CN118119501A - Polymer film and method for producing same - Google Patents

Abstract

The present invention provides a polymer film having orthogonal lengths and widths. The polymer film includes a base and a plurality of fins extending away from the base and substantially coextensive with the base along the length. The fins are aligned over the width. At least a majority of each fin includes a first portion extending from the base to a tip of the fin opposite the base; and a second portion extending from the tip of the fin toward or to the base. The second portion is attached to the first portion near the tip and is separated from the first portion near the base along at least a portion of the length. The first portion and the second portion have respective different first and second compositions.

Description

Polymer film and method for producing same

Disclosure of Invention

In some aspects, the present description provides a polymer film having orthogonal lengths and widths. The polymer film includes a base and a plurality of fins extending away from the base and substantially coextensive with the base along the length. The fins are aligned over the width. At least a majority of each fin includes a first portion extending from the base to a tip of the fin opposite the base; and a second portion extending from the tip of the fin toward or to the base. The second portion is attached to the first portion near the tip and is separated from the first portion near the base along at least a portion of the length. The first portion and the second portion may have respective different first and second compositions.

In some aspects, the present description provides a polymer film having orthogonal lengths and widths. The polymer film includes: a substrate; and a plurality of fins extending along the length and aligned across the width. The plurality of fins are substantially coextensive with the base along the length. The substrate has an average thickness T in a direction orthogonal to the length and width. The fins extend from the base to an average height H along a height direction and have an average width W at tips of the fins along a direction orthogonal to the height direction. In some embodiments, H/W is greater than or equal to 40 and H/T is greater than or equal to 40.

In some aspects, the present description provides a polymer film comprising: a first substrate; and a plurality of fins extending along a length of the polymer film and substantially coextensive with the first substrate along the length. The fin extends in a height direction from an attachment portion of the fin to the first base to an average height H. The attachment portions are spaced apart at an average spacing S along a width direction of the polymer film, the width direction being substantially orthogonal to the length direction and orthogonal to a thickness direction of the polymer film. H may be greater than S. The height direction can be sufficiently inclined with respect to the thickness direction so that adjacent fins contact each other.

In some aspects, the present description provides a thermal management system that includes a polymer film including a base and a plurality of fins extending away from the base.

In some aspects, the present description provides a method for manufacturing at least a first polymer film. The first polymer film extends along a length direction of the first polymer film and has a width along a width direction of the first polymer film orthogonal to the length direction. The method includes extruding a first resin and a second resin through respective first and second pluralities of slots in a slotted plate to form molten stacks of alternating respective first and second extension elements. Each of the first plurality of slots and the second plurality of slots has a flow direction that is angled relative to a first plane defined by the length direction and the width direction. The first extension element and the second extension element extend along the length direction and are inclined in a second plane orthogonal to the length direction. The method includes extruding a first skin layer and a second skin layer onto respective opposite first and second sides of the molten stack to form a molten film; compressing the molten film in a thickness direction orthogonal to the length direction and the width direction; and cooling the molten film to form the first polymer film.

These and other aspects will become apparent from the detailed description that follows. In no event, however, should this brief summary be construed as limiting the subject matter which may be claimed.

Drawings

Fig. 1 is a schematic cross-sectional view of a polymer film according to some embodiments.

Fig. 2 is a schematic top view of a polymer film according to some embodiments.

Fig. 3 is a schematic plan view of a die for extruding a polymer film, according to some embodiments.

Fig. 4A-4C are schematic cross-sectional views of slotted plates according to some embodiments.

Fig. 5A is a schematic cross-sectional view of a molten film according to some embodiments.

Fig. 5B is a schematic cross-sectional view of a film according to some embodiments, which may correspond to the molten film of fig. 5A after being compressed.

Fig. 5C is a schematic cross-sectional view of a film according to some embodiments, which may correspond to the film of fig. 5B after the skin layer has been removed.

Fig. 6 is a schematic diagram of a method of making a film according to some embodiments.

Fig. 7A is a top perspective image of an exemplary polymer film.

Fig. 7B is a perspective image of an exemplary polymer film.

Fig. 7C is a perspective image of a portion of the polymer film of fig. 7B.

Fig. 8 is a schematic end view of a slotted plate, according to some embodiments.

Fig. 9 is a schematic diagram of a polymer flow path through a slotted plate, according to some embodiments.

Fig. 10 is a schematic end view of a skin plate according to some embodiments.

FIG. 11 is a schematic cross-sectional view of a thermal management system according to some embodiments.

Detailed Description

In the following description, reference is made to the accompanying drawings, which form a part hereof and in which are shown by way of illustration various embodiments. The figures are not necessarily drawn to scale. It is to be understood that other embodiments are contemplated and made without departing from the scope or spirit of the present description. The following detailed description is, therefore, not to be taken in a limiting sense.

According to some embodiments of the present description, a polymeric film is provided that provides a plurality of fins extending along the length of the film. The film may be an extruded and/or integrally formed film. The film is integrally formed if the various portions of the film are manufactured together rather than separately and then subsequently joined. It has been found that according to some embodiments, fins having a high aspect ratio (e.g., a height of at least 40 times the width) may be provided in an integrally formed film by coextruding a web comprising a plurality of obliquely extending elements disposed between two skin layers and then removing one of the skin layers and rotating the extending elements. The fins may include substantially coextensive first and second portions having different compositions. According to some embodiments, the membrane has been found useful for transporting material and/or energy through the membrane, for example, along the length of the membrane. For example, fins may be used to direct fluid along the surface of the membrane, where the fluid may be heated or cooled so that the membrane may be used as a heat exchanger, for example. Such films may be used, for example, for battery cooling. Battery systems cooled using polymeric heat exchanger films are described, for example, in international application publication No. WO 2021/044345 (Bartling et al). According to some embodiments, the film may alternatively or additionally be used as a packaging film.

Fig. 1 is a schematic cross-sectional view of a polymer film 100 according to some embodiments. Fig. 2 is a schematic top view of a polymer film 100 according to some embodiments. The polymer film 100 has orthogonal length and width. That is, the length and width are along the respective orthogonal length direction (z direction) and width direction (x direction). The polymer film 100 includes a substrate 120 and a plurality of fins 110 substantially coextensive with the substrate 120 along a length (along a length direction (z-direction) of the polymer film 100). The substrate (which may also be referred to as a substrate portion) may be a portion of the film having a substantially constant thickness. The base may be integrally formed with the fins. The fins 110 extend away from the base 120 and along the length and are aligned along the width (along the width direction (x-direction) of the polymer film). Fins 110 may extend away from base 120 along height direction 147 to an average height H. Each fin 110 may have a minimum width, which is the minimum distance between opposing major surfaces of the extension element along a direction substantially orthogonal to the major surfaces (e.g., within 30, 20, 10, or 5 degrees of orthogonal to the opposing major surfaces). The minimum thickness may occur in an upper portion of the extension element (e.g., at the tip 113). For example, in some embodiments, the extension element 110 includes a first portion 111 and a second portion 112 that are attached to each other near the tip 113 of the extension element, and the minimum width may be substantially equal to the total combined thickness of the first portion 111 and the second portion 112. The average of the minimum widths is W, which may be referred to as the average width at the tips of the fins. In some embodiments, the H/W is at least 40 or within another range described elsewhere herein. In some embodiments, the extension elements are spaced apart in the width direction and are arranged at an average spacing S that may be greater than 10W, and/or greater than 10 times the average thickness T of the substrate, and/or less than the average height H, or within another range described elsewhere herein. The spacing S may be described as the center-to-center distance between fins. The fins may be regularly arranged along the width at a pitch equal to the average spacing S.

A layer or element may be described as being substantially coextensive with each other if at least about 60 area percent of each layer or element (e.g., in a plan view of the major surface facing the layer or element) is coextensive with at least about 60 area percent of each other layer or element. In some embodiments, at least about 70 area%, or at least about 80 area%, or at least about 90 area% of each layer or element is coextensive with at least about 70 area%, or at least about 80 area%, or at least about 90 area% of each other layer or element, for layers or elements described as being substantially coextensive. A layer or element may be described as being substantially coextensive with each other in length and/or width if at least about 60% of the length and/or width of each layer or element is coextensive with at least about 60% of the length and/or width of each other layer or element. In some embodiments, for layers or elements described as being substantially coextensive with each other in length and/or width, at least about 80% or at least about 90% of each layer or element is coextensive in length and/or width with at least about 80% or at least about 90% of the length and/or width of each other layer or element.

The extension elements 110 may be referred to as fins. In some embodiments, at least a majority (greater than 50%) of each of the extension elements (or fins) comprises: a first portion 111 extending from the base 120 to a tip 113 of the extension element (or fin) opposite the base 120; and a second portion 112 extending from the tip 113 of the extension element (or fin) toward the base 120 or to the base. The second portion 112 may be attached to the first portion 111 near the tip and may be separated from the first portion 111 near the base 120 along at least a portion of the length L of the extension element (or fin) along that length. In some embodiments, the first portion 111 and the second portion 112 have respective different first and second compositions, as further described elsewhere herein. The first portion 111 and the second portion 112 of the fin or extension element may be individually referred to as extension elements and may be referred to as first extension element and second extension element.

In some embodiments, the polymer film 100 has orthogonal length and width, and includes a base 120 and a plurality of fins 110 extending along the length (along the length direction (z-direction) of the polymer film 100) and aligned in width (in the width direction (x-direction) of the polymer film). In some embodiments, the plurality of fins are substantially coextensive with the base 120 along the length. In some embodiments, each of the fins, or at least a majority of the fins, or at least 60%, 70%, 80%, or 90% of the fins, are substantially coextensive with the base 120 along the length. The substrate 120 has an average thickness T in a thickness direction (y-direction) orthogonal to the length and width. In some embodiments, the fins 110 extend from the base 120 to an average height H along the height direction 147 and have an average width W at the tips of the fins that is the average of the smallest widths of the fins 110 along a direction orthogonal to the height direction 147. The height direction 147 may be within 30 degrees, 20 degrees, or 10 degrees of parallel to the thickness direction (y-direction) for each of at least a majority of the fins 110. In some embodiments, W is in the range of 0.05mm to 2 mm. In some embodiments, H/W is greater than or equal to 40, 80, 100, 120, 150, or 200. In some such embodiments, or in other embodiments, H/T is greater than or equal to 40, 80, 100, 120, 150, or 200. For example, in some embodiments, H/W is 80 or greater and H/T is 80 or greater. H/W and/or H/T may be up to, for example, 10,000, 5000, 1000, 500 or 250.

In some embodiments, the fins 110 are spaced apart in width and arranged at an average spacing S (or pitch), which may be, for example, greater than 10T, or greater than 20T, or greater than 30T. The spacing S may be, for example, up to 1000 times T or 10,000 times T. In some embodiments, the fins 110 are regularly arranged along the width direction. In some such embodiments, or in other embodiments, the fins are arranged at an average spacing S in the range of 0.1cm to 3 cm. In some embodiments, H > S. For example, H may be at least 1.5, 2, 2.5, or 3 times S. For example, H may be up to 100 times, 50 times, 20 times, or 10 times that of S. In some embodiments, the spacing S is, for example, greater than 10W, or greater than 20W, or greater than 30W. The spacing S may be, for example, up to 1000 times or 10,000 times W.

In some embodiments, each fin has a maximum height H1 along the height direction 147 and a minimum width W1 along a direction orthogonal to the height direction. The plurality of fins 110 may have an average H1/W1 of at least 40, or H1/W1 may be within any of the ranges of H/W described elsewhere herein.

In some embodiments, the polymer film 100 has a length L along the length direction (z-direction) that is greater than 1m, 10m, 30m, or 100 m.

In some embodiments, the first portion 111 and the second portion 112 have respective different first and second compositions. In some embodiments, the substrate 120 comprises a first composition. In some embodiments, the first composition is a first polyester composition and the substrate comprises a second polyester composition. In some embodiments, the first polyester composition and the second polyester composition are different. In some embodiments, the first polyester composition and the second polyester composition are the same polyester composition. The polyester composition may comprise greater than 50 weight percent polyester.

In some embodiments, the first portion 111 (but not the second portion 112) is directly bonded to the substrate 120. For example, the first portion 111 and the substrate 120 may be formed of the same composition or may be formed of similar polymers that adhere well to one another (e.g., polymers comprising at least one same monomer unit), while the second portion 112 is formed of a different composition that has weaker adhesion to the substrate 120, such that when the fins (or extension elements) are formed and rotated, as further described elsewhere herein, the second portion 112 may separate from the substrate 120. In some embodiments, the first composition is a polyester composition. In some such embodiments, or in other embodiments, the second composition comprises at least one of an olefin composition and a styrene composition. In some such embodiments, or in other embodiments, the second composition is an olefin composition. The olefin composition may comprise greater than 50 wt% olefins. Similarly, the styrenic composition may comprise greater than 50 wt% styrene-containing polymer. A composition comprising a significant amount (e.g., greater than 10 or 20 wt%) of an olefin-and-styrene-containing compound may be referred to as one or both of an olefin composition and a styrene composition, or may be referred to as an olefin/styrene composition.

In some embodiments, the composition is selected such that the first portion 111 and the second portion 112, and/or the second portion 112 and the substrate 120, have surface tension that differ from each other by at least 10%. For example, the surface tension may differ from each other by at least 15%, or at least 20%. For example, the surface tension may differ by up to about 130%, about 100%, or about 80%. The surface tension of the polymers used in the film can generally be found in a standard table of surface tension, as understood by one of ordinary skill in the art. For example, surface tension can be measured using contact angle measurements as described in ASTM D7490-13 "standard test method (Standard Test Method for Measurement of the Surface Tension of Solid Coatings,Substrates and Pigments using Contact Angle Measurements)" for measuring surface tension of solid coatings, substrates and pigments using contact angle measurements.

In some embodiments, the plurality of fins 110 (or extension elements) and the base 120 are integrally formed. In some embodiments, the plurality of fins 110 (or extension elements) and the base 120 are co-extruded.

In some embodiments, the composition used in the fins (or extension elements) and the substrate comprises a thermoplastic polymer that can be selected to be easily extrudable and processable. For example, the thermoplastic polymer may be selected to have a molecular weight and/or intrinsic viscosity and/or Melt Flow Index (MFI) within a suitable range of extrudability. In some embodiments, the thermoplastic polymer has a weight average molecular weight Mw greater than 20,000 daltons or greater than 35,000 daltons or greater than 50,000 daltons. For example, the weight average molecular weight Mw may be at most 1,000,000 daltons, or at most 600,000 daltons, or at most 400,000 daltons, or at most 200,000 daltons, or at most 150,000 daltons. In some such embodiments, or in other embodiments, the thermoplastic polymer has an intrinsic viscosity in the range of 0.3dl/g to 1.2dl/g or 0.4dl/g to 1.0dl/g, as measured in a solvent blend comprising 60 weight percent o-chlorobenzene and 40 weight percent phenol. In some such embodiments, or in other embodiments, the thermoplastic polymer has a melt flow index greater than 5g/10min, or greater than 10g/10min, or greater than 20g/10 min. For example, the melt flow index may be at most 300g/10min, or at most 200g/10min, or at most 100g/10min. For example, the weight average molecular weight Mw can be determined using gel permeation chromatography. For example, the intrinsic viscosity may be measured using a capillary viscosimeter. For example, the melt flow index (which may alternatively be referred to as melt flow rate) may be determined using an extrusion plastometer according to ASTM D1238-20.

Suitable materials for the various parts of the films of the present description include, for example, polyethylene naphthalate (PEN), coPEN (copolymerized ethylene naphthalate terephthalate copolymer), polyethylene terephthalate (PET), polyhexamethylene naphthalate copolymer (PHEN), glycol modified PET (PETG), glycol modified PEN (PENG), syndiotactic polystyrene (sPS), THV (terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride), polymethyl methacrylate (PMMA), copma (copolymer of methyl methacrylate and ethyl acrylate), styrene block copolymers (block copolymers comprising styrene blocks) such as linear triblock copolymers based on styrene and ethylene/butylene (e.g., styrene-ethylene/butylene-styrene (SEBS) copolymers), acrylic block copolymers (block copolymers comprising acrylate or methacrylate blocks) such as linear triblock copolymers based on methyl methacrylate and n-butyl acrylate, anhydride modified ethylene vinyl acetate polymers, ketovinyl ester terpolymers, polyolefin thermoplastic elastomers, polypropylene (PP), polypropylene (35) such as thermoplastic copolymers of acrylic acid, or thermoplastic copolymers such as thermoplastic polyurethane (coPP) thereof.

Random polystyrene (aPS) may optionally be blended with sPS (e.g., about 5 wt% to about 30 wt% of aPS) to adjust the refractive index of the resulting layer and/or reduce the haze of the layer (e.g., by reducing the crystallinity of the layer). Suitable THV polymers are described, for example, in U.S. patent application publication No. 2019/0369314 (Hebrink et al), and include those commercially available under the tradename DYNEON THV from 3M Company (3M Company) (St. Paul, MN) of Minnesota. In some embodiments, THV may comprise from about 35 mol% to about 75 mol% tetrafluoroethylene, from about 5 mol% to about 20 mol% hexafluoropropylene, and from about 15 mol% to about 55 mol% vinylidene fluoride. Suitable styrene block copolymers include KRATON G1645 and KRATON G1657 available from KRATON Polymers (Houston, TX) of Ketone Polymers. Suitable acrylic block copolymers include those commercially available from cola corporation under the trade name KURARITY from Kuraray co., ltd.) (Tokyo, JP)). PETG can be described as PET in which some of the glycol units of the polymer are replaced by different monomer units, typically those derived from cyclohexanedimethanol. For example, PETG may be prepared by substituting cyclohexane dimethanol for a portion of the ethylene glycol used in the transesterification reaction to produce polyester. Suitable PETG copolyesters include GN071 from the Company of iysman chemicals (EASTMAN CHEMICAL Company) (Kingsport, TN) in tennessee. PEN and coPEN can be prepared as described in U.S. Pat. No. 10,001,587 (Liu). The low melting point PEN is a coPEN comprising about 90 mole% naphthalene dicarboxylate groups based on total carboxylate groups, also referred to as coPEN 90/10. Another useful coPEN is coPEN 70/30, which comprises about 70 mole% naphthalene dicarboxylate groups and about 30 mole% terephthalate dicarboxylate groups, based on total carboxylate groups. More generally, coPEN Z/100-Z may be used, where coPEN Z/100-Z comprises Z mole% naphthalene dicarboxylate groups (typically greater than 50 mole% and no more than about 90 mole%) and 100-Z mole% terephthalate dicarboxylate groups based on total carboxylate groups. Glycol modified polyethylene naphthalate (PENG) may be described as PEN in which some of the glycol units of the polymer are replaced with different monomer units, and may be prepared by, for example, replacing a portion of the ethylene glycol used in the transesterification reaction to produce the polyester with cyclohexanedimethanol. PHEN can be prepared, for example, as described for PEN in U.S. Pat. No. 10,001,587 (Liu), except that a portion (e.g., about 40 mole%) of the ethylene glycol used in the transesterification reaction is replaced with hexylene glycol. Suitable PET is available, for example, from southern Asia plastics America (NAN YA PLASTICS Corporation, america) (Lake City, SC), nanlona. Suitable sPS are available, for example, from light-emitting products (Idemitsu Kosan co., ltd.) (tokyo, japan). Suitable PMMA is available, for example, from acarma, inc (archema inc., philiadelphia, PA.) of Philadelphia, pennsylvania. Suitable anhydride modified ethylene vinyl acetate polymers include, for example, those available from Dow Chemical company (Dow Chemical) (Midland, mich.) under the trade name BYNEL. Suitable ketovinyl ester terpolymers include, for example, those polymers available from the Dow chemical company (Midland, mich.) under the trade name BYNEL. Suitable polyolefin thermoplastic elastomers include those commercially available under the trade name ADMER from Mitsui Chemicals (Tokyo, japan). Suitable coPP include PP8650 (random copolymer of propylene and ethylene) commercially available from dadel petrochemical company (Total Petrochemicals, inc.) (Houston, TX).

Fig. 3 is a schematic plan view of a die 444 for extruding a polymer film according to some embodiments. The mold 444 includes a slot plate 431, a skin piece 432, and a compression section 433. The compression section 433 compresses the extruded web in the thickness direction (y-direction) and may optionally compress the web in the width direction (x-direction). Die 444 may include other elements not shown but commonly used in extrusion dies, as will be appreciated by those of ordinary skill in the art.

Fig. 4A-4C are schematic cross-sectional views of slotted plates 431 according to some embodiments. Fig. 4A is a cross-section adjacent the input side of slot plate 431, fig. 4C is a cross-section adjacent the output side of slot plate 431, and fig. 4B is a cross-section between the cross-sections of fig. 4A and 4C. The slots are schematically shown as rectangular slots in fig. 4A-4C, but may alternatively have other shapes (e.g., to facilitate flow to certain areas). For example, the slot may have rounded edges or may have a generally trapezoidal shape. The slotted plate 431 may include other features, such as holes on opposite sides of the plurality of slots 410, 420, to provide channels to facilitate flow and fill in material in corner regions on sides of the plurality of slots 410, 420. There may also be additional slots at one or both sides of the plurality of slots 410 and additional slots at one or both sides of the plurality of slots 420 that are not staggered with respect to each other. For example, additional apertures and/or non-staggered slots may help stabilize the extruded web. As further described in the examples, fig. 8 is a schematic end view of a slotted plate showing holes 772, 772 'and non-staggered slots 771, 771' according to some embodiments. Fig. 9 is a schematic illustration of polymer flow produced by the slotted plate of fig. 8, and fig. 10 schematically illustrates the slotted plate of fig. 8 adjacent to a skin plate. The slotted plate 431 and other mold elements may be made using conventional machining techniques such as wire Electrical Discharge Machining (EDM).

Fig. 5A is a schematic cross-sectional view of a molten film 250 according to some embodiments. The molten film 250 may correspond to a molten film formed by the slot plate 431 and the skin piece 432 before being compressed in the compression section 433. The molten film 250 includes a molten stack 240 of alternating first 245 and second 246 extending elements disposed between a first skin layer 325 and a second skin layer 320. The first and second extension elements 245, 246 have different first and second compositions 545, 546, and the first and second skin layers 325, 320 have third and fourth compositions 525, 520, which may be the same or different. For example, the third composition 525 and the fourth composition 520 may be the same composition as one of the first composition 545 and the second composition 546.

Fig. 5B is a schematic cross-sectional view of a polymer film 260 according to some embodiments. The polymer film 260 may correspond to the molten film 250 after being compressed and cooled in the compression section 433. The polymer film 260 may be described as including a plurality of alternating first and second extension elements 111, 112 disposed between the first and second skin layers 125, 120. The first and second extension elements 111, 112 may be the first and second extension elements 245, 246 after the molten film 250 is compressed and cooled to form the polymer film 260. Similarly, the first skin layer 125 and the second skin layer 120 may be the first skin layer 325 and the second skin layer 320 after the molten film 250 is compressed and cooled to form the first polymer film 260.

Fig. 5C is a schematic cross-sectional view of a polymer film 262 according to some embodiments. The polymer film 262 may correspond to the polymer film 260 after the skin layer 125 has been removed.

In some embodiments, the polymer films 260, 262 include a first substrate 120 and a plurality of fins 110 extending along a length direction (z-direction) of the polymer film and substantially coextensive with the first substrate 120 along the length direction. The fins 110 extend along a height direction 147 from their attachment portions 117 to the first base 120 to an average height H. The attachment portions 117 are spaced apart and aligned at an average spacing S along a width direction (x-direction) of the polymer film, which is substantially orthogonal to the length direction and to a thickness direction (y-direction) of the polymer film. H is greater than S, and the height direction 147 is sufficiently inclined with respect to the thickness direction so that adjacent fins contact each other. In some embodiments, the polymer film 260 further includes a second substrate 125, wherein the plurality of fins 110 are disposed between the first substrate 120 and the second substrate 125.

In some embodiments, each of at least a majority of the fins (or extension elements) includes a first portion 111 and a second portion 112 that are attached to each other and substantially coextensive with the fins. The first portion 111 and the second portion 112 may have respective different first and second compositions, as further described elsewhere herein. In some embodiments, the first substrate 120 comprises a first composition. In some such embodiments, or in other embodiments, the polymeric film 260 includes a second substrate 125, wherein the second substrate 125 comprises a second composition.

Fig. 6 is a schematic diagram of a method of making a polymer film according to some embodiments. One or both of resins P1 and P2, and optionally P3 and P4, are extruded through extrusion die 344 (e.g., corresponding to die 444) to form an extruded web 350, which is cooled by casting the extruded web onto casting wheel 346 (also referred to as a chill roll) to form cast web 351, which may correspond to first polymer film 260. As will be appreciated by those of ordinary skill in the art, optional roller 347 may be included, and additional rollers (not shown) may optionally be included. The first portion 111 and the second portion 112 may be formed of a first resin P1 and a second resin P2. The first substrate 120 and the second substrate 125 (which may be referred to as skin layers) may be formed of P1 and P2 or any one of P1 to P4. In some embodiments, the first resin P1 comprises a polyester and the second resin P2 comprises an olefin. In some such embodiments, or in other embodiments, the first substrate 120 and the second substrate 125 are formed from resins P3 and P4, which may include polyesters and may be the same or different from the first resin P1. In some embodiments, the first extension element 111 and the second extension element 112 in the first polymer film 260 have surface tensions that differ from each other by at least 10% or within the ranges described elsewhere herein.

In some embodiments, a method for manufacturing at least a first polymer film is provided. The first polymer film extends along a length direction of the first polymer film and has a width along a width direction of the first polymer film orthogonal to the length direction. The method includes extruding first and second resins (e.g., P1 and P2) through respective first and second pluralities of slots (410, 420) in slotted plates 431 to form molten stacks 240 of alternating respective first and second extension elements 245, 246. Each of the first and second pluralities of slots has a flow direction (e.g., 158, 159 schematically shown in fig. 3) that is angled relative to a first plane (plane 455 or xz-plane) defined by the length and width directions. The first and second extension members 245 and 246 extend along the length direction and are inclined in a second plane (yx plane) orthogonal to the length direction. The method comprises the following steps: extruding (e.g., via skin pieces 432) the first skin layer (325) and the second skin layer (320) onto respective opposite first side 242 and second side 241 of the melt stack to form a melt film 250; compressing the molten film in a thickness direction (y direction) orthogonal to the length direction and the width direction (e.g., in compression section 433); and cooling the molten film to form the first polymer film 260.

In some embodiments, the flow direction 158, 159 of each of the first and second pluralities of slots forms an angle θ1, θ2 with the first plane in the range of 5 to 85 degrees, or 10 to 90 degrees, 20 to 80 degrees, 30 to 60 degrees, or 40 to 50 degrees. Each of the angles θ1, θ2 may be, for example, about 45 degrees.

In some embodiments, the method further includes removing the first skin layer (125) from the first polymer film 260, but not removing the second skin layer (120), to form a second polymer film 262 having a plurality of angled fins 110 formed by the first extending elements 245 (or 111) and the second extending elements 246 (or 112). In some embodiments, the method further includes rotating the tilted fins such that the fins extend generally away from the second skin layer (e.g., rotating the fins of fig. 5C such that they extend generally away from the skin or substrate 20, as schematically shown in fig. 1). In some embodiments, each of at least a majority of the angled fins includes adjacent first and second portions 111, 112 that extend generally parallel to one another and are bonded to one another along at least a portion of the angled fins. In some embodiments, rotating the angled fins separates the first portion 111 and the second portion 112 from each other along at least a portion of the fins adjacent to the second skin layer 120. It has been found that the first portion 111 and the second portion 112 may remain bonded to each other near the tip of the portion, but that adjacent fins 110 may separate from each other as the fins rotate.

Fig. 7A is a top perspective image of an exemplary polymer film that may correspond to polymer film 260. The fins of the exemplary polymer film include a dye in one of the first and second portions of the fin. The dye-bearing edges of this portion are visible as dark fringes in fig. 7A. Fig. 7B is a perspective image of an exemplary polymer film in which the top skin (e.g., the top skin of the polymer film of fig. 7A) has been removed and the fins in a portion of the film have been rotated so that they extend generally away from the bottom skin or substrate of the film. Fig. 7C is a perspective image of a portion of the polymer film of fig. 7B, enlarged at a scale relative to fig. 7B.

In some embodiments, the first polymer film 260 or the second polymer film 262 includes a first substrate 120 and a plurality of fins 110 extending along a length direction (z-direction) of the polymer film. The fins 110 extend along a height direction 147 from their attachment portions 117 to the first base 120 to an average height H. The attachment portions 117 may be spaced apart at an average spacing S along a width direction (x-direction) of the polymer film that is substantially orthogonal to the length direction (z-direction) and orthogonal to a thickness direction (y-direction) of the polymer films 260, 262. H may be greater than S. H. S and/or H/S may be within any of the ranges described elsewhere herein. The height direction 147 of the polymer films 260, 262 may be sufficiently inclined relative to the thickness direction such that adjacent fins contact each other.

Fig. 11 is a schematic cross-sectional view of a thermal management system 1000 according to some embodiments. Thermal management system 1000 includes a pump 973 for circulating fluid 900 between fins of film 800, which may correspond to, for example, polymer film 100. Film 800 may be disposed on an object or device 830 that is desired to be cooled or heated. An adhesive may be disposed between the film 800 and the object or device 830 to bond the film to the object or device. Alternatively, film 800 may include an adhesive for bonding to object or device 830. The adhesive may be a thermally conductive adhesive (e.g., the adhesive may contain a thermally conductive filler). The fluid 900 may be a cooling fluid (e.g., maintained at a temperature below a predetermined operating temperature of the device) or a heating fluid (e.g., maintained at a temperature above a predetermined temperature of the object). In some embodiments, a film 800 is provided that includes a polymer film 100 (see, e.g., fig. 1) and a liquid 900 that at least partially fills the spaces between adjacent fins 110 of the polymer film 100. The films 100, 800 may optionally include additional layers disposed on top of the fins 110 to define channels between the base 120 of the polymer film 100 and the additional layers. Additional layers may be bonded to the tips of fins 110, for example, via an adhesive layer.

Examples

Films with extension elements (fins or louvers) were prepared and handled. Physical properties were evaluated and are shown in the examples below.

These examples are for illustrative purposes only and are not intended to limit the scope of the appended claims. All parts, percentages, ratios, etc. in the examples, as well as in the remainder of the specification, are by weight unless otherwise specified. The following abbreviations are used herein: mil = thousandth inch, mm = millimeter, cm = centimeter, c = degrees celsius, sec = seconds,% = percent, in = inch, IV = intrinsic viscosity, MFI = melt flow index.

TABLE 1 materials

Examples E1 to E5

The hardware that forms the film with the substrate and the plurality of fins includes a dual manifold mold, where each manifold feeds a series of slots cut in a slot plate. The slot was 0.687 inches (17.45 mm) long, 0.033 inches (0.84 mm) wide, and 0.022 inches (0.56 mm) narrow (trapezoidal shape). The slots are spaced 0.066 inches (1.68 mm) apart centrally at the outlet side. These slots are angled and staggered in the yz plane from the manifold to the centerline of the mold to form an ABAB … … pattern as shown in fig. 3. As shown in fig. 8, the slot is also inclined 45 degrees in the xy plane (see, e.g., fig. 4A-4C). At each edge of the slot plate are a number of slots 771, 771' which are not staggered because the inlet ends of the opposing slots would extend beyond the feed manifold. To facilitate flow in the manifold and "fill" the corners of the louvre stack, holes 772, 772' angled in the yz plane are drilled at each end of the slot plates. The output film has a solid band of resin a on one edge and a solid band of resin B on the other edge.

Fig. 9 shows the resulting polymer flow path through the slotted plate. AB staggered patterns and polymer streams 871 and 872 corresponding to slots 771 and holes 772, respectively, are shown.

After the louvered stack is formed, as shown in FIG. 10, the resin flows into the skin plates, which apply skin layers on the top and bottom of the stack through respective channels 781 and 782. The skin layer may be the same resin as one or both of the louvers, or one or two different resins. Of particular interest is the case where the top skin layer matches louvered resin a and the bottom skin layer matches louvered resin B.

The louvered stack plus skin flowed to the die outlet from 0.50 inch (1.3 cm) high compression to about 0.050 inch (0.13 cm) in the y-direction. The x-direction width remains constant from the slot plate to the die exit.

The examples were prepared:

With the above configuration, a series of films were produced using the following equipment setup: the cooled roll (wheel) side skin layer was fed through a Leistritz 18mm TSE (twin screw extruder) which was run in vacuum and utilized a gradual temperature profile with 8/0 temperature of 260 to 271 ℃. The associated gear pump and neck were also heated to 260 to 271 ℃. The air side skin layers were fed by a 27mm Leistritz (neolumbo Leistritz extrusion technique (Leistritz Extrusion Technologies, nurnberg, germany)) TSE which was run in vacuum and also utilized a gradual temperature profile with 8/0 temperature at 260 to 271 ℃. The associated gear pump and neck were also heated to 260 to 271 ℃. Each set of discrete inclined layers was fed by a 27mm Leistritz TSE, which was run in vacuum and utilized with a gradual temperature profile having a temperature of 8/0 at 260 to 271 ℃. The associated gear pump and neck were also heated to 260 to 271 ℃. The mold described in detail above was positioned just above a 27 ℃ rotating chill roll with associated electrostatic pins for rapid web quenching. The above substrate was produced on the equipment with a cast web thickness in the range of 12 mils to 30 mils in thickness.

Table 2 shows the material composition details of the produced cast web (film).

Table 2.

The cast web film was then manipulated as follows:

1) One of the skins is removed from the web. In most cases, one of the skins is easily separated due to the low adhesion between one of the louvers and that skin.

2) For various samples, a stylus, probe or fingertip was used to manipulate the shutter (fins), advancing against the "negative" of the shutter as it was extruded. The louvers are substantially parallel to the base layer of the substrate after extrusion, but form discontinuous-1/4 inch (0.64 cm) wide channels with one end of the channels attached to the base layer and the other end free floating like a fish scale. When the moire is detected, the louver can be easily rotated.

3) When the louvers are rotated beyond a certain non-recoverable point, they tend to adhere upward generally perpendicular to the cast web film. The height of these louvers is about 3/16 inch to 5/16 inch (0.35 cm to 0.79 cm).

Typical dimensions of the film are as follows. The base film is typically about 24 mils thick prior to handling the fins. The peeled top substrate is about 6 to 7 mils thick, the bottom substrate is about 6 to 7 mils thick, and the louvers are each 5.5 to 6 mils thick. The louvers are arranged in about 6 to 7 per inch (about 2.4 to 2.8 per cm).

Fig. 7A to 7C are images of embodiment E5. Fig. 7A shows the film prior to manipulation, then fig. 7B shows the same film that has been pulled apart and then manipulated as described above to produce a base film with >1/4 inch (0.64 cm) fins protruding from the film surface at 90 degrees. The middle portion of the film in FIG. 7B has been manipulated to produce a substantially vertical fin of-1/4 inch (0.64 cm) height. Fig. 7C is a close-up view of the middle portion. In fig. 7B, the discontinuous and flat positioning of the non-manipulated fins directly on either side of the vertical channel can be seen.

Terms such as "about" will be understood by those of ordinary skill in the art in the context of use and description herein. If the use of "about" in the context of the use and description of this specification is not clear to one of ordinary skill in the art as to the amount of information that is applied to express feature size, quantity, and physical characteristics, then "about" will be understood to mean within 10% of the specified value. The amount given to be about the specified value may be precisely the specified value. For example, if it is not clear to a person of ordinary skill in the art in the context of use and description in this specification, an amount having a value of about 1 means that the amount has a value between 0.9 and 1.1, and the value may be 1.

All references, patents and patent applications cited above are hereby incorporated by reference in their entirety in a consistent manner. In the event of an inconsistency or contradiction between the incorporated references and the present application, the information in the foregoing description shall prevail.

Unless otherwise indicated, the descriptions of elements in the drawings should be understood as equally applicable to corresponding elements in other drawings. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This disclosure is intended to cover any adaptations or variations or combinations of the specific embodiments discussed herein. Accordingly, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims (15)

1. A polymer film having orthogonal lengths and widths, the polymer film comprising a base and a plurality of fins extending away from the base and substantially coextensive with the base along the length, the fins being aligned over the width, at least a majority of each of the fins comprising:

A first portion extending from the base to a tip of the fin opposite the base; and

A second portion extending from the tip of the fin toward or to the base, the second portion being attached to the first portion near the tip and separated from the first portion near the base along at least a portion of the length, the first and second portions having respective different first and second compositions.

2. The polymer film of claim 1, wherein the substrate comprises the first composition.

3. The polymer film of claim 1 or 2, wherein the first composition is a first polyester composition and the substrate comprises a second polyester composition.

4. The polymer film of any one of claims 1-3, wherein the second composition is an olefin composition.

5. The polymer film of any one of claims 1 to 4, wherein the fins extend from the base to an average height H along a height direction and have an average width W at tips of the fins along a direction orthogonal to the height direction, wherein H/W is ≡40.

6. A polymer film having orthogonal lengths and widths, the polymer film comprising:

a substrate; and

A plurality of fins extending along the length and aligned across the width, the plurality of fins being substantially coextensive with the base along the length, the base having an average thickness T in a direction orthogonal to the length and width, the fins extending from the base to an average height H in a height direction, and having an average width W at the tips of the fins in a direction orthogonal to the height direction, wherein H/W is greater than or equal to 40 and H/T is greater than or equal to 40.

7. The polymer film of claim 6, wherein the fins are arranged along the width at an average spacing S greater than 20T.

8. The polymer film of claim 7, wherein H > S.

9. The polymer film of any one of claims 6 to 8, wherein at least a majority of each of the fins comprises a first portion and a second portion bonded to each other and extending from a tip of the fin opposite the substrate toward or to the substrate, the first and second portions having respective different first and second compositions.

10. The polymer film of claim 9, wherein for each of at least a majority of the fins, the second portion is attached to the first portion near the tip and separated from the first portion near the base along at least a portion of the length of the fin.

11. A polymer film comprising:

a first substrate; and

A plurality of fins extending along a length direction of the polymer film and substantially coextensive with the first base along the length direction, the fins extending along a height direction from attachment portions of the fins to the first base to an average height H, the attachment portions being spaced apart at an average spacing S along a width direction of the polymer film, the width direction being substantially orthogonal to the length direction and thickness direction of the polymer film, H being greater than S, the height direction being sufficiently oblique relative to the thickness direction such that adjacent fins contact each other.

12. The polymer film of claim 11, further comprising a second substrate, the plurality of fins being disposed between the first substrate and the second substrate.

13. A method for manufacturing at least a first polymer film, the first polymer extending along a length direction of the first polymer film and having a width in a width direction orthogonal to the length direction along the first polymer film, the method comprising:

Extruding first and second resins through respective first and second pluralities of slots in a slotted plate to form a molten stack of alternating respective first and second extension elements, each of the first and second pluralities of slots having a flow direction that is angled relative to a first plane defined by the length direction and the width direction, the first and second extension elements extending along the length direction and being inclined in a second plane orthogonal to the length direction;

extruding first and second skin layers onto respective opposite first and second sides of the melt stack to form a melt film;

Compressing the molten film in a thickness direction orthogonal to the length direction and the width direction; and

Cooling the molten film to form the first polymer film.

14. The method of claim 13, further comprising removing the first skin layer from the first polymer film, but not removing the second skin layer, to form a second polymer film having a plurality of angled fins formed by the first extension element and the second extension element.

15. The method of claim 14, further comprising rotating the angled fins such that the fins extend generally away from the second skin layer.