Resin composition, master batch, black resin composition, black resin molded body, and methods for producing the same

Abstract

To provide a resin composition, a masterbatch, a black resin composition, and a black resin molding which enable molding of a high ebony black molding without need of surface coating, and a method for producing them.SOLUTION: There is provided a resin composition in which carbon-based particles (B) containing carbon black as a main component and a dispersant (C) are dispersed in a (meth)acrylic resin syrup (A), and 25.0-98.9 mass% of a (meth)acrylic resin syrup (A), 1-65 mass% of carbon-based particles (B) containing carbon black as a main component and 0.1-10 mass% of a dispersant (C) are contained with respect to 100 mass% of the total of the (meth)acrylic resin syrup (A), the carbon-based particles (B) and the dispersant (C).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition, a masterbatch, a black resin composition, a black resin molded product, and methods for producing them. [Background technology]

[0002] In recent years, there has been a demand for highly jet-black surfaces to improve the design and give a high-quality appearance to thermoplastic plastic molded products. To achieve this, it is known to finely disperse carbon black (CB) with small particle size and large specific surface area in plastics (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6277335 [Patent Document 2] Patent No. 6356006 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional methods such as those described in Patent Documents 1 and 2, a thermoplastic resin, carbon black, and a dispersant are melt-kneaded by an extruder to obtain a master batch with high jet blackness. However, the carbon black used to realize high jet blackness on the surface has a strong cohesive force, and it is difficult to disperse it with the shear force of normal melt kneading. In order to improve the dispersibility of carbon black, the effect of adjusting the kneading conditions or using a dispersant is limited. Therefore, in order to realize high jet blackness on the surface, it is often dealt with by painting the plastic surface. On the other hand, there is a demand for paint-free molding to reduce processing costs and be environmentally friendly, and there is a strong need for highly jet-black molded products with unprocessed surfaces.

[0005] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a resin composition capable of molding a highly jet-black molded product that does not require surface painting, a masterbatch, a black resin composition, a black resin molded product, and methods for producing them. [Means for solving the problem]

[0006] The present invention includes the following aspects. (1) A resin composition comprising (meth)acrylic resin syrup (A), carbon-based particles (B) mainly composed of carbon black, and a dispersant (C) dispersed therein, the (meth)acrylic resin syrup (A) being 25.0 to 98.9% by mass, the carbon-based particles (B) mainly composed of carbon black, and 0.1 to 10% by mass of the dispersant (C) being 100% by mass in total of the (meth)acrylic resin syrup (A), the carbon-based particles (B), and the dispersant (C). (2) The (meth)acrylic resin syrup (A) contains a (meth)acrylic monomer and a (meth)acrylic polymer, and the (meth)acrylic monomer is 40 to 90 mass% and the (meth)acrylic polymer is 10 to 60 mass% relative to 100 mass% in total of the (meth)acrylic monomer and the (meth)acrylic polymer. The resin composition according to (1). (3) The resin composition according to (1) or (2) above, further comprising a polymerization initiator (D). (4) A master batch comprising granular cured material obtained by curing the resin composition described in (3) above. (5) A black resin composition comprising the masterbatch according to (4) above and a thermoplastic resin (E). (6) A black resin molded product obtained by melt molding the black resin composition according to (5) above. (7) There are no carbon black agglomerates with a diameter of 100 μm or more on the surface, and the surface is within 48 mm 2 The black resin molding according to (6) above, wherein the number of carbon black aggregates each having a diameter of less than 10 μm is 10 or less. (8) A method for producing a resin composition, comprising the steps of blending (meth)acrylic resin syrup (A), carbon-based particles (B) mainly composed of carbon black, and a dispersant (C), and dispersing the carbon-based particles (B) and the dispersant (C) in the (meth)acrylic resin syrup (A). (9) The method for producing a resin composition according to (8) above, wherein the (meth)acrylic resin syrup (A) contains a (meth)acrylic monomer and a (meth)acrylic polymer. (10) The method for producing a resin composition according to (8) or (9) above, further comprising a step of mixing a polymerization initiator (D) into the (meth)acrylic resin syrup (A). (11) A method for producing a masterbatch, comprising the steps of obtaining a resin composition by the production method described in (10) above, curing the functional resin composition to obtain a cured product, and crushing the cured product to obtain granules. (12) A method for producing a black resin composition, comprising the steps of obtaining a masterbatch by the production method according to (11) above, and mixing and / or melt-kneading the masterbatch with a thermoplastic resin (E). (13) A method for producing a black resin molded product, comprising the steps of obtaining a black resin composition by the method according to (12) above, and melt-molding the black resin composition. Effect of the Invention

[0007] According to the present invention, it is possible to provide a resin composition capable of molding a highly jet-black molded article that does not require surface painting, a masterbatch, a black resin composition, a black resin molded article, and methods for producing them. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is an optical microscope photograph of the black molded body according to Example 1. [Diagram 2] FIG. 4 is an optical microscope photograph of a black molded body according to Example 2. [Diagram 3] FIG. 11 is an optical microscope photograph of a black molded body according to Example 3. [Figure 4]FIG. 11 is an optical microscope photograph of a black molded body according to Example 4. [Diagram 5] FIG. 2 is an optical microscope photograph of a black molded body according to Comparative Example 1. [Figure 6] FIG. 11 is an optical microscope photograph of a black molded body according to Comparative Example 2. [Figure 7] FIG. 11 is an optical microscope photograph of a black molded body according to Comparative Example 3. [Figure 8] FIG. 11 is an optical microscope photograph of a black molded body according to Comparative Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Resin composition> The resin composition according to this embodiment is obtained by dispersing carbon-based particles (B) (hereinafter sometimes referred to as “component (B)”) mainly composed of carbon black and a dispersant (C) (hereinafter sometimes referred to as “component (C)”) in a (meth)acrylic resin syrup (A) (hereinafter sometimes referred to as “component (A)”). The resin composition according to the present embodiment is preferably applied to molding of a highly jet-black molded article, and more preferably applied to molding of a highly jet-black molded article that does not require surface painting.

[0010] [Component (A): (meth)acrylic resin syrup] The component (A) is a monomer or a monomer mixture in which a (meth)acrylic oligomer or polymer is dissolved. The component (A) is a so-called in situ polymerizable monomer.

[0011] The component (A) preferably contains a (meth)acrylic monomer and a (meth)acrylic polymer. When component (A) contains a (meth)acrylic monomer and a (meth)acrylic polymer, the (meth)acrylic monomer is preferably 40 to 90 mass% and the (meth)acrylic polymer is 10 to 60 mass%, more preferably the (meth)acrylic monomer is 45 to 85 mass% and the (meth)acrylic polymer is 15 to 55 mass%, and even more preferably the (meth)acrylic monomer is 50 to 80 mass% and the (meth)acrylic polymer is 20 to 50 mass%, relative to 100 mass% in total of the (meth)acrylic monomer and the (meth)acrylic polymer. When the content of the (meth)acrylic monomer and (meth)acrylic polymer in the component (A) is within the above range, it is easy to achieve a viscosity suitable for in-situ polymerization.

[0012] The dynamic viscosity of component (A) is preferably 10 mPa·s to 10,000 mPa·s, more preferably 50 mPa·s to 5,000 mPa·s, and even more preferably 100 mPa·s to 1,000 mPa·s. It is preferably 10 mPa·s or more, more preferably 50 mPa·s or more, and even more preferably 100 mPa·s or more, and is preferably 10,000 mPa·s or less, more preferably 5,000 mPa·s or less, and even more preferably 1,000 mPa·s or less. When the dynamic viscosity of component (A) is within the above-mentioned preferred range, components (B) and (C) are easily dispersed in component (A). On the other hand, when the dynamic viscosity of component (A) is equal to or greater than the lower limit of the above-mentioned preferred range, the handleability of the resin composition is easily improved. The viscosity of component (A) can be easily measured with a rheometer. Dynamic viscosity is measured at 25°C. Component (A) exhibits Newtonian behavior and does not thin with shear. Therefore, dynamic viscosity is independent of shear in a rheometer and independent of mobile velocity in a viscometer. .

[0013] Specific examples of the component (A) include the ELIUM series manufactured by Arkema.

[0014] The component (A) may use one type alone, or two or more types.

[0015] In the resin composition according to this embodiment, the content of the (A) component, relative to 100% by mass of the total of the (A), (B), and (C) components, is 25.0% by mass or more, preferably 30.0% by mass or more, and more preferably 45.0% by mass or more, and is 98.9% by mass or less, preferably 97.5% by mass or less, and more preferably 95.0% by mass or less. When the content of component (A) is equal to or greater than the lower limit of the above range, components (B) and (C) are easily dispersed in component (A). On the other hand, when the content of component (A) is equal to or less than the upper limit of the above range, the handleability of the resin composition is easily improved.

[0016] [Component (B): Carbon-based particles mainly composed of carbon black] The component (B) is carbon-based particles containing preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 95% by mass or more of carbon black.

[0017] Examples of carbon black in component (B) include channel black, oil furnace black, gas furnace black, thermal black, acetylene black, and bone black.

[0018] The average primary particle size of the component (B) is preferably from 5 nm to 1 μm, more preferably from 10 nm to 500 nm, and even more preferably from 10 nm to 100 nm. When the average primary particle size of component (B) is equal to or greater than the lower limit of the above-mentioned preferred range, high jet blackness is easily achieved. On the other hand, when the average primary particle size of component (B) is equal to or less than the upper limit of the above-mentioned preferred range, the brightness is easily reduced and good dispersibility is easily achieved.

[0019] The average primary particle diameter of component (B) is obtained by obtaining a primary particle image of component (B) by observation with a transmission electron microscope (TEM), measuring the particle diameter of each of approximately 200 to 300 particles, and calculating the average value.

[0020] The specific surface area of ​​component (B) is preferably 10 m 2 / g or more, more preferably 20m 2 / g or more, more preferably 40m 2 / g or more, and preferably 700m 2 / g or less, more preferably 650m 2 / g or less, more preferably 600m 2 / g or less. When the specific surface area of ​​component (B) is equal to or greater than the lower limit of the above-mentioned preferred range, a uniform jet black color is easily obtained. On the other hand, when the specific surface area of ​​component (B) is equal to or less than the upper limit of the above-mentioned preferred range, aggregation of component (B) is easily suppressed, and a uniform black color is easily obtained.

[0021] The specific surface area of ​​component (B) can be measured in accordance with JIS K6217-2.

[0022] The surface of component (B) may be physically or chemically treated, which provides good dispersibility.

[0023] The component (B) may use one type alone, or two or more types.

[0024] In the resin composition according to this embodiment, the content of the (B) component, relative to 100% by mass of the total of the (A), (B), and (C) components, is 1% by mass or more, preferably 2% by mass or more, and more preferably 5% by mass or more, and is 65% by mass or less, preferably 60% by mass or less, and more preferably 55% by mass or less. When the content of component (B) is equal to or greater than the lower limit of the above range, high jet blackness is easily achieved, whereas when the content of component (B) is equal to or less than the upper limit of the above range, the dispersibility of component (B) is easily improved.

[0025] [Component (C): Dispersant] The component (C) is not particularly limited as long as it is a known pigment dispersant applied to carbon black. Examples of the component (C) include polyvinyl alcohols, polyvinylpyrrolidones, acrylic resins such as acrylic acid-acrylate copolymers, styrene-acrylic resins such as styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylate copolymers, styrene-α-methylstyrene-acrylic acid copolymers, and styrene-α-methylstyrene-acrylic acid-acrylate copolymers, aqueous resins of styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, and vinylnaphthalene-acrylic acid copolymers, as well as salts of the aqueous resins, zinc stearate, magnesium stearate, calcium stearate, oleic acid amide, stearic acid amide, palmitic acid amide, methylene bisstearylamide, and ethylene bisstearylamide (EBS).

[0026] Specific examples of the component (C) that can be used include the Ajisper PB series manufactured by Ajinomoto Fine-Techno Co., Ltd., the Disperbyk series manufactured by BYK Japan K.K., the EFKA series manufactured by BASF, the SOLSPERSE series manufactured by The Lubrizol Japan Co., Ltd., and the TEGO series manufactured by EVONIK.

[0027] The component (C) may be used alone or in combination of two or more types.

[0028] In the resin composition according to this embodiment, the content of the (C) component, relative to 100% by mass of the total of the (A), (B), and (C) components, is 0.1% by mass or more, preferably 0.5% by mass or more, and 10% by mass or less, preferably 7.5% by mass or less, and more preferably 5.0% by mass or less. When the content of component (C) is equal to or greater than the lower limit of the above range, the dispersibility of component (B) is likely to be good, whereas when the content of component (C) is equal to or less than the upper limit of the above range, high jet blackness is likely to be achieved.

[0029] [Component (D): Polymerization initiator] The resin composition according to the present embodiment may further contain a polymerization initiator (D) (hereinafter, sometimes referred to as "component (D)"). When the resin composition contains component (D), in-situ polymerization of the resin composition is easily promoted.

[0030] The component (D) is not particularly limited as long as it is a known polymerization initiator for the component (A). Examples of the component (D) include diacyl peroxides, peroxy esters, dialkyl peroxides, peroxy acetals, and azo compounds.

[0031] Specific examples of component (D) include isopropyl carbonate, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, dicumyl peroxide, tert-butyl perbenzoate, tert-butyl per(2-ethylhexanoate), cumyl hydroperoxide, 1,1-di(tert-butylperoxy)-3,3,5-trimethyl-cyclohexane, tert-butylperoxyisobutyrate, tert-butyl peracetate, tert-butyl perpivalate, amyl perpivalate, tert-butyl peroctoate, azobisisobutyronitrile (AIBN), azobisisobutyramide, 2,2'-azo-bis(2,4-dimethylvaleronitrile), and 4,4'-azobis(4-cyanopentane).

[0032] The component (D) may use one type alone, or two or more types.

[0033] In the resin composition according to this embodiment, the content of the (D) component, relative to 100 parts by mass of the (A) component, is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, even more preferably 1.5 parts by mass or more, and is preferably 11 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 9.0 parts by mass or less. When the content of the component (D) is within the above preferred range, the polymerization reaction of the component (A) tends to proceed smoothly.

[0034] The resin composition according to this embodiment is obtained by dispersing carbon-based particles (B) mainly composed of carbon black and a dispersant (C) in a (meth)acrylic resin syrup (A). In this embodiment, by using the component (A) as the resin component, it is possible to finely disperse the component (B), which is difficult to disperse by the shear force in normal melt kneading. In addition, the resin composition according to this embodiment can be polymerized in situ, and the dispersed state can be maintained by curing. Furthermore, the resin composition according to this embodiment has thermoplastic properties even after curing, and therefore can be used as a masterbatch. Therefore, the resin composition according to this embodiment can be used to mold a highly jet-black molded product that does not require surface painting.

[0035] <Master batch> The master batch according to the present embodiment is made of granular cured material obtained by curing the resin composition. The masterbatch according to the present embodiment is obtained from the cured product of the resin composition. Therefore, the component (B) is finely dispersed in the polymer matrix formed by polymerization of the component (A). Therefore, the masterbatch according to the present embodiment can be used to mold highly jet-black molded products that do not require surface painting.

[0036] <Black resin composition> The black resin composition according to this embodiment contains the masterbatch and a thermoplastic resin (E).

[0037] [Component (E): Thermoplastic resin] The thermoplastic resin (E) (hereinafter, sometimes referred to as "component (E)") is not particularly limited, and any known thermoplastic resin for masterbatches can be used. Examples of component (E) include polyolefin resins such as polyethylene resin and polypropylene resin, polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, polycarbonate resin, polyamide resin, polyester resin, polybutylene terephthalate resin, and polymethyl methacrylate resin (PMMA).

[0038] The component (E) may be used alone or in combination of two or more types.

[0039] In the resin composition according to this embodiment, the content of the (E) component, relative to 100% by mass of the total of the master batch and the (E) component, is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and is preferably 99% by mass or less, more preferably 97.5% by mass or less, even more preferably 95% by mass or less. When the content of component (E) is within the above preferred range, it is easy to obtain the desired highly jet-black molded product.

[0040] The black resin composition according to this embodiment may contain various additives, such as pigments other than the black pigment, ester wax, polyethylene wax, antioxidants, ultraviolet absorbers, various stabilizers such as antistatic agents, flame retardants, and surfactants, as long as the effects of the present invention are not impaired.

[0041] The black resin composition according to the present embodiment contains the masterbatch, and therefore, the black resin composition according to the present embodiment can be used to mold highly jet-black molded products that do not require surface painting.

[0042] <Black resin molding> The black resin molded article according to this embodiment is produced by melt molding the black resin composition. In the present embodiment, the melt molding method is not particularly limited, and known molding methods such as injection molding and extrusion molding can be applied.

[0043] The black resin molding according to this embodiment has a surface free of carbon black aggregates with a diameter of 100 μm or more, and is 48 mm 2 When the number of carbon black aggregates each having a diameter of less than 10 μm is 10 or less, the surface tends to have good jet blackness.

[0044] The carbon black aggregates on the surface of the black resin molded body can be measured using an optical microscope with a magnification of 50 or more, a digital microscope, or the like. The optical microscope is not particularly limited, but for example, an "LV100D-U" (manufactured by Nikon Corporation) can be used. 2 The number of carbon black aggregates with a diameter of less than 10 μm per unit area was determined by, for example, measuring 10 random locations on the surface of a black resin molded product (area of ​​each location: 4.8 mm 2 ) can be measured and used as the total number of aggregates.

[0045] The black resin molded article according to the present embodiment is obtained by melt molding a black composition containing the masterbatch, and therefore the black resin molded article according to the present embodiment can exhibit a high jet black color even without a surface coating.

[0046] <Method of producing resin composition> The method for producing a resin composition according to this embodiment includes a step of blending the components (A), (B) and (C) and dispersing the components (B) and (C) in the component (A). In this embodiment, the components (A), (B) and (C) are the same as the components (A), (B) and (C) in the resin composition.

[0047] There are no particular limitations on the method for dispersing components (B) and (C) in component (A), and examples include methods using a wet grinder or a colloid mill.

[0048] A wet grinding pump is a wet grinding pump that can simultaneously grind, disperse, mix, and pump solids in liquid. A wet grinding pump is preferably a mechanism that grinds solids with fixed blades and rotary blades, or rotary blades and grids while pumping them in liquid, and more preferably a mechanism that grinds solids in three stages by combining four parts: cutting blades, grinding impeller, shroud ring, and grid.

[0049] A colloid mill is a machine used to reduce particle size in a dispersion where the particles are suspended in a liquid. A colloid mill consists of a rotor-stator combination, where the rotor rotates at high speed against a fixed stator. The high speed rotation creates high levels of shear, which is used to reduce the particle size in the liquid.

[0050] The method for producing a resin composition according to this embodiment may further include a step of mixing the component (D) into the component (A). The method for mixing component (D) into component (A) is not particularly limited, but typically, components (B) and (C) are dispersed in component (A), and then component (D) is added and stirred. The stirring time is, for example, 1 minute to 1 hour.

[0051] According to the method for producing a resin composition of this embodiment, by using the component (A) as a resin component, it is possible to finely disperse the component (B), which is difficult to disperse by the shear force in normal melt kneading, by wet dispersion treatment, etc. Therefore, according to the method for producing a resin composition of this embodiment, a resin composition capable of expressing high jet blackness can be obtained.

[0052] <Masterbatch manufacturing method> The method for producing a masterbatch according to this embodiment includes a step of obtaining a resin composition by the production method according to the embodiment (hereinafter, sometimes referred to as a "resin composition production step"); a step of curing the functional resin composition to obtain a cured product (hereinafter, sometimes referred to as a "curing step"); and a step of crushing the cured product to obtain granules (hereinafter, sometimes referred to as a "crushing step").

[0053] (Resin composition manufacturing process) The resin composition production process is the same as the above-mentioned resin composition production method.

[0054] (hardening process) In the curing step, the resin composition obtained in the resin composition production step is cured. Typically, a polymerization initiator (D) is added to the resin composition, and the polymerization reaction is allowed to proceed at 15°C to 40°C, preferably 20 to 30°C, for 15 minutes to 5 hours, preferably 30 minutes to 3 hours, to cure the resin composition and obtain a cured product. The (D) component may be mixed with the (A) component in the resin composition production step.

[0055] (Crushing process) In the crushing step, the cured product is crushed to obtain granules (master batch). The crushing method is not particularly limited, and any known crushing means such as a cutter mill, a comb crusher, a hammer mill, a jaw crusher, a rotor mill, a cutting mill, a knife mill, a disk mill, or a freezing crusher can be used.

[0056] According to the method for producing a masterbatch of this embodiment, a cured product of a resin composition is obtained by in-situ polymerization, and the cured product is pulverized to obtain a masterbatch. According to this embodiment, a masterbatch is obtained in which component (B) is finely dispersed in a polymer matrix in which component (A) is polymerized. Therefore, according to the method for producing a masterbatch of this embodiment, a masterbatch that is highly practical and can exhibit high jet blackness is obtained.

[0057] <Method of producing black resin composition> The method for producing a black resin composition according to this embodiment includes a step of obtaining a masterbatch by the production method according to the embodiment (hereinafter, may be referred to as a "masterbatch production step"), and a step of mixing and / or melt-kneading the masterbatch with a thermoplastic resin (E) (hereinafter, may be referred to as a "mixing / melt-kneading step").

[0058] (Masterbatch manufacturing process) The masterbatch production process is the same as the above-mentioned masterbatch production method.

[0059] (Mixing / melting / kneading process) The method for mixing and / or melt-kneading the master batch and the component (E) is not particularly limited, and any known mixing means may be used. When the masterbatch and the component (E) are melt-kneaded, the melt-kneading temperature is typically 100 to 350°C.

[0060] According to the method for producing a black resin composition according to the present embodiment, since the master batch is used, a black resin composition capable of exhibiting high jet blackness can be easily obtained.

[0061] <Method of manufacturing black resin molded body> The method for producing a black resin molded body according to this embodiment includes a step of obtaining a black resin composition by the production method according to the embodiment (hereinafter, may be referred to as a "black resin composition production step"), and a step of melt-molding the black resin composition (hereinafter, may be referred to as a "melt-molding step").

[0062] (Black resin composition manufacturing process) The process for producing the black resin composition is the same as the process for producing the black resin composition described above.

[0063] (Melt molding process) The melt molding method is not particularly limited, and known molding methods such as injection molding and extrusion molding can be used. The molding temperature is typically 100 to 350° C. The molding time is typically 1 second to 10 minutes.

[0064] According to the method for producing a black resin molded article according to this embodiment, a black composition containing the masterbatch is melt-molded, so that a black resin molded article that can exhibit high jet blackness can be obtained even without surface coating. EXAMPLES

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0066] (Example 1: Production of black molded body (1)) Carbon black (PM-8000 (Birla) 6% by mass), in situ polymerization type acrylic monomer (Elium 188 O (Arkema) 93% by mass) and dispersant (BYK-9076 (BYK-Chemie) 1 wt % were dispersed in a wet bead mill to obtain a resin composition (1). To 93% by mass of the resin composition (1), 7% by mass of peroxide (Niper FF (manufactured by NOF Corp.) was added, and the mixture was stirred in a beaker with a magnetic stirrer for 10 minutes. The mixture was then removed from a metal tray and kept at room temperature for 12 hours to obtain a cured product. The obtained cured product was pulverized to obtain a master batch (1). The master batch (1) was blended with PMMA resin (TF9 (manufactured by Mitsubishi Chemical Corporation)) so that the carbon black content was 1%, to obtain a black resin composition (1). The obtained black resin composition was used in an injection molding machine (cylinder temperature 230°C, mold temperature 50°C) to produce a D2 test piece (black molded body (1)).

[0067] (Example 2: Production of black molded body (2)) Carbon black (FW-200 (Orion) 6% by mass), in-situ polymerization type acrylic monomer (Elium 188 O (Arkema) 93% by mass) and dispersant (BYK-9076 (BYK-Chemie) 1 wt % were dispersed in a wet bead mill to obtain a resin composition (2). To 93% by mass of resin composition (2), 7% by mass of peroxide (Niper FF (manufactured by NOF Corp.) was added, and the mixture was stirred in a beaker with a magnetic stirrer for 10 minutes. The mixture was then removed from a metal tray and kept at room temperature for 12 hours to obtain a cured product. The obtained cured product was pulverized to obtain a master batch (2). The master batch (2) was blended with PMMA resin (TF9 (manufactured by Mitsubishi Chemical Corporation)) so that the carbon black content was 1%, to obtain a black resin composition (1). The obtained black resin composition was used in an injection molding machine (cylinder temperature 230°C, mold temperature 50°C) to produce a D2 test piece (black molded body (2)).

[0068] (Example 3: Production of black molded body (3)) Carbon black (PM-8000 (Birla) 6% by mass), in situ polymerization type acrylic monomer (Elium 188 O (Arkema) 93% by mass) and dispersant (BYK-9076 (BYK-Chemie) 1 wt % were dispersed in a wet bead mill to obtain a resin composition (1). To 93% by mass of the resin composition (1), 7% by mass of peroxide (Niper FF (manufactured by NOF Corp.) was added, and the mixture was stirred in a beaker with a magnetic stirrer for 10 minutes. The mixture was then removed from a metal tray and kept at room temperature for 12 hours to obtain a cured product. The obtained cured product was pulverized to obtain a master batch (1). The master batch (1) was blended with polystyrene resin (CR2500 (DIC)) so that the carbon black content was 1%, to obtain a black resin composition (3). The obtained black resin composition was used in an injection molding machine (cylinder temperature 230°C, mold temperature 50°C) to produce a D2 test piece (black molded body (3)).

[0069] (Example 4: Production of black molded body (4)) Carbon black (FW-200 (Orion) 6% by mass), in-situ polymerization type acrylic monomer (Elium 188 O (Arkema) 93% by mass) and dispersant (BYK-9076 (BYK-Chemie) 1 wt % were dispersed in a wet bead mill to obtain a resin composition (2). To 93% by mass of resin composition (2), 7% by mass of peroxide (Niper FF (manufactured by NOF Corp.) was added, and the mixture was stirred in a beaker with a magnetic stirrer for 10 minutes. The mixture was then removed from a metal tray and kept at room temperature for 12 hours to obtain a cured product. The obtained cured product was pulverized to obtain a master batch (2). The master batch (2) was blended with polystyrene resin (CR2500 (DIC)) so that the carbon black content was 1%, to obtain a black resin composition (4). The obtained black resin composition was used in an injection molding machine (cylinder temperature 230°C, mold temperature 50°C) to produce a D2 test piece (black molded body (4)).

[0070] (Comparative Example 1: Production of black molded body (1')) 5% by mass of carbon black (PM-8000 (manufactured by Birla)), 94.5% by mass of PMMA resin (ACRYPET (manufactured by Mitsubishi Chemical Corporation)), and 0.5% by mass of dispersant (magnesium stearate) were kneaded in a twin-screw extruder TEM-26SX (manufactured by Shibaura Machine Co., Ltd.) (cylinder temperature 220°C, screw rotation speed 300 rpm, discharge rate 10 kg / hr) to obtain master batch (1'). The master batch (1') was blended with PMMA resin (TF9 (manufactured by Mitsubishi Chemical Corporation)) so that the carbon black content was 1%, to obtain a black resin composition (1'). The obtained black resin composition was used in an injection molding machine (cylinder temperature 230°C, mold temperature 50°C) to produce a D2 test piece (black molded body (1')).

[0071] (Comparative Example 2: Production of black molded body (2')) 5% by mass of carbon black (FW-200 (manufactured by Orion)), 94.5% by mass of PMMA resin (ACRYPET (manufactured by Mitsubishi Chemical Corporation)), and 0.5% by mass of dispersant (magnesium stearate) were kneaded in a twin-screw extruder TEM-26SX (manufactured by Shibaura Machine Co., Ltd.) (cylinder temperature 220°C, screw rotation speed 300 rpm, discharge rate 10 kg / hr) to obtain masterbatch (2'). The master batch (2') was blended with PMMA resin (TF9 (manufactured by Mitsubishi Chemical Corporation)) so that the carbon black content was 1%, to obtain a black resin composition (2'). The obtained black resin composition was used in an injection molding machine (cylinder temperature 230°C, mold temperature 50°C) to produce a D2 test piece (black molded body (2')).

[0072] (Comparative Example 3: Production of black molded body (3')) 5% by mass of carbon black (PM-8000, manufactured by Birla), 94.5% by mass of polystyrene resin (CR-2500, manufactured by DIC Corporation) and 0.5% by mass of dispersant (magnesium stearate) were kneaded in a twin-screw extruder TEM-26SX (manufactured by Shibaura Machine Co., Ltd.) (cylinder temperature 220°C, screw rotation speed 300 rpm, discharge rate 10 kg / hr) to obtain masterbatch (3'). The master batch (3') was blended with polystyrene resin (CR-2500 (DIC)) so that the carbon black content was 1%, to obtain a black resin composition (3'). The obtained black resin composition was used in an injection molding machine (cylinder temperature 230°C, mold temperature 50°C) to produce a D2 test piece (black molded body (3')).

[0073] (Comparative Example 2: Production of black molded body (4')) 5% by mass of carbon black (FW-200 (manufactured by Orion)), 94.5% by mass of polystyrene resin (CR-2500 (manufactured by DIC)), and 0.5% by mass of dispersant (magnesium stearate) were kneaded in a twin-screw extruder TEM-26SX (manufactured by Shibaura Machine Co., Ltd.) (cylinder temperature 220°C, screw rotation speed 300 rpm, extrusion rate 10 kg / hr) to obtain masterbatch (4'). The master batch (4') was blended with polystyrene resin (CR-2500 (DIC)) so that the carbon black content was 1%, to obtain a black resin composition (4'). The obtained black resin composition was used in an injection molding machine (cylinder temperature 230°C, mold temperature 50°C) to produce a D2 test piece (black molded body (4')).

[0074] (Evaluation of dispersibility) The surface conditions of the D2 test pieces obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were observed at 10 points each using an optical microscope with a magnification of 50. The observed images are shown in Figures 1 to 8, respectively. As a result, no carbon black aggregates with a diameter of 100 μm or more were observed in the D2 test pieces of Examples 1 to 4 (Figures 1 to 4), and no carbon black aggregates with a diameter of 100 μm or more were observed within 48 mm of the molded product surface. 2 On the other hand, carbon black agglomerates with diameters of 100 μm or more were observed in the D2 test pieces of Comparative Examples 1 to 4 (FIGS. 5 to 8), and carbon black agglomerates with diameters of 100 μm or more were observed within 48 mm of the molded product surface. 2 More than 100 carbon black aggregates smaller than 10 μm were identified in the sample.

Claims

1. The present invention comprises a (meth)acrylic resin syrup (A) in which carbon-based particles (B) containing carbon black as a main component and a dispersant (C) are dispersed, with respect to a total of 100% by mass of the (meth)acrylic resin syrup (A), the carbon-based particles (B), and the dispersant (C), A resin composition for black masterbatches, comprising 25.0 to 98.9 mass% of a (meth)acrylic resin syrup (A), 1 to 65 mass% of carbon-based particles (B) mainly composed of carbon black, and 0.1 to 10 mass% of a dispersant (C).

2. The (meth)acrylic resin syrup (A) contains a (meth)acrylic monomer and a (meth)acrylic polymer, and the (meth)acrylic monomer is 40 to 90 mass% and the (meth)acrylic polymer is 10 to 60 mass% relative to a total of 100 mass% of the (meth)acrylic monomer and the (meth)acrylic polymer. The resin composition for black master batches according to claim 1.

3. The resin composition for black masterbatches according to claim 1 or 2, further comprising a polymerization initiator (D).

4. A masterbatch comprising granular cured material obtained by curing the resin composition for black masterbatches according to claim 3.

5. A black resin composition comprising the masterbatch according to claim 4 and a thermoplastic resin (E).

6. A black resin molded article obtained by melt molding the black resin composition according to claim 5.

7. 7. The black resin molding according to claim 6, wherein there are no carbon black agglomerates having a diameter of 100 μm or more on the surface, and there are 10 or less carbon black agglomerates having a diameter of less than 10 μm per 48 mm2.

8. A method for producing a resin composition for black master batches, comprising the steps of blending (meth)acrylic resin syrup (A), carbon-based particles (B) mainly composed of carbon black, and a dispersant (C), and dispersing the carbon-based particles (B) and the dispersant (C) in the (meth)acrylic resin syrup (A).

9. The method for producing a resin composition for black master batches according to claim 8, wherein the (meth)acrylic resin syrup (A) contains a (meth)acrylic monomer and a (meth)acrylic polymer.

10. The method for producing a resin composition for black master batches according to claim 8 or 9, further comprising a step of mixing a polymerization initiator (D) into the (meth)acrylic resin syrup (A).

11. A method for producing a masterbatch, comprising the steps of: obtaining a resin composition by the production method according to claim 10; curing the resin composition to obtain a cured product; and crushing the cured product to obtain granules.

12. Obtaining a masterbatch by the method according to claim 11; and mixing and / or melt-kneading the masterbatch with a thermoplastic resin (E).

13. Obtaining a black resin composition by the production method according to claim 12; melt-molding the black resin composition; A method for producing a black resin molded body having the above structure.

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