A sealing aid, a method for preparing the same and a method for bonding polyetherimide materials

Abstract

The application provides a sealing aid, a preparation method thereof and a bonding method of polyetherimide material, and relates to the field of polymer material forming technology.The sealing aid provided by the application comprises the following components in mass percentage: 50-80% of an amide compound, 10-25% of an aromatic hydrocarbon and 10-25% of acetone.The application also provides a bonding method of polyetherimide material.By introducing the sealing aid, the sealing temperature (150-200 DEG C) is reduced, the deformation of the material and the flow channel is reduced, and the sealing firmness is increased;the hot sealing is carried out under vacuum conditions, the air between the PEI sealing surfaces and the air in the environment are removed to a large extent, the air bubbles generated by the gas expansion in the sealing process or the poor sealing firmness is reduced, and the quality and yield are improved.The bonding method of the application adopts the sealing aid to assist the vacuum heating, and the high-precision sealing of double-layer or multi-layer PEI can be realized.

Description

Technical Field

[0001] This invention relates to the field of polymer material molding technology, and in particular to a sealing aid and its preparation method, and a bonding method for polyetherimide materials. Background Technology

[0002] Engineering plastics—polyetherimide (PEI)—are formed into sheets through injection molding or extrusion. They are commonly used to manufacture manifolds, distributors, hubs, and other devices containing built-in hollow pipes or flow channels to achieve directional flow control of liquids or gases. They are applied in fluid equipment and valve groups in the field of in vitro diagnostics, as well as fluid components in the fields of pharmaceuticals or environmental monitoring.

[0003] Simple manifolds can be made into branch manifolds by directly carving or drilling PEI sheet. However, when it is a distributor, manifold, or rotary valve distributor with a complex flow path structure that has non-linear perforations, carving and drilling alone cannot achieve the desired result. It is necessary to cross-section the part with the flow path structure into two or more parts, carve each layer separately, and then seal (i.e., bond) the two or more layers to form a closed flow path.

[0004] Currently, the main method for sealing two layers of PEI material relies on the thermal fusion effect. This method requires reaching the inherent Vicat softening point and melting point of PEI material, which necessitates temperatures close to 240°C. This can lead to severe deformation of the non-sealed surfaces or pipe deformation. For structures with pipe widths greater than 1 mm, the deformation in the width and depth directions caused by the sealing process (e.g., around 0.1 mm) is acceptable for systems that do not strictly control flow rate. However, for structures with smaller pipe depths and widths (e.g., less than 0.5 mm) and are flow-sensitive, the changes in flow velocity and flow rate caused by the sealing deformation directly affect system stability. Therefore, sealing small-sized pipes with PEI material, such as PEI manifolds or distributors, remains a challenge in the industry. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a sealing aid, its preparation method, and a bonding method for polyetherimide materials. By using the sealing aid provided by this invention to activate the sealing surface of the polyetherimide material to be bonded, the sealing temperature can be reduced, deformation of the material and flow channels can be decreased, which is beneficial for achieving high-precision bonding.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The present invention provides a sealing aid comprising the following components in weight percentage: 50-80% amide compounds, 10-25% aromatic hydrocarbons, and 10-25% acetone.

[0007] Preferably, the sealing aid comprises the following components in weight percentage: 55-60% amide compounds, 20-25% aromatic hydrocarbons, and 15-20% acetone.

[0008] Preferably, the amide compound includes one or more of formamide, acetamide, acetamide derivatives, acrylamide, and acrylamide derivatives.

[0009] Preferably, the aromatic hydrocarbon includes one or more of benzene, toluene, and xylene.

[0010] This invention provides a method for preparing the sealing aid described in the above technical solution, comprising the following steps: The sealing aid is obtained by mixing amide compounds, aromatic hydrocarbons, and acetone.

[0011] This invention provides a bonding method for polyetherimide materials, comprising the following steps: The sealing surfaces of each polyetherimide sheet to be bonded are activated with a sealing aid, and the sealing surfaces have flow channels; the sealing aid is the sealing aid described in the above technical solution or the sealing aid prepared by the preparation method described in the above technical solution; After aligning the flow channels on the sealing surfaces of each activated polyetherimide sheet, they are assembled together to obtain an assembly. The assembly is vacuum heat-sealed to obtain bonded polyetherimide material; the vacuum heat-sealing temperature is 150~200℃.

[0012] Preferably, the number of polyetherimide sheets is greater than or equal to 2, the thickness of each polyetherimide sheet is independently 1~20mm, and the depth of the flow channel is 0.3~5mm and the width is 0.3~5mm.

[0013] Preferably, the activation treatment time is 30~120s.

[0014] Preferably, the heat preservation time of the vacuum heat sealing is 16~30h. When the temperature of the vacuum heat sealing is 150℃, the heating rate to the temperature of the vacuum heat sealing is 5~10℃ / min. When the temperature of the vacuum heat sealing is greater than 150℃, the heating procedure to the temperature of the vacuum heat sealing is: first, heat to 150℃ at a heating rate of 5~10℃ / min, and then heat to the temperature of the vacuum heat sealing at a heating rate of 0.5~1℃ / min.

[0015] Preferably, the vacuum heat sealing is performed in a vacuum-sealed heating device.

[0016] This invention provides a sealing aid comprising the following components in weight percentages: 50-80% amide compounds, 10-25% aromatic hydrocarbons, and 10-25% acetone. Using the sealing aid provided by this invention to activate the sealing surface of polyetherimide materials reduces the surface energy of the polyetherimide material, resulting in a softening temperature significantly lower than the Vicat softening and hot-melt temperatures. This reduction in sealing temperature ensures that the polyetherimide material and the flow channels on the sealing surface do not deform or deform minimally during the heat sealing process. The sealing aid provided by this invention is suitable for heat sealing of large-size and small-size pipes (width less than 0.5 mm) and can increase the sealing strength, thereby improving the quality of the device.

[0017] This invention provides a bonding method for polyetherimide materials. By introducing a sealing aid, the sealing temperature is lowered (sealing can be achieved at 150-200℃), reducing material and channel deformation while increasing seal strength. This invention performs heat sealing under vacuum conditions, which largely eliminates air between the PEI sealing surfaces and air from the environment, reducing air bubbles or weak seals caused by gas expansion during the sealing process, thus improving quality and yield. This innovative bonding method using sealing aid-assisted vacuum heating enables high-precision sealing of double-layer or multi-layer PEI structural polyetherimide materials. Attached Figure Description

[0018] Figure 1 The tooling fixture used for bonding the polyetherimide material in the embodiments of the present invention; Figure 2 This is a diagram showing the effect of bonding the double-layer PEI channels in Example 1; Figure 3 The image shows the effect of the unsealed flow channel semi-finished product after processing in step (2) of Example 2 and the sealed flow channel semi-finished product after heat sealing in step (5); Figure 4 This is a cross-sectional view of the closed flow channel in Example 2; Figure 5 This is a diagram showing the effect of flow channel bonding in Comparative Example 1. Figure 1 In the middle, 1-multi-layer PEI sheet combination, 2-multi-layer positioning column, 3-screw lock, 4-upper mold upper block, 5-upper mold heat spreader block, 6-upper mold lower block, 7-support block, 8-lower mold upper block, 9-lower mold heat spreader block, 10-lower mold lower block, 11-lower template, 12-upper template. Detailed Implementation

[0019] The present invention provides a sealing aid comprising the following components in weight percentage: 50-80% amide compounds, 10-25% aromatic hydrocarbons, and 10-25% acetone.

[0020] Unless otherwise specified, all raw materials and equipment involved in this invention are commercially available products well known in the art.

[0021] The sealing aid provided by this invention, by weight percentage, comprises 50-80% amide compounds, which can be 50%, 55%, 60%, 65%, 70%, 75%, or 80%. In this invention, the amide compounds preferably include one or more of formamide, acetamide, acetamide derivatives, acrylamide, and acrylamide derivatives. The acetamide derivatives can be N,N-diethylacetamide or N-methylacetamide, and the acrylamide derivatives can be N,N-dimethylacrylamide or N,N-diethylacrylamide. In this invention, the amide compounds can achieve shallow surface dissolution of solid PEI, and the amide compounds also act as diluents for aromatic hydrocarbons.

[0022] The sealing aid provided by the present invention comprises 10-25% aromatic hydrocarbons by weight percentage, which can be 10%, 15%, 20% or 25%. In the present invention, the aromatic hydrocarbons preferably include one or more of benzene, toluene and xylene, and the aromatic hydrocarbons can dissolve PEI in small amounts at high temperatures.

[0023] The sealing aid provided by the present invention comprises 10-25% acetone by weight, which can be 10%, 12%, 15%, 18%, 20% or 25%. In the present invention, the acetone is used as a diluent for aromatic hydrocarbons.

[0024] The sealing aid provided by this invention, through the compounding of its components, can reduce the surface energy of the polyetherimide material and cause a small amount of shallow polyetherimide material to swell or dissolve into the sealing aid. This results in a softening temperature much lower than the Vicat softening and hot-melt temperatures, and allows the swollen or dissolved PEI in the shallow layers to permeate each other during contact between the upper and lower interfaces, thereby reducing the sealing temperature and enabling sealing after gradual cooling, while also improving the seal strength. In this invention, the proportion of each component in the sealing aid can be adjusted according to the thickness of the polyetherimide material. When the polyetherimide material is thicker, the proportion of aromatic hydrocarbons in the sealing aid can be increased, while the proportion of amide compounds can be appropriately reduced.

[0025] This invention provides a method for preparing the sealing aid described in the above technical solution, comprising the following steps: The sealing aid is obtained by mixing amide compounds, aromatic hydrocarbons, and acetone.

[0026] The present invention does not have any special requirements for the mixing method; any mixing method well known in the art can be used to mix the components evenly.

[0027] This invention provides a bonding method for polyetherimide materials, comprising the following steps: The sealing surfaces of each polyetherimide sheet to be bonded are activated with a sealing aid, and the sealing surfaces have flow channels; the sealing aid is the sealing aid described in the above technical solution or the sealing aid prepared by the preparation method described in the above technical solution; After aligning the sealing surfaces of the activated polyetherimide sheets with the flow channels, they are assembled together to obtain an assembly. The assembly is vacuum heat-sealed to obtain bonded polyetherimide material; the vacuum heat-sealing temperature is 150~200℃.

[0028] In this invention, the sealing surfaces of each polyetherimide sheet to be bonded are activated using a sealing aid.

[0029] In this invention, the polyetherimide sheet refers to a sheet made of polyetherimide material. This invention does not have special requirements for the polyetherimide material; any polyetherimide material well-known to those skilled in the art or a modified polyetherimide material can be used, such as SABIC (ULTEM 1000~1110 series) or PEI plastic ester produced by Mitsui Chemicals. In this invention, the number of polyetherimide sheets is preferably greater than or equal to two, and the thickness of each polyetherimide sheet is preferably 1~20 mm, or 3~9 mm. The bonding method provided by this invention can achieve bonding of multilayer polyetherimide sheets. In this invention, the sealing surface of the polyetherimide sheet has a flow channel, the depth of which is preferably 0.3~5 mm (can be 0.3, 0.5, 1 or 2 mm), and the width is preferably 0.3~5 mm (can be 0.3, 0.5, 1 or 2 mm).

[0030] In this invention, the polyetherimide sheet with flow channels is preferably formed by preheating the polyetherimide sheet and then processing the surface flow channels. In this invention, the preheating temperature can be 120~200℃, specifically 130, 150, 160, 180 or 200℃, and the holding time can be 2~10h, specifically 2, 5, 6, 7, 8 or 9h. The preheating treatment is preferably carried out in a high-temperature sealed oven. In this invention, the preheating treatment serves to release internal stress in the material and reduce the risk of cracking during processing. This invention does not have special requirements for the method of processing the surface flow channels; processing methods well known to those skilled in the art can be used, such as CNC machine tool engraving, laser etching, etc. This invention also preferably processes the polyetherimide sheet with positioning holes, which are used to insert positioning posts. This invention does not have special requirements for the method of processing the positioning holes; processing methods well known to those skilled in the art can be used, such as CNC machine tool engraving, laser etching, etc.

[0031] In this invention, the sealing aid is the sealing aid described in the above technical solutions or the sealing aid prepared by the preparation method described in the above technical solutions. In this invention, the sealing aid can be applied to the sealing surface by surface immersion or equipment spraying for activation treatment; the preferred spraying amount is 0.3~2 μL / cm². 2 The activation treatment time is preferably 30~120s.

[0032] After the activation treatment is completed, the flow channels of the sealing surfaces of each activated polyetherimide sheet are aligned and then assembled together to obtain an assembly.

[0033] In this invention, the preferred assembly method is to insert positioning posts into the positioning holes processed in each polyetherimide sheet to lock the multi-layer polyetherimide sheets and achieve multi-layer assembly.

[0034] After obtaining the assembly, the present invention performs vacuum heat sealing on the assembly to obtain bonded polyetherimide material.

[0035] In this invention, the vacuum heat sealing temperature is 150~200℃, which can be 150, 160, 170, 180, 190, 195, or 200℃. When the vacuum heat sealing temperature is 150℃, the heating rate to the vacuum heat sealing temperature is preferably 5~10℃ / min. When the vacuum heat sealing temperature is greater than 150℃, the heating procedure to the vacuum heat sealing temperature is preferably: first heating to 150℃ at a heating rate of 5~10℃ / min, and then heating to the vacuum heat sealing temperature at a heating rate of 0.5~1℃ / min. Controlling the above heating procedure in this invention is beneficial for the relatively uniform heating and expansion ratio of each PEI sealing layer, especially sealing layers with different thicknesses, thus reducing deformation. In this invention, the holding time for vacuum heat sealing is preferably 16~30h, which can be 16, 20, 22, 25, 28, or 30h. In this invention, the vacuum heat sealing is preferably performed in a vacuum-sealed heating device, that is, the assembly is placed in the vacuum-sealed heating device for heat sealing. The pressure of the vacuum-sealed heating device is preferably -30~-50 kPa, and can be -30, -35, -40 or -50 kPa. In an embodiment of this invention, the vacuum-sealed heating device is a vacuum oven. This invention utilizes a vacuum oven to achieve temperature control, resulting in uniform temperature within the sealed space.

[0036] In this embodiment of the invention, the assembly is loaded into a tooling fixture, and then the tooling fixture with the assembly is placed in a vacuum-sealed heating device for vacuum heat sealing. Figure 1The above is a schematic diagram of the tooling fixture in an embodiment of the present invention, including an upper template 12, a lower template 11, a support block 7 and a screw lock 3. The upper template 12 includes an upper mold upper block 4, an upper mold heat-equalizing block 5 and an upper mold lower block 6 stacked from top to bottom. The lower template 11 includes a lower mold upper block 8, a lower mold heat-equalizing block 9 and a lower mold lower block 10 stacked from top to bottom. The screw lock is used to lock the upper and lower templates, and can be pressurized with a torque wrench; the upper mold block and lower mold block are used for pressure support, keeping the upper and lower templates balanced after pressurization and heating; the upper mold heat spreader and lower mold heat spreader ensure uniform heating of the product; the upper mold block and lower mold block support the product and maintain balance after pressurization and heating; the support block is used to maintain the product at the preset thickness before bonding during pressurization and heating, preventing the product from deforming under gravity or pressure after softening at high temperature; the upper mold block, upper mold block, lower mold block, lower mold block and support block can be made of stainless steel, and the upper mold heat spreader and lower mold heat spreader can be made of copper. In this invention, the specific operation of loading the assembly into the tooling fixture is as follows: placing the lower template on the worktable; placing the assembly ( Figure 1 After the middle layer is stacked, the multilayer polyetherimide sheet 1) aligned with the positioning post 2 is placed in the center of the lower template; then support blocks are placed at both ends of the lower template; the upper template is pressed together with the hole position; pressure is applied by screw locking and torque wrench so that the upper and lower templates lock the assembly.

[0037] In this invention, the sealing agent treats the sealing surface, reducing the surface energy of PEI. The softening temperature is significantly lower than the Vicat softening and hot-melt temperatures. The upper and lower surfaces of PEI in contact with the tooling fixture remain the original material, and the Vicat softening temperature remains unchanged. High temperatures are required for the upper and lower surfaces to soften. Therefore, the pipes or structures on the sealing surface do not deform or deform minimally during the heat-sealing process. This invention employs a vacuum-assisted oven heating mode instead of a hot plate. Its advantages are: firstly, uniform temperature within the sealed space; and secondly, the vacuum largely eliminates air between the PEI sealing surfaces and within the oven, reducing air bubbles or weak seals caused by gas expansion during the sealing process, thus improving quality and yield.

[0038] After the vacuum heat sealing is completed, the material is cooled to obtain the bonded polyetherimide material; the cooling rate is preferably 10~20℃ / h, and can be 10~15℃ / h.

[0039] This invention employs a sealing agent-assisted heat sealing method. By optimizing the composition and content of the multi-component sealing agent, it is suitable for heat sealing of both large-size and small-size pipes. This reduces the heat sealing temperature, thereby minimizing deformation during the sealing process of double or multi-layer PEI structures. The method provided by this invention is applicable to the manufacture of high-precision PEI manifolds, distributors, and busbars with flow channels, improving the quality of the devices.

[0040] To further illustrate the present invention, the sealing aids and their preparation methods, as well as the bonding methods of polyetherimide materials provided by the present invention, are described in detail below with reference to examples. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0041] In this embodiment, the PEI sheet is SABIC ULTEM 1010 with a melting point of 340~400℃ and a glass transition temperature of 217℃.

[0042] Example 1 The bonding method for double-layer PEI channels (rectangular single-sided PEI double-layer sealing, single-layer PEI thickness is 8mm, channel width is 2mm, and depth is 1mm) is as follows: (1) Preheating treatment: Place the PEI board in a high-temperature sealed oven and control the temperature at 190℃ for 2 hours.

[0043] (2) Processing: The surface flow channel layer and positioning holes are processed on the PEI sheet after preheating.

[0044] (3) Activation treatment of PEI board sealing surface using sealing aid: The composition of sealing aid is: acetamide 60wt%, xylene (CAS No.: 1330-20-7) 20wt%, acetone 20wt%; spray the sealing aid onto the sealing surface of PEI board and activate for 120s.

[0045] (4) Loading into the tooling fixture: After aligning the two flow channel sealing surfaces, place them into the tooling fixture (e.g., Figure 1 As shown), it is locked by the positioning pin.

[0046] (5) Heat sealing: Place the tooling fixture into a vacuum oven (-30kPa), heat it to 150℃ at a heating rate of 5℃ / min, then heat it to 195℃ at a heating rate of 1℃ / min, heat seal for 16h, and then cool it down at a rate of 15℃ / h.

[0047] Figure 2 This is a diagram showing the effect of bonding the double-layer PEI channel in Example 1.

[0048] Example 2 Bonding of dual-layer multi-flow-path parallel PEI valve bodies: (1) Preheating treatment: Place the PEI board (the thickness of the PEI board is 9mm and 3mm respectively) in a high-temperature sealed oven, and control the temperature at 190℃ for 2 hours.

[0049] (2) Processing: The surface flow channel layer and positioning holes are processed on the PEI sheet after preheating.

[0050] (3) Activation treatment of PEI board sealing surface using sealing aid: The composition of sealing aid is: acetamide 55wt%, xylene (CAS No.: 1330-20-7) 25wt%, acetone 20wt%; spray the sealing aid onto the board sealing surface and activate for 120s.

[0051] (4) After aligning the flow channel sealing surfaces of the tooling fixture block, place it into the tooling fixture (such as...). Figure 1 As shown), it is locked by the positioning pin.

[0052] (5) Heat sealing: Place the tooling fixture into a vacuum oven (-35kPa), heat it to 150℃ at a heating rate of 5℃ / min, then heat it to 190℃ at a heating rate of 1℃ / min, heat seal for 20h, and then cool it down at a rate of 10℃ / h.

[0053] Figure 3 This is a diagram showing the effect of the unsealed flow channel semi-finished product after step (2) of Example 2 and the sealed flow channel semi-finished product after heat sealing in step (5). Figure 3 In the diagram, A1 is the liquid outlet channel, and B1, C1, and D1 are different liquid inlet channels. The measurement data for each channel A1 to D1 before and after heat sealing are shown in Table 1 and Table 2, respectively.

[0054] Table 1 Measurement data of unsealed flow channels

[0055] Table 2 Measurement data of closed flow channels

[0056] As can be seen from the data in Tables 1 and 2, the deformation in the width direction of the flow channel before and after sealing is 30~60μm, and the deformation in the depth direction is about 100μm. By adjusting and compensating for the semi-finished product size according to the deformation, the deviation of the width direction from the target accuracy can be less than 30μm (A1 target: width 0.25mm, depth 0.25mm; B1 / C1 / D1 target: width 0.50mm, depth 0.4mm).

[0057] Figure 4 This is a cross-sectional view of the closed flow channel in Example 2. Figure 4 It can be seen that the D-shaped flow channel did not shrink inward or collapse into the flow channel after sealing, and the sealing interface was flat and seamless.

[0058] The PEI valve body bonded in Example 2 was subjected to a pressure test using an airtightness tester (Wanken airtightness tester) to characterize the sealing strength. The results are shown in Table 3.

[0059] Table 3 Pressure Test Results

[0060] As can be seen from Table 3, the bonded PEI valve body has good sealing strength.

[0061] Comparative Example 1 The composition of the sealing agent was changed to: acetamide 30wt%, xylene (CAS No.: 1330-20-7) 40wt%, and acetone 30wt%. The bonding process and conditions were the same as in Example 2.

[0062] Figure 5 This is a diagram showing the effect of flow channel bonding in Comparative Example 1. Figure 5 The four flow channels have different widths and depths, with a depth-to-width ratio of 1:1. The widths of the four flow channels from left to right are 0.4mm, 0.6mm, 0.8mm, and 1.0mm, respectively. Cracks have appeared in the product.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A sealing aid, characterized in that, It includes the following components by mass percentage: amide compounds 50-80%, aromatic hydrocarbons 10-25%, and acetone 10-25%.

2. The sealing aid according to claim 1, characterized in that, It includes the following components by mass percentage: amide compounds 55-60%, aromatic hydrocarbons 20-25%, and acetone 15-20%.

3. The sealing aid according to claim 1 or 2, characterized in that, The amide compounds include one or more of formamide, acetamide, acetamide derivatives, acrylamide, and acrylamide derivatives.

4. The sealing aid according to claim 1 or 2, characterized in that, The aromatic hydrocarbons include one or more of benzene, toluene, and xylene.

5. A method for preparing the sealing aid according to any one of claims 1 to 4, characterized in that, Includes the following steps: The sealing aid is obtained by mixing amide compounds, aromatic hydrocarbons, and acetone.

6. A bonding method for polyetherimide materials, characterized in that, Includes the following steps: The sealing surfaces of the polyetherimide sheets to be bonded are activated with a sealing aid, and the sealing surfaces have flow channels; the sealing aid is the sealing aid according to any one of claims 1 to 4 or the sealing aid prepared by the preparation method according to claim 5; After aligning the flow channels on the sealing surfaces of each activated polyetherimide sheet, they are assembled together to obtain an assembly. The assembly is vacuum heat-sealed to obtain bonded polyetherimide material; the vacuum heat-sealing temperature is 150~200℃.

7. The bonding method according to claim 6, characterized in that, The number of polyetherimide sheets is greater than or equal to 2, the thickness of each polyetherimide sheet is independently 1~20mm, and the depth and width of the flow channel are 0.3~5mm.

8. The bonding method according to claim 6, characterized in that, The activation treatment time is 30~120s.

9. The bonding method according to claim 6, characterized in that, The heat preservation time for the vacuum heat sealing is 16~30h; when the temperature of the vacuum heat sealing is 150℃, the heating rate to the temperature of the vacuum heat sealing is 5~10℃ / min; when the temperature of the vacuum heat sealing is greater than 150℃, the heating procedure to the temperature of the vacuum heat sealing is: first, heat to 150℃ at a heating rate of 5~10℃ / min, and then heat to the temperature of the vacuum heat sealing at a heating rate of 0.5~1℃ / min.

10. The bonding method according to claim 6 or 9, characterized in that, The vacuum heat sealing is carried out in a vacuum-sealed heating device.

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