JPH06322699A - Production of article formed by paper-making process - Google Patents

Abstract

PURPOSE:To produce a formed article having high strength by screening a paper component from a paper-making slurry and hot-pressing the intermediate product. CONSTITUTION:A paper-making slurry containing pulp and thermoplastic polymer fiber as the paper components is subjected to paper-making process to screen the paper component from the slurry and the obtained paper-making intermediate product is hot-pressed to obtain a formed paper article.

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 paper molded product.

[0002]

2. Description of the Related Art In recent years, for the packaging of household appliances, precision instruments, foods, etc., paper-making components are made from foamed synthetic resin materials and paper-making raw material liquids in which pulp raw materials are dispersed. The thing etc. which were made into a predetermined shape are used. Of these, those made from pulp are mainly used as containers for packaging small electric products and foods such as eggs.

Conventionally, as a method for producing a papermaking molded article, a papermaking component is simply removed from a papermaking raw material liquid in which pulp is dispersed by a papermaking molding die formed into a predetermined shape, water is dehydrated, and then heated. A method of finally forming by a press or the like to obtain a papermaking molded article having a predetermined shape has been adopted.

[0004]

However, the conventional papermaking molded article produced by removing the papermaking components from the papermaking raw material liquid in which the pulp is simply dispersed as described above has a strength higher than that of the plastic molded article. It was low and could not be used as a packaging for heavy items.

The present invention has been made in view of the above points,
It is an object of the present invention to provide a method for producing a paper-formed product that can produce a paper-made product with high strength.

[0006]

[Means for Solving the Problems] The method for producing a paper-formed product of the present invention is a method for producing a paper-formed product in which a paper-forming component is removed from a paper-forming raw material liquid, and a paper-forming intermediate product formed by heating is pressed. The above-mentioned papermaking raw material liquid is characterized by containing thermoplastic polymer fibers as a papermaking component together with pulp.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a papermaking molding mechanism for carrying out a papermaking molding step which is one step of the method of the present invention, and FIG. 2 shows an example of a heating press mechanism for carrying out a heating press step which is one step of the method of the present invention. There is.

According to the method of the present invention, the papermaking molding intermediate 10 is obtained by first removing the papermaking components from the papermaking molding raw material liquid.
Are formed (papermaking molding step), and then the papermaking molding intermediate product 10 is heated and pressed (heating press step) to produce a papermaking molded article.

In the papermaking molding step, for example, an upper mold 3 having an inner surface shape or an outer surface shape of a container to be made as shown in FIG. 1 (in the example shown in the figure, a shape substantially conforming to the outer surface shape of the container is formed. ), And a lower papermaking mold 2 having the outer surface shape or the inner surface shape of the container to be manufactured (in the example shown in the figure, it is formed into a shape that substantially matches the inner surface shape of the container). And, it is preferable to carry out in a paper making mechanism 1 composed of a support frame 4 supporting the lower paper making mold 2. In FIG. 1, 6 is a drainage hole.

The upper mold 3 of the papermaking and forming mechanism 1 is provided with a large number of fine holes through which air and water vapor can pass, and the material is preferably metal or elastic material. Examples of the metal include aluminum and nickel, and examples of the elastic material include rubber, elastic synthetic resin, synthetic resin foam and the like. Further, a plurality of through holes through which water can permeate are provided on the wall surface, the bottom surface, etc. of the papermaking lower mold 2. The size of the through holes is usually 0.5 mm to 2.0 mm in order to allow water in the papermaking raw material liquid described below to efficiently permeate and not allow papermaking components to permeate. Is preferred. If the pores are too large, the amount of papermaking components passing through the pores will be increased, which will hinder the papermaking molding at that location, or the papermaking components will enter into the pores, resulting in traces of pores in the resulting molded article. There is a risk that it will remain clear and deteriorate the appearance. On the contrary, if the holes are too small, clogging easily occurs.

The papermaking molding lower mold 2 is, if necessary, the lower mold 2
Alternatively, a vacuum pump or the like may be provided, and vacuum suction may be performed to reduce the pressure on the lower surface of the lower mold 2 to dehydrate the water in the papermaking raw material liquid. Although not particularly shown on the lower mold 2, a shape (that is,
A shape that roughly matches the outer or inner shape of the container. It is also possible to mount the water-permeable papermaking net of). The papermaking net promotes drainage of water, and it is preferable to use a net having a mesh of about 15 to 80 mesh. By providing the net, drainage can be efficiently performed. When a papermaking net is used, the through hole provided in the lower mold 2 is 0.5 mm
It may be slightly larger than about 2.0 mm.

In the method of the present invention, a papermaking forming raw material liquid containing the thermoplastic polymer fibers together with pulp in the papermaking forming raw material liquid is used. In the method of the present invention, it is important to use such a raw material liquid. The thermoplastic polymer fibers preferably have a melting point lower than the thermal decomposition temperature of pulp. Examples of such thermoplastic polymer fibers include polyvinyl alcohol, linear ultra low density polyethylene, branched low density polyethylene, linear low density polyethylene, linear medium density polyethylene, high density polyethylene, and ethylene-vinyl acetate copolymer. , Ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-maleic anhydride copolymer, ethylene-vinyl chloride copolymer, polystyrene, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer Coalesce, styrene-maleic anhydride copolymer, polypropylene, propylene-ethylene random or block copolymer,
Propylene-butene random or block copolymer,
Propylene-ethylene-butene random copolymer, propylene-maleic anhydride copolymer, vinyl chloride, polyethylene terephthalate, polybutylene terephthalate,
Non-degradable polymers such as various nylons, ethylene diadipate, propiolactone, caprolactone, β
Examples include fibers which are made of polymers such as easily decomposable homopolymers or copolymers derived from hydroxybutyric acid and the like, which may be used alone or in combination of two or more. still,
The fiber length of the polymer fiber is preferably 1 mm to 20 mm,
The fiber diameter is preferably 1 μ to 100 μ.

The above-mentioned thermoplastic polymer fibers which are contained in the papermaking raw material liquid together with pulp as a papermaking component are preferably contained in the papermaking component in a proportion of less than 50%, more preferably less than 30%. Further, various additives may be added to the papermaking forming raw material liquid as needed. It should be noted that recycled pulp using recovered paper may be used as part or all of the pulp dispersed in the papermaking raw material liquid as a papermaking component.

In the papermaking molding mechanism 1 described above, in order to carry out the papermaking molding step of removing the papermaking components from the papermaking molding raw material liquid, for example, the papermaking molding raw material liquid is poured onto the lower papermaking mold 2 and Papermaking components are removed from the mold or the lower mold 2
The whole is immersed in a papermaking raw material liquid tank, and if necessary, vacuum suction is applied from the lower side of the lower mold, and then the lower mold is raised to remove the papermaking components in the papermaking raw material liquid onto the lower mold 2. Then, the papermaking components in the papermaking raw material liquid are made on the lower papermaking mold 2. Next, the upper mold 3 and the lower mold 2 are combined with each other to press the papermaking components, and if necessary, vacuum suction is applied from below the lower mold 2 and / or air pressure is applied from the upper surface side of the upper mold 3. As a result,
Most of the water remaining in the paper-making component that has been drawn off on the lower mold 2 flows out of the support frame 4 through the through holes of the lower mold 2, and the paper-making component that contains water on the lower mold 2. Is removed and left to form a papermaking intermediate product 10 having the shape of the lower mold 2.

As described above, when the papermaking components are taken out from the papermaking lower mold 2, the intermediate papermaking product 10 (and further the papermaking product) formed is pulp and thermoplastic polymer fibers uniformly distributed. As described above, it is preferable to stir the papermaking raw material liquid while heating to uniformly disperse the papermaking components such as pulp and resin in the stock solution. Also,
The amount of the paper-making components to be made on the lower mold 2 should be adjusted by the concentration of the paper-making components dispersed in the pulp material and the vacuum suction time, etc., which is performed as necessary when making paper on the lower mold 2. You can

Thus, the papermaking components in the papermaking raw material liquid are made on the papermaking lower mold 2, pressed by the upper mold 3 from the upper surface side, and further, the lower surface side of the lower mold 2 is depressurized if necessary. Then, when the water content is dehydrated, the intermediate product 10 having a predetermined shape having a predetermined shape has a water content of about 30% by weight to 70% by weight. At this time, the pressing by the upper mold 3 is preferably performed so as to have a thickness of about 10 to 40 when the apparent thickness in a state where the papermaking components are taken out on the lower mold 2 is 100. Accordingly, when decompressing the lower surface side of the lower mold 2,
The reduced pressure condition is preferably about 700 mmHg to 10 mmHg.

The papermaking and molding intermediate product 10 thus obtained
Are then transferred to the hot pressing process. The heating press process is performed by the heating press mechanism 7, and the heating press mechanism 7 is
For example, as shown in FIG. 2, a press upper die 9 having an inner surface shape or an outer surface shape of a papermaking molded article (in the example shown in the figure, formed into a shape that substantially matches the outer surface shape of the molded article), and papermaking. It is preferable that the press lower die 10 has an outer surface shape or an inner surface shape of the molded product (in the example shown in the figure, it is formed in a shape that substantially matches the inner surface shape of the molded product). The upper press die 8 and the lower press die 9 are provided with a large number of fine holes through which air and water vapor can pass, and both are provided with an electric heating device. Further, the inside of the mold may be sucked through the fine holes.

In the hot pressing step, the papermaking intermediate product 10 is sandwiched between the upper press die 8 and the lower press die 9 and pressed under heat. In the method of the present invention, since the papermaking raw material liquid containing the above-mentioned pulp and the thermoplastic polymer fiber is used, the papermaking intermediate 10 is formed from the pulp and the thermoplastic polymer fiber. Therefore, in the state where the thermoplastic polymer fibers in the papermaking intermediate product 10 are melted by heating, the papermaking intermediate product 10 is pressed by the upper press die 8 and the lower press die 9.

The hot pressing in the hot pressing step depends on the thermoplastic polymer fiber used,
Generally preferably carried out at a heating temperature of 60 ° C. to 300 ° C., pressing ^{force, 1kg / cm 2 · G~10kg /} cm 2 · G, the pressing time is preferably about 3 to 100 seconds. Then, it is preferable that the final product has a thickness of about 5 to 30 when the apparent thickness in a state where the papermaking components are taken out on the net is set to 100, and hot pressing is performed. In addition, the press upper mold 8
And when the finally molded paper-formed product is taken out from the lower press die 9, in order to improve the releasability of the resin on the surface of the paper-formed product from both press dies, cooling is performed from the fine holes provided in both. It is preferable to blow out air.

In the method of the present invention, a high-frequency applying step of applying a high frequency to the papermaking intermediate 10 in order to efficiently dry the papermaking intermediate 10 may be performed in addition to the papermaking forming step and the hot pressing step. it can.

To apply a high frequency to the papermaking intermediate product,
The transmission frequency is 10 ³ Hz to 10 ¹³ Hz, preferably 10
⁶ Hz to 10 ¹² Hz, more preferably 10 ⁷ Hz to 10 Hz
A high frequency oscillator 2 having a frequency of ⁸ Hz and an output of about 1 kw to 100 kw is used, and an electrode provided on the high frequency oscillator 2 is positioned, for example, while the upper mold 3 and the papermaking lower mold 2 are aligned with each other. , The upper die 3 and the papermaking lower die 2 (that is, the papermaking mechanism 3), or the press upper die 9
It is provided so as to be connected to the upper press die 9 and the lower press die 10 (that is, the heating press mechanism 4) while the hydrous papermaking molded article 16 is being hot pressed by the press lower die 10 and Further, the electrodes of the high frequency oscillator 2 may be connected to both the paper making mechanism 3 and the heating press mechanism 4.

Next, the present invention will be described with reference to specific examples.

Example 1 The following papermaking raw material liquid was prepared, papermaking components were made from the papermaking raw material liquid, and the intermediate papermaking intermediate product was heated and pressed under the following conditions. The papermaking molded article shown in was obtained. The weight of the obtained molded product was about 24 g, the vertical length a was about 20 cm, the horizontal length b was about 16 cm, and the height h was about 5 cm. The density of the molded product is 0.04
It was 72 g / cm ² and the thickness d was 0.8 mm.

[Papermaking raw material liquid] -Concentration of papermaking components contained in the papermaking raw material liquid ... 0.5 wt% concentration-Constitution ratio of papermaking components Pulp ... ·············································································· but 15% by weight

[Conditions of heating press] ・ Heating temperature ・ ・ ・ ・ ・ ・ ・ ・ ・ 170 ° C ・ Pressing force ・ ・ ・ ・ ・ ・ ・ ・ ・ 3kg / cm ²・ G ・Press time: 180 seconds

As a strength test of the obtained paper-formed molded product, a compression plate (having an area larger than the projected area of the plan view of the molded product, which does not deform when the molded product is compressed) .) Was used to apply a compression load at a speed of 10 mm / min, a graph showing the relationship between the compression load and the compression amount at that time was recorded, and the load showing the yield point was read from the graph (JIS- According to Z-0212-A method). The value was 40.5 kgf. Moreover, at the yield point, no fracture occurred on the side wall of the molded product.

Comparative Example A paper molded product was obtained under the same conditions as in Example 1 except that the pulp component was 100% by weight. Similarly, when the yield point load was read, it was 31.3 kgf. Moreover, the side wall of the molded product was fractured at the yield point.

[0028]

As described above, according to the method for producing a paper-formed molded product of the present invention, a paper-forming raw material liquid containing thermoplastic pulp fibers together with pulp as a paper-making component is used, and hot-pressing is performed in the hot-pressing step. Therefore, it is possible to improve the strength as compared with the molded product obtained by the conventional method, and it is possible to obtain an effect that it can be used for packing heavy objects.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a papermaking molding mechanism for performing a papermaking molding step which is one step of the method of the present invention.

FIG. 2 is a cross-sectional view showing an example of a hot press mechanism for performing a hot press step which is one step of the method of the present invention.

FIG. 3 is a perspective view showing an example of a paper molded product obtained by the method of the present invention.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

[Explanation of symbols]

 1 Papermaking molding mechanism 7 Heating press mechanism 10 Papermaking intermediate product 11 Papermaking molded product

Claims (1)

[Claims] 1. A method for producing a papermaking molded article, which comprises heating and pressing a papermaking molding intermediate product obtained by removing papermaking components from a papermaking molding raw material liquid to form a thermoplastic polymer fiber together with pulp in the papermaking molding raw material liquid. A method for producing a paper-formed molded product, characterized in that it is contained as a component.