JPH086022B2 - Thermoplastic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention has a drawdown property and is a thermoplastic resin mainly composed of a polycarbonate resin, a polybutylene terephthalate resin or a mixture thereof suitable for blow molding. It relates to a composition.

<Prior Art> Polycarbonate resins are widely used as engineering plastics because of their excellent mechanical, thermal and electrical properties. In addition, polybutylene terephthalate resin is also widely used as an engineering plastic because it has excellent electrical properties and chemical resistance.

Various molding methods have been adopted for molding polycarbonate resins and polybutylene terephthalate resins,
Since all of these resins have poor drawdown properties, only a small molded product can be obtained by blow molding, and improvement in drawdown properties is desired.

Conventionally, as a method for improving the drawdown property of a polycarbonate resin, Japanese Patent Publication No. 53-28193 proposes a method of copolymerizing a branching agent having three or more phenolic hydroxyl groups. However, since the branched polycarbonate resin thus obtained is difficult to purify, it is liable to contain unreacted substances and by-products, and has a drawback that it may be colored at the time of molding or cause deterioration of physical properties, and if the degree of branching is too high,
It has the drawback of gelling and is difficult to put into practical use.

Further, JP-A 1-268761 proposes a method of blending a polycarbonate resin or a polyester resin with an acrylic polymer having a weight average molecular weight of at least about 500,000 as a melt rheology modifier. Although the drawdown property of the polycarbonate resin is improved to some extent by this method, the size of the blow-molded article has been increasing in recent years, and is not yet sufficient. Further, the drawdown property of the polybutylene terephthalate resin is hardly improved.
Furthermore, when the above acrylic polymer is added to a mixture of a polycarbonate resin and a polybutylene terephthalate resin and melt-extruded, when the molten resin is extruded from the die,
A phenomenon occurs in which the die expands larger than the size of the die, and this phenomenon occurs at the same time as drawdown, so that the wall thickness is likely to change, and it is difficult to obtain a molded product having a uniform wall thickness.

<Object of the Invention> The present invention solves these problems and provides a polycarbonate resin, a polybutylene terephthalate resin, or a mixture thereof, which has excellent drawdown properties and is capable of easily blow molding a large-sized molded article. With the goal.

The present inventor, as a result of earnest studies to achieve the above object, by using a specific carbon black together with a specific high degree of polymerization acrylic copolymer, polycarbonate resin, polybutylene terephthalate resin or a drawdown of a mixture thereof. The inventors have completed the present invention by finding that the properties can be remarkably improved.

<Structure of Invention> The present invention relates to at least one resin selected from a polycarbonate resin and a polybutylene terephthalate resin.
An acrylic copolymer containing (A) at least 30% by weight of alkyl methacrylate and at least 5% by weight of alkyl acrylate in 0 part by weight, wherein 0.1 g of the polymer is dissolved in 1 deciliter of methylene chloride. 25 ℃
Acrylic copolymer 0.1 with a specific viscosity of 0.2 or more
~ 8 parts by weight and (B) specific surface area (by BET low temperature nitrogen adsorption method) of 150
The present invention relates to a thermoplastic resin composition containing 0.5 to 6 parts by weight of carbon black having an m ³ / g or more and an oil absorption of 500 ml / 100 g or more.

The polycarbonate resin used in the present invention has a viscosity average molecular weight of 10,000 to 100,00 derived from a dihydric phenol.
The polycarbonate is 0, preferably 15,000 to 60,000, and is usually produced from a dihydric phenol and a carbonate precursor by a solution method or a melting method.

The dihydric phenol used here is mainly 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A), but part or all of it may be replaced with another dihydric phenol. Other dihydric phenols include, for example, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane,
2,2-bis (4-hydroxy-3-methylphenyl) propane and the like can be mentioned. Examples of the carbonate precursor include carbonyl halide, carbonyl ester, haloformate and the like, and specific examples include phosgene, diphenyl carbonate, dihaloformate of dihydric phenol and the like. Moreover, in the production of the polycarbonate resin, an appropriate molecular weight modifier, catalyst and the like may be used.

The polybutylene terephthalate resin is a polymer obtained by reacting terephthalic acid or its ester-forming derivative with tetramethylene glycol or its ester-forming derivative as a main raw material, and its molecular weight is not particularly limited, but o-chloro Those having an intrinsic viscosity of about 0.8 to 2.0 measured at 25 ° C. using phenols as a solvent are preferably used. In the polybutylene terephthalate, 30 mol% or less of terephthalic acid may be replaced with other dicarboxylic acids, and 30 mol% of tetramethylene glycol may be substituted.
The following may be replaced with other diols. Examples of other dicarboxylic acids include isophthalic acid and naphthalenedicarboxylic acid, and examples of other diols include polymethylene-α, ω-other than tetramethylene glycol.
Examples thereof include diols, neopentyl glycol, diethylene glycol and the like. The molecular weight of the polybutylene terephthalate is not particularly limited, but those having an intrinsic viscosity of about 0.6 to 2.0 measured at 25 ° C. using o-chlorophenols as a solvent are preferably used.

The acrylic copolymer (A) used in the present invention is a random copolymer containing 30% by weight or more of alkyl methacrylate and 5% by weight or more of alkyl acrylate as constituent components, and mainly contains methyl methacrylate. A random copolymer composed of an alkyl methacrylate and an alkyl acrylate mainly containing butyl acrylate is preferable. Further, one or two or more other copolymerizable monomers may be copolymerized within a range satisfying the conditions of 30% by weight or more of alkyl methacrylate and 5% by weight or more of alkyl acrylate. Examples of other copolymerizable monomers include aromatic vinyl, vinyl cyanide, vinyl ester, and the like, and it is also possible to use polyfunctional monomers such as divinylbenzene, diallyl phthalate, and triallyl cyanurate. is there.

The molecular weight of such an acrylic copolymer must be such that the specific viscosity measured at 25 ° C. of a solution of 0.1 g of the copolymer dissolved in 1 deciliter of methylene chloride is 0.2 or more. If the specific viscosity is less than 0.2, the effect of improving the drawdown property is difficult to appear.

The (B) carbon black used in the present invention is a carbon black having a specific surface area (by BET type low temperature nitrogen adsorption method) of 150 m ³ / g or more and an oil absorption of 500 ml / 100 g or more,
Especially with a specific surface area of 500 m ³ / g or more and an oiling amount of 500 ml / 100 g
The above carbon black is preferable. When the specific surface area and oil absorption of the carbon black are outside the above ranges, the effect of improving the drawdown property is hardly seen.

Such carbon blacks are commercially available as conductive carbon blacks, for example, Ketjen Black EC manufactured by Lion Akzo Co., Ltd., Vulcan XC-72 manufactured by Cabot Corporation, Black Pearl 2000, Denka Black Co., Ltd. Denka Black, Degussa. Printex L, L6, etc.
Other examples include carbon black produced as a by-product when a synthetic gas containing hydrogen and carbon monoxide is produced by partially oxidizing a hydrocarbon such as naphtha in the presence of water vapor and oxygen, or a product obtained by oxidizing this.

The ratio of (A) acrylic copolymer and (B) carbon black blended in the polycarbonate resin, polybutylene terephthalate resin or mixture thereof is such that the resin component 10
Component (A) is 0.1 to 8 parts by weight, component (B) is 0.5 to 6 parts by weight, and component (A) is preferably 0.6 to 0 parts by weight.
˜5 parts by weight, and the component (B) is 2 to 4 parts by weight. (A)
When the amount of the component and the component (B) does not reach the above amount, the drawdown property is not sufficiently improved and the improving effect increases as the amount of the component (A) and the component (B) increases. If the component (b) exceeds 8 parts by weight, or if the component (B) exceeds 6 parts by weight, the mechanical properties may deteriorate and the surface of the molded product may become rough.

The mechanical properties, thermal properties, chemical resistance, etc. of the resulting composition depend on the properties of the polycarbonate resin and the polybutylene terephthalate resin, and the mixing ratio of the two can be adjusted according to the required performance.

If necessary, the resin composition of the present invention may be blended with an impact modifier, an inorganic filler, an inorganic fiber and the like. Examples of the inorganic filler include talc, silica, diatomaceous earth, mica, alumina, calcium carbonate, and the like.
Examples of the inorganic fibers include glass fibers and whiskers. Further, other additives within a range not impairing the object of the present invention,
For example, a lubricant, a stabilizer, an antioxidant, an ultraviolet absorber and the like can be used if necessary.

In particular, it is preferable to add an impact modifier. As the impact modifier, for example, an acrylic elastic body,
Examples thereof include a butadiene polymer and a modified polyolefin polymer. Among them, a graft copolymer obtained by polymerizing two or more copolymerizable vinyl monomers in the presence of a diene rubber is preferable. Examples of the diene rubber here include polybutadiene, polyisoprene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer and the like. Examples of vinyl monomers copolymerizable with these rubber components include acrylonitrile,
Vinyl cyanide compounds such as methacrylonitrile and chloroacrylonitrile, styrene, α-methylstyrene,
aromatic vinyl compounds such as p-methylstyrene, amecoxystyrene, halogenated styrene, methyl acrylate,
Examples thereof include lower alkyl esters of acrylic acid such as ethyl acrylate, butyl acrylate and octyl acrylate, and lower alkyl esters of methacrylic acid such as methyl methacrylate, ethyl methacrylate, butyl methacrylate and octyl methacrylate. The content of these impact modifiers is usually 20 parts by weight or less with respect to 100 parts by weight of the polycarbonate resin, the polybutylene terephthalate resin or a mixture thereof.

In order to produce the resin composition of the present invention, any method is adopted, and in general, each component is dry-blended with a tumbler, a blender, a Nauta mixer, etc., and then melt-kneaded and extruded. Examples thereof include a method of kneading with an extruder. In any case, it is sufficient to select a condition and an apparatus in which each component is sufficiently dispersed and mixed. Examples of the kneading device include a Banbury mixer, a kneading roll, an extruder, and a kneader.

<Effects of the Invention> Since the resin composition of the present invention has improved drawdown properties, it is suitable for blow molding and vacuum molding, and other molding methods such as injection molding, extrusion molding and compression molding. Can also be applied to. Further, not only the molding process is easy, but the molded product thus obtained is excellent in mechanical properties, has a high deflection temperature under load, and is an extremely useful composition from an industrial viewpoint.

<Examples> The present invention will be specifically described below with reference to Examples. In addition, the part in an Example means a weight part. Tensile strength, impact strength (with Izod notch, 1/8 ") and load deflection temperature were measured according to ASTM standard. For drawdown test, pellets were dried at 120 ° C for 4 hours, and 30mmφ extruder ( VSK-30) manufactured by Chuo Kikai Seisakusho Co., Ltd., melt-extruded from a nozzle with a diameter of 4 mmφ at an extrusion temperature of 250 ° C and an extrusion speed of 6 kg / hr, cut the thread hanging from the nozzle from time to time, and measured the weight and the minimum diameter of the thread. The drawdown property was evaluated with the weight as the limit value as the limit value, and the drawdown property was better as the obtained limit value was larger. The following were rejected, and the swell ratio, which is important in blow molding, was calculated from the following formula: swell ratio = thread diameter / nozzle diameter.In general, the larger the swell ratio, the better for large blow molding. However, since it occurs at the same time as the drawdown, it causes a significant change in wall thickness when it becomes extremely large, so 1.5 <swell ratio <3.5 was accepted.

Production of acrylic copolymer 300 parts of distilled water in a reaction vessel equipped with a stirrer and a reflux condenser,
1.8 parts of sodium dioctyl sulfosuccinate, 0.24 parts of ammonium persulfate, 102 parts of methyl methacrylate, 18 parts of n-butyl acrylate and 0.06 parts of n-octyl mercaptan were charged, and after heating with an inert gas, the temperature was raised to 58 ° C. By heating and stirring according to a conventional method, an acrylic copolymer having a specific viscosity of 1.68 was obtained. Further, acrylic copolymers (specific viscosity 0.48), (specific viscosity 0.24), (specific viscosity 0.05) having different specific viscosities were obtained in the same manner except that the compounding amounts of -n-butyl acrylate and n-octyl mercaptan were changed. It was

Examples 1 to 12 and Comparative Examples 1 to 12 Polycarbonate resin, polybutylene terephthalate resin, acrylic copolymer, carbon black, and MBS resin as an impact modifier after dry blending with a blender in the blending ratio shown in Table 1. Using a 30 mmφ vent type extruder, the mixture was melt-kneaded at a cylinder temperature of 270 ° C. to form pellets. The pellets thus obtained were subjected to an injection molding machine (J-120SA manufactured by Japan Steel Works, Ltd.) at a cylinder temperature of 260 ° C. or 280.
Physical property test pieces were prepared at 0 ° C., and the tensile strength, impact strength and load deflection temperature were measured, and the results are shown in Table 1. Furthermore, the drawdown property is evaluated using the pellets produced by the above method, the swell ratio is determined by measuring the thread tip diameter,
The respective results are shown in Table 1.

In Table 1, PC: Polycarbonate resin with a viscosity average molecular weight of 25,000 (Panlite L1250 manufactured by Teijin Chemicals Ltd.) PBT: Polybutylene terephthalate resin (TRB-H manufactured by Teijin Chemicals Ltd.) with an intrinsic viscosity of 1.07 MBS: MBS resin ( Kureha Chemical Industry's Paraloid EXL-2
602) Acrylic copolymer: Specific viscosity 1.68 Acrylic copolymer: Specific viscosity 0.48 Acrylic copolymer: Specific viscosity 0.24 Acrylic copolymer: Specific viscosity 0.05 Carbon black A: Specific surface area 970 m ² / g, Oil absorption 930 ml / 100
g (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd.) Carbon black B: Specific surface area 134 m ² / g, oil absorption 100 ml / 100
g (Mitsubishi Chemical Industry Co., Ltd. Mitsubishi carbon black MA-10
0)

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the thread diameter for measuring the drawdown limit value and its weight. Shows the drawdown limit values of Example 2, Example 8, Example 12, and Example 9.

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Claims (1)

[Claims] 1. At least one resin selected from a polycarbonate resin and a polybutylene terephthalate resin.
An acrylic copolymer containing (A) at least 30% by weight of alkyl methacrylate and at least 5% by weight of alkyl acrylate in 0 part by weight, wherein 0.1 g of the polymer is dissolved in 1 deciliter of methylene chloride. 25 ℃
Acrylic copolymer 0.1 with a specific viscosity of 0.2 or more
~ 8 parts by weight and (B) specific surface area (by BET low temperature nitrogen adsorption method) of 150
A thermoplastic resin composition comprising 0.5 to 6 parts by weight of carbon black having m ³ / g or more and an oil absorption of 500 ml / 100 g or more.