JP3092960B2 - 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 molded product comprising a core material and a surface layer substantially covering the entire periphery thereof. More specifically, it consists of a core material and a surface layer that substantially covers the entire circumference, and has not only excellent impact resistance and cold impact resistance, but also has good rigidity and heat resistance. The present invention relates to a molded article having a sandwich structure which is excellent and has good adhesion between a core material and a surface layer.

[0002]

2. Description of the Related Art As is well known, propylene-based polymers are not only excellent in moldability, but also have good mechanical properties, heat resistance, solvent resistance, oil resistance, etc., and are widely produced industrially. It is widely used as parts for automobiles, electric equipment, electronic equipment, and daily necessities. Further, the propylene-based polymer is expected to improve its functional properties by blending (adding) other synthetic resins, rubbers and fillers as various second components and third components due to its wide characteristics as described above. It is a well-known fact that various polymer blends are widely used in the field because of the improvement of the so-called polymer blending technology. Hereinafter, among the above-mentioned applications, a bumper which is a part of an exterior material of an automobile will be specifically described as an example.

Under the trend of reducing the weight, fuel consumption, and cost of the automobile industry, and further specializing and differentiating the automobile, the bumper shape is increased in size, complexity, and luxury. Polymer blends in which one or more of ethylene-propylene rubber, polyethylene resin and inorganic filler are mixed with a propylene polymer composition, especially a propylene polymer (polypropylene resin) rather than a metal Has been widely used and many proposals have been made (for example, see JP-A-53-6425).
No. 6, No. 53-64257, No. 57-55952,
Nos. 57-159841 and 58-11846).

[0004] In the field of injection molding of a thermoplastic resin, sandwich molding is performed. In this molding method, not only the materials used for the surface layer (skin layer) and the core material (core layer) can be of the same kind, but also different kinds of materials can be molded. ,
It is widely used mainly for home electric equipment and OA equipment for the purpose of improving sleds and further improving rigidity and the like.

[0005]

However, although the bumper using the polymer component has sufficient cold shock resistance, the baking temperature at the time of coating cannot be increased because the heat resistance is not always sufficient. In addition, there is a drawback that a molded product (product) cannot be thinned. In order to improve the heat resistance, it is conceivable to increase the amount of the inorganic filler added. However, not only the appearance of the obtained product (bumper) is not good, but also the coating property is reduced and the impact resistance is reduced.

[0006] The purpose of the conventional sandwich molding method is mainly for the following reasons. (1) A foaming agent is used in the core layer to prevent sinking of a thick product such as a housing of the above-mentioned household electric appliance or OA appliance. (2) A composite reinforced material such as glass fiber is used for the core layer in order to improve the dimensional accuracy of home electric appliances such as TV garnishes and parabolic antennas, prevent warpage, and improve rigidity.

[0007] That is, while the conventional sandwich molding method improves the physical properties as described above, there is a problem in the balance of the cold shock resistance, rigidity and heat resistance of the obtained molded product. From the above, the present invention does not have these drawbacks, that is, a molding comprising a polypropylene-based resin composition having sufficient cold impact resistance as a molded article such as an automobile exterior part, and having excellent heat resistance and rigidity. The purpose is to obtain something.

[0008]

SUMMARY OF THE INVENTION The present invention has solved these problems, and its gist is to form a core comprising a core material and a surface layer substantially covering the entire surface of the core material. The surface layer is (A) a propylene homopolymer having a xylene-soluble content of at most 5% by weight at a temperature of 30 ° C. and / or a copolymerization ratio of ethylene of at most 10% by weight (% unless otherwise specified). Is a weight-based, the same applies hereinafter) propylene-ethylene random copolymer,
(B) an ethylene-propylene random copolymer having a xylene-insoluble content of less than 1% at a temperature of 30 ° C and a copolymerization ratio of propylene of 30 to 75%;

(C) The copolymerization ratio of propylene is 15 to 4
0% and the melt flow rate (JIS K72
In accordance with 10, the measurement was performed under the conditions of 14, hereinafter referred to as “MFR”) was 0.1 to 4.0 g / 10 min, the melting peak measured by the differential scanning calorimeter was 80 ° C. or more, and 30 ° C. An ethylene-propylene copolymer having a xylene-insoluble content of 1% or more at a temperature of not less than 4 and a weight average molecular weight / number average molecular weight of 4 or more as an index of the molecular weight distribution measured by gel permeation chromatography, or (D) a core material having a flexural modulus of 10,000 kg / cm ² or more;
And Izod impact strength at 23 ° C (ASTM D
According to 256, measured with notch) is 5.0 kg · cm /
cm or more of a composition containing a propylene polymer as a main component,

The composition ratio of (B) in the total amount of (A) and (B) in the surface layer is 5.0 to 40%, and the MFR (melt flow rate) of the total of these polymers is 2%. 0.085 g / 10 min, the composition ratio of (C) in the surface layer composition is 15-40%, the composition ratio of the inorganic filler is 0-20%, and the thickness of the core material of the molded product is 10
The molded article is characterized in that the thickness of the surface layer relative to 0 is 100 or less, but the thickness of all surface layers is 0.2 mm or more. Hereinafter, the present invention will be described specifically.

The surface layer of the molded article of the present invention comprises a propylene homopolymer and / or a propylene-ethylene random copolymer, an ethylene-propylene random copolymer, an ethylene-propylene copolymer, or a mixture thereof with an inorganic filler. A composition comprising:

(A) Propylene homopolymer and / or propylene-ethylene random copolymer The propylene homopolymer used in the present invention is obtained by homopolymerizing propylene.
The propylene-ethylene random copolymer is obtained by copolymerizing propylene with at most 10% (preferably 9.0% or less, preferably 7.0% or less) of ethylene.

These propylene homopolymers and / or propylene-ethylene random copolymers each have at most 5% (preferably 3%) of a component soluble in xylene at a temperature of 30 ° C. Further, the MFR of these polymers is generally 20 to 100 g / 10 min, preferably 30 to 100 g / 10 min, and particularly preferably 30 to 80 g / 10 min. If the MFR of the propylene homopolymer and / or the propylene-ethylene random copolymer is less than the lower limit, the kneading property is not good,
Furthermore, the moldability of the composition is not good. On the other hand, when the ratio exceeds the upper limit, the impact resistance of the composition is not good.

(B) Ethylene-propylene random copolymer The propylene copolymerization ratio of the ethylene-propylene random copolymer used in the present invention is 30 to 7
5%, preferably 30-70%, especially 35-70%
70% is preferred. Propylene copolymerization ratio is 30%
If less than the ethylene-propylene random copolymer is used, the impact resistance of the composition is not good. On the other hand, an ethylene-propylene random copolymer in which the copolymerization ratio of ethylene exceeds 75% is not only difficult to produce, but also has a problem in the rigidity of the composition.

The ethylene-propylene random copolymer has less than 1% (preferably all soluble) of xylene-insoluble components at a temperature of 30 ° C. Further, the MFR of the ethylene-propylene random copolymer is usually 0.1 for the same reason as in the case of the propylene homopolymer and / or the propylene-ethylene random copolymer.
01 to 5.0 g / 10 min, and 0.02 to 3.0 g / 10 min.
Min., Especially 0.02 to 2.0 g / 10 min.

These propylene homopolymers, propylene-ethylene random copolymers and ethylene-propylene random copolymers are produced by homopolymerization or copolymerization, respectively. A polymer and / or a propylene-ethylene random copolymer and an ethylene-propylene random copolymer may be mixed, and this mixture and other components may be mixed at the composition ratio described below. Producing coalesced and / or propylene-ethylene random copolymers and copolymerizing ethylene and propylene in the same polymerization vessel or another polymerization vessel in the presence of these polymers and the catalyst system used to produce the polymers It may be produced by so-called block copolymerization.

In any of the above cases, the MFR of the total amount of the propylene homopolymer and / or the propylene-ethylene random copolymer and the ethylene-propylene random copolymer is 2.0 to 85 g / 10 minutes, and .
0 to 70 g / 10 min is preferable, especially 5.0 to 50 g / 10 min.
Minutes are preferred. If the total MFR is less than 2.0 g / 10 minutes, the kneading properties and the moldability of the composition are not good. On the other hand, if it exceeds 85 g / 10 minutes, the mechanical properties of the composition, especially the impact resistance, are poor.

(C) Ethylene-propylene copolymer Further, the ethylene-propylene copolymer used in the present invention has a copolymerization ratio of propylene of 15 to 40%, preferably 18 to 40%, more preferably 20 to 40%. 38% is preferred. When an ethylene-propylene copolymer having a propylene content of less than 15% is used, the effect of improving the impact resistance of the obtained composition is poor. On the other hand, if it exceeds 40%, the effect of improving the impact resistance of the obtained composition is good, but the rigidity of the composition is insufficient and the gasohol resistance is not good.

The MFR of the ethylene-propylene copolymer is 0.1 to 4.0 g / 10 minutes, and 0.2 to 4.0 g / 10 minutes.
0 g / 10 min is desirable, especially 0.5 to 4.0 g / 10 min.
Minutes are preferred. When the MFR is less than 0.1 g / 10 minutes, the dispersion at the time of kneading is difficult and the processability of the composition is poor when producing the obtained composition. Further, even if a uniform composition is obtained, the surface of the molded article becomes noticeable such as flow marks and welds, and a composition having good appearance cannot be obtained. On the other hand, if it exceeds 4.0 g / 10 minutes, the effect of improving the impact resistance and gasohol resistance of the obtained composition is insufficient.

The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the ethylene-propylene copolymer is usually from 10 to 10.
0, preferably 10 to 70, and particularly preferably 20 to 70. Incidentally, the ethylene-propylene copolymer,
Normally Differential Scanning Calorime
ter, DSC) is higher than 80 ° C,
80-125 degreeC is preferable, and especially 85-125 degreeC is suitable. When the melting peak is less than 80 ° C., the resulting composition has poor rigidity and tensile strength. The ethylene-propylene copolymer has a xylene insoluble content of 1% or more at a temperature of 30 ° C, preferably 2 to 30%, and more preferably 2 to 25%. This xylene-insoluble matter is 1
%, The rigidity and tensile strength of the composition are poor. On the other hand, if the content exceeds 30%, the impact resistance is not good.

Further, the ethylene-propylene copolymer is subjected to gel permeation chromatography (GPC).
Weight average molecular weight (M
w) / number average molecular weight (Mn) is 4 or more, preferably 4 to 8. If Mw / Mn is less than 4, the resulting composition has poor workability.

(D) Inorganic filler The inorganic filler used in the surface layer of the molded article of the present invention is widely used in general synthetic resins and rubbers. As the inorganic filler, an inorganic compound which does not react with oxygen and water and which does not decompose during kneading and molding is preferably used. As the inorganic filler, aluminum, copper, iron, lead, nickel,
Compounds such as oxides of metals such as magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony, and titanium, hydrates (hydroxides), sulfates, carbonates, and silicates; They are roughly classified into salts and mixtures thereof.

Among these inorganic fillers, those having a powder size of 30 μm or less (preferably 10 μm or less) are preferable. In the case of fibrous materials, the diameter is 1 to 20 μm.
m (preferably 1 to 15 μm) and a length of 10 to 15
0 μm (preferably 15 to 150 μm) is desirable. Further, it is preferable that the flat plate has a diameter of 30 μm or less (preferably 10 μm or less). Among these inorganic fillers, talc, mica, clay, wollastonite,
Potassium titanate, calcium carbonate and the like are preferred.

Composition Ratio The surface layer of the composition of the present invention comprises these propylene homopolymer, propylene-ethylene random copolymer (A), ethylene-propylene random copolymer (B), and ethylene-propylene copolymer. (C) or a composition in which these high molecular weight substances and the inorganic filler are uniformly mixed are used. The composition ratio of (B) in the total amount of (A) and (B) is 5.0 to 40%, preferably 5.0 to 35%, and particularly preferably 7.0 to 35%. If the composition ratio of (B) is less than 5.0%, the resulting composition has poor impact resistance, especially low-temperature impact resistance. On the other hand, if it exceeds 40%, the rigidity of the composition is not good.

In the composition of the present invention, the ethylene-
The composition ratio of the propylene copolymer (C) is 15 to 40%, preferably 15 to 35%, and more preferably 18 to 35%.
Is preferred. When the composition ratio of (C) is less than 15%, improvement in impact resistance at low temperatures is not satisfactory.
On the other hand, if it exceeds 40%, the rigidity and heat resistance of the molded product are not good. When the inorganic filler is further added, the composition ratio is usually at most 20%, and particularly preferably 16% or less. If this composition ratio exceeds 20%, not only the appearance of the obtained molded product is poor, but also the coatability is poor when the surface is coated.

Core Material The core material of the molded article of the present invention is a composition containing a propylene-based polymer as a main component. The propylene-based polymer is typically one or a mixture of two or more of the above-described propylene homopolymer, propylene-ethylene random copolymer, ethylene-propylene random copolymer, and ethylene-propylene copolymer. The MFR of the propylene-based polymer is from 1.0 to 80 g / 10 minutes, preferably from 2.0 to 60 g / 10 minutes. If the MFR is less than 1.0 g / 10 min, the kneadability and moldability are not good, and if it exceeds 80 g / 10 min, the mechanical properties of the molded product, especially the impact resistance, are poor.

The core material in the present invention comprises the propylene-based polymer as a main component, that is, is composed of a propylene-based polymer alone or a composition containing at least 50% of the propylene-based polymer. In the latter case, the remainder is the inorganic filler of the surface layer and other rigid resin such as polyamide resin.

The core material of the present invention has a flexural modulus (ASTM D
Measured according to 690) is at 10,000 kg / cm ² or more, particularly 12,000 / cm ² or more. If the flexural modulus is less than 10,000 kg / cm ² , the effect of improving heat resistance is low. In addition, Izod impact strength (A
(Notched, measured at 23 ° C. according to STM D256) is greater than or equal to 5.0 kg · cm / cm;
It is desirable that the weight is 0 kg · cm / cm or more. If the Izod impact strength is less than 5.0 kg · cm / cm, the impact resistance is significantly reduced, which is not preferable.

When the composition comprising the propylene polymer has a flexural modulus and an Izod impact strength within the above ranges, it can be used as it is. When higher physical properties are desired, the above-mentioned inorganic filler and other synthetic resins may be blended in a range of less than 50%. In this case, if an example of a polyamide as another synthetic resin is described, the polyamide resin has a melting point of 180 to 100 from the viewpoint of kneadability and moldability of the propylene-based polymer and heat resistance and bending elastic modulus of the obtained molded product. 280 ° C (preferably 2
00 to 280 ° C) and the flexural modulus at the time of drying (measurement method is based on the method described above) is 20 × 10 ³ to 35 ×.
10 ³ kg / cm ² (preferably 23 × 10 ^{3 to} 35 × 1
0 ³ kg / cm ²⁾ of it is desirable. Intrinsic viscosity of the polyamide resin (at a concentration of 1 in 98% concentrated sulfuric acid at 25 ° C.)
g / dl, [η]) is generally 1.0 to 5.0 (preferably 1.0 to 4.0) from the viewpoint of moldability and strength.

Examples of the polyamide resin having both the melting point and the flexural modulus are polyamide 6-6 and polyamide 6-6.
Polyamide 6 and polyamide MxD6.
These polyamide resins are described in “Engineering Plastics Encyclopedia” edited by Ihouchi, Oyanagi and Senoo (Gihodo, 19
The production method, various physical properties, applications and the like are described in detail on pages 1 to 56 and pages 74 to 94 of December 15, 1988).

When the above-mentioned polyamide resin is blended to improve the rigidity and heat resistance of the propylene-based polymer, the compatibility of the polymers (resins) is not good. In order to mix uniformly, a so-called compatibilizer must be blended. As the compatibilizer, from the viewpoint of heat resistance and rigidity of the core material, a propylene polymer such as the propylene homopolymer or propylene-ethylene random copolymer or another monomer containing ethylene as a main component (for example, α, α, β-unsaturated dicarboxylic acid (eg, maleic acid) or its anhydride (eg, maleic anhydride) by graft polymerization to a copolymer with β-unsaturated dicarboxylic acid, its anhydride, methyl methacrylate). Are preferred. The compounding ratio of the modified product is generally 3.0 to 100 parts by weight of the total amount of the propylene-based polymer and the polyamide resin.
20 parts by weight.

Method for Producing the Composition In the molded article of the present invention, when the above-described composition is used for producing the surface layer and the core material, the respective components may be uniformly mixed. In this case, ultraviolet absorbers, antioxidants, weathering stabilizers, plasticizers, lubricants, antistatic agents, coloring agents (pigments) generally added in the field of polyolefin resins (particularly, polypropylene resins).
Such an additive may be added in a range that does not substantially impair the substance of each composition or synthetic resin.

In order to produce the composition, a method generally used in the field of synthetic resins may be applied. Examples of the mixing method include a method of dry blending using a mixer such as a Henschel mixer and a method of melt-kneading using a mixer such as a roll mill, a screw type extruder, a kneader and a Banbury mixer. At this time, a more uniform composition can be obtained by dry blending the composition components in advance and further melt-kneading the resulting mixture. In addition, the composition is preferable in terms of handling when the pellet is used to produce a molded article described below.

Molding Method The molded article of the present invention can be obtained, for example, by a so-called sandwich molding method generally practiced in the field of synthetic resins. As described above, the sandwich molding method involves injecting the material of the surface layer, subsequently injecting the material of the core material, and finally injecting a small amount of the material of the surface layer into the gate portion. The sandwich molding method is described in detail in "Mulder Series, Latest Injection Molding Technology-Its Practice and Application-" (edited by Sanko Shuppan Co., Ltd., 1988), pp. 137 to 144, edited by Akari Hiroe. I have.

In both the melt-kneading and the sandwich molding, it is necessary to carry out the process at a temperature at which the polymer materials such as propylene-based polymers to be used are respectively melted. However, when carried out at a high temperature, the polymer material used may be thermally decomposed. Although the melt-kneading temperature and the injection molding temperature cannot be unconditionally defined by the types and composition ratios of the respective materials used for the surface layer and the core material, they are generally 180 to 300 ° C. (preferably,
190-280 ° C).

Molded Article The molded article of the present invention obtained as described above has a surface layer substantially covered over the entire surface of the core material.
The thickness of the surface layer with respect to the thickness 100 of the core material is 100 or less, particularly preferably 80 or less. Core thickness 10
If the thickness of the surface layer with respect to 0 exceeds 100, not only the rigidity of the obtained molded product is not good but also the heat resistance is insufficient. The thickness of all surface layers is 0.2
mm or more, preferably 0.3 mm or more, particularly 0.5 mm
The above is preferable. When the thickness of all the surface layers is less than 0.2 mm, it is difficult to cover the entire surface of the core material of the obtained molded product, and the impact resistance and cold impact resistance of the molded product are poor. It is enough.

The molded article of the present invention is characterized in that a polymer composition having extremely high impact resistance is used for the surface layer, a material having good adhesion between the core material and the surface layer and high rigidity is used as described above. By manufacturing by a molding method, a material having a so-called sandwich structure and obtaining a balance between impact resistance and heat resistance, which could not generally be obtained with a commonly used polypropylene resin blend material, is obtained. It was possible. If the material used for the surface layer and the material used for the core material are opposite, a material having a sufficient balance between impact resistance and heat resistance cannot be obtained.
The reason for this is that the crack generation point (starting point) generated when the sandwich molded body receives an impact becomes the surface layer, which propagates through the surface layer.

[0038]

The present invention will be described in more detail with reference to the following examples and comparative examples. In Examples and Comparative Examples, the flexural modulus was in accordance with ASTM D790, and the bending speed was 2.
Measured under the condition of 5 mm / min.
In accordance with D648, the measurement was performed under the condition that the load was 4.6 kg / cm ² . Further, the impact strength was measured by a high-speed impact tester [Rohmometric, Model Impact Tester-8].
000], the impact velocity is 5 m / sec, the diameter of the tip of the shooting bar is 1/2 inch, the diameter of the sample receiving jig is 2.5 inches,
The fracture energy was obtained from a stress-strain curve obtained when an impact test was performed under the conditions of a sample size of 100 × 100 mm, a thickness of 6 mm, and a measurement temperature of −30 ° C., and displayed. The physical properties and the like of the polymers (A) to (E) and the inorganic filler used as the surface layer (skin layer) and the core material (core layer) in Examples and Comparative Examples are shown below.

[(A) propylene homopolymer and (B)
Ethylene-propylene random copolymer] In a polymerization vessel, only propylene was polymerized using a Ziegler-Natta catalyst without using a solvent. Then, ethylene was supplied to the polymerization vessel to produce a random copolymer of ethylene and propylene. Obtained polymer [hereinafter referred to as "HIPP (1)"
Is a propylene homopolymer (A) (MFR 32 g
/ 10 min, insoluble in xylene at 30 ° C)
Ethylene-propylene random copolymer (B) (M) containing 84% of ethylene and a copolymerization ratio of ethylene of 53%
FR 0.1 g / 10 min, all soluble in xylene at a temperature of 30 ° C.). This HIPP (1)
Had an MFR of 13 g / 10 min. A polymer produced by the same method [hereinafter referred to as "HIPP (2)"] is a propylene homopolymer (A) (MFR 40 g / 10 min, 3
Ethylene-propylene random copolymer (B) (MFR0.0) containing 74% of xylene at a temperature of 0 ° C.) and containing 50% of ethylene.
8 g / 10 min, all soluble in xylene at a temperature of 30 ° C.). MFR of this HIPP (2)
Was 17 g / 10 min.

[(C) Ethylene-propylene copolymer]
Further, as the ethylene-propylene copolymer, the copolymerization ratio of propylene was 38%, and the Mooney viscosity (ML
_{1 + 4} , 100 ° C.) is 42 and the MFR is 1.0 g
/ 10 minutes ethylene-propylene copolymer [melting point 11
At a temperature of 5 ° C. and 30 ° C., a xylene-insoluble content of 4.0%,
Mw / Mn 5.0, hereinafter referred to as “EP (1)”], the copolymerization ratio of propylene is 37%, and the Mooney viscosity (M
L _{1 + 4} , 100 ° C.) is 41 and the MFR is 1.0
g / 10 minutes ethylene-propylene copolymer [melting point 1
Xylene insolubles at a temperature of 05 ° C. and 30 ° C. 2.0
%, Mw / Mn 4.8, hereinafter referred to as “EP (2)”].

[(D) Inorganic Filler] Further, as an inorganic filler, talc having an average particle size of 2.0 μm and an aspect ratio of 5.0, and light carbonic acid having an average particle size of 0.5 μm are used. Calcium (hereinafter referred to as “CaCO ₃ (1)”) and heavy calcium carbonate having an average particle size of 10 μm (hereinafter referred to as “CaCO ₃ (2)”) having an average particle size of 5.
Mica having a size of 0 μm and clay having an average particle size of 5.0 μm were used.

[(E) Other Synthetic Resin Used for the Core Material] In addition to the same polymer as the above-mentioned surface layer, other synthetic resins other than the same polymer as the above-mentioned surface layer include propylene single weight having an MFR of 0.6 g / 10 min. To 100 parts by weight of the coalesced, 0.7 parts by weight of maleic anhydride and 0.4 parts by weight of benzoyl peroxide were previously dry-blended for 5 minutes using a Henschel mixer, and the obtained mixture was extruded into an extruder (diameter 40 mm, cylinder A modified product (hereinafter referred to as a “modified PP”) having a limiting viscosity [η] of 2.5 and a flexural modulus of 2 when dried.
Polycaprolactam (hereinafter referred to as “PA6”) having a density of 6 × 10 ³ kg / cm ² was used.

Each of the polymers and the inorganic fillers whose types and amounts are shown in Table 1 were dry-blended for 5 minutes using a Henschel mixer in advance. Each of the obtained mixtures was melt-kneaded at a resin temperature of 200 ° C. using a vented twin-screw extruder (diameter 30 mm) to produce pellet-shaped compositions. Table 1 shows abbreviations of the obtained compositions. Each composition was used as a surface layer of a molded article described below.

Further, each composition component whose type and amount is shown in Table 2 was dry-blended in the same manner as described above to produce each mixture. Each mixture was melt-kneaded in the same manner as described above (the resin temperature varies depending on the type and amount of the composition components) to produce pellet-shaped composition components. Table 2 shows the MFR, flexural modulus, Izod impact strength (with notch), and abbreviations of the obtained compositions. Each composition component was used as a core material of a molded product described below.

Examples 1 to 9 and Comparative Examples 1 to 7 Tables 3 and 4 show the types of the respective compositions.
Each composition obtained as described above was sandwiched with a sandwich injection molding machine [Battenfeld, West Germany].
ld), model BM850S-C], the material of the surface layer is injection molded first, then the material of the core material is injection molded, and then the material of the surface layer (about 2% of the surface layer) is injection molded. Then, a flat molded product (400 × 400 mm, thickness 6 mm) was molded. Cut a sample from the obtained molded product,
The flexural modulus, heat deformation temperature, and fracture energy were measured.
Tables 3 and 4 show the results. Tables 3 and 4 show the thickness of the surface layer of each molded product.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

The molded article of the present invention exhibits the following effects. (1) It has excellent impact resistance (particularly, low-temperature impact resistance). (2) Good heat resistance. (3) Excellent rigidity (flexural modulus). (4) In particular, when molded using the same type of material as compared with a molded product obtained by a commonly used injection molding method, the molded article has higher impact resistance (including low-temperature impact resistance), heat resistance and rigidity. The balance is excellent. In particular, the physical properties of heat resistance and impact resistance are well balanced. (5) Since the core material can be highly filled with the inorganic filler, the dimensional accuracy is excellent. The molded article of the present invention can be used in various fields to exhibit the above effects. Representative applications are shown below. (1) Automotive exterior parts such as bumpers, bumper aprons, spoilers, side moldings, side air dams, and engine under covers. (2) Motorcycle parts such as front fenders and body covers.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akirako Katagiri 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Showa Denko KK Kawasaki Resin Laboratory (56) References JP-A-4-35943 (JP, A JP-A-3-163143 (JP, A) JP-A-3-168235 (JP, A) JP-A-64-18633 (JP, A) JP-A-61-192752 (JP, A) JP-A-58-1983 163656 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J ⁷ /04-7/06 B32B 27/00-27/42 C08L 1/00-101/16

Claims (1)

(57) [Claims] 1. A molded article comprising a core material and a surface layer substantially covering the entire surface of the core material, wherein the surface layer (A) has a high xylene-soluble content at a temperature of 30 ° C. A propylene homopolymer and / or a propylene-ethylene random copolymer having a copolymerization ratio of ethylene of at most 10% by weight, and (B) 30 ° C.
The xylene insoluble content is less than 1% by weight at the temperature of
And an ethylene-propylene random copolymer having a copolymerization ratio of propylene of 30 to 75% by weight, a copolymerization ratio of (C) propylene of 15 to 40% by weight, and a melt flow rate of 0.1 to 4. 0 g / 10 min, and the melting peak measured by a differential scanning calorimeter is 80 ° C. or more,
An ethylene-propylene copolymer having a xylene-insoluble content of 1% by weight or more at a temperature of 30 ° C and a weight average molecular weight / number average molecular weight of 4 or more, which is an index of a molecular weight distribution measured by gel permeation chromatography; Alternatively, the core material has a bending elastic modulus of 10,000 kg / cm.
It is composed of a composition mainly composed of a propylene-based polymer having an Izod impact strength at 23 ° C. of not less than ^{2 and not} less than 5.0 kg · cm / cm, and the total amount of (A) and (B) in the surface layer The composition ratio of (B) in the
The total melt flow rate of these polymers is 2.0 to 85 g / 10 min, the composition ratio of (C) in the surface layer composition is 15 to 40% by weight, The composition ratio of the material is 0 to 20% by weight, and the thickness of the surface layer is 100 or less with respect to the thickness of the core material 100 of the molded product, but the thickness of all surface layers is 0.2 mm or more. A molded article characterized by the following.