JP7254866B2 - Method for producing thermoplastic resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a thermoplastic resin composition, and more particularly, to a method for producing a thermoplastic resin composition having less carbon black aggregates and excellent dispersibility.

Adding carbon black to thermoplastic resins to make products black is a common practice, and is widely used in various parts such as automobiles, electrical and electronic equipment, precision machinery, and office equipment. . In the case of coloring black, resin pellets or powder are blended with carbon black, melted and kneaded by an extruder, extruded into strands, and cut into pellets.

Carbon black is an aggregate of ultra-fine spherical particles obtained by incomplete combustion of various hydrocarbons or compounds containing carbon. Since it is a powdery substance with a well-developed structure bonded to a small bulk density and a large surface area, it is highly cohesive and highly dispersible. Therefore, when carbon black powder is blended into thermoplastic resin as it is, there are problems such as contamination of the working environment, handling problems, generation of carbon black particles due to classification or aggregation, color retention in subsequent lots, color mixing, etc. Therefore, in general, a technique of once producing a masterbatch in which a thermoplastic resin is mixed with carbon black at a high concentration and then adding the obtained masterbatch to the thermoplastic resin is widely adopted.

Various proposals have been made for a resin composition in which carbon black is blended with a thermoplastic resin. In Patent Document 1, a polycarbonate resin and a polyethylene terephthalate resin in which a polymerization catalyst has been deactivated are mixed with a carbon black of 30 to 30%. An invention using a BET specific surface area of 1500 m ² /g and a DBP absorption of 100 to 500 cm ³ /100 g is described. Patent document 2 describes an invention using carbon black having a primary particle size of 70 to 200 nm and a ratio of DBP absorption to primary particle size of 0.5 to 1.5. Further, Patent Document 3 proposes blending carbon black and a dispersing agent in a polyacetal resin, and describes that the average particle size of the carbon black is preferably 5 to 50 nm. However, in the inventions described in these patent documents, since carbon black is directly added to thermoplastic resins and other additives and melt-kneaded with an extruder or the like, the agglomerated foreign matter of carbon black is insufficient. There is

As a method of blending a carbon black masterbatch with a thermoplastic resin, a polystyrene resin or the like, which is well compatible with carbon black, is often used as a masterbatch resin for the carbon black masterbatch (for example, Patent Documents 4 to 5). ). Moreover, Patent Document 6 proposes to convert carbon black having an average primary particle size of 10 to 24 μm into a polycarbonate oligomer (Patent Document 6).

These carbon black masterbatches are produced by kneading with a kneader, a Banbury mixer, an extruder, or the like. Since the particles are taken in without being destroyed, even if such a carbon black masterbatch is used to blend with a thermoplastic resin, the carbon black agglomerated foreign matter will not be eliminated in the end, and as a result, Problems such as poor appearance and reduced strength tend to occur.

JP 2012-77242 A WO2012/131829 JP 2017-14304 A Japanese Patent Application Laid-Open No. 2016-138200 JP 2012-057152 A JP-A-06-345951

As described above, carbon black is highly cohesive and is generally considered to form primary aggregates and secondary aggregates called structures. For this reason, a masterbatch containing a high concentration of carbon black is more difficult to flow than a resin containing this, and problems such as generation of foreign matter and reduction in strength tend to occur.
The present invention has been devised in view of such problems, and provides a method for producing a thermoplastic resin composition that produces less carbon black agglomerated foreign matter, has excellent dispersibility, and does not have problems such as reduced strength of molded products. for the purpose.

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that carbon black forms spherical particles (structures) with different degrees of chain structure, but primary aggregates (aggregates) permanently fused together ) and secondary aggregates (agglomerates) in the dispersion system due to the interaction of Van der Waals forces. It has been found that by improving the properties, a thermoplastic resin composition can be stably produced with less generation of agglomerated foreign matter of carbon black, excellent dispersibility, and free from problems such as reduction in strength of molded articles.
The present invention relates to the following method for producing a thermoplastic resin composition.

[1] A method for producing a thermoplastic resin composition,
50 to 90% by mass of thermoplastic resin (A-1) and 50 to 10% by mass of carbon black (B) pulverized by a jet mill pulverizer are supplied to a twin-screw extruder, melt-kneaded, and passed through a screen mesh. a step of producing a carbon black masterbatch (MB);
The thermoplastic resin (A-2) and the carbon black masterbatch (MB), and at least one of the stabilizer (C) and release agent (D) are supplied to a twin-screw extruder and melt-kneaded to obtain a resin. A method for producing a thermoplastic resin composition, comprising a step of producing a resin composition having a carbon black content of 0.1 to 5% by mass in the composition.
[2] The method for producing a thermoplastic resin composition according to [1] above, wherein the screen mesh has a mesh size of 100 meshes or more.
[3] The above [1], wherein the pulverized carbon black has an average particle size (Dp50) of 0.3 to 5 μm as determined by a laser diffraction scattering method, and the proportion of particle sizes of 10 μm or more is 5% or less, or [2] A method for producing a thermoplastic resin composition.
[4] The thermoplastic resin according to any one of [1] to [3] above, wherein the thermoplastic resin (A-1) is a resin selected from polystyrene resins, polycarbonate resins, polybutylene terephthalate resins and polyacetal resins. A method of making the composition.
[5] The thermoplastic resin composition according to any one of [1] to [4] above, wherein the thermoplastic resin (A-2) is a resin selected from a polycarbonate resin, a polybutylene terephthalate resin and a polyacetal resin. Production method.
[6] The method for producing a thermoplastic resin composition according to any one of [1] to [5] above, wherein the pulverized carbon black (B) is supplied in multiple stages from at least one location of the twin-screw extruder.
[7] The method for producing a thermoplastic resin composition as described in [6] above, wherein a square-flighted screw is used in the carbon black (B) feeding section of the twin-screw extruder.

According to the method for producing a thermoplastic resin composition of the present invention, it is possible to stably produce a thermoplastic resin composition that has excellent dispersibility with less generation of agglomerated foreign substances of carbon black and that does not cause problems such as reduction in strength of molded articles. be able to.

Hereinafter, the present invention will be described in detail by showing embodiments and examples, etc., but the present invention is not limited to the embodiments, examples, etc. shown below, and can be arbitrarily used without departing from the scope of the present invention. can be implemented by changing to

In the method for producing the thermoplastic resin composition of the present invention, 50 to 90% by mass of thermoplastic resin (A-1) and 50 to 10% by mass of carbon black (B) pulverized with a jet mill pulverizer are extruded. A step of supplying to and melt-kneading to pass through a screen mesh to produce a carbon black masterbatch (MB),
The thermoplastic resin (A-2) and the carbon black masterbatch (MB), and at least one of the stabilizer (C) and release agent (D) are supplied to a twin-screw extruder and melt-kneaded to obtain a resin. The method is characterized by including a step of producing a resin composition having a carbon black content of 0.1 to 5 mass % in the composition.

[Carbon black (B)]
In the production method of the present invention, carbon black (B) pulverized by a jet mill pulverizer is used as carbon black. As the raw material carbon black for the carbon black (B), there are no restrictions on its production method, raw material species, and the like, and conventionally known arbitrary ones can be used. Specific examples include oil furnace black, channel black, acetylene black, and ketjen black. Among these, oil furnace black is particularly preferable in terms of colorability and cost.

The average particle size of the raw material carbon black may be appropriately selected and determined.
In addition, the nitrogen adsorption specific surface area of the raw material carbon black is generally preferably less than 1000 m ² /g, and more preferably 50 to 400 m ² /g. The nitrogen adsorption specific surface area (unit: m ² /g) can be measured according to JIS K6217.
Further, the DBP absorption of the raw material carbon black is preferably less than 300 cm ³ /100 g, more preferably 30 to 200 cm ³ /100 g. The DBP absorption (unit: cm ³ /100 g) can be measured according to JIS K6217.

The raw material carbon black used in the present invention can be used alone or in combination of two or more.

In the present invention, the carbon black (B) obtained by pulverizing the raw material carbon black as described above with a jet mill pulverizer is used as the carbon black for producing the carbon black masterbatch. Raw material carbon black consists of permanently fused primary aggregates (aggregates), van der Waals interaction, and secondary aggregates (agglomerates) in a dispersed system. By applying, especially the secondary agglomerates are destroyed and the dispersibility is improved.

A jet mill pulverizer is a device that attaches particles to a high-speed jet stream such as air and atomizes by collision between particles. A type that divides into a pulverization zone and a classification zone to obtain fine powder, Majac Jet Pulverizer manufactured by Majac, Super Jet Mill manufactured by Nissei Engineering, CGS type jet mill manufactured by Nippon Coke, Spiral Jet Mill manufactured by Hosokawa Micron. , SK-Single Track Jet Mill manufactured by Seishin Enterprise Co., Ltd., etc., are used to achieve pulverization by colliding particles accelerated by a jet stream from two or three directions, but the latter jet Mill grinders are preferred, especially those of the single track type.
The conditions for jet mill pulverization vary depending on the pulverizer used, but usually the nozzle pressure is 0.5 to 2.0 MPa, the air volume is 1 to 50 m ³ /min, and the throughput is about 0.5 to 100 kg/hr. is preferably

The carbon black (B) pulverized with a jet mill pulverizer preferably has an average particle size (Dp50) of 0.3 to 5 μm, and the proportion of particles having a particle size of 10 μm or more is 5% or less. is preferred. By having such a particle size and particle size distribution, the dispersibility of carbon black in the finally obtained thermoplastic resin composition is improved, the occurrence of carbon black agglomerated foreign matter is reduced, and the strength of the molded product is reduced. It becomes possible to stably produce a thermoplastic resin composition free from problems such as The average particle size (Dp50) of carbon black (B) is preferably in the range of 0.3-5 μm, more preferably 0.5-1 μm. In addition, the proportion of particles having a diameter of 10 μm or more is preferably 5% or less, more preferably 3% or less. When the average particle size is less than 0.3 μm, secondary aggregation tends to occur after the carbon black is pulverized. Agglomerated foreign matter tends to become large, which is not preferable because it leads to deterioration in performance such as mechanical properties.
The particle size of the pulverized carbon black (B) is a value measured by a laser diffraction scattering method, and the average particle size Dp50 is the particle size at which the cumulative distribution in the laser diffraction scattering method is 50%.

[Production of carbon black masterbatch (MB)]
Carbon black masterbatch (MB) is produced by mixing 50 to 90% by mass of thermoplastic resin (A-1) and 50 to 10% by mass of carbon black (B) pulverized with a jet mill pulverizer into a twin-screw extruder. It is carried out by feeding, melt-kneading, and passing through a screen mesh.

The thermoplastic resin (A-1) is not particularly limited, and includes, for example, polystyrene resin; polycarbonate resin; polyester resin such as polyethylene terephthalate resin and polybutylene terephthalate resin; polyacetal resin; polyphenylene ether resin, modified polyphenylene ether resin, etc. Polyphenylene ether-based resins; thermoplastic resins such as polyamide resins such as polyamide 6, polyamide 66, and polyamide MXD. Among them, polystyrene resin, polycarbonate resin, polybutylene terephthalate resin, and polyacetal resin are preferably used as the thermoplastic resin (A-1). The thermoplastic resin (A-1) is preferably the same type of thermoplastic resin as the thermoplastic resin (A-2) described later, but when the thermoplastic resin (A-2) is a polycarbonate resin, A polystyrene resin is also preferred as the thermoplastic resin (A-1). Further, the thermoplastic resin (A-1) may be blended with two or more thermoplastic resins.

The blending ratio of the thermoplastic resin (A-1) and carbon black (B) when making the carbon black masterbatch (MB) is 50 to 90% by mass of the thermoplastic resin (A-1) and 50 to 90% by mass of the carbon black (B ) is 50 to 10% by mass, while the preferred amount of carbon black (B) is 45 to 10% by mass.

As a melt-kneading method, a twin-screw extruder is used for melt-kneading. As the twin-screw extruder, both a co-rotating type and a counter-rotating type can be used. The melt-kneading temperature is preferably 180 to 350°C, and preferably within the range of the melting point (Tm) of each thermoplastic resin (A-1) ±10°C.

The mixture produced by melt-kneading is passed through a screen mesh preferably provided at the rear end in a twin-screw extruder to obtain a carbon black masterbatch (MB). Agglomerated foreign matter generated in the extruder is captured by a screen mesh, which preferably has a mesh size of 100 mesh or more, more preferably 200 mesh or more, and still more preferably 300 mesh or more.

As a method for producing a carbon black masterbatch (MB), for example, the following aspects are preferred.
The extruder has a first raw material supply port for the thermoplastic resin (A-1) at the most upstream part, and a second raw material supply port for the raw material carbon black (B) downstream thereof. and use a twin-screw extruder configured with either an open vent or a vacuum vent.
The pulverized carbon black (B) is preferably supplied in multiple stages from at least one point of the twin-screw extruder. The thermoplastic resin (A-1) is supplied from the first raw material supply port, and the raw material carbon black is supplied from the second raw material supply port (singular or plural) using a side feeder. It is preferable to provide at least one vent port at the connection portion of the feed port from the side feed and the twin-screw extruder or on the upstream side thereof.
As for the screw arrangement, it is preferable to use square-flighted screws in the carbon black (B) feeding section of the twin-screw extruder. Then, from the first raw material supply unit side, a conveying full flight screw portion, a plasticizing kneading screw portion, and a kneading screw portion are provided, and further, a conveying flight corresponding to the second raw material supply port. It is preferable to have a screw portion and a kneading screw portion for kneading.
After melt-kneading, it is passed through a screen mesh installed at the rear end of the extruder and extruded as a strand from the tip nozzle. The extruded strand is preferably introduced into a water tank adjusted to a temperature range of 30 to 50 ° C. It is then cooled, inserted into a pelletizer and cut to produce carbon masterbatch pellets.

[Production of thermoplastic resin composition]
The production of the thermoplastic resin composition includes the carbon black masterbatch (MB) and the thermoplastic resin (A-2) obtained above, and at least one stabilizer (C) or release agent (D). , supplied to a twin-screw extruder and melt-kneaded to manufacture. The production of the thermoplastic resin composition may be carried out following the production process of the carbon black masterbatch (MB) described above, or the obtained carbon black masterbatch (MB) may be once held or stored and then used. You may

The thermoplastic resin (A-2) is not particularly limited, and examples thereof include polycarbonate resin; polyester resin such as polyethylene terephthalate resin and polybutylene terephthalate resin; polyacetal resin; polyphenylene ether such as polyphenylene ether resin and modified polyphenylene ether resin. system resin; thermoplastic resins such as polyamide resins such as polyamide 6, polyamide 66, and polyamide MXD can be preferably mentioned, and among them, it is more preferable to use polycarbonate resin, polybutylene terephthalate resin, and polyacetal resin.
The thermoplastic resin (A-2) is preferably the same type of thermoplastic resin as the thermoplastic resin (A-1), as described above, but the thermoplastic resin (A-2) is a polycarbonate resin. In this case, it is also preferable that the thermoplastic resin (A-1) is a polystyrene resin. The thermoplastic resin (A-2) used may be used alone or in combination of two or more.

The carbon black masterbatch (MB) is blended so that the content of carbon black in the resulting thermoplastic resin composition is 0.1 to 5% by mass. A preferable content of carbon black in the thermoplastic resin composition is 0.20 to 5% by mass. If the content of carbon black is too high, the appearance of the surface is impaired, which may cause contamination of the mold during molding, which is not preferred. If the content of carbon black is less than 0.1% by mass, the expected functionality may not be sufficiently exhibited.

The stabilizer (C) and/or release agent (D) to be blended in addition to the thermoplastic resin (A-2) and carbon black masterbatch (MB) is not particularly limited, and various phosphorus-based stabilizers, Phenol-based stabilizers, sulfur-based stabilizers, etc., and various release agents can be used.

[Stabilizer (C)]
Phosphorus-based stabilizers include, for example, phosphorus-based compounds. Any known phosphorus compound can be used. Specific examples include phosphorus oxo acids such as phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, and polyphosphoric acid; acid pyrophosphate metal salts such as sodium acid pyrophosphate, potassium acid pyrophosphate, and calcium acid pyrophosphate; phosphoric acid; phosphates of Group 1 or Group 10 metals such as potassium, sodium phosphate, cesium phosphate, zinc phosphate; organic phosphate compounds, organic phosphite compounds, organic phosphonite compounds, and the like.

Among others, triphenylphosphite, tris(monononylphenyl)phosphite, tris(monononyl/dinonylphenyl)phosphite, tris(2,4-di-tert-butylphenyl)phosphite, monooctyldiphenylphosphite, dioctyl monophenylphosphite, monodecyldiphenylphosphite, didecylmonophenylphosphite, tridecylphosphite, trilaurylphosphite, tristearylphosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl) Organic phosphites such as octylphosphite are preferred.

Specific examples of such organic phosphite compounds include, for example, "ADEKA STAB 1178", "ADEKA STAB 2112", and "ADEKA STAB HP-10" manufactured by ADEKA Corporation, "JP-351" manufactured by Johoku Chemical Industry Co., Ltd., " JP-360", "JP-3CP", and "Irgafos 168" manufactured by BASF.

Examples of phenolic stabilizers include hindered phenolic stabilizers. Specific examples include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl ) propionate, thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexane-1,6-diylbis[3-(3,5-di- tert-butyl-4-hydroxyphenylpropionamide), 2,4-dimethyl-6-(1-methylpentadecyl)phenol, diethyl [[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl ]methyl]phosphoate, 3,3′,3″,5,5′,5″-hexa-tert-butyl-a,a′,a″-(mesitylene-2,4,6-triyl)tri -p-cresol, 4,6-bis(octylthiomethyl)-o-cresol, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], hexamethylene Bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3 ,5-triazine-2,4,6(1H,3H,5H)-trione,2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazine- 2-ylamino)phenol, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] and the like.

Among them, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate are preferred. . Specific examples of such phenolic antioxidants include, for example, "Irganox 1010" and "Irganox 1076" manufactured by BASF, "ADEKA STAB AO-50" and "ADEKA STAB AO-60" manufactured by ADEKA. is mentioned. Further, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] is also preferable, and a specific example thereof is "Irganox 245" manufactured by BASF.

Sulfur stabilizers include, for example, dilauryl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearyl -3,3'-thiodipropionate, laurylstearyl-3,3'-thiodipropionate, pentaerythritol tetrakis(3-laurylthiopropionate), bis[2-methyl-4-(3- laurylthiopropionyloxy)-5-tert-butylphenyl]sulfide, octadecyl disulfide, mercaptobenzimidazole, 2-mercapto-6-methylbenzimidazole, 1,1′-thiobis(2-naphthol) and the like.

Among the above, pentaerythritol tetrakis(3-laurylthiopropionate) is preferred. As such a sulfur-based stabilizer, specifically, "Sea Nox 412S" manufactured by Shipro Kasei Co., Ltd. is preferably exemplified.

The amount of the stabilizer (C) to be blended is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.8 part by mass, with respect to a total of 100 parts by mass of the thermoplastic resins (A-1) and (A-2). parts is more preferred, and 0.1 to 0.5 parts by mass is even more preferred.

[Release agent (D)]
Preferred examples of the release agent (D) include aliphatic carboxylic acids, aliphatic carboxylic acid esters, and polyolefin waxes.

Aliphatic carboxylic acids include saturated or unsaturated aliphatic monocarboxylic, dicarboxylic, or tricarboxylic acids. Aliphatic carboxylic acids here also include alicyclic carboxylic acids. Of these, preferred aliphatic carboxylic acids are mono- or dicarboxylic acids having 6 to 36 carbon atoms, and more preferred are saturated aliphatic monocarboxylic acids having 6 to 36 carbon atoms. Specific examples of such aliphatic carboxylic acids include palmitic acid, stearic acid, valeric acid, caproic acid, capric acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, melisic acid, and tetratriacontanoic acid. , montanic acid, glutaric acid, adipic acid, and azelaic acid.

As the aliphatic carboxylic acid component constituting the aliphatic carboxylic acid ester, the same aliphatic carboxylic acid as mentioned above can be used. On the other hand, examples of the alcohol component constituting the aliphatic carboxylic acid ester include saturated or unsaturated monohydric alcohols, saturated or unsaturated polyhydric alcohols, and the like. These alcohols may have substituents such as fluorine atoms and aryl groups. Of these alcohols, monohydric or polyhydric saturated alcohols having 30 or less carbon atoms are preferable, and more preferable are saturated monohydric or polyhydric alcohols having 30 or less carbon atoms. Aliphatic alcohols here also include alicyclic alcohols.

Specific examples of these alcohols include octanol, decanol, dodecanol, stearyl alcohol, behenyl alcohol, ethylene glycol, diethylene glycol, glycerin, pentaerythritol, 2,2-dihydroxyperfluoropropanol, neopentylene glycol, ditrimethylolpropane, and dipentaerythritol. etc. can be mentioned. These aliphatic carboxylic acid esters may contain aliphatic carboxylic acids and/or alcohols as impurities, and may be mixtures of multiple compounds.

Specific examples of aliphatic carboxylic acid esters include beeswax, stearyl stearate, behenyl behenate, octyldodecyl behenate, glycerin monopalmitate, glycerin monostearate, glycerin distearate, glycerin tristearate, pentaerythritol mono Palmitate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate and the like can be mentioned.

Examples of polyolefin waxes include homopolymers and copolymers of olefins. Examples of olefin homopolymers include polyethylene wax, polypropylene wax, partial oxides thereof, and mixtures thereof. Copolymers of olefins include ethylene, propylene, 1-butene, 1-hexene, 1-decene, 2-methylbutene-1, 3-methylbutene-1, 3-methylpentene-1, 4-methylpentene-1 and the like. copolymers such as α-olefins, monomers copolymerizable with these olefins, such as unsaturated carboxylic acids or their acid anhydrides (maleic anhydride, (meth)acrylic acid, etc.), (meth)acrylic acid esters Examples thereof include copolymers with polymerizable monomers such as (alkyl esters of (meth)acrylic acid having 1 to 6 carbon atoms such as methyl (meth)acrylate and ethyl (meth)acrylate). These copolymers also include random copolymers, block copolymers, or graft copolymers. Olefin copolymers are usually copolymers of ethylene and at least one monomer selected from other olefins and polymerizable monomers. Among these polyolefin waxes, polyethylene waxes are most preferred. The polyolefin wax may have a linear or branched structure.

The content of the release agent (D) is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, with respect to the total of 100 parts by mass of the thermoplastic resins (A-1) and (A-2). is more preferred, and 0.1 to 2 parts by mass is even more preferred.

The extruder used for manufacturing the thermoplastic resin composition is a twin-screw extruder. A twin-screw extruder usually has a hopper raw material feed port, a temperature-controlled cylinder, two screws rotatably arranged in the cylinder, and a rotary drive consisting of a motor and a reducer for rotating the two screws. The mechanism consists of a die attached to the tip of the extruder. The screws of the extruder used in the present invention may rotate in the same direction or in opposite directions, but are preferably co-rotating twin screws.

The twin-screw extruder preferably has a L _TL /D _TL (L _TL = extruder screw length, D _TL = extruder screw diameter) of 30-80. If the L _TL /D _TL is less than 30, it will be difficult to obtain the desired screw configuration, and if the L _TL /D _TL exceeds 80, the resin will remain in the resin for a long time, and the decomposition and deterioration of the resin will tend to progress.

The thermoplastic resin composition of the present invention comprises a thermoplastic resin (A-2) and a carbon black masterbatch (MB), a stabilizer (C) and / or a release agent (D), and if necessary other components. , sufficiently dry-blended, fed to the raw material feeder of a twin-screw extruder, and melt-kneaded. The resin temperature during melt-kneading varies depending on the thermoplastic resin (A-2), but is preferably 200 to 350°C.

In the method for producing the thermoplastic resin composition of the present invention, various resin additives other than those mentioned above may be used, if necessary, as long as they do not significantly impair the desired physical properties.
Examples of resin additives include fillers, flame retardants, ultraviolet absorbers, dyes and pigments, antistatic agents, antifogging agents, antiblocking agents, fluidity modifiers, plasticizers, dispersants, and antibacterial agents. . One resin additive may be contained, or two or more resin additives may be contained in any combination and ratio.

The thermoplastic resin composition produced by the method of the present invention has less carbon black agglomerated foreign matter, excellent dispersibility, and does not have problems such as reduced strength of molded articles. It can be widely used as molded products or parts in the housing-related field, the automobile field, and other various fields.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples. However, the present invention should not be construed as being limited to the following examples, and can be arbitrarily modified within the scope of the present invention.

[Production of carbon black masterbatch (MB)]
In the production of the carbon black masterbatch (MB) below, the thermoplastic resins shown in Table 1 below were used as the thermoplastic resin (A-1).

なお、上記したカーボンブラックのＤｐ５０および１０μｍ以上の粒子割合は、セイシン企業社製のレーザー回折・散乱式粒度分布測定器「ＬＭＳ－２０００ｅ」を用いて、カーボンブッラク試料を、０．５％の界面活性剤水溶液で超音波洗浄機で３分間分散させた後に、循環式にて粒度分布測定を行って求めた。 Carbon blacks shown in Table 2 below were used as raw material carbon blacks.

In addition, the above-described carbon black Dp50 and the particle ratio of 10 μm or more are measured using a laser diffraction/scattering particle size distribution analyzer “LMS-2000e” manufactured by Seishin Enterprise Co., Ltd., and the carbon black sample is measured at an interface of 0.5%. After dispersing in the aqueous activator solution with an ultrasonic cleaner for 3 minutes, the particle size distribution was measured using a circulation system.

[Jet mill pulverization of carbon black]
Using a single track jet mill (horizontal jet grinder) “STJ-200” manufactured by Seishin Enterprise Co., Ltd., the carbon blacks CB1, CB2 and CB4 described in Table 2 above are ground under the treatment conditions described in Table 3 below. It was treated and recovered with a bag filter to obtain pulverized carbon black (CB1-M1, CB2-M1, CB2-M2, CB4-M1).

[Production of carbon black masterbatch (MB) (Production Examples 1 to 8)]
As an extruder, C1 (first raw material supply port) at the most upstream part, C5 (second raw material supply port) and C8 (third raw material supply port) downstream thereof have supply ports, and C4 (open vent) , C7 (open vent) and C11 (vacuum vent) with a total of 12 cylinder configuration (referred to as C1 to C12 cylinders from upstream) Toshiba Machine Co., Ltd. intermeshing co-rotating twin screw extruder "TEM37BS" was used.
The thermoplastic resin (A-1) is supplied from the first raw material supply port, and the carbon black is supplied from the second raw material supply port and the third raw material supply port, respectively, with a side feeder (“HSF-37” manufactured by Toshiba Machine Co., Ltd.). supplied by using
The screw arrangement is equipped with a conveying full flight screw section, a plasticizing kneading screw section, and a kneading kneading screw section from the first raw material supply section side, and also corresponds to the second raw material supply port and the third raw material supply port. Then, it has a flight screw section for conveying, a kneading screw section for kneading, and a screw mesh of the mesh shown in Table 4 at the most downstream side.
The thermoplastic resin (A-1) shown in Table 1 and the jet-mill pulverized carbon black or unpulverized carbon black shown in Table 3 were mixed under the raw material composition, supply conditions and extrusion conditions shown in Table 4. It was supplied to the twin-screw extruder from each supply port and extruded as a strand for about 1 hour from 4 nozzle holes (circular (φ4 mm, length 1.5 cm). The extruded strand was heated to a temperature of 30 to 50 ° C. It was cooled by introducing it into a water tank adjusted to the range of , inserted into a pelletizer and cut to produce pellets of carbon black masterbatch (MB-1 to MB-8).

The evaluation method is as follows.
<Extrusion stability>
Extrusion stability when operated for 1 hour under the conditions of Production Examples 1 to 8 The presence or absence of resin vent-up, the presence or absence of extruder tip pressure rise, and strand take-up performance were checked.
<Strand surface appearance>
Visually observe the surface appearance of the resulting strand,
○
△,
It was evaluated as × when the surface had no smoothness, had a rough feeling, and had bumps.
The results are shown in Table 4 below.
In addition, in Table 4, "%" of each supply amount is all "% by mass".

(Examples 1-5 and Comparative Examples 1-4)
As the thermoplastic resin (A-2), stabilizer (C) and release agent (D), those shown in Table 5 below were used.

The carbon black masterbatch (MB-1 to 8) described in Table 4 above, the thermoplastic resin (A-2) described in Table 5 above, the stabilizer (C) and the release agent (D) were added to Table 6 below. After sufficiently dry blending at the compounding ratio described in 1 to 7, an intermeshing co-rotating twin screw extruder "TEM37BS" manufactured by Toshiba Machine Co., Ltd. was set to 250 ° C. (only Example 5 was set to 200 ° C.). , a discharge rate of 50 kg/hr and a screw rotation speed of 400 rpm.
The obtained pellets were dried at 120 ° C. (80 ° C. for Example 5 only) for 6 hours, and using an injection molding machine (“NEX80III” manufactured by Nissei Plastic Industry Co., Ltd.), the cylinder temperature was 250 ° C. (210 ° C. for Example 5 only), Under conditions of a mold temperature of 100° C. (80° C. only in Example 5) and a cycle time of 42 sec, 100 ISO test pieces (thickness: 4 mm) for tensile test evaluation were injection molded.

[Evaluation method]
The evaluation method is as follows.
Tensile test evaluation was carried out using a strograph ("APII" manufactured by Toyo Seiki Co., Ltd.) under the conditions of a tensile speed of 500 mm/min and a distance between chucks of 70 mm.
Furthermore, for the fracture surface of the test piece that was fractured before yielding, using a multi-coater "VES-10" manufactured by Vacuum Device Co., Ltd., after vapor deposition with a C source to a film thickness of 25 nm, SEM observation (Apparatus: "SU8020" manufactured by Hitachi High-Tech, Measurement conditions: 10 kV-250 times to 1000 times) were performed, and the maximum particle diameter (equivalent circle diameter) of carbon black aggregates was measured.
The evaluation results are shown in Tables 6-7 below.

INDUSTRIAL APPLICABILITY The method for producing a thermoplastic resin composition of the present invention has high industrial applicability because it can produce a thermoplastic resin composition having less carbon black aggregates and excellent dispersibility.

Claims (1)

A method for producing a thermoplastic resin composition for parts of electrical equipment or electronic equipment,
50 to 90% by mass of the thermoplastic resin (A-1) and carbon black pulverized with a jet mill pulverizer have an average particle diameter (Dp50) of 0.3 to 5 μm and 10 μm or more as determined by a laser diffraction scattering method. A step of producing a carbon black masterbatch (MB) containing 50 to 10% by mass of carbon black (B) having a certain particle size of 5% or less by melt-kneading with a twin-screw extruder;
A thermoplastic resin (A-2) containing a polybutylene terephthalate resin, the carbon black masterbatch (MB), a stabilizer (C) and a release agent (D) are supplied to a twin-screw extruder and melt-kneaded. including a step of producing a resin composition having a carbon black content of 0.1 to 5% by mass in the resin composition,
The amount of the stabilizer (C) is 0.01 to 1 part by mass and the amount of the release agent (D) is 0.01 to 1 part by mass with respect to a total of 100 parts by mass of the thermoplastic resins (A-1) and (A-2). 01 to 5 parts by mass,
A method for producing a thermoplastic resin composition for parts of electrical or electronic equipment, characterized by: