KR101926958B1 - Manufacturing method of non-paint injection molding products having excellent scratch-resistance and fouling resistance, and crash pad prepared thereby - Google Patents

Abstract

The present invention relates to a method of manufacturing a non-cast injection molded article having improved scratch resistance and stain resistance, and a crash pad manufactured by the method. More particularly, the present invention relates to a method of forming an emboss having fine pores capable of improving stain resistance and photo- , A coating film containing thin and uniform carbon nanotubes is formed, and a plastic material which is resistant to gloss reduction, scratch resistance and stain resistance is injection-molded to produce a non-cast injection molded article improved in scratch resistance and stain resistance To a crash pad as an injection molded article produced thereby.

Description

Technical Field [0001] The present invention relates to a method of manufacturing a non-cast injection molded article having improved scratch resistance and stain resistance, and a crash pad manufactured thereby,

The present invention relates to a method for manufacturing a non-cast injection molded article having improved scratch resistance and stain resistance, and a crash pad manufactured by the method, more specifically forming an emboss having micro pores capable of improving stain resistance and gloss reduction on an injection mold surface , A coating film containing thin and uniform carbon nanotubes is formed, and a plastic material which is resistant to gloss reduction, scratch resistance and stain resistance is injection-molded to produce a non-cast injection molded article improved in scratch resistance and stain resistance To a crash pad as an injection molded article produced thereby.

Generally, a crash pad is installed inside the front of a driver's seat and a passenger's seat to protect passengers when a passenger collides due to an accident.

Conventional crash pads were surface treated by adding a separate process to improve the appearance quality. However, such a surface treatment had a problem of rising costs, and environmental problems caused by VOCs also appeared.

Accordingly, there is a need to provide a method for producing a non-coated injection molded article which satisfies mechanical properties and appearance quality, and has improved scratch resistance and stain resistance.

1: Korean Patent No. 10-1592794

Accordingly, the present inventors have found that embossing with fine pores capable of improving stain resistance and gloss reduction on the surface of an injection mold, increasing the transferability of the emboss in the injection mold, improving the durability, and achieving a thin and uniform coating film, Using a polypropylene resin composition which is resistant to gloss reduction, scratch resistance, and stain resistance including a predetermined amount of polypropylene resin, ethylene -? - olefin copolymer and inorganic filler by using a coating composition containing a tube, It has been found that when a pad is produced, it is excellent in low gloss, scratch resistance, stain resistance, and mechanical properties, thereby completing the present invention.

Accordingly, an object of the present invention is to provide a method of manufacturing a non-coated injection molded article having improved scratch resistance and stain resistance.

Another object of the present invention is to provide an unpainted crash pad which is an injection molded product manufactured by the above method.

According to an aspect of the present invention, there is provided a method of manufacturing an injection mold, comprising the steps of: (i) attaching an ultraviolet curing ink film manufactured by a screen printing method to the surface of an injection mold and etching it with an acid to form an emboss; (Ii) attaching a wax ink film manufactured by a nozzle printing method to the surface of the injection mold on which the embossing is formed, and etching it with an acid to form fine pores; (Iii) coating a coating composition containing carbon nanotubes on an injection mold having embossed and fine pores by a spray coating method; And (iv) a step of injection-molding a polypropylene resin composition into an injection mold of the step (iii) to produce a molded article, and a method of manufacturing the unpatterned injection molded article with improved stain resistance do.

The present invention also provides a mattress crush pad manufactured by the above manufacturing method, which is a molded article improved in scratch resistance and stain resistance.

The method for manufacturing a non-coated injection molded article according to the present invention can improve the scratch resistance and stain resistance on the surface of a non-coated injection molded article, thereby improving the secondary problems caused by the interior material damage and contaminants.

In addition, the automotive crash pad, which is an injection molded product manufactured according to the present invention, can improve the quality of the appearance without any additional surface treatment, thereby optimizing the cost and advantage of cost reduction.

Fig. 1 shows an ultraviolet curing ink film (a) produced by a screen printing method used for embossing and a waxing ink film (b) produced by a nozzle printing method used for forming fine pores.
Fig. 2 shows a conventional embossed shape of Comparative Example 1 (left), and embossing formation (right side) in which fine pores are formed according to the present invention of Example 1; Fig.
FIG. 3 is a SEM photograph (left) of the injection mold having the embossing formed thereon and shows the SEM photograph (right) of the injection mold having embossed and meso pores.
Fig. 4 shows a state (a) in which contaminants are whitewashed in a section of the emboss without micro pores formed therein, and Fig. 4 (b) shows a state in which no contaminants are trapped in the section of the emboss with micro pores formed therein.
5 shows SEM photographs of the injection molds before and after the coating process according to the present invention.
6 shows a process of (iii) coating a coating composition containing carbon nanotubes according to the present invention by a spray coating method.
Figure 7 shows the surface of the mold after the coating step (iii) according to the invention, with black or dark gray coated surfaces.

Hereinafter, the present invention will be described in more detail as an embodiment.

The present invention relates to a process for producing an unpainted injection molded article improved in scratch resistance and stain resistance by forming an emboss having fine pores capable of improving stain resistance and gloss reduction on the surface of an injection mold, A coating composition containing carbon nanotubes capable of enhancing durability and realizing a thin and uniform coating film is coated by a spraying method and then coated with a polypropylene resin composition resistant to gloss reduction, scratch resistance and stain resistance, Thereby producing an injection molded article.

More specifically, in the present invention, a method for producing a non-coated injection molded article having improved scratch resistance and stain resistance is largely divided into four steps. Each step will be described in detail below.

(I) Step: Injection mold Embo  Forming step

First, in order to form an emboss on the surface of an injection mold, the present invention is etched using a chemical agent. Typically, in the present invention, an ultraviolet curable ink film produced by a screen printing method is adhered to the surface of an injection mold and an acid is etched to form an emboss (i).

A method of printing a masking film necessary for processing an embossed shape on a mold surface by a chemical etching method can realize a fine shape when a film is printed using a wax jet printer having excellent transferability and acid resistance.

The step (i) according to the present invention is a conventional printing method using an ultraviolet curable ink film. Since the printing level of a fine pattern can be realized to at least 0.13 mm, it is difficult to produce a more delicate and fine patterned film. 1 (a) shows the appearance of an ultraviolet curing ink film produced by a screen printing method used for embossing.

In this way, the surface shape of the injection mold surface is made by using chemical agent before the plastic injection molding. This not only reduces the design effect of the product, but also reduces the width of gloss variation according to the injection condition, GU As well. In this way, while embossed on the finished product gives a positive effect, there is also a negative effect produced by embossing. When the injection molded article is taken out, scratches may be caused and the surface staining may be increased.

(Ii) Step: Embo  Step of forming fine pores

In order to improve the negative effects of the prior art, the present invention includes a step (ii) of forming a fine pore by attaching a wax ink film manufactured by a nozzle printing method to the surface of an injection mold having an embossing formed thereon and etching it with an acid . FIG. 1 (b) shows a wax ink film produced by a nozzle printing method used for fine pore formation. When an injection mold is etched using a wax ink type nozzle-type printing method using a wax jet printer, it is possible to pattern at a minimum level of 0.06 mm smaller than the above (i), thereby forming micro pores in the emboss can do.

When the step (ii) is carried out, the corners of the hill portion of the emboss formed in the step (i) may be rounded to improve the scratch resistance by raising the round value. In addition, fine pores are formed on the embossed surface to reduce the contamination area, thereby ultimately improving the stain resistance and reducing the gloss.

FIG. 2 shows a conventional embossed shape (left) and shows an embossing formation (right side) in which fine pores are formed according to the present invention. FIG. 3 shows SEM photographs (right side) of the injection mold having embossed and fine pores formed through step (ii), and it can be confirmed that embossed and fine pores are well formed.

Fig. 4 shows a state (a) in which contaminants are whitewashed by the end face of the emboss without fine pores formed therein, and Fig. 4 (b) shows a state in which no contaminants are trapped by the end face of the embossed pores. The effect of increasing the degree of contamination due to the formation of fine pores in the injection molded article can be given.

(Iii) Step: Transferability  For increased and durability Coating film  Forming step

In order to increase the transferability of micropores on the inner embossed surface of the injection mold to increase the stain resistance and scratch resistance, the present invention uses a spray coating method to coat the coating composition containing carbon nanotubes Iii). This can improve appearance quality problems (gas mark, ghost mark, flow mark, micro scratch) by improving the material flowability by the inner coating film of the injection mold.

FIG. 5 shows SEM photographs of the injection molds before and after the coating process according to the present invention. When the coating according to the present invention is performed, the embossing property is increased, and the fine pore shape plays a normal role. As shown in FIG.

More specifically, in the case of the coating according to the present invention, the step (ii ') of pretreating the surface of the injection mold by the sand blast method, the step (ii' ') of masking the remaining part except the surface to be coated, (Iii) coating a coating composition containing carbon nanotubes on the formed injection mold by a spray coating method, and (iii ') drying the coated injection mold.

Conventional coating technology is coated by using PVD / CVD method. However, since coating according to the present invention is a technique to form a coating film on a mold at a lower cost than a conventional coating technique, the efficiency is also excellent.

 Conventional coating techniques have expensive coating equipment and are limited in size of the mold depending on the size of the vacuum equipment. However, the spray coating method according to the present invention is inexpensive and simple compared with the conventional coating technique and is limited to the size and shape of the mold A broader range of coating implementations is possible.

However, it is obvious that it is difficult to realize a thin and uniform coating film which has been pointed out as a problem of spray coating method, and that the durability of the coating film is inferior.

In order to overcome such limitations, the present invention employs a coating composition comprising an acrylic polymer and a carbon nanotube (CNT), and preferably a carbon nanotube in an amount of 10 to 40 wt% based on the total weight of the coating composition . When the carbon nanotube is less than 10 wt%, the coating film has a limited durability. When the carbon nanotube is more than 40 wt%, the coating material may not be smoothly dispersed.

More specifically, in the present invention, an acrylic polymer mixture is basically used for excellent adhesion of an injection mold and a coating material. The acrylic polymer mixture may include a compound selected from polymethyl methacrylate (PMMA), polyimide, hexamethyldisiloxane, polysiloxane, and glycidyl methacrylate, or a mixture thereof.

Further, in order to improve the mechanical properties (hardness, heat resistance, etc.) of the coating material, carbon nanotube (CNT) materials are mixed with the polymer to improve heat resistance up to 400 DEG C when the conventional heat resistance is 250 DEG C or less . In addition, the mechanical strength of the carbon nanotubes itself is added to increase the hardness of the coating material itself.

The average particle size of the carbon nanotubes used in the process of polymerizing the coating material is preferably 40 to 200 nm. When the thickness is less than 40 nm, surface gloss control is limited. When the thickness is more than 200 nm, the surface friction coefficient is increased, and there is a limit to adversely affect the injection speed.

In spray coating, it is preferable to adjust the spray amount of the coating composition to a level of 10 to 30 ml / mTorr in order to form a thin and uniform coating film.

6 shows a process of (iii) coating a coating composition containing carbon nanotubes according to the present invention by a spray coating method.

More specifically, the coating process disperses the coating composition according to the present invention in a solvent at a ratio of 5 to 6: 4 to 5. First, put the solvent into the container and add the coating material. Place the container in an ultrasonic dishwasher and disperse it at a constant rate for a certain period of time, then seal it in a vial containing no light. When coating, mix coating agent and catalyst of reagent bottle in proper ratio and put in spray nozzle to coat. The spraying pressure during coating is variable depending on the shape and structure of the mold, but it should not exceed 2 MPa at maximum. And preferably 1.5 to 2 Mpa.

In addition, the distance between the mold and the spray gun is maintained at 30 to 50 cm, depending on the shape of the mold, and repeatedly coated at the same speed and injection rate. Also, in order to confirm the uniform thickness of the coating film, the color difference value and the glossiness of the coating film are periodically measured to confirm the uniformity of the coating film. Since the gloss of the coating film is transferred even to the surface gloss of the product, it is also necessary to set the target gloss and prepare a coating composition suitable for the target gloss. When the uniformity of the coating film is different, the uniformity of the coating film is important because the glossiness is differently realized. Basically, the thicker the coating film, the higher the glossiness.

In addition, a gloss reducing agent (fine particle) may be mixed with the coating material as necessary to adjust the gloss of the coating film. In addition, the surface of automobile plastic injection mold is mostly patterned, so that the thickness of coating film is limited to 10 ㎛ maximum to prevent the coating film from losing pattern. More preferably 5 to 6 占 퐉. The thickness of the coating film can be measured by using a film thickness measuring device generally used, but it is difficult to measure the thickness when the surface of the injection mold is patterned.

In order to completely cure the film, the coated injection mold is cured in a room set at a temperature of 20 ° C or less at room humidity of 30% or less. If necessary, curing can be carried out through heat treatment, but unreasonable curing process may cause the durability of the coating film to be deteriorated, so that natural curing is performed basically.

The injection mold coated with this process has a considerably high adhesion between the injection mold and the coated carbon nanotube thin film, so that peeling of the coating film during use can be minimized.

In addition, unlike other mold coating methods, when the surface of a mold is damaged, it is possible to remove the coating film from the surface of the mold by a sand blast method and then re-coat the same, thereby facilitating maintenance and repairing of the mold.

In addition, the carbon nanotube coating film is colored black or dark gray when it is coated on the mold, which is a characteristic color of the carbon nanotube. When the thin film of the coating is broken, the carbon nanotube coating is very visible on the mold, (See FIG. 7).

(Iv) Step: injection molding step

In the present invention, a plastic material is used for improving gloss reduction, scratch resistance and stain resistance. More specifically, the present invention carries out the step (iv) of producing a molded article by injection molding the polypropylene resin composition into the injection mold of the step (iii).

Wherein the polypropylene resin composition comprises (a) 50 to 70% by weight of at least one polypropylene resin selected from the group consisting of highly crystalline homopolypropylene and highly crystalline propylene-ethylene copolymer, (b) an ethylene /? - olefin copolymer 20 to 49% by weight; And (c) 1 to 20% by weight of an inorganic filler.

First, the polypropylene resin is used for improving scratch resistance and moldability, and it is preferable to use 50 to 70% by weight based on the total weight of the polypropylene resin composition. If the content of the polypropylene resin is less than 50% by weight, the overall physical properties of the molded article may deteriorate. If the amount exceeds 70% by weight, the amount of other compositions may be too small to cause other problems.

The polypropylene resin may be at least one selected from the group consisting of highly crystalline homopolypropylene and highly crystalline propylene-ethylene copolymer. Since the impact resistance and surface luster of a molded article may be deteriorated, It is preferable to mix them.

More specifically, the highly crystalline homopolypropylene has an isotacticity index of 97.5 to 99.5% as measured by C13-NMR, and a melt index of 0.5 to 100 g / 10 min (2.16 kg, 230 DEG C) is preferably used. If the isotactic index is out of the above range, the scratch resistance of the molded article may deteriorate. In addition, it is advantageous in terms of moldability to use a resin having a melt index within the above range.

In addition, the highly crystalline propylene-ethylene copolymer preferably contains 1 to 50% by weight of ethylene and 50 to 99% by weight of propylene based on the total weight of the propylene-ethylene copolymer. If the content of propylene deviates from the above range, the mechanical properties of the molded article may deteriorate. In addition, the amount of ethylene used is a relative value determined by the propylene content.

In addition, it is preferable to use a highly crystalline propylene-ethylene copolymer having a melt index of 0.5 to 100 g / 10 min (2.16 kg, 230 DEG C). If the isotactic index of the isotactic index is less than 97%, the stiffness and surface hardness of the molded article may be insufficient for use in automobile interior materials. If the melt index is less than 0.5 g / 10 min (2.16 Kg, 230 ° C) The moldability may be deteriorated. If the melt index exceeds 100 g / 10 min (2.16 Kg, 230 ° C), the impact resistance of the molded product may be remarkably lowered.

When high crystallinity homopolypropylene and highly crystalline propylene-ethylene copolymer are mixed, it is preferable to mix them at a weight ratio of 3 to 4: 6 to 7.

Next, the ethylene -? - olefin copolymer (b) is used for reducing gloss and securing mechanical properties, and preferably has a Mooney viscosity of 5 to 60ML1 + 4 (121 ° C). This is because having a Mooney viscosity within the above range is advantageous in realizing mechanical properties. The ethylene /? - olefin copolymer preferably has a glass transition temperature of -65 to -50 占 폚. When a glass transition temperature of less than -65 占 폚 is used, the rigidity and heat resistance of the molded article may be deteriorated, If it is used at a temperature higher than -50 ° C, the low-temperature impact resistance may be deteriorated, so that it is preferable to have a glass transition temperature within the above range.

In addition, the inorganic filler (c) in the present invention serves to reinforce the rigidity of the molded article, and it is preferable to use 1 to 20% by weight based on the total weight of the polypropylene resin composition. More preferably 5 to 15% by weight. If the amount of the inorganic filler is less than 1% by weight, the rigidity of the molded article may be deteriorated. If the inorganic filler is used in an amount exceeding 20% by weight, the amount of other compositions to be used may be relatively decreased, causing other problems, It is good to use.

The inorganic filler in the present invention is preferably a plate-shaped fine talc having an average particle size of 0.5 to 5 占 퐉 or a whisker having an average particle size of 10 to 15 占 퐉 or a mixture thereof. If the average particle size of the talc is less than 0.5 탆, the productivity of the molded product may deteriorate. If the talc has an average particle size exceeding 5 탆, the overall mechanical properties of the molded product may be deteriorated. good. In addition, whiskers having an average particle size of less than 10 mu m are poor in mechanical properties, and those having a mean particle size within the above range may be used if products having an average particle size exceeding 15 mu m are used.

In addition to the fine talc, it is preferable to use at least one selected from the group consisting of olustonite, barium sulfate, calcium carbonate, silica, mica, calcium silicate, magnesium whisker and glass fiber.

The polypropylene resin composition according to the present invention improves gloss reduction, scratch resistance and stain resistance, and is particularly suitable as an injection molded article of an automobile crash pad.

As described above, the present invention provides a method for manufacturing a carbon nanotube, which comprises forming an embossing with fine pores capable of improving stain resistance and gloss reduction on the surface of an injection mold, forming a coating film containing thin and uniform carbon nanotubes, And injection-molded plastic materials resistant to stain resistance, it is possible to provide unpainted injection molded articles improved in scratch resistance and stain resistance, and the cost can be reduced by improving the appearance quality without any additional surface treatment of the molded article.

Hereinafter, the present invention will be described in more detail with reference to examples. However, these examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1: Manufacturing using an injection mold having embossed and fine pores

An ultraviolet curable ink film prepared by a screen printing method was adhered to the surface of the injection mold and etched with an acid to form an emboss (step (i)). Next, a wax ink film produced by a nozzle printing method is attached to the surface of the injection mold having the embossing formed thereon, and etching is performed with acid to form fine pores (step (ii)).

Next, 60 to 90% by weight of a compound selected from polymethyl methacrylate (PMMA), polyimide, hexamethyldisiloxane, polysiloxane, and glycidyl methacrylate, or a mixture thereof, and 10 to 40 wt% %) Was spray-coated at an injection pressure of 2 MPa and a distance of 30 to 50 cm to prepare an injection mold (step (iii)).

Finally, a homogeneous propylene-ethylene copolymer (25% by weight of ethylene and 75% by weight of propylene) was mixed with high crystallinity homopolypropylene (isotactic index of 98%, melt index of 50 g / Olefin copolymer having a melt viscosity of 60 g / 10 min (2.16 Kg, 230 ° C) at a weight ratio of 2: 8 of 70% by weight and an ethylene- ), 10% by weight of a platelet-shaped fine talc (talc) having an average particle size of 3 占 퐉 and a 20% by weight glass transition temperature of -60 占 폚 were injected into the injection mold, .

Comparative Example 1: Production using an injection mold formed with embossing

An ultraviolet curing ink film manufactured by a screen printing method was attached to the surface of the injection mold and etched with an acid to form an emboss. Next, an embossed injection mold is sprayed with a coating composition comprising 100 wt% of a compound selected from polymethyl methacrylate (PMMA), polyimide, hexamethyldisiloxane, polysiloxane, glycidyl methacrylate, or a mixture thereof An injection mold was prepared by spray coating at a pressure of 2 MPa and a distance of 30-50 cm.

Finally, a homogeneous propylene-ethylene copolymer (25% by weight of ethylene and 75% by weight of propylene) was mixed with high crystallinity homopolypropylene (isotactic index of 98%, melt index of 50 g / Olefin copolymer having a melt viscosity of 60 g / 10 min (2.16 Kg, 230 ° C) at a weight ratio of 2: 8 of 70% by weight and an ethylene- ), 10% by weight of a platelet-shaped fine talc (talc) having an average particle size of 3 占 퐉 and a 20% by weight glass transition temperature of -60 占 폚 were injected into the injection mold, .

Experimental Example: Measurement of Physical Properties of Specimen

The properties of the specimens prepared according to Example 1 and Comparative Examples 1 and 2 were measured using the following test methods and the physical properties thereof are shown in Table 2.

(1) Gloss measurement: Measured using a Gardner gloss meter.

(2) Measurement of scratch resistance: Measured by MS 210-05 standard.

(3) Measurement of stain resistance: Measured by the MS 210-05 standard.

Physical property measurement result division Glossiness Scratch resistance Stain resistance Reference value
(Target value) 1.8 - 2.4
± 0.2 GU ? 1.2 or less △ 2.0 or less Example 1 2.2 G.U. 0.6 1.7 Comparative Example 1 2.2 G.U. 1.0 △ 2.2

As shown in Table 1, in the case of Example 1 according to the present invention, it was confirmed that both the scratch resistance and stain resistance were satisfied when the sample had the same gloss. However, in Comparative Example 1 in which fine pores were not formed, the scratch resistance was satisfactory but the stain resistance was not satisfied.

Therefore, when embossing with fine pores on the surface of an injection mold according to the present invention, forming a coating film containing carbon nanotubes and then injection molding a plastic material, the scratch resistance, stain resistance, and mechanical properties It is possible to manufacture a non-cast injection molded article which can be satisfactorily satisfied, and this can be widely applied particularly to the manufacture of automobile crash pads.

Claims (13)

(I) attaching a patterned ultraviolet curing ink film manufactured by a screen printing method to the surface of an injection mold and etching it with an acid to form an emboss;
(Ii) attaching a patterned waxing ink film, which is manufactured by a nozzle printing method, to the surface of an injection mold having an embossed shape and etching it with an acid to form fine pores;
(Iii) coating a coating composition containing carbon nanotubes on an injection mold having embossed and fine pores by a spray coating method; And
(Iv) preparing a molded article by injection molding a polypropylene resin composition into an injection mold of the step (iii);
Wherein the method comprises the steps of: preparing a non-coated injection molded article having improved scratch resistance and stain resistance.
The method according to claim 1, further comprising the step (ii ') of pre-treating the surface of the injection mold by a sandblast method after the step (ii) is further performed. Way.
The method according to claim 1, wherein in the step (iii), the coating composition comprises an acrylic polymer and a carbon nanotube (CNT), and the carbon nanotube comprises 10 to 40 wt% Wherein the method comprises the steps of: preparing a non-coated injection molded article having improved scratch resistance and stain resistance;
The acrylic polymer according to claim 3, wherein the acrylic polymer is a compound selected from polymethyl methacrylate (PMMA), polyimide, hexamethyldisiloxane, polysiloxane, and glycidyl methacrylate, or a mixture thereof. And a method of manufacturing the unpainted injection molded article improved in stain resistance.
The method of claim 1, wherein the carbon nanotubes have an average particle size of 40 to 200 nm.
The method according to claim 1, wherein the spraying pressure in spray coating in (iii) is 1.5 to 2 MPa, and the spacing distance between the mold and the spray gun is within a range of 30 to 50 cm. A method of manufacturing an unpainted injection molded article.
The method according to claim 1, further comprising the step (iii ') of drying the coated injection mold after the step (iii).
The polypropylene resin composition according to claim 1, wherein the polypropylene resin composition of the step (iv)
(a) from 50 to 70% by weight of at least one polypropylene resin selected from the group consisting of high crystalline homopolypropylene, and highly crystalline propylene-ethylene copolymers;
(b) 20 to 49% by weight of an ethylene -? - olefin copolymer; And
(c) 1 to 20% by weight of an inorganic filler;
Wherein the method comprises the steps of: preparing a non-coated injection molded article having improved scratch resistance and stain resistance.
The method of claim 8, wherein the highly crystalline homopolypropylene has an isotacticity index of 97.5 to 99.5% measured by C13-NMR and a melt index of 0.5 to 100 g / 10 min (2.16 kg, 230 DEG C) Wherein the scratch resistance and stain resistance of the non-coated injection molded article are improved.
9. The process of claim 8, wherein the highly crystalline propylene-ethylene copolymer comprises from 1 to 50% by weight of ethylene and from 50 to 99% by weight of propylene, based on the total weight of the propylene- Min. (2.16 kg, 230 DEG C). The method according to claim 1, wherein the non-coated injection molded article has an improved scratch resistance and stain resistance.
The ethylene /? - olefin copolymer (b) according to claim 8, wherein the ethylene /? - olefin copolymer (b) has a Mooney viscosity of 5 to 60ML1 + 4 (121 ° C) and a glass transition temperature of -65 to -50 ° C Wherein the scratch resistance and stain resistance of the non-coated injection molded article are improved.
The inorganic filler (c) according to claim 8, wherein the inorganic filler (c) is a plate-shaped micro talc having an average particle size of 0.5 to 5 占 퐉 or a whisker having an average particle size of 10 to 15 占 퐉 or a mixture thereof A method for manufacturing a unpainted injection molded article improved in scratch resistance and stain resistance.
13. A unpainted crash pad produced by the method of any one of claims 1 to 12, wherein the molded article is improved in scratch resistance and stain resistance.

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