High-thermal-conductivity oil-resistant composite material and preparation method thereof

Abstract

The invention discloses a high-thermal-conductivity oil-resistant composite material and a preparation method thereof.The composite material is of a three-layer symmetrical structure and sequentially comprises upper-layer domestic high-thermal-conductivity aramid paper, a modified polyamide-imide film and lower-layer domestic high-thermal-conductivity aramid paper from top to bottom, the upper-layer domestic high-thermal-conductivity aramid paper and the lower-layer domestic high-thermal-conductivity aramid paper are bonded with the modified polyamide-imide film through a modified polyurethane adhesive; and the preparation method of the composite material comprises the following steps: preparing the modified polyurethane adhesive, compounding for the first time, pre-curing at low temperature, compounding for the second time, post-curing, slitting and packaging. The heat-conducting property is greatly improved; the oil-resistant stability is excellent; the cost advantage is obvious; the process feasibility is high.

Description

Technical Field

[0001] This invention belongs to the field of thermal conductive materials technology, and in particular relates to a high thermal conductivity and oil-resistant composite material and its preparation method. Background Technology

[0002] The drive motor of new energy vehicles is the core of vehicle power. Its operating characteristics are "high speed, high power density, and compact installation". Compared with traditional industrial motors, drive motors have narrow installation space (mostly integrated into the chassis or power compartment), strong enclosure (need to withstand vibration and dust), and violent acceleration and deceleration processes (frequent start-stop and operating condition switching). As a result, the Joule heat and iron loss heat generated during motor operation are difficult to dissipate naturally and need to rely on oil cooling or water cooling systems for forced heat dissipation.

[0003] The core insulation component of the existing motor stator and rotor is YHY type slotted insulating paper, which is mainly composed of ordinary aramid paper and unmodified polyamide-imide (PI) film. Although it has basic insulation performance (breakdown voltage ≥15kV / mm), it has two major defects:

[0004] 1. Shortcoming in thermal conductivity: The thermal conductivity of ordinary YHY slot insulation paper is only [insert value here]. The thermal conductivity of the internal metal components of the motor (such as the electromagnetic wire and silicon steel sheets) is as high as [value missing]. As mentioned above, the insulating paper becomes a "thermal resistance bottleneck" in the heat dissipation path of the motor, which prevents the heat generated by the stator winding from being quickly transferred to the cooling system. Long-term operation can easily lead to failures such as aging of the insulation material and burning of the winding.

[0005] 2. Insufficient oil resistance: In oil-cooled motors, the insulating paper needs to be immersed in cooling oil (such as synthetic ester oil) for a long time. The adhesive and PI film of ordinary YHY insulating paper have poor oil resistance. After long-term immersion in oil, "swelling and adhesion failure" are likely to occur, resulting in the peeling of the composite layer and the decay of insulation performance (the tensile strength retention rate is less than 70% after immersion in oil for 1000 hours, which does not meet the requirements of GB / T11547-2010 "Determination of the resistance of plastics to liquid chemical reagents").

[0006] Furthermore, existing high thermal conductivity insulation materials mostly rely on imported aramid paper (such as DuPont Nomex® 411 from the United States), which is costly (approximately 80 yuan / m²). 2 Furthermore, the thermally conductive fillers added to the adhesives are mostly micron-sized (such as micron-sized alumina), which can easily lead to uneven coating and decreased bond strength (peel strength < 5N / 25mm). Therefore, developing a composite material that is "domestically replaceable, has high thermal conductivity, is oil-resistant and stable, and has feasible processing" is of great significance for reducing the cost of new energy vehicle motors and improving operational reliability. Summary of the Invention

[0007] This invention provides a high thermal conductivity and oil-resistant composite material and its preparation method. The thermal conductivity of this composite material is significantly improved compared to ordinary YHY slot insulation paper, which can quickly transfer heat from the motor stator windings, thereby greatly reducing the motor operating temperature and significantly extending the motor life. By adding a modified polyamide-imide film with polytetrafluoroethylene micropowder and an oil-resistant adhesive cured with isocyanate, the tensile strength and peel strength retention rates of the composite material are maintained at high values ​​after 1000 hours of oil immersion, with no interlayer delamination. Using domestically produced high thermal conductivity aramid paper instead of imported aramid paper can greatly reduce material costs, and the preparation process is compatible with existing production lines, requiring no additional equipment. The adhesive uses nanofillers, has stable coating viscosity, enables continuous production, and has good product performance uniformity. In summary, this invention solves the problems in the background technology.

[0008] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0009] The present invention discloses a high thermal conductivity and oil-resistant composite material, wherein the composite material has a three-layer symmetrical structure, consisting of an upper layer of domestically produced high thermal conductivity aramid paper, a modified polyamide-imide film, and a lower layer of domestically produced high thermal conductivity aramid paper from top to bottom. Both the upper and lower layers of domestically produced high thermal conductivity aramid paper are bonded to the modified polyamide-imide film by a modified polyurethane adhesive.

[0010] The thickness of the upper and lower layers of domestically produced high thermal conductivity aramid paper is 50-100 μm, and the thermal conductivity is... Quantitative amount 80-120g / m 2， Tensile strength ≥200MPa;

[0011] The modified polyamide-imide film has a thickness of 20-50 μm, a breakdown voltage of ≥25 kV / mm, and contains an oil-resistant modifier.

[0012] The modified polyurethane adhesive is composed of solvent-based polyurethane adhesive, nano-thermal conductive filler, curing agent, and solvent. Its solid content is 30-40%, viscosity is 15-25s, and thermal conductivity is [not specified]. Peel strength ≥8N / 25mm.

[0013] Furthermore, the oil-resistant modifier added to the modified polyamide-imide film is polytetrafluoroethylene micro powder, with a content of 3-8 wt% and a particle size of 1-5 μm.

[0014] Furthermore, the specific formulation of the modified polyurethane adhesive is as follows: solvent-based polyurethane adhesive: 50-70%, nano-thermal conductive filler: 2-5%, curing agent: 1-3%, solvent: 22-47%.

[0015] Furthermore, the nano-thermal conductive filler is nano-boron nitride with a particle size of 50-100 nm, and the amount added is 5-15% of the solid content of the solvent-based polyurethane adhesive.

[0016] Furthermore, in the modified polyurethane adhesive, the curing agent is an isocyanate, and the amount added is 3-8% of the solids of the solvent-based polyurethane adhesive, and the solvent is acetone.

[0017] The preparation method of the high thermal conductivity and oil-resistant composite material includes the following steps:

[0018] Step 1: Preparation of modified polyurethane adhesive: Add solvent to the mixing tank, stir, and then add solvent-based polyurethane adhesive, nano thermally conductive filler and curing agent in sequence. After stirring evenly, measure the viscosity. If it is qualified, it can be used for later use.

[0019] Step 2: First lamination: After coating and solvent evaporation in an oven, the modified polyamide-imide film is laminated with the lower layer of domestic high thermal conductivity aramid paper under high temperature and high pressure on the pressure roller, and then wound up to obtain a double-layer semi-finished product.

[0020] Step 3: Low-temperature pre-curing: Insulate the double-layer semi-finished product at 60-80℃ for 12 hours;

[0021] Step 4: Second lamination: Repeat the coating-lamination process of Step 2 with the pre-cured double-layer semi-finished product, and laminate it with the upper layer of domestic high thermal conductivity aramid paper, and then roll it up to obtain a three-layer semi-finished product.

[0022] Step 5: Post-curing: Curing the three-layer semi-finished product at a stepped temperature of 60℃ / 2h → 100℃ / 2h → 130℃ / 3h, and inspecting it after cooling to ensure it passes inspection;

[0023] Step 6: Slitting and Packaging: According to the order requirements, the qualified semi-finished products are slitting and packaged to obtain the finished products.

[0024] Furthermore, in step 1, the stirring speed is 500-800 rpm, the total stirring time is 15-25 min, and the room temperature is controlled at 20-25℃.

[0025] Furthermore, in step 2, the coating amount is 8-12 g / m², the oven is a three-section type with temperatures of 80-100℃, 120-140℃, and 150-170℃ respectively, the pressure roller temperature is 160-180℃, the pressure is 0.3-0.5 MPa, and the traction speed is 5-10 m / min.

[0026] The present invention has the following advantages over the prior art:

[0027] (1) Significantly improved thermal conductivity: The thermal conductivity of this composite material is significantly improved compared with ordinary YHY slot insulation paper, which can quickly transfer the heat of the motor stator winding, so as to greatly reduce the motor operating temperature and thus greatly extend the motor life.

[0028] (2) Excellent oil resistance and stability: By adding polytetrafluoroethylene micro powder to the modified polyamide-imide film and the oil-resistant adhesive after isocyanate curing, the tensile strength retention rate and peel strength retention rate of the composite material are maintained at a high value after immersion in oil for 1000h, and there is no interlayer peeling phenomenon.

[0029] (3) Significant cost advantage: Using domestically produced high thermal conductivity aramid paper to replace imported aramid paper can greatly reduce material costs, and the preparation process is compatible with existing production lines, requiring no additional equipment.

[0030] (4) High process feasibility: The adhesive uses nano fillers, the coating viscosity is stable, continuous production can be realized, and the product performance is uniform.

[0031] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart illustrating the preparation process of a high thermal conductivity and oil-resistant composite material according to the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be understood that the terms "relative", "one end", "inner", "lateral", "end", "both ends", "both sides", "front", "one end face", "the other end face", etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0036] Please see Figure 1 As shown, the present invention provides a high thermal conductivity and oil-resistant composite material. The composite material has a three-layer symmetrical structure, consisting of an upper layer of domestically produced high thermal conductivity aramid paper, a modified polyamide-imide film, and a lower layer of domestically produced high thermal conductivity aramid paper, from top to bottom. Both the upper and lower layers of domestically produced high thermal conductivity aramid paper are bonded to the modified polyamide-imide film using a modified polyurethane adhesive.

[0037] The thickness of the upper and lower layers of domestically produced high thermal conductivity aramid paper is 50-100μm, and the thermal conductivity is... Quantitative amount 80-120g / m 2， Tensile strength ≥200MPa;

[0038] The modified polyamide-imide film has a thickness of 20-50μm, a breakdown voltage ≥25kV / mm, and contains an oil-resistant modifier.

[0039] Modified polyurethane adhesives consist of solvent-based polyurethane adhesives, nano-thermal conductive fillers, curing agents, and solvents. Their solid content is 30-40%, viscosity is 15-25s, and thermal conductivity is [not specified]. Peel strength ≥8N / 25mm;

[0040] Thermal conductivity of composite materials Its oil resistance meets GB / T11547-2010, and its tensile strength retention rate is ≥85% after immersion in oil for 1000 hours.

[0041] The oil-resistant modifier added to the modified polyamide-imide film is polytetrafluoroethylene micro powder (or fluororubber micro powder), with a content of 3-8 wt% and a particle size of 1-5 μm.

[0042] The specific formulation of the modified polyurethane adhesive is as follows: solvent-based polyurethane adhesive (50% solid content): 50-70%, used to provide the bonding base; nano thermally conductive filler: 2-5%, used to improve thermal conductivity; curing agent: 1-3%, crosslinks with polyurethane to enhance oil resistance; solvent: 22-47%, used to adjust viscosity for easy coating.

[0043] The nano thermally conductive filler is nano boron nitride (or nano aluminum oxide), with a particle size of 50-100 nm, and the addition amount is 5-15% of the solid content of the solvent-based polyurethane adhesive.

[0044] In the modified polyurethane adhesive, the curing agent is an isocyanate, and the amount added is 3-8% of the solids of the solvent-based polyurethane adhesive. The solvent is acetone (or ethyl acetate).

[0045] A method for preparing a high thermal conductivity and oil-resistant composite material includes the following steps:

[0046] Step 1: Preparation of modified polyurethane adhesive: Add solvent to the mixing tank, stir, and then add solvent-based polyurethane adhesive, nano thermally conductive filler, and curing agent in sequence. After stirring evenly, measure the viscosity (it needs to reach 15-25s, Coat 4 cup). If it is qualified, it can be used for later use.

[0047] Step 2: First lamination: After coating and solvent evaporation in an oven, the modified polyamide-imide film is laminated with the lower layer of domestic high thermal conductivity aramid paper under high temperature and high pressure on the pressure roller, and then wound up to obtain a double-layer semi-finished product.

[0048] Step 3: Low-temperature pre-curing: Insulate the double-layer semi-finished product at 60-80℃ for 12 hours;

[0049] Step 4: Second lamination: Repeat the coating-lamination process of Step 2 with the pre-cured double-layer semi-finished product, and laminate it with the upper layer of domestic high thermal conductivity aramid paper, and then roll it up to obtain a three-layer semi-finished product.

[0050] Step 5: Post-curing: Curing the three-layer semi-finished product at a stepped temperature of 60℃ / 2h → 100℃ / 2h → 130℃ / 3h, and inspecting it after cooling to ensure it passes inspection;

[0051] Step 6: Slitting and Packaging: According to the order requirements, the qualified semi-finished products are slitting and packaged to obtain the finished products.

[0052] In step 1, the stirring speed is 500-800 rpm, the total stirring time is 15-25 min, and the room temperature is controlled at 20-25℃.

[0053] In step 2, the coating amount is 8-12 g / m², the oven is a three-section oven with temperatures of 80-100℃, 120-140℃, and 150-170℃ respectively, the pressure roller temperature is 160-180℃, the pressure is 0.3-0.5 MPa, and the traction speed is 5-10 m / min.

[0054] Example 1:

[0055] I. Material Preparation

[0056] 1. Upper / lower aramid paper: Domestic high thermal conductivity para-aramid paper, 80μm thick, thermal conductivity... Quantitative measure: 100g / m²;

[0057] 2. Intermediate PI film: Modified polyamide-imide film, 30μm thick, with 5wt% polytetrafluoroethylene micro powder (oil-resistant modifier) ​​added, breakdown voltage 28kV / mm;

[0058] 3. Modified polyurethane adhesive formulation (mass ratio): 60% solvent-based polyurethane (50% solid content) + 3% nano boron nitride (80nm particle size) + 2% isocyanate curing agent + 35% acetone, viscosity 20s (25℃, Forecast cup 4).

[0059] II. Preparation Process

[0060] 1. Adhesive preparation: Add acetone to the mixing tank, add polyurethane while stirring at 800 rpm, then add nano boron nitride and stir for 10 min, finally add curing agent and stir for 5 min. After the viscosity is qualified, transfer it to the glue tank.

[0061] 2. First lamination: Unwind PI film #1 → Coat with adhesive (10g / ㎡ dry weight) → Oven (80℃→130℃→160℃) → Lay with the lower aramid paper pressure roller (170℃, 0.4MPa, 8m / min) → Rewind to obtain a double-layer semi-finished product;

[0062] 3. Low-temperature pre-curing: Incubate in a 70℃ drying oven for 12 hours;

[0063] 4. Second lamination: Unwind the double-layer semi-finished product No. 1 → Coat with adhesive (10g / ㎡ dry weight) → Oven → Laminate with the upper aramid paper (same parameters as the first time) → Rewind to obtain a three-layer semi-finished product;

[0064] 5. Post-curing: 60℃ / 2h → 100℃ / 2h → 130℃ / 3h;

[0065] 6. Slitting: Slitting into discs with a width of 100mm and a length of 300m.

[0066] III. Performance Test Results

[0067] 1. Thermal conductivity: (Hotline method, GB / T10297-2015);

[0068] 2. Peel strength: 9.2N / 25mm (GB / T2790-1995);

[0069] 3. Oil immersion performance: After immersion in synthetic ester oil for 1000 hours (120℃), the tensile strength retention rate is 88% (GB / T11547-2010).

[0070] 4. Breakdown voltage: 23.5kV / mm (GB / T1408.1-2016).

[0071] Example 2:

[0072] I. Material Preparation

[0073] 1. Upper / lower aramid paper: Domestic high thermal conductivity aramid paper, 60μm thick, thermal conductivity coefficient Quantitative amount 80g / m²;

[0074] 2. Intermediate PI film: Modified PI film, 25μm thick, with 3wt% fluororubber micro powder added, breakdown voltage 26kV / mm;

[0075] 3. Modified polyurethane adhesive formulation: 55% solvent-based polyurethane (50% solid content) + 4% nano-alumina (60nm particle size) + 1.5% curing agent + 40.5% ethyl acetate, viscosity 18s.

[0076] 2. Preparation process

[0077] Except for the pressure roller temperature of 165℃, the traction speed of 6m / min, and the post-curing temperature of 125℃, the other steps are the same as in Example 1.

[0078] 3. Performance test results

[0079] 1. Thermal conductivity: ;

[0080] 2. Peel strength: 8.5N / 25mm;

[0081] 3. Oil immersion tensile strength retention rate: 86%;

[0082] 4. Breakdown voltage: 22.8kV / mm.

[0083] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high thermal conductivity and oil-resistant composite material, characterized in that, The composite material has a three-layer symmetrical structure, consisting of an upper layer of domestically produced high thermal conductivity aramid paper, a modified polyamide-imide film, and a lower layer of domestically produced high thermal conductivity aramid paper, from top to bottom. Both the upper and lower layers of domestically produced high thermal conductivity aramid paper are bonded to the modified polyamide-imide film using a modified polyurethane adhesive. The thickness of the upper and lower layers of domestically produced high thermal conductivity aramid paper is 50-100 μm, and the thermal conductivity is... Quantitative amount 80-120g / m 2， Tensile strength ≥200MPa; The modified polyamide-imide film has a thickness of 20-50 μm, a breakdown voltage of ≥25 kV / mm, and contains an oil-resistant modifier. The modified polyurethane adhesive is composed of solvent-based polyurethane adhesive, nano-thermal conductive filler, curing agent, and solvent. Its solid content is 30-40%, viscosity is 15-25s, and thermal conductivity is ≥ [missing information]. Peel strength ≥8N / 25mm.

2. The high thermal conductivity and oil-resistant composite material according to claim 1, characterized in that, The oil-resistant modifier added to the modified polyamide-imide film is polytetrafluoroethylene micro powder, with a content of 3-8 wt% and a particle size of 1-5 μm.

3. The high thermal conductivity and oil-resistant composite material according to claim 1, characterized in that, The specific formulation of the modified polyurethane adhesive is as follows: solvent-based polyurethane adhesive: 50-70%, nano-thermal conductive filler: 2-5%, curing agent: 1-3%, solvent: 22-47%.

4. The high thermal conductivity and oil-resistant composite material according to claim 1, characterized in that, The nano-thermal conductive filler is nano-boron nitride with a particle size of 50-100nm, and the addition amount is 5-15% of the solid content of the solvent-based polyurethane adhesive.

5. The high thermal conductivity and oil-resistant composite material according to claim 1, characterized in that, In the modified polyurethane adhesive, the curing agent is an isocyanate, and the amount added is 3-8% of the solids of the solvent-based polyurethane adhesive, and the solvent is acetone.

6. The method for preparing a high thermal conductivity and oil-resistant composite material according to claim 1, characterized in that, The preparation of a high thermal conductivity and oil-resistant composite material according to any one of claims 1-5 comprises the following steps: Step 1: Preparation of modified polyurethane adhesive: Add solvent to the mixing tank, stir, and then add solvent-based polyurethane adhesive, nano thermally conductive filler and curing agent in sequence. After stirring evenly, measure the viscosity. If it is qualified, it can be used for later use. Step 2: First lamination: After coating and solvent evaporation in an oven, the modified polyamide-imide film is laminated with the lower layer of domestic high thermal conductivity aramid paper under high temperature and high pressure on the pressure roller, and then wound up to obtain a double-layer semi-finished product. Step 3: Low-temperature pre-curing: Insulate the double-layer semi-finished product at 60-80℃ for 12 hours; Step 4: Second lamination: Repeat the coating-lamination process of Step 2 with the pre-cured double-layer semi-finished product, and laminate it with the upper layer of domestic high thermal conductivity aramid paper, and then roll it up to obtain a three-layer semi-finished product. Step 5: Post-curing: Curing the three-layer semi-finished product at a stepped temperature of 60℃ / 2h → 100℃ / 2h → 130℃ / 3h, and inspecting it after cooling to ensure it passes inspection; Step 6: Slitting and Packaging: According to the order requirements, the qualified semi-finished products are slitting and packaged to obtain the finished products.

7. The method for preparing a high thermal conductivity and oil-resistant composite material according to claim 6, characterized in that, The stirring speed in step 1 is 500-800 rpm, the total stirring time is 15-25 min, and the room temperature is controlled at 20-25℃.

8. The method for preparing a high thermal conductivity and oil-resistant composite material according to claim 6, characterized in that, In step 2, the coating amount is 8-12 g / ㎡, the oven is a three-section oven with temperatures of 80-100℃, 120-140℃, and 150-170℃ respectively, the pressure roller temperature is 160-180℃, the pressure is 0.3-0.5MPa, and the traction speed is 5-10m / min.

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