JPH09316251A - Polypropylene-based resin composition and its formed product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polypropylene-based resin composition having excellent balance between cold-impact strength and heat resistance, and its formed product. SOLUTION: This resin composition comprises (A) 25-60wt.% flexible propylene-α-olefin block copolymer composed of polypropylene block (1) and 20-70wt.% copolymer elastomer block (2) of propylene with a 2-12C α-olefin (except a 3Cα-olefin), existing in a state dispersed in polypropylene block (1) matrix phase, having <=1.0μm number-average particle diameter of dispersed particles and <=1.5μm area average particle diameter and (B) 75-40wt.% polypropylene-based resin having >=13g melt tension at 230 deg.C. The resin composition has the following physical properties. (a) Crystallization peak temperature measured by using a differential scanning calorimeter: 120 deg.C to 128 deg.C. (b) Crystallization energy: 60-75J/g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin composition having an excellent balance between cold impact strength and heat resistance, and a foamed molded product thereof.

[0002]

2. Description of the Related Art Foam molded articles of polypropylene resin are
It is used in various fields, taking advantage of its excellent heat resistance. For example, in the automobile field, it is used as a heat insulating material for ceiling materials, door linings, instrument panels and handle parts. Further, in the food packaging field, it is used as a foaming tray as a packaging material for frozen foods. In particular, recently, a method has been widely used in which these frozen foods are directly heated in a microwave oven and then eaten. Conventionally, a method of processing a polypropylene foamed sheet into a product such as a tray by secondary processing such as vacuum molding or compression molding is usually used for the foamed molded product of these polypropylene resins. Since vacuum molding and compression molding are generally performed at a high temperature of 120 to 200 ° C., heat resistance at the time of secondary processing is required, and foamed molded articles generally composed of a crosslinked polypropylene resin composition are well known. .

However, the foamed molded article made of the crosslinked polypropylene resin composition has drawbacks that it cannot be recycled and that it is inferior in cold impact strength during frozen storage in the frozen food field. As a method for solving this, for example, a foamable polyolefin resin composition obtained by adding a pyrolyzable foaming agent to a composition composed of polypropylene, linear polyethylene and a styrene-ethylene-propylene block copolymer (Japanese Patent Laid-Open No. 9324), a polypropylene-based foam sheet comprising a polypropylene-based block copolymer, an ethylene / α-olefin copolymer, and high-density polyethylene (JP-A-6-212007),
Polypropylene foam sheet composed of crystalline polypropylene and amorphous polypropylene or low density polyethylene (JP-A-49-18958), polypropylene foam sheet composed of specific n-heptane-soluble polypropylene and amorphous ethylene-propylene copolymer ( JP-A-5
0-44260), a polypropylene-based resin foam sheet made of a specific camel-type polypropylene and random or block polypropylene (JP-A-6-1924).
No. 60), a polypropylene resin foam sheet made of a specific camel-type polypropylene resin and atactic amorphous polypropylene (JP-A-6-279611), and the like have been proposed.

[0004]

However, in heating microwave oven foods, the surface temperature of the container is about 50 ° C., but the contents of the container reach 100 ° C. or more. However, none of the above methods has yielded a foamed sheet that satisfies the balance between cold impact strength required during frozen storage and heat resistance during foaming and heating in a microwave oven. That is, since the cold resistance and the heat resistance are contradictory to each other, there is a problem that one of these characteristics is inferior. An object of the present invention is to provide a polypropylene-based resin composition suitable for a foam molded article having an excellent balance between cold shock resistance and heat resistance, and a foam molded article thereof.

[0005]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention can achieve the above object with a composition comprising a specific soft propylene-α-olefin block copolymer and a polypropylene resin. Based on this finding, the present invention has been completed. That is, the present invention comprises (A) a polypropylene block (1) and a copolymer elastomer block (2) of propylene and an α-olefin having 2 to 12 carbon atoms (excluding 3), and the elastomer block (2) 2) is present in a state of being dispersed in the propylene block (1) matrix phase, and the number average particle diameter of dispersed particles is 1.0 μm or less. Yes,
25% by weight of a soft propylene-α-olefin block copolymer having an area average particle diameter of 1.5 and μm.
%, And (B) polypropylene resin having a melt tension of 13 g or more at a temperature of 230 ° C. of 75% by weight to
The present invention provides a polypropylene resin composition comprising 40% by weight and having the following physical properties, and a foam molded article using the resin composition. (A) Crystallization peak temperature (Tcp) measured using a differential scanning calorimeter (DSC): 120 ° C to 128 ° C (b) Crystallization energy (ΔHc): 60 to 75 J / g

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Soft propylene according to the present invention
The α-olefin block copolymer (hereinafter referred to as “BPP”) is a block copolymer composed of a polypropylene block and a copolymer elastomer block of propylene and an α-olefin having 2 to 12 carbon atoms (excluding 3). Is. Examples of the α-olefin include ethylene, 1-butene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4-dimethyl-1-pentene, vinylcyclopentane and vinylcyclohexane. Etc. These α-olefins may be used alone or in combination of two or more.

The BPP of the present invention has a structure in which a polypropylene block is a matrix phase and an elastomer block is dispersed in the matrix phase. The number average particle size (hereinafter referred to as “Dn”) of the dispersed elastomer particles is 1.0 μm or less, and the area average particle size (hereinafter referred to as “Ds”) is required to be 1.5 μm or less. . Dn is preferably 0.8 μm or less, and particularly preferably 0.5 μm or less. If Dn exceeds 1.0 μm, cold impact strength and heat resistance deteriorate, which is not preferable. Regarding the distribution of Dn, it is preferable that the maximum particle size is 0.6 μm or less and the standard deviation is 1.5 μm or less.
Further, Ds is preferably 1.0 μm or less, particularly 0.8 μm.
m or less is suitable. When Ds exceeds 1.5, cold impact strength and heat resistance deteriorate, which is not preferable.

Further, as the BPP excellent in the balance between impact strength and heat resistance, those having the following characteristics (a) and (b) are preferable. That is, (a) Temperature 25 ° C
In the range of 25 to 65% by weight of para-xylene insolubles in (b), and (b) the para-xylene solubles at a temperature of 25 ° C., (i) the average propylene content (FP) by the two-site model is 20 to 80 mole%, (ii) a propylene content in the copolymer produced in the active sites of polymerization preferentially propylene in two-site model _{(P H)} (P P)
There ratio 65 to 90 mol% and the (iii) P _H occupies the copolymer (P _f1) is from 0.60 to 0.90.

(A) Para-xylene insoluble matter means that BPP is dissolved in para-xylene at a temperature of 130 ° C. in an amount of about 1% by weight,
It is an insoluble component that precipitates when cooled to 25 ° C., and the BPP of the present invention is preferably 25 to 65% by weight, and particularly 30 to
60% by weight is preferred. Further, the (b) para-xylene soluble component is a component dissolved by the above-mentioned operation, and the properties obtained by the two-site model are preferably in the above range. Specifically, the component soluble in para-xylene at a temperature of 25 ° C. of BPP was added to a mixed solvent of 1,2,4-trichlorobenzene / deuterated benzene at a temperature of 120% so that the polymer concentration became 10% by weight. Dissolve by heating at ℃. This solution was put into a ¹⁰ mmφ glass sample tube, and ¹³ C-NM
R spectrum is measured.

Here, 2 of propylene-α-olefin
The site model will be described by taking a propylene-ethylene copolymer as an example. An example of a nuclear magnetic resonance ( ¹³ C-NMR) spectrum of isotope carbon of a propylene-ethylene copolymer is shown in FIG. In the spectrum, 10 peaks shown in (1) to (10) appear due to the difference in the chain distribution (arrangement of ethylene and propylene). The name of this chain is Carm
an.CJ, et al; Macromolecules, Vol.10, p536-544 (1977)
2 and the name is shown in FIG. Such a chain can be expressed as a reaction probability (P) assuming a reaction mechanism of copolymerization, and the relative intensity of each peak of (1) to (10) is P when the overall peak intensity is 1. Can be expressed as a stochastic equation by Bernoulli statistics. For example, in the case of Sαα in (1), if the propylene unit is p and the ethylene unit is the symbol e, the possible chains are [pppp], [pppe], [epp
e], and these are referred to as reaction probabilities (P), respectively.
Express and add. The remaining peaks of (2) to (10) can be obtained by formulating equations in the same manner and optimizing P so that the peak intensity actually measured is closest to these 10 equations. .

The two-site model is a model that assumes this reaction mechanism. HNCHENG; Jounal of Applied Polymer
Sience, Vol. 35, p. 1639-1650 (1988). That is, in a model in which propylene and ethylene are copolymerized using a catalyst, the propylene content (P _P ) of the copolymer (P _H ) generated at the active site where propylene is preferentially polymerized.
And the propylene content (P ' _P ) of the copolymer produced at the active site where ethylene is preferentially polymerized, and the ratio of P _H to the copolymer (P _f1 ) is used as a parameter. The probability equation shown in FIG. Therefore, in order to make the relative intensities of the ¹³ C-NMR spectrum described above and the stochastic equations shown in Table 1 coincide with each other, the three _values of P _P , P ′ _P and P _f1
It is obtained by optimizing the individual parameters.

[0012]

[Table 1]

The (i) average propylene content (FP) of the para-xylene-soluble matter in the BPP of the present invention is determined by the following equation using the above three parameters. _{FP = P P × P f1 +} P 'P copolymer × (1-P _f1) (mol%) FP obtained by the above formula is 20 to 80 mol%, more preferably from 30 to 70 mol%. Further, the (ii) P _P of the parameters is preferably 65 to 90 mol%, it is preferable especially 70 to 85 mol%. Further, (iii) P _f1 is preferably 0.40 to 0.90, and particularly preferably 0.48 to 0.82.

The method for producing BPP of the present invention includes a slurry method carried out in the presence of an inert hydrocarbon such as hexane, heptane, kerosene or a liquefied α-olefin solvent such as propylene, a gas phase polymerization method without a solvent, etc. The temperature condition is room temperature to 130 ° C., preferably 50 to 90.
It is carried out under conditions of a temperature of ² ° C. and a pressure of ^{2 to} 50 kg / cm ² . As the reactor in the polymerization step, those usually used in the technical field can be appropriately used, for example, a stirred tank type reactor, a fluidized bed type reactor, a circulation type reactor and the like, a continuous type, an anti-batch type,
Either batch method may be adopted. In particular,
It is obtained using a known multistage polymerization method. That is, it is a method of polymerizing propylene and / or a propylene-α-olefin copolymer in a first-stage reactor and then copolymerizing propylene and α-olefin in a second-stage reaction. JP-A-3-97747 and JP-A-3-205
No. 439, JP-A-4-153203, JP-A-5-93024, JP-A-4-261423 and the like. Alternatively, a method in which polypropylene and an α-olefin copolymer elastomer are mixed in an extruder or the like may be used, but it tends to be difficult to satisfy the conditions of the present invention.

On the other hand, the polypropylene resin (B) in the present invention is homopolypropylene, a random or block copolymer of propylene and an α-olefin having 2 to 12 carbon atoms (excluding 3), and is particularly limited. Although there is nothing to do, the melt tension at a temperature of 230 ° C is 13g.
It is necessary to be above. The melt tension represents the tension at the time of melting and is measured according to ASTM D1238. Specifically, using a melt tension tester type II manufactured by Toyo Seiki Seisaku-sho, Ltd., a temperature of 230 ° C., an extrusion rate of 10 mm / min, a die diameter of 2.095 mm, a die length of 8.03 mm and a take-up rate of 3 m / min. It is measured under the conditions. The melt tension is preferably 15 g or more, particularly preferably 17 g or more. When the melt tension is less than 13 g, foam moldability and heat resistance are poor. The upper limit is not particularly limited, but is usually 25 g or less. The composition ratio of the α-olefin as a copolymer component is generally at most 10% by weight, preferably 7% by weight or less, particularly preferably 5% by weight or less.

The polypropylene used in the present invention includes
The component (A) described in JP-A No. 7-109386 previously filed by the present applicant can be mentioned. Specific examples thereof include those obtained by irradiating polypropylene with ionizing radiation such as electron beams or gamma rays in a vacuum or an inert gas atmosphere, and polypropylene obtained by using porous δ-type titanium trichloride as a polymerization catalyst. Also,
JP-A-57-185304, JP-A-58-740
6, JP-A-59-172507, JP-B-6
Polypropylene obtained by introducing a high molecular weight component by the multistage polymerization method described in JP-A-4-5051, JP-A-3-4821, JP-A-4-98004, JP-B-6-99511 and the like, and Kai 57-1
85336, JP-A-57-187337,
An example is a polypropylene mixture obtained by mixing and kneading polypropylenes having different molecular weights as described in JP-A-58-7439. Of these, the melt tension is 1
It is preferable to use 3 g or more of polypropylene. The ratio of the α-olefin component in the random copolymer of propylene and α-olefin is preferably 10% by weight or less in consideration of heat resistance. It is preferably 7% by weight or less, particularly preferably 5% by weight or less.

Further, considering the foaming processability, impact resistance and heat resistance of the foamed molded product, the weight average molecular weight (Mw) measured by GPC (gel permeation chromatography) is 250,000 to 450,000. Is preferred, especially 30
It is preferably 10,000 to 400,000. The Z-average molecular weight is 100.
It is preferably from 10,000 to 1,300,000, particularly preferably from 1,100,000 to 1,250,000. Regarding the molecular weight distribution, Mw / Mn is 5 to 8
Is preferable, and 6 to 7 is particularly preferable. Mz / Mw is preferably 2.5 to 6.0, and particularly preferably 3.0 to 5.0.

The composition ratio of the component (A) in the resin composition of the present invention is 25 to 60% by weight, preferably 28 to 58% by weight, and particularly preferably 30 to 55% by weight.
When the composition ratio of the component (A) is less than 25% by weight, the cold impact resistance is poor, which is not preferable. On the other hand, if it exceeds 60 weight, the heat resistance is deteriorated, which is not preferable.

The resin composition of the present invention must further satisfy the following physical properties (a) and (b). (A) Crystallization peak temperature (Tcp) measured using a differential scanning calorimeter (DSC) is 120 to 128 ° C. (b) Crystallization energy (ΔHc) is 60 to 75 J / g Crystallization peak temperature (Tcp) ) Is preferably 121-12
6 ° C., particularly preferably 122 to 125 ° C.
When Tcp is less than 120 ° C, heat resistance is poor. On the other hand, 128
If the temperature exceeds ℃, cold impact strength and foam moldability are deteriorated, which is not preferable. The crystallization energy (ΔHc) is preferably 6
2 to 72 J / g, and particularly preferably 63 to 70 J / g.
g. When ΔHc is less than 60 J / g, heat resistance and foam moldability are poor. On the other hand, if it exceeds 75 J / g, the cold impact strength becomes poor, which is not preferable.

The polypropylene resin composition of the present invention is
A foam molded article can be obtained by a known foam molding method commonly used in the resin field. As the foam molding method, there are a method of foaming with a pyrolysis gas using a pyrolytic chemical foaming agent and a gas foaming method of injecting the foaming agent from the middle of a cylinder of an extruder. In the method using a thermal decomposition type chemical foaming agent, a thermal decomposition type chemical foaming agent is mixed with a resin composition, and foam molding is performed by extrusion foaming, injection foaming or the like.

The thermal decomposition type chemical foaming agent may be either an inorganic compound or an organic compound. Examples of the inorganic compound include sodium bicarbonate, ammonium carbonate, ammonium nitrite, sodium borohydride and the like. On the other hand, as the organic compound, azido compounds such as azodicarbonamide, azobisformamide, isobutyronitrile and diazoaminobenzene, nitroso such as N, N′-dinitrosopentatetramine and N, N′-dimethyl-dinitroterephthalamide. Compounds. The amount of the thermal decomposition type chemical foaming agent used is 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the polypropylene resin composition. The thermal decomposition type chemical foaming agent may be used alone or in combination of two or more kinds.

As the foaming agent in the gas foaming method, butane,
Examples thereof include aliphatic hydrocarbons such as pentane, hexane, butadiene, methylene dioxide, dichloroethane, trichloromonofluoromethane, dichlorotetrafluoroethane, chlorinated aliphatic hydrocarbons and fluorinated aliphatic hydrocarbons. An appropriate insertion pressure for these is usually about 100 Kg / cm ² . When these methods are used, in-mold foaming methods other than foam molding using the above extruder may be used.

The apparent specific gravity of the foamed molded product thus obtained is preferably 0.02 to 0.90 g / cm ³ . The expansion ratio is 30 to 1.2 times. The foamed molded article of the present invention can be molded into any shape such as a sheet shape and a block shape, and is appropriately selected depending on the application.

For the polypropylene resin composition of the present invention, other additives commonly used in thermoplastic resins (eg, antioxidants, weather resistance stabilizers, antistatic agents, lubricants, anti-blocking agents) are also included. , Antifogging agents, dyes, pigments, oils, waxes, etc.) can be added in appropriate amounts within the range not impairing the object of the present invention. For example, examples of such additives include 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4, and 4 as antioxidants.
4'-thiobis- (6-t-butylphenol), 2,
2-methylene-bis (4-methyl-6-t-butylphenol), octadecyl 3- (3 ', 5'-di-t-butyl-1'-hydroxyphenyl) propinate, 4,
4'-thiobis- (6-butylphenol), as an ultraviolet absorber ethyl-2-cyano-3,3-diphenyl acrylate, 2- (2'-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxy-4 Octoxybenzophenone, dimethyl phthalate as plasticizer, diethyl phthalate, wax, liquid paraffin, phosphoric acid ester, tomonostearate, sorbitan monopalmitate, sulfated oleic acid as antistatic agent,
Polyethylene oxide, carbon wax, ethylene bis stearamide as a lubricant, butyl stearate, etc.,
Carbon black, phthalocyanine, quinacridone, indoline, azo pigments, titanium oxide, red iron oxide, etc. as colorants, glass fiber, asbestos as fillers,
Mica, ballastonite, calcium silicate, aluminum silicate, calcium carbonate, and many other polymer compounds can also be blended to the extent that the effects of the present invention are not impaired.

The polypropylene resin composition of the present invention comprises:
It can be obtained by blending the components (A) and (B) with other additives and melt-kneading. Specifically, conventionally known mixing methods, for example, each component is mixed using a ribbon blender, a Henschel mixer, a tumbler,
Further, it may be melt-mixed using a kneader, a mixing roll, a Banbury mixer, an extruder or the like. The melt-kneading temperature is usually 160 to 300 ° C. As another method, each component may be directly supplied to a molding machine and molded.

Melt flow rate of the polypropylene resin composition of the present invention (measured in accordance with JIS K7210 at a temperature of 230 ° C. and a load of 2.16 Kg.
It is generally preferable to use "R") in the range of 0.5 to 10 g / 10 minutes. MFR is preferably 0.8-8
g / 10 minutes, particularly preferably 1.0 to 5 g / 10
Minutes.

[0027]

The present invention will be described in more detail with reference to the following examples. I. Evaluation of unfoamed molded product [Type of component (A) resin] BP having physical properties shown in Table 2
P was used. The following mixture was used for Comparative Example 7. [PP / EPR] MA810 manufactured by Showa Denko KK, which is a commercially available homopolypropylene, and has an ethylene content of 70% by weight.
The ethylene-propylene rubber in Example 2 was pelletized at a ratio of 70/30 using a twin-screw extruder. The obtained pellets are
The weight average particle diameter of the dispersed ethylene-propylene rubber particles by image analysis was 2.93 μm, and the number average particle diameter was 0.93 μm.

[Type of component (B) resin] (PP1 to PP3) Homopolypropylene powder having an MFR of 0.5 g / 10 min was placed in a glass container purged with nitrogen gas, and an electron beam irradiation device (Nisshin High Voltage) was used. (Manufactured by K.K.) is used, and the irradiation dose is 3 Mrad.
It heat-processed at 60 degreeC for 60 minutes. The obtained treated product (hereinafter referred to as "PP
1 ”) has a melt tension of 16.4 g, and GPC has an Mw of 32.6 × 10 ⁴ and an Mz of 112.3 × 10.
⁴ , Mw / Mn = 6.4, and Mz / Mw = 3.1. A treated product (hereinafter referred to as "PP2") was obtained in the same manner as PP1 except that the irradiation dose was changed to 5 Mrad. PP2
Has a melt tension of 18.6 g and has a Mw of 3 by GPC.
5.1 × 10 ⁴ , Mz is 117.7 × 10 ⁴ , Mw / M
n = 6.9 and Mz / Mw = 3.4. MFR is 1
A treated product was treated in the same manner as PP2 except that a homopolypropylene powder of 5 g / 10 min was used (hereinafter, referred to as “PP”).
3 ”). The melt tension of PP3 is 5.2 g, the Mw by GPC is 17.2 × 10 ⁴ , and the Mz is 6.
5.5 × 10 ⁴ , Mw / Mn = 30.9, Mz / Mw =
3.8.

(PP4 to PP5) β-type titanium trichloride obtained by reducing titanium tetrachloride with diethylaluminum chloride is treated with isoamyl ether to extract aluminum trichloride contained as a eutectic, and then with titanium tetrachloride. Using a δ-type titanium trichloride catalyst obtained by the treatment, a 5-liter stainless steel autoclave was used, and the temperature was 80
Propylene gas was injected under pressure at 0 ° C. to obtain PP4 and PP5.
The melt tension of PP4 is 16.8 g, and M by GPC
w is 29.2 × 10 ⁴ , Mz is 108.4 × 10 ⁴ , M
w / Mn = 7.2 and Mz / Mw = 3.8. On the other hand, PP5 has a melt tension of 10.5 g, Mw by GPC of 23.9 × 10 ⁴ , Mz of 97.6 × 10 ⁴ ,
It was Mw / Mn = 7.2 and Mz / Mw = 4.2.

(PP6) PP6 was obtained according to the example described in JP-B-3-48214. That is, a solid titanium trichloride catalyst is used as a polymerization catalyst,
After prepolymerization, homopolypropylene was obtained by a multistage polymerization method. The melt tension of PP6 is 17.6 g, Mw by GPC is 29.6 × 10 ⁴ , and Mz is 10
5.1 × 10 ⁴ , Mw / Mn = 6.8, Mz / Mw =
It was 3.9.

(PP7) J-Allomer MA210 manufactured by Nippon Polyolefin Co., Ltd., which is a commercially available homopolypropylene
Was used. The melt tension of PP7 was 0.6 g.

[0032]

[Table 2]

Examples 1 to 7, Comparative Examples 1 to 7 Types and blending amounts shown in Table 3, 0.05 parts by weight of di-t-butyl-p-cresol as a stabilizer, pentaerythrityl-tetrakis [3-] (3,5-Di-t-butyl-4-hydroxyphenyl)] propionate 0.
10 parts by weight and 0.10 parts by weight of calcium stearate are mixed to prepare a super mixer (SMV2 manufactured by Kawata Manufacturing Co., Ltd.
0 type) and mixed, Kobe Steel's twin-screw extruder (KT
X-37 type) was used to form a pellet. Each of the obtained pellets was injected into an injection molding machine (IS170II-5 manufactured by Toshiba Machine Co., Ltd.).
A type), Izod impact test at a temperature of 230 ℃,
Create test pieces for measuring heat deformation temperature and falling weight impact strength,
The sample was left in a thermostatic chamber at a temperature of 23 ° C. and a humidity of 50% for 2 days and nights, and the following measurements were carried out.

The measuring method and apparatus for each physical property in the present invention are shown below. Observation of TEM: Thickness of 3 under the conditions of temperature of 230 ° C and pressure of 80 kg / cm ^2.
After making a test piece of mm, it is cut out into a block shape of 1 cm in length × 5 mm in width × 3 mm in height, and surface-cut with an ultramicrotome (ULTRACUT UN, diamond knife manufactured by Reichert), and then 0.5% of commercially available
Immersion dyeing was performed using a RuO ₄ aqueous solution under the conditions of a temperature of 80 ° C. and a time of 3 hours. Next, a 100 nm-thick ultrathin section was cut from the block stained with an ultramicrotome and collected on a copper mesh. The TEM observation was performed using the following device. Device: H-800 transmission electron microscope manufactured by Hitachi, Ltd. Accelerating voltage: 100 kV Resolution: 2.04 angstrom (lattice image) Magnification: 10,000 times

Image Analysis Based on the photographs obtained by the above TEM observation, the number average particle size and area average particle size were determined by image analysis processing using the following apparatus. Equipment: Toshiba image processing equipment TOSPIX
-U2 Screen size: Vertical 1024 x Horizontal 1024 x Depth 8 (pixels / sheet) Gradation gradation: 256 gradations

Measurement of Para-Xylene Insoluble Content and Soluble Content The polymer was once dissolved in para-xylene at a temperature of 130 ° C. to a concentration of about 1% by weight, then cooled to a temperature of 25 ° C., and the precipitate was insoluble in para-xylene. The content that did not precipitate was defined as the para-xylene-soluble content, and the weight ratio was determined. The para-xylene solubles were used for the next measurement of the ¹³ C-NMR spectrum.

Measurement of ¹³ C-NMR spectrum Measuring instrument: JNM-GSX4 manufactured by JEOL Ltd.
00 Measurement mode: Proton decoupling method Pulse width: 8.0 μs Pulse repetition time: 5.0 μs Number of integrations: 20000 Solvents: 1,2,4-trichlorobenzene / deuterated benzene mixed solvent (75/25 volumes %) Internal standard: Hexamethyldisiloxane Sample concentration: 300 mg / 3.0 ml Solvent measurement temperature: 120 ° C

Measurement of GPC (Gel Permeation Quattography) Measuring instrument: GPC1 manufactured by Waters
50C type column: KF-80M 2 bottles (SHODEX manufactured by Showa Denko KK) Column temperature: 145 ° C Injection temperature: 145 ° C Pump temperature: 60 ° C Solvent: O-dichlorobenzene

Differential Scanning Calorimeter (DSC) Measuring Device: PERKIN-ELMER DSC7 Model Weight: Approximately 3 to 5 mg Measuring Method: The sample was heated to 230 ° C. and held for 5 minutes, then 20 ° C. / The temperature is lowered to 0 ° C. at a rate of minutes to obtain a crystallization temperature curve. The main crystallization peak temperature Tcp and the crystallization energy ΔHc are determined from the obtained crystallization temperature curve.

Low temperature Izod impact strength (with notch) Measured in accordance with ASTM D790 at a temperature of -40 ° C.

Drop Weight Impact Test According to ASTM D3029-78, while dropping the weight from a height of 1 m and changing the load of the weight every 50 g,
The energy (Kg-cm) at which 50% of 30 test pieces was broken was determined. The measurement temperature was −40 ° C.

Heat distortion temperature: Measured under a load of 4.6 Kg according to JIS K7207B method. The above results are shown in Table 3.

[0043]

[Table 3]

II. Evaluation of foamed molded article Example 8 Using the resin composition of Example 2, 100 parts by weight of this resin composition was used as a foaming agent and azodicarbonamide 1.2.
65 parts by weight and 0.6 parts by weight of basic zinc carbonate as a foaming aid, and a T-die with a width of 1000 mm
It was extruded by an extruder to obtain a uniform and beautiful foam sheet having a density of 0.3 g / cm ^{3 and} a smooth surface. Next, using 20 of the foamed sheets, a falling weight impact test was performed at -40 ° C. to obtain a breakage rate, but no breakage was observed at all. Next, this foamed sheet was put into a microwave oven for 10 minutes for treatment, but no deformation or twisting of the sheet or collapse of bubbles was observed.

Example 9 Using the resin composition of Example 3, the same procedure as in Example 8 was carried out. As a result, a beautiful and uniform foam having a smooth surface was obtained. Moreover, no damage was observed in the falling weight impact test. On the other hand, no change due to microwave oven treatment was observed.

Comparative Example 8 Using the resin composition of Comparative Example 1, the same procedure as in Example 8 was performed. In the drop weight impact test, the failure rate was that all of 20 sheets were damaged. Twisting was observed in the microwave oven treatment.

Comparative Example 9 Using the resin composition of Comparative Example 7, the same procedure as in Example 8 was carried out, but a uniform foam was not obtained.

[0048]

EFFECT OF THE INVENTION The polypropylene resin composition of the present invention and the foam thereof have a better balance between cold impact strength and heat resistance than conventional ones, and a beautiful foam can be obtained.
In particular, it is useful as food packaging, automobile fields, home appliances fields, industrial material fields, and various product members.

[Brief description of drawings]

FIG. 1 is an example of a nuclear magnetic resonance spectrum of isotope carbon of an ethylene-propylene copolymer.

FIG. 2 is a view showing names of carbons derived from a chain distribution in a polyolefin.

FIG. 3 is a DSC of the polypropylene resin composition of the present invention.
It is an example of a crystallization curve.

Claims (3)

[Claims] 1. A polypropylene block (A) (A)
And propylene and 2 to 12 carbon atoms (excluding 3)
The copolymer block with the α-olefin of (2) is contained in the polypropylene block (1) matrix phase, and the elastomer block (2) accounts for 20 to 70% by weight of the total copolymer. Exist in a state and the number average particle size of dispersed particles is 1.0 μm.
m or less and the area average particle diameter is 1.5 μm or less, the soft propylene-α-olefin block copolymer 2
A polypropylene resin composition having the following physical properties, which comprises 5 to 60 wt% and (B) 75 to 40 wt% of a polypropylene resin having a melt tension of 13 g or more at a temperature of 230 ° C. (A) Crystallization peak temperature (Tcp) measured using a differential scanning calorimeter (DSC): 120 ° C to 128 ° C (b) Crystallization energy (ΔHc): 60 to 75 J /
g 2. The polypropylene resin composition according to claim 1, wherein the propylene-α-olefin block copolymer has the following physical properties (a) and (b). (B) Proportion of para-xylene insoluble matter at a temperature of 25 ° C
25-65% by weight (b) Properties of para-xylene solubles at a temperature of 25 ° C
(I) Average propylene content (F
P) 20 to 80 mol%, (ii) propylene content (P _P ) of the copolymer (P _H ) formed at active sites for preferentially polymerizing propylene in the two-site model, 65 to 90 mol%, and (iii) Ratio of P _H to the copolymer (P _f1 )
0.60 to 0.90 3. A foamed molded article obtained by heat foaming the polypropylene resin composition according to claim 1 or 2.