typically an example of the heat insulation composite container produced in the Example, (a) is a half sectional view, (b) is an enlarged view of the A part of (a), (c) is a figure of (a). The enlarged view of the part of B, (d) is the enlarged view of the part of C of (a).

Explanation of symbols

1 Male type (dry type)
DESCRIPTION OF SYMBOLS 11 Molding part 12 Flange part 14 Exhaust slit 17, 18 Heater (heating means)
2 Female mold 21 Molding part 10 Container (fiber molded body)
100 Flange

Claims (5)

  A drying mold for use in the production of a fiber molded body containing pulp, having a convex shaped portion, extending in a protruding direction on a side surface portion of the molded portion, and having a width on the protruding base side of the molded portion. A drying mold for producing a fiber molded body, which is narrow and is provided with an exhaust slit which is wide at the tip end side.   The width of the slit on the protruding base side is 0.1 to 0.4 mm, the width of the slit on the tip side is 0.2 to 1.0 mm, and on the protruding base side and the tip side. The drying mold for producing a fiber molded body according to claim 1, wherein the difference in width of the slit is 0.1 to 0.6 mm.   The drying mold for producing a fiber molded body according to 1 or 2, wherein the molding part is composed of a plurality of blocks that can be divided, and the width of the slit is changed for each block.   The drying mold according to claim 3, wherein the plurality of blocks include heating means capable of setting a temperature. 5. The slit is provided with a remaining length of 3 to 30% from the protruding base and the tip with respect to the protruding length L in the protruding direction of the molded portion. Dry mold for manufacturing fiber molded products.