JPH0671829A - Polypropylene resin molding - Google Patents

Abstract

PURPOSE:To provide a polypropylene resin molding, utilizing the recycled material of polypropylene resin, excellent in appearance and prominent in resistance to shock, especially in low-temperature impact one, as well as in rigidity. CONSTITUTION:The molding is constituted of polypropylene resin or a core member having the principal constituent of recycled material of the same resin and a surface coating layer having the principal constituent of fresh polypropylene resin. The preferably surface coating layer is formed of a composition consisting of polypropylene polymer, copolymer of ethylene/alpha-olefin and inorganic filler, where necessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin molded product in which scrap resin of a recovered polypropylene resin molded product is reused. More specifically, a core material containing scrap resin (hereinafter referred to as recycled resin) of recovered polypropylene-based resin molding as a main component, and a surface coating layer or polypropylene-based polymer containing a fresh polypropylene resin as a main component. The present invention relates to a polypropylene resin molded article including a surface coating layer made of a composition containing an ethylene / α-olefin copolymer as a main component.

The polypropylene resin molded article of the present invention is
It has a good appearance, a good balance of impact resistance, especially cold impact resistance, rigidity and heat resistance, and has good adhesiveness between the core material and the surface layer.

[0003]

2. Description of the Related Art Propylene-based polymers are not only excellent in moldability but also good in mechanical properties, heat resistance, solvent resistance, oil resistance and the like. It is used in various fields as parts of electrical equipment, electronic equipment, and daily necessities. Further, a colored resin coating film is often formed on the surface of a propylene-based polymer molded article for the purpose of improving its high quality (appearance) and imparting scratch resistance.

On the other hand, from the viewpoint of global environment protection, in recent years, collecting and reusing (recycling) resin molded products has been taken up as an urgent issue, and has been studied and implemented.

As a recycling method, generally, the recovered resin molded product is crushed by a crusher and used as a raw material for molding, or the crushed product is pelletized by an extruder and used as a raw material for molding. Has been taken.
However, a molded product obtained from a recycled material of a resin molded product having the above-mentioned colored resin coating film has poor moldability,
Further, not only the appearance of the molded product is inferior, but also the physical properties are greatly deteriorated. Therefore, in reality, it cannot be reused as the same molded product as the original molded product.

Explaining automobile bumpers, which are a typical application of polypropylene resins, in order to reduce the weight of automobiles, reduce fuel consumption, and reduce manufacturing costs, further specialization and diversification of automobile designs are expected. Under the circumstances, bumpers are becoming larger, more complex, and higher quality.Under such circumstances, as a molding material, a propylene-based polymer composition is used rather than a metal, and particularly a polypropylene-based polymer is used as ethylene-propylene. A large number of polymer blends in which one type or two or more types of a system rubber, a polyethylene resin or an inorganic filler are mixed have been proposed and put into practical use. (For example, JP-A-53-64256 and JP-A-53-6.
No. 4257, No. 57-55952, No. 57-1598.
No. 41, No. 58-111846). In many cases, the surface of the bumper molded from these compositions is coated with urethane or acrylic for the purpose of improving the commercial properties.

In the field of thermoplastic resin injection molding, sandwich molding is performed. In this molding method, the materials used for the surface layer (skin layer) and the core material (core layer) are not only the same kind but also different materials can be formed. ,
It is widely used mainly for household electric appliances, office automation equipment, etc. for the purpose of improving the warp and further improving the rigidity. Furthermore, also in the field of blow molding, the surface layer (skin layer)
There has been proposed a manufacturing method for obtaining a molded product having a sandwich structure composed of a core material (core layer).

In particular, there is also known a method for producing an injection molded product and a blow molded product using a recycled material for a core material (core layer) and a fresh resin for a surface layer (for example, Japanese Examined Patent Publication No. 6).
0-44155, JP-A-61-259943, JP-A-62-28332, and JP-A-63-237924). However, a molded article in which a recycled material of polypropylene resin is used as a core material and a fresh polypropylene resin is used as a surface coating layer is not known.

[0009]

When a polypropylene resin molded product, for example, an automobile bumper is crushed and the recycled material is reused, the colored resin coating film coated on the surface is mixed into the remolded product, so that the appearance is deteriorated. Markedly inferior,
The physical properties, in particular the impact resistance, are greatly deteriorated, so that the bumper cannot be used again.

An object of the present invention is a molded article using a polypropylene resin recycled material, which has a good appearance and has a good balance of impact resistance, particularly cold impact resistance, rigidity and heat resistance. To provide a resin-based molded product.

[0011]

[Means and Action for Solving the Problems] The above-mentioned object is to provide a core material mainly composed of scrap resin of a recovered polypropylene-based resin molded product, particularly a polypropylene-based resin molded product having a colored coating film on the surface, and a fresh material. This is achieved by a polypropylene-based resin molded article including a surface coating layer containing such a polypropylene-based resin as a main component.

In particular, the surface coating layer comprises (a) a polypropylene-based polymer and (b) an ethylene / α-olefin copolymer rubber having a copolymerization ratio of 20 to 70% by weight of an α-olefin having 6 or less carbon atoms. , And (c) those containing as a main component a composition comprising these (a) and / or (b) and an inorganic filler are preferred.

Using the recycled material of the polypropylene resin molded product recovered as described above, particularly the polypropylene resin molded product having a colored resin coating film on the surface, as a core material,
By selecting a fresh polypropylene-based resin or a composition mainly composed of a polypropylene-based polymer and an ethylene / α-olefin copolymer as a surface coating material,
It was quite surprising that a molded product having a good balance of impact resistance, particularly cold impact resistance, rigidity and heat resistance was obtained.

In the present specification, the "polypropylene resin" means a polypropylene polymer alone or a polypropylene polymer as a main component, and another polymer (for example, ethylene / vinyl acetate copolymer) as a minor component. Refers to a resin composition. The term “polypropylene polymer” as used herein refers to a propylene homopolymer or a copolymer containing propylene as a main component, for example, a propylene / ethylene block copolymer or a propylene / ethylene random copolymer.

The polypropylene resin molded article of the present invention is
The core material is made of recycled polypropylene resin molded product recycled material. As the recycle material, one having a colored resin coating film derived from a urethane-based paint or an acrylic-based paint is particularly used. In particular, in order to obtain a polypropylene-based resin molded product with high impact resistance and rigidity, the bending elastic modulus is 8,000 kg as a recycled material.
/ Cm ² or more and the Izod impact strength at 23 ° C. of 6.5 kg · cm / cm ² or more is preferable.

The surface coating layer of the polypropylene resin molded article of the present invention comprises (a) a fresh polypropylene resin, that is, a homopolymer of propylene or a copolymer containing propylene as a main component (preferably propylene / ethylene). Random copolymer) or a composition containing these polymers as a main component, or (a) a fresh polypropylene-based polymer, that is, a propylene homopolymer or a propylene-based copolymer. Polymer and (b) Copolymer of fresh ethylene and α-olefin having 6 or less carbon atoms, particularly ethylene and α-, wherein the copolymerization ratio of α-olefin having 6 or less carbon atoms is 20 to 70% by weight. A composition containing a copolymer with an olefin as a main component, or (c) a composition in which a small proportion of an inorganic filler is added to the above (a) and / or (b) Constructed. The polypropylene resin (a) has a melt flow rate of 0.1 to 1
00g / 10min is preferable, and ethylene / α
-The olefin copolymer (b) has a Mooney viscosity (M
L _{1 + 4} , 100 ° C.) is preferably 10 to 140.

The polypropylene polymer, the copolymer of ethylene and α-olefin, and the inorganic filler used for forming the preferred surface coating layer of the polypropylene resin molded article of the present invention will be described below.

Polypropylene Polymer (Surface Coating Layer) The polypropylene polymer used for forming the surface coating layer of the molded article of the present invention is a propylene homopolymer and / or a copolymer containing propylene as a main component. Among the propylene copolymers, a propylene / ethylene random copolymer having a copolymerization ratio of ethylene of 10% by weight or less, particularly 6% by weight or less is preferable. If the amount of ethylene in this copolymer is too large, the rigidity will decrease. The melt flow rate (MFR) of the propylene-based polymer is 0.1 to 100 g /
It is 10 minutes, 1.0 to 80 g / 10 minutes is desirable, and 2.0 to 60 g / 10 minutes is particularly preferable.

Ethylene / α-olefin Copolymer (Surface Coating Layer) The ethylene / α-olefin copolymer used in the surface coating layer of the molded article of the present invention is preferably at least ethylene which is not substantially crystalline. At most 6 carbons
It is a copolymer rubber with individual α-olefins. Of the α-olefins, propylene and butene-1 are preferred. This copolymer rubber may be a copolymer of ethylene and the above-mentioned α-olefin, and further comprises ethylene and propylene as main components, and copolymerizes a small amount (generally 10% by weight or less) of the monomer described below. It may be a multi-component copolymer rubber obtained by the above. As the monomer, 1,4
-Pentadiene, 1,5-hexadiene and 3,3-
Linear or branched diolefins containing two double bonds at the ends such as dimethyl-1,5-hexadiene, 1,4-hexadiene and 6-methyl-1,5-
A linear or branched diolefin containing only one double bond at the end, such as heptadiene, or bicyclo [2,2]
Cyclic diene hydrocarbons such as 2,1] -heptene-2 and its derivatives.

The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the ethylene / α-olefin copolymer rubber is generally 10 to 10.
140, preferably 15 to 130, especially 2
0 to 120 is preferable. When the Mooney viscosity of less than 10 is used, the moldability is improved, but not only the effect of improving the impact resistance is low, but also delamination may occur during gate cutting of the molded product. On the other hand, when the number of ingredients exceeds 140, not only is it difficult to disperse during kneading, but even if a uniform composition is obtained, flow marks, weld lines, etc. stand out on the surface of the obtained molded product. Becomes severe and the appearance is inferior.

The copolymerization ratio of propylene in the ethylene / α-olefin copolymer is 20 to 70% by weight.
-60% by weight is preferable, and 20-55% by weight is particularly preferable. When a copolymer rubber having a propylene copolymerization ratio of less than 20% by weight is used, the heat resistance of the resulting composition is inferior and the impact resistance improving effect is not good. on the other hand,
If it exceeds 70% by weight, the rigidity of the composition is insufficient, and there is a problem in terms of scratch resistance of the obtained molded product.

Inorganic Filler (Surface Coating Layer) The resin or rubber component used in the surface coating layer of the molded article of the present invention may optionally contain an inorganic filler. The inorganic filler is not particularly limited, and examples thereof include those widely used in the fields of general synthetic resins and rubber. Specific examples are aluminum, copper, iron,
Lead, nickel, magnesium, calcium, barium,
Compounds such as oxides of metals such as zinc, zirconium, molybdenum, silicon, antimony and titanium, their hydrates (hydroxides), sulfates, carbonates, silicates, double salts thereof and mixtures thereof Can be mentioned. Of these, talc, mica, clay, wollastonite, potassium titanate, and calcium carbonate are preferable. The form of these inorganic fillers is not particularly limited, but spherical or tabular grains having a diameter of 30 μm or less or fibrous substances having a diameter of 1 to 20 μm and a length of 10 to 150 μm are preferable.

When an inorganic filler is blended, the composition ratio of the inorganic filler to the total amount of the polymer substances (resin and rubber component) of 100 parts by weight is usually at most 25 parts by weight, preferably 20 parts by weight or less. Is. When the composition ratio of the inorganic filler is more than 25% by weight based on 100 parts by weight of the total amount of the polymer substance, not only the appearance of the obtained molded product is deteriorated but also the coatability on the surface of the core material is not good.

A particularly preferred surface coating layer is formed from a composition comprising the above-mentioned polypropylene polymer, ethylene / α-olefin copolymer rubber and, if necessary, an inorganic filler. Ethylene in the total amount of polypropylene-based polymer and ethylene / α-olefin copolymer rubber /
The composition ratio of the α-olefin copolymer rubber is 25 to 55% by weight, preferably 30 to 55% by weight, and particularly 30 to 55% by weight.
50% by weight is preferred. If the composition ratio of the ethylene / α-olefin copolymer rubber in the total amount of both is less than 25% by weight, the impact resistance of the obtained molded article is not sufficient, while if it exceeds 55% by weight, the molding Insufficient rigidity and heat resistance of the product. When an inorganic filler is compounded in addition to the polypropylene-based polymer and the ethylene / α-olefin copolymer rubber, the compounding amount is the total of the polypropylene-based polymer and the ethylene / α-olefin copolymer rubber as described above. The amount is 25 parts by weight or less, preferably 20 parts by weight or less, relative to 100 parts by weight.

Core Material Next, the core material of the polypropylene resin molded product of the present invention will be described. This core material is a recycled material of polypropylene resin molded product, and in particular, a recycled product of molded product having a urethane or acrylic colored resin coating film on the surface can be used, but those obtained by removing these coating films are also available. Of course you can use it. The content of the colored resin coating film derived from the urethane-based or acrylic-based coating material in the recycled material constituting the core material is generally 10% by weight or less, preferably 8% by weight or less. It is not preferable to use a resin coating film having a mixing ratio of more than 10% by weight, because the molded article has poor blocking resistance.

The polypropylene resin that constitutes the core material is
Polypropylene polymer (that is, polypropylene homopolymer and copolymer containing propylene as a main component, for example, propylene / ethylene random copolymer having an ethylene content of 10% by weight or less) or polypropylene polymer as a main component And a composition with another polymer.
Alternatively, a composition of a polypropylene-based polymer and the above-mentioned copolymer rubber of ethylene and an α-olefin having 6 or less carbon atoms, or a composition obtained by further adding a small proportion of an inorganic filler to this composition. Is. The proportion of the polypropylene-based polymer in these recycled material compositions is 60% by weight or more, preferably 65% by weight or more. If the proportion of the polypropylene-based polymer in the recycled material is less than 60% by weight, the impact resistance of the molded product will be poor. Also,
When the core material and the surface coating layer are made of a polypropylene-based polymer, ethylene / α-olefin copolymer rubber and an inorganic filler, the core material and the surface coating layer may have the same components but different components. May be.

The MFR of recycled materials is generally from 1.0 to
80 g / 10 minutes, preferably 2.0-80 g / 10
Min, more preferably 2.0 to 60 g / 10 min. If the MFR of the recycled material is less than 1.0 g / 10 minutes, the moldability is poor. On the other hand, if more than 80 g / 10 minutes is used, the mechanical properties of the molded product, especially the impact resistance, will be poor.

Flexural modulus of recycled material used as core material of the present invention (measured according to ASTM-D690)
Is more than 8,000kg / cm ² , especially 9,000kg /
cm ² or more is preferable. Flexural modulus 8,000kg / cm ²
If it is less than 1, the heat resistance of the molded product is low. Also, according to the Izod impact strength (ASTM-D256) of recycled materials,
Notched, measured at 23 ° C) is 6.5 kg · cm / cm ²
Above, above all, it is desirable to have 8.0 kg · cm / cm ² or more. Izod impact strength of 6.5kg ・ cm / cm ²
When it is less than 1, the impact resistance of the molded product is significantly deteriorated, which is not preferable.

It is particularly preferable that the core material of the present invention has both the flexural modulus and the Izod impact strength as described above. When the recycled material has a flexural modulus and an Izod impact strength within the ranges, it can be used as it is. When the flexural modulus and Izod impact strength of the recycled material do not fall within these ranges, the above-mentioned inorganic filler and rubber (for example, ethylene / α-
It is preferable to blend olefin copolymer rubbers) and adjust their properties so that they fall within the respective ranges described above.

The recovered polypropylene resin molded article can be used as a recycled material with the colored resin coating film attached, which is advantageous in terms of cost.
Depending on the recovered molded product, the colored resin coating film can be removed and used as a recycled material.

Preparation of molding raw material The recycled material used as the core material is obtained by crushing the collected polypropylene resin and pelletizing it if necessary. When the material forming the surface coating layer is a mixture, the respective components are combined and mixed uniformly. This mixture and, if necessary, the recycled material pulverized product should be mixed with a polyolefin resin (specifically,
Additives such as UV absorbers, antioxidants, weather resistance stabilizers, plasticizers, lubricants, antistatic agents, and colorants (pigments) that are commonly added in the field of polypropylene resins) You may add the substance which a resin has in the range which does not impair substantially.

To produce a homogeneous mixture, a method generally used in the field of synthetic resins may be applied. Examples of the mixing method include a dry blending method using a mixer such as a Henschel mixer, and a melt kneading method using a mixer such as a roll mill, a screw type extruder, a kneader and a Banbury mixer. A more uniform composition can be obtained by previously dry-blending the composition components and further melt-kneading the resulting mixture. In addition, the composition is preferably pelletized in terms of handling when producing a molded product.

Molding Method In order to manufacture the polypropylene resin molded article of the present invention from the above-mentioned recycled material and surface coating layer-forming material, a so-called sandwich molding method which is generally practiced in the field of synthetic resins can be adopted. it can. In the sandwich molding method, the material of the surface layer is first injected, then the material of the core material is injected, and finally, a small amount of the material of the surface layer is injected into the gate portion. For sandwich molding method,
Megumi Hiroe "Mulder series, latest injection molding technology-
Its actuality and application- "(published by Sanko Publishing Co., Ltd., 1988), pp. 137 to 144.

In the melt-kneading or the sandwich molding, it is necessary to heat the polymer materials such as polypropylene polymer and ethylene / α-olefin copolymer rubber to be melted. is there. However, when heated to a high temperature, the polymer material used may be thermally decomposed. The melt-kneading temperature and the injection molding temperature cannot be unconditionally specified depending on the type and composition ratio of each material used for the surface coating layer and the core material, but generally 180 to 300 ° C (preferably 190 to 280 ° C). Is.

Molded Product The molded product of the present invention obtained as described above has a surface coating layer formed on the entire surface of the core material. The thickness of the surface layer is preferably 100 or less with respect to the thickness 100 of the core material. Further, the thickness of all surface coating layers is preferably 0.2 mm or more.

The molded article of the present invention is characterized in that a polypropylene polymer having a very high impact is used for the surface coating layer, and a material having a good adhesion to the surface coating layer as a core material and having an extremely high rigidity is used. By using the molding method as described above, it has a so-called sandwich structure, and has a balance of impact resistance and heat resistance that could not be generally obtained with a commonly used polypropylene-based resin blend material. I was able to get what I had.

[0037]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. In Examples and Comparative Examples, the flexural modulus was measured according to ASTM-D790, the bending speed was measured at 2.5 mm / min, and the heat deformation temperature was measured according to ASTM-D648, and the load was 4.6 kg / cm ^2.
It was measured under the conditions. Furthermore, for impact strength, use a high-speed impact tester [RHOMETRIC company type, model impact tester (Impact tester) -8000],
Impact velocity is 5 m / sec, diameter of tip of hammer is 1/2 inch, diameter of sample receiving jig is 2.5 inch, sample size is 100 × 100 mm, same thickness is 6 mm and measurement temperature is -30.
The fracture energy was obtained from the stress-strain curve obtained during the impact test under the condition of ° C and displayed.

The physical properties and the like of the polypropylene-based polymer, the ethylene / α-olefin copolymer rubber and the inorganic filler used as the surface layer (skin layer) in Examples and Comparative Examples are shown below. (A) Polypropylene-based polymer Propylene homopolymer having MFR of 15 g / 10 minutes [hereinafter referred to as "PP (A)"] and ethylene copolymerization ratio of 5.0% by weight, and MFR of 13 g / 10
The propylene / ethylene random copolymer (hereinafter referred to as "PP (B)") was used.

(B) Ethylene / α-olefin copolymer Mooney viscosity (ML _{1 + 4} , 100 ° C., the same applies hereinafter) is 36.
And an ethylene / propylene copolymer rubber having a propylene copolymerization ratio of 38% by weight (hereinafter referred to as "EPR
(A)) and a Mooney viscosity of 60 and an propylene copolymerization ratio of 27% by weight (hereinafter referred to as “EPR (b)”).

(C) Inorganic filler As the inorganic filler, talc having an average particle size of 2.0 μm and an aspect ratio of 5.0, and an average particle size of 0.5.
μm Light calcium carbonate (hereinafter “CaCO
₃ (1) ”), mica having an average particle size of 5.0 μm and clay having an average particle size of 5.0 μm were used.

The recycled material used as the core material and its physical properties are shown below (however, the same materials as those used for the surface coating layer are omitted). (D) Recycled material Several types of polypropylene bumpers (different shapes, mixed with painted and unpainted products) collected from scrap cars are crushed with a crusher and recycled (hereinafter called recycled material (A)) Used as. When the physical properties were confirmed, the MFR was 9.5 g / 10 minutes, the flexural modulus was 9,800 kg / cm ² , and the Izod impact strength was 48 kg.
It was / cm ² . Further, 1.8% by weight of the urethane coating film was mixed in the recycled material (A).

A padless instrument panel (a type in which vinyl chloride leather and foam were not attached) recovered from a scrap car was crushed by a crusher and used as a recycled material (hereinafter referred to as a recycled material (B)). When the physical properties were confirmed, the MFR was 12.5 g / 10 minutes, the flexural modulus was 28,000 kg / cm ² , and the Izod impact strength was 5.3 kg · cm / cm ² . The recycled paint (B) contains 0.7% by weight of acrylic paint film.
It was mixed.

The EPR (a) was dry blended with the recycled material (B) in an amount of 10% by weight, melted and kneaded using a screw type extruder, and used as a recycled material (hereinafter referred to as a recycled material (C)). When the physical properties were confirmed, the MFR was 9.5 g / 10 minutes, the flexural modulus was 23,500 kg / cm ² , and the Izod impact strength was 8.5 kg · cm / cm ² . Further, 0.6% by weight of an acrylic coating film was mixed in the recycled material (C).

The recycled material (A) has the above-mentioned talc (average particle diameter is 2.0 μm and aspect ratio is 5.0).
20% by weight was dry blended, melt-kneaded using a screw type extruder, and used as a recycled material (hereinafter referred to as a recycled material (D)). When the physical properties were confirmed, the MFR was 8.0 g / 10 minutes, the flexural modulus was 17,000 kg / cm ² , and the Izod impact strength was 3
It was 5 kg · cm / cm ² . Further, a urethane coating film was mixed in the recycled material (D) by 1.4% by weight.

The propylene-based polymer, the copolymer rubber and the inorganic filler whose types and blending amounts are shown in Table 1 were dry blended in advance for 5 minutes using a Henschel mixer. The obtained mixture was mixed with a vented twin-screw extruder (diameter: 30 m) at a resin temperature of 200 ° C.
m) was melt-kneaded to produce pelletized compositions. The abbreviations of the obtained compositions are shown in Table 1. Each composition was used as a surface layer of a molded article described below.

[0046]

[Table 1]

Examples 1 to 7 and Comparative Examples 1 to 7 Table 2 shows the type of each composition. Each composition obtained as described above was subjected to a sandwich injection molding machine [Model BM850S-C manufactured by Battenfeld, West Germany] to first injection-mold the material of the surface coating layer, and then to form the core material. After injection molding the material, the material of the surface coating layer is injection molded, and a flat molded product (400 x
400 mm, thickness 6 mm) was molded. A sample was cut out from the obtained molded product, and the flexural modulus, heat deformation temperature, and breaking energy were measured. The results are shown in Tables 2 and 3. Further, the thickness of the surface layer of each molded product is shown in Tables 2 and 3.

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

The molded article of the present invention has the following excellent properties. (1) The appearance of the molded product is good. (2) It has excellent impact resistance, especially at low temperature. (3) Excellent rigidity (flexural modulus). (4) Since the core material can be highly filled with the inorganic filler, the dimensional accuracy is excellent.

Since the molded article of the present invention has the above-mentioned characteristics, it can be used in various fields. Typical uses are shown below. (1) Automotive exterior parts such as bumpers, bumper aprons, spoilers, side moldings, side air toms and engine undercovers (2) Motorcycle parts such as front fenders and body covers.

Front Page Continuation (72) Inventor Akiko Katagiri 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Showa Denko K.K.

Claims (5)

[Claims] 1. A polypropylene-based resin molded product comprising a recovered polypropylene-based resin molded product, a core material containing scrap resin as a main component, and a surface coating layer containing fresh polypropylene resin as a main component. 2. The polypropylene resin molded product according to claim 1, wherein the recovered polypropylene resin molded product has a colored resin coating film. 3. The copolymerization ratio of the core material mainly containing scrap resin of the recovered polypropylene resin molded product, the polypropylene polymer and the α-olefin having 6 or less carbon atoms is 20 to 70% by weight. A polypropylene resin molded article comprising a surface coating layer made of a composition containing ethylene / α-olefin copolymer rubber as a main component. 4. The polypropylene resin molded article according to claim 3, wherein the composition forming the surface coating layer further contains an inorganic filler. 5. The polypropylene resin molded product according to claim 3, wherein the recovered polypropylene resin molded product has a colored resin coating film.