JPH0742100A - Production of pulp mold - Google Patents

Abstract

PURPOSE:To provide a method for producing pulp molds, intended to dramatically improve their production efficiency compared with conventional methods, esp. significantly shorten the drying time for pulp mold products from wet papermaking process, and also remove the shape strains thereof developed during the drying process. CONSTITUTION:A mold intermediate 7 after suction and dehydration by wet process via a papermaking mold 4 is subjected to hot pressing through a pair of male and female porous molds 8, 9 engaging with each other while exhausting the steam produced during heating and drying said mold intermediate, thus affording the objective pulp mold as the final product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pulp mold product such as a cushioning material for packaging by a wet method using a pulp material such as waste paper pulp, virgin halp, etc. The present invention relates to a method in which a molded product after dehydration is transferred to a pair of porous molds which are engaged with each other, and is dried while being heated in the molds to be a final product.

[0002]

2. Description of the Related Art The wet method is mainly used in the production of pulp mold products. In all of these methods, a fibrous laminate formed by suction dehydration through a papermaking mold to form a papermaking surface. After removing the object (hereinafter referred to as a mold intermediate) from the papermaking mold and introducing it into a preheating furnace to dry it, it is again introduced into a non-aeration type molding die in which male and female engage with each other, and heating, By pressurizing, a pulp mold product as a final product is obtained.

There are two types of papermaking used in the conventional wet papermaking method, one of which is a papermaking method in which a wire mesh is stretched on the surface of a die substrate made of an aluminum casting. Another method is to use a porous mold having fine voids instead of the wire net. In any of the methods, after transferring the mold intermediate obtained in the papermaking process to a mold that engages with the papermaking mold, the mold intermediate is removed from the mold and introduced into a heating furnace. After drying, the product is transferred to a hot mold again, where the final product is obtained while correcting the shape.

The problem with the above conventional method is that the productivity cannot be improved unless it takes time to obtain a product and the improvement is required. In particular, since the method is a method in which the dehydrated mold intermediate is once put in a heating furnace to be pre-dried and then again introduced into the heating mold to be heated and dried. It was not possible to completely remove the distortion, and there were many problems in terms of dimensional accuracy.

For this, a method is employed in which the dehydrated mold intermediate body is once floated from the wire netting and then heated air is blown between the wire netting and the intermediate material to dry it (Japanese Patent Laid-Open No. 4-194100). The problem that air does not escape from the aluminum substrate is still unsolved, and the problem of product distortion remains the same.

[0006]

SUMMARY OF THE INVENTION Here, the present invention is a porous metal in which a mold intermediate made by a wet method is incorporated with a pair of male and female molds, that is, a heater in the final finishing step. Mold or a porous metal mold capable of introducing heated air from the outside, and the porous metal mold is composed of a male and female pair so that they can be engaged with each other. It is intended to propose a method in which a cold-molded intermediate is transferred and dried while suctioning or degassing in the mold to obtain a pulp mold product as a final product. In other words, the present invention is intended to solve the above-mentioned problems by using a porous mold in the process of obtaining the final product and performing drying using heated air on the mold. is there.

[0007] More specifically, the mold intermediate after being sucked and dehydrated by a wet method through a papermaking machine is hot while exhausting steam generated during heating and drying through a porous mold in which male and female engage with each other. The present invention relates to a method for producing a pulp mold, which comprises pressing and thereby producing a pulp mold product as a final product, wherein one or both of a pair of porous molds used when carrying out this method is heated. -It does not matter if you have a built-in battery. In short, according to the present invention, the mold intermediate after suction and dehydration is hot-pressed through a porous mold in which males and females engage with each other while exhausting water vapor generated during drying, whereby the final product is obtained. This is a method for producing a pulp mold, which is characterized by producing a pulp mold product as a product.

The preferred embodiments of the present invention will be briefly described below. A. The mold is taken out by the papermaking process, and while the mold intermediate is attached to the papermaking process, the takeup is placed on the mold intermediate, and the product is sucked under pressure to be dehydrated, b. The mold is transferred to a mold and transferred to a hot pressing male mold made of a heat-resistant porous mold and set on it. C. At the same time as covering the mold intermediate with a female mold for hot pressing made of a heat-resistant porous mold and heating and pressurizing to dry the intermediate, d. The mold with the intermediate removed can be put back into operation and used to repeat paper making.

At least one of the paper making mold and the take-up mold is preferably constructed of a heat-resistant porous mold similar to the male and female molds for hot pressing. By the way, it is preferable that both of the papermaking mold and the take-up mold, or at least one of them, has a structure capable of supplying heated air.

The mold used as the mold of the present invention is a conventionally used aluminum cast product, usually 2 m.
Although an aluminum cast product formed by perforating m diameter ventilation holes at a rate of 1 may be used, it is advantageous to use this as a porous mold, preferably a resin molded product made of epoxy resin. is there. This is because it is possible to use a mold manufacturing master common to the above-described hot pressing mold, so that the manufacturing cost can be greatly reduced.

[0011] To reiterate, if either the paper making mold or the take-up mold is made into a porous mold having a structure in which heated air can be used, predrying can be carried out in the paper making process. This is further advantageous in that the burden of the above can be reduced. It should be noted that any of the above-mentioned molds is required to have heat resistance, drainage resistance and compression resistance strength, because pressurization and suction are indispensable for dehydration in the paper making process, and heating is also required. Since heated air of 100 to 200 ° C. is used at the time of drying, it is also necessary to have a structure capable of withstanding it.

By the way, the water content of the mold intermediate after suction dehydration is about 75%, and the water content of the mold intermediate when starting the hot pressing is about 60% after the predrying is completed. However, the lower limit value can be arbitrarily set in view of the ease of molding the molded product. Metals, ceramics, etc. can be used for the above-mentioned porous mold. For example, a metal mold can be made by itself such as Sumitomo Electric's porous metal (Celmet), or glass beads are bonded to each other with an adhesive. You may make it adhere | attach and form a metal mold in a mold.

Furthermore, the ratio of the number of molds used in the paper making process of the mold to the number of molds used in the hot pressing process is arbitrary, but as an example, it is 1: 2 to 1: 3. Is good.

The present invention will be specifically described below with reference to an embodiment shown in the drawings. 1A to 1B are schematic views conceptually showing a molding machine, and in the figure, reference numeral 1 is a pulp suspension storage tank having a pulp concentration adjusted to about 1 to 2%. On the other hand, the rotary suction device 2 having the following configuration is combined. The device 2 is mounted radially,
It is composed of a plurality of suction arms 3 that rotate at a constant speed, and a papermaking mold 4 attached to the tip of the suction arms. Rotate and
The structure is such that the pulp liquid is adsorbed on the surface of the papermaking mold 11 via the arm 3 during immersion (see FIG. 1B). In addition, the above
As shown in FIG. 1A, the rotary suction device 2 is also provided with a rotary transfer device 5, and a take-up die 6 attached to the tip of the rotary device 5 has a constant time interval. It is configured to be engaged with the papermaking mold 4 attached to the previous suction device.

As described above, the papermaking mold 4 may be a conventional wire mesh type or the above-mentioned porous metal mold. In short, what is required is a papermaking mold of a type which can be manufactured by a wet suction method. May be. The same applies to the take-up die 6, as long as the mold intermediate product 7 produced in the paper-making die 4 can be removed from the paper-making die 4 and transferred.

The relationship between the papermaking mold 4 and the take-up mold 6 will be described below with reference to FIG. Both the papermaking mold 4 and the take-up mold 6 have drainage property and air permeability, and the pulp liquid containing water is sucked and dehydrated under a negative pressure to form a mold intermediate 7 along the surface of the mold. Carry out the action of causing. Further, when the intermediate body 7 is removed from the mold, pressure air is blown out from the mold to perform so-called blowout. Therefore, between any of the plurality of papermaking dies 4 and the take-up dies 6, the respective dies are individually supplied via the rotary shaft portion of the suction device 2 and the transfer device 5 which are collecting them. -It is connected to a source (both of which are not shown), and the above operation is performed by switching between intake air and exhaust air through an appropriate valve mechanism.

That is, as shown in (1) to (2) of FIG. 2, the mold intermediate 7 produced by the papermaking mold 4 is transferred to the take-up mold 6 fitted to the papermaking mold 4 to further suck and dehydrate water.
The water content in this case is approximately 75% as described above.
Next, as shown in the same figure, the dehydrated mold intermediate 7 is transferred to the male mold 8 for hot pressing, which is a porous mold, through the above-mentioned mold 6. The molded intermediate body 7 transferred to the male mold 8 is, as shown in and of FIG.
The product is heated and pressurized by the so as to obtain a predetermined product.

It should be noted that an electric heating heater 10 can be built in the hot press 8 so that the male and female molds can be heated, or the heater can be built-in without the built-in heater. The entire mold may be housed in a furnace in which hot air is introduced so that the hot air can pass through the mold.

A more specific embodiment will be described below.

[0020]

Example 1 a. As the papermaking mold 4, a conventional aluminum casting product was used, and a 40-mesh wire net was stretched around this mold. Using this papermaking machine, a 2 mm-thick mold intermediate 7 (pulp sheet) was prepared from a pulp slurry having a concentration of 1%. An epoxy resin molded product was used as the mold 6. This mold is placed on the mold intermediate body 7 described above and dehydrated under pressure. The water content of the sheet at this time was 75%.

B. The pulp sheet is peeled off from the papermaking mold 6, and in place thereof, a male mold 8 for hot press having the same size as the papermaking mold 4 and having the following constitution is prepared, and the intermediate 7 is transferred onto this one. Further, a female mold 9 for heat press of the same mold as the above-mentioned mold is covered from above to heat and pressurize. That is, as an example, the heater 10 mounted in the male die 8 for hot pressing is operated, or the male die 8 and female die 9 for hot pressing are entirely housed in a furnace 11 as shown in FIG. Above, the mold intermediate in a state of being clamped between the male mold 8 and the female mold 9 is heated and dried. In other words, heated air of about 180 ° C. is blown through the male and female press dies, and the air is sucked from the female dies to obtain the mold intermediate 7
Is dried to obtain the desired product.

The specifications of the male mold for hot pressing will be described. In the above embodiment, the constituent materials are:
A glass bead having a diameter of 0.3 mm laminated on an aluminum mold using an epoxy adhesive was used. As the female mold, one having the same structure was used. While using the male mold 8 and the female mold 9 which are the porous molds having such a constitution, while pressurizing and inhaling (negative pressure -600 mmHg)
As a result of the drying, a strain-free pulp mold product was obtained in a short time (see the graph in FIG. 4).

[0023]

[Example 2] A product was manufactured in exactly the same manner as in Example 1 except that the papermaking mold and the die of Example 1 had the same structure as the porous mold for hot pressing of Example 1. Obtained. That is, after dehydration under pressure between the paper making mold and the take-up mold, heated air is blown from the paper making mold and sucked from the take-up mold to be pre-dried (water content 60
%). That is, as shown in FIG. 3, the mold 6 in which the mold intermediate 7 is mounted is housed in the drying furnace 11 and hot air (1 per second) heated to about 180 ° C. is blown therein. And by using the fine voids in the porous mold 6, -6
Suction with a negative pressure of about 00 mmHg. If you do this
The initial moisture content of the cold intermediate 7 is reduced from 75% to 60%. In this case, the time required to obtain the product was about 1.5 minutes in Example 1, but it is reduced to about 1 minute.

[0024]

As shown in FIG. 4, according to the present invention, the productivity is greatly improved as compared with the conventional method. That is, the process proceeds such that hot pressing is performed in a state where the water content of the mold intermediate is sufficient, in other words, a water content of about 60 to 75%, and drying is performed while maintaining the state. Therefore, not only is it easy to press, but since it contains appropriate water, the molding effect is high, and a product without distortion can be obtained in a short time. As is well known, in order to enhance the molding effect in the conventional method, it was necessary to impregnate water again, but there is an effect of eliminating such a defect and improving productivity. Furthermore, it has a significant effect in that the time required for drying can be greatly shortened as compared with the time required for making a molded product.

FIG. 4 is a graph showing the change in water content of the mold intermediate with time as the horizontal axis. The symbol a shows the change in Example 2 and the same b shows the change in Example 1. The conventional method required about 20 minutes conventionally as shown in the same C, but according to the present invention, it can be shortened to about 1 to 1.5 minutes, and further, when molding a molded product. The most efficient area (area indicated by the symbol α in the figure), that is, the average moisture 25 to 35
It is extremely advantageous in that hot pressing is performed in the area of%.

[Brief description of drawings]

FIG. 1A is a schematic diagram for explaining a wet papermaking method for a pulp mold product, and B in FIG. 1 is a side view showing a relationship between a papermaking mold and a storage tank.

FIG. 2 is a schematic view for sequentially explaining the processing steps of the present invention.

FIG. 3 is a cross-sectional view when a mold intermediate body transferred to a mold is introduced into a preliminary drying furnace.

FIG. 4 is a graph showing a change in water content of a mold intermediate in comparison between the present method and a conventional method, in which the vertical axis represents water and the horizontal axis represents time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Storage tank 2 Rotary type suction device 3 Suction arm 4 Paper making type 5 Rotary type transfer device 6 Taking type 7 Mold intermediate (fiber deposit) 8 Male type for heat press 9 Female type for heat press 10 Electric heating type heater 11 Heating furnace 12 Heating air introduction hole

Claims (5)

[Claims] 1. A hot press while exhausting steam generated at the time of heating and drying a mold intermediate after being sucked and dehydrated by a wet method through a papermaking mold, through a porous mold in which male and female engage with each other. And thereby producing a pulp mold product as a final product. 2. The method for producing a pulp mold according to claim 1, wherein a heater is built in one or both of the porous molds for male and female engaging with each other. 3. A. Using a paper mold and a mold that engage with each other, after the mold intermediate is made by the paper mold, the mold is stacked on the mold intermediate and pressed while the intermediate is attached to the paper mold. While dehydrating, b. After dehydration, the mold intermediate is transferred to a mold, and then transferred to a hot pressing male mold made of a heat resistant porous mold and set on it. C. At the same time as covering the mold intermediate with a female mold for hot pressing made of a heat-resistant porous mold and heating and pressing to dry the mold intermediate, d. The method for producing a pulp mold is one in which the mold with the mold intermediate removed is returned to its original state, reused for circulation, and paper making is repeated. 4. The method for producing a pulp mold according to claim 1, wherein the hot air is heated by supplying heated air from either male or female and sucking it by the other. 5. A method for producing a pulp mold, wherein at least one of a papermaking mold and a take-up mold is composed of a porous mold having heat resistance similar to that of a male and female mold for hot pressing.