Graphite products and their manufacturing methods

Abstract

This invention relates to graphite articles and methods for manufacturing the same. The invention provides a graphite article formed from wrinkled graphite sheets. The wrinkled graphite sheet has a first main surface and a second main surface disposed opposite to the first main surface, and a plurality of large wrinkles, each large wrinkle having a plurality of associated micro wrinkles, wherein each micro wrinkle is smaller than the associated large wrinkle. Compared to unwrinkled graphite sheets, the wrinkled graphite article has improved flexibility. The wrinkled graphite sheet can be formed from sheets of flexible natural graphite or sheets of synthetic graphite.

Description

[0001] This application is a divisional application of the invention patent application filed on January 11, 2019, with application number 201980005723.1 (international application number PCT / IB2019 / 050231) and entitled "Graphite Articles and Methods for Manufacturing the Same". Technical Field

[0002] The articles described herein generally relate to the field of graphite products, particularly three-dimensional graphite products formed from sheets through a wrinkling process. Background Technology

[0003] Graphite products have been used in the thermal management of various devices. This previous use of graphite includes heat dissipation away from the heat source along the z-direction (through the plane of the product) or heat diffusion away from hot spots on the heat source along the xy-direction (within the plane of the product). Summary of the Invention Attached Figure Description

[0004] Figures 1a to 1b The image shows a flexible graphite sheet before it is wrinkled.

[0005] Figure 2 The graphite product is shown as formed by wrinkling graphite sheets;

[0006] Figure 3 The graphite product is shown as formed by wrinkling graphite sheets;

[0007] Figures 4a to 4d The wrinkling process of graphite sheets is shown;

[0008] Figure 5 A wrinkled bag is shown, which is formed by wrinkling a flexible graphite sheet on a flat carrier with a scraper.

[0009] Figure 6 A wrinkled bag is shown, which is formed by wrinkling a flexible graphite sheet on a cylindrical Yankee carrier with a scraper.

[0010] Figure 7 A laminated article including wrinkled graphite is shown;

[0011] Figure 8 The liquid retained in the folds of a wrinkled graphite article is shown;

[0012] Figure 9 The calendering of wrinkled graphite articles is shown to impart a uniform thickness to the wrinkled sheets.

[0013] Figure 10 It is an image of one (1) or more large folds;

[0014] Figure 11The tensile strength of the sample before the tensile strength test is shown:

[0015] Figure 12 The results after the tensile strength test are shown. Figure 11 The tensile strength sample shown;

[0016] Figure 13 It shows Figure 11 and Figure 12 The tensile strength test results of the sample shown are as follows;

[0017] Figure 14 It shows Figure 13 Part of the tensile strength test results;

[0018] Figures 15a to 15b The image shows wrinkled graphite sheets drawn or formed into enclosures;

[0019] Figure 16 The image shows a folded, wrinkled graphite sheet; and

[0020] Figure 17 A wrinkled graphite sheet forming an article is shown, the article having wrinkled portions and unwrinkled portions. Detailed Implementation

[0021] Now refer to Figure 1a and Figure 1b Graphite 1 consists of hexagonal arrays or networks of carbon atoms 3, or layers 2 of crystal planes. These hexagonally arranged carbon atom planes 2 are substantially flat and oriented or ordered so that they are substantially parallel and equidistant from each other. These substantially flat, parallel, equidistant carbon atom layers (commonly referred to as graphene layers or basal planes) are linked or bonded together, and their arrangement is within microcrystals. Highly ordered graphite consists of relatively large microcrystals that are highly aligned or oriented relative to each other and have well-ordered carbon layers. In other words, highly ordered graphite has a highly preferred microcrystal orientation. It should be noted that graphite has an anisotropic structure and therefore exhibits or possesses many properties with high orientation, such as thermal and electrical conductivity.

[0022] Briefly, the flexible graphite sheet (approximately shown in 4) is characterized by a laminated structure of carbon 5, that is, a structure composed of stacks or sheets 2 of carbon atoms 3 held together by weak van der Waals forces. When considering the graphite structure, the two axes or directions generally refer to the "c" axis or direction and the "a" axis or direction. For simplicity, the "c" axis or direction can be considered as perpendicular to the carbon layers. The "a" axis or direction can be considered as parallel to the carbon layers or perpendicular to the "c" direction. The graphite suitable for manufacturing the flexible graphite sheet 4 has a very high degree of orientation.

[0023] As mentioned above, the binding force that holds the parallel layers of carbon atoms together is merely a weak van der Waals force. Natural graphite can be treated to significantly open up the spacing between overlapping carbon layers or sheets, thereby providing significant expansion in the direction perpendicular to the carbon layers (i.e., the "c" direction), resulting in an intumescent graphite structure that essentially retains the layered characteristics of the carbon layers.

[0024] Flake graphite has expanded dramatically, and more specifically, to the point that the final thickness or "c" dimension is approximately 80 times or more of the original "c" dimension. This flake graphite can be formed into, for example, webs, paper, strips, tapes, foils, pads, etc. (often referred to as "flexible graphite") without the need for binders to adhere or integrate the expanded graphite sheets. It is considered possible to form graphite particles into integrated flexible sheets by compression without using any binder, because mechanical interlocking or cohesion is achieved between a large number of expanded graphite particles that have expanded to have a final thickness or "c" dimension approximately 80 times or more of the original "c" dimension.

[0025] In addition to its flexibility, as mentioned above, sheet 4 is found to have a high degree of anisotropy relative to thermal conductivity due to the orientation of the expanded graphite particles and the graphite layers that are substantially parallel to the opposing sides of the sheet produced by high compression, making it particularly suitable for heat dissipation applications. Sheet 4 thus produced is flexible, possesses good strength, and has a high degree of orientation.

[0026] In brief, the process of producing flexible, non-adhesive anisotropic graphite sheet materials (e.g., webs, paper, strips, tapes, foils, pads, etc.) involves compressing or compacting expanded graphite particles under a predetermined load without a binder, thereby forming a substantially flat, flexible, integrated graphite sheet. The expanded graphite particles have a "c"-direction dimension up to approximately 80 times or greater than the original particle size. Once compressed, the expanded graphite particles, which appear roughly worm-like or worm-like, retain their compression deformation and align with the opposing main surfaces of the sheet. The density and thickness of the sheet can be varied by controlling the degree of compression. The density of sheet 4 can range from approximately 0.04 g / cc to approximately 2.0 g / cc.

[0027] The flexible graphite sheet 4 exhibits significant anisotropy due to the alignment of graphite particles parallel to the main opposing, parallel surfaces of the sheet. This anisotropy increases as the sheet is compressed to increase orientation. In the compressed anisotropic sheet 4, the thickness (i.e., the direction perpendicular to the opposing parallel sheet surfaces) includes the "c" direction, and the direction of variation along the length and width (i.e., along or parallel to the opposing main surfaces) includes the "a" direction. For the "c" and "a" directions, the thermal and electrical properties of the sheet differ significantly (by several orders of magnitude).

[0028] Now for reference Figure 2 The three-dimensional graphite article described herein is generally shown as 10. In one or more examples, the graphite article 10 may be formed from a flexible graphite sheet 4, which, as described in further detail below, is wrinkled to form a wrinkled graphite sheet 12.

[0029] One embodiment of the flexible graphite sheet 4 is a compressed exfoliated graphite sheet, particularly natural graphite. As mentioned above, graphite is a crystalline form of carbon containing covalently bonded atoms in planar layers with weaker bonds between these planes. By treating graphite particles (e.g., natural flake graphite) with intercalation materials such as solutions of sulfuric acid and nitric acid, the crystal structure of graphite reacts to form a compound of graphite and intercalation material. The treated graphite particles are referred to as "particles of intercalated graphite." When exposed to high temperatures, the intercalated graphite particles expand in an accordion-like manner in the "c" direction (i.e., in the direction perpendicular to the crystal planes of graphite) to 80 times or more of their original volume. The exfoliated graphite particles have a worm-like appearance and are therefore commonly referred to as worms. Worms can be compressed together to form a flexible sheet, which, unlike the original flake graphite, can be formed and cut into various shapes.

[0030] An example of a flexible graphite sheet 4 formed from natural graphite that can be used according to the present invention is available from NeoGraf in Lakewood, Ohio. TM Solutions LLC obtained HITHERM TM Flexible graphite or SPREADERSHIELD TM Flexible graphite.

[0031] In one or more other examples, the flexible graphite sheet 4 can be formed from synthetic graphite, which is formed from graphitized polymers. The flexible graphite sheet 4 can be manufactured by the pyrolysis of a polymer film (also known as a pyrolytic graphite sheet). The precursor for the flexible graphite sheet formed from the graphitized polymer can be a polymer film selected from: polybenzoxadiazole (POD), polybenzothiazole (PBT), polybenzobisthiazole (PBBT), polybenzoxazole (PBO), polybenzodioxazole (PBBO), poly(phenylenetetracarboximide) (PI), poly(phenylene-isophthalamide) (PPA), poly(phenylenebenzimidazole) (PBI), poly(phenylenebenzimidazole) (PPBI), polythiazole (PT), and poly(p-phenylenevinylene) (PPV). Polybenzoxadiazoles include polyphenylene-1,3,4-oxadiazole and its isomers. When heat-treated in a suitable manner, these polymers can be converted into high-quality graphite. Although the polymers used for starting the membrane are described as being selected from POD, PBT, PBBT, PBO, PBBO, PI, PPA, PBI, PPBI, PT, and PPV, other polymers that can produce high-quality graphite through heat treatment may also be used.

[0032] An example of a flexible graphite sheet 4 formed from synthetic graphite that can be used according to the present invention is available from NeoGraf in Lakewood, Ohio. TM Solutions LLC obtained HITHERM TM or SPREADERSHIELD TM Another suitable type of graphite sheet is pyrolytic graphite sheet, such as Panasonic, which is available from Matsushita Electric Components Company Ltd., Ceramic Division, Japan.

[0033] In one or more examples, graphite sheet 4 is not foamed graphite.

[0034] The graphite article 10 includes a wrinkled graphite sheet 12 having a first main surface 14 and a second main surface 16 disposed opposite to it, wherein the second main surface is disposed on the side of the sheet opposite to the first main surface. The wrinkled graphite sheet 12 has a thickness Tc.

[0035] The wrinkled graphite sheet 12 formed from natural graphite has a thickness Tc of about 50 micrometers to about 2 mm. In other examples, the wrinkled flexible graphite sheet 12 has a thickness Tc of about 75 micrometers to about 1.5 mm. In yet another example, the wrinkled flexible graphite sheet has a thickness Tc of about 75 micrometers to about 500 micrometers. In yet another example, the wrinkled graphite sheet has a thickness Tc of about 75 micrometers to about 300 micrometers. The wrinkled flexible graphite sheet 12 claimed in this invention, formed from synthetic graphite, preferably has a thickness Tc of about 25 micrometers to 700 micrometers. In other examples, the flexible graphite sheet 12 has a thickness Tc of about 50 micrometers to about 600 micrometers. In yet another example, the flexible graphite sheet 12 has a thickness Tc of about 50 micrometers to about 500 micrometers.

[0036] As used herein, before being wrinkled, the flexible graphite sheet 4 is considered to be a substantially two-dimensional sheet product. The substantially two-dimensional flexible graphite sheet 4 has a thickness T. ag The thickness is less than one percent (%) of at least one of the sheet length L extending in one of the x or y directions or the sheet width W extending in the other of the x or y directions. Conversely, the graphite article 10 is considered a three-dimensional article, with a height H significantly greater than the sheet thickness Tc. In one example, H is more than 10 times larger than Tc. In another example, H is more than 100 times larger than Tc, and in yet another example, H is more than 1000 times larger than Tc.

[0037] If desired in an alternative embodiment, the wrinkled graphite 12 may also include a laminate of other materials. Examples of other materials that can be wrinkled together with the graphite sheet 4 include metal foil, plastic, paper, and thin ceramics.

[0038] The three-dimensional article 10 includes multiple large folds (typically denoted by 20). Large folds 20 may include raised large folds 20a and recessed large folds 20b. As used herein, "raised" and "recessed" are defined relative to the same surface or the same side.

[0039] In one or more examples, raised large wrinkles 20a and recessed large wrinkles 20b may alternate. The large wrinkles 20 may be spaced regularly or randomly. In one or more examples, raised large wrinkles 20a and recessed large wrinkles 20b may alternate and be spaced regularly. The height Hi of the three-dimensional article may be the distance between the highest raised wrinkle 20a and the lowest recessed wrinkle 20b in the z-direction. In other examples, the height Hi may be determined using the average distance between adjacent raised and recessed large wrinkles. In other examples, the height Hi may be determined using the median distance between adjacent raised and recessed large wrinkles. In the example where raised large wrinkles 20a and recessed large wrinkles 20b alternate at regularly spaced intervals, the three-dimensional article includes a pitch Pi, which is defined as the distance between two (2) adjacent peaks. The minimum pitch value Pi will be twice the thickness T of the starting material, the flexible graphite sheet 4. After wrinkling, the tension sheet 12 decreases the height H and increases the pitch value Pi. Compressing the wrinkle 12 without restricting it will decrease the height H and increase the pitch value Pi. Compressing the wrinkle 12 while restricting it will decrease the height H but will not increase the pitch value Pi.

[0040] like Figure 10 As shown, the micro-pleats 20 may include straight portions 20c. The length of the straight portions 20c can typically be similar to approximately the height H. The length of the straight portions 20c can vary between adjacent large pleats 20, can be uniform, or any combination thereof. Typically, the length 20c includes one (1) or fewer micro-pleats 22.

[0041] Large pleats 20a or 20b can be uniform, non-uniform, or any combination thereof.

[0042] The article 10 also includes a plurality of micro-pleats 22, which are smaller than the large pleats 20, and groups of different micro-pleats 22 are arranged between adjacent large pleats. Figure 3 As shown, each concave large fold 23 and convex large fold 21 can include micro folds 22. For example... Figure 3 As shown, the raised large wrinkles 21, the sunken large wrinkles 23, the raised micro-wrinkles 22a and the sunken micro-wrinkles 22b can usually be best shown by displaying the wrinkled pieces in the end view.

[0043] Similar to large pleats 20, micro pleats 22 can be uniform, non-uniform, or any combination thereof.

[0044] The large pleat 20 may include one or more micro pleats, preferably at least two (2) micro pleats 22, more preferably more than two (2) micro pleats 22.

[0045] Regarding the height comparison between the micro-pleat height H2 and the large pleat height H, typically, the height of the large pleat is at least 2.5 times the height H2 of the micro-pleat 22 (which is part of the large pleat 20). More preferably, the height ratio between the large pleat height H and the micro-pleat height H2 is at least approximately 3:1.

[0046] The bending radius of the micro-pleats 22 is compared with the bending radius of the large pleats 20. Typically, the bending radius of the large pleats 20 is at least 2.5 times that of the micro-pleats 22.

[0047] For all the comparisons above, micro-pleats 22 are micro-pleats included in specific large pleats 20.

[0048] Micro-folds 22 can be raised micro-folds 22a, recessed micro-folds 22b, or a combination thereof. In one or more examples, raised micro-folds 22a and recessed micro-folds 22b can alternate. Micro-folds 22 can be regularly spaced apart. In one or more examples, raised micro-folds 22a and recessed micro-folds 22b can alternate and be regularly spaced apart. The height H2 of the micro-folds can be determined as the height difference measured perpendicular to the process direction between the highest raised micro-fold 22a and the lowest recessed micro-fold 22b. In other examples, the height 3 / 4 can be determined using the average distance measured perpendicular to the process direction between adjacent raised and recessed micro-folds. In other examples, the height 3 / 4 can be determined using the median distance measured perpendicular to the process direction between adjacent raised and recessed micro-folds. In the example, raised micro-folds 22a and recessed micro-folds 22b alternate at regularly spaced intervals, and the three-dimensional article includes a pitch P2, which is defined as the distance between adjacent recessed micro-folds 22b. In other examples, the pitch P2 may be defined as the distance between adjacent raised micro-folds 22a.

[0049] The pitch dimension Pi can be designed as needed based on the material properties of the flexible graphite sheet 4 of thickness T and the wrinkling process described in more detail below. In a non-limiting example, a synthetic graphite sheet 4 with a thickness of 25 micrometers, once processed into a wrinkled graphite sheet 12, exhibits ten (10) wrinkles / mm. In another example, a natural graphite sheet 4 with a thickness of 125 micrometers, once processed into a wrinkled graphite sheet 12, exhibits four (4) wrinkles / mm. Thinner starting material 4 may produce a wrinkled graphite sheet 12 with a much higher number of wrinkles and a closer pitch Pi. The wrinkle density can be reduced by stretching the wrinkled graphite sheet 12 after its formation.

[0050] The three-dimensional article 10 has a length L that extends in the process direction M from a first end 30 to an opposite second end 32, as described in further detail below. Figure 2In the example shown, the length L and process direction M are shown extending along the y-axis. In this example, article 10 also includes a width W extending along the x-direction, perpendicular to both the length and process direction M. In some examples, the length L may be longer than the width W. In other examples, the length L may be shorter than the width W. In yet another example, the length L = W. In embodiments, large pleats 20 and micro pleats 22 may extend substantially perpendicular to the process direction M.

[0051] The three-dimensional article 10 is malleable along its length L, such that ends 30 and 32 can be pulled apart (i.e., separated from each other) without tearing or damaging the integrity of the wrinkled graphite sheet 12. In the case of a graphitized polymer, in one embodiment, the malleability of the three-dimensional article 10 allows the wrinkled graphite sheet 12 to extend along its length L to approximately 6 times its original length after wrinkling. In other examples, the malleability of the three-dimensional article 10 allows the wrinkled graphite sheet 12 to extend along its length L to approximately 5 times its original length after wrinkling. In the case of a peelable wrinkled graphite sheet 12, if the graphite sheet 12 is wrinkled with a plastic carrier, the sheet 12 can also extend along its length L to approximately 6 times its original length after wrinkling. Furthermore, the inventors have observed that the peelable wrinkled graphite sheet 12 can extend along its length L to approximately 4 times its original length after wrinkling.

[0052] In percentage terms, graphite sheet 4 does not elongate more than one percent (1%) of its length before tension is applied. For graphite sheet 12, it elongates at least ten percent (10%) of its length before tension is applied (“plastic elongation”); other typical examples of plastic elongation of graphite sheet 12 include at least twenty-five percent (25%), at least fifty percent (50%), at least one hundred percent (100%), at least one hundred and fifty percent (150%), and at least two hundred percent (200%). At the time of application, plastic elongation up to 300% has been observed.

[0053] When the load is released, the graphite sheet 12 does exhibit a certain amount of elastic recovery, but this recovery in length is not significant in terms of plastic deformation.

[0054] Exceeding the elastic limit, the wrinkled sheet 12 will not be able to fully return to its original length, thus maintaining an extension length greater than its original length after wrinkling. However, as described in further detail below, because the structure of the wrinkled sheet 12 has been permanently deformed by the wrinkling action, there is no tension that allows the wrinkled sheet 12 to return to its flatness and length before wrinkling after the tension is released.

[0055] Under compression in the penetrating plane direction, the wrinkled graphite sheet 12 stretches irreversibly by 20% in length along the process direction M, but does not stretch significantly in the width direction W.

[0056] In these examples, a greater force can be used to pull ends 30 and 32 apart, causing the length of the wrinkled sheet 12 to return (after the force is removed) to be greater than the original length, but the graphite will not be torn or its integrity compromised. In other examples, ends 30 and 32 can be pulled apart (into each other in the process direction) with a force lower than the predetermined yield force, so that the change in length L after the force is removed does not exceed a predetermined value.

[0057] When comparing graphite sheet 12 to graphite sheet 4, the thickness of graphite sheet 12 can be at least about four times (4x) that of graphite sheet 4. In a typical example, this thickness can be increased by at least about 15 times (15x). To date, the maximum achievable thickness increase is about thirty-five times (35x). It is not believed that graphite sheet 12 can be stretched sufficiently to have substantially the same thickness as graphite sheet 4. The thickness of article 10 can be measured using vernier calipers across multiple large folds 20 (at least three large folds). Typically, the length of graphite sheet 12 is at least about ten percent (10%) shorter than the length of the initial graphite sheet 4. In other embodiments, the length of graphite sheet 12 is up to ninety percent (90%) shorter than the original length of graphite sheet 4.

[0058] The typical pitch of the large folds in graphite sheet 12 is at least approximately twice the thickness of the starting material graphite sheet 4 (2T). S In specific examples, the pitch is at least 50 micrometers and can reach 2 mm.

[0059] like Figures 4a to 4d As shown, the wrinkled graphite sheet 12 can be formed by a wrinkling process to produce the aforementioned large wrinkles 20 and micro wrinkles 22. During the wrinkling process, as shown, a flexible graphite sheet 4 is disposed on the surface 38 of an optional carrier 40. In one or more examples, the carrier surface 38 has sufficiently high friction to counteract the movement of graphite along the carrier surface, thereby causing the graphite 4 to wrinkle, as described in more detail below.

[0060] In one or more other examples, graphite 4 is bonded to the carrier surface 38 to form an adhesive bond with sufficiently high adhesion to resist the movement of graphite 4 along the carrier surface 38, thereby causing the graphite to wrinkle, as described in more detail below.

[0061] like Figure 5 As shown, the carrier surface 38 can be flat. In other examples, the optional carrier can be the surface of the Yankee cylinder 40', which has, for example, Figure 6The cylindrical carrier surface 38' is shown. The carrier is typically slightly wider than the entire width of sheet 4. The cylindrical surface 38' is formed onto one or more counteremipers (not shown) and provides a platform on which wrinkling occurs.

[0062] In one or more other examples, the carrier may be a liner. Graphite 4 may be bonded to the liner such that the adhesive adhesion between the graphite and the liner resists scratching, thereby causing the graphite to wrinkle, as described in further detail below.

[0063] In a controlled process known as wrinkling, a blade (referred to as a scraper 60) is brought into contact with a carrier surface 38 to scrape graphite off the carrier surface. The scraper 60 has a width measured in the cross-process direction that is wider than the width of the graphite sheet 4. Variations of this process can include a scraper 60 that is notched (also called a gapped) scraper. This will provide a varied texture to the graphite sheet 12. It can also be referred to as a striped wrinkled graphite sheet.

[0064] Just before reaching the scraper, the graphite carbon atoms 3 of graphite sheet 4 are attached to each other via C-C bonds. One function of wrinkling is to disrupt or alter the orientation of the sheet, causing it to expand in the Z direction away from the carrier surface 38 or carrier surface 38' (as the case may be), thereby partially separating the graphite layer from the carrier surface, such as... Figure 4a As shown. The energy to break these bonds is imparted by the rotating Yankee or by moving a flat carrier, forming an adhesive bond by which graphite is bonded to the carrier, and sheet 4 is firmly held on the carrier. When most of the adhesive separates from graphite 4, some adhesive may remain on the graphite and bond adjacent wrinkles together. Moving sheet 4 impacts a fixed scraper 60, and energy transfer occurs sufficient to cause partial breakage of the C-C bonds, detaching graphite 4 from the carrier surface 38 along the interface at the scraper, thus lifting the graphite from the carrier surface to form micro-wrinkles 22. In other examples where graphite is not bonded to the carrier surface, this energy transfer occurs, causing partial breakage of the C-C bonds, sufficient to lift the graphite from the carrier surface 38 along a portion of the carrier surface to form micro-wrinkles 22. It should be understood that in other examples, scraper 60 may move against the fixed graphite sheet 4, or in other examples, both scraper 60 and graphite sheet move in a direction toward each other.

[0065] In addition to causing the sheet to expand in the Z-direction, some graphite 4 also buckles and bends. Depending on the bond strength and / or coefficient of friction of the carrier surface 38, the expanded and buckled sheet will release a short distance D from the carrier surface, such as... Figure 4a As shown. It should be understood that the stronger the adhesion strength and / or the higher the coefficient of friction on the carrier surface, then... Figure 4a The shorter the distance D shown, the more likely it is to cause small wrinkles, referred to herein as micro-wrinkles 22 of graphite wrinkles, to form before the graphite sheet, which is held against the carrier surface 38, collides with the scraper surface 62 again and the process restarts.

[0066] The fully wrinkled graphite 12, formed by the micro-folds 22 of the graphite, moves continuously away from the wrinkling bag formed along the end of the scraper 60. If desired, the wrinkled graphite 12 can be wound onto a spool. It has been found that the three-dimensional graphite article 10 does not naturally roll itself into a roll without the use of a spool. The wrinkled graphite 12 is easier to wind than the unwrinkled sheet 4 because the flexibility in the web direction has been improved through the wrinkling process described above. A reel can be used, or the generated material can be dropped into a collection box to maintain maximum plasticity.

[0067] During wrinkling, when C-bond breakage occurs, the graphite sheet 4 first expands along the Z-direction (i.e., perpendicular to the process direction (y-axis) and transverse to the process direction (x-axis), and then, as described above, expands through the wrinkling action that forms micro-wrinkles 22. The wrinkled graphite is not entirely uniformly composed of only micro-wrinkles 22. Instead, the wrinkled three-dimensional graphite article includes larger large wrinkles 20 interspersed with numerous smaller micro-wrinkles 22, as described above.

[0068] In other examples, the scraper 60 can move back and forth in the transverse process direction to create a serrated pattern in the graphite of the three-dimensional article 10.

[0069] like Figure 5 and Figure 6 The geometry of the pleated bag (shown approximately as 300) is illustrated in more detail. The pleated bag 300 is defined by a bag corner 302, which is the angle formed between the blade face 62 and the graphite 4 at the contact line where the blade edge 62 contacts the carrier surface 38. In examples where the carrier surface 38' is not flat (e.g., a cylindrical Yankee surface), the bag corner 302 is formed between the blade face 62 and the tangent at the location where the blade edge 62 contacts the carrier surface 38'.

[0070] The bag angle 302 is determined by the blade bevel angle 306, which is the angle formed at the contact point 64 between the blade face 62 and the carrier surface (or its tangent). The blade bevel angle 306 is the angle formed between the blade face 62 and the blade base 66. The blade base 66 extends from the blade holder 68 to form a sliding wear angle 308. The sliding wear angle 308 is determined by the blade holder angle 310 minus the blade deflection angle 312. The blade holder angle 310 is formed between the blade base 66 and the carrier surface 38 (or its tangent) at the point where the blade base 66 exits the blade holder 68 and the carrier surface 38. The sliding wear angle 308 reduces the amount of blade deflection at the contact line 64. The blade deflection is determined in part by the blade material and the length of the blade extension. The blade extension is the length of the blade base 66 extending from the blade holder 68 to the blade edge 62. Examples of blade materials may include metals, ceramics, or carbides. The blade may be coated with similar materials.

[0071] In certain embodiments, the sliding wear angle 308 can range from approximately 15 degrees to 40 degrees. The final sliding wear angle 308 is limited in two ways. If the sliding wear angle 308 is too small (less than approximately 15 degrees), its ability to detach from the sheet is impaired, and the sheet may bypass or clog the blade, leading to web breakage. If the angle is too large (over 40°), it will exert too much friction on the carrier surface 38, and wear or damage caused by vibration on the carrier surface becomes problematic. Therefore, although other angles are conceivable, the blade seat angle is typically 17° to 19°. To obtain what is considered a relatively more open bag angle, the blade can be tilted at an angle 306 of up to 60°. The more open the pleated bag (bag angle greater than 90°), the easier it is for the blade to create micro-pleats with a smaller pitch P2. The amplitude or height H of large pleats generally decreases as the bag angle becomes more open. Pleated bags with a relatively smaller opening amplitude formed by bag angles less than 90° will increase the height H of large pleats during pleating.

[0072] The blade extension amount determines the fine-tuning of the bag angle, because increasing the extension amount allows the blade deflection to open the bag. However, a larger extension amount can also cause the blade to vibrate more and may also lead to looping. While extension amounts of 15 mm to 35 mm can be used, 20 mm to 25 mm is preferred, and in other examples, 10 mm to 50 mm can be used. The angles and measurements above are exemplary and should not be considered limiting for the purpose of practicing the embodiments disclosed herein.

[0073] The adhesion of graphite to the carrier can cause debonding, and this debonding must be overcome in order to form micro-wrinkles and large wrinkles.

[0074] Examples of adhesives may include acrylic PSAs. There is no particular limitation on the type of PSA contained in the first PSA layer. The PSA may be a PSA containing one or more of a variety of polymers (PSA polymers) selected as constituents of a PSA, such as acrylic polymers, polyesters, urethane polymers, polyethers, rubber-based polymers, silicone-based polymers, polyamides, and fluoropolymers. From the perspective of, for example, PSA performance and cost, PSAs containing acrylic polymers or rubber polymers as base polymers can be advantageously used. Preferably, PSAs containing acrylic polymers as base polymers (acrylic PSAs) are preferred. The following configuration will now be explained primarily: a PSA layer composed of acrylic PSAs (i.e., an acrylic PSA layer), but the first PSA layer in the features disclosed herein is not intended to be limited to acrylic PSA layers.

[0075] In other examples, the adhesive may include a silicone layer applied to the PET carrier.

[0076] A relatively weak adhesive will break more easily, resulting in coarse wrinkles with high wrinkling amplitude (e.g., a relatively long measured H) and low frequencies (e.g., a relatively long measured pitch P). A relatively strong adhesive will be less prone to adhesive bond breakage, resulting in fine wrinkles, low amplitude (e.g., a relatively short measured H), and high frequencies (e.g., a relatively short measured pitch P).

[0077] The flexibility of the three-dimensional article 10 makes it ideal for use as gaskets or seals that can withstand high temperatures. Furthermore, compared to typical, essentially two-dimensional flexible graphite sheets, its flexibility allows the article to be stamped, drawn, or pressed into a wider variety of shapes.

[0078] The flexibility of the three-dimensional article 10 makes it ideal for use as a thermal interface that can withstand high temperatures.

[0079] Furthermore, compared to typical, essentially two-dimensional flexible graphite sheets, the flexibility allows for the stamping or pressing of articles to form a wider variety of shapes.

[0080] Graphite product 12 can be used as a thermal interface. For example... Figure 7 As shown, the primary function of the thermal interface is to create sufficient effective thermal communication between the first surface 14 of the flexible graphite sheet 12 and the outer surface of the electronic component to remove heat from the heat source to the maximum extent under acceptable contact pressure. The graphite article 10 also provides a secondary function as a thermal interface, providing an increased effective surface area of ​​the electronic component to facilitate heat dissipation from the electronic component; therefore, the graphite article 10 is used as a thermal spreader or heat spreader.

[0081] Applications of the article may include its use as a thermal interface in environments such as consumer electronics, white goods, drive systems for automobiles, commercial or motorcycles, telecommunications, thermoelectric devices and industrial equipment.

[0082] The article describes an article that possesses any of the following advantages: low contact resistance, excellent thickness thermal conductivity, high in-plane thermal conductivity, relatively high bonding line thickness, and greater adaptability to varying thicknesses and roughness compared to planar graphite sheets. One advantage is its suitability as a large-area thermal interface material. Other advantages of this material compared to conventional thermal interface materials include lower thermal resistance, increased compressibility, and higher in-plane thermal conductivity.

[0083] Compared to unwrinkled graphite sheet 4, graphite article 10 exhibits increased plasticity. This increased plasticity, compared to graphite sheet 4, enhances the article 10's ability to be bent, molded, and extruded into three-dimensional shapes. The article's plasticity allows it to be drawn around an object or formed into enclosures. Figure 15a , Figure 15b and Figure 16 The example shown is as follows.

[0084] The graphite product 10 has been formed as an EMI, which simultaneously surrounds EMI sources on five sides without any leakage. The EMI also removes heat from the same package and dissipates heat outward along a sixth side.

[0085] Graphitized polymer graphite sheet 12 exhibits improved shielding effectiveness compared to control graphite sheet 4. Graphite sheet 12 was tested according to ASTM test method D4935, “Shielding Effectiveness.” The wrinkled graphite sheet 12 showed an improvement in shielding effectiveness of at least 10 dB in the frequency range of 2 GHz to 6 GHz. Moreover, the shielding effectiveness increased with increasing frequency in this range. Striped graphite sheet 12 (wrinkled by a notched scraper 60) showed a slope of 1.3 dB / MHz across the entire frequency range, approximately 6 times higher than control graphite sheet 4, while graphite sheet 12 (wrinkled by a straight scraper 60) showed a slope of 3.8 dB / MHz across the entire frequency range, approximately 20 times higher. Therefore, the wrinkled graphite 12 disclosed herein exhibits improved shielding effectiveness in the frequency range of 2 GHz to 6 GHz, wherein the slope of the best-fit line has the following slope: at least 0.6 dB / MHz, preferably at least 0.8 MHz, and more preferably at least 1.0 dB / MHz.

[0086] Furthermore, the drawn graphite sheet 12 can be clamped without tearing.

[0087] The graphite article 12 has excellent impermeability, making the wrinkled graphite 12 suitable for sealing fluids and other types of substances. Regarding the water vapor transmission rate (“WVTR”) (also referred to as moisture transmission rate (“MVTR”)), preferably, the embodiment may have a value not exceeding about 20 gm / m. 2 -WVTR at 60% RH at 20°C for one day. Other preferred WVTRs include those not exceeding about 15 gm / m. 2 - WVTR at 60% RH at 20°C for one day; not exceeding approximately 10 gm / m 2 - WVTR at 60% RH at 20°C for one day, and not exceeding approximately 5 gm / m 2 - WVTR at 60% RH at 20°C for one day. Another example showed less than 1.0 gm / m 2 - Impermeability at 60% RH and 20°C. Another example has shown 0.05 g / m². 2 - Impermeability at 60% RH and 20°C. The test method for determining this WVTR is ASTM F-1249.

[0088] Regarding oxygen permeability (“OTR”), the preferred embodiment has an OTR of no more than 150 cc / m³. 2 -day-atm@23% controlled RH. Other preferred OTRs include not exceeding 100cc / m 2 - day-atm@23% controlled RH, not exceeding 75cc / m 2 - day-atm@23% controlled RH, not exceeding 50cc / m 2 - day-atm@23% controlled RH, and not exceeding 25cc / m 2 - day-atm@23% controlled RH and not exceeding 10cc / m 2 -day-atm@23% controlled RH. The test method for determining OTR is ASTM F-1927.

[0089] Refer again Figure 7 The three-dimensional article can be used to form a laminate consisting of an article disposed between a first material 100 and a second material 102. In one example, the first material and the second material are the same. In other examples, the first material and the second material are different. In the case of wrinkling of both materials, interlocking wrinkles formed by micro-wrinkles and large wrinkles can form a Vickers-like connection between the upper and lower materials. The upper and lower materials can be further isolated by the wrinkled graphite interface. In this way, materials that might otherwise react with each other or must remain separated can now be interconnected through this thin layer composed of article 10.

[0090] Another application of graphite sheet 12 is to form the core of a laminate having three or more layers of graphite sheet 12 as its core. For the outer surface of such a laminate, graphite sheet 4 can be used on one or two surfaces. Optionally, different materials can be used for the outer surface of the laminate, such as, but not limited to, metal foil. The resulting laminate is similar to a corrugated sheet. Such a laminate can have high flexural strength in both the x and y directions. Such a laminate can have structural applications.

[0091] Starting with graphitized polymers, wrinkled graphite sheets 12 can be used as the core of multilayer laminates, thereby increasing the strength, thermal conductivity, or dielectric properties of the laminates. Single-layer wrinkled sheets 12 add strength to laminates in a manner similar to corrugated paper. Increased strength has been observed even when the geometry of the wrinkled sheets 12 is non-uniform.

[0092] The graphite article 10 described herein has a high specific surface area, which is the area of ​​surface 14 or surface 16 relative to the area of ​​the footprint occupied by article 10. This specific surface area can also be expressed as the surface area of ​​the article divided by the area occupied by article 10 (also known as the footprint) when the article is stretched. This specific surface area is approximately 3:1 to 10:1, and in other examples 2:1 to 20:1.

[0093] like Figure 8As shown, the increased specific surface area of ​​the article and the narrow channels formed by micro- and macro-folds provide binding areas for liquids, such as those used to improve wettability and / or reduce contact resistance. This is useful for applications where the article is used as a thermal interface. Greases and oils (e.g., Fulblin oil, synthetic oils, or other oils) can be added to surface 14 or surface 16 to improve the thermal conductivity of article 10. In other examples, the oils used in this invention include a variety of substances, including, for example, mineral oils, vegetable oils, animal oils, fragrance oils, edible oils, synthetic oils (such as silicone oils), and combinations thereof. The mineral oils used in this invention include, for example, alkane mineral oils, naphthenic mineral oils, intermediate-based mineral oils, etc. The mineral oils used in this invention are generally petroleum-based and include aliphatic, aromatic, and mixed base oils. Specific examples of mineral oils used in this invention include neutral oils, medium-gravity neutral oils, heavy-neutral oils, bright oils, and common lubricants (e.g., engine oils), as well as pharmaceutical oils (e.g., refined paraffin oils). The vegetable oils used in this invention can be primarily derived from seeds or nuts, and include rapeseed oil, oil, low-erucic acid rapeseed oil, soybean oil, corn oil, cottonseed oil, linseed oil, olive oil, tung oil, peanut oil, meadow foam oil, sunflower oil, soybean oil, safflower oil, jojoba oil, palm oil, castor oil, coconut oil, etc. Vegetable-based oils can be obtained, for example, from genetically modified plants, or modified through washing, refining, esterification, hydrolysis, etc. Animal oils used in this invention include fish oil, cod liver oil, oleic acid, etc. Essential oils used in this invention include liquids derived from flowers, stems, and leaves (and generally the whole plant). These oils can include oils commonly used in cosmetics. Additionally, conventional edible oils can be used in this invention. These oils are derived from fruits or seeds and plants. The most common are corn, coconut, soybean, olive, cottonseed, and safflower. These oils have varying degrees of saturation. Finally, synthetic oils can be used in this invention. Synthetic oils are ester-type oils, polyolefin oligomers, or alkylated benzenes.

[0094] Another embodiment of the invention is a process for preparing a thermal interface material. The process includes providing a graphite article having micro-folds and macro-folds. One of an oil, grease, or wax (collectively referred to as "oil") is provided, and the oil is brought into contact with the graphite sheet until the micro-folds and macro-folds contain approximately 2% to approximately 75% (by weight) of oil.

[0095] Fluorinated synthetic oil is added to the wrinkled sheet 12 by contacting the sheet with the oil until the oil is absorbed into the graphite, to obtain a wrinkled graphite sheet containing about 2% by weight to about 75% by weight of oil. In other examples, the graphite sheet contains about 2% by weight to about 50% by weight of oil; in yet another example, the graphite sheet contains about 2% by weight to about 20% by weight of oil; and in still another example, the graphite sheet contains about 10% by weight to about 50% by weight of oil.

[0096] like Figure 9 As shown, the wrinkled sheet 12 can be calendered between spaced rolls R to provide a calendered article 10' with a controlled maximum thickness, which is more suitable for the application without significantly reducing the compressibility of the article. Calendering reduces... Figure 2 The height Hi is shown as varying between the raised and recessed large folds. Depending on the roll pitch, this new material 10' can maintain high compressibility and compliance, or it can have a higher density. This step is optional.

[0097] Dielectric materials such as polyimide or PET can also be used to combine the compliance of the elastic graphite wrinkles with materials possessing high voltage breakdown characteristics. Alternatively, a highly flexible layer of silicone can be used to fill voids or applied to the surface to reduce the electrical conductivity of the composite while allowing heat flux to pass through the entire graphite composite. The continuous nature of the graphite sheets ensures relatively uniform spacing of the bands connecting the upper and lower surfaces without the need for additional matrix materials.

[0098] Wrinkling is different from embossing. Embossing compresses the material perpendicular to its plane, while the compression caused by wrinkling does not occur perpendicular to the plane of the material to be wrinkled.

[0099] Example

[0100] Now refer to Figures 11 to 14 The ability of the wrinkled graphite sheet 12 to withstand tensile stress was tested.

[0101] For comparison purposes, the tensile force T is... F ( Figure 11 The tensile force T is applied to two samples (as shown on 114 and 116) of graphite sheet 4 (as shown on 112) used as a control sample and wrinkled graphite sheet 12, respectively. A tensile force T is applied along the wrinkling direction (also called the process direction). F . Figure 11 This shows the application of tensile force T F Previous samples 112, 114 and 116. Figure 12 This shows the application of tensile force T F The following are samples 112, 114 and 116.

[0102] The first sample 114 of the wrinkled graphite sheet includes large wrinkles 20 and micro wrinkles 22, which are generally perpendicular to the applied tensile force T. F Extension. For example... Figure 13 and Figure 14 As shown, the first sample 114 bears approximately half the load of the graphite sheet 112. The first sample 114 has the advantage that it elongates to approximately three times its original length and is at least approximately 50 times longer than the control sample 112. Figure 12 As shown.

[0103] The second sample 116 of the wrinkled graphite sheet includes large wrinkles 20 and micro wrinkles 22, which are generally parallel to the applied tensile force T. F Extension. For example... Figure 13 and Figure 14 As shown, the second sample 116 was able to withstand more than twice the load applied to the graphite sheet 112. The second sample 116 elongated by approximately the same amount, roughly the same order of magnitude, as the control sample 112. The width of the second sample 116 also increased by at least 20% during the application of the tensile force, as... Figure 12 As shown.

[0104] The MTS / Instron tensile testing equipment was used for the above tests. The tensile testing procedure was performed according to the equipment's instruction manual. It is similar to ASTM D638. All samples 112, 114, and 116 were formed from synthetic graphite. Samples 114 and 116 were formed from a synthetic graphite material with a roughness approximately four times that of sample 112.

[0105] When comparing the thermal resistance of wrinkled and unwrinkled graphite sheets under a pressure of at least 250 kPa, for the wrinkled, peeled graphite sheet 12, the sheet 12 with a thickness increased by approximately 4 to 7.5 times exhibited similar resistance to its unwrinkled counterpart (e.g., graphite sheet 4). For the graphitized polymer graphite sheet 4, the wrinkled sample wrinkled with a straight doctor blade exhibited similar resistance when its thickness was approximately 2.5 to 4 times that of its unwrinkled graphite sheet. For the graphite sheet 12 wrinkled with a notched doctor blade 60, it exhibited two times or more of the thickness for similar thermal resistance. From this test, it should be noted that the striped wrinkled sheet 12 has a thickness approximately half that of the straight wrinkled sheet 12. The tests were conducted according to ASTM D5470.

[0106] In addition, the thermal resistance of the wrinkled graphite sheet 12 was compared with that of some existing spacers. The existing spacers tested had a thickness of at least about 500 micrometers to about 1 mm. The above-described ASTM D5470 test was used. The sampled existing spacers included 1 mm (uncompressed) Fujipoly 100XR-m and 500 micrometers (uncompressed) Fujipoly 50XR-m. At a pressure of 700 kPa, the wrinkled graphite sheet consistently outperformed existing spacers by exhibiting lower thermal resistance. For the natural graphite wrinkled graphite sheet 12 with an uncompressed thickness of about 1 mm, the natural wrinkled sheet 12 exhibited a thermal resistance reduction of 5% to 50% compared to existing spacers. For the graphitized polymer wrinkled graphite sheet, it exhibited a thermal resistance reduction of 0.5 to 2.5 times compared to the control sample. This same trend continued for the graphitized polymer graphite sheet 12 with a thickness of about 500 micrometers. The wrinkled pads exhibited a reduction in thermal resistance that was approximately 2.5 to 4 times greater than that of the control gap pads.

[0107] The thermal impedance results of the samples under a contact pressure of 700 kPa include values ​​less than 0.5 °C*cm. 2 / W, less than 0.35℃*cm 2 / W and less than 0.20℃*cm 2 / W.

[0108] When comparing the in-plane diffusivity of graphitized polymer wrinkled sheets 12, the difference between the in-plane diffusivity in the x and y directions of sheet 12 is at least 15%. Another, non-limiting example of the difference in in-plane diffusivity of graphitized polymer wrinkled sheets 12 is at least 20%, at least 30%, at least 40%, and at least 50%. For exfoliated natural graphite wrinkled sheets 12, the difference between the in-plane diffusivity in the x and y directions is at least five percent (5%). Another, non-limiting example of the difference in in-plane diffusivity of exfoliated natural graphite wrinkled sheets 12 is at least 15%, at least 20%, at least 30%, at least 40%, and at least 50%. This diffusivity was tested on a Bethel TA33 thermal analyzer.

[0109] Now for reference Figure 17 One particular embodiment of the wrinkled graphite of interest is a wrinkled graphite sheet (generally shown as 200) having one or more wrinkled portions 202 and one or more unwrinkled portions 204. Another embodiment is a graphite sheet having only one (1) wrinkled portion located between two (2) unwrinkled portions. Yet another embodiment is a graphite sheet having only one (1) unwrinkled portion located between two (2) wrinkled portions.

[0110] Examples include:

[0111] 1. A graphite article comprising: a wrinkled graphite sheet having a first main surface and a second main surface disposed opposite to the first main surface, the wrinkled graphite sheet having a plurality of large wrinkles and a plurality of micro wrinkles, wherein each of the plurality of micro wrinkles adjacent to each of the plurality of large wrinkles has a height less than the height of the adjacent large wrinkles.

[0112] 2. The graphite article according to Example 1, wherein the large folds include raised folds and recessed micro-folds.

[0113] 3. The graphite article according to Example 1 or Example 2, wherein the large folds include alternating raised folds and recessed micro-folds.

[0114] 4. The graphite article according to any of the foregoing examples, wherein the large folds include regularly spaced alternating raised folds and recessed microfolds, the pitch being defined as the distance between at least one of adjacent raised folds and adjacent recessed microfolds.

[0115] 5. The graphite article according to any one of Examples 1 to 4, wherein raised wrinkles and recessed micro-wrinkles can be seen when the graphite article is viewed in cross-section.

[0116] 6. The graphite article according to any of the foregoing examples, wherein the graphite article further includes oil contained in the microfolds.

[0117] 7. The graphite article according to any of the foregoing examples, wherein the graphite article exhibits elastic and / or plastic properties.

[0118] 8. The graphite article according to any of the foregoing examples, wherein the elongation of the article includes at least 10% of the original length of the article.

[0119] 9. The graphite article according to any of the foregoing examples, wherein the difference in in-plane diffusion rate in the xy direction includes at least 15%.

[0120] 10. The graphite article according to any of the foregoing examples, wherein the graphite article includes a thermal interface.

[0121] 11. The graphite article according to any of the foregoing examples, wherein the graphite article exhibits a temperature of less than 0.5°C*cm under a contact pressure of approximately 700 kPa. 2 / W thermal resistance.

[0122] 12. The graphite article according to any of the foregoing examples has a thickness of at least 0.5 mm.

[0123] 13. A method of manufacturing a three-dimensional article, comprising: providing a graphite sheet disposed on a carrier, wherein the carrier comprises PET or an adhesive-coated surface; oriented a blade at an angle to the graphite sheet; and using the blade to scrape the graphite away from the carrier, thereby forming repeating microfolds on the graphite sheet.

[0124] 14. The method according to Example 13, wherein the microfolds include raised microfolds and recessed microfolds.

[0125] 15. The method according to Example 13 or Example 14, wherein the microfolds include alternating raised microfolds and recessed microfolds spaced regularly or irregularly, having a pitch defined as the distance between at least one of adjacent raised microfolds and adjacent recessed microfolds.

[0126] 16. The method according to any one of Examples 13 to 15, wherein a blade is used to scrape graphite away from the carrier, thereby forming repeating large folds on the graphite sheet.

[0127] 17. The method according to any one of Examples 13 to 16, wherein the large folds include alternating raised large folds and recessed large folds.

[0128] 18. An article comprising a wrinkled flexible graphite sheet.

[0129] 19. The article of manufacture according to Example 18, wherein the flexible graphite sheet comprises a sheet of compressed particles of exfoliated graphite sheet and / or a sheet of graphitized polymer.

[0130] 20. The article of manufacture according to Example 18 or Example 19, wherein the elongation of the wrinkled flexible graphite sheet is at least 10% of its original length.

[0131] 21. The article according to any one of Examples 18 to 20, wherein the difference in in-plane diffusion rate of the article in the xy direction is at least 15%.

[0132] 22. The article according to any one of Examples 18 to 21 above, wherein the article has a temperature of less than 0.5°C*cm under a contact pressure of about 700 kPa. 2 / W thermal resistance.

[0133] 23. The article of manufacture according to Example 18, wherein the wrinkled flexible graphite sheet comprises an integral article.

[0134] 24. The article according to Example 18, wherein the oxygen permeability of the article does not exceed 150 cc / m 2 -day-atm@23% controlled relative humidity.

[0135] 25. The article according to Example 18, wherein the moisture permeability of the article does not exceed 20 gm / m 2 - Day @ 60% relative humidity @ 20℃

[0136] 26. The article of example 18, wherein the article has a temperature of less than 0.5°C*cm under a contact pressure of about 700 kPa. 2 / W thermal resistance.

[0137] 27. The article according to Example 18 further includes a thermoplastic layer forming an outer or inner layer of the article.

[0138] 28. A wrinkled flexible graphite product itself.

[0139] The above description is intended to enable those skilled in the art to practice the invention. It is not intended to describe in detail all possible modifications and variations, which will become apparent to those skilled in the art upon reading the specification. However, all such modifications and variations should be included within the scope of the invention as defined by the appended claims.

[0140] Therefore, although new and useful applications of graphite articles and specific embodiments of the invention on how to manufacture such graphite articles have been described, such references are not intended to be construed as limiting the scope of this disclosure unless set forth in the appended claims. Various embodiments discussed above may be practiced in any combination thereof.

[0141] This application also relates to the following:

[0142] Item 1. A graphite product, comprising:

[0143] A wrinkled graphite sheet having a first main surface and a second main surface disposed opposite to the first main surface, the wrinkled graphite sheet having a plurality of large wrinkles, each large wrinkle having a plurality of associated micro wrinkles, wherein each micro wrinkle is smaller than the associated large wrinkle.

[0144] Item 2. The graphite article according to Item 1, wherein the large folds include raised large folds and recessed large folds.

[0145] Item 3. The graphite article according to Item 1 or Item 2, wherein the large folds include alternating raised large folds and recessed large folds.

[0146] Item 4. The graphite article according to any one of items 1 to 3, wherein the thickness (Tc) of the wrinkled graphite sheet is 50 micrometers to 2 mm.

[0147] Item 5. The graphite article according to any one of items 1 to 4, wherein the height (H) of the graphite article is more than 100 times greater than the thickness (Tc) of the wrinkled graphite sheet.

[0148] Item 6. The graphite article according to any one of items 1 to 5, wherein the large folds include at least two micro folds.

[0149] Item 7. The graphite article according to any one of items 1 to 6, wherein the height ratio between at least one of the large folds and at least one of the micro folds is at least 3:1.

[0150] Item 8. A graphite article according to any one of items 1 to 7, wherein the graphite article is arranged in a three-dimensional shape having a measurement value of at least 0.5 mm in the z-direction.

[0151] Item 9. The graphite article according to any one of items 1 to 8, wherein the graphite article further includes oil contained in the large folds.

[0152] Item 10. A graphite article according to any one of items 1 to 9, wherein the graphite article exhibits elastic and / or plastic properties.

[0153] Item 11. A graphite article according to any one of items 1 to 10, wherein the elongation of the article includes at least 10% of the original length of the article.

[0154] Item 12. The graphite article according to any one of items 1 to 11, wherein the difference in in-plane diffusion rate in the xy direction includes at least 15%.

[0155] Item 13. A graphite article according to any one of items 1 to 12, wherein the graphite article includes a thermal interface.

[0156] Item 14. A graphite article according to any one of items 1 to 13, wherein the graphite article exhibits a temperature of less than 0.5°C*cm under a contact pressure of about 700 kPa. 2 / W thermal resistance.

[0157] Item 15. A wrinkled graphite sheet having a first main surface and a second main surface disposed opposite to the first main surface, the wrinkled graphite sheet having a plurality of large wrinkles, each large wrinkle having a plurality of associated micro wrinkles, wherein each micro wrinkle has a height less than that of the associated large wrinkle.

[0158] Item 16. The sheet according to Item 15, wherein the thickness (Tc) of the wrinkled graphite sheet is from 50 micrometers to 2 mm.

[0159] Item 17. The sheet according to Item 15 or Item 16, wherein the height (H) of the wrinkled graphite sheet is more than 100 times greater than the thickness (Tc) of the wrinkled graphite sheet.

[0160] Item 18. The sheet according to any one of items 15 to 17, wherein each large fold comprises at least two micro folds.

[0161] Item 19. The sheet according to any one of items 15 to 18, wherein the height ratio between at least one of the large folds and at least one of the micro folds is at least 3:1.

[0162] Item 20. A method for manufacturing graphite articles, comprising:

[0163] A flexible graphite sheet is provided disposed on a carrier, wherein the carrier surface has sufficiently high friction to resist movement of the graphite sheet along the carrier surface, or wherein the graphite sheet is bonded to the carrier surface.

[0164] Orienting the blade to form an angle with the graphite sheet; and

[0165] The blade is used to scrape graphite away from the carrier, thereby forming repeated large and micro wrinkles on the graphite sheet.

[0166] Item 21. The method according to Item 20, wherein the blade has a base extending from the blade holder and forming a sliding wear angle of 15 to 40 degrees.

[0167] Item 22, the method according to Item 20 or Item 21, wherein the blade has a blade bevel angle of 0 to 60 degrees.

[0168] Item 23. The method according to any one of items 20 to 22, wherein the blade has a blade extension of 15 mm to 35 mm.

[0169] Item 24. The method according to any one of items 20 to 23, wherein the graphite sheet comprises a sheet of compressed particles of exfoliated graphite sheet and / or a sheet of graphitized polymer.

[0170] Item 25. The method according to any one of items 20 to 24, the method further comprising the steps of stamping, drawing and / or pressing the wrinkled graphite sheet.

[0171] Item 26. The method according to any one of items 20 to 25, said method being used to manufacture graphite articles according to any one of items 1 to 14.

[0172] Item 27. An article comprising a graphite article according to any one of items 1 to 14 or a wrinkled graphite sheet according to any one of items 15 to 19.

[0173] Item 28. An article comprising a wrinkled flexible graphite sheet.

[0174] Item 29. The article of claim 27 or 28, wherein the elongation of the wrinkled flexible graphite sheet is at least 10% of its original length.

[0175] Item 30, the article according to any one of items 27 to 29, wherein the difference in in-plane diffusion rate of the article in the xy direction is at least 15%.

[0176] Item 31. The article according to any one of items 27 to 30, wherein the graphite article is an integral article.

[0177] Item 32. The article according to any one of items 27 to 31, wherein the article is a laminate composed of a graphite article disposed between a first material and a second material.

[0178] Item 33. The article according to any one of items 27 to 32, wherein the article exhibits a temperature of less than 0.5°C*cm at a contact pressure of about 700 kPa. 2 / W thermal resistance.

[0179] Item 34. The article according to any one of items 27 to 33, wherein the article further comprises a thermoplastic layer forming an outer or inner layer of the article.

[0180] Item 35. Use of a graphite article according to any one of Items 1 to 14 or a wrinkled graphite sheet according to any one of Items 15 to 19 as a thermal interface.

[0181] Item 36. Use of a graphite article according to any one of items 1 to 14 or a wrinkled graphite sheet according to any one of items 15 to 19 for forming an enclosure.

[0182] Item 37, a wrinkled flexible graphite product itself.

[0183] Item 38. The article according to Item 37, when a tensile force is applied, the article is capable of having an elongation of greater than 10% and up to 300%, wherein the force is in a direction perpendicular to the large folds of the wrinkle.

Claims

1. A graphite article comprising: A wrinkled graphite sheet having a first main surface and a second main surface disposed opposite to the first main surface, the wrinkled graphite sheet having a plurality of large wrinkles, each large wrinkle having a plurality of associated micro wrinkles, wherein each micro wrinkle is smaller than the associated large wrinkle, wherein compression caused by wrinkling does not occur perpendicular to the plane of the material to be wrinkled.

2. The graphite article according to claim 1, wherein, The large folds include raised large folds and sunken large folds.

3. The graphite article according to claim 2, wherein, The large folds include alternating raised and recessed large folds.

4. The graphite article according to any one of claims 1 to 3, wherein, The thickness (Tc) of the wrinkled graphite sheet is 50 micrometers to 2 mm.

5. The graphite article according to any one of claims 1 to 3, wherein, The height (H) of the graphite article is more than 100 times greater than the thickness (Tc) of the wrinkled graphite sheet.

6. The graphite article according to any one of claims 1 to 3, wherein, A large fold consists of at least two micro folds.

7. The graphite article according to any one of claims 1 to 3, wherein, The height ratio between at least one of the large folds and at least one of the micro folds is at least 3:

1.

8. The graphite article according to any one of claims 1 to 3, wherein the graphite article is arranged in a three-dimensional shape having a measurement value of at least 0.5 mm in the z-direction.

9. The graphite article according to any one of claims 1 to 3, wherein, The graphite article also includes oil contained in the large folds.

10. The graphite article according to any one of claims 1 to 3, wherein, The graphite products exhibit elastic and / or plastic properties.

11. The graphite article according to any one of claims 1 to 3, wherein, The elongation of the article includes at least 10% of the original length of the article.

12. The graphite article according to any one of claims 1 to 3, wherein, The difference in in-plane diffusion rate in the xy direction includes at least 15%.

13. The graphite article according to any one of claims 1 to 3, wherein, The graphite product includes a thermal interface.

14. The graphite article according to any one of claims 1 to 3, wherein, The graphite product exhibits a temperature drop of less than 0.5℃*cm under a contact pressure of approximately 700 kPa. 2 / W thermal resistance.

15. The graphite article according to any one of claims 1 to 3, wherein, when a tensile force is applied, the article is capable of having an elongation of up to 300%, wherein, The force is in the direction perpendicular to the large folds that cause the wrinkling.

16. An article comprising a graphite article according to any one of claims 1 to 15.

17. The article of claim 16, wherein, The graphite product is a single, integral product.

18. The article of claim 16, wherein the article is a laminate composed of a graphite article disposed between a first material and a second material.

19. The article of claim 16, further comprising a thermoplastic layer forming an outer or inner layer of the article.

20. Use of the graphite article according to any one of claims 1 to 15 as a thermal interface.

21. Use of the graphite article according to any one of claims 1 to 15 for forming an enclosure.

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