JP2013209552A - Polypropylene resin composition and foam/blow molded article thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene resin composition having excellent surface appearance and good foam/blow moldability, allowing significant reduction in weight, and exhibiting excellent heat stability.SOLUTION: A polypropylene resin composition includes: 15-88 wt% of a specific crystalline polypropylene (A); 10-60 wt% of a linear propylene-ethylene block copolymer (B); and 2-25 wt% of a polypropylene polymer (C). In the polypropylene resin composition, a melt flow rate (at 230°C under a load of 2.16 kg) is 1-5 g/10min.

Description

  The present invention relates to a polypropylene resin composition and a foamed blow molded article thereof. More specifically, the present invention has excellent surface appearance, good melt processing characteristics such as draw-down resistance, improved thermal stability and recyclability. The present invention relates to a polypropylene resin composition excellent in foamability and capable of drastically reducing weight, and a foamed blow molded article thereof.

Polypropylene resins have good physical properties and moldability, and the range of use is rapidly expanding as an environmentally friendly material. In particular, so-called foam blow molding in which foaming is performed in blow molding for the purpose of weight reduction, cost reduction, heat insulation, and sound absorption of products such as automobile parts has attracted attention (see, for example, Patent Document 1).
In conventional polypropylene, when the foamed parison is blown with pressurized air in the mold, the melt tension is small, so the foamed bubbles are crushed and it is difficult to obtain a sufficiently foamed hollow molded product. there were.

Therefore, as a method for increasing the melt tension of polypropylene, a method in which an organic peroxide and a crosslinking aid are reacted with crystalline polypropylene under a molten state (for example, see Patent Documents 2 and 3), A method of producing a polypropylene having free end long chain branching and containing no gel by reacting a low decomposition temperature peroxide in the absence of oxygen is disclosed (see Patent Document 4).
In addition, a polypropylene resin is commercially available as HMS-PP (High Melt Strength Polypropylene) from Sun Allomer Co., which has a higher melt tension than ordinary linear polypropylene resins into which long-chain branches have been introduced by irradiation. Yes.

  The various polypropylenes proposed above have some improvement in melt tension. Polypropylene resin containing long-chain branched polypropylene (see Patent Document 5) has improved foam blow moldability, but has a problem in residual odor due to a crosslinking aid that is considered to be caused by the production method. . Furthermore, there are problems such as lack of recycling usability to solve problems such as environmental problems.

In order to solve such a problem, the present applicant has previously described a linear propylene / ethylene block having 20 to 80% by weight of crystalline polypropylene (A) and specific requirements (i) to (vi). It consists of 10 to 65% by weight of copolymer (B), 10 to 65% by weight of polypropylene polymer (C), and 0 to 20% by weight of an optional thermoplastic resin (D). Proposal of a polypropylene-based resin composition having a MFR of 1 to 15 g / 10 min and a foamed blow molded article thereof (see Patent Document 6). This is a polypropylene resin composition having excellent surface appearance, good foam blow moldability, significant weight reduction, excellent thermal stability, and excellent recyclability.
However, the foamed blow molded product is required to have further excellent product thickness (surface irregularity) control and surface smoothness. For example, as can be seen in ducts and the like used for air conditioning in automobiles, there is a demand for performance that satisfies further excellent moldability, heat insulation, strength, surface appearance and weight reduction.

Under these circumstances, the problems in the prior art are solved, the melt processing characteristics (formability) such as rigidity, heat insulation, and drawdown resistance are good, the surface appearance is improved, and the thermal stability (returnability) In addition, an excellent propylene resin composition is required.
JP 2004-116956 A JP 59-93711 A JP 61-152754 A JP-A-2-298536 JP 2006-181957 A JP 2010-121054 A

In view of the above-mentioned problems of the prior art, the object of the present invention is particularly excellent in surface appearance when used in a foam blow molded article, good foam blow moldability, can be significantly reduced in weight, and has a thermal stability. An object of the present invention is to provide a polypropylene resin composition excellent in (returnability) and a foamed blow molded article thereof.
Incidentally, in this specification, excellent surface appearance means that the surface has a smooth appearance, and good foam blow moldability means good resistance to drawdown and return, It means that foaming is performed according to the set expansion ratio and the cell diameter is uniform as a cell form.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a resin composition in which a specific linear propylene / ethylene block copolymer and a polypropylene polymer are blended with a general polypropylene resin, We have found that the surface appearance is excellent, the foam blow moldability is good, the weight can be significantly reduced, the recyclability is excellent, and the physical properties such as rigidity are improved, and the present invention is completed based on these findings. It came to.

That is, according to the first invention of the present invention, it contains the following (A) to (C), and has a melt flow rate (230 ° C., 2.16 kg load) of 1 to 15 g / 10 min. A polypropylene resin composition is provided.
(A): crystalline polypropylene having a melt flow rate (230 ° C., 2.16 kg load) of 0.05 to 2 g / 10 min; 15 to 88% by weight
(B): a linear propylene polymer comprising the linear propylene polymer component (b1) and the linear ethylene / propylene random copolymer component (b2) and having the following characteristics (i) to (vi): Ethylene block copolymer; 10-60% by weight
(C): Polypropylene polymer (C): Propylene / ethylene block copolymer having the requirements defined in the following (C-a) to (C-e).
(C-A): 30 to 95% by weight of propylene homopolymer or propylene / ethylene random copolymer component (c1) having an ethylene content of 7% by weight or less in the first step using a metallocene catalyst, the second step The propylene / ethylene random copolymer component (c2) containing 3 to 20 wt% more ethylene than the component (c1) is obtained by sequential polymerization of 5 to 70 wt%.
(C-A): Melting peak temperature (Tm) measured by DSC method is 110 to 150 ° C.
(C-C): In the temperature-loss tangent curve obtained by solid viscoelasticity measurement, the tan δ curve has a single peak at 0 ° C. or lower.
(C-D): Melt flow rate (MFR: 230 ° C., 2.16 kg load) is 3 to 40 g / 10 min. 2-25% by weight
Characteristic (i): Melt flow rate (230 ° C., 2.16 kg load) of the linear propylene polymer component (b1) is 120 g / 10 min or more.
Characteristic (ii): The ratio of the linear ethylene / propylene random copolymer component (b2) to the entire linear propylene / ethylene block copolymer (B) is 2 to 50% by weight.
Characteristics (iii): The intrinsic viscosity _{[eta] copoly} of linear ethylene-propylene random copolymer component (b2) is 5.3~10.0dl / g.
Characteristic (iv): Melt flow rate (230 ° C., 2.16 kg load) is 45 g / 10 min or more.
Characteristic (v): The die swell ratio is 1.2 to 2.5.
Characteristic (vi): Shows strain hardening in 180 ° C. extensional viscosity measurement.

  According to the second invention of the present invention, in the first invention, the linear propylene / ethylene block copolymer (B) is a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn). (Q value: Mw / Mn) is 7 to 13, and a polypropylene resin composition is provided.

  Further, according to the third invention of the present invention, in the first or second invention, the linear ethylene / propylene random copolymer component (b2) has an ethylene content of linear ethylene / propylene random copolymer. A polypropylene resin composition is provided that is 15 to 80% by weight based on the total amount of the combined component (b2).

Furthermore, according to the fourth aspect of the present invention, in any one of the first to third aspects, the hydrogenated product (d1) of the styrene / conjugated diene block copolymer, Mooney viscosity [ML1 + 4 (121 ° C.) ] Is 5 or more ethylene / α-olefin copolymer rubber (d2) and melt flow rate (230 ° C., 2.16 kg load) is 0.3 to 2 g / 10 min, and density is 0.920 g / cm ³ or more. And containing at least one thermoplastic resin (D) selected from the group consisting of ethylene polymer resin (d3) of 20% by weight or less, with the total amount of (A) to (D) being 100% by weight. A polypropylene resin composition is provided.

  According to a fifth aspect of the present invention, there is provided a foamed blow molded article comprising the polypropylene resin composition according to any one of the first to fourth aspects and a foaming agent (E). .

  The polypropylene resin composition and foamed blow molded article of the present invention have excellent surface appearance, good foamed blow moldability, can be significantly reduced in weight, and are excellent in recyclability without undergoing cross-linking modification. In addition, a significant effect of improving physical properties such as rigidity and heat insulation is exhibited. In addition, since cross-linking modification is not performed, recyclability is excellent and environmental adaptability is also good. Therefore, it is suitable for blow molding parts for automobiles such as ducts, protective coating materials for pipes, resonators, deck boards, and for heat insulation panels, household goods, tanks, etc. be able to.

It is a figure which shows the elution amount and elution amount integration by temperature rising elution fractionation (TREF).

In the present invention, the specific crystalline polypropylene (A) is 15 to 88% by weight, the linear propylene / ethylene block copolymer (B) is 10 to 60% by weight, and the polypropylene polymer (C) is 2 to 2%. The present invention relates to a polypropylene resin composition containing 25% by weight and having a melt flow rate (230 ° C., 2.16 kg load) of 1 to 15 g / 10 min. In addition, a mixture ratio is a value when the total amount of (A)-(C) and (D) mix | blended arbitrarily is 100 weight%.
Hereinafter, each component of the polypropylene resin composition, the production of the polypropylene resin composition, the production of the foamed blow molded article, and the like will be described in detail.

1. Crystalline polypropylene (A)
The crystalline polypropylene (A) used in the present invention (hereinafter also simply referred to as “(A)”) is not particularly limited, and examples thereof include other propylene homopolymers, propylene and ethylene, butene-1, and the like. A random copolymer or block copolymer with an α-olefin may be mentioned, and these may be used in combination.
The crystalline polypropylene used in the present invention has an MFR (measured at JIS K7210, 230 ° C., 2.16 kg load) of 0.05 to 2 g / 10 minutes, preferably 0.1 to 1.5 g / 10 minutes, more preferably Is 0.2 to 1.2 g / 10 min. If it is less than the lower limit, the melt ductility may be lowered, and if it exceeds the upper limit, the drawdown resistance may be lowered.

The crystalline polypropylene according to the present invention is a polypropylene having crystallinity, but the presence or absence of crystallinity can be determined by the presence or absence of a melting point. That is, the crystalline polypropylene according to the present invention has a melting point.
The melting point can be measured as an endothermic peak based on melting of the crystal by DSC measurement. The crystalline polypropylene according to the present invention preferably has a melting point of 110 to 175 ° C, more preferably 150 to 170 ° C (A).
The melting point was determined by using a differential scanning calorimeter (DSC6200 manufactured by Seiko Instruments Inc.), filling the sheet-like sample piece into a 5 mg aluminum pan, and increasing the temperature from 50 ° C. to 200 ° C. at a rate of temperature increase of 100 ° C./min. Then, after holding for 5 minutes, the temperature is lowered to 40 ° C. at 10 ° C./min for crystallization, held for 1 minute, and then obtained as the maximum melting peak temperature when the temperature is raised to 200 ° C. at 10 ° C./min.
The crystalline polypropylene according to the present invention can be produced by a production method similar to the production method described in the linear propylene / ethylene block copolymer (B) described later. In particular, it is important to control the hydrogen / propylene ratio in the polymerization process in order to bring the MFR within the specified range in the crystalline polypropylene (A).
In addition, various products of these crystalline polypropylenes are sold by many companies, and those having desired physical properties may be purchased from these commercially available products.

2. Linear propylene / ethylene block copolymer (B)
The linear propylene / ethylene block copolymer (B) used in the present invention (hereinafter also referred to simply as “(B)”) is a linear propylene polymer component (b1) (hereinafter simply referred to as “component ( b1) ”) and a linear ethylene / propylene random copolymer component (b2) (hereinafter also simply referred to as“ component (b2) ”). is there.
The linear propylene / ethylene block copolymer (B) has the following characteristics (i) to (vi), and in the polypropylene resin composition of the present invention, it has an excellent surface appearance and high foam blow moldability. (Foaming ratio, foaming state), and has a feature that contributes to the appearance of the surface appearance.
Characteristic (i): MFR (230 ° C., 2.16 kg load) of the linear propylene polymer component (b1) is 120 g / 10 minutes or more.
Characteristic (ii): The ratio of the linear ethylene / propylene random copolymer component (b2) to the entire linear propylene / ethylene block copolymer (B) is 2 to 50% by weight.
Characteristics (iii): The intrinsic viscosity _{[eta] copoly} of linear ethylene-propylene random copolymer component (b2) is 5.3~10.0dl / g.
Characteristic (iv): MFR (230 ° C., 2.16 kg load) is 45 g / 10 min or more.
Characteristic (v): The die swell ratio is 1.2 to 2.5.
Characteristic (vi): Shows strain hardening in 180 ° C. extensional viscosity measurement.

Here, “linear” in the linear propylene polymer component (b1), the linear ethylene / propylene random copolymer component (b2) and the linear propylene / ethylene block copolymer (B) This means that the number of branched structures other than the methyl branched structure is extremely small, and preferably does not exist. This is a structure often found in ordinary polypropylene resins.
For example, it can be confirmed by ¹³ C-NMR analysis that no peak is observed at 31.5 to 31.7 ppm based on branched carbon (see Macromol. Chem. Phys. 2003, Vol. 204, page 1738).

  Although the linear propylene / ethylene block copolymer (B) has a linear structure as described above, it exhibits strain hardening. Strain hardenability is usually said to be caused by molecular entanglement. In order to develop strain hardenability, for example, the molecular weight of the linear propylene polymer component (b1) and the linear ethylene / propylene random Examples of the method include increasing the difference in molecular weight of the copolymer component (b2) and increasing the compatibility between the component (b1) and the component (b2).

The linear propylene / ethylene block copolymer (B) not only satisfies these requirements, but also includes the linear ethylene / propylene random copolymer component (b2) in the linear propylene polymer component (b1). The dispersion structure is peculiar, that is, in the case of a general propylene / ethylene block copolymer (in this case, when subjected to shearing, the ethylene / propylene random copolymer portion is rejected at the interface of the propylene polymer portion). Unlike the agglomerated and dispersed individually), a state similar to a network (that is, the component (b2) soaks into the component (b1) in a network) is exhibited. It is considered to show strain hardening.
Further, it is considered that the compatibility between the component (b1) and the component (b2) is further enhanced by exhibiting a state approximate to a kind of network.

  In the polypropylene resin composition and foam blow molded article of the present invention, the effect of exhibiting strain hardening is likely to be beautiful surface smoothness due to bubble breakage at the die opening portion during foam blow molding, In addition, it is easy to obtain a foamed blow molded article having uniform fine bubbles at a high magnification.

(1) Production The production method of the linear propylene / ethylene block copolymer (B) used in the polypropylene resin composition of the present invention is characterized by the obtained linear propylene / ethylene block copolymer (B). As long as it has (i) to (vi), it is not particularly limited, and can be appropriately selected from known polymerization methods and polymerization conditions. Examples thereof include the following methods.
As the propylene polymerization catalyst, a highly stereoregular catalyst is usually used. For example, a catalyst comprising a combination of a titanium trichloride composition obtained by reducing titanium tetrachloride with an organoaluminum compound and further treating with various electron donors and electron acceptors, an organoaluminum compound and an aromatic carboxylic acid ester ( (See JP-A 56-1000080, JP-A 56-120712, and JP-A 58-104907.), And support in which magnesium tetrachloride is contacted with titanium tetrachloride and various electron donors. And the like (see JP-A-57-63310, JP-A-63-43915, and JP-A-63-83116).

  Examples of organoaluminum compounds used as promoters include trialkylaluminums such as trimethylaluminum, triethylaluminum, and triisobutylaluminum, alkylaluminum halides such as diethylaluminum chloride and diisobutylaluminum chloride, and alkyls such as diethylaluminum hydride. Examples thereof include alkylaluminum alkoxides such as aluminum hydride and diethylaluminum ethoxide, alumoxanes such as methylalumoxane and tetrabutylalumoxane, and complex organoaluminum compounds such as dibutyl methylboronate and lithium aluminum tetraethyl. It is also possible to use a mixture of two or more of these.

  In addition, various polymerization additives for the purpose of improving stereoregularity, controlling particle properties, controlling soluble components, controlling molecular weight distribution, and the like can be used for the above-described catalyst. For example, organic silicon compounds such as diphenyldimethoxysilane and tert-butylmethyldimethoxysilane, esters such as ethyl acetate, butyl benzoate, methyl p-toluate, and dibutylphthalate, ketones such as acetone and methyl isobutyl ketone, diethyl ether And electron donating compounds such as ethers such as benzoic acid and propionic acid, and alcohols such as ethanol and butanol.

  As a polymerization form, a production process such as a gas phase polymerization method, a liquid phase bulk polymerization method, or a slurry polymerization method is applied to polymerize propylene, followed by random polymerization of propylene and ethylene. In order to obtain a propylene / ethylene block copolymer having the above-described melting characteristics (MFR), it is preferable to perform multistage polymerization by a slurry method or a gas phase fluidized bed method.

The polymerization of the linear propylene polymer component (b1) may be one-stage polymerization of propylene or multi-stage polymerization, but it is more preferable to obtain by the multi-stage polymerization in order to exhibit the above-mentioned characteristics. .
Examples of the multistage polymerization method of the linear propylene polymer component (b1) include a two-stage polymerization method by the following step (1) and step (2).
Step (1): Propylene is polymerized in the presence of hydrogen as a molecular weight regulator. This is to suppress the formation of a polymer having a too high molecular weight. Hydrogen is added so that the MFR of the linear propylene polymer component (b1) is 120 g / 10 min or more. The hydrogen concentration is usually selected from the range of 0.1 to 40 mol% with respect to the total monomer amount. The polymerization temperature is usually selected from the range of 40 to 90 ° C., and the pressure is selected from the range of 2 × 10 ^{5 to} 35 × 10 ⁵ Pa. The amount of the polymer obtained in this step (1) is usually adjusted to be 80 to 99% by weight of the total polymerization amount. Since the linear propylene polymer component of the present invention is characterized in that the linear propylene polymer component (b1) has a high MFR, the hydrogen of the chain transfer agent is relatively high depending on the type of catalyst. It is necessary to adjust and control the concentration. Specifically, the hydrogen / propylene ratio is 0.04 to 0.2.
In addition, the linear propylene polymer component of the present invention is characterized in that the intrinsic viscosity [η] of the linear ethylene / propylene random copolymer component (b2) is high. However, it is necessary to control [η] by adjusting the hydrogen of the chain transfer agent to the lowest possible concentration. Specifically, the hydrogen / (propylene + ethylene) ratio is 10 ⁻⁵ to 10 ⁻⁴ . Further, in order to maintain the ethylene content in the ethylene / propylene random copolymer portion (rubber component) within a specific range, the ethylene concentration relative to the latter propylene concentration is adjusted.

Step (2): Compared with the linear propylene polymer component (b1) produced in the step (1), in order to polymerize a high-molecular-weight propylene polymer, a hydrogen atmosphere of a concentration as low as possible or substantially hydrogen It is preferred to polymerize in the absence. The polymerization is subsequently carried out in the presence of the propylene polymer produced in step (1) and a catalyst. The polymerization temperature is usually selected from the range of 40 to 90 ° C. and the pressure of 2 × 10 ^{5 to} 35 × 10 ⁵ Pa. The amount of the polymer obtained in this step (2) is usually adjusted by the following method so as to be 1 to 20% by weight of the total polymerization amount. Any combination of the steps (1) and (2) may be adopted as long as the overall physical property value of the resulting (B) can be adjusted to the above-described range.
It is desirable to add alcohols such as ethanol during or before the reaction of the linear ethylene / propylene random copolymer component (b2). The linear propylene polymer component of the present invention has a large MFR difference (viscosity difference) between the linear propylene polymer component (b1) and the linear ethylene / propylene random copolymer component (b2). Therefore, a gel that is poorly dispersed in the ethylene / propylene random copolymer portion often occurs. Adding a certain amount of alcohol has the effect of suppressing this gel, so it is necessary to control the gel by charging as much alcohol as possible. Specifically, the ratio of alcohols / organoaluminum compound is 0.5 to 2.0 mole ratio, preferably 1.0 to 1.5 mole ratio. Further, the proportion of the linear ethylene / propylene random copolymer component (b2) in the linear propylene polymer component can be controlled by the amount of the alcohol added.

  The linear propylene polymer component (b1) is preferably a propylene homopolymer from the viewpoint of the rigidity of the polypropylene-based resin composition of the present invention. As long as the properties are not significantly impaired, a copolymer with a small amount of a comonomer can also be used. Specifically, for example, α-olefins other than propylene such as ethylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 4-methyl 1-pentene, styrene, vinylcyclopentene, vinyl A comonomer unit corresponding to one or more comonomers selected from the group consisting of vinyl compounds such as cyclohexane and vinyl norbornane, etc., can be contained preferably in a content of 5% by weight or less. Two or more of these comonomers may be copolymerized. The comonomer is preferably ethylene and / or 1-butene, most preferably ethylene. Here, the content of the comonomer unit is a value determined by infrared spectroscopy (IR).

Subsequent to the polymerization of the linear propylene polymer component (b1), the linear ethylene / propylene random copolymer component (b2) is polymerized. Component (b2) is preferably a high molecular weight linear ethylene / propylene random copolymer in order to adjust the die swell ratio and molecular weight distribution (Q value) to predetermined values.
The polymerization of component (b2) is preferably carried out in a hydrogen atmosphere as low as possible or substantially free of hydrogen in order to polymerize a high molecular weight polymer. The polymerization is subsequently carried out in the presence of the propylene polymer produced in the polymerization step of component (b1) and a catalyst. The polymerization temperature is usually selected from the range of 40 to 90 ° C. and the pressure of 2 × 10 ^{5 to} 35 × 10 ⁵ Pa.
In addition, linear propylene / ethylene block copolymers are sold by many companies, and those satisfying the desired physical properties may be purchased and used from these commercially available products.

(2) Physical property (i):
The MFR (230 ° C., 2.16 kg load) of the linear propylene polymer component (b1) of the linear propylene / ethylene block copolymer (B) used in the polypropylene resin composition of the present invention is 120 g / It is 10 minutes or more, preferably 135 to 3000 g / 10 minutes, more preferably 150 to 2000 g / 10 minutes. When the MFR is less than 120 g / 10 minutes, the surface appearance and the foam blow moldability of the polypropylene resin composition and the foam blow molded article tend to deteriorate. In order to bring the melt flow rate (MFR: 230 ° C., 2.16 kg load) of the linear propylene polymer component (b1) of the linear propylene / ethylene block copolymer into the range specified above, as described above, What is necessary is just to control hydrogen / propylene ratio in the superposition | polymerization process of a linear propylene polymer component (b1).

Characteristic (ii):
The composition ratio of the linear propylene / ethylene block copolymer (B) used in the polypropylene resin composition of the present invention to the entire (B) of the linear ethylene / propylene random copolymer component (b2) is 2 -50% by weight, preferably 5-40% by weight, more preferably 7-20% by weight. That is, the ratio of the linear propylene polymer component (b1) to the whole (B) is 50 to 98% by weight, preferably 60 to 95% by weight, and more preferably 80 to 93% by weight. When the component (b2) is less than 2% by weight (that is, the component (b1) exceeds 98% by weight), the foamed blow moldability and the drawdown resistance of the polypropylene resin composition and the foamed blow molded product are deteriorated. Tend. On the other hand, when the proportion of the component (b2) exceeds 50% by weight (that is, the component (b1) is less than 50% by weight), the surface appearance and foam blow moldability are deteriorated, and the fluidity is lowered. There is a tendency for productivity to decrease as the load on the plant increases. In order to set the ratio of the linear propylene / ethylene block copolymer to the entire block copolymer of the linear ethylene / propylene random copolymer component (b2) as described above, the linear Pressure, temperature, residence time in polymerization step of propylene polymer component (b1) and pressure, temperature, residence time in polymerization step of linear ethylene / propylene random copolymer component (b2), of alcohols / organoaluminum compounds Control the molar ratio

Characteristic (iii):
The intrinsic viscosity [eta] _copoly of linear ethylene-propylene random copolymer component of the linear propylene-ethylene block copolymer used in the polypropylene resin composition of the present invention (B) (b2) is 5. 3 dl / g or more, preferably 6.0 dl / g or more, more preferably 6.5 dl / g or more, 10.0 dl / g or less, preferably 9.5 dl / g or less, more preferably 9.0 dl / g. It is as follows. When the intrinsic viscosity _{[eta] copoly} is less than 5.3 dl / g, there is a tendency that the polypropylene resin composition and foamed blow moldability of the foamed blow molded article is deteriorated. Further, the intrinsic viscosity _{[eta] copoly} is more than 10.0 dl / g, there is a tendency that the surface appearance is deteriorated.
In order to bring the intrinsic viscosity [η] of the linear ethylene / propylene random copolymer component (b2) of the linear propylene / ethylene block copolymer to the range specified above, the ethylene / propylene random copolymer is used as described above. What is necessary is just to control hydrogen / (propylene + ethylene) ratio in the superposition | polymerization process of a superposition | polymerization part.

Characteristic (iv):
The MFR (230 ° C., 2.16 kg load) of the entire linear propylene / ethylene block copolymer (B) used in the polypropylene resin composition of the present invention is 45 g / 10 min or more, preferably 50 g / 10 min. As mentioned above, More preferably, it is 70-500 g / 10min, More preferably, it is 100-300 g / 10min. When the MFR is less than 45 g / 10 min, the surface appearance and injection foam moldability of the polypropylene resin composition and the foamed blow molded article are deteriorated, the fluidity is lowered, the load on the apparatus is increased, and the productivity is increased. There is a tendency to decrease.

Characteristic (v):
The die swell ratio of the entire linear propylene / ethylene block copolymer (B) used in the polypropylene resin composition of the present invention is 1.2 to 2.5, preferably 1.3 to 2.4. More preferably, it is 1.4-2.3. When the die swell ratio is less than 1.2, the polypropylene resin composition cannot maintain a good cell shape at a high magnification, and foam blow moldability deteriorates. On the other hand, those having a die swell ratio exceeding 2.5 are less practical because they are difficult to manufacture industrially.
The die swell ratio is such that when the constituent linear ethylene / propylene random copolymer component (b2) is polymerized, the polymerization is carried out in a hydrogen atmosphere as low as possible or in the absence of hydrogen to increase the molecular weight. By controlling, a large value can be obtained.

Characteristic (vi):
The linear propylene / ethylene block copolymer (B) used in the polypropylene resin composition of the present invention exhibits strain hardening in 180 ° C. extensional viscosity measurement. In the polypropylene resin composition of the present invention, the effect of showing strain hardening in the 180 ° C. extensional viscosity measurement is that the surface smoothness due to foam breakage at the die opening portion during foam blow molding is beautiful. It is easy to obtain a foamed blow molded article having uniform fine cells at high magnification.

The term “strain hardenability” as used herein means that the elongational viscosity gradually increases as the amount of stretch strain of the melt increases. It is a case of increasing.
In addition, regarding the method for evaluating strain hardening, the same value can be obtained in principle by any method as long as the uniaxial extensional viscosity can be measured. For example, details of the measuring method and measuring instrument can be obtained from a known document: Polymer. 42 (2001) 8663. As a preferable measurement method, there are Ales (Jig: Extensive Viscosity Fixture manufactured by TEA Instrument Co., Ltd.) manufactured by Rheometrics, and Melten Rheometer manufactured by Toyo Seiki Co., Ltd. The method using is mentioned.

  The degree of strain hardening is 2.0 or more, more preferably 2.5 or more, particularly preferably 3.0 or more, further preferably 5 in the 180 ° C. extensional viscosity measurement (strain rate: 1.0 / sec). It preferably has a strain hardening degree (λmax) of 0.0 or more. When the degree of strain hardening (λmax) is 2.0 or more, the polypropylene resin composition and the foamed blow molded article of the present invention have no bubble breakage at the die opening portion during foam blow molding, and surface smoothness Tends to be beautiful, and it becomes easy to obtain a foamed blow molded article having uniform fine cells at a high magnification.

Other characteristics:
The linear propylene / ethylene block copolymer (B) used in the polypropylene resin composition of the present invention is a ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) representing the molecular weight distribution (Q value = Mw / Mn) is preferably 7 to 13, more preferably 8 to 12. When the Q value is 7 or more, the polypropylene-based resin composition tends to maintain a good cell shape and easily obtain a high-magnification foam molded article. On the other hand, a linear propylene / ethylene block copolymer having a Q value of 13 or less is easy to produce and is economical.

  The ethylene content of the linear ethylene / propylene random copolymer component (b2) used in the polypropylene resin composition of the present invention is preferably 15 to 80% by weight, more preferably based on the total amount of the component (b2). It is 20 to 70% by weight, more preferably 25 to 45% by weight. When the ethylene content is 15% by weight or more, the foamed blow moldability and surface appearance of the polypropylene resin composition and the foamed blow molded article are good, while when the ethylene content is 80% by weight or less, the foamed state is further improved. .

  The weight average molecular weight (Mw) of the linear ethylene / propylene random copolymer component (b2) in the linear propylene / ethylene block copolymer (B) used in the polypropylene resin composition of the present invention is preferably Is 1 million or more, more preferably 110 to 8 million, still more preferably 1.2 to 7 million, and particularly preferably 1.5 to 4 million. When the weight average molecular weight (Mw) of the component (b2) is lower than 1,000,000, the effect of improving the foam blow moldability of the polypropylene resin composition tends to be insufficient.

MFR, die swell ratio, Mw, Q value, linear ethylene / propylene random copolymer component (b2) content and ethylene content are MFR meter, cross fractionator, Fourier transform infrared absorption spectrum analysis, gel permeation It is a value measured by chromatography (GPC). Intrinsic viscosity [η] _copy is measured using an Ubbelohde viscometer, and strain hardening in 180 ° C extensional viscosity measurement is measured using an extensional viscosity meter. The measurement conditions of the main items are described in the examples below.

3. Polypropylene polymer (C)
The polypropylene polymer (C) used in the present invention is a propylene / ethylene block copolymer having the requirements defined in the following (C-a) to (C-e).
The propylene / ethylene block copolymer here refers to propylene alone or a propylene / ethylene random copolymer component (c1) (hereinafter also referred to as component (c1)) having an ethylene content of 7% by weight or less, and the propylene / ethylene block copolymer. Common name obtained by sequential polymerization of propylene / ethylene random copolymer component (c2) (hereinafter also referred to as component (c2)) containing 3 to 20% by weight of ethylene more than component (c1). The component (c1) and the component (c2) do not necessarily have to be completely combined in a block shape.
(C-A): 30 to 95% by weight of propylene / ethylene random copolymer component (c1) having propylene alone or ethylene content of 7% by weight or less in the first step using a metallocene-based catalyst, and component in the second step It is a propylene / ethylene block copolymer obtained by sequential polymerization of 5 to 70% by weight of propylene / ethylene random copolymer component (c2) containing 3 to 20% by weight of ethylene more than (c1). .
(C-A): Melting peak temperature (Tm) measured by DSC method is 110 to 150 ° C.
(C-C): In the temperature-loss tangent curve obtained by solid viscoelasticity measurement, the tan δ curve has a single peak at 0 ° C. or lower.
(C-E): Melt flow rate (hereinafter also referred to as MFR) (230 ° C., 2.16 kg load) is 3 to 40 g / 10 min.

(1) Requirements (C-A)
The polypropylene polymer (C) used in the present invention is, as described above, using the metallocene catalyst, in the first step, propylene alone or ethylene content of 7% by weight or less, preferably 5% by weight or less, more preferably 30 to 95% by weight of propylene / ethylene random copolymer component (c1) of 3% by weight or less, and 3 to 20% by weight more ethylene than component (c1) in the second step, preferably 6 to 18% by weight % Of ethylene, more preferably 8 to 16% by weight of ethylene, and propylene / ethylene random copolymer component (c2) containing 5 to 70% by weight must be sequentially polymerized. Here, if the difference in ethylene content between the second step component (c2) and the first step component (c1) is less than 3% by weight, the foaming ratio of the present invention is reduced, so that the expansion ratio decreases. Tend. On the other hand, if it exceeds 20% by weight, the compatibility between the component (c1) and the component (c2) is reduced, so that the gas diffusion becomes unstable and the uniformity of the cell is deteriorated, resulting in uneven product thickness. Tend.
That is, in the polypropylene-based polymer (C), it is possible to sequentially polymerize components having different ethylene contents within a predetermined range in the first step and the second step, and in the foam blow molding of the present invention, gas diffusion is stabilized. The component (c1) is necessary to increase the uniformity of the cell and to develop a uniform product thickness (surface unevenness) and to prevent problems such as adhesion of reaction products to the reactor. ) After polymerization, it is necessary to use a method of polymerizing component (c2).

(C-I)
The melting peak temperature (Tm) measured by the DSC (Differential Scanning Calorimetry) method of the polypropylene polymer (C) used in the present invention is 110 ° C. to 150 ° C., preferably 115 to 148 ° C., more preferably 120 ° C. It must be in the range of ~ 145 ° C.
When Tm is less than 110 ° C., the foaming blow rate of the present invention tends to escape and the expansion ratio tends to decrease. On the other hand, when the temperature exceeds 150 ° C., the resin pressure tends to be high, so that the gas diffusion becomes unstable and the uniformity of the cell is deteriorated, and the product thickness tends to be uneven.

(C-W)
The polypropylene polymer (C) used in the present invention is required to have a single peak at 0 ° C. or lower in the tan δ curve in the temperature-loss tangent curve obtained by solid viscoelasticity measurement (DMA).
That is, in the present invention, during foam blow molding, gas diffusion is stabilized and cell uniformity is increased, and in order to express a uniform product thickness (surface irregularities), in the polypropylene-based polymer (C), It is necessary that the component (c1) and the component (c2) are not phase-separated, but in that case, the tan δ curve shows a single peak at 0 ° C. or lower.
Incidentally, when the component (c1) and the component (c2) are in a phase separation structure, the glass transition temperature of the amorphous part contained in the component (c1) and the glass transition of the amorphous part contained in the component (c2). Since each temperature is different, there are a plurality of peaks.
In the present invention, the solid viscoelasticity measurement is specifically performed by applying a sinusoidal strain of a specific frequency to a strip-shaped sample piece and detecting the generated stress. Here, the frequency is 1 Hz, and the measurement temperature is raised stepwise from −60 ° C. until the sample is melted and cannot be measured.
Further, it is recommended that the magnitude of distortion is about 0.1 to 0.5%. From the obtained stress, the storage elastic modulus G ′ and the loss elastic modulus G ″ are obtained by a known method, and the loss tangent (= loss elastic modulus / storage elastic modulus) defined by this ratio is plotted against the temperature. It shows a sharp peak in the temperature range of 0 ° C. or lower, and generally the peak of the tan δ curve at 0 ° C. or lower is for observing the glass transition of the amorphous part, and here this peak temperature is the glass transition temperature Tg (° C.). Define as

(C-D)
The MFR (230 ° C., 2.16 kg load) of the polypropylene polymer (C) used in the present invention is 3 to 40 g / 10 minutes, preferably 4 to 38 g / 10 minutes, more preferably 5 to 35 g / 10 minutes. It is necessary to be in the range. If the MFR is less than 3 g / 10 min, the resin pressure of the present invention tends to be high, so that the gas diffusion becomes unstable and the cell uniformity tends to be poor, and the product thickness tends to be uneven. On the other hand, when it exceeds 40 g / 10 minutes, there is a possibility that the drawdown at the time of foam blow molding becomes remarkable. The MFR can also be adjusted by using a molecular weight lowering agent. In addition, this component (C) can also use 2 or more types together.
In the present specification, MFR is a value measured at a test temperature = 230 ° C. and a load = 2.16 kg in accordance with JIS K7210.

(2) Production (i) Metallocene Catalyst The production of the polypropylene polymer (C) used in the present invention requires the use of a metallocene catalyst.
The type of the metallocene catalyst is not particularly limited as long as the polypropylene polymer (C) having the performance of the present invention can be produced. In order to satisfy the requirements of the present invention, for example, the following is shown. It is preferable to use a metallocene catalyst comprising such components (a) and (b), and component (c) used as necessary.
Component (a): at least one metallocene transition metal compound selected from transition metal compounds represented by the following general formula (1).
Component (b): at least one solid component selected from the following (b-1) to (b-4).
(B-1): A particulate carrier on which an organic aluminum oxy compound is supported.
(B-2): A particulate carrier carrying an ionic compound or Lewis acid capable of reacting with component (a) to convert component (a) into a cation.
(B-3): Solid acid fine particles.
(B-4): Ion exchange layered silicate.
Component (c): an organoaluminum compound.

As the component (a), at least one metallocene transition metal compound selected from transition metal compounds represented by the following general formula (1) can be used.
^{_{Q (C 5 H 4-a}} R 1 a) (C 5 H 4-b R 2 b) MeXY (1)
[Wherein Q represents a divalent binding group that bridges two conjugated five-membered ring ligands, Me represents a metal atom selected from titanium, zirconium, and hafnium, X and Y represent a hydrogen atom, A halogen atom, a hydrocarbon group, an alkoxy group, an amino group, a nitrogen-containing hydrocarbon group, a phosphorus-containing hydrocarbon group or a silicon-containing hydrocarbon group is shown, and X and Y may be the same or different from each other. R ¹ and R ² are hydrogen, hydrocarbon group, halogenated hydrocarbon group, silicon-containing hydrocarbon group, nitrogen-containing hydrocarbon group, oxygen-containing hydrocarbon group, boron-containing hydrocarbon group, or phosphorus-containing hydrocarbon group. Indicates. a and b are the number of substituents. ]

  Among them, preferred for the production of the polypropylene-based polymer (C) are a substituted cyclopentadienyl group, a substituted indenyl group crosslinked with a silylene group, a germylene group or an alkylene group having a hydrocarbon substituent as Q, Transition metal compounds comprising a ligand having a substituted fluorenyl group or a substituted azulenyl group, and particularly preferably a silylene group having a hydrocarbon substituent, or a 2,4-position substituted indenyl group crosslinked with a germylene group, Examples thereof include transition metal compounds composed of a ligand having a 2,4-position substituted azulenyl group.

As the component (b), at least one solid component selected from the aforementioned components (b-1) to (b-4) is used. Each of these components is a well-known thing, and can be used selecting it suitably from well-known techniques. Specific examples and manufacturing methods thereof are described in detail in JP-A No. 2002-284808, JP-A No. 2002-53609, JP-A No. 2002-69116, JP-A No. 2003-105015, and the like.
Of the component (b), particularly preferred is the ion-exchange layered silicate of component (b-4), and more preferred are chemical treatments such as acid treatment, alkali treatment, salt treatment, and organic matter treatment. Is an ion-exchange layered silicate.

Examples of the organoaluminum compound used as the component (c) as necessary include the following general formula (2)
AlRaP _3-a (2)
(Wherein R is a hydrocarbon group having 1 to 20 carbon atoms, P is hydrogen, halogen or alkoxy group, a is a number of 0 <a ≦ 3), trimethylaluminum, triethylaluminum, Trialkylaluminum such as tripropylaluminum and triisobutylaluminum or halogen- or alkoxy-containing alkylaluminum such as diethylaluminum monochloride and diethylaluminum monomethoxide. In addition, aluminoxanes such as methylaluminoxane can also be used. Of these, trialkylaluminum is particularly preferred.

  As a method for forming the catalyst, the component (a), the component (b) and, if necessary, the component (c) are brought into contact with each other to form a catalyst. In addition, the contact method will not be specifically limited if it is a method which can form a catalyst, A well-known method can be used.

Moreover, the usage-amount of component (a), (b), and (c) is arbitrary. For example, the amount of component (a) used relative to component (b) is preferably in the range of 0.1 μmol to 1,000 μmol, particularly preferably 0.5 μmol to 500 μmol, relative to 1 g of component (b). The amount of component (c) used relative to component (b) is preferably such that the amount of transition metal is 0.001 μmol to 100 μmol, particularly preferably 0.005 μmol to 50 μmol, relative to 1 g of component (b).
Furthermore, it is preferable that the catalyst used in the present invention is subjected to a prepolymerization treatment in which a small amount of polymer is brought into contact with an olefin in advance.

(Ii) Sequential polymerization In producing the polypropylene polymer (C) used in the present invention, it is necessary to sequentially polymerize the component (c1) and the component (c2).
That is, in the present invention, the polypropylene polymer (C) is a block copolymer obtained by sequentially polymerizing components having different ethylene contents in the first step and the second step, so that gas diffusion is stable during foam blow molding. In addition, the uniformity of the cells is increased, and this is necessary for expressing a uniform product thickness (surface irregularities).
In the present invention, it is necessary to use a method of polymerizing component (c2) after polymerizing component (c1) in order to prevent problems such as adhesion of reaction products to the reactor. is there.
When performing sequential polymerization, either a batch method or a continuous method can be used, but it is generally desirable to use a continuous method from the viewpoint of productivity.

In the case of the batch method, the component (c1) and the component (c2) can be polymerized even by using a single reactor by changing the polymerization conditions with time. A plurality of reactors may be connected in parallel as long as the effects of the present invention are not impaired.
In the case of the continuous method, it is necessary to use a production facility in which two or more reactors are connected in series because it is necessary to individually polymerize the component (c1) and the component (c2), but the effect of the present invention is not impaired. As long as components (c1) and (c2) are used, a plurality of reactors may be connected in series and / or in parallel.

(Iii) Polymerization process The polymerization process of a polypropylene-type polymer (C) can use arbitrary polymerization methods, such as a slurry method, a bulk method, and a gaseous-phase method. Although it is possible to use supercritical conditions as intermediate conditions between the bulk method and the gas phase method, they are substantially equivalent to the gas phase method, and are therefore included in the gas phase method without particular distinction.
Since component (c2) is readily soluble in organic solvents such as hydrocarbons and liquefied propylene, it is desirable to use a gas phase method for the production of component (c2).
For the production of the component (c1), there is no particular problem even if any process is used. It is desirable to use a vapor phase method to avoid problems.
Therefore, it is most desirable to polymerize the component (c1) first by the bulk method or the gas phase method using the continuous method, and subsequently polymerize the component (c2) by the gas phase method.

(Iv) Other polymerization conditions The polymerization temperature can be used without any particular problem as long as it is within a commonly used temperature range.
Specifically, a range of 0 to 200 ° C, more preferably 40 to 100 ° C can be used.
The polymerization pressure varies depending on the process to be selected, but the optimum pressure can be used without any problem as long as it is in a pressure range usually used. Specifically, a relative pressure with respect to atmospheric pressure can be used in the range of greater than 0 MPa to 200 MPa, more preferably 0.1 to 50 MPa. At this time, an inert gas such as nitrogen may coexist.
When the component (c1) is sequentially polymerized in the first step and the component (c2) is sequentially polymerized in the second step, it is desirable to add a polymerization inhibitor into the system in the second step. In the case of producing a propylene / ethylene block copolymer, a polymerization inhibitor is added to a reactor that performs ethylene-propylene random copolymerization in the second step. Product quality can be improved. Various techniques have been studied for this method, and examples thereof include the methods described in Japanese Patent Publication Nos. 63-54296, 7-25960, and 2003-2939. It is desirable to apply the method to the present invention.
As the polypropylene polymer (C), various products (for example, made by Nippon Polypro Co., Ltd., Wellnex series, etc.) are sold by many companies, and those having desired physical properties are purchased from these commercial products. May be used.

4). Thermoplastic resin (D)
In the polypropylene resin composition of the present invention, the hydrogenated product (d1) of the specific styrene / conjugated diene block copolymer described below (hereinafter also referred to simply as “(d1)”), ethylene / α-olefin. Copolymer rubber (d2) (hereinafter also simply referred to as “(d2)”)) or ethylene polymer resin (d3) (hereinafter also simply referred to as “(d3)”)). It is preferable that at least one thermoplastic resin (D) (hereinafter, also simply referred to as “(D)”) is blended.
The blending of (D) has an effect of improving the melt tension.

(1) Hydrogenated product of styrene / conjugated diene block copolymer (d1)
The hydrogenated product (d1) of the styrene / conjugated diene block copolymer used in the present invention is a hydrogenated product of a block copolymer using butadiene, isoprene or the like as the conjugated diene. For example, styrene / ethylene / butylene -In addition to styrene (SEBS) and styrene / ethylene / propylene / styrene (SEPS), there are hydrogenated products of block copolymers of styrene, butadiene and isoprene. Here, styrene derivatives such as α-methylstyrene and p-methylstyrene can also be used as styrene.

  By blending the hydrogenated product (d1) of these styrene / conjugated diene block copolymers, the melt tension is improved and the drawdown resistance in hollow molding is improved, which is very effective for large hollow molding. However, this blending reduces the melt fracture rate and makes it difficult to stretch, so in the case of hollow molding with a large blow ratio such as a deep-drawn shape or a complicated shape mold, it has extensibility such as parison tearing and uneven thickness of the molded product. In addition to the problem of lowering, the economic efficiency of the composition is impaired, so it is not preferable to add a large amount.

The hydrogenated product (d1) of the styrene / conjugated diene block copolymer used here is not particularly limited as long as a hollow molded body that satisfies the above-mentioned requirements can be obtained, but the density in ISO 2781 is 0. .90 to 0.92 g / cm ³ , styrene content of 31 to 35% by weight, and viscosity by BMS0380 method of 1 to 2 Pa · s are desirable.

(2) Ethylene / α-olefin copolymer rubber (d2)
In the present invention, the ethylene / α-olefin copolymer rubber (d2) can be added to improve paintability and the like.
The ethylene / α-olefin copolymer rubber (d2) used in the present invention is a copolymer rubber using propylene, butene-1, hexene-1, octene-1, etc. as an α-olefin, A terpolymer rubber (so-called EPDM) containing a non-conjugated diene such as ethylidene norbornene, dicyclopentadiene or 1,4-hexadiene as a three-component may be used.

The Mooney viscosity [ML1 + 4 (121 ° C.)] (according to ASTM D1646) of these ethylene / α-olefin copolymer rubber (d2) is 5 or more, preferably 10 or more, more preferably 20 to 40. When the Mooney viscosity is in the above range, it is preferable that the drawdown resistance of the composition is deteriorated and the shapeability during molding is suppressed.
Density of use in the present invention (d2) is preferably 0.890 g / cm ³ or less, more preferably 0.885 g / cm ³ or less.

(3) Ethylene polymer resin (d3)
Examples of the ethylene polymer resin (d3) used in the present invention include copolymers of ethylene as a main component and other ethylenic monomers such as butene-1 and hexene-1 in addition to an ethylene homopolymer. Specific examples include high-density polyethylene, low-density polyethylene, and linear low-density polyethylene. The ethylene polymer resin is effective in improving the drawdown resistance.

From the viewpoint of the surface quality and paintability of the molded product, an ethylene polymer resin having an MFR (JIS K6760, 230 ° C., 2.16 kg load) of 0.3 to 2 g / 10 min and a density of 0.920 g / cm ³ or more is preferable. . In particular, MFR (JIS K6760,230 ℃, 2.16kg load) 0.3 to 2 g / 10 min, density of 0.940 g / cm ³ or more 0.960 g / cm ³ or less of high density polyethylene. If the density exceeds 0.960 g / cm ³ , the resin pressure tends to be high during foam blow molding, so that the gas diffusion becomes unstable and the uniformity of the cells becomes poor, and the product thickness tends to be uneven. .
As these thermoplastic resins (D), since various products are commercially available from many companies, desired ones may be purchased and used.

5. Content Ratio of Components The content of the crystalline polypropylene (A) used in the present invention is 15% by weight or more, preferably 19% by weight or more, and more preferably 25% by weight or more. The content of (A) is 88% by weight or less, preferably 82.5% by weight or less, more preferably 77% by weight or less. When the content of (A) exceeds 88% by weight, the foaming property tends to be lowered. On the other hand, when the content is less than 15% by weight, the blowing property tends to be lowered, and the melt tension and the drawdown resistance tend to be lowered. is there.

  The content of the linear propylene / ethylene block copolymer (B) used in the present invention is 10% by weight or more, preferably 15% by weight or more, more preferably 20% by weight or more. The content of (B) is 60% by weight or less, 58% by weight or less, more preferably 55% by weight or less. When content of (B) exceeds 60 weight%, there exists a tendency for a blow characteristic to fall and for a melt tension and drawdown-proof property to fall. On the other hand, if it is less than 10% by weight, the foamability tends to decrease.

  The content of the polypropylene polymer (C) used in the present invention is 2% by weight or more, preferably 2.5% by weight or more, more preferably 3% by weight or more. The content of (C) is 25% by weight or less, preferably 23% by weight or less, more preferably 20% by weight or less. When content of (C) exceeds 25 weight%, thermal stability (return property) will fall. On the other hand, if it is less than 2% by weight, the foaming properties tend to be lowered.

The content of the thermoplastic resin (D) used in the present invention is preferably 0.5% by weight or more, more preferably 1% by weight or more. Further, the content of the thermoplastic resin (D) is preferably 20% by weight or less, more preferably 15% by weight or less, more preferably 10% by weight or less. When the content of (D) exceeds 20% by weight, the foamability tends to decrease.
In addition, in this specification, each compounding ratio of (A)-(D) is a value when the total amount of (A), (B), (C), and (D) is 100% by weight. .

6). Other components In the polypropylene-based resin composition of the present invention, in addition to (A), (B), (C) and (D), if necessary, for example, within the range not significantly impairing the effects of the present invention. Arbitrary additive components can be blended in order to further improve the effects or to impart other effects.

The polypropylene resin composition of the present invention may contain other blending components such as polymers, fillers, additives and the like other than the thermoplastic resin (D) as necessary.
Examples of the polymer other than the thermoplastic resin (D) that may be contained in the polypropylene resin composition of the present invention include polyolefins other than the above (A), (B), and (C), polystyrene, polyamide, polyester, Examples include polyacetal, polyvinyl chloride, and polycarbonate.

  Examples of polyolefins other than the above (A), (B) and (C) of the present invention include ethylene homopolymers, ethylene / propylene copolymers, ethylene / butene copolymers, ethylene / hexene copolymers, ethylene / octene copolymers. Copolymer, ethylene / propylene / butene copolymer, ethylene / propylene / hexene copolymer, ethylene / propylene / octene copolymer, ethylene / butene / hexene copolymer, ethylene / butene / octene copolymer, ethylene / hexene・ Ethylene polymers such as octene copolymer, propylene homopolymer, propylene / ethylene copolymer, propylene / butene copolymer, propylene / hexene copolymer, propylene / octene copolymer, propylene / ethylene / butene Copolymer, propylene / ethylene / hexene copolymer, propylene・ Ethylene / octene copolymer, propylene / butene / hexene copolymer, propylene / butene / octene copolymer, propylene polymer such as propylene / hexene / octene copolymer, butene polymer, etc. Examples include polymers other than the plastic resin (D).

  Polystyrene includes styrene homopolymers, copolymers of styrene and acrylonitrile, methyl methacrylate, α-methylstyrene, block copolymers or random copolymers of styrene and butadiene, isoprene, etc., or hydrogenated products thereof. And other polymers than the thermoplastic resin (D).

  Examples of the filler that may be contained in the polypropylene resin composition of the present invention include plate-like inorganic fillers such as talc, mica, and montmorillonite, short fiber glass fibers, long fiber glass fibers, carbon fibers, aramid fibers, and alumina. Fibrous inorganic fillers such as fiber, boron fiber and zonolite, acicular (whisker) inorganic such as potassium titanate, magnesium oxysulfate, silicon nitride aluminum borate, basic magnesium sulfate, zinc oxide, wollastonite, calcium carbonate Examples include fillers, granular inorganic fillers such as precipitated calcium carbonate, heavy calcium carbonate, and magnesium carbonate, balun-like inorganic fillers such as glass balloons, and organic fillers such as polyester fiber, kenaf, jute, and wood flour. The

  Additives that may be contained in the polypropylene resin composition of the present invention include antioxidants, heat stabilizers, weathering stabilizers, ultraviolet absorbers, nucleating agents, dispersants, pigments, dyes, antistatic agents, A lubricant, a metal deactivator, a flame retardant, a neutralizing agent, a foaming agent, a crosslinking agent, a plasticizer and the like can be mentioned.

  Specifically, light stabilizers such as hindered amines, ultraviolet absorbers such as benzotriazoles, nucleating agents such as sorbitols, colorants such as pigments, antioxidants such as phenols and phosphoruss, nonionics Antistatic agents such as inorganic compounds, antibacterial and antifungal agents such as thiazoles, flame retardants such as halogen compounds, process oils (blending oils), plasticizers, antiionics such as nonionics, Dispersants such as organic metal salts, lubricants such as fatty acid amides, metal deactivators such as nitrogen compounds, nonionic surfactants, and polypropylenes other than (A) to (D) as described above And the like, thermoplastic resins such as polyamide and polyester, fillers, elastomers and the like. These components may be used in combination of two or more, may be added to the composition, may be added to each component, and may be used in combination of two or more in each component.

As light stabilizers and ultraviolet absorbers, for example, hindered amine compounds, benzotriazoles, benzophenones and salicylates are used to impart and improve the weather resistance and durability of linear polypropylene resin compositions and foamed blow molded articles. It is valid.
Specific examples of the hindered amine compound include a condensate of dimethyl succinate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine; poly [[6- (1, 1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2 , 2,6,6-tetramethyl-4-piperidyl) imino]]; tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate; tetrakis ( 1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate; bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebake Bis-2,2,6,6-tetramethyl-4-piperidyl sebacate and the like, and examples of the benzotriazole type include 2- (2′-hydroxy-3 ′, 5′-di-t-butyl) Phenyl) -5-chlorobenzotriazole; 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole and the like. -Methoxybenzophenone; 2-hydroxy-4-n-octoxybenzophenone and the like. Examples of the salicylates include 4-t-butylphenyl salicylate; 2,4-di-t-butylphenyl 3 ', 5'-di -T-butyl-4'-hydroxybenzoate and the like.

In addition, as a nucleating agent, for example, inorganic, sorbitol, carboxylic acid metal salt, and organic phosphate, the rigidity, heat resistance and hardness of linear polypropylene resin compositions and injection-foamed molded articles, injection It is effective for imparting and improving foam moldability.
Specific examples include talc as an inorganic type; silica and the like, and 1,3,2,4-dibenzylidene-sorbitol as a sorbitol type; 1,3,2,4-di- (p-methyl-benzylidene). Sorbitol; 1,3,2,4-di- (p-ethyl-benzylidene) sorbitol; 1,3,2,4-di- (2 ′, 4′-di-methyl-benzylidene) sorbitol; p-chlorobenzylidene-2,4-p-methyl-benzylidene-sorbitol; 1,3,2,4-di- (p-propylbenzylidene) sorbitol and the like. Hydroxy-di-pt-butylbenzoate; sodium benzoate; calcium montanate and the like. 4-t-butylphenyl) phosphate; sodium-2,2′-methylene-bis (4,6-di-t-butylphenyl) phosphate; lithium-2,2′-methylene-bis (4,6- And di-t-butylphenyl) phosphate.

In addition, as a colorant, for example, an inorganic or organic pigment, such as a linear polypropylene resin composition and a foamed blow molded article, the colored appearance, appearance, texture, commercial value, weather resistance, durability, etc. It is effective for granting and improving.
Specific examples of the inorganic pigment include titanium oxide; iron oxide (eg, bengara); chromic acid (eg, galvanized lead); molybdic acid; selenide sulfide; ferrocyanide and carbon black. A poorly soluble azo lake; a soluble azo lake; an insoluble azo chelate; a condensable azo chelate; an azo pigment such as other azo chelates; a phthalocyanine pigment such as phthalocyanine blue; a phthalocyanine green; an anthraquinone; a perinone; a perylene; Rake; quinacridone type; dioxazine type; isoindolinone type. Moreover, in order to make a metallic tone or a pearl tone, an aluminum flake; a pearl pigment can be contained. Moreover, dye can also be contained.

Antioxidants such as phenol-based, phosphorus-based, and sulfur-based antioxidants are imparted with heat resistance stability, processing stability, heat aging resistance, etc. of linear polypropylene resin compositions and foamed blow molded products. It is effective for improvement.
Examples of phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol; tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl). Propionate] -methane; tris (3,5-di-t-butyl-4-hydroxyphenyl) isocyanurate and the like. Examples of phosphorus antioxidants include distearyl pentaerythritol diphosphite; tris (2,4-di-t-butylphenyl) phosphite; tris (2-t-butyl-4-methylphenyl) phosphite. For example, fights. Moreover, as a sulfur type antioxidant, distearyl thiodipropionate etc. are mentioned, for example.

As the antistatic agent, for example, a nonionic or cationic antistatic agent is effective for imparting and improving the antistatic property of the linear polypropylene resin composition and the foamed blow molded article.
Specific examples include polyoxyethylene alkylamines; polyoxyethylene alkylamides; polyoxyethylene alkylphenyl ethers; stearic acid monoglycerides; alkyldiethanolamines; alkyldiethanolamides; alkyldiethanolamine fatty acid monoesters;

7). Production method, characteristics and use of polypropylene resin composition The production method of the polypropylene resin composition of the present invention includes (A), (B), (C), (D), and (E) described later. Are blended in the above blending ratio, and are applied by dry blending such as dusting or hand blending, various blenders such as V blenders and tumbler mixers, methods of mixing using a mixer, etc., single screw extruder, twin screw extruder , Banbury mixer, roll mixer, Brabender plastograph, kneader and other kneading and granulating methods, and each of the above components separately (or partly blended) as it is with a foaming agent A method of directly supplying to a molding machine can be mentioned.

  When selecting a kneading / granulating method, it is usually preferable to knead / granulate using a twin screw extruder. In this kneading and granulation, the blends (A) to (E) may be kneaded at the same time, and each component is divided to improve performance. For example, first, (A) and (C) It is also possible to knead a part or all of the above, and then knead and granulate the remaining components.

  The polypropylene resin composition of the present invention has an MFR (230 ° C., 2.16 kg) of 1 to 15 g / 10 minutes, preferably 1.05 to 12 g / 10 minutes, more preferably 1.1 to 9 g / 10 minutes. is there. If the MFR exceeds the upper limit, the melt tension tends to decrease. If it is less than the lower limit, the foamability tends to decrease, and the load on the apparatus becomes high, which is not preferable.

The foamed blow molded article of the present invention is a molded article obtained by adding the following foaming agent (E) to the polypropylene resin composition of the present invention and foaming and blowing the polypropylene resin composition.
The foam blow molding method for producing the foam blow molded article in the present invention is not particularly limited, and usually includes a foam molding method using a direct blow molding machine or an accumulator blow molding machine.
The foamed blow molded article of the present invention may have a laminated structure with a non-foamed layer, a barrier layer, and the like.

8). Foaming agent (E)
The foaming agent (E) (also simply referred to as “(E)”) used in the present invention is a chemical foaming agent, a physical foaming agent, a microcapsule, or the like. It is used for the purpose of developing (foaming ratio, foaming state).

  As a kind of foaming agent, a chemical foaming agent, a physical foaming agent, a microcapsule, etc. are mentioned, for example, if it can be normally used for foam blow molding, it can use without a restriction | limiting in particular. These foaming agents can be used alone or in admixture of two or more.

  Examples of the chemical foaming agent include inorganic chemical foaming agents and organic chemical foaming agents. Examples of the inorganic chemical foaming agent include sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, and ammonium nitrite. Examples of the organic chemical foaming agent include azodicarbonamide (ADCA), N, N′-dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide, 4,4′-diphenyldisulfonyl azide, and the like. As the chemical foaming agent, an inorganic chemical foaming agent is preferable from the viewpoint that a normal blow molding machine can be used safely and uniform fine bubbles are easily obtained in the molded body.

  To these chemical foaming agents, an organic acid, an organic acid metal salt, and a nucleating agent can be added in order to stably and uniformly make the bubbles of the foamed molded article. An example of the organic acid is citric acid. Examples of the organic acid metal salt include sodium citrate. Examples of the nucleating agent include inorganic fine particles, and examples of the inorganic fine particles include talc and lithium carbonate.

  As described above, various chemical foaming agents include inorganic and organic types. Preferred examples include sodium bicarbonate, citric acid, sodium citrate, and mixtures of two or more thereof. Preferred are sodium bicarbonate, a combination of sodium bicarbonate and sodium citrate, and a combination of sodium bicarbonate and citric acid.

These chemical foaming agents are, for example, processed into particles having an average particle diameter of 1 to 100 μm and, when foam blow molding is performed, the mixture is applied to the polypropylene resin composition and mixed, and then supplied to a blow molding machine or the like. When blow molding is performed, the gas is injected from the middle of a cylinder of a blow molding machine or decomposed in the cylinder to generate a gas such as carbon dioxide.
Moreover, a chemical foaming agent can also be used, after granulating as a masterbatch which used the polyolefin resin as the base material from points, such as a handleability, storage stability, and a polypropylene resin. Thereby, contamination of the hopper of the molding machine and adhesion of powder to the surface of the molded body can be suppressed. In this case, it is preferably used as a master batch of polyolefin resin having a concentration of 10 to 50% by weight.
Alternatively, the chemical foaming agent may be added once, and the chemical foaming agent may be decomposed by pelletization, or the chemical foaming agent having a high concentration may be decomposed in advance and the residue may be added. The chemical foaming agent decomposes in the cylinder of the blow molding machine, and the foaming residue can become the foaming nucleating agent.

  The addition amount of the chemical foaming agent is about 0.1 to 10 parts by weight, preferably about 0.5 to 5 parts by weight with respect to 100 parts by weight of the polypropylene resin composition.

Examples of the physical foaming agent include inert gas, low boiling point organic solvent vapor, halogen-based inert solvent vapor, carbon dioxide gas, and air.
Examples of the inert gas include nitrogen, argon, helium, neon, and astatine. Examples of the low-boiling organic solvent vapor include methanol, ethanol, propane, butane, and pentane. Examples of the active solvent vapor include dichloromethane, chloroform, carbon tetrachloride, Freon, and nitrogen trifluoride. Among these, since it is not necessary to use steam, it is inexpensive, environmental pollution, and the risk of fire is extremely low, it is preferable to use inert gas, carbon dioxide gas, and air, especially carbon dioxide gas, nitrogen, Argon and helium are preferable, and carbon dioxide and nitrogen are particularly preferable.
Furthermore, the physical foaming agent is preferably in a supercritical state, which has the advantage of facilitating gas melting into the resin.
A physical foaming agent is injected as a gaseous or supercritical fluid into the polypropylene resin composition or the like in a cylinder of an injection molding machine, and is dispersed or dissolved. By releasing pressure from a die slip, It functions as a foaming agent.
The addition amount of the physical foaming agent is about 0.5 to 30 parts by weight, preferably about 1 to 15 parts by weight with respect to 100 parts by weight of the polypropylene resin composition.

Microcapsules are obtained by encapsulating a foaming agent (expansion agent) in a shell made of various thermoplastic resins. Examples of the blowing agent (swelling agent) include specific freons such as trichlorofluoromethane, dichlorofluoromethane, and dichlorofluoroethane, alternative freons, hydrocarbons such as n-pentane, isopentane, isobutane, and petroleum ether, Examples thereof include chlorinated hydrocarbons such as methyl chloride, methylene chloride, and dichloroethylene. The average particle size of the microcapsule foaming agent is usually 2 to 50 μm.
These microcapsules are usually supplied to a blow molding machine or the like after being previously mixed with the polypropylene resin composition or the like.
The addition amount of the microcapsule is about 0.5 to 30 parts by weight, preferably about 1 to 15 parts by weight with respect to 100 parts by weight of the polypropylene resin composition.

  These foaming agents are preferably used in combination with a chemical foaming agent and a physical foaming agent in order to obtain more uniform and fine bubbles in a polypropylene resin composition and a foamed blow molded article, and to increase the expansion ratio. In particular, it is preferable to use an inorganic chemical foaming agent in combination with carbon dioxide or nitrogen as a physical foaming agent.

9. Uses of Foam Blow Molded Body Applications of the foam blow molded body of the present invention include parts for automobile parts, houses, construction equipment, and the like. As automobile parts, ducts, protective coating materials for pipes, resonators, deck boards, etc., and as parts for houses and construction facilities, it can be suitably used for heat insulation panels, daily goods, tanks and the like.
In particular, since the foamed blow molded article of the present invention is excellent in heat insulation, it is effective in heat insulation, heat retention, and prevention of dew condensation when used in automobile parts ducts, heat insulation panels for houses and construction facilities.

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
The evaluation methods, analysis methods and materials used in the examples are as follows.

1. Evaluation method, analysis method (1) Surface appearance (glossiness):
The 60 ° specular glossiness of the foamed blow molded article surface was measured based on the method specified in JIS Z8741.

(2) Foaming ratio:
The raw material polypropylene resin composition and the chemical foaming agent were supplied to a direct blow molding machine, and the foamed parison was melt extruded at a die setting temperature of 170 ° C. The ratio between the specific gravity of the raw material polypropylene resin composition and the specific gravity of the obtained parison was defined as the expansion ratio. Specific gravity was determined by an underwater substitution method.

(3) Cell form:
The micrograph of the cross section which cut | disconnected the foaming molding (parison) obtained by said (2) in the thickness direction was observed visually, and was evaluated. The evaluation criteria are the following three stages.
Cell diameter is small and uniform throughout ○
Cell diameter is small and partly uneven △
Cell diameter is not uniform or completely peeled ×
In this case, ◯ and Δ are levels that are judged to have practicality.

(4) Drawdown resistance:
The ratio of the upper wall thickness of the parison to the lower wall thickness of the parison when a polypropylene resin composition and a chemical foaming agent are fed to a direct blow molding machine and the foamed parison is extruded by a length of 1.0 m at a die setting temperature of 170 ° C. Of 0.8 to 1.0 was judged as good, and those of less than 0.8, or poorly formed or unmoldable.

(5) Thermal stability (returnability):
The polypropylene resin composition and the chemical foaming agent were supplied to a direct blow molding machine, and a foamed parison was extruded 1.0 m in length at a die set temperature of 170 ° C. The parison was pulverized with a pulverizer and molded with a direct blow molding machine. The case where the parison is stable even if it is repeated 5 times or more is ◎, and the case where the parison is stable even if it is repeated 3 times or more and less than 5 times ○ The case where the parison is stable is repeated 1 or more times but less than 3 times The thing was made into x, and the thing which has a large drawdown and was not able to repeat a product once was made into x.

(6) MFR (unit: g / 10 min):
Conforms to JIS K7210. Test temperature: 230 ° C., load: 2.16 kg.

(7) Melt tension (unit: g):
Using a Toyo Seiki Capillograph, put the resin in a cylinder with a diameter of 10 mm heated to a temperature of 190 ° C., and extrude the molten resin through an orifice with a diameter of 2.095 mm and a length of 8 mm at an indentation speed of 10 mm / min. Was taken at a speed of 4.0 m / min, and the tension detected by the pulley was taken as melt tension (MT).

(8) Melt spreadability (unit: m / min):
Using a Toyo Seiki Capillograph, put the resin in a cylinder with a diameter of 10 mm heated to a temperature of 190 ° C., and extrude the molten resin through an orifice with a diameter of 2.095 mm and a length of 8 mm at an indentation speed of 10 mm / min. Was taken at a speed of 4.0 m to 200 m / min, and the speed at which the molten resin broke was measured and used as an index of parison extensibility.

(9) Content of linear ethylene / propylene random copolymer component (b2) and ethylene content:
(A) Analyzer used:
(A-1) Cross sorter:
Diamond Instruments CFC T-100 (abbreviated as CFC)
(A-2) Fourier transform infrared absorption spectrum analysis:
FT-IR, Perkin Elmer 1760X
The fixed wavelength infrared spectrophotometer attached as a CFC detector was removed, and an FT-IR was connected instead, and this FT-IR was used as a detector. The transfer line from the outlet of the solution eluted from the CFC to the FT-IR was 1 m long, and the temperature was maintained at 140 ° C. throughout the measurement. The flow cell attached to the FT-IR was one having an optical path length of 1 mm and an optical path width of 5 mmφ, and the temperature was maintained at 140 ° C. throughout the measurement.
(A-3) Gel permeation chromatography (GPC):
The GPC column in the latter part of the CFC was used by connecting three AD806MS manufactured by Showa Denko KK in series.

(B) CFC measurement conditions:
(B-1) Solvent: Orthodichlorobenzene (ODCB)
(B-2) Sample concentration: 4 mg / mL
(B-3) Injection amount: 0.4 mL
(B-4) Crystallization: The temperature was lowered from 140 ° C. to 40 ° C. over about 40 minutes.
(B-5) Sorting method:
The fractionation temperature at the time of temperature-raising elution fractionation is 40, 100, and 140 ° C., and fractionation is performed in three fractions in total. In addition, the elution ratio (unit:% by weight) of the component eluting at 40 ° C. or lower (fraction 1), the component eluting at 40 to 100 ° C. (fraction 2), and the component eluting at 100 to 140 ° C. (fraction 3), respectively W ₄₀ , W ₁₀₀ , and W ₁₄₀ were defined. W ₄₀ + W ₁₀₀ + W ₁₄₀ = 100. Each fractionated fraction was automatically transported to the FT-IR analyzer as it was.
(B-6) Solvent flow rate during elution: 1 mL / min

(C) FT-IR measurement conditions:
After elution of the sample solution started from GPC at the latter stage of CFC, FT-IR measurement was performed under the following conditions, and GPC-IR data was collected for each of fractions 1 to 3 described above.
(C-1) Detector: MCT
(C-2) Resolution: 8 cm ⁻¹
(C-3) Measurement interval: 0.2 minutes (12 seconds)
(C-4) Number of integrations per measurement: 15 times

(D) Post-processing and analysis of measurement results:
The elution amount and molecular weight distribution of the components eluted at each temperature were determined using the absorbance at 2945 cm ⁻¹ obtained by FT-IR as a chromatogram. The elution amount was normalized so that the total elution amount of each elution component was 100%. Conversion from the retention capacity to the molecular weight was performed using a standard curve prepared in advance with standard polystyrene.
The standard polystyrenes used were 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. For the calibration curve, a cubic equation obtained by approximation by the least square method was used. Conversion to molecular weight uses a general-purpose calibration curve with reference to “Size Exclusion Chromatography” written by Sadao Mori (Kyoritsu Shuppan). The following numerical values were used in the viscosity equation ([η] = K × M ^α ) used at that time.
(D-1) When creating a calibration curve using standard polystyrene:
K = 0.000138, α = 0.70
(D-2) Sample measurement of linear propylene / ethylene block copolymer (B):
K = 0.000103, α = 0.78
The ethylene content distribution (distribution of ethylene content along the molecular weight axis) of each eluted component is a ratio of the absorbance of 2956 cm ⁻¹ and the absorbance of 2927 cm ⁻¹ obtained by FT-IR, and is obtained by using polyethylene, polypropylene, or ¹³ Converted to ethylene content (% by weight) using a calibration curve prepared in advance using ethylene-propylene rubber (EPR) and mixtures thereof whose ethylene content is known by C-NMR measurement, etc. Asked.

(E) Content of linear ethylene / propylene random copolymer component (b2):
The content (Wc) of the linear ethylene / propylene random copolymer component (b2) in the linear propylene / ethylene block copolymer (B) used in the present invention is theoretically represented by the following formula (I). It was defined and found in the following procedure.
Wc (% by weight) = W ₄₀ × A ₄₀ / B ₄₀ + W ₁₀₀ × A ₁₀₀ / B ₁₀₀ (I)
In the formula (I), W ₄₀ and W ₁₀₀ are elution ratios (unit:% by weight) in each of the above-described fractions, and A ₄₀ and A ₁₀₀ are actual values in the respective fractions corresponding to W ₄₀ and W _100. the average ethylene content of measurement (unit: wt%), B _40, B _100, the ethylene content of the linear ethylene-propylene random copolymer component contained in each fraction (b2) (unit: wt% ). A method for _obtaining A ₄₀ , A ₁₀₀ , B ₄₀ , and B ₁₀₀ 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 the linear ethylene / propylene random copolymer component (b2) contained in the fraction 1 (portion soluble at 40 ° C.). When fraction 1 contains only component (b2) and does not contain linear propylene polymer component (b1), W ₄₀ contributes to the content of component (b2) derived from fraction 1 as it is in the whole. However, since the fraction 1 includes a component derived from the component (b2) in addition to the component derived from the component (b2) (component having extremely low molecular weight and atactic polypropylene), it is necessary to correct the portion. is there. Therefore, by multiplying W ₄₀ by A ₄₀ / B ₄₀ , the amount derived from the component (b2) in fraction 1 is calculated. For example, when the average ethylene content (A ₄₀ ) of fraction 1 is 30% by weight and the ethylene content (B ₄₀ ) of component (b2) contained in fraction 1 is 40% by weight, 40 = 3/4 (that is, 75% by weight) is derived from the component (b2), and 1/4 is derived from the component (b1). In this way, the operation of multiplying A ₄₀ / B ₄₀ by the first term on the right side means that the contribution of the component (b2) is calculated from the weight% (W ₄₀ ) of the fraction 1. The same applies to the second term on the right side, and for each fraction, the component (b2) content is obtained by calculating and adding the contribution of the component (b2).

(E-1) As described above, the average ethylene contents corresponding to fractions 1 and 2 obtained by CFC measurement were A ₄₀ and A ₁₀₀ , respectively (unit is weight%). A method for obtaining the average ethylene content will be described later.

(E-2) The ethylene content corresponding to the peak position in the differential molecular weight distribution curve of fraction 1 is defined as B ₄₀ (unit is% by weight). Fraction 2 is considered to be substantially defined as B ₁₀₀ = 100 in the present invention because it is considered that the rubber part is completely eluted at 40 ° C. and cannot be defined with the same definition. B ₄₀ and B ₁₀₀ are ethylene contents of the linear ethylene / propylene random copolymer component (b2) contained in each fraction, but it is practically impossible to obtain this value analytically. . The reason is that there is no means for completely separating and separating the linear propylene polymer component (b1) and the component (b2) mixed in the fraction.
As a result of examination using various model samples, B ₄₀ can explain the improvement effect of material physical properties well by using the ethylene content corresponding to the peak position of the differential molecular weight distribution curve of fraction 1. all right. Further, B ₁₀₀ has crystallinity derived from ethylene chain, and the amount of component (b2) contained in these fractions is relatively small compared to the amount of component (b2) contained in fraction 1. For two reasons, the approximation to 100 is closer to the actual situation and hardly causes an error in calculation. Therefore, the analysis was performed with B ₁₀₀ = 100.

(E-3) The content (Wc) of the linear ethylene / propylene random copolymer component (b2) was determined according to the following formula for the above reason.
Wc _{(wt%) = W 40 × A 40} / B 40 + W 100 × A 100/100 (II)
That is, W ₄₀ × A ₄₀ / B ₄₀ which is the first term on the right side of the formula (II) indicates the content (% by weight) of the component (b2) having no crystallinity, and W ₁₀₀ × A which is the second term. _100/100 shows a component having a crystallinity (b2) content (wt%).
_Here, the average of _{B 40} and CFC each fraction 1 and 2 obtained by measuring the ethylene content _{A 40, A 100} was determined as follows.
Ethylene content corresponding to the peak position of the differential molecular weight distribution curve is B _40. In addition, the sum of the products of the weight ratio for each data point and the ethylene content for each data point, which is captured as data points at the time of measurement, is the average ethylene content A _{40 of} fraction 1. The average ethylene content A _{100 of} fraction 2 was determined in the same manner.

The significance of setting the three types of fractionation temperatures is as follows. In the CFC analysis of the present invention, a polymer having no crystallinity at 40 ° C. (for example, most of the linear ethylene / propylene random copolymer component (b2) or the linear propylene polymer component (b1) Among them, it has a significance that it is a temperature condition necessary and sufficient for fractionating only extremely low molecular weight components and atactic components). 100 ° C. means a component that is insoluble at 40 ° C. but becomes soluble at 100 ° C. (for example, component (b2) having a crystallinity due to a chain of ethylene and / or propylene, and a low crystallinity The temperature is necessary and sufficient to elute only the component (b1)). 140 ° C. is a component that is insoluble at 100 ° C. but becomes soluble at 140 ° C. (eg, component (b1) having particularly high crystallinity, and component (b2) having an extremely high molecular weight and extremely high molecular weight) This temperature is necessary and sufficient to elute only the component having ethylene crystallinity and recover the entire amount of the propylene / ethylene block copolymer (B) used in the analysis. It should be noted that W ₁₄₀ does not contain any component (b2) or is present in a very small amount, and can be substantially ignored. Therefore, the content of component (b2) and the ethylene content of component (b2) Excluded from calculation.

(F) Ethylene content of linear ethylene / propylene random copolymer component (b2):
The ethylene content of the linear ethylene / propylene random copolymer component (b2) in the propylene / ethylene block copolymer (B) used in the present invention was determined from the following formula using the values described above.
Ethylene content (% by weight) of component (b2) = (W ₄₀ × A ₄₀ + W ₁₀₀ × A ₁₀₀ ) / Wc
[Wc is the ratio (% by weight) of the component (b2) obtained previously. ]

(10) Intrinsic viscosity [η] _{copy of the} linear ethylene / propylene random copolymer component (b2):
The intrinsic viscosity [eta] _copoly of linear ethylene-propylene random copolymer component in the propylene-ethylene block copolymer used in the present invention (B) (b2) was determined as follows.
First, after completion of the polymerization of the linear propylene polymer component (b1), a part was sampled from the polymerization tank, and the intrinsic viscosity [η] _{homo of the part} was measured. Next, after the linear propylene polymer component (b1) is polymerized, the intrinsic viscosity [η] of the final polymer (F) obtained by polymerizing the linear ethylene / propylene random copolymer component (b2) [η ] _F was measured. This measurement was performed at a temperature of 135 ° C. using decalin as a solvent using an Ubbelohde viscometer. [Η] _copy was determined from the following relationship.
[Η] _F = (100−Wc) / 100 × [η] _homo + Wc / 100 × [η] _copy

(11) Die swell ratio:
The die swell ratio is a value obtained by the following method.
The in-cylinder temperature of the MFR meter was set to 190 ° C. The orifice used had a length of 8.00 mm, a diameter of 1.00 mmφ, and L / D = 8. In addition, a graduated cylinder containing ethyl alcohol was placed directly under the orifice (the distance between the orifice and the ethyl alcohol liquid surface was 20 ± 2 mm). In this state, the sample was put into the cylinder, and the load was adjusted so that the amount of extrusion per minute was 0.10 ± 0.03 g. The extrudates after 6 to 7 minutes were dropped into ethanol and solidified before being collected. The maximum and minimum values of the diameter of the strand-shaped sample of the collected extrudate were measured at 3 locations, 1 cm from the top, 1 cm from the bottom, and the center. Ratio.

(12) Strain hardenability:
Strain hardenability was measured by the following method.
(A) Apparatus: Ales manufactured by Rheometrics
(B) Jig: EXTENSIONAL VISUALITY FIXTURE (c) manufactured by TA Instruments Inc. Test temperature: 180 ° C.
(D) Strain rate: 1.0 / sec
(E) Sample test piece: press-molded sheet of 15 mm × 10 mm, thickness 0.5 mm

(F) Determination of the presence or absence of strain hardening:
The elongational viscosity at a strain rate of 1.0 / sec is plotted as a logarithmic graph of the amount of strain on the horizontal axis and the elongational viscosity ηE (Pa · s) on the vertical axis. As the amount of strain increases, the extensional viscosity gradually increases, and when the rate of increase in the extensional viscosity increases abruptly from a certain amount of strain, this is a case where strain hardening is exhibited. The case was made “strain hard”. On the other hand, the case where the above-mentioned phenomenon was not substantially recognized was set as “no strain”.

(G) Calculation method of strain hardening degree (λmax):
On the above log-log graph, the viscosity immediately before the strain hardening is approximated by a straight line, and the maximum value (ηmax) of the extension viscosity η _E until the strain amount becomes 4.0 is obtained. Let ηlin be the viscosity on the approximate straight line. ηmax / ηlin was defined as λmax.
The strain rate can be measured in the range of 0.001 / sec to 10.0 / sec, and the strain hardening degree varies depending on the difference in strain rate.

(13) Q value (Mw / Mn):
The Q value of the linear propylene / ethylene block copolymer (B) and the polypropylene-based polymer (C) used in the present invention is a fraction 1 measured by gel permeation chromatography (GPC) in the above-described cross fractionator. It was calculated | required from the molecular weight distribution curve of the whole (B) created by synthetic-processing the molecular weight distribution curve of ~ 3. The method for calculating the weight average molecular weight (Mw) and the number average molecular weight (Mn) from this molecular weight distribution curve was according to a known method, and Mw / Mn was used as the Q value.
Further, the Q value of the polypropylene polymer (C) was measured under the following measurement conditions.
Apparatus: GPC 150C type manufactured by Waters Inc. Detector: 1A infrared spectrophotometer manufactured by MIRAN (measurement wavelength: 3.42 μm)
Column: 3 AD806M / S manufactured by Showa Denko Co., Ltd. The column was calibrated by measuring monodisperse polystyrene (0.5 mg / ml solution of each of A500, A2500, F1, F2, F4, F10, F20, F40, and F288) manufactured by Tosoh. And the logarithm of the elution volume and molecular weight was approximated by a quadratic equation. The molecular weight of the sample was converted to polypropylene using the viscosity formula of polystyrene and polypropylene. Here, the coefficients of the viscosity formula of polystyrene are α = 0.723 and log K = −3.767, and polypropylene has α = 0.707 and log K = −3.616.
Measurement temperature: 140 ° C
Concentration: 20 mg / 10 mL
Injection volume: 0.2ml
Solvent: Orthodichlorobenzene Flow rate: 1.0 ml / min Viscosity formula: log [η] = log K + α × log M

(14) Identification of component (c1) and component (c2) in the polypropylene-based polymer (C):
A technique for evaluating the crystallinity distribution of a propylene / ethylene random copolymer by temperature-elevated elution fractionation (TREF, hereinafter, also simply referred to as TREF) is well known to those skilled in the art. Detailed measurement methods are shown.
G. Glockner, J. et al. Appl. Polym. Sci. : Appl. Polym. Symp. 45, 1-24 (1990)
L. Wild, Adv. Polym. Sci. 98, 1-47 (1990)
J. et al. B. P. Soares, A .; E. Hamielec, Polymer; 36, 8, 1639-1654 (1995)
The component (c1) and the component (c2) in the component (C) used in the present invention are specified by TREF.
A specific method will be described using the figure showing the elution amount and elution amount integration by TREF in FIG. In the TREF elution curve (plot of elution amount versus temperature), components (c1) and (c2) show their elution peaks at T (A) and T (B), respectively, due to the difference in crystallinity, and the difference is sufficiently large. Separation is possible at an intermediate temperature T (C) (= {T (A) + T (B)} / 2).

In addition, the lower limit of the TREF measurement temperature is −15 ° C. in the apparatus used for this measurement, but in the case where the crystallinity of the component (c2) is very low or an amorphous component, There is a case where no peak is shown in the range (in this case, the concentration of the component (c2) dissolved in the solvent is detected at the lower limit of the measurement temperature (ie, −15 ° C.)).
At this time, T (B) is considered to exist below the measurement temperature lower limit, but the value cannot be measured. In such a case, T (B) is the measurement temperature lower limit − It is defined as 15 ° C.
Here, if the integrated amount of the components eluted up to T (C) is defined as W (B) wt%, and the integrated amount of the component eluted at T (C) or higher is defined as W (A) wt%, W (B) Almost corresponds to the amount of the component (c2) having low crystallinity or amorphousness, and the integrated amount W (A) of the component eluted at T (C) or higher is the component (c1) having relatively high crystallinity. Almost corresponds to the amount of. The elution amount curve obtained by TREF and the above-described methods for calculating the various temperatures and amounts obtained therefrom are performed as illustrated in FIG.

(A) TREF Measuring Method In the present invention, TREF is specifically measured as follows. A sample is dissolved in orthodichlorobenzene (ODCB (containing 0.5 mg / mL BHT)) at 140 ° C. to obtain a solution. This is introduced into a 140 ° C. TREF column, cooled to 100 ° C. at a rate of 8 ° C./min, subsequently cooled to −15 ° C. at a rate of 4 ° C./min, and held for 60 minutes. Then, ODCB (containing 0.5 mg / mL BHT) as a solvent is allowed to flow through the column at a flow rate of 1 mL / min, and components dissolved in ODCB at −15 ° C. are eluted for 10 minutes in the TREF column. The column is linearly heated to 140 ° C. at a rate of 100 ° C./hour to obtain an elution curve.
The outline of the apparatus is as follows.
TREF column: 4.3 mmφ × 150 mm stainless steel column Column filler: 100 μm Surface inactive glass beads Heating method: Aluminum heat block Cooling method: Peltier element (Peltier element is cooled by water)
Temperature distribution: ± 0.5 ° C
Temperature controller: Chino Corporation Digital Program Controller KP1000 (Valve Oven)
Heating method: Air bath oven Measurement temperature: 140 ° C
Temperature distribution: ± 1 ° C
Valve: 6-way valve 4-way valve Injection method: Loop injection method Detector: Fixed wavelength infrared detector MIRAN 1A manufactured by FOXBORO
Detection wavelength: 3.42 μm
High-temperature flow cell: Micro flow cell for LC-IR Optical path length 1.5 mm Window shape 2φ × 4 mm long round Synthetic sapphire window Sample concentration: 5 mg / mL
Sample injection volume: 0.1 mL

(B) Determination of ethylene content in component (c1) and component (c2) (i) Separation of component (c1) and component (c2):
Based on the T (C) obtained by the previous TREF measurement, a soluble component (c2) in T (C) and an insoluble component (c1) in T (C) by a temperature rising column fractionation method using a preparative fractionator And determine the ethylene content of each component by NMR.
As the temperature rising column fractionation method, a detailed measurement method is shown in the following document, for example.
Macromolecules; 21, 314-319 (1988).
Specifically, the following method is used in the present invention.

(Ii) Sorting conditions:
A cylindrical column having a diameter of 50 mm and a height of 500 mm is packed with a glass bead carrier (80 to 100 mesh) and maintained at 140 ° C.
Next, 200 mL of a sample ODCB solution (10 mg / mL) dissolved at 140 ° C. is introduced into the column. Thereafter, the temperature of the column is cooled to 0 ° C. at a rate of temperature decrease of 10 ° C./hour. After holding at 0 ° C. for 1 hour, the column temperature is heated to T (C) at a heating rate of 10 ° C./hour and held for 1 hour. Note that the temperature control accuracy of the column through a series of operations is ± 1 ° C.
Next, while maintaining the column temperature at T (C), 800 mL of ODCB of T (C) is flowed at a flow rate of 20 mL / min to elute and recover components soluble in T (C) existing in the column. To do.
Next, the column temperature is increased to 140 ° C. at a rate of temperature increase of 10 ° C./min, held at 140 ° C. for 1 hour, and then 800 mL of a 140 ° C. solvent (ODCB) is flowed at a flow rate of 20 mL / min to obtain T (C). Insoluble components are eluted and recovered.
The solution containing the polymer obtained by fractionation is concentrated to 20 mL using an evaporator and then precipitated in 5 times the amount of methanol. The precipitated polymer is recovered by filtration and then dried overnight in a vacuum dryer.

(Iii) Measurement of ethylene content by 13C-NMR:
The ethylene content of each of the component (c1) and component (c2) obtained by the fractionation is determined by analyzing a 13C-NMR spectrum measured according to the following conditions by the proton complete decoupling method.
Model: GSX-400 (carbon nuclear resonance frequency 400 MHz) manufactured by JEOL Ltd.
Solvent: ODCB / heavy benzene = 4/1 (volume ratio)
Concentration: 100 mg / mL
Temperature: 130 ° C
Pulse angle: 90 °
Pulse interval: 15 seconds Integration count: 5,000 times or more The attribution of the spectrum may be performed with reference to the following documents, for example.
Macromolecules; 17, 1950 (1984).
The attribution of spectra measured under the above conditions is as shown in the table below. In the table, symbols such as Sαα follow the notation in the following literature, P represents methyl carbon, S represents methylene carbon, and T represents methine carbon.
Carman, Macromolecules; 10,536 (1977)

Hereinafter, when “P” is a propylene unit in a copolymer chain and “E” is an ethylene unit, six types of triads of PPP, PPE, EPE, PEP, PEE, and EEE may exist in the chain. As described in Macromolecules, 15 1150 (1982), the concentration of these triads and the peak intensity of the spectrum are linked by the following relational expressions <1> to <6>.
[PPP] = k × I (Tββ) <1>
[PPE] = k × I (Tβδ) <2>
[EPE] = k × I (Tδδ) <3>
[PEP] = k × I (Sββ) <4>
[PEE] = k × I (Sβδ) <5>
[EEE] = k × [I (Sδδ) / 2 + I (Sγδ) / 4} <6>
Here, [] indicates the fraction of triads, for example, [PPP] is the fraction of PPP triads in all triads.
Therefore, [PPP] + [PPE] + [EPE] + [PEP] + [PEE] + [EEE] = 1 <7>.
Further, k is a constant, I indicates the spectral intensity, and for example, I (Tββ) means the intensity of the 28.7 ppm peak attributed to Tββ.

By using the relational expressions <1> to <7> above, the fraction of each triad is obtained, and the ethylene content is obtained from the following expression.
Ethylene content (mol%) = ([PEP] + [PEE] + [EEE]) × 100
Note that the propylene random copolymer according to the present invention contains a small amount of propylene heterogeneous bonds (2,1-bonds and / or 1,3-bonds), thereby producing the following minute peaks.

In order to obtain an accurate ethylene content, it is necessary to include these peaks derived from heterogeneous bonds in the calculation, but it is difficult to completely separate and identify the peaks derived from heterogeneous bonds. Since the amount is small, the ethylene content in the present invention uses the relational expressions <1> to <7>, as in the analysis of the copolymer produced with a Ziegler-Natta catalyst that does not substantially contain a heterogeneous bond. To ask.
Conversion from mol% to wt% of ethylene content is performed using the following formula.
Ethylene content (% by weight) = (28 × X / 100) / {28 × X / 100 + 42 × (1−X / 100)} × 100
Here, X is the ethylene content in mol%. The ethylene content [E] W of the entire propylene / ethylene block copolymer is calculated from the ethylene contents [E] A, [E] B and TREF of the component (C1) and the component (C2), respectively, measured from the above. From the weight ratios W (A) and W (B)% by weight of the respective components to be calculated, the following formula is used.
[E] W = {[E] A × W (A) + [E] B × W (B)} / 100 (% by weight)

(15) Melting peak temperature (Tm) of component (C):
Using a DSC6200 model manufactured by Seiko Instruments Inc., take 5.0 mg of sample, hold it at 200 ° C for 5 minutes, crystallize it to 40 ° C at a cooling rate of 10 ° C / min, and further melt at a heating rate of 10 ° C / min. And measure.

(16) Peak of tan δ curve of component (C):
Measured by solid viscoelasticity measurement. The sample used is a 10 mm width × 18 mm length × 2 mm thickness strip cut out from a 2 mm thick sheet formed by injection molding under the following conditions.
The apparatus uses ARES manufactured by Rheometric Scientific.
Standard number: JIS-7152 (ISO294-1)
Frequency: 1Hz
Measurement temperature: From -60 ° C. until the sample melts.
Strain: Range of 0.1-0.5% Molding machine: TU-15 injection molding machine manufactured by Toyo Machine Metal Co., Ltd. Molding machine set temperature: 80, 80, 160, 200, 200, 200 ° C. from below the hopper
Mold temperature: 40 ℃
Injection speed: 200 mm / sec (speed in the mold cavity)
Injection pressure: 800kgf / cm2
Holding pressure: 800 kgf / cm2
Holding time: 40 seconds
Mold shape: Flat plate (2mm thickness, 30mm width, 90mm length)

(17) Content of propylene-ethylene copolymer part and ethylene content of component (C-3):
・ Analyzer to be used (i) Cross sorter CFC T-100 manufactured by Dia Instruments (hereinafter abbreviated as CFC)
(Ii) Fourier transform infrared absorption spectrum analysis FT-IR, Perkin Elmer 1760X
A 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 the CFC to the FT-IR is 1 m long, and the temperature is maintained at 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 the temperature is maintained at 140 ° C. throughout the measurement.
(Iii) Gel permeation chromatography (GPC)
The GPC column in the latter part of the CFC is used by connecting three AD806MS manufactured by Showa Denko KK in series.

(18) Weight average molecular weight (Mw-H) of the propylene homopolymer portion of component (C-3) and weight average molecular weight (Mw-W) of the entire component (C-3):
The (Mw-H) and the (Mw-W) of the component (C-3) are determined by the following method. That is, in the preceding analysis, the component that elutes in orthodichlorobenzene (ODCB) at 100 to 140 ° C. of component (e) is defined as a propylene homopolymer portion. That is, the temperature is raised using orthodichlorobenzene as a solvent, the components eluted at 100 ° C. to 140 ° C. or less are extracted, and the weight average molecular weight is obtained by gel permeation chromatography (GPC), and (Mw-H) And In addition, the weight average molecular weight of all components eluted with orthodichlorobenzene up to 140 ° C. is determined by GPC, and is defined as the weight average molecular weight (Mw−W) of the entire component (C-3).

2. Material (1) (A): Crystalline polypropylene (A-1): Nippon Polypro Novatec EC9EV (MFR 0.5 g / 10 min, melting point 161 ° C. ethylene / propylene block copolymer)
(A-2): Nippon Polypro Novatec BC4 (MFR 6.5 g / 10 min, melting point 163 ° C. ethylene / propylene block copolymer)
Table 3 summarizes the crystalline polypropylene (A) used.

(2) (B): Linear propylene / ethylene block copolymer (B-1): A product having the following physical properties was selected from those commercially available as Novatec series manufactured by Nippon Polypro Co., Ltd. and used. This is polymerized with a Ziegler-based catalyst, the linear propylene polymer component (b1) has an MFR (230 ° C., 2.16 kg load) of 620 g / 10 min, a linear ethylene / propylene random copolymer component (b2 ) Of the entire linear propylene / ethylene block copolymer (B) is 9.4% by weight, the intrinsic viscosity [η] _{copolymer of the} component (b2) is 9.3 dl / g, (B) the MFR of the whole (B) 230 ° C., 2.16 kg load) is 150 g / 10 min, (B) the overall die swell ratio is 1.7, and shows strain hardening in 180 ° C. extensional viscosity measurement (strain hardening “Yes”). The strain hardening degree (λmax) is 7.47, and (B) the overall Q value is 12.3, the ethylene content of the component (b2) is 25% by weight (measured by a cross fractionation method), and the component (b2) Mw is 1.93 million (black) It was linear propylene-ethylene block copolymer fractionation GPC measurement).

(B-2): From what was marketed as Novatec series by Nippon Polypro Co., Ltd., those having the following physical properties were selected and used. This is polymerized with a Ziegler catalyst, the linear propylene polymer component (b1) has an MFR (230 ° C., 2.16 kg load) of 150 g / 10 min, a linear ethylene / propylene random copolymer component (b2 ) Of the linear propylene / ethylene block copolymer (B) is 8.5% by weight, the intrinsic viscosity [η] _{copolymer of the} component (b2) is 7.9 dl / g, (B) the MFR of the whole (B) 230 ° C., 2.16 kg load) is 65 g / 10 min, (B) the overall die swell ratio is 1.6, and shows strain hardening in 180 ° C. extensional viscosity measurement (strain hardening “Yes”). The strain hardening degree (λmax) is 3.81, and (B) the overall Q value is 8.5, the ethylene content of the component (b2) is 43% by weight (measured by a cross fractionation method), and the component (b2) Mw 1.7 million (for the cross Linear propylene-ethylene block copolymer of GPC measurement) (antioxidant-neutralizing agent were added already pellets).

(B-3): A product having the following physical properties was selected from those commercially available as Novatec series manufactured by Nippon Polypro Co., Ltd. and used. This is polymerized with a Ziegler catalyst, the linear propylene polymer component (b1) has an MFR (230 ° C., 2.16 kg load) of 270 g / 10 min, a linear ethylene / propylene random copolymer component (b2). ) Of the linear propylene / ethylene block copolymer (B) is 20.3% by weight, the intrinsic viscosity [η] _{copolymer of the} component (b2) is 2.7 dl / g, (B) the MFR of the whole (B) 230 ° C., 2.16 kg load) is 103 g / 10 min, (B) the overall die swell ratio is 1.0, and shows strain hardening in 180 ° C. extensional viscosity measurement (strain hardening “Yes”). The strain hardening degree (λmax) is 1.16, and the (B) overall Q value is 5.6, the ethylene content of the component (b2) is 39% by weight (measured by a cross fractionation method), and the component (b2) Mw 350,000 (cross Another GPC measurement) of the linear propylene-ethylene block copolymer (antioxidant-neutralizing agent were added already pellets).

(B-4): A commercially available product as PF814 from Basel was used. This shows that (B) the overall MFR (230 ° C., 2.16 kg load) is 2.5 g / 10 min, and shows strain hardening in the 180 ° C. extensional viscosity measurement (strain hardening “Yes”). The propylene-based polymer having (λmax) of 34 was a polypropylene having a long chain branch that is commercially available as a high melt tension polypropylene.
The linear propylene / ethylene block copolymer (B) used is summarized in Table 4.

(3) (C): Polypropylene polymer (hereinafter, both are pellets to which an antioxidant and a neutralizing agent have been added.)
C-1: The grades of the following composition and physical properties were used from Wellnex series manufactured by Nippon Polypro Co., Ltd.
The material is polymerized with a metallocene-based catalyst, 56.0% by weight of propylene / ethylene random copolymer component (c1) having an ethylene content of 1.8% by weight in the first step, and from component (c1) in the second step. Is obtained by sequential polymerization of 44.0% by weight of a propylene / ethylene random copolymer component (c2) containing 9.2% by weight of a large amount of ethylene, and the melting peak temperature measured by the DSC method ( Tm) is 133.0 ° C., and in the temperature-loss tangent curve obtained by solid viscoelasticity measurement, the tan δ curve has a single peak at −8 ° C., and the MFR (230 ° C., 2.. 16kg load) is 6g / 10min.
C-2: The grades of the following composition and physical properties were used from the Wellnex series manufactured by Nippon Polypro Co., Ltd.
The material is polymerized with a metallocene-based catalyst, 56.2% by weight of propylene / ethylene random copolymer component (c1) having an ethylene content of 2.0% by weight in the first step, and from component (c1) in the second step. Obtained by sequential polymerization of 43.8% by weight of a propylene / ethylene random copolymer component (c2) containing 9.2% by weight of a large amount of ethylene, and the melting peak temperature measured by the DSC method ( In the temperature-loss tangent curve obtained by solid viscoelasticity measurement with a Tm) of 135.3 ° C, the tan δ curve has a single peak at -8 ° C, and the MFR (230 ° C, 2.2. 16kg load) is 18g / 10min.
C-3: NIPPON manufactured by Nippon Polypro Co., Ltd., 0.045 parts by weight of 1,3-bis- (t-butylperoxyisopropyl) benzene as a molecular weight depressant was added to 100 parts by weight of the grade having the composition shown below. And kneaded and granulated (using a single screw extruder, kneading temperature 210 ° C.) (finished MFR (230 ° C., 2.16 kg load) = 7 g / 10 min).
The material used above is 1 g / 10 min of MFR (230 ° C., 2.16 kg load) of the entire copolymer resin polymerized with a Ziegler-based catalyst, and contains 47% by weight of a propylene homopolymer portion. A composition containing 53% by weight of an ethylene-propylene copolymer portion, wherein the ethylene content of the ethylene-propylene copolymer portion is 36% by weight.
Table 5 summarizes the polypropylene polymer (C) used.

(4) (D): Thermoplastic resin (D-1): Novatec HB332R manufactured by Nippon Polyethylene (MFR 0.5 g / 10 min, high density polyethylene with a density of 0.952 g / cm ³ ).
Table 6 summarizes the thermoplastic resin (D) used.

(5) (E): Foaming agent (E-1): Chemical foaming agent master batch (Polyslen EE25C manufactured by Eiwa Kasei Co., Ltd., foaming agent concentration 20%, amount of generated gas 75 to 90 ml / 2.5 g (at 220 ° C. constant temperature × 20 min) ... Sodium bicarbonate / citric acid base, low density polyethylene base.

3. Examples and Comparative Examples [Example 1]
Crystalline polypropylene (A) (A-1) 50% by weight, linear propylene / ethylene block copolymer (B) (B-1) 40% by weight, polypropylene polymer ( C) 100% by weight of a mixture of 10% by weight of (C-1) as a stabilizer, 0.1 weight of phenolic antioxidant (manufactured by Ciba Specialty Chemicals: Irganox 1010) And 0.05 parts by weight of a phosphorus-based antioxidant (Ciba Specialty Chemicals: Irgaphos 168), mixed with a mixer, melt-kneaded with a twin-screw extruder, and extruded at a extrusion temperature of 200 ° C. It was cut by cooling and granulated to obtain a pellet-shaped polypropylene resin composition.
Table 7 shows the melt flow rate (MFR), melt tension (MT) at 190 ° C, and melt stretchability (MEL) evaluation results at 190 ° C of the obtained polypropylene resin composition.
Further, 3 parts by weight of a foaming agent (E-1) is added to 100 parts by weight of the obtained polypropylene resin composition, and foaming is performed at a die slip temperature of 170 ° C. by a direct blow molding machine having a screw diameter of 50 mmΦ. The performance of the parison was evaluated. Table 7 shows the evaluation results. In the present invention, the target of the expansion ratio is set to “1.8” times or more.

[Example 2]
Evaluation was performed in the same manner as in Example 1 except that the polypropylene polymer (C) was changed to (C-2). Table 7 shows the evaluation results.

[Example 3]
Evaluation was conducted in the same manner as in Example 1 except that the linear propylene / ethylene block copolymer (B) was changed to (B-2). Table 7 shows the evaluation results.

[Example 4]
65% by weight of crystalline polypropylene (A) (A-1), 30% by weight of linear propylene / ethylene block copolymer (B) (B-1), polypropylene polymer ( Evaluation was performed in the same manner as in Example 1 except that 100 parts by weight of a mixture in which 5% by weight of (C-1) as C) was blended was used. Table 7 shows the evaluation results.

[Comparative Example 1]
Evaluation was performed in the same manner as in Example 1 except that the polypropylene polymer (C) was not blended and the thermoplastic resin (D) (D-1) was used. Table 7 shows the evaluation results.

[Comparative Example 2]
30% by weight of (A-1) which is crystalline polypropylene (A), 30% by weight of (B-1) which is a linear propylene / ethylene block copolymer (B), and a polypropylene polymer ( Evaluation was performed in the same manner as in Example 1 except that 100 parts by weight of a mixture obtained by blending 40% by weight of (C-1) which was C) was used. Table 7 shows the evaluation results.

[Comparative Example 3]
Evaluation was conducted in the same manner as in Example 1 except that the linear propylene / ethylene block copolymer (B) was changed to (B-4). Table 7 shows the evaluation results.

[Comparative Example 4]
Evaluation was conducted in the same manner as in Example 1 except that the linear propylene / ethylene block copolymer (B) was changed to (B-3). Table 7 shows the evaluation results.

[Comparative Example 5]
Evaluation was performed in the same manner as in Example 1 except that the crystalline polypropylene (A) was changed to (A-2). Table 7 shows the evaluation results.

[Comparative Example 6]
The same evaluation as in Example 1 was performed except that the polypropylene polymer (C) was changed to (C-3). Table 7 shows the evaluation results.

4). Evaluation As is clear from the results shown in Table 7, when the polypropylene resin composition having the composition shown in Examples 1 to 4 that satisfies the respective requirements in the essential constituent elements of the present invention is made into a blow-molded foam, All have excellent surface appearance, good melt processing such as resistance to drawdown, improved thermal stability and excellent recyclability, all of which have been significantly improved and have suitable performance for foam blow molded products. Yes.

On the other hand, when the polypropylene polymer (C) was not added, the surface appearance and the expansion ratio were reduced (Comparative Example 1). When more polypropylene polymer (C) was blended than specified in the present invention, the MFR became too high and the expansion ratio was lowered (Comparative Example 2). When the linear ethylene / propylene random copolymer (B) does not satisfy the characteristics (i) to (vi), the thermal stability is poor (Comparative Examples 3 and 4). When crystalline polypropylene (A) did not satisfy the provisions of the present invention, the MFR was too high and the drawdown resistance was lowered (Comparative Example 5). When the polypropylene polymer (C) did not satisfy the provisions of the present invention, the expansion ratio decreased (Comparative Example 6).
From the results of the examples and comparative examples described above, the rationality and significance of the configuration of the present invention and the requirements are demonstrated, and the superiority of the present invention over the prior art is also clarified.

  The polypropylene resin composition of the present invention is excellent in surface appearance during foam blow molding, has good foam blow moldability, can be significantly reduced in weight, has excellent recyclability, and has physical properties such as rigidity and heat insulation. Also shows a remarkable effect of improving. In addition, since cross-linking modification is not performed, recyclability is excellent and environmental adaptability is also good. Therefore, it is suitable for blow molding parts for automobiles such as ducts, protective coating materials for pipes, resonators, deck boards, and for heat insulation panels, household goods, tanks, etc. And its industrial applicability is enormous.

Claims (5)

A polypropylene resin composition comprising the following (A) to (C) and having a melt flow rate (230 ° C., 2.16 kg load) of 1 to 15 g / 10 min.
(A): crystalline polypropylene having a melt flow rate (230 ° C., 2.16 kg load) of 0.05 to 2 g / 10 min; 15 to 88% by weight
(B): a linear propylene polymer comprising the linear propylene polymer component (b1) and the linear ethylene / propylene random copolymer component (b2) and having the following characteristics (i) to (vi): Ethylene block copolymer; 10-60% by weight
(C): Polypropylene polymer (C): Propylene / ethylene block copolymer having the requirements defined in the following (C-a) to (C-e).
(C-A): 30 to 95% by weight of propylene homopolymer or propylene / ethylene random copolymer component (c1) having an ethylene content of 7% by weight or less in the first step using a metallocene catalyst, the second step The propylene / ethylene random copolymer component (c2) containing 3 to 20 wt% more ethylene than the component (c1) is obtained by sequential polymerization of 5 to 70 wt%.
(C-A): Melting peak temperature (Tm) measured by DSC method is 110 to 150 ° C.
(C-C): In the temperature-loss tangent curve obtained by solid viscoelasticity measurement, the tan δ curve has a single peak at 0 ° C. or lower.
(C-D): Melt flow rate (MFR: 230 ° C., 2.16 kg load) is 3 to 40 g / 10 min. 2-25% by weight
Characteristic (i): Melt flow rate (230 ° C., 2.16 kg load) of the linear propylene polymer component (b1) is 120 g / 10 min or more.
Characteristic (ii): The ratio of the linear ethylene / propylene random copolymer component (b2) to the entire linear propylene / ethylene block copolymer (B) is 2 to 50% by weight.
Characteristics (iii): The intrinsic viscosity _{[eta] copoly} of linear ethylene-propylene random copolymer component (b2) is 5.3~10.0dl / g.
Characteristic (iv): Melt flow rate (230 ° C., 2.16 kg load) is 45 g / 10 min or more.
Characteristic (v): The die swell ratio is 1.2 to 2.5.
Characteristic (vi): Shows strain hardening in 180 ° C. extensional viscosity measurement.   The linear propylene / ethylene block copolymer (B) is characterized in that the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Q value: Mw / Mn) is 7 to 13. The polypropylene resin composition according to claim 1.   The linear ethylene / propylene random copolymer component (b2) has an ethylene content of 15 to 80% by weight based on the total amount of the linear ethylene / propylene random copolymer component (b2). The polypropylene resin composition according to claim 1 or 2. Further, a hydrogenated product (d1) of a styrene / conjugated diene block copolymer, an ethylene / α-olefin copolymer rubber (d2) having a Mooney viscosity [ML1 + 4 (121 ° C.)] of 5 or more, and a melt flow rate (230 At least one thermoplastic resin (D) selected from the group consisting of an ethylene polymer resin (d3) having a temperature of 2.16 kg at 0.32 g / 10 min and a density of 0.920 g / cm ³ or more. The polypropylene resin composition according to any one of claims 1 to 3, wherein the total amount of (A) to (D) is 20% by weight or less based on 100% by weight.   A foamed blow molded article comprising the polypropylene resin composition according to any one of claims 1 to 4 and a foaming agent (E).

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