Pulp molding process and paper-shaped article made thereby

A pulp molding process and a paper-shaped article made thereby are provided. The pulp molding process comprises the steps of providing a composite having at least one fiber material, performing a pulp-dredging step including a first pre-compression forming step, performing a compression thermo-forming step, and performing an edge-cutting step for forming a paper-shaped article, wherein the composite comprises 20 to 99 parts by weight of a superior short fiber material for forming the paper-shaped article for eliminating the crosslinking effect. The paper-shaped article made by the pulp molding process comprises a cave having a transversal width of from 0.5 mm to 8 mm.

FIELD OF THE INVENTION

The present invention relates to a pulp molding technology, and more particularly to a pulp molding process for eliminating a crosslinking effect, and also particularly to a paper-shaped article made by the pulp molding process.

BACKGROUND OF THE INVENTION

Please refer toFIG. 1, which is a schematic cross-sectional view of a wet pulp body or a paper-shaped object manufactured by the conventional pulp molding process. Generally, the conventional pulp molding process comprises a pulp-dredging step and a thermo-forming step. In the pulp-dredging step, a pulp-dredging stage1is applied to move and dip a mold die2into at least one slurry tank (not shown) which is used to store wet paper slurry in liquid. The raw material kind of the paper slurry commonly consists of specific plant fiber, water, other raw materials, and so on. Then, a part of the wet paper slurry is dredged from the slurry tank by the mold die2to accumulate a wet pulp body or a very rough paper-shaped object5correspondingly onto an upper surface of the mold die2.

After the pulp-dredging step of dredging up the wet pulp body/paper-shaped object5by the mold die2from the paper slurry, a little of the wet pulp body may be accumulated above an opening of a shallow cave/groove3formed with the wet pulp body5, to constitute a crosslinking portion4(or so-call “bridging”) as shown in dotted lines covering the opening of the cave/groove3, since most of the wet pulp body contains long-length fibers (over 2 mm) which are floated above a narrow/tiny cavity on the mold die2correspondingly to the shallow cave/groove3so that a crosslinking effect occurs thereabove; especially in the manner when the cave/groove3of the wet pulp body5needs to be shaped in a thinner cross-sectional width (i.e. below 8 mm) or a deeper depth (as over 8 mm). In actually, the crosslinking effect may occur on two opposite sides of the thinner cross-sectional width of the cave/groove3.

Secondly, a finished product made from the wet pulp body/paper-shaped object5by the rest following manufacturing process (i.e. the thermo-forming step/a tool-cutting/trimming step) has a very rough surface smoothness. For example, the surface smoothness of the inner surface thereof may be larger than over 30 seconds according to a ‘Bekk’ Smoothness measurement standard. Furthermore, a structure of the paper-shaped object5/the finished product may crash/be damage easily during the following process (i.e. the thermo-forming step/the tool-cutting/trimming step). Thus, the crosslinking effect will seriously decrease the yield of the paper-shaped object5/the finished product.

Even though the crosslinking effect might be decreased in part by changing/replacing the raw material kind of the wet paper slurry with the other which has a shorter-length fiber (as less than 2 mm but larger than 1.4 mm), a mechanical strength of the whole paper-shaped object/the finished product constructed with such a shorter-length fiber will be weak which is not enough for forgoing use. Additionally, because the cave/groove3is too small, a corresponding broken opening possibly formed with the cave/groove3will hugely affect the following process. Moreover, the paper-shaped object manufactured by the conventional molding process and made of the same composite consisting of raw materials will form a smooth surface and a rough surface respectively as both surfaces of the paper-shaped objects. The rough surface reduces the aesthetics of the paper-shaped object.

Furthermore, the conventional pulp molding process comprising the pulp-dredging step and the thermo-forming step needs take a working cycle time of over 200 seconds per each paper-shaped object, thereby resulting in a very lower manufacturing efficiency for mass manufacture requirement.

Therefore, it is necessary to provide a pulp molding process and a paper-shaped article to solve the above problems.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a pulp molding process and a paper-shaped article which can solve a technical problem of the crosslinking effect occurring in part of a wet pulp dredged up by a mold die from paper slurry during the conventional molding process.

In order to solve the aforementioned drawbacks of the prior art, the present invention provides a pulp molding process comprising:

providing a composite having at least one fiber material, which comprises a superior short fiber material and a relatively longer fiber material;

performing a pulp-dredging step of dredging a pulp body made of the composite, by one of a first upper mold and a first lower mold, from a slurry tank carrying a paper slurry containing of the composite;

performing a first pre-compression forming step on the pulp body to form at least one first semi-finished product with a first cave on a surface thereof, by and between the first upper mold and the first lower mold; and

performing a compression thermo-forming step on the at least one first semi-finished product to form at least one second semi-finished product, by and between a third upper mold and a third lower mold;

wherein the composite comprises 20 to 99 parts by weight of the superior short fiber material enough to prohibit a crosslinking portion from being formed in/above the first cave.

In the pulp molding process described above, the pulp-dredging step and the first pre-compression forming step are performed in the same working stage applied in the pulp molding process.

In the pulp molding process described above, a fiber length of the superior short fiber material is greater than 0 mm and less than or equal to 1 mm.

In the pulp molding process described above, a fiber length of the superior short fiber material is greater than 0 mm and less than or equal to 0.8 mm

In the pulp molding process described above, the superior short fiber material is selected from the group consisting of synthetic fibers, regenerated fibers, nature fibers, microfibers, nanofibers and/or any combinations thereof.

In the pulp molding process described above, the composite comprises an additive which comprises a water retention agent and a paper strength agent.

In the pulp molding process described above, the relatively longer fiber material further comprises a shorter fiber material and/or a longer fiber material, each of which is longer than the superior short fiber material in fiber length, and the composite comprises less than 50 parts by weight of the relatively longer fiber material.

In the pulp molding process described above, a Canadian standard freeness of the first semi-finished product is about greater than 300 csf.

In the pulp molding process described above, before the compression thermo-forming step and after the first pre-compression forming step, the process further comprises a second pre-compression forming step performed on the at least one first semi-finished product by and between a second upper mold and a second lower mold.

In the pulp molding process described above, in the second pre-compression forming step, the at least one first semi-finished product comprises a second cave having a transversal width of from 6 mm to 8 mm.

In the pulp molding process described above, in the first pre-compression forming step, the at least one first semi-finished product comprises the first cave having a transversal width greater than 0 mm and less than 8 mm.

In the pulp molding process described above, in the compression thermo-forming step, the at least one second semi-finished product comprises a third cave having a transversal width of from 6 mm to 8 mm.

In the pulp molding process described above, the process further comprises performing an edge-cutting step on the at least one second semi-finished product to form at least one paper-shaped article with a fourth cave wherein the fourth cave has a transversal width of from 0.5 mm to 8 mm.

In the pulp molding process described above, each working cycle time for performing the pulp-dredging step, the first pre-compression forming step, and the compression thermo-forming step is less than 150 seconds per each of the at least one second semi-finished product object.

In the pulp molding process described above, each working cycle time for performing the pulp-dredging step, the first pre-compression forming step, and the compression thermo-forming step is less than 100 seconds per each of the at least one second semi-finished product.

In order to solve the aforementioned drawbacks of the prior art, the present invention provides a paper-shaped article made by the pulp molding process comprising:

a smooth inner surface having a surface smoothness of the inner surface about 8-10 seconds according to Bekk Smoothness measurement;

a smooth outer surface having a surface smoothness of the outer surface about 7-9 seconds according to Bekk Smoothness measurement; and

a cave having a transversal width equal to or greater than 0.5 mm but less than or equal to 8 mm.

In the paper-shaped article described above, a thickness of the paper-shaped article is 0.5 mm to 3 mm.

In the paper-shaped article described above, the paper-shaped article comprises a composite having at least one fiber material, the composite comprises 20 to 99 parts by weight of a superior short fiber material.

In the paper-shaped article described above, a fiber length of the superior short fiber material is greater than 0 mm and less than or equal to 0.8 mm.

In the paper-shaped article described above, the superior short fiber material is selected from the group consisting of synthetic fibers, regenerated fibers, nature fibers, microfibers, nanofibers and/or any combinations thereof.

In the paper-shaped article described above, each working cycle time for performing the pulp molding process including a pulp-dredging step, a first pre-compression forming step, and a compression thermo-forming step is less than 100 seconds per each of the paper-shaped article

The present invention has shown that the pulp molding process and the paper-shaped article made by the pulp molding process are able to solve the problem of the crosslinking effect of the wet pulp dredged up by the mold from paper slurry during the pulp-dredging stage and achieving a desirable combination of strength and the surface smoothness of the inner surface and the outer surface suited for the paper-shaped article.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, terms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top”, and “bottom” as well as derivatives thereof should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation, and do not limit the scope of the invention.

Referring toFIG. 2, which is a flowchart of a pulp molding process according to a first embodiment of the present invention.

A pulp molding process of the present invention comprises the following steps of:

S01: providing a composite having at least one fiber material, which comprises a superior short fiber material and a relatively longer fiber material;

S02: performing a pulp-dredging step of dredging a wet pulp body made of the composite, by one of a first upper mold and a first lower mold, from a slurry tank carrying a paper slurry containing the composite;

S03: performing a first pre-compression forming step on the pulp body to form at least one first semi-finished product with a first cave on a surface thereof, by and between the first upper mold and the first lower mold; and

S04: performing a compression thermo-forming step on the at least one first semi-finished product to form at least one second semi-finished product, by and between a second upper mold and a second lower mold;

The composite comprises 20 to 99 parts by weight of the superior short fiber material, and most preferably is 65 to 75 parts by weight of the superior short fiber material, for forming the paper-shaped article without formation of a crosslinking portion above the first cave201(shown inFIG. 6A) of the first semi-finished product101.

Besides, in this embodiment of the present invention, the process further comprises a step of performing an edge-cutting step S05for forming a shaped pulp article80(shown inFIG. 7).

Referring toFIG. 3, which is a flowchart of a pulp molding process according to the first embodiment of the present invention, which includes a pulp-dredging step, a first pre-compression forming step, a compression thermo-forming step, and an edge-cutting step for forming a paper-shaped article, that are respectively preformed in different working stages shown inFIG. 3.

In step S01, a fiber length of the superior short fiber material is greater than 0 mm and less than or equal to 1 mm. More precisely, a fiber length of the superior short fiber material is greater than 0 mm and less than or equal to 0.8 mm. Preferably, the fiber length of the superior short fiber material is 0.1 mm to 0.5 mm.

The superior short fiber material may be selected from the group consisting of a synthetic fiber such as polyethylene terephthalate (PET), nylon, polypropylene (PP) and polyethylene (PE), and/or a regenerated fiber such as rayon and tencel, and/or a nature fiber such as wood fiber and non-wood fiber, nature fibers, microfibers, nanofibers and/or any combinations thereof.

The pulp-dredging step and the first pre-compression forming step are performed in the same working stage applied in the pulp molding process. That is to say, the pulp-dredging step S02which is applied to collect/dredge up a pulp body200from a paper slurry tank100and further including a first pre-compression forming step S03which is applied on the dredged pulp body200by and between the first upper mold10and the first lower mold20, both kept in a first molding gap (not shown) therebetween, so as to form at least one first semi-finished product101, and a dryness of the first semi-finished product101is about 10%˜50%.

In the pulp-dredging step S02, a feeding shaft21is adapted for sinking the first lower mold20downward into the paper slurry tank100to collect/dredge up the pulp body200above the first lower mold20. Then, the first lower mold20is moved upward by the feeding shaft21to a predetermined position, and the first upper mold20is moved downward by a first vertical rack11in a close manner to the first lower mold20, accompanied with performing the first pre-compression forming step S03where the first upper mold10downwardly applies a first compressing force on the dredged pulp body by and between the first upper mold10and the first lower mold20, both kept in the first molding gap therebetween, so as to form the at least one first semi-finished product101.

The first semi-finished product101is suctioned by the first upper mold10, and the first upper mold10with the at least one first semi-finished product101is moved upward to an initial position of the pulp-dredging step. Then, the first upper mold20is horizontally conveyed by a first horizontal sliding rack12to convey and place the at least one first semi-finished product101over the third lower mold60.

It can be understood that the dredged pulp body200is formed on a surface of the first lower mold20. The first lower mold20has a shallow cave23(shown inFIG. 6A) corresponding to the first cave of the first semi-finished product101or corresponding to the cave201(shown inFIG. 6A) of the dredged pulp body200. A transversal width (inner diameter) of the shallow cave23is 1 mm to 8 mm.

Then, the compression thermo-forming step S04which is further applied on the at least one first semi-finished product101by and between the third upper mold50and the third lower mold60, both kept in a third molding gap (not shown) therebetween, and less than the first molding gap, so as to form at least one second semi-finished product102, and a dryness of the second semi-finished product102is about 50%-100%.

In the compression thermo-forming step S04, the third upper mold50is moved downward in a close manner to the third lower mold60, accompanied with applying a third compressing force on the at least one first semi-finished product101by and between the third upper mold50and the third lower mold60, both kept in the third molding gap therebetween and less than the first molding gap.

In addition, the at least one first semi-finished product101is heated by a heater (not shown) located above the third lower mold60, drawing the water/vapor out from the at least one first semi-finished product101between the third upper and third lower molds50,60, so as to form the at least one second semi-finished product102. Then, the third upper mold50with the at least one second semi-finished product102is conveyed to perform the edge-cutting step by a third horizontal sliding rack62.

The edge-cutting step S05which is further applied on the at least one second semi-finished product102by a chopper70to form the paper-shaped article80(shown inFIG. 7).

For eliminating the crosslinking effect and manufacturing the paper-shaped article having high aesthetics, in addition to adapting the superior short fiber material for forming the paper-shaped article, the composite comprises an additive which comprises a water retention agent and a paper strength agent, further for increasing the printability and dry strength of the paper-shaped article. Furthermore, in different embodiments of the present invention, the relatively longer fiber material can comprise a shorter fiber material and/or a longer fiber material, each of which is longer than the superior short fiber material in fiber length. Besides, the composite comprises less than 50 parts by weight of the relatively longer fiber material. Thus, the paper-shaped article has a Canadian standard freeness is about greater than 300 csf, preferably 470 csf to 550 csf.

In the first preferred embodiment of the present invention, the paper-shaped article is made of at least one high freeness composite for increasing the freeness and the drainability of the composite.

Referring toFIG. 4, which is a flowchart of a pulp molding process according to a second embodiment of the present invention, and referring toFIG. 5, which is a flowchart of a pulp molding process according to the second embodiment of the present invention, which includes a pulp-dredging step, a first pre-compression forming step, a second pre-compression forming step, a compression thermo-forming step, and an edge-cutting step of the pulp molding process, for forming a paper-shaped article.

The difference between the second preferred embodiment and the first preferred embodiment is that before the compression thermo-forming step S04and after the first pre-compression forming step S03, the process further comprises a second pre-compression forming step S031applied on the at least one first semi-finished product101by and between a second upper mold30and a second lower mold40.

More specifically, the first semi-finished product101is suctioned by the first upper mold10, and the first upper mold10is moved upward to an initial position of the first pre-compression forming step. Next, the first upper mold10with the first semi-finished product101is horizontally conveyed by the first horizontal sliding rack12to place the first semi-finished product101over the second lower mold40, instead of the third lower mold60of the first preferred embodiment. Then, the second upper mold30is moved downward by a second vertical sliding rack31in a close manner to the second lower mold40, accompanied with applying a second compressing force on the first semi-finished product101by and between the second upper mold30and the second lower mold40, both kept in the second molding gap therebetween and less than the first molding gap.

Simultaneously, the first semi-finished product101is heated by a heater (not shown) located above the second lower mold40, drawing the water/vapor out from the first semi-finished product101between the second upper and second lower molds30,40, so as to form the first semi-finished product102. Then, the second upper mold30with the first semi-finished product102is conveyed to perform the compression thermo-forming step by a second horizontal sliding rack32.

Thus, the second pre-compression forming step can increase the drying efficiency of the first semi-finished product101and reduce the time consumption of processing the following compression thermo-forming step in thermo-forming the second semi-finished product102.

Referring toFIGS. 6A-6D, which are schematic views of a transversal width of a cave of an object made by the pulp molding process according to the second embodiment of the present invention, including a pulp-dredging step, a first pre-compression forming step, a second pre-compression forming step, and a compression thermo-forming step of the pulp molding process, for forming a paper-shaped article. Also refer toFIG. 7, which is a schematic view of the paper-shaped article made by the pulp molding process according to the present invention.

In a conventional molding process and molding articles made thereby, a crosslinking effect always occurs to form a crosslinking portion in the cave/groove3(shown inFIG. 1), so that the wet pulp5(shown inFIG. 1) does not form a cave at the position of the molding article corresponding to the cave/groove3rather than forming a crosslinking portion4(the dotted line shown inFIG. 1).

Unlike the conventional molding process and molding article, the pulp molding process according to the present invention mentioned above can solve the technical problem of the conventional molding process and molding articles made thereby. Moreover, a paper-shaped article80(shown inFIG. 7) made by the pulp molding process according to the present invention does not have the crosslinking portion produced by the crosslinking effect. The paper-shaped article80(shown inFIG. 7) composed by a composite having at least one fiber material as mentioned above can solve the technical problem of the crosslinking effect. In this embodiment, the paper-shaped article80comprises a fourth cave1021(shown inFIG. 6D) having a transversal width w4 equal to or greater than 0.5 mm but less than or equal to 8 mm, and preferably greater than or equal to 6 mm and less than or equal to 8 mm.

Referring toFIG. 7. The paper-shaped article80further comprises: a smooth inner surface81having a surface smoothness of the inner surface about 8-10 seconds (according to Bekk Smoothness measurement); a smooth outer surface82having a surface smoothness of the outer surface about 7-9 seconds (according to Bekk Smoothness measurement) so that the paper-shaped article80manufactured by the pulp molding process according to the present invention is highly aesthetic.

Furthermore, a thickness of the paper-shaped article80is 0.5 mm to 3 mm.

Referring toFIG. 6AandFIG. 3, in the first pre-compression forming step, the first semi-finished product101formed on a surface of the first lower mold20comprises the first cave201having a transversal width w1 greater than 0 mm and less than 8 mm. It is noted that the first lower mold20has a shallow cave23corresponding to the first cave201of the first semi-finished product101. A transversal width (inner diameter) of the shallow cave23is 1 mm to 8 mm.

Referring toFIG. 6BandFIG. 3, in the second pre-compression forming step, the first semi-finished product101placed on the surface of the second lower mold40comprises a second cave1011having a transversal width w2 of from 6 mm to 8 mm. It is noted that the second lower mold40has a shallow cave43corresponding to the second cave1011of the paper-shaped article80or corresponding to the second cave1011of the first semi-finished product101. A transversal width (inner diameter) of the shallow cave43is 1 mm to 8 mm.

Referring toFIG. 6CandFIG. 3, in the compression thermo-forming step, the first semi-finished product101placed on the surface of the third lower mold60comprises a third cave1012having a transversal width w3 of from 6 mm to 8 mm. It is noted that the third lower mold60has a shallow cave63corresponding to the third cave1012of the second semi-finished product101. A transversal width (inner diameter) of the shallow cave63is 1 mm to 8 mm.

Referring toFIG. 6DandFIG. 3, after performing the compression thermo-forming step, the at least one second semi-finished product102placed on the surface of the third lower mold60is to be performed the edge-cutting step to form at least one paper-shaped article80with the fourth cave1021wherein the fourth cave1021has a transversal width w4 of from 0.5 mm to 8 mm.

The present invention has disclosed that the pulp molding process and the paper-shaped article made by the pulp molding process are able to solve the problem of the crosslinking effect of the dredged pulp body dredged up by the first lower mold from the paper slurry during the pulp-dredging step and achieving a desirable combination of strength and the surface smoothness of the inner surface and the outer surface suited for the paper-shaped article.

The present invention has been described with preferred embodiments thereof, and it is understood that many changes and modifications to the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.