JPH04263700A - Method and device for manufacture of article from paper pulp - Google Patents

Abstract

PURPOSE: To simply obtain an article of a concave shape that has an arbitrary dimension by holding both of a molding step where a slurry of paper pulp is compressed to a mold and a drying step where a molded article in the mold is dried by supplying heat in specific states, respectively. CONSTITUTION: A mold 1 made of an air-permeable material is placed on a support 2 substantially horizontally so that its concave inside may face upward. A paper pulp slurry is cast in the mold 1 and a higher pressure is applied to the outside part 5 in comparison with the inside part 3 at an ambient temperature, during the molding step, while a reduced pressure is applied on the outside part 5 compared with the inside part 3 and heat 6 is fed to an article molded in the mold during the drying step.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION The present invention relates to a method for producing molded articles from paper pulp, particularly paper pulp of a quality commonly known in this industry, such as high-grade pulp, and The material of the article has substantially the same stiffness as a given cardboard.

The invention furthermore relates to a device for carrying out this method.

0003

BACKGROUND OF THE INVENTION This method is used in particular for games, carvings, decorations or cosmetics, with articles that can be used in the field of jewelry, hygiene, or the art of forming containers, cases, or optionally supporting advertising. , making it possible to produce display cases and/or containers for perfumes, medicines, agricultural products.

Various devices are known for producing articles from paper pulp.

In particular, the relatively old US Pat. No. 169,724
No. 4 relates to a machine for forming paper pulp comprising a wheel rotating about a horizontal axis and supporting a mold container around the wheel. A container filled with paper pulp is provided in the lower part of this wheel. The material is provided with means for maintaining suction on the mold. In this way, a constant uniform pressure is maintained on the layer of paper pulp placed in the mold during the deposition of the paper pulp and its drying. Drying is brought about by the suction of hot air through the paper pulp and the mold during the passage of the mold in the drying chamber. Means are provided for supplying compressed air towards the inside of the mold so as to inject the article as it is being dried.

[0006] More recent British Patent No. 1,137,761 and French Patent No. 1,399,753 describe machines for producing hollow articles from paper pulp and are equipped with similar means, in particular a mold container wheel.

Due to their rotation, these machines:
It can be seen that this is particularly complicated with respect to supply devices, for example compressed air supply devices. In addition, replacing the mold on the wheel is
This is a relatively long task.

These machines are large in size because the molds have to be fixed on wheels. Thus, the size of articles molded by these machines is limited. In particular, it is impossible to envisage the manufacture of articles with a width of 2 or 3 meters.

[0009] These materials are intended to enable relatively high production volumes; they are used, for example, to produce packs and containers for agricultural products, such as egg cartons. In particular, by using the machines just mentioned,
Known methods for manufacturing cellulosic articles produced from paper pulp thus have the shape of the article such that the paper pulp is molded onto the recesses, said recesses being placed on a support. squeezing the paper pulp by suctioning it through the recesses of the support and drying the pulp thus deposited.

These known methods require the use of at least three different complementary tools and have the following sequence of steps: 1) Installation of a metal grid having the shape of the desired item and defining the recesses: This metal grid may be made of solid metal or other strong material to prevent deformation of the relatively flexible grid or recesses. Supported by the same shape made from. This metal shape has a number of holes formed in it to allow suction through this lattice that covers it. 2) suction of the pulp through this grid and this shape made of metal or other strong materials; 3) drying of the shaped article by passage in a tunnel furnace:
In this furnace, the articles are conveyed by a conveyor belt passing through this tunnel, the articles are dried by being blown with a jet of hot air along their path in the tunnel furnace, and the hot air is exchanged through a ventilation system. The temperature is sufficient to convert the remaining liquid into evaporated vapor.

In another embodiment of the drying step, the article is dried by two complementary tools.

[0012] The first tool is made of metal, has a recess on one side of the article, and has a temperature of 260°C to 290°C.
The tool and the recess are formed with a number of holes that allow exchange of evaporative gas.

[0013] The second tool is similar to the first tool in that it has an article recess, contains an assembly of electrically heated resistors, and has a number of holes formed therein; The shape complements the shape of one of the recesses of the first tool to complete it.

[0014]Each of the two tools required to carry out the drying stage of the currently used method is complex to assemble and must have a shape that corresponds to the item to be dried, which , the manufacture of these tools involves considerable expense and time.

[0015] These methods thus require the use of several tools, and the weeks to months required to make these tools result from the problem of matching the shape of the item being dried. It depends on the difficulties that arise.

Furthermore, these methods are expensive to implement due to the high energy consumed in heating the tool or the tunnel furnace.

In addition, this tunnel furnace is large and operating and maintaining it complicates manufacturing operations.

Regarding the special drying tools mentioned above, they are very expensive to manufacture and to fit into a single size and shape of item. Thus, for each different item it is necessary to manufacture a new tool with all the resulting manufacturing complexity.

As mentioned above, molds generally consist of similarly shaped elements made of solid metal in which holes are formed, in particular depressions made like a metal grid giving the shape of the desired article. , consists of.

It can be seen that in the known machine, when the mold is filled with paper pulp, a considerable suction must be supplied to the mold. In practice, the mold is driven in rotation by a wheel and the paper pulp is held in the mold only by suction supply.

It can be seen that due to suction, the paper pulp enters the holes of the grid. This allows the production of only non-reentrant articles. In practice, re-entrant articles cannot be removed from the mold.

[0022] This limitation results in considerable disadvantages because it complicates the manufacture of the mold. In addition, the reentrant appearance is advantageous, especially when manufacturing display cases for cosmetic products, in order to increase the volumetric recess of the resulting article. It is absolutely important if, for example, it is necessary to perform engraving.

[0023]

SUMMARY OF THE INVENTION The present invention ameliorates these drawbacks and, in particular, significantly simplifies the equipment required and provides molds that can be manufactured quickly, generally within 24 hours. by providing and making it possible to produce articles with reentrant corners of any size and by using means common to those used to form the articles, making the drying step economical. The purpose is to make it easy to implement, and to bring about various advantages, including:

[0024]

[Means for Solving the Problems] To this end, the present invention
a forming stage in which the paper pulp is pressed into a mold having the shape of the article, and a drying stage in which heat is supplied to the shaped article in the mold;
The present invention relates to a method for producing an article from paper pulp having the following.

According to the invention, during both stages the mold is fixed substantially horizontally with the inner part of the mold pointing upwards. Additionally, during the molding stage, a higher pressure is maintained on the outside of the mold compared to the inside of the mold at ambient temperature.

Finally, during the drying phase a reduced pressure is maintained on the outside of the mold compared to the inside of the mold.

The degree of high pressure maintained during the molding step is selected to obtain a substantially uniform layer of paper pulp inside the mold.

According to a first embodiment of the invention, heat is supplied to the article by infrared radiation during the drying phase.

Preferably, this radiation is from 100°C to 2°C.
yielding a temperature between 90°C.

[0030] According to a second embodiment of the invention, during the drying phase heat is supplied to the article by means of a heated gas that is drawn through the article due to the reduced pressure.

[0031] Thereby, the drying of the articles is as short as possible and complete, the hot gas sucked in during the drying stage having a temperature of between 100°C and 290°C.

While the molded article is still in the mold, it is dried either by radiation and suction of gas, or by suction of preheated gas through the mold and supports, thereby removing the mold from the mold. All stages of the manufacturing process, up to the release of the dried article, are effected using the same tools for molding, shaping and drying.

[0033] In order to limit manual labor and to accommodate all shapes of articles, articles made from paper pulp are dried and then demolded by a jet of compressed air through the mold.

In another embodiment, the articles use the same suction source as for the other steps of the process, especially when they are of large size, in order to save on maintenance and manual costs of the articles. It is removed from the mold by a suction device that can be used.

[0035] In order to increase the visual interest of the article and give it a good informaticity, this manufacturing method can optionally be applied by applying pigments to the surface of the article or by adding pigments to the paper pulp. , with a further step of coloring the shaped article. In this case, an article colored throughout is thus obtained.

[0036]For the purpose of increasing rigidity and aesthetic design, the molded article is covered with metal.

[0037] In order for the article to withstand inclement weather conditions when placed outside or stored in a humid location or unprotected, the method of manufacturing the article optionally provides a water-resistant treatment using a resin. It has a stage of

The invention furthermore relates to a device for carrying out the method just described.

According to the invention, the mold is made from a breathable and waterproof material.

[0040] Preferably, this material resists thermal shock due to the passage of vaporized air when the article is dried by suction of hot gas, thereby providing a relatively long mold life. For this same purpose, preferably non-oxidizing materials are selected.

[0041] This material is synthesized.

Various details and advantages of the invention will become apparent from the following non-limiting description, taken in conjunction with the accompanying drawings, in which: FIG.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the apparatus according to the invention which makes it possible to manufacture articles from paper pulp essentially comprises a mold 1 mounted on a stationary support 2. The mold is arranged substantially horizontally, with the inner part 3 of the mold facing upwards. It is made of breathable material.

Article 4 is formed as follows. A suitable amount of paper pulp is poured into mold 1 by manual or automatic means. A high pressure is then maintained at ambient temperature on the outer part 5 of the mold 1 compared to the inner part 3 of the mold throughout the molding stage.

This high pressure, the extent of which is carefully chosen, prevents the paper pulp from settling at the bottom of the mold due to its specific gravity and maintains a uniform layer of paper pulp on the inner part 3 of the mold. enable.

During the drying phase, a reduced pressure is applied on the outer part 5 of the mold 1 compared to the inner part 3 of the mold, and heat is supplied to the article molded in the mold. For example, this reduced pressure is obtained by a vacuum pump and duct located at the rear of the mold 1. These devices are not shown.

[0047] This heat is supplied to the article by infrared radiation. This radiation is provided by suitable equipment, not shown. This device is particularly suitable for
yielding a temperature between 90°C.

The value of radiation for heating the article without heating the mold is determined by any suitable method. This makes it possible to protect the mold from thermal shock in an effective manner.

Additionally, hot gas 6 through the article and mold
It is possible to choose to dry the articles 4 in the mold 1 by inhaling gas, the flow of gas being directed from the top to the bottom of the mold, as shown in FIG.

For example, this suction 6 of hot gas is obtained by a heating device placed above the mold and heating of the gas sucked in due to the reduced pressure. This device is
Not shown in FIG. Preferably, the gas used consists of ambient air.

[0051] Thus, the heating device preferably heats the air to a temperature between 100°C and 290°C, and the hot air 6 is pumped into the mold 1 by means of the pump mounted at the end of the suction duct. and the molded article 4 in the mold, this step dries the molded article 1 still present in the recess.

[0052] Due to the reduced pressure, the paper pulp is fixed in the mold. In fact, the pressure is not sealed, but the mold is leak-tight with respect to the paper pulp, the paper pulp is not further entrained by the reduced pressure, and this pulp takes the shape given by the mold, while the radiation or dried due to the temperature of the air being drawn in.

[0053] The article 1 is then demolded by two selectable methods. The first method is by a jet of compressed air provided by a stationary and available source of compressed air, which circulates in the same way as the air drawn in by the pump, but in the opposite direction. , is discharged from mold 1 to article 4. A second method is by a suction device placed on at least one outer surface of the article and a suction opening or movement of the suction device onto the article 4 .

Mold 1 is preferably made of waterproof material.

Mold 1 undergoes considerable thermal shock during drying by suction of hot gas, and in order to increase its service life it is preferably made of a material that resists thermal shock.

For the same purpose, this material is not oxidized. Preferably, mold 1 is made of synthetic material, in particular to allow rapid production.

[0057] The method has further steps depending on the purpose of the article. Some details are given by way of example below.

[0058] In general, articles may have different appearances due to different surfaces of the article being molded, so as to change the information capacity of the article used, especially display cases. colored in a further step by the deposition of all kinds of pigments.

According to another embodiment, the articles obtained are colored throughout by adding pigments to the paper pulp before the various stages of the method just described.

[0060] According to certain embodiments, the article is covered with metal.

[0061] To achieve the elegant appearance particularly required for display cases, the molded articles may be colored by coloring using a gun.

In order to obtain various surface conditions, the method for producing the article to be molded has a further lacquering step with or without baking, which changes the quality of the surface of the roll of article. adjustment and, in addition, allows the article to be completely waterproof.

[0063] It can be clearly seen from the foregoing that the mold and the article can be of any size since the mold is fixed horizontally.

In addition, this device is very simple compared to known devices. In particular, molds are exchanged very quickly and
This is advantageous in the technical field referred to by the present invention when the continuous work is of small volume.

[0065] Since the mold is arranged with its inner part facing upward, the degree of gas suction provided during the drying stage is much greater than that required for rotating wheel devices that do not use specific gravity. small. In this way, the paper pulp hardly penetrates the inner surface of the mold and articles with concave corners can be produced.

Although the invention has been described with respect to a very specific method, this does not limit the invention in this way; for example, without departing from the scope of the invention, Many variations of the invention can be made, such as all methods that allow evaporation of liquid.

[0067] Reference numerals following technical features recited in the claims are solely for the purpose of facilitating an easier understanding of the claims and are not intended to limit the scope of the invention.

[Brief explanation of the drawing]

1 shows a still wet article during the forming stage; FIG.

FIG. 2 shows the article during the suction drying stage.

[Explanation of symbols]

1...type 3...Inner part 4...Goods 5...Outer part 6...Hot gas

Claims (16)

[Claims] 1. A method for producing an article from paper pulp, comprising a forming step in which the paper pulp is pressed into a mold having the shape of the article, and a drying step in which heat is supplied to the formed article in the mold. In the method, during both stages the mold (1) is fixed substantially horizontally with the inner part (3) of the mold facing upward; ), a higher pressure is maintained at ambient temperature on the outer part (5) of the mold compared to the inner part (3) of the mold during the drying phase.
A method for producing articles from paper pulp, characterized in that a reduced pressure is maintained on the outer part (5) of the mold compared to the mold. 2. characterized in that the degree of high pressure maintained during the molding stage is selected so as to obtain a substantially uniform layer of paper pulp on the inner part (3) of the mold (1); The method according to claim 1. 3. A method according to claim 1, characterized in that during the drying stage heat is supplied to the article (4) by means of infrared radiation. 4. A method according to claim 3, characterized in that the radiation produces a temperature between 100°C and 290°C. 5. According to claim 1 or 2, characterized in that during the drying phase, heat is supplied to the article (4) by means of a heated gas which is sucked through the article due to the reduced pressure. Method. 6. A method according to claim 5, characterized in that the gas consists of ambient air. Claim 7: Hot gas (
7. A method according to claim 5 or 6, characterized in that 6) is a temperature between 100<0>C and 290<0>C. 8. A method according to claim 1, characterized in that, after the drying step, the article (4) is removed from the mold (1) by jetting compressed air through the mold. 9. A method according to claim 1, characterized in that, after the drying step, the article (4) is removed from the mold (1) by means of a suction device. 10. A method according to claim 1, characterized in that it comprises a further step of coloring the shaped article (4) by applying pigments to the surface of the article. 11. A method according to claim 1, characterized in that it comprises a further step of coloring the article (4) throughout by adding pigments to the paper pulp. 12. Claim 1, characterized in that it comprises a further step of covering the surface of the shaped article (4) with metal.
12. The method according to any one of 11 to 11. 13. A method according to claim 1, further comprising the step of providing waterproofing of the article (4) using a resin. 14. Apparatus for carrying out the method according to claim 1, comprising a mold, characterized in that said mold (1) is made of a breathable and waterproof material. 15. Device according to claim 14, characterized in that the material resists thermal shock and does not oxidize. 16. Device according to claim 14 or 15, characterized in that the material is synthetic.