High-gloss elastic grinding block and preparation process thereof

Abstract

The application discloses a high-gloss elastic grinding block and a preparation process thereof. The high-gloss elastic grinding block comprises the following raw materials in percentage by mass: resin 25-53%, lubricant 1-3%, pore-forming agent 20-40%, filler 5-15%, diamond 7-15%, silicon dioxide 3-15%, chelating agent 0.1-1.0%, dispersant 0.1-1.0% and cerium oxide 8-20%. The resin is compounded by phenolic resin and melamine resin. The phenolic resin and melamine resin are combined as a binder, the preferred diamond is used as a main abrasive, the nano-silicon dioxide and cerium oxide are used as auxiliary abrasives, the barium sulfate is used as a filler, the zinc stearate is used as a lubricant and a release agent, the pretreated sodium chloride is used as a pore-forming agent, and the grinding block is obtained by adding appropriate dispersant and chelating agent. The grinding block has sufficient sharpness and good service life. The glazed tile product polished by the grinding block has high gloss, is not prone to fogging, and is not prone to scratches. After the grinding block is used on a fine polishing grinding head, the gloss of the glazed tile can reach more than 90 degrees.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of grinding blocks, in particular to a high-gloss elastic grinding block and a preparation process thereof. BACKGROUND

[0002] With the continuous development of the building industry, ceramic tiles have begun to diversify into various types. Generally, ceramic tiles are made through processes such as pressing, applying glaze, high-temperature firing and polishing. Ceramic tile products require a smooth and glossy surface with certain stain resistance. Therefore, the polishing process plays a crucial role.

[0003] At present, the popular elastic grinding blocks on the market can only make the gloss of the polished ceramic tiles about 40-70 degrees, and the ceramic tile surface is prone to produce fog (commonly known as polishing fog) or scratches. Subsequent re-polishing with super-clean nano liquid is required to make the gloss of the ceramic tile surface reach more than 90 degrees and also repair the surface scratches. SUMMARY

[0004] The main purpose of the application is to provide a high-gloss elastic grinding block and a preparation process thereof, aiming to solve the technical problems that the gloss of the ceramic tile polished by the existing elastic grinding block is low, and the ceramic tile surface is prone to produce fog and scratches.

[0005] To achieve the above-mentioned purpose, the application provides a high-gloss elastic grinding block, which is prepared by mixing the following raw materials in percentage by mass: 25-53% of resin, 1-3% of lubricant, 20-40% of pore-forming agent, 5-15% of filler, 7-15% of diamond, 0.1-1.0% of chelating agent, 0.1-1.0% of dispersing agent, 3-15% of silicon dioxide and 8-20% of cerium oxide; the resin is compounded by phenolic resin and melamine resin.

[0006] The two resins, phenolic resin and melamine resin, are combined to obtain a grinding block with sufficient heat resistance and toughness, that is, the grinding block has sufficient sharpness and good service life. The gloss of the ceramic tile product polished by the grinding block is high and is not prone to fog.

[0007] Preferably, the mass ratio of the phenolic resin to the melamine resin is (3.2-100):(5-60).

[0008] Preferably, the pore-forming agent is sodium chloride, which needs to be pretreated. The pretreatment step is: dissolving sodium chloride in water, adding Na2CO3, NaOH and BaCl2 for precipitation, filtering out the precipitate, and removing Ca 2+ , Mg 2+ and SO2 -4The impurity ions are obtained in a sodium chloride solution, which is crystallized and then broken to obtain the sodium chloride with a purity of ≥99.9%.

[0009] The pore-forming agent is subjected to the pretreatment process, and the number and size of the pores obtained are suitable, so that the polishing block is used for polishing the ceramic tiles, the tile surface is not prone to mist, and the mirror effect and smoothness of the ceramic tile product are higher.

[0010] Preferably, the size of the broken sodium chloride is 20-150 mesh in fineness.

[0011] Preferably, the silicon dioxide is nano-silicon dioxide, and the size of the nano-silicon dioxide is 10-150 nanometers. The silicon dioxide in the present scheme is in nanoscale, and the 10-150 nanometer silicon dioxide can further improve the gloss of the ceramic tile.

[0012] Preferably, the filler is at least one of barium sulfate or titanium white.

[0013] Preferably, the lubricant is stearic acid. Zinc stearate serves as a lubricant and a release agent.

[0014] Preferably, the chelating agent is at least one of disodium ethylenediaminetetraacetate (EDTA), nitrilotriacetic acid (NTA), diethylenetriamine pentaacetic acid (DTPA), sodium citrate, and sodium gluconate.

[0015] Preferably, the dispersing agent is at least one of sodium silicate, sodium tripolyphosphate, sodium hexametaphosphate, and sodium polyacrylate.

[0016] In addition, the present application also provides a preparation process of the high-gloss elastic polishing block, which comprises the following steps: placing the resin, the lubricant, the pore-forming agent, the filler, the diamond, the chelating agent, the dispersing agent, the silicon dioxide, and the cerium oxide in a container in a mass percentage, stirring and mixing for 0.5-4 hours, and then hot-pressing to obtain a polishing block working layer, and then bonding the back surface of the polishing block working layer with an elastic rubber block and a plastic base by using glue to obtain the high-gloss elastic polishing block.

[0017] Preferably, the pressure during hot-pressing is 12-20 MPa, the temperature is 140-180℃, and the holding time is 12-18 minutes.

[0018] The high-gloss elastic abrasive block of the present invention has the following beneficial effects: it uses a combination of phenolic resin and melamine resin as a binder, preferably diamond as the main abrasive, nano-silica and cerium oxide as auxiliary abrasives, barium sulfate as a filler, zinc stearate as a lubricant and release agent, and pretreated sodium chloride as a pore-forming agent. At the same time, appropriate amounts of chelating agents and dispersants are added to solve the problem of polishing slag deposition on the surface of ceramic tiles and improve the dispersion state of polishing micro powder in water, thereby improving polishing efficiency. The resulting abrasive block has sufficient sharpness and good service life. The ceramic tile products polished by this abrasive block have a high gloss and are not easy to fog up or scratch. After using the above abrasive block on a fine polishing head, the gloss of the ceramic tile can reach more than 90 degrees. There is no need to apply super-clean nano liquid; only an anti-fouling agent is needed. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0020] Currently, the main problems in tile polishing are insufficient gloss, surface fogging, and scratches on the polished tiles. The main reasons are insufficient sharpness of the grinding blocks and the deposition of polishing residue on the tile surface, which are generally caused by the following reasons: (1) Improper selection or inappropriate addition of pore-forming agent in the grinding blocks, resulting in unsuitable number, size, and shape of pores in the grinding blocks. When the number of pores produced in the grinding blocks is insufficient, some of the polishing residue will remain on the tile surface, affecting the polishing efficiency and easily causing fogging. Currently, commonly used pore-forming agents include soda ash, industrial salt, and sugar. Most manufacturers now use industrial salt as a pore-forming agent, which contains Ca 2+ Mg 2+ and SO4 2- Ions will cause polishing slag to condense on the brick surface, affecting polishing efficiency and causing fogging. Therefore, the amount of pore-forming agent added should not be too large, otherwise it will affect the polishing effect of the grinding block. (2) During the polishing process, the polishing slag produced is very fine, and the glaze will undergo hydrolysis, releasing Ca. 2+ Mg 2+ Plasma ions cause polishing residue to easily coagulate and settle on the tile surface, affecting the polishing effect and causing fogging or haziness. Additionally, the water used in ceramic factory polishing lines is generally recycled, resulting in high water hardness and a high calcium content. 2+ Mg 2+ Plasma. Adding an appropriate amount of chelating agent to chelate Ca... 2+ Mg 2+Plasma chelating agent, so that the polishing slag is not easy to condense on the surface of the ceramic tile, can effectively solve the problem of fogging on the surface of the ceramic tile during polishing.(3) The elastic grinding block forms a suspension with water during polishing. In order to fully disperse and suspend the diamond and various auxiliary materials in water, it is necessary to add a dispersing agent.(4) The bonding effect of the grinding block binder on the diamond. If the holding is too firm, the diamond is not easy to fall off, that is, the self-sharpening of the grinding block is poor, and the gloss of the ceramic tile is low. If the holding is too loose, the diamond falls off too fast, and the service life of the grinding block is too short.(5) The quality of the diamond has a great influence on the gloss of the polished ceramic tile.(6) Selection of auxiliary polishing materials. Silicon carbide and corundum are often selected as auxiliary polishing materials in the prior art, which have low cost, but the gloss of the polished ceramic tile is not high enough.

[0021] The present application is targeted to solve the above problems.(1) The pore-forming agent is selected to be an industrial salt, which is refined to remove impurities and then broken into appropriate particle size.(2) The ions of Ca 2+ , Mg 2+ , and plasma in the circulating water are selected to be chelated by a suitable chelating agent so that they cannot deposit on the surface of the ceramic tile.(3) A dispersing agent is added to the grinding block to fully disperse and suspend the diamond and auxiliary abrasive on the surface of the ceramic tile, thereby improving the polishing efficiency.(4) A resin is compounded to improve the bonding of the grinding block.(5) A suitable diamond powder is selected.(6) A suitable auxiliary abrasive is selected.

[0022] In summary, the present application provides a preparation process of a high-gloss elastic grinding block, including the following steps: placing 25-53% resin, 1-3% lubricant, 20-40% pore-forming agent, 5-15% filler, 7-15% diamond, 0.1-1.0% chelating agent, 0.1-1.0% dispersing agent, 3-15% silicon dioxide, and 10-20% cerium oxide in a container in a mass percentage, stirring and mixing for 0.5-4h, and then hot pressing to obtain a grinding block working layer. The high-gloss elastic grinding block is obtained by combining the grinding block working layer with a base. The pressure during hot pressing is 12-20MPa, the temperature is 140-180℃, and the holding time is 12-18min.

[0023] The resin is compounded by phenolic resin and melamine resin, and the mass ratio of the phenolic resin and the melamine resin is (3.2-100):(5-60). The resin as a binder is directly related to the sharpness, wear resistance and wear ratio of the grinding block. At present, the commonly used binding resin is combined by phenolic resin and melamine resin. Since the phenolic resin has poor heat resistance, the diamond shedding speed is fast, the sharpness of the grinding block made of the phenolic resin is high, but the service life is short; the melamine resin has good heat resistance, high hardness, but low impact strength, the grinding block produced by the melamine resin has good wear resistance, but low sharpness. Considering the sharpness of the grinding block and the service life of the grinding block, the phenolic resin and the melamine resin are combined in the scheme. The obtained grinding block has sufficient heat resistance and toughness, that is, the grinding block has sufficient sharpness and good service life, and the gloss of the ceramic tile product polished by the grinding block is higher.

[0024] The pore former is sodium chloride; and the sodium chloride needs to be pretreated, and the pretreatment step is: dissolving sodium chloride in water, adding Na2CO3, NaOH and BaCl2 for precipitation, filtering out the precipitate to obtain a sodium chloride solution, crushing the crystallized sodium chloride to obtain sodium chloride with a purity of ≥99.9%; the fineness of the crushed sodium chloride is 20-150 mesh. The grinding block with high sharpness also has a fast grinding slag production speed, and if there is no corresponding slag containing and removing capacity, it will also affect the sharpness of the grinding block, and the polishing slag is left on the tile surface, causing the tile surface to mist, affecting the mirror effect and the improvement of the smoothness of the ceramic tile product. Therefore, the selection of the pore former and the setting of the addition amount are very important to obtain appropriate pore size of the grinding block. The selected sodium chloride is pretreated, first, an industrial grade salt is dissolved in water, various reagents are added, and after filtering out the precipitate, a sodium chloride solution with a purity of ≥99.9% is obtained, which is crystallized into large particles and then crushed to the required particle size range.

[0025] The silicon dioxide is nano silicon dioxide, and the size of the nano silicon dioxide is 10-150 nanometers. In the scheme, instead of using silicon carbide and corundum as auxiliary polishing materials, nano SiO2 and cerium oxide are selected as auxiliary polishing materials, and the gloss of the ceramic tile is further improved. The filler is at least one of barium sulfate or titanium white, and the lubricant is zinc stearate.

[0026] The diamond is W5 grade industrial micro-powder diamond, and the fineness is 1200-10000 mesh. According to different grinding block fineness requirements, the corresponding mesh diamond is selected.

[0027] The chelating agent is at least one of disodium ethylenediaminetetraacetate (EDTA), nitrilotriacetic acid (NTA), diethylenetriamine pentaacetic acid (DTPA), sodium citrate and sodium gluconate. It is required that the selected chelating agent does not decompose at the hot pressing forming temperature.

[0028] The dispersant is at least one of sodium silicate, sodium tripolyphosphate, sodium hexametaphosphate, and sodium polyacrylate. The selected dispersant is required not to decompose at the hot-pressing temperature.

[0029] The technical solutions of the present application are further described in detail below in combination with specific examples. It should be understood that the following examples are only used to explain the present application and do not limit the present application.

[0030] Example 1

[0031] Preparation steps of the high-gloss elastic grinding block:

[0032] (1) The pore-forming agent is pretreated. The pretreatment step is as follows: sodium chloride is dissolved in water, and then Na2CO3, NaOH, and BaCl2 are added for precipitation. The precipitate is filtered out, and a sodium chloride solution with a purity of ≥99.9% is obtained. The sodium chloride solution is dried and crystallized to form coarse crystalline substances. The coarse crystalline substances are crushed and then passed through a 20-mesh and a 150-mesh sieve. The crystalline substances above 20 mesh and below 150 mesh are screened out, and the remaining crystalline substances are the pretreated sodium chloride pore-forming agent.

[0033] (2) The ingredients are proportioned by mass percentage as shown in the following table. The ingredients in the table are weighed and then stirred and mixed in a container for 2 hours.

[0034] Raw Material Name Amount (Wt%) Phenolic Resin 12 Melamine Resin 25 Lubricant - Zinc Stearate 1 Pore Former - Pre-treated Sodium Chloride 28 Filler - Barium Sulfate 9 Diamond W5 10 Nano-Silica 4.4 Cerium Oxide 10 Chelating Agent - Disodium EDTA 0.3 Dispersant - Sodium Tripolyphosphate 0.3 Total 100

[0035] (3) The mixed ingredients are poured into a mold, a magic tape is placed in the mold, and then a 150-ton hot press is used for hot-pressing forming at a pressure of 18 MPa and a temperature of 155°C for 15 minutes. After that, the mold is removed for cooling, and a grinding block working layer is obtained.

[0036] (4) The back surface of the grinding block working layer is bonded to the elastic rubber block and the plastic base with glue, and the high-gloss elastic grinding block is obtained.

[0037] Example 2

[0038] The parameters and preparation steps in this example are the same as those in Example 1, except that the dispersant is replaced with sodium polyacrylate.

[0039] Example 3

[0040] The parameters and preparation steps in this example are the same as those in Example 1, except that sodium tripolyphosphate and sodium polyacrylate are used as dispersants, and the addition amount of each is 0.15%.

[0041] Example 4

[0042] The parameters and preparation steps in this example are the same as those in Example 1, except that sodium citrate is used as a chelating agent.

[0043] Example 5

[0044] The parameters and preparation steps in this example are the same as in Example 1, except that the amount of pore-forming agent in Example 1 is reduced, and the amounts of barium sulfate, cerium oxide and nano-silica are increased. The specific amounts of each raw material are as follows:

[0045] Raw Material Name Amount (Wt%) Phenolic Resin 12 Melamine Resin 25 Lubricant - Zinc Stearate 1 Pore Former - Pre-treated Sodium Chloride 20 Filler - Barium Sulfate 12 Diamond W5 10 Nano-Silica 7.4 Cerium Oxide 12 Chelating Agent - Disodium EDTA 0.3 Dispersant - Sodium Tripolyphosphate 0.3 Total 100

[0046] Example 6

[0047] The parameters and preparation steps in this example are the same as in Example 1, except that the amount of pore-forming agent in Example 1 is increased to 40%, and the amounts of resin, barium sulfate and nano-silica are reduced. The specific amounts of each raw material are as follows:

[0048] Raw Material Name Amount (Wt%) Phenolic Resin 8 Melamine Resin 20 Lubricant - Zinc Stearate 1 Pore Former - Pre-treated Sodium Chloride 40 Filler - Barium Sulfate 7 Diamond W5 10 Nano-Silica 3.4 Cerium Oxide 10 Chelating Agent - Disodium EDTA 0.3 Dispersant - Sodium Tripolyphosphate 0.3 Total 100

[0049] Comparative Example 1

[0050] The formulation of the conventional elastic grinding block in the prior art is used, and the preparation steps include the following:

[0051] (1) The raw materials are weighed according to the mass percentages in the following table and then placed in a container for stirring and mixing for 2 h.

[0052] Raw Material Name Amount (Wt%) Melamine Resin 41 Zinc Stearate 1 Industrial Salt (Sodium Chloride) 15 Zinc Oxide 15 Diamond 8 Silicon Carbide 10 Aluminum Oxide 10 Total 100

[0053] (2) The mixed raw materials are poured into a mold, a magic tape is placed in the mold, and a 150-ton hot press is used for hot forming, with a pressure of 18 MPa, a temperature of 155°C, a holding time of 15 min, and the mold is cooled after ejection, to obtain the grinding block working layer.

[0054] (3) The back of the grinding block working layer is bonded to the elastic rubber block and the plastic base with glue. The elastic grinding block is obtained.

[0055] Comparative Example 2

[0056] The parameters and preparation steps in this example are the same as in Example 1, except that no dispersant and chelating agent are added. The specific amounts of each raw material are as follows:

[0057] Raw Material Name Amount (Wt%) Phenolic Resin 12 Melamine Resin 25 Lubricant - Zinc Stearate 1 Pore Former - Pre-processed Sodium Chloride 28 Filler - Barium Sulfate 9 Diamond W5 10 Nano-Silica 5 Cerium Oxide 10 Total 100

[0058] Comparative Example 3

[0059] The parameters and preparation steps in this example are the same as in Example 1, except that industrial salt (sodium chloride) is used instead of pretreated sodium chloride.

[0060] The product prepared above can produce the following types of polishing blocks: 2000#, 3000#, 5000#, 6000#, 8000#, the polishing blocks are used on the polishing machine of a ceramic factory which produces 800*800 glazed tiles, the polishing block combination used initially by the ceramic factory is shown in Table 1, the high-gloss polishing blocks produced by the above embodiments of the application and the polishing blocks produced by the comparative examples are installed on the fine polishing head starting from 2000#, the number is not adjusted, and the polishing indicators of the ceramic tiles obtained are shown in Table 2.

[0061] Table 1 Polishing machine polishing block fineness table

[0062]

[0063] Table 2 Polishing block use result evaluation of various formulations

[0064] Average Gloss / ° Average Smoothness Whether the surface is fogged Average Service Life Example 1 92 0.039 No Fog 12 hours Example 2 92 0.036 No Fog 12 hours Example 3 92 0.036 No Fog 12 hours Example 4 92 0.04 No Fog 12 hours Example 5 92 0.039 Light Fog 12 hours Example 6 92 0.041 No Fog 6 hours Comparative Example 1 67 0.398 Severe Fog 13 hours Comparative Example 2 75 0.352 Fog 12 hours Comparative Example 3 80 0.132 Light Fog 12 hours

[0065] Note: The evaluation of fogging is according to the severity, severe fogging > fogging > light fogging > slight fogging > no fogging.

[0066] As shown in the above table, the detection results of Example 1 and Examples 2-4 show that the several chelating agents and dispersants of the application, used alone or in combination, can achieve relatively excellent polishing effect. It should be noted that at present, chelating agents and dispersants are often used in CMP (chemical mechanical polishing), but are less used in solid products such as polishing blocks.

[0067] As shown in the detection results of Example 1 and Examples 5-6, when the amount of pore-forming agent (pretreated sodium chloride) is reduced or increased in the formulation with chelating agent and dispersant, the gloss of the polished ceramic tile does not decrease, the polishing effect is relatively stable, and the smoothness of the polished ceramic tile is controlled to be above 0.039. The traditional polishing block uses industrial salt as a pore-forming agent and does not use chelating agent and dispersant, and the impurities in the salt have a great impact, resulting in fogging after polishing and low gloss. If the amount of pore-forming agent is increased, the polishing effect will be worse. In the present scheme, the amount of sodium chloride can be increased to 20-40%, among which the optimal amount of sodium chloride is 26-32%, when used together with the complex resin in the present scheme and other raw materials, the service life of the high-gloss elastic polishing block obtained does not decrease, and the gloss of the ceramic tile surface after polishing can be maintained at about 92°.

[0068] Compared with the conventional elastic polishing block of Comparative Example 1, the gloss of the polished ceramic tile is higher, which can reach about 92°, and the gloss of the polished ceramic tile of the conventional elastic polishing block of Comparative Example 1 is only 67°, which cannot achieve high-gloss polishing effect, and the conventional elastic polishing block of Comparative Example 1 is prone to "fogging" after polishing the ceramic tile, which affects the mirror effect of the ceramic tile product.

[0069] The high-gloss elastic grinding block of Example 1 and the grinding block of Comparative Example 2 were compared. The grinding block of Comparative Example 2 was not added with dispersant and chelating agent, and the gloss of the ceramic tile polished by the grinding block was reduced to 75°. Similarly, the ceramic tile polished by the grinding block also had the problem of "fogging".

[0070] The high-gloss elastic grinding block of Example 1 and the grinding block of Comparative Example 3 were compared. The grinding block of Comparative Example 3 used conventional industrial salt as pore-forming agent, and the gloss of the ceramic tile polished by the grinding block was low, only 80°, and the polishing effect of high gloss could not be achieved. Meanwhile, the gloss of the ceramic tile was greatly reduced, only 0.132, and the ceramic tile polished by the grinding block had the problem of "light fogging", which indicated that the purity of the pore-forming agent sodium chloride had a great influence on the polishing effect.

[0071] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or use of the content of the present application within the inventive concept of the present application is included in the patent protection scope of the present application.

Claims

1. A high-gloss, resilient grinding block, characterized in that The raw materials are mixed to obtain the high-gloss elastic grinding block, including the following components by mass percentage: resin 25-53%, lubricant 1-3%, pore-forming agent 20-40%, filler 5-15%, diamond 7-15%, chelating agent 0.1-1.0%, dispersant 0.1-1.0%, silicon dioxide 3-15% and cerium oxide 8-20%; The resin is a mixture of phenolic resin and melamine resin; The pore-forming agent is pretreated sodium chloride, and the pretreatment process comprises the following steps: dissolving sodium chloride in water, adding Na2CO3, NaOH and BaCl2 for precipitation, filtering out the precipitate to obtain a sodium chloride solution, and crushing the crystallized sodium chloride to obtain sodium chloride with a purity of ≥99.9%.

2. A high-gloss, resilient grinding element as claimed in claim 1, characterized in that The mass ratio of the phenolic resin to the melamine resin is (3.2-100):(5-60).

3. A high-gloss, resilient grinding element as defined in claim 1, wherein, The crushed sodium chloride has a fineness of 20-150 mesh.

4. A high-gloss, resilient grinding element as defined in claim 1, wherein, The silicon dioxide is nano-silicon dioxide with a size of 10-150 nm.

5. A high-gloss, resilient grinding element as defined in claim 1, wherein, The filler is at least one of barium sulfate and titanium white, and the lubricant is zinc stearate.

6. A high-gloss, resilient grinding element as defined in claim 1, wherein, The chelating agent is at least one of disodium ethylenediaminetetraacetate, trisodium amino triacetate, diethylenetriamine pentaacetate, sodium citrate and sodium gluconate.

7. A high-gloss, resilient grinding element as defined in claim 1, wherein, The dispersant is at least one of sodium silicate, sodium tripolyphosphate, sodium hexametaphosphate and sodium polyacrylate.

8. A process for the production of a high-gloss, resilient grinding element according to any one of claims 1 to 7, characterized in that The method comprises the following steps: placing the resin, the lubricant, the pore-forming agent, the filler, the diamond, the silicon dioxide, the cerium oxide, the chelating agent and the dispersant in a container, stirring and mixing for 0.5-4 h, and then hot-pressing to obtain a working layer of the grinding block, and combining the working layer of the grinding block with a base to obtain the high-gloss elastic grinding block.

9. A process for the production of high-gloss elastic grinding elements according to claim 8, characterized in that, The pressure during hot-pressing is 12-20 MPa, the temperature is 140-180℃, and the holding time is 12-18 min.

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