JPH10227000A - Method for manufacturing pulp mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain a pulp mold useful as a packaging material, etc., by repeating the operations of opening and tightly closing a pair of top and bottom hot-press forces to thereby significantly reduce the drying time and improve the productivity. SOLUTION: This method comprises a preliminary drying process of drying, through suction dehydration, an intermediate molding M' which has been obtained by skimming and causing the pulp content in a pulp slurry 2 to be adsorbed on a molding tool A, a releasing process of releasing the intermediate molding M' from the molding tool A and transferring the same onto a bottom force B2 for hot-press, and a hot-press/drying process of clamping a pair of top and bottom forces B1 , B2 constituting the hot-press mold B to dry the intermediate molding M' while vacuum evacuating the air. In the hot-press/drying process, the operations of instantaneously opening the pair of top and bottom forces B1 , B2 of the hot-press mold B and of clamping and tightly closing both of the top and bottom forces B1 , B2 again are repeated to obtain the pulp mold M. The evacuation pressure is preferably -400 to -600mmH while the heating temperature is 150 to 250 deg.C, and the duration of opening the bottom force B2 and the top force B1 is preferably 0.5 to 1s.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a pulp mold, which comprises a step of hot-pressing and drying an intermediate molded product obtained by extracting a pulp component in a pulp slurry and forming the molded product under vacuum, and further comprising: More specifically, the present invention relates to a method of manufacturing a pulp mold in which the efficiency of hot press drying is increased to improve productivity.

[0002]

2. Description of the Related Art When a predetermined product or the like is transported, the product or the like is packed in a state where a part or all of the product is fitted by a packing material having a recess corresponding to the shape of the product or the like. ing. Since such a packing material is usually made of a material such as expanded polystyrene, disposal of the packing material becomes difficult.

On the other hand, for the purpose of effective use of recovered resources and the like, a packing material is manufactured from waste paper pulp such as corrugated cardboard or newsprint, and such a packing material is called a pulp mold. Have been. Such a pulp mold usually has a molding surface having a shape corresponding to the pulp mold, and further uses a molding die provided with a large number of suction holes opening in the molding surface. The pulp component is formed by adsorbing the pulp component on the molding surface by continuing suction from the suction hole while being immersed in the pulp, and by continuing suction outside the pulp slurry, the adsorbed pulp component is dehydrated on the mold. After the water content is sufficient to maintain the shape, it is released from the mold, and dried by hot air in a drying furnace,
Manufactured.

However, if an intermediate molded product of the pulp mold released from the molding die is directly dried in a drying furnace, the product may not be able to fit into the molded pulp mold due to heat shrinkage. In addition, it requires a long drying time. In addition, since traces of suction holes provided in the molding die remain on the surface of the molded pulp mold, when the pulp mold is required to have high aesthetics, such as a decorative box, the above-mentioned drying method is used. The method cannot be adopted.

[0005] Therefore, in order to increase the drying efficiency of the pulp mold and enhance the aesthetics after the drying, a method of drying the pulp mold by hot pressing has been implemented. In order to carry out this drying method, a hot press mold composed of a pair of upper and lower molds is used. In order to further enhance the drying efficiency, there is a method in which hot pressing is performed while vacuum suction is performed from one of the pair of molds. In this method, the number of suction holes provided in the hot press mold is limited in order to secure a certain cosmetic property in the molded pulp mold (the minimum pitch of the suction holes that can be pierced is about 10 mm). There is a problem that the steam generated by heating cannot be sufficiently absorbed, the surface of the manufactured pulp mold becomes rough, and the drying time cannot be reduced as expected. In addition, if the number of suction holes provided in the hot press mold is increased as much as possible in order to increase absorption of generated steam, the cost of manufacturing the hot press mold increases in accordance with the number of suction holes. .

For this reason, JP-A-6-158600 and JP-A-8-4920
In No. 0, it has been proposed to shorten the drying time by efficiently absorbing generated steam when using a hot press mold having a suction hole. In the former method, a wire mesh is attached to the press surface of the hot press mold, and a gap is positively formed between the intermediate molded product of the pulp mold and the press surface of the hot press mold. It is intended to be easily sucked. In the latter case, in addition to the use of the wire netting, a slit or the like which communicates with the suction hole is provided in the hot press mold itself to make it easier to suck generated steam. However, providing a slit or the like in the hot press mold itself has a problem that the structure of the mold is complicated and the manufacturing cost is increased.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to efficiently absorb generated steam in the case of drying an intermediate molded product of a pulp mold by using a conventional hot press having suction holes. By shortening the drying time, the production cycle time of the product is shortened, and the productivity is increased.

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention relates to a preparatory method for drying an intermediate molded product of a pulp mold obtained by removing a pulp component from a pulp slurry and adsorbing the pulp component on a molding die by suction dehydration. A drying step, a mold release step of releasing the intermediate molded article from the molding die, and transferring the intermediate molded article to a lower mold for hot press, and clamping a pair of upper and lower molds constituting the hot press mold, A hot press drying step of drying the intermediate molded article by hot pressing while evacuating the vacuum, wherein in the hot press drying step, the pair of upper and lower It is characterized in that the operation of opening the mold and the operation of closing and sealing both molds again are repeated.

In the hot press drying step, when a pair of upper and lower molds constituting the hot press mold is momentarily opened slightly while the intermediate molded product of the pulp mold being hot pressed is sufficiently heated, the intermediate molding is performed. While the article remains vacuum-adsorbed to the upper mold, a vent is formed on the back side of the intermediate molded article, and the air sucked from the back side passes through the inside of the intermediate molded article while passing through the interior. The steam is taken in, and the internal steam and the air are exhausted together. The time for opening both molds is extremely short so that the heat of the intermediate molded product of the pulp mold is not deprived. Immediately thereafter, the molds are clamped again and hot press drying is continued. In this way, while instantly opening the upper and lower pair of hot press molds,
The internal steam contained in the intermediate molded product is efficiently removed, and when the molds of both molds are restarted, the drying time of the intermediate molded product is greatly reduced because the hot press drying is continued. .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples. FIG. 1 is a schematic view showing a method of manufacturing a pulp mold according to the present invention, FIG. 2 is a cross-sectional view of a molding die A used for carrying out the present invention, and FIG. FIG. 4 is a cross-sectional view taken along the line XX of FIG. 2 mainly showing the arrangement of the openings 8a, and FIG.
FIG. 5 is a cross-sectional view of the hot press die B, and FIG. 5 is a schematic view showing a hot press drying step which is a characteristic step of the present invention. First, a schematic configuration of a pulp mold manufacturing apparatus for carrying out the present invention will be described. In FIG. 1, a raw material tank 1
Inside, for example, pulp slurry 2, which is a forming raw material obtained by dissolving used paper such as corrugated cardboard or newsprint at a predetermined concentration (about 0.7%) in water, is stored. Immediately above the raw material tank 1, a molding die A is provided so as to be vertically movable so that it can be immersed in the pulp slurry 2 in the raw material tank 1 and can be completely escaped. As shown in FIGS. 2 and 3, the molding die A is made of a pulp mold M in which the pulp component in the pulp slurry 2 is taken out and adsorbed on a molding surface 3 formed in a concave shape on its lower surface. The intermediate molded product M 'is preliminarily dried by vacuum dehydration. This mold A
Are integrally attached to the mounting frame F, and a space formed between the molding die A and the mounting frame F is a suction space 4. The molding die A is provided with countless suction holes 5 opened in the molding surface 3, and the suction space 4 communicates with the atmosphere via the suction holes 5. A metal net 6 is laid on the molding surface 3 of the mold A over the entire surface. By laying the wire net 6, a gap is formed between the molding surface 3 and the intermediate molded product M 'of the pulp mold M adsorbed on the molding surface 3, and the suction force applied to the intermediate molded product M' is reduced. The range is widened, and the effect of preliminary drying by vacuum dehydration is enhanced.

A suction cylinder 7 is mounted on the mounting frame F on which the mold A is mounted so as to be substantially vertical.
Its lower end is inserted into the suction space 4. A large number of L-shaped branch pipes 8 are integrally connected to the lower end of the suction tube 7, and a suction opening 8 a at the lower end of each branch pipe 8 is
An annular flat surface 9 formed in an annular shape at the lowest position of the upper surface of the mold A is opposed to and opposed to the annular flat surface 9. For this reason, when a vacuum pump (not shown) or the like connected to the suction cylinder 7 is operated, suction force is applied to the countless suction holes 5 via the suction space 4, so that the molding surface 3 of the mold A is formed. When the suction force is applied to the innumerable suction holes 5 in a state where the whole of the pulp is immersed in the pulp slurry 2, the pulp component in the pulp slurry 2 is adsorbed on the molding surface 3. A check valve 10 is attached to the lower end of each branch pipe 8 of the suction cylinder 7, and a mold A
When the intermediate molded product M ′ of the pulp mold M adsorbed on the molding surface 3 is preliminarily dried by vacuum dehydration, the water sucked into the suction tube 7 flows backward, is returned into the suction space 4, and It prevents adhesion to the intermediate molded product M '.

A first hot press die B comprising a pair of upper and lower dies B ₁ and B ₂ is disposed on the side of the forming die A at the rising end position. The first hot press mold B is for hot-pressing and drying an intermediate molded product M ′ of the pulp mold M preliminarily dried by the mold A while sucking the vacuum. The first hot press die B has the same structure as a known hot press die, and as shown in FIG.
_1, directly above the lower mold B ₂ of the normal position when performing hot pressing dried, with being vertically movably disposed relative to the lower die B _2, lower die B ₂ is a hot press drying It is provided so as to be able to move horizontally at two positions: a regular position where the operation is performed, and a position immediately below the mold A at the rising end position.

Each of the pressing surfaces 11 of the pair of upper and lower molds B ₁ and B ₂
Reference numeral 12 follows the shape of the front and back surfaces of the pulp mold M to be molded. As shown in FIG. 4, the upper die B ₁ has substantially the same structure as the molding die A, is integrally attached to a mounting frame F ′, and is provided between the upper die B ₁ and the mounting frame F ′. Is formed as a suction space 13, and a suction tube 14 is attached to the mounting frame F 'so as to be substantially vertical.
3 is inserted inside. In addition, the upper die B ₁ is provided with countless suction holes 15 opened in the press surface 11,
The suction space 13 communicates with the atmosphere via the suction hole 15. Furthermore, the press surface 11 of the upper die B ₁ represents, wire mesh 16 is laid over the entire surface. By laying the wire net 16, a gap is formed between the press surface 11 and the intermediate molded product M 'of the pulp mold M adsorbed on the press surface, and the suction force applied to the intermediate molded product M' is reduced. The range is widened, and the drying effect by the hot press is enhanced.

On the other hand, as shown in FIG. 4, the lower mold B ₂ has a solid structure different from the upper mold B _1, and has an appropriate number of ventilation holes opened on the mirror-finished press surface 12. 1
A heater 7 such as a far-infrared heater for heating the entire mold is provided at the lower end thereof.
Reference numeral 8 denotes a structure provided inside. The suction holes 5, 15 and the ventilation holes 17 shown in FIGS. 2 and 4 are only a part of the whole.

[0015] The pulp mold M is formed using the above-described apparatus in the following manner. In FIG. 1, when the mold A is lowered and the entire molding surface 3 on the lower surface is immersed in the raw material tank 1 for only 1 to 3 seconds, the suction holes 5 formed in the molding surface 3 are sucked. Due to the air flow, only the pulp component in the pulp slurry 2 is taken out and adsorbed on the molding surface 3 with a thickness of 1 to 2 mm. 2. Raise the liquid level above 2 and return to the normal position. In this state,
When the vacuum suction is continued, the intermediate molded product M ′ of the pulp mold M adsorbed on the molding surface 3 is continuously dehydrated by suction.
This suction dehydration is performed so that the water content (68 to 75%) of the intermediate mold M 'can be maintained on the mold A.
Dehydration is continued (preliminary drying step).

Next, as shown by a two-dot chain line in FIG.
The lower mold B ₂ of the first hot press type B, and after being horizontally moved to just below the mold A having adsorbed said intermediate molded article M ',
Lowers the forming die A, after the die matching state with respect to the lower mold B _2, when releasing the suction force that span the molding surface 3 of the mold A, pulp mold, which is dehydrated to the water content The intermediate molded product M ′ of M is the lower die B of the first hot press die B.
Transferred to ₂ . Thereafter, the lower die B of the first hot press die B on which the intermediate molded product M ′ has been transferred to its own press surface 12.
₂ and is horizontally moved, back to the normal position is directly below the upper die B ₁ (transfer step).

The lower mold B ₂ of the first hot press mold B to which the intermediate molded article M ′ has been transferred and returned to the normal position is heated to a temperature described later by a heater 18 provided therein. lower die B _2, by the upper die B ₁ was lowered from directly above its is mold clamping, the intermediate molded article M 'is hot press space formed between the pair of upper and lower mold B _1, B ₂ It is confined inside and hot pressed. Upper die B ₁ which is clamping against the lower die B ₂ is heated by heat conduction from the lower die B _2.
The heat pressing condition, the intermediate molded article M 'moisture internal becomes steam by a suction force that extends in the press surface 11 of the upper die B _1, the intermediate molded article M' inside vapor is evacuated. Then, as shown in FIG. 5 (a), after the pair of upper and lower molds B ₁ and B ₂ are sufficiently heated and the moisture inside the intermediate molded product M ′ becomes steam, As shown in (1), when the pair of dies B ₁ and B ₂ are momentarily opened slightly, the intermediate molded product M ′ is sucked from below under the vacuum suction of the upper die B ₁ . While the air passes through the inside of the intermediate molded article M ′, the inside steam is taken in, and the steam and the air are sucked and exhausted together. The time for opening the pair of dies B ₁ and B ₂ is an extremely short time such that the heat of the intermediate molded product M ′ is not taken away, and the time for clamping and hot pressing is about 5 seconds. In the case of (1), it is about 0.5 second, and when the hot pressing time is about 10 seconds, it is about 1 second, and generally, 0.5 to 1 second is preferable. After that, the same figure (c)
As shown in (2), the pair of dies B ₁ and B ₂ is closed again, and hot press drying is continued. By repeating the operation of clamping and hot pressing and the operation of slightly opening the pair of dies B ₁ and B ₂ , the intermediate molded product M ′ is hot pressed and dried until it reaches the set water content ( Hot press drying process).

By opening the pair of dies B ₁ and B ₂ , the gap D formed between the lower surface of the intermediate molded product M ′ and the press surface 12 of the lower die B ₂ is preferably 0.1 mm. It is more preferably 0.1 to 0.5 mm. When the gap D is 0.1 mm or less, the effect of the air suction is poor,
If it is 5 mm or more, the amount of suction air is too large, and the intermediate molded product M 'is excessively cooled. The heating temperature of the pair of molds B ₁ and B ₂ by the heater 18 is preferably 100 ° C. or higher, more preferably 150 to 250 ° C.
° C. Further, the degree of vacuum of the hot press space formed between the pair of dies B ₁ and B ₂ is preferably (−400) mmHg.
Or less, more preferably (−450) to (−65)
0) It is mmHg. A comparison of the drying time of the intermediate molded product M ′ between the conventional continuous hot press drying method and the intermittent hot press drying method according to the present invention shows that the conventional method required 90 seconds, but reduced to 60 seconds. Was done. As a result, the cycle time of manufacturing the pulp mold M can be significantly reduced while using the conventional first hot press die B having the same structure.

When the pulp mold M is to be mirror-finished, as shown in the schematic diagram of FIG.
In addition to the hot press die B, a second hot press die C having substantially the same structure as this is used. Each of the press surfaces 21 and 2 provided on the upper die C ₁ and the lower die C ₂ constituting the second hot press die C
2 are all be mirror-finished, the pressing surface 21 of the upper mold C _1, as the first heat-press type B, wire mesh is not laid. Also, the upper die C constituting the second hot press die C
With numerous suction holes (not shown) is provided in the _1, on its lower mold C _2, an appropriate number of vent holes (not shown) is provided. The interval between the molding spaces formed between the pair of upper and lower dies C ₁ and C ₂ of the second hot press die C is slightly smaller than that of the first hot press die B. Also,
The lower die C _2, a heater (not shown) is furnished, a pair of upper and lower mold C _1, C ₂ of the movement of the second hot press type C is a pair of upper and lower mold of the first hot press type B It is the same as B ₁ and B ₂ . In FIG. 6, 23 denotes a suction tube provided in the upper mold C _1.

When the pulp mold M is a decorative box, a high-end packaging box, or the like, and high cosmetics are required, the drying time by the first hot press mold B is set shorter than the above. 'in the water content is higher than the state of the intermediate molded article M' intermediate product M was allowed to transfer to the lower die C ₂ of the second hot press types C, for thermal press drying a second time. Both the front and back surfaces of the intermediate molded product M 'are in direct contact with the press surfaces 21 and 22 of the mirror-finished second hot press die C, and are further hot pressed. The traces of wire mesh remaining on the surface are eliminated, and the front and back surfaces are mirror-finished (mirror finishing process).

[0021]

According to the present invention, in manufacturing a pulp mold, in a hot press drying step, an operation of instantly opening a pair of upper and lower molds of a hot press mold and an operation of clamping and sealing both molds again. By repeating the intermittent hot press drying method, the steam contained in the intermediate molded product during drying is efficiently removed, so that the drying time of the pulp mold can be greatly reduced. Thereby, the cycle time for manufacturing the pulp mold can be shortened, and the productivity is improved.

Further, since the present invention can use a conventional hot press mold as it is, it can be implemented with little new capital investment.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for producing a pulp mold according to the present invention.

FIG. 2 is a cross-sectional view of a mold A used for carrying out the present invention.

FIG. 3 is a sectional view taken along line XX of FIG. 2, mainly showing the arrangement of a suction opening 8a of a suction tube 7.

FIG. 4 is a sectional view of a first hot press die B used for carrying out the present invention.

FIG. 5 is a schematic view showing a hot press drying step which is a characteristic step of the present invention.

FIG. 6 is a schematic view showing a method for producing a pulp mold according to the present invention including a mirror finishing step.

[Explanation of symbols]

A: mold B: first hot press type B _1: the first hot press mold of the upper mold B _2: a lower mold of the first hot press type C: second hot press type D: first hot press type vertical pair M: Pulp mold M ': Intermediate molded product of pulp mold 2: Pulp slurry

Claims (4)

[Claims] 1. A pre-drying step in which an intermediate molded product of a pulp mold in which pulp components in a pulp slurry are removed and adsorbed on a molding die is dried by suction dehydration, and the intermediate molded product is released from the molding die. Then, a mold release step of transferring to a lower mold for hot pressing, and clamping of a pair of upper and lower molds constituting the hot press mold, hot pressing while evacuating, and drying the intermediate molded product. It is a manufacturing method of a pulp mold including a hot press drying step, wherein in the hot press drying step, an operation of instantly opening a pair of upper and lower molds of the hot press mold, and closing and sealing both molds again A method for producing a pulp mold, characterized by repeating the above steps. 2. An exhaust pressure in the hot press drying step is (−400) to (−600) mmHg, a heating temperature is 150 to 250 ° C., and a lower mold for the hot press is used. The method for producing a pulp mold according to claim 1, wherein a time for opening between the upper mold and the upper mold is 0.5 to 1 second. 3. A gap provided by temporarily opening a lower mold and an upper mold for the hot press in the hot press drying step, wherein the gap is 0.1 mm or more. 2. The method for producing a pulp mold according to 1. 4. The pulp mold manufacturing method according to claim 1, further comprising a mirror finishing step of mirror finishing an intermediate product of the pulp mold by another hot press mold after the hot press drying step. Method.