JP3561755B2 - Dry process for pulp molding - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for producing a deep drawn pulp molded product used as a buffer packaging material for eggs, fruits, etc. in a dry manner by recycling waste paper, particularly waste of a milk pack laminated with a polyethylene film, as a resource. Things.
[0002]
[Prior art]
BACKGROUND ART In order to transport easily damaged products such as chicken eggs and fruits, pulp molded products provided with concave portions for storing them one by one are used. In the past, vacuum moldings of plastic films were widely used as such structures, but due to the problem of refuse disposal and pollution, pulp mold products that can be easily treated have been replaced with non-polluting pulp molded products.
[0003]
A method for producing a pulp mold product is a mold in which a surface (a surface in contact with pulp slurry) of a metal having a predetermined shape, often a bronze, is covered with a 60-80 mesh wire mesh, usually a bronze wire mesh. Is immersed in the pulp slurry and the inside of the drain hole provided in the matrix is depressurized, the pulp slurry adheres to the entire surface along the shape of the mold, moisture is sucked in from the mesh of the wire mesh, and The pulp adheres to the shape of the mold as it flows through the gap between the mold and the water and collects at the drain hole and is discharged to the outside. When the pulp has adhered to a desired thickness, the mold is pulled up from the pulp slurry, and the adhered pulp layer is extracted from the mold and dried to obtain a product. The wire mesh covering the surface of the mold is indispensable for performing uniform dehydration over the entire surface of the mold. However, it is not an easy task to completely cover the surface of the uneven mold with a wire mesh. In some places, complicated hand work such as stretching the wire mesh and cutting out and welding the extra wire mesh in another place is required, especially in deep drawing molds, skilled skills and long hours of work are required, In addition, a metal matrix can be mass-produced by making one mold for casting. However, since wire mesh processing must be performed manually for each matrix, the manufacturing cost of the mold increases. Therefore, the ratio of the mold cost to the manufacturing cost of the pulp mold buffer packaging material increases, which is a factor that hinders the spread of pollution-free pulp mold buffer packaging material. Further, since the pulp layer is in a wet state at the time of being removed from the mold, it is necessary to provide a drying step, and the problem of wastewater treatment is accompanied with an increase in equipment and an increase in energy cost.
[0004]
Generally, recovered waste paper is defibrated by adding a large amount of water, and is made into a pulp slurry in a state of paper making or a molded product as described above. However, milk packs laminated with a polyethylene film have not been used effectively because extra work is required to separate the polyethylene film, even though very high quality pulp is used.
[0005]
A device (for example, a crushing and defibrating machine manufactured by Masuyuki Sangyo Co., Ltd .: trade name (R) Super Grinder) manufactured by grinding a milk pack with a rotating grindstone while being laminated with a polyethylene film was developed and obtained. There is known a mixture of cellulose fiber and polyethylene powder formed into a board. However, such a board is not as stretchable as a plastic film, and therefore cracks are likely to occur when deep drawing is performed as in a plastic film vacuum formed product.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for dry-producing a pulp molded product that can be deep drawn.
[0007]
[Means for Solving the Problems]
The dry manufacturing method of a pulp molded product according to the present invention is a method of milling waste paper and defibrating the mixture to obtain a mixture of cellulose fibers and a hot-melt plastic powder into a sheet having a partially convex portion. Accumulate and heat to melt the hot-melt plastic, or vacuum- or press-mold a sheet with a partially convex part integrated by needle punching, stretch the convex part of the sheet, heat and heat The method comprises fixing cellulose fibers by melting a fusible plastic.
[0008]
A mixture of cellulose fibers obtained by grinding and defibrating waste paper and a hot-melt plastic powder is used to grind ordinary waste paper (waste paper without a laminate of a hot-melt plastic film such as polyethylene). A mixture obtained by mixing and defibrating and a powder of a hot-melt plastic such as polyethylene may be used. The product may be one obtained by grinding and fibrillating with a crushing and fibrillating machine (trade name: Super Grinder) manufactured by Masuko Sangyo Co., Ltd. Cellulose fiber bundles fall apart and are finally broken up into submicron units, and polyethylene is also powdered. As the milk pack, once used as a milk pack and collected as an empty container, cutting waste generated when the milk pack is manufactured at a box making plant can also be used.
[0009]
Means for accumulating a mixture of cellulose fiber and a hot-melt plastic powder such as polyethylene in a sheet having a partially convex portion include a cellulose fiber on a wire mesh or plate provided with a concave portion corresponding to the convex portion. And a mixture of the heat-meltable plastic powder and the heat-meltable plastic powder so that the surface becomes flat. Since it is not possible to move to the final molding process as it is as it is, it is possible to heat it to melt a heat-meltable plastic such as polyethylene, or to integrate it with a needle punch to temporarily form a sheet with a partially convex part. Mold. At this stage, it is only necessary to have strength enough to move to the next final molding step.
[0010]
Depending on the shape of the mold, when the sheet having a partially convex portion is vacuum-formed or press-molded, the convex portion of the sheet is stretched, and the cellulose fiber is fixed by heating and melting the hot-melt plastic. A pulp molded product having a deep drawing can be obtained.
[0011]
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a plan view showing a pulp molded article 1 having a deep drawing recess 11 for storing perishable products such as eggs and fruits produced by the present invention one by one, and FIG. 2 is a pulp molded article shown in FIG. 1 is a cross-sectional view taken along line AA of FIG. FIG. 3 is a diagram showing a state 2 in which a mixture of cellulose fibers and a heat-meltable plastic powder is partially accumulated in a sheet shape having a convex portion 21, and a wire mesh having a concave portion 31 corresponding to the convex portion 21. The mixture of the cellulose fibers and the hot-melt plastic powder is spread on the plate 3 so that the surface becomes flat. Since it is not possible to move to the final molding step as it is as it is, it is heated to melt a heat-meltable plastic such as polyethylene, or it is integrated by a needle punch to form a partially convex portion shown in FIG. A sheet 4 having 41 is obtained. Next, the integrated sheet 4 having the partially convex portions 41 shown in FIG. 4 is press-formed using a male mold 5 and a female mold 6 as shown in FIG. 5, or partially formed as shown in FIG. The plastic film 7 is placed on the integrated sheet 4 having the convex portions 41 and placed on a mold 8 for vacuum forming, and is sucked through an air vent hole 82, so that a plan view is shown in FIG. The pulp molded article 1 having a deep drawn shape can be obtained. The reason why the plastic film 7 is overlaid on the sheet 4 is to prevent the air permeability of the sheet 4 and increase the suction force.
[0012]
【The invention's effect】
By recycling waste paper laminated with a plastic film such as a milk pack as a resource, a deep drawn pulp molded product used as a buffer packaging material for eggs and fruits can be produced in a dry manner.
[Brief description of the drawings]
FIG. 1 is a plan view showing an example of a pulp molded product manufactured according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA of the pulp molded product shown in FIG.
FIG. 3 is a view for explaining a state in which a mixture of a cellulose fiber and a hot-melt plastic powder is partially accumulated in a sheet shape having convex portions.
FIG. 4 is a view showing an integrated sheet partially having a convex portion.
FIG. 5 is a diagram for explaining a case where an integrated sheet having a partially convex portion shown in FIG. 4 is press-formed.
FIG. 6 is a view for explaining a case where an integrated sheet partially having convex portions shown in FIG. 4 is vacuum formed.

Claims (2)

A mixture of cellulose fiber obtained by grinding and defibrating waste paper and a hot-melt plastic powder is accumulated in a sheet shape having a partially convex portion, and heated to melt the hot-melt plastic. Or a sheet having a partially convex portion integrated by needle punching is stretched by vacuum forming or press forming the convex portion of the sheet, and heated to melt the hot-melt plastic, thereby fixing the cellulose fibers. Dry manufacturing method for pulp molded articles. A mixture of cellulose fibers obtained by grinding and defibrating waste paper and a hot-melt plastic powder is obtained by crushing and defibrating a milk pack laminated with a polyethylene film. A dry production method of the pulp molded product according to claim 1.

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