JP3129056B2 - Method and apparatus for molding fibrous molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pulp obtained from used newspaper collected for the purpose of recycling resources, other synthetic pulp,
The present invention relates to a molding method and a molding apparatus for producing a fibrous molded product from an inorganic fibrous material or the like as a raw material.

[0002]

2. Description of the Related Art In recent years, for the purpose of recycling resources, molded articles of various packing materials such as egg containers have been manufactured using pulp obtained by pulping newspaper waste paper or the like as a raw material. Here, a conventional method for forming a pulp molded product will be described. First, a used paper is disaggregated and dispersed in water to form a pulp suspension, and then the pulp suspension is screened. After being supplied to the filtration mold, a pulp deposition tank is formed on a screen by a suction dehydration operation, formed into a desired shape by a subsequent compression dehydration operation, and the molded product taken out from the molding die is sufficiently dried by a drying furnace or the like. I try to get the product dry. Further, as an example of a filtration mold used for molding this pulp molded article,
For example, there is a molding die disclosed in JP-A-57-71500.

[0003] As raw materials for molded articles produced by the above-mentioned method, in addition to various fibrous materials such as natural fibers, synthetic fibers and inorganic fibers other than the above-mentioned used newspaper pulp, powders such as gypsum and cement are used. A molded article can also be produced from the powder suspension using a body.

[0004]

However, the conventional molding method described above has the following disadvantages in terms of productivity and manufacturing cost. As an example, used newspaper is disintegrated in water to prepare a pulp suspension having a pulp dry matter concentration of 1.5%, and then this pulp suspension is fed onto a screen provided in a filter mold, and then the screen is screened. The pulp suspension is sucked and dehydrated at a vacuum pressure of about 400 mmHg from behind to form a pulp deposit layer on the cavity surface of the mold.
When pressed under a molding pressure of Kg / cm ² for about 10 seconds, a pulp molded product having a thickness of about 3 mm and a water content of 78% by weight (pulp dry product 1)
A water content of 3.6 kg per kg was obtained. Next, the pulp molded article was dried in a drying furnace until the water content became 15%. The electric energy required for this drying step was 2.2 KWH per 1 kg of dry pulp. Moreover, since the molded article produced in this way suffered large distortion and deformation in the drying step, the molded article was used as a post-treatment for correcting the distortion and deformation of the molded article and adjusting the shape. It was necessary to re-form in a molding die of the same shape again.

As described above, in the conventional molding method, a large amount of power needs to be supplied and consumed in a drying step performed after molding, and a large distortion and deformation are caused in a molded article having a complicated shape due to uneven drying. In order to correct the deformation, post-processing of re-molding in a molding die is required, which lowers productivity and increases production cost. The present invention has been made in view of the above points, and an object of the present invention is to solve the above-mentioned problems, to sufficiently reduce the water content of a molded article in a molding step, and to suppress the consumption of electric power supplied to a subsequent drying step. In addition, a method for forming a fibrous molded product that enables high-quality molded products to be manufactured at low cost and high productivity, such as a process of correcting distortion and deformation of the molded product after drying is almost unnecessary, and a method of forming the same. An object of the present invention is to provide a molding apparatus used for the implementation.

[0006]

According to the present invention, there is provided, according to the present invention, a method of forming a fibrous molded article using a fibrous material dispersed and suspended in a liquid as a raw material. A suspension of the fibrous material is supplied to a molding die having a screen on the peripheral surface, and a fibrous material deposition layer is formed on the screen by suction dehydration from behind the screen. When a fibrous molded article is obtained by squeezing and dewatering the sedimentary layer by an operation, a fibrous molding used when applying a DC voltage to the fibrous material sedimentary layer for electroosmotic dehydration in the squeezing and dewatering step An article molding apparatus is configured as follows.

That is, a molding die comprising a female die having a screen also serving as an electrode on the inner peripheral surface of the cavity and having a drainage passage connected to the outside behind the screen, and a male die having a surface electrode. It is provided with a mold, a mold clamping press, a suction pump connected to the drainage passage, and a DC power supply connected between the female screen and the male surface electrode. ,

The male surface electrode is an insoluble electrode having high corrosion resistance.

[0009]

In the above-mentioned forming method and apparatus, the suspension of the fibrous material supplied on the screen disposed in the female mold of the forming die is suctioned and dehydrated to form a fibrous material deposition tank, and then formed. In the process of compressing and dewatering the deposited layer of fibrous material by the mold clamping operation, simultaneously applying a DC voltage to the deposition tank via the electrode, the deposition of the fibrous material sandwiched between the female mold and the male mold The layer is subjected to mechanical squeezing force and current flows. By the way, the fibrous material dispersed in the suspension is usually in a negatively charged state, and the surrounding liquid in contact with the fibrous material is charged to a positive polarity opposite to the surface charge of the fibrous material. I have. Therefore, when a voltage is applied from a DC power source with the screen electrode arranged in the female type being a negative electrode and the male surface electrode being a positive electrode, the liquid contained in the fibrous material deposited layer is caused by the action of electroosmosis. After moving to the screen electrode, it is drained from the mold to the outside through the screen by the suction pump. As a result, the moisture content of the fibrous molded article is significantly reduced as compared with the case where only mechanical compression dewatering is performed.

In addition, by providing an insoluble electrode made of platinum, iridium oxide or the like on the surface of the male mold, electrolytic corrosion and elution of the electrode due to application of a DC voltage are suppressed, and metal components are mixed into the molded product. Can be prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking a pulp molded article as an example. First, FIG. 1 shows a configuration of a molding apparatus, in which 1 is a female mold of a molding die,
2 is a male mold, 3 is a mold clamping press connected to the male mold 2, 4 is a raw material storage tank storing a pulp suspension 5, 6 is a pulp suspension supply tank containing the female mold 1, and 7 is a supply tank. DC power supply. Here, a cavity 1a corresponding to the shape of the molded product is formed in the male mold 1, and a screen 8 serving also as an electrode made of a wire mesh is laid over the entire inner peripheral area of the cavity 8. Further, behind the screen 8, a groove-shaped drain passage 1b communicating with the outside of the female die is formed, and a suction pump 9 is connected to the drain passage 1b by piping. On the other hand, the male mold 2 corresponding to the female mold 1 is made of bronze, for example, and the surface thereof is covered with an insoluble electrode 10 such as platinum or iridium oxide. An intake blower 11 is connected to the male mold 2 in connection with the opened intake hole 2a for taking out a molded product. 12 is male type 2
Is an electrical insulating material attached to the peripheral surface of the flange portion. The positive pole of the DC power source 7 is connected to the male mold 2, and the negative pole is connected to the screen 8, which is provided in the cavity of the female mold 1 and serves as an electrode. Further, between the raw material storage tank 4 and the supply tank 5, a suspension supply pipe 14 having a liquid sending pump 13 and a return valve 15
Are provided, and constitute a molding apparatus for producing a pulp molded article.

Next, a method of molding a pulp molded article by the molding apparatus having the above configuration will be described with reference to FIGS. 2 (a) and 2 (b). First, as shown in FIG. 1A, the female mold 1 is suspended in the supply tank 6 from the raw material storage tank 4 through the liquid supply pump 13 and the supply pipe 14 in a state where the male mold 2 is pulled up and the mold is opened. After the pulp suspension 5 is filled in the cavity of the male mold 1 by introducing the pulp suspension 5 to a level immersed in the liquid 5, the suction pump 9 leading to the drainage passage 1 b of the female mold 1 is started to perform suction dehydration. This allows
The liquid component of the suspension passes through the screen 8 and is drained to the outside, and the pulp of the fibrous material filtered by the screen 8 is deposited on the screen to form a pulp deposited layer 17.

Next, as shown in FIG.
After opening the excess pulp suspension 5 from the supply tank 6 to the raw material storage tank 4, the male mold 2 is lowered by the operation of the press 3 (see FIG. 1), and the molding die is clamped. A pressing force is applied to the mold to mechanically squeeze the pulp deposit layer 17 sandwiched between the screen 8 of the female mold 1 and the male mold 2, and at the same time, the DC power supply 7 applies a force between the screen 8 and the male mold 2. Voltage. As a result, a mechanical squeezing force due to the mold clamping operation and an electroosmotic action due to the application of a DC voltage are added to the pulp sedimentary layer 17, and the liquid content contained in the pulp sedimentary layer 17 passes through the screen 8 and passes through the screen 8. It flows out into the drainage path 1b of the mold 1 and is sucked and discharged to the outside through the suction pump 9. Further, a part of the liquid component evaporates due to Joule heat accompanying the electroosmosis. As a result, the pulp sedimentary layer 17 is formed into a cake with a low water content, and becomes a pulp molded product.

FIG. 3 is a schematic diagram showing the electroosmotic dehydration in the above, and shows the pulp sedimentary layer 17 in a wet state.
The fibrous material 17a is charged to the negative polarity, and the liquid portion 17b charged to the positive polarity moves to the screen 8, which also serves as the electrode, by the electroosmotic action caused by the application of the DC voltage, and then passes through the screen 8. Then, it is discharged outside by the suction pump 9.

When the above molding step is completed, the intake blower 11 is started to remove the pulp molded product from the male mold 2 through the intake hole 2.
The male mold 2 is pulled upward while the vacuum suction is performed on the mold a, and the mold is opened. Thereby, the pulp molded article is taken out from the female mold 1 together with the male mold 2. In this case, according to the results of experiments performed by the inventors, the molding pressure applied between the female mold 1 and the male mold 2 in the mold clamping operation is 5 kg / cm ² , and the electro-osmotic dehydration is 2 kg / cm ² .
When molded by applying a DC voltage of 00 V for 10 seconds, the pulp molded product taken out of the mold was compressed to a thickness of 2 mm, and its water content was up to 48% by weight (water content of 0.92 kg per kg of dry pulp). It was confirmed that it decreased. And
This pulp molded product is then placed in a drying oven to have a water content of 15%.
And the amount of electric power supplied to the drying step was 0.4 KWH per 11 kg of dry pulp. That is, as compared with the conventional molding method described above, the water content immediately after molding is reduced from 78% by weight to 48% by weight, and the power consumption input to the drying step is from 2.2 KWH per 11 kg of dry pulp to 0%. It was reduced to 0.4 KWH. Moreover,
Since the thickness of the pulp molded product is reduced to 2/3, it has been confirmed that the shrinkage in the drying step is small and the molded product does not undergo large deformation and distortion. A pulp molded product with a stable shape was obtained without the need for a modifying reforming process.

In the above-described embodiment, a pulp molded article made from used newspaper pulp is described. However, other natural fibers, synthetic fibers, inorganic fibers, or powders such as gypsum and cement are used as raw materials. It has been confirmed that a similar effect can be obtained even when molding is performed using the above-mentioned dispersion suspension.

[0017]

As described above, according to the present invention, since the electroosmotic dehydration is used in combination with the pressing and dehydrating in the molding step, the water content is high, the degree of compression is high, and the drying in the subsequent stage is performed. A good quality fibrous molded product with almost no distortion or deformation during the process can be obtained. In addition, due to the decrease in water content in the molding process, the amount of power consumed in the subsequent drying process can be reduced, and the power consumed during electro-osmosis is significantly higher than that of the conventional method. In addition to significant savings, a high-quality fibrous molded product can be manufactured at high productivity and at low cost, for example, by eliminating the need for reshaping to correct the deformation caused in the drying process.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a forming apparatus according to an embodiment of the present invention.

2A and 2B are explanatory diagrams of a method of manufacturing a pulp molded article by the molding apparatus of FIG. 1, wherein FIG. 2A is a state diagram in a first half step of supplying a pulp suspension to a molding die, and FIG. Diagram in the latter half of the process of pressing dewatering and electroosmotic dewatering

FIG. 3 is a schematic diagram illustrating electroosmotic dehydration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Female type 1a Cavity 1b Drainage channel 2 Male type 2a Suction hole 3 Mold clamping press 4 Raw material storage tank 5 Pulp suspension 6 Supply tank 7 DC power supply 8 Screen 9 Suction pump 10 Insoluble surface electrode 11 Suction blower 17 Pulp deposition layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) D21J 1/00-7/00 D21F 1/00-13/12 B01D 35/06

Claims (1)

(57) [Claims] When a fibrous molded article is prepared from a fibrous material dispersed and suspended in a liquid, a suspension of the fibrous material is placed in a molding die having a screen disposed on an inner peripheral surface of a cavity. Supplying, while forming a deposited layer of fibrous material on the screen by suction dehydration from behind the screen, and pressing and dehydrating the deposited layer by a mold clamping operation of a subsequent molding die to obtain a fibrous molded product, A molding device for a fibrous molded product used in a case where a direct current voltage is applied to a deposited layer of a fibrous material in the above-described compression dehydration step to perform electroosmotic dehydration, and a screen also serving as an electrode on an inner peripheral surface of a cavity. And a molding die comprising a female die having a drainage passage leading to the outside behind the screen, and a male die having a surface electrode, a mold-clamping press, and the drainage passage connected thereto. Suction pump, the female screen and the male type A DC power source connected between the surface electrode and the surface electrode, and the male surface electrode is an insoluble electrode having high corrosion resistance.