Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers

Definitions

• This invention relates to polyamide resin compositions having high impact resistance, high energy absorption characteristics, excellent moldability and coating properties, and low specific gravity.
• the compositions are useful in the production of the molded products requiring such characteristics.
• EPDM ethylene-propylene terpolymer
• polyamide resin compositions which are based on semi- or non-polyamides and compounded with EPDM, because of their high impact resistance, are suitable for the production of the molded products requiring impact resistance. If the products are molded thinner to reduce the weight, however, their elongation at break becomes low thus leading to a breakage of the molded products by small external force. Therefore, polyamide resin compositions have been demanded which have high elongation at break and nevertheless have high rigidity, thus exhibiting excellent energy absorption when an external force is applied.
• the present invention provides a polyamide resin composition with high impact resistance and high energy absorption characteristics which consists of a polymer blend comprising 82 to 93% by weight of a non- crystalline resin, 2 to 12% by weight of EPDM, and 2.5 to 6% by weight of a thermoplastic, semicrystalline polyamide resin.
• the invention also provides a polyamide resin molded product wherein such polyamide resin composition is used in the production of the molded parts requiring the energy absorption characteristics.
• Fig. 1 is a graph showing a change in breaking energy relative to a change in the content of EPDM and 66 nylon in the polyamide resin composition.
• Fig.2 is a plan view of a helmet molded from the polyamide resin composition of the present invention.
• Fig.3 is a sectional view taken substantially along the lines I-I of Fig.2.
• a non-crystalline polyamide resin a principal component of the present polyamide resin composition, is a group of particular polyamides wherein almost no crystallization of polymer occurs or the rate of crystallization is very small, which is also called a transparent nylon.
• the non-crystalline resin as defined herein is characterized by transparency due to non-crystalline property, provides a transparent molded article under a conventional condition of melt molding in which no loss of clarity occurs by after-crystallization upon heat treatment and water absorption treatment and does not have a definite melting point and also a measurable heat of fusion.
• the heat of fusion is conveniently measured by a differential scanning calorimeter (DSC). Suitable calorimeter is 990 thermal analysis apparatus manufactured by E. I. du Pont de Nemours and Company.
• non-ciystalline polyamide resin those having less than 1 cal/g of heat of fusion as measured by this apparatus are defined as a non-ciystalline polyamide resin.
• Processes of producing such non-crystalline polyamide resins can include those by the use of particular monomers or by copolymerization and in combination therewith.
• a structure segment to inhibit a crystallization i.e., a monomer component containing a side chain to provide a polymer chain with its irregularity and a ring structure such as cyclohexane and phenol rings.
• dicarboxylic acids such as adipic acid, sberic acid, azelaic acid, sebacic acid, dodecanoic diacid, terephthalic acid, isophthahc acid and cyclohexane- 1,4-dicarboxylic acid; caprolactam, lauric lacta or ring open products thereof, i.e., c., ⁇ - amino carboxylic acid; and diamines such as 1,6-hexamethylenediamine, trimemyl-l,6-hexamethylenediamine, 1,3-or 1,4- bis(_iminomethyl)cyclohexane, bis(p-aminocyclohexyl)methane(or 4,4'- ⁇ amino-dicyclohe- ylenemethane), 4,4'
• non-crystalline polyamide resins are recited below.
• a) Polyamides prepared from hex_unethylenediamine and a mixture of 55-100% by weight of isophthahc acid and 45-0% by weight of terephthalic acid based on the total weight of the acids b) Polyamides prepared from a mixture of 70-100% by weight of 2,2,4-and 2,4,4-trimemylhexamethylenediamine and 30-0% by weight of hexamethylenediamine(based on the total weight of the diamines) and a mixture of 0-100% by weight of terephthalic acid and 100-0% by weight of isophthahc acid(based on the total weight of the acids), c) Polyamides prepared from i) an alicyclic diamine of 8-20 carbon atoms containing at least one cyclohexyl component, ii) 50-100% by weight of isophthahc acid 50-0% by weight of terephthalic acid, 10-50% by weight
• the second component constituting the polyamide resin composition of the present invention refers to a terpolymer prepared by subjecting to stereospecif ⁇ c polymerization ⁇ -olefins of 3-6 carbons containing ethylene and propylene in the presence of dienes as a third component.
• the terpolymers include various types depending on a ratio of ⁇ -olefins to the third component and the kind of the third component.
• a rubber-like elastomer is preferred comprising 30-70% of ethylene, 60-25% of ⁇ -olefins of 3-6 carbons containing propylene and 10-5% of dienes.
• the dienes constituting the third component of EPDM include divinylbenzene, 1,4-cyclohexadiene, cyclooctadiene, dicyclopentadiene, ethylidene norbomene, 1,4-hexadiene, butadiene, isoprene or the like, but limiting thereto. Any dienes can be used which are copolymerized with ethylene and propylene or ⁇ -olefins other than propylene to produce a rubber-like elastomer.
• EPDM examples include copolymers of eftylene/propylene/divinyl benzene, ethylene/propylene/1,4- cyclohexadiene, ethylene/propylene/cyclooctadiene, ethylene/propylene/dicyclopentadiene, ethylene/propylene/ethylidene norbomene, ethylene/propylene/l,4-hexadiene, ethyIene/propylene/1,3- butadiene and ethylene/propylene/isoprene.
• EPDM may be grafted with minor amount of fumaric acid, maleic acid, monoalkylesters of these acids wherein the alkyl group contains 1-3 carbon atoms or maleic anhydride, examples of which can include copolymers of ethylene/propylene/l,4-hexadiene grafted with maleic anhydride, ethylene/propylene/l,4-hexadiene grafted with fumaric anhydride, ethylene/propylene/l,4-hexadiene/norbornadiene grafted with maleic anyhydride, ethylene/propylene/l,4-hexadiene/norbornadiene grafted with maleic monoethyl ester, ethylene/propylene/1,4- hexadiene/norbornadiene grafted with fumaric acid, ethylene /propylene/5- ethylidene-2-norbornene grafted with fumaric acid, ethylene/propylene/d
• EPDM may be used alone to corporate in the non- crystalline polyamide resins. More than two different EPDM may be used in admixture therewith. Further, those EPDM can be used in admixture with minor amount of other polymers or copolymers such as butadiene/acrylonitrile copolymer, styrene/maleic anhydride copolymer, ethylene/propylene copolymer, ethylene/maleic anhydride copolymer, polyethylene, butyl a ⁇ rylate/monoethyl fumarate copolymer, ethylene/methyl methacrylate copolymer, ethylene/isobutyl acrylate/methacrylic acid copolymer and metallic salts thereof.
• other polymers or copolymers such as butadiene/acrylonitrile copolymer, styrene/maleic anhydride copolymer, ethylene/propylene copolymer, ethylene/maleic anhydride copolymer, polyethylene,
• thermoplastic semicrystalline polyamide resin which is the third component constituting the polyamide resin composition of the present invention is characterized by definite melting point having a measurable heat of fusion.
• the resins having a heat of fusion exceeding 1 cal/g as measured on differential scanning calorimeter are defined as thermoplastic semicrystalline polyamide resins in the present invention.
• the semicrystalline 66 nylon polyamide having a molecular weight of about 17000 has a heat of fusion of about 10 cal/g.
• Semicrystalline polyamide resins are known. They can be prepared from the condensation in equimolar amounts of an ahphatic saturated dicarboxyhc acid of 4-12 carbons having a molecular weight exceeding 10000 and an ahphatic diamine of 2-12 carbons.
• the diamine may be used if desired, in the amount to provide in the polyamide an amine terminal group in excess of a carboxyl terminal group.
• the dicarboxyhc acid may be used in the amount to provide an acid terminal group in excess.
• the polyamides can also be prepared from the derivatives of the dicarboxyhc acid and diamine such as esters, acid chlorides and amine salts thereof.
• Representative ahphatic dicarboxyhc acids which are used for the production of polyamides include adipic acid, pimeric acid, azelaic acid, sberic acid, sebacic acid and dodecanedionic acid.
• Representative ahphatic diamines include hexamethylenediamine and octamethylenediamine.
• the polyamides can be prepared from the autocondensation of lactam.
• polyamides examples include polyhexamethylene adipamide(66 nylon), polyhexamethylene azeramide(69 nylon), polyhexamethylene sebacamide(610 nylon), polyhexamethylene dodecanoamide(612 nylon), polybis(p- aminocyclohe-_yl)me_hanedodecanoamide or polyamides prepared fromthe ring opening polymerization of lactam such as polycaprolactam(6 nylon) and polylauryl lactam.
• lactam such as polycaprolactam(6 nylon) and polylauryl lactam
• polyamides prepared from the polymerization of at least one amine and acid used for the production of said polymers for example polymers from adipic or sebacic acid and hexamethylenediamine.
• the blends of polyamides such as a blend of 66 nylon and 6 nylon or the copolymers such as a copolymer of nylon 66/nylon 6 are also included.
• the polyamide resin compositions of the present invention may contain if necessary stabilizers, pigments, fillers and other additives usually used in such resin composition, in addition to the non-crystalline polyamide EPDM and the thermoplastic semicrystalline polyamide resins.
• the polyamide resin compositions of the present invention can be prepared by mixing the non-crystalline polyamide resin EPDM and the thermoplastic semicrystalhne polyamide resins in the prescribed proportion, if necessary with the additives and milling it in a double-screw extruder. The milling is performed at a temperature above the melting point of the non- crystalline polyamide resin used, usually in the range of 200°C-300°C.
• the polyamide resin compositions as prepared by milling are molded immediately as they are or formed into chips and molded into a desired molded product using suitable injection or extrusion molding machine.
• the polyamide resin compositions may be molded optionally by compression molding means.
• 61 stands for a unit of hexamethylene ⁇ amine(HMD) and isophthahc acid(I).
• 6T stands for a unit of HMD and terephthalic acid(T).
• PACM I stands for a unit of bis(p-_umnocyclohexyl)methane(PACM) and I.
• PACM T stands for a unit of PACM and T.
• the above polyamide resin was prepared in the following manner.
• the concentrated solution was placed into an autoclave to which were added 7.2 lbs. of glacial acetic acid and polyethylene oxide.
• the salt solution was heated and the pressure was elevated to 250 psig. Excessive water was flow out gradually while maintaining that pressure.
• the pressure was dropped gradually to normal pressures within 90 minutes and the content of the autoclave was maintained at normal pressures for about 45 minutes.
• the polymer was extruded from the autoclave under a nitrogen pressure, cooled was cut into a pellet. The inherent viscosity was 0.73. This polymer was coated with 0.09% by weight of aluminum distearate lubricant. ii.
• EPDM EPDM used in this example is a mixture comprising (a) 10% of a graft copolymer with Mooney viscosity of 50-60 at 121°C by ASTM D 1646 ML-2 wherein fumaric acid is grafted onto a copolymer of ethylene/propylene/hexadiene/norbornadiene in a weight ratio of 66-70/35- 29/4.1/0.4 to provide a 1.8% fumaric acid grafting and (b) 90% of the copolymer which is not grafted with fumaric acid.
• thermoplastic semicrystalline polyamide resin used in this example is 66-nylon.
• composition comprising 91% by weight of non-crystalline polyamide resin, 6% by weight of EPDM and 3% by weight of 66 nylon was dried, injection-molded to prepare a test piece and measured for tensile strength, elongation, flexural modulus, Uexural strength, Izod value, specific gravity, shrinkage factor and heat deformation temperature.
• the testing methods are recited below.
• Example 1 The same non-crystalline polyamide resin, EPDM and 66 nylon as used in Example 1 were used in different proportions from those in Example 1. That is, a composition comprising 85% by weight of non-crystalline polyamide resin, 10% by weight of EPDM and 5% by weight of 66 nylon was used to prepare a test piece in a similar manner as in Example 1. The test piece was measured for the physical properties. The result is shown in Table 1. The energy absorption characteristics were tested in a similar manner as in Example 1 with the results as shown in Table 2. Comparative Example 1
• Example 1 The same non-crystalline polyamide resin, EPDM and 66 nylon as used in Example 1 were used in different proportions from those in Example 1. That is, a composition comprising 95% by weight of non-crystalline polyamide resin, 3% by weight of EPDM and 2% by weight of 66 nylon was used to prepare a test piece in a similar manner as in Example 1. The test piece was measured for the physical properties. The result is shown in Table 1.
• Example 1 The same non-crystalline polyamide resin, EPDM and 66 nylon as used in Example 1 were used in different proportions from those in Example 1. That is, a composition comprising 81% by weight of non-crystalline polyamide resin, 13% by weight of EPDM and 6% by weight of 66 nylon was used to prepare a test piece in a similar manner as in Example 1. The test piece was measured for the physical properties. The result is shown in Table 1.
• a composition comprising 80% by weight of nylon 66 and 20% by weight of EPDM was used to prepare a test piece in a similar way as in Example 1.
• the test piece was measured for the physical properties. The result in shown in Table 1.
• the following referential example illustrates the production of a helmet molded from the polyamide resin composition of the present invention.
• Figs. 2 and 3 show an example of helmet molded according to the present invention.
• numeral 1 designates a cap shell body having at the bottom an opening 2 for insertion of a head and at the front a sight window 3, at the circumferences of which are provided a welting la, lb of heavy-walled.
• the cap shell body 1 is integrally molded from the afore-described non-crystalline polyamide resin composition.
• the shell cap body 1 is lined on the inside with a liner 4 molded from a formed polystyrene, as indicated with a chain line in Fig. 2.
• the inside of a liner 4 is provided with a soft cushion such as polyurethane (not shown).
• the shell cap body is molded by an injection molding.
• a melted non-crystalline polyamide resin composition is casted into a mold through a gate as shown in Fig.2 with an arrow G.
• the streams of the melted resin within the mold are as shown in Fig. 3 with a solid line arrow and a broken line arrow.
• Such two streams have a difference in the flow rate.
• the stream indicated with the solid line arrow is faster than that with the broken line arrow. Therefore, a gas pocket is apt to occur at the front head indicated at A in the shell cap body structure as shown in Figs.2 and 3. It may be responsible for defective molding.
• a convex lc can result in increased rate of the melted resin flowing from the back to the front along the shell body in the direction of the broken line as shown in Figs.2 and 3, while keeping the front in a filled condition before the resin in the solid line arrow reach the front, thus preventing an occurrence of a gas pocket.
• the non- crystalline polyamide resin compositions of the present invention possess excellent energy absorption characteristics per unit weight, so that the weight of the molded product can be reduced to about 2/3 by reducing its wall thickness while keeping the energy absorption performance of the product.
• the polyamide resin compositions of the present invention possess an impact resistance equal to a prior impact resistant 66 nylon and still have a higher rigidity, so that about 15% reduction in wall thickness of the molded product can result in equal rigidity to prior products, thus meeting the weight-saving of the molded products such as a helmet.

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• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
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• 1991
  • 1991-11-01 JP JP28762591A patent/JPH05125274A/ja active Pending
• 1992
  • 1992-10-29 EP EP92923540A patent/EP0610406A1/en not_active Ceased
  • 1992-10-29 WO PCT/US1992/009216 patent/WO1993009182A1/en not_active Application Discontinuation
  • 1992-10-29 AU AU29271/92A patent/AU2927192A/en not_active Abandoned

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