JP2973353B2 - Powder resin composition used for powder 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 powder resin composition used for powder molding, and more particularly, to powder molding such as a fluid immersion method, an electrostatic coating method, a powder spraying method, a powder rotational molding method, and a powder slush molding method. The present invention relates to a powdery resin composition used for the above.

[0002]

2. Description of the Related Art As a powder molding method using a soft powder material, a powder slash molding method using a soft vinyl chloride resin powder is used for an instrument panel, a console box,
Widely used for the skin of car interior parts such as door trim. This is a soft touch, and can be provided with leather grain and stitches, and has good design properties such as a large degree of freedom in design.

However, in recent years, with the worsening of global environmental problems, vinyl chloride resins are being avoided as materials having a large environmental load. This is often misunderstood,
There are many problems such as the necessity of appropriate facilities for incineration, and the time and effort required for separation to avoid mixing with other materials when recycling materials.

Therefore, one method is disclosed in Japanese Patent Laid-Open No. 7-82.
No. 433, the weight ratio of a polypropylene resin to a specific styrene-based thermoplastic elastomer is 70/30 to 30.
It has been proposed to use a mixture mixed at a ratio of / 70 and pulverized. Here, a styrene-based thermoplastic elastomer is a styrene-ethylene-butylene-styrene block copolymer having a styrene content of 20% by weight or less, and a styrene content of 2%.
It is selected from styrene / ethylene propylene / styrene block copolymer of 0% by weight or less and hydrogenated styrene butadiene rubber of styrene content of 20% by weight or less, and has good compatibility with polypropylene resin and is suitable for powder molding. Composition.

[0005]

However, in this composition, the cold impact resistance is deteriorated when the amount of the polypropylene resin is increased and the formulation is set to be harder, and the gasoline resistance is decreased when the amount of the styrene-based thermoplastic elastomer is increased. In some cases, inconveniences such as deterioration of heat resistance when hot air heating was used occurred. The present invention is intended to solve such problems, and powders having excellent melt fluidity required for powder molding, particularly powder slush molding, and having improved cold shock resistance, gasoline resistance, and low-temperature brittle point are provided. An object is to provide a powder resin composition used for molding.

[0006]

That is, a feature of the present invention is that a polypropylene resin and a hydrogenated styrene resin are used.
80/20 to 2 by weight of tadiene random copolymer rubber
To 100 parts by weight in a mixing ratio of 0/80, ethylene
Ethylene-butylene-ethylene block copolymer
Powder resin used for powder molding obtained thermoplastic elastomers that possess ethylene <br/> emission units selected from styrene-octene block copolymer was ground in a mixing ratio of 5 to 50 parts by weight In the composition.

[0007] The present invention relates to a polypropylene resin,
Styrene butadiene having a hydrogen content of 20% by weight or less
Random copolymer rubber and thermoplastic with ethylene units
Ethylene / octene block copolymer as elastomer
Including, when the market using a mixture of the body.

The present invention also relates to a polypropylene resin and water
Thermoplastic elastomers that possess iodized styrene-butadiene random copolymer rubber and ethylene units was kneaded in a biaxial extruder or the like and pelletizing includes a case the pellet is a powder product obtained by refrigerating crushed.

The polypropylene resin used in the present invention comprises:
Either a polypropylene homopolymer or a block or random copolymer with an α-olefin may be used, but a block or random copolymer using ethylene as the α-olefin is particularly preferred from the viewpoint of the flexibility of the molded article. Further, in order to use the powder slush molding without applying pressure, the MFR (melt flow rate) measured at 230 ° C. under a load of 2.16 kgf according to JIS K7210 as an index of the melt fluidity of the polypropylene resin is 20 g / 10 min or more. It is necessary to be.

Further, a styrene-based thermoplastic elastomer and
In the present invention, a hydrogenated styrene-butadiene rubber (hydrogenated SBR) having a styrene content of 20% by weight or less is used.
It is.

[0011]

[0012] Hydrogenation SBR is in that styrene and butadiene are hydrogenated styrene-butadiene rubber are randomly copolymerized, a block copolymer styrene
Ethylene-butylene-styrene block copolymer (S
EBS) . A typical example is the Dynalon series, a product made by Nippon Synthetic Rubber Co., Ltd.

[0013] The styrene-based thermoplastic elastomer this M
The FR (230 °, 2.16 kgf) is preferably 10 or more, but if it is less than 10, it can be compensated to some extent by making other resins or elastomers highly fluid. Further, the mixing ratio of the polypropylene resin and the styrene-based thermoplastic elastomer (polypropylene resin / styrene-based thermoplastic elastomer) is 80/20 to 20/80 by weight, and if the weight ratio exceeds 80/20, the flexibility is impaired.
On the other hand, when the weight ratio is less than 20/80, the heat resistance and chemical resistance of the molded body are reduced.

In the present invention, as a thermoplastic elastomer having an ethylene unit, ethylene / ethylene / butylene / ethylene is used .
An ethylene block copolymer or an ethylene / octene block copolymer is used .

The ethylene / ethylene / butylene / ethylene block copolymer has the same soft segment as SEBS, but differs in that the hard segment is an ethylene crystal phase in place of styrene, and is expected to have improved gasoline resistance. . Further, although the compatibility with polypropylene is slightly inferior to that of hydrogenated SBR, improvement in cold shock resistance is expected.

The ethylene / octene block copolymer is
In general, the melting temperature of a single substance is 100 ° C. or less, and when added to a system of a polypropylene resin and a styrene-based thermoplastic elastomer, an effect of lowering the molding temperature and suppressing thermal degradation during molding of the styrene-based thermoplastic elastomer can be expected .

[0017]

[0018] MFR of the thermoplastic et <br/> Rasutoma over carrying these ethylene unit is preferably 10 or more, compensated to some extent by the high flow of another resin or elastomer used in combination may be less than this be able to. The amount of the thermoplastic elastomers that possess the ethylene unit, based on 100 parts by weight of a mixture of a polypropylene resin and a styrene-based thermoplastic elastomer, 5-5
0 parts by weight.

As the heat stabilizer, those used in ordinary polyolefins can be used. Generally, phenol and a phosphorus-based antioxidant are used in combination, but are not particularly limited. As the light stabilizer, a hindered amine or benzotriazole type radical scavenger may be used. Organic and inorganic pigments suitable for ordinary olefins are used. Further, a lubricant such as a fatty acid metal salt and a filler such as calcium carbonate and talc are added as required.

The mixture of these compounds is mixed in a V-type blender,
This is performed using a tumbler, Henschel mixer or the like.
Next, the mixture is melt-kneaded by a twin-screw extruder or the like and pelletized. These pellets are finely pulverized using an impact type fine pulverizer such as a turbo mill, a pin mill, and a hammer mill. At this time, it is usually frozen and pulverized using liquid nitrogen . The pulverized particles having a particle size of at least 500 μm or less, preferably 300 μm or less are collected by sieving or the like, and those having a particle size exceeding 500 μm are pulverized again.

When the thus obtained powder resin composition used for powder molding does not have sufficient powder flowability, the sheet having defects or pinholes without flowing into the complicated shape portion of the mold is used. Will be molded. Therefore, in the present invention, in particular, a filler such as calcium carbonate or silica as a fluidity improver, or a lubricant such as a fatty acid metal salt such as zinc stearate or calcium stearate, a fatty acid amide, or a fatty acid ester in the powder resin composition. Alternatively, fine resin powder or the like can be added. The filler remains without being melted during powder slush molding, but the lubricant and the resin fine powder are melted and taken into the powdered resin composition. These fluidity improvers are added by a mixer such as a Henschel mixer after crushing the pellets, but may be crushed by crushing the pellets before crushing.

These additives adhere to the surface of the powdered resin composition and act as a roller, thereby improving the fluidity of the powder. However, if the above-mentioned additives are added in a large amount, the mechanical properties of the sheet molded body are reduced. Therefore, the amount of the filler and the lubricant is 2 parts per 100 parts by weight of the mixture of the polypropylene resin and the styrene-based thermoplastic elastomer.
Less than 10 parts by weight of the resin fine powder. The resin fine powder is an olefin-based resin having excellent compatibility with the powdered resin composition, and particularly suitable is a low-density polyethylene chemical pulverized product. Chemical pulverization involves dissolving a resin in a solvent and introducing the resin into an insoluble solvent to precipitate the resin. Finer particles can be obtained than in mechanical pulverization.

Next, powder slush molding is performed using the powdered resin composition having the adjusted fluidity. In this molding, the powdered resin composition is dropped into a mold heated above the melting point of the powdered resin composition mainly by gravity, and after a certain period of time, the mold is inverted and excess powdered resin composition is collected in a collection box. The powder resin composition adheres as a layer to the mold surface, and melts over time to form a skin layer. Then, the mold is cooled to remove the skin layer, and this is repeatedly performed.

The method of heating the mold is generally a method of circulating oil or putting it into a hot blast stove. Oil circulation is easy to adjust the mold temperature by pipe arrangement, but is heated only from the mold surface. On the other hand, when a hot blast stove is used, heating can be performed from both sides of the mold surface and the back surface of the molded product. It is necessary to consider the prescription and conditions so as not to cause oxidative deterioration. The hot air method is effective when performing powder slush molding in multiple layers (two or three).
That is, the first powder to be the outermost layer is slush-molded in a heated mold, and the second powder is adhered in a semi-molten state,
Then, if necessary, slush molding is performed a third time, and then, heat melting is performed. In this case, if the heating is performed only from the mold surface side, the heat transfer is insufficient, so that a hot blast stove method capable of heating from the back surface of the molded product is often used.

[0025]

Next, the present invention will be described in more detail with reference to specific examples. Examples 1 and 2 XK0286 (manufactured by Chisso Corporation, as a polypropylene resin)
Random copolymer with ethylene, MFR27g / 10
62.5 parts by weight and Dynaron 1321P as hydrogenated SBR (manufactured by Nippon Synthetic Rubber Co., Ltd., styrene content 10% by weight, MFR 10 g / 10 minutes, JIS hardness 39)
Ethylene / ethylene butylene / ethylene block copolymer (Dynalon 6200P, manufactured by Nippon Synthetic Rubber Co., MFR 2.5 g / 10 min, JIS hardness 63) as a thermoplastic elastomer having ethylene units in 5 parts by weight, ethylene octene block Copolymer (Engage SM84
00, Dow Chemical Company, MFR 30g / 10min, JI
S hardness 67 ) 25 parts by weight, and A060 as a heat stabilizer
(Adeka, hindered phenol) 0.25 parts by weight and PEP36 (Adeka, phosphorus-based secondary antioxidant)
0.25 parts by weight was mixed with a tumbler and extruded at 200 ° C. into a pellet using a twin-screw extruder (PCM45, manufactured by Ikegai Iron and Steel). And Turbo Mill T250-4J
The pellets immersed in liquid nitrogen were put into (Turbo Kogyo Co., Ltd.) and pulverized to collect only the 500 μm sieve.

Next, powder slush molding was performed using the above powdered resin composition. As a method of the powder slush molding, first, an electroforming mold (150 mm × 150 mm × 2 m
m) was preheated in an oven heated to 300 ° C., taken out of the oven, and when the mold temperature reached 250 ° C., 300 g of the powdered resin composition was dropped at one time to cover the mold surface. After standing for 10 seconds, the mold was inverted to remove excess powder, the mold was returned to the oven and cured for 90 seconds, then the mold was taken out of the oven, quenched in water, and the sheet was demolded. . The thickness of the sheet was about 1 mm.

The MFR of the above pellets, the melting start temperature of the pulverized material, the hardness, tensile strength, elongation, low-temperature brittle point, and gasoline resistance of the molded sheet were evaluated by the following methods. Table 1 shows the obtained results. MFR uses pellets according to JIS K7
It was measured at 210 ° C. under a load of 2.16 kgf with a 210. While observing the melting start temperature of the pulverized product with a microscope (magnification: 50 times), the temperature at which the powder molded product was heated on a thin glass plate at 5 ° C./min and melted to measure the temperature at which the shape began to become round was measured. The hardness was measured by a JISA hardness tester by stacking six sheets obtained by slush molding.

The tensile strength and elongation were measured by punching a sheet obtained by slush molding with a JIS No. 3 dumbbell at a tensile speed of 200 mm / min. The low-temperature embrittlement point was determined by punching a sheet obtained by slush molding into a JIS K7216A-type test piece and measuring the 5% of the test piece in accordance with JIS K7216.
It was determined at a temperature at which 0% breakdown occurred. For gasoline resistance, one drop of gasoline was dropped on a sheet obtained by slush molding with a spoid, and after 3 hours, it was wiped off with a cloth to determine the presence or absence of spots.

COMPARATIVE EXAMPLE 1 Except for the ethylene / ethylene / butylene / ethylene block copolymer of Example 1, Dynalon 1321P was replaced with 62.5%
A powdered resin composition was prepared and evaluated, except that it was used in parts by weight. Table 1 shows the results.

Reference Example 1 Dinalon 1321P of Comparative Example 1 was replaced with Dynalon 6200
Comparative Example 1 was the same as Comparative Example 1 except that P was changed to 62.5 parts by weight. A powdered resin composition was prepared and evaluated. Table 1 shows the results.

REFERENCE EXAMPLE 2 Dynalon 1321P of Comparative Example 1 was replaced with Engage SM84.
The same procedure as in Comparative Example 1 was carried out except that the powder slush molding oven temperature was changed to 280 ° C. and the mold temperature was changed to 230 ° C. instead of 62.5 parts by weight.
The evaluation was performed. Table 1 shows the results.

Reference Example 3 Dinalon 1321P of Comparative Example 1 was replaced with ethylene propylene
Random copolymer (EP02P, manufactured by Nippon Synthetic Rubber Co., Ltd.
MFR 3.2 g / 10 min, JIS hardness 55) The procedure was the same as that of Comparative Example 1 except that the weight was changed to 62.5 parts by weight. A powdered resin composition was prepared and evaluated. Table 1 shows the results.

[0033]

[Table 1]

From these results, it is understood that the powder resin composition of the present embodiment has good melt fluidity, and that the sheet obtained by slush molding is also rich in flexibility, and is excellent in tensile strength, elongation and low-temperature brittle point. Also, the gasoline resistance is good.

[0035]

As described above, in the present invention, the thermoplastic elastomer having an ethylene unit alone does not have good compatibility with the polypropylene resin, but is one of the styrene-based thermoplastic elastomers having good compatibility with the polypropylene resin. By substituting the parts, the low temperature brittle point is improved.
In addition, ethylene / octene block copolymer is effective in lowering the molding temperature, and
Ethylene block copolymer is effective in improving gasoline resistance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 53/00 C08L 53/00 (72) Inventor Kazuki Sakai 4-1-1, Hamazoe-dori, Nagata-ku, Kobe Mitsuboshi Belting, Ltd. (72) Inventor Kenro Ono 4-1-1-21 Hamazoedori, Nagata-ku, Kobe Mitsuboshi Belting Co., Ltd. (56) References JP-A-10-30036 (JP, A) JP-A-7-96529 (JP) , A) JP-A-7-173366 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 23/00-23/16 C08L 9/00-9/10 C08L 53/00 -53/02 C08J 3/12 B29C 41/18

Claims (3)

(57) [Claims] 1. A polypropylene resin and hydrogenated styrene
Butadiene random copolymer rubber with a weight ratio of 80/20 to
To 100 parts by weight in a mixing ratio of 20/80, ethyl
Len / ethylene butylene / ethylene block copolymer,
And wherein the thermoplastic elastomers that possess ethylene <br/> lens units selected from ethylene octene block copolymer is obtained by grinding in a mixing ratio of 5 to 50 parts by weight Powder resin composition used for powder molding. 2. A polypropylene resin having a styrene content of 2
0% by weight or less of hydrogenated styrene butadiene random
Polymerized rubber and thermoplastic elastomer containing ethylene units
Ethylene-octene block copolymer
The powder molding according to claim 1, wherein the powder molding is used.
Powder resin composition used for 3. Polypropylene resin and hydrogenated styrene
Butadiene random copolymer rubber, and the thermoplastic elastomers that possess ethylene units was kneaded in a biaxial extruder or the like pelletized powder of claim 1, wherein the pellet is a powder product obtained by refrigeration pulverization Powder resin composition used for molding.