Process and device for the production of high-viscosity resin panels

Abstract

The present application relates to a kind of processes and devices for preparing high viscosity resin plate.The mold for preparing high viscosity resin plate includes mold bottom plate, thickness control middle frame and mold cover plate.The process and device for preparing high viscosity resin plate in the present application adopt direct access to mold from planetary mixer, which avoids the problem of re-mixing air bubbles in the transfer process.A circle of exhaust passage with height of 0.1-0.2mm is arranged at the edge of mold cavity, and the passage is filled with semi-permeable cloth (air can pass through but resin cannot, thickness 0.12mm), which can ensure that air is discharged from the passage and avoid the formation of cavity in the area not filled with resin in time at the edge of mold.In addition, the semi-permeable cloth also avoids the blockage of the passage, improving the efficiency of the exhaust passage.

Description

Technical Field

[0001] This invention relates to a process and apparatus for manufacturing high-viscosity resin boards, belonging to the field of resin processing technology. Background Technology

[0002] Commonly used prepreg resins have high viscosity and are typically solid at room temperature. Characterizing viscosity usually requires heating to melt the resin, but high-temperature resins generally have a short pot life and cannot be heated repeatedly or for extended periods.

[0003] To characterize the mechanical or optical properties of such resins, resin plates with extremely high purity and uniformity are required. However, for high-viscosity resins, fabricating thin-walled resin plates (typically 0.1–20 mm thick) often fails to eliminate air trapped within the resin during the mixing process. Unvented gas within the plate forms bubbles, leading to inaccurate mechanical property test results or affecting optical properties such as transparency. Furthermore, the trapped air also reduces the resin's resistance to aging, such as thermal oxidation.

[0004] Currently, the common process for degassing resin in resin board manufacturing involves using a vacuum oven. However, due to the high viscosity of resin (viscosity of 30,000–500,000 cps at the degassing temperature), air bubbles mixed in the resin are difficult to escape, or require a long vacuum degassing time. Prolonged heating may lead to resin prepolymerization modification or direct explosive polymerization, resulting in serious consequences.

[0005] Another degassing method is centrifugal degassing. In this method, the mixed resin is usually in small amounts and has a certain thickness, making it impossible to make thin-walled resin plates with large areas or products of a certain shape.

[0006] Another method for removing air bubbles is to use a vacuum planetary mixer to mix the materials. Although this method can mix a sufficient amount of resin at once, it requires the resin to be transported, and a lot of air may be mixed into the resin during the process. It is also difficult to make resin boards and products with fixed shapes.

[0007] Therefore, there is an urgent need in this field for a process and apparatus that can efficiently produce high-viscosity resins for plate making. Summary of the Invention

[0008] The problem to be solved by the present invention is that the high viscosity resin board obtained by the existing high viscosity resin board preparation method has air bubbles.

[0009] To address the aforementioned problems, the present invention provides a process and apparatus for preparing high-viscosity resin boards.

[0010] In a first aspect, the present invention provides a mold for preparing a high-viscosity resin board, comprising a mold base plate, a thickness control frame, and a mold cover plate. Locking screw holes and positioning holes are passed through the mold's perimeter. A triangular glue inlet area is provided at the front of the back of the thickness control frame. A triangular symmetrical area corresponding to the glue inlet area is provided on the front of the mold base plate. A glue inlet is provided at the front of the triangular glue inlet area, and a molding recess is provided at the rear. A glue outlet is provided at the rear of the molding recess. An exhaust channel is provided on one or both sides opposite or adjacent to the glue inlet, and the exhaust channel is connected to a vacuum port. A sealing groove is provided on the mold cover plate and the mold base plate at corresponding positions of the exhaust channels, and a molding boss is provided on the mold base plate and the molding recess at corresponding positions.

[0011] Preferably, the height of the mold cavity in the thickness control frame is set to 4mm according to the thickness of a general resin strip.

[0012] Preferably, the edge of the thickness control frame is provided with mold opening pry points.

[0013] Preferably, the height of the exhaust channel is 0.1 to 0.2 mm.

[0014] Preferably, the exhaust channel is filled with a semi-permeable fabric, and the thickness of the semi-permeable fabric is further preferably 0.12 mm.

[0015] Preferably, the rear end of the glue inlet is provided with a triangular glue expansion area, and a flat and elongated narrow opening is provided at the point where the glue expansion area enters the molding boss, with the height of the narrow opening preferably being 0.5mm.

[0016] Preferably, the glue inlet is connected to the outlet of the planetary mixer, so that the high-viscosity resin can directly enter the mold from the planetary mixer.

[0017] Preferably, the mold has a vacuum port on the side opposite to the injection port.

[0018] A second aspect of the present invention provides a method for preparing a high-viscosity resin plate using the above-described mold, comprising the following steps:

[0019] Step 1: Place the mold on a heating platform and preheat it to 70-85°C, then keep it at that temperature;

[0020] Step 2: Mix the raw materials of the formula to be tested evenly using a planetary mixer, and then remove the gas inside the resin. If the total amount of resin is small, it can be degassed by heating and then using a vacuum centrifugal degassing machine.

[0021] Step 3: Keep the planetary mixer sealed and connect the mixer outlet to the injection mold inlet using a heat-resistant PU tube;

[0022] Step 4: Connect the injection mold outlet to the vacuum line;

[0023] Step 5: Ensure the planetary mixer is sealed, raise the resin temperature to 50-75℃, and vacuum mix. The mixing time should be determined by observing through the sight glass of the barrel. If the resin can slowly level out after stopping the mixing and no more bubbles are generated, it can be considered that the air in the resin has been completely expelled. This usually takes 20-40 minutes.

[0024] Step 6: Keep the planetary mixer barrel sealed, turn off the vacuum and introduce high-pressure nitrogen to subject the resin to a certain positive pressure;

[0025] Step 7: First open the vacuum end of the mold, then open the injection end of the mold to allow the resin to slowly enter the mold cavity;

[0026] Step 8: When resin slowly flows out of the mold from the vacuum end, it means that the mold cavity is full of resin. At this time, shut off the glue inlet pipe, shut off the high-pressure gas, shut off the vacuum end pipe in sequence, and cut off the glue inlet pipe and glue outlet pipe after shutting off the vacuum. Keep the mold closed and heat the mold evenly to ensure that the resin is heated evenly and does not deform.

[0027] Preferably, in step 3, the inner diameter of the PU tube is set to 8-10 mm. More preferably, a check valve is provided on the pipeline to facilitate the adjustment of the pipeline's opening and closing.

[0028] Preferably, in step 4, the vacuum pipeline is equipped with a resin collector, and more preferably, a switch is provided. The vacuum pipeline is preferably made of transparent, heat-resistant PU tubing.

[0029] Preferably, in step 8, when placing the mold, the side of the mold outlet is raised to avoid changes in the thickness of the board due to volume shrinkage during the resin curing process.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The resin is fed directly into the mold from the planetary mixer, avoiding the problem of air bubbles being reintroduced during the transfer process.

[0032] 2. The sloping area of ​​the sprue inlet connects to a triangular expansion zone. Firstly, this zone prevents resin from directly entering the mold cavity, avoiding voids. Secondly, the narrow opening at the cavity entrance is only 0.5mm high, buffering and thinning the incoming resin. The triangular structure allows the resin to spread evenly, filling the mold cavity uniformly from one side. After passing through the narrow opening, there is a smooth transition into the cavity area. Throughout the flow path, there are no steps or other structural features that could affect the pouring process.

[0033] 3. Adding a vacuum device to the other side of the mold can further remove air bubbles from the resin, ensuring that there is no residual air or surrounding voids caused by inconsistent resin flow rate during the injection process.

[0034] 4. A venting channel with a height of approximately 0.1–0.2 mm is provided around the edge of the mold cavity. The channel is filled with a semi-permeable fabric (allowing air to pass through but not resin, with a thickness of 0.12 mm). This ensures that air is discharged through the channel, preventing the formation of cavities in areas at the mold edge that are not promptly filled with resin. Furthermore, the semi-permeable fabric prevents resin from clogging the channel, improving the efficiency of the venting. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the front of the mold base plate in this invention;

[0036] Figure 2 This is a schematic diagram of the back side of the mold base plate in this invention;

[0037] Figure 3 This is a schematic diagram of the side of the mold base plate in this invention;

[0038] Figure 4 This is a top front view of the mold thickness control frame in this invention;

[0039] Figure 5 This is a front view of the mold thickness control frame in this invention;

[0040] Figure 6 This is a front view of the back of the mold thickness control frame in this invention;

[0041] Figure 7 This is a side view of the mold base plate and the thickness control frame after they are combined in this invention;

[0042] Figure 8 This is a top view of the mold cover plate in this invention;

[0043] Figure 9 This is a front view of the mold cover plate in this invention;

[0044] Figure 10 This is a left view of the mold cover plate in this invention;

[0045] Reference numerals: 1. Locking screw hole; 2. Positioning hole; 3. Sealing groove; 4. Triangular symmetrical area; 5. Molding boss; 6. Venting channel; 7. Triangular injection area; 8. Inlet; 9. Outlet; 10. Mold opening pry point. Detailed Implementation

[0046] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings:

[0047] like Figure 1-8As shown, the pouring mold is placed on a heating platform and preheated to the commonly used pouring temperature of the resin, and then kept at this temperature. The temperature is usually 50-75℃ to ensure that the resin does not cool down rapidly after entering the mold, which would cause it to thicken quickly and affect the filling of the mold.

[0048] After thoroughly mixing the raw materials of the formulation to be tested using a planetary mixer, the gas inside the resin is removed. If the total amount of resin is small, it can be degassed using a vacuum centrifuge after heating (the centrifuge cup must have an outlet to connect to the inlet tube).

[0049] Keep the planetary mixer sealed. Connect the mixer outlet to the injection mold inlet 8 using a heat-resistant and transparent PU tube with an inner diameter of 8-10mm. A check valve should be installed on the pipeline to facilitate adjustment of the pipeline's flow.

[0050] Connect the injection mold outlet 9 to the vacuum line. The inner diameter of the line should be 8mm. A resin collector should be installed at the vacuum line to ensure stable resin injection pressure and uniform resin flow rate; this also prevents resin from entering the vacuum pump and causing damage. A switch should be installed on the line for easy adjustment of its opening and closing. Transparent, heat-resistant PU tubing is typically used for the vacuum line.

[0051] Ensure the planetary mixer is sealed, raise the resin temperature to the specified temperature, and vacuum stir for 20-30 minutes to ensure that any air bubbles mixed in the resin can completely escape.

[0052] Keep the planetary mixer barrel sealed, turn off the vacuum, and introduce high-pressure nitrogen to subject the resin to a certain positive pressure.

[0053] First open the vacuum end of the mold, then open the mold inlet 8 to allow the resin to slowly enter the mold cavity.

[0054] Once resin slowly flows out of the vacuum end of the mold, it indicates that the mold cavity is full of resin. At this point, it is necessary to sequentially close the glue inlet pipe, shut off the high-pressure gas, and close the vacuum end pipe to prevent resin backflow. After shutting off the vacuum, disconnect the glue inlet 8 and the glue outlet 9, keep the mold sealed, and place the mold in an oven for even heating to ensure that the resin is heated evenly and does not deform. When placing the mold, the glue outlet 9 side of the mold should be slightly raised to prevent changes in the thickness of the board due to volume shrinkage during resin curing.

[0055] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make several improvements and additions without departing from the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A mold for preparing high-viscosity resin sheets, characterized in that, The mold includes a base plate, a thickness control frame, and a mold cover plate. Locking screw holes and positioning holes are drilled around the mold's perimeter. A triangular injection area is located on the front of the back of the thickness control frame, and a symmetrical triangular area mates with the injection area on the front of the base plate. The triangular injection area has an injection port at the front and a molding recess at the rear. An outlet is located at the rear of the molding recess. Exhaust channels are located on one or both sides opposite or adjacent to the injection port and are connected to a vacuum port. Sealing grooves are located on the mold cover plate and base plate at corresponding positions on the exhaust channels. Molding bosses are located on the base plate and molding recess at corresponding positions. The injection port is connected to the planetary mixer outlet, allowing high-viscosity resin to enter the mold directly from the planetary mixer. A flat, elongated narrow opening with a height of 0.5 mm is located at the point where the triangular injection area enters the molding boss.

2. The mold for preparing high-viscosity resin plates as described in claim 1, characterized in that, The thickness control frame sets the height of the mold cavity to 4mm according to the thickness of the general resin strip.

3. The mold for preparing high-viscosity resin plates as described in claim 1, characterized in that, The thickness control frame is provided with mold opening pry points on its edge.

4. The mold for preparing high-viscosity resin plates as described in claim 1, characterized in that, The height of the exhaust channel is 0.1~0.2mm.

5. The mold for preparing high-viscosity resin plates as described in claim 1, characterized in that, The exhaust channel is filled with a semi-permeable fabric with a thickness of 0.12 mm.

6. A method for preparing a high-viscosity resin board using a mold as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Place the mold as described in any one of claims 1 to 5 on a heating platform and preheat it to 70 to 85°C, then keep it at that temperature; Step 2: Mix the raw materials of the formula to be tested evenly using a planetary mixer, and then remove the gas inside the resin. If the total amount of resin is small, degas it using a vacuum centrifugal degassing machine after heating. Step 3: Keep the planetary mixer sealed and connect the mixer outlet to the injection mold inlet using a heat-resistant PU tube; Step 4: Connect the injection mold outlet to the vacuum line; Step 5: Ensure the planetary mixer is sealed, raise the resin temperature to 50~75℃, and vacuum mix. The mixing time should be determined by observing through the sight glass of the barrel. If the resin can slowly flow and level after stopping the mixing and no more bubbles are generated, it is considered that the air in the resin has been completely expelled. Step 6: Keep the planetary mixer barrel sealed, turn off the vacuum and introduce high-pressure nitrogen to subject the resin to a certain positive pressure; Step 7: First open the vacuum end of the mold, then open the injection end of the mold to allow the resin to slowly enter the mold cavity; Step 8: When resin slowly flows out of the mold from the vacuum end, it means that the mold cavity is full of resin. At this time, shut off the glue inlet pipe, shut off the high-pressure gas, shut off the vacuum end pipe in sequence, and cut off the glue inlet pipe and glue outlet pipe after shutting off the vacuum. Keep the mold closed and heat the mold evenly to ensure that the resin is heated evenly and does not deform.

7. The method for preparing a high-viscosity resin board as described in claim 6, characterized in that, In step 3, the inner diameter of the PU tube is set to 8~10mm, and a check valve is provided on the tube to facilitate the adjustment of the tube's opening and closing.

8. The method for preparing a high-viscosity resin board as described in claim 6, characterized in that, In step 4, the vacuum pipeline is equipped with a resin collector, and the vacuum pipeline is made of transparent, heat-resistant PU tubing.

9. The method for preparing a high-viscosity resin board as described in claim 6, characterized in that, In step 8, when placing the mold, the side of the mold outlet is raised to prevent the thickness of the board from changing due to volume shrinkage during the resin curing process.

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