JP2536331B2 - Sandwich long molded product - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sandwich long molded product such as a side molding for an automobile, which is excellent in mounting appearance quality, dimensional stability and the like, and particularly to a constituent material thereof.

[0002]

2. Description of the Related Art Side moldings used for exteriors of automobiles, ships, etc. are excellent in terms of quality of installation and dimensional stability during use.
Excellent scratch resistance and product assembling are required. The above-mentioned excellent appearance quality means that the side moldings can be adhered to each other on a car door or the like without any gap, or that the adhered side moldings have a predetermined gap. In addition, the term “excellent in dimensional stability” means that the side molding does not significantly expand or contract due to temperature changes during use, such as winter and summer, daytime and nighttime.

The term "excellent in scratch resistance" means that the surface of the side molding is not easily scratched when it is mounted or used. Furthermore, good product assembling means that a side molding can be easily assembled to an automobile in an automobile assembly line, for example. For example, when the side molding is warped, the side molding must be forcibly pressed and adhered according to the surface shape of the mating material, resulting in poor product assembling. Also, if the side moldings are too soft or too hard, it is difficult to attach them, resulting in poor product assembly. By the way, conventionally, as long molded products such as side moldings,
For example, polypropylene resin or the like is used (JP-A-63-95252, JP-A-61-233048).

[0004]

[Problems to be Solved] However, there is no long molded product that satisfies the above four requirements. In particular, in recent years, the demands for mounting appearance quality and dimensional stability have increased. Therefore, as a countermeasure, it is possible to reduce the linear expansion coefficient of the material. And as a means for that,
Conventionally, it has been proposed to blend a fibrous filler such as glass fiber into a material such as polypropylene resin (JP-A-61-34047, Japanese Patent Publication No. 1-2229).
No. 9).

However, when the fibrous filler is blended as described above, the appearance of defects such as warp and twist occurs in the long molded product. As a result, the above-mentioned appearance quality and product assemblability deteriorate. On the other hand, it is possible to use a thermoplastic elastomer having excellent impact resilience as a material satisfying scratch resistance. However, since the thermoplastic elastomer has a large linear expansion coefficient, the above-mentioned quality of attachment and quality and dimensional stability are not satisfied. In addition, since the whole long molded product becomes too flexible, the assembling property of the product deteriorates. In view of such conventional problems, the present invention intends to obtain a sandwich long molded product which is particularly excellent in appearance quality and dimensional stability in installation, scratch resistance, and product assembling property.

[0006]

The present invention is a sandwich-shaped long molded article comprising a skin layer and a core layer covered with the skin layer, wherein the skin layer is made of a thermoplastic elastomer. The core layer contains 30 to 70% by weight of polypropylene resin as a matrix phase and ethylene-
70% to 30% by weight of a dispersed phase composed of an α-olefin copolymer or a styrene-based thermoplastic elastomer, and the ratio of the flexural modulus of the core layer to the skin layer is 3.0 or more. There is a sandwich long molded product.

The long molded article of the present invention has a sandwich structure composed of a core layer formed inside and a skin layer covering the surface of the core layer. In the present invention, the skin layer is formed of a thermoplastic elastomer. The thermoplastic elastomer is a polymer material composed of a flexible component (soft segment) having rubber elasticity in the molecule and a molecular constraining component (hard segment) for preventing plastic deformation.

Examples of the thermoplastic elastomer applicable to the skin layer of the present invention include the following. (1) A styrene-based thermoplastic elastomer in which the hard segment is polystyrene and the soft segment is composed of polybutadiene, polyisoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, and the like. Also,
This may be supplemented with polypropylene resin, oil or the like. (2) An olefin-based thermoplastic elastomer in which the hard segment is polypropyne or polyethylene, while the soft segment is ethylene-propylene rubber (EPR) or ethylene-propylene-diene terpolymer (EPDM). In addition, the above EPR, EPDM
May be partially or completely crosslinked.

(3) A urethane-based thermoplastic elastomer in which the hard segment is polyurethane and the soft segment is polyester or polyether. (4) A polyester thermoplastic elastomer in which the hard segment is polyester and the soft segment is polyether or polyester. (5) A thermoplastic polyamide elastomer in which the hard segment is polyamide and the soft segment is polyether or polyester. (6) A thermoplastic vinyl chloride elastomer in which the hard segment is crystalline PVC (polyvinyl chloride), while the soft segment is amorphous PVC. (7) Other thermoplastic elastomers include chlorinated polyethylene, ionomers and syndiotactic 1.2 polybutadiene.

Next, the coefficient of linear expansion of the thermoplastic elastomer is generally in the range of 10 to 20 × 10 ^-5 cm / cm · ° C. On the other hand, the core layer is made of polypropylene resin as a matrix phase and ethylene-α-olefin copolymer or styrene-based thermoplastic elastomer as a dispersed phase. That is, the core layer has a sea-island structure in which the dispersed phase is dispersed like islands in the matrix phase of polypropylene resin. And, due to this sea-island structure, an excellent low linear expansion coefficient can be obtained.

Further, when the aspect ratio of the dispersed phase is in the form of a string having an aspect ratio of 5 or more, the linear expansion coefficient is further reduced, and good results can be obtained with respect to dimensional stability. Here, the aspect ratio means a dimensional ratio of length to diameter in the dispersed phase. As described above, the core layer is composed of the matrix phase of 30 to 70% by weight and the dispersed phase of 70 to 30% by weight. When the dispersed phase is less than 30% by weight or more than 70% by weight, the linear expansion coefficient of the core layer becomes high.

As the polypropylene resin, in addition to homopolypropylene, propylene-ethylene random copolymer, propylene-ethylene block copolymer and mixtures thereof are used. The amount of ethylene in these copolymers or the mixture is preferably 0 to 15%. If it exceeds 15%, the rigidity may decrease.

The polypropylene resin may be replaced with a polyolefin resin in which a part of the polypropylene resin is modified with a functional group such as carboxylic acid, carboxylic acid anhydride or hydroxyl group, depending on the kind of the thermoplastic elastomer of the skin layer. good. This can improve the adhesiveness between the core layer and the skin layer. It is particularly effective when the skin layer is a polar polymer such as polyester elastomer, polyamide elastomer, polyurethane elastomer.

Next, the ethylene-α-olefin copolymer means ethylene, propylene, butene-1, and hexene-
It is a copolymerization component with an α-olefin such as 1, decene-1,4-methylbutene-1,4-methylpentene-1. Further, among the above ethylene-α-olefin copolymers, when propylene is used as the α-olefin, that is, in the case of ethylene-propylene rubber (EPR), a particularly low linear expansion coefficient is exhibited.

The ethylene-α olefin copolymer preferably has a Mooney viscosity ML _{1 + 4} (100 ° C.) of less than 70. This is because the linear expansion coefficient of the molded product becomes high when it is 70 or more. The Mooney viscosity ML _{1 + 4} (100 ° C.) is preferably less than 65, more preferably less than 60.

Examples of the styrene thermoplastic elastomer include styrene / ethylene / butylene / styrene block copolymer (SEBS), styrene / butadiene / styrene block copolymer (SBS), styrene / isoprene / styrene block. Copolymer (SIS),
Examples include styrene / ethylene / propylene copolymer (SEP). In these, polystyrene constitutes the hard segment, while polybutadiene, polyisoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, etc. constitute the soft segment.

The flexural modulus of the core layer is 2000 kg / cm ^{2 to} 10000 kg /
It is preferably cm ² . More preferably, 300
It is 0 to 8000 kg / cm ² . Such a flexural modulus can also be achieved by, for example, adjusting the type and the amount of the filler to be described later. Next, in the core layer, in order to reduce the linear expansion coefficient and adjust the hardness and rigidity of the core layer and the entire long molded product, 100% by weight of the core layer is used.
It is desirable to add the filler in an amount of 1 to 40% by weight based on (the total amount of the matrix phase and the dispersed phase). If it exceeds 40% by weight, the hardness and rigidity become too high, which is not preferable.

Examples of such fillers include non-fibrous fillers such as calcium carbonate, talc, clay, mica, silica and barium sulfate. The diameter of the fiber is 3 μm
There are the following fibrous fillers. As the fibrous filler, a fibrous filler such as potassium titanate whisker, magnesium oxysulfate whisker, zinc oxide whisker, wollastonite, glass fiber or carbon fiber is used. The fibrous filler acts on the dispersed phase and greatly contributes to the reduction of the linear expansion coefficient. Among the above,
Whiskers having a fiber diameter of 1 μm or less, such as potassium titanate whiskers, are preferable in terms of material physical properties and dimensional stability.

Further, the core layer having the above composition is 10 ×
It has a linear expansion coefficient of 10 ^-5 cm / cm · ° C or less, and it can be lowered to around 3 × 10 ^-5 cm / cm · ° C by adjusting the aspect ratio of the dispersed phase and the type and amount of filler. You can Next, the ratio of the flexural modulus of the core layer to the skin layer needs to be 3.0 or more. When it is less than 3.0, the low linear expansion characteristic of the core material is not effectively exhibited,
It does not achieve the object of the present invention.

The coefficient of linear expansion of the core layer and the skin layer is larger in the skin layer than in the core layer. However, as described above, by setting the ratio of the bending elastic modulus of the core layer to the skin layer to be 3.0 or more, the characteristics of the core layer having a low linear expansion are predominantly exhibited. Therefore, the coefficient of linear expansion of the entire long molded product decreases due to the synergistic effect of the skin layer and the core layer (see the section on action and effect).

That is, the coefficient of linear expansion is smaller than the value of the coefficient of linear expansion calculated from the additive effect (addition rule) obtained from the coefficients of linear expansion of only the skin layer and only the core layer.
Therefore, the quality of mounting and the dimensional stability of the entire long molded product are improved. Further, in the sandwich structure of a long molded product, the filling rate of the core layer is preferably 10 to 90%. If it is less than 10%, the core layer is small and the whole long molded product becomes too flexible, and the linear expansion coefficient of the whole may be large. On the other hand, if it exceeds 90%, the core layer may become thick and flexibility may be reduced. The filling rate of the core layer means the weight% of the core layer in the cross-sectional area in the cross section in the direction orthogonal to the longitudinal direction of the long molded product.

Further, in the present invention, in addition to the above-mentioned components, an antioxidant, an ultraviolet absorber, a lubricant, an antistatic agent, a nucleating agent, a pigment, a flame retardant, an extender, a processing aid, etc. You may mix an additive. Further, the above-mentioned respective components are mixed and kneaded by using a kneading machine such as a single-screw extruder, a twin-screw extruder, a kneader, a Brabender, a Banbury mixer or the like. After the melt-kneading, pelletization is usually performed. Further, such a composition is formed into a desired sandwich-shaped long molded product by sandwich injection molding, two-layer extrusion molding or the like. Here, examples of long molded articles to which the present invention can be applied include exterior parts and interior parts for automobiles. The above-mentioned exterior parts include various malls, bumpers, spoilers, rocker panels and the like. Further, the interior parts include pillars and garnishes.

[0023]

[Operation and effect] The sandwich long molded article of the present invention is
The linear expansion coefficient is as low as 2 to 8 × 10 ⁻⁵ cm / cm · ° C. Therefore, even during use, the expansion and contraction due to temperature changes is small, and dimensional stability is excellent. In addition, because of its excellent dimensional stability, the gap between adjacent side moldings can be kept small even when the side moldings are attached to automobile doors, etc., resulting in excellent mounting quality. .

The surface of the long molded product is covered with a skin layer made of a flexible thermoplastic elastomer. Therefore, it has excellent scratch resistance. Furthermore,
As mentioned above, the surface is composed of a skin layer having a relatively large flexibility, and the inside is composed of a core layer having a high bending elastic modulus and a high mechanical strength. Therefore, the long molded product as a whole has appropriate flexibility and hardness and does not warp. Therefore, it can be easily mounted according to the surface shape of the mating material, and it is excellent in product assembly.

Further, as described above, the reason why the long molded product as a whole exhibits a low linear expansion coefficient is not clear, but the linear expansion coefficient of each of the skin layer and the core layer and the ratio of the bending elastic moduli of the two are determined. There is a factor. That is, as is known from the examples described later, the skin layer made of a thermoplastic elastomer has a coefficient of linear expansion of generally 10 to 20 × 10 ⁻⁵ cm.
/ Cm · ° C. On the other hand, in the core layer having the above composition, the dispersed phase of the ethylene-α-olefin copolymer or the styrene-based thermoplastic elastomer is dispersed like islands in the matrix phase of polypropylene resin. And, these dispersed phases greatly contribute to the reduction of the linear expansion coefficient of the matrix phase. Therefore, the core layer is 10 × 10 ^-5 cm / cm
・ Has a low coefficient of linear expansion of less than ° C.

Further, the overall linear expansion coefficient of a sandwich molded product is usually an additive law value based on the linear expansion coefficients of both the skin layer and the core layer. Additive rule value (CT)
Is the value calculated by the following formula. CT = a × CS + b
× CC In the above formula, a is the filling rate (% by weight) of the skin layer, CS is the coefficient of linear expansion of the skin layer, b is the filling rate of the core layer (% by weight), and CC is the coefficient of linear expansion of the core layer. In addition, the filling rate of the skin layer or core layer means the weight ratio (%) of the skin layer or core layer in the cross-sectional area of the cross section of the long molded product which is orthogonal to the longitudinal direction.

However, the sandwich long molded product of the present invention exhibits a low linear expansion coefficient of 40 to 60% of the linear expansion coefficient calculated by the above additive rule value.
The low linear expansion coefficient is obtained when the bending elastic modulus ratio of the core layer to the skin layer is 3.0 or more. As described above, the long molded product of the present invention can achieve a low linear expansion coefficient depending on the materials of the skin layer and the core layer and the bending elastic modulus ratio. As described above, according to the present invention, it is possible to obtain a sandwich long molded product which is excellent in appearance quality and dimensional stability, and is also excellent in scratch resistance and product assembling property.

[0028]

EXAMPLES Examples 1 to 8 Examples of the present invention will be described below together with comparative examples. Sandwich molding of automobile side moldings was carried out as a sandwich long molded product, and its linear expansion coefficient and scratch resistance were tested. That is, FIG.
As shown in FIG. 2, the side molding 1 includes a skin layer 12 and a core layer 1 covered by the skin layer 12.
It is a sandwich long molded product consisting of 1. The side molding 1 has a length Q of 110 cm and a height R of 5 m.
m, the bottom width P is 3 cm, and the upper part has an arc shape.
The width G of the film gate 15 at the time of molding the side molding 1 is about 4.5 cm.

The sandwich side molding 1 was molded by the sandwich injection molding method. That is, the skin layer material in the softened state is first injected into the mold cavity,
Then, the core layer material in a softened state was injected into the skin layer material, and the whole was cooled to be molded. Tables 2 and 3 show the properties of the skin layer material, the core layer material, and the molded molding used in the above molding. In both tables, the material names (skins A to F, cores L to P) in the column of skin layer and core layer materials indicate the materials described below used in each example or comparative example. The table also shows the flexural modulus, linear expansion coefficient of both materials and the flexural modulus ratio of the core layer material to the skin layer material.

Further, in the same table, the packing ratio of the core layer in the obtained side molding, the linear expansion coefficient W by the additive rule calculation, the actually measured linear expansion coefficient Y for each side molding, and the difference (W- Y), scratch resistance of side moldings, warpage, and product assembly are shown. Regarding scratch resistance, warpage, and product assemblability, good is indicated by a circle, bad is indicated by a cross, and the middle is indicated by a triangle.

Next, the above-mentioned skin layer materials (skin A to
F) is as follows. (1) Skin A; olefin-based thermoplastic elastomer Mirastomer 9590B (manufactured by Mitsui Petrochemical Co., Ltd.) (2) Skin B; olefin-based thermoplastic elastomer Mirastomer 9070B [manufactured by Mitsui Petrochemical Co., Ltd.] (3) Skin C; Polyester thermoplastic elastomer PELPRENE S-6001 [Toyobo Co., Ltd.]

(4) Skin D: Polyester thermoplastic elastomer Perprene S-1001 (Toyobo Co., Ltd.) (5) Skin E: Styrene thermoplastic elastomer Lavalon SJ9400B (manufactured by Mitsubishi Petrochemical Co., Ltd.) (6) Skin F: Urethane-based thermoplastic elastomer Pandex T-1190 (manufactured by Dainippon Ink and Chemicals, Inc.)

Next, the above core layer materials (cores K to P)
Are shown in Table 1. The table shows matrix phase, dispersed phase,
The ratio of each component of the filler and the aspect ratio of the dispersed phase are shown. The ratio of each component is shown in parts by weight. for that reason,
The total value of the matrix phase and the dispersed phase is 100 parts by weight.

[0034]

[Table 1]

In Table 1, the polypropylene resin used for the matrix phase is shown below. (1) Block PP (polypropylene resin); BC-
03F [manufactured by Mitsubishi Petrochemical Co., Ltd.] (2) Block PP; BC-05C [manufactured by Nippon Synthetic Rubber Co., Ltd.] Further, modified polyolefin resins are shown below. (1) Maleic anhydride modified PP; QE-050 [manufactured by Mitsui Petrochemical Co., Ltd.] (2) Polyolefin polyol; Polytail H
[Made by Mitsubishi Kasei Co., Ltd.]

The components of the dispersed phase are shown below. (1) Ethylene-α-olefin copolymer; EP911
P [manufactured by Japan Synthetic Rubber Co., Ltd.] (2) SEBS (as styrene-based thermoplastic elastomer component); Kraton G1657 [Shell Chemical Co., Ltd.]
Manufacturing] The filler components are shown below. (1) Potassium titanate whiskers; Tismo D [manufactured by Otsuka Chemical Co., Ltd.] (2) Talc: LMR # 100 [Fuji Talc Co., Ltd.]
(3) Glass fiber; CS03MA486A [Made by Asahi Fiber Glass Co., Ltd.]

[0037]

[Table 2]

[0038]

[Table 3]

As is known from Tables 2 and 3, in Examples 1 to 8 according to the present invention, the measured linear expansion coefficient of the side molding is as low as 3.2 to 6.9 × 10 ⁻⁵ cm / cm · ° C. Indicates the value. On the other hand, in Comparative Examples C1 to C4, the flexural modulus ratio of the core layer to the skin layer was 1.6 or 1.1.
6.8 to 10.1 × 10 ^-5 cm / cm ・ ° C.
And shows a high linear expansion coefficient. In addition, Comparative Example C5
The bending elastic modulus ratio is 5, but the core layer material does not contain a dispersed phase (core O in Table 1). Therefore, the coefficient of linear expansion is low, but warpage and product assembly are poor (marked with x in the table).

Comparative Example C6 is a side molding which does not use a skin layer but has only a core layer. This side molding is not good in scratch resistance and product assembly. In addition, in both tables above,
Regarding the coefficient of linear expansion, the additive law value W, the measured value Y, and the difference (W−Y) between the two are shown together. The calculation method of the additive rule value is described above. As is known from the table, the additive rule value W
Is 7.7 to 11.6 × 10 ⁻⁵ in each of the examples and comparative examples.
cm / cm.degree. C. (excluding Comparative Example C5 having no dispersed phase and Comparative Example C6 having no skin layer). However, in Examples 1 to 8 according to the present invention, the actual measurement value Y is low as described above. Also, the value of W-Y is as large as 3.8 to 6.4.

As described above, according to the present invention, it is possible to obtain a sandwich long molded product which has a low linear expansion coefficient as a whole, and is excellent in appearance quality in mounting and dimensional stability. In addition, it is possible to obtain a sandwich long molded product which is excellent in scratch resistance and product assembling property and has no warp.

Next, Examples 1 to 3 and Comparative Examples C1 to C
For No. 3, the relationship between the filling rate of the core layer and the linear expansion coefficient is
It is shown graphically in FIG. Also, in the same figure, Comparative Example C6 in which only the core layer (filling rate 100%) and Comparative Example C7 in which the side layer includes only the skin layer are shown. Here, Comparative Example C7 uses only the same skin layer material as in the Examples.

As is known from FIG. 3, Comparative Examples C1 to C
The linear expansion coefficient of No. 3 is the same as that of Comparative Example C6 (core layer filling rate 100
%) And Comparative Example C7 (filling rate of core layer 0%, skin layer only), which is slightly lower than the value on the straight line.
On the other hand, the linear expansion coefficients of Examples 1 to 3 according to the present invention are considerably lower than those of Comparative Examples C1 to C3 having the same filling rate. This is because in the present invention, the bending elastic modulus ratio is 3.0 or more.

[Brief description of drawings]

FIG. 1 is an explanatory view of a side molding manufactured in an example.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a relationship diagram of a filling rate of a core layer and a coefficient of linear expansion in an example.

[Explanation of symbols]

 1. . . Side mall, 11. . . Core layer, 12. . . Skin layer,

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 23/16 LCY C08L 23/16 LCY 25/04 LDS 25/04 LDS 53/00 LLY 53/00 LLY (72) Inventor Takahiko Sato Kasuga-cho, Nishi-Kasugai-gun, Aichi Ochiai, Nagahata No. 1, Toyoda Gosei Co., Ltd.

Claims (1)

(57) [Claims] 1. A long sandwich-shaped molded article comprising a skin layer and a core layer covered with the skin layer, wherein the skin layer is made of a thermoplastic elastomer.
The core layer is composed of 30 to 70% by weight of polypropylene resin as a matrix phase and 70 to 30% by weight of a dispersed phase of either ethylene-α olefin copolymer or styrene thermoplastic elastomer, and A sandwich long molded article, characterized in that the ratio of the flexural modulus of the core layer to the skin layer is 3.0 or more.