Long carbon chain nylon coating material for extruded busbar and preparation method of long carbon chain nylon coating material

Abstract

The invention discloses a long-carbon-chain nylon coating material for an extruded busbar and a preparation method of the long-carbon-chain nylon coating material, and belongs to the technical field of high polymer material modification. The long carbon chain nylon coating material is prepared from low-crystallinity long carbon chain nylon, a compatibilizer, an antioxidant, toner, a dispersant, a light stabilizer and the like, the crystallinity of the low-crystallinity long carbon chain nylon is smaller than 13%, and the melt flow rate under the condition of 235 DEG C / 2.16 kg is 10-30 g / 10 min. The low-crystallinity long-carbon-chain nylon is adopted to replace conventional homopolymerization long-carbon-chain nylon, and the problem that the adhesive force between a coating layer and a metal interface is reduced due to shrinkage after nylon is formed and crystallized is solved. The long-carbon-chain nylon coating material prepared by the preparation method disclosed by the invention is small in molding shrinkage rate, strong in metal adhesive force, high in elongation at break, good in tensile property and bending property, suitable for a three-dimensional bending molding process and capable of meeting the application requirements of a new energy automobile market.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material modification, and in particular relates to a long carbon chain nylon coating material for an extruded busbar and a preparation method thereof. Background Art

[0002] As a power module electrical connection component, busbars are widely used in the field of new energy vehicles. Compared with traditional automotive cables, busbars adapt to various wiring angles and vehicle structures; the rigid structure is simple to position, lower assembly costs, higher quality, and safer; busbars with the same cross-section can carry 10-20% more current than cables, which can shorten charging time.

[0003] Depending on the part structure and coating material, the busbar can be processed in different ways, such as heat shrink tubing, insert injection molding, plastic dipping, electrostatic spraying, extrusion coating (extrusion), etc. The busbar has extremely stringent requirements for coating or painting: the material needs to pass electrical testing certification and strict thermal cycle testing; it must be resistant to thermal runaway; the orange color representing high voltage must be long-lasting and stable, and will not fade even in high temperature environments for a long time; it must have high production efficiency, saving manufacturing time and costs. In order to avoid stress whitening or peeling off from the metal when the coating material is bent, resulting in problems such as reduced conductivity or even poor contact during the subsequent use of the busbar, the extrusion process, in particular, places high demands on the toughness of the coating material and its adhesion to the metal.

[0004] Long carbon chain nylon has high elongation and heat resistance, and its surface is smooth and defect-free after molding. It is very suitable for three-dimensional bending molding process, so it becomes an ideal coating material for extruded bus. During the processing of extruded bus, the inner layer of the coating material contacts the metal core material first, and the core material needs to be preheated to reduce the crystallization rate of nylon and improve the wettability of the coating material and metal; the outer layer of the coating material is solidified by water cooling, and the solidification rate of the outer layer is generally faster than that of the inner layer. Internal stress is easily retained in the nylon, causing the coating layer to warp toward the outer layer, affecting the adhesion effect. Most existing technologies improve the polarity and toughness of the material by blending compatibilizers and / or elastomers into homopolymerized long carbon chain nylon, thereby enhancing the adhesion between the nylon coating and the metal interface. Publication No. CN Chinese patent 117024953A discloses a high-toughness and high-metal-bonding polyamide composition and its preparation method. The composition comprises the following raw materials by weight: 55-95.5 parts of long-chain polyamide resin, 3-40 parts of elastomer binder, 0.2-3 parts of antioxidant, 0-3 parts of masterbatch, and 0-3 parts of light stabilizer; the elastomer binder is a polyether block amide. The composition of the invention uses a long-chain polyamide as the resin matrix, and there are strong polar amide groups and strong hydrogen bonds in the molecule, resulting in a high melting point. At the same time, the alkyl segment content in the long-chain polyamide molecule is The resin toughness and impact resistance are also good; on this basis, by adding a polyether block amide with a suitable melt index and polyether ratio, it acts as an "amphiphilic" elastomer adhesive containing polyamide segments and polyether segments, which not only ensures good interfacial compatibility between the adhesive and the nylon matrix, but also improves the intermolecular force and wetting effect between the adhesive and the metal core material, thereby effectively improving the elongation at break and metal adhesion of the polyamide composition, making the composition less prone to stress whitening or shelling from the metal after bending, and is suitable for busbar sheath materials. However, with the increase in the energy density of battery packs, the complexity of integrated connections of large-capacity cells increases, and the busbar bending curvature radius becomes larger, which puts higher requirements on the metal adhesion of extruded busbar coating materials. The existing method of using a compatibilizer and / or elastomer to improve the adhesion between the nylon coating and the metal interface is difficult to meet the use requirements. Summary of the Invention

[0005] In view of this, the present invention provides a long carbon chain nylon coating material for extruded busbar and a preparation method thereof. By selecting a long carbon chain nylon resin with low crystallinity to replace the conventional homopolymer long carbon chain nylon resin, the separation of the coating layer from the metal surface caused by the shrinkage of the nylon after molding and crystallization is improved, thereby improving the adhesion between the coating layer and the metal interface.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A long carbon chain nylon coating material for an extruded busbar is prepared from the following components in parts by weight:

[0008]

[0009] The low-crystallinity long-carbon-chain nylon includes low-crystallinity copolymerized long-carbon-chain nylon and / or transparent nylon. The low-crystallinity long-carbon-chain nylon has a crystallinity of less than 13% and a melt flow rate of 10-30 g / 10 min at 235° C. / 2.16 kg. When transparent nylon is present, the melt flow rate and crystallinity of the transparent nylon are both lower than those of the low-crystallinity copolymerized long-carbon-chain nylon.

[0010] The higher the nylon crystallinity, the greater the degree of shrinkage of the material after processing and molding, and the more likely it is that the adhesion between the coated nylon and the metal interface will decrease; if the nylon melt index is too small, the material's wettability to the metal surface will be poor, which will easily lead to poor adhesion between the coated nylon and the metal interface; if the nylon melt index is too large, the extrusion processing stability will be poor, which will easily cause uneven thickness on the upper and lower surfaces of the coated nylon; by using nylon resins with different melt flow rates and crystallinity, the difference in solidification time between the transparent nylon enriched in the outer layer and the copolymerized long carbon chain nylon enriched in the inner layer is reduced, avoiding the deterioration of the metal adhesion of the coating layer due to stress warping in the nylon.

[0011] As a further embodiment of the present invention: the low crystallinity copolymerized long carbon chain nylon is at least one of PA610 / PA66, PA612 / PA66, PA612 / PA610, PA612 / PA614, PA1012 / PA612, PA1012 / PA1010, and PA1012 / PA1212; preferably, the low crystallinity copolymerized long carbon chain nylon has a crystallinity of 5-13% and a melt flow rate of 15-30 g / 10 min at 235°C / 2.16 kg.

[0012] As a further embodiment of the present invention: the transparent nylon is at least one of PAMACM12, PAPACM12, PAMACM12 / Y, PAPACM12 / Y, PA6I / Y, and PATMDI / Y, wherein Y is one of PA612, PA1012, and PA1212; preferably, the crystallinity of the transparent nylon is less than 1%; the melt flow rate of the transparent nylon at 235°C / 2.16kg is 10-25g / 10min; more preferably, the weight portion of the transparent nylon is 0 to 50 parts.

[0013] As a further embodiment of the present invention, the compatibilizer is at least one of ethylene-octene copolymer grafted maleic anhydride (POE-g-MAH), ethylene-methyl acrylate copolymer grafted maleic anhydride (EMA-g-MAH), linear low-density polyethylene grafted maleic anhydride (LLDPE-g-MAH), and hydrogenated styrene-butadiene-styrene copolymer grafted maleic anhydride (SEBS-g-MAH); preferably, the maleic anhydride grafting rate of the compatibilizer is greater than 0.5%.

[0014] As a further embodiment of the present invention: the antioxidant is at least one of a hindered phenol antioxidant, an amine antioxidant, a phosphite antioxidant, and a thioester antioxidant; preferably, the antioxidant is a compound of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine (1098) and bis(2,4-dicumylphenyl)pentaerythritol diphosphite (S-9228).

[0015] As a further solution of the present invention: the toner is at least one of yellow toner, orange toner, red toner, white toner and black toner; preferably, the surface color of the material is between Ral2003 and Ral2011; more preferably, the surface color of the material is Ral2003.

[0016] As a further solution of the present invention: the dispersant is at least one of an amide compound, a stearate compound, and a metal soap compound; preferably, the dispersant is ethylene bisstearamide (EBS).

[0017] As a further embodiment of the present invention: the light stabilizer is at least one of a salicylate light stabilizer, a triazine / organic complex light stabilizer, a benzotriazole light stabilizer, a substituted acrylonitrile light stabilizer, and a benzophenone light stabilizer; preferably, the light stabilizer is 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-octyloxyphenol (UV-1164).

[0018] Another aspect of the present invention discloses a method for preparing the long carbon chain nylon coating material for the extruded busbar, comprising the following steps:

[0019] S1: Weigh the raw materials of each component according to the ratio and mix them to obtain a mixed material;

[0020] S2: adding the mixed material to the main feed port of a twin-screw extruder, and performing melting, extrusion, pelletizing, and drying to obtain a long carbon chain nylon coating material for an extruded busbar.

[0021] As a further solution of the present invention: the temperature of one zone of the twin-screw extruder is 150-190° C., the temperature of other zones and the die is 180-240° C.; the screw speed is 200-500 r / min.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention uses low-crystallinity long-carbon-chain nylon to replace conventional homopolymer long-carbon-chain nylon, reducing the crystallinity of nylon from the resin intrinsic perspective, and improving the problem of decreased adhesion between the coating layer and the metal interface caused by shrinkage after nylon molding.

[0024] 2. The present invention uses nylon resins with different crystallinity and melt flow rates to shorten the difference in solidification time between the inner and outer layers of the extruded coated nylon, and reduce the degree of deterioration in the metal adhesion of the coating layer caused by internal stress warping of the nylon.

[0025] 3. The present invention uses low-crystallinity long-carbon-chain nylon compounded with a compatibilizer to synergistically improve the toughness of the material and the compatibility between the components, reduce the water absorption rate and cost of the material, and at the same time, the compatibilizer reacts with the nylon resin to play a chain extension role, so that the material has both good tensile and bending properties. DETAILED DESCRIPTION

[0026] To facilitate understanding of the present invention, the present invention will be described more fully below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for describing specific embodiments and are not intended to limit the present invention.

[0028] The raw materials used in the following examples and comparative examples are all commercially available products, and their specific information is shown in Table 1:

[0029] Table 1

[0030]

[0031]

[0032] The above materials are all commercially available conventional products. It is understood that the above raw materials and reagents are only examples of some specific embodiments of the present invention to make the technical solution of the present invention clearer, and do not represent that the present invention can only adopt the above reagents. The specific scope in the claims shall prevail. In addition, the "parts" described in the examples and comparative examples, unless otherwise specified, all refer to parts by weight.

[0033] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0034] The examples and comparative examples were prepared using the following method:

[0035] S1: Weigh the raw materials of each component in the formula according to the weight parts in Table 2, place them in a high-speed mixer and stir for 8 minutes to obtain a mixed material;

[0036] S2: Add the mixed material into the main feed port of the twin-screw extruder, and after melting, extrusion, pelletizing and drying, the long carbon chain nylon coating material for the extruded bus is obtained.

[0037] In Examples 1-5 and Comparative Examples 1, 2, 3, and 6, the temperature of one zone of the twin-screw extruder was set to 170° C., the temperatures of the other zones and the die were set to 225° C., and the screw speed was 300 r / min.

[0038] In Comparative Example 4, the temperature of one zone of the twin-screw extruder was set to 160°C, the temperature of the other zones and the die was set to 200°C, and the screw speed was set to 300 r / min;

[0039] In Comparative Example 5, the temperature of one zone of the twin-screw extruder was set to 180° C., the temperature of the other zones and the die head was set to 235° C., and the screw speed was set to 300 r / min.

[0040] Table 2

[0041]

[0042] The extruded busbars prepared in each of the above examples were homogenized with long carbon chain nylon coating material particles, and then injection molded into specimens for performance testing. The test items and results are shown in Table 3:

[0043] Table 3

[0044]

[0045]

[0046] The test standards for the test items in Table 3 are as follows:

[0047] The tensile performance test standard refers to ISO527, the flexural performance test standard refers to ISO178, the impact performance test standard refers to ISO179, the water absorption (23℃ / 24h) test standard refers to ISO62, the volume resistivity test standard refers to IEC60093, the shrinkage test standard refers to ISO294, the heat deformation temperature test standard refers to ISO75, and the maximum peel force test standard refers to ISO4624.

[0048] According to the test results in Table 3, the long carbon chain nylon covering material for the extruded busbars of Examples 1 to 5 of the present invention has a small molding shrinkage (parallel shrinkage <0.5%, vertical shrinkage <0.6%), strong metal adhesion (maximum peel force ≥30N), high elongation at break (elongation at break >105%), and good tensile properties (tensile strength >37MPa, tensile modulus >1100MPa, elongation at break >105%) and bending properties (bending strength ≥40MPa, bending modulus >1100MPa).

[0049] A comprehensive comparison of Example 1 and Comparative Examples 1-2 shows that by using copolymerized long carbon chain nylon instead of homopolymerized long carbon chain nylon, the regularity and crystallinity of the nylon molecular chain can be destroyed, thereby reducing the shrinkage rate of the material after molding and significantly improving the adhesion between the coated nylon and the metal core material; adding a compatibilizer can improve the compatibility between nylon and each component to form a uniform blend. This uniform dispersion helps to reduce micropores and defects in nylon, thereby reducing water absorption and ensuring sufficient insulation of the coating material during use. At the same time, it improves the toughness of the material to meet the processing requirements of the extruded busbar three-dimensional bending molding process.

[0050] A comprehensive comparison of Example 2 and Comparative Examples 3-6 shows that by using copolymerized long carbon chain nylon with specific melt flow rate and crystallinity in combination with transparent nylon, the copolymerized long carbon chain nylon with high melt index preferentially contacts the metal core material during the extrusion process, and the solidification rate of the inner layer nylon is reduced by preheating the metal, while the low crystallinity transparent nylon in the outer layer is enriched and its solidification rate is accelerated by water cooling, so that the solidification time of the inner and outer layers of the coated nylon is close, avoiding the shrinkage and warping of the coated material due to the internal stress of the nylon, further reducing the shrinkage rate of the material, and making the vertical shrinkage rate closer to the horizontal shrinkage rate, thereby ensuring the durability of the adhesion effect of the coated nylon.

[0051] Although this specification is described according to implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0052] Therefore, the above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application; that is, all equivalent modifications made according to the scope of the claims of the present application are within the scope of protection of the claims of the present application.

Claims

1. A long carbon chain nylon coating material for an extruded busbar, characterized in that: It is prepared from the following components in parts by weight: The low-crystallinity long-carbon-chain nylon is a copolymerized long-carbon-chain nylon and / or a transparent nylon. The low-crystallinity long-carbon-chain nylon has a crystallinity of less than 13%, a melt flow rate of 10-30 g / 10 min at 235° C. / 2.16 kg, and both the melt flow rate and crystallinity of the transparent nylon are lower than those of the copolymerized long-carbon-chain nylon.

2. The long carbon chain nylon coating material for an extruded busbar according to claim 1, characterized in that: The copolymerized long carbon chain nylon is at least one of PA610 / PA66, PA612 / PA66, PA612 / PA610, PA612 / PA614, PA1012 / PA612, PA1012 / PA1010, and PA1012 / PA1212.

3. The long carbon chain nylon coating material for an extruded busbar according to claim 1, characterized in that: The transparent nylon is at least one of PAMACM12, PAPACM12, PAMACM12 / Y, PAPACM12 / Y, PA6I / Y, and PATMDI / Y, wherein Y is PA612, PA1012, or PA1212.

4. The long carbon chain nylon coating material for an extruded busbar according to claim 1, characterized in that: The compatibilizer is at least one of ethylene-octene copolymer grafted with maleic anhydride, ethylene-methyl acrylate copolymer grafted with maleic anhydride, linear low-density polyethylene grafted with maleic anhydride, and hydrogenated styrene-butadiene-styrene copolymer grafted with maleic anhydride; and the maleic anhydride grafting rate in the compatibilizer is greater than 0.5%.

5. The long carbon chain nylon coating material for an extruded busbar according to claim 1, characterized in that: The antioxidant is at least one of hindered phenol antioxidants, amine antioxidants, phosphite antioxidants, and thioester antioxidants.

6. The long carbon chain nylon coating material for an extruded busbar according to claim 1, characterized in that: The toner is at least one of yellow toner, orange toner, red toner, white toner and black toner.

7. The long carbon chain nylon coating material for an extruded busbar according to claim 1, characterized in that: The dispersant is at least one of an amide compound, a stearate compound, and a metal soap compound.

8. The long carbon chain nylon coating material for an extruded busbar according to claim 1, characterized in that: The light stabilizer is at least one of a salicylate light stabilizer, a triazine / organic complex light stabilizer, a benzotriazole light stabilizer, a substituted acrylonitrile light stabilizer, and a benzophenone light stabilizer.

9. A method for preparing the long carbon chain nylon coating material for an extruded busbar according to claim 1, characterized in that: The following steps are involved: S1: Weigh the raw materials of each component according to the ratio and mix them to obtain a mixed material; S2: adding the mixed material to the main feed port of a twin-screw extruder, and performing melting, extrusion, pelletizing, and drying to obtain a long carbon chain nylon coating material for an extruded busbar.

10. The method for preparing the long carbon chain nylon coating material for extruded busbar according to claim 9, characterized in that: The temperature of one zone of the twin-screw extruder is 150-190° C., the temperature of other zones and the die head is 180-240° C.; the screw speed is 200-500 r / min.

Images