JP3149710B2 - High gloss resin molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded product used for exterior parts of automobiles, and more particularly to a high gloss resin molded product having a high glossiness.

[0002]

2. Description of the Related Art Side moldings, bumper corners and the like used for exterior parts of automobiles are required to have a high glossiness, that is, high glossiness, in order to obtain a beautiful appearance. on the other hand,
Exterior products such as side moldings are easy to assemble to automobiles,
From the viewpoint of flexibility, strength and the like, a resin molded body is usually used.

[0003] As the resin molded body, there are a polypropylene resin containing glass fiber (hereinafter referred to as PPG), a polyolefin thermoplastic elastomer, and the like.
There are olefin-based composite materials. Then, in order to exhibit the high gloss, the surface of the resin molded body is coated with a metallic or solid paint.

[0004]

However, the above-mentioned conventional resin molded article having high gloss has the following problems. That is, since the above-mentioned coating process is required, the manufacturing process cannot be rationalized, and the cost increases. Further, if the resin molded body is simply colored by adding a pigment in order to omit the coating step, a high quality applicable to exterior products cannot be obtained.

Conventionally, as a technique for improving the high glossiness and metallic feeling of a colored resin, a method of specifying a pigment component or a pigment dispersant (JP-A-1-308441-2, 25584).
2,4-7363, 2-214747, 5-27809
9, JP-A-61-138652), which is based on an improvement in the method of producing a colored resin (JP-A-51-49264;
-301748) and a resin composition improved (Japanese Patent Application Laid-Open No. 60-152543, 62-84142) have been proposed, but none of them have provided the same high glossiness and metallic feeling as those of painted products.

That is, when the coating step is omitted, the same high glossiness and metallic feeling as those of the coated product cannot be exhibited, and the scratch resistance is inferior to that of the coated product.
The present invention has been made in view of the above-mentioned conventional problems, and can achieve high glossiness, metallic feeling, and scratch resistance comparable to those of a coated product, and can omit a coating process. And a high-gloss resin molded article.

[0007]

The present invention relates to a resin molded article comprising a core layer and a skin layer coated around the core layer,
The core layer is made of a polypropylene-based composite material, while the skin layer is made of a mixture of a polypropylene resin and a coloring agent, and the polypropylene resin in the skin layer contains or contains less than 6% by weight of ethylene. It does not contain, and Ri polypropylene resin der the Rockwell hardness to have a crystallinity becomes 85 or more, the scan
A high-gloss resin molded article characterized in that a transparent layer is formed on a surface layer of a kin layer .

The polypropylene resin in the skin layer is a polypropylene resin containing no ethylene or containing 6% by weight or less of ethylene and having a Rockwell hardness of 85 or more. As a result, it is possible to reliably obtain the same high glossiness, metallic feeling, and scratch resistance as the painted product. When the ethylene content exceeds 6% by weight or when the Rockwell hardness of the polypropylene resin is less than 85, high glossiness, metallic feeling, and scratch resistance comparable to those of a coated product are obtained. Can not do.

[0009] Examples of the polypropylene resin for the skin layer include crystalline homopolypropylene, crystalline propylene-ethylene random copolymer, crystalline propylene-ethylene block copolymer, and mixtures thereof.

Of these, a highly crystalline polypropylene resin having a high isotactic index (Rockwell hardness of 95 or more) is particularly preferred. Further, among these, a highly crystalline homopolypropylene resin (Rockwell hardness of 105 or more) is most preferable. Thereby, higher glossiness, metallic feeling, and scratch resistance can be further obtained. Here, the isotactic index is defined as ¹³ C-
It is an isotactic fraction in a triad unit of a methyl group by an NMR method.

It is preferable that the polypropylene composite material in the core layer contains one or both of a rubber component and an inorganic filler in a polypropylene resin. As a result, a core layer having appropriate flexibility and rigidity can be obtained. The polypropylene resin for the core layer includes homopolypropylene, block polypropylene, random polypropylene, and a mixture thereof.

Further, the rubber component is made of amorphous ethylene-
It is preferably at least one selected from the group consisting of an α-olefin copolymer and a styrene-based thermoplastic elastomer. Thereby, appropriate flexibility can be obtained, and strength characteristics such as low-temperature impact resistance can be improved.

The amorphous ethylene-α-olefin copolymer includes propylene as an α-olefin component,
Butene-1, pentene-1, hexane-1, octene
There are 1,4-methylpentene-1, heptene-1 and the like.
In addition, as the styrene-based thermoplastic elastomer,
SEBS, SEPS, SEP, SEEPS, SBS, S
IS.

Further, the above-mentioned inorganic filler is made of glass fiber,
It is preferably at least one selected from the group consisting of talc, mica, calcium carbonate, wollastonite, clay, barium sulfate, potassium titanate whisker, magnesium sulfate whisker, calcium carbonate whisker, and silica. This can also improve strength characteristics such as low-temperature impact resistance.

[0015] As the colorant, both inorganic pigments and organic pigments can be used. The inorganic pigments include titanium white, zinc oxide, zinc sulfide, red iron, chrome yellow, barium yellow, ultramarine, cobalt blue, cobalt green,
There are brilliant materials such as carbon block, aluminum powder, aluminum flake, aluminum foil, pearl mica, zinc powder, and bronze powder.

Examples of the organic pigment include Watching Red, Permanent Red, Para Red, Toluidine Maroon, Benzidine Yellow, Phthalocyanine Blue, Phthalocyanine Green, Fast Sky Blue, Brilliant Carmine 6B and the like.

[0017]

The high gloss resin molded article of the present invention comprises a core layer and a skin layer covering the core layer. The core layer is made of a polypropylene-based composite material. Therefore, the strength of the product such as rigidity and flexibility can be adjusted by the polypropylene-based composite material of the core layer. Therefore, the most suitable skin layer can be selected for its appearance and scratch resistance without taking special strength characteristics into consideration.

The skin layer is made of a mixture of the specific polypropylene resin and a coloring agent. for that reason,
In the skin layer, a phenomenon of desorption of the pigment from the surface to the inside occurs, and the surface layer is transparent and does not contain the coloring agent.
A layer is formed as if it were a clear layer. Therefore,
In the high-gloss resin molded article of the present invention, a glossy feeling as deep as a painted product can be obtained. In particular, when the above-mentioned brilliant material is used as a pigment, the brilliant material is present inside,
Since a layer such as the above clear layer is formed on the surface,
The same metallic feeling as a metallic paint product can be obtained.

Further, since the skin layer is made of the above-mentioned specific polypropylene resin, its hardness is high and its surface is not easily scratched. Therefore, the high-gloss resin molded article of the present invention does not need to be separately coated in order to obtain the same high gloss, metallic feeling, and scratch resistance as the coated product.

As described above, according to the present invention, it is possible to obtain the same high glossiness, metallic feeling, and scratch resistance as a coated product, and to omit the coating process.
A high-gloss resin molded article can be provided.

[0021]

【Example】

Examples 1 to 7 A high-gloss resin molded product according to an example of the present invention will be described together with a comparative example. In this example, using a test piece,
The gloss, appearance, scratch resistance, and low-temperature impact resistance were evaluated. As the test piece, a flat plate formed into a size of 60 mm wide × 120 mm long × 3 mm thick using a sandwich type injection molding machine was used. A part of the comparative example was not a sandwich molded product having a two-layer structure including a core layer and a skin layer, but a single-layer molded product.

Table 1 shows the composition and properties of the materials used in this example. Examples 1 to 7 and Comparative Examples 1 to 5 shown in Table 5
Sample No. 9 was prepared from the materials with the formulation numbers shown in Table 1.
The materials of the core layer and the skin layer were selected and used (only one kind of single layer sample was selected). Then, a pigment described later was mixed in the skin layer.

As shown in Table 1, five kinds of crystalline polypropylene resins (hereinafter abbreviated as PP) were prepared. Also, as shown in Table 2, two types of rubber-modified PP groups prepared by adding amorphous ethylene / propylene rubber and talc to PP were prepared. In addition, PPG
Is a mixture of PP and glass fiber. In addition, PP (PP-6 to P-6) contained in rubber-modified PP and PPG
Table 3 shows the ethylene content and MFR (melt flow index) of P-8).

As the colorant, two kinds of pigments having the components and the compounding ratios shown in Table 4 were used. The pigment M has a dark blue metallic color, and the pigment S has a dark blue color. Next, Table 5 shows the materials of the skin layer and the core layer in Examples 1 to 7 and Comparative Examples 1 to 9 and test results described later. In Table 5, each material was designated as Sample No. These are shown in the order of (Table 1, Table 3) -Pigment symbol (Table 4).
For example, in the skin layer of Example 1, the sample of PP-1 is used and the pigment M is used, so that the skin layer is represented as PP-1-M.

The PP was measured for its Rockwell hardness and MFR (melt flow index) as characteristics, and the results are shown in Table 1. Rockwell hardness was measured on an R scale according to JIS-K7207. The MFR is based on JIS-K6758,
The test was performed at a temperature of 230 ° C. under a load of 2160 g.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

Hereinafter, each evaluation result will be described with reference to Table 5. First, the glossiness evaluation result will be described. Gloss is measured by a gloss meter according to JIS-Z8741.
The 0 ° specular gloss value was measured and evaluated. When the glossiness exceeds 70%, the same glossiness as that of a coated product can be sufficiently obtained.

As a result of the test, as shown in Table 5, Examples 1 to 3 in which PP 1 to 3 were used for the skin layer or the single layer were used.
7 and Comparative Examples 5 and 6 show that 7
High gloss of 0% or more was exhibited. Also, its glossiness is
The higher the crystallinity, that is, the higher the Rockwell hardness, the higher the value.

Next, the evaluation result of the appearance will be described. Appearance was evaluated by visually observing the molded test piece. The evaluation criterion is that the appearance quality of the test specimens is 1st class when the appearance quality is equivalent to the appearance quality
Classes were markedly inferior to class 3, and target levels were grades 1 and 2.

As a result, as shown in Table 5, similarly to the gloss test results, those using high crystalline PP 1 to 3 as a skin layer or a single layer show good appearance of second class or higher. Was. In particular, those using high crystalline PPs 1 and 2 exhibited excellent appearance almost equivalent to that of painted products.

Next, the results of the scratch resistance test will be described. The scratch resistance was measured using a surface tester manufactured by Shinto Chemical Co., Ltd. according to the test method described in JIS-K5401. Specifically, an iron pin having a diameter of 2 mm was set in the direction of 45 ° with respect to the test piece, the surface of the test piece was scratched at a constant speed of 150 mm / sec while applying a load of 100 g, and the scar was determined based on the following criteria. evaluated.

That is, in the test pieces, grade 1 was obtained when no scar was observed at all, grade 2 when scar was scarcely observed, grade 3 when the scar was slightly observed, and grade 4 when the scar was slightly observed. Classes 1 and 2 were set as target values.

As a result of the test, as shown in Table 5, the high crystal PPs 1 to 3 and those using PPG for the skin layer or the single layer showed good scratch resistance of the second grade or higher. In particular, those using the high crystalline PPs 1 and 2 showed no scars and showed excellent scratch resistance.

Next, regarding the results of the low-temperature impact resistance test,
explain. In the low-temperature impact resistance test, a test piece was left in an atmosphere of -30 ° C for 3 hours, and then a steel ball having a diameter of 50 mm and a weight of 1 kg was dropped, and the drop height at which the test piece was broken (cracked or cracked) was measured. It was measured and evaluated.

As a result of the test, as shown in Comparative Examples 1 to 7 of Table 5, the rubber-modified PP
And a high difference between high crystalline PP. That is, the rubber-modified PP exhibited excellent low-temperature impact resistance such that the steel ball was not broken even when dropped from a height of 150 cm or more. On the other hand, PP alone showed considerably lower impact resistance than rubber-modified PP. In addition, PPG exhibited intermediate performance between rubber-modified PP and PP alone.

In the test piece having a two-layer structure, Table 5
As shown in Examples 1 to 7 and Comparative Examples 8 and 9, the performance of the material used for the core layer (the performance of Comparative Examples 1 to 7) appeared as it was. That is, those using the rubber-modified PP for the core layer exhibited better low-temperature impact resistance than those using PPG.

Summarizing the above four evaluation results, the appearance quality expressed by gloss and appearance is good when using PP 1 to 3 as a skin layer or a single layer. On the other hand, those using the rubber-modified PP and PPG cannot obtain the same excellent appearance quality as the coated product. In addition, single-layer products using PP have good appearance quality,
Poor low-temperature impact resistance makes it unsuitable for use as exterior parts for automobiles.

As described above, according to the present invention, it is possible to obtain the same high glossiness, metallic feeling, and scratch resistance as the coated product, and it is possible to omit the coating process.

[0042]

[Table 5]

Example 8 As shown in FIG. 1, the high-gloss resin molded article of this example is a side molding material for automobiles comprising a core layer 2 and a skin layer 3 coated around the core layer 2. . The core layer 2 is made of a polypropylene-based composite material, while the skin layer 3 is made of a mixture of a polypropylene resin and a coloring agent.

As in the first embodiment, the polypropylene resin in the skin layer 3 does not contain ethylene.
A polypropylene resin having a Rockwell hardness of 113 was used. As the coloring agent, the pigment M used in Examples 1 to 5 (Table 4) was used. Further, the polypropylene-based composite material in the core layer 2 was formed in the same manner as in Example 1.
A highly crystalline polypropylene resin contains 60% by weight of amorphous ethylene / propylene rubber and 10% by weight of talc.

The side molding 10 of this example was formed by using a sandwich type injection molding machine using the above-mentioned materials. In the side molding 10 of this example, as in the case of Example 1, the same high glossiness, metallic feeling, and scratch resistance as those of the coated product were obtained. Further, as in the case of the first embodiment, since the low-temperature impact resistance is also excellent, the function as a side molding can be sufficiently exhibited.

The present invention provides, in addition to the above-mentioned side molding, exterior products such as wheel covers, side garnishes, rocker panels, bumpers, bumper corners, spoilers, and center pillars; interior products such as meter clusters, center clusters, and garnishes; It can be applied to various transport equipment and electrical equipment and other industrial equipment that require high gloss. Further, the above-mentioned molded body can be manufactured by two-layer extrusion molding, two-layer blow molding, or the like, in addition to the sandwich injection molding method.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a side molding according to an eighth embodiment.

[Explanation of symbols]

 10. . . Side mall, 2. . . 2. core layer; . . Skin layer,

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-16740 (JP, A) JP-A-4-35943 (JP, A) JP-A-4-368844 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 B60R 13/02-13/04 B29C 45/16

Claims (4)

(57) [Claims] 1. A resin molded article comprising a core layer and a skin layer coated around the core layer, wherein the core layer is made of a polypropylene-based composite material, while the skin layer is colored with a polypropylene resin. And a polypropylene resin in the skin layer,
Not containing or it contains% by weight of ethylene, and Ri polypropylene resin der the Rockwell hardness to have a crystallinity becomes 85 or more, the surface of the skin layer
A high-gloss resin molded product comprising a transparent layer formed on a layer . 2. A high-gloss resin molded article according to claim 1, wherein the polypropylene-based composite material in the core layer contains one or both of a rubber component and an inorganic filler in a polypropylene resin. . 3. A high-gloss resin molding according to claim 2, wherein said rubber component is at least one selected from the group consisting of an amorphous ethylene-α-olefin copolymer and a styrene-based thermoplastic elastomer. body. 4. The inorganic filler according to claim 2, wherein the inorganic filler is glass fiber, talc, mica, calcium carbonate, wollastonite, clay, barium sulfate, potassium titanate whisker, magnesium sulfate whisker, calcium carbonate whisker, A high-gloss resin molded product, which is at least one member selected from the group consisting of silica.