JP4585180B2 - Pulp cellulose forming method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulp cellulose molding method, and more particularly, a pulp mold molded body having a shape such as a tray used as a container for storage and sale of foods, etc., from pulp slurry raw materials using straw pulp in particular. The present invention relates to a pulp cellulose molding method for producing a pollution-free pulp mold molded body having excellent water leakage resistance, low hygroscopicity, and high rigidity.
[0002]
[Prior art]
Various molded containers including synthetic resin tableware such as polyurethane are used for sales and storage of foods and fresh vegetables.
However, these synthetic containers are in a situation where their use is restricted due to the need for environmental protection due to the contained components, and they must be replaced with natural materials. Molded containers have attracted attention.
[0003]
As a pulp cellulose molding method for producing a pulp mold molded body formed into a three-dimensional shape using a pulp raw material liquid, conventionally, suction filtration is performed on a papermaking mold in which a pulp slurry is formed into a predetermined container shape, and the papermaking is performed. Thereafter, a method of dehydrating and removing a water-containing paper-molded body having a predetermined shape from the paper-making mold and drying in a drying furnace is employed. Furthermore, a male mold and a female mold that engage with each other in the pulp mold molding intermediate after drying in order to correct the distortion of the shape of the molded article that occurs during drying, ensure dimensional stability, and smooth the surface. A step of heating and pressurizing with a shape-modifying press formed of a mold is provided.
[0004]
However, when the pulp mold molded body produced through each of the steps as described above is used as a food container or the like, liquid leakage occurs and it cannot be used as a liquid container. On the other hand, (1) a method in which a molded body material is mixed with a water leakage preventing agent, (2) a method in which a water-resistant agent is applied to the surface of the molded product, and (3) a method in which a film such as polyethylene is raffinated on the molded body Such measures have been taken.
[0005]
For example, according to Patent Document 1 (Japanese Patent Publication No. 58-28400), a paper cup-shaped container excellent in water resistance by adding a sulfuric acid band as a rosin sizing agent and a fixing agent to a pulp slurry, particularly a deep-squeezed portion. A method for manufacturing a paper container is disclosed. Patent Document 2 (Japanese Patent Laid-Open No. 7-186308) discloses a non-polluting tableware product in which a waterproofing agent such as a fatty acid salt such as calcium stearate, calcium palmitate and cellulose stearate is mixed with pulp to improve the waterproofness. It is disclosed. Similarly, Patent Document 3 (Japanese Patent Application Laid-Open No. 11-348957) discloses a food-made paper container that uses hot pulp or other natural pulp as a raw material and is subjected to hot-pressure molding by adding a waterproofing agent and an oilproofing agent such as rosin. The manufacturing method is described. As described above, a paper container manufactured using pulp liquid as a raw material is indispensable for blending a waterproofing agent, a coating agent and the like.
[0006]
However, such waterproofing agents, coating agents, plastics, etc. may cause environmental problems associated with disposal of paper containers, and a pulp cellulose molding method that does not use such additives in order to cope with environmental conservation in recent years Development has been eagerly desired.
[0007]
[Patent Document 1]
Japanese Patent Publication No. 58-28400 [Patent Document 2]
JP-A-7-186308 [Patent Document 3]
Japanese Patent Laid-Open No. 11-348957
[Problems to be solved by the invention]
Therefore, the subject of the present invention is a pulp mold molded body produced using only pulp as a raw material without using additives such as the waterproofing agent and a synthetic product such as a plastic film, and can prevent water leakage. Another object of the present invention is to provide a pulp cellulose molding method for producing a pollution-free pulp mold molded body capable of controlling rigidity and hygroscopicity.
[0009]
A second object of the present invention is to provide an automated manufacturing method of a pulp slurry molded body from pulp slurry.
[0010]
[Means for Solving the Problems]
Therefore, in view of the state of technical development as described above regarding the production of a pulp molded article, the present inventor has intensively studied to solve the above problems, and as a result, the pulp slurry is subjected to a conventional papermaking process, a dehydration / drying process, and By providing a pulp cellulose forming method including a papermaking process, a pressing / drying process, a shape heat setting process, and a curing process, which are different from the manufacturing method comprising the press finishing process, in particular, by providing a curing process, Since the cellulose component of the component is cured, the surface of the pulp mold molded body is keratinized, and it has been found that water leakage of the molded body can be prevented. Based on these findings, the present invention has been completed.
[0011]
Thus, according to the present invention,
1) The pulp slurry is supplied to a cocoon forming mold having a number of suction holes, dehydrated from the cocoon forming mold, and a pulp mold forming intermediate having a shape corresponding to the shape of the cocoon forming mold is placed on the cocoon forming mold. A paper making process to be formed;
2) The hydrous pulp mold intermediate obtained in the paper making process is pressed with a pressure core mold having a shape that engages with the shape of the koji forming mold while being held on the koji forming mold,
Squeezing and drying process to squeeze the remaining water,
3) The pulp mold molding intermediate having a water content of 10% or less obtained in the pressing / drying step is transferred to a curing mold having the same shape as the shape of the cocoon forming mold, and the pulp mold molding intermediate A shape heat setting step of pressing the pressure core mold at a temperature of 100 ° C. to 120 ° C., a pressure of 0.2 MPa or less, and fixing the shape of the pulp mold intermediate,
4) Temperature of the pulp mold molding intermediate obtained in the shape heat setting step on the curing mold;
A pulp cellulose molding method for producing a pulp mold molded body comprising heating steps of 150 ° C. to 180 ° C. and a curing step of pressing under pressure of 0.2 Mpa to 0.3 Mpa with the pressure core mold. In addition, a pulp cellulose molding method is provided, in which the water leakage resistance of the pulp molded article is improved and the moisture absorption is 10% or less.
[0012]
Although this invention provides the pulp cellulose molding method which consists of said each process, what is hung up over the following 1) -5) as a more preferable embodiment is included.
1) The pulp cellulose molding method, wherein the pulp slurry is a mixture of 0.5 parts by weight or less of wood pulp (B) with respect to 1 part by weight of straw pulp (A).
2) The moisture content in the pulp mold product obtained in the pressing / drying step is 45%.
The said pulp cellulose molding method which is the following.
3) The pulp cellulose molding method, wherein the conditions of the pressing / drying step include a temperature controlled by a heating means provided in the pressure core mold.
4) As for the conditions of the shape heat setting step, the temperature of the pressure core mold and the curing mold are both 100 ° C. to 120 ° C., and the pressure of the pressure core is controlled to 0.08 MPa to 0.15 MPa. The pulp cellulose molding method, which is under different conditions.
5) The temperature of the pressure core mold and the curing mold in the curing step are both 150 ° C.
The pulp cellulose molding method, wherein the temperature is 180 ° C. and the pressure of the pressure core mold includes 0.2 MPa to 0.3 MPa.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
The flowchart which shows the manufacturing process of the pulp mold molded object in the pulp cellulose molding method which concerns on this invention is shown in FIG.
[0014]
According to FIG. 1, the papermaking intermediate formed body obtained by the pulp slurry suction step (A) is subjected to a shape heat fixing step (D) by a heating press after the suction dehydration step (B), the squeezing / drying step (C). , Stabilize the form. The manufacturing process of the pulp mold molded object by passing through the shape heat setting process, and also through the hardening process (E) and finishing process (F) which press at high temperature is shown.
[0015]
The form of the pulp mold molded body according to the present invention is not particularly limited, and each mold used for the two sexually engageable wrinkle forming molds or the curing mold and the pressure core mold is arbitrarily designed. Although various forms can be manufactured by this, when a specific example is given as a pulp mold molded body that can be manufactured efficiently and easily, a food container having the form shown in FIGS. 2 and 3 can be exemplified.
Therefore, for convenience, the following description and drawings in each step of the pulp cellulose molding method according to the present invention will be made with respect to the food container, but it is of course not limited thereto.
[0016]
(1) Papermaking process The papermaking process in the pulp cellulose molding method according to the present invention is a papermaking process in which the pulp slurry is passed through a koji forming mold provided with a large number of suction holes, and the fibers in the pulp slurry are combed. It is a step of forming a pulp molding intermediate along the shape of the koji forming mold on the top. The cocoon forming mold is usually used in the form of a female mold that is open upward or in the form of a male mold that is open downward. It can be arbitrarily selected depending on the process and the molding apparatus. In particular, a female ridge-forming mold opened upward is simple in terms of operation and device design.
[0017]
FIG. 4 is a schematic view of an apparatus for a paper making process in which the cocoon forming mold 12 is installed on the cocoon forming mold support 15. A filling bucket 11 for supplying the pulp slurry 100 is provided on the upper part of the koji forming body 12. The cocoon forming mold 12 is provided with a recess 14, and suction holes 121 are perforated on the bottom surface and the side surface, and moisture from the pulp slurry supplied to the recess 14 of the cocoon forming mold 12 passes through the suction hole 121. Removed downward.
[0018]
In FIG. 5, the pulp slurry 100 is supplied to the recess 14 of the cocoon forming mold 12, the water in the pulp slurry is drained by suction dehydration from the hole 121, and the fibers in the pulp slurry are accumulated on the cocoon forming mold 12. The state in which the pulp molding intermediate S is formed is shown.
[0019]
The material of the wrinkle forming mold is not particularly limited, but it may be further added to the curing mold used in the subsequent process, that is, the shape heat setting process and the curing process performed under conditions of heating and pressure. Since a hardening process is performed under conditions of temperature and pressure, those using a metal material such as a copper alloy are preferable.
[0020]
More specifically, the papermaking process for forming the pulp mold forming intermediate from the pulp slurry will supply the pulp slurry 100 to the concave portion 14 of the cocoon forming mold 12, evacuate the inside of the filling bucket 11, and place it on the cocoon forming mold. The thickness of the ridge formed is made uniform on both the side surface and the bottom surface. By uniforming the thickness of the cocoon, the thickness of the pulp molding intermediate S formed on the cocoon forming mold can be made uniform, and the fiber density can be made constant. The evacuation is performed by allowing air or an inert gas to pass through the pulp slurry. When the slurry in the pulp slurry forms a uniform state by the evacuation, the drainage provided below the cocoon forming mold. The mechanism (not shown) is opened, and water is instantaneously drained from the pulp slurry in the recess 14 of the koji forming mold 12. By such instant drainage, a molded body having a uniform thickness on both the side surface 5 and the bottom surface 3 can be obtained on the ridge forming mold 12.
After the drainage from the hole 121 of the ridge forming mold 12 is completed, further suctioning is performed.
[0021]
The pulp slurry of the papermaking raw material used in the papermaking process is preferably a straw pulp slurry or a mixture of straw pulp and wood pulp slurry. Persimmon pulp is obtained by processing perennial persimmons of the grass family. The kites are naturally grown in large numbers along the rivers and lakes in China. To obtain the kite pulp, for example, first, the kites are washed to remove dirt, and then cut to an appropriate size. Cook in high pressure steam at about 200 ° C for 2-3 hours. Then, the undiluted | stock solution slurry containing the cocoon pulp which consists of a cellulose fiber extracted from a cocoon by grind | pulverizing and disperse | distributing to water can be prepared. The stock solution slurry preferably contains 2 to 6% cellulose fiber. If impurities are removed from the raw pulp slurry thus obtained by filtration or the like, it is suitable as a pulp slurry used in the pulp cellulose molding method according to the present invention.
[0022]
Further, by changing the mixing ratio of straw pulp and wood pulp, it is possible to control the rigidity, hygroscopicity and other physical property values of a pulp molded product such as a tray. For example, the mixing ratio of straw pulp (A) and wood pulp (B) is in the range of (A) :( B) = 1: 0 to 1: 0.5, preferably 1: 0.1 to 1: 0.3 When set, a molded body having particularly excellent rigidity can be obtained. Hardwood pulp is preferred as the wood pulp.
[0023]
In general, the pulp only needs to be manufactured using a conventionally employed method, and examples of the manufacturing method include a kraft pulp method and a mechanical pulp method.
[0024]
In the kraft pulp method, hardwood chips, sodium hydroxide, sodium sulfide and water are charged into a digester and heated at 150 ° C. to 200 ° C. for 1 to 2 hours to obtain pulp. In the digestion of chemical pulp, lignin in the cell stroma is eluted and the wood fibers are disaggregated. In the Kraft method, sodium hydroxide + sodium sulfide is used as the cooking chemical.
The kraft pulp method can be made from almost any kind of wood, forest plant, etc.
[0025]
The wood pulp such as hardwood used in the pulp cellulose molding process according to the present invention may be obtained by such a production method.
In the paper making process, the pulp molding intermediate S formed on the inner surface of the recess 14 of the female mold forming die 12 by suction drainage as described above is water-containing, and the normal water content after suction squeezing is 30% to 30%. Those controlled to 45% are preferred.
[0026]
(2) Squeezing / Drying Process The squeezing / drying process is a process for squeezing out moisture in the hydrous pulp molding intermediate obtained in the papermaking process, which is a pre-process, and is exemplified in FIG. 6C.
In the pressing / drying process, as shown in FIG. 6, except for the filling bucket 11 used in the paper making process, a pressure core mold 21 that engages with the cocoon forming mold 12 is inserted into the recess 14 to form the cocoon forming mold. The pulp molding intermediate S formed on the surface 12 is pressed to remove water from squeezing. Moreover, the method of heating with the heating means attached to the ridge forming type | mold can also be employ | adopted as needed. The pulp mold molded product intermediate S ′ having a moisture content reduced to 45% or less by the pressing / drying step can be obtained.
Furthermore, as a pressing / drying method, a method of removing the hydrous pulp molding intermediate S from the koji forming mold 12 and holding it in a drying chamber in which the temperature and humidity are controlled may be employed.
[0027]
(3) Shape heat setting step In the shape heat setting step, the pulp molding intermediate S ′ obtained in the pressing / drying step is moved from the koji forming die 12 to a thermosetting die, and the temperature is 150 ° C. or lower. Preferably, at 100 ° C. to less than 150 ° C., and further at 100 ° C. to 120 ° C., the pressure core 21 is pressed against the pulp mold intermediate S ′; 0.2 MPa or less, preferably 0.08 MPa to less than 0.2 MPa, More preferably, it is to be subjected to a heat press treatment comprising pressing under conditions of 0.08 MPa to 0.15 MPa, particularly 0.09 MPa to 0.1 MPa, and is to fix the shape of the pulp mold intermediate.
That is, after papermaking, the deformation given to the pulp mold intermediate is corrected by drying and heating in the dehydration, pressing and drying processes.
Specifically, as shown in FIG. 7, the pulp mold molding intermediate S ′ moved to the curing mold 23 is pressed from above by the pressure core mold 21, and the shape of the molding intermediate S ′ is fixed. It is held as it is for the time required. The holding time varies depending on the composition of the pulp slurry and the amount of water, but it is sufficient to control the holding time to about 0.2 to 0.3 minutes.
[0028]
(4) Curing step The curing step is for subjecting the pulp mold intermediate S '' obtained by the shape heat setting step to a heat compression treatment under severe conditions. Curing conditions are: temperature; 150 ° C. to 220 ° C., preferably 150 ° C. to 180 ° C. and pressure; 0.2 MPa to 0.5 MPa, preferably pulp pulp molding intermediate forming the main component of pulp at 0.2 MPa to 0.3 MPa By hardening and keratinizing the cellulose component on the surface of the body, it is possible to obtain a molded product S ′ ″ with increased rigidity, excellent water leakage resistance, and low moisture absorption. Moreover, the molded product of the stable quality can be obtained by controlling the keratinization of a cellulose component according to the use conditions of the use of a pulp mold molded product.
[0029]
If the temperature does not reach 150 ° C. as the curing condition, the water leakage resistance is not sufficient. On the other hand, if the temperature exceeds 220 ° C., not only the effect but also the risk of firing occurs. Moreover, if the pressure is less than 0.2 MPa, the effect of cellulose keratinization may not be obtained.
[0030]
More specifically describing the curing step, as shown in FIG. 8, after completion of the shape heat setting step, the pulp molding intermediate S '' obtained in the shape heat setting step is subjected to the curing step, Change to curing conditions. The curing conditions are more severe than the shape heat setting conditions, the temperature is set to 150 ° C. to 220 ° C., the pressure of the pressurized core mold is increased to 0.2 MPa to 0.5 MPa, and the cellulose component The pressing state of the pressure core type is maintained until an effect such as keratinization is obtained. Usually, a pressing time of 0.2 minutes to 0.5 minutes is sufficient.
[0031]
(5) Finishing process The molded body finished through the above steps is taken out by sucking the molded body by air blowing and suction cups, and after transporting, post-processing such as trimming and sterilization is performed. As shown in FIG. 10, the pulp molded product is adsorbed by the lowered suction cup (32), and is conveyed to the product dispensing device through the product outlet.
[0032]
In the pulp cellulose molding method according to the present invention, the paper making step, the pressing / drying step, the shape heat setting step, and the curing step can be performed by an automated operation.
[0033]
As shown in FIGS. 10 (a) to 10 (d), the automation operation is performed by using a laterally movable wrinkle forming type and a curing type two-group connection type and a pressure core type movable up and down. be able to.
According to FIGS. 10A to 10D, the mold in which the ridge forming mold 12 and the curing mold 23 connected so as to be movable on the transport device 13 are translated according to each step. It is shown.
As shown in the figure, the position of the pressure core mold is fixed and is a pressure position. In the case of a process that requires pressure treatment, either the ridge forming mold 12 or the curing mold 23 is moved to the pressure position.
[0034]
FIG. 10A shows the paper making process. Papermaking process,漉形molding 12 from a non-pressurized state is located on the right side,漉形molding 12 is moved to the pressure position in the pressing and drying process, to be pressed with a pressure core mold 21 It is shown.
FIG. 10 (c) shows the movement of the mold, in which the pulp mold forming intermediate S ″ is sucked and lifted by the pressure core mold 21 from the cocoon forming mold, and the thermosetting mold 12 is moved to the pressurizing position. Is shown. Further, FIG. 10 (d) shows that after the mold movement, the shape heat setting step and the curing step are performed by changing the conditions at the same position.
Thus, the automation of the three steps can be achieved by linking the parallel movement of the ridge forming mold 12 and the thermosetting mold 23 with the downward movement of the pressure core mold 21 in a predetermined manner.
[0035]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the examples.
In addition, the quality and performance of pulp molded products prepared in the examples and the like were evaluated by the following test methods.
[0036]
Water leakage resistance;
20 to 30 molded container prototypes were each filled with water, stored at room temperature, the residual amount of water was measured after 1 hour, and the leakage resistance was displayed as the time (hr) at which the residual amount of water appeared. .
[0037]
Moisture absorption resistance;
The molded container prototype is placed in a constant temperature and humidity standard at a humidity of 95% and a temperature of 70 ° C., and the weight is measured every 10 minutes. The ratio of the weight change to the original weight is continued until the weight change does not occur. The water absorption rate was taken as%.
[0038]
Example 1
A pulp pulp slurry containing 5% fiber content and a wood pulp slurry containing 5% fiber content are mixed at a weight ratio of 50:50, and the mixture is supplied to a filling bucket of a 30-liter mold and evacuated. After the thickness of the mold was made uniform, the water was instantaneously drained from the hole formed in the lower part of the mold for forming the bowl, and further sucked and sucked.
Next, a male pressure core mold that engages with the shape of the female mold forming mold was inserted into the recess of the mold forming mold from above, and the molded product was squeezed to squeeze out the remaining water. .
The molded product after squeezing is sucked and lifted with a pressure core mold from a mold, transferred to a curing mold, the mold temperature is set to 120 ° C., and the pressure core mold is used at a pressure of 0.1 MPa. And the shape of the molded product was fixed.
Next, the temperature of the mold was raised to 180 ° C., and pressed with a pressure core mold at a pressure of 0.2 MPa for 20 seconds to cure the cellulose fibers. After the curing treatment, the molded product was evaluated by the above test method, and the following results were obtained.
[0039]
Specific gravity: 0.71 g / cm3
Water leakage resistance (water resistance retention time): 180 hours or more
Moisture absorption resistance (moisture absorption rate): 10% or less When compared with the evaluation results of the comparative examples, the water leakage resistance and moisture absorption resistance were remarkably remarkable.
[0040]
Comparative Example 1
A pulp pulp slurry containing 5% fiber content and a wood pulp slurry containing 5% fiber content are mixed at a weight ratio of 50:50, and the mixture is supplied to a filling bucket of a 30-liter mold and evacuated. After the thickness of the mold was made uniform, the water was instantaneously drained from the hole formed in the lower part of the mold for forming the bowl, and further sucked and sucked.
Next, insert the male pressure core mold that engages with the shape of the female mold forming mold into the recess of the mold forming mold from the top, squeeze the molded product, and squeeze out the remaining moisture. did.
The molded product after pressing is sucked and lifted from the mold by a pressure core mold, transferred to a curing mold, the temperature of the mold is set to 120 ° C., and the pressure core mold is set at a pressure of 0.1 MPa. The shape of the molded product was fixed and finished.
[0041]
Specific gravity: 0.66 g / cm3
Water leakage resistance (water resistance retention time): Immediate liquid leakage
Hygroscopic resistance (moisture absorption rate): 27%
[0042]
【The invention's effect】
Since the present invention has the configuration described above, it is possible to prevent water leakage without blending additives and the like, and control of rigidity and hygroscopicity is possible. Manufacturing is possible.
[Brief description of the drawings]
FIG. 1 is a schematic view showing steps of a pulp cellulose molding method according to the present invention.
FIG. 2 is a perspective view showing an example of a form of a pulp mold molded body obtained by carrying out the present invention.
3 is a cross-sectional view of the pulp mold product of FIG. 2. FIG.
FIG. 4 is a schematic view showing an example of a paper making process in a pulp cellulose molding process according to the present invention.
FIG. 5 is an explanatory diagram showing an example of a paper making process in a pulp cellulose molding process according to the present invention.
FIG. 6 shows an example of a pressing / drying step in a pulp cellulose molding step according to the present invention.
FIG. 7 is a schematic view showing an example of a shape heat setting step in a pulp cellulose molding step according to the present invention.
FIG. 8 is a schematic view showing an example of a curing step in a pulp cellulose molding step according to the present invention.
FIG. 9 is a schematic view showing an example of a finishing process in a pulp cellulose molding process according to the present invention.
FIG. 10 is a schematic view showing an example of an automated operation of each step in the pulp cellulose molding step according to the present invention.
[Explanation of symbols]
A Papermaking process B Dehydration process C Squeezing / drying process D Shape heat setting process E Curing process F Molded product finishing process 1 Molded container 2 Inner surface 3 Outer surface 4 Flange 5 Side 11 Filling bucket 12 Saddle forming mold 121 Suction hole 14 Recess 15 Wrinkle-forming mold support 21 Pressurized core mold 22 Suction device 23 Curing mold 25 Curing mold support S Hydrous molded product S ′ Dry molded product S ″ Shape heat-fixed molded product S ′ ″ Cured molded product

Claims (5)

1) Supplying pulp slurry to a cocoon forming mold having a number of suction holes, dewatering from the cocoon forming mold, and placing a pulp mold forming intermediate having a shape corresponding to the shape of the cocoon forming mold on the cocoon forming mold A paper making process to be formed;
2) While holding the hydrous pulp mold molding intermediate obtained in the paper making step on the cocoon forming mold, press with a pressure core mold having a shape that engages with the shape of the cocoon forming mold, Squeezing and drying process to squeeze the remaining water,
3) The pulp mold molding intermediate having a moisture content of 10% or less obtained in the pressing / drying step is transferred to a curing mold having the same shape as the shape of the koji forming mold, and the pulp mold molding intermediate is A shape heat fixing step of pressing at a pressure of 100 MPa to 120 ° C .; pressing at 0.2 MPa or less and fixing the shape of the pulp mold intermediate;
4) The pulp mold molding intermediate obtained in the shape heat setting step is heated on the curing mold at a temperature of 150 ° C. to 180 ° C., and is pressurized at 0.2 Mpa to 0.3 Mpa by the pressure core mold. A pulp cellulose molding method for producing a pulp mold molded body comprising each step consisting of a curing step that is pressed with, wherein the water resistance of the pulp mold molded body is improved, and the moisture absorption is 10% or less. A pulp cellulose molding method characterized by comprising:   The pulp cellulose molding method according to claim 1, wherein the pulp slurry is a mixture of slurry of straw pulp and wood pulp.   The pulp cellulose molding method according to claim 1, wherein the wrinkle forming mold and the curing mold are female molds.   The pulp cellulose molding method according to claim 1, wherein the pressure core mold is a male mold.   The pulp cellulose molding method according to claim 1, wherein a specific gravity of the cured pulp mold molded body is 0.68 g / cm3 or more.

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