Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
  • C08L77/12—Polyester-amides

Definitions

• the present invention relates to a thermoplastic biodegradable, preferably fully biodegradable polymer ("biopolymer”) having uniformly dispersed therein a mixture of an inert particulate filler and at least one particulate, vapor phase inhibiting (“VPI”) or volatile corrosion inhibiting (“VCI”) ingredient in a polymeric article of arbitrary shape and cross-section.
• biopolymer preferably fully biodegradable polymer
• VPI volatile corrosion inhibiting
• inert is meant that the filler particles are environmentally friendly and do not react chemically with either the polymer or any of the additives therein. It is essential that the VCI and filler are to be substantially uniformly dispersed within the mass of a thermoplastic biopolymer which is to be shaped so as to form a sealed enclosure for a corrosion-prone or tarnish-prone metal object. Though ingredients effective to convert the polymer into a VCI polymer are also inert relative to the polymer, and are technically also "filler” particles, the term “filler particles” as used herein refers specifically to particles other than those to which the corrosion or tarnish inhibition is attributable, such filler particles being talc, calcium carbonate, silica, and the like.
• the shaped article is typically a synthetic resinous (hereafter also "plastic") box- like container or film such as is used to protect metal objects packaged for storage and transportation.
• the shaped article is an extruded, blown or cast sheet of film which can be wrapped around the metal object and sealed; or, wrapped around a container in which the metal object is held, then sealed; or, the shaped article is a container, such as a box or gun case which is injection molded, blow molded, or otherwise thermoformed; or, a liner less than 0.25 mm thick, to be inserted in the box or gun case.
• Metal objects including ferrous ones, are commonly packaged in either a polyolefinic (“PO") bag or flexible container of PO film, typically polyethylene (“PE”) or polypropylene (“PP); or, in a rigid cardboard or wood container which is lined with a relatively flexible film in which metal parts are sealed.
• PO polyolefinic
• PE polyethylene
• PP polypropylene
• VCI film Dispersed in conventional "VCI film", as an integral part thereof, is a small amount of inert filler particles, typically silica, no more than 5 parts by weight of particles in 100 parts of thermoformed article (5 % by weight or 5 wt%) and an effective amount of VCI ingredient, more preferably a combination of VCIs providing protection for a year or more.
• a VCI in a polymer functions as such because its effectiveness derives from diffusion of the compound, such as vapor of the compound diffusing through the polymer.
• the effectiveness of protection accorded is necessarily attributed to the combined vapor pressure exerted by the VCIs which provide the corrosion protection without the VCI compounds themselves directly contacting the metal surfaces of an article being protected; the wall of the container, or the plastic wrap around the article, is generally spaced apart from the surface; vapor diffuses through the plastic in which the VCIs are dispersed and inhibits corrosion of metal held in the sealed space within the plastic.
• thermoprocessable polymer containing a hindered phenol in combination with an alkali metal nitrite, and less than 1 wt% of silica.
• the PE or PE/polyester films specifically disclosed therein may contain additional additives such as are conventionally used to improve the processability and stability of the polymer, for example, antioxidants, processing aids, heat stabilizers, and the like.
• Microtrac-XlOO which measures sizes in the range from 0.04 - 704 ⁇ m of particles suspended in a liquid by laser light diffraction and dynamic light scattering.
• Tensile strength is measured according to ASTM 882-01 which is incorporated by reference thereto as if fully set forth herein.
• the conventional way to disperse a particulate ingredient, smaller than about 45 ⁇ m (micrometers) into any polymer, is by melt- processing a mixture of the ingredient and polymer, either in an extruder, or by plasticizing the polymer sufficiently so as to then be able to mix the ingredient into the plasticized mass.
• a particulate ingredient smaller than about 45 ⁇ m (micrometers) into any polymer
• plasticizing the polymer sufficiently so as to then be able to mix the ingredient into the plasticized mass.
• particles agglomerate, such agglomeration being particularly severe in any biopolymer.
• the sodium nitrite is incorporated into the polymer as particles in the size range from about 1 ⁇ m to 45 ⁇ m, all of which pass through a 325 mesh screen or 45 ⁇ m (Standard Test Sieves)
• large agglomerates of small particles each agglomerate greater than 50 ⁇ m, are formed.
• the formation of agglomerates does not allow the small particles to be uniformly distributed and packed around the VCI in the polymer when an article is molded, or a film is extruded, causing an expected decrease in tensile strength.
• large agglomerates decrease the strength of film, get caught in screens inside an extruder (which screens are used to protect the die from damage by large particles), and cause the polymer's melt-processed surface to be noticeably rough to the touch, compared to a smooth surface of the same polymer without any particles.
• substantially transparent is meant that a film 0.025 mm (1 mil) thick is sufficiently light-permeable so that 12-point (font) print on this page can be read through the film, irrespective of its color; films as thick as 0.125 mm (5 mils) may be substantially transparent.
• addition of inert particles in the polymer even if uniformly distributed, will greatly decrease its tensile strength at break, its elongation at break, its tensile modulus of elasticity, and its Elmendorf tear strength; the higher the concentration of inert particles in the film, the stiffer and weaker the film, and, both the stiffness and the rigidity are greatly increased by large agglomerates in the polymer;
• biodegradable plastic films typically offer less protection to metallic articles than is available from the more traditional polyolefin films.
• this disadvantage may be overcome when the biodegradable plastic resin film is combined with a particulate vapor phase corrosion inhibitor dispersed within and through the film or coated on the surface of the film.
• the selected vapor phase corrosion inhibitors used in connection with the present invention are highly compatible with biodegradable resins and films, and offer significant protection to metallic articles within an enclosure.” (see '929, col 1, lines 49-62).
• the e 929 patent further states: "To offset the greater permeability and accessibility of the enclosure to corrosive atmospheres rich in water vapor, salt air, carbon dioxide, sulfur dioxide, hydrogen sulfide, or other gases which pose a threat to the surfaces of metallic objects, a vapor phase corrosion inhibitor in films of the type selected for this invention will provide significant protection for metallic articles, as well as other advantages.” (see col 2, lines 9 - 15).
• any thermally processable organic polymers may be used in the preparation of a VCI-containing article and specifically disclosed polyolefins, polyolefin/polyester and polyester/- polyvinylchloride plastisols.
• the polyolefins included PE and polypropylene ("PP"); the polyolefin/polyester was commercially available Microthene FE-532 having randomly i distributed chains of PE and polyvinylacetate, the chains being of arbitrary length.
• VCI ingredients used in the '912 patent is an inorganic nitrite, a hindered phenol, and fumed silica; in particular, an alkali metal nitrite, e.g. potassium nitrite or sodium nitrite, in combination with a 2,4,6-tri- substituted phenol and fumed silica.
• a specific '912 combination in PE film comprised about equal parts (1.485 phr each) by weight of sodium nitrite and 2,6-di-tert-butyl-4- methyl phenol, along with 0.03 phr fumed silica, the film being extruded at 149°C (300°F).
• a biodegradable polymer which has a WVTR in the range from at least twice to about 50 times greater than that of low density PE having a melt flow index of 1 g/10 min, each of the same thickness, may be filled with more than 5 wt%, and up to about 35 wt% of an inert particulate filler, and is not only substantially transparent if the neat biopolymer is transparent, as evidenced by a 0.025 mm thick cross-section, but also provides better corrosion protection than the PE film without decreasing the tensile strength of the film below a critical tensile strength of 2000 psi in either the machine or transverse direction, preferably in both directions.
• the particles be dried at a temperature higher than a projected molding or extrusion temperature of the film, so that the particles are essentially anhydrous, preferably with less than 100 ppm moisture. Uniformity of distribution of the solid particles in the biopolymer is essential to avoid unduly decreasing the tensile strength of the filled biopolymer.
• a "filled" biopolymer provides a higher WVTR than the "neat” biopolymer.
• the result of the higher WVTR of the filled biopolymer, which WVTR is from about 1% to 20% higher than that of the neat biopolymer, is that the polymer filled with both VCI ingredients and filler particles, provides at least as good protection as the unfilled biopolymer, and typically, better protection of metals against corrosion as measured below.
• Preferred biopolymers include aromatic-aliphatic copolyesters, aliphatic polyesters having repeating units having from 2 to 5 carbons atoms, and, polyesteramides formed by reaction with at least one diacid, at least one diol, and at least one amino acid.
• the biofilm is uniquely adapted to be "filled" with a relatively high concentration, preferably from about 10 - 30 wt%, of micronized inert filler particles in the primary particle size range from about 1 ⁇ m - 45 ⁇ m, wherein at least 75% of the particles are smaller than about 20 ⁇ m, more preferably from about 1 ⁇ m - 25 ⁇ m, wherein at least 75% of the particles are smaller than about 15 ⁇ m, in combination with at least one VCI which is in particulate form in the size range from about 1 ⁇ m - 45 ⁇ m, and the particles are substantially uniformly dispersed in the polymer provided all ingredients added to the polymer before it is thermoformed are essentially anhydrous, that is, the moisture (water) content whether absorbed or not, is less than 0.05%, preferably less than 200 ppm, and most preferably less than 100 ppm.
• the inert particles are required to be substantially light permeable, preferably having a refractive index ⁇ 20% of the refractive index of the neat polymer; the smaller the particles, the greater the tolerance in refractive index.
• the inert particles have an aspect ratio ⁇ 10 so they are clearly not fiber fragments.
• aspect ratio of an irregular particle is meant the ratio of its longest dimension in the longitudinal direction, divided by its longest dimension in a direction normal to the longitudinal direction.
• particles with a very low specific surface area ideally 6/diameter, or "6/d", for spherical particles
• particles with irregular surfaces and a specific surface ratio greater than 12/d, more preferably from 12/d to 60/d are preferred.
• the specific surface ratio is the ratio of surface area to volume of a particle.
• particles with a refractive index relatively closely matched to that of the biopolymer are likely to be invisible when dispersed in the polymer; however, the high aspect ratio of the small particles causes such a high degree of scattering of light that the film would be expected to appear opaque, this being the same reason why a mass of finely divided talc (refractive index 1.573) and calcium carbonate (ref. ind. 1.63) particles appears opaque.
• a shaped article of an aromatic-aliphatic copolyester includes one or more VCI ingredients in an amount less than 3 wt%, and from more than 5 wt% to about 35 wt% of an essentially anhydrous inert filler substantially uniformly distributed in the polymer so as to have a tensile strength of 2000 psi in at least one direction; further a cross- section of the article 0.025 mm thick, is substantially transparent and essentially free of agglomerates greater than 50 ⁇ m, that is, there are less than 5 such agglomerates / cm 2 of film which is 0.05 mm thick.
• uniformly distributed is meant that the uniformity of dispersed particles in the film may be quantified by known microscopic techniques, or by a blown film test.
• the polymer containing solid powder particles is extruded through a blown film apparatus which produces a film about 0.025 mm (1 mil) thick, and this film is placed over a light source of appropriate wavelength and intensity to enable one to quantify the number of particles which show up as "imperfections"; and the size of each is also visible under appropriate magnification.
• No unit area of the film appears to have a substantially higher concentration of particles than another, that is, the variation in population density of the particles is less than + 20%, preferably less than about ⁇ 10%.
• a two-stage process for blending ingredients into a polymer is conventional, it is generally not practiced to produce a finished film in which more than 5 wt%, preferably more than 10 wt% and most preferably more than 20 wt% of inert particles, are mixed with VCI particles, all particles to be uniformly distributed in the thermo-formed polymer which not only maintains high tensile strength, at least 2000 psi, but is susbtantially transparent.
• a modified two-stage process comprises, in a first stage, (i) adding from 0 wt%, preferably from 20 wt% to 100% of all the essentially anhydrous inert filler particles, and all the VCI ingredients to be present in the finished film, to essentially anhydrous biopolymer and blending at a temperature below the melting point of the biopolymer, to make a biopolymer concentrate in which the concentration of dispersed particles is in the range from about 25 - 60 phr, preferably about 50 phr (parts per hundred of blended concentrate) for 50 phr of biopolymer, (ii) further dispersing the inert particles and VCI ingredients in the biopolymer while melting the polymer to form a molten concentrate, preferably in the barrel of an extruder, (iii) cooling the molten concentrate into a solidified mass of arbitrary shape, and (iv) comminuting the solidified mass to form granules smaller
• an injection-molded article of the novel biopolymer may not be critical, as it is in a "see-through” biofilm, the same two stage process may be used to prepare an injection-moldable or cast "filled" biopolymer.
• the aforementioned second stage process may be repeated on biopolymer (which has been formulated with filler and VCI ingredients, as previously described), in which the VCI ingredients have been depleted by long use.
• the biopolymer is recycled by simply adding the desired level of essentially anhydrous VCI ingredients to thoroughly dried VCI-depleted polymer.
• a shaped article comprises an essentially anhydrous aromatic-aliphatic copolyester having a tensile strength of at least 2000 psi at 23 °C in one direction, and a WVTR at atmospheric pressure (1 atm) at least about 5, preferably about 10 times higher than that of PE film, that is, greater than 10 x 0.5 g/m 2 /24 hr/mm (g water per sq.
• essentially anhydrous inert particulate filler in the size range from about 1 ⁇ m - 45 ⁇ m, wherein at least 75% of the particles are smaller than about 20 ⁇ m, more preferably from about 1 ⁇ m - 25 ⁇ m, wherein at least 75% of the particles are smaller than about 15 ⁇ m, and at least 1 percent by weight of a particulate, essentially anhydrous VCI ingredient having a primary particle size in the same aforestated size range as the filler, the filler and VCI both substantially uniformly dispersed in the polyester, the copolyester including the filler and VCI ingredient being essentially free of agglomerates greater than 50 ⁇ m and substantially transparent in a thickness of 0.05 mm.
• a finished filled thermoplastic biopolymer in which the inert filler is uniformly distributed is preferably made in a two-stage process, the first stage, comprising, (i) adding from 20 wt% to 100 wt% of essentially anhydrous inert filler particles, and all the VCI ingredients to be present in the finished film, to essentially anhydrous biopolymer. If the finished biopolymer is to have only 10 wt% of filler particles, then all or nearly all the particles may be added to the VCI ingredients and biopolymer to form a mixture.
• the last step may be carried out in an injection molding machine, a blow molding machine, a slit extruder or, if film having a thickness in the range from about 0.025 mm to about 0.25 mm is desired, the film may be blown. Thicker films are typically cast.
• the fully biodegradable polymer :
• the neat biopolymer is limited to those having a tensile strength high enough so that when the polymer is infused with at least a total of 6 wt% of micronized particles, the tensile strength at ambient temperature is at least 2000 psi.
• Preferred "hard” biopolymers such as are typically used for injection molding applications, include terpolymers based on polylactic acid, and other polylactic acid- based polymers, polyesteramides, polyglycolic acid, poly(lower C -C 5 alkylene carbonates, and modified polyethylene terephthalates, all commercially available from Bayer, Cargill-Dow Polymers, Dianippon Ink, Du Pont, Mitsui Chemicals, PAC Polymers, inter alia.
• Preferred hard injection-molding biopolymers include modified polyethylene terephthalate (PET) Biomax® biopolymers (DuPont) described in greater detail in U.S. Patents Nos. 5,053,482 and 5,097,005 to Tietz, U.S. Patents Nos. 5,097,004 5,171,308 and 5,219,646 to Gallagher et al., U.S. Patent No. 5,295,985 to Romesser et al.
• Such biopolymers typically consist essentially of alternating terephthalate and an aliphatic units derived from at least two diols.
• Biomax polymers have a m pt in the range from about 200 - 208°C and a Tg in the range from about 40 - 60°C.
• PLA polylactic acid
• Mn molecular weight range of Mn from about 50,000 to 110,000.
• Commercially available PLA has a m pt of about 180°C and a Tg of about 60°C.
• polyesteramides e.g. BAK 1095 (BASF) made by reacting adipic acid, 1,4-butanediol, and 6-aminocaproic acid and having a Mn of about 22,700 and a Mw of about 69,700, a m. pt. of 125°C; and BAK 2195 which has a m pt of 175°C; and a terpolymer of polylactide, polyglycolide and polycaprolactone produced by Mitsui Chemicals, Inc. using a condensation reaction, three of which are sold under the designations H100J, S100 and T100.
• the H100J has a Tg of about 74°C and a m pt of 173°C.
• Preferred "soft" biopolymers are aliphatic-aromatic copolyesters; aliphatic polyesters such as polyhydroxyvalerate, polyhydroxybutyrate-hydroxyvalerate copolymer and polycaprolactone; and succinate-based aliphatic polymers, e.g., polybutylene succinate. polybutylene succinate adipate, and polyethylene succinate, all of which are commercially available from manufacturers such as BASF, Daicel Chemical, Eastman Chemical, Monsanto, Showa High Polymer, Solvay, and Union Carbide. Most preferred aliphatic-aromatic copolyesters are disclosed in U.S. Pat. No.
• the biopolymer used for extruding or blowing film is Ecoflex® (BASF), believed to be formed by reaction of adipic acid, 1,4- butanediol and dimethyl-terephthalate (DMT), which biopolymer has a Tg of -33°C and a m pt in the range from about 105°C - 115°C.
• the thickness made and used is in the range from about 0.025 mm (1 mil) to 0.125 mm (5 mil), the thinner film being used to carry lighter loads than the thicker film, and also for faster decomposition, if the biopolymer is not to be recycled after the VCI is depleted.
• Eastar Bio® (Eastman) believed to be a random copolymer formed by reaction of the same ingredients as the Ecoflex and having essentially the same physical properties.
• Eastar Bio has a tensile strength at break in the machine direction of 19 MPa, an elongation at break of 600%, a tensile modulus of elasticity of 97 MPa (tangent), and an Elmendorf tear strength of 282 g.
• PCL polycaprolactone
• ⁇ - caprolactone formed by polymerizing ⁇ - caprolactone, the polymer having a relatively low melting point and a low glass transition temperature.
• the Tg of PCL is -60°C and the m pt is only 60°C. Because of this, PCL and other similar aliphatic polyesters with low melting points are difficult to process by conventional techniques such as film blowing and blow molding.
• Film made from PCL is tacky as extruded and has low melt strength near its m pt. Also, the slow crystallization of this polymer causes the properties to change over time. Blending PCL with the inert filler improves the processability of PCL and reduces tackiness.
• Commercially available PCLs are manufactured by Union Carbide (Tone®), Daicel Chemical, Ltd. and Solvay.
• Another "soft" aliphatic polyester that may be used are (i) polyhydroxybutyrate- hydroxyvalerate copolymer, made using a microbial-induced fermentation, e.g.
• Biopol® (Monsanto) which has a Tg of about 0°C and a m pt of about 170°C; and (ii) a polyhydroxy-alkanoate Metabolix®
• Still other "soft" aliphatic polyesters are based on repeating succinate units such as polybutylene succinate, polybutylene succinate adipate, and polyethylene succinate e. g. Bionolle® from Showa High Polymer, Ltd., which has a Tg of -30°C and a m pt of 114°C.
• the choice of the biopolymer depends upon the amount of filler particles to be added - the higher the wt% of filler particles, the higher the tensile strength required of the biopolymer chosen; typically, loadings of filler higher than 20 wt% yet meeting the requirement of a 200 psi tensile strength for filled biopolymer, requires choosing a biopolymer having a tensile strength greater than at least about 3000 psi in at least one direction.
• the particulate filler is a mixture of:
• inert filler particles function to increase the mean free path of water vapor through the filled polymer the particles may be either inorganic or organic particulate fillers, so long as they are environmentally friendly.
• inorganic fillers are preferred among which are silica, talc, calcium carbonate, titanium dioxide, pumice, and the like which are readily dried to essentially anhydrous conditions. Because of the high scattering of light at the aspect ratios of filler particles used herein, the refractive indices of the filler particles is not narrowly critical. The optimum amount to be used for a finished article having desired strength properties may be determined by a microstructural engineering approach, choosing an appropriate aspect ratio and specific surface area, and such amount will provide the desired higher WVTR relative to less filled polymer.
• Preferred particles have a surface area in a range from about 100 m 2 /g to 1000 m 2 /g, more preferably in range from about 300 m 2 /g to 800 m 2 /g, and most preferably in a range from about 500 m 2 /g to 600 m 2 /g.
• Most preferred are talc particles in the size range from about 0.5 - 25 ⁇ m, more than 50%) of which are in the range from 4 - 9 ⁇ m; and calcium carbonate particles in the size range from about 0.4 - 70 ⁇ m, more than 50%) of which are in the range from 5 - 20 ⁇ m, both ranges measured by Microtrac- X100.
• Preferred inorganic VCIs include alkali metal molybdates and alkali metal nitrites, most preferably sodium molybdate and sodium nitrite.
• Preferred organic VCIs include amine salts, ammonium benzoate, alkali dibasic acid salts, tall oil imidazolines, and triazole compounds, most preferably benzotriazole, sodium sebacate and dicyclohexylammonium nitrite. It will be appreciated that the size of particles of an organic VCI which melts under thermoforming conditions is immaterial, and that the VCI crystallizes in the biopolymer when cooled, and adds to the particle density in the biopolymer.
• the amount of the VCI ingredients used is chosen to be effective for a predetermined period, from 1 to 10 years for metal objects which might be stored a long time, but typically from 1 to 5 years. Even for the longer period, the amount of VCI dispersed in the biopolymer is less than 3 wt%, and for shorter periods, less than 1 wt%>.
• Example 1 Sodium silicate (7 parts), sodium nitrite (90 parts) and Cabosil® fumed silica (3 parts) are ground to a size range from about 1 - 45 ⁇ m (bell curve, Microtrac-XlOO), and thoroughly mixed into a powder blend. The powder blend is then dried at 250°C for 3 hr.
• the motor speed is about 150 rpm at 47%) torque exerting about 620 kPa (90 psia) generates a "noodle" which is cooled in a water bath, pelletized into pellets about 3.18 mm (0.125 in) and dried.
• Talc powder, mean diameter 2.2 ⁇ m, sp gr 2.8, in the aforestated size range, from Luzenac® is dried at 250°C for 3 hr and 20 parts by wt are thoroughly blended with dried Ecofiex® FBX 7011 (78 parts) and the pellets of masterbatch (2 parts) in a high-speed blender for 15 minutes. The blended mixture is then fed to the feed port of the Century extruder with the same screw configuration as before.
• the pellets melt in the range from 182°C (360°F) - 195.9°C (385°F). Die temperatures are set in the range from about 182°C (350°F) - 193.1°C (380°F); zone temperatures are set in the range from 201.4°C (395°F) - 212.6°C (415°F); speed is about 12 rpm and pressure exerted is in the range from 8.27 Mpa (1200 psia) - 11.02 Mpa (1600 psia); film is blown at about 5 ft/min. Production of the blown film commences at low rotation speed (screw speed) so that the raising of a flexible bubble is slow and uniform. If cooled internally, a minimum amount of air is used and tension at the film winder is set very low. Thickness of the blown film is in the range from 0.025 mm (1 mil) to 0.375 mm (1.5 mil).
• the tensile strength of neat blown Ecofiex film using ASTM D-882 testing procedure is in the range from about 32 - 36 N/mm 2 (4634 - 5213 psi).
• the tensile strength of blown film filled with both VCI and filler particles using the same ASTM D-882 testing procedure is in the range from about 13.8 - 20.7 N/mm 2 (2000 - 3000 psi), the more the filler and VCI particles, the lower the tensile strength.
• Example 2 In a manner analogous to that described in Examplel above, 90 Zinc oxide (54 parts), sodium silicate (25 parts) are ground to a size range from about 1 - 45 ⁇ m (bell curve, Microtrac-XlOO), and mixed, then Cobratec® 99 benzotriazole (10.5 parts), Naugard® 2,6 di-t-butyl-4-methyl phenol (10.5 parts) thoroughly mixed into the mixture.
• the zinc oxide particles function as filler particles they also have a beneficial effect on the corrosion-protection properties of the thermoformed biopolymer.
• the diluted biopolymer may be extruded through a slit die or blown into film using a procedure analogous to that described above in Example 1.
• This biopolymer is crosslinked using a free radical initiator, specifically 0.1 part of 2,5-bis(t-butylperoxy)-2,5-dimethylhexane (Luperox ® 101) in 100 parts of the biopolymer, in the Century extruder under conditions similar to those described in Example 1 above, and pelletized as described.
• the pellets are then mixed with the ingredients specified in Example 1 to make a powder blend which is then extruded and pelletized as a master batch which in turn is mixed with 78 parts of neat crosslinked polymer as before, and extruded and pelletized as before.
• the pellets are then dried to essentially anhydrous conditions and blown into film in a manner analogous to that described above.
• this crosslinked biopolymer Since the tensile strength of the crosslinked bioopolymer is higher than its uncrosslinked strength, this crosslinked biopolymer is preferred for higher strength requirements, and may be blown into film using a procedure analogous to that described above in Example 1.
• An extruder thoroughly mixes and disperses the inert particles and VCI ingredients and feeds molten polymer through a slot or flat die to form a thin molten sheet of film.
• This film is "pinned" to the surface of a chill roll which is typically chrome-plated and water-cooled, by a blast of air from an air knife or vacuum box. The film quenches immediately and then has its edges slit prior to winding.
• Example 5 Testing of film for Uniformity of Dispersion of the particles: A film of Eastar Bio GP biopolymer prepared with about 1 wt% of the VCI formulation set forth in Example 1 and filled with 20 wt% talc particles, about 90%) of which are in the size range from 1 - 15 ⁇ m was blown to a thickness of 0.025 mm and placed viewed against a ?? light. The distribution of particles over each unit area appears to be substantially the same to the naked eye.
• Films are prepared from "neat” low density Petrothene® NA 960 PE from Equistar having a melt index of about 1 g/10 min, and "neat” biofilms each film at least 0.025 mm (1 mil) thick; and filled films are made with the stated amount of filler.
• the amounts of particles in each film is given, the remaining being polymer; the designation "VCI” indicates that the film contained the stated about 1 wt% of the combination of VCI ingredients used in Example 1.
• Various samples tested below were locked over a test dish and measurements made according to ASTM E96-00 "Standard Test Methods for Water Vapor Transmission of Materials".
• the WVTR which is measured as (g of water / 100 in 2 / mil /day) is normalized to (g of water / meter 2 / mm / day).
• the experimental error for the method is estimated to be about 10%.
• a statistically significant number of measurements are made (five) and the average read.
• the results, normalized to (gm of water/m 2 /day/mm) are set forth below:
• the WVTR of Ecofiex with 1 wt%> VCI ingredients is only slightly higher than that for neat Ecofiex, but the WVTR of the Ecofiex filled with 29 wt% talc particles is about 14% higher.
• Corrosion is measured according to JEC 68-2-30 the requirements of which are incorporated by reference thereto as if fully set forth herein, using aggressive conditions for relative humidity in a Thermatron® as follows:
• Test specimens of 1010 carbon steel 25.4 mm x 44.4 mm (1" x 1.75") are subjected to repetitive 24 hour cycles over 10 days, cycling the conditions of exposure. Each cycle commenced at 25°C and 98% relative humidity with an initial period of 6 hours, after which the temperature setting was raised to 55°C and the relative humidity lowered to 93%>. After 3 hr the relative humidity and temperature are set as follows: (i) the relative humidity is lowered to 93%> and is maintained at this humidity for 6 hr; and (ii) the temperature is lowered to 25°C and remains at this temperature for the remaining 15 hr of the 24 hr cycle. After 6 hr, and 15 hr after the cycle commenced, the relative humidity is raised to its starting 98% level and maintained for the remaining 9 hr of the cycle.
• the samples are subjected to 10 cycles consecutively. In each case, the specimens are protected by film having a thickness of 0.05 mm (2 mil); six (6) carbon steel specimens are used, and the average number of corrosion spots read.

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