Classifications

• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/06—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
• • 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
  • C08L77/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
• • 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
  • C08L77/06—Polyamides derived from polyamines and polycarboxylic acids

Definitions

• the present invention relates to improved thermoplastic films. More particularly, this invention relates to flexible polyamide films.
• Thermoplastic polymers that possess a range of useful properties from stiffness and strength characteristics to abrasion and chemical resistances are well known to the art.
• these thermoplastic polymers are polyamides, and the class of polyamides which are generally referred to as nylons.
• nylons are semi-crystalline in structure, although chemically or thermally modified amorphous polyamides can be produced.
• Nylons providing useful physical properties have found utility in a broad range of applications, including the formation of molded articles, cast articles, blow molded articles, oriented and non-oriented films, sheet, rods, fibers, fabrics, and other.
• Thermoplastic compositions comprising nylons have found wide use in a film form for packaging in consumer and industrial applications due to their advantageous properties including chemical resistance, toughness, strength, low gas permeability (including oxygen) , and relatively high heat stability that can readily be further improved with an addition of traditional heat stabilizers, such as metal halides.
• a master batching process comprises preparing a well mixed additive composition by extruding not-readily- miscible additives, such as plasticizers, with a relatively small amount of the major constituent of the film forming composition utilizing a high shear mixing extruder or other mixing device. Subsequently, the resulting composition, which is called a "master batch” in the art, is mixed and extruded with the rest of the composition constituents to form the final homogeneous film composition.
• nylon film compositions with the above-mentioned good physical characteristics that form homogeneous compositions without having to utilize such extra processes as master batching process.
• polyamides are generally hygroscopic, that is, they have a tendency to absorb moisture from their environment. Moisture acts as a plasticizer in polyamides, reducing most mechanical and electrical properties while changing flexibility and elongation characteristics. It is widely believed that water molecules actually replace the amide-amide hydrogen bond in polyamides with an amide-water hydrogen bond.
• the hygroscopic nature of polyamides further complicates the task of selecting appropriate plasticizers since the flexibility of polyamide film varies significantly with the humidity level of the surrounding environment. Therefore, it is further desirous to provide a plasticizer that can reduce the moisture sensitivity of polyamide film.
• lactam monomers such as caprolactam and lauryl lactam
• lactam monomers are highly volatile at elevated temperatures, they may be volatilized during the film manufacturing process in the form of fumes and may accumulate at various cold spots in the manufacturing equipment or in the manufacturing facility. Therefore, it is additionally desirous to utilize a plasticizer that is not volatile.
• a flexible film comprising, based on the total weight of the composition, from about 50 to about 95 weight percent of a polyamide and about 5 to about 50 weight percent of a modified polyolefin having a functional moiety selected from the group consisting of unsaturated polycarboxylic acids and acid anhydrides, wherein the tensile modulus of such film is below about 85,000 psi (580 MPa) at 50 percent relative humidity.
• the modified polyolefin further comprises from about 3 to about 40 weight % of vinyl acetate.
• an improved nylon film having a generally homogeneous structure which film exhibits improvements in softness and film flexibility.
• the present invention provides flexible nylon films comprising from about 50 to about 95 weight %, more preferably about 60 to about 90 weight %, and most preferably about 65 to about 85 weight %, of a polyamide and, correspondingly, from about 5 to about 50 weight %, more preferably about 10 to about 40 weight %, and most preferably about 15 to about 35 weight %, based on the total weight of the composition, of a modified polyolefin having a functional moiety selected from the group consisting of unsaturated polycarboxylic acids and acid anhydrides, wherein the tensile modulus of the film is below about 85,000 psi (580 MPa) at 50% relative humidity.
• the modified polyolefin further comprises from about 3 to about 40 weight %, more preferably about 4 to about 30 weight %, and most preferably about 5 to about 25 weight %, based on the total weight of the modified olefin, of vinyl acetate.
• Polyamides commonly known as "nylons,” suitable for the present invention include those which may be obtained by the polymerization of a diamine having two or more carbon atoms between the amine terminal groups with a dicarboxylic acid, or alternately those obtained by the polymerization of a monoamino carboxylic acid or an internal lactam thereof with a diamine and a dicarboxylic acid. Further, suitable polyamides may be derived by the condensation of a monoaminocarboxylic acid or an internal lactam thereof having at least two carbon atoms between the amino and the carboxylic acid groups, as well as other means.
• Suitable diamines include those having the formula
• n preferably is an integer of 1 - 16, and includes such compounds as t rime thy 1 enediamine , tetramethylene diamine , p en tamethyl enediamine , hexamethyl enediamine, oc tamethyl enediamine, decamethylenediamine, dodecamethylenediamine, and hexade came thy 1 enediamine; aromatic diamines such as p- phenyl enediamine , m-xyl enediamine , 4,4'- diaminodiphenyl ether, 4 , 4 ' -diaminodiphenyl sulphone, 4,4'- diaminodiphenylmethane , alkylated diamines such as 2,2- dimethylpentamethylenediamine , 2 , 2 , 4 - t rimethylhexamethylenediamine , and 2,4,4- trimethylpentamethylenedi
• dicarboxylic acids useful in the formation of polyamides are preferably those which are represented by the general formula
• Z is representative of a divalent aliphatic radical containing at least 2 carbon atoms, such as adipic acid, sebacic acid, octadecanedioic acid, pimelic acid, subeic acid, azelaic acid, undecanedioic acid, and glutaric acid; 5 or a divalent aromatic radical, such as isophthalic acid and terephthalic acid.
• suitable polyamides include: polypropiolactam (nylon 3), polypyrrolidone (nylon 4), 10 polycaprolactam (nylon 6) , polyheptolactam (nylon 7) , polycaprylacta (nylon 8) , polynonanolactam (nylon 9) , polyundecaneolactam (nylon 11) , polydodecanolactam (nylon 12) , poly(tetramethylenediamine-co-adipic acid) (nylon 4,6), poly(tetramethylenediamine-co-isophthalic acid) 15 (nylon 4,1) , polyhexamethylenediamine adipamide polyhexa ethylene azelaiamide polyhexamethylene sebacamide polyhexamethylene isophthalamide
• nylon 612 poly(decamethy1enediamine-co-sebacic acid)
• nylon 1010 poly(dodecamethylenediamine- co-dodecanedioic acid)
• poly(bis[4-aminocyclohexyl]methane-co-dodecanedioic acid) POM-12
• POM-12 poly(bis[4-aminocyclohexyl]methane-co-dodecanedioic acid)
• such polyamide copolymers include: caprolactam- hexamethylene adipamide (nylon 6/6,6), hexamethylene
• nylon 6,6/6T trimethylene adipamide-hexamethylene- azelaiamide
• adipamide-hexamethylene-azelaiamide caprolactam (nylon 6,6/6,9/6) as well as others polyamide copolymers which are not particularly delineated here. Blends of two or more polyamides may also be employed.
• the preferred polyamides suitable for use in the present invention are polycaprolactam (nylon 6) , polyhexamethylene adipamide (nylon 6/6) , and copolymers and blends thereof.
• the caprolactam-based polyamides suitable for use in the present invention exhibit a number average molecular weight, which is determined by the formic acid viscosity method, of between about 10,000 and about 60,000; more preferably, the polyamides exhibit a number average molecular weight of between about 15,000 and about 45,000.
• a further constituent in the film of the present invention is a modified polyolefin.
• the modified polyolefin comprises from about 5 to about 50 weight %, more preferably about 10 to about 40 weight %, and most preferably about 15 to about 35 weight %, of the total weight of the film composition.
• the polyolefins which may be used to form the modified reaction product suitable for the present invention include crystalline or crystallizable poly( ⁇ .-olefins) and their copolymers, wherein the c.-olefin monomers have between about 2 and about 6 carbon atoms.
• suitable polyolefins include low, medium or high density polyethylene, linear low density polyethylene, polypropylene, polybutylene, polybutene-1, polypentene-l, poly-3-methylbutene-l, poly-4-methylpentene-l, polyhexene, and copolymers and blends thereof.
• preferred polyolefins are polyethylenes, polypropylene, polybutylene, and copolymers and blends thereof.
• the modified polyolefins suitable for use in conjunction with the present invention include copolymers and graft copolymers of a polyolefin and a constituent having a functional moiety selected from the group consisting of unsaturated polycarboxylic acids and acid anhydrides thereof.
• the unsaturated polycarboxylic acids and anhydrides include maleic acid, maleic anhydride, fumaric acid, crotonic acid, citraconic anhydride, itaconic anhydride and the like. Preferred of these are anhydrides, of which the most preferred is maleic anhydride.
• the preferred modified polyolefin comprises between about 0.001 and about 10 weight % of the functional moiety, based on the total weight of the modified polyolefin, having a functional moiety selected from the group consisting of unsaturated polycarboxylic acids and acid anhydrides thereof. More preferably, the functional moiety comprises between about 0.005 and about 5 weight %; most preferably, between about 0.01 and about 2 weight %.
• modified polyolefins suitable for the present invention can be produced in accordance with the processes known to the art, including but not limited to the processes -described in U.S. Patent Nos. 3,481,910; 3,480,580; 4,612,155 and 4,751,270.
• various methods for initiating the grafting polymerization process such as ⁇ -ray, X-ray or high-speed cathode ray irradiation processes, and a free radical initiator process.
• the reaction of the polyolefin with an unsaturated polycarboxylic acid or an anhydride in the presence of a free radical is the most widely used method of the grafting process.
• a free radical e.g., a peroxide
• the method of using peroxide is advantageous since no special equipment or device is required for initiating the graft polymerization reaction although the method suffers from non-specificity and less than optimal grafting efficiency.
• the peroxides employable include benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide and azo compounds, such as azo-bis (isobutyronitrile) .
• Graft polymerization reaction is generally performed by standard graft polymerization techniques known in the art, such as heating a mixture of a polyolefin, a monomer of the functional moiety and a radical initiator, after mixing those or in mixing procedure, to a temperature at which polyolefin becomes molten, under kneading of the mixture.
• graft polymerization techniques such as heating a mixture of a polyolefin, a monomer of the functional moiety and a radical initiator, after mixing those or in mixing procedure, to a temperature at which polyolefin becomes molten, under kneading of the mixture.
• the above-stated compounds are dissolved or suspended in an appropriate solvent to perform the graft polymerization reaction.
• the modified polyolefin of the present invention preferably further comprises between about 3 to about 40 weight %, based on the total weight of the modified polyolefin, of vinyl acetate. More preferably, the modified polyolefin comprises between about 4 and about 30 weight % of vinyl acetate; most preferably, between about 5 and about 25 weight %.
• the modified polyolefins suitable for use in the present invention may also contain at least one thermoplastic elastomer such as ethylene/propylene rubber, ethylene/l-butene rubber, butyl rubber, butadiene rubber, styrene/butadiene rubber, ethylene/butadiene rubber, isopropene rubber, isobutylene or the like.
• Preferred thermoplastic elastomers are ethylene/propylene rubber and isobutylene rubber.
• Such thermoplastic elastomers may also be modified with a constituent having a functional moiety selected from the group consisting of unsaturated polycarboxylic acids and acid anhydrides thereof in accordance with the method described above in conjunction with modified poly( ⁇ -olefin) .
• compositions of the present invention may also include one or more conventional additives which do not materially affect the physical properties of the films including: lubricants, heat stabilizers, coloring agents including dye and pigments, flame-retardants, fibrous and particulate fillers and reinforcing agents (both organic and inorganic) , nucleators, ultraviolet light stabilizers, as well as other additives.
• conventional additives may be incorporated into compositions at any suitable stage of the production process; typically such conventional additives are included in the mixing step and included in an extrudate.
• the film compositions of the present invention may contain one or more heat stabilizers which include Group I
• metal halides e.g., sodium, potassium, and lithium with cuprous halides, e.g., chloride, bromide, iodide; hindered phenols; hydroquinoines, and varieties of substituted members of those groups and combinations thereof.
• the film compositions of the present invention may further comprise a coloring agent, which agent may be a dye, pigment or other coloring agent or material which is useful in imparting a color modification to the noncolored nylon, and which are not found to have a detrimental effect on the film compositions, particularly subsequent to heat ageing.
• a coloring agent which agent may be a dye, pigment or other coloring agent or material which is useful in imparting a color modification to the noncolored nylon, and which are not found to have a detrimental effect on the film compositions, particularly subsequent to heat ageing.
• Useful coloring agents include those which are known to the art as suitable for coloring polyamide comprising compositions and generally include inorganic pigments, metal oxides, organic pigments, organic dyes, as well as other coloring agents and color concentrates known to the art.
• Blending or mixing of the constituents which comprise the film compositions may be accomplished by any effective means which will effect their uniform dispersion. All of the constituents may be mixed simultaneously or separately utilizing the mixing means well known in the art, such as a mixer or extruder.
• a common method is to melt-knead a previously dry-blended composition further in a heated extruder provided with a single-screw, or in the alternative, a plurality of screws, extrude the uniform composition into strands, and subsequently chop the extruded strands into pellets.
• the dry-blended composition is provided to a film forming apparatus which comprises a heated extruder having at least a single screw. The heated extruder melt-blends the film composition and forms a film therefrom. This method is generally to be preferred as it provides an overall reduction of process and handling steps necessary to form a useful film combination therefrom.
• the film compositions of the present invention may be formed into films by conventional methods using conventional film forming apparati.
• Conventional methods include the production of films by blown film techniques, by extruding the film through a film forming die and optionally casting the film, calendaring, and forming a film forming composition into a billet and subsequently skiving a film from the billet.
• a film forming composition is plasticized and melt blended in an extruder to form an extrudate, which extrudate is then heated and extruded through a film forming die and then transported to a casting roll.
• the film forming apparatus may be one which is referred to in the art as a "blown film” apparatus and includes a circular die head through which the plasticized film composition is forced and formed into a film “bubble", which is ultimately collapsed and formed into a film.
• the films may optionally be stretched or oriented in any direction if so desired.
• the film may be stretched in either the direction coincident with the direction of movement of the film being withdrawn from the casting roll, also referred to in the art as the "machine direction", or in a direction which is perpendicular to the machine direction, and referred to in the art as the "transverse direction", or in both the machine direction and the transverse direction, where the resulting film is considered to be "biaxially" oriented.
• the films formed by any of the above methods may be of any thickness desired and includes those which have thicknesses typically less than 20 mils (500 ⁇ m) .
• the films have a thickness in the range of about 0.1 mil (2.5 ⁇ m) and about 10 mils (250 ⁇ m) ; most preferably the films have a thickness of between about l mil (25 ⁇ m) and 5 mils (125 ⁇ m) . While such thicknesses are preferred as providing a readily flexible film, it is to be understood that other film thicknesses may be produced to satisfy a particular need and yet fall within the present invention's scope.
• the flexible and conforming properties of the film of the present ' invention may be characterized as having low tensile modulus, low yield strength, high yield elongation and high ultimate elongation. Particularly, low tensile modulus indicates flexibility of the film.
• the flexible film of the present invention preferably has tensile modulus below about 85,000 psi (580 MPa) at 50% relative humidity. Most preferably, the flexible film has tensile modulus below about 75,000 psi (510 MPa) at 50% relative humidity.
• the films of the present invention provide good retention of physical properties, such as flexibility, softness and conforming characteristics, and feature low embrittlement even when subjected to high heat for an extended duration.
• the films of the present invention do not have any significantly volatile constituents and are not as moisture sensitive as the flexible nylon films of the prior art.
• the film compositions of the present invention form non-phase separating homogeneous mixtures that do not require additional mixing steps or pre-blending processes, such as master batching, due to the high compatibility of the plasticizers of the present invention with polyamides.
• the flexible, soft and relatively heat-stable films of the present invention find particular utility in the formation of parts or articles, particularly composite parts and articles.
• the formation of the article requires that a "preform" of the article, which contains one or more layers of an organic or inorganic web that is impregnated with an at least partially uncured resin, is wrapped in a film, and the wrapped preform is then subjected to elevated temperatures for a period of time, usually in excess of one hour.
• the films of the present invention provide good flexibility which readily conforms to complicated or complex preform shapes, and further feature excellent retention of physical properties subsequent to the heat ageing conditions and pressure normally associated with vacuum bagging and vacuum forming operations.
• Examples 1-4 were formed from the constituents indicated in Table 1 by first dry-blending the constituents, and then supplying them to a single-screw extruder with a 24:1 length/diameter (L/D) ratio.
• This extruder comprised 4 heating zones which were maintained at 238°C for zone 1 and 260°C for zones 2 through 4.
• the pressure in the extruder was 800 psi (5.5 MPa).
• the extruder was operated to produce approximately 30 lbs/hour (13.6 kg/hour) of the composition; the screw rotational speed was approximately 25 rpm.
• the extrudate exiting the extruder was then force in to conventional film forming die head of the "coathanger" type, which had a die gap of 30 mils (750 ⁇ m) , and a width of 14 inches (35.6 cm) .
• the die head was maintained at a temperature of 260°C; the rate of film production was maintained at approximately 35 feet/min
• a control film was formed from 100% nylon 6 of about 70 FAV, as indicated in Table 1, following the film forming procedures and specifications of Example 1.
• An analytical analysis has shown that the product is comprised of about 68% ethylene, about 25% propylene, about 7% vinyl acetate and less than 1% maleic anhydride.
• a maleic anhydride graft modified ethylene vinyl acetate copolymer comprising about 18 % vinyl acetate, about 82% ethylene and less than 1% maleic anhydride, available from * Quantum Chemical Corp.
• a film composition comprising 85 weight % nylon 6 of about 125 FAV and 15 weight % Admer SF700 modified polyolefin was further modified by the addition of copper ion, in the form of a copper iodide, potassium chloride blend, to 120 ppm level for heat-stabilization.
• the composition was extruded as in Example 1 which was then formed into films by forming a bubble of film. The bubble was then drawn in the direction of extrusion while maintaining an internal bubble pressure sufficient to keep the bubble in a substantially cylindrical shape with the wall thickness of approximately 2 mils (50 ⁇ m) .
• Example 5 The pre ⁇ heat aged and heat aged physical properties of the resulting film (Example 5) were compared with the properties of a nylon 6 film containing a relatively high level of caprolactam monomer that is commercially available to the vacuum bagging industry (Comparative Example Cl) .
• Comparative Example Cl contains about 5 ⁇ aprolactam, compared to only about 0.6% of Example 5.
• he pre-heat aged films were conditioned in a 50% relative humidity chamber at room temperature for at least 24 hours, and the heat aged films were prepared and conditioned by placing the films in an air circulating oven maintained at a temperature of 350°F (177°C) and a relative humidity of 50% for 4 hours.
• the physical properties were evaluated in accordance with the ASTM D882-83 test protocols. The results are shown in Table 3.
• Example 5 and Comparative Example Cl pre-heat aged specimens of Example 5 and Comparative Example Cl were tested for their physical characteristics at different humidity environments.
• a number of samples were placed in a desiccator, in a 50% relative humidity chamber and in a water bath for at least 24 hours at room temperature to obtain 0%, 50% and 100% relative humidity samples, respectively.
• the samples were tested in accordance with the ASTM D882-83 test protocols. The results are shown in Table 4.
• the film produced from the composition of the present invention provides measurably decreased tensile modulus at all humidity levels, indicating " improved flexibility over the film of the prior art.
• the ultimate elongation and ultimate strength properties of the film of the present invention are not as sensitive to humidity as the films of the prior art, indicating that, unlike the films of the prior art, the films of the present invention provide much more consistent and predictable properties of flexibility and softness at all varying levels of humidity.
• the films and the film compositions of the present invention provide improved flexible, soft films that have relatively high heat stability and low moisture sensitivity.
• the film compositions of the present invention do not contain any significantly volatile constituents and can easily be processed to form uniform films due to their non- separating homogeneous blending characteristic.

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• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)

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• 1992
  • 1992-06-09 WO PCT/US1992/004807 patent/WO1993000404A1/en not_active Application Discontinuation
  • 1992-06-09 JP JP5501245A patent/JPH06508649A/ja active Pending
  • 1992-06-09 CA CA002111830A patent/CA2111830C/en not_active Expired - Fee Related
  • 1992-06-09 EP EP92913697A patent/EP0591357A1/de not_active Withdrawn

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