Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • 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
  • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
  • C08J2377/02—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
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
  • C08J2377/06—Polyamides derived from polyamines and polycarboxylic acids

Definitions

• the present invention relates to polyamide-containing films produced by bubble formation of compositions which are useful, for example, as carrier webs in the production of composite materials.
• SMC is generally comprised of crosslinkable polymeric resin, particularly unsaturated polyester, styrene monomer (a cross-Unking agent), particulate filler, and chopped fiber reinforcement, as weU as various other additives in minor amounts.
• This composite material is usually prepared by depositing the chopped fiber on a layer of fluid resin supported on a moving polyamide film and then placing another layer of polyamide film (onto which another layer of fluid resin may have been deposited) on top to form a sandwiched composite which is passed through a series of kneading and compaction roUs and is usually wound into large roUs or festooned for storage.
• the SMC is used to produce molded parts for automobiles, boats, etc., by cutting a piece of appropriate size from the roU (or other structure), peeling away the polyamide carrier film(s), and placing the SMC in a heated mold for simultaneous molding and complete curing.
• SMC sandwich composites are used in compression molding procedures, and particularly in matched die molding operations.
• a similar material, thick molding compound (TMC) is prepared by a similar process and is used mostly in injection molding appUcations.
• Polyamide-containing films are useful in the production of SMC and TMC because polyamide is relatively impermeable to styrene monomer and provides good strength.
• the present invention which responds to the aforedescribed problem facing the film production industry of the inabiUty to blow extrude films wherein the polyamide has a relatively low molecular weight (for nylon 6, a formic acid viscosity of less than about 120), provides a composition of polyamide with a minimal amount of a polyolefin having reactive groups which maintain the strength of the bubble during blown film extrusion.
• the present invention provides a film produced by forming a bubble from a composition comprising: (a) up to about 99.9 weight percent based on the total weight of the composition of a polyamide; and (b) at least about 0.1 weight percent based on the total weight of the composition of a polyolefin having functional groups which are reactive with the functional groups of the polyamide wherein the functional groups of the polyolefin are present in an amount sufficient to maintain the strength of the bubble.
• the present invention also provides a film produced by forming a bubble from a composition
• a composition comprising: (a) up to about 99.9 weight percent based on the total weight of the composition of a polyamide; (b) at least about 0.1 weight percent based on the total weight of the composition of a polyolefin having functional groups which are reactive with the functional groups of the polyamide wherein the functional groups of the polyolefin are present in an amount of at least about 0.01 weight percent based on the total weight of the polyolefin, preferably from about 0.01 to about 10 weight percent based on the total weight of said polyolefin; and (c) about 5 to about 50 weight percent based on the total weight of the composition of an unfunctionalized polyolefin.
• the present invention also provides a process of forming a polyamide-contai ing film produced from a bubble.
• the improvement comprises forming the bubble from a composition comprising: (a) up to about 99.9 weight percent based on the total weight of the composition of a polyamide; and (b) at least about 0.1 weight percent based on the total weight of the composition of a polyolefin having functional groups which are reactive with the functional groups of the polyamide, wherein the functional groups of the polyolefin are present in an amount sufficient to maintain the strength of the bubble.
• the film of this invention comprises a polyamide and a functionalized polyolefin, preferably also comprising an unfunctionalized polyolefin.
• Polyamides useful in the present invention are characterized by the presence of recurring carbonamide groups as an integral part of the polymer chain which are separated from one another by at least two carbon atoms, fllustrative of these polyamides are those having recurring monomeric units represented by the general formula:
• the polyamides of the present invention have relatively low molecular weights.
• the formic acid viscosity (FAV) of the polyamide is preferably from about 50 to about 120 (as measured by ASTM D-789). In this method, a solution of 11 grams of polyamide in 100 ml of 90% formic acid at 25°C is used.
• poly(tetramethylene adipamide) (nylon 4,6); poly(hexamethylene adipamide) (nylon 6,6); polyhexamethylene azelaiamide (nylon 6,9); poly(hexamethylene sebacamide) (nylon 6,10); polyhexamethylene isophthaUmide (nylon 6,1); polyhexamethylene terephthalimide (nylon 6,T); poly(heptamethylene pimelamide) (nylon 7,7); poly(octamethylene suberamide) (nylon 8,8); poly(nonamethylene azelamide) (nylon 9,9); poly(decamethylene azelamide) (nylon 10,9); and the Uke.
• poly(tetramethylene adipamide) (nylon 4,6); poly(hexamethylene adipamide) (nylon 6,6); polyhexamethylene azelaiamide (nylon 6,9); poly(hexamethylene sebacamide) (nylon 6,10); polyhexamethylene isophthaU
• useful polyamides are those formed by polymerization of amino acids and derivatives thereof, as for example lactams.
• IUustrative of these useful polyamides are poly(4-aminobutyric acid) (nylon 4); poly(6- aminohexanoic acid), also known as poly(caprolactam) (nylon 6); poly(7- aminoheptanoic acid) (nylon 7); poly(8-aminooctanoic acid)(nylon 8); poly(9-aminononanoic acid) (nylon 9); poly(10-aminodecanoic acid) (nylon 10); poly(l l-aminoundecanoic acid) (nylon 11); poly(12- aminododecanoic acid) (nylon 12); and the Uke. Blends of two or more polyamides may also be employed.
• polyamides that can be utilized are those resulting from adipic acid and meta-xylylene diamines (nylon MXDA); adipic acid, azelaic acid and 2,2-bis-(p-aminocyclohexyl)propane; terephthaUc acid and 4,4'-diamino-dicyclohexylmethane; and the like.
• Copolymers formed from recurring units of the above referenced polyamides may also be used.
• such polyamide copolymers include caprolactam/hexamethylene adipamide copolymer (nylon 6/6,6); hexamethylene adipamide/caprolactam copolymer (nylon 6,6/6); trimethylene adipamide/hexamethylene azelaiamide copolymer (nylon trimethyl 6,2/6,2); hexamethylene adipamide/ hexamethylene-azelaiamide/ caprolactam copolymer (nylon 6,6/6,9/6); and the like.
• Preferred polyamides for use in the practice of this invention are poly(caprolactam) (nylon 6) and poly(hexamethylene adipamide) (nylon 6,6), and blends and copolymers thereof.
• the most preferred polyamide is poly(caprolactam).
• Polyamides useful in the practice of this invention may be obtained from commercial sources or prepared in accordance with known preparatory techniques.
• the polyamides of this invention have relatively low molecular weight.
• the FAV of the polyamides ranges from about 20 to about 120, preferably from about 50 to about 120. This corresponds to a number average molecular weight of about 10,000 to about 35,000. Preferably, the molecular weight ranges from about 20,000 to about 30,000.
• the polyamide is present in an amount preferably of up to about 99.9 weight percent based on the total weight of the composition, more preferably about 50 to about 99.9 weight percent based on the total weight of the composition, and most preferably about 75 to about 99.9 weight percent based on the total weight of the composition.
• the polyolefins used herein include polymers of alpha-olefin monomers having between about 2 and about 6 carbon atoms and includes homopolymers, copolymers (including graft copolymers), and terpolymers of alpha-olefins.
• IUustrative homopolymer examples include low, linear low, medium, or high density polyethylene; polypropylene; polybutylene; polybutene-1; poly-3-methylbutene-l; poly-pentene-1; poly-4-methylpentene-l; polyisobutylene; and polyhexene.
• IUustrative copolymer and terpolymer examples include copolymers and terpolymers of alpha-olefins with other olefins such as ethylene-propylene copolymers; ethylene-butene copolymers; ethylene-pentene copolymers; ethylene-hexene copolymers; and ethylene-propylene-diene copolymers (EPDM).
• polyolefin as used herein also includes acrylonitrile- butadiene-styrene (ABS) polymers.
• Preferred polyolefins are those prepared from alpha-olefins, most preferably ethylene polymers, copolymers, and terpolymers.
• the above polyolefins may be obtained by any known process.
• the polyolefin may have a molecular weight of about 1,000 to about 1,000,000, and preferably about 10,000 to about 500,000.
• Preferred polyolefins are polyethylene, polypropylene, polybutylene, and copolymers, and blends thereof.
• the polyolefins having functional groups useful herein are polyolefins which have functional groups which are reactive with the functional groups of the polyamide (which are amine and/or carboxyUc acid). Any functional group which wiU react with the fimctional groups of the polyamide may be used in the present invention.
• Preferred functional groups are selected from the group consisting of unsaturated polycarboxyUc acids and acid anhydrides thereof.
• the unsaturated polycarboxyUc acids and anhydrides include maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, and mixtures thereof.
• the more preferred functional group is anhydride and the most preferred functional group is maleic anhydride.
• the functional group may be suppUed by reacting the polyolefin with the functional group.
• the functional group may be grafted to the polyolefin by any known grafting process. Alternatively, the reactive moiety may be copolymerized into the backbone of the polyolefin.
• the polyolefin may include one or more types of functional groups.
• polyolefins having functional groups which are reactive with polyamide are preferably employed in the composition of this invention.
• the polyolefin having functional groups suitable for the present invention may also be produced in accordance with known processes, including but not limited to the processes described in U.S. Patents 3,481,910; 3,480,580; 4,612,155; and 4,751,270.
• various methods have been utilized 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 polycarboxyUc 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.
• the peroxides employable include benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide and azo compounds, such as azo-bis (isobutyronitrile).
• U.S. Patent No. 4,612,155 discloses a grafting process employing such a radical initiator that obtains the grafting yield of 50-90% under favorable circumstances.
• U.S. Patent No. 4,751,270 discloses more specialized radical initiators that attain up to 100% grafting efficiency and improve grafting specificity of the functional moiety to polyolefins.
• Graft polymerization reaction is generaUy performed by standard graft polymerization techniques known in the art, such as heating a mixture of a polyolefin, a monomer of the functional group, and a radical initiator, after mixing those or in mixing procedure, to a temperature at which the 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 polyolefin having functional groups is present in an amount preferably of at least about 0.1 weight percent based on the total weight of the composition, more preferably about 0.1 to about 10 weight percent based on the total weight of the composition, and most preferably about 0.1 to about 1 weight percent based on the total weight of the composition.
• the functional groups of the polyolefin are present in an amount preferably of about 0.01 to about 10 weight percent based on the total weight of the polyolefin, more preferably about 0.1 to about 5 weight percent based on the total weight of the polyolefin, and most preferably about 0.2 to about 1 weight percent based on the total weight of the polyolefin.
• the functional groups of the polyolefin react with the functional groups on the polyamide.
• the anhydride or acids groups of the polyolefin react with the amine groups on the polymeric chain ends of the polyamide. These reactions graft the polyamide to the polyolefin. It is beUeved that these reactions contribute to the bubble strength.
• esters on the polyolefin undergo minimal or no reaction with amine groups on the polymeric chain ends of the polyamide. It is believed that this explains why a bubble did not form when an attempt was made to blow extrude film from a blend of ethylene-vinyl acetate copolymer and polyamide 6.
• compositions such as the blends of: polycarbonamide and ethylene- methyl acrylate copolymer taught by U.S. Patent 3,472,916 and polyamide and ethylene-methylacrylate-methacryUc acid taught by U.S. Patent 4,174,358 would not form a bubble.
• the present invention further comprises unfunctionaUzed polyolefin.
• the unfunctionaUzed polyolefins include those mentioned above which do not have the aforementioned functional groups attached thereto. These include polymers of alpha-olefin monomers having between about 2 and about 6 carbon atoms and includes homopolymers, copolymers (including graft copolymers), and terpolymers of alpha-olefins and unlike the above-described polyolefin having functional groups, the polyolefin does not have functional groups, i.e.. is unfunctionaUzed.
• Illustrative homopolymer examples include low, linear low, medium, or high density polyethylene; polypropylene; polybutylene; polybutene-1 ; poly-3-methylbutene-l; poly-pentene-1; poly-4-methylpentene-l; polyisobutylene; and polyhexene.
• Illustrative copolymer and terpolymer examples include copolymers and terpolymers of alpha-olefins with other olefins such as ethylene-propylene copolymers; ethylene-butene copolymers; ethylene-pentene copolymers; ethylene-hexene copolymers; and ethylene-propylene-diene copolymers (EPDM).
• the above polyolefins may be obtained by any known process.
• the polyolefin component may have a molecular weight of about 1,000 to about 1,000,000, and preferably about 10,000 to about 500,000.
• Preferred polyolefins are polyethylene, polypropylene, polybutylene, and copolymers, and blends thereof.
• the unfunctionaUzed polyolefin provides good release properties when the present film is used in the production of sandwich composites of SMC, TMC or other composite material, and are generaUy less expensive than the functionalized polyolefins.
• the unfunctionaUzed polyolefin is present in an amount preferably of about 5 to about 50 weight percent based on the total weight of the composition, more preferably about 5 to about 40 weight percent based on the total weight of the composition, and most preferably about 5 to about 25 weight percent based on the total weight of the composition.
• the film of the present invention may be prepared by thoroughly blending together the polyamide, polyolefin having functional groups, and unfunctionaUzed polyolefin if used, and optionaUy various minor amounts of conventionaUy used additives such as pigments, heat stabilizers, antistatic agents, and the like.
• a pigment is used so that it can eastiy be determined that aU of the release film has been removed from the composite material.
• the film of this invention is formed by a bubble formation process.
• the film forming apparatus may be one which is referred to in the art as a "blown film” apparatus and includes an annular die head for bubble blown film through which the plasticized film composition is forced and formed into a film "bubble", which is ultimately collapsed and formed into a film.
• the film of this invention may be of any thickness desired and includes those which have thicknesses typicaUy less than about 16 mils (400 ⁇ m).
• the film has a thickness of from about 0.2 ⁇ ul (5 ⁇ m) to about 10 mils (250 ⁇ m); more preferably the film has a thickness of from about 0.4 mil (10 ⁇ m) to about 5 mils (130 ⁇ m), and most preferably the film has a thickness of from about 0.5 mil (12.5 ⁇ m) to about 2 mils (50 ⁇ m). While such thicknesses are preferred as providing a readUy flexible film, it is to be understood that other film thicknesses may be produced to satisfy a particular need and yet faU within the present invention's scope.
• the films of this invention may optionaUy be stretched or oriented in any direction if so desired using methods known to those of skiU in the art.
• the film may be stretched in either the direction coincident with the direction of movement of the blown film, 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” where the resulting film is “uniaxiaUy” oriented, or in both the machine direction and the transverse direction, where the resulting film is "biaxiaUy” oriented.
• Such biaxiaUy orientation may be simultaneous or sequential.
• the film typicaUy is drawn by passing it over a series of preheating and heating roUs.
• the heated film moves a set of nip roUs downstream at a faster rate than the film entering the nip roUs at an upstream location.
• the change of rate is compensated for by stretching in the film.
• Typical process and range of conditions for monoaxiaUy oriented polyamide films are disclosed, for example, in U.S. Patent No. 4,362,385.
• the carrier film should also exhibit a peel adhesion or peelabiUty such that the film peels off easily from the composite material prior to molding with very little, if any, of the film adhered to the compound.
• the films of this invention offer a range of release properties suitable for use in various release film applications.
• the films are particularly applicable for the production of prepreg material forms and in the production of SMC, TMC as weU as bulk molding compound (BMC).
• BMC bulk molding compound
• the films are also particularly apphcable as a carrier web for the production of fiber reinforced panels (FRP). In each of these processes, a carrier film is used in the production procedure.
• FRP fiber reinforced panels
• the process for the production of SMC generaUy comprises casting a layer of heat-curable thermosetting resin, in fluid form, onto a continuously advancing film of the present invention; introducing reinforcing material onto the advancing fluid layer; contacting another layer of film (onto which there may have been deposited a layer of thermosetting resin) to the top surface of the reinforced fluid layer thereby forming a sandwiched composite; advancing the sandwiched composite through a series of kneading and compacting roUs; and winding or festooning the sandwiched composite for maturation.
• the process for the production of TMC generaUy comprises impregnating discontinuous reinforcing fiber, i.e. desired lengths of chopped fiber, with resin paste; applying the impregnated fiber/resin composition to a moving carrier release film of the present invention; then applying a second release film of the present invention to sandwich the composition; then moving the sandwiched composition through a compaction area, thereby compacting the composition to form a sheet, generaUy much thicker then SMC; and then cutting the TMC sheet into desired lengths for packing.
• a process describing the production of TMC utilizing release films is disclosed, for example, in U.S. Patent 3,932,980. It can be seen that by this invention, it is possible to provide a blown film from relatively lower molecular weight polyamides. Such film retains the desirable physical properties mentioned earher, and is particularly useful as carrier webs in the production of SMC, TMC and similar composite materials.
• a blend comprising 90% nylon 6 (71 FAV) and 10% ethylene vinyl acetate copolymer was extruded on a single screw extruder with a Maddox mixing head screw on a blown film extrusion line.
• the barrel and die temperatures were between 450 to 500°F (232-260°C); the die gap was between 0.020 and 0.040 inches. Film could not be successfuUy produced from this blend because a bubble could not be estabUshed.
• blends of nylon 6 (70 FAV) and 10 to 20 weight percent of an unmodified polyolefin could not be used to produce film by the blown film process, again because a bubble could not be estabUshed.
• a blend of nylon 6 (130 FAV) and 20 weight percent of the same polyolefin copolymer likewise could not be used to produce film by this method because a bubble could not be estabUshed.
• Good bubble stabiUty was Jachied / for bubbles at blow up ratios from 1.6 to 2.3, with film thicknesses of 0.0005 to 0.002 inch.
• Comparative Example 2 was a film formed from a composition of 90 weight percent nylon 6 (135 FAV) and 10 weight percent of ethylene- vinyl acetate copolymer. The film was formed by blown film extrusion.
• Example 2 was a composition of 94 weight percent nylon 6 (85 FAV), 1 weight percent of maleic anhydride modified linear low density poly(ethylene-butene) copolymer (0.3 weight percent maleic anhydride, density of 0.904, melt index of 3.0), and 5 weight percent unmodified linear low density poly(ethylene-butene) copolymer (density of 0.900, melt index of 5.0).
• the film was formed by blown film extrusion as above.
• Example 3 was a composition of 90 weight percent of the nylon 6 of Example 2, 1 weight percent of maleic anhydride modified polyolefin of Example 2, and 9 weight percent of the unmodified polyolefin of Example 2.
• the film was formed by blown film extrusion as above. The films were tested and had the foUowing properties.
• COF means coefficient of friction. Where two values are indicated, the first value is in the machine direction and the second value is in the transverse direction:
• the release properties of the present film were determined to be as good as the release properties of the comparative film.
• the styrene impermeabiUty and strength were also as good as the comparative film.

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• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Shaping By String And By Release Of Stress In Plastics And The Like (AREA)

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• 1994
  • 1994-11-29 CA CA 2176576 patent/CA2176576A1/en not_active Abandoned
  • 1994-11-29 EP EP95902703A patent/EP0731821A1/en not_active Withdrawn
  • 1994-11-29 JP JP51570295A patent/JP3467745B2/ja not_active Expired - Fee Related
  • 1994-11-29 WO PCT/US1994/013657 patent/WO1995015354A1/en not_active Application Discontinuation

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