JP2001002863A - Thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropyrene resin composition which shows not only excellent surface hardness but excellent toughness such as impact resistance, tensile elongation at break and the like. SOLUTION: This composition comprises (A) 50 to 99 wt.% of a polypropyrene resin, (B) 1 to 40 wt.% of an ethylene-α-olefin random copolymer which has a density of 0.85 to 0.90 g/cm3 and a melt flow rate (MFR: at 230 deg.C and under a load of 2,160 g) of 0.1 to 100 g/10 min and shows not less than 2 peaks of crystallization temperatures (Tc) in a temperature decrease thermogram at a rate of 10 deg.C/min measured by means of a differential scanning calorimeter(DSC) and (C) 0 to 40 wt.% of an inorganic filler.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition having excellent surface hardness and excellent toughness such as impact resistance and tensile elongation at break, and more particularly to injection molding (injection compression) of automobile interior and exterior parts. (Molding and molding).

[0002]

2. Description of the Related Art Polypropylene is widely used in various fields because of its low cost, low density, but good heat resistance, rigidity and moldability. However, because of poor toughness such as impact resistance and tensile elongation at break, ethylene-propylene block copolymers obtained by multi-stage polymerization for the purpose of improving ethylene-propylene copolymer, ethylene-butene copolymer, etc. Various polypropylene compositions to which a rubber component and an inorganic filler such as talc are added have been proposed. These compositions are used in particular for molding materials for various industrial parts such as interior and exterior parts for automobiles such as bumpers, instrument panels and garnishes, and parts for home appliances such as TV cases. In recent years, these products have become thinner, more functional, and larger in size, so that higher performance of materials is required.

Since the effect of improving the impact resistance of the rubber component is small, it is necessary to incorporate a large amount of the rubber component in order to improve the impact resistance. Although the thermoplastic resin composition containing a large amount of the rubber component is excellent in impact resistance, the rigidity, surface hardness, and heat resistance are greatly reduced. Therefore, it has been difficult to obtain a thermoplastic resin composition having excellent impact resistance and excellent rigidity, surface hardness, and heat resistance. Attempts have been made to use other ethylene / α-olefin random copolymers or blends thereof instead of the rubber component. For example, JP-A-6-192506 discloses a melting point of 80 ° C. derived from polypropylene and 1-octene.
Or less, a glass transition temperature of −50 ° C. or less, a degree of crystallinity of less than 20%, and a randomness parameter of 1.0 to 1.4, which is a polypropylene containing an ethylene / 1-octene random copolymer. A composition is disclosed. However, although this polypropylene composition is excellent in impact resistance, there is room for improvement in rigidity. In addition, Japanese Patent Application Laid-Open
No. 4,488,884 discloses ethylene and α having 4 to 12 carbon atoms.
-Copolymer of olefin, propylene and carbon number 6-1
The copolymer with α-olefin No. 2 is blended with polypropylene, which is excellent in impact resistance but has room for improvement in surface hardness. Further, in JP-A-9-143338, an ethylene / 1-hexene random copolymer is used, but there is still room for improvement in the surface hardness. Therefore, development of a thermoplastic resin composition which is excellent in rigidity, surface hardness, heat resistance and also excellent in toughness such as impact resistance and tensile elongation at break is desired.

[0004]

Therefore, the problem to be solved by the present invention is that the surface hardness is excellent,
An object of the present invention is to provide a polypropylene resin composition having excellent toughness such as impact resistance and tensile elongation at break.

[0005]

DISCLOSURE OF THE INVENTION In view of the above objects, the present inventors have formulated a polypropylene resin, an ethylene / α-olefin random copolymer having a specific crystallization peak temperature, and optionally an inorganic filler. As a result, they have found that the above problems can be solved, and have completed the present invention. That is, the present invention relates to (A) polypropylene resin 50 to 9
9% by weight and (B) (i) a density of 0.85 to 0.90 g /
is cm ^3, (ii) a melt flow rate (MFR:
230 ° C, under 2160g load) 0.1-100g / 1
0 minutes, and (iii) an ethylene / α-olefin random copolymer 1 in which two or more crystallization peak temperatures (Tc) are observed in a cooling thermogram at 10 ° C./min by a differential scanning calorimeter (DSC). A thermoplastic resin composition comprising from about 40% by weight to about 40% by weight and (C) 0 to 40% by weight of an inorganic filler.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below. [1] Each component of the thermoplastic resin composition Polypropylene resin (component (A)) The (A) polypropylene resin used in the present invention is:
The homo-propylene resin of the propylene homopolymer may of course be a propylene-ethylene copolymer. In particular, a propylene-ethylene copolymer is desirable from the viewpoint of physical property balance and cost. The propylene-ethylene copolymer is preferably synthesized by multi-stage polymerization. In multistage polymerization,
First, propylene is polymerized in the presence of a Ziegler catalyst or the like to produce a crystalline propylene homopolymer portion (which may contain a small amount of a comonomer component). Produces a copolymer moiety. The propylene-ethylene block copolymer synthesized by the multi-stage polymerization has a substantially crystalline homopropylene portion and a propylene-
It is composed of an ethylene copolymer part and a small amount of crystalline homopolyethylene part, and each part may be present as a single polymer or may be in a state where they are combined. Each of the above-mentioned parts is basically composed of propylene and / or ethylene, but other α-olefins, for example, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene , 1-octene, diene-based monomers and the like may be contained in small amounts.

[0007] The above-mentioned polypropylene resin can be produced by various methods. Among them, a preferable method is, for example, production by applying a known slurry polymerization method, a solution polymerization method, a liquid phase polymerization method using an olefin monomer as a medium, and a gas phase polymerization method in the presence of a stereoregular catalyst. Can be. An organic peroxide may be added to the polypropylene resin to reduce the molecular weight by a melt extrusion reaction or the like, and may be adjusted to a desired melt flow rate.

[0008] 2. Ethylene / α-olefin random copolymer (component (B)) (1) Physical properties of ethylene / α-olefin random copolymer (i) Density The density of the ethylene / α-olefin random copolymer used in the present invention is as follows. 0.85 to 0.90 g / cm ³
And preferably 0.86 to 0.88 g / cm ³ . From the ethylene / α-olefin random copolymer having a density of less than 0.85 g / cm ³ , only a thermoplastic resin composition having insufficient hardness can be obtained, and the density is 0.90 g / cm ^3.
From the above ethylene / α-olefin random copolymer, only a thermoplastic resin composition having insufficient impact resistance can be obtained.

(Ii) Melt flow rate The melt flow rate of the ethylene / α-olefin random copolymer used in the present invention (MFR: 230)
C. under a 2160 g load) is 0.1 to 100 g / 10 min, preferably 0.2 to 80 g / 10 min. M
From an ethylene / α-olefin random copolymer having an FR of less than 0.1 g / 10 minutes, only a thermoplastic resin composition having insufficient impact resistance and fluidity can be obtained, and an MFR of 100 or less.
From the ethylene / α-olefin random copolymer exceeding g / 10 minutes, only a thermoplastic resin composition having insufficient impact resistance and surface hardness can be obtained.

(Iii) Crystallization peak temperature 10 ° C. of the ethylene / α-olefin random copolymer used in the present invention measured by a differential scanning calorimeter (DSC)
Crystallization peak temperature (Tc) in cooling thermogram per minute
Need to be observed more than once. The difference between the high temperature side (Tc2: high temperature crystallization peak temperature) and the low temperature side (Tc1: low temperature crystallization peak temperature) of the crystallization peak temperature (Tc) is 5 ° C. or more, preferably 8 ° C. or more. Further, Tc2 is 110 ° C. or lower, preferably 100 ° C. or lower, more preferably 90 ° C. or lower, and Tc1 is 70 ° C. or lower, preferably 60 ° C. or lower, more preferably 50 ° C. or lower.

(Iv) TREF elution amount Temperature T1 = −1097 + c × represented by carbon number (c) and density (d) of α-olefin of the ethylene / α-olefin random copolymer used in the present invention.
For 2.3 + d × 1270, the elution amount by T2 = (T1 + 30) or more by temperature-rise elution fractionation (TREF) is preferably 5% by weight or more of the total elution.

[0012] The temperature rise elution fractionation (Temperat
ure Rising Elution Fracti
onion: TREF) is described in “Jour
nal of Applied Polymer Sc
issue, Vol 26, 4217-4231. (1
981) ”and“ Polymer Paper Collection 2P1C09 (19
1985) ”as follows. First, a polymer to be measured is completely dissolved in a solvent. Thereafter, cooling is performed to form a thin polymer layer on the surface of the inert carrier. Such a polymer layer is likely to be crystallized inside (the side close to the inert carrier surface)
In addition, what is difficult to crystallize is formed on the outside. Next, when the temperature is increased continuously or stepwise, in the low temperature stage, the polymer elutes from the amorphous portion in the target polymer composition, that is, the polymer having a large degree of short-chain branching, and gradually increases as the temperature increases. In this case, the one with a low degree of branching elutes, and finally the linear part without branching elutes, and the measurement is completed. The concentration of the eluted component at such a temperature is detected, and the composition distribution of the polymer can be seen from a graph drawn by the amount of the eluted and the elution temperature.

(2) Production of ethylene / α-olefin random copolymer The above ethylene / α-olefin random copolymer (B) can be polymerized using a known titanium catalyst or metallocene catalyst. It is desirable to carry out polymerization using a metallocene catalyst. The ethylene / α-olefin random copolymer (B) is composed of ethylene and C 4
Desirably, the copolymer is a random copolymer with α-olefins of from 12 to 12. Specific examples of such α-olefin include 1-butene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, and the like. Among them, a random copolymer with an α-olefin having 6 carbon atoms is preferable.

3. Inorganic Filler ((C) Component) Specific examples of the (C) inorganic filler used in the present invention include talc, calcium carbonate, glass fiber, basic magnesium sulfate whisker, calcium titanate whisker, aluminum borate whisker, Mica and the like. Among them, talc is preferred. Talc preferably used in the present invention is talc having an average particle size of 10 μm or less, preferably 5 μm or less. The average particle size of talc can be measured by a laser diffraction scattering method. In the present invention, among such talcs, talc having an average value of an aspect ratio (a ratio of length or thickness in either a vertical direction or a horizontal direction) of 4 or more, preferably 5 or more is used. The measurement of the aspect ratio of talc is obtained from a value measured by a microscope or the like.

The talc is first produced by, for example, crushing raw talc with an impact mill or a micron-mill type pulverizer. It is manufactured by a method such as classification adjustment. The talc may be untreated or surface-treated in advance. Surface treatment is preferred because the rigidity and heat resistance of the composition can be improved. Specific examples of the surface treatment include a chemical or physical treatment using a treating agent such as a silane coupling agent, a higher fatty acid, a fatty acid metal salt, an unsaturated organic acid, or an organic titanate. In particular, the surface treatment method of talc using a metal salt is not particularly limited, for example, talc powder that has been previously pulverized and classified, and a method of mixing a predetermined amount of metal salt with a high-speed mixer, and the resin composition of the present invention. When kneading and granulating the above, a method of blending and mixing the metal salt and talc powder together with other polypropylene or the like and supplying the mixture to a granulator may be used. Further, the above-mentioned inorganic fillers may be used alone or as a blend of several kinds.

4. Other Ingredients The thermoplastic resin composition of the present invention may have other additives such as a heat stabilizer, an antioxidant, and a light-stable Agents, flame retardants, nucleating agents, plasticizers, antistatic agents, copper damage inhibitors, mold release agents, foaming agents, coloring agents, pigments and dispersants thereof. The above-mentioned various additives and pigments are generally added when each component is mixed, but a high-concentration master batch may be prepared in advance and then blended after injection or extrusion.

5. Mixing ratio of each component The mixing ratio of the above components is such that (A) the polypropylene resin is 50 to 99% by weight, preferably 60 to 95% by weight, and (B) the ethylene / α-olefin random copolymer is 1%. -40% by weight, preferably 3-30% by weight;
(C) 0-40% by weight of inorganic filler, preferably 5-3%
0% by weight. When the content of the (A) polypropylene resin is less than 50% by weight, the rigidity, heat resistance and hardness of the obtained thermoplastic resin composition are liable to decrease, while when it exceeds 99% by weight, the toughness is reduced. When the (B) ethylene / α-olefin random copolymer is less than 1% by weight, toughness is insufficient, while when it exceeds 40% by weight, strength, rigidity, heat resistance, hardness and the like are reduced. When the content of the inorganic filler (C) exceeds 40% by weight, impact resistance and ductility are reduced.

[2] Production of thermoplastic resin composition (1) Kneading The above components (A) to (C) and, if necessary, other components are blended in the above blending ratio, and a single-screw extruder or a twin-screw extruder is used. ,
The thermoplastic resin composition of the present invention can be obtained by kneading using an ordinary kneading machine such as a Banbury mixer, a roll mixer, a Brabender plastograph, a kneader or the like. In this case, it is preferable to select a kneading method capable of uniformly dispersing the components, and usually kneading is performed using a twin-screw extruder. In this kneading, the compound of each of the above components may be kneaded at the same time or may be kneaded sequentially.

(2) Molding of thermoplastic resin composition The thermoplastic resin composition thus obtained is molded by injection molding (including gas injection molding) or injection compression molding (press injection). Accordingly, various molded products, particularly, automotive interior and exterior parts such as bumpers, instrument panels, and garnishes, and home electric appliance parts such as TV cases can be obtained.

[0020]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto. The raw materials and test methods used in Examples and Comparative Examples are as follows. 1. Raw Material (A) Polypropylene (PP) 8% by weight of ethylene / propylene copolymer part is contained,
A crystalline ethylene / propylene block copolymer having an overall ethylene content of 3.2% by weight and an overall component MFR of 50 g / 10 min was used.

(B) Ethylene / α-olefin random copolymer α-olefin carbon number, density, MFR, DS shown in Table 1
An ethylene / α-olefin random copolymer having a high-temperature crystallization peak temperature, a low-temperature crystallization peak temperature and a difference between them, and a TREF elution amount by C was used. These ethylene / α-olefin random copolymers are disclosed in
Polymerization was carried out according to the description of No. 8545. That is, a catalyst solution was prepared by mixing a specific amount of a solid metal component and an ionic activator into purified toluene under an inert nitrogen atmosphere at a controlled temperature (20 ° C.). The stirred catalyst container is made of transparent pressure-resistant glass,
Each catalyst solution could be visually inspected. After adding the catalyst components to the toluene, all catalysts appeared yellow and homogeneous. At such a speed that the desired maximum reactor temperature is obtained,
The catalyst solution was continuously fed to the reactor using a high pressure pump. And, in ERA-1a to 7a, 8b and 9b, silicon-bridged bis-Cp hafnocene (3.7 g / l) as a solid metal component and tri (pentafluorophenyl) boron (1.2 g / l) as an ion activator. The catalyst used was adjusted. The polymerization of ERA-1a was carried out at a constant pressure of 1300 bar and a constant flow rate of hexene of 51.6 mol% with respect to ethylene and controlling the temperature at 136 ° C. Table 2 shows other polymerization conditions of the ethylene / α-olefin random copolymer. Also, ERA-1b to 7
For b, the grade shown in Table 3 manufactured by DuPont Dow was used.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

(C) Inorganic filler Talc having an average particle size of 4.6 μm and an aspect ratio of 6 was used.

2. Physical property measurement method (1) MFR: According to ASTM D1238, temperature:
It measured at 230 degreeC and load: 2160 g. (2) Crystallization peak temperature: Both the heating and cooling processes were performed at a rate of 10 ° C./min using a differential scanning calorimeter (DSC manufactured by Seiko Instruments Inc.), and the crystallization peak temperature was measured.

(3) TREF: TREF Temperature rising elution fractionation (Temperature Rising Elut)
In the measurement by ion fractionation (TREF), the polymer was once completely dissolved at a high temperature, then cooled, a thin polymer layer was formed on the surface of the inert carrier, and then the temperature was continuously or stepwise increased to elute. The components are collected, the concentration is continuously detected, and the composition distribution of the polymer is measured by the peak of a graph (elution curve) drawn by the elution amount and the elution temperature.

The elution curve was measured as follows. As a measuring device, a cloth separation device (CFC T101 manufactured by Diamond Instrument) was used. This cross-separation apparatus includes a temperature-rise elution separation (TREF) mechanism for separating a sample by using a difference in dissolution temperature, and a size exclusion chromatograph (Size Exclusion Chromatog) for further separating the separated fractions by molecular size.
SEC) is connected online.

First, the sample to be measured (ethylene-α-
An olefin random copolymer) is dissolved at 140 ° C. using a solvent (o-dichlorobenzene) so as to have a concentration of 3 mg / ml, and the solution is injected into a sample loop in a measuring device. The following measurements are performed automatically according to the set conditions.
The sample solution held in the sample loop is separated using a difference in dissolution temperature by a TREF column (inside diameter 4 mm, length 150 m filled with glass beads as an inert carrier).
0.4 ml is injected into a stainless steel column attached to the m apparatus. The sample is then cooled at a rate of 1 ° C./min from 140 ° C. to a temperature of 0 ° C. and coated on the inert carrier. At this time, a polymer layer is formed on the surface of the inert carrier in the order of high crystalline components (easily crystallized) to low crystalline components (difficult to crystallize). After the TREF column is kept at 0 ° C. for another 30 minutes, 2 ml of the component dissolved at a temperature of 0 ° C. is injected from the TREF column into a SEC column (three AD806MS manufactured by Showa Denko) at a flow rate of 1 ml / min. . While the molecular size is being fractionated by SEC, the temperature of the TREF column is raised to the next elution temperature (5 ° C.) and maintained at that temperature for about 30 minutes. The measurement of each elution section by SEC was performed at intervals of 39 minutes. The elution temperature is raised stepwise at the following temperature. 0, 5, 10, 15,
20, 25, 30, 35, 40, 45, 49, 52, 5
5,58,61,64,67,70,73,76,7
9,82,85,88,91,94,97,100,1
02,120,140 ° C

The solution fractionated by the molecular size in the SEC column was measured for absorbance in proportion to the concentration of the polymer using an infrared spectrophotometer attached to the apparatus (wavelength 3.42 μm,
Chromatogram of each elution temperature category is obtained. Using built-in data processing software,
The baseline of the chromatogram of each elution temperature section obtained by the above measurement is drawn and processed. The area of each chromatogram is integrated and an integrated elution curve is calculated. Further, this integrated elution curve is differentiated with respect to temperature to calculate a differential elution curve.

(4) Tensile test (tensile strength and tensile elongation): Measured at 23 ° C. according to ASTM D658 (unit is MPa and%). The tensile speed was 20 mm / min. (5) Izod impact strength (Izod): ASTM D
It was measured at 23 ° C. according to 256 (unit is KJ / m ² ). (6) Rockwell hardness: measured by ASTM D785 (unit is R scale).

Examples 1 to 9 and Comparative Examples 1 to 11 The components (A) to (C) were blended in the proportions shown in Table 4 and dry blended using a super mixer. The mixture was melt-kneaded using a high-speed twin-screw extruder (KCM) and extruded to obtain pellets. The obtained pellets were subjected to a resin temperature of 210 ° C. and a mold temperature of 3 using an injection molding machine.
Injection molding was performed at 0 ° C., and a physical property test piece was molded and evaluated. Table 5 shows the evaluation results.

[0033]

[Table 4]

[0034]

[Table 5]

As shown in Table 5, each of the thermoplastic resin compositions having the compositions shown in Examples 1 to 9 exhibited a good balance of physical properties. On the other hand, those shown in Comparative Examples 1 to 11 had poor physical property balance.

[0036]

Industrial Applicability The thermoplastic resin composition of the present invention has excellent surface hardness and also excellent toughness such as impact resistance and tensile elongation at break. Therefore, it is useful for products obtained by injection molding of industrial materials such as automobile interior / exterior parts and home electric parts. In particular, it can be suitably used as a molding material for various industrial parts such as thinner parts, higher functions, and larger moldings, for example, automobile parts such as bumpers, instrument panels and garnishes, and household electric appliance parts such as TV cases. Can be done.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuji Fujita 1 Toho-cho, Yokkaichi-shi, Mie Japan Polychem Corporation Material Development Center F-term (reference) 4J002 BB052 BB121 BB151 DE186 DE236 DJ046 DJ056 DK006 DL006 FA046 FA066 FD016 GN00

Claims (10)

[Claims] (1) 50-99% by weight of a polypropylene resin and (B) (i) a density of 0.85-0.90 g / cm
³ , (ii) melt flow rate (MFR: 23
(0 ° C., under a load of 2160 g) is 0.1 to 100 g / 10 min, and (iii) 1 according to a differential scanning calorimeter (DSC).
In a thermostat at 0 ° C./min, 1 to 40% by weight of an ethylene / α-olefin random copolymer at which two or more crystallization peak temperatures (Tc) are observed and (C) 0 to 40% by weight of an inorganic filler A thermoplastic resin composition comprising: 2. The ethylene / α-olefin random copolymer (B) is measured at 10 ° C. by a differential scanning calorimeter (DSC).
2. The thermoplastic resin composition according to claim 1, wherein a difference between the high-temperature crystallization peak temperature (Tc2) and the low-temperature crystallization peak temperature (Tc1) is 5 ° C. or more in the cooling thermogram per minute. 3. The thermoplastic resin composition according to claim 1, wherein Tc2 is 110 ° C. or lower. 4. The thermoplastic resin composition according to claim 1, wherein Tc1 is 70 ° C. or lower. 5. Tc2 is 110 ° C. or less, and Tc
The thermoplastic resin composition according to claim 1, wherein 1 is 70 ° C. or lower. 6. A temperature T1 of the ethylene / α-olefin random copolymer (B) represented by the carbon number (c) and the density (d) of the α-olefin: T1 = −1097 + c × 2.3.
The thermoplastic resin composition according to any one of claims 1 to 5, wherein the amount eluted by temperature rise elution fractionation (TREF) of T2 = (T1 + 30) or more with respect to + d x 1270 is 5% by weight or more of the total amount. 7. The thermoplastic resin composition according to claim 1, wherein the ethylene / α-olefin random copolymer (B) is polymerized using a metallocene catalyst. 8. The method according to claim 1, wherein the ethylene / α-olefin random copolymer (B) is a copolymer of ethylene and an α-olefin having 4 to 12 carbon atoms. Thermoplastic resin composition. 9. The thermoplastic according to claim 1, wherein the ethylene / α-olefin random copolymer (B) is a copolymer of ethylene and an α-olefin having 6 carbon atoms. Resin composition. 10. The inorganic filler (C) has an average particle size of 10 μm.
The thermoplastic resin composition according to any one of claims 1 to 9, which is the following talc.