WO1990003418A1 - Polymer composition and process for producing the same - Google Patents

Polymer composition and process for producing the same Download PDF

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Publication number
WO1990003418A1
WO1990003418A1 PCT/US1989/004158 US8904158W WO9003418A1 WO 1990003418 A1 WO1990003418 A1 WO 1990003418A1 US 8904158 W US8904158 W US 8904158W WO 9003418 A1 WO9003418 A1 WO 9003418A1
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WIPO (PCT)
Prior art keywords
rubber
polyamide resin
hopper
polymer composition
carboxylic acid
Prior art date
Application number
PCT/US1989/004158
Other languages
French (fr)
Inventor
Kunio Iwanami
Kissho Kitano
Kiyotada Narukawa
Kenichi Aoki
Yukihiko Yagi
Takashi Mikami
Original Assignee
Tonen Sekiyukagaku K.K.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP24158788A external-priority patent/JPH0288671A/en
Priority claimed from JP24158688A external-priority patent/JPH0288672A/en
Application filed by Tonen Sekiyukagaku K.K. filed Critical Tonen Sekiyukagaku K.K.
Publication of WO1990003418A1 publication Critical patent/WO1990003418A1/en

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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L53/00Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
    • C08L53/02Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes
    • C08L53/025Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes modified
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02Compositions 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
    • C08L23/16Elastomeric ethene-propene or ethene-propene-diene copolymers, e.g. EPR and EPDM rubbers
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L51/00Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
    • C08L51/006Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to block copolymers containing at least one sequence of polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L51/00Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
    • C08L51/06Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L77/00Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00Polymer mixtures characterised by other features
    • C08L2205/03Polymer mixtures characterised by other features containing three or more polymers in a blend
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2666/00Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
    • C08L2666/02Organic macromolecular compounds, natural resins, waxes or and bituminous materials
    • C08L2666/14Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
    • C08L2666/20Macromolecular compounds having nitrogen in the main chain according to C08L75/00 - C08L79/00; Derivatives thereof

Definitions

  • the . present invention relates to a polymer composition composed mainly of a polyamide resin and -rubber, particularly a [fiber-reinforced] polymer composition composed mainly of a polyamide resin and rubber, optionally fiber reinforced, having balanced superior mechanical properties, heat resistance, impact resistance, and oldability, and also to a process for producing the same.
  • Bac crround Art composed mainly of a polyamide resin and -rubber, particularly a [fiber-reinforced] polymer composition composed mainly of a polyamide resin and rubber, optionally fiber reinforced, having balanced superior mechanical properties, heat resistance, impact resistance, and oldability, and also to a process for producing the same.
  • Polyamide resins are light in weight and superior in mechanical properties, heat resistance, wear resistance, and chemical resistance.
  • nylon-6 and nylon-66 which are superior especially in strength and heat resistance.
  • the moldings of polyamide resin have a disadvantage that they do not have sufficient impact resistance.
  • Japanese Patent Laid-open No. 6693/1975 a rubber-reinforced polyamide composed of (A) polyamide resin, (B) crosslinked elastomer having epoxy and oxy functional groups, and (C) fine particle filler (with the ratio of component (A) to component (B) being 100:6 to 100:70 by weight).
  • said polyamide resin forms the continuous phase and said elastomer forms the dispersion phase, with the two phases forming an interface in which the amide group of the polyamide resin and the epoxy and oxy functional groups of the elastomer chemically bond each other.
  • a disadvantage of this rubber-reinforced polyamide is that it does not have the well-balanced mechanical strength, heat resistance, impact resistance, and moldability because it is composed of polyamide resin and modified elastomer, which are excessively compatible with each other, and hence it has the equalized properties of the two constituents.
  • Japanese Patent La id-open Japanese Patent La id-open
  • polyamide composition which is composed of (A) 50-99 parts by weight of polyamide resin and (B) 50-1 parts by weight of modified polyolefin or modified polyolefin elastomer formed by adding 0.001-10 ol % of at least one compound selected from the group consisting of alicyclic carboxylic acid having a cis-type double bond in the ring and a function ⁇ tl derivative thereof to a polyolefin or polyolefin elastomer. Further, there is disclosed a composition which is composed of said polyamide composition and an unmodified polyolefin. In one embodiment glass fiber is also included.
  • the polyamide composition disclosed in Japanese Patent Laid-open No. 165952/1980 does not have the well-badanced mechanical properties, heat resistance, impact resistance, and moldability because of the excessive compatibility of the polyamide resin and modified polyolefin. It is an object of the present invention to provide a polymer composition which has well-balanced heat resistance and impact resistance, with the polyamide resin exhibiting its characteristic properties, especially heat distortion resistance, and the rubber exhibiting its good impact resistance.
  • the present inventors carried out a series of researches which led to the finding that it is possible to obtain a polymer composition which exhibits well-balanced mechanical strength, heat resistance, impact resistance, and moldability while retaining the good heat distortion temperature of polyamide resin and the good impact resistance of rubber, if a polyamide resin is incorporated with a rubber and an unsaturated carboxylic acid-modified rubber so as to form a specific morphology in which the rubber uniformly disperses as the domain phase having a specific diameter in the matrix phase of the polyamide resin.
  • the present invention was completed based on this finding.
  • the gist of the present invention resides in a polymer composition which comprises a polyamide resin, rubber, unsaturated carboxylic-acid modified rubber, and, optionally, a glass fiber filler said polyamide resin forming the continuous matrix phase and said rubber forming the uniformly dispersed domain phase having an average diameter of 0.1-5 _ .
  • the polymer composition is produced by a process which comprises feeding said polyamide resin, rubber, and unsaturated carboxylic acid-modified rubber to a twin-screw extruder provided with a hopper, vacuum vent, and die outlet (arranged consecutively) and having a length-to-diameter ratio (I D) of 25 and above through said hopper, intensively mixing said components in at least one set of a first kneading zone constructed of consecutive four or more kneading discs having an I n of 1/4 to 2/8 before said components reach the point of I D 15 downstream from said hopper, and intensively mixing said components again in at least one set of a second kneading zone constructed of consecutive four or more kneading discs having an I D of 1/4 to 1/8 before said components reach the point short of said vacuum vent and beyond the point of I D - ⁇ > downstream from said hopper.
  • a twin-screw extruder provided with a hopper, vacuum vent, and die outlet (arranged consecutive
  • a second hopper, to be used for the addition of glass fiber should be included at the point I D 15-20 downstream from the first hopper, but upstream of the vacuum vent.
  • the glass fiber is thus added after the intensive mixing in the first kneading zone causes a temperature rise to 280* -320 "C just upstream of the second hopper.
  • Fig. 1 is a partial schematic sectional view showing an example of the twin-screw extruder used for producing the fiber-reinforced polymer composition of the present invention according to the process of the present invention.
  • Fig. 2 is a partial enlarged view showing the kneading zone of the twin-screw extruder used for the process of the present invention.
  • Fig. 3 is a sectional view showing a pair of kneading discs.
  • Second hopper (optional)
  • the polyamide resin used in the present invention includes polyamide resins formed from an aliphatic, alicyclic, or aromatic diamine (such as hexamethylene dia ine, decamethylene diamine, dodecamethylene diamine. 2,2,4- or 2,4,4-trimethylhexamethylene diamine, 1,3- or l,4-bis(aminomethyl) cyclohexane, bis(p-aminocyclohexylmethane), and m- or p-xylylene diamine) and an aliphatic, alicyclic, or aromatic dicarboxylic acid (such as adipic acid, suberic acid, sebacic acid, cyclohexane dicarboxylic acid, terephthalic acid, and isophthalic acid); polyamide resins formed from an aminocarboxylic acid (such as 6-aminocaproic acid, 11-aminoundecanoic acid, and 12 aminododecanoic acid); polyamide resins formed from a lac
  • Typical examples of the polyamide resin include nylon-6, nylon-66, nylon-610, nylon-9, nylon-6/66, nylon-66/610, nylon-6/ll, nylon-6/12, nylon- 12, and nylon-46. Preferable among them are nylon-6 and nylon-66.
  • polyamides are not specifically limited in molecular weight. Usually, they should preferably have a relative viscosity J7 r (measured in 98% sulfurlc acid according to JIS K6810) of 1.0 and above. Those having a relative viscosity of 2.0 and above are preferable because of their high mechanical strength.
  • the rubber used in the present invention includes natural rubber, ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM), ethylene-butene rubber (EBR), butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (I ⁇ R), hydrogenated styrene-butadiene block copolymer rubber (SEBS), polyisobutylene rubber, acrylic rubber, etc.
  • EPR ethylene-propylene rubber
  • EPDM ethylene-propylene-diene rubber
  • EBR ethylene-butene rubber
  • BR butadiene rubber
  • IR isoprene rubber
  • SBR styrene-butadiene rubber
  • NBR nitrile-butadiene rubber
  • SEBS hydrogenated styrene-butadiene block copoly
  • ethylene-butene rubber EBR
  • EPR ethylene-propylene rubber
  • SEBS hydrogenated styrene-butadiene block copolymer rubber
  • the modified rubber used in the present invention is one which is formed by modifying a rubber with an unsaturated carboxylic acid or an anhydride thereof.
  • unsaturated carboxylic acid or anhydride thereof include monocarboxylic acid (such as acrylic acid and methacrylic acid), dicarboxylic acid (such as maleic acid, fu aric acid, and itaconic acid), and dicarboxylic acid anhydride (such as maleic anhydride and itaconic anhydride).
  • monocarboxylic acid such as acrylic acid and methacrylic acid
  • dicarboxylic acid such as maleic acid, fu aric acid, and itaconic acid
  • dicarboxylic acid anhydride such as maleic anhydride and itaconic anhydride
  • the rubber to be modified with the unsaturated carboxylic acid or anhydride thereof includes those rubbers enumerated above.
  • Preferred rubbers are ethylene-butene rubber (EBR), ethylene-propylene rubber (EPR), and hydrogenated styrene-butadiene block copolymer (SEBS). When used as the rubber component of the modified rubber, these rubbers impart superior impact resistance to the polymer composition.
  • the modified rubber should preferably contain the unsaturated carboxylic acid or derivative thereof in an amount of 0.01-15 vt%. With an amount less than 0.01 wt%, the modified rubber does not sufficiently improve the compatibility of the polyamide resin and rubber. With an amount in excess of 15 wt%, the modified rubber lowers the compatibility of the rubber.
  • the modified rubber can be produced by either the melt-mixing method or the solution method. In the former case, a rubber, unsaturated carboxylic acid (or anhydride thereof) for modification, and catalyst are heated, melted, and mixed at 150-250 "C in an extruder or twin-screw kneader.
  • the catalyst is an ordinary catalyst for radical polymerization.
  • the catalyst incudes peroxides (such as benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, acetyl peroxide, t-butyl peroxybenzoic acid, dicumyl peroxide, peroxybenzoic acid, peroxyacetic acid, t-butyl peroxypivalate, and 2,5-dimethyl-2,5-di-t-butyl peroxyhexyne) and diazo compounds (such as azobisisobutyronitrile).
  • the catalyst should be used in an amount of 1-100 parts by weight for 100 parts by weight of the unsaturated carboxylic acid or anhydride thereof for modification.
  • the polymer composition of the present invention is not specifically limited in the amount of the polyamide resin and rubber component.
  • the polymer composition should contain the polyamide resin in an amount of 30-90 wt%, preferably 50-70 wt%, of the total amount of the rubber components (rubber plus modified rubber) and also
  • the amount of the modified rubber should be related with the amount of the, terminal amine in the polyamide resin so that the rubber forms the domain which has a desired l odiameter.
  • the amount of the modified rubber in the polymer composition should be adjusted so that a molar ratio of 10-1000 is established between the number of moles of the terminal amine and the number of moles of the carboxylic acid group in the modified rubber.
  • 20-Jodified rubber does not sufficiently improves the compatibility, resulting in a polymer composition having low mechanical strength.
  • the preferred molar ratio is 20-200.
  • the content of the modified rubber should be 0.1-20 wt%, preferably 0.5-10 wt%, which meet the above-mentioned
  • the fiber-reinforced polymer composition of the present invention should contain glass fiber in an amount of 10-50 p ⁇ urts by weight for 100 parts by weight of the total amount of the composition excluding glass fiber. With glass fiber in ah amount less than 10 parts by weight, the • fiber-reinforced polymer composition does not have satisfactory heat resistance and mechanical strength. With glass fiber in an amount in excess of 50 parts by weight, the fiber-reinforced polymer composition is so poor in moldability that it cannot be produced easily. A preferred content of glass fiber is 15-40 parts by weight.
  • the glass lOfiber should preferably be in the form of chopped strand or roving, having a fiber diameter of 5-15 ⁇ a. In addition, surface-treated glass fiber is desirable for the improved adhesion to the polyamide resin.
  • the polymer composition of the present invention is lScharacterized by that the polyamide resin forms the continuous matrix phase and the rubber forms the domain phase having an average diameter of 0.1-5 ⁇ a. If the polyamide resin does not form the continuous matrix phase or if the rubber does not form the domain phase having an average
  • the resulting polymer composition will be very poor in heat distortion resistance. If the rubber forms the domain phase having average diameter larger than 5 /an, the resulting polymer composition will be very poor in mechanical properties such as tensile
  • the polymer composition of the present invention may be incorporated with additives such as inorganic filler, heat stabilizer, antioxidant, photostabilizer, flame retardant, plasticizer, antistatic agent, mold release, blowing agent, nucleating agent, and the like.
  • additives such as inorganic filler, heat stabilizer, antioxidant, photostabilizer, flame retardant, plasticizer, antistatic agent, mold release, blowing agent, nucleating agent, and the like.
  • the mixing of the components is accomplished by using a twin-screw extruder which meets the following requirements.
  • a second hopper arranged consecutively after the first hopper is suitable where fiber-reinforced polymer compositions are desired.
  • (c) It should have at least one set of a second kneading zone (constructed of consecutive four or more kneading discs as mentioned above) which is used for intensively mixing the polyamide resin and rubber components again before they reach the vacuum vent.
  • the requirement (a) is supplemented below.
  • the hopper is intended for feeding the polyamide resin, rubber, and modified rubber.
  • the second hopper is intended for feeding glass fiber.
  • the vacuum vent is intended for eliminating the low-molecular weight components which occur during the mixing of the polyamide resin and rubber components.
  • the die outlet is intended for extruding the mixed composition in the form of strand.
  • the requirement (b) is supplemented below.
  • the first kneading zone is intended for intensively mixing the polyamide resin and rubber components. If necessary, a plurality of kneading zones may be installed. Each unit of the first kneading zone should preferably be composed of four or more, especially 4 to 16 consecutive kneading discs having an I/D of 3/4 to 3/8. Each pair of the kneading discs is fixed to two screw shafts such that they rotate as the screws rotate. Each kneading disc has a cam-like shape, so that the distance between paired kneading discs varies as the kneading discs rotate. This exerts intensive mixing on the polyamide resin and rubber components which pass through the space between them.
  • the requirement (c) is supplemented below.
  • the second kneading zone is intended for intensively mixing the polyamide resin and rubber components again, optionally with the glass fiber. It is constructed substantially the same way as the first kneading zone.
  • the twin-screw extruder having the above-mentioned features is constructed as shown in Fig. 1_ According to the preferred structure, it should have:
  • a vacuum vent 4 installed between said hopper 1 and said die 2, or between said hopper 3 and said die 2 where said hopper 3 is included;
  • the temperature of the polyamide resin and rubber should be 250-300 * C during mixing in the twin-screw extruder and at the die outlet, in the case in which 5 glass fiber is not added;
  • the temperature of the polyamide resin and rubber components should be 280-320 * C during mixing in the section I/D 3.5-7.5 upstream from said second hopper; the temperature of the polyamide resin and rubber components should be 260-290 "C during mixing in the other sections; and, the temperature of the polyamide resin and rubber components should be 250-290 *C at the die outlet.
  • the twin-screw extruder should have an I/D ratio of 25 and above. With an I D ratio smaller than 25, the extruder cannot perform complete mixing. A preferred I D ratio is 25 lOtO 35.
  • the first hopper 1, the optional second hopper 3, the vacuum vent 4, and the die 2 may be of the known structure.
  • the vacuum vent 4 should be installed a distance equivalent 15to an I/D 15-20 away from the hopper 1. If the distance between the two is smaller than I/D 15, the extruder does not perform complete mixing and the vacuum vent does not fully produce its effect. If the distance is larger than an I D 20, the extruder is liable to vent-up. 20
  • the distance between the second hopper 3 and the die 2 should be I D 5-20. With a distance shorter than I/D 5, the mixing of the polyamide resin and rubber components is incomplete. With a distance longer than I/D 20, the polyamide resin and 2-rubber components become deteriorated and glass fiber is broken.
  • the distance between the first hopper 1 and the second hopper 3 should be I/D 15-20.
  • the distance between the second hopper 3 and the vacuum vent 4 should be I/D 2.5-10. With a distance shorter than I/D 2.5, the sizing agent of the glass fiber does not melt and the sufficient venting effect is not produced. With a distance longer than I D 10, there is a possibility of vent-up.
  • the first kneading zone 5, 5 * and the second kneading zone 6 each should have a length equivalent to an I/D 1 to 4.
  • the requirement is met by forming the kneading zone from four and more consecutive kneading discs each having a length equivalent to an I/D 3/4 to 3/8.
  • Both the first and second kneading zones have a structure as shown in Fig. 2.
  • the kneading zone N is formed by a plurality of kneading discs 12, 12 ' , ... installed somewhere along the two screws 10, 13_
  • the kneading zone lies between the screw zones S and S • .
  • the kneading discs 12, 12 * , ... are paired and fixed to the two screws.
  • Fig. 3 is a sectional view of a pair of kneading discs 12, 12 * .
  • the individual kneading discs 12, 12 ' have a cam-like peripheral composed of projecting parts 13, 13 ' and circumferential parts 14, 14 ' .
  • a pair of kneading discs axe fixed to the screw shafts (not shown) by means of spline grooves 15, 15 • such that the prOJecting parts 13, 13 • and the circumferential -parts 12, 12 ' face each other. Because of this arrangement, the distance between the paired kneading discs 12, 12 ' greatly increases and decreases as the screws rotate.
  • the structure shown in Fig. 2 has the transition section (seal ring) T downstream from the kneading zone N so that the compound being mixed does not move forward easily beyond the kneading zone.
  • the extruder should have at least one set, preferably two sets, of the first kneading zone and at least one set of the second kneading zone.
  • the extruder does not perform the complete mixing of the polyamide resin and rubber components and hence does not plasticize them sufficiently.
  • the extruder With the second kneading zone 6 shorter than I/D 1 and for compositions not * f___er-reinforced, the extruder will yield a polymer composition in which the rubber domain has uneven particle diameters.
  • the second kneading zone 6 is shorter than I D 1, the polyamide resin and rubber components are cooled as the glass fiber is fed. This presents the smooth mixing of glass fiber, causing surge (pulsation) and hindering 5production.
  • the polyamide resin and rubber should be kept at 250-300 *C during their mixing; otherwise, the desired morphology is not obtained. With an excessively high mixing temperature, the polyamide resin and rubber become deteriorated and do not exhibit their performance.
  • the temperature of the polyamide resin and rubber components should be 280-320 *C in the section which is I D 3.5-7.5 upstream from the second hopper 3; other-wise, the mixing of glass fiber is hindered and surge is liable to occur. With an excessively high mixing temperature, the polyamide resin and rubber components become deteriorated and do not exhibit their performance.
  • the temperature of the polyamide resin and rubber components should be 260-290 * C in other sections.
  • the temperature of the polyamide resin and rubber components should be 250-290 *C at the die outlet.
  • the polyamide resin and rubber components are fed to the first hopper 1 of the above-mentioned twin-screw extruder and are mixed by the two screws running at a rate of 100-300 rp .
  • Glass fiber, where desired, is fed to the second hopper 3, and mixed under the same conditions.
  • the mixed compound is extruded through the die outlet 2 in the form of strand
  • the strand is easily pelletized by a strand cutter.
  • Both the polymer composition and fiber-reinforced composition produced by the above-mentioned twin-screw extruder can be formed into a desired shape by ordinary injection molding.
  • the polymer composition of the present invention has such a morphology that the polyamide resin forms the continuous matrix phase or the polyamide resin constitutes the skeleton of the composition. Therefore, the polymer composition has high heat distortion resistance.
  • the rubber component forms the domain having an average diameter larger than 0.1 ⁇ a so that the rubber component does not become excessively compatible with the polyamide resin. This is important for the polyamide resin skeleton to retain its heat resistance. If the rubber component forms the domain having an average diameter larger than 5 ⁇ m, the surface of the domain is cracked by external stress, which causes the composition to decrease in mechanical properties.
  • the polyamide resin and rubber components, with optionally added glass fiber are mixed using a twin-screw extruder provided with a first kneading zone and a second kneading zone.
  • the extruder performs intensive mixing in a stable manner. The intensive mixing uniformly disperses the difficultly compatible rubber into the polyamide, so that the resulting composition has improved mechanical strength and heat resistance.
  • the resin temperature in the twin-screw extruder was as follows:
  • the twin-screw extruder was run at a screw speed of 200 rpm and the resulting composition was pelletized. After drying, the pellets of the composition were made into test pieces by injection molding and the test pieces were tested cis followsr
  • a polyamide resin, rubber, and modified rubber were dry-blended using a high-speed mixer according to the formulation shown in Table 2.
  • the resulting dry blend was fed to the main hopper of a twin-screw extruder as shown in
  • Fig. 1 Glass fiber (chopped strand having an average diameter of 13 ⁇ m and an average length of 3 mm) was fed to the second hopper according to the formulation shown in
  • the amount of the polyamide resin, rubber, and modified rubber is expressed in terms of wt% on the basis of the total amount of the resin and rubber components.
  • the amount of glass fiber (Table 2) is expressed in terms of wt% on the basis of the total amount of the composition.
  • Example 1 of Table 1 for Table 3
  • Example 1 of Table 2 for Table 4
  • the composition of the present invention has good impact resistance and heat resistance because the rubber forms the uniformly dispersed domain having a diameter in the range of 0.1 to 5 ⁇ m in the nylon matrix phase.
  • the compositions in the Comparative Examples of Table 3 which have the rubber or polypropylene domain outside the specified range or contain no modified-rubber) are poor in heat distortion resistance and impact resistance.
  • the fiber-reinforced composition of the present invention also has good impact resistance and heat resistance because of the rubber forming the uniformly dispersed domain having a diameter in the range of 0.1 to 5 ⁇ m in the nylon matrix phase.
  • the polymer composition pertaining to the present invention has the well-balanced heat distortion resistance, impact resistance, tensile strength, and moldability, because it contains an unsaturated carboxylic acid-modified rubber which promotes the compatibility of polyamide resins and rubbers and it also has the morphology characterized in that the rubber having an average diameter in a specific range is uniformly dispersed in the polyamide resin matrix phase. It has an additional advantage that the production cost is reduced on account of the comparatively high content of polyolefin.
  • compositions of the present invention are suitable for use as mechanical, automotive, and electrical parts and building materials formed by injection molding and extrusion molding.

Abstract

A polymer composition which comprises a polyamide resin, rubber, unsaturated carboxylic-acid modified rubber, and, optionally, a glass fiber filler, said polyamide resin forming the continuous matrix phase and said rubber forming the uniformly dispersed domain phase having an average diameter of 0.1-5 νm, and process for preparation in a twin-screw extruder. The polymer composition is suitable for use as mechanical, automotive, and electrical parts and building materials formed by injection molding and extrusion molding.

Description

Title of the Invention
POLYMER COMPOSITION AND PROCESS FOR PRODUCING THE SAME
Technical Field
The . present invention relates to a polymer composition composed mainly of a polyamide resin and -rubber, particularly a [fiber-reinforced] polymer composition composed mainly of a polyamide resin and rubber, optionally fiber reinforced, having balanced superior mechanical properties, heat resistance, impact resistance, and oldability, and also to a process for producing the same. Bac crround Art
Polyamide resins are light in weight and superior in mechanical properties, heat resistance, wear resistance, and chemical resistance. Among the most popular polyamide resins are nylon-6 and nylon-66 which are superior especially in strength and heat resistance.
Despite the superior mechanical strength, heat resistance, and long-term durability, the moldings of polyamide resin have a disadvantage that they do not have sufficient impact resistance.
The characteristic properties in which polyamide resins are lacking are usually possessed by rubber.
There is disclosed in Japanese Patent Laid-open No. 6693/1975 a rubber-reinforced polyamide composed of (A) polyamide resin, (B) crosslinked elastomer having epoxy and oxy functional groups, and (C) fine particle filler (with the ratio of component (A) to component (B) being 100:6 to 100:70 by weight). In this rubber-reinforced polyamide, said polyamide resin forms the continuous phase and said elastomer forms the dispersion phase, with the two phases forming an interface in which the amide group of the polyamide resin and the epoxy and oxy functional groups of the elastomer chemically bond each other. A disadvantage of this rubber-reinforced polyamide is that it does not have the well-balanced mechanical strength, heat resistance, impact resistance, and moldability because it is composed of polyamide resin and modified elastomer, which are excessively compatible with each other, and hence it has the equalized properties of the two constituents. There is also disclosed in Japanese Patent La id-open
No. 165952 1980 a polyamide composition which is composed of (A) 50-99 parts by weight of polyamide resin and (B) 50-1 parts by weight of modified polyolefin or modified polyolefin elastomer formed by adding 0.001-10 ol % of at least one compound selected from the group consisting of alicyclic carboxylic acid having a cis-type double bond in the ring and a functionεtl derivative thereof to a polyolefin or polyolefin elastomer. Further, there is disclosed a composition which is composed of said polyamide composition and an unmodified polyolefin. In one embodiment glass fiber is also included.
The polyamide composition disclosed in Japanese Patent Laid-open No. 165952/1980 does not have the well-badanced mechanical properties, heat resistance, impact resistance, and moldability because of the excessive compatibility of the polyamide resin and modified polyolefin. It is an object of the present invention to provide a polymer composition which has well-balanced heat resistance and impact resistance, with the polyamide resin exhibiting its characteristic properties, especially heat distortion resistance, and the rubber exhibiting its good impact resistance.
It is another object of the present invention to provide a process for producing such a polymer composition. Summary Of The Invention
In order to achieve the above-mentioned objects, the present inventors carried out a series of researches which led to the finding that it is possible to obtain a polymer composition which exhibits well-balanced mechanical strength, heat resistance, impact resistance, and moldability while retaining the good heat distortion temperature of polyamide resin and the good impact resistance of rubber, if a polyamide resin is incorporated with a rubber and an unsaturated carboxylic acid-modified rubber so as to form a specific morphology in which the rubber uniformly disperses as the domain phase having a specific diameter in the matrix phase of the polyamide resin. The present invention was completed based on this finding. Accordingly, the gist of the present invention resides in a polymer composition which comprises a polyamide resin, rubber, unsaturated carboxylic-acid modified rubber, and, optionally, a glass fiber filler said polyamide resin forming the continuous matrix phase and said rubber forming the uniformly dispersed domain phase having an average diameter of 0.1-5 _ .
The polymer composition is produced by a process which comprises feeding said polyamide resin, rubber, and unsaturated carboxylic acid-modified rubber to a twin-screw extruder provided with a hopper, vacuum vent, and die outlet (arranged consecutively) and having a length-to-diameter ratio (I D) of 25 and above through said hopper, intensively mixing said components in at least one set of a first kneading zone constructed of consecutive four or more kneading discs having an I n of 1/4 to 2/8 before said components reach the point of I D 15 downstream from said hopper, and intensively mixing said components again in at least one set of a second kneading zone constructed of consecutive four or more kneading discs having an I D of 1/4 to 1/8 before said components reach the point short of said vacuum vent and beyond the point of I D -~> downstream from said hopper. A second hopper, to be used for the addition of glass fiber should be included at the point I D 15-20 downstream from the first hopper, but upstream of the vacuum vent. The glass fiber is thus added after the intensive mixing in the first kneading zone causes a temperature rise to 280* -320 "C just upstream of the second hopper.
This application is combined from Ja241,586/88 and Ja241,587/88. The specification has been combined. Claims need to be sorted out and U.S. formatting requirements met. 5 Brief Description of the Drawings
Fig. 1 is a partial schematic sectional view showing an example of the twin-screw extruder used for producing the fiber-reinforced polymer composition of the present invention according to the process of the present invention. 10 Fig. 2 is a partial enlarged view showing the kneading zone of the twin-screw extruder used for the process of the present invention.
Fig. 3 is a sectional view showing a pair of kneading discs.
15 1 . . . First hopper
2 . . . Die
3 . . . Second hopper (optional)
4 . . . Vent
5, 5 ' . . . First kneading zone 6 . . . Second kneading zone 10, 11 . . . Screws 12, 12 ' . . . Kneading discs 20 13, 13 ' . . . Projecting parts
14, 14 * . . . Circumferential parts
15, 15' . . . Spline grooves N . . . Kneading zone
T . . . Seal ring S, S ' . . . Screw
Description Of The Preferred Em_yv- ..τ.<-n.-c.
25 The polyamide resin used in the present invention includes polyamide resins formed from an aliphatic, alicyclic, or aromatic diamine (such as hexamethylene dia ine, decamethylene diamine, dodecamethylene diamine. 2,2,4- or 2,4,4-trimethylhexamethylene diamine, 1,3- or l,4-bis(aminomethyl) cyclohexane, bis(p-aminocyclohexylmethane), and m- or p-xylylene diamine) and an aliphatic, alicyclic, or aromatic dicarboxylic acid (such as adipic acid, suberic acid, sebacic acid, cyclohexane dicarboxylic acid, terephthalic acid, and isophthalic acid); polyamide resins formed from an aminocarboxylic acid (such as 6-aminocaproic acid, 11-aminoundecanoic acid, and 12 aminododecanoic acid); polyamide resins formed from a lactam (such as e-caprolactam and w-dodecalactam); copolymer polyamide resins composed of the above-mentioned components; and mixtures of these polyamide resins. Typical examples of the polyamide resin include nylon-6, nylon-66, nylon-610, nylon-9, nylon-6/66, nylon-66/610, nylon-6/ll, nylon-6/12, nylon- 12, and nylon-46. Preferable among them are nylon-6 and nylon-66.
These polyamides are not specifically limited in molecular weight. Usually, they should preferably have a relative viscosity J7r (measured in 98% sulfurlc acid according to JIS K6810) of 1.0 and above. Those having a relative viscosity of 2.0 and above are preferable because of their high mechanical strength.
The rubber used in the present invention includes natural rubber, ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM), ethylene-butene rubber (EBR), butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IΣR), hydrogenated styrene-butadiene block copolymer rubber (SEBS), polyisobutylene rubber, acrylic rubber, etc.
Preferable among these rubbers are ethylene-butene rubber (EBR), ethylene-propylene rubber (EPR), and hydrogenated styrene-butadiene block copolymer rubber (SEBS). When used as the rubber component, these rubbers impart superior impact resistance to the polymer composition.
The modified rubber used in the present invention is one which is formed by modifying a rubber with an unsaturated carboxylic acid or an anhydride thereof. Examples of the unsaturated carboxylic acid or anhydride thereof include monocarboxylic acid (such as acrylic acid and methacrylic acid), dicarboxylic acid (such as maleic acid, fu aric acid, and itaconic acid), and dicarboxylic acid anhydride (such as maleic anhydride and itaconic anhydride). Preferable among them cure dicarboxylic acids and anhydrides thereof.
The rubber to be modified with the unsaturated carboxylic acid or anhydride thereof includes those rubbers enumerated above. Preferred rubbers are ethylene-butene rubber (EBR), ethylene-propylene rubber (EPR), and hydrogenated styrene-butadiene block copolymer (SEBS). When used as the rubber component of the modified rubber, these rubbers impart superior impact resistance to the polymer composition.
The modified rubber should preferably contain the unsaturated carboxylic acid or derivative thereof in an amount of 0.01-15 vt%. With an amount less than 0.01 wt%, the modified rubber does not sufficiently improve the compatibility of the polyamide resin and rubber. With an amount in excess of 15 wt%, the modified rubber lowers the compatibility of the rubber. The modified rubber can be produced by either the melt-mixing method or the solution method. In the former case, a rubber, unsaturated carboxylic acid (or anhydride thereof) for modification, and catalyst are heated, melted, and mixed at 150-250 "C in an extruder or twin-screw kneader. In the latter case, the above-mentioned starting materials are dissolved in an organic solvent such as xylene and the reaction is carried out at 80-140 *C with stirring. In either case, the catalyst is an ordinary catalyst for radical polymerization. The catalyst incudes peroxides (such as benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, acetyl peroxide, t-butyl peroxybenzoic acid, dicumyl peroxide, peroxybenzoic acid, peroxyacetic acid, t-butyl peroxypivalate, and 2,5-dimethyl-2,5-di-t-butyl peroxyhexyne) and diazo compounds (such as azobisisobutyronitrile). The catalyst should be used in an amount of 1-100 parts by weight for 100 parts by weight of the unsaturated carboxylic acid or anhydride thereof for modification.
The polymer composition of the present invention is not specifically limited in the amount of the polyamide resin and rubber component. For the polyamide resin to form the continuous matrix phase and for the rubber to form the uniformly dispersed domain phase, thereby imparting good heat distortion resistance and impact resistance, the polymer composition should contain the polyamide resin in an amount of 30-90 wt%, preferably 50-70 wt%, of the total amount of the rubber components (rubber plus modified rubber) and also
5 contain the rubber plus modified rubber in an amount of 10-70 wt%, preferably 30-50 wt%.
The amount of the modified rubber should be related with the amount of the, terminal amine in the polyamide resin so that the rubber forms the domain which has a desired lodiameter. In other words, the amount of the modified rubber in the polymer composition should be adjusted so that a molar ratio of 10-1000 is established between the number of moles of the terminal amine and the number of moles of the carboxylic acid group in the modified rubber. With an
15amin_ carboxylic acid molar ratio smaller than 10, the compatibility is so high that the rubber forms the domain having an excessively small diameter. This lowers the heat resistance of the polymer composition. With an amine carboxylic acid molar ratio in excess of 1000, the
20-Jodified rubber does not sufficiently improves the compatibility, resulting in a polymer composition having low mechanical strength. The preferred molar ratio is 20-200. Thus the content of the modified rubber should be 0.1-20 wt%, preferably 0.5-10 wt%, which meet the above-mentioned
2 -requirements.
The fiber-reinforced polymer composition of the present invention should contain glass fiber in an amount of 10-50 pεurts by weight for 100 parts by weight of the total amount of the composition excluding glass fiber. With glass fiber in ah amount less than 10 parts by weight, the fiber-reinforced polymer composition does not have satisfactory heat resistance and mechanical strength. With glass fiber in an amount in excess of 50 parts by weight, the fiber-reinforced polymer composition is so poor in moldability that it cannot be produced easily. A preferred content of glass fiber is 15-40 parts by weight. The glass lOfiber should preferably be in the form of chopped strand or roving, having a fiber diameter of 5-15 μa. In addition, surface-treated glass fiber is desirable for the improved adhesion to the polyamide resin.
The polymer composition of the present invention is lScharacterized by that the polyamide resin forms the continuous matrix phase and the rubber forms the domain phase having an average diameter of 0.1-5 μa. If the polyamide resin does not form the continuous matrix phase or if the rubber does not form the domain phase having an average
2Q__Lameter smaller than 0.1 μm, the resulting polymer composition will be very poor in heat distortion resistance. If the rubber forms the domain phase having average diameter larger than 5 /an, the resulting polymer composition will be very poor in mechanical properties such as tensile
2_strength, fLexural modulus, and impact strength.
For the purpose of property improvement, the polymer composition of the present invention may be incorporated with additives such as inorganic filler, heat stabilizer, antioxidant, photostabilizer, flame retardant, plasticizer, antistatic agent, mold release, blowing agent, nucleating agent, and the like. The polymer composition of the present invention is produced in the manner explained below.
The mixing of the components is accomplished by using a twin-screw extruder which meets the following requirements.
(a) It should have a first hopper, a vacuum vent, and a die outlet arranged consecutively and also have a length to diameter ratio (I D) of 25 and above. A second hopper arranged consecutively after the first hopper is suitable where fiber-reinforced polymer compositions are desired. (b) It should have at least one set of a first kneading zone constructed of consecutive four or more kneading discs having an I/D of 4 to 3/8 which is used for intensively mixing the polyamide resin and rubber components before they reach the point of I/n 15 downstream from the hopper. This first kneading zone is installed upstream from the second hopper where included.
(c) It should have at least one set of a second kneading zone (constructed of consecutive four or more kneading discs as mentioned above) which is used for intensively mixing the polyamide resin and rubber components again before they reach the vacuum vent. The requirement (a) is supplemented below. The hopper is intended for feeding the polyamide resin, rubber, and modified rubber. The second hopper is intended for feeding glass fiber. The vacuum vent is intended for eliminating the low-molecular weight components which occur during the mixing of the polyamide resin and rubber components. The die outlet is intended for extruding the mixed composition in the form of strand.
The requirement (b) is supplemented below. The first kneading zone is intended for intensively mixing the polyamide resin and rubber components. If necessary, a plurality of kneading zones may be installed. Each unit of the first kneading zone should preferably be composed of four or more, especially 4 to 16 consecutive kneading discs having an I/D of 3/4 to 3/8. Each pair of the kneading discs is fixed to two screw shafts such that they rotate as the screws rotate. Each kneading disc has a cam-like shape, so that the distance between paired kneading discs varies as the kneading discs rotate. This exerts intensive mixing on the polyamide resin and rubber components which pass through the space between them.
The requirement (c) is supplemented below. The second kneading zone is intended for intensively mixing the polyamide resin and rubber components again, optionally with the glass fiber. It is constructed substantially the same way as the first kneading zone.
The twin-screw extruder having the above-mentioned features is constructed as shown in Fig. 1_ According to the preferred structure, it should have:
(1) a length-to-diameter ratio (I/D) of 25 and above;
(2) a hopper 1 through which the polyamide resin and rubber components are fed;
(3) a die 2 from which the resulting polymer composition is extruded;
(4) an optional second hopper 3 for glass fiber feeding, which is installed at the point of I/D 15-20 downstream 0 from said first hopper;
(5) a vacuum vent 4 installed between said hopper 1 and said die 2, or between said hopper 3 and said die 2 where said hopper 3 is included;
(6) at least one set (two sets in the example shown) of a 5 first kneading zone 5, 5 ' installed at the point before I/D 15 downstream from said hopper 1, but upstream of said hopper 3 where included;
(7) at least one set of a second kneading zone 5 installed at the point before said vacuum vent 3, but downstream o of said hopper 3 where included; and it should perform the mixing under the following conditions.
(8) the temperature of the polyamide resin and rubber should be 250-300* C during mixing in the twin-screw extruder and at the die outlet, in the case in which 5 glass fiber is not added;
(9) and, when glass fiber is to be added, the temperature of the polyamide resin and rubber components should be 280-320 *C during mixing in the section I/D 3.5-7.5 upstream from said second hopper; the temperature of the polyamide resin and rubber components should be 260-290 "C during mixing in the other sections; and, the temperature of the polyamide resin and rubber components should be 250-290 *C at the die outlet. The twin-screw extruder should have an I/D ratio of 25 and above. With an I D ratio smaller than 25, the extruder cannot perform complete mixing. A preferred I D ratio is 25 lOtO 35.
The first hopper 1, the optional second hopper 3, the vacuum vent 4, and the die 2 may be of the known structure.
For compositions of the invention not fiber-reinforced, the vacuum vent 4 should be installed a distance equivalent 15to an I/D 15-20 away from the hopper 1. If the distance between the two is smaller than I/D 15, the extruder does not perform complete mixing and the vacuum vent does not fully produce its effect. If the distance is larger than an I D 20, the extruder is liable to vent-up. 20 For fiber reinforced compositions of the invention, the distance between the second hopper 3 and the die 2 should be I D 5-20. With a distance shorter than I/D 5, the mixing of the polyamide resin and rubber components is incomplete. With a distance longer than I/D 20, the polyamide resin and 2-rubber components become deteriorated and glass fiber is broken. The distance between the first hopper 1 and the second hopper 3 should be I/D 15-20. The distance between the second hopper 3 and the vacuum vent 4 should be I/D 2.5-10. With a distance shorter than I/D 2.5, the sizing agent of the glass fiber does not melt and the sufficient venting effect is not produced. With a distance longer than I D 10, there is a possibility of vent-up.
The first kneading zone 5, 5 * and the second kneading zone 6 each should have a length equivalent to an I/D 1 to 4. The requirement is met by forming the kneading zone from four and more consecutive kneading discs each having a length equivalent to an I/D 3/4 to 3/8.
Both the first and second kneading zones have a structure as shown in Fig. 2. The kneading zone N is formed by a plurality of kneading discs 12, 12 ' , ... installed somewhere along the two screws 10, 13_ The kneading zone lies between the screw zones S and S . In the kneading zone N, the kneading discs 12, 12 * , ... are paired and fixed to the two screws. Fig. 3 is a sectional view of a pair of kneading discs 12, 12 * . The individual kneading discs 12, 12 ' have a cam-like peripheral composed of projecting parts 13, 13 ' and circumferential parts 14, 14 ' . A pair of kneading discs axe fixed to the screw shafts (not shown) by means of spline grooves 15, 15 • such that the prOJecting parts 13, 13 • and the circumferential -parts 12, 12 ' face each other. Because of this arrangement, the distance between the paired kneading discs 12, 12 ' greatly increases and decreases as the screws rotate. This exerts by far more intensive mixing to the polyamide resin and rubber components (or a mixture of the polyamide resin, rubber, and glass fiber) passing through the kneading discs than the screws do, as the kneading discs 12, 12 - ... are arranged consecutively with the plural pieces. Incidentally, the structure shown in Fig. 2 has the transition section (seal ring) T downstream from the kneading zone N so that the compound being mixed does not move forward easily beyond the kneading zone. The extruder should have at least one set, preferably two sets, of the first kneading zone and at least one set of the second kneading zone.
If the first kneading zone 5, 5 ' does not exist or does not have the sufficient length, the extruder does not perform the complete mixing of the polyamide resin and rubber components and hence does not plasticize them sufficiently.
With the second kneading zone 6 shorter than I/D 1 and for compositions not *f___er-reinforced, the extruder will yield a polymer composition in which the rubber domain has uneven particle diameters. For fiber-reinforced compositions, if the second kneading zone 6 is shorter than I D 1, the polyamide resin and rubber components are cooled as the glass fiber is fed. This presents the smooth mixing of glass fiber, causing surge (pulsation) and hindering 5production.
In the case where there are two or more sets of the first kneading zone 5, 5 ' , its forward end is located I/D 5-15 downstream from the hopper 1 and its total length is equivalent to I D 2-8. In the case where there are two or more sets of the second kneading zone 6, its forward end is located I/D 15-20 downstream from the hopper 1 and its total length is equivalent to I/D 1-4.
For compositions not fiber-reinforced, the polyamide resin and rubber should be kept at 250-300 *C during their mixing; otherwise, the desired morphology is not obtained. With an excessively high mixing temperature, the polyamide resin and rubber become deteriorated and do not exhibit their performance.
For fiber-reinforced compositions, the temperature of the polyamide resin and rubber components should be 280-320 *C in the section which is I D 3.5-7.5 upstream from the second hopper 3; other-wise, the mixing of glass fiber is hindered and surge is liable to occur. With an excessively high mixing temperature, the polyamide resin and rubber components become deteriorated and do not exhibit their performance. The temperature of the polyamide resin and rubber components should be 260-290* C in other sections. The temperature of the polyamide resin and rubber components should be 250-290 *C at the die outlet.
According to the process of the present invention, the polyamide resin and rubber components are fed to the first hopper 1 of the above-mentioned twin-screw extruder and are mixed by the two screws running at a rate of 100-300 rp . Glass fiber, where desired, is fed to the second hopper 3, and mixed under the same conditions. The mixed compound is extruded through the die outlet 2 in the form of strand The strand is easily pelletized by a strand cutter.
Both the polymer composition and fiber-reinforced composition produced by the above-mentioned twin-screw extruder can be formed into a desired shape by ordinary injection molding.
Function of the Invention
As mentioned above, the polymer composition of the present invention has such a morphology that the polyamide resin forms the continuous matrix phase or the polyamide resin constitutes the skeleton of the composition. Therefore, the polymer composition has high heat distortion resistance. According to the present invention, the rubber component forms the domain having an average diameter larger than 0.1 μa so that the rubber component does not become excessively compatible with the polyamide resin. This is important for the polyamide resin skeleton to retain its heat resistance. If the rubber component forms the domain having an average diameter larger than 5 μm, the surface of the domain is cracked by external stress, which causes the composition to decrease in mechanical properties.
According to the process of the present invention, the polyamide resin and rubber components, with optionally added glass fiber, are mixed using a twin-screw extruder provided with a first kneading zone and a second kneading zone. The extruder performs intensive mixing in a stable manner. The intensive mixing uniformly disperses the difficultly compatible rubber into the polyamide, so that the resulting composition has improved mechanical strength and heat resistance.
Examples
The invention will be described in more detail with reference to the following examples. Examples 1 to 18 of Table 1 A polyamide resin, rubber, and modified rubber were dry-blended using a high-speed mixer according to the formulation shown in Table 1. The resulting dry blend was fed to the hopper of a twin-screw extruder having the structure specified below. Screw diameter. 45 mm I/D ratio: 28
Position of vacuum vent: I/D 5.5 upstream from the die First kneading zone: Number: 1 Position: I/D 2-3.5 and I/D 5-6.5 downstream from the hopper Size of kneading disc: I/D = 1/4 Number of kneading discs: 6 Second kneading zone: Number: 1
Position: I/D 7 upstream from the die Size of kneading disc: I/D = 3/4 Number of kneading discs: 4
The resin temperature in the twin-screw extruder was as follows:
270 *C in Examples 1 to 12, 15, and 16 250 *C in Examples 13 and 14
290 "C in Examples 17 and 18
The twin-screw extruder was run at a screw speed of 200 rpm and the resulting composition was pelletized. After drying, the pellets of the composition were made into test pieces by injection molding and the test pieces were tested cis followsr
(1) MFR according to JIS K7210, at 275 *C under a load of 2160 g.
(2) Heat distortion temperature according to JIS K7207. A test piece (simple beam) measuring 110 x 4 x 12.7 mm is heated at a constant rate (2'C/min) under a fixed load (4.6 kg/cm2) and the temperature at which the test piece is bent as much as a prescribed amount (0.25 mm) is recorded. (3) Tensile strength at 23 *C according to JIS K7113.
(4) Flexural modulus at 23 *C according to JIS K7203.
(5) Izod impact strength at 23 *C and -40* C according to JIS K7110.
The results are shown in Table 1. Examples 1 to 18 of Table 2
A polyamide resin, rubber, and modified rubber were dry-blended using a high-speed mixer according to the formulation shown in Table 2. The resulting dry blend was fed to the main hopper of a twin-screw extruder as shown in
Fig. 1. Glass fiber (chopped strand having an average diameter of 13 μm and an average length of 3 mm) was fed to the second hopper according to the formulation shown in
Table 2. 0 The extruder had the same structure specified for the examples of Table 1 except for the additional inclusion of a second hopper. Configuration differences are specified below.
Position of second hopper: I D 10 upstream from the die 15 The temperature of the polyamide resin and rubber components in the twin-screw extruder was as follows:
In the section I D 3.5-7.5 upstream from the second hopper:
290 *C in Examples 1 to 12, 15, and 16
280* C in Examples 13 and 14 20 310* C in Examples 17 and 18
In other sections I/D 7.5-25:
270* C in Examples 1 to 12, 15, and 16
250 *C in Examples 13 and 14
290 *C in Examples 17 and 18 25 The twin-screw extruder was run at a screw speed of 200 rpm and the resulting composition was pelletized and tested as done for the examples of Table 1_ Additional tensile strength and flexural modulus measurements were taken as noted. (3.) Tensile strength at 23*C and 140*C according to JTS
K7113. (2) Flexural modulus at 23*C and 140*C according to JIS K7203. The results are shown in Table 3.
Notes to Tables 1 and 2
(1) The amount of the polyamide resin, rubber, and modified rubber is expressed in terms of wt% on the basis of the total amount of the resin and rubber components. The amount of glass fiber (Table 2) is expressed in terms of wt% on the basis of the total amount of the composition.
(2) "Amiran CM3001N", made by Toray Industries Inc., conteiining 0.034 m i 11 i equivalents/g of terminal amino group measured according to Korshak-Zamyationa method
(back titration method) (Chem. Abs. 40, 4665, '46, ib. 42, 6152, «48)
(3) "A1030BRT", made by Unitica Ltd., containing 0.042 __i__Liequivalents/g of terminal amino group measured according to Korshak-Zamyationa method (as mentioned in
(2) above).
(4) "Unitica Nylon-46", made by Unitica Ltd., containing 0.026 milliequivalents/g of terminal amino group measured according to Korshak-Zamyationa method (as mentioned in (2) above).
(5) "Tafmer A4085", made by Mitsui Petrochemical Industry Co., Ltd.
(6) "Tafmer P0180", made by Mitsui Petrochemical Industry Co., Ltd. (7) "Kraton G1652", made by Shell Chemical Co., Ltd. (8) Polyisobutylene, "Vistanex MML-80", made by Esso Chemical Co., Ltd. (9) Maleic acid anhydride
(10) "MA03FT-2", made by Asahi Fiberglass Co., Ltd. Comparative Examples 1 to 5 of Tables 3 and 4
The same procedures as in Example 1 of Table 1 (for Table 3) and Example 1 of Table 2 (for Table 4) were repeated except that the materials and formulations were changed as shown in Tables 3 and 4. The results are shown in those Tables 3 and 4.
Note to Tables 3 and 4
(1), (2), (5), (6), and (9): same as in Table 3_
(10) J-215, made by Tonen Sekiyukagaku K. K.
It is noted from Tables 1 and 3 that the composition of the present invention has good impact resistance and heat resistance because the rubber forms the uniformly dispersed domain having a diameter in the range of 0.1 to 5 μm in the nylon matrix phase. In contrast to the examples of Table 1, the compositions in the Comparative Examples of Table 3 (which have the rubber or polypropylene domain outside the specified range or contain no modified-rubber) are poor in heat distortion resistance and impact resistance. It is noted from Tables 2 and 4 that the fiber-reinforced composition of the present invention also has good impact resistance and heat resistance because of the rubber forming the uniformly dispersed domain having a diameter in the range of 0.1 to 5 μm in the nylon matrix phase. In contrast to the examples of Table 2, the composition in Comparative Example 1 of Table 4 (which contains polypropylene in place of rubber), the compositions in Comparative Examples 2 and 4 (which have the rubber domain outside the range specified above), and the compositions in Comparative Examples 3 and 5 (which do not contain the _jodified rubber) are poor in heat distortion resistance and impact resistance. Effect of the invention
As mentioned above, the polymer composition pertaining to the present invention has the well-balanced heat distortion resistance, impact resistance, tensile strength, and moldability, because it contains an unsaturated carboxylic acid-modified rubber which promotes the compatibility of polyamide resins and rubbers and it also has the morphology characterized in that the rubber having an average diameter in a specific range is uniformly dispersed in the polyamide resin matrix phase. It has an additional advantage that the production cost is reduced on account of the comparatively high content of polyolefin.
The compositions of the present invention are suitable for use as mechanical, automotive, and electrical parts and building materials formed by injection molding and extrusion molding.

Claims

CLAIMS :
(1) A polymer composition which comprises a polyamide resin, rubber, and unsaturated carboxylic-acid modified rubber, said polyamide resin forming the continuous matrix phase and said rubber forming the uniformly dispersed domain phase having an average diameter of 0.1-5 μm.
(2) A polymer composition as claimed in Claim 1, wherein the ratio of the number of moles of the terminal amine in said polyamide resin to the number of moles of the carboxylic acid group in said unsaturated carboxylic acid-modified rubber is 10-1000.
(3) A polymer composition as claimed in Claim 1, wherein the amount of said polyamide resin is 30-90 wt% and the total amount of said rubber and said unsaturated carboxylic acid-modified rubber is 10-70 wt%.
(4) A polymer composition as claimed in Claim 2, wherein the amount of said polyamide resin is 30-90 wt% and the total amount of said rubber and said unsaturated carboxylic acid-modified rubber is 10-70 wt%.
(5) A polymer composition as claimed in any of Claims 1 to 4, wherein said rubber and the rubber component in said unsaturated carboxylic acid-modified rubber are both ethylene-butene rubber, ethylene-propylene rubber, or hydrogenated styrene-butadiene-block copolymer rubber.
(6) A polymer composition as claimed in Claim 3, which additionally comprises 10-50 parts by weight of glass fiber for 100 parts by weight of the total amount of the composition.
(7) A polymer composition as claimed in Claim 6, wherein the ratio of the number of moles of the terminal amine in said polyamide resin to the number of moles of the carboxylic acid group in said unsaturated carboxylic acid-modified rubber is 10-1000.
(8) A polymer composition as claimed in Claims - or , wherein said rubber and the rubber component in said unsaturated carboxylic acid-modified rubber are both ethylene-butene rubber, ethylene-propylene rubber, or hydrogenated styrene-butadiene-block copolymer rubber.
(9) A process for producing a polymer composition containing a polyamide resin, rubber, and unsaturated carboxylic acid-modified rubber, said process comprising feeding said polyamide resin, rubber, and unsaturated carboxylic acid-modified rubber to a twin-screw extruder provided with a hopper, vacuum vent, and die outlet (arranged consecutively) and having a length-to-diameter ratio (I/D) of 25 and above through said hopper, intensively mixing said components in at least one set of a first kneading zone constructed of consecutive four or more kneading discs having an I/D of 3/4 to 3/8 before said components reach the point of I/D 15 downstream from said hopper, and intensively mixing said components again in at least one set of a second kneading zone constructed of consecutive four or more kneading discs having an I D of 1/4 to 3/8 before said components reach the point short of said vacuum vent and beyond the point of I D 15 downstream from said hopper.
(10) A process for producing a fiber-reinforced polymer composition containing a polyamide resin, rubber, and unsaturated carboxylic acid-modified rubber, said process comprising feeding said polyamide resin, rubber, and unsaturated carboxylic acid-modified rubber to a twin-screw extruder provided with a first hopper and a second hopper, a vacuum vent, and a die outlet (arranged consecutively) and having a length-to-diameter ratio (I/D) of 25 and above through said first hopper, intensively mixing said components in at least one set of a first kneading zone constructed of consecutive four or more kneading discs having an I/D of 3/4 to 3/8 before said components reach said second hopper, thereby raising the temperature of the polyamide resin and rubber components to 280-320 *C at the point upstream from the second hopper, feeding glass fiber to the extruder through said second hopper, and intensively mixing said polyamide resin, rubber components, and glass fiber in at least one set of a second kneading zone constructed of consecutive four or more kneading discs having an I/D of 3/4 to 3/8 before said components reach the point short of said vacuum vent.
(11) A process as claimed in Claim 10, wherein the temperature of the polyamide resin and rubber components is kept at 280-320 *C at the point of I/D 3.5-7.5 upstream from said second hopper and the temperature of the polyamide resin and rubber components is kept at 260-290 *C at the other points.
PCT/US1989/004158 1988-09-27 1989-09-26 Polymer composition and process for producing the same WO1990003418A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP24158788A JPH0288671A (en) 1988-09-27 1988-09-27 Fiber reinforced polymer composition and production thereof
JP63/241586 1988-09-27
JP63/241587 1988-09-27
JP24158688A JPH0288672A (en) 1988-09-27 1988-09-27 Polymer composition and production thereof

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EP0875534A1 (en) * 1997-05-02 1998-11-04 Dsm N.V. Thermoplastic elastomer composition adhesion to polar materials
WO1998050465A1 (en) * 1997-05-02 1998-11-12 Dsm N.V. Thermoplastic elastomer composition adapted for adhesion to polar materials
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EP1086991A1 (en) * 1999-09-24 2001-03-28 Riken Vinyl Industry Co., Ltd. Thermoplastic elastomeric resin composition and a granule thereof
US6300418B1 (en) 1997-05-02 2001-10-09 Dsm N.V. Thermoplastic elastomer composition adapted for adhesion to polar materials
US8044139B2 (en) 2007-12-28 2011-10-25 Cheil Industries Inc. Fiber reinforced nylon composition
CN102634199A (en) * 2012-04-27 2012-08-15 常熟市发东塑业有限公司 Preparation method of modified nylon alloy material
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0506095A1 (en) * 1991-03-29 1992-09-30 ENICHEM S.p.A. Thermoplastic compositions with improved mechanical characteristics
EP0875534A1 (en) * 1997-05-02 1998-11-04 Dsm N.V. Thermoplastic elastomer composition adhesion to polar materials
WO1998050465A1 (en) * 1997-05-02 1998-11-12 Dsm N.V. Thermoplastic elastomer composition adapted for adhesion to polar materials
US6300418B1 (en) 1997-05-02 2001-10-09 Dsm N.V. Thermoplastic elastomer composition adapted for adhesion to polar materials
EP0985709A1 (en) * 1998-09-09 2000-03-15 EMS-Chemie AG Reversible thermotropic composition, its preparation and use
EP1086991A1 (en) * 1999-09-24 2001-03-28 Riken Vinyl Industry Co., Ltd. Thermoplastic elastomeric resin composition and a granule thereof
US9796845B2 (en) 2006-12-18 2017-10-24 Lotte Advanced Materials Co., Ltd. Nylon-based resin composite
US8044139B2 (en) 2007-12-28 2011-10-25 Cheil Industries Inc. Fiber reinforced nylon composition
CN102634199A (en) * 2012-04-27 2012-08-15 常熟市发东塑业有限公司 Preparation method of modified nylon alloy material

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AU4341689A (en) 1990-04-18

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