JP6965664B2 - Polypropylene resin composition for injection molding - Google Patents

Description

The present invention relates to a polypropylene-based resin composition for injection molding, and more particularly to a polypropylene-based resin composition for injection molding, which has an excellent balance of flexibility, impact resistance, light-shielding property, whitening resistance, and moldability.

Since polypropylene is lightweight and has excellent mechanical strength and the like, it is widely used in various fields as an injection-molded molded product or the like.
However, since the balance between impact resistance and rigidity is inferior, many various polypropylene-based resin compositions have been proposed (see, for example, Patent Document 1).
However, the polypropylene-based resin composition proposed above is excellent in whitening property, but lacks impact resistance in a refrigerated environment, and further impairs light-shielding property due to high transparency, and the performance is still insufficient. Further improvement in performance is required, and in particular, a polypropylene-based resin composition having an excellent balance of flexibility, impact resistance, light-shielding property, whitening resistance, and moldability and an injection molded product using the same are required. There is.

Japanese Unexamined Patent Publication No. 2015-20603

An object (problem) of the present invention is an injection-molding polypropylene-based resin composition having an excellent balance of flexibility, impact resistance, light-shielding property, whitening resistance, and moldability, and injection, in view of the above-mentioned problems of the prior art. The purpose is to provide a molded product.

As a result of diligent studies to solve the above problems, the present inventor has added flexibility, impact resistance, light shielding property, and whitening resistance when a specific polypropylene resin is blended with a specific propylene-ethylene resin composition. , And found that an excellent polypropylene-based resin composition for injection molding and an injection-molded product using the same can be obtained with improved moldability, and based on these findings, the present invention has been completed.

That is, according to the first invention of the present invention, the ethylene content is 0.1 to 3.0% by weight, and the melt flow rate (MFR) conforming to JIS K7210 (230 ° C., 2.16 kg load) is 10 to 150 g. A propylene-containing a propylene-ethylene copolymer (a) having a / 10-minute content and a propylene-ethylene copolymer (b) having an ethylene content of 5 to 20% by weight and an MFR of 1 to 30 g / 10 minutes. The propylene-ethylene resin composition (A), wherein the weight ratio of the propylene-ethylene copolymer (a) and the propylene-ethylene copolymer (b) is 90: 10 to 60:40. 80 to 95% by weight of the substance (A) and 5 to 20% by weight of the polypropylene resin (X) having the following characteristics (i) to (v) (however, the propylene-ethylene resin composition (A) and the polypropylene A polypropylene-based resin composition for injection molding containing (the total blending ratio of the resin (X) is 100% by weight) is provided.
Characteristic (i): MFR is 8 to 100 g / 10 minutes.
Characteristic (ii): The flexural modulus is 1100 to 1500 MPa.
Characteristic (iii): Charpy impact strength at 0 ° C. is 4.5 kJ / m ² or more.
Characteristic (iv): The amount of n-hexane extracted is 1.0 to 5.5 wt%.
Characteristic (v): HAZE by 1 mmt sheet is 90% or more.

Further, according to the second invention of the present invention, in the first invention, the n-hexane extraction amount of the propylene-ethylene resin composition (A) is 1.0 to 5.5 wt%, that is, polypropylene for injection molding. A based resin composition is provided.

Further, according to the third invention of the present invention, in any one of the first and second inventions, the polypropylene-based resin composition for injection molding has the following characteristics (a) to (d) for injection molding. A polypropylene-based resin composition is provided.
Characteristics (a): Charpy impact strength at 0 ° C. is 3.5 kJ / m ² or more.
Characteristic (a): The flexural modulus is 1000 MPa or less.
Characteristics (c): HAZE from a 1 mmt sheet is 55 to 95%.
Characteristic (d): MFR is 10 to 100 g / 10 minutes.

Further, according to the fourth invention of the present invention, there is provided an injection molding member made of the polypropylene resin composition for injection molding according to any one of the first to third inventions.

Further, according to the fifth invention of the present invention, there is provided an injection molding cap member made of the polypropylene resin composition for injection molding according to any one of the first to third inventions.

Further, according to the sixth aspect of the present invention, there is provided an injection-molded hinge cap member made of the polypropylene-based resin composition for injection molding according to any one of the first to third inventions.

The polypropylene-based resin composition for injection molding of the present invention has an excellent balance of flexibility, impact resistance, light-shielding property, whitening resistance, and moldability.

Hereinafter, embodiments of the present invention will be described in detail, but the description of the constituent requirements described below is an example of embodiments of the present invention, and the present invention is limited to these contents. is not it.

The polypropylene-based resin composition for injection molding of the present invention has an ethylene content of 0.1 to 3.0% by weight and a melt flow rate (MFR) of 10 to 150 g in accordance with JIS K7210 (230 ° C., 2.16 kg load). A propylene-containing a propylene-ethylene copolymer (a) having a / 10-minute content and a propylene-ethylene copolymer (b) having an ethylene content of 5 to 20% by weight and an MFR of 1 to 30 g / 10 minutes. The propylene-ethylene resin composition (A), wherein the weight ratio of the propylene-ethylene copolymer (a) and the propylene-ethylene copolymer (b) is 90: 10 to 60:40. 80 to 95% by weight of the substance (A) and 5 to 20% by weight of the polypropylene resin (X) having the following characteristics (i) to (v) (however, the propylene-ethylene resin composition (A) and the polypropylene It is composed of a polypropylene-based resin composition for injection molding, which comprises (the total blending ratio of the resin (X) is 100% by weight).
Characteristic (i): MFR is 8 to 100 g / 10 minutes.
Characteristic (ii): The flexural modulus is 1100 to 1500 MPa.
Characteristic (iii): Charpy impact strength at 0 ° C. is 4.5 kJ / m ² or more.
Characteristic (iv): The amount of n-hexane extracted is 1.0 to 5.5 wt%.
Characteristic (v): HAZE by 1 mmt sheet is 90% or more.

1. 1. Propylene-ethylene copolymer (a)
The propylene-ethylene copolymer (a) used in the present invention satisfies the following properties.
(1) Characteristic 1: MFR
The MFR of the propylene-ethylene copolymer (a) used in the present invention needs to be in the range of 10 to 150 g / 10 minutes, preferably 30 to 120 g / 10 minutes, and more preferably 50 to 100 g / 10 minutes. Minutes.
When it is at least the lower limit value (10 g / 10 minutes) of this MFR range, the molding processability is improved due to the improvement of fluidity, while the one below the upper limit value (150 g / 10 minutes) is a resin composition. Productivity is good, which is economically preferable.
The method of controlling the MFR value is well known, and it can be easily adjusted by adjusting the temperature and pressure which are the polymerization conditions, or by controlling the amount of hydrogenation in the method of adding a chain transfer agent such as hydrogen at the time of polymerization. Can be done.
In the present invention, the MFR of the propylene resin is the method A and the condition M (230) of JIS K7210: 1999 "Test method for melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic plastic". Measured according to ° C., 2.16 kg load), the unit is g / 10 minutes.

(2) Property 2: Ethylene content The ethylene content of the propylene-ethylene copolymer (a) used in the present invention needs to be in the range of 0.1 to 3.0% by weight, preferably 1.0. It is ~ 2.8% by weight, more preferably 1.5 to 2.6% by weight.
When it is at least the lower limit value (0.1% by weight) in this range, the flexibility of the molded product becomes good. Further, when it is not more than the upper limit value (3.0% by weight), the solidification at the time of molding becomes faster due to the increase in the crystallization temperature, and the molding processability becomes good.
The ethylene content can be adjusted by controlling the monomer composition of propylene and ethylene at the time of polymerization.

2. Propylene-ethylene copolymer (b)
The propylene-ethylene copolymer (b) used in the present invention satisfies the following properties.
(1) Characteristic 1: MFR
The MFR of the propylene-ethylene copolymer (b) used in the present invention needs to be in the range of 1 to 30 g / 10 minutes, preferably 3 to 20 g / 10 minutes, and more preferably 5 to 15 g / 10 minutes. Minutes.
When it is at least the lower limit value (1 g / 10 minutes) in this range, the dispersibility in the propylene-ethylene copolymer (a) is improved, and it is possible to suppress the occurrence of fish eyes in the molded product. .. Further, when it is not more than the upper limit value (30 g / 10 minutes), the low crystal component is less likely to bleed on the surface, so that the appearance after heating is improved.

(2) Property 2: Ethylene content The ethylene content of the propylene-ethylene copolymer (b) used in the present invention needs to be in the range of 5 to 20% by weight, preferably 7 to 15% by weight, more. It is preferably 8 to 13% by weight.
When it is at least the lower limit value (5% by weight) in this range, the impact resistance of the molded product is improved. Further, when it is not more than the upper limit value (20% by weight), the compatibility with the propylene-ethylene copolymer (a) is improved, and the whitening resistance of the molded product is improved.

3. 3. Propylene-ethylene resin composition (A)
The propylene-ethylene resin composition (A) used in the present invention satisfies the following characteristics.
(1) Characteristic 1: Weight ratio of propylene-ethylene copolymer (a) and propylene-ethylene copolymer (b) The propylene-ethylene resin composition used in the present invention is the propylene-ethylene copolymer (a). And the propylene-ethylene copolymer (b), where the weight ratio of the propylene-ethylene copolymer (a) to the propylene-ethylene copolymer (b) is 90: 10-60. It needs to be in the range of: 40, preferably 87:13 to 65:35, more preferably 84:16 to 70:30.
When it is not more than the upper limit value (90) of the weight ratio of the propylene-ethylene copolymer (a), the impact resistance of the molded product is improved and the transparency is further improved. For example, HAZE of 1 mmt is as high as 60% or less. Shows whitening resistance. On the other hand, when it is at least the lower limit value (60), the solidification at the time of molding becomes faster and the molding processability is improved.

The ratio of the propylene-ethylene copolymers (a) and (b) and the ethylene content are measured by the CFC-IR method. The method is as follows.

(I) Analytical device to be used (a) Cross sorting device CFC T-100 manufactured by Dia Instruments Co., Ltd. (abbreviated as CFC)
(B) Fourier transform infrared absorption spectrum analysis FT-IR, 1760X manufactured by PerkinElmer Co., Ltd.
The fixed wavelength infrared spectrophotometer attached as a CFC detector is removed, and an FT-IR is connected instead, and this FT-IR is used as a detector.
The transfer line from the outlet of the solution eluted from CFC to FT-IR shall be 1 m long and maintained at a temperature of 140 ° C. throughout the measurement. The flow cell attached to the FT-IR has an optical path length of 1 mm and an optical path width of 5 mmφ, and is maintained at a temperature of 140 ° C. throughout the measurement.
(C) Gel permeation chromatography (GPC)
The GPC column in the latter part of the CFC is used by connecting three AD806MS manufactured by Showa Denko in series.

(Ii) CFC measurement conditions (a) Solvent: Ortodichlorobenzene (ODCB)
(B) Sample concentration: 4 mg / ml
(C) Injection amount: 0.4 ml
(D) Crystallization: The temperature is lowered from 140 ° C. to 40 ° C. over about 40 minutes.
(E) Sorting method:
The sorting temperature at the time of temperature-raising elution sorting is 40 ° C., 100 ° C., and 140 ° C., and the separated fractions are separated into three fractions in total.
The elution ratio (unit: weight%) of the component eluted at 40 ° C. or lower (fraction 1), the component eluted at 40 to 100 ° C. (fraction 2), and the component eluted at 100 to 140 ° C. (fraction 3), respectively. It is defined as W40, W100, W140. W40 + W100 + W140 = 100. In addition, each separated fraction is automatically transported to the FT-IR analyzer as it is.
(F) Solvent flow rate at elution: 1 ml / min

(Iii) FT-IR measurement conditions After the elution of the sample solution starts from the GPC in the subsequent stage of CFC, FT-IR measurement is performed under the following conditions, and GPC-IR data is collected for each of the above fractions 1 to 3. ..
(A) Detector: MCT
(B) Resolution: 8 cm ^-1
(C) Measurement interval: 0.2 minutes (12 seconds)
(D) Cumulative number of times per measurement: 15 times

(Iv) Post-treatment and analysis of measurement results The elution amount and molecular weight distribution of the components eluted at each temperature are determined by using the absorbance of ^{2945 cm-1 obtained by FT-IR as a chromatogram.} The elution amount is standardized so that the total elution amount of each elution component is 100%. The conversion from the holding capacity to the molecular weight is performed using a calibration curve prepared in advance using standard polystyrene.
The standard polystyrenes used are all the following brands manufactured by Tosoh Corporation.
F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000.
A calibration curve is created by injecting 0.4 ml of a solution dissolved in ODCB (containing 0.5 mg / ml BHT) so that each is 0.5 mg / ml. The calibration curve uses a cubic equation obtained by approximating with the least squares method.
For conversion to molecular weight, a general-purpose calibration curve is used with reference to "Size Exclusion Chromatography" (Kyoritsu Shuppan) by Sadao Mori. The following numerical values are used for the viscosity formula ([η] = K × M ^α ) used at that time.
(A) When creating a calibration curve using standard polystyrene K = 0.000138, α = 0.70
(A) When measuring a sample of a propylene-ethylene resin composition K = 0.000103, α = 0.78
The molecular weight of each eluted portion separated by elution is defined as Mw (40), Mw (100), and Mw (140). The overall molecular weight distribution was calculated by summing up the data obtained by the three divisions. From this, the content (% by weight) of the components having a weight average molecular weight of 3,000 or less, which will be described later, can be obtained by integrating.
For the ethylene content distribution of each eluted component (distribution of ethylene content along the molecular weight axis), ^{the ratio of the absorbance of 2956 cm -1} obtained by FT-IR to the absorbance of 2927 cm ^-1 was used, and polyethylene, polypropylene, and ^{13 were used.} Using ethylene propylene rubber (EPR) whose ethylene content is known by C-NMR measurement and a mixture thereof, it is converted to ethylene content (% by weight) by a calibration line prepared in advance. Ask.

The ratio (Wc) of the propylene-ethylene copolymer (a) part (EP1) and the propylene-ethylene copolymer (b) part (EP2) in the propylene-ethylene resin composition (A) in the present invention is. Using the results measured by the above method, it is theoretically defined by the following formula (I) and obtained by the following procedure.
Wc (% by weight) = W40 x A40 / B40 + W100 x A100 / B100 ... (I)

In the formula (I), W40 and W100 are the elution ratios (unit:% by weight) in each of the above-mentioned fractions, and A40 and A100 are the average ethylene contents (actually measured) in each fraction corresponding to W40 and W100. Unit:% by weight), and B40 and B100 are ethylene contents (unit:% by weight) of EP1 and EP2 contained in each fraction. How to obtain A40, A100, B40, and B100 will be described later.
The meaning of the formula (I) is as follows. That is, the first term on the right side of the formula (I) is a term for calculating the amount of EP1 contained in fraction 1 (a portion soluble at 40 ° C.). When the fraction 1 contains only EP2 and does not contain EP1, the W40 directly contributes to the EP2 content derived from the fraction 1 in the whole, but the fraction 1 contains a small amount in addition to the components derived from EP2. Since a component derived from EP1 (a component having an extremely low molecular weight) is also included, it is necessary to correct that portion. Therefore, by multiplying W40 by A40 / B40, the amount derived from the EP2 component in fraction 1 is calculated. For example, when the average ethylene content (A40) of fraction 1 is 15% by weight and the ethylene content (B40) of EP contained in fraction 1 is 20% by weight, 15/20 = 3/4 of fraction 1 (that is, that is). 75% by weight) is derived from EP2, and 1/4 is derived from EP1. The operation of multiplying A40 / B40 in the first term on the right side as described above means that the contribution of EP2 is calculated from the weight% (W40) of fraction 1.

Here, the calculation is further performed in consideration of the following conditions.
(A) As described above, the average ethylene contents corresponding to fractions 1 and 2 obtained by CFC measurement are A40 and A100, respectively (the unit is weight%). How to determine the average ethylene content will be described later.
(A) The ethylene content corresponding to the peak position on the differential molecular weight distribution curve of fraction 1 is defined as B40 (unit is weight%).
Regarding fraction 2, it is considered that the rubber portion is completely eluted at 40 ° C., and it cannot be defined by the same definition. Therefore, in the present invention, B100 = 100 is substantially defined.
B40 and B100 are the ethylene contents of the propylene-ethylene copolymer contained in each fraction, but it is practically impossible to determine this value analytically. The reason is that there is no means to completely separate and separate EP1 and EP2 mixed in the fraction. As a result of examination using various model samples, B40 can well explain the effect of improving the material physical characteristics by using the ethylene content corresponding to the peak position of the differential molecular weight distribution curve of fraction 1. That is, B40 is the ethylene content corresponding to the peak position of the differential molecular weight distribution curve of fraction 1. In addition, B100 has two reasons: it has crystallinity derived from an ethylene chain, and the amount of EP1 contained in these fractions is relatively small compared to the amount of EP1 contained in fraction 1. Approximating to 100 is closer to the actual situation and causes almost no error in calculation. Therefore, the analysis is performed with B100 = 100.

(C) For the above reason, the above ratio (Wc) is obtained according to the following formula (II).
Wc (% by weight) = W40 x A40 / B40 + W100 x A100 / 100 ... (II)
That is, W40 × A40 / B40, which is the first term on the right side of the formula (II), indicates the EP2 content (% by weight) having no crystallinity, and W100 × A100 / 100, which is the second term, indicates the crystallinity. The EP1 content (% by weight) to have is shown.
Here, the average ethylene contents A40 and A100 of the fractions 1 and 2 obtained by B40 and CFC measurement are obtained as follows.
Let B40 be the ethylene content corresponding to the peak position of the differential molecular weight distribution curve. Further, the sum of the product of the weight ratio of each data point and the ethylene content of each data point, which is taken in as data points at the time of measurement, is defined as the average ethylene content A40 of fraction 1. The average ethylene content A100 of fraction 2 is also determined in the same manner.

The significance of setting the above three types of sorting temperatures is as follows.
In the CFC analysis of the present invention, 40 ° C. is a temperature condition necessary and sufficient to separate only a non-crystalline polymer (for example, most of EP2 or a component having an extremely low molecular weight in EP1). It has a certain significance. 100 ° C. refers to a component that is insoluble at 40 ° C. but soluble at 100 ° C. (for example, a component having crystallinity due to the chain of ethylene and / or propylene in a propylene-ethylene copolymer, and crystals. The temperature is sufficient to elute only low-quality EP1). 140 ° C. means a component that is insoluble at 100 ° C. but soluble at 140 ° C. (for example, a component having particularly high crystallinity in EP1 and an extremely high molecular weight and extremely high ethylene crystallinity in EP2. The temperature is sufficient to elute only the component) and recover the entire amount of the propylene-ethylene resin composition used for the analysis.
Since W140 does not contain any EP2 component or is present in an extremely small amount and can be substantially ignored, it is excluded from the calculation of the ratio of EP2 and the ethylene content of EP2.
The ethylene content of the propylene-ethylene copolymer (a) part (EP1) and the propylene-ethylene copolymer (b) part (EP2) in the propylene-ethylene resin composition (A) in the present invention can be determined by the above method. It is calculated by the following formula (III) using the result measured in.
Ethylene content of EP (% by weight) = (W40 x A40 + W100 x A100) / Wc ... (III)

The catalyst used for obtaining the propylene-ethylene copolymer (a) and the propylene-ethylene copolymer (b) used in the present invention is not particularly limited, and known catalysts can be used. be.
For example, a so-called Ziegler-Natta catalyst or a metallocene catalyst in which a titanium compound and organoaluminum are combined (for example, described in JP-A-5-295022) can be used.
In the present invention, a propylene-ethylene resin composition having a good balance between flexibility and impact resistance is particularly preferable, and therefore a Ziegler-Natta catalyst having high stereoregularity is generally more preferable.

Regarding the production process of the propylene-ethylene copolymer (a) and the propylene-ethylene copolymer (b), any method may be used as long as the above-mentioned properties are satisfied. The phase method process is preferable, and among them, it is more preferable to produce by a process having a horizontal reactor having a stirrer rotating around the horizontal axis in a form in which the heat of polymerization is removed by utilizing the latent heat of evaporation of liquefied propylene.
Further, the mixture of the propylene-ethylene copolymer (a) and the propylene-ethylene copolymer (b) may be produced by any method as long as the above-mentioned characteristics are satisfied, but the two-stage continuous weight is used. By adopting the legality, the dispersion of the propylene-ethylene copolymer (b) with respect to the propylene-ethylene copolymer (a) becomes good, and the whitening resistance is further improved.

(2) Characteristic 2: n-hexane extraction amount The n-hexane extraction amount of the propylene-ethylene resin composition (A) used in the present invention is preferably in the range of 1.0 to 5.5 wt%, more preferably. Is 1.5 to 5.0 wt%, more preferably 2.0 to 4.5 wt%.
When it is at least the lower limit value (1.0 wt%) in this range, the impact resistance of the molded product is improved, while when it is at least the upper limit value (5.5 wt%), the food hygiene is improved.

4. Polypropylene resin (X)
The polypropylene resin (X) used in the present invention satisfies the following characteristics.
(1) Characteristic 1: MFR
The MFR of the polypropylene resin (X) used in the present invention needs to be in the range of 8 to 100 g / 10 minutes, preferably 10 to 75 g / 10 minutes, and more preferably 20 to 50 g / 10 minutes. be.
When it is at least the lower limit value (8 g / 10 minutes) in this range, the molding processability becomes good due to the improvement of fluidity, while when it is at least the upper limit value (100 g / 10 minutes), the impact resistance becomes good. ..

(2) Characteristic 2: Flexural modulus The flexural modulus of the polypropylene resin (X) used in the present invention needs to be in the range of 1100 to 1500 MPa, preferably 1200 to 1450 MPa, and more preferably 1300 to 1300 MPa. It is 1400 MPa.
When it is at least the lower limit value (1100 MPa) in this range, solidification at the time of molding becomes faster and the moldability is improved, while when it is at least the upper limit value (1500 MPa), the impact resistance of the molded product is improved.

(3) Characteristics: Charpy impact strength at 0 ° C. The Charpy impact strength of the polypropylene resin (X) used in the present invention at 0 ° C needs to be in the range of ^{4.5 kJ / m 2 or more, more preferably.} It is 5.5 kJ / m ² or more.
When it is at least the lower limit value (4.5 kJ / m ² ) in this range, the impact resistance of the molded product in a refrigerated environment is improved.

(4) Characteristic 4: n-hexane extraction amount The n-hexane extraction amount of the polypropylene resin (X) used in the present invention needs to be in the range of 1.0 to 5.5 wt%, and is preferably 1. It is 5 to 5.0 wt%, more preferably 2.0 to 4.5 wt%.
When it is at least the lower limit value (1.0 wt%) in this range, the impact resistance of the molded product is improved, while when it is at least the upper limit value (5.5 wt%), the food hygiene is improved.

(5) HAZE with characteristics of 5: 1 mmt
The HAZE of the polypropylene resin (X) used in the present invention at 1 mmt needs to be in the range of 90% or more, preferably 95% or more, and more preferably 98% or more.
When it is at least the lower limit value (90%) in this range, the light-shielding property becomes high, and the effect of suppressing the deterioration of ultraviolet rays in the contents is improved.

The polypropylene resin (X) used in the present invention may be homopolypropylene or a propylene-α-olefin copolymer containing another α-olefin such as ethylene as a comonomer, as long as the above-mentioned characteristics are satisfied.

5. Polypropylene resin composition for injection molding (1) Characteristic 1: Blending ratio of polypropylene resin (X) The polypropylene resin composition for injection molding of the present invention is the propylene-ethylene resin composition (A) 80 to 95 weight by weight. %, preferably 85 to 95% by weight, more preferably 90 to 95% by weight, and 5 to 20% by weight of the polypropylene resin (X), preferably 5 to 15% by weight, more preferably 5 to 10% by weight. include. However, the total mixing ratio of the propylene-ethylene resin composition (A) and the polypropylene resin (X) is 100% by weight.
When the blending ratio of the propylene-ethylene resin composition (A) and the polypropylene resin (X) is within the above range, the polypropylene resin composition for injection molding of the present invention has flexibility, impact resistance, and light shielding property. It has an excellent balance between whitening resistance and moldability.

(2) Characteristic 2: Charpy impact strength at 0 ° C. The Charpy impact strength of the polypropylene-based resin composition for injection molding according to the present invention at 0 ° C is preferably in the range of ^{3.5 kJ / m 2 or more, more preferably.} Is 4.5 kJ / m ² or more, more preferably 5.0 kJ / m ² or more.
When it is at least the lower limit value (3.5 kJ / m ² ) in this range, the impact resistance of the molded product in a refrigerated environment is improved.

(3) Characteristic 3: Flexural modulus The flexural modulus of the polypropylene-based resin composition for injection molding according to the present invention is preferably in the range of 1000 MPa or less, more preferably 950 MPa or less, and further preferably 900 MPa or less. Is.
When it is not more than the upper limit value (1000 MPa) in this range, good flexibility can be obtained.

(4) HAZE with characteristics 4: 1 mmt
The HAZE in 1 mmt of the polypropylene resin composition for injection molding according to the present invention is preferably in the range of 55 to 95%, more preferably 60 to 90%, and further preferably 65 to 85%. ..
When it is at least the lower limit value (55%) in this range, the light-shielding property is high and the effect of suppressing ultraviolet deterioration of the contents is improved, while when it is at least the upper limit value (95%), the whitening resistance is good. It becomes.

(5) Characteristic 5: MFR
The MFR of the polypropylene-based resin composition for injection molding according to the present invention is preferably in the range of 10 to 100 g / 10 minutes, more preferably 20 to 75 g / 10 minutes, and further preferably 30 to 50 g / 10 minutes. Minutes.
When it is at least the lower limit value (10 g / 10 minutes) in this range, the moldability and dispersibility in the molded product are improved due to the improvement of fluidity, while when it is at least the upper limit value (100 g / 10 minutes), it is said. Impact resistance is improved.

6. Nucleating agent By adding a nucleating agent to the polypropylene-based resin composition for injection molding of the present invention, a molded product having better transparency and impact resistance can be obtained.
As the nucleating agent, an organic phosphoric acid ester metal salt, an organic monocarboxylic acid metal salt, an organic dicarboxylic acid metal salt, a polymer nucleating agent, dibenzylidene sorbitol or a derivative thereof, a metal salt of diterponic acids and the like are used.

Examples of the organic phosphate metal salt include sodium-2,2'-methylene-bis (4,6-di-t-butylphenyl) phosphate and sodium-2,2'-ethylidene-bis (4,6). -Di-t-butylphenyl) phosphate, lithium-2,2'-methylene-bis (4,6-di-t-butylphenyl) phosphate, lithium-2,2'-ethylidene-bis (4,6) -Di-t-butylphenyl) phosphate, sodium-2,2'-ethylidene-bis (4-i-propyl-6-t-butylphenyl) phosphate, lithium-2,2'-methylene-bis (4) -Methyl-6-t-butylphenyl) phosphate, lithium-2,2'-methylene-bis (4-ethyl-6-t-butylphenyl) phosphate, sodium-2,2'-butylidene-bis (4) , 6-Di-Methylphenyl) Phosphate, Sodium-2,2'-Butylidene-bis (4,6-di-t-Butylphenyl) Phosphate, Sodium-2,2'-t-octylmethylene-bis (4,6-di-t-butylphenyl) 4,6-di-methylphenyl) phosphate, sodium-2,2'-t-octylmethylene-bis (4,6-di-t-butylphenyl) phosphate, calcium-bis [(2,2'-) Methylene-bis (4,6-di-t-butylphenyl) phosphate], magnesium-bis [2,2'-methylene-bis (4,6-di-t-butylphenyl) phosphate], barium-bis [2,2'-methylene-bis (4,6-di-t-butylphenyl) phosphate], sodium-2,2'-methylene-bis (4-methyl-6-t-butylphenyl) phosphate, Sodium-2,2'-methylene-bis (4-ethyl-6-t-butylphenyl) phosphate, sodium-2,2'-ethylidene-bis (4-s-butyl-6-t-butylphenyl) phos Fate, sodium-2,2'-methylene-bis (4,6-di-methylphenyl) phosphate, sodium-2,2'-methylene-bis (4,6-di-ethylphenyl) phosphate, potassium- 2,2'-Etilidene-bis (4,6-di-t-butylphenyl) phosphate, calcium-bis [2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate], Magnesium-bis [2,2'-ethylidene-bis (4,6-di-t-butyl) Ruphenyl) Phenyl Phenyl], Barium-Bis [2,2'-Etilidene-Bis (4,6-di-t-Butylphenyl) Phenyl Phenyl], Aluminum-Tris [2,2'-Methylene-Bis (4,6) -Di-t-butylfel) phosphate], aluminum-tris [2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate], aluminum hydrooxy-bis [2,2'- Methylene-bis (4,6-di-t-butylphenyl) phosphate], aluminum dihydrooxy-2,2'-methylene-bis (4,6-di-t-butylphenyl) phosphate and the like are exemplified. ..

Examples of the organic monocarboxylic acid metal salt include salts of metals such as benzoic acid and allyl-substituted acetic acid, and specifically, benzoic acid, p-isopropylbenzoic acid, o-tertiary butylbenzoic acid, and the like. Examples thereof include pt-butylbenzoic acid, monophenylacetic acid, diphenylacetic acid, phenyldimethylacetic acid, adipic acid and Li, Na, Mg, Ca, Ba and Al salts thereof. Examples of the organic dicarboxylic acid metal salt include succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, phthalic acid, cyclohexanecarboxylic acid, norbornandicarboxylic acid and their Li, Na, Mg, Ca, Ba and Al. Examples include salt. Examples of the polymer nucleating agent include polyvinylcyclohexane and poly-3-methyl-butene-1.

Examples of the dibenzylidene sorbitol or a derivative thereof include 1,3,2,4-dibenzylidene sorbitol, 1,3-benzylidene-2,4-p-methylbenzylidene sorbitol, and 1,3-benzylidene-2,4-. p-ethylbenzylidene sorbitol, 1,3-p-methylbenzylidene-2,4-benzylidene sorbitol, 1,3-p-ethylbenzylidene-2,4-benzylidene sorbitol, 1,3-p-methylbenzylidene-2,4 -P-ethylbenzylidene sorbitol, 1,3-p-ethylbenzylidene-2,4-p-methylbenzylidene sorbitol, 1,3,2,4-di (p-methylbenzylidene) sorbitol, 1,3,2,4 -Di (p-ethylbenzylidene) sorbitol, 1,3,2,4-di (pn-propylbenzylidene) sorbitol, 1,3,2,4-di (pi-propylbenzylidene) sorbitol, 1, 3,2,4-di (pn-butylbenzylidene) sorbitol, 1,3,2,4-di (ps-butylbenzylidene) sorbitol, 1,3,2,4-di (pt-) Butylbenzylidene) sorbitol, 1,3,2,4-di (p-methoxybenzylidene) sorbitol, 1,3,2,4-di (p-ethoxybenzylidene) sorbitol, 1,3-benzylidene-2,4-p − Chlorbenzylidene sorbitol, 1,3-p-chlorobenzylidene-2,4-benzylidene sorbitol, 1,3-p-chlorobenzylidene-2,4-p-methylbenzylidene sorbitol, 1,3-p-chlorbenzylidene-2 , 4-p-ethylbenzylidene sorbitol, 1,3-p-methylbenzylidene-2,4-p-chlorobenzylidene sorbitol, 1,3-p-ethylbenzylidene-2,4-p-chlorobenzylidene sorbitol, 1,3 , 2,4-Di (p-chlorobenzylidene) sorbitol, 1,2,3-trideoxy-4,6: 5,7-bis-O-[(4-propylphenyl) methylene] -nonitol and the like. Can be done. Particularly preferred are 1,3,2,4-dibenzylidene sorbitol, 1,3,2,4-di (p-methylbenzylidene) sorbitol, 1,3-p-chlorbenzylidene-2,4-p-methylbenzylidene. Examples thereof include sorbitol, 1,2,3-trideoxy-4,6: 5,7-bis-O-[(4-propylphenyl) methylene] -nonitol and the like.

The metal salt of diterpene acids is a reaction product of diterpenic acids and a predetermined metal compound such as a magnesium compound and an aluminum compound. Diterpenic acid is a rosin generally known as a natural resin obtained from pine plants, specifically natural rosins such as gum rosin, tall oil rosin, wood rosin; disproportionated rosin, hydride rosin, dehydrogenated. Various modified rosins such as rosin, polymerized rosin, α, β-ethylenic unsaturated carboxylic acid-modified rosin; and purified products of the natural rosin and modified rosin can be obtained as raw materials. Examples of diterpenic acids include pimaric acid, sandaracopimal acid, palastolic acid, isopimal acid, abietic acid, dehydroabietic acid, neoavietic acid, dihydropimal acid, dihydroabietic acid, tetrahydroabietic acid and the like.

Of these, preferred nucleating agents are organic phosphoric acid ester metal salts and organic dicarboxylic acid metal salts, and more preferably sodium-2,2'-methylene-bis (4,6-di-t-butylphenyl). Phenyl Phenyl, Sodium-2,2'-Etilidene-Bis (4,6-di-t-Butylphenyl) Phenyl Phenyl, Aluminum-Tris [2,2'-Methylene-Bis (4,6-di-t-Butylphenyl) ) Phosphate], Aluminum Hydrooxy-Bis [2,2'-Methylene-Bis (4,6-di-t-Butylphenyl) Phenyl Phenyl], Aluminum Dihydrooxy-2,2'-Methylene-Bis (4, A phosphoric acid ester metal salt having a crosslinked substituted aromatic group such as 6-di-t-butylphenyl) phosphate, or sodium 2-cyclohexanedicarboxylate, sodium 1,2-norbornane dicarboxylate, 1,2-norbornane. Examples thereof include alicyclic hydrocarbon dicarboxylic acid metal salts such as magnesium dicarboxylate. Examples of the metal salt include lithium, sodium, potassium, calcium, magnesium, aluminum salt and the like, and more preferably a group 1 metal such as lithium, sodium and potassium.
The content of the nucleating agent is preferably 0.01 to 0.7 parts by weight, more preferably 0.01 to 0.7 parts by weight, based on 100 parts by weight of the total of the propylene-ethylene resin composition (A) and the polypropylene resin (X). It is 0.05 to 0.5 parts by weight. When the content of the nucleating agent is 0.01 parts by weight or more, the effect of improving transparency and impact resistance can be sufficiently obtained, while when it is 0.7 parts by weight or less, the cost vs. the above effect (cost).・ It is advantageous in terms of performance).
In addition, these nucleating agents may be used in combination of 2 or more types.

7. Other Additives The polypropylene-based resin composition for injection molding of the present invention has various additives such as heat-resistant stabilizers, antioxidants, weather-resistant stabilizers, ultraviolet absorbers, and copper damage, as long as the performance is not impaired. It can contain an inhibitor, an antistatic agent, a flame retardant, a hydrophilic agent, a slip agent, an anti-blocking agent, an antifogging agent, a colorant, a filler, a polyethylene, an elastomer, a petroleum resin, an antibacterial agent and the like.
Further, if MFR adjustment is required, an organic peroxide can be blended.

8. Method for Producing Polypropylene Resin Composition for Injection Molding The polypropylene resin composition for injection molding of the present invention comprises the above-mentioned propylene-ethylene resin composition (A), polypropylene resin (X), and if necessary, a nucleating agent. And other additives and other various compounding ingredients are obtained by mixing using a normal mixing device such as a polypropylene mixer (trade name), a super mixer, a ribbon blender, a tumbler mixer, a Banbury mixer, or the like. be able to. The obtained mixture is pelletized at a melt-kneading temperature of 150 to 300 ° C., preferably 180 to 250 ° C. using a single-screw or twin-screw extruder, a roll, or the like to obtain a pellet-like composition. You can also.

9. Injection-molded article The injection-molded article (injection-molded article) of the present invention is obtained by subjecting the above-mentioned polypropylene-based resin composition for injection molding to an ordinary injection molding method, an injection compression molding method, an injection foam molding method, or the like.
Specific examples of this injection-molded product include food containers (pudding containers, jelly containers, yogurt containers, other dessert containers, prepared food containers, tea bowl steaming containers, containers for instant foods such as instant ramen, etc. , Rice container, retort container, lunch container, etc.), Beverage container (beverage bottle, chilled coffee container, one-hand cup container, other beverage container, etc.), cap (hinge cap, pet bottle cap, 1 piece cap, 2 piece cap, Instant coffee caps, seasoning caps, cosmetic container caps, etc.), various other containers (ink containers, cosmetic containers, shampoo containers, detergent containers, etc.), daily necessities (clothing cases, buckets, washbasins, writing utensils, containers, toys, etc.) Cooking utensils, other various cases, etc.).

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these examples. The physical property measurement method and the materials used are as follows.

1. 1. Evaluation method of physical properties (1) MFR
In the present invention, the melt flow rate (MFR) is measured according to JIS K-7210-1999 (230 ° C., 2.16 kg load).
(2) Bending elastic modulus A test piece was molded by an injection molding method, and after molding, it was left in a constant temperature room adjusted to a room temperature of 23 ° C. and a relative humidity of 50% for 24 hours, and then determined in accordance with JIS K7171 (ISO178). ..
(3) Charpy impact strength A test piece is molded by an injection molding method, and after molding, it is left in a thermostatic chamber adjusted to a room temperature of 23 ° C. and a relative humidity of 50% for 24 hours, and then placed in a constant temperature bath at 0 ° C. for 1 hour or longer. It was adjusted and obtained in accordance with JIS K7111.
(4) Transparency (Haze)
A flat plate having a thickness of 1 mmt was molded by an injection molding method, and after molding, it was left in a constant temperature room adjusted to a room temperature of 23 ° C. and a relative humidity of 50% for 24 hours, and then obtained in accordance with JIS K7136 (ISO14782).
(5) Extraction amount of n-hexane A sheet of 120 mm × 120 mm × 0.1 mmt was prepared by press molding at 200 ° C., and 2.5 g of this sheet was cut out and used as a test piece. The test piece was placed in 1 L of n-hexane adjusted to 50 ° C., and extraction was performed for 2 hours with stirring. After extraction, the test piece was taken out from the n-hexane solution, and then n-hexane was evaporated from the n-hexane solution to determine the weight ratio of the components extracted into the n-hexane solution.
(6) Whitening Whitening when a flat plate with a thickness of 1 mmt is molded by an injection molding method, left in a thermostatic chamber adjusted to a room temperature of 23 ° C. and a relative humidity of 50% for 1 week or more, and then the molded product is bent. The degree was visually evaluated. When whitening could not be confirmed, it was marked with ◯, when slight whitening was confirmed, it was marked with Δ, and when marked whitening occurred, it was marked with ×.
(7) Product Appearance A flat plate having a thickness of 1 mmt was molded by an injection molding method, and the degree of appearance (color unevenness) of the molded product was visually evaluated. If there is no color unevenness, it is marked with ○, and if there is color unevenness, it is marked with ×.

2. Materials used (1) Propylene-ethylene resin composition (A)
The propylene-ethylene resin composition (A) obtained in Production Example 1 below, that is, a propylene-based polymer (referred to as PP-1) was used.

<Manufacturing Example 1 (PP-1)>
(I) Production of Solid Catalyst Component (A) A 10 L capacity autoclave equipped with a stirrer was sufficiently replaced with nitrogen, and 2 L of purified toluene was introduced. To this, at room temperature, 200 g of _{Mg (OEt) 2} and 1 L of _{TiCl 4 were added.} The temperature was raised to 90 ° C. and 50 ml of di-n-butyl phthalate was introduced. Then, the temperature was raised to 110 ° C. and a 3 hr reaction was carried out. The reaction product was thoroughly washed with purified toluene. Then, purified toluene was introduced to adjust the total liquid volume to 2 L. 1 L of TiCl ₄ was added at room temperature, the temperature was raised to 110 ° C., and a 2 hr reaction was carried out. The reaction product was thoroughly washed with purified toluene. Then, purified toluene was introduced to adjust the total liquid volume to 2 L. 1 L of TiCl ₄ was added at room temperature, the temperature was raised to 110 ° C., and a 2 hr reaction was carried out. The reaction product was thoroughly washed with purified toluene. Further, using purified n-heptane, toluene was replaced with n-heptane to obtain a slurry of solid components. When a part of this slurry was sampled and analyzed, the Ti content of the solid component was 2.7% by weight.
Next, an autoclave having a capacity of 20 L equipped with a stirrer was sufficiently replaced with nitrogen, and 100 g of the slurry of the solid component was introduced as a solid component. Purified n-heptane was introduced to adjust the concentration of the solid component to 25 g / L. 50 ml of SiCl ₄ was added, and a 1 hr reaction was carried out at 90 ° C. The reaction product was thoroughly washed with purified n-heptane.
Then, purified n-heptane was introduced to adjust the liquid level to 4 L. Here, dimethyl divinyl silane 30 _ml, was added 80g as (i-Pr) 2 Si ( OMe) 2 to 30 ml, _Et 3 Al of n- heptane dilution _Et 3 Al, were 2hr reaction at 40 ° C..
The reaction product was thoroughly washed with purified n-heptane, and a part of the obtained slurry was sampled, dried and analyzed. As a result, Ti was 1.2% by weight as a solid component, (i-Pr) _2. Si (OMe) ₂ was contained in an amount of 8.8% by weight.
Further, using the solid component obtained above, prepolymerization (pre-activation treatment) was carried out by the following procedure. Purified n-heptane was introduced into the above slurry to adjust the concentration of the solid component to 20 g / L.
Then, after cooling the slurry to 10 ° C., 10 g was added n- heptane dilution of _Et 3 Al as _Et 3 Al, were fed over 4hr of propylene 280 g. After the supply of propylene was completed, the reaction was continued for another 30 minutes. The gas phase was then thoroughly replaced with nitrogen and the reaction product was thoroughly washed with purified n-heptane.
The obtained slurry was taken out from the autoclave and vacuum dried to obtain a pre-activated solid catalyst component (A). This solid catalyst component contained 2.5 g of polypropylene per 1 g of the solid component. Further, the portion of the solid catalyst component (A) excluding polypropylene contained 1.0% by weight of Ti and 8.2% by weight of _{(i-Pr) 2} Si (OMe) _2.

(Ii) Production of propylene-based polymer A propylene-based polymer was produced by a two-stage polymerization method using a polymerization reactor composed of two gas-phase fluidized beds.
The pre-activated solid catalyst component (A) is continuously supplied to the first reactor (internal volume 2.19 m ³ _{) at 0.26 g / hr and Et 3} Al as an organoaluminum compound at 5.2 g / hr. bottom. Hydrogen / ethylene = 0.056 mol, respectively, of hydrogen and ethylene in the polymer while maintaining the conditions of reaction temperature 75 ° C., reaction pressure 3.0 MPa, empty tower speed 0.35 m / s, and polypropylene powder bed weight 40 kg. The propylene-ethylene copolymer (a) portion was obtained by continuously supplying the mixture at a ratio of ethylene / propylene = 0.013 mol.

Next, the obtained polymer was transferred to a second reactor (internal volume 2.19 m ³ ), a reaction temperature of 80 ° C., a reaction pressure of 2.5 MPa, an empty tower speed of 0.50 m / s, and a bed weight of polypropylene powder. While maintaining the condition of 60 kg, hydrogen and ethylene were continuously supplied into the polymer at a hydrogen / propylene = 0.032 mol ratio and an ethylene / propylene = 0.071 mol ratio, respectively, to obtain a propylene-based polymer (PP-1). Got
In order to adjust the reaction amount of the propylene-ethylene copolymer, ethanol was supplied as a polymerization activity inhibitor at an ethanol / Al = 0.72 molar ratio.
The MFR of the propylene-ethylene copolymer (a) part was 88.0 g / 10 minutes, and the ethylene content was 2.2% by weight. The MFR of the propylene-based polymer (PP-1) was 44.0 g / 10 minutes, and the ethylene content was 4.0% by weight. Here, when the index for the propylene-ethylene copolymer (b) portion produced in the second stage was calculated, the production amount was 33% of the total weight, the MFR was 10.7 g / 10 minutes, and ethylene. The content was 7.5% by weight.

Further, a propylene-ethylene resin composition (A), that is, a propylene-based polymer (referred to as PP-2) was used.
(PP-2) Propropylene ethylene copolymer: Wintec PP WSX02 (trade name manufactured by Japan Polypropylene Corporation), catalyst: metallocene catalyst, MFR: 25 g / 10 minutes, ethylene content: 3.4% by weight

(2) Polypropylene resin (X)
As the polypropylene resin (X), the following polypropylene resins (X-1 to 5) were used.
(X-1) Propylene ethylene block copolymer: Novatec PP BC03GN (trade name manufactured by Japan Polypropylene Corporation), catalyst: Ziegler catalyst, MFR: 30 g / 10 minutes, flexural modulus: 1350 MPa
(X-2) Propylene ethylene block copolymer: Novatec PP NBC03HRA (trade name manufactured by Japan Polypropylene Corporation), catalyst: Ziegler catalyst, MFR: 30 g / 10 minutes, flexural modulus: 980 MPa
(X-3) Propylene ethylene block copolymer: Novatec PP BC6D (trade name manufactured by Japan Polypropylene Corporation), catalyst: Ziegler catalyst, MFR: 2.5 g / 10 minutes, flexural modulus: 1150 MPa
(X-4) Propylene ethylene block copolymer: Novatec PP BC3HF (trade name manufactured by Japan Polypropylene Corporation), catalyst: Ziegler catalyst, MFR: 8.5 g / 10 minutes, flexural modulus: 1200 MPa
(X-5) Propylene ethylene block copolymer: Novatec PP BC02NC (trade name manufactured by Japan Polypropylene Corporation), catalyst: Ziegler catalyst, MFR: 20 g / 10 minutes, flexural modulus: 1400 MPa
(X-6) Propylene homopolymer: Novatec PP MA04A (trade name manufactured by Japan Polypropylene Corporation), catalyst: Ziegler catalyst, MFR: 40 g / 10 minutes, flexural modulus: 2000 MPa

(3) Nucleating agent (i) Nucleating agent (B-1): Trade name manufactured by ADEKA Corporation, ADEKA STUB NA21, organic phosphoric acid ester metal salt-based nucleating agent

[Example 1]
(1) Production of Polypropylene Resin Composition As the propylene-ethylene resin composition (A), 95% by weight of the (PP-1) powder obtained in Production Example 1 and pellets (X-) of polypropylene resin (X). 1) 0.2 parts by weight of the nucleating agent (B-1) and 0.05 weight by weight of the neutralizing agent calcium stearate with respect to 5% by weight and 100 parts by weight of (PP-1) and (X-1) in total. Part, pentaerythrityl-tetrakis [3- (3,5-t-butyl-4-hydroxyphenyl) propionate], a phenolic antioxidant (trade name manufactured by BASF, Irganox 1010; hereinafter abbreviated as RA1010) 0 .05 parts by weight, phosphorus-based antioxidant tris (2,4-di-t-butylphenyl) phosphat (trade name manufactured by BASF, Irgaphos 168; hereinafter abbreviated as RA168) 0.05 parts by weight, slip agent As a result, 0.08 part by weight of oleic acid amide was added, and the mixture was sealed with a super mixer and mixed for 3 minutes.
Then, the obtained powder mixture was granulated at a cylinder temperature of 200 ° C., a screw rotation speed of 150 rpm, and an extrusion rate of 15 kg / h while nitrogen-sealing the hopper using a twin-screw extruder TEM35 manufactured by Toshiba Machine Co., Ltd., and polypropylene. Pellets of the based resin composition were obtained. The MFR of the obtained polypropylene resin composition was 43 g / 10 minutes.
The propylene-ethylene resin composition (A), which is the propylene polymer (PP-1) powder obtained in Production Example 1, and the propylene-ethylene copolymer (a) in the resin composition (A). The composition of the propylene-ethylene copolymer (b) is shown in Table 1.

(2) Manufacture of injection molded product (injection molded product) The pellet of the polypropylene-based resin composition obtained above is supplied to an injection molding machine EC100 manufactured by Toshiba Machine Co., Ltd., and molded at an injection primary pressure of 50 MPa. The test piece and the test flat plate were molded at a temperature of 200 ° C., a mold cooling water temperature of 40 ° C., and a molding cycle of 15 seconds.
The physical properties of the above-mentioned items (flexural modulus, Charpy impact strength, haze, whitening) were evaluated for the obtained test piece and test flat plate. The results are shown in Table 1.

[Example 2]
The polypropylene-based resin composition and injection were carried out in the same manner as in Example 1 except that 90% by weight of the propylene-based polymer (PP-1) and 10% by weight of the pellets (X-1) of the polypropylene resin (X) were used. A molded product was obtained. The results are shown in Table 1.

[Example 3]
The polypropylene resin composition and injection were carried out in the same manner as in Example 1 except that 80% by weight of the propylene polymer (PP-1) and 20% by weight of the polypropylene resin (X) pellets (X-1) were used. A molded product was obtained. The results are shown in Table 1.

[Example 4]
The polypropylene resin composition was prepared in the same manner as in Example 1 except that 90% by weight of the propylene polymer (PP-1) was used and 10% by weight of (X-4) was used as pellets of the polypropylene resin (X). An injection molded product was obtained. The results are shown in Table 1.

[Example 5]
The polypropylene resin composition was prepared in the same manner as in Example 1 except that 90% by weight of the propylene polymer (PP-1) was used and 10% by weight of (X-5) was used as pellets of the polypropylene resin (X). An injection molded product was obtained. The results are shown in Table 1.

[Example 6]
The polypropylene resin composition was prepared in the same manner as in Example 1 except that 80% by weight of the propylene polymer (PP-1) was used and 20% by weight of (X-5) was used as pellets of the polypropylene resin (X). An injection molded product was obtained. The results are shown in Table 1.

[Comparative Example 1]
A polypropylene-based resin composition and an injection-molded product were obtained in the same manner as in Example 1 except that 100% by weight of the propylene-based polymer (PP-1) was used. The results are shown in Table 1.

[Comparative Example 2]
The polypropylene-based resin composition and injection were carried out in the same manner as in Example 1 except that 75% by weight of the propylene-based polymer (PP-1) and 25% by weight of the pellets (X-1) of the polypropylene resin (X) were used. A molded product was obtained. The results are shown in Table 1.

[Comparative Example 3]
The polypropylene-based resin composition and injection were carried out in the same manner as in Example 1 except that 70% by weight of the propylene-based polymer (PP-1) and 30% by weight of the pellets (X-1) of the polypropylene resin (X) were used. A molded product was obtained. The results are shown in Table 2.

[Comparative Example 4]
The polypropylene resin composition and injection were carried out in the same manner as in Example 1 except that the polypropylene resin (X) pellet (X-1) was used in an amount of 100% by weight without using the propylene-ethylene resin composition (A). A molded product was obtained. The results are shown in Table 2.

[Comparative Example 5]
The polypropylene resin composition was prepared in the same manner as in Example 1 except that 90% by weight of the propylene polymer (PP-1) was used and 10% by weight of (X-2) was used as pellets of the polypropylene resin (X). An injection molded product was obtained. The results are shown in Table 2.

[Comparative Example 6]
The polypropylene resin composition was prepared in the same manner as in Example 1 except that 90% by weight of the propylene polymer (PP-1) was used and 10% by weight of (X-3) was used as pellets of the polypropylene resin (X). An injection molded product was obtained. The results are shown in Table 2.

[Comparative Example 7]
Polypropylene-based in the same manner as in Example 1 except that 90% by weight of (PP-2) was used as the propylene-ethylene resin composition and 10% by weight of (X-1) was used as the pellet of the polypropylene resin (X). A resin composition and an injection molded product were obtained. The results are shown in Table 2.

[Comparative Example 8]
Polypropylene-based in the same manner as in Example 1 except that 80% by weight of (PP-2) was used as the propylene-ethylene resin composition and 20% by weight of (X-1) was used as the pellet of the polypropylene resin (X). A resin composition and an injection molded product were obtained. The results are shown in Table 2.

[Comparative Example 9]
Polypropylene-based in the same manner as in Example 1 except that 90% by weight of (PP-2) was used as the propylene-ethylene resin composition and 20% by weight of (X-6) was used as the pellet of the polypropylene resin (X). A resin composition and an injection molded product were obtained. The results are shown in Table 2.

As is clear from Tables 1 and 2, Examples 1 to 5, which are injection-molded products obtained by using the polypropylene-based resin composition for injection molding of the present invention, have flexibility, impact resistance, light-shielding property, and whitening resistance. It can be seen that the properties and moldability are good.
On the other hand, in Comparative Examples 1 to 4 and 7 to 9, which do not satisfy the constituent requirements of the polypropylene resin composition for injection molding of the present invention, any one of flexibility, impact resistance, light shielding property, whitening resistance, and moldability. Is not good. Further, Comparative Example 5 is not practical from the viewpoint of food hygiene because the extraction amount of n-hexane of polypropylene resin (X) is high, and Comparative Example 6 is color because the MFR of polypropylene resin (X) is low. There is unevenness.

The injection-molded product obtained by using the polypropylene-based resin composition for injection molding of the present invention has good flexibility, impact resistance, light-shielding property, whitening resistance, and moldability, and is characterized by polypropylene resin. Since it retains a certain lightweight feeling, it can be suitably used for applications such as food containers, beverage containers, caps (particularly hinge caps), and daily necessities, and has extremely high industrial utility.

Claims (4)

A propylene-ethylene copolymer (a) having an ethylene content of 0.1 to 3.0% by weight and a melt flow rate (MFR) of 10 to 150 g / 10 minutes according to JIS K7210 (230 ° C., 2.16 kg load). ) And the propylene-ethylene copolymer (b) having an ethylene content of 5 to 20% by weight and an MFR of 1 to 30 g / 10 minutes. The weight ratio of the −ethylene copolymer (a) to the propylene-ethylene copolymer (b) is 90: 10 to 60:40, and the polypropylene-ethylene resin composition (A) is 80 to 95% by weight, and the following. 5 to 20% by weight of the polypropylene resin (X) having the characteristics (i) to (v) (however, the total mixing ratio of the propylene-ethylene resin composition (A) and the polypropylene resin (X) is 100% by weight. A polypropylene-based resin composition for injection-molded hinge cap members.
Characteristic (i): MFR is 8 to 100 g / 10 minutes.
Characteristic (ii): The flexural modulus is 1100 to 1500 MPa.
Characteristic (iii): Charpy impact strength at 0 ° C. is 4.5 kJ / m ² or more.
Characteristic (iv): The amount of n-hexane extracted is 1.0 to 5.5 wt%.
Characteristic (v): HAZE by 1 mmt sheet is 90% or more. The polypropylene resin composition for an injection-molded hinge cap member according to claim 1, wherein the n-hexane extraction amount of the propylene-ethylene resin composition (A) is 1.0 to 5.5 wt%. The polypropylene resin composition for an injection-molded hinge cap member according to any one of claims 1 and 2, wherein the polypropylene-based resin composition for an injection-molded hinge cap member has the following characteristics (a) to (d).
Characteristics (a): Charpy impact strength at 0 ° C. is 3.5 kJ / m ² or more.
Characteristic (a): The flexural modulus is 1000 MPa or less.
Characteristics (c): HAZE from a 1 mmt sheet is 55 to 95%.
Characteristic (d): MFR is 10 to 100 g / 10 minutes. An injection-molded hinge cap member made of the polypropylene-based resin composition for the injection-molded hinge cap member according to any one of claims 1 to 3.