KR20070066289A - An apparatus and a method of producing pulp-moulded products - Google Patents

Abstract

A method and an apparatus for manufacturing pulp-molded products are provided to increase the productivity and improve the quality of the products, by installing a light transmitting member for transmitting liquid of slurry in a container and applying a positive gauge pressure to the light transmitting member. A container(102) has a liquid transmitting member(106) installed therein. A slurry(112) of fibers and liquid is inputted into the container. A positive type gauge pressure is applied onto the slurry to push out a portion of the liquid in the slurry through the liquid transmitting member, thereby forming fiber layers on the liquid transmitting member. The gauge pressure is supplied by compressed air. The liquid transmitting member has a porous structure.

Description

An Apparatus and a Method of Producing Pulp-Moulded Products

1 shows steps in a conventional forming process for the production of pulp-formed outputs;

2 shows the change (corrosion) of the vacuum force of a vacuum tank during the circulation of a conventional forming process;

3 shows a partial cross-sectional view of a device according to a first embodiment of the present invention;

4A shows the drainage of fibers through the mesh for the initial high water flow rate;

4B shows the precipitation of fibers in the network for the initial low water flow rate;

5A is a cross-section of the shape of a pulp-molded output produced according to a conventional forming process obtained through an electron microscope;

FIG. 5B is a cross-sectional shape of a pulp-molded output produced according to the forming process according to the present invention obtained through an enlarged electron microscope as in FIG. 5A;

FIG. 6 shows a plot of possible variations in pressure provided by compressed air in the apparatus shown in FIG. 3 at slurry over time, comparing the over time variation (corrosion) of the suction force in a conventional vacuum formation process; FIG.

7 is a sectional view of an apparatus according to a second embodiment of the present invention;

8 is a sectional view of an apparatus according to a third embodiment of the present invention;

9 is a sectional view of an apparatus according to a fourth embodiment of the present invention;

10 is a sectional view of an apparatus according to a fifth embodiment of the present invention; And

11 shows the hot pressure apparatus used in the pulp-molding process.

FIELD OF THE INVENTION The present invention relates to methods and apparatuses for producing pulp-molded outputs, and in particular, to methods and apparatuses such as performing improved formation / configuration in a pulp-molding process.

Pulp is used today for primarily degradable properties, for example in the manufacture of many products of food containers, liquid containers or packing materials. There are two main methods of making these outputs. In the drying method, the containers are made by sandwiching and connecting various adjacent wings from a flat piece of dry cardboard. The method is cumbersome and expensive. The resulting product is also not completely sealed. With regard to the wet method, the wet pulp is contoured to the final output and then dried to form the final output. Thus the resulting output is generally completely formed to an even thickness.

Conventional wet methods are generally divided into six main steps, i.e., cutting step, fine engraving step, mixing step, forming step, cold compression step and hot compression step. In the cutting step, fresh paper and water made from plant fibers such as wood fibers, bamboo or stems are fed into the mixer which breaks down the paper. In the fine engraving step, the fiber decomposed in the cutting step is further mixed with water and the fiber and fed into a processing apparatus to freely orient the plant fiber in a thin slurry. The contents are then fed to a second mixing device with additives such as water repellents, oil sealants, etc. to adjust the properties of the plant fiber according to the output produced in the mixing step. In the forming step, also called the constructing step, the plant fibers and the additive slurry are inserted into the chamber and supported by the lower mold and the mesh formed on top of it. Water is discharged from the wet plant fibers by vacuum supplied from below the mash. The material to be similar in structure to the wet tissue paper in this step is then compressed between the upper mold and the lower mold to further compress some remaining water in the subsequent cold compression step. After this step, the material will be formed into the configuration and shape of the final output. The cold-compressed output will be placed between a pair of hot molds for hot compression. The output will be heated by hot molds between 150 ° C. and 180 ° C. for about 45 to 60 seconds to completely dry the outputs.

Regardless of the type of machine used to produce the pulp-formed outputs, that is, continuous form or batch processing machine, production workload is found to be highly dependent on the time spent in the forming step. Depending on the contours of the deliverables, the forming step of the match processing machine will take 20 to 60 seconds. In the continuous form, although the forming step is faster than the batch processing form, the forming step is still the longest time step in the machine than any other step. For a typical 600 ml food container produced in a batch system, the forming step will generally take about 45 seconds.

During the forming step, and in the form of a suspension, shown in FIG. 1, the thin fiber slurry is poured into the container with its underlying mesh or porous material. The slurry will then settle. By applying vacuum suction from underneath the network, water will be discharged through the mesh and down the slurry, and the initial layers of the fiber will be defined and placed on the network, creating a wet layer of fiber mat. . After the forming process the fiber mat will then be cold-compressed to form the shape of the initial pulp before the final hot compression.

The use of the vacuum withstands the following drawbacks:

(i) The maximum difference in compression that can cause absorption and release of water from the slurry through the mesh is limited to a negative 1 bar (ie 1 kg / cm 2).

(ii) Suction pumps and vacuum tanks are mostly required.

(iii) The vacuum tank has to be supplied into the vacuum tank at regular intervals because of the suction of water to maintain the suction performance. This requires any step of (a) a stop time period in which the vacuum is stopped, (b) the water is drained from the tank, and (c) the vacuum is supplied again. Alternatively, additional pumps are installed to continuously discharge water from the tank. For the previous method, the system would be meaningless during downtime, thus affecting the workload. For subsequent methods, the complexity and cost of the system will be increased.

(iv) As shown in FIG. 2, as the fiber precipitates on top of the mesh, vacuum corrosion will develop a drawback of excess time, thus increasing the time required for the formation process. This is also prominent in the repetitive use of the mesh in the formation process, and the tiny holes in some of the mesh will be clogged with fibers. Thus, the tiny holes in the network become clogged so that very little water can pass through, so the performance of the vacuum will also exacerbate the overtime.

(v) In view of the problem described in (iv) above, the network will be required to provide for maintaining the productivity of the machine and the quality of the outputs and to maintain certain prevention.

It is therefore an object of the present invention to provide a method and apparatus for the production of pulp-formed outputs with the aforementioned drawbacks reduced, or at least to provide a useful alternative to the public.

According to a first aspect of the invention, there is provided a method comprising the steps of: (a) providing a container having at least one liquid permeable end; (b) placing a slurry containing fibers and liquid into the vessel; And (c) applying a positive pressure gauge over said slurry to said liquid force at least a portion of said liquid in said slurry within said chamber via said liquid permeable end to form said fibrous layers above said liquid permeable end. A method of forming a pulp-molded article is provided.

According to a second aspect of the invention, there is provided a container for containing a slurry containing fibers and liquids, the container having at least one liquid permeable end, and a positive pressure gauge on the slurry through the liquid permeable end and within the chamber. Apparatuses for forming pulp-formed outputs are provided that include a device for applying the force of at least a portion of the liquid in a slurry to form the fiber layer over the liquid permeable end.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings:

1 shows steps in a conventional forming process for the production of pulp-formed outputs;

2 shows the change (corrosion) of the vacuum force of a vacuum tank during the circulation of a conventional forming process;

3 shows a partial cross-sectional view of a device according to a first embodiment of the present invention;

4A shows the drainage of fibers through the mesh for the initial high water flow rate;

4B shows precipitation of fibers in the network for the initial low water flow rate;

5A is a cross-section of the shape of a pulp-molded output produced according to a conventional forming process obtained through an electron microscope;

FIG. 5B is a cross-sectional shape of a pulp-molded output produced according to the forming process according to the present invention obtained through an enlarged electron microscope as in FIG. 5A;

FIG. 6 shows a plot of the possible variation in the pressure provided by the compressed air in the apparatus shown in FIG. 3 at the slurry over time, comparing the over time variation (corrosion) of the suction force in a conventional vacuum formation process;

7 is a sectional view of an apparatus according to a second embodiment of the present invention;

8 is a sectional view of an apparatus according to a third embodiment of the present invention;

9 is a sectional view of an apparatus according to a fourth embodiment of the present invention;

10 is a sectional view of an apparatus according to a fifth embodiment of the present invention; And

11 shows the hot pressure apparatus used in the pulp-molding process.

Referring to FIG. 3, a device according to the first embodiment of the present invention is generally designed such as 100, using a "pressure-time" forming process. The device 100 includes a pressure chamber 102 with a conduit 104 at the top end and a wire mesh or porous material 106 at the lower end. Mesh 106 or less is a forming mold 108 (which must be made of metal) in which a porous structure or channels are installed to allow a liquid such as water to pass out of the chamber 102. The conduit 104 is connected to a high pressure source such as, for example, compressed air 110, to apply a fiber-containing instrument pressure in the form of slurry 112 contained in the chamber 102.

In order to carry out the forming process according to the invention, the slurry 112 is injected into the chamber 102 via, for example, an inlet (not shown) of the side wall of the chamber 102. The source of compressed air 110 is then facilitated by blowing compressed air at a meter pressure of, for example, up to 10 kg / cm 2 through conduit 104 into the chamber 102 to apply a positive meter pressure of slurry 112. Positive gauge pressure will drive water out of slurry 112 in device 100 through mesh tissue 106 and then through mold 108. During the outflow of water from the chamber 102, the fibers in slurry 112 will then be placed and determined on the network 106 to form layers of fibers for cold-compression.

There are three variables that can be adjusted to control the formation process. That is, (a) the pressure of the compressed air, (b) the time the pressure is supplied, and (c) the flow rate of the compressed air into the chamber 102. The flow rate of compressed air is an important function of the pressure supplied and the resistance of the overall system. The resistance of the entire system depends on the geometry of at least a portion of the network, such as the size of the small holes and the number of small holes in the network. The outflow rate of water, and thus the overall formation time, can be controlled by adjusting one or more of the three variables. In this regard, it is relatively easy to adjust and control the variables (a) and (b), and the variable (c), although to a lesser extent, can also be adjusted and controlled. This is in stark contrast to the conventional method of supplying a vacuum to the slurry, in which a small number of adjustments can be carried out without waiting for the completion of the supply and formation of the vacuum.

Three types of water removal mechanisms that can be operated around and above the network 106 are already known. In the filtration form, the fibers of slurry 112 move freely around slurry 112. In the concentration method, the fibers in slurry 112 weaken and compact into a coherent mesh structure with the progress of the drained water. Finally, in intense concentration, the previous two types of machinery are mixed.

In the conventional vacuum forming process shown in FIG. 4A, a strong vacuum is initially supplied through the mesh 154 which will cause a high initial outflow rate of water and intense concentration of the fiber 150 in the slurry 152. Therefore, the fibers 150 will not have enough time to level themselves, so many small fibers 150 will be lost for drainage through the tiny holes 153 of the mesh 154 as shown in FIG. 4A. The loss of fibers and additives will be significant for high initial water flow rates. For the purpose of alleviating this problem, chemical maintenance aids are used to prevent the reduction of fibers and particulates in the drained water at high initial flow rates. On the other hand, in the process according to the invention, the amount of pressure supplied to the slurry will be initially assigned relatively low, resulting in a relatively low initial flow rate of water exiting the slurry as shown in FIG. 4B. Low initial flow rates will reduce accidental non-horizontally directed fibers lost through drainage.

In a conventional vacuum forming process, when the initial layers of fiber are formed on a mesh or small pore, the water in the slurry acts as a resistance to pass before draining. As the number of layers of the fiber increases, and thus the thickness, the effective suction force (ie, so-called "vacuum") will drop, and thus the compressive force on top of the layers of the fiber will gradually decrease.

FIG. 5A shows a cross-sectional image of a pulp-formed output made according to a conventional vacuum forming process, obtained with a scanning electron microscope (SEM). It can be clearly seen that the lower layers are more compressed than the upper layers. The structure is not suitable for waterproofing outputs, where water can seep into the top layers and pass through the lower layers due to osmotic pressure and thus cause failure. With the sudden change in vacuum suction force, the density of the upper layers follows a random pattern.

On the other hand, FIG. 5B shows a cross-sectional image of a pulp-formed output produced according to the forming process according to the invention, obtained by scanning electron microscope with the same magnification as shown in FIG. 5A. The output was formed by applying a pressure trend with a meter pressure of approximately up to 4 bar. It can be seen that all fibrous layers are formed at essentially the same degree of pressure from the top layers to the lower bottom layers. It should also be noted that the thickness of the two pulp-formed outputs shown in FIGS. 5A and 5B. The amount of fibers used in the production of the two outputs, and their final weight, are very much the same. However, it can be more clearly seen that the output formed under the conventional vacuum suction forming process is almost 10% to 15% thicker than the output produced under the forming process according to the present invention. This concludes that the use of positive gauge pressure results in a more uniform and tightly finished output. Thus, a product made with a uniform pressure uniformity used for waterproofing purposes can be formed by the apparatus and method according to the invention.

In detail and as described above, the pressure of the air compressed in the apparatus 100, the time during which the pressure is supplied, and the flow rate of the air compressed into the chamber 102 are all independently controlled. As shown in FIG. 6, the possible process pressure trend diagram will be pre-adjusted. The diagram shows a relatively small gauge pressure that is initially fed for 1 second, thus causing a small initial flow rate of water in the slurry 122 through the mesh 106, for example significantly less than 1 bar. This will reduce interference and fiber loss during the initial formation phase. The diagram also allows sufficient time for the fibers facing horizontally to form good initial layers. Once the initial layers are formed, a higher gauge pressure, for example up to 3 bar, will be supplied for 1 second to facilitate the outflow of water through the network 106. Application of a higher gauge pressure of slurry 122 will also produce top layers of more compacted fibers compared to the outputs produced under conventional vacuum forming processes. Then, a lower gauge pressure, such as 2 bar or 1 bar, is supplied for 1/2 second and 1/4 second, respectively. It can also be seen that the time required for completing the forming process according to the invention is considerably less than that required under conventional methods.

The invention will be used in conjunction with the application of a vacuum to help achieve higher densities, shorter formation times and more uniform layers of result output. For example, if a total of 4 bar gauge pressure is applied for the forming process, it will be supplied alone by applying pressure using compressed air. However, it is better to have a strong chamber that is well sealed to withstand such high pressures. As an alternative, it is also possible to apply a gauge pressure of 3 bar with compressed air and a suction vacuum of 1 bar simultaneously. In this case, rather than withstanding 4 bar gauge pressure, the chamber now needs to withstand only 3 bar gauge pressure.

With reference to FIG. 7, the devices according to the second embodiment of the present invention are the device 200 which makes the formation process called “displacement-volumetric” or “positive displacement” used. Rather, it usually shows the specified device. In the apparatus 200, the piston 202 is provided in the chamber 204 containing the slurry. The piston 202 pushes the piston 202 which presses over the slurry 208 to drive water out of the slurry 208 through the mesh or porous material 210 supported by the lower metallic mold 212 of the porous structure; Effectively combined. The movement of the piston 202 can be pre-adjusted, for example by a microprocessor, to connect the motor and screw assembly 202 to create a predetermined pressure change or trend chart of pressure during the forming step. It is therefore possible to pre-adjust the time for the meter pressure to be supplied and the magnitude of the meter pressure supplied over the slurry. It is of course also possible to pre-adjust the time for each magnitude of the meter pressure to be supplied, and the magnitude change of the meter pressure supplied, over the slurry during the progress of the forming step. The pressure trend chart will also be adjusted to the needs of the process based on commissioning and errors.

Devices according to a third embodiment of the present invention are shown in FIG. 8 and are generally referred to as device 300. The device 300 is similar to the device 100 described above except that a feedback-response mechanical device is provided. Specifically, the first traveling valve 302 is provided downstream of the network 304. The first traveling valve 302 may detect the flow rate of water and transfer control feedback signals to the second downstream valve 306 downstream of the source of compressed air 308. Thus, by means of the above arrangement, if the flow rate of water through the first flow valve 302 is too slow, the flow rate of water through the mesh 304 is increased to supply a higher gauge pressure on the slurry 310 of the chamber 312. The two-way valve 306 will be able to supply more compressed air from the source 308 for passage. It will also have an effective force to erase some of the inhibitory elements in the mesh 304. Conversely, if the flow rate of water through the first flow valve 302 is too high, the second flow valve 306 may pass through to supply a lower gauge pressure over the slurry 310 of the chamber 312 where the flow rate of water through the mesh 304 is reduced. Will be adjusted to supply less compressed air from source 308.

An apparatus according to a fourth embodiment of the invention is shown in FIG. 9 and is generally referred to as apparatus 400. The device 400 is similar to the device 200 described above, except in the case of the device 300 described above where a feedback-response mechanism is provided. Specifically, the flow valve 402 is provided downstream of the network 404. The flow valve 402 transmits control feedback signals for detecting the flow rate of water and controlling the operation of the motor and screw assembly 406. Thus, by the method of the arrangement, if the flow rate of water through the progress valve 402 is too low, the motor and screw to supply a higher gauge pressure over the slurry 412 of the chamber 410, which reduces the outflow rate of water through the mesh 404. Assembly 406 will be adjusted to move piston 408 more quickly towards mesh 404. Conversely, if the flow rate of water through the flow valve 402 is too high, to move the piston 408 more slowly in the chamber 410 to supply a lower gauge pressure over the slurry 412 of the chamber 410, which reduces the rate of outflow of water through the network 404 Will be adjusted.

In the conventional method of forming pulp-molded output, once the forming step is completed, the wire mesh and fiber layers formed thereon are transferred to a cold compression machine, including an upper mold and a lower mold. The cold compression is then compressed into the fiber layers to further reduce the water content of the fiber layers. The device for performing the "Positive Displacement" formation method would be an additional modification that could also carry out a cold-compression step. The device, shown in FIG. 10 and generally referred to as device 500, is similar to the devices 200 and 400 mentioned above. The lower end 501 of the piston 502 is contoured to correspond to or coincide with the upper contour produced to be finally formed. For the above mentioned devices 100, 200, 300 and 400, the mesh or porous material 504 and the lower mold 510 (made of metal) are also contoured corresponding to or corresponding to the lower contour of the output to be finally formed. . The piston 502 thus moves downward to compress over the slurry 507 in the forming chamber 508 to perform the forming step. After the forming step, the motor and screw assembly 506 continues to move the piston 502 further downwards to perform the cold-compression process. Thus, one step of the conventional pulp forming process is eliminated and the mold set is also saved. After the combined formation and cold-compression steps shown in FIG. 11, the cold-compressed fibers supported by the mesh 504 and the mold 510 will be hot-compressed by the upper mold 520 to complete the pulp molding process.

It is to be understood that the above embodiments are merely illustrative of the embodiments carried out by the present invention, and that various modifications and / or alternatives may be made therein without departing from the principles of the invention.

For clarity, it should also be understood that certain features of the invention, described in the context of each embodiment, are provided in combination with a single embodiment. On the other hand, for the sake of brevity, the various features of the invention described in the context of a single embodiment will also be provided separately or in any suitable sub-defect.

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Claims (34)

(a) providing a container having at least one liquid permeable end; (b) inserting a slurry of fibers and liquid into the vessel; And (c) supplying a positive meter pressure over said slurry to push said liquid of at least a portion of said slurry in said chamber through said liquid permeable end to form layers of said fiber over said liquid permeable end A method of forming a pulp-molded article comprising a. The method of claim 1, Wherein the gauge pressure is provided by a compressed gas, Method of Forming Pulp-Formed Articles. The method of claim 2, characterized in that the gas is air, Method of Forming Pulp-Formed Articles. The method of claim 1, The positive gauge pressure is the pressure of the air, Method of Forming Pulp-Formed Articles. The method of claim 1, Wherein said liquid permeable end comprises a porous configuration, Method of Forming Pulp-Formed Articles. The method of claim 5, Characterized in that the porous portion comprises a mesh tissue, Method of Forming Pulp-Formed Articles. The method of claim 1, (d) supplying a gauge pressure of a first magnitude over said slurry; And (e) subsequently supplying a second pressure gauge pressure different from the first pressure gauge pressure on the slurry. Including, Method of Forming Pulp-Formed Articles. The method of claim 1, The gauge pressure of the first magnitude is supplied over the slurry for a first time and the gauge pressure of the second magnitude is supplied over the slurry for a second time different from the first time, Method of Forming Pulp-Formed Articles. The method of claim 7, wherein (f) subsequently supplying a gauge pressure of a third magnitude different from the gauge pressure of the second magnitude onto the slurry Further comprising, Method of Forming Pulp-Formed Articles. The method of claim 1, (g) detecting the flow rate of the liquid in the chamber through the liquid permeable end Further comprising, Method of Forming Pulp-Formed Articles. The method of claim 9, Varying the magnitude of the meter pressure supplied over the slurry in response to the flow rate of the liquid in the chamber through the liquid permeable end Further comprising, Method of Forming Pulp-Formed Articles. The method of claim 1, Characterized in that the gauge pressure is supplied by a piston configuration, Method of Forming Pulp-Formed Articles. The method of claim 12, (i) forming a lower end vessel of the piston configuration to generally coincide with the vessel top of the article Further comprising, Method of Forming Pulp-Formed Articles. The method of claim 13, (j) compressing the piston configuration over the layers of the fiber above the liquid permeable end Further comprising, Method of Forming Pulp-Formed Articles. The method of claim 1, (k) pre-determining the magnitude of the meter pressure supplied over the slurry Further comprising, Method of Forming Pulp-Formed Articles. The method of claim 1, (l) pre-determining the time that meter pressure is supplied over the slurry Further comprising, Method of Forming Pulp-Formed Articles. The method of claim 1, (m) supplying suction from below or below the liquid permeable end to withdraw the liquid of at least a portion of the slurry in the chamber through the liquid permeable end; Further comprising, Method of Forming Pulp-Formed Articles. A container for containing a slurry of liquid and fibers having at least one liquid permeable end, and a positive amount over the slurry in the container to push the liquid of at least a portion of the slurry in the chamber through the liquid permeable end Including all devices for supplying meter pressure, thereby forming layers of the fiber on the liquid permeable end, Pulp-molded products manufacturing apparatus. The method of claim 18, Further comprising a conduit adapted to be connected to a source of compressed gas, Pulp-molded products manufacturing apparatus. The method of claim 19, Characterized in that the gas is air, Pulp-molded products manufacturing apparatus. The method of claim 18, The gauge pressure is characterized in that more than 1kg / ㎠, Pulp-molded products manufacturing apparatus. The method of claim 18, Wherein the liquid permeable end comprises a porous configuration, Pulp-molded products manufacturing apparatus. The method of claim 22, Characterized in that the porous configuration comprises a mesh tissue, Pulp-molded products manufacturing apparatus. The method of claim 18, Wherein the pressure supply devices are adapted to supply a gauge pressure of a first magnitude onto the slurry, and that the gauge pressure of a second magnitude different from the gauge pressure of the first magnitude is subsequently adapted onto the slurry. doing, Pulp-molded products manufacturing apparatus. The method of claim 24, Wherein said pressure supply devices are adapted to supply a gauge pressure of said first magnitude for a first time and adapted to supply a gauge pressure of said second magnitude for a second time different from said first time. doing, Pulp-molded products manufacturing apparatus. The method of claim 24, Said pressure supply devices being adapted to subsequently supply a gauge pressure of a third magnitude different from said pressure of said second magnitude, Pulp-molded products manufacturing apparatus. The method of claim 18, Further comprising devices for detecting the flow rate of said liquid in said chamber through said liquid permeable end, Pulp-molded products manufacturing apparatus. The method of claim 27, Further comprising devices for varying the magnitude of the meter pressure supplied over the slurry in response to the flow rate of the liquid in the chamber through the liquid permeable end detected by the detection devices, Pulp-molded products manufacturing apparatus. The method of claim 18, Further comprising a piston configuration, Pulp-molded products manufacturing apparatus. The method of claim 29, Characterized in that the container at the lower end of the piston configuration generally corresponds to the upper container of the article, Pulp-molded products manufacturing apparatus. The method of claim 30, Wherein said piston configuration is movable to compress over said layers of said fiber above said liquid permeable end, Pulp-molded products manufacturing apparatus. The method of claim 18, Devices for supplying suction force from below the liquid permeable end to withdraw the liquid at least at least a portion of the slurry in the chamber through the liquid permeable end; Pulp-molded products manufacturing apparatus. 3, 4B, and 6 to 10 of the accompanying drawings and fully described herein, Pulp-molded article formation method. 3, 4B, and 6 to 10 of the accompanying drawings and fully described herein, Pulp-molded products manufacturing apparatus.

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