WO1996026242A2 - Procede d'amelioration des proprietes de polyamides chargees - Google Patents

Procede d'amelioration des proprietes de polyamides chargees Download PDF

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Publication number
WO1996026242A2
WO1996026242A2 PCT/US1996/001762 US9601762W WO9626242A2 WO 1996026242 A2 WO1996026242 A2 WO 1996026242A2 US 9601762 W US9601762 W US 9601762W WO 9626242 A2 WO9626242 A2 WO 9626242A2
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WO
WIPO (PCT)
Prior art keywords
plasticizer
carbon black
polyamide
particulate filler
oil absorption
Prior art date
Application number
PCT/US1996/001762
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English (en)
Other versions
WO1996026242A3 (fr
Inventor
Edward Armand Fontaine
Sunil Shantilal Parikh
Kishore Udipi
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Monsanto Company
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Filing date
Publication date
Application filed by Monsanto Company filed Critical Monsanto Company
Publication of WO1996026242A2 publication Critical patent/WO1996026242A2/fr
Publication of WO1996026242A3 publication Critical patent/WO1996026242A3/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/10—Esters; Ether-esters
    • C08K5/12—Esters; Ether-esters of cyclic polycarboxylic acids

Definitions

  • This invention is directed to a process for incorporating particulate fillers such as stabilizing fillers and solid pigments, including, carbon black, into thermoplastic polymers such as polyamides.
  • This invention is also directed to filled polyamide molding compositions and to molded articles prepared therefrom having improved properties.
  • stabilizing fillers and solid pigments such as carbon black
  • carbon black solid pigments
  • U.S.P. 4,277,288 to Lawrence et al. teaches a process for producing a substantially dry, low dusting, free flowing granular pigment composition comprising (a) contacting a fluidized bed of pigment and a granulating assistant, (b) optionally contacting the granules so obtained with a surfactant and (c) removing the dry granules from the bed.
  • Waggoner and in U.S.P. 4,518,728 to Robert E. Pollard.
  • Waggoner teaches polyamide molding blends containing carbon black and nigrosine and teaches that carbon black can be employed in any of its commercial forms.
  • Waggoner demonstrates, by way of working examples Control D and Control D-l (displayed in Table IV) that the addition of carbon black (by way of the process disclosed therein) to a nylon 66 base resin results in a molded article having reduced elongation and showing brittle breaks.
  • Pollard teaches using a carbon black that is a concentrate or pre ix of a 25% by weight dispersion of carbon black in a nylon 6 carrier.
  • Such premixes are preferred over carbon black powder which is difficult to handle and to disperse evenly in the polyamide.
  • the concentrate approach provides an easier method for handling particulate fillers, such as carbon black, but requires separate steps for dispersing the material and preparing the concentrate. This adds to the cost of the final polymer composition.
  • the present invention is therefore directed to a process for improving the processability and tensile strength of, and promoting ductile failure of filled polyamides, while not adversely affecting the flammability of such filled polyamides, which process comprises:
  • the present invention is also directed to a flame retardant filled polyamide molding composition having improved processability and to a flame retardant, molded article having improved thermal properties, tensile strength and toughness.
  • plasticizers to polyamide molding compositions is known to adversely affect the flammability of, in addition to causing a lowering in the heat distortion temperature of molded articles prepared therefrom.
  • the present invention it has been found that by wetting a particulate filler with a quantity of plasticizer prior to blending the filler with a polyamide the heat distortion temperature of molded articles prepared from such filled polyamides is unexpectedly increased, and the flammability of such articles is surprisingly not adversely affected, while incorporation of the filler into the polyamide is facilitated.
  • Polyamides which may be employed in the practice of the present invention are commonly known as nylons and include, but are not limited to, nylon 6 or poly(caprolactam) , nylon 11 or poly(ll-aminoundecanoic acid) , nylon 12 or poly(lauryl lactam) or poly(12-aminododecanoic acid), nylon 6,6 or poly(hexamethylene adipamide) , nylon 6,9 or poly(hexamethylene azela ide) or poly(hexamethylene noandiamide) , nylon 6,10 or poly(hexamethylene sebacamide) or poly(hexamethylene decanediamide) , nylon 6,12 or poly(hexamethylene dodecanoamide) or nylon 4 or poly(..-butyrolactam) , nylon 7 or poly(7- aminoheptanoic acid) or poly(7-aminooenanthylic acid) , nylon 8 or poly(8-aminocaprylic acid) or poly(8-amino
  • PARNs result when an aromatic residue or unit is substituted in whole or in part for an aliphatic residue or unit in an aliphatic nylon polymer.
  • substitution of all of the adipic acid [HOOC-(CH 2 ) 4 - COOH] residues in nylon 6,6 by those from mixtures of about 50-70% terphthalic acid (TA, or p-HOOC- C 6 H 5 -COOH) /-50-30% isophthalic acid (IA, or m-HOOC- C 6 H 5 -COOH) gives suitable PARNs which are high- melting, partly crystalline nylons 6,TA-co-6, IA or poly(hexamethylene tere-coisophthalamides) .
  • PARNs are partly crystalline nylons 6,6- co-6,-TA, nylons 6,6-co-6,IA, nylons 6,6-co-6,-TA- co-6,IA, and other similar PARNs, including partly crystalline PARNs wherein some or all of the diamine residues have aromatic character and those containing lactam residues, such as nylons 6-co- 6,6-co-6,TA.
  • copolyamides are also suitable.
  • block copolymers are also suitable.
  • graft copolymers are also suitable.
  • Particulate fillers such as stabilizing fillers and solid pigments, used in the present invention include conventional carbon blacks and other pigments. Such materials typically have particle sizes ranging from about 20 to about 100 nanometers (run) .
  • Carbon black is usually present in molding compositions in small amounts as a colorant. Carbon black may also be used in higher amounts (e.g. , two weight percent loadings) in order to stabilize the resulting molding compositions against ultra-violet radiation by minimizing the absorption of light.
  • plasticizers which are used to wet the particulate fillers, such as carbon black, are those plasticizers conventionally used with polyamides.
  • plasticizers which are well known in the art, include phthalates such as diundecylphthalate, dioctyl phthalate, dibutoxyethyl phthalate, butylbenzyl phthalate, dibutyl phthalate, etc.; sulfonamides such as cyclohexyl-p-toluene sulfonamide, N-ethyl-p-toluene sulfonamide, N-ethyl-o,p toluenesulfonamide, o,p Toluene sulfonamide, etc.
  • trimellitates such as trioctyltrimellitate, tri n-hexyl trimellitate, triisodecyl trimellitate, triisononyl trimellitate, n-octyl-n-decyltrimellitate, etc; epoxidized unsaturated fatty esters; partially hydrogenated terphenols; and other plasticizers used for polyamides.
  • the oil absorption value for the particulate fillers of the present invention is a function of the surface and chemical nature of the filler surface and can be readily determined by reference to American Society for Testing and Materials (ASTM) test methods.
  • ASTM American Society for Testing and Materials
  • the oil absorption value for carbon black is readily determined by ASTM D-2414-93 and the oil absorption value for other pigments by ASTM D-1483-84 (Reapproved 1989) and ASTM D-1483-60. Determination of the oil absorption value allows the proper amount of particulate filler and plasticizer to be blended so as to provide a filler that is dry and free flowing but not dusty.
  • the presence of significant amounts of plasticizer may be detrimental to the properties of the molded polyamide article in certain applications.
  • the oil absorption value of the filler By determining the oil absorption value of the filler and by using an amount of plasticizer that is within about 60 to about 110 percent, and preferably within about 70 to about 90 percent and more preferably within about 75 to about 85 percent of the oil absorption value, one is able to prepare a wetted filler while using an optimum amount of the plasticizer.
  • the particulate filler of the present invention is preferably wetted with the plasticizer in a powder mixer such as a Henschel mixer.
  • a powder mixer such as a Henschel mixer.
  • the mixer is turned on to low speed (- 430 rpm) and the plasticizer introduced into the mixer in finely divided form.
  • the mixer is turned on to high speed (- 860 rpm) for an additional minute and then stopped.
  • cooling water be circulated through the jacket of the mixer throughout the process.
  • high speed mixing be minimized as described above. It is further preferred that process temperatures and the temperature of the wetted product be maintained at or below 45°C.
  • a preferred polyamide molding composition of the present invention contains:
  • a more preferred molding composition comprises:
  • trioctyltrimellitate plasticizer from about 0.5 to about 5% by wt. of trioctyltrimellitate plasticizer.
  • the polyamide molding composition of the present invention may also advantageously contain a heat stabilizer component.
  • heat stabilizer components preferably contain from about 40 to about 200 ppm copper and more preferably contain from about 50 to about 120 ppm copper.
  • Nylon 6,6 - used in Examples A, B and C was Vydyne* 21 nylon available from Monsanto Chemical Co., 800 N. Lindbergh Blvd., St. Louis, MO 63167.
  • Raven C - is carbon black from Columbian Chemicals Co., 1600-T Parkwood Circle, Suite 400, Atlanta, GA 30339 (18 to 20 nanometers (run) in size) .
  • Additive 1 - is a 25% carbon black concentrate in nylon obtained from Americhem, Inc., 225 Broad Blvd., East, Cuyahoga Falls, OH 44221.
  • Additive 2 - is a 25% phthalocyanine blue concentrate in nylon prepared by extruding a blend of 25% phthalocyanine blue and 75% nylon 6,6 (% by wt.).
  • Additive 3 - is a heat stabilizer package of 84.5% Potassium Iodide, 10.5% Cuprous Iodide, 5% Aluminum Distearate (% by weight) .
  • Additive 4 - is aluminum distearate which is used as an external lubricant.
  • Control C - is a commercial weather stable black nylon molding composition available from Monsanto Chemical Co. as Vydyne 25 WSP-F. It is the system described in U.S.P. 4,518,728 to Pollard.
  • Control D - is a commercial weather stable black nylon molding composition available from duPont Chemicals, 1000-T Market St., Wilmington, DE 19898 as Zytel FE-3664.
  • the oil absorption value for the Raven C carbon black was determined to be 114.
  • the amount of TOTM plasticizer used was 80% of the oil absorption value.
  • TSE twinscrew extruder
  • the extruded strands were cooled in a water bath and then pelletized.
  • the pellets were subsequently dusted with an external lubricant (aluminum distearate) and packed into appropriate containers ready for molding.
  • the extrusion process may also be carried out by feeding the wet carbon black and the nylon into the extruder using separate feeders.
  • Molding of the Blend Molding of the finished product was performed on a Newbury 200 (283 gram barrel capacity) molding machine utilizing a family mold which produced a variety of test specimens. Molding conditions used were more or less standard Nylon 6,6 conditions which include: set temperature about 295°C, mold temperature 93°C, injection time - l sec, hold and clamp closed time about 15 seconds each, injection pressure about 5.5 MPa, hold pressure about 4.8 MPa, back pressure about 0.34 MPa, screw rpm about 120. The moisture content of the pellets was in the range of from 0.11 to 0.17%. It is believed that the plasticizing effect of TOTM allows the material to be molded at lower temperatures (275-285 ⁇ C) with slightly increased injection and hold pressures. The above molding conditions were selected because they produced a good balance of properties and are similar to those conventionally used by molders of nylon 6,6 products.
  • the specimens to be tested were separated from the rest of the family of parts, allowed to cool, sealed in polyethylene bags to minimize moisture pick up and hermetically sealed in foil lined bags until tested.
  • test specimens were tested on the following day in a "dry as molded” (DAM) condition.
  • Notched Izod Impact (determined using 0.32 cm thick x 1.27 cm wide x 12.7 cm long specimen bars cut into 6.35 cm long bars to provide two pieces for testing: Gate end (GE)- the piece closest to gate) - ASTM D256-88 using a machined 0.025 cm radius notch in bar. Measurements in Joules per meter (J/m) .
  • Mold Shrinkage (determined using 0.32 cm thick x 1.27 cm wide x 12.7 cm long end gated specimen bars. Specimen bars, sealed upon molding, were equilibrated at 23°C for 24 hours and then the lengths of the bars were measured to within 0.0013 cm and recorded. The difference between the bar length and the length of the mold cavity (12.9134 cm) was then determined for 5 specimen bars and the average used to compute the actual mold shrinkage.) Measurements in cm/cm.
  • a moldability index is the length of the elongated flow path that is filled before solidification of the injected molten polymer composition at specified molding conditions, i.e., volumetric injection rate, mold temperature, polymer melt temperature and mold volume.
  • the mold configuration used had a half round profile extended in spiral or serpentine shapes.
  • the moldability index of the molding compositions of this invention is characterized by "Spiral Flow", which is the length of the spirally-elongated, half-round mold that is filled with molten polymer composition under the injection molding conditions specified below.
  • the mold had a flat surface with a round broach having a radius of 2.77 mm, a depth of 2.77 mm and a length of at least 42 cm.
  • a 5 to 15 cm long runner was connected from a 4 mm (diameter) sprue to the mold at the beginning of the spiral.
  • the runner had a cross sectional area of between 2 and 4 times the cross-sectional area of the half round mold.
  • injection pressure 4.83 MPa hold pressure: 4.14 MPa back pressure: 0.21 MPa barrel temperature: 300°C mold temperature: 93°C injection cycle: injection time: 2 seconds hold time: 10 seconds cooling time: 10 seconds
  • Shot size was set at 1.25 which provided a cushion of 0.5.
  • Spiral Flow was measured after equilibrating the molding cycle (e.g., after 30 cycles) and was determined as the average half round injection length of 20 consecutive moldings. A minimum of 30 molded specimens were discarded between samples. The length of spiral flow was measured to the nearest 0.64 cm.
  • Peak Melting Point, Peak Recrystallization Point, % Crystallinity and Heat of Fusion were derived from differential scanning calorimetry on a Perkin Elmer DSC-7 calorimeter, in an inert atmosphere (nitrogen purged at 20 ml/min) at a heating/cooling rate of 20°C/min. Heat of fusion was measured from the area under the derived melting endotherm and the % crystallinity was based on the heat of fusion value of 188.28 J/g for 100% crystallinity as set forth in Uournal of Polymer Science, Part A, p. 2697 (1963) .
  • Flammability per Underwriters Laboratory Test No. UL-94 (vertical burn) - specimens (at specified thicknesses, 0.33 cm, 0.15 cm, 0.08 cm) tested for flammability were supported from the upper end with the longest dimension vertical, by a clamp on a ring stand so that the lower end of the specimen was one centimeter above the top of a burner tube. The burner was then placed remote from the sample, ignited and adjusted to produce a blue flame two centimeters in height.
  • test flame was placed centrally under the lower end of the test specimen and allowed to remain for 10 seconds. The test flame was then withdrawn, and the duration of flaming or glowing combustion of the specimen noted. If flaming or glowing combustion of the specimen ceased within 30 seconds after removal of the test flame, the test flame was again placed under the specimen for 10 seconds. The test flame was again withdrawn, and the duration of flaming or glowing combustion of the specimen noted.
  • Materials classified as V-2 did not have any specimens that burned with flaming combustion for more than 30 seconds after either application of the test flame; did not have a total flaming combustion time exceeding 250 seconds for the 10 flame applications for each set of five specimens; did not have any specimens that burned with flaming or glowing combustion up to the holding clamp; were permitted to have specimens that dripped flaming particles that ignited the surgical cotton; and did not have any specimens with glowing combustion that persisted for more than 60 seconds after the second removal of the test flame.
  • Peak Melting Point (°C) 259 259.2 258.6 258-2
  • Kev b.i.g. - broken in gate.
  • the molding compositions of the present invention exhibit improved processability and improved physical properties as compared to the weather stable black nylon molding compositions of Controls C and D.
  • the improved processability of Examples A and B is demonstrated by the peak recrystallization points.
  • the 2 to 5° difference in peak recrystallization points denotes the ability of the present inventive compositions to set faster in the mold.
  • the improved physical properties of Examples A and B are demonstrated by the heat distortion or deflection temperatures, tensile strengths at yield and % elongation at fail values obtained.
  • the present inventive molding compositions containing a heat stabilizing component demonstrate, upon heat aging, a full retention of tensile strength and elongation, unlike Control D.
  • the molding compositions of the present invention exhibit comparable flammability results to those of Controls C and D.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

L'invention porte sur un procédé permettant d'améliorer la facilité d'utilisation ainsi que les propriétés physiques de polyamides chargées sans toutefois en affecter l'inflammabilité; le procédé consiste à imprégner des particules de charge (noir de fumée par exemple) à l'aide d'un plastifiant représentant entre 60 et 110 % de la capacité maximale d'absorption de la charge, à mélanger la charge ainsi imprégnée avec les polyamides, puis à couler ou extruder le mélange pour en faire un article moulé.
PCT/US1996/001762 1995-02-15 1996-02-09 Procede d'amelioration des proprietes de polyamides chargees WO1996026242A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US38910195A 1995-02-15 1995-02-15
US08/389,101 1995-02-15

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WO1996026242A2 true WO1996026242A2 (fr) 1996-08-29
WO1996026242A3 WO1996026242A3 (fr) 1996-10-17

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1092622A (en) * 1963-11-12 1967-11-29 Monsanto Co Process for producing pigmented nylon filaments
US3945978A (en) * 1973-05-12 1976-03-23 Chemische Werke Huels Aktiengesellschaft Process for the production of pourable, pulverulent filler mixtures containing plasticizer oils
US4277288A (en) * 1978-10-06 1981-07-07 Ciba-Geigy Corporation Fluidized granulation of pigments using organic granulating assistant
US4391936A (en) * 1980-11-20 1983-07-05 E. I. Du Pont De Nemours And Company Molding blends
US4518728A (en) * 1984-04-04 1985-05-21 Monsanto Company Carbon black filled nylons modified for improved toughness

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1092622A (en) * 1963-11-12 1967-11-29 Monsanto Co Process for producing pigmented nylon filaments
US3945978A (en) * 1973-05-12 1976-03-23 Chemische Werke Huels Aktiengesellschaft Process for the production of pourable, pulverulent filler mixtures containing plasticizer oils
US4277288A (en) * 1978-10-06 1981-07-07 Ciba-Geigy Corporation Fluidized granulation of pigments using organic granulating assistant
US4391936A (en) * 1980-11-20 1983-07-05 E. I. Du Pont De Nemours And Company Molding blends
US4518728A (en) * 1984-04-04 1985-05-21 Monsanto Company Carbon black filled nylons modified for improved toughness

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