KR20010075652A - Polycarbonate resin/abs graft copolymer/san blends - Google Patents

Abstract

Thermoplastic resin blends comprising aromatic polycarbonate resins, acrylonitrile-butadiene-styrene graft copolymers and styrene-acrylonitrile copolymers with reduced styrene-acrylonitrile oligomer content improve the balance of flow properties and ductility.

Description

Polycarbonate resin / acrylonitrile-butadiene-styrene graft copolymer / styrene-acrylonitrile blend {POLYCARBONATE RESIN / ABS GRAFT COPOLYMER / SAN BLENDS}

Polycarbonate resins are tough and rigid engineering thermoplastics with good impact strength. However, the flow characteristics of polycarbonate resins sometimes make processing difficult. Attempts have been made in various prior arts to blend polycarbonate resins with other polymer modifiers to increase flow properties while still retaining the toughness and impact resistance of polycarbonate resins. For example, ABS graft copolymers have been blended with polycarbonate resins to yield lower cost blends with improved processing properties while retaining good impact resistance (US Pat. No. 3,130,177 to Grabowski). And Plastics World, November 1977, pp. 5-58). However, various attempts to further improve the flow properties of polycarbonate resin / ABS graft copolymer blends have been found to be brittle or undesirably low heat. It has resulted in a deformation temperature ("HDT"). Thus, it would be highly desirable and useful to prepare polycarbonate resin / ABS graft copolymer blends having good low temperature ductility and high HDT and good flow properties.

Summary of the Invention

In a first aspect, the invention provides a thermoplastic comprising (a) an aromatic polycarbonate resin, (b) an acrylonitrile-butadiene-styrene graft copolymer and (c) a styrene-acrylonitrile copolymer with reduced oligomer content. It relates to a resin composition.

The resin composition of this invention improves the balance of flow characteristics and ductility.

In a second aspect, the invention provides a thermoplastic comprising blending together an aromatic polycarbonate resin, an acrylonitrile-butadiene-styrene graft copolymer and a styrene-acrylonitrile copolymer with reduced styrene-acrylonitrile oligomer content. It relates to a method for producing a resin composition.

The present invention contains thermoplastic resin compositions, more specifically polycarbonate ("PC") resins, acrylonitrile-butadiene-styrene ("ABS") graft copolymers and styrene-acrylonitrile ("SAN") copolymers. It relates to a thermoplastic resin composition.

In a preferred embodiment, the thermoplastic resin composition of the present invention is based on 100 parts by weight of the thermoplastic resin composition 40 to 95 parts by weight of aromatic polycarbonate resin, more preferably 50 to 90 parts by weight, even more preferably 55 to 80 Parts by weight, 3 to 58 parts by weight of the ABS graft copolymer, more preferably 7 to 47 parts by weight, even more preferably 10 to 40 parts by weight and SAN 2 to 57 parts by weight, more preferably 3 to 43 parts by weight. And even more preferably 5 to 35 parts by weight.

Aromatic polycarbonate resin

The aromatic polycarbonate resin component of the composition of the present invention comprises at least one aromatic polycarbonate resin. Aromatic polycarbonate resins suitable for use as the polycarbonate resin component of the thermoplastic resin composition of the present invention are known compounds whose preparation methods and properties are described in the literature (generally US Pat. Nos. 3,169,121, 4,487,896 and 5,411,999). (Each of which is incorporated herein by reference).

In a preferred embodiment, the aromatic polycarbonate resin component of the present invention is the reaction product of a dihydric phenol according to formula (I) and a carbonate precursor containing structural units according to formula (II).

HO-A-OH

Wherein A is a divalent aromatic radical.

The term "bivalent aromatic radical" as used herein refers to a divalent radical containing a single aromatic ring such as, for example, phenylene, such as a divalent radical containing a condensed aromatic ring system such as naphthalene, such as alkylene, Divalent radicals containing two or more aromatic rings joined by non-aromatic bonds such as alkylidene or sulfonyl groups, either of which may be present at one or more positions on the aromatic ring, such as a halo group or (C1-C6) It may be substituted with an alkyl group.

In a preferred embodiment, A is a divalent aromatic radical according to formula III below.

Suitable dihydric phenols include, for example, 2,2, -bis (4-hydroxyphenyl) propane ("bisphenol A"), 2,2, -bis (3,5-dimethyl-4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane, 4,4-bis (4-hydroxyphenyl) heptane, 3,5,3 ', 5'-tetrachloro-4,4'-dihydroxyphenyl) propane, 2, One or more of 6-dihydroxy naphthalene, hydroquinone, 2,4'-dihydroxyphenyl sulfone. In a very preferred embodiment the dihydric phenol is bisphenol A.

The carbonate precursor is one or more of carbonyl halides, carbonate esters or haloformates. Suitable carbonyl halides include, for example, carbonyl bromide and carbonyl chloride. Suitable carbonate esters include, for example, diphenyl carbonate, dichlorophenyl carbonate, dinaphthyl carbonate, phenyl tolyl carbonate and ditolyl carbonate. Suitable haloformates include, for example, bishaloformates of dihydric phenols such as hydroquinone, or glycols such as ethylene glycol and neopentyl glycol. In a very preferred embodiment the carbonate precursor is carbonyl chloride.

Suitable aromatic polycarbonate resins include linear aromatic polycarbonate resins and branched aromatic polycarbonate resins. Suitable linear aromatic polycarbonate resins include, for example, bisphenol A polycarbonate resins. Suitable branched polycarbonates are known and are prepared by reacting a multifunctional aromatic compound with divalent phenols and carbonate precursors to form branched polymers (see generally US Pat. Nos. 3,544,514, 3,635,895 and 4,001,184). Each disclosure of which is incorporated herein by reference). Multifunctional compounds are generally aromatic and contain three or more functional groups, such as carboxyl, carboxylic anhydride, phenol, haloformate or mixtures thereof such as 1,1,1-tri (4-hydroxyphenyl) ethane, 1 , 3,5-trihydroxybenzene, trimellitic anhydride, trimellitic acid, trimellityl trichloride, 4-chloroformyl phthalic anhydride, pyromellitic acid, pyromellitic dianhydride, melitric acid, melic acid anhydride, tri Mesic acid, benzophenonetetracarboxylic acid and benzophenone-tetracarboxylic dianhydride. Preferred polyfunctional aromatic compounds are 1,1,1-tri (4-hydroxyphenyl) ethane, trimellitic anhydride or trimellitic acid, or haloformate derivatives thereof.

In a preferred embodiment, the polycarbonate resin component of the invention is a linear polycarbonate resin derived from bisphenol A and phosgene.

In a preferred embodiment, the weight average molecular weight of the polycarbonate resin is from about 10,000 to about 200,000 g / mol as measured by gel permeation chromatography against a polystyrene standard, and in another preferred embodiment, the weight of the polycarbonate resin The average molecular weight is about 10,000 to about 100,000 g / mol as measured by gel permeation chromatography against polystyrene standards. The resin typically exhibits an intrinsic viscosity of about 0.3 to about 1.5 dl / g in methylene chloride at 25 ° C.

Polycarbonate resins are prepared by known methods such as, for example, interfacial polymerization, transesterification, solution polymerization or melt polymerization.

Copolyester-carbonate resins are also suitable for use as the aromatic polycarbonate resin component of the present invention. Copolyester-carbonate resins suitable for use as aromatic polycarbonate resin components of the thermoplastic resin compositions of the present invention are known compounds whose preparation methods and properties are described in the literature (generally US Pat. Nos. 3,169,121, 4,430,484). And 4,487,896, each disclosure of which is incorporated herein by reference).

Copolyester-carbonate resins contain, in the polymer chain, linear or irregular powders containing repeating carbonate groups, carboxylate groups and aromatic carbocyclic groups, wherein at least a portion of the carbonate groups are directly bonded to the ring carbon atoms of the aromatic carbocyclic groups. Topographic polymers.

In a preferred embodiment, the copolyester-carbonate resin component of the present invention is derived from a carbonate precursor, at least one dihydric phenol and at least one dicarboxylic acid or dicarboxylic acid equivalent. In a preferred embodiment, the dicarboxylic acid is according to formula IV below and the copolyester-carbonate resin comprises a first structural unit according to formula II and a second structural unit according to formula V below.

Wherein A 'is alkylene, alkylidene, cycloaliphatic or aromatic, preferably an unsubstituted phenylene radical or a phenylene radical substituted at one or more positions on the aromatic ring, each of which is independently ( C1-C6) alkyl.

Suitable carbonate precursors and dihydric phenols are those disclosed above.

Suitable dicarboxylic acids include, for example, phthalic acid, isophthalic acid, terephthalic acid, dimethyl terephthalic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimethyl malonic acid, 1 , 12-dodecanoic acid, cis-1,4-cyclohexane dicarboxylic acid, trans-1,4-cyclohexane dicarboxylic acid, 4,4'-bisbenzoic acid and naphthalene-2,6-dicarboxylic acid. Suitable dicarboxylic acid equivalents include, for example, anhydrides, esters or halide derivatives of the dicarboxylic acids disclosed above, such as phthalic anhydride, dimethyl terephthalate and succinyl chloride.

In a preferred embodiment, the dicarboxylic acid is an aromatic dicarboxylic acid, more preferably at least one of terephthalic acid and isophthalic acid.

In a preferred embodiment, the ratio of ester bonds to carbonate bonds present in the copolyester-carbonate resin is 0.25 to 0.9 ester bonds per carbonate bond.

In a preferred embodiment, the copolyester-carbonate copolymer has a weight average molecular weight of about 10,000 to about 200,000 g / mol.

Copolyester-carbonate resins are prepared by known methods such as, for example, interfacial polymerization, transesterification, solution polymerization or melt polymerization.

ABS graft copolymer

The ABS graft copolymer component of the composition of the present invention comprises at least one ABS graft copolymer. ABS graft copolymers suitable for use as the ABS graft copolymer component of the present compositions are well known in the art. ABS graft copolymers are two-phase systems based on styrene-acrylonitrile (SAN) copolymer continuous phases and dispersed elastomer phases, typically based on butadiene rubber. Small amounts of styrene and acrylonitrile are grafted to the rubber particles to commercialize the two phases.

Three main methods that can be used to prepare ABS include emulsion polymerization, bulk polymerization and suspension polymerization or combinations thereof. Emulsification polymerization of ABS is a two-step method comprising polymerizing butadiene to form a rubber latex followed by polymerization by addition of acrylonitrile and styrene, during which the grafted to rubber produces a SAN continuous phase. When prepared in emulsion, the rubber content of the ABS graft can range from about 10 to 90 weight percent, and the SAN is grafted to about 10 to 90 weight percent of the ABS graft composition. The ratio of styrene to acrylonitrile is from 50:50 to 85:15. When prepared in emulsion, the rubber latex has a particle size in the range of about 0.15 to about 0.8 microns, preferably 0.3 microns by weight. The rubber phase in composition may be polybutadiene, styrene-butadiene or butadiene-acrylonitrile copolymer, polyisoprene, EPM (ethylene / propylene rubber), EPDM rubber (diene, nonconjugated diene such as hexadiene- (1,5) or Ethylene / propylene / diene rubbers containing small amounts of norbornadiene), and crosslinked alkylacrylate rubbers based on C1-C8 alkylacrylates, in particular ethylacrylate, butylacrylate and ethylhexylacrylate Can be. About 10 to about 90 weight percent and about 90 to about 10 weight percent of one or more rubber grafted resins may also be used. The latex emulsion is triturated and ABS is recovered at the end of the polymerization. In the bulk process the polymerization is carried out in styrene / acrylonitrile monomers rather than water. Instead of preparing the rubber, the prefabricated rubber is dissolved in the monomer solution. The rubber-monomer solution is then fed to the reactor and the grafting / polymerization is carried out. When prepared via a bulk or bulk-suspension method, the soluble rubber ranges from about 5 to 25 weight percent and the dispersed rubber phase has a diameter in the range from about 0.5 to about 10 microns. Many weight percent depending on the amount of rubber used. There is an advantageous SAN phase of.

Instead of styrene and acrylonitrile used in graft or non-graft resins, alpha-methyl styrene, para-methyl styrene, mono, di or trihalo styrene, alkyl methacrylates, alkyl acrylates, maleic anhydride, methacrylo Monomers such as nitrile, maleimide, N-alkyl maleimide, N-aryl maleimide, or N-aryl maleimide substituted with alkyl or halo may replace or add styrene or acrylonitrile. As with the bulk method, suspension polymerization uses rubber dissolved in the monomer solution, but after the SAN is polymerized with low conversion, the rubber / SAN / monomer mixture is suspended in water to complete the polymerization.

SAN copolymer

The SAN copolymer component of the composition of the present invention comprises at least one SAN copolymer. Conventional SAN copolymers have an oligomer content of about 0.1 to about 10 weight percent, which oligomers may be defined as components of a SAN having a molecular weight of generally about 15,000 g / mol or less. More typically oligomers are defined as having a molecular weight of about 10,000 g / mol or less.

Preferred SAN copolymers have a relative weight average molecular weight, as determined by gel permeation chromatography, against a narrow dispersion polystyrene standard of about 40,000 to about 110,000 g / mol, more preferably 50,000 to about 90,000 g / mol, even more preferred. Preferably from about 60,000 to about 85,000 g / mole. The SAN copolymer typically comprises 10 to 40% by weight of acrylonitrile, preferably 15 to 35% by weight, more preferably 20 to 30% by weight, the balance being styrene.

The inventors have found that by first removing at least a portion of the low molecular weight end of the distribution (ie, at least a portion of the oligomer content) from the polymerized SAN, a lowered notched Izod ductile-brittle transition temperature (which indicates an improvement in ductility) is realized. Found. In addition, removing at least a portion of the low molecular weight ends of the distribution only slightly increases the blend viscosity. Therefore, the viscosity-ductility balance obtained is very excellent. Moreover, by selecting the amount of oligomer to be removed, it is possible to produce a product having a wide range of properties while making the polycarbonate resin / ABS / SAN blend to have an acceptable viscosity. Also removing the low molecular weight end of the distribution increases the Tg (and HDT) of the blend. This increase in Tg (and HDT) is not simply achieved by switching to high molecular weight SANs.

The reduction of the content of low molecular weight materials, ie styrene-acrylonitrile oligomers, in the styrene-acrylonitrile copolymer component of the composition of the present invention can be achieved by any suitable method.

In a preferred embodiment, the oligomer content of the SAN copolymer component of the present invention is reduced by chemical fractionation. Suitable chemical fractionation is well known in the art.

In a preferred chemical fractionation method, the SAN copolymer is dissolved in a SAN copolymer species and a low molecular weight SAN oligomer species soluble in a first solvent such as methyl ethyl ketone, followed by a second solvent such as a high molecular weight SAN copolymer species which is relatively insoluble. Isopropanol or methanol is added to the solution at a slow rate sufficient to prevent precipitation of high molecular weight SAN copolymer species and with mixing. The resulting mixture is then separated into two layers, a layer of a first solvent and a layer of a second solvent, and a second solvent is added to isolate the fractionated high molecular weight SAN copolymer species from the layer of the first solvent.

One preferred method of removing oligomer content is chemical fractionation, but this should not be viewed as limiting the invention. Other methods can also be used to remove the oligomer content, and the present invention includes such methods. In addition, the oligomer content can be removed at any time. That is, the oligomer may be removed from the SAN component before blending with the polycarbonate component or after blending, and combinations may be used to remove the oligomer before and after blending.

Other ingredients

In addition, certain additives such as antistatic agents, fillers, pigments, dyes, antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, flame retardants and other additives commonly used in polycarbonate / ABS / SAN blends may be included in the resin composition of the present invention. Can be.

Suitable antistatic agents that can optionally be incorporated into the resin blends of the present invention include, but are not limited to, reaction products of polystyrene oxide block polymers with epichlorohydrin, polyurethane, polyamides, polyesters or polyetheresteramides. It is not limited to this.

Suitable fillers that may optionally be included in the resin blends of the present invention include, but are not limited to, talc, glass fibers, calcium carbonate, carbon fibers, clays, silica, mica and conductive metals.

Suitable release agents may also be optionally incorporated into the resin blends of the present invention. The product of the invention is combined and mixed with the components of the composition of the invention, for example by melt mixing using a two roll mill, Banbury mixer, or a single screw or twin screw extruder under conditions suitable for the blend formation of the components, and then optionally so formed. The compositions can be prepared, for example, by pelletizing or grinding to form particles.

The blends of the present invention can be molded into useful moldings by various means such as injection molding, extrusion, rotational molding, blow molding and thermoforming to form products such as, for example, housings and home appliances of computers and office machines.

Various examples of the invention are included in the following examples. However, the examples should be regarded as illustrative and should not be construed as limiting the scope of the invention as defined in the appended claims.

In the examples, the following abbreviations are used.

PC-1: linear polycarbonate resin having an absolute weight average molecular weight of about 29,000 g / mol,

PC-2: linear polycarbonate resin having an absolute weight average molecular weight of about 24,000 g / mol,

ABS: acrylonitrile-butadiene-styrene graft copolymer containing about 50% by weight of butadiene and 50% by weight of styrene-acrylonitrile copolymer (75% by weight of styrene and about 25% by weight of acrylonitrile),

SAN-1: a copolymer of 75% by weight of styrene and 25% by weight of acrylonitrile having a relative weight average molecular weight of about 62,600 g / mol,

SAN-2: SAN-1 having an oligomer content of about 3.5 wt% removed by chemical fractionation and a relative weight average molecular weight of about 66,600 g / mol,

SAN-3: SAN-1 having an oligomer content of about 7.0 wt% removed by chemical fractionation and a relative weight average molecular weight of about 71,500 g / mol,

SAN-4: Copolymer of about 75 wt% styrene and 25 wt% acrylonitrile with a relative weight average molecular weight of about 87,600 g / mol.

Example 1-2 and Comparative Examples C1-C2

Blends of Examples 1-2 and Comparative Examples C1-C2 of the present invention were prepared by combining the following components in the relative amounts (represented in parts by weight), respectively, described in Table I. The ingredients listed in Table I were Henschel blended for about 1 minute to produce a blend containing these components, and the blend was then added to the hopper of the extruder. In a typical small laboratory experiment, these blends were mixed at 320 to 400 rpm with a melt temperature of about 550 ° F. using a 6 barrel Welding Engineers 20 mm extruder. The mixed material was injection molded at about 525 ° F. with a 28 ton Angel molding machine. The specimens were 3.2 ± 0.2 mm thick unless otherwise specified. Notched Izod impact was measured according to ASTM test method D256. Notched Izod data was collected at a range of temperatures. Ductile / brittle temperature was measured as the temperature at which the impact energy fell below 8 ft-lb / in.

The viscosity of the sample was measured using a Goettfert Capillary Rheometer. Viscosity was measured at about 550 ° F. at frequencies ranging from about 100 to about 6300 Hz.

The absolute weight average molecular weight of the polycarbonate resin was measured by gel permeation chromatography on an absolute molecular weight polycarbonate standard.

SAN-1 and SAN-4 are the typical classes of SANs. SAN-2 was prepared by taking about 300 g of SAN-1 type SAN, dissolved in about 1.5 liters of methyl ethyl ketone and dropping about 2.1 liters of isopropanol while stirring the solution. The addition of isopropanol was maintained at a rate slow enough to prevent precipitation of the polymer. The mixture was left for about 1 hour. The upper layer was decanted and concentrated to dryness to afford about 10.5 g of residue. The polymer dissolved in the lower layer precipitated when methanol was added to the blender. This precipitate was filtered and dried in vacuo at about 40 ° C. overnight, then at 80 ° C. for several days.

SAN-3 was prepared by taking about 250 g of SAN-1 type SAN, dissolving it in about 1.25 liters of methyl ethyl ketone and dropping about 1.3 liters of isopropanol as in the formation of SAN-2. SAN-2 was prepared using the same method used to prepare SAN-3.

Blend viscosity, notched Izod ductile / brittle transition temperature results, Tg on polycarbonate, and HDT for each composition are listed in Table I below.

C1 C2 One 2 PC-1 36.8 36.8 36.8 36.8 PC-2 27.7 27.7 27.7 27.7 SAN-1 22.0 - - - SAN-2 - - 22.0 - SAN-3 - - - 22.0 SAN-4 - 22.0 - - ABS 13 13 13 13 Antioxidants and Flow Improvers 0.5 0.5 0.5 0.5 characteristic Notched Izod Ductile / Brittle Transition Temperature (° C) -10 -38 -25 -35 Blend Viscosity (measured at Pa-sec, 100s ^-1 ) 209 293.1 226.6 257.9 Tg (℃) on PC 144.46 143.5 149.1 147.9 HDT (℃) 108 * 111 111 * HDT: not measured for C2

Examples 1 and 2 and Comparative Examples C1 and C2 remove at least a portion of the oligomer distribution from the SAN component of the polycarbonate / ABS / SAN blend, thereby maintaining good notched Izod ductile / brittle transition temperature while maintaining a relatively low blend viscosity. It proves possible to obtain.

While the above description includes very specific disclosures, various modifications may be made to those skilled in the art, and all such modifications should be considered to be within the scope of the claims appended hereto.

Claims (18)

A thermoplastic resin composition comprising (a) an aromatic polycarbonate resin, (b) an acrylonitrile-butadiene-styrene graft copolymer and (c) a styrene-acrylonitrile copolymer with reduced oligomer content. The method of claim 1, A thermoplastic resin composition in which the oligomer content of the styrene-acrylonitrile copolymer is reduced by chemical fractionation. The method of claim 1, The thermoplastic resin composition having a styrene-acrylonitrile copolymer having a weight average molecular weight of about 40,000 to about 110,000 g / mol. The method of claim 3, wherein The thermoplastic resin composition wherein the styrene-acrylonitrile copolymer has a weight average molecular weight of about 50,000 to about 90,000 g / mol. The method of claim 4, wherein The thermoplastic resin composition wherein the styrene-acrylonitrile copolymer has a weight average molecular weight of about 60,000 to about 85,000 g / mol. The method of claim 1, A thermoplastic resin composition wherein the weight average molecular weight of the aromatic polycarbonate resin is about 10,000 to about 200,000 g / mol. The method of claim 6, A thermoplastic resin composition wherein the aromatic polycarbonate resin comprises two or more aromatic polycarbonate resins. The method of claim 6, A thermoplastic resin composition wherein the aromatic polycarbonate resin comprises an aromatic polycarbonate resin having a weight average molecular weight of about 29,000 g / mol. The method of claim 6, A thermoplastic resin composition wherein the aromatic polycarbonate resin comprises an aromatic polycarbonate resin having a weight average molecular weight of about 24,000 g / mol. The method of claim 1, A thermoplastic resin composition comprising about 4 to about 59 parts by weight of acrylonitrile-butadiene-styrene copolymer based on 100 parts by weight of the thermoplastic resin composition. The method of claim 1, A thermoplastic resin composition comprising about 5 to about 46 parts by weight of acrylonitrile-styrene copolymer based on 100 parts by weight of the thermoplastic resin composition. The method of claim 11, And wherein the acrylonitrile-styrene copolymer comprises about 10 to about 40 weight percent acrylonitrile and about 60 to about 90 weight percent styrene based on the total weight of the acrylonitrile-styrene copolymer. A method of blending a thermoplastic resin composition comprising blending together an aromatic polycarbonate resin, an acrylonitrile-butadiene-styrene graft copolymer and a styrene-acrylonitrile copolymer having reduced oligomer content. The method of claim 13, Reducing the oligomer content of the styrene-acrylonitrile copolymer by chemical fractionation. The method of claim 13, And wherein the styrene-acrylonitrile copolymer has a weight average molecular weight of about 40,000 to about 110,000 g / mol. The method of claim 13, The styrene-acrylonitrile copolymer has a weight average molecular weight of about 50,000 to about 90,000 g / mol. The method of claim 13, And wherein the weight average molecular weight of the styrene-acrylonitrile copolymer is from about 60,000 to about 85,000 g / mol. An article molded from the thermoplastic resin composition of claim 1.