Patent Application
20240409784
Batteries are used as power sources for electric vehicles. During the operation or charging of a vehicle battery, the battery heats up. As a result of the heating, the vehicle battery can age prematurely or be damaged due to heat-promoted chemical reactions. It is therefore common practice to provide cooling in order to keep the vehicle battery at an optimal operating temperature. Cooling plate assemblies (or simply cooling plates) through which fluid can flow have proven to be a suitable means for cooling items such as, for example, a vehicle battery.
Usually, individual components of cooling plate assemblies are joined together by, for example, welding, soldering, or brazing. At least one cooling channel having an inlet and an outlet is usually contained between the individual components of the cooling plate assemblies. Often, portions of fluid conduits are molded into the individual components of the cooling plate by mechanical shaping processes such that when they are assembled with the other components a fluid conduit is formed by joining the components.
Adhesive bonding may be better suited and/or more environmentally friendly than welding, soldering, and/or brazing, when joining especially for larger cooling plate components. However, coolant containing water/ethylene glycol, is often circulated through the fluid conduit and over time it may degrade the adhesive potentially resulting in failure of the cooling plate assembly. The present disclosure overcomes such problems by providing a cooling plate assembly that is formed by bonding component plates together with an adhesive that is resistant to damage cause by the coolant. More specifically, this is achieved by incorporating epoxy-functional hydrolyzable organosilane in the adhesive. Without wishing to be bound by theory, the present inventors believe that hydrolysis and condensation of the silane groups to form new crosslinks compensate for any adhesive strength drop due to coolant attack on the adhesive.
Accordingly, in a first embodiment, the present disclosure provides a cooling plate assembly comprising at least two component plates bonded together by an adhesive, wherein the adhesive and the at least two component plates collectively define at least one fluid conduit having an inlet and an outlet, and wherein the adhesive comprises an epoxy-functional hydrolyzable organosilane compound.
In a second aspect, the present disclosure provides a method of making a cooling plate assembly, the method comprising:
In yet another aspect, the present disclosure provides a curable composition comprising:
In some embodiments, the curable composition is formed into a gasket.
In this application, compounds that are not expressly identified as including one or more epoxy groups are free of epoxy groups.
Features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.
It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figures may not be drawn to scale.
Referring now to
The adhesive may be thermoplastic (e.g., a hot melt adhesive) or a thermoset (e.g., an at least partially cured curable (i.e., thermosetting) composition).
Exemplary thermoplastic adhesives may include polyamides, polyolefins (e.g., polystyrene, polyethylene, polypropylene, styrene-co-butadiene-co-styrene copolymers, polybutene, polyisoprene, and mixtures thereof).
Exemplary curable compositions that can be at least partially cured to form useful thermosets include, epoxy resins, phenolic resins, acrylic resins (e.g., free-radically polymerizable acrylates, methacrylates, acrylamides, and/or methacrylamides), alkyd resins, methylol urea resins, aminoplasts, cyanate resins, one-part and two-part urethane resins, and combinations thereof. Often epoxy resins are used.
In some embodiments, a curable composition comprises a dicyclopentadiene-based epoxy resin, a hydrophobic epoxy resin that imparts good coolant resistance. In some embodiments, the amount of dicyclopentadiene-based epoxy resin is 15 to 40 weight percent (e.g., 15 to 30 weight percent or 18 to 25 weight percent) based on the total weight of the curable resin.
The preparation of epoxidized cycloaliphatic dicyclopentadiene phenolic resin (a dicyclopentadiene-based epoxy resin) is well known in the art. Examples of such resins and their precursors suitable for use in curable compositions of some embodiments of the present disclosure are also described, for example, in U.S. Pat. No. 3,536,734 (Vegter et al.).
In some embodiments, the dicyclopentadiene-based epoxy resin is represented by the formula
wherein b is a positive integer. One such material is available as TACTIX 756 from Huntsman Advanced Chemicals, The Woodlands, Texas. Additional materials are described in U.S. Pat. No. 4,663,400 (Wang et al.) and U.S. Pat. No. 8,173,745 (Shirrell).
In some embodiments, curable compositions include an amount of 15 to 55 weight percent (e.g., 20 to 50 weight percent or 25 to 45 weight percent) of at least one aromatic glycidyl ether having a functional of 1.5 to 4, based on the total weight of the curable composition. Preferably, the aromatic glycidyl ether is liquid at 20° C. to facilitate a composition that is tacky at 20° C. Exemplary suitable aromatic glycidyl ethers may include bisphenol A diglycidyl ethers and bisphenol F diglycidyl ethers. As used herein, the term of “bisphenol A diglycidyl ether”, as the term is commonly used in the art, refers to compounds represented by the formula
wherein c is an integer greater than equal to 0.
Likewise, as used herein, the term of “bisphenol F diglycidyl ether”, as the term is commonly used in the art, refers to compounds represented by the formula
wherein c is an integer greater than or equal to 0.
Mixtures with different values of c are typical. Such materials are widely available from Dow Chemical, Midland, Michigan under the trade designation D.E.R (e.g., DER 332) and from Kaneka Texas Corporation, Pasadena, Texas (e.g., KANE ACE MX-257 which is a mixture of bisphenol A diglycidyl ether and a butadiene-acrylic copolymer core shell rubber particles).
Exemplary aromatic glycidyl ether having a functionality of 1.5 to 4 also include flexible difunctional aromatic glycidyl ether epoxy resins, for example, as available under the trade designation Cardolite (e.g., Cardolite NC-514) from Cardolite Corporation, Bristol, Pennsylvania.
In some embodiments, curable compositions include 5 to 20 weight percent or 7 to 19 weight percent of core shell rubber (CSR) particles based on the total weight of the curable composition. CSR particles may have a core selected from the group consisting of methyl methacrylate-butadiene-styrene (MBS) copolymers, methyl methacrylate-acrylonitrile-butadiene-styrene (MABS) copolymers or a combination thereof. CSR particles may also have a shell formed from an acrylic polymer, an acrylic copolymer, or a combination thereof, for example, as described in U. S., Pat. Appl. Publ. No. 2016/0297960 A1 (Aguirre-Vargas et al.). They are commercially available from suppliers such as, for example, Kaneka Texas Corporation and Kukdo Chemical, Seoul, South Korea.
In some embodiments, curable compositions include 1 to 8 weight percent (e.g., 2 to 5 weight percent) of hydroxyl-functionalized polyethersulfone. Hydroxyl-functionalized polyethersulfones are commercially available, for example, from Solvay, Brussels, Belgium under the trade designation VIRANTAGE (e.g., in grades VW-10700, VW-10200, VW-10300, and VW-10700). However, adding polyethersulfones typically decreases the flexibility of the cured adhesive and may decrease the peel adhesion to bonded substrates.
In some embodiments, curable compositions include 2 to 10 weight percent (e.g., 2 to 6 weight percent or 3 to 5 weight percent), based on the total weight of the curable composition, of phenoxy resin.
As used herein, phenoxy resins have the structural segment
wherein e is an integer greater than 1. Often e is greater than 50, greater than 100, or even greater than 150. Phenoxy resins are available from commercial sources such as Huntsman Advanced Chemicals, The Woodlands, Texas (e.g., under the trade designation PKHH). The addition of phenoxy resin typically improves the peel adhesion of the cured adhesive, although the coolant resistance is typically not as good as seen using polyethersulfone.
In some embodiments, curable compositions include 0.1 to 20 weight percent (e.g., 1 to 15 weight percent or 3 to 8 weight percent), based on the total weight of the curable composition, of epoxy-functional bisphenol A novolac resin. Often, the epoxy-functional bisphenol A novolac resin has an average epoxy functionality of 2 to 10 or 2.5 to 10). Mixtures of epoxy-functional bisphenol A novolac resins may be used. Epoxy-functional bisphenol A novolac resins are commercially available, for example, as EPON SU-2.5 and EPON SU-8 from Hexion Specialty Chemicals, Columbus, Ohio.
In practice of the present disclosure, at least one epoxy resin may be chosen to be free of ester, and/or urethane groups, or other hydrolyzable chemical bonds which can be hydrolyzed by water or alcoholyzed by alcohol and which may then lead to degradation of adhesive properties.
In some embodiments, curable compositions include 1 to 5 weight percent (e.g., 1 to 3 weight percent), based on the total weight of the curable composition, of surface-modified fumed silica. The surface modification is typically a hydrophobic surface treatment, but other surface treatments are also permissible. Fumed silicas are available commercially for suppliers such as, for example, Evonik Corp., Essen, Germany under the trade designation AEROSIL (e.g., in grades R816, R504, R104, R106, and R709).
In some embodiments, curable compositions include 0.1 to 20 weight percent (e.g., 3 to 15 weight percent), or 4 to 15 weight percent of a nitrogen-based epoxy curative to facilitate epoxy curing. Many nitrogen-based latent epoxy resin curatives are known and include: 3,3-daminodiphenylsulfone, 4,4-daminodiphenylsulfone, dicyandiamide; acyl hydrazides such as, for example, isophthalic acid dihydrazide; substituted imidazole curatives such as those available under the trade designation CURAZOL (e.g., 2MA-OK, 2MZ-Azine) from Evonik, Essen, Germany. In some embodiments, curable compositions include 0.01 to 6 weight percent (e.g., 0.01 to 2 weight percent), based on the total weight of the curable composition, of an accelerator for dicyandiamide to facilitate epoxy curing, although it may be omitted entirely. Examples include C2MAOK and C2MZ-Azine accelerators available from Air Products and Chemicals, Allentown, Pennsylvania, and aromatic substituted ureas available under the trade designation OMICURE from Huntsman Advanced Chemicals (e.g., in grades U-52M, U-24M, and U-405).
In some embodiments, curable compositions include 0.5 to 15 weight percent (e.g., 0.5 to 3 weight percent) of epoxy-functional hydrolyzable organosilane based on the total weight of the curable composition and/or adhesive, although other amounts may be used.
Useful epoxy-functional hydrolyzable organosilanes contain at least one hydrolyzable silyl group and at least one epoxy group. Examples of hydrolyzable silyl groups (e.g., —SiX3) include those having a silicon atom bonded to at least one group selected from alkoxy (e.g., methoxy or ethoxy), acyloxy (e.g., acetoxy), halogen (e.g., Cl, Br), and combinations thereof. Often the hydrolyzable group is a trimethoxysilyl group or a triethoxysilyl group.
Exemplary epoxy-functional hydrolyzable organosilane compounds include those represented by the formula
and wherein Z is a divalent organic group, and each L is independently a hydrolyzable group. Often Z contains one or more catenary oxygen atoms. In some embodiments, Z represents a hydrocarbyl group; for example, a hydrocarbyl group having from 2 to 36 carbon atoms, preferably 2 to 12 carbon atoms, and more preferably 24 carbon atoms. In some embodiments, Z represents a divalent group having the formula —CH2OR1— wherein R1 represents a divalent organic group; for example, a divalent hydrocarbylene group having 2 to 12 carbon atoms, preferably 24 carbon atoms.
In some embodiments, the epoxy-functional hydrolyzable organosilane is represented by the formula
wherein R and X are each independently epoxy-based moieties and a is an integer greater than or equal to 1. One exemplary such material is available commercially as DYNASYLAN VPS 4721 from Evonik Industries AG, Essen, Germany. In some embodiments, 1 to 10 weight percent of such compounds are included in the adhesive.
Examples of suitable epoxy-functional hydrolyzable organosilane compounds also include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)-ethyltriethoxysilane; 2-(3,4-epoxycyclohexyl)ethylrimethoxysilane; 5,6-epoxyhexyltriethoxysilane; 8-glycidoxyoctyltrimethoxysilane; (3-glycidoxypropyl)methyldiethoxysilane; (3-glycidoxypropyl)-methyldimethoxysilane; 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane; (3-glycidoxypropyl)-dimethylethoxysilane; and 1-(3-glycidoxypropyl)-1,1,3,3,3-pentaethoxy-1,3-disilapropane. In some embodiments, 1 to 10 weight percent of such compounds are included in the adhesive.
Combinations of epoxy-functional hydrolyzable organosilane compounds may be, and often are used.
Additional components and additives may also be included in curable composition according to the present disclosure such as, for example, colorants, antioxidants, thixotropes, and heat-conductive and/or electrically conductive filler.
Curable compositions according to the present disclosure is supplied as a film (either free-standing or support on one or more liner(s). In some embodiments, the curable composition comprises a unitary or multipart curable gasket. For example, a film of the curable composition may have gasket portions cut out by a die punch or laser that can be separated from weed portions during assembly of a cooling plate assembly according to the present disclosure.
For example, an exemplary method of making a cooling plate assembly comprises adhering a film of a curable composition having cutout portion corresponding to raised features of a first (e.g., bottom) component plate (e.g., see raised features 125 in
Cooling plate assemblies according to the present disclosure are useful, for example, for cooling batteries by placing them adjacent to (e.g., between) battery cells often found in hybrid or full electric vehicles.
Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.
Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Table 1 (below) reports abbreviations and descriptions of material used in the examples.
In this application ASTM refers to ASTM International, Conshohocken, Pennsylvania,
Grade 2024T3 bare aluminum panels were obtained from Erickson Metals of Minnesota, Inc., Coon Rapids, Minnesota. Prior to bonding with the samples, the panels were subjected to one of the following surface preparation processes:
The bare aluminum panels were slightly abraded with a green 3M SCOTCH-BRITE abrasive handpad (obtained from 3M Company) to remove the surface oxide layer for about 10-30 seconds. Residual dust was removed by means of compressed air, rinsing with solvent and allowing to dry for 10 minutes at approximately 25° C. The aluminum panel was then pre-treated using 3M Surface Pre-Treatment AC-130-2, 3M, Maplewood, Minnesota.
AC-130-2 and dried at 75° F. (23.9° C.) for 60 minutes according to the manufacturers directions, after which curable composition was applied, and heated at 350° F. (177° C.) for 30 minutes.
A curable composition was applied onto the end of the primed aluminum panel (measuring 4 inches×1 inch×0.063 inch (10.16 cm×2.54 cm×0.16 cm)) and a second equally sized primed aluminum panel was then applied over the sample at an overlap of 0.5 inches (12.7 mm). The assembly was clamped together using metal clamps and cured as described above.
Overlap shear strength was measured according to ASTM D1002-10 (2019) “Standard Test Method for Apparent Shear Strength of Single-Lap-Joint Adhesively Bonded Metal Specimens by Tension Loading (Metal-to-Metal)”, using a model SINTECH-30 tensile tester, obtained from MTS Corporation, Eden Prairie, Minnesota, at a grip separation rate of 0.05 inches/minute (1.3 mm/min). Three test panels were prepared and evaluated per each example.
Two primed and etched aluminum panels, one measuring 63 mils by 8-inches by 1-inches (1.60 mm by 20.32 cm by 2.54 cm), the other measuring 25 mils by 10-inches by 3-inches (0.635 mm by 25.4 cm by 2.54 cm), were bonded together as described in the Overlap Shear Strength Test. Test strips, from the bonded panel assembly were evaluated for floating roller peel strength of the thinner substrate, according to ASTM D3167-10 (2017) “Standard Test Method for Floating Roller Peel Resistance of Adhesives” using a tensile strength tester, model SINTECH 20 from MTS Corporation, at a separation rate of 6 inches/minute (15.24 cm/min) and at 70° F. (21.1° C.). Three test panels were prepared and evaluated per each example.
A set of the testing OLS specimens are made according to OLS standard procedure stated above.
After they are made, they were placed into PRESTONE DEX-COOL coolant (50/50 ethylene glycol-water, from Prestone Products Corp. of Lake Forest, Illinois) at 90° C. for aging. After two, four, six, nine, and/or twelve weeks, the sample was removed and OLS testing was performed.
Glass transition temperature (Tg) was determined by DMA and according to ASTM E1640-13 (2018). Samples approximately 1-2 mm thick, 6-10 mm wide and 20 mm long were machined from a larger sample of cured epoxy. Sample thickness and width were measured at three points along the specimen length using a micrometer, and the average of these measurements was used for calculation of cross-sectional area. Length of samples were measured by TA Instruments Q800 DMA. DMA testing was performed using a TA Instruments Q800 DMA. The Tg was used by the onset Tg of the storage modulus, according to ASTM D7028-07 (2015).
DER 332, SU-2.5, SU-8, MX 257, MX 154, MY 721, RA 95, EPON 1004 and DER 332 were combined in quantities (listed in grams), indicated in Table 2, and melted together at 300° F. (149° C.). After the mixture melted, the VW-10700, or PKHH, or its blend was added, and agitation continued at 300° F. (149° C.) until the polymers dissolved. After it was dissolved, T756 was added and agitated until it was melted.
The mixtures from Step 1 were cooled to 220° F. (104° C.) and Z-6040 and/or VPS 4721 (if needed) was added. The fumed silica was added and dispersed using a high-speed mixer along with curatives as reported in Table 2. Mixing time was limited to no more than two minutes and care was taken to ensure that the mixture did not over-heat during mixing.
The mixture from Step 2 was immediately used to draw a film on a silicone-coated liner. A film adhesive was achieved for each of the Examples and Comparative Examples listed in Table 2.
The samples underwent OLS, FRP, Coolant Immersion, and Glass Temperature Testing and the results are reported in Table 3.
All cited references, patents, and patent applications in this application are incorporated by reference in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in this application shall control.
The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2022/058429 | 9/7/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63252215 | Oct 2021 | US |
