JP4714603B2 - Polypropylene resin composition and molded product thereof - Google Patents

Description

  The present invention relates to a polypropylene resin composition containing talc and a molded product thereof, and more particularly to a polypropylene resin composition containing degassed compressed talc having improved dispersibility and excellent mechanical properties, and a molded product thereof.

In recent years, industrial parts such as bumpers, instrument panels, door trims, pillar trims, air conditioner cases, lamp housings, and other automotive parts are polypropylene-based blends of inorganic fillers such as talc and elastomers due to their excellent physical property balance and moldability. Many composite materials are used.
Generally, these polypropylene-based composite materials are manufactured by melting and kneading a polypropylene resin as a raw material and an inorganic filler powder such as talc with a biaxial kneader.
Recently, from the environmental protection point of view to promote energy saving and the economic point of view to reduce manufacturing costs, the movement to adopt the so-called in-line compound process that performs these melt-kneading processes in a consistent process starting from the polymerization reaction of propylene. There is.

However, when performing melt-kneading, if there is a lot of air entrained in the inorganic filler powder in the kneader, for example, even if pressure is applied from the hopper side of the kneader toward the outlet, the internal volume of the air changes. Thus, the pressure is absorbed and there is a problem that this air pressure does not work effectively as a resin pressure toward the outlet of the extruder. As means for solving this, it has been proposed to compress and deaerate inorganic fillers (see, for example, Patent Document 1). Further, a technique relating to an inline compound process in which a specific compression talc is used and an inline compound is formed using an apparatus in which a polymerization apparatus and a kneading and granulating apparatus are continuously formed is disclosed (for example, Patent Documents). 2).
Patent Document 1 discloses a degassed compressed talc having a compression ratio exceeding 3.0, and an effect that the dispersion state of talc is improved by melt kneading with a propylene resin using the talc. The kneader used in Japan (CIM-90 manufactured by Nippon Steel Works Co., Ltd.) has a screw diameter of about 90 mm and has a poor kneading force used in recent enlargement facilities such as in-line compounds (for example, In Patent Document 2, a screw having a screw diameter of 320 mm is used), and it cannot be said that talc is dispersed to a desired state.
Further, in Patent Document 2, the number of test pieces in which “white spots” due to the aggregates of inorganic fillers occurred was measured in the Examples (see “Appearance” in Table 1). When the compression ratio of the inorganic filler, which is the technical feature of the invention, is 3.0 or less, the number of white spots generated decreases, but the production volume decreases, and when the compression ratio exceeds 3.0, the white spots Occurrence could not be suppressed.

On the other hand, as a means for improving the dispersibility while maintaining the productivity of the composite material, talc having a predetermined bulk density and fracture rate is disclosed after degassing and compressing powdered talc (for example, (See Patent Document 3). However, with the method of Patent Document 3, white spots based on talc aggregation cannot be completely eliminated, and when used as an instrument panel or bumper, the white spots can be seen in an unpainted state, resulting in poor appearance and painting. However, there is a problem of occurrence of pinholes due to this white spot.
JP-A-4-306261 JP-A-2002-302554 (Claims 1 and 6) Japanese Patent Laying-Open No. 2005-104794

  In view of the above-mentioned problems, the present invention further derives from the fact that a large amount of resin is kneaded in a short time when actually manufactured with a twin-screw kneader of a scale used in a commercial production plant. The new problem that the inorganic filler is poorly dispersed (occurrence of white spots) and the white spot even if the blending was not a problem in a relatively small-scale kneader such as CIM-90. Reducing the degree of compression to eliminate it increases the amount of air to be brought in, so in particular in the case of large kneaders, it is an in-line compound that can solve the disadvantage of adversely affecting productivity, but based on such talc dispersion failure An object of the present invention is to provide a polypropylene resin composition containing talc having no white spots and a molded product thereof.

  As a result of various studies to elucidate the above-mentioned problems, the present inventors have blended a specific amount of a specific degassed compressed talc and a thermoplastic elastomer, so that the talc-containing polypropylene has no white spots due to poor talc dispersion. The present inventors have found that a resin composition can be obtained and completed the present invention.

That is, according to the first invention of the present invention, the polypropylene resin (A) is 30 to 92% by weight, the degassed compressed talc (B) having the following physical properties is 5 to 45% by weight, and the thermoplastic elastomer ( A polypropylene resin composition comprising 3 to 30% by weight of C) is provided.
(B) Degassed compression talc: bulk specific gravity of 0.3 to 1.0 obtained by degassing and compressing talc having an average particle size of 0.1 to 12 μm and bulk specific gravity of 0.1 to 0.5, compression ratio of 3 Degassed compressed talc with a component of 1,000 μm or more, 15% by weight or less when sieved by a low tap method according to JIS-A1102

According to the second invention of the present invention, there is provided a polypropylene resin composition according to the first invention, wherein the thermoplastic elastomer (C) is an ethylene elastomer or a styrene elastomer. .

According to a third aspect of the present invention, there is provided an automotive exterior part comprising the polypropylene resin composition of the first or second aspect.

According to a fourth aspect of the present invention, there is provided an automobile interior part comprising the polypropylene resin composition according to the first or second aspect.

  In the present invention, by using a degassed compression talc having a specific bulk specific gravity and a compression ratio, and having a small large-sized lump based on compression unevenness, and blending a thermoplastic elastomer with a polypropylene resin, a machine such as a flexural modulus is obtained. It is possible to produce a polypropylene resin composition with improved physical properties and excellent appearance, and the propylene composition should be a polypropylene resin composition that is an in-line compound but does not produce white spots due to poor talc dispersion. Can do.

  The present invention is a polypropylene resin composition containing talc containing (A) polypropylene resin, (B) degassed compressed talc, and (C) thermoplastic elastomer. Below, each component, the manufacturing method of a resin composition, the use of a resin composition, a molded article, etc. are demonstrated in detail.

[I] Polypropylene resin composition Component (A) Component: Polypropylene Resin The (A) polypropylene resin component constituting the polypropylene resin composition of the present invention is not particularly limited, and a propylene homopolymer, a propylene random copolymer, a propylene block copolymer, etc. A propylene / ethylene block copolymer or a propylene homopolymer having an ethylene content of 25% by weight or less is preferable.
The form of the polypropylene resin is not particularly limited. However, in order to produce the blending and melt-kneading process in a consistent process from the polypropylene polymerization process, it is preferably a powder form.

The polypropylene resin component used in the polypropylene resin composition of the present invention has a melt flow rate (MFR: 230 ° C., 2.16 kg load) of 3 to 300 g / 10 minutes, preferably 8 to 250 g / 10 minutes, particularly preferably. It is preferably 10 to 200 g / 10 minutes, most preferably 20 to 100 g / 10 minutes. When the MFR of the polypropylene resin component is less than the above range, the fluidity is insufficient, and when the MFR of the polypropylene resin component exceeds the above range, the impact resistance is lowered.
Here, MFR is a value measured according to JIS K-7210-1995.

The propylene / ethylene block copolymer is a block copolymer composed of a propylene homopolymer portion and a propylene / ethylene random copolymer portion, and the MFR of the propylene homopolymer portion is 5 to 1. 1,000 g / 10 min is preferable, more preferably 10 to 800 g / 10 min, and particularly preferably 30 to 500 g / 10 min. Furthermore, the isotactic pentad fraction (P) of the propylene homopolymer portion is preferably 0.98 or more, more preferably 0.985 or more.
When the MFR of the propylene homopolymer portion of the propylene / ethylene block copolymer is less than the above range, the fluidity becomes insufficient, and when the MFR exceeds the above range, the impact resistance is inferior. Further, if the isotactic pentad fraction (P) of the propylene homopolymer portion of the propylene / ethylene block copolymer is less than the above range, the flexural modulus is insufficient, which is inappropriate.
Here, the isotactic pentad fraction (P) is an isotactic fraction in pentad units in a polypropylene molecular chain measured using ¹³ C-NMR.

As the polypropylene resin used in the present invention, one produced by a Ziegler-Natta catalyst or a metallocene catalyst can be used.
In the presence of the catalyst, it is obtained by applying a production process such as a gas phase fluidized bed, a solution method, a slurry method and the like and polymerizing using propylene and, if necessary, a comonomer component.

(B) component: deaeration compression talc The deaeration compression talc used for the polypropylene resin composition of the present invention is obtained by deaeration compression of talc having an average particle diameter of 0.1 to 12 μm and a bulk specific gravity of 0.1 to 0.5. The obtained bulk specific gravity is 0.3 to 1.0, the compression ratio is 3.1 to 7.0, and the component of 1,000 μm or more when sieving by the low tap method according to JIS-A1102 is 15% by weight or less of compressed talc. is there.

The average particle diameter of the talc before being deaerated and compressed for use in the present invention is 0.1 to 12 μm, preferably 0.1 to 10 μm, and more preferably 2 to 8 μm. When the average particle diameter exceeds the above-mentioned rule, the improvement range of mechanical strength by talc is small, and there is a disadvantage that the bending elastic modulus of a product obtained by molding a polypropylene resin composition obtained by melt-kneading them is lowered. . On the other hand, when the average particle size is less than the above-mentioned limit, not only the aspect ratio of talc is impaired due to overgrinding, but also the pulverization is expensive and economically unfavorable, and inconveniences such as poor dispersion are likely to occur.
Here, the average particle size is a value obtained from a particle size value of a cumulative amount of 50% by weight read from a particle size cumulative distribution curve measured by a laser method measuring instrument (for example, LA900 manufactured by Horiba, Ltd.).

The bulk specific gravity of the talc before being deaerated and compressed for use in the present invention is 0.1 to 0.5, preferably 0.11 to 0.35, and particularly preferably 0.12 to 0.25. is there.
Moreover, the bulk specific gravity of the talc immediately after the deaeration compression process used for this invention is 0.3-1.0, Preferably it is 0.4-0.9, Especially preferably, it is 0.45 or more and 0.00. The range does not exceed 8. If the bulk specific gravity exceeds this range, a lump based on uneven compression tends to occur, which is not preferable. Conversely, if the bulk specific gravity is less than this range, the amount of air brought into the kneader during melt kneading is increased, which adversely affects productivity.
Here, the bulk specific gravity is a value measured based on JIS K-6720.

The compression rate of the degassed and compressed talc used in the present invention is 3.1 to 7.0, preferably 3.1 to 6.5, and particularly preferably 3.2 to 5.5. If the compression ratio is outside the lower limit of the above specified range, the amount of air brought into the twin-screw kneader at the time of melt kneading increases, which is not preferable because of inconvenience in productivity such as a feed neck. On the other hand, if the above specified upper limit is not reached, lumps based on uneven compression are likely to occur, resulting in the disadvantage that white spots based on talc aggregation occur in the molded product.
Here, the compression ratio is a value obtained by dividing the bulk specific gravity of after degassing compression in the bulk specific gravity of the pre-deaeration compression.

The component of 1,000 μm or more when sieved by the degassed and compressed talc used in the present invention is 15% by weight or less, preferably 13% by weight or less, more preferably 10% by weight or less. . Moreover, it is preferable that the component of 500 μm or more is 45% by weight or less, preferably 40% by weight or less, and more preferably 35% by weight or less. It is preferable that the large talc lump based on the compression unevenness is as small as possible. When the component of 1,000 μm or more when sifted by the low tap method exceeds 15% by weight, the extrusion amount of the propylene resin composition per hour is 1,000 kg. If the pellets are granulated with a large kneader exceeding / hr, white spots may be formed.
Here, the low-tap method is a sieving method defined in JIS-A1102, and a low-tap type sieve shaker has a diameter of 200 mmφ, a depth of 45 mm, and a mesh of 30 mesh (500 μm sieve) having the same diameter. Place a 16 mesh sieve (1000 μm sieve) on the pan, place 100 g of talc on the top mesh, cover and shake for 3 minutes under the conditions of a sieve width of 25 mm, a shaking speed of 290 rpm, and a hammer hitting speed of 156 rpm. This is how to do it.
The shaking condition by the low tap method gives a vibration that can collapse the compressed talc. When the compressed talc collapses due to shaking, the compressed talc passes through the sieve. Therefore, the dispersibility of the compressed talc can be evaluated by measuring the residual sieve. It is evaluated that the smaller the ratio of components of 1,000 μm or more when sieved by the degassed and compressed talc low tap method, the better the dispersibility.

  The degassed compressed talc used in the present invention is a talc having a size of 0.6 mm or more in polypropylene containing talc obtained by melt kneading with a polypropylene resin having an MFR of 30 g / 10 min and an extrusion rate of 1,000 kg / hr or more. The number of aggregates is preferably zero. By doing so, it becomes possible to further improve the dispersibility of talc, and it is possible to reduce white spots even under melt-kneading conditions such as in-line compounds that tend to cause poor dispersion.

In the present invention, the occurrence of white spots in the degassed compression talc of the component (A) is that the proportion of components having particles larger than 2.8 mm is 0.3% by weight or less, preferably 0.1% by weight or less. It is preferable from the viewpoint of preventing. Degassed and compressed talc in which the proportion of the component having a particle size larger than 2.8 mm is 0.1% by weight or less can be obtained by removing coarse powder (2.8 mm or more) after deaeration and compression once.
Examples of the method for removing the coarse powder include a method using a relatively coarse mesh and applying a sieve without greatly impairing the compression structure. Specifically, the size of the sieve mesh at this time is 6.5 mesh (sieve 2.8 mm) to 26 mesh (sieve 600 μm), preferably 7.5 mesh (sieve 2.36 mm) to 22. It is a mesh (sieve 710 micrometers), More preferably, it is the range of 8.6 mesh (sieve 2.0 mm)-18.5 mesh (sieve 850 micrometers). If the size is larger than this range, the talc processing productivity is hindered. Conversely, if the size is small and the size is large, the effect of preventing white spots is inferior.

  The degassed compression talc used in the present invention satisfies the above-mentioned regulations, and is characterized in that it is compacted relatively uniformly for a high compression rate unlike a conventional talc. Therefore, there is no strong compression history received locally, so there is very little “core”, so it can be easily dissociated and uniformly dispersed when melt-kneaded, and white spots on the appearance surface of the molded product Does not exist or its number is extremely low. The production method of talc with few lumps based on compression unevenness used in the present invention is not particularly limited as long as it does not depart from the gist of the present invention. For example, talc is produced by continuously performing the following steps (a) and (b). can do.

(A) Deaeration A known apparatus and method can be used for deaeration. For example, as a deaeration volume reduction machine, it can deaerate in advance before compressing with a roller by Kurimoto Kiko Co., Ltd. cripack or Hosokawa Micron dense pack. Following this deaeration process, a compression operation is performed as shown below.
(B) Compression Although compression can be performed using a conventionally known apparatus, it is necessary to carefully select the operating conditions. This condition is not specifically disclosed or suggested by the prior art documents so far. As a device used for the compression, a known device can be used. For example, a roller (a roller compactor manufactured by Kurimoto Seiko Co., Ltd.) can be used.

For example, the apparatus shown in FIG. 1 as disclosed in Japanese Patent Application Laid-Open No. 10-1000014 is used as the continuous apparatus of (a) and (b) described above for reducing the lump based on the compression unevenness used in the present invention. Can be used. In FIG. 1, talc stored in the hopper 15 is taken into the vacuum degassing device 1 from the supply port 5 and sent to the discharge port 6 by a screw while being degassed by the vacuum pump 12. The degassed talc is dropped into the feeder 2 from the discharge port 6, pushed downward by a screw, supplied to the compression deaerator 3 having a pair of cylindrical rolls 23, and further compressed and degassed between the rolls 23. It is discharged downward while being noticed.
In this case, it is important to set the distance between the rolls of the illustrated cylindrical roll as wide as possible. For example, this is achieved by adjusting the clearance size between 0.8 and 2.0 mm. . When the distance between the rolls is small, a large pressure is generated in the talc compressed between the rolls, and as a result, a lump that is difficult to collapse even during melt kneading is generated. On the other hand, if the width is too large, the talc cannot be compressed and a problem of slipping through occurs. At this time, it is preferable to suppress the number of revolutions of the pushing screw by setting the number of revolutions of the roll within the range of 5 to 20 rpm within a range that does not hinder the production balance and setting the number of revolutions as high as possible. . In order to compress under such conditions, it is preferable to perform deaeration compression as high as possible at the time of preliminary deaeration by a vacuum deaeration device.
The steps (a) and (b) may be performed simultaneously.

  The (A) degassed compressed talc defined in the present invention has various organic titanate coupling agents, organic silane coupling agents, fatty acids, fatty acid metal salts for the purpose of improving the adhesion or dispersibility with the polymer. The talc surface-treated with a fatty acid ester or the like may be produced by deaeration compression.

Component (C): Thermoplastic Elastomer Examples of the thermoplastic elastomer used in the polypropylene resin composition of the present invention include ethylene elastomers and styrene elastomers.
Specific examples of the ethylene elastomer include, for example, ethylene / propylene copolymer elastomer (ethylene propylene rubber: EPR), ethylene / butene copolymer elastomer (EBR), ethylene / hexene copolymer elastomer (EHR), and ethylene / octene copolymer. Ethylene / α-olefin copolymer elastomer such as elastomer (EOR); Ethylene / α-olefin such as ethylene / propylene / ethylidene norbornene copolymer, ethylene / propylene / butadiene copolymer, ethylene / propylene / isoprene copolymer -Diene terpolymer elastomer (EPDM) etc. are mentioned. These elastomer components can be used as a mixture of two or more.

  The ethylene / α-olefin copolymer elastomer is produced by polymerizing each monomer in the presence of a catalyst. Examples of the catalyst include titanium compounds such as titanium halide, organoaluminum-magnesium complexes such as alkylaluminum-magnesium complexes, so-called Ziegler-type catalysts such as alkylaluminum or alkylaluminum chloride, WO-91 / 04257, etc. The metallocene compound catalyst described in 1) can be used. As the polymerization method, polymerization can be performed by applying a production process such as a gas phase fluidized bed, a solution method, or a slurry method. Examples of commercially available products include ED series manufactured by JSR Corporation, Tuffmer P series and Tuffmer A series manufactured by Mitsui Chemicals, and Engage EG series manufactured by DuPont Dow, all of which are used in the present invention. Can do.

  Styrene elastomers include styrene / butadiene / styrene triblock, styrene / isoprene / styrene triblock, hydrogenated styrene / butadiene / styrene triblock (SEBS), styrene / isoprene / styrene triblock. And hydrogenated product (SEPS). The above hydrogenated product of styrene / butadiene / styrene triblock is usually abbreviated as SEBS since the polymer main chain is styrene-ethylene-butene-styrene when viewed in monomer units. These elastomer components can be used as a mixture of two or more.

An outline of a method for producing a hydrogenated triblock copolymer (SEBS, SEPS) among styrene elastomers will be described below.
These triblock copolymers can be produced by a general anion living polymerization method. This includes a method of sequentially polymerizing styrene, butadiene and styrene to produce a triblock, followed by hydrogenation (SEBS production method), a styrene-butadiene diblock copolymer, and a cup after There is a method in which a triblock body is made using a ring agent and then hydrogenated. Moreover, the hydrogenated product (SEPS) of a styrene-isoprene-styrene triblock body can be similarly manufactured by using isoprene instead of butadiene.

  The melt flow rate (MFR: 230 ° C., 2.16 kg load) of these thermoplastic elastomer components is 0.5 to 150 g / 10 min, preferably 0 when considering the automobile exterior material which is the main use of the present invention. It is preferably in the range of 7 to 100 g / 10 min, particularly preferably 0.7 to 80 g / 10 min.

(D) Additional component (optional component)
In the polypropylene resin composition of the present invention, in addition to the above essential components (A), (B), and (C), other additional components (optional components) are included within the range not significantly impairing the effects of the present invention. ) Can be added.
Additives such as phenolic and phosphorus antioxidants, hindered amine, benzophenone, and benzotriazole weathering resistance inhibitors, nucleating agents such as organic aluminum compounds and organic phosphorus compounds, and metal salts of stearic acid Neutralizers, dispersants, colored materials such as quinacridone, perylene, phthalocyanine, titanium oxide, carbon black, fibrous potassium titanate, fibrous magnesium oxysulfate, fibrous aluminum borate, calcium carbonate whiskers, carbon fibers And materials such as glass fiber.
Examples of the dispersant include fatty acids such as stearic acid, zinc stearate, magnesium stearate, zinc behenate, lithium stearate, barium stearate, calcium stearate, and metal salts thereof.

2. Component blending ratio In the polypropylene resin composition of the present invention, the blending ratio of the component (A) propylene resin, component (B) degassed compression talc, and component (C) thermoplastic elastomer is such that (A) component is 30 to 30. 92% by weight, (B) component is 5-45% by weight, (C) component is 3-30% by weight, preferably (A) component is 45-80% by weight, (B) component is 10-30% by weight %, (C) component is 3 to 25 weight%. When the component (B) is less than 5% by weight, the rigidity is insufficient, and when it exceeds 45% by weight, the fluidity and impact properties are lowered. Further, when the component (C) is less than 3% by weight, impact resistance and paintability are low, and when it exceeds 30% by weight, rigidity and heat resistance are lowered.

[II] Method for Producing Polypropylene Resin Composition The polypropylene resin composition of the present invention is produced by melt-kneading with a large kneader having a large extrusion amount. At that time, in order to enjoy the cost merit of the in-line compound, it is preferable that the pre-mixing, melt-kneading, and granulating steps are performed consistently as follows.
First, a polypropylene resin produced in a polypropylene polymerization plant is transferred to a kneading and granulating facility through a transport pipeline. Next, the transferred polypropylene resin (component (A)) is degassed and compressed talc (component (B)) having the above physical properties, thermoplastic elastomer (component (C)), and if necessary, the additional Premix with component (component (D)). Although it does not specifically limit as a premixer, A batch type Henschel mixer, a tumbler mixer, a continuous powder mixer etc. can be illustrated.
Subsequently, after blending the above-described constituent components, melt-kneading is performed using a large extruder, and cutting is performed in the subsequent granulation step. At this time, the lower limit of the extrusion amount of the resin composition is 1,000 kg / hr, preferably 2,000 kg / hr, more preferably 3,000 kg / hr. A low extrusion amount that is less than the lower limit is not preferable from the economical viewpoint. On the contrary, the upper limit value is not particularly limited, but is preferably 20,000 kg / hr, more preferably 10,000 kg / hr in view of the scale of facilities that have been used so far. The kneader is not particularly limited, and examples thereof include a single-screw kneader, a twin-screw kneader, or a tandem kneader in which two and a single shaft (uniaxial) are combined. In particular, in consideration of talc dispersion and the like, a tandem kneader is preferable, and a method of melt kneading with a single screw extruder after a biaxial melt kneading is preferable.

[III] Use of polypropylene resin composition Since the polypropylene resin composition of the present invention is reinforced with talc, it has excellent balance between rigidity and impact resistance and is a material having high dimensional properties. However, it is preferably used for injection molded products such as automobile parts, especially door trims, pillar trims, console boxes, various housing materials, case materials, bumper materials, air conditioner cases, lamp housings, etc. .

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In addition, the measuring method used for an Example and a comparative example is as follows.

(1) Talc average particle diameter: measured using a laser particle size distribution measuring machine (LA920 manufactured by Horiba, Ltd.).
(2) Talc bulk specific gravity: Measured according to JIS K-6720.
(3) Compressed uneven lump amount by low tap method: low tap type sieve shaker (Teraoka Co., Ltd. low tap type sieve shaker S-2 type 1996 made), diameter 200 mmφ, depth 45 mm, 30 mesh Place a 16-mesh sieve of the same diameter on a sieve and place it on a tray. Place 100 g of talc on the top mesh and cover it with a sieve width of 25 mm. Shake for a minute. Then, from the change in the weight of each dish, the weight of coarse particles that did not pass through the mesh was obtained, and the weight of the component of 1000 μm or more from the 16 mesh sieve residue was calculated from the total of the 16 mesh sieve residue and the 30 mesh sieve residue. The weight of the component of 500 μm or more was determined, and the ratio was determined by calculation.
(4) Number of white spots when kneaded with PP of MFR = 30 g / 10 min: each talc and propylene-ethylene copolymer (PP: MFR = 30 g / 10 min, rubber component content 13 wt%, ethylene content in rubber 50 wt% %: Nippon Polypro Co., Ltd .: Product name BC03EQ), as an additive, tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4 ′) per 100 parts by weight of polypropylene resin -Hydroxyphenyl) propionate] methane (IRGANOX1010 manufactured by Ciba Specialty Chemicals) 0.05 parts by weight, zinc stearate 0.4 parts by weight, and a biaxial continuous powder mixer (screw diameter 330 mm, L / D; 9 ), The mixture is uniformly mixed and blended at a screw speed of 30 rpm, and then continuously mixed with a twin-screw kneader (Nippon Steel). And manufactured CIM320), single-screw extruder (screw diameter 305 mm, and melt-kneaded and granulated in combination L / D = 13), were prepared talc-containing polypropylene resin composition of interest.
The conditions of CIM320 were a rotor rotational speed of 360 rpm, ESP = 0.18, a single screw extruder of 70 rpm, a resin temperature of 215 ° C., and a discharge rate of 3.8 t / h.
The resulting pellet was evaluated for white point by the method (8).
(5) MFR: Measured according to JIS-K7210.
(6) Flexural modulus: measured in accordance with JIS-K7203.
(7) Izod (IZOD) impact strength: measured in accordance with JIS-K7110.
(8) Evaluation of the number of white spots: After the pellets obtained by kneading and granulation are put into an injection molding machine hopper, empty shot is performed for 10 shots, and further molding is started under the following molding conditions, and 5 shots until molding is stabilized. The minutes were discarded and the 6th to 15th shots were sampled. Observe the presence or absence of white granular material (referred to as white spots) on the entire front and back surfaces of the obtained product, and observe with a magnifying magnifier (16 times) with a scale, and measure the number and size of the white spots. Judgment based on criteria. In addition, as what can be visually discriminate | determined, it classify | categorized into 0.6 mm or more and within 0.4-0.6 mm, and discriminate | determined by counting the number.
(Criteria)
×: 0.6 mm or more component 1 or more ○: 0.6 mm or more component 0
(Molding condition)
(A) Product shape: vertical 345 mm × width 200 mm × height 30 mm, top wall thickness 2.5 mm box shape, product rear surface is fully rough finished (b) injection molding machine: IS170FII-10A manufactured by Toshiba Machine Co., Ltd.
(C) Mold: A two-plate structure consisting of a pair of males and females, with the fixed mold (female) on the product surface and the movable mold (male) on the back of the product, and in the center of the product is filled with resin with a direct gate (d ) Molding conditions: molding temperature: 220 ° C., mold temperature: 40 ° C., injection pressure: 100 MPa, holding pressure; 40 MPa, injection filling time: 7 seconds, holding time: 8 seconds, cooling time: 20 seconds, screw rotation speed ; 150 rpm, screw back pressure; None

Example 1
A fine talc having an average particle size of 5.0 μm and a bulk specific gravity of 0.12 (manufactured by Hayashi Kasei Co., Ltd .: MW5000S) (hereinafter referred to as “raw material 1”) was used with a Kurimoto Seiko Cripack and a bulk specific gravity of 0. After primary deaeration to around 35, without taking out, it was subsequently subjected to secondary compression with a roller compactor made by Kurimoto Seiko (1.1 mm between rollers, roller rotation speed 10 rpm, pushing screw 17 rpm), and deaeration compression talc (talc- 1) was produced.
The property of this talc-1 was a bulk specific gravity of 0.58, and the amount of components of 1,000 μm or more by the low tap method was 6% by weight.
The talc-1 thus obtained was blended in the proportions shown in Table 2, with a propylene-ethylene copolymer (PP: MFR = 27 g / 10 min, rubber component content 22 wt%, ethylene content 40 wt% in rubber: In addition to Nippon Polypro Co., Ltd .: product name BC02GQ), ethylene-butene copolymer rubber (JSR: EBM3021 MF) is used as a thermoplastic elastomer, and tetrakis is added to 100 parts by weight of polypropylene resin as an additive. [Methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane (IRGANOX 1010, manufactured by Ciba Specialty Chemicals) 0.05 parts by weight and calcium stearate 0.4 parts by weight were added. , By a biaxial continuous powder mixer (screw diameter 330mm, L / D = 9) Premixing was performed at a screw rotation speed of 30 rpm to obtain a resin composition.
This was continuously melt kneaded and granulated with a combination of a twin screw kneader (CIM320 manufactured by Nippon Steel Co., Ltd.) and a single screw extruder to produce a target talc-containing polypropylene resin composition.
The obtained pellets were injection-molded, and white point evaluation and physical properties were measured. Table 1 shows the physical properties of talc, and Table 2 shows the evaluation results of the resin composition.

(Example 2)
A talc-containing polypropylene resin composition was produced in the same manner as in Example 1 except that the amounts of PP, talc-1, and rubber were changed as shown in Table 2. The obtained pellets were injection-molded, and white point evaluation and physical properties were measured. The evaluation results of the resin composition are shown in Table 2.

(Example 3)
About the manufacturing conditions of talc-1 used in Example 1, the same roll space | interval and the same roll rotation speed as Example 1 were employ | adopted, only the rotation speed of a pushing screw was changed and adjusted, and deaeration compression talc (talc-2 ) Was manufactured. Using the obtained talc, the composition shown in Table 2 was blended by the same method as in Example 1, melt kneaded and granulated, and the white spot of the test sample was evaluated. Table 1 shows the physical properties of talc, and Table 2 shows the evaluation results of the resin composition.

(Comparative Example 1)
About the manufacturing conditions of talc-1 used in Example 1, the same roll rotational speed as Example 1 was adopted, the rotational speed of the pushing screw was changed to 13 rpm, and the roll interval was changed to 0.5 mm. Talc-3) was produced.
The properties of this talc-3 were as follows: bulk specific gravity 0.8, amount of components of 1,000 μm or more by low tap method was 18% by weight, and amount of components of 500 μm or more was 46% by weight. The number of talc aggregates with a size of 0.6 mm or more in polypropylene containing talc obtained by melt kneading with polypropylene resin having an MFR of 30 g / 10 min and an extrusion rate of 1,000 kg / hr is 10. there were. Using the obtained talc, the composition shown in Table 2 was blended by the same method as in Example 1, melt kneaded and granulated, and the white spot of the test sample was evaluated. Table 1 shows the physical properties of talc, and Table 2 shows the evaluation results of the resin composition.

(Comparative Example 2)
About the manufacturing conditions of talc-1 used in Example 1, the same roll space | interval and the same roll rotation speed as Example 1 were employ | adopted, only the rotation speed of a pushing screw was changed and adjusted, and deaeration compression talc (talc-4 ) Was manufactured. Using the obtained talc, the composition shown in Table 2 was blended by the same method as in Example 1, melt kneaded and granulated, and the white spot of the test sample was evaluated. Table 1 shows the physical properties of talc, and Table 2 shows the evaluation results of the resin composition.

  Since the polypropylene resin composition of the present invention is a high-performance material without the problem of poor dispersion of inorganic filler (generation of white spots), it is an injection-molded product such as automobile parts, particularly bumpers, instrument panels, It can be used for door trims, pillar trims, console boxes, various housing materials, and the like.

It is a figure explaining an example of the deaeration compression device of talc.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum deaeration device 2 Feeder 3 Compression deaeration device 5 Supply port 6 Discharge port 12 Vacuum pump 15 Hopper 23 A pair of cylindrical rolls

Claims (4)

30 to 92% by weight of polypropylene resin (A), 5 to 45% by weight of deaerated compressed talc (B) having the following physical properties, and 3 to 30% by weight of thermoplastic elastomer (C) A featured polypropylene resin composition.
(B) Degassed compression talc: bulk specific gravity of 0.3 to 1.0 obtained by degassing and compressing talc having an average particle size of 0.1 to 12 μm and bulk specific gravity of 0.1 to 0.5, compression ratio of 3 Degassed compressed talc with a component of 1,000 μm or more, 15% by weight or less when sieved by a low tap method according to JIS-A1102   The polypropylene resin composition according to claim 1, wherein the thermoplastic elastomer (C) is an ethylene elastomer or a styrene elastomer. Automobile exterior parts, characterized by comprising a polypropylene resin composition according to claim 1 or 2. Automobile interior parts, characterized by comprising a polypropylene resin composition according to claim 1 or 2.

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