JP6955070B2 - Manufacturing method of thermoplastic resin composition and manufacturing method of molded product - Google Patents

Description

The present invention relates to a thermoplastic resin composition containing carbon black and a molded product using the same.

With the development of technology, resins have been expanding their application fields more and more in recent years, such as vehicle parts, home appliance parts, and various industrial materials. Secondary processing technology related to resin bonding is also one of the technologies that contributes to its expansion.
Resin joining methods include, for example, mechanical joining with screws and bolts, joining with adhesives such as hot melt, hot plate welding by applying heat typified by hot plate welding, and vibrating the joint. Examples thereof include vibration welding using the frictional heat generated by the above, laser welding by irradiating the joint portion with laser light and utilizing the absorption heat generated at the portion. Recently, hot plate welding, vibration welding, and laser welding have been increasing their usefulness from the viewpoints of reducing the processing process, reducing the weight, and reducing the environmental load.

In hot plate welding, for example, a heated hot plate is pressed against the surface (adhesion site) of each of the two resin members to be joined for several seconds, melted together, and then quickly separated from the hot plate to join the two. .. Hot plate welding is widely used. However, in hot plate welding, when the hot plate is pulled away from the bonding portion of the resin member, a stringing phenomenon may occur in which the molten resin is stretched into a thread shape. When this stringing becomes remarkable, the obtained resin joint has a poor appearance.

In vibration welding, for example, vibration due to pressure and reciprocating motion is applied to the bonding portion of each of the two resin members, and the resin component of the bonding portion is melted by the frictional heat to join the two. Vibration welding is an excellent method that does not require heating the resin members and can join the resin members to each other in an extremely short time. However, in this vibration welding, a thread burr phenomenon may occur in which the molten resin protrudes to the outside of the joint portion in a thread-like manner. When this thread burr becomes remarkable, the obtained resin bonded body has a poor appearance.

In laser welding, two materials, a "transmissive material" that transmits laser light and an "absorbent material" that absorbs laser light, are usually joined. For example, when the absorbent material and the transmissive material are arranged in contact with each other, and the laser beam is irradiated from the transmissive material side to the material contact interface in a non-contact manner, the irradiated laser light is transmitted through the transmissive material as it is. It reaches the surface of the absorbent material and is absorbed. The light energy absorbed on the surface of the absorber is converted into heat and melts the bonding site. Further, the heat of fusion is transferred to the transmission material to melt the bonding portion of the transmission material. After that, the melted adhesive parts of the absorbent material and the transparent material are solidified and welded with cooling. The resin bonded body obtained through such a process is excellent in strength, airtightness, and appearance (no burrs, etc.). Further, laser welding has features such as a good working environment and less damage to the built-in parts when some parts are built in the resin member to be joined. However, in this method, if the laser beam to be irradiated is too strong, the calorific value of the resin increases, which causes poor appearance such as foaming, charring, and discoloration. On the other hand, if the laser beam to be irradiated is too weak, the bonding strength is lowered, and in some cases, problems such as insufficient welding may occur. Therefore, when performing laser welding, it is very important to control the calorific value of the resin within an appropriate range.

By the way, a molded product obtained from a thermoplastic resin is often used in a state of being colored with a pigment (colored molded product). From the viewpoint of product design, the color tone of colored molded products is very important. Color tones are also very important for vehicle parts, but the demand for black color tends to increase year by year because the design is especially popular in the market.
Since carbon black, which is a typical black colorant, has high absorption of laser light, it is efficient in increasing the calorific value and melting the resin.
However, if the amount of carbon black added is too large, the amount of heat generated becomes excessive, and as described above, poor appearance such as foaming, charring, and discoloration is likely to occur during irradiation with laser light. That is, if the amount of carbon black added is increased in order to obtain a deep blackness, the appearance after laser welding is conversely deteriorated. Therefore, it is very difficult to achieve both the color tone (particularly blackness) and the appearance after laser welding.

Patent Document 1 contains a styrene resin and a colorant as a colored styrene resin molded product having excellent laser marking properties and the appearance (surface gloss) of the molded product, and contains a secondary of 0.1 to 10 μm in the molded product. Those in which the number of colorants present in the particles is 100 to 20000 / m ^{2 are disclosed.}
However, in this document, there is no description about achieving both the color tone (particularly blackness) of the molded product and the appearance after laser welding. The colored styrene resin molded body disclosed in Patent Document 1 has technical problems as a laser welding material from the viewpoint of the balance between blackness and absorption of laser light and impact resistance.

Patent Document 2 describes a rubber-reinforced copolymer resin (gel content is 70) in order to improve a defective phenomenon that occurs during vibration welding, hot plate welding, or laser welding when joining a lamp housing to another member. % Or more obtained by polymerizing a vinyl-based monomer containing an aromatic vinyl compound and a vinyl cyanide compound in the presence of a rubbery polymer) or the rubber-reinforced copolymer resin and a vinyl-based monomer. A rubber-reinforced resin composed of a composition with the (co) polymer of No. 1 and a copolymer containing a maleimide-based monomer unit and / or a (co) polymer of α-methylstyrene were combined in a specific ratio. A thermoplastic resin composition for a lamp housing is disclosed.
However, in this document, there is no description about achieving both the color tone (particularly blackness) of the molded product and the appearance after laser welding. The composition disclosed in Patent Document 2 has not sufficiently satisfied the required level for blackness.

Japanese Unexamined Patent Publication No. 2000-309639 Japanese Unexamined Patent Publication No. 2004-182835

An object of the present invention is to provide a thermoplastic resin composition capable of obtaining a molded product having excellent color tone, impact resistance and welded appearance.
Another object of the present invention is to provide a molded product having excellent color tone, impact resistance and welded appearance.

As a result of diligent studies, the present inventors have found that the above problems can be solved by blending carbon black having a specific secondary particle size distribution with a thermoplastic resin composition containing a rubber-containing graft copolymer. The present invention has been reached.
That is, the gist of the present invention is as follows.

[1] Containing a thermoplastic resin (A) and carbon black (B),
The thermoplastic resin (A) contains a graft copolymer (C) in which a vinyl-based polymer is grafted onto a rubber-like polymer.
In the carbon black (B), the volume average particle diameter of the secondary particles is 200 nm or more, and the ratio of the secondary particles having a particle diameter of 800 nm or more to the entire secondary particles is less than 20% by volume.
A thermoplastic resin composition characterized in that the content of the carbon black (B) is 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin (A).
[2] In the volume-based particle size distribution of the carbon black (B), the particle size having a cumulative value of 10% is 10% cumulative particle size (d10), and the particle size having a cumulative value of 50% is 50% cumulative. When the particle size (d50) and the particle size at which the cumulative value is 90% are 90% cumulative particle size (d90), M obtained by the following formula (1) satisfies the following formula (2), [1 ] Thermoplastic resin composition.
M = (d90-d10) / d50 ... (1)
1.5 ≤ M ≤ 2.5 ... (2)
[3] A molded product using the thermoplastic resin composition of the above [1] or [2].

According to the thermoplastic resin composition of the present invention, a molded product having excellent color tone, impact resistance and welded appearance can be obtained.
The molded product of the present invention is excellent in color tone, impact resistance and welded appearance.

Hereinafter, the present invention will be described in detail.
In the following description, the "molded article" is a product obtained by molding the thermoplastic resin composition of the present invention. Further, in the following description, unless otherwise specified, "excellent in color tone" means that the molded product has a deep blackness (darkness). Further, "excellent welded appearance" means that there is no poor appearance in the welded portion after welding the molded product by laser welding, vibration welding or hot plate welding. In the case of laser welding, poor appearance means charring, discoloration, or insufficient welding in the welded part, in the case of vibration welding, it means thread burr in the welded part, and in the case of hot plate welding, the thread in the welded part. Means pulling.

"Thermoplastic resin composition"
The thermoplastic resin composition of the present invention contains a thermoplastic resin (A) and carbon black (B).
The thermoplastic resin composition of the present invention contains, if necessary, other additives in addition to the thermoplastic resin (A) and carbon black (B), as long as the effects of the present invention are not significantly impaired. You may.

<Thermoplastic resin (A)>
The thermoplastic resin (A) contains the graft copolymer (C).
The thermoplastic resin (A) may be composed of only the graft copolymer (C), or may further contain a thermoplastic resin (D) other than the graft copolymer (C). From the viewpoint of the balance between impact resistance and fluidity, the thermoplastic resin (A) preferably contains another thermoplastic resin (D).

The thermoplastic resin (A) is preferably composed of 20 to 100% by mass of the graft copolymer (C) and 0 to 80% by mass of the other thermoplastic resin (D), and the graft copolymer (C). ) Is more preferably composed of 20 to 60% by mass and 40 to 80% by mass of the other thermoplastic resin (D) (however, of the graft copolymer (C) and the other thermoplastic resin (D). The total is 100% by mass.). When the content of the graft copolymer (C) in the thermoplastic resin (A) is at least the lower limit of the above range, the impact resistance and the welded appearance of the molded product are more excellent.

<Graft copolymer (C)>
The graft copolymer (C) is a rubber-like polymer grafted with a vinyl-based polymer.
The rubber-like polymer constituting the graft copolymer (C) is not particularly limited, and is, for example, a butadiene rubber such as polybutadiene, styrene / butadiene copolymer, acrylic acid ester / butadiene copolymer; styrene / isoprene. Conjugate diene rubbers such as copolymers; acrylic rubbers such as butyl polyacrylate; olefin rubbers such as ethylene / propylene copolymers; silicone rubbers such as polyorganosiloxane; and the like. Any one of these can be used alone or in combination of two or more. In addition, these rubber-like polymers can be used from a monomer. The rubber-like polymer may have a composite rubber structure or a core / shell structure.
As the rubber-like polymer constituting the graft copolymer (C), a butadiene rubber, an acrylic rubber, or a composite rubber-like polymer thereof is preferable from the viewpoint of having a good balance between color tone and impact resistance.

The gel content of the rubbery polymer is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, and particularly preferably 70 to 85% by mass. When the gel content of the rubber-like polymer is within the above range, the impact resistance of the molded product obtained from the thermoplastic resin composition is more excellent.

Specifically, the gel content of the rubber-like polymer is measured by the following method.
The weighed rubber-like polymer is dissolved in a suitable solvent at room temperature (23 ° C.) for 20 hours, centrifuged, the supernatant is removed by decantation, and the remaining insoluble matter is dried at 60 ° C. for 24 hours. Then weigh. The ratio (mass%) of the insoluble content to the rubber-like polymer weighed first is determined, and the ratio is defined as the gel content of the rubber-like polymer. As the solvent used for dissolving the rubber-like polymer, for example, toluene or acetone can be used.

The rubbery polymer is typically granular.
The average particle size of the rubber-like polymer is not particularly limited, but is preferably 0.1 to 1 μm, more preferably 0.2 to 0.5 μm. When the average particle size of the rubber-like polymer is not less than the lower limit of the above range, the impact resistance is more excellent, and when it is not more than the upper limit of the above range, the color tone is more excellent.
The average particle size of the rubber-like polymer can be calculated from the obtained particle size distribution by measuring the volume-based particle size distribution using a particle size distribution measuring device.

The vinyl-based polymer constituting the graft copolymer (C) is composed of a structural unit based on the vinyl-based monomer.
The vinyl-based monomer is not particularly limited, but aromatic vinyl compounds, (meth) acrylic acid alkyl esters, vinyl cyanide compounds and the like are preferable. "(Meta) acrylic acid alkyl ester" is a general term for acrylic acid alkyl ester and methacrylic acid alkyl ester. Examples of the aromatic vinyl compound include styrene, α-methylstyrene, p-methylstyrene and the like. Examples of the (meth) acrylic acid alkyl ester include methyl methacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate and the like. Can be mentioned. Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile. These vinyl-based monomers may be used alone or in admixture of two or more.
Among the above, as the vinyl-based monomer, it is preferable to use styrene and acrylonitrile in combination because the impact resistance of the molded product is further improved. That is, the vinyl-based polymer preferably has a structural unit based on styrene and a structural unit based on acrylonitrile.

In the graft copolymer (C), the mass ratio of the rubber-like polymer to the vinyl-based polymer is not particularly limited, but the rubber-like polymer has a mass of 10 to 80 with respect to the total mass of the graft copolymer (C). %, The vinyl-based polymer is preferably 20 to 90% by mass, and the rubber-like polymer is particularly preferably 30 to 70% by mass, and the vinyl-based polymer is particularly preferably 30 to 70% by mass (however, the rubber-like polymer). The total of the polymer and the vinyl-based polymer is 100% by mass.). When the mass ratio of the rubber-like polymer to the vinyl-based polymer is within the above range, the impact resistance of the molded product becomes more excellent.

(Method for Producing Graft Copolymer (C))
The graft copolymer (C) is obtained by grafting a vinyl-based polymer onto a rubber-like polymer.
Examples of the method of grafting the vinyl-based polymer to the rubber-like polymer include a method of polymerizing (graft-polymerizing) the vinyl-based monomer in the presence of the rubber-like polymer. The graft copolymer (C) thus obtained has a form in which the vinyl-based polymer obtained by polymerizing the vinyl-based monomer is grafted onto the rubber-like polymer.
The method for performing graft polymerization is not particularly limited, but emulsion polymerization is preferable because the reaction can be controlled so as to proceed stably. Specifically, a method in which a vinyl-based monomer is collectively charged into an aqueous dispersion of a rubber-like polymer and then polymerized; a part of the vinyl-based monomer is first added to the aqueous dispersion of a rubber-like polymer. A method of charging and dropping the rest into the polymerization system while polymerizing at any time; a method of dropping the entire amount of the vinyl-based monomer onto the aqueous dispersion of the rubber-like polymer and polymerizing at any time can be mentioned. The polymerization of the vinyl-based monomer may be carried out in one stage or may be carried out in two or more stages. When it is divided into two or more stages, it is also possible to change the type and composition ratio of the vinyl-based monomer in each stage.

The mass ratio of the rubber-like polymer to the vinyl-based monomer is not particularly limited, but the rubber-like polymer is 10 to 80% by mass based on the total mass of the rubber-like polymer and the vinyl-based monomer, and the vinyl-based monomer is vinyl-based. The monomer is preferably 20 to 90% by mass, the rubber-like polymer is 30 to 70% by mass, and the vinyl-based monomer is 30 to 70% by mass (however, the rubber-like polymer is particularly preferable. And the total of vinyl-based monomers is 100% by mass.). When graft polymerization is carried out at such a mass ratio, the impact resistance of the molded product becomes more excellent.

Emulsion polymerization is usually carried out using a radical polymerization initiator and an emulsifier. For example, a vinyl-based monomer is added to an aqueous dispersion of a rubber-like polymer, and the vinyl-based monomer is radically polymerized in the presence of a radical polymerization initiator and an emulsifier.
When performing radical polymerization, various known chain transfer agents may be added in order to control the molecular weight and graft ratio of the obtained graft copolymer (C).
The polymerization conditions for radical polymerization are not particularly limited, and examples thereof include polymerization conditions at 50 to 100 ° C. for 1 to 10 hours.

Examples of the radical polymerization initiator include peroxides, azo-based initiators, and redox-based initiators in which an oxidizing agent and a reducing agent are combined. Among these, a redox-based initiator is preferable, and a sulfoxylate-based initiator in which ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, sodium formaldehyde sulfoxylate, and hydroperoxide are combined is particularly preferable.

The emulsifier is not particularly limited, but various carboxylic acids such as sodium sarcosate, potassium fatty acid, sodium fatty acid, dipotassium alkenyl succinate, and soap loginate are excellent in the stability of the latex during radical polymerization and can increase the polymerization rate. Acid salts are preferred. Among these, dipotassium alkenyl succinate is preferable because gas generation can be suppressed when the obtained graft copolymer (C) and the thermoplastic resin composition containing the same are molded at a high temperature.

The graft copolymer (C) obtained by performing graft polymerization as described above is usually in the state of latex.
As a method of recovering the graft copolymer (C) from the latex of the graft copolymer (C), for example, the latex of the graft copolymer (C) is put into hot water in which a coagulant is dissolved. A wet method of coagulating into a slurry; a spray-drying method of semi-directly recovering the graft copolymer (C) by spraying the latex of the graft copolymer (C) in a heated atmosphere can be mentioned.

Examples of the coagulant used in the wet method include inorganic acids such as sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid; and metal salts such as calcium chloride, calcium acetate and aluminum sulfate, which are selected according to the emulsifier used in the polymerization. .. For example, when only a carboxylic acid soap such as a fatty acid soap or a rosin acid soap is used as an emulsifier, one or more of the above-mentioned coagulants can be used. When an emulsifier that exhibits stable emulsifying power even in an acidic region such as sodium alkylbenzene sulfonate is used as the emulsifier, a metal salt is suitable as the coagulant.

When the wet method is used, a slurry-like graft copolymer (C) can be obtained. As a method for obtaining the dried graft copolymer (C) from the slurry-like graft copolymer (C), first, the remaining emulsifier residue is eluted with water and washed, and then the slurry is centrifuged or A method of dehydrating with a press dehydrator or the like and then drying with an air flow dryer or the like; a method of simultaneously performing dehydration and drying with a pressing dehydrator or an extruder can be mentioned. By such a method, a powder or particulate dry graft copolymer (C) is obtained.

The cleaning conditions are not particularly limited, but it is preferable to perform cleaning under conditions in which the amount of emulsifier residue contained in 100% by mass of the dried graft copolymer (C) is in the range of 0.5 to 2% by mass. When the emulsifier residue in the graft copolymer (C) is 0.5% by mass or more, the fluidity of the obtained graft copolymer (C) and the thermoplastic resin composition containing the same tends to be further improved. .. On the other hand, when the emulsifier residue in the graft copolymer (C) is 2% by mass or less, gas generation when the thermoplastic resin composition is molded at a high temperature can be suppressed.
It is also possible to directly send the graft copolymer (C) discharged from the extrusion dehydrator or extruder to the extruder or molding machine that manufactures the resin composition to obtain a molded product.

<Other thermoplastic resin (D)>
The other thermoplastic resin (D) is not particularly limited, but for example, an acrylonitrile-styrene copolymer (AS resin), an acrylonitrile-α-methylstyrene copolymer (αSAN resin), and a styrene-maleic anhydride copolymer. , Acrylonitrile-styrene-N-substituted maleimide ternary copolymer, styrene-maleic anhydride-N-substituted maleimide ternary copolymer, acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-styrene-alkyl ( Meta) acrylate copolymer (ASA resin), acrylonitrile-ethylene-propylene-diene-styrene copolymer (AES resin), polymethyl methacrylate, polycarbonate resin, polybutylene terephthalate (PBT resin), polyethylene terephthalate (PET resin) , Polypolymers such as polyvinyl chloride, polyethylene and polypropylene, styrene-based elastomers such as styrene-butadiene-styrene (SBS), styrene-butadiene (SBR), hydrogenated SBS, styrene-isoprene-styrene (SIS), and various olefins. Elastomer, various polyester-based elastomers, polystyrene, methyl methacrylate-styrene copolymer (MS resin), acrylonitrile-styrene-methyl methacrylate copolymer, polyacetal resin, modified polyphenylene ether (modified PPE resin), ethylene-vinyl acetate Examples thereof include polymers, polyphenylene sulfide (PPS resin), polyether sulfone (PES resin), polyether ether ketone (PEEK resin), polyarylate, liquid crystal polyester resin, polyamide resin (for example, nylon) and the like. These other thermoplastic resins (D) may be used alone or in combination of two or more.

<Carbon black (B)>
Examples of the carbon black (B) include channel black, furnace black, lamp black, thermal black, Ketjen black, naphthalene black and the like. Any one of these can be used alone or in combination of two or more.

The carbon black (B) may have a particle surface that has been secondarily treated.
Examples of the secondary treatment include addition of surface functional groups by oxidation treatment, graphitization by crystal structure by heat treatment in an inert atmosphere, and pirate activity treatment with steam or carbon dioxide gas. Examples of the oxidation treatment include treatment with ozone, nitric acid, nitrite, sodium hypochlorite, and hydrogen peroxide. Acidic functional groups such as carboxyl groups and phenolic hydroxyl groups are generated on the surface of carbon black by the oxidation treatment, and the wettability and dispersibility of the surface of carbon black are improved.

Carbon black (B) usually exists as secondary particles in the form of aggregated spherical primary particles.
In carbon black (B), the volume average particle diameter of the secondary particles is 200 nm or more, and the ratio of the secondary particles having a particle diameter of 800 nm or more to the entire secondary particles is less than 20% by volume. If the volume average particle size of the secondary particles is less than 200 nm, or if the proportion of secondary particles having a particle size of 800 nm or more is 20% by volume or more, the color tone and laser weldability may be insufficient.
The upper limit of the volume average particle diameter of the secondary particles of carbon black (B) is not particularly limited as long as the proportion of secondary particles having a particle diameter of 800 nm or more is less than 20% by volume, but is typically 600 nm or less.
The lower limit of the proportion of secondary particles having a particle size of 800 nm or more is not particularly limited, and may be 0% by mass.
The volume average particle size is measured by a dynamic light scattering method. For example, carbon black (B) is dispersed in a dispersion medium (N-methylpyrrolidone), the volume-based particle size distribution is measured using nanotrack, and the volume average particle size is calculated from the obtained particle size distribution. ..

Carbon black (B) has a 10% cumulative particle size (d10) and a 50% cumulative value of 50% in the volume-based particle size distribution of secondary particles. When the cumulative particle size (d50) and the particle size at which the cumulative value is 90% are 90% cumulative particle size (d90), M obtained by the following formula (1) satisfies the following formula (2). It is preferable to have.
M = (d90-d10) / d50 ... (1)
1.5 ≤ M ≤ 2.5 ... (2)
When M is more than 1.5, the color tone and laser weldability tend to be better. When M is less than 2.5, the color tone tends to be better.
It is more preferable that M satisfies 1.5 ≦ M ≦ 2.0.
The particle size distribution is measured by a dynamic light scattering method. For example, carbon black (B) is dispersed in a dispersion medium (N-methylpyrrolidone), and the particle size distribution is measured using nanotrack.

The content of carbon black (B) in the thermoplastic resin composition is 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin (A), and is 0.3 to 2.0 parts by mass. Is preferable, and 0.5 to 1.0 parts by mass is more preferable.
When the content of carbon black (B) is at least the above lower limit value, the color tone of the molded product obtained from the thermoplastic resin composition is excellent. In addition, sufficient bonding strength can be obtained by laser welding.
When the content of carbon black (B) is not more than the above upper limit value, charring and discoloration are less likely to occur during laser welding, and the welded appearance is excellent. Further, the appearance of welding tends to be excellent even in vibration welding and hot plate welding.

<Other additives>
Other additives include, for example, various stabilizers such as antioxidants and light stabilizers, lubricants, plasticizers, mold release agents, dyes, pigments, antistatic agents, flame retardants, inorganic fillers, metal powders and the like. Can be mentioned.
The content of the other additives is appropriately set according to the type of the additive and is not particularly limited, but is preferably 10 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin (A), and is preferably 0 parts by mass. It may be.

<Manufacturing method of thermoplastic resin composition>
In the thermoplastic resin composition of the present invention, for example, the thermoplastic resin (A), the carbon black (B), and other additives, if necessary, are mixed and dispersed by a V-type blender, a Henschel mixer, or the like. The mixture thus obtained is produced by melt-kneading using a melt-kneader such as a screw extruder, a Banbury mixer, a pressure kneader, or a mixing roll. If necessary, the melt-kneaded product may be pelletized using a pelletizer or the like.

<Effect>
The thermoplastic resin composition of the present invention described above contains the thermoplastic resin (A) and carbon black (B), and the thermoplastic resin (A) contains the graft copolymer (C). However, the volume average particle size of the secondary particles of carbon black (B) is 200 nm or more, and the ratio of the secondary particles having a particle size of 800 nm or more to the entire secondary particles is less than 20% by volume. Since the content is 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin (A), when it is made into a molded product, it has sufficient impact resistance as a resin member and excellent color tone (particularly). Blackness) is expressed. Further, this molded product can be welded by laser welding, vibration welding or hot plate welding, and the welded portion has an excellent appearance and can exhibit sufficient bonding strength.

"Molding"
The molded product of the present invention uses the thermoplastic resin composition of the present invention.
The molded article of the present invention can be produced by molding the thermoplastic resin composition of the present invention.
As a molding method, a known molding method can be used, and examples thereof include an injection molding method, a press molding method, an extrusion molding method, a vacuum forming method, and a blow molding method.

The molded product of the present invention can be welded by laser welding, vibration welding, hot plate welding, or the like. For example, a resin bonded body can be obtained by welding the molded products of the present invention to each other, or the molded product of the present invention and another resin molded product by laser welding, vibration welding, or hot plate welding. Such a resin bonded body is excellent in the appearance of the welded portion and the bonding strength.

Examples of applications of the molded product of the present invention and a resin joint using the same include vehicle parts such as lamps, interiors, and exteriors, OA equipment, home appliances, medical appliances, and various industrial materials. , Vehicle lighting fixtures are suitable.

Specific examples will be shown below. However, the present invention is not limited to the following examples. In addition, "%" and "part" in the following examples are based on mass unless otherwise specified.
Various measurement and evaluation methods in the following examples and comparative examples are as follows.

<Evaluation of impact resistance>
A test piece (molded product) was prepared from a pellet-shaped thermoplastic resin composition by an injection molding machine (manufactured by Toshiba Machine Co., Ltd., "IS55FP-1.5A") in accordance with ISO 3167. The Charpy impact strength of this test piece was measured in a notched, 23 ° C. atmosphere in accordance with ISO 179-1: 2000.

<Evaluation of laser welding appearance>
From the pelletized thermoplastic resin composition produced in each example, a 4 ounce injection molding machine (manufactured by Japan Steel Works, Ltd.) was used, the cylinder set temperature was 260 ° C, the mold temperature was 60 ° C, and the injection rate was 20 g / sec. Under the conditions of (1), a plate-shaped test piece (molded product) having a length of 100 mm, a width of 100 mm, and a thickness of 2 mm was prepared, and this was used as an absorbent material.
A transparent material was prepared in the same procedure as the absorbent material, except that the resin used was changed from the pellet-shaped thermoplastic resin composition produced in each example to the pellet-shaped acrylic resin.
Laser light with the conditions of output: 3W, focal diameter: 2mm, scanning speed: 20mm / sec, welding length: 30mm, using the "laser welding machine NOVOLAS-C type" manufactured by Leister, by superimposing the absorbent material and the transmitting material. Was irradiated from the transmission material side and welded to the absorbent material to obtain a bonded body. Then, the appearance of welding on the joint surface of the joined body was visually observed and evaluated according to the following criteria.
◯: There is no foaming.
Δ: There is some foaming.
X: There is foaming or charring on the whole.

<Evaluation of vibration welding appearance>
From the pellet-shaped thermoplastic resin composition produced in each example, a flat plate molded product (traploid, width 70 mm, short side 110 mm, long side 160 mm) having a thickness of 2 mm was obtained by injection molding.
The obtained flat plate molded product and the evaluation lens were vibrated and welded to obtain a bonded body. As an evaluation lens, polymethylmethacrylate (PMMA) resin (Acrypet VH4 manufactured by Mitsubishi Rayon Co., Ltd.) is injection-molded to a 3 mm ribbed sheet (trapezoidal, width 70 mm, short side 110 mm, long side 160 mm, rib: high. The one formed into a diameter of 10 mm, a short side of 100 mm, and a long side of 150 mm) was used. Vibration welding was performed using BRANSON VIBRATION WELDER 2407 manufactured by Emerson Japan, Ltd. under the conditions of an amplitude of 1 mm, a pressure of 0.3 MPa, and a subduction amount of 1.5 mm.
The number of thread burrs generated by melting and joining during vibration welding was visually observed and evaluated according to the following criteria.
◯: 0 or more and less than 15.
Δ: 15 or more and less than 20.
X: 20 or more.

<Evaluation of hot plate welding appearance>
From the pellet-shaped thermoplastic resin composition produced in each example, a test sheet (25 mm × 100 mm × 3 mm) was obtained by injection molding.
The obtained test sheet was brought into contact with a hot plate heated to 220 ° C. for 12 seconds and then pulled apart horizontally, and the number of threads of 5 mm or more at that time was visually observed and evaluated according to the following criteria.
◯: 0 or more and less than 5.
Δ: 5 or more and less than 15.
X: 15 or more.

<Evaluation of color tone>
The color tone (L *) was measured with a colorimeter using the same test piece used to evaluate the appearance of laser welding. The smaller the value of L *, the deeper (darker) the blackness of the molded product.

<Measurement of volume average particle size and particle size distribution of secondary particles of carbon black (B)>
Volume-based particle size distribution was measured by dynamic light scattering using Nanotrac UPA-EX150 manufactured by Nikkiso Co., Ltd. as a 0.04% dispersion in which carbon black (B) was dispersed in N-methylpyrrolidone, and the volume average was measured. The particle size was determined.
Further, in the volume-based particle size distribution, the particle size at which the cumulative value is 10% is 10% cumulative particle size (d10), and the particle size at 50% is 50% cumulative particle size (d50), 90%. The particle size was determined as 90% cumulative particle size (d90), and the value of M was calculated from the above formula (1).

<Measurement of volume average particle size of polymer in latex>
The volume average particle size was determined by a dynamic light scattering method using a Nanotrac UPA-EX150 manufactured by Nikkiso Co., Ltd.

<Measurement of gel content of rubber-like polymer>
The weighed rubber-like polymer is dissolved in toluene at room temperature (23 ° C.) for 20 hours, centrifuged, the supernatant is removed by decantation, and the remaining insoluble matter is dried at 60 ° C. for 24 hours. Weighed. The ratio (%) of the insoluble content to the rubber-like polymer weighed first was determined, and the ratio was taken as the gel content of the rubber-like polymer.

"Manufacture of acid group-containing copolymer latex"
<Production Example 1: Production of acid group-containing copolymer latex (K)>
200 parts of ion-exchanged water, 2 parts of potassium oleate, 4 parts of sodium dioctyl sulfosuccinate, 0.003 ferrous sulfate heptahydrate in a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer. Parts, 0.009 part of ethylenediaminetetraacetic acid disodium salt and 0.3 part of sodium formaldehyde sulfoxylate were charged under a nitrogen stream, and the temperature was raised to 60 ° C. From the time when the temperature reached 60 ° C., a mixture consisting of 85 parts of n-butyl acrylate, 15 parts of methacrylic acid and 0.5 part of cumene hydroperoxide was continuously added dropwise over 120 minutes. After completion of the dropping, aging was carried out for another 2 hours at 60 ° C., and the solid content was 33%, the polymerization conversion rate was 96%, and the volume average particle size of the acid group-containing copolymer was 120 nm. A copolymer latex (K) was obtained.

"Graft copolymer (C)"
<Production Example 2: Production of Graft Copolymer (C-1)>
In a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer, 150 parts of ion-exchanged water and polybutadiene latex (volume average particle diameter 0.2 μm, gel content 84%) are placed in a solid content equivalent of 50. , 1 part of disproportionated potassium rosinate, 0.03 part of potassium hydroxide, and after heating to 60 ° C, 0.007 part of ferrous sulfate heptahydrate, 0.1 part of sodium pyrophosphate, 0 crystalline glucose . 3 parts were added. Next, a mixed solution consisting of 15 parts of acrylonitrile, 35 parts of styrene, 0.4 parts of cumene hydroperoxide, and 0.5 parts of t-dodecyl mercaptan was added dropwise over 120 minutes for polymerization. After completion of the dropping, the temperature of 70 ° C. was maintained for 60 minutes, 0.05 part of cumene hydroperoxide was added, the temperature of 70 ° C. was maintained for 30 minutes, and then the mixture was cooled to add acrylonitrile and styrene to polybutadiene. Was graft-polymerized to obtain a latex of a polybutadiene-based graft copolymer (C-1).
Next, an antioxidant was added to the latex, 150 parts of a 1% aqueous sulfuric acid solution was heated to 60 ° C., and 100 parts of the latex of the graft copolymer (C-1) was gradually added dropwise into the latex to solidify. Then, the precipitate was separated, dehydrated, washed, and then dried to obtain a graft copolymer (C-1).

<Production Example 3: Production of Graft Copolymer (C-2)>
In a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer, 2.0 parts of polybutadiene latex (volume average particle size 200 nm) in terms of solid content and 0.8 parts of dipotassium alkenyl succinate were added. , 190 parts of ion-exchanged water was charged and mixed. Then, a mixture consisting of 48.0 parts of n-butyl acrylate, 0.6 parts of allyl methacrylate, 0.1 part of 1,3-butylene glycol dimethacrylate, and 0.1 part of t-butyl hydroperoxide was added. Nitrogen was replaced in the atmosphere by passing a nitrogen stream through this reactor, and the internal temperature was raised to 60 ° C. When the internal temperature reaches 60 ° C, from 0.000075 parts of ferrous sulfate heptahydrate, 0.00023 parts of ethylenediaminetetraacetic acid disodium salt, 0.2 parts of sodium formaldehyde sulfoxylate, and 10 parts of ion-exchanged water. An aqueous solution was added to initiate radical polymerization. After the polymerization heat generation was confirmed, the jacket temperature was set to 75 ° C., the polymerization was continued until the polymerization heat generation was not confirmed, and this state was maintained for another 1 hour to obtain a composite rubber in which polybutadiene and polybutyl acrylate rubber were compounded. (Radical polymerization step). The volume average particle size of the obtained composite rubber was 280 nm.
After the liquid temperature inside the reactor was lowered to 70 ° C., 0.60 part of a 5% aqueous sodium pyrophosphate solution was added as a solid content. After controlling the internal temperature at 70 ° C., 0.60 part of acid group-containing copolymer latex (K) was added as a solid content, and the mixture was stirred for 30 minutes and enlarged to obtain a latex of a composite rubber-like polymer (latex of a composite rubber-like polymer). Enlargement process). The volume-equal particle size of the composite rubber-like polymer in the obtained latex was 300 nm, and the gel content was 83%.

To the latex of this composite rubber-like polymer, an aqueous solution consisting of 0.001 part of ferrous sulfate heptahydrate, 0.003 part of ethylenediamine tetraacetate disodium salt, 0.3 part of longalit, and 10 parts of ion-exchanged water was added. .. Next, a mixed solution consisting of 10 parts of acrylonitrile, 30 parts of styrene, and 0.18 parts of t-butyl hydroperoxide was added dropwise over 80 minutes for polymerization. After completion of the dropping, the temperature was maintained at 75 ° C. for 30 minutes, and then a mixture consisting of 2.5 parts of acrylonitrile, 7.5 parts of styrene, 0.05 parts of t-butyl hydroperoxide, and 0.02 parts of n-octyl mercaptan. Was added dropwise over 20 minutes to polymerize. After completion of the dropping, the state of the temperature of 75 ° C. was maintained for 30 minutes, 0.05 part of cumenehydroperoxide was added, the state of the temperature of 75 ° C. was further maintained for 30 minutes, and then the mixture was cooled to form a composite rubber-like polymer. , A latex of a butadiene / acrylic composite rubber-based graft copolymer (C-2) obtained by graft-polymerizing acrylonitrile and styrene was obtained.
Next, 150 parts of a 1% calcium acetate aqueous solution was heated to 60 ° C., and 100 parts of the latex of the graft copolymer (C-1) was gradually added dropwise into the mixture to coagulate. Then, the precipitate was separated, dehydrated, washed, and then dried to obtain a graft copolymer (C-2).

<Production Example 4: Production of Graft Copolymer (C-3)>
190 parts of ion-exchanged water, 0.6 parts of dipotassium alkenyl succinate, 50 parts of n-butyl acrylate, 0.6 parts of allyl methacrylate in a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer. , A mixture consisting of 0.1 parts of t-butyl hydroperoxide was added. The atmosphere was replaced with nitrogen by passing a nitrogen stream through this reactor, and the internal temperature was raised to 55 ° C. When the internal temperature reaches 55 ° C, from 0.0001 parts of ferrous sulfate heptahydrate, 0.0003 parts of ethylenediaminetetraacetic acid disodium salt, 0.2 parts of sodium formaldehyde sulfoxylate, and 10 parts of ion-exchanged water. An aqueous solution was added to initiate radical polymerization. After the heat generation of polymerization was confirmed, the jacket temperature was set to 75 ° C., and the polymerization was continued until the heat generation of polymerization was no longer confirmed, and this state was maintained for another 1 hour. The volume average particle size of the obtained rubber-like polymer was 100 nm.
After the liquid temperature inside the reactor was lowered to 70 ° C., 0.6 part of a 5% aqueous sodium pyrophosphate solution was added as a solid content. After controlling the internal temperature at 70 ° C., 1.2 parts of the acid group-containing copolymer latex (K) was added as a solid content, and the mixture was stirred for 30 minutes and enlarged to obtain a latex of a rubber-like polymer. The obtained latex-like rubber-like polymer had a volume average particle size of 290 nm and a gel content of 85%.

The obtained rubbery polymer latex was added to 0.001 part of ferrous sulfate heptahydrate, 0.003 part of ethylenediamine tetraacetate disodium salt, 0.3 part of sodium formaldehyde sulfoxylate, and 10 parts of ion-exchanged water. An aqueous solution was added. Next, a mixed solution consisting of 15 parts of acrylonitrile, 35 parts of styrene, and 0.225 parts of t-butyl hydroperoxide was added dropwise over 100 minutes for polymerization. After completion of the dropping, the temperature of 80 ° C. was maintained for 30 minutes, 0.05 part of cumene hydroperoxide was added, the temperature of 75 ° C. was further maintained for 30 minutes, and then the mixture was cooled to obtain a graft copolymer (C). -3) Latex was obtained.
Next, 100 parts of a 1.5% sulfuric acid aqueous solution was heated to 80 ° C., and 100 parts of the latex of the graft copolymer (C-3) was gradually added dropwise into the heat to solidify. Then, the precipitate was separated, dehydrated, washed, and then dried to obtain a graft copolymer (C-3).

"Other thermoplastic resin (D)"
<Manufacturing Example 5: Production of Another Thermoplastic Resin (D-1)>
27 parts of acrylonitrile and 73 parts of styrene were polymerized by a known suspension polymerization to obtain an acrylonitrile-styrene copolymer having a reduced viscosity of 0.61 dl / g measured at 25 ° C. from an N, N-dimethylformamide solution. This was used as another thermoplastic resin (D-1).

<Manufacturing Example 6: Production of Another Thermoplastic Resin (D-2)>
Acrylonitrile-styrene having a reduced viscosity of 0.65 dl / g measured at 25 ° C. from an N, N-dimethylformamide solution obtained by polymerizing 19 parts of acrylonitrile, 53 parts of styrene and 28 parts of N-phenylmaleimide by a known continuous solution polymerization. A −N—phenylmaleimide ternary copolymer was obtained. This was used as another thermoplastic resin (D-2).

"Carbon black (B)"
(B-1) "RB-92995S" manufactured by Koshiya Kasei Kogyo Co., Ltd.
(B-2) "ABF-TT2351-G" manufactured by Regino Color Industry Co., Ltd.
(B-3) "DBSP-3387HC" manufactured by Maeda Kasei Co., Ltd.
(B-4) "FW285" manufactured by Orion Engineered Carbons Co., Ltd.
(B-5) "BP2000" manufactured by Cabot Japan Co., Ltd.
(B-6) "# 44" manufactured by Mitsubishi Chemical Corporation.

"Examples 1 to 8, Comparative Examples 1 to 5"
The types and amounts of graft copolymers (C), other thermoplastics (D) and carbon black (B) shown in Tables 1 to 3, 1 part of ethylene bisstearylamide, and silicone oil SH200 (Toray Dow Corning). 0.2 parts of ADEKA STAB AO-60 (manufactured by ADEKA Corporation) and 0.4 parts of ADEKA STAB LA-57 (manufactured by ADEKA Corporation) were mixed using a Henschel mixer. The obtained mixture is melt-kneaded at 250 ° C. using a screw extruder (manufactured by Japan Steel Works, Ltd., TEX-30α twin-screw extruder), and then pelletized with a pelletizer to form pellets of thermoplastic. A resin composition was obtained.
The obtained thermoplastic resin composition was evaluated for impact resistance, laser welding appearance, vibration welding appearance, hot plate welding appearance and color tone by the above procedure. These results are shown in Tables 1-3.
Tables 1 to 3 show the characteristics of the secondary particles of carbon black (B) used in each example (volume average particle size, ratio of secondary particles having a particle size of 800 nm or more, and the value of M obtained from the particle size distribution). It is also written in.

As shown in Tables 1 to 3, from the thermoplastic resin compositions obtained in each example, molded products having excellent impact resistance, laser welding appearance, vibration welding appearance, hot plate welding appearance and color tone can be obtained. rice field.
On the other hand, in the case of each comparative example, the result was inferior to any one or more of the impact resistance of the molded product, the laser welding appearance, the vibration welding appearance, the hot plate welding appearance and the color tone.
Specifically, in the case of Comparative Example 1, the ratio of the secondary particles having a particle diameter of 800 nm or more to the entire secondary particles of carbon black (B) was 20% or more, so that the laser welding appearance was inferior.
In the case of Comparative Example 2, since the volume average particle diameter of the secondary particles of carbon black (B) was less than 200 nm, the appearance of laser welding was inferior.
In the case of Comparative Example 3, since the content of carbon black (B) was small, the laser welded appearance and color tone were inferior.
In the case of Comparative Example 4, since the content of carbon black (B) was large, the impact resistance and the laser welded appearance were inferior.
In the case of Comparative Example 5, since the graft copolymer (C) was not contained, the impact resistance, the laser welding appearance, the vibration welding appearance and the hot plate welding appearance were inferior.

According to the present invention, a thermoplastic resin composition capable of obtaining a molded product having excellent color tone and appearance after welding by laser welding, vibration welding or hot plate welding and having sufficient impact resistance as a resin member. Can be provided. In particular, the balance between the color tone of the molded product and the appearance after laser welding is at a very high level that cannot be obtained with the conventionally known thermoplastic resin compositions, and vehicle parts such as lighting fixtures, interiors, and exteriors, and OA equipment. The utility value as a home appliance part, medical equipment, and various industrial materials is extremely high.

Claims (9)

A method for producing a thermoplastic resin composition, in which a thermoplastic resin (A) and carbon black (B) are mixed and melt-kneaded.
The thermoplastic resin (A) is composed of a graft copolymer (C) in which a vinyl-based polymer is grafted on a rubber-like polymer and a thermoplastic resin (D) other than the graft copolymer (C). Naru,
The carbon black (B) has a volume average particle diameter of secondary particles in a volume-based particle diameter distribution measured by a dynamic light scattering method for a 0.04 mass% dispersion liquid using N-methylpyrrolidone as a dispersion medium. Is 200 nm or more, and the ratio of the secondary particles having a particle diameter of 800 nm or more to the entire secondary particles is less than 20% by volume.
A method for producing a thermoplastic resin composition, wherein the content of the carbon black (B) is 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin (A). In the volume-based particle size distribution of the carbon black (B), the particle size having a cumulative value of 10% is 10% cumulative particle size (d10), and the particle size having a cumulative value of 50% is 50% cumulative particle size. (D50), claim 1, when the particle size at which the cumulative value is 90% is 90% cumulative particle size (d90), M obtained by the following formula (1) satisfies the following formula (2). The method for producing a thermoplastic resin composition according to the above.
M = (d90-d10) / d50 ... (1)
1.5 ≤ M ≤ 2.5 ... (2) The method for producing a thermoplastic resin composition according to claim 1 or 2, wherein the rubber-like polymer is granular. The method for producing a thermoplastic resin composition according to claim 3, wherein the rubber-like polymer has a volume average particle size of 0.1 to 1 μm. The method for producing a thermoplastic resin composition according to any one of claims 1 to 4, wherein the rubber-like polymer is a butadiene rubber, an acrylic rubber, or a composite rubber thereof. The method for producing a thermoplastic resin composition according to any one of claims 1 to 5, wherein the gel content of the rubber-like polymer is 50 to 99% by mass. The rubber-like polymer is composed of a structural unit based on a vinyl-based monomer.
The invention according to any one of claims 1 to 6, wherein the vinyl-based monomer is at least one selected from the group consisting of an aromatic vinyl compound, a (meth) acrylic acid alkyl ester, and a vinyl cyanide compound. Method for producing a thermoplastic resin composition. The thermoplastic according to any one of claims 1 to 7, wherein the graft copolymer (C) is obtained by polymerizing a vinyl-based monomer in the presence of the rubber-like polymer. A method for producing a resin composition. A method for producing a molded product, wherein the thermoplastic resin composition is produced by the method for producing a thermoplastic resin composition according to any one of claims 1 to 8, and the thermoplastic resin composition is molded.