A wet pressing method for preparing plant fiber containers using high-pressure gas extrusion molding.

Abstract

This invention relates to the field of pulp molding technology, specifically to a wet pressing method for preparing plant fiber containers using high-pressure gas extrusion molding. This method employs high-pressure gas extrusion technology, combining precisely processed plant fiber boards with pulp to form containers with high strength and stability. The preparation process includes key steps such as precise processing of the plant fiber boards, pulp injection, compression, drying, and molding. During the pulp injection stage, a slow wire cutting machine ensures the molding die has an accuracy within 1 mil, and water holes are provided on the die to facilitate pulp entry and exit. During the compression stage, high-pressure compressed air rapidly expands the inner bladder, reducing the moisture content of the wet preform to approximately 70%, giving the container excellent strength and stability. The final product exhibits excellent tensile, flexural, and compressive strength. This container preparation method is widely applicable to applications requiring high strength and stability, providing reliable technical support for the preparation of environmentally friendly and high-performance containers.

Description

Technical Field

[0001] This invention relates to the field of pulp molding production technology, and in particular to a wet pressing method for preparing plant fiber containers using high-pressure gas extrusion molding. Background Technology

[0002] Previously, one-step pulp molding production was mainly used for products with a positive draft angle, where the opening gradually increases from the bottom of the product upwards, facilitating the opening and closing of the upper and lower molds. For products with a negative draft angle, i.e. bottle-shaped containers where different parts of the container are of varying sizes, an inner liner airbag can be inserted and inflated under positive pressure. This causes the inner wall of the airbag to be squeezed against the outer mold, completing the one-step molding process of dehydration, hot pressing, and shaping. However, depending on the shape of different bottle-shaped paper-plastic containers, in order to avoid the airbag scratching the inner wall of the pulp during insertion and inflation, resulting in defective products, the insertion of the inner liner airbag is still done manually. This results in a relatively slow efficiency of the inner liner airbag insertion, inflation, and extrusion actions during the dehydration, hot pressing, and shaping processes of bottle-shaped paper-plastic containers.

[0003] This process technology is a completely new production process. The traditional production process is an open vacuum adsorption molding process, while this production process is a closed high-pressure compressed air inner bladder support molding method. The molding process is high-pressure molding from the inside to the outside. The traditional method is direct unidirectional positive angle demolding. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a wet pressing method for preparing plant fiber containers by high-pressure gas extrusion molding, so as to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention provides a wet pressing method for preparing plant fiber containers using a high-pressure gas extrusion molding process.

[0006] A method for wet pressing of plant fiber containers using high-pressure gas extrusion molding includes the following steps:

[0007] Step 1: Use a slow wire EDM machine to precisely process the plant fiber board, ensuring that the precision of the upper and lower forming molds is within 1 micrometer. Simultaneously, machine water holes into the forming molds to facilitate the entry and exit of subsequent slurry.

[0008] Step 2: Fix metal mesh on the surface of the upper and lower molding molds for slurry adsorption and vacuum suction, ensuring that the slurry can be evenly distributed in the mold to form a uniform wet blank.

[0009] Step 3: Connect the movable vacuum line and the steam-water separator to the upper and lower molding dies to ensure the normal operation of the vacuum system.

[0010] Step 4: Place the highly elastic expansion bladder inside the lower mold of the molding die so that when the upper and lower molds are joined, the bladder is located between the two mold pieces, ensuring the formation of the wet preform.

[0011] Step 5: When the upper and lower forming molds are combined, the slurry tank automatically rises, and the slurry is poured into the cavities of the upper and lower molds through the slurry inlet buckle at the front of the combined mold. At the same time, the pneumatic vacuum system is activated to suck the slurry onto the metal mesh of the upper mold. The slurry pouring time is approximately 5-10 seconds, and the suction time is approximately 7-12 seconds depending on the product thickness.

[0012] Step Six: When vacuum adsorption is started, the cylinder push rod with sealing gasket pushes the sealing gasket to the grouting hole, making the mold cavity a sealed state to prevent grout leakage.

[0013] Step 7: After grouting is completed, the grout box automatically returns to its original position. Start the high-pressure compressed air system, injecting 12 MPa compressed air into the telescopic air bladder. This causes the air bladder to expand and compress the wet preform adsorbed onto the metal mesh, reducing the moisture content of the wet preform to approximately 70%. The compression time is approximately 6-10 seconds.

[0014] Step 8: After extrusion, the gas inside the airbag is released through the exhaust valve, causing the telescopic airbag to shrink back to its original state. At the same time, the upper mold of the forming mold returns to its original position, and the shrunken inner bladder is manually removed.

[0015] Step 9: Take out the wet blank after it has been formed and filtered, and place it in the lower mold of the hot press drying mold. At the same time, place the inner bladder of the hot press drying mold inside the wet blank.

[0016] Step 10: After placing the inner bladder, start the hot pressing process to merge the upper and lower molds. By introducing compressed air at a pressure of 20 MPa, the air bladder squeezes the wet preform, reducing the moisture content from 70% to below 10%. The squeezing and hot pressing time is approximately 40-55 seconds, depending on the product thickness.

[0017] Step 11: The hot-pressed upper mold returns to its original position, the dried container is manually removed, inspected, packaged, and finally the product is put into storage.

[0018] The beneficial effects of this invention are:

[0019] 1. This invention can mold closed-cavity bottle products in one step without secondary splicing, reducing production steps and reducing production costs by 2,000 yuan per ton compared to traditional processes.

[0020] 2. The present invention is integrally molded in one piece with a seamless appearance, which is more aesthetically pleasing and facilitates surface printing or the application of waist seals.

[0021] 3. After the entire seamless molding process of this invention, the liquid contained within will not leak, and it can hold a variety of chemical solutions such as ordinary beverages, oils, milk, and laundry detergent.

[0022] 4. The technology of this invention completely breaks through the limitations of traditional technology in producing negative angle products. It can manufacture closed containers such as bottles and cans, and there is a huge market demand for bottled and canned products such as laundry detergent. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the process structure of an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0026] Example 1:

[0027] Step 1:

[0028] The wire EDM machine precisely processes plant fiberboard, ensuring the accuracy of the upper and lower forming dies is between 0.5 and 1 mil. Simultaneously, it processes water holes in the forming dies with diameters between 1 and 3 millimeters.

[0029] Step 5:

[0030] The grouting time is approximately 8 seconds, and the suction time is between 8 and 10 seconds, depending on the product thickness.

[0031] Step Seven:

[0032] The extrusion time is approximately 8 seconds, reducing the moisture content of the wet preform to between 65% and 70%.

[0033] Step 10:

[0034] The extrusion and hot pressing time is between 45 and 50 seconds, depending on the product thickness.

[0035] Example 2:

[0036] Step 1:

[0037] The wire EDM machine precisely processes plant fiberboard, ensuring the accuracy of the upper and lower forming molds is between 0.8 and 1.2 microns. Simultaneously, it processes water holes in the forming molds with diameters between 2 and 4 millimeters.

[0038] Step 5:

[0039] The grouting time is approximately 7 seconds, and the suction time is between 9 and 12 seconds, depending on the product thickness.

[0040] Step Seven:

[0041] The extrusion time is approximately 7 seconds, reducing the moisture content of the wet preform to between 60% and 70%.

[0042] Step 10:

[0043] The extrusion and hot pressing time is between 40 and 55 seconds, depending on the product thickness.

[0044] Example 3:

[0045] Step 1:

[0046] The wire EDM machine precisely processes plant fiberboard, ensuring the accuracy of the upper and lower forming dies is between 0.7 and 1.2 microns. Simultaneously, it processes water holes in the forming dies with diameters between 1.5 and 3.5 millimeters.

[0047] Step 5:

[0048] The grouting time is approximately 9 seconds, and the suction time is between 7 and 11 seconds, depending on the product thickness.

[0049] Step Seven:

[0050] The extrusion time is approximately 9 seconds, reducing the moisture content of the wet preform to between 65% and 70%.

[0051] Step 10:

[0052] The extrusion and hot pressing time is between 45 and 50 seconds, depending on the product thickness.

[0053] Example 4:

[0054] Step 1:

[0055] The wire EDM machine precisely processes plant fiberboard, ensuring the accuracy of the upper and lower forming dies is between 0.6 and 1.0 microns. Simultaneously, it processes water holes in the forming dies with diameters between 1.2 and 2.8 millimeters.

[0056] Step 5:

[0057] The grouting time is approximately 8 seconds, and the suction time is between 8 and 10 seconds, depending on the product thickness.

[0058] Step Seven:

[0059] The extrusion time is approximately 8 seconds, reducing the moisture content of the wet preform to between 65% and 70%.

[0060] Step 10:

[0061] The extrusion and hot pressing time is between 40 and 55 seconds, depending on the product thickness.

[0062] Example 5:

[0063] Step 1:

[0064] The wire EDM machine precisely processes plant fiberboard, ensuring the accuracy of the upper and lower forming molds is between 0.8 and 1.2 microns. Simultaneously, it processes water holes in the forming molds with diameters between 1.5 and 3.5 millimeters.

[0065] Step 5:

[0066] The grouting time is approximately 7 seconds, and the suction time is between 9 and 12 seconds, depending on the product thickness.

[0067] Step Seven:

[0068] The extrusion time is approximately 7 seconds, reducing the moisture content of the wet preform to between 60% and 70%.

[0069] Step 10:

[0070] The extrusion and hot pressing time is between 45 and 50 seconds, depending on the product thickness.

[0071] The product obtained according to the above embodiments was tested according to the following test standards:

[0072] Tensile strength (ASTM D638): ≥ X MPa

[0073] Bending strength (ASTM D790): ≥ Y MPa

[0074] Compressive strength (ASTM D695): ≥ Z MPa

[0075] Water absorption performance test:

[0076] Water absorption rate (ASTM D570): ≤W%

[0077] Heat resistance test:

[0078] Heat distortion temperature (ASTM D648): ≥V℃

[0079] Environmental performance test:

[0080] Formaldehyde emission (GB / T 27630): ≤U mg / L

[0081] The measured data are as follows:

[0082]

[0083] In summary, Example 4 is the best implementation scheme.

[0084] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A process for the wet-pressing of high-pressure gas extrusion formed plant fibre containers, characterised in that, Used for one-piece molded closed-cavity bottle products, eliminating the need for secondary splicing; The high-pressure gas extrusion molding process for preparing plant fiber containers via wet pressing includes the following steps: Step 1: Use a slow wire EDM machine to process the plant fiber board, ensuring that the precision of the upper and lower forming molds is within 1 mil; at the same time, process water holes for the forming molds to facilitate the entry and exit of subsequent slurry; Step 2: Fix metal mesh on the surface of the upper and lower forming molds for slurry adsorption and vacuum suction, ensuring that the slurry is evenly distributed in the mold to form a uniform wet blank. Step 3: Connect the movable vacuum line and the steam-water separator to the upper and lower molding dies to ensure the normal operation of the vacuum system; Step 4: Place the highly elastic expansion bladder inside the lower mold of the molding die so that when the upper and lower molds are joined, the bladder is located between the two mold pieces, ensuring the formation of the wet preform; Step 5: When the upper and lower forming molds are combined, the slurry tank rises automatically and the slurry is poured into the cavities of the upper and lower molds through the slurry inlet buckle in front of the combined mold; at the same time, the pneumatic vacuum system is activated to draw the slurry onto the metal mesh of the upper mold; the slurry pouring time is 5-10 seconds, and the suction time is 7-12 seconds depending on the product thickness. Step Six: When vacuum adsorption is started, the cylinder push rod with sealing gasket pushes the sealing gasket to the grouting hole, making the mold cavity a sealed state to prevent grout leakage. Step 7: After grouting is completed, the grout box will automatically return to its original position; start the high-pressure compressed air system and inject compressed air at a pressure of 12 MPa into the telescopic air bladder, causing the air bladder to expand and squeeze the wet blank adsorbed on the metal mesh, reducing the moisture content of the wet blank to 70%; the squeezing time is 6-10 seconds. Step 8: After extrusion, the gas inside the airbag is discharged through the exhaust valve, causing the telescopic airbag to shrink back to its original state; at the same time, the upper mold of the forming mold returns to its original position, and the shrunken inner bladder is manually removed. Step 9: Take out the wet blank after it has been formed and drained and place it in the lower mold of the hot press drying mold. At the same time, place the inner bladder of the hot press drying mold inside the wet blank. Step 10: After placing the inner bladder, start the hot pressing process to merge the upper and lower molds; by introducing compressed air at a pressure of 20 MPa, the air bladder squeezes the wet blank, reducing the moisture content from 70% to less than 10%; the squeezing and hot pressing time is 40-55 seconds depending on the product thickness; Step 11: After the hot-pressed upper mold returns to its original position, the dried container is manually removed for inspection, packaging, and final warehousing.

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