JP4870380B2 - Granular white resin composition - Google Patents

Description

  The present invention relates to a granular white resin composition for use in the production of a white automotive resin product such as a white automobile bumper, a white automobile interior product, and a white automobile exterior product.

  White automotive resin products such as white automobile bumpers, white automobile interior parts, and white automobile exterior parts are usually added with unused components such as elastomer resin, filler, and white pigment to unused polyolefin resin. Heat-melting granular materials (eg, powder, pellets, flakes, granules, pulverized products) of white polyolefin resin (raw material composition consisting of such unused materials is usually called virgin material) Then, it is manufactured by introducing into a forming die and then cooling. In such a granular product manufacturing process or molded product molding process, a colored resin modified product may be formed by local overheating of the resin melt and mixed into the molded product, and may float in the air. Or fine solid foreign substances adhering to the molding machine may be mixed into the raw resin granules or the resin melt and get mixed into the molded product. When these resin-modified products and solid foreign substances are mixed in the resin molding beyond a certain level, the presence of the colored resin-modified products and solid foreign bodies will appear on the surface of the molding. In particular, since such colored resin-modified products and solid foreign substances are often dark, they are easily noticeable when mixed in a white resin molded product. Further, an automobile in which a white resin molded product in which contamination of a colored resin modified product or solid foreign material has been manifested on the surface is mounted as an automobile part is not preferable because the value of the automobile as a product is lowered. Therefore, a white resin molded product in which contamination of a colored resin modified product or solid foreign material has been revealed on the surface is usually applied to the surface on which the foreign material has been manifested, and is used by covering the foreign material with the coating film. It is being considered to be disposed of as a non-defective product or to be reused as a raw material for resin moldings that will not cause any problems even if such resin-modified products or solid foreign substances are present on the surface of the molding. Yes.

  On the other hand, in recent years, the demand for recycling of various materials has increased. In particular, laws related to advanced recycling of automobile-related materials have been enacted, so automobile manufacturers, automobile accessories manufacturers, and automobile supplies materials are supplied. Material manufacturers and companies that dispose of automotive supplies are working on recycling various materials for automotive supplies. Such objects to be recycled are roughly classified into defective products (usually referred to as process defective products) generated during the production of the above-mentioned resin molded products, and actually mounted on automobiles as products, and the automobiles are used by users. After that, it is divided into recovered products separated from automobiles that were disposed of.

  In Patent Document 1, a pulverized product of a thermoplastic resin product containing a black pigment, a mixture of a pulverized product of a thermoplastic resin product containing a black pigment and a pulverized product of a thermoplastic resin product containing a chromatic pigment, or Prepare a heated melt by mixing and heating a white pigment and a chromatic pigment to a pulverized product of two or more kinds of chromatic pigments having different hues, and then heating the solid melt into a solid particulate form. A method for producing a chromatic color regenerated resin granular material by converting to a product is disclosed.

  In Patent Document 2, a small amount of a cured resin is mixed, and a light-shielding material such as a white pigment, a black pigment, or a chromatic pigment is added to a pulverized thermoplastic resin product containing a black pigment or a chromatic pigment. 1 type or two or more types of conductive pigments are mixed to prepare a heated melt, and then the heated melt is converted into a solid granular material, so that a thermoplastic resin product with a film such as an automobile bumper is applied to the surface coating. There is a disclosure that a recycled resin granular material that can be reused in many fields can be produced without removing the above.

WO 03/095531 A1 brochure WO 03/089500 A1 brochure

  Regarding the resin product pulverized product obtained by recovering and pulverizing the thermoplastic resin product containing the black pigment or the chromatic pigment, it is necessary to carry out a regeneration operation as described in Patent Documents 1 and 2 above. At the same time, it has been found that it can be reused by utilizing a method of regenerating by additionally adding a light shielding pigment.

  However, in the known method, the light shielding pigment to be added while recognizing the state of contamination of the crushed thermoplastic resin product by solid foreign matters at the time of the regeneration operation of the pulverized thermoplastic resin product. There is a complication that the type and amount of addition must be determined.

  The main object of the present invention is to provide a modified colored resin produced when a white thermoplastic resin composition (virgin material) mainly composed of a polyolefin resin is molded to produce a white resin molded product to be mounted on an automobile. An object of the present invention is to provide a technique capable of suppressing the generation of a molded article having a defective appearance, which has been conventionally disposed of as a defective process product due to formation or mixing of solid foreign substances.

  It is another object of the present invention to add a new light-shielding pigment or reuse a new light-shielding pigment when reusing a pulverized white thermoplastic resin product mainly composed of used polyolefin. Another object is to provide a technique that does not require fine adjustment of the amount of pigment added.

  The inventor of the present invention usually uses a small amount of black when producing a granular white resin composition prepared by adding a filler and a white pigment to an unused thermoplastic resin component containing a polyolefin resin and an elastomer resin. By allowing pigments to exist under specific conditions, even if a small amount of colored resin-modified product or solid foreign matter is mixed in a molded product manufactured through heating and melting, such contamination will be manifested on the surface of the resin molded product. It has been found that it is possible to prevent (invisibility), and the present invention has been achieved.

The present invention relates to a granular white resin composition containing an unused thermoplastic resin component containing a polyolefin resin and an elastomer resin, a filler, a white pigment and a black pigment, and the brightness of a sheet prepared from the granular white resin composition The relationship between (L ^* ) and light transmittance satisfies the following formula: a granular white resin composition for producing a resin molded product for automobiles.

1300 ≦ (L ^* × B) ≦ 4000

However, L ^* is the brightness of a sheet having a thickness of 3 mm prepared from the resin composition, and B is the total light transmittance (%) of a sheet having a thickness of 50 μm prepared from the resin composition. L ^* is preferably in the range of 55 to 90, more preferably in the range of 60 to 90, further preferably in the range of 70 to 90, and particularly preferably in the range of 80 to 90. preferable.

  The present invention also resides in a white resin molded article for mounting on an automobile obtained by heating and melting the granular white resin composition and then molding.

Preferred embodiments of the granular white resin composition for producing a resin molded product for mounting on an automobile according to the present invention are as follows.
(1) The brightness represented by L _* of the sheet prepared from the granular white resin composition of the present invention is in the range of 55 to 90 (more preferably in the range of 60 to 90, more preferably in the range of 70 to 90, particularly preferably. 80 to 90).
(2) The total light transmittance represented by B of the sheet prepared from the granular white resin composition of the present invention is in the range of 15 to 60% (more preferably in the range of 18 to 55, more preferably in the range of 20 to 50, The range of 25 to 48 is particularly preferable.
(3) The content of the white pigment in the granular white resin composition of the present invention is 1% by mass or more and 20% by mass or less (more preferably in the range of 1 to 20% by mass, more preferably 1.5 to 18% by mass). In the range of 2 to 15% by mass, most preferably in the range of 3 to 12% by mass).
(4) The white pigment contained in the granular white resin composition of the present invention is titanium dioxide.
(5) The content of the black pigment in the granular white resin composition of the present invention is 0.01% by mass or more and 1.0% by mass or less (more preferably in the range of 0.05 to 0.8% by mass, further The range is preferably in the range of 0.01 to 0.5 mass%, particularly preferably in the range of 0.012 to 0.3 mass%, and the black pigment content is less than the white pigment content.
(6) The black pigment contained in the granular white resin composition of the present invention is iron black.
(7) The whiteness of a sheet having a thickness of 3 mm prepared from the granular white resin composition of the present invention is 55 or more (more preferably 65 or more, more preferably 75 or more, particularly preferably 80 or more).
(8) (L ^* × B) is 1300 or more and 4000 or less (preferably 1500 to 4000, more preferably 1800 to 4000, particularly preferably 2000 to 3800).

  By using the granular white resin composition of the present invention, conventionally, when the granular white resin composition (virgin material) is thermoformed to produce a white resin molded product to be mounted on an automobile, It is possible to suppress the generation of a molded product having a defective appearance that has been generated due to mixing of solid foreign matters and has been disposed of as a defective product.

  Furthermore, a white resin molded product for use in automobiles manufactured using the granular white resin composition of the present invention requires the addition of a new light-shielding pigment when the pulverized product of the molded product after use is reused. Or fine adjustment of the addition amount of a new light-shielding pigment is unnecessary.

  The granular white resin composition of the present invention includes an unused thermoplastic resin component including a polyolefin resin and an elastomer resin, a filler, a white pigment, and a black pigment. The mixing ratio of the polyolefin resin and the elastomer resin in the thermoplastic resin component is usually in a mass ratio of 100: 1 to 100: 80 (preferably in the range of 100: 1 to 100: 50, more preferably 100: 5 to 100: 40).

  Examples of polyolefin resins include polypropylene resins such as crystalline polypropylene, polyethylene resins such as high density polyethylene and low density polyethylene, and mixtures of these resins. The granular white resin composition of the present invention may contain other thermoplastic resin in a small amount as compared with the polyolefin resin. Examples of thermoplastic resins other than such polyolefin resins include polycarbonate resins, polyurethane resins, styrene resins, ABS resins (acrylonitrile-butadiene-styrene resins), polyester resins such as polybutylene terephthalate, polyethylene terephthalate, Modified polyphenylene ethers, polyphenyl ether resins such as polyphenylene sulfide, polyacrylic acid resins such as polymethyl methacrylate, polyamide resins such as 6-nylon, 66-nylon, 12-nylon, 6 / 12-nylon, A polysulfone etc. can be mentioned.

  As the elastomer resin, a thermoplastic low crystalline elastomer having no clear yield point or a thermoplastic amorphous elastomer resin having no clear melting point and yield point, and an elastomer or rubber having rubber elasticity at room temperature Can be used. Specific examples of the elastomer that can be used include thermoplastic elastomers such as styrene elastomers, olefin elastomers, polyester elastomers, polyamide elastomers, and polyurethane elastomers. Elastomer resins may be used alone or in combination of two or more.

  If desired, when the granular white resin composition of the present invention is produced, a recycled resin component may be mixed in a relatively small amount with an unused thermoplastic resin component (virgin material). .

  As the filler, organic fillers and inorganic fillers excluding pigments can be used, but inorganic fillers are preferred. These fillers are preferably light shielding fillers. The filler is preferably added in an amount of 1 to 40 parts by mass, more preferably 2 to 30 parts by mass, with respect to 100 parts by mass of the thermoplastic resin component containing the polyolefin resin and the elastomer resin. A particularly preferable addition amount is 5 to 30 parts by mass with respect to 100 parts by mass of the thermoplastic resin component.

  Inorganic fillers include talc, clay, mica, silica, diatomaceous earth, moss heidi, tismo, wollastonite, montmorillonite, bentonite, dolomite, dosonite, silicates, carbon fiber, glass fiber, barium ferrite, beryllium oxide, water Aluminum oxide (magnesium hydroxide, basic magnesium carbonate, calcium carbonate, magnesium carbonate, magnesium sulfate, calcium sulfate, barium sulfate, ammonium sulfate, calcium sulfite, calcium oxalate, molybdenum sulfide, zinc borate, barium metaborate, calcium borate , Sodium borate, or zinc, copper, iron, lead, aluminum, nickel, chromium, titanium, manganese, tin, platinum, tungsten, gold, magnesium, cobalt, strontium And metal oxides of these metals, alloys such as stainless steel, solder and brass, powders of metal ceramics such as silicon carbide, silicon nitride, zirconia, aluminum nitride and titanium carbide, fibrous whiskers and fibers, etc. Particularly preferred are talc and mica.

  Examples of white pigments include titanium dioxide, white lead, and zinc oxide. Particularly preferred is titanium dioxide.

  As titanium dioxide, those conventionally used for pigments can be used, and for example, those produced by the chlorine method or sulfuric acid method can be used. The thing manufactured by the chlorine method is preferable. The particle shape is not particularly limited, but tetragonal, rutile, and anatase types can be used, and tetragonal and rutile types are particularly preferable. The average particle diameter is not particularly limited, but is preferably 0.01 to 0.5 μm, more preferably 0.05 to 0.5 μm, more preferably 0.1 to 0.4 μm, and particularly preferably 0.2 to 0.00. 3 μm particles are excellent in dispersibility, handleability and workability. The DOP oil absorption amount of titanium dioxide is not particularly limited, but is preferably 5 to 40 (cc / 100 g), more preferably 8 to 30 (cc / 100 g), more preferably 10 to 20 (cc / 100 g), particularly preferably. Is 12 to 18 (cc / 100 g). Two or more types of white pigments can be used in combination.

  Examples of the black pigment include carbon black and iron black. The black pigment can impart high light shielding properties to the white resin molded product. Two or more black pigments can be used in combination.

  As the carbon black, those conventionally used for pigments can be used. For example, carbon black, acetylene black, lamp black, channel black, ketjen black, etc. produced by the furnace method or the channel method are used. Can do. Carbon black can be oxidized. As the carbon black, it is particularly preferable to use furnace black produced by the furnace method because it has excellent appearance uniformity and dispersibility, and the effects of improving the blackness and gloss of the resulting molded product are large. The average particle size of carbon black is not particularly limited, but is preferably 0.001 to 0.3 μm, more preferably 0.005 to 0.2 μm, more preferably 0.01 to 0.1 μm, and particularly preferably 0.00. Those having a thickness of 01 to 0.03 μm are preferable because they are excellent in dispersibility, handleability, and workability, and exhibit high effects in improving blackness and gloss.

  As the iron black, black iron oxide obtained by a firing method can be used. The particle shape of the iron black is not particularly limited, but a polyhedral shape such as an octahedron, a spherical shape, and the like can be used, and an octahedron is particularly preferable. The average particle size of iron black is not particularly limited, but is preferably 0.05 to 0.4 μm, more preferably 0.15 to 0.35 μm, and particularly preferably 0.2 to 0.35 μm. The DOP oil absorption amount of iron black is not particularly limited, but is preferably 10 to 80 (cc / 100 g), more preferably 15 to 50 (cc / 100 g), more preferably 20 to 40 (cc / 100 g), and particularly preferably. Is in the range of 25-35 (cc / 100 g). The pH of the iron black is not limited, but is preferably 9 to 11, and particularly preferably 9 to 10.

  The black pigment added to the granular white resin composition of the present invention is preferably iron black, which has a weaker black color than carbon black. That is, iron black having such characteristics can be easily adjusted to an appropriate brightness and light transmittance by fine adjustment of the addition amount.

  If desired, a small amount of a chromatic pigment may be added to the granular white resin composition of the present invention.

  As the chromatic pigment, known pigments can be used. For example, inorganic pigments such as metal oxides, hydroxides, sulfides, chromates, carbonates, sulfates, silicates; azo series, diphenylmethane series, trivalent pigments. Examples thereof include organic pigments such as phenylmethane, phthalocyanine, nitro, nitroso, anthraquinone, quinacridone red, benzidine and condensed polycyclic. Further, it may be colored fibers or glossy metal particles. There is no restriction | limiting in particular about the hue of a chromatic color pigment, Any things, such as yellow, blue, red, and green, can be used. Two or more kinds of these pigments can be used in combination.

  If desired, the granular white resin composition of the present invention may further contain various resin additives (eg, dispersants such as calcium stearate, lubricants, antistatic agents, surfactants, nucleating agents, ultraviolet absorbers, antioxidants). Agents, flame retardants).

  The filler, white pigment, black pigment, and other optional components to be added as desired may be added directly to unused thermoplastic resin components including polyolefin resin and elastomer resin, or a high concentration pigment may be added in advance. After preparing the resin composition containing (masterbatch), you may utilize the method (masterbatch formation technique) of mixing with the resin composition to which a pigment is not added. A masterbatch technique using various pigments and resin components is already known.

The example of the manufacturing method of the granular white resin composition of this invention is shown below.
(1) Add fillers, white pigments, and black pigments that are estimated to be appropriate amounts to unused thermoplastic resin component granules containing polyolefin resin and elastomer resin, and further, if necessary, chromatic pigments and various resins Additives are added to obtain a granular white resin composition as a mixture.
(2) The above mixture is melt-kneaded, and then sheet-like test pieces for measuring lightness and light transmittance are produced directly or via a granular material.
(3) The lightness and light transmittance of the sheet-like test piece are measured, and the measurement results are compared with the conditions shown in the above formula to determine the suitability of the types and addition amounts of the white pigment and the black pigment. When the product of the lightness and light transmittance (%) of the test piece exceeds 4000 or less than 1300, the type and amount of addition of the white pigment and the black pigment are appropriately changed, and the above (1) Return to the process. When the product of the lightness and light transmittance (%) of the test piece is 1300 or more and 4000 or less, it is used as the granular white resin composition according to the present invention.
By performing the above operation, a granular white resin composition that can be used for molding having a desired color tone, appearance, and physical properties can be produced.

  In the present invention, there are no particular limitations on the mixing method, mixing device, and mixing equipment of the unused thermoplastic resin component granules and each additive component, and there are no particular restrictions on the known single-screw extruder (kneader), twin-screw extruder. (Kneading machine), mixing and / or kneading of a tandem kneading device, a calendar, a banbury mixer, a kneading roll, a brabender, a plastograph, a kneader, etc., in which a twin screw extruder and a single screw extruder (kneading machine) are connected in series A device or the like can be used.

  The granular white resin composition of the present invention is formed by using a known molding or molding method such as extrusion molding, sheet molding, injection molding, injection compression molding, gas injection injection molding, probe molding, vacuum molding, bumper, molding, door trim, It can be used as a white resin molded product used for automobile-mounted parts such as interior and exterior parts for vehicles such as instrument panels, trims, and console boxes, and interior parts of the engine room such as battery trays and air cleaner cases.

  In addition, the granular white resin composition of the present invention is a molded article having an arbitrary surface state such as a molded article having a glossy surface, a molded article having irregularities and patterns such as a drawing, or a molded article having smooth irregularities and patterns. Can be obtained. In addition, the white of the granular white resin composition of the present invention is usually used in a meaning including a white chromatic color called ivory or light gray.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated, this invention is not limited to these Examples.

(1) Measurement of whiteness and hue White resin pellets using an injection molding machine with a clamping force of 130 tons, mold: square plate (100 mm x 100 mm x 3 mm; one side: skin-like shape, one side: mirror surface), molding temperature : C1-C2-C3-C4 = 180-190-200-210 ° C., injection pressure: P1-P2-P3-P4 = 108-98-88-78 MPa, injection speed: V1-V2-V3-V4 = 30- A test piece (thickness: 3 mm) was molded under injection conditions of 30-20-20%, screw back pressure: free, screw rotation speed: 60%, mold temperature: 40 ° C, cycle: injection 10 seconds, cooling 20 seconds. . Measure the L ^* , a ^* , b ^* , L, a, and b using the SM-4 colorimeter of Suga Test Instruments Co., Ltd. Lightness and hue were obtained.

(2) Measurement of light transmittance Using a hot press molding machine with a clamping force of 40 tons, white resin pellets are sandwiched between photographic ferro-type plates (spacer: 70 × 50 × 0.05 mmt), heating plate temperature is 230 ° C., residual heat A film with a thickness of 50 ± 3 μm was prepared under the molding conditions of 2 minutes, defoaming treatment time 1 minute, pressurization time 1 minute (pressure: 100 kg / cm ² ), cooling temperature 20 ° C., cooling time 2 minutes, and transmitted through all rays. A test piece for rate measurement was used.
The total light transmittance was measured for this test piece using a turbidimeter (turbidimeter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.), and the total light transmittance (%) was defined as the light transmittance (%). The light source used was a halogen lamp rating of 5V9W, the light entrance opening diameter was 20 mmφ, and five points of the film were measured and averaged.

(3) Preparation of test piece and appearance evaluation method of narrowed surface 0.05 parts by mass of iron powder having an average particle size of 0.3 mm is added to 100 parts by mass of white resin pellets, and the platen tumbler is used for 5 minutes. Dry blended. Next, a test piece (100 mm × 100 mm × 3 mm, one surface having a skin-like shape and the other surface having a mirror surface) is molded under the above injection molding conditions. Whether or not the presence of the powder was conspicuous in appearance was determined by visual observation. The visual observation results were evaluated in three stages according to the following criteria.
1: Presence of solid foreign matter on both the mirror surface and the skin-squeezed surface is visible (failed)
2: The presence of solid foreign matter is visible on the mirror surface, but the presence of solid foreign matter is hardly visible on the skin-squeezed surface (pass)
3: The presence of solid foreign matter is not visible on both the mirror surface and the leather surface (pass)

[Examples 1-4, Comparative Examples 1-2]
<Materials used>

(1) Polyolefin resin: crystalline polypropylene (virgin resin, MFR = 70 g / 10 min, ethylene / propylene copolymer having an ethylene content of 7% by mass) 65 parts by mass (2) elastomer resin: ethylene-propylene copolymer resin (Virgin material, Mooney viscosity: MI1 + 4 (100 ° C.) = 35, ethylene content: 72% by mass) 20 parts by mass (3) Filler: Talc (hydrous magnesium silicate, average particle size: 2.7 μm) 15 parts by mass ( 4) White pigment: Titanium dioxide (addition amount is described in Table 1 as mass% with respect to the total amount of the above components (1), (2) and (3))
(4) Black pigment: Iron black (addition amount is described in Table 1 as mass% with respect to the total amount of the above components (1), (2) and (3))
(5) Colored pigment: Titanium yellow and petrol (addition amount is described in Table 1 as mass% with respect to the total amount of the above components (1), (2) and (3))
(6) Other additives: Dispersant (calcium stearate, the addition amount is 0.1% by mass with respect to the total amount of the components (1), (2) and (3) above), Irgafos 168: 0 (addition amount) Is 0.1% by mass with respect to the total amount of the above components (1), (2) and (3)), Irganox 1010 (addition amount is the total amount of the above components (1), (2) and (3) 0.1 mass%)

<Manufacture of white resin pellets>
Each component was dry blended using a Platec tumbler and then melt kneaded using a twin-screw kneader (UME40-48T, Ube Industries, Ltd.) at a barrel temperature of 220 ° C. and a throughput of 60 kg / hour. To obtain white resin pellets.

Table 1
────────────────────────────────────
Comparative Example
1 2 1 2 3 4
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<Pigment addition amount>
Titanium Yellow 0.03-0.108 0.16 0.23-
Iron black 0.01 0.01 0.034 0.05 0.08 0.05
Titanium dioxide 1.2 1.2 4.20 6.20 9.20 6.2
Petty----0.002-
────────────────────────────────────
Color tone L ^* 86.5 87.21 86.82 86.79 86.61 87.67
a ^* -1.13 -0.84 -1.19 -1.18 -0.91 -0.89
b ^* 4.31 -0.74 4.5 4.54 4.47 -1.29
L 84.1 84.65 84.34 84.45 84.29 85.44
a -1.79 -1.15 -1.87 -1.91 -1.54 -1.36
b 4.01 -1.24 4.22 4.27 4.23 -1.76
Whiteness W 83.5 84.55 83.69 83.76 83.65 85.27
────────────────────────────────────
Light transmittance (%) 63.7 65.9 44.9 36.2 27.3 37.1
────────────────────────────────────
L ^* x Light transmission 5510 5747 3898 3142 2364 3253
────────────────────────────────────
Appearance evaluation 1 1 2 2-3 3 2-3
────────────────────────────────────

  From the results described in Table 1, the granular white resin composition of the present invention has a high light shielding ability of solid foreign matters mixed in the molded product molded from the resin composition, and therefore, a white resin molded product for automobile mounting. It turns out that it is suitable for the manufacture of things.

Claims (6)

Granules containing an unused thermoplastic resin component including a polyolefin resin and an elastomer resin, a filler, 1.5 to 20% by mass of white titanium dioxide pigment, and 0.01% by mass or more and less than 1.0% by mass of a black pigment A white resin composition, wherein a sheet having a thickness of 3 mm prepared from the granular white resin composition exhibits a whiteness of 55 or more and a lightness (L ^* ) of 55 to 90 , and a thickness prepared from the resin composition. The total light transmittance (%) of the 50 μm sheet is in the range of 15 to 60%, and the relationship between the lightness (L ^* ) and light transmittance of the sheet made from the granular white resin composition satisfies the following formula: A granular white resin composition for producing a resin molded product for automobile mounting, characterized in that:

1300 ≦ (L ^* × B) ≦ 4000

[L ^* is the brightness of a sheet having a thickness of 3 mm prepared from the resin composition, and B is the total light transmittance (%) of a sheet having a thickness of 50 μm prepared from the resin composition]. The granular white resin composition according to claim 1, wherein the content of the white titanium dioxide pigment is in the range of 2 to 15% by mass. The granular white resin composition according to claim 1, wherein the content of the white titanium dioxide pigment is in the range of 3 to 12% by mass. The granular white resin composition according to claim 1, wherein the black pigment content is in the range of 0.012 to 0.3 mass%. The granular white resin composition according to claim 1 or 4, wherein the black pigment is iron black. The white resin molding for motor vehicles obtained by heat-melting the granular white resin composition of any one of Claims 1 thru | or 5, and then shape | molding it.