JP2914894B2 - Automotive side molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile side molding.

[0002]

2. Description of the Related Art As shown in FIG. 4, a side surface 41 of an automobile body 40 is formed on a side surface of the vehicle body 40 for the purpose of protecting the side surface from damage due to contact with other objects, and at the same time, enhancing the decorativeness of the side surface of the body. A band-shaped side molding 50 made of a resin molded product is often attached. FIG. 5 is a sectional view of an example of the side molding 50.

As a method of improving the decorativeness, coloring is applied to the side molding 50. As the coloring method, there is a method of performing painting after molding of the side molding, and a so-called “material attachment method” in which a pigment is added to the molding material of the side molding, but an extra painting step is required in the case of painting. Therefore, material deposition is advantageous in terms of workability and cost. However, in the case of this material attachment, a molding material for the side molding that has a high degree of freedom in coloring and that is excellent in the sharpness of the colored color is required. To satisfy them, a material having excellent transparency and gloss is required. In particular, the transparency of the molding material is important for a metallic color characterized by metallic shine.

Conventionally, PVC has been used as a material for side moldings.
(Vinyl chloride resin) is frequently used. Since the impact resistance of PVC alone is insufficient, the flexibility is increased by adding a plasticizer to improve the impact resistance.

However, the side molding made of PVC has a large specific gravity of about 1.29 to 1.41 as well as being flexible to improve impact resistance, so that it can be attached to a body. To solve the difficulties,
Since it is formed thick to provide rigidity, it has a considerable weight. In addition, there is a problem that the cost increases due to an increase in the amount of PVC used. For this reason, PVC side moldings are not suitable for the recent reduction in weight and cost of automobiles, and more economical side moldings made of lighter materials have been required.

Recently, as a material for a side molding for an automobile, it has a moderate buffering property and a specific gravity which is lighter than that of PVC.
Moreover, polypropylene that can increase rigidity has been used. However, polypropylene is composed of a crystalline polymer and has a lower transparency than PVC, so that a large amount of pigment is required for coloring by material deposition, which causes a problem of increased cost. Especially for metallic colors,
The proportion of the metallic pigment (metal powder) must be increased in order to produce a metallic shine, which greatly increases the cost. Further, polypropylene generally has a problem in scratch resistance. From these points, most of the conventional polypropylene side moldings are colored by painting, and the coating film improves the scratch resistance.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has excellent lightness and scratch resistance.
Moreover, it is an object of the present invention to provide an automobile side molding which is economically excellent.

[0008]

That is, the present invention provides:
An automobile side molding comprising a core layer and a skin layer covering the surface thereof, wherein the core layer is made of a polypropylene-based resin, while the skin layer is made of a resin component and a pigment, and But melt flow rate 1
A propylene homopolymer having a melt flow rate of more than 0 g / 10 min and a crystallinity of more than 60% and an ethylene-propylene random copolymer having a melt flow rate of more than 10 g / 10 min and a crystallinity of more than 60%, or 60 -90% by weight of a polypropylene component and a melt flow rate of 2 g
Ethylene-α-olefin rubber having an ethylene content of 60 mol% or less and a melt flow rate of 2 g / 1
At least one rubber 40-1 selected from the group consisting of a propylene-α olefin rubber having a melt flow rate of more than 0 minutes and a styrene rubber having a melt flow rate of more than 2 g / 10 minutes;
0% by weight, the physical properties at the time of curing are greater than Rockwell hardness (R scale) of 70, and the haze value is 20%
It is characterized by being smaller.

In the present invention, the melt flow rate (also called melt flow index, abbreviated as MI) refers to a value measured according to JIS K7210. Rockwell hardness (R scale) is A
The value measured according to STM D785, the haze (HA
(ZE value) refers to a value measured according to ASTM D1003 (t = 0.4 mm).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of the automobile side molding of the present invention, FIG. 2 is a cross-sectional view showing another example of the automobile side molding of the present invention, and FIG. 3 is still another example of the automobile side molding of the present invention. FIG.

As shown in FIG. 1, a side molding 10 for an automobile according to the present invention comprises a core layer 11 and a skin layer 15 covering the surface thereof.
Are integrally formed by known sandwich molding, and a bottom surface portion 10A is a surface to be attached to the body.

The core layer 11 is mainly for providing the side molding 10 with rigidity required for good attachment and moderate shock absorption, and is made of a lightweight polypropylene resin. This polypropylene resin is not particularly limited. For example, a resin obtained by adding talc, calcium carbonate, or the like to a resin obtained by adding ethylene-propylene rubber (EPR), styrene-based rubber, polyethylene, or the like to polypropylene as needed is used. Examples of the polypropylene include propylene homopolymer (also referred to as homopolypropylene and abbreviated as H-PP), ethylene-propylene block copolymer (B-PP), and ethylene-propylene random copolymer (R-PP). PP) or a mixture thereof is used.

The physical properties of the core layer 11 are appropriately determined.
As a preferred example, the flexural modulus is 4000 to 12000.
kg / cm ² (ASTM D790), linear expansion coefficient is 7
Less than × 10 ⁻⁵ cm / cm / ° C. (ASTM D69
6) and those having an Izod impact strength of more than 5 kg · cm / cm (−30 ° C., ASTM D256).

The cross-sectional shape of the core layer 11 is appropriately determined. Although the core layer 11 of this example is formed in a substantially trapezoidal cross section, it can be further reduced in weight by forming a curved shape having a concave portion 22 inside like the core layer 21 of the side molding 20 shown in FIG. . In the side molding 20, the core layer 21 and the skin layer 25 are integrally formed by co-extrusion of two layers.

The core layer 11 has a two-layer structure like the core layer 31 of the side molding 30 shown in FIG. 3, and the side close to the skin layer 35 is made of a first core made of a polypropylene-based resin having an improved cushioning property. The layer 32 and the side to be attached to the automobile body may be a second core layer 33 made of a polypropylene-based resin having improved hardness and adhesiveness to an adhesive tape to improve the attachment of the side molding to the automobile body.

On the other hand, the skin layer 15 is made of a material having excellent scratch resistance and transparency, is colored in a desired color, and covers the surface of the core layer 11. This skin layer 15
It consists of a mixture of a resin component containing 0 to 90% by weight of a polypropylene component and 40 to 10% by weight of a rubber component and an appropriate amount of a pigment.

The polypropylene component is crystallized melt flow rate large propylene homopolymer than 60% crystallinity at greater than 10 g / 10 min (H-PP) and a melt flow rate at greater than 10 g / 10 min degree is 60% greater ethylene - propylene random copolymer (R-PP) or
Or one of them , and has high scratch resistance (hardness) and transparency. B-PP is not preferable because it is opaque. The reason why the melt flow rate of the polypropylene component is larger than 10 g / 10 minutes is to obtain good smoothness. The reason why the crystallinity is greater than 60% is to make the surface hardness of the side molding appropriate. Since the skin layer 15 has this polypropylene component, the core layer 11 made of the polypropylene resin is used.
And the adhesiveness with the adhesive.

On the other hand, the rubber component gives the polypropylene component a certain degree of flexibility, and the skin layer 15
Is added to prevent the occurrence of cracks.
The rubber component is an ethylene-α olefin rubber having a melt flow rate of more than 2 g / 10 min and an ethylene content of less than 60 mol%, a propylene-α olefin rubber having a melt flow rate of more than 2 g / 10 min and a melt flow And at least one rubber selected from the group consisting of styrene rubbers having a weight of more than 2 g / 10 minutes.

In this rubber component, the melt flow rate is set to be larger than 2 g / 10 minutes in order to disperse the rubber component well in the polypropylene component. If the rubber component has a melt flow rate of 2 g / 10 minutes or less, the rubber component does not have a uniform composition with the polypropylene component, and becomes turbid, and a good skin layer cannot be obtained. When the rubber component is an ethylene-α-olefin rubber, if the ethylene content is more than 60 mol%, the compatibility between the rubber component and the polypropylene component becomes poor, and the skin layer becomes opaque. The lower limit of the ethylene content is preferably set to 30 mol%.

It is to be noted that if the rubber component is added too much, it causes a reduction in scratch resistance and transparency of the entire skin layer 15. In addition, when the relationship between scratch resistance and transparency and physical property values was examined in various ways, the scratch resistance was easily damaged when the Rockwell hardness (R scale) was 70 or less, and the cloudiness (transparency) was determined for transparency. (Haze value) of 20% or more was found to lack transparency. For this reason, the mixing amount of the rubber component in the resin component is set to 40 to 10% by weight, and the Rockwell hardness (R
Scale) is greater than 70 and haze value (HAZE value) is 20%
It was made smaller.

The α-olefin in the ethylene-α-olefin rubber and the propylene-α-olefin rubber is
An aliphatic hydrocarbon compound having one C ＝ C unsaturated bond, and includes, for example, propylene, 1-butene, 1-pentene, 1-octene and the like, and propylene is preferred in ethylene-α-olefin rubber. On the other hand, in propylene-α-olefin rubber, it is other than propylene. Further, as the styrene rubber, a hydrogenated product of a styrene copolymer rubber is preferable, and among them, a styrene-ethylene-butylene-styrene copolymer (S
EBS), styrene-ethylene-propylene copolymer (SEP), and styrene-ethylene-propylene-styrene copolymer (SEPS) are preferred.

Further, additives such as a crystal nucleating agent, a light stabilizer, an antioxidant, and a lubricant can be appropriately added to the resin component of the skin layer 15. In particular, the nucleating agent is effective for improving the hardness and transparency of the polypropylene component.
Examples of the crystal nucleating agent include a metal salt of an aromatic monocarboxylic acid such as benzoic acid, and a metal salt of an aromatic phosphate compound such as sodium bis (4-tert-butylphenyl) phosphate. In order to improve the transparency of the resin component, the thickness of the skin layer 15 is preferably less than 0.5 mm.

Various pigments are used. In the case of a metallic pigment, a powder or a piece of metal such as aluminum or mica is used. The amount of the pigment to the resin component varies depending on the type of the pigment,
It is usually less than 2% by weight based on 100% by weight of the resin component. In the skin layer 15, the degree of freedom of color is increased due to the transparency of the resin component. In addition, the pigment is not necessarily blended in the skin layer 15 and the pigment is not necessarily blended in the core layer 11, so that the amount of the pigment used can be reduced.

[0024]

EXAMPLES A core layer (thickness 2 mm) composed of 60% by weight of B-PP, 30% by weight of ethylene-propylene rubber (EPR), and 10% of talc, and a skin layer (thickness 0.5 mm) having the composition shown in Table 1 were prepared. 2 is formed by coextrusion as shown in FIG. 2, and the Rockwell hardness and haze value (HAZE value) of the skin layer are measured, and the scratch resistance, impact resistance, and appearance test are performed. Was performed by the following method. In this case, if the skin layer was colored with a pigment, the haze value could not be measured accurately. Therefore, a skin layer containing no pigment was formed. Table 1 shows the Rockwell hardness and haze, and Table 2 shows the results of the appearance test.

[0025]

[Table 1]

[0026]

[Table 2]

In Table 1, H-PP has a melt flow rate of 22 g / 10 min and a crystallinity of 70%, and R-PP has a melt flow rate of 12 g / 10 min.
The degree of crystallinity is 70%. The propylene-1-butene copolymer rubber has a melt flow rate of 5 g / 10 minutes,
Hydrogenated styrene-butene rubber has a melt flow rate of 3.
5 g / 10 min, the ethylene-propylene copolymer rubber has an ethylene content of 40 mol% and a melt flow rate of 4.
Consists of 5 g / 10 minutes.

[Method of measuring Rockwell hardness] ASTM
Measured on R scale according to D785. [Haze value test method] ASTM D1003
Measured at t = 0.4 mm according to. [Scratch resistance test method] A pencil hardness test method with a load of 50
The damage level in g and B is evaluated. In the evaluation, ○ indicates “the extent to which no flaws or thin and thin lines remain”, and X indicates “the extent to which a clear mark remains”. [Impact resistance test method] An iron ball of 500 g was dropped from a height of 20 cm on a side molding left at -30 ° C for 3 hours, and cracks and the like were evaluated. In the evaluation, ○ indicates “no crack” and “x” indicates “crack in skin layer”. [Appearance test method] Transparency, gloss, unevenness, warpage and the like were visually evaluated. In the evaluation, ○ indicates “good” and X indicates “poor”.

As is clear from Tables 1 and 2, the side moldings of Examples 1 to 6 were good in all of the scratch resistance, appearance and impact resistance, whereas those of Comparative Examples 1 and 2 were good. Those were inferior in either impact resistance or scratch resistance.

Next, the visibility of the side molding of the present invention, in which the skin layer was colored in a metallic color by material deposition, and the conventional side molding having a single-layer structure, were visually evaluated. The side molding used was the same as that of the above-mentioned Example 1, and 0.5% by weight of a spherical aluminum powder (trade name: Metax, manufactured by Toyo Aluminum Co., Ltd.) was added to the skin layer as a metallic pigment, and colored in a green metallic tone. Example 7 and Example 8 in which the same pigment was blended at 0.35% by weight were used. As a conventional example, B
FIG. 5 formed from 60% by weight of PP, 30% by weight of EPR, 10% by weight of talc, and 0.5% by weight of aluminum powder.
Was also examined for sharpness. The results are shown in Table 3. In Table 3,
◎ indicates “very good”, Δ indicates “good”, and X indicates “poor”.

[0031]

[Table 3]

As shown in Table 3, in Examples 7 and 8, good sharpness was obtained. In contrast, the conventional example has a dull metallic color and lacks sharpness. Moreover, while the conventional example contains 0.5% by weight of the pigment with respect to 100% by weight of the total resin component, Examples 7 and 8 show 0% by weight with respect to 100% by weight of the resin component of the skin layer. It is understood that the pigment is 0.5 or 0.35% by weight, and that the examples can provide good sharpness even though the total amount of the pigment is smaller than that of the conventional example.

[0033]

As described above, according to the automobile side molding of the present invention, the core layer is made of a polypropylene resin, so that it is light in weight. Further, since the skin layer covering the surface of the core layer is covered with a skin layer made of a resin component having a Rockwell hardness (R scale) of greater than 70 and a haze value of less than 20%, scratch resistance and transparency are improved. Is excellent.

Further, according to the side molding for automobiles of the present invention, a pigment is added to the transparent skin layer. In particular, when a metallic pigment is used, excellent sharpness can be obtained, and coating is performed. No need. Therefore, there is an effect that not only the economic efficiency is improved but also the workability at the time of manufacturing is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an automobile side molding according to the present invention.

FIG. 2 is a cross-sectional view showing another example of the automobile side molding according to the present invention.

FIG. 3 is a cross-sectional view showing still another example of the automobile side molding according to the present invention.

FIG. 4 is a perspective view showing an attached state of a general automobile side molding.

FIG. 5 is a sectional view showing an example of a conventional automobile side molding.

[Explanation of symbols]

 10 Side molding for automobile 11 Core layer 15 Skin layer

Continuation of front page (56) References JP-A-6-328508 (JP, A) JP-A-5-185880 (JP, A) JP-A-4-366635 (JP, A) JP-A-4-372435 (JP) JP-A-4-307236 (JP, A) JP-A-4-244441 (JP, A) JP-A-6-316241 (JP, A) JP-A-60-177049 (JP, A) 2-45552 (JP, A) JP-A-2-67129 (JP, A) JP-A-63-142032 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60R 13/04 B29D 31/00

Claims (1)

(57) [Claims] An automobile side molding comprising a core layer and a skin layer covering the surface thereof, wherein the core layer is made of a polypropylene resin, and the skin layer is made of a resin component and a pigment, The resin component has a melt flow rate of greater than 10 g / 10 minutes,
Large propylene homopolymer than crystallinity of 60% and from main <br/> belt flow rate 10 g / 10 min large, crystallinity of 60
Large ethylene than% - propylene random copolymer also
Is a polypropylene component consisting of 60 to 90% by weight of one of them, an ethylene-α-olefin rubber having a melt flow rate of more than 2 g / 10 min and an ethylene content of 60 mol% or less, and a propylene having a melt flow rate of more than 2 g / 10 min. A rubber component comprising 40 to 10% by weight of at least one rubber selected from the group consisting of α-olefin rubber and styrene rubber having a melt flow rate of more than 2 g / 10 minutes, and the physical properties at the time of curing are Rockwell Hardness (R scale)
An automobile side molding having a haze value of greater than 70 and a haze value of less than 20%.