WO1991018051A1 - Melanges de polyoxymethylene thermostables - Google Patents

Melanges de polyoxymethylene thermostables Download PDF

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Publication number
WO1991018051A1
WO1991018051A1 PCT/US1991/002841 US9102841W WO9118051A1 WO 1991018051 A1 WO1991018051 A1 WO 1991018051A1 US 9102841 W US9102841 W US 9102841W WO 9118051 A1 WO9118051 A1 WO 9118051A1
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blend
polymer
stabilizer
polyoxymethylene
meltable
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PCT/US1991/002841
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English (en)
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Ken-Ichi Shinohara
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E.I. Du Pont De Nemours And Company
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Publication of WO1991018051A1 publication Critical patent/WO1991018051A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L59/00—Compositions of polyacetals; Compositions of derivatives of polyacetals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/08—Copolymers of ethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
    • C08L25/02—Homopolymers or copolymers of hydrocarbons
    • C08L25/04—Homopolymers or copolymers of styrene
    • C08L25/08—Copolymers of styrene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L29/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
    • C08L29/02—Homopolymers or copolymers of unsaturated alcohols
    • C08L29/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; 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
    • C08L35/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical, and containing at least one other carboxyl radical in the molecule, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L35/02—Homopolymers or copolymers of esters
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L55/00—Compositions of homopolymers or copolymers, obtained by polymerisation reactions only involving carbon-to-carbon unsaturated bonds, not provided for in groups C08L23/00 - C08L53/00
    • C08L55/02—ABS [Acrylonitrile-Butadiene-Styrene] polymers
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L69/00—Compositions of polycarbonates; Compositions of derivatives of polycarbonates
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L71/00—Compositions of polyethers obtained by reactions forming an ether 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
    • C08L75/00—Compositions of polyureas or polyurethanes; Compositions of derivatives of such polymers
    • C08L75/04—Polyurethanes
    • 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
    • C08L81/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen or carbon only; Compositions of polysulfones; Compositions of derivatives of such polymers
    • C08L81/06—Polysulfones; Polyethersulfones

Definitions

  • This invention relates to certain polyoxymethylene blends comprised of a
  • polyoxymethylene component a thermoplastic elastomer component
  • an amorphous thermoplastic polymer component that are stabilized with a certain polymer stabilizer that is non-meltable and that contains formaldehyde reactive nitrogen groups.
  • the blends stabilized with the polymer stabilizer described herein are characterized as having excellent melt processing stability and a good overall balance of physical properties.
  • Polyoxymethylene compositions are generally understood to include compositions based on homopolymers of formaldehyde or of cyclic oligomers of formaldehyde, for example trioxane, the terminal groups of which are end-capped by esterification or etherification, as well as copolymers of formaldehyde or of cyclic oligomers of formaldehyde, with
  • compositions based on POM of relatively high molecular weight, i.e., 20,000 to 100,000 are useful in preparing semi-finished and finished articles by any of the techniques commonly used with thermoplastic materials, e.g., compression molding, injection molding, extrusion, blow molding, melt spinning. stamping and thermoforming. Finished products made from such polyoxymethylene compositions possess
  • thermoplastic polyurethanes have been recently
  • compositions possess extraordinary toughness and/or impact resistance, along with also possessing a good overall balance of physical
  • compositions could be significantly reduced by
  • polyurethane composition with at least one amorphous thermoplastic polymer.
  • a polymer stabilizer that is non-meltable has a number average particle size in the blend of 10 microns or less, and that contains formaldehyde reactive nitrogen groups, as described in.further detail below, not only was effective as a melt processing stabilizer for the blends but also that it Imparted superior melt
  • polyoxymethylene/thermoplastic polyurethane/amorphous thermoplastic polymer blends to a significantly greater degree than did the more conventional
  • polyoxymethylene stabilizers was not only unexpected but was also quite surprising.
  • polyoxymethylene/thermoplastic polyurethane/amorphous thermoplastic polymer blend was a mixture of the polymer stabilizer, as described below, and a
  • co-stabilizer selected from conventional meltable nylon (or polyamide) based stabilizers, meltable hydroxy containing oligomers or polymers, such as ethylene vinyl alcohol, or microcrystalline cellulose.
  • melt processing stability of the blends containing such a mixed stabilizer system was better than the melt processing stability of the same blend containing only the polymer stabilizer, described below, or the co-stabilizer.
  • the polyoxymethylene blends of the present invention are useful as injection molding resins in applications where the properties of a
  • polyoxymethylene or polyoxymethylene/thermoplastic polyurethane composition are desired and where
  • polyoxymethylene compositions stabilized with examples of nylon-type stabilizers are disclosed in U.S. patent 4,640,949; U.S. patent 3,960,984; and U.S. patent 4,098,843.
  • U.S. patent 4,640,949 polyoxymethylene compositions are stabilized with a blend comprised of a thermoplastic polyurethane with a polyamide dispersed therein as a separate phase.
  • U.S. patent 3,960,984 polyoxymethylene compositions are stabilized with dicapped amide oligomers having a molecular weight of 800 to 10,000.
  • polyoxymethylene compositions are examples of nylon-type stabilizers.
  • polyoxymethylene are also described in Alsup et al., U.S. patent 2,993,025.
  • Hydroxy-containing polymers and oligomers useful as stabilizers in polyoxymethylene are
  • melt processing stability of a polyoxymethylene/thermoplastic polyurethane/amorphous thermoplastic polymer blend could be significantly improved by the incorporation therein of 0.05 to 3.0 weight percent, based upon the weight of the blend, of a polymer stabilizer that is non-meltable, has a number average particle size in the blend of less than ten microns, and contains formaldehyde reactive nitrogen groups wherein the amount of formaldehyde reactive nitrogen groups present as or part of the side chains of the backbone of the polymer stabilizer is at least three times greater than the amount of formaldehyde reactive nitrogen groups, if any, present in the backbone of the polymer stabilizer.
  • the melt processing stability of said blends is improved even further by the incorporation therein of a 0.01 to 1.00 weight percent, based upon the weight of the blend, of a co-stabilizer, said co-stabilizer being selected from meltable polyamide-based stabilizers, meltable hydroxy-containing polymer or oligomer stabilizers, and microcrystalline cellulose.
  • a co-stabilizer being selected from meltable polyamide-based stabilizers, meltable hydroxy-containing polymer or oligomer stabilizers, and microcrystalline cellulose.
  • the stabilized blends are useful as injection molding resins where the properties of a polyoxymethylene are desired and where enhanced thermal stability is required.
  • This invention relates to certain polyoxymethylene blends characterized by improved melt processing stability. Specifically, the
  • polyoxymethylene blends consist essentially of (a) a polyoxymethylene component, (b) a thermoplastic polyurethane component, (c) an amorphous thermoplastic polymer component, and (d) a polymer stabilizer component.
  • the melt processing stability of said blends is even further improved by the inclusion therein of a specific co-stabilizer component (e).
  • the co-stabilizer component (e) is selected from conventional meltable nylon-based stabilizers,
  • meltable hydroxy-containing polymer and oligomer stabilizers meltable hydroxy-containing polymer and oligomer stabilizers, and microcrystalline cellulose
  • polyoxymethylene includes homopolymers of formaldehyde or of cyclic oligomers of formaldehyde, the terminal groups of which are end-capped by esterification or
  • the polyoxymethylenes used in the blends of the present invention can be branched or linear and will generally have a number average molecular weight in the range of 10,000 to 100,000, preferably 20,000 to 90,000, and more preferably 25,000 to 70,000.
  • the molecular weight can be conveniently measured by gel permeation chromatography in jn-cresol at 160oC using a Du Pont PSM bimodal column kit with nominal pore size of 60 and 1000 A.
  • polyoxymethylenes having higher or lower molecular weight averages can be used, depending on the physical and processing properties desired, the polyoxymethylene molecular weight
  • polyoxymethylene blend with the most desired combination of physical properties in the molded articles made from such blends.
  • polyoxymethylenes which are suitable for use in the blends of the present invention will have a melt flow rate (measured according to ASTM-D-1238, Procedure A, Condition G with a 1.0 mm (0.0413 inch) diameter orifice of 0.1-40 grams/10 minutes.
  • melt flow rate of the polyoxymethylene used in the blends of the present invention will be from 0.5-35 grams/10 minutes.
  • the most preferred polyoxymethylenes are linear polyoxymethylenes with a melt flow rate of about 1-20 gram/10 minutes.
  • the polyoxymethylene can be either a homopolymer, a copolymer, or a mixture thereof.
  • Copolymers can contain one or more
  • comonomers such as those generally used in preparing polyoxymethylene compositions.
  • Comonomers more commonly used include alkylene oxides of 2-12 carbon atoms and their cyclic addition products with
  • polyoxymethylene homopolymer is preferred over copolymer because of its greater stiffness and strength.
  • Preferred polyoxymethylene homopolymers include those whose terminal hydroxyl groups have been end-capped by a chemical reaction to form ester or ether groups, preferably acetate or methoxy groups, respectively.
  • polyoxymethylene may also contain those additives, ingredients, and modifiers that are known to be added to
  • polyurethanes suited for use in the blends of the present invention can be selected from those
  • Thermoplastic polyurethanes are derived from the reaction of polyester or
  • Thermoplastic polyurethanes are generally composed of soft segments, for example polyether or polyester polyols, and hard segments, usually derived from the reaction of the low molecular weight diols and diisocyanates. While a thermoplastic polyurethane with no hard segments can be used, those most useful will contain both soft and hard segments.
  • a polymeric soft segment material having at least about 500 and preferably from about 550 to about 5,000 and most preferably from about 1,000 to about 3,000, such as a dihydric polyester or a polyalkylene ether diol, is reacted with an organic diisocyanate in a ratio such that a substantially linear polyurethane polymer results, although some branching can be present.
  • a diol chain extender having a molecular weight less than about 250 may also be incorporated.
  • the mole ratio of isocyanate to hydroxyl in the polymer is preferably from about 0.95 to 1.08 more preferably 0.95 to 1.05, and most preferably, 0.95 to 1.00.
  • monofunctional isocyanates or alcohols can be used to control molecular weight of the polyurethane.
  • Suitable polyester polyols include the polyesterification products of one or more dihydric alcohols with one or more dicarboxylic acids.
  • Suitable polyester polyols also include polycarbonate polyols.
  • Suitable dicarboxylic acids include adipic acid, succinic acid, sebacic acid, suberic acid, methyladipic acid, glutaric acid, pimelic acid, azelaic acid, thiodipropionic acid and citraconic acid and mixtures thereof, including small amounts of aromatic dicarboxylic acids.
  • Suitable dihydric alcohols include ethylene glycol, 1,3- or
  • hydroxycarboxylic acids such as E -caprolactone and 3-hydroxybutyric acid can be used in the preparation of the polyester.
  • Preferred polyesters include poly (ethylene adipate), poly(1,4-butylene adipate), mixtures of these adipates, and poly E caprolactone.
  • Suitable polyether polyols include the condensation products of one or more alkylene oxides with a small amount of one or more compounds having active hydrogen containing groups, such as water, ethylene glycol, 1,2- or 1,3-propylene glycol,
  • Suitable alkylene oxide condensates include those of ethylene oxide, propylene oxide and butylene oxide and mixtures thereof.
  • Suitable polyalkylene ether glycols may also be prepared from
  • suitable polyether polyols can contain comonomers, especially as random or block comonomers, ether glycols derived from
  • THF tetrahydrofuran
  • a THF polyether copolymer with minor amounts of 3-methyl THF can also be used.
  • Preferred polyethers include
  • PTMEG poly(tetramethylene ether) glycol
  • propylene oxide and ethylene oxide and copolymers of tetrahydrofuran and ethylene oxide.
  • suitable polymeric diols include those which are primarily hydrocarbon in nature, e.g., polybutadiene diol.
  • Suitable organic diisocyanates include
  • butanediol can also be present in the polyurethanes.
  • thermoplastic polyurethanes include those containing carbon chains which are either uninterrupted or which are interrupted by oxygen or sulfur linkages,
  • dihydroxyethyl terephthalate and dihydroxymethyl benzene and mixtures thereof Hydroxyl terminated oligomers of 1,4-butanediol terephthalate can also be used, giving a polyester-urethane-polyester repeating structure.
  • Diamines can also be used as chain
  • 1,4-Butanediol, 1,2-ethanediol and 1,6-hexanediol are preferred.
  • the ratio of isocyanate to hydroxyl should be close to unity, and the reaction can be a one step or a two step reaction. Catalyst can be used, and the reaction can be run neat or in a
  • thermoplastic polyurethane can influence the results achieved.
  • Water is known to react with polyurethanes, causing the polyurethane to degrade, thereby lowering the effective molecular weight of the polyurethane and lowering the inherent and melt viscosity of the polyurethane. Accordingly, the drier the better.
  • the moisture content of the blend, and of the individual components of the blend should contain less than 0.2 percent by weight of water, preferably less than 0.1 percent, especially when there is no opportunity for the water to escape, for example during an injection molding process and other techniques of melt processing.
  • thermoplastic polyurethane can also contain those additives, ingredients, and modifiers known to be added to thermoplastic polyurethane.
  • Component (c) is at least one amorphous thermoplastic polymer.
  • amorphous thermoplastic polymers are thermoplastic polymers that are generally used by themselves in extrusion and injection molding processes. These polymers are known to those skilled in the art as extrusion and injection molding grade resins, as opposed to those resins that are known for use as minor components (i.e., processing aids, impact modifiers, stabilizers) in polymer compositions.
  • amorphous it is meant that the polymer has no distinct crystalline melting point, nor does it have a measurable heat of fusion (although with very slow cooling from the melt, or with of sufficient annealing, some crystallinity may develop).
  • the heat of fusion is conveniently determined on a differential scanning calorimeter (DSC).
  • a suitable calorimeter is the Du Pont Company's 990 thermal analyzer. Part Number 990000 with cell base II, Part Number 990315 and DSC cell. Part Number 900600. With this instrument, heat of fusion can be measured at a heating rate of 20oC per minute. The sample is alternately heated to a temperature above the
  • Amorphous polymers are defined herein as having a heat of fusion, by this method, of less than 1 cal/gram.
  • semicrystalline 66 nylon polyamide with a molecular weight of about 17,000 has a heat of fusion of about 16 cal/gm.
  • thermoplastic it is meant that the polymer softens, when heated, to a flowable state in which under pressure it can be forced or
  • the amorphous thermoplastic polymers useful in the present blends must be “melt processible” at the temperature at which the polyoxymethylene blend is melt processed.
  • Polyoxymethylene, and blends thereof is normally melt processed at melt-temperatures of about 170-260oC, preferably 185-240oC, and most preferably 200-230oC.
  • melt processible it is meant that the amorphous thermoplastic polymer must soften or have a sufficient flow such that it can be melt compounded at the particular melt processing temperature for the polyoxymethylene blend.
  • the minimum molecular weight of the amorphous thermoplastic polymer is not considered to be significant for the present blends, provided that the polymer has a degree of polymerization of at least twenty and further provided that the polymer is melt processible (i.e., it flows under pressure) at the temperature at which the polyoxymethylene is melt processed.
  • the maximum molecular weight of the amorphous thermoplastic polymer should not be so high that the amorphous thermoplastic polymer by itself would not be injection moldable by standard present techniques.
  • the maximum molecular weight for a polymer to be used for injection molding processes will vary with each individual, particular amorphous
  • thermoplastic polymer is thermoplastic polymer.
  • said maximum molecular weight for use in injection molding processes is readily discernible by those skilled in the art.
  • thermoplastic polymer have matching melt viscosity values under the same conditions of temperature and pressure.
  • the amorphous thermoplastic polymer can be incorporated into the blend as one amorphous
  • thermoplastic polymer or as a blend of more than one amorphous thermoplastic polymer.
  • thermoplastic polymer or as a blend of more than one amorphous thermoplastic polymer.
  • component (c) consists of one amorphous thermoplastic polymer. Whether it is incorporated as one amorphous thermoplastic polymer or as a blend of more than one, the weight percent of all amorphous thermoplastic polymers in the composition shall not exceed the weight percent ranges given above.
  • Amorphous thermoplastic polymers, which are injection molding and extrusion grade, suited for use in the blends of the present invention are well known in the art and can be selected from those commercially available or can be made by processes known in the art.
  • Suitable amorphous thermoplastic polymers can be selected from the group consisting of styrene acrylonitrile copolymers (SAN), SAN copolymers toughened with a mostly unsaturated rubber, such as acrylonitrile-butadiene-styrene (ABS) resins, or toughened with a mostly saturated rubber, such as acrylonitrile-ethylene-propylene-styrene resins (AES), polycarbonates, polyamides, polyarylates,
  • SAN styrene acrylonitrile copolymers
  • ABS acrylonitrile-butadiene-styrene
  • AES acrylonitrile-ethylene-propylene-styrene resins
  • polyphenyleneoxides polyphenylene ethers, high impact styrene resihs (HIPS), acrylic polymers, imidized acrylic resins, styrene maleic anhydride copolymers, polysulfones, styrene acrylonitrile maleic anhydride resins, and styrene acrylic copolymers, and
  • the preferred amorphous thermoplastic polymers are selected from the group consisting of styrene acrylonitrile copolymers (SAN), SAN copolymers toughened with a. mostly unsaturated rubber, such as acrylonitrile-butadiene-styrene (ABS) resins, or toughened with a mostly saturated rubber, such as acrylonitrile-ethylene-propylene-styrene resins (AES), polycarbonates, and derivatives thereof.
  • SAN styrene acrylonitrile copolymers
  • ABS acrylonitrile-butadiene-styrene
  • AES acrylonitrile-ethylene-propylene-styrene resins
  • amorphous thermoplastic polymers are SAN copolymers, ABS resins, AES resins, and
  • thermoplastic polymers The amorphous thermoplastic polymers
  • SAN copolymer is generally a random, amorphous, linear copolymer produced by copolymerizing styrene and acrylonitrile.
  • the preferred SAN copolymer has a minimum molecular weight of 10,000 and consists of 20-40% acrylonitrile, 60-80% styrene. The more
  • SAN copolymer consists of 25-35%
  • SAN copolymer is commercially available or it can be readily prepared by techniques well known to those skilled in the art. Amorphous thermoplastic SAN copolymers are further described on pages.214-216 in Engineering Plastics, volume 2, published by ASM INTERNATIONAL, Metals Park, Ohio (1988).
  • ABS resin is produced by polymerizing
  • the ABS resin is comprised of 50-95% of a matrix of SAN, with said matrix being comprised of 20-40% acrylonitrile and 60-80% styrene, and 5-50% of a butadiene rubber or a mostly butadiene rubber, such as styrene butadiene rubber (SBR) . More preferably, it is comprised of 60-90% of a matrix of SAN, with said matrix more preferably being comprised of 25-35% acrylonitrile and 65-75% styrene, and 10-40% of a butadiene rubber.
  • AES resin is produced by
  • the preferred and more preferred AES resin is the same as the preferred and more preferred ABS resin except that the rubber component is comprised of mostly ethylene-propylene copolymer, as opposed to butadiene, or mostly
  • ABS and AES copolymers are commercially available or can be readily prepared by techniques well known to those skilled in the art.
  • Amorphous thermoplastic ABS resin is further described on pages 109-114 in Engineering Plastics, referenced above.
  • thermoplastic polycarbonates that are useful herein are well known in the art and can be most basically defined as possessing the repetitive carbonate group
  • the polycarbonate can be any polycarbonate.
  • the polycarbonate can be any polycarbonate.
  • Z is a single bond, an alkylene or alkylidene moiety with 1-7 carbon atoms, a cycloalkylene or cycloalkylidene moiety with 5-12 carbon atoms, -O-, -S-, -CO-, -SO- or -SO 2 -, preferably methylene or isopropylidene;
  • R 1 and R 2 are a hydrogen, a halogen, or an alkylene or alkylidene moiety having 1-7 carbon atoms, and n equals 0 to 4.
  • thermoplastic polycarbonates are commercially available or can be readily prepared by techniques well known to those skilled in the art.
  • aromatic polycarbonate on the basis of commercial availability and available technical information is the polycarbonate of
  • bis(4-hydroxyphenyl)-2,2-propane known as bisphenol-A polycarbonate.
  • Amorphous thermoplastic polycarbonate is further described on pages 149-150 of Engineering Plastics, referenced above.
  • thermoplastic polyamide polymers useful herein are described in U.S. patent 4,410,661, incorporated herein by reference.
  • thermoplastic polyarylate polymers useful herein are described in U.S. patent 4,861,828, incorporated herein by reference.
  • PPE amorphous thermoplastic polyphenylene ethers
  • PPO polyphenylene oxides
  • composition of the homopolymer is
  • the chemical composition of PPE which is a copolymer, is as follows:
  • thermoplastic high impact styrene (HIPS) resins that are useful herein are produced by dissolving usually less than 20 percent polybutadiene rubber, or other rubber, in styrene monomer before initiating the polymerization reaction. Polystyrene forms the continuous phase of the polymer and the rubber phase exists as discrete particles having occlusions of polystyrene. HIPS resin is further described on pages 194-199 in Engineering Plastics, referenced above.
  • amorphous thermoplastic acrylics useful herein are those polymers in which the major monomeric constituents belong to two families of ester-acrylates and methacrylates.
  • Amorphous thermoplastic acrylic polymers are described on pages 103-108 in Engineering Plastics, referenced above. The molecular weight of the amorphous thermoplastic acrylic polymer, in order for it to be injection moldable by standard
  • the preferred amorphous thermoplastic acrylic resin is polymethyl methacrylate.
  • amorphous styrene maleic anhydride copolymers that are useful herein are produced by the reaction of styrene monomer with smaller amounts of maleic anhydride.
  • the structure of styrene maleic anhydride is as follows:
  • thermoplastic styrene maleic anhydride copolymers are further described on pages 217-221 in Engineering Plastics, referenced above.
  • thermoplastic polysulfones that are useful herein have the following structure:
  • the amorphous thermoplastic polymers may also contain those additional ingredients, modifiers, stabilizers, and additives commonly included in such polymers.
  • polymer stabilizer used in the blends of the present invention is a homopolymer or copolymer containing "formaldehyde reactive" nitrogen groups, is "non-meltable” at the temperature at which the
  • polyoxymethylene blend is melt processed, and has a number average particle size, before melt processing and thereafter, of less than ten microns.
  • Formaldehyde reactive it is meant that the nitrogen group contains a nitrogen with one or two hydrogen atoms bonded to it. Formaldehyde will react with the -NH bonds of the polymer stabilizer. These reactive sites are referred to herein as formaldehyde reactive sites. It is preferred that the polymer stabilizer contain formaldehyde reactive nitrogen groups having the maximum number of formaldehyde reactive sites.
  • a polymer stabilizer containing formaldehyde reactive nitrogen groups wherein there are two hydrogen atoms attached directly to the nitrogen atom is preferred over one containing formaldehyde reactive nitrogen groups wherein there is only one hydrogen atom attached directly to the nitrogen atom (i.e., one formaldehyde reactive site in the group).
  • the polymer stabilizer further has at least ten repeat units. It preferably has a weight average molecular weight of greater than 5,000, most
  • the polymer stabilizer is "non-meltable" at the temperature at which the polyoxymethylene blend is melt processed. More specifically, by the term “non-meltable”, it is meant that the polymer
  • the polymer stabilizer has its "major melting,point" above the temperature at which the polyoxymethylene blend is melt processed and thus remains essentially a solid during melt processing of the polyoxymethylene blend.
  • the polymer stabilizer is
  • melt flow rate of the polymer stabilizer may not be significant because the polymer stabilizer has a high viscosity, attributed to, for example, high molecular weight or crosslinking.
  • the melt flow rate of the polymer stabilizer is preferably less than one-tenth that of the
  • polyoxymethylene in the blend It is recommended that for most accurate results, the polymer stabilizer be dried for 12 hours at 90oC prior to measuring its melt flow rate.
  • the "major melting point" of the polymer stabilizer can be determined on a differential
  • the polyoxymethylene blends described herein are usually melt processed at melt temperatures of about 170-260oC, preferably 185-240oC, most preferably 200-230oC.
  • the polymer stabilizer must also have a number average particle size of less than 10 microns after melt processing in the blend. It further should have a number average particle size of less than 10 microns before melt processing with the
  • the loose agglomerates should be broken up prior to measuring the number average particle size of the polymer stabilizer or, alternatively, they should be discounted in making said measureraent. Whether or not a polymer stabilizer contains a high degree of loose agglomerates can be determined by standard techniques of transmission electron microscopy. The details of determining the number average particle size, both before and after melt processing, are disclosed below.
  • the formaldehyde reactive nitrogen groups can be incorporated into the polymer stabilizer by using an appropriate nitrogen containing monomer, such as, for example, acrylamide and methacrylamide.
  • Preferred nitrogen containing monomers are those that result in the polymer stabilizer containing
  • formaldehyde reactive nitrogen groups wherein there are two hydrogen atoms attached to the nitrogen.
  • the particularly preferred monomer is acrylamide which, when polymerized, results in a polymer stabilizer having substantially all of the formaldehyde reactive nitrogen groups attached directly as a side chain of the polymer backbone or indirectly as a side chain of the polymer backbone.
  • the formaldehyde reactive nitrogen groups can be generated on the polymer stabilizer by modification of the polymer or copolymer.
  • the formaldehyde reactive nitrogen groups may be incorporated by either method as long as the resultant polymer prepared therefrom is non-meltable, or is capable of being made non-meltable, at the temperature at which the polyoxymethylene blend is melt processed.
  • the quantity of the formaldehyde reactive nitrogen groups in the polymer stabilizer must be such that the atoms in the backbone to which the
  • formaldehyde reactive nitrogen groups are attached, either directly or indirectly, are separated from each other (i.e., connected to each other) by not more than twenty chain atoms.
  • the polymer is preferably, the polymer
  • the stabilizer will contain at least one formaldehyde reactive nitrogen group per each twenty carbon atoms in the backbone of the polymer. More preferably, the ratio of formaldehyde reactive nitrogen groups to carbon atoms in the backbone will be 1:2-1:10, most preferably 1:2-1:5.
  • the formaldehyde reactive nitrogen groups should be present in the polymer stabilizer such that the amount of the formaldehyde reactive nitrogen groups as, or part of, the side chains of the polymer stabilizer backbone is at least 3 times, preferably at least ten times, the amount of the formaldehyde reactive nitrogen groups, if any, present in the backbone of the polymer stabilizer.
  • the formaldehyde reactive nitrogen groups, attached directly or indirectly to the atom ⁇ ih the backbone of the stabilizer polymer should be at least three times as great, preferably at least ten times as great, as those in the backbone of the polymer stabilizer, if such are present.
  • the formaldehyde reactive nitrogen groups attached directly or indirectly to the side of the polymer backbone are preferably present in a substantially greater quantity than the formaldehyde reactive nitrogen groups, if any, present in the the polymer backbone. Most preferably, nearly one hundred percent of the formaldehyde reactive nitrogen groups are attached to the sides of the polymer backbone.
  • the polymer stabilizer can be a homopolymer or a copolymer, provided it is non-meltable. It is preferred that the polymer stabilizer be polymerized from acrylamide or methacrylamide monomer by free radical polymerization and that the polymer stabilizer prepared therefrom consist of at least 75 mole percent
  • R hydrogen or methyl. More preferably, it consists of at least 90 mole percent of the above units, even more preferably, it consists of at least 95 mole percent of the above units, and most
  • the polymer stabilizer may be a copolymer in that it is polymerized from more than one monomer.
  • the comonomer may or may not contain formaldehyde reactive nitrogen and/or formaldehyde reactive hydroxyl groups. Examples of other monomers that may be thus
  • incorporated include styrene, ethylene, alkyl
  • the comonomer preferably should be added such that it does not unduly minimize the number of moles of formaldehyde reactive groups per gram of polymer stabilizer. Further, it should not unduly minimize the number of formaldehyde reactive sites per gram of polymer stabilizer.
  • Specific preferred stabilizers that are copolymeric include copolymers of hydroxypropyl methacrylate with acrylamide, methacrylamide, or dimethylaminoethyl methacrylate.
  • the polymer stabilizer must have a number average particle size of less than 10 microns
  • the number average particle size of the polymer stabilizer is important in achieving the improved stability for
  • Stability is related to the interaction that occurs between the polyoxymethylene blend components and the polymer stabilizer and as such, it is desirable to have good interaction between the polyoxymethylene and the polymer stabilizer. Maximizing the surface area/gram of polymer stabilizer increases interaction between the polymer stabilizer and the blend components. The surface area/gram of polymer stabilizer increases as the particle size of the polymer stabilizer decreases. Thus, a stabilizer with small particle size is highly desired.
  • the polymer stabilizer particle size is, on average, on the order of 10-100 microns, then the polymer stabilizer may impart stability to the
  • the small number average particle size of the polymer stabilizer may be obtained directly during the polymerization of the monomer or comonomers. To obtain the small average particle size, the stabilizer polymerization is carried out by conventional
  • the polymer stabilizer prepared therefrom should be insoluble in the polymerization media.
  • the particular media selected for polymerization is dependent upon the particular monomer or comonomers chosen and the polymer that will result therefrom.
  • the preferred media is a lower alkyl alcohol.
  • the polymerization may be by addition or condensation polymerization or free radical polymerization. The most preferred method is one that will result in the number of formaldehyde reactive sites in the formaldehyde reactive group being maximized.
  • free radicals is one that will result in the number of formaldehyde reactive sites in the formaldehyde reactive group being maximized.
  • Polymer stabilizer prepared from acrylamide is most preferably prepared by free radical polymerization.
  • the polymerization method must be such that it results in a polymer stabilizer having formaldehyde reactive nitrogen groups in the quantities and amounts previously defined.
  • the polymer stabilizer produced by the polymerization to small particle size will have a sufficient major melting point or have a sufficiently low melt flow rate such that it is non-meltable as polymerized. In other cases, the polymer stabilizer may not be non-meltable as
  • crosslink due to, for example, application of heat, to a sufficiently high molecular weight such that it has a low melt flow rate and is non-meltable at the temperature at which the polyoxymethylene blend is melt processed. Whether the polymer stabilizer will be non-meltable as polymerized or will become
  • non-meltable after polymerization depends upon the nature of the particular monomer or comonomers being polymerized.
  • the polymer stabilizer produced by the polymerization of the monomer or comonomers will not be non-meltable as polymerized and it will not become non-meltable subsequent to
  • unsaturated monomers such as, for example, acrylates, methacrylates, acrylamides, and methacrylamides, and derivatives thereof.
  • acrylates, methacrylates, acrylamides, and methacrylamides and derivatives thereof.
  • Specifically preferred monomers are ethylene glycol dimethacrylate and
  • Monomers that may cause crosslinking after polymerization of the stabilizer polymer is complete include, for example, glycidyl methacrylate, acrylic acid, methacrylic acid, and derivatives thereof.
  • the crosslinking monomer should be added in an amount that is sufficient to yield a polymer stabilizer that is non-meltable at the
  • cros ⁇ linking monomer it can be advantageous to have a dispersing aid present.
  • a dispersing aid present.
  • Dispersing aids and the methods of preparing them are well known in the art. A description of the methods of making and choosing dispersing aids is included in Dispersion Polymerization in Organic Media (by K. E. J. Barrett, New York: John Wiley & Sons, 1975). Particularly preferred dispersing aids include polyethylene glycol and its derivatives, methyl methacrylate copolymers, and poly (oxypropylene) -poly(oxyethylene) glycol block copolymers.
  • Emulsifiers and the method of preparing them are well known in the art. Emulsion
  • the dispersant or dispersant solution or the emulsifier is added to the polymerization reaction vessel simultaneously with the monomer and
  • dispersant or dispersant solution or emulsifier is known to destabilize polyoxymethylene. If the
  • dispersant or dispersant solution or emulsifier is not known to destabilize polyoxymethylene in particular, it may be advantageous to leave it in the polymer stabilizer as it can act to reduce any agglomeration of particles that may occur during the drying of the polymer stabilizer.
  • the small number average particle size of the polymer stabilizer may alternatively be obtained subsequent to the polymerization of the monomer or comonomers, while the polymer stabilizer is still in the polymerization medium or is in solution. In such cases, the small number average particle size of the stabilizer may be obtained by adding a crosslinking monomer to the polymer stabilizer in the
  • the small number average particle size of the stabilizer may be obtained by adding a solvent in which the stabilizer polymer is insoluble to the polymer stabilizer in the polymerization medium.
  • polymerization medium may be added to a solvent in which the polymer stabilizer is insoluble.
  • Small number average particle size can be obtained by other known means of separating the polymer from the
  • polymer stabilizer provided that such method will yield a polymer stabilizer having small particles, with a number average size less than 10 microns, prior to melt processing with the polyoxymethylene blend.
  • the small particles should be non-meltable at the temperature at which the polyoxymethylene blend is melt processed and should not coalesce or agglomerate to such an extent that they are not readily
  • the number average particle size of the polymer stabilizer before it is melt processed with the polyoxymethylene blend components can be measured by any means capable of determining number average particle size.
  • the preferred means is the MICROTRAC II SMALL PARTICLE ANALYZER (ANALYZER), manufactured by Leeds & Northrup.
  • a preferred model is 158705/158708.
  • the polymer stabilizer is added to a liquid, such as, for example, 2-propanol (usually about 0.1 grams of polymer stabilizer in 15 ml. of liquid), and shaken by hand to disperse the polymer stabilizer in the liquid. From this dispersion, the number average particle size for the polymer
  • stabilizer is determined by the ANALYZER.
  • the ANALYZER is equipped with a
  • ANALYZER prints the percent of particle volume that has a diameter of less than the given detector
  • the number average particle size of the polymer stabilizer can be calculated. In this calculation, the particle diameter for a given detector channel is approximated by the channel diameter. The number of particles in each channel is calculated by the following formula:
  • V% volume of particles in that channel
  • the total number, of particles By summing the number of particles in all 17 channels, the total number, of particles can be calculated. By multiplying the number of particles in a channel by 100, and dividing the result by the total number of particles, the percent of particles in each channel can be calculated. To calculate the total number percent having a diameter of less than that channel, a cumulative number percent is calculated by adding the number percent in all channels that have a diameter less than or equal to that particular channel. From this cumulative sum of number percents, the median number average particle size of the polymer stabilizer can be calculated. The median number average particle size of the polymer stabilizer will be 10 microns or less for purposes of this invention.
  • the number average particle size of the polymer stabilizer after it has been melt processed with the components of the polyoxymethylene blend should be less than 10 microns, preferably less than 5 microns, and most preferably less than 2 microns. It can be measured by any technique capable of measuring number average particle size for particles in a polymer.
  • the preferred method of measuring the number average particle size of the polymer stabilizer in the polyoxymethylene blend is by transmission electron microscopy.
  • the polymer stabilizer should be substantially free of basic materials which can destabilize the polyoxymethylene.
  • Basic impurities should preferably be removed to levels of not more than 50 ppm and most preferably to not more than 10 ppm. In stabilizing blends based upon polyoxymethylene copolymer or homopolymer that is substantially all ether-capped, higher concentrations of basic materials can be tolerated. In addition, it should be
  • acidic impurities in the polymer etabilizer should be minimized. Acidic impurities should preferably be removed to levels of not more than 50 ppm and most preferably to not more than 10 ppm. As with basic impurities, it should be understood that if the impurity is only weakly acidic, relatively higher amounts can be tolerated.
  • the polymer stabilizer should be purified before it is introduced into the blends of the present invention.
  • Polymer stabilizers used in the blends of the present invention can be purified by washing with an appropriate liquid, such as methanol and/or water.
  • Polymer stabilizers prepared with dispersants or emulsifiers that have destabilizing effects because, for example, they are highly acidic or highly basic can be purified by washing the stabilizer with a solvent in which the dispersants or emulsifiers are soluble and in which the polymer stabilizer is insoluble.
  • component (e) co-stabilizer component is selected from the group consisting of conventional
  • meltable polyamide stabilizers for polyoxymethylene, certain “meltable” hydroxy containing polymers or oligomers, and microcrystalline cellulose.
  • melttable means the inverse of the term
  • non-meltable as described above. More specifically, it means that the co-stabilizer component has its “major melting point”, as described above, below the temperature at which the polyoxymethylene blend is melt processed.
  • the preferred conventional meltable nylon stabilizer is a terpolymer of polycaprolactam/polyhexamethylene
  • adipamide/polyhexamethylene sebacamide terpolymer most preferably in the ratio of 43/34/23.
  • polymers/oligomers containing hydroxy groups wherein the atoms in the backbone of the polymer or oligomer to which the hydroxy groups are attached, directly or indirectly, are separated from each other, on average, by not more than twenty chain atoms and provided further that the polymer or oligomer is substantially free of acidic materials.
  • the preferred hydroxy containing co-stabilizer is a polymer or oligomer of ethylene vinyl alcohol.
  • microcrystalline cellulose co-stabilizer useful herein is described in U.S. patent 3,023,104, incorporated herein by reference. Microcrystalline cellulose is referred to therein as "cellulose
  • Microcrystalline cellulose is also described in "Hydrolysis and Crystallization of Cellulose", Industrial and Engineering Chemistry, vol. 42, 502-507 (1950).
  • microcrystalline cellulose useful herein will have an average particle size no greater than 300 microns.
  • the average particle size is the point at which 50% of the particles are greater than average and 50% of the particles are less than average.
  • Average particle size can be determined by standard techniques, such as microscopic inspection,
  • the average particle size of the microcrystalline cellulose used herein be 100 microns or less, more preferably, 50 microns or less, even more preferably, 25 microns or less, and most preferably, 10 microns or less.
  • compositions of the present invention can include, in addition to the components of the polyoxymethylene blend, other ingredients, modifiers, and additives as are generally used in polyoxymethylene molding resins, including co-stabilizers other. than those described above, anti-oxidants, especially amide-containing phenolic antioxidants such as N,N'-hexamethylene bis (3,5-di-tert-butyl-4-hydroxyhydrocinnamide and mixtures thereof, pigments, colorants, UV stabilizers, hindered amine light stabilizers, toughening agents, nucleating agents, lubricants, glass, talc, and fillers. It should also be understood that some pigments and colorants can, themselves, adversely affect the stability of polyoxymethylene compositions.
  • anti-oxidants especially amide-containing phenolic antioxidants such as N,N'-hexamethylene bis (3,5-di-tert-butyl-4-hydroxyhydrocinnamide and mixtures thereof, pigments, colorants, UV stabilizers, hindere
  • the polymer stabilizer should be present in the blends of the present invention in the amount of 0.05-3 weight percent, based on the weight of
  • polyoxymethylene blend may be improved; however, with increased loading of the polymer stabilizer, the physical properties of the polyoxymethylene blend may decrease.
  • the co-stabilizer component When the co-stabilizer component is present, it should be incorporated into the blend at the following weight percent ranges, with said weight percent ranges being based upon the total of components (a), (b), and (c) only: 0.01 to 1.00 weight percent, preferably 0.01 to 0.50 weight percent, and more preferably, 0.05 to 0.30 -weight percent.
  • weight percent range of components (a), (b), and (c) should be as follows, with said weight percent ranges being based upon the total weight of components (a), (b), and (c) only: 40 to 98 weight percent component (a) polyoxymethylene, 1 to 40 weight percent component (b) thermoplastic polyurethane, and 1 to 59 weight percent component (c) amorphous
  • thermoplastic polymer Preferably, the weight percent range of components (a), (b), and (c) is as follows: 45-90 weight percent component (a) polyoxymethylene, 5-30 weight percent component (b) thermoplastic polyurethane, and 5-50 weight percent component (c) amorphous thermoplastic polymer.
  • the weight percent range of components (a), (b), and (c) is as follows: 50-90 weight percent component (a) polyoxymethylene, 5-20 weight percent component (b) thermoplastic polyurethane, and 5-45 weight percent component (c) amorphous thermoplastic polymer.
  • compositions of the present invention can be prepared by mixing the polymer stabilizer, which has a number average particle size of less than 10 microns and which is non-meltable, or can be made non-meltable during processing, with the
  • thermoplastic polyoxymethylene compositions such as rubber mills, internal mixers such as
  • machines, and extruders both single screw and twin screw, both co-rotating and counter rotating, both intermeshing and non-intermeshing.
  • These devices can be used alone or in combination with static mixers, mixing torpedoes and/or various devices to increase internal pressure and/or the intensity of mixing, such as valves, gate or screws designed for this purpose. Extruders are preferred. Of course, such mixing should be conducted at a temperature below which significant degradation of the polyoxymethylene will occur.
  • the polymer stabilizer in the composition after melt processing will have a number average particle size less than 10 microns.
  • Shaped articles can be made from the
  • compositions of the present invention using any of several common methods, including compression molding, injection molding, extrusion molding, blow molding, rotational molding, melt spinning, and thermoforming. Injection molding is preferred.
  • shaped articles include sheet, profiles, rod stock, film, filaments, fibers, strapping, tape tubing, and pipe. Such shaped articles can be post treated by
  • Such shaped articles and scrap therefrom can be ground and remolded.
  • melt temperatures of about 170-260oC, preferably
  • the mold temperature will generally be 10-120oC,
  • blends stabilized with a mixed stabilizer system containing the polymer stabilizer described herein and either a polyamide stabilizer or a hydroxy containing stabilizer have better melt processing stability than blends stabilizer with one component of the stabilizer system.
  • POM-A was an acetate end-capped homopolymer having a number average molecular weight of about 35,000.
  • polyoxymethylene copolymer having a melt flow index of about 9.0 at 190oC under a load of 2160 g. It was prepared from the cationic polymerization of trioxane and ethylene oxide using bortrifluoride as a catalyst. Stabilizers
  • Stabilizer "A” was the non-meltable polymer stabilizer, containing formaldehyde reactive nitrogen groups, of the present invention. It was prepared by adding a solution of 14.3 kg of acrylamide and 145.15 grams of 1,4-butanediol diacrylate to a refluxing solution of 1.44 kg of polyethylene glycol having a molecular weight of about 8000 in 48.06 kg of methanol (approximately 64oC) over a period of about two hours. Throughout this addition, a total of 195.04 grams of tert-butylperoxypivylate polymerization initiator was portionwise added. The resulting reaction suspension was cooled and filtered. The resulting white solid was washed with methanol and dried in a vacuum oven
  • Co-Stabilizer "B” was a 43/34/23
  • This is also known as a 43/34/23 terpolymer of nylon 6, nylon 66, and nylon 610, respectively. It had a melting point, measured in accordance with ASTM D796, between 148-160oC.
  • Co-Stabilizer "C” was a 29/79 copolymer of ethylene and vinyl alcohol prepared in accordance with U.S. 4,766,168. It had a melting point, measrued in accordance with ASTM D796, of about 191oC.
  • Co-Stabilizer "D” was nylon 66 dispersed in an ethylene/methacrylate copolymer, prepared as described in U.S. 4,098,843. Specifically, it was nylon 66 (33.5%) in an 85/15 ethylene/methacrylate copolymer (66.5%) partially crosslinked by zinc salts. The percent of neutralization with the zinc salts is about 58%. It had a melt flow rate of 0.7 g/10min, as measured by ASTM D-1238, and a melting point of 88oC, as measured by Differential Thermal Analysis (ASTM D3418, heating rate of 10oC/minute.
  • thermoplastic Polyurethane Thermoplastic Polyurethane (TPU)
  • Thermoplastic polyurethane used in the blends of the examples below had an inherent viscosity of 1.33, a soft segment glass transition temperature (Tg) of -35oC, and was comprised of 37% adipic acid, 39% butanediol, and 24% 4,4'-methylene bisphenyl isocyanate.
  • Inherent viscosity was measured by ASTM D-2857 with a "Schott" automatic viscometer at 0.1% polyurethane in dimethyl formamide at 30oC.
  • the Tg was determined using a Du Pont Model 981 Dynamic
  • viscosity data in Pascal seconds, on the amorphous thermoplastic polymer component used in the blends of the examples below was obtained at 220oC, at shear rates of 100 1/sec and 1000 1/sec.
  • the viscosity data for the individual amorphous thermoplastic polymers used in the examples is reported firstly for a shear rate of 100 1/sec and secondly for a shear rate of 1000 1/sec.
  • the individual araorphous thermoplastic polymeric components used in the examples are
  • SAN-A was a styrene acrylonitrile copolymer having a melt viscosity of 934 and 241, respectively, and consisting of 30% acrylonitrile, 70% styrene.
  • SAN-B was a styrene acrylonitrile copolymer having a melt viscosity of 1713 and 329, respectively, and consisting of 24% acrylonitrile, 76% styrene.
  • AES was an acrylonitrile-ethylene-propylene- styrene resin having a melt viscosity of 1841 and 363, respectively, and consisting of 51% styrene, 21% acrylonitrile, and 28% ethylene propylene rubber.
  • ABS was an acrylonitrile-butadiene-styrene resin having a melt viscosity of 1081 and 223,
  • PC-A was a polycarbonate of bisphenol A having a melt viscosity of 218 Pascal seconds
  • Antioxidant "A” was 2,2-methylene-bis-(4- methyl-6-tert-butyl-phenol).
  • Antioxidant "B” was N,N'-hexamethylene-bis- 3-(3,5-di-tert-butyl-4-hydroxyphenol) proprionate.
  • Antioxidant "C” was a triethyleneglycol-bis-
  • the components of the blends were melt compounded on a 28 mm Werner & Pfleiderer bilobal extruder, using a screw design containing two working sections with five kneading elements (70 mm total), and two reverse elements (24 mm total). All
  • the extruder was operated at about 150 rpm with 15-25 pounds per hour throughput.
  • the temperature of the melt coming out of the die ranged from 210oC to 230oC.
  • the components of the blend were melt compounded in two steps.
  • the polyoxymethylene component, the thermal stabilizer component(s), and the antioxidant(s) were compounded on a 2 1/2" sterling screw extruder with a screw speed of 60 rpm.
  • the temperature of the melt exiting the extruder was between 225-240*C.
  • polyoxymethylene product was pelletized.
  • the pelletized product was melt
  • the components of the blend were melt compounded on a 2" sterling single screw extruder, using a single stage screw design with a metering ratio of 2.5/1.0 and a barrier section 8" long and 6" from the front of the screw. All components were supplied from the rear side of the screw.
  • temperature of the melt coming out of the valve die ranged from 225oC to 240oC.
  • the extruder was operated at 60-80 rpm with 25-45 pounds per hour throughput.
  • the components of the blend were melt compounded on a 30 mm Werner & Pfleiderer bilobal extruder with/without a seed feeder.
  • the screw contained two kneading sections (84 mm total) and two reverse sections (20 mm total).
  • the temperature of the melt exiting the die ranged from 200oC to 210oC and the throughput was 15-25 pounds per hour.
  • the extruder was operated at 140-160 rpm.
  • the components of the blend were added to the extruder via the rear side of the screw and side feeder as described in
  • the feed ratio is the ratio of rear feed:side feed.
  • the components of the blend were melt compounded on a 57 mm Werner and Pfleiderer bilobal extruder.
  • the polyoxymethylene polymer and stabilizer components were supplied from the rear of the extruder while the thermoplastic polyurethane and amorphous thermoplastic polymer components were added via a side feeder.
  • the ratio of rear feed:side feed was 45:55.
  • the screw had four kneading blocks and four reverse sections.
  • the temperature of the melt coming out of the die was about 244oC.
  • the extruder was operated at
  • polyoxymethylene blends of the examples was determined using a thermally evolved formaldehyde (TEF) test procedure.
  • TEZ thermally evolved formaldehyde
  • a weighed sample of polyoxymethylene blend was placed in a tube and the tube was fitted with a cap for introduction of nitrogen to the test sample for removal of any evolved gases from the apparatus while maintaining the sample in an oxygen-free environment.
  • the tube that contained the sample was heated at either 250oC or 259oC in a silicon oil bath.
  • the nitrogen and any evolved gases transported thereby were bubbled through 75 ml of a 40 g/liter sodium sulfite in water solution.
  • Any evolved formaldehyde reacts with the sodium sulfite to liberate sodium hydroxide.
  • the sodium hydroxide was continuously neutralized with standard 0.1 N HCl. The results were obtained as a chart of ml of titer versus test time.
  • the percent evolved formaldehyde was calculated by the formula
  • V the volume of titer in milliliters
  • N the normality of the titer
  • the factor "0.03" is the milliequivalent weight of formaldehyde in g/milliequivalent. Thermally evolved formaldehyde results are reported after 15 minutes and 30 minutes for the blend.
  • V the volume of titer in milliliters
  • N the normality of the titer
  • WP the weight percent of polyoxymethylene in the sample
  • W3 weight of sample (in grams) + glass tube weight after 30 minutes of testing (in grams)
  • the physical properties of the stabilized blends were tested. Specifically , the physical properties that were tested were as follows: mold shrinkage, strength (i.e., tensile), elongation, and toughness (i.e., notched Izod).
  • Mold shrinkage was determined on bars molded from the melt-compounded stabilized blends. Unless otherwise specified, the pellets of the melt
  • compounded stabilized blend were loaded into a 6 ounce C Molding Machine using cylinder temperature settings of about 200oC, a mold temperature set to 60oC, a back pressure of 50 psi, a screw speed of 60 rpm, a cycle of 15 seconds injection/15 seconds hold, mold pressure about 6 kpsi, and a general purpose screw.
  • the melted blend was injection molded into standard 12.7 cm X 1.27 cm X 0.32 cm (5 in X 1/2 in X 1/8) test bars that are used in measuring "Izod" toughness (according to ASTM-0256, Method A). The length of the mold was measured.
  • the sample blend was allowed to stand in the test bar mold at least 2 days in an air
  • Mold shrinkage was determined by the following formula:
  • Mold (mold length-molded sample bar length) x(100) Shrinkage (mold length)
  • Elongation was measured in accordance with ASTM-D638 at 2"/min. Samples were allowed to stand at least two days in an air conditioned room after
  • Toughness reported as "Izod" was measured according to ASTM D-256, Method A. Samples were notched using a single toothed cutting wheel on a TMI Notching Cutter Model 43-15 with a cutter speed setting of 10.0 and a feed speed setting of 6.0. The samples were allowed to stand at least two days in an air conditioned room after molding prior to testing. Testing was done at 23oC (50% RH). Sample bars were prepared as for the mold shrinkage test, i.e., from a 12.7 cm X 1.27 cm X 0.32 cm (5 in X 1/2 X 1.8 in) injection molded bar. The sample bar was cut in half with a notch in each half cut approximately 3.1 cm (1 1/4 in) from each end. Six samples of each
  • TEM samples were prepared by cross-sectional microtoming of molded flexural bars (1/8 inch) of the melt processed blend, said bars being prepared as described for the mold shrinkage tests. The TEM samples were microtomed so that cross sectional views perpendicular to the direction of flow of the blend would be cut from the flexural bar. Using standard -90oC cryo-ultramicrotomy techniques, 90-120 nanometer sections of each sample were microtomed. The sections were mounted on copper TEM grids and exposed to ruthenium tetroxide vapors for staining. The stained sections were examined using a Zeiss EM10CR transmission electron microscope.
  • Examples C1-C4 and Example 1.1 show the effect of various stabilizers on the thermal stability of a POM/TPU blend.
  • Stabilizers A-D worked equally well in stabilizing the POM/TPU blend.
  • Example 1.1 showed, however, that a stabilizer system consisting of the polymer stabilizer A and the nylon stabilizer B acted to improve the stability of the POM/TPU blend to a greater extent than did polymer stabilizer A alone or nylon stabilizer B alone.
  • Samples of the C4 blend were taken for TEM analysis, as described above. The particle size of the polymer stabilizer A in the C4 blend ranged from 0.6-1.4 microns.
  • Examples C5-C7 and 2.1-2.2 show the effect, of the polymer stabilizer A and conventional
  • Example 2.1 Samples of the Example 2.1 blend were taken for TEM analysis, as described above.
  • the particle size of the polymer stabilizer A in Example blend 2.1 ranged from 0.6-1.8 microns.
  • the polymer stabilizer A provided significantly better thermal stability at 15 minutes of testing to the POM/TPU/PC blend than did the other conventional thermal stabilizers.
  • a mixed stabilizer system consisting of polymer
  • stabilizer A and nylon stabilizer B imparted better thermal stability to the POM/TPU/PC blend than did either stabilizer by itself.
  • Examples C8-C9 and 3.1-3.2 stabilized POM/TPU/ABS blends were tested.
  • Examples C10-C12 and 4.1-4.3 POM/TPU/AES blends were tested.
  • the polymer stabilizer A imparted significantly better thermal stability to the blends than did the other conventional stabilizers.
  • a mixed stabilizer system consisting of polymer stabilizer A and nylon stabilizer B imparted better thermal stability. to the blend than did either
  • Example 3.2 Samples were taken from the blends of Example 3.2, Example 4.1, and Example 4.3 for TEM analysis, as described above.
  • the particle size of the polymer stabilizer. A in Example 3.2 ranged from
  • Example 4.1 The particle size of the polymer stabilizer A in Example 4.1 ranged from 0.8-1.2 and in Example 4.3 it ranged from 0.8-1.6.
  • polyoxymethylene used was polyoxymethylene A.
  • Example 10 relates to blends of POM, TPU, and AES.
  • the blends, along with the method by which each was prepared, are described in TABLE IV. below.
  • the polyoxymethylene used was
  • a 45/15/40 POM-A/TPU/SAN-B blend was prepared by Method E.
  • the blend contained as a stabilizer system 0.27 weight percent polymer stabilizer A and 0.14 weight percent conventional nylon stabilizer B. No antioxidant was added to the blend.
  • the TEF results (at 250oC) on the blend were as follows: 0.11 after 15 minutes of testing and 0.29 after 30 minutes of testing.
  • the weight loss of the blend after 30 minutes of testing by the TEF procedure was 1.81.
  • Example 12 and C20 relate to blends of POM-B (a polyoxymethylene copolymer), TPU, and ABS.
  • POM-B a polyoxymethylene copolymer
  • TPU polyoxymethylene copolymer
  • ABS polyoxymethylene copolymer
  • the blends, and the method by which they were prepared, are described in TABLE V, below.
  • the thermal stability of the blend was improved when polymer stabilizer A was incorporated into the blend and the weight loss experienced by the blend was significantly reduced when polymer
  • stabilizer A was added to the blend.

Abstract

L'addition de 0,05 à 3,0 pour cent en poids d'un stabilisant de polymère non fusible ayant une granulométrie particulaire moyenne de 10 microns ou moins et contenant des groupes d'azote réagissant avec le formaldéhyde dans des mélanges de polyoxyméthylène/polyuréthane thermoplastique/polymères thermoplastiques amorphes a pour résultat d'améliorer la stabilité de traitement en fusion desdits mélanges, à condition que le stabilisant polymère non fusible ait une granulométrie particulaire moyenne, dans le mélange de 10 microns ou moins. On obtient une amélioration supplémentaire de la stabilité de traitement en fusion desdits mélanges en leur ajoutant 0,1 à 1,00 pour cent en poids d'un constituant co-stabilisant tel qu'une polyamide, un polymère ou un oligomère contenant de l'hydroxy, ou une cellulose microcristalline, en plus du stabilisant polymère non fusible.
PCT/US1991/002841 1990-05-23 1991-05-01 Melanges de polyoxymethylene thermostables WO1991018051A1 (fr)

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US5344882A (en) * 1990-06-22 1994-09-06 E. I. Du Pont De Nemours And Company Polyacetal blends
EP0672704A2 (fr) * 1994-03-18 1995-09-20 BASF Aktiengesellschaft Masses de moulage thermoplastiques résistant aux chocs, à couleur stable à base de polyoxyméthylènes
EP1448708A1 (fr) * 2001-11-21 2004-08-25 Korea Engineering Plastics Co., Ltd Composition de resine composite a base de polyoxymethylene et articles prepares a partir de cette composition
CN102395625A (zh) * 2009-04-15 2012-03-28 宝理塑料株式会社 聚缩醛树脂组合物
CN106366558A (zh) * 2016-09-30 2017-02-01 无锡市明盛强力风机有限公司 一种工程塑料材料及制备方法

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DE19810659A1 (de) * 1998-03-12 1999-09-16 Basf Ag Nukleierte Polyoxymethylenformmassen
US20040121175A1 (en) * 2002-12-20 2004-06-24 Flexman Edmund A. Layered articles having polyoxymethylene blend substrates with enhanced surface properties and at least one layer thereon and process for making the same
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US4179479A (en) * 1978-04-20 1979-12-18 Mobay Chemical Corporation Thermoplastic polyurethane blends containing a processing aid
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* Cited by examiner, † Cited by third party
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US5344882A (en) * 1990-06-22 1994-09-06 E. I. Du Pont De Nemours And Company Polyacetal blends
EP0672704A2 (fr) * 1994-03-18 1995-09-20 BASF Aktiengesellschaft Masses de moulage thermoplastiques résistant aux chocs, à couleur stable à base de polyoxyméthylènes
EP0672704A3 (fr) * 1994-03-18 1995-11-08 Basf Ag Masses de moulage thermoplastiques résistant aux chocs, à couleur stable à base de polyoxyméthylènes.
EP1448708A1 (fr) * 2001-11-21 2004-08-25 Korea Engineering Plastics Co., Ltd Composition de resine composite a base de polyoxymethylene et articles prepares a partir de cette composition
EP1448708A4 (fr) * 2001-11-21 2006-03-22 Korea Eng Plastics Co Ltd Composition de resine composite a base de polyoxymethylene et articles prepares a partir de cette composition
CN102395625A (zh) * 2009-04-15 2012-03-28 宝理塑料株式会社 聚缩醛树脂组合物
CN106366558A (zh) * 2016-09-30 2017-02-01 无锡市明盛强力风机有限公司 一种工程塑料材料及制备方法

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CN1056698A (zh) 1991-12-04

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