IMPROVED PLASTIC/METAL LAMINATES

Abstract: Plastic/metal laminates (for example, plastic-coated cable shielding or armoring tapes) having improved friction, adhesion, and heat-sealability properties which comprise at least one metallic substrate having directly adhered to at least one surface thereof a thermoplastic adhesive layer containing an amount of embosser sufficient to substantially lower the coefficient of friction of the laminate and sufficient to emboss the surface of the plastic/metal laminate.

Description: IMPROVED PLASTIC/METAL LAMINATES This invention generally relates to improved plastic/metal laminates with improved adhesion to various substrates, improved heat-sealabi ty. and a lower Coefficient of Fπction ("COF") The improved plastic/metal laminates of the present invention also exhibit reduced breakage rates and substantially reduced flaking and dusting during the manufacture of cables and other formed plastic/metal composite articles utilizing the plastic/metal laminates of the present invention Additionally, the present invention relates to plastic/metal composite articles or laminates that can reasonably be expected to be installed and/or otherwise used as electrical communications cables. metal/plastic/metal laminates for potential use as electrical appliance housings, in heating ducts, in various automotive applications, etc In the manufactuπng of cables and other formed plastic/metal composite articles from various laminated articles involving one or more metallic layers or substrates having one or more layers or coatings of a thermoplastic polymer mateπal adhered thereto, an oftentimes controlling factor or consideration governing their suitability for various end-use applications is the degree by which the plastic/metal laminate can be shaped and formed and the degree of adhesion as between the various polymeric and metallic layers in such laminated or composite articles. One particularly useful application for plastic/metal laminates of the present invention is in electrical cables. In the an of designing and constructing electrical cables, especially telecommunication cables such as telephone cables, it is known to assemble insulated conductors or glass fibers in a core and surround it by shield and jacketing components. The shield component is often referred to as shield, screen, shielding tape, or armoring tape." In general, the process by which plastic/metal laminates (for example, shielding or armoring tape) are made into cables generally consists of an unwind stand which delivers the plastic/metal laminate, typically having a width from 0.5 inch ( 1.27 e i to 8.0 inches (20.32 cm), to a comigator. ( if smooth finished cable is desired, the comigator is bypassed ) From the corrugator. the plastic/metal laminate is forwarded to a pretormer or a forming tray which starts the shaping of the laminate into a tube. The preformed laminate is then forwarded to at least one forming die. at which point the laminate is formed into a tube having an overlap seam. At the forming dιe(s), the core is fed inside the formed plastic/metal tube. From the forming dιe(s). the plastic/metal tube containing the core is forwarded to at least one sizing die which sizes the plastic/metal tube to the proper dimension of the desired cable A heating source can be used to promote the adhesion of the overlap seam Next a jacketing resin is extruded onto the plastic/metal tube After the extrusion of the jacketing onto the plastic/metal tube, the final cable is cooled in a water bath and is typicallv wound on a coil Depending on final cable size and type of cable desired, the line speed of this cable fabπcation process can range from 8 ft/min (2.44 m/min.) to 300 ft/min (91 44 m min) In the present art. typicallv the contact surface energy of the plastic/metal laminate to the suπace of the pretormer. forming dιe( sι. and sizing diei s ) is sufficient to cause blocking ot the plastic/metal laminate resulting in some lerkmg motion ot the plastic/metal laminate as it is pulled through the cable fabrication process This blocking and jerking motion occasionally results in breakage of the plastic/metal laminate This blocking and resulting jerking motion is believed to be due to tight clearances of the forming and sizing dies and the typically high COF of the plastic/metal laminates of the present art Because of the substantial high surface contact energy as the plastic/metal laminate is pulled through the cable fabncation process, the surface of the thermoplastic polymer is significantly abraded causing flaking and dusting of the thermoplastic polymer, specifically around the pretormer. forming dιe(s). and sizing dιe(s), but more typicallv after the sizing dιe(s) The resulting dust and flakes can accumulate around the fabrication process, promoting process downtime. Additionally, there is a corresponding increase in temperature of the sizing dιe(s) as the formed plastic/metal tube is pulled through the sizing dιe(s). In order to lessen the abrasion, flaking, dusting, die temperature, and rate of laminate breakage, a preferred mode of operation in the industry is to apply an oil lubricant to the surface of the plastic/metal laminate pnor to the preforming operation of the fabncation process The intended purpose of the oil lubricant is to lower the COF of the plastic/metal laminate surface contacting the preformer, forming dιe(s). and sizing dιe(s) However, the use of an oil lubπcant can sometimes substantially reduce the adhesion performance of the plastic/metal laminate to the jacketing component as well as reduce the adhesion in the overlap seam. The use of an oil lubncant can also sometimes cause guidance problems between the plastic/metal laminate and affected process surfaces. Thus, there is a need in industry for plastic/metal laminates that exhibit reduced rates of breakage, exhibit reduced flaking and dusting, maintain or increase adhesion to jacket components, and maintain or increase adhesion in overlap seams while eliminating or substantially reducing the amount of oil lubncant needed dunng manufacture into articles such as electrical cables The present invention substantially solves the problems of. abrasion, flaking, dusting, and breakage of plastic/metal laminates (for example, plastic coated cable shielding tapes) dunng the shaping and forming of these laminates into cables and other formed plastic/metal articles while substantially reducing or eliminating the need to use an oil lubricant In general. Applicant has found that these problems are substantially solved by incorporating into the plastic layer of the plastic/metal laminate, a sufficient amount of embosser to substantially reduce the coefficient of fnction ot the laminate and to emboss the surface of the plastic laver When formed and incorporated into plastic/metal composite articles such as electrical cables, the plastic/metal laminates of the present invention also exhibit improved heat-sealabihty and adhesion to outer jacketing components - --- - Accordingly , in one aspect the present invention is a plastic/metal laminate comprising a metallic substrate and at least one surface layer adhered to said substrate either directly or ia an intermediate polymeric layer or iavers. said surface layer consisting essentially of a base adhesive polymer or blend of polymers and an amount of embosser sufficient to substantially lower the coefficient ot friction of the laminate and sufficient to emboss said surface layer In another aspect, the present invention is a more finished plastic/metal composite article, such as an electneal or communication cable, comprising a core of at least one insulating conductor or glass fiber, a shield surrounding said core, and an outer plastic jacket surrounding and adhered to said shield. said shield compnsing a metallic substrate, a surface layer adhered to said metallic substrate either directly or via an intermediate polymeric layer or layers, said surface layer consisting essentially of a base adhesive polymer or blend of polymers and an embosser, wherein said shield exhibits a greater bond strength to said outer plastic jacket relative to a similar shield differing only by the absence of embosser in said shield, and wherein said shield exhibits greater heat-seal values relative to a similar shield differing onlv in the absence of embosser in said shield Figure I is a graphical representation of heat sealability testing results for embodiments of the present invention In one embodiment, the present invention is a monolayer or multilayer thermoplastic adhesive system Adhesive systems of the present invention contain at least one layer consisting essentially of a base adhesive resin and an amount of embosser sufficient to lower the coefficient of fπction ("COF") of the adhesive system and sufficient to emboss the adhesive system Generally, adhesive systems of the present invention have a thickness of from 0 1 mil (2.54 μm) to 5 mil ( 127 μm) More preferably are adhesive systems with a thickness of from 0 2 mil (5 08 μm) to 5 mil (127 μm). and most preferred are adhesive systems with a thickness of from 1 mil (25 4 μm) to 2 5 mil (63 5 μm) Another embodiment of the present invention is a plastic/metal laminate formed bv applying adhesive svstems of the present invention to one or both sides ol a metallic substrate in the form of a stπp or tape The adhesive systems are applied via techniques well known in the art (tor example extrusion coating or lamination ) Generally, plastic/metal laminates of the present invention have a thickness of from 2 (50 8) to 25 mil (635 μm), and preferably, from 4 ( 101 6) to 15 mil (381 μm i Yet another embodiment of the present invention is a composite structure comprising a core component, a shield component surrounding the core, and an outer thermoplastic jacket component surrounding and adhered to the shield component wherein the shield component consists essentially of a plastic/metal laminate ot the present invention Adhesive svstems of the present invention must be capable of adheπng to both the metallic substrate of the plastic/metal laminate and the jacketing component of any composite article into which the laminate may be incorporated In a multilayer adhesive system the outer or surface layer li e . laver to be adhered to the jacketing component) must contain the requisite sufficient amount of embosser In a multilayer adhesive system, layers other than the surface layer do not necessarily contain embosser and may comprise either the same or a different base adhesive resin than the surface layer. Thermoplastic polymers suitable for use in the base adhesive resin of the present invention ( base adhesive polymers") arc generally those known in the art of producing laminates useful for manufacturing communication cables. Prefened base adhesive polymers include the known normally solid random copolymers of a major proportion ot ethylene with a minor proportion ( for example, typically from 1 to 30. preferably from 2 to 20, percent by weight based upon the weight of such copolymer) of an ethylenically unsaturated carboxylic acid monomer. Specific examples of such suitable ethylenically unsaturated carboxylic acids (which term includes mono- and polybasic acids, acid anhydndes. and panial esters of polybasic acids, as well as the various metallic salts thereof) are acrylic acid, methacrylic acid, crotonic acid, fumanc acid, maleic acid, itaconic acid, maleic anhydride, mono- methyl maleate. monoethyl maleate. monomethyl fumarate. monoethyl fumarate. tπpropylene glycol mono-methyl ether acid maleate, or ethylene glycol mono-phenyl ether acid moleaie. The carboxylic acid monomer is preferably selected from the alpha/beta-eihylenically unsaturated mono- and polycarboxylic acids and acid anhydndes having from 3 to 8 carbon atoms per molecule and panial esters of such poly carboxylic acid wherein the acid moiety has at least one carboxylic acid group and the alcohol moiety has from 1 to 20 carbon atoms. Such copolymers may consist essentially of ethylene and one or more of such ethylenically unsaturated acid or anhydride commoners or can also contain a small amount of other monomer copolymenzable with ethylene. Thus, the copolymers can contain other copolymenzable monomers including esters of acrylic acid, methacrylic acid and the like. Random copolymers of such type and methods of making them are readily know in the art. Other thermoplastic polymers suitable for use in the present invention include the known olefin polymers which are. as a general rule, the ethylenic olefin polymers such as. for example, the various known ethylene homopolymers (for example, ultra low. linear low. low. medium, and high density polyethylene s having a density range of 0.82 to 0.96 g/cc). copolymers having a major proportion of ethylene with a minor proportion of known copolymenzable monomers such as higher (tor example. C3 to C12 alpha-olefins. ethylenically unsaturated ester monomers (for example, vinyl acetate, ethyl acrylate. etc. ). and graft modified versions of such ethylenic homopolymer and copolymer ( for example, grafted with acrylic acid, maleic anhydnde. etc. ). Olefin polymers, copolymers of such type and chemically modified olefin and or copolymers of such type and methods of making them are readily known in the an. In one embodiment of the present invention, the base adhesive resin is a blend of (a) a random copolymer of ethylene with an ethylenically unsaturated carboxylic acid monomer with (b ) at least one different ethylenic olefin and or a copolymer of an ethylenic olefin polymer resin which is not a random ethylene/unsaturated carboxylic acid copolymer. Preferably, the base adhesive resin compnses from 5 percent to 95 percent of (a), more preferably from 50 percent to 95 percent, and most preferably from 65 percent to 95 percent, based on the weight ot the base adhesive resin Preferably the base adhesive resin also comprises from ϋ percent to 95 percent ot (b). more preferably 0 percent to 50 percent, and most preferably from 5 percent to 20 percent, based on the weight of the base adhesive resin Further, it should be understood that when random copolymers ot ethvlene with an ethylenically unsaturated carboxylic acid" are refened to it is intended to include therewith the known partially or fully neutralized versions thereof which are commonly retereed to in the art as lonomers Further still, it should be understood that when "different ethylenic olefin and or a copolymer of an ethylenic olefin polymer resin which is not a random ethvlene/unsaturated carboxvlic acid copolymer is refened to. it is intended to include ethylenic olefin polymers that may be modified by copolymerizaiion or graft copolymerizaiion techniques employing an ethylenically unsaturated dicarboxyiic acid anhydride or anhydride precursor, esters of an ethylenically unsaturated dicarboxyiic acid and rubber modified derivatives thereof Generally, embossers useful in the present invention are otherwise known in the an as organic or inorganic fillers Embossers suitable for use in the present invention are desirably substantially noncompatibilized. chemically-inen. and insoluble in the base adhesive polymers Being non- compatibihzed refers to a substantial lack of chemical (for example polymeric) linking or bonding with the base adhesive polymers and preferably such a lack with respect to any other substance in the film Being chemically men refers to a substantial inability to dissolve in the base adhesive polymers, or preferably, any other components in the base adhesive resin. Being insoluble refers to a substantial inability to dissolve in the base adhesive polymers to an extent such that the physical integnty of the embossed surface is substantially maintained. The amount of embosser must be sufficient to substantially lower the COF of the plastic/metal laminate and to emboss the surface of the plastic/metal laminate. By embossing the surface of the plastic/metal laminate, it is meant that there are bosses on the surface ranging in height from 1/100th to l/4th of the thickness of the adhesive layer(s). Larger bosses result in too rough of a surface and adversely affect film strength and other properties Smaller bosses are generally less effective in reducing the COF of the plastic/metal laminate. Surface embossing was herein evaluated by measuring the difference in contact measurement of the thermoplastic polymer as defined in ASTM D374 and weight measurement of the thermoplastic polymer as defined in ASTM E252 Preferably, the surface layer contains from 0 1 weight percent to 16 weight percent of embosser, more preferably from 2 weight percent to 16 weight percent, and most preferably from 4 weight percent to 8 weight percent. Examples of organic embossers suitable for use in the present invention include paniculated polyester, polytetrafluoroethylene ("PTFE"). nylon, polystyrene, high-impact polystyrene ι HIPS") styreneacrylonitπle ("SAN"), acrylonitnle-butadiene-styrene CABS"), polycarbonate, etc Suitable inorganic embossers include paniculated graphite, mica, chalk, calcium sulfate. caicium silicate, calcium carbonate, talcum, bentonues. barvtes. kaolin, magnesium aluminum silicates, magnesium silicate, mineral colloids, pyrophylite. sentes. silicas, tena alba, etc Prefened embossers are non-compatibilized. non-hygroscopic and non-microporous forming in the base adhesive polymers A most prefened embosser is mica, which has the ability of not only effectively imparting a uniform embossed surface to the plastic/metal laminate, but also to improve the adhesion properties of the plastic/metal laminate By substantially loweπng the COF of the plastic/metal laminate, it is meant that both the resulting static or staning COF and resulting kinetic or sliding COF are lower than the static COF and kinetic COF of an essentially identical plastic/metal laminate differing only by the absence of any embosser The static and kinetic COFs of the plastic/metal laminate were measured using a modified ASTM Dl 894 (See Example I ) Preferably, the static COF of the plastic/metal laminate is at most 040 more preferably at most 0.30. and most preferably, at most 0.20 as measured by the modified ASTM D1894 Preferably, the kinetic COF of the plastic/metal laminate is at most 040. more preferably at most 0.30. and most preferably, at most 0.20 as measured by the modified ASTM D1894 Plastic/metal laminates ot the present invention exhibit improved adhesion Adhesion properties were evaluated by measuring the peel strength of the plastic/metal laminate pursuant to a modified ASTM B736 (See Example II) The adhesion of the plastic/metal laminate to matenals typically found in jacketing components was measure using a modified ASTM 1876 (See Example V) Further, it should be understood that when improved adhesion is referred to herein, it is meant that the adhesion is improved relative to the adhesion observed when utilizing essentially identical plastic/metal laminates or composite articles differing only by the absence of embosser. Preferably, the adhesion between layers of a multilayer adhesive system of the present invention is at least 5 lbs/in. more preferably at least 8 lbs/in ( 142.86 kg/m l. and most preferably at least 12 lbs/in (214.30 kg/m) as measured by the modified ASTM B736 Preferably, the adhesion between a coating layer ( i e. such as an outer insulating jacketing layer in an electncal cable) and plastic/metal laminates ot the present invention is at least 8 lbs/in. more preferably at least 10 lbs/in ( 178 58 kg/m ). and most preferably at least 15 lbs/in (267 87) as measured by the modified ASTM 1876 The thickness of metallic substrates (for example, sheets, strips, foils, etc ) employed in the present invention is not cπtical Foils less than 1 mil may be used as well as relatively thick sheets Typically, metallic substrates have a thickness of from 3 (76 2) to 25 mil (635 OOum). and preferably trom 4 mil ( 101 60) to 15 mil (381 OOμm) The metallic substrate can be composed of a wide variety of metallic matenals such as. tor example, aluminum, aluminum alloys, alloy-clad aluminum, copper, surface modified copper, bronze steel, tin free steel, tin plate steel, aluminized steel, aluminum-clad steel, stainless steel, copper-clad stainless steel, copper-clad low carbon steel, terne-plate steel, galvanized steel, chrome plated or chrome treated steel, lead, magnesium, tin and the like. Such metals can. of course, be surface treated or have conversion coatincs on the surface thereof if desired Particularly prefened metallic substrates tor use herein include those composed of chrome/chrome oxide coated steel (also commonly refened to in the art as tin-free steel ), stainless steel, aluminum, and copper Adhesive systems of the present invention can be applied to the metallic substrates in any convenient fashion which may be desired. For example, conventional extrusion coating techniques may be employed to apply the adhesive system to the chosen metallic substrate. Alternatively, conventional film lamination techniques can also be suitably employed to adhere an adhesive film system to the desired metallic substrate. Also, a combination of conventional coextrusion and film lamination technologies can be employed. For example, it may be desirable to first extrude or coextrude an adhesive system as a film and laminate the film to one or two surfaces of a metallic substrate. EXAMPLES The present invention is further illustrated by. but is not to be understood as being in any way limned to. the following examples. In the following examples, all pans and percentages are based on weight unless otherwise indicated Example I In this example. 1.6 mil (40.64 μm) thick monoiayer adhesive films were created using a conventional blown film process. The adhesive film contained a base adhesive resin and a blend containing high density polyethylene and 40 weight percent mica (i.e.. Micafil 40. available from DuPont Canada). The base adhesive resin was a blend of a random ethylene/acrylic acid ("EAA") copolymer and an olefin polymer. The EAA copolymer contained 6 weight percent acrylic acid based upon the weight of the copolymer and had a melt index of 5.5. The olefin polymer used was either a polyethylene having a melt index of 5.5 and a density of 0.916 g/cc ("LDPE- 1 ") or a polyethylene having a melt index 5.0 and a density of 0.958 g/cc ( "HDPE- 1 "). The amounts of EAA. LDPE- 1. HDPE- 1. and Micafil 40 used in various samples are shown in Table I. The vaπous film samples were laminated to one side of a 7.5 mil (190.5μm) thick sheet of aluminum. In the preparation of such samples, the indicated monoiayer film was laminated by preheating the metal for one minute in a circulating air oven heated to 300°F ( 148.89°C) and by then pulling the preheated metal sheet and the indicated monoiayer film through a set of rubber nip rolls. The resulting laminate was then post heated for one minute in a circulating air oven heated to 300°F ( 148.89°C) The resulting post heated laminate was allowed to equilibrate in 73°F (22.78°C) air having 50 percent relative humidity for at least 12 hours before any testing was done. The resulting laminate samples were cut using a template into 2.75 inches (6.99cm i by 4.00 inch ( 10.16 cm ) pieces, with the larger dimension in the machine direction. Laminate samples were subjected to coefficient of friction (COF) testing in accordance with ASTM Dl 894 (except that a five- inch per minute crosshead speed, a 2000 gram load cell, a #7 high luster stainless steel plate, and a 1 kg sled are employed, conditioning is at least 12 hours in 50 percent relative humidity air at 73°F (22.78°C . TABLE 1 9c ---: <?€ <7c < 7c Micafiμo Static Kinetic Sample # EΔΔ LDPE- 1 HDPE- I. COF COF control 91.00 5.00 0.5429 0 5257 1-1 40.00 56.00 0.3320 0.3120 1-2 67.20 16.80 12.00 0.2313 0.2099 1-3 60.80 15.20 20.00 0.2005 0.1696 1-4 58.80 25.20 12.00 0.1757 0.1518 1-5 53.20 22.80 20.00 0.1796 0.1532 1-6 46.20 19.80 30.00 0.1449 0.1289 1-7 43.20 10.80 30.00 0.1428 0.1359 1-8 79.00 5.00 12.00 0.3400 0.3150 1-9 71.00 5.00 20.00 0.2727 0.2509 1-10 61.00 5.00 30.00 0.1940 0.1657 1- 1 1 94.00 2.00 0.4520 0.4152 1-12 84.00 12.00 0.3300 0.3150 1-13 76.00 20.00 0.2795 0.2572 The balance of the film composition contained approximately equal weight percents of anti-blocking agent and heat stabihzing antioxidam agent and testing is performed on at least 5 test specimens) at standard constant laboratory conditions. The results of COF testing are shown in Table I. A control sample was created and tested in the same way as the above examples except that no mica was incorporated in the adhesive film used to make the laminates. The results in Table I show that laminates utilizing relatively high levels of high density polyethylene exhibit reduced COF values relative to COF values exhibited by the control (Sample I- 1 v s control). However, the results in Table I also show that the addition of mica in sample laminates results in more significant reductions in COF values. Example II Laminates were prepared in the same manner as the laminates in Example I. In addition to the olefin polymers used in Example I (i.e.. LDPE- 1 and HDPE- 1 ), an additional low density polyethylene, having a melt index of 1 9 and a density of 0.925 g cc ("LDPE-2"), was used. The laminates were cut TABLE II Peak Average Heat Heat * 9c 9c 9c a c Micaf-l Seal Seal Sample # EΔΔ I .DPF.- I IDPE-: HDPE- 1 4Q ( kg/ ) ( kg/m ) control 91.00 5 00 150.36 1 12.76 II- 1 40.00 56.00 18.54 17 45 II-2 67.20 16.80 12.00 103.43 60.41 II-3 60.80 15.20 20.00 96.15 46.27 II-4 52.80 25.20 12.00 73.27 35.88 II-5 53.20 22.80 20.00 89.70 37.20 II-6 40.00 54.00 2.00 17.84 17.18 II-7 40.00 44.00 12.00 27.32 24.66 40.00 36.00 20.00 31.56 30.75 II-9 61.00 5.00 30.00 42.93 37.61 11-10 94.00 2.00 101 84 86.02 11-1 1 84.00 12.00 73.74 49.77 11-12 76.00 20.00 167.94 147.94 The balance of the film composition contained approximately equal weight percents of anti¬ blocking agent and heat stabihzing/antioxidant agent. into samples that were 1 inch (2.54cmι wide by 6 inches ( 15.24cm), with the larger dimension in the machine direction. Samples were subjected to 90° heat sealabihty testing in accordance with ASTM B736 (except that a 12-ιnches per minute crosshead speed, a 25 kilograms load cell, a heat seal temperature of 300° F ( 148 89°C). a heat seal pressure of 40 psig, a dwell time of 2 seconds are employed, conditioning is at least 5 minutes in 50 percent relative humidity air at 73° F (22.78°C). and testing is performed on at least 5 test specimens) at standard laboratory conditions For comparison purposes, a control sample was created and tested in the same manner as the other samples. The control did not contain any HDPE- 1 or Micafil 40 The heat sealabihty testing results for each sample are shown in Table II The results in Table II show that the addition of a relatively high level of high density polyethylene in a blend with EAA significantly reduces the adhesion propeπies of the sample as compared to the control sample. Further still, it is seen that the addition ot mica in blends with low density and high density polyethylene can also substantially reduce the adhesion properties of the laminate. However, given the proper balance of mica and high density polyethylene in blends (for example, via Micafil 40) with the random ethylene/carboxylic acid copolymer. significant improvement tn heat sealabihty adhesion properties can be obtained as compared to the control laminate (11-12 vs control ). Example III Samples were prepared and tested in a manner similar to the samples in Examples I and II. However, the adhesive film used to prepare the samples was a 2.3 mil (58.42μm) thick two-layer adhesive film with each layer being of equal thickness. The adhesive film was prepared by a conventional cast film process as opposed to a blown film process. For comparison, a control sample was prepared using a 2.3 mil (58.42μm) thick monoiayer film. Each sample in Example III had one layer contacting the metal having the same composition as the control. The composition of the other layer (surface layer) in each sample is shown in Table III. The samples were tested in the same manner as the samples in Examples I and II and the test results are also shown in Table III. IΔELE -JI Peak Average 9c Heat Heat * 9c 9c a c Micafil Static Kinetic Seal Seal Sample # FAA LDPE- I HDPE- 1 4Q £ΩE COF I kg/m i ( kg/m i control 91.00 5.00 0.7834 0.7386 273.23 1 16.43 III- l 45.60 30.40 20.00 0.1900 0.1734 170.72 141.08 III-2 57.60 38.40 0.6150 0.6064 237.87 140.19 III-3 45.60 30.40 20.00 0.3015 0.3440 1 18.04 92.33 III-4 57.60 38.40 0.4375 0.2773 176.26 101.25 III-5 91.00 5.00 0.4235 0.4356 263.94 121.61 III-6 45.60 38.40 12.00 0.2682 0.2764 159.29 1 10.54 III-7 76.00 20.00 0.2934 0.2595 255.01 233.23 III-8 45.60 38.40 12.00 0.4398 0.3788 191.26 88.93 III-9 72.33 10.46 13.21 0.1900 0.1700 239.30 179.47 III- 10 57.31 24.38 14.21 0.1200 0.1080 202.33 160.19 * The balance of the surface layer composition contained approximately equal weight percents of anti¬ blocking agent and heat stabilizing/antioxidant agent. Example IV Two sets of samples were prepared in the same manner as the samples in Example III. The samples in one set had a thickness of 1.6 mil (40.64 μmt and the samples in the other set had a thickness of 2.3 mil (58.42μm). Each set of samples contained samples made in accordance with both Sample Ill- control and Sample III-7. The samples were cut into 1 inch by 6 inch pieces with the larger dimension in the machine direction. The samples were subjected to heat sealabihty testing in accordance with the same modified ASTM B736 of Example III (except that heat seal temperatures of 200. 250. 300. 350. and 400 °F (204.44°C) were employed). The results of these tests are depicted graphically in Figure 1. From the results depicted in Figure 1. it is seen that a substantial improvement in heat sealability is achieved at low heat sealability temperatures. The results in Figure 1 also sho that the thickness of the samples had verv little, if anv. effect. Example v Samples were prepared in the same manner as the samples in Example III except in that the two-layer adhesive film had a total thickness of 1 6 mil (40 64 μm) instead of 2 3 mil (58 42μ ι To test adhesion to typical jacketing component materials, these samples were compression molded to two different sets of 75 mil ( 1.905μm) thick sheets of polyethylene to form composite structures The first set of sheets were made of a high density polyethylene IUC3479. available from Union Carbide i and the second set of sheets were made of a medium density polyethylene ( UC8864. available from Union Carbide) Both sets of sheets also contained approximately 2.6 weight percent carbon black In the compression molding operation to form these composite structures, a platen press was employed The laminate samples were placed in contact with the sheets in the press and compression molding was accomplished at 230°C and 15 psig for three minutes The resulting composite structure was then cooled to room temperature in the platen press, removed from the press, and subsequently cut into 1 inch wide by 6 inch strips with the larger dimension in the machine direction Some of the resulting stnps were then subjected to 180° peel with backing plate testing in accordance with ASTM D1876 (except that a two-inch per minute crosshead speed, a 25 kilograms load cell is employed, conditioning is for 12 to 48 hours in 50 percent relative humidity air at 73°F (22.78°C), the bonded and unbonded lengths of the polymer layer are 2.5 and 0.5 inches respectively, and testing is performed on at least 3 test specimens instead of ten) Other strips were immersed (i.e . aged") in water at 140°F (60°C) for 7, 30, 60 and 120 days, allowed to equilibrate and dry in 50 percent relative humidity. 73°F (22.78°C) air, overnight and then were also subjected to the aforementioned 180° peel test. For comparison purposes, a control sample was prepared and tested in the same manner as the other samples except the adhesive film used was a 2.3 mil (58 42μm) thick monoiayer film The peel testing results for each sample are shown in Table V-A for the HDPE-2 sheets and in Table V-B for the MDPE sheets As can be seen from the results in Table V-A and Table V-B. the Examples ot the present invention exhibit improvement in aged adhesion TABLE V-A HDPE JACKET BOND ADHESION (kg/m) 9c * 9c 9c Micafil peel peel peel peel peel Sample #. EΔΔ LEE-- 1 40 initial 7davs ?tøaγs. 60 davs 1 0 davs control 91.00 5.00 13.46 16.12 17.03 16.91 17.00 V-A- l 75.60 8.40 12.00 1 1.58 20.65 20.90 20.89 20.90 V-A-2 58.80 25.20 12.00 1 1.68 18.08 19.15 18.67 19.00 The balance of the surface layer composition contained approximately equal weight percents anti¬ blocking agent and heat stabilizing/antioxidant agent. TABLE V-B MDPE JACKET BOND ADHESION (kg/m) * % Micafil peel peel peel peel peel Sample # EΔΔ LDPE- 1 4Q initial 7davs 30davs 60 days 120 days control 91.00 5.00 13.77 15.39 16.29 16.27 16.20 V-B- l 75.60 8.40 12.00 11.92 19.71 21.81 21.83 21.80 V-B-2 58.80 25.20 12.00 12.35 18.49 18.88 18.33 18.25 The balance of the surface layer composition contained approximately equal weight percents anti¬ blocking agent and heat stabilizing/antioxidant agent. Example VI In this example, laminates were prepared in the same manner as Example III. The resulting laminates were then slit to a 1 1 1/16 inch (4.29 c iwidth tape and were shaped and formed into electrical and or communication cables using a conventional cable manufacturing process as described in this application. The laminates used to make the cables are shown in Table VI and some resulting cable processing data are shown in Table VII. TABLE vi LAMINATES USED TO MAKE CABLES 9c * 9c 9c 9c Micafil Static Kinetic laminate Sample # EΔΔ LDPE- 1 HDPF.- l άΩ COF surface control 91.00 5 00 0 7834 0 7386 smooth VI- 1 57.60 38.40 0.4136 0.2814 smooth VI-2 58.80 25.20 12.00 0.2700 0.2800 embossed VI-3 67.20 16.80 12.00 0.3200 0.2400 embossed Vl-4 76.00 20.00 0.2600 0.2200 embossed The balance of the surface layer composition contained approximately equal weight percents anti-blocking agent and heat stabilizing antioxidant agent. From the results in Table VII, it is seen that substantial improvement in the fabncation of plastic/metal laminates into electncal and/or communication cables can be achieved with laminates of the present invention. While the present invention has been herein illustrated by reference to particular embodiments and examples thereof, such fact is not to be understood as in any way limiting the scope of the present invention. TABLE Vll PROCESSING DATA FOR LAMINATES USED TO MAKE CABLES flaking & cable line use of dusting at tape breaks at final temp speed oil formers & dies weld point ( °C) at sizing die Sample # meters/min. lubricant control 40 no yes yes 29.44 50 no yes yes 30 60 no yes yes 31.1 1 control 40 yes yes yes 25 50 yes yes yes 25.56 60 yes yes yes 26.1 1 VII- 1 40 no yes no 27.78 50 no yes no 27.78 60 no yes no 28.33 VII-2 40 no no no 28.89 50 no no no 27.22 60 no no no 27.22 VII-3 40 no no no 26.67 50 no no no 26.67 60 no no no 26.67 VII-4 40 no no no 27.22

Claims: 1 A laminate comprising a) a metallic substrate. b) a surface layer adhered to said substrate either directly or via an intermediate polymeric layer or layers; said surface layer consisting essentially ot a base adhesive resin and an amount ot embosser sufficient to substantially lower the coefficient ot friction ot the laminate and sufficient to emboss said surface layer. 2 A laminate according to Claim 1 wherein the laminate has a peak heat seal of at least 5 lb/in (89.29 kg/m) and an average heat seal of at least 5 lb/in (89 29 kg/m) 3 A laminate according to Claim 1. wherein the laminate has a peak heat seal of at least 8 lb/in ( 142.86 kg/m). and an average heat seal of at least 8 lb/in ( 142.86 kg/m i 4 A laminate according to Claim 1. wherein the base adhesive resin consists essentially of a blend of (a) a random copolymer of ethylene with an ethylenically unsaturated carboxylic acid monomer with (b) at least one different ethylenic olefin and or a copolymer of an ethylenic olefin polymer resin which is not a random ethvlene/unsaturated carboxylic acid copolymer. 5. A laminate according to Claim I . wherein the ethylenic olefin polymer resin is selected from the group consisting of ethylene homopolymers and copolymers having a major proportion of ethylene with a minor proportion of a commoner which is polymeπzable and or reacted therewith 6 A laminate according to Claim I . wherein the ethylene olefin polymer is a high density polyethylene. 7 A laminate according to Claim 1. wherein the embosser is mica 8 A plastic/metal laminate, compnsing a) a metallic substrate. b) an intermediate thermoplastic polymer laver adhered to at least one surface of said metallic substrate, said intermediate layer comprising a random copolymer ot ethylene with an ethylenically unsaturated carboxylic acid monomer. c i a surface layer adhered to said intermediate layer, consisting essentially of ι ) a random copolymer ot ethylene with an ethvlenically unsaturated carboxylic acid monomer. u ) at least one olefin polymer resin which is not a random copolymer ot ethylene with an ethylenically unsaturated carboxylic acid monomer. in ) an amount of embosser sufficient to substantially lower the coefficient ot fnction of the laminate and sufficient to emboss said surface layer 9 A laminate according to Claim 8 wherein the laminate has a peak heat seal of at least 5 lb/m (89.29 kg/m i and an average heat seal of at least 5 lb/in (89 29 kg/m ) 10 A laminate according to Claim 8. wherein the laminate has a peak heat seal of at least 8 lb/in ( 142 86 kg/m ) and an average heat seal of at least 8 lb/in ( 142.86 kg/m i 1 1 A laminate according to Claim 8. wherein the ethylenic olefin polymer resin is selected from the group consisting ot ethylene homopolymers and copoiymers having a major proponion of ethylene with a minor proponion of a commoner which is polvmenzable and or reacted therewith 12 A laminate according to Claim 8. wherein the ethylene olefin polymer is a high density polyethylene 13 An article compnsing a core of at least one insulating conductor, a shield sunounding said core, and an outer plastic jacket suπounding and adhered to said shield, wherein said shield consists essentially of a laminate according to either Claim I or Claim 8 14 An article according to Claim 13. wherein the bond strength of said shield to said outer jacket is at least 8 lbs/in ( 142.86 kg/m) Plastic/metal laminates ( tor example, plastic-coated cable shielding or armoring tapes) having improved friction, adhesion, and heat-sealability propeπies w hich comprise at least one metallic substrate having directly adhered to at least one surface thereof a thermoplastic adhesive layer containing an amount of embosser sufficient to substantially lower the coefficient of friction of the laminate and sufficient to emboss the surtace of the plastic/metal laminate

Inventors: ACHILLE FELIX, ACHILLE, FELIX
Applicants: DOW CHEMICAL CO, THE DOW CHEMICAL COMPANY
Application year: 1996
Main classification: B32B15
IPC codes: B32B15