JP2004143451A - Polyproylene based resin composition, polyproylene based resin foaming particle and in-mold molded product using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polyproplylene based resin foaming particles imparting an in-mold molded article excellent in surface external appearance and mechanical properties together with reduced permanent distortion, to provide the in-mold molded article and to provide the optimum polypropylene based resin composition as the base resin of the polypropylene based resin foaming particles. <P>SOLUTION: The polypropylene based resin composition comprises [A] 5-95 wt.% of a polypropylene based resin satisfying following requirements (a) and (b) and [B] 95-5 wt.% of a polypropylene based resin satisfying following requirement (a). The requirement (a):the polypropylene based polymer comprises 100-85 mol.% of structural unit obtained from propylene and 0-15 mol.% of structural unit obtained from ethylene or an α-olefin, the requirement (b) the polymer has 0.5-2.0% of position irregular units based on 2, 1-insertion, and 0.005-0.4% of position irregular units based on 1, 3-insertion. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an expanded polypropylene resin particle capable of obtaining an in-mold molded article having excellent surface appearance and mechanical properties at a low molding temperature, a molded article in the mold, and a base material of the expanded polypropylene resin particle. The present invention relates to a polypropylene resin composition most suitable as a resin.

In-mold foamed articles obtained from polypropylene-based resin foamed particles have excellent chemical resistance, impact resistance, compression strain recovery, etc. as compared with molded articles made of polystyrene-based resin foamed particles, and are therefore used in automobiles, etc. Is suitably used as a bumper core material and various packaging materials.

The expanded polypropylene resin particles contain a polypropylene resin composition as a base resin and a foaming agent.
As the polypropylene resin composition, a propylene-α-olefin random copolymer obtained by copolymerizing propylene with an α-olefin such as ethylene or 1-butene is mainly used from the viewpoint of foaming suitability. . However, since these are copolymers, the mechanical properties of the polymer itself are low.
Therefore, in order to improve the mechanical properties of the polypropylene resin composition, a method of lowering the comonomer content in the copolymer, or a method of mixing linear polyethylene with a propylene-α-olefin random copolymer ( Patent Document 1) has been proposed. However, even with such a method, there is a limit in improving the mechanical properties of the molded body.

On the other hand, polypropylene is a synthetic resin that originally has excellent mechanical properties such as rigidity. Therefore, if foamed particles can be obtained from a homopolymer of polypropylene, a foamed molded article having sufficiently high rigidity can be obtained. However, when a molded article is to be obtained from foamed particles composed of a polypropylene homopolymer, the foaming temperature range and the molding range are very narrow, and it is extremely difficult to precisely control these conditions. For this reason, the obtained molded article has a problem that defects such as defective fusion between particles occur and appearance of the molded article surface is deteriorated. Therefore, in actual industrial production, a foamed molded article could not be obtained from a polypropylene homopolymer.

However, in recent years, a method has been proposed in which polypropylene having a syndiotactic structure obtained using a so-called metallocene catalyst is used as a base resin of a foam (see Patent Document 2). This proposal has made it possible to produce foams made of propylene homopolymer.
However, polypropylene having a syndiotactic structure has a problem that the melting point is lower and mechanical properties are inferior to polypropylene having an isotactic structure.

Patent Document 3 described below proposes expanded polypropylene resin particles using an isotactic polypropylene resin polymerized using a metallocene polymerization catalyst as a base resin.
In this case, there is a feature that the cell diameter of the expanded particles is relatively uniform. However, there is a problem that a molded article obtained by using such expanded particles has a large compression set, and further improvement is desired. Was.

JP-A-57-90027 (Claims) JP-A-4-224832 (Claims) JP-A-6-240041 (Claim 1)

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and it is an object of the present invention to provide a foamed polypropylene resin particle having excellent surface appearance and mechanical properties at a low molding temperature and capable of obtaining an in-mold molded product having a small compression set. It is an object of the present invention to provide a polypropylene resin composition which is most suitable as a base resin for foamed polypropylene resin particles, and a molded article thereof.

In the first invention, the following propylene-based polymer [A] is 5 to 95% by weight, and the following propylene-based polymer [B] is 95 to 5% by weight (provided that the propylene-based polymer (A) and the propylene-based (The total amount with the coalescing [B] is 100% by weight).
Propylene-based polymer [A]: A propylene-based polymer having the following requirements (a) and (b).
(A) 100 to 85 mol% of structural units obtained from propylene, and 0 to 15 mol% of structural units obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms (provided that propylene is obtained from propylene) The total amount of the structural units and the structural units obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms is 100 mol%).
(B) the ratio of the position irregular units based on the 2,1-insertion of the propylene monomer units in the total propylene insertion is 0.5 to 2.0%, as measured by 13C-NMR, and the propylene monomer The ratio of the position irregular units based on the 1,3-insertion of the unit is 0.005 to 0.4%.
Propylene-based polymer [B]: A propylene-based polymer having only the requirement (a) among the requirements (a) and (b).

The polypropylene resin composition of the present invention comprises 5 to 95% by weight of a propylene polymer [A] having the above requirements (a) and (b), and the requirement (a) of the above (a) and (b). 95% by weight of a propylene-based polymer [B] having only Therefore, the polypropylene resin composition is excellent in mechanical properties and workability.

Further, when the polypropylene resin composition of the present invention is used as a base resin to produce expanded particles, it is possible to obtain expanded particles having excellent mechanical properties and excellent expandability during molding (secondary expandability). it can. Therefore, when the expanded particles are molded, an in-mold molded product having excellent surface appearance and mechanical properties and small compression set can be obtained. That is, the polypropylene-based resin composition of the present invention can be used as an optimal base resin for expanded polypropylene-based resin particles.

Here, the base resin means a basic resin component constituting the expanded particles. The foamed particles are composed of the base resin and other polymer components to be added as required, or additives such as a foaming agent, a catalyst neutralizing agent, a lubricant, a crystal nucleating agent, and other additives. However, it is desirable that other polymer components and additives be as small as possible within a range not to impair the object of the present invention.
That is, when the total amount of the propylene-based polymer [A] and the propylene-based polymer [B] is 100 parts by weight, the addition amount of the other polymer components is preferably 40 parts by weight or less. More preferably, the amount is 30 parts by weight or less, and even more preferably 15 parts by weight or less. Most preferably, the amount is 5 parts by weight or less.
When the total amount of the propylene-based polymer [A] and the propylene-based polymer [B] is 100 parts by weight, the additive amount of the above-mentioned additive (for the foaming agent, the one that eventually disappears, such as a foaming agent, Is excluded), but is preferably 40 parts by weight or less, depending on the purpose of use of the additive. More preferably, the amount is 30 parts by weight or less, and even more preferably 0 to 15 parts by weight.

２ A second invention resides in expanded polypropylene resin particles containing the polypropylene resin composition of the first invention as a base resin (claim 5).

In the present invention, since the polypropylene resin composition of the first invention is used as a base resin, expanded polypropylene resin particles having excellent mechanical properties and excellent foamability during molding can be obtained. . Further, by using the expanded polypropylene resin particles, it is possible to obtain an in-mold molded article having excellent mechanical properties such as compressive strength and tensile strength, and excellent surface appearance.

The third invention is a molded article in a mold having a density of 0.5 to 0.008 g / cm ³ , wherein the foamed polypropylene resin particles are molded in a molding die.
In addition, the foamed polypropylene-based resin particles are formed in the mold according to the second aspect of the present invention (claim 7).

The in-mold molded article of the present invention is formed by in-mold molding using the expanded polypropylene resin particles of the second invention, and has the above density.
Therefore, the in-mold molded article has excellent mechanical properties such as compressive strength and tensile strength, and also has excellent surface appearance such as smoothness and gloss.
In addition, the density of the in-mold molded body means an apparent overall density defined by JIS K7222 (1999).

In the first aspect of the invention, the polypropylene resin composition contains a propylene polymer [A] and a propylene polymer [B]. First, the propylene-based polymer [A] is a propylene-based polymer having the above requirements (a) and (b). Hereinafter, the propylene-based polymer [A] will be described.

First, the requirement (a) is that 100 to 85 mol% of the structural unit obtained from propylene and 0 to 15 mol% of the structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms are present. is there.
Here, the total amount of the structural units obtained from propylene and the structural units obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms is 100 mol%.
Therefore, the propylene-based polymer satisfying the requirement (a) may be a propylene homopolymer (100 mol%) or a copolymer of propylene with ethylene and / or an α-olefin having 4 to 20 carbon atoms. There are things that consist of

Specific examples of the comonomer ethylene and / or an α-olefin having 4 to 20 carbon atoms copolymerized with propylene include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4- Methyl-1-butene and the like can be mentioned.

Further, in the present invention, as the propylene-based polymer [A], other monomers which have been conventionally difficult to polymerize with a Ziegler / Natta catalyst are copolymerized with propylene as long as the object of the present invention is not impaired. Things can be used. In this case, the structural unit obtained from the other monomer is preferably 0.01 to 20 mol%, more preferably 0.05 to 10 mol% in the propylene-based polymer [A].
The polypropylene resin composition containing such a propylene polymer can be used as a base resin for producing expanded particles.

Such other monomers include, for example, cycloolefins such as cyclopentene, norbornene, 1,4,5,8-dimethano-1,2,3,4,4a, 8,8a, 5-octahydronaphthalene, Examples thereof include one or more non-conjugated dienes such as methyl-1,4-hexadiene and 7-methyl-1,6-octadiene, and aromatic unsaturated compounds such as styrene and divinylbenzene.

The propylene-based polymer [A] used in the present invention is the above-mentioned requirement (a), that is, a propylene-based (co) polymer resin containing 85 to 100 mol% of a structural unit obtained from propylene in the propylene-based polymer. It is necessary that a structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms (comonomer) is contained in a proportion of 0 to 15 mol%.

(4) When the proportion of the structural unit of the comonomer exceeds 15 mol%, mechanical properties such as bending strength and tensile strength of the polypropylene resin composition are significantly reduced. Even if foamed particles are produced using the above-mentioned polypropylene resin composition as a base resin, desired foamed particles cannot be obtained. Furthermore, even if the foamed particles are molded, a desired in-mold molded article excellent in mechanical strength and compression recovery cannot be obtained.

Next, as shown in the requirement (b), the propylene-based polymer [A] has a position based on the 2,1-insertion of the propylene monomer unit in the total propylene insertion as measured by 13C-NMR. The proportion of irregular units is 0.5 to 2.0%, and the proportion of positional irregular units based on 1,3-insertion of propylene monomer units is 0.005 to 0.4%.
This requirement (b) relates to the proportion of the positionally irregular units in the propylene-based polymer, and such irregular units have the effect of lowering the crystallinity of the propylene-based polymer and exhibit the effect of increasing foaming suitability. .

If the proportion of the irregular units based on the 2,1-insertion is less than 0.5%, the polypropylene-based resin composition of the present invention contains expanded polypropylene-based resin particles using the same as a base resin. When molding, there is a problem that the effect of reducing the compression set of the obtained molded article in the mold is inferior. On the other hand, if it exceeds 2.0%, the mechanical properties of the polypropylene-based resin composition as a base resin, such as bending strength and tensile strength, are reduced, so that the expanded particles and the in-mold molded product obtained therefrom are reduced. There is a problem that strength is reduced.

When the proportion of the irregular units based on the 1,3-insertion is less than 0.005%, the polypropylene-based resin composition of the present invention uses expanded polypropylene-based resin particles using the same as a base resin. When performing in-mold molding, there is a problem that the effect of reducing the compression set of the obtained in-mold molded product is poor. On the other hand, if it exceeds 0.4%, the mechanical properties of the polypropylene-based resin composition as the base resin, such as bending strength and tensile strength, are reduced, so that the strength of the foamed particles and the in-mold molded product obtained therefrom is reduced. Is low.

In the above requirement (b), the positional irregularity unit based on the 2,1-insertion and the positional irregularity unit based on the 1,3-insertion are both crystalline properties of the polypropylene resin containing these units in its structure. Has the effect of reducing More specifically, these regio-irregular units have a function of lowering the melting point and a function of lowering the crystallinity of the polypropylene resin.

These two effects show that when such a polypropylene resin is subjected to foaming, the foaming suitability is enhanced and the compression set of the foam obtained is reduced. The propylene-based polymer [A] having the above-mentioned positionally irregular units has excellent compatibility with the propylene-based polymer [B] described below, and therefore, when both are melt-kneaded, they mix very well. Such a resin composition, in addition to the above-mentioned features of the propylene-based polymer [A], has an effect of having good secondary foamability when processed into foamed particles and molded in a mold.

However, if the proportion of the positionally irregular units contained in the polypropylene resin is too high, the melting point and crystallinity of the base resin are highly reduced, so that such a resin is used as the propylene polymer [A]. If the foamed resin particles are used for foaming, there may be a problem that the bubble diameter in the obtained foamed resin particles becomes large. In such a case, the molded article obtained from the foamed resin particles may be used. There is a problem that the appearance of the is impaired. Further, as described above, there is a problem that the strength of the in-mold molded article obtained from such expanded particles is reduced.

Here, the fraction of the structural unit obtained from propylene in the propylene-based polymer, the fraction of the structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms, and the fraction of an isotactic triad described below are: This is a value measured using the 13C-NMR method.
The method of measuring the 13C-NMR spectrum is, for example, as follows.
That is, about 350 to 500 mg of a sample was placed in a sample tube for NMR having a diameter of 10 mmφ, and completely dissolved using about 2.0 ml of o-dichlorobenzene as a solvent and about 0.5 ml of deuterated benzene for rock. Thereafter, the measurement was performed at 130 ° C. under the condition of complete proton decoupling.

As the measurement conditions, a flip angle of 65 deg and a pulse interval of 5T1 or more (where T1 is the longest value among the spin lattice relaxation times of the methyl group) were selected. In the propylene-based polymer, the spin lattice relaxation time of the methylene group and the methine group is shorter than that of the methyl group. Therefore, under these measurement conditions, the recovery of the magnetization of all carbons is 99% or more.
In addition, the detection sensitivity of the position irregular unit in the 13C-NMR method is usually about 0.01%, but it can be increased by increasing the number of integrations.

The chemical shift in the above measurement was determined by setting the peak of the methyl group in the third unit of the five propylene units having 5 head-to-tail bonds and the same direction of methyl branching as 21.8 ppm. The chemical shifts of other carbon peaks were set.

Using this criterion, the peak based on the methyl group of the second unit in the 3 chains of propylene units represented by PPP [mm] in the following formula [Chemical Formula 1] falls within the range of 21.3 to 22.2 ppm, and The peak based on the methyl group of the second unit in the three chains of propylene units represented by [mr] is in the range of 20.5 to 21.3 ppm, and the second unit in the three chains of propylene units represented by PPP [rr] The peak based on the methyl group of the eye appears in the range of 19.7 to 20.5 ppm.

Here, PPP [mm], PPP [mr], and PPP [rr] are indicated as follows, respectively.

Further, in the present invention, the propylene-based polymer [A] has the following partial structures (Ι) and (ΙΙ) containing regiorandom units based on 2,1-insertion and 1,3-insertion of propylene. Content.

It is considered that such a partial structure is caused by positional irregularities that occur during the polymerization of a propylene polymer, for example, when a polymerization reaction is performed using a metallocene catalyst.
That is, the propylene monomer usually reacts in a manner in which the methylene side is bonded to the metal component in the catalyst, that is, a so-called “1,2-insertion”. , 3-insertion ". “2,1-insertion” is a reaction type in which the addition direction is opposite to “1,2-insertion”, and forms a structural unit represented by the above partial structure (Ι) in a polymer chain.

The term "1,3-insertion" means that the propylene monomer is incorporated into the polymer chain by C-1 and C-3, and as a result, a linear structural unit, that is, the above partial structure ( ΙΙ).

The propylene-based polymer [A] in which the proportion of each of the above-mentioned positionally irregular units falls within the range of the present invention can be obtained by selecting an appropriate catalyst. Specifically, for example, it can be obtained using a metallocene-based polymerization catalyst having a hydroazulenyl group as a ligand. Here, the metallocene-based polymerization catalyst is composed of a transition metal compound component having a metallocene structure and a promoter component. Although the proportion of each regio-irregular unit differs depending on the chemical structure of the metal complex component of the catalyst used for the polymerization, generally, the higher the polymerization temperature, the larger the tendency. In the present invention, the polymerization temperature is preferably from 0 to 80 ° C. in order to keep the proportion of each position irregular unit in the propylene-based polymer [A] within the above specific range.

The metal complex component can be used as it is as a catalyst component, but it can be used as a solid catalyst in which the above metal complex component is supported on an inorganic or organic fine-grained carrier that is a granular or fine solid. May be used.
When the metal complex component is supported on the fine particle carrier, the amount of the metal complex component supported is preferably 0.001 to 10 mmol, more preferably 0.001 to 5 mmol per 1 g of the carrier.

Among the above metallocene catalysts having a hydroazulenyl group as a ligand, catalysts using titanium, zirconium, and hafnium as metal atoms are preferable. Among them, complexes having zirconium are preferable because of high polymerization activity. .
Among the above metallocene catalysts, zirconium dichloride type complexes are preferably used, and among them, it is particularly preferable to use a crosslinked type complex.
Specifically, methylenebis {1,1 ′-(2-methyl-4-phenyldihydroazulenyl)} zirconium dichloride, methylenebis {1,1 ′-(2-ethyl-4-phenyldihydroazulenyl)} zirconium dichloride , Methylenebis {1,1 '-(4-phenyldihydroazulenyl)} zirconium dichloride, methylenebis {1,1'-(4-naphthyldihydroazulenyl)} zirconium dichloride, ethylenebis {1,1 '-(2- Methyl-4-phenyldihydroazulenyl) zirconium dichloride, ethylenebis {1,1 ′-(2-ethyl-4-phenyldihydroazulenyl)} zirconium dichloride, ethylenebis {1,1 ′-(4-phenyldihydro (Azulenyl) zirconium dichloride, ethylenebis 1,1, '-(4 Naphthyldihydroazulenyl) {zirconium dichloride, isopropylidenebis} 1,1 ′-(2-methyl-4-phenyldihydroazulenyl)} zirconium dichloride, isopropylidenebis {1,1 ′-(2-ethyl-4- Phenyldihydroazulenyl)｝ zirconium dichloride, isopropylidenebis ｛1,1 ′-(4-phenyldihydroazulenyl)｝ zirconium dichloride, isopropylidenebis ｛1,1 ′-(4-naphthyldihydroazulenyl)｝ zirconium dichloride , Dimethylsilylenebis {1,1 '-(2-methyl-4-phenyldihydroazulenyl)} zirconium dichloride, dimethylsilylenebis {1,1'-(2-ethyl-4-phenyldihydroazulenyl)} zirconium dichloride , Dimethylsilylene bis {1,1 ′-(4-phenyldihydroazulenyl)} zirconium dichloride, dimethylsilylenebis {1,1 ′-(4-naphthyldihydroazulenyl)} zirconium dichloride, diphenylsilylenebis {1,1 ′-(2 -Methyl-4-phenyldihydroazulenyl) {zirconium dichloride, diphenylsilylenebis} 1,1 ′-(2-ethyl-4-phenyldihydroazulenyl)} zirconium dichloride, diphenylsilylenebis {1,1 ′-(4 -Phenyldihydroazulenyl) zirconium dichloride, diphenylsilylene bis {1,1 '-(4-naphthyldihydroazulenyl)} zirconium dichloride, and the like.
Among them, dimethylsilylenebis {1,1 ′-(2-methyl-4-phenyldihydroazulenyl)} zirconium dichloride and dimethylsilylenebis {1,1 ′-(2-ethyl-4-phenyldihydroazulene) are particularly preferable. (Nyl)｝ It is preferable to use zirconium dichloride. In this case, the proportion of each of the above-mentioned positional irregular units can be easily controlled within the range of the present invention, and the requirement (d) described later is satisfied (the isotactic triad fraction is 97%). The above) propylene polymer can be easily obtained.

Examples of the co-catalyst component include aluminoxanes such as methylaluminoxane, isobutylaluminoxane and methylisobutylaluminoxane; Lewis acids such as triphenylborane, tris (pentafluorophenyl) borane and magnesium chloride; and dimethylaniliniumtetrakis (pentafluorophenyl). And ionic compounds such as borate. It is also possible to use these cocatalyst components in combination with other organoaluminum compounds, for example, trialkylaluminums such as trimethylaluminum, triethylaluminum, and triisobutylaluminum.

Ｍｍ The mm fraction in the entire polymer chain of the propylene-based polymer according to the present invention is represented by the following [Equation 1]. By the way, in the partial structure (ΙΙ), as a result of 1,3-insertion, one methyl group derived from a propylene monomer has disappeared.

In this formula, ΣΙCH ₃ indicates the area of all methyl groups (all peaks at 19 to 22 ppm of chemical shift). A <1>, A <2>, A <3>, A <4>, A <5>, A <6>, A <7>, A <8>, and A <9> are The peak areas at 42.3 ppm, 35.9 ppm, 38.6 ppm, 30.6 ppm, 36.0 ppm, 31.5 ppm, 31.0 ppm, 37.2 ppm, and 27.4 ppm, and the partial structures (Ι) and (ΙΙ) ) Indicates the abundance ratio of carbon.
Further, the ratio of 2,1-inserted propylene and the ratio of 1,3-inserted propylene relative to the total propylene insertion were calculated by the following equations.

Next, the propylene polymer [A] is the melting point of the polymer Tm [° C.], also the water vapor permeability in the case of forming the polymer into a film and ^{Y [g / m 2 / 24hr} ] In this case, it is preferable that Tm and Y satisfy the following relational expression (1).
(−0.20) Tm + 35 ≦ Y ≦ (−0.33) Tm + 60 Equation (1)

The above water vapor permeability can be measured according to JIS K7129 (1992) “Test Method for Water Vapor Permeability of Plastic Films and Sheets”. In this measurement, an infrared sensor method is employed as a test method, and a test temperature of 40 ± 0.5 ° C. and a relative humidity (90 ± 2)% RH are employed as test conditions.

The propylene-based polymer [A] in the range of the above formula (1) shows a moderate water vapor permeability. Moderate water vapor permeability facilitates the penetration of saturated steam used for molding into the foamed particles during in-mold molding, thereby increasing the secondary foamability of the foamed particles and eliminating voids between the foamed particles. Alternatively, the production of a small number of in-mold molded articles becomes easy.
In addition, as a method for producing expanded polypropylene resin particles, a method is generally used in which resin particles are dispersed in water and impregnated with a foaming agent, and then released from high temperature and high pressure to low pressure to form expanded particles. In this case, the appropriate water vapor permeability facilitates penetration of water and a foaming agent into the resin particles. As a result, the dispersion of the water and the foaming agent in the resin particles becomes uniform, the cell diameter of the foamed particles obtained becomes uniform, and the expansion ratio can be improved.
The water vapor permeability (Y) is expressed in relation to the melting point (Tm) of the propylene-based polymer because the foaming temperature during the production of foamed particles and the saturated steam temperature during in-mold molding are generally This is based on the fact that the higher the melting point (Tm) of the propylene polymer as the base resin, the higher the melting point (Tm), and the lower the melting point (Tm), the lower the melting point (Tm).

When the water vapor permeability (Y) is lower than [(−0.20) · Tm + 35], the permeability of the water vapor and the foaming agent to the base resin becomes poor, and conversely, [(−0.33) ) .Tm + 60], the permeability of water vapor to the base resin becomes too good. In any case, the dispersion of water and the foaming agent in the resin particles during the production process of the foamed particles becomes uneven. And the uniformity of the cell diameter of the obtained expanded particles may be reduced. In particular, when the water vapor permeability (Y) exceeds [(−0.33) · Tm + 60], coarse bubbles may be mixed in the obtained expanded particles.

プ ロ ピ レ ン A propylene-based polymer having a melting point (Tm) and a water vapor permeability (Y) satisfying the relationship of the formula (1) can be obtained by selecting an appropriate catalyst in producing the polymer. Specifically, among the above-mentioned metallocene-based catalysts, it can be suitably obtained by using bridged bis {1,1 '-(4-hydroazulenyl)} zirconium dichloride as a metal complex component. Preferred examples of such a metal complex component are as described above.

In the present invention, the melting point (Tm) of the propylene-based polymer [A] is generally from 125 ° C to 165 ° C, preferably from 130 ° C to 160 ° C, more preferably from 133 ° C to 158 ° C.
The melting point (Tm) described in JIS K7121 (1987) is used to determine the melting temperature after performing a certain heat treatment. , Each adopts 10 ° C. per minute), a DSC curve is drawn at a heating rate of 10 ° C. per minute using a heat flux DSC apparatus, and the top of the melting peak on the obtained DSC curve is adopted. If multiple peaks are observed, the peak with the highest melting peak is used based on the baseline on the high-temperature side. If there are multiple peaks with the highest melting peak, their arithmetic mean values are used. Is adopted.

Next, the propylene-based polymer [B] in the first invention will be described.
The propylene-based polymer [B] is a propylene-based polymer having only the requirement (a) among the requirements (a) and (b). That is, in the propylene-based polymer [B], 100 to 85 mol% of structural units obtained from propylene and 0 to 15 mol% of structural units obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms are present. That is, the requirement (a) is satisfied, but the requirement (b) is not satisfied. The propylene-based polymer [B] usually does not satisfy the above formula (1). Such a propylene-based polymer [B] can be obtained using, for example, a Ziegler / Natta catalyst or the like.
The requirement (a) is the same as the requirement [a] for the propylene-based polymer [A].

The foamed resin particles obtained by using a resin composition obtained by mixing the propylene polymer [B] with the propylene polymer [A] as a base resin are the propylene polymer [A]. Compared with the resin foam particles obtained by using the resin alone, the secondary foamability in in-mold molding is excellent, and therefore, the surface appearance of the molded article is excellent.

The reason for this is not necessarily clear, but is presumed to be due to the following mechanism.
That is, the propylene-based polymer [A] generally has a narrow molecular weight distribution, while the propylene-based polymer [B] generally has a wide molecular weight distribution. Therefore, the resin composition obtained by mixing the propylene-based polymer [B] with the propylene-based polymer [A] has a wide molecular weight distribution.

Also, the process of expanding the resin particles to produce the expanded particles can be regarded as a process of stretching the resin portion, and thus can be considered as a process of orienting the resin. When the degree of this orientation is high, the oriented portion is considered to act in a direction to suppress secondary foaming when the foamed particles are heated. Conversely, the lower the degree of orientation, the higher the secondary foamability in in-mold molding.
In general, when the molecular weight distribution is broad, the degree of orientation is lower than when the molecular weight distribution is narrow. From this, the expanded polypropylene resin particles obtained by using the resin composition obtained by mixing the propylene polymer [A] with the propylene polymer [B] are the same as the propylene polymer [A]. It is presumed that the secondary foaming power is higher than that of the foamed resin particles obtained by using [A] alone.

In addition, resin foamed particles obtained by using a resin composition obtained by mixing the propylene-based polymer [A] and the propylene-based polymer [B] as a base resin are the propylene-based polymer [B]. Compared to the resin foam particles obtained by using alone, they can be molded at a lower temperature, and are further characterized by excellent mechanical properties such as compressive strength and bending strength.

The mixing ratio of the propylene-based polymer [A] and the propylene-based polymer [B] is 5 to 95% by weight of the propylene-based polymer [A] and 95 to 95% by weight of the propylene-based polymer [B]. It is necessary to be in the range of 5% by weight (however, the total amount of the propylene-based polymer [A] and the propylene-based polymer [B] is 100% by weight).
When the blending ratio of the propylene-based polymer [A] is less than 5% by weight, since the propylene-based polymer [B] is a main component, the bubble diameter in the obtained expanded particles tends to be small. And its mechanical properties may be insufficient. In addition, high-temperature steam may be required for in-mold molding of such expanded resin particles.
On the other hand, if the blending ratio of the propylene-based polymer [A] exceeds 95% by weight, the obtained foamed polypropylene-based resin particles may have insufficient secondary expandability.

The mixing ratio of the propylene polymer [A] and the propylene polymer [B] is preferably 10 to 80% by weight of the propylene polymer [A] and the propylene polymer [B]. 90 to 20% by weight (however, the total amount of the propylene-based polymer [A] and the propylene-based polymer [B] is 100% by weight), and more preferably the propylene-based polymer [A] is 20 to 20% by weight. The propylene-based polymer [B] is preferably 80 to 20% by weight relative to 80% by weight (however, the total amount of the propylene-based polymer [A] and the propylene-based polymer [B] is 100% by weight).

In the present invention, the propylene-based polymer [A] preferably further has the following requirement (d) (claim 2).
(D) The isotactic triad fraction in the propylene unit chain portion composed of head-to-tail bonds, as measured by 13C-NMR, is 97% or more.
In this case, the effect that the uniformity of the cell diameter in the foamed particles obtained by using the above-mentioned polypropylene-based resin composition as the base resin can be further improved can be obtained.

That is, in addition to the requirements (a) and (b) described above, a 13C-NMR of a propylene unit chain portion composed of a head-to-tail bond is further defined as a propylene polymer [A] which is a constituent component of the resin composition. Isotactic triad fraction measured by (nuclear magnetic resonance method) (that is, among three arbitrary propylene units in a polymer chain, each propylene unit is linked head-to-tail, and methyl branching in the propylene unit) (The proportion of three propylene units in the same direction) is 97% or more.

The isotactic triad fraction is hereinafter referred to as the mm fraction as appropriate. When the mm fraction is less than 97%, the mechanical properties of the polypropylene resin composition are reduced. Therefore, there is a possibility that the mechanical properties of a molded article made of foamed particles obtained by using this as a base resin may also be reduced.
In addition, more preferably, the mm fraction is 98% or more.

Next, the propylene polymer [A] preferably further has the following requirement (e) (claim 3).
(E) The melt flow rate is 0.5 to 100 g / 10 minutes.

In this case, the polypropylene resin composition can be produced while maintaining industrially useful production efficiency. Further, a molded article made of expanded particles obtained by using this as a base resin can have the effect of having excellent mechanical properties.

If the melt flow rate (MFR) is less than 0.5 g / 10 minutes, the production efficiency of the polypropylene-based resin composition, especially the productivity when performing the melt-kneading described below, may be reduced. When the MFR exceeds 100 g / 10 minutes, the dynamic properties such as the compressive strength and the tensile strength of the molded product obtained by further molding the expanded particles using the obtained polypropylene resin composition as the base resin are obtained. Physical properties may be reduced. In addition, Preferably, it is 1.0 to 50 g / 10 minutes, Furthermore, it is 1.0 to 30 g / 10 minutes. The above-mentioned MFR means a melt mass flow rate measured according to the conditions described in Table 3 of JIS K6921-2 (1997).

Next, the polypropylene-based resin composition preferably exhibits a substantially single melting peak as measured by a differential scanning calorimeter (claim 4).
"A melting point measured by a differential scanning calorimeter shows a substantially single melting peak" means that when the melting point of the polypropylene resin composition is measured by the same method as the method for measuring the melting point (Tm), 1 In addition to the case where two melting peaks are observed, even when multiple melting peaks are observed, the temperature difference between the apexes of adjacent melting peaks (the apex of the hot side melting peak-the low temperature side) The temperature difference is preferably within 5 ° C, more preferably within 3 ° C.

However, in this case, the temperature difference is the difference between the tops of the respective melting peaks (high-temperature side) obtained when the melting points of the propylene-based polymer [A] and the propylene-based polymer [B] are measured independently. (The peak of the melting peak−the peak of the low-temperature melting peak).
The smaller the temperature difference between the vertexes of the adjacent melting peaks, the higher the level of the propylene-based polymer [A] and the higher the propylene-based polymer [B] are. This shows that the composition has high uniformity. As a result, foamed resin particles obtained by using such a polypropylene-based resin composition as a base resin have excellent secondary foamability during in-mold molding.
In the present invention, the melting point of the propylene polymer [B] may be the same as the melting point of the propylene polymer [A] used, but the melting points of both polymers are 2 ° C. or more. It is preferably separated, more preferably 3 ° C or more, more preferably 5 to 30 ° C.

The polypropylene-based resin composition according to the present invention is used as a material for obtaining expanded polypropylene-based resin particles using this as a base resin. Furthermore, the polypropylene resin foamed particles can be filled in a mold and heated to expand the foam to obtain a molded article in the mold.

Next, in the second invention (Claim 5), it is preferable that the expanded polypropylene resin particles are foamed using a foaming agent satisfying the following requirement (f) (Claim 6).
(F) When the critical temperature of the foaming agent is Tc [° C.], Tc satisfies the following expression (2).
-90 ° C ≦ Tc ≦ 400 ° C Equation (2)

(4) In this case, the foamed polypropylene resin particles obtained tend to have a uniform cell diameter, and as a result, the mechanical properties of the in-mold foam molded product obtained using such foamed particles are improved.

If Tc is less than -90 ° C, the resulting foamed polypropylene resin particles may have remarkable unevenness in cell diameter. The reason for this is not necessarily clear, but is presumed to be due to the rapid progress of foaming.
On the other hand, when the temperature exceeds 400 ° C., it may be extremely difficult to obtain high magnification, for example, expanded polypropylene resin particles having a bulk density of 0.1 g / cm ³ or less.

具体 Specific examples of the above foaming agents are as follows. The critical temperature (° C) is also described after the substance name. Chains of methane (-82), ethane (32), propane (97), butane (152), isobutane (135), pentane (197), hexane (235), cyclopentane (239), cyclohexane (280), etc. And halogenated hydrocarbons such as dichlorodifluoromethane (112) and trichloromonofluoromethane (198), and inorganic gases such as carbon dioxide (31).

Further, among the foaming agents satisfying the above formula (2), when the following formula (3) is further satisfied, there is an advantage that special equipment and apparatus are not required particularly for handling these foaming agents. There is.
0 ° C ≦ Tc ≦ 300 ° C Equation (3)

Further, when the following expression (4) is satisfied, in addition to the industrial utility described in the preceding section, there is an effect that the bubble diameter of the obtained expanded particles becomes extremely uniform.
30 ° C ≦ Tc ≦ 200 ° C Equation (4)
The above-mentioned foaming agents may be used alone or in combination with a plurality of foaming agents.

Further, as the foaming agent, a so-called inorganic gas such as nitrogen, oxygen, air, carbon dioxide, and water is used as the foaming agent as a whole or as a main component (50 mol% or more of the entire foaming agent, preferably 70 mol% or more, more preferably Is 90 mol% or more.) When used, the energy absorption of the final in-mold foam molded article can be increased. Among these inorganic gases, nitrogen, air, and carbon dioxide are particularly preferable in consideration of the stability of the apparent density of the expanded particles, the environmental load, the cost, and the like.

Next, in the expanded polypropylene resin particles of the second invention, the above-mentioned base resin of the polypropylene resin composition comprising the propylene polymer [A] and the propylene polymer [B] is used. As described above, other polymer components and additives can be mixed as long as the effects of the present invention are not impaired.

Examples of the other polymer component include ethylene resins such as high-density polyethylene, low-density polyethylene, and linear low-density polyethylene which is a copolymer of ethylene and an α-olefin (having 4 or more carbon atoms); polybutene resin; Ethylene-propylene rubber; Ethylene-propylene-diene rubber; hydrogenated block obtained by saturating at least a part of the ethylene-based double bond of styrene-diene block copolymer or styrene-diene block copolymer by hydrogenation Styrene-based thermoplastic elastomers such as copolymers; and graft-modified products of these resins, elastomers or rubbers with acrylic acid-based monomers. In the present invention, these resins, elastomers, rubbers or modified products thereof can be used alone or in combination of two or more.

As the above additives, various additives such as a foam nucleating agent, a coloring agent, an antistatic agent, a lubricant and the like can be added. These are usually added together at the time of melt kneading described later and contained in the resin particles.
Examples of the foam nucleating agent include inorganic compounds such as talc, calcium carbonate, silica, titanium oxide, gypsum, zeolite, borax, zinc borate, and aluminum hydroxide, as well as carbon, phosphoric acid nucleating agents, and phenolic nucleating agents. And organic nucleating agents such as amine nucleating agents. The amount of these various additives varies depending on the purpose of the addition, but is not more than 15 parts by weight, preferably not more than 8 parts by weight, more preferably not more than 5 parts by weight based on 100 parts by weight of the base resin of the present invention. preferable.

In the present invention, when mixing the propylene-based polymer [A] and the propylene-based polymer [B] as the base resin and when mixing the other components into the base resin, solid mixing is performed. However, in general, melt kneading is used. That is, using a kneader such as a roll, a screw, a Banbury mixer, a kneader, a blender, or a mill, the above-mentioned propylene-based polymers or the above-mentioned base resin and other components are kneaded at a desired temperature. After kneading, it is formed into resin particles having a size suitable for the production of expanded particles.

After melt-kneading in the extruder, the kneaded material is extruded in a string form from a mouthpiece having micro holes attached to the tip of the extruder, and cut into a specified weight or size with a cutter equipped with a take-off machine to reduce the resin particles. The method of obtaining is preferred.
Generally, if the weight of one resin particle is 0.1 to 20 mg, there is no problem in the production of foamed particles. If the weight of one resin particle is in the range of 0.2 to 10 mg and the variation in the weight between the particles is small, the production of the expanded particles becomes easy, and the density variation of the obtained expanded particles also becomes small. In addition, the filling property of the foamed resin particles into the molding die and the like is improved.

As a method for obtaining foamed particles, a method of impregnating a resin particle with a volatile foaming agent and then heating and foaming, specifically, for example, Japanese Patent Publication Nos. 49-2183 and 56-1344, West German Patent The methods described in Japanese Patent Nos. 1857722 and 2107683 can be used.

When the resin particles are impregnated with a foaming agent and then heat-foamed, put the resin particles together with the volatile foaming agent in a pressure vessel that can be sealed and opened, and heat the resin particles above the softening temperature of the base resin, as well as volatile foaming the resin particles. Impregnate the agent. After that, the contents in the closed container are released from the closed container to a low-pressure atmosphere, and then the drying process is performed. Thereby, foamed particles are obtained.

The expanded polypropylene particles of the present invention have a DSC curve obtained by differential scanning calorimetry (provided that 2 to 4 mg of expanded particles are heated from 20 ° C to 200 ° C by a differential scanning calorimeter at a rate of 10 ° C / min). In the DSC curve obtained at the time of the above, it is preferable to show an endothermic peak at a higher temperature in addition to the endothermic peak inherent to the base resin.

In addition to the endothermic peak specific to the base resin in the DSC curve, an expanded particle in which an endothermic peak having a higher temperature than the endothermic peak can be produced by a method described in, for example, JP-A-2002-200635. Yes, it can be obtained by controlling the conditions for foaming the resin particles, specifically, the temperature, pressure, time, etc., until the resin particles are released into a low-pressure atmosphere.

In the method of producing foamed particles by discharging the contents in the closed container from the closed container to a low-pressure atmosphere, if the decomposable foaming agent is kneaded in the resin particles in advance, the foaming agent is contained in the pressure container. The above-mentioned expanded particles can be obtained without blending.
As the decomposable foaming agent, any one that decomposes at the foaming temperature of the resin particles to generate gas can be used. Specific examples include sodium bicarbonate, ammonium carbonate, azide compounds, azo compounds and the like.

(4) At the time of heating and foaming, it is preferable to use water, alcohol, or the like as a dispersion medium for the resin particles. In addition, aluminum oxide, tribasic calcium phosphate, magnesium pyrophosphate, zinc oxide, kaolin, amsunite, mica, clay, and other poorly water-soluble inorganic substances, polyvinylpyrrolidone, and polyvinyl alcohol so that the resin particles are uniformly dispersed in the dispersion medium. It is preferable to use a water-soluble polymer-based protective colloid agent such as methyl cellulose and anionic surfactants such as sodium dodecylbenzenesulfonate and sodium alkanesulfonate alone or as a mixture of two or more.

Further, a dispersion enhancer that enhances the dispersing power of the dispersant (prevents fusion of the resin particles in the container even when the amount of the dispersant is reduced) may be added to the dispersion medium. In particular, when producing low-expanded foamed particles having an apparent density of 100 g / L or more, it is preferable to use a dispersion enhancer.
As such a dispersion enhancer, an inorganic substance which can be dissolved in at least 1 mg or more in 100 cc of water at 40 ° C. and in which at least one of the anion and cation of the compound is divalent or trivalent, is used. be able to. Examples of such an inorganic substance include magnesium chloride, magnesium nitrate, magnesium sulfate, aluminum chloride, aluminum nitrate, aluminum sulfate, iron chloride, iron sulfate, and iron nitrate.

When releasing resin particles into a low-pressure atmosphere, in order to facilitate the release, the same inorganic gas or volatile foaming agent as described above is introduced into the closed container from outside to keep the pressure in the closed container constant. It is preferable to hold.

The expanded polypropylene resin particles obtained by the above-described method are aged under atmospheric pressure, and after increasing the internal pressure of the cells as necessary, are heated with steam or hot air to form expanded particles having a higher expansion ratio. It can be a particle.

Next, the expanded polypropylene resin particles of the present invention are molded using dies under various conditions. For example, after filling foamed polypropylene resin particles into a cavity composed of a pair of cavities and depressions under atmospheric pressure or reduced pressure, the cavities are compressed so as to reduce the volume of the cavities by 5 to 70%. A compression molding method in which a heat medium is introduced into the cavity and the polypropylene-based resin foam particles are heated and fused is exemplified (for example, Japanese Patent Publication No. 46-38359).

In addition, the foaming resin particles are preliminarily treated with one or more of a volatile foaming agent or an inorganic gas to increase the secondary foaming force of the foaming resin particles, and then the atmospheric pressure or the pressure is reduced while maintaining the secondary foaming force. There is also a pressure aging method in which, after filling the foamed resin particles into a cavity formed by a pair of lower concave and convex molds, a heating medium is introduced into the mold cavity and the foamed resin particles are heated and fused. JP-B-51-22951).

Also, after filling the foamed resin particles pressurized above the atmospheric pressure into the mold cavity pressurized by the compressed gas or more, the foamed resin is introduced by introducing a heat medium such as steam into the mold cavity. There is also a compression filling method of heating and fusing the particles (for example, Japanese Patent Publication No. 4-46217).

Further, using foamed resin particles having a high secondary foaming power obtained under special conditions, the foamed resin particles are filled into a cavity formed by a pair of concave and convex molds under atmospheric pressure or reduced pressure. There is also a normal pressure filling method in which a heat medium such as steam is introduced into the cavity to heat and fuse the foamed resin particles (for example, Japanese Patent Publication No. 6-49795). It can also be formed by a combination of the above methods (for example, see Japanese Patent Publication No. Hei 6-22919).

フ ィ ル ム Furthermore, a film can be laminated on the above-mentioned foamed molded article as required. The film to be laminated is not particularly limited. For example, polystyrene resin films such as OPS (biaxially oriented polystyrene sheet), heat-resistant OPS and HIPS, and polypropylene such as CPP (unoriented polypropylene film) and OPP (biaxially oriented polypropylene film) A resin film, a polyethylene resin film, a polyester resin film, or the like is used.

Although the thickness of the film to be laminated is not limited, a film of 15 μm to 150 μm is usually used. These films may be printed as needed. When lamination is performed, it may be performed simultaneously with the heat fusion molding of the expanded particles. Moreover, you may laminate | stack on the molded object once molded. In addition, lamination can also be performed using a hot-melt adhesive as needed.

Next, in the in-mold molded product of the third invention, the density of the in-mold molded product is 0.008 to 0.5 g / cm ³ . If the density of the in-mold molded body is more than 0.5 g / cm ³ , favorable characteristics of the foam such as light weight, shock absorption, and heat insulation cannot be sufficiently exhibited, and the low foaming ratio results in a disadvantage in cost. May be caused.
On the other hand, if the density is less than 0.008 g / cm ³ , the closed cell ratio tends to be small, and mechanical properties such as bending strength and compressive strength may be insufficient.
The in-mold molded product of the present invention is suitable for, for example, packaging containers, toys, automobile parts, helmet core materials, cushioning packaging materials, and the like.

Next, embodiments of the present invention will be described.

[Production of propylene-based polymer]
First, propylene polymers [A] and [B] constituting the polypropylene resin composition were synthesized by the methods shown in Production Examples 1 to 8 below.

Production Example 1
(I) Synthesis of [dimethylsilylenebis {1,1 ′-(2-methyl-4-phenyl-4-hydroazulenyl)} zirconium dichloride] The following reactions were all carried out in an inert gas atmosphere. A dried and purified solvent was used.

(A) Synthesis of racemic-meso mixture 2.22 g of 2-methylazulene synthesized according to the method described in JP-A-62-207232 was dissolved in 30 mL of hexane, and 15.6 mL of a cyclohexane-diethyl ether solution of phenyllithium (15.6 mL). 1.0 eq) at 0 ° C. in small portions.
The solution was stirred at room temperature for 1 hour, cooled to -78 ° C, and 30 mL of tetrahydrofuran was added.

Next, 0.95 mL of dimethyldichlorosilane was added, the temperature was raised to room temperature, and the mixture was further heated at 50 ° C. for 90 minutes. Thereafter, a saturated aqueous solution of ammonium chloride was added, the organic layer was separated, dried over sodium sulfate, and the solvent was distilled off under reduced pressure.

The resulting crude product was purified by silica gel column chromatography (hexane-: dichloromethane = 5: 1) to give bis {1,1 '-(2-methyl-4-phenyl-1,4-dihydroazulenyl). 1.) 1.48 g of dimethylsilane were obtained.
786 mg of bis {1,1 ′-(2-methyl-4-phenyl-1,4-dihydroazulenyl) dimethylsilane obtained above is dissolved in 15 mL of diethyl ether, and n-butyllithium hexane is added at −78 ° C. 1.98 mL of a solution (1.68 mol / L) was added dropwise, and the temperature was gradually raised to room temperature, followed by stirring at room temperature for 12 hours. The solid obtained by evaporating the solvent under reduced pressure was washed with hexane and dried under reduced pressure.

Further, 20 mL of a toluene-diethyl ether mixed solvent (40: 1) was added, 325 mg of zirconium tetrachloride was added at -60 ° C, and the mixture was gradually heated and stirred at room temperature for 15 minutes.
The obtained solution is concentrated under reduced pressure, and hexane is added to cause reprecipitation, whereby dimethylsilylenebis {1,1 ′-(2-methyl-4-phenyl-4-hydroazulenyl)} zirconium dichloride is obtained. / Meso mixture 150 mg was obtained.

(B) Separation of a racemic body 887 mg of a racemic / meso mixture obtained by repeating the above reaction was placed in a glass container, dissolved in 30 mL of dichloromethane, and irradiated with light from a high-pressure mercury lamp for 30 minutes. Thereafter, dichloromethane was distilled off under reduced pressure to obtain a yellow solid.
To this solid, 7 mL of toluene was added, stirred, and allowed to stand, whereby a yellow solid was separated as a precipitate. The supernatant was removed, and the solid was dried under reduced pressure to give 437 mg of a racemate comprising dimethylsilylenebis {1,1 '-(2-methyl-4-phenyl-4-hydroazulenyl)} zirconium dichloride.

(Ii) Synthesis of catalyst (a) Treatment of catalyst carrier 135 mL of demineralized water and 16 g of magnesium sulfate were placed in a glass container, and stirred to form a solution. 22.2 g of montmorillonite ("Kunipia-F" manufactured by Kunimine Industries) was added to this solution, and then the temperature was raised and the temperature was maintained at 80 ° C for 1 hour.
Then, after adding 300 mL of demineralized water, the solid content was separated by filtration. After adding 46 mL of demineralized water, 23.4 g of sulfuric acid, and 29.2 g of magnesium sulfate to the solid content, the mixture was heated, treated with heating under reflux for 2 hours, added with 200 mL of demineralized water, and filtered.
Further, an operation of adding 400 mL of deionized water and filtering was performed twice. Thereafter, the solid was dried at 100 ° C. to obtain a chemically treated montmorillonite as a catalyst carrier.

(B) Preparation of catalyst component After sufficiently replacing the inside of a 1-liter stirred autoclave with propylene, 230 mL of dehydrated heptane was introduced, and the system temperature was maintained at 40 ° C.
Here, 10 g of the chemically treated montmorillonite as a catalyst carrier prepared above was suspended in 200 mL of toluene and added.

Furthermore, racemic (0.15 mmol) of dimethylsilylenebis {1,1 ′-(2-methyl-4-phenyl-4-hydroazulenyl)} zirconium dichloride and triisobutylaluminum (3 mmol) prepared in separate containers. Was mixed in toluene (20 mL in total) and added to the autoclave.

(5) Thereafter, propylene was introduced at a rate of 10 g / hr for 120 minutes, and thereafter, the polymerization reaction was continued for 120 minutes. Thereafter, the solvent was distilled off and dried under a nitrogen atmosphere to obtain a solid catalyst component. This catalyst component contained 1.9 g of polymer per 1 g of solid component.

(Iii) Polymerization of propylene (production of propylene polymer A)
After sufficiently replacing the inside of a stirred autoclave having an internal volume of 200 L with propylene, 45 kg of sufficiently dehydrated liquefied propylene was introduced. To this, 500 mL (0.12 mol) of a hexane solution of triisobutylaluminum and hydrogen (3NL) were introduced, and the inside of the autoclave was heated to 70 ° C.
Thereafter, the solid catalyst component (1.7 g) was press-injected with argon to start polymerization, and a polymerization reaction was performed for 3 hours.

Thereafter, 100 mL of ethanol was injected into the reaction system to stop the reaction, and the remaining gas components were purged to obtain 14.1 kg of a polymer.
This polymer has 100 mol% of structural units obtained from propylene, that is, it is a propylene homopolymer. This satisfies the requirement (a).

This polymer has an MFR (melt flow rate) of 10 g / 10 min, an isotactic triad fraction of 99.7%, and a melting point (Tm) of 146 ° C., and satisfies the above requirements (d) and (e). Meets Furthermore, the ratio of the position irregular units based on the 2,1-insertion is 1.32%, and the ratio of the position irregular units based on the 1,3-insertion is 0.08%, which satisfies the requirement (b). I have.
Hereinafter, the obtained polypropylene-based polymer is referred to as “polymer 1”.

(Iv) Measurement of Water Vapor Permeability The polymer 1 obtained above was formed into a film having a thickness of 25 μm, and the water vapor permeability Y was measured according to the method described in JIS K7129 (the same applies to the following production examples). was ^{.5 (g / m 2 / 24hr} ).
In addition, since the melting point Tm of the polymer 1 is 146 ° C. as described above, from the above formula (1), Y should be within the range of 5.8 ≦ Y ≦ 11.8. Was.

Production Example 2 (Production of propylene-based polymer [A], propylene homopolymerization)
After sufficiently replacing the inside of a stirred autoclave having an internal volume of 200 L with propylene, 45 kg of sufficiently dehydrated liquefied propylene was introduced. To this, 500 mL (0.12 mol) of a hexane solution of triisobutylaluminum and hydrogen (3 NL) were introduced, and the inside of the autoclave was heated to 40 ° C.
Thereafter, the solid catalyst component (3.0 g) was injected with argon to start polymerization, and a polymerization reaction was performed for 3 hours.

Thereafter, 100 mL of ethanol was injected into the reaction system to stop the reaction, and the remaining gas components were purged to obtain 4.4 kg of a polymer.
This polymer has 100 mol% of structural units obtained from propylene, that is, it is a propylene homopolymer. This satisfies the requirement (a).

Further, this polymer has MFR = 2, an isotactic triad fraction of 99.8%, and a melting point (Tm) of 152 ° C., and satisfies the requirements (d) and (e). Further, the ratio of the position irregular units based on the 2,1-insertion is 0.89%, and the ratio of the position irregular units based on the 1,3-insertion is 0.005%, which satisfies the requirement (b). I have.
Hereinafter, the obtained polymer is referred to as “polymer 2”.

As for the polymer 2, as in the polymer 1 was examined the water vapor transmission rate Y when molded into a film was ^{9.5 (g / m 2 / 24hr} ).
In addition, since the melting point Tm of the polymer 2 is 152 ° C. as described above, from the above formula (1), Y should be within the range of 4.6 ≦ Y ≦ 9.8, but is within the range. Was.

Production Example 3 (Production of propylene polymer [A], propylene / ethylene copolymerization)
After sufficiently replacing the inside of a 200 L stirred autoclave with propylene, 60 L of purified n-heptane was introduced, 500 mL (0.12 mol) of a hexane solution of triisobutylaluminum was added, and the inside of the autoclave was heated to 70 ° C. Warmed up. Thereafter, the solid catalyst component (9.0 g) was added, and a mixed gas of propylene and ethylene (propylene: ethylene = 97.5: 2.5; weight ratio) was introduced so that the pressure became 0.7 MPa. To initiate polymerization, and a polymerization reaction was carried out under these conditions for 3 hours.

Thereafter, 100 mL of ethanol was injected into the reaction system to stop the reaction, and the remaining gas components were purged to obtain 9.3 kg of a polymer.
This polymer contains 97.0 mol% of structural units obtained from propylene and 3.0 mol% of structural units obtained from ethylene. This satisfies the requirement (a).

This polymer had MFR = 14, ethylene content = 2.0 wt%, isotactic triad fraction of 99.2%, and melting point (Tm) of 141 ° C., satisfying the above requirements (d) and (e). Meets Further, the ratio of the position irregular units based on the 2,1-insertion is 1.06%, and the ratio of the position irregular units based on the 1,3-insertion is 0.16%, which satisfies the requirement (b). I have.
Hereinafter, the obtained polymer is referred to as “polymer 3”.

Further, the polymer 3, in the same manner as in the polymer 1 and polymer 2, was examined water vapor transmission rate Y after molding into a film was ^{12.0 (g / m 2 / 24hr} ).
In addition, since the melting point Tm of the polymer 3 is 141 ° C. as described above, from the above formula (1), Y should be within the range of 6.8 ≦ Y ≦ 13.5, but should be within the range. Was.

Production Example 4 (Production of propylene-based polymer [A], propylene / 1-butene copolymerization)
After sufficiently replacing the inside of a 200 L stirred autoclave with propylene, 60 L of purified n-heptane was introduced, 500 mL (0.12 mol) of a hexane solution of triisobutylaluminum was added, and the inside of the autoclave was heated to 70 ° C. Warmed up. Thereafter, the solid catalyst component (9.0 g) was added, and a mixed gas of propylene and 1-butene (propylene: 1-butene = 90: 10) was introduced so that the pressure became 0.6 MPa, to start polymerization. Then, a polymerization reaction was carried out under these conditions for 3 hours.

Thereafter, 100 mL of ethanol was injected into the reaction system to stop the reaction, and the remaining gas components were purged to obtain 8.6 kg of a polymer.
This polymer contains 95.4 mol% of a structural unit obtained from propylene and 4.6 mol% of a structural unit obtained from 1-butene. This satisfies the requirement (a).

This polymer had MFR = 6,1-butene content = 6.0 wt%, a melting point (Tm) of 142 ° C., an isotactic triad fraction of 99.3%, and the above requirements (d) and (e). ). Furthermore, the ratio of the position irregular units based on the 2,1-insertion is 1.23%, and the ratio of the position irregular units based on the 1,3-insertion is 0.09%, which satisfies the requirement (b). I have. The polymer obtained here is referred to as “Polymer 4”.

Polymer 4 was formed into a film in the same manner as in the polymer 1 to 3, were examined water vapor transmission rate Y, it was ^{11.5 (g / m 2 / 24hr} ).
In addition, since the melting point Tm of the polymer 4 is 142 ° C. as described above, from the above formula (1), Y should be within the range of 6.6 ≦ Y ≦ 13.1. Was.

Production Example 5 (Production of propylene polymer [B], propylene homopolymerization)
After sufficiently replacing the inside of a 200 L stirred autoclave with propylene, 60 L of purified n-heptane was introduced, and 11.5 g of diethylaluminum chloride (45 g) and a titanium trichloride catalyst manufactured by Marubeni Solvay Co., Ltd. were placed in a propylene atmosphere. Introduced. Further, while maintaining the hydrogen concentration in the gas phase at 7.0% by volume, propylene was introduced into the autoclave at an internal temperature of 60 ° C. at a rate of 9 kg / hr for 4 hours.

After stopping the introduction of propylene, the reaction was further continued for 1 hour, the reaction was stopped by adding 100 mL of butanol to the reaction system, and the remaining gas components were purged to obtain 26 kg of a polymer. The polymer obtained here is referred to as “Polymer 5”.
This polymer has 100 mol% of structural units obtained from propylene, that is, it is a propylene homopolymer. This satisfies the requirement (a).

This polymer had an MFR of 7, a melting point (Tm) of 165 ° C., an isotactic triad fraction of 97.6%, a proportion of regiorandom units based on 2,1-insertion of 0%, and 1,3-insertion. Was 0%.
That is, this one does not satisfy the requirement (b).

For Polymer 5, in the same manner as in the above polymers 1 to 4, were examined water vapor transmission rate Y after molding into a film was ^{7.8 (g / m 2 / 24hr} ).
Since the melting point Tm of the polymer 5 is 165 ° C. as described above, from the above formula (1), Y should be within the range of 2.0 ≦ Y ≦ 5.6, but should be within the range. Absent.

Production Example 6 (Production of propylene-based polymer [B], propylene / ethylene copolymerization)
After sufficiently replacing the inside of a 200 L stirred autoclave with propylene, 60 L of purified n-heptane was introduced, and diethyl aluminum chloride (40 g) and 7.5 g of Marubeni Solvay's titanium trichloride catalyst were placed in a propylene atmosphere. Introduced. Further, while maintaining the hydrogen concentration in the gas phase at 7.0% by volume, a mixed gas of propylene and ethylene (propylene: ethylene = 97.5: 2.5; weight ratio) was applied at an internal temperature of the autoclave of 60 ° C. The pressure was introduced so as to be 0.7 MPa.

After stopping the introduction of the mixed gas, the reaction was further continued for 1 hour, the reaction was stopped by adding 100 mL of butanol to the reaction system, and the residual gas component was purged to obtain 32 kg of a polymer. This polymer is referred to as “polymer 6”.
This polymer contains 96.1 mol% of structural units obtained from propylene and 3.9 mol% of structural units obtained from ethylene. This satisfies the requirement (a).

Further, this polymer 6 had MFR = 12, melting point (Tm) of 146 ° C., an isotactic triad fraction of 96%, a proportion of position irregular units based on 2,1-insertion of 0%, and 1,3-insertion. Was 0%.
That is, the polymer 6 does not satisfy the requirement (b).

Further, the polymer 6, in the same manner as in the above polymers 1 to 5, were examined water vapor transmission rate Y after molding into a film was ^{15.0 (g / m 2 / 24hr} ).
In addition, since the melting point Tm of the polymer 6 is 146 ° C., from the above formula (1), Y should be within the range of 5.8 ≦ Y ≦ 11.8, but does not fall within the range.

Production Example 7 (Production of propylene polymer [B], propylene homopolymerization)
The method was carried out by applying the method described in [Production of base resin 1] in the examples of JP-A-6-240041.
That is, after thoroughly replacing the inside of a 200 L stirred autoclave with propylene, 60 L of purified n-heptane was introduced, and 120 g of methylalumoxane (average degree of oligomer 16) manufactured by Tosoh Akzo Co., Ltd. was used. Rac-Dimethylsilylenebis (2-methylindenyl) zirconium dichloride (150 mg) synthesized by the method described in Japanese Patent No. 268307 was introduced in a propylene atmosphere. Further, while maintaining the hydrogen concentration in the gas phase at 0.5% by volume, propylene was introduced into the autoclave at an internal temperature of 40 ° C. at a rate of 7 kg / hr for 3 hours.

After stopping the introduction of propylene, the reaction was further continued for 1 hour, the reaction was stopped by adding 100 mL of butanol to the reaction system, and the residual gas component was purged to obtain 9.4 kg of a polymer. This polymer is referred to as “polymer 7”.
This polymer 7 had an MFR = 9, a melting point (Tm) of 150 ° C., an isotactic triad fraction of 94.4%, a proportion of positional irregular units based on 2,1-insertion of 0.25%, and 1,1. 3- The proportion of regio-irregular units due to insertion was below the detection limit, ie less than 0.005%. That is, this one does not satisfy the requirement (b).
In Table 2, which will be described later, the ratio of the position irregular units based on the 1,3 insertion of the polymer 7 is shown as 0%.

Also, for the polymer 7, in the same manner as in the above polymers 1 to 6, were examined water vapor transmission rate Y after molding into a film was ^{4.8 (g / m 2 / 24hr} ).
In addition, since the melting point Tm of this polymer 7 is 150 ° C., Y should be within the range of 5.0 ≦ Y ≦ 10.5 from the above formula (1), but it was outside the range.

Production Example 8 (Production of propylene-based polymer [B], propylene homopolymerization)
After sufficiently replacing the inside of a 200 L stirred autoclave with propylene, 60 L of purified n-heptane was introduced, and 120 g of methylalumoxane (average degree of oligomer: 16) manufactured by Tosoh Akzo Co., Ltd. was used. H. Yamazaki et al., "Chemistry Letters", Japan, 1989, Vol. 18, p. 1853], rac-dimethylsilylenebis (3-methylcyclopentadienyl) zirconium dichloride (100 mg) was introduced under a propylene atmosphere. Further, while maintaining the hydrogen concentration in the gas phase at 0.5% by volume, propylene was introduced into the autoclave at an internal temperature of 40 ° C. at a rate of 7 kg / hr for 3 hours.

After stopping the introduction of propylene, the reaction was further continued for 1 hour, the reaction was stopped by adding 100 mL of butanol to the reaction system, and the residual gas component was purged to obtain 5.6 kg of a polymer. This polymer is referred to as "polymer 8".
This polymer 8 has an MFR = 20, a melting point of 141 ° C., an isotactic triad fraction of 91.5%, a proportion of regiorandom units based on 2,1-insertion of 2.1%, and 1,3-insertion. Was 0.45%.
That is, this one does not satisfy the requirement (b).

Also, for the polymer 8, in the same manner as in the above polymers 1 to 7, were examined water vapor transmission rate Y after molding into a film was ^{13.8 (g / m 2 / 24hr} ).
In addition, since the melting point Tm of this polymer 8 is 141 ° C., from the above formula (1), Y should be within the range of 6.8 ≦ Y ≦ 13.5, but was out of the range.
Tables 1 and 2 show the results of Production Examples 1 to 8 described above.

As can be seen from Table 1, Polymer 1 to Polymer 4 satisfy the above requirements (a) and (b) and correspond to the propylene-based polymer [A]. Polymers 1 to 4 also satisfy the above requirements (d) and (e).
On the other hand, Table 2 shows that Polymer 5 to Polymer 8 satisfy the above requirement (a) but do not satisfy the above requirement (b). That is, the polymers 5 to 8 correspond to the propylene-based polymer [B].

Next, using the various propylene-based polymers (polymers 1 to 8) obtained in Production Examples 1 to 8, a polypropylene-based resin composition and expanded polypropylene-based resin particles were produced. An example in which an in-mold molded body was manufactured using the method will be described.

Example 1
The polymer 1 (propylene polymer [A]) obtained in Production Example 1 and the polymer 5 (propylene polymer [B]) obtained in Production Example 5 were mixed at a ratio of 90:10 (weight ratio), and this mixture was used. Antioxidant (Yoshinox BHT, manufactured by Yoshitomi Pharmaceutical Co., Ltd., 0.05% by weight, and Ciba Geigy, product name "Irganox 1010," 0.10% by weight) was added to a 1 mm diameter strand using a 65 mmφ single screw extruder. After being extruded into a shape, cooled in a water tank, and cut into a length of 2 mm, fine pellets of a polypropylene resin composition were obtained.

ポ リ プ ロ ピ レ ン The DSC measurement of the polypropylene resin composition thus obtained showed one endothermic peak, and the peak temperature (melting point) was 153 ° C.

Next, using this polypropylene resin composition as a base resin, foamed polypropylene resin particles are produced as follows.
First, 1000 g of the polypropylene resin composition in the form of pellets was put into an autoclave having an internal volume of 5 liters together with 2500 g of water, 200 g of tribasic calcium phosphate and 0.2 g of sodium dodecylbenzenesulfonate, and 120 g of isobutane as the above foaming agent was added. After the temperature was raised to 140 ° C. for 60 minutes, it was kept at this temperature for 30 minutes.

Thereafter, the valve at the bottom of the autoclave was opened and the contents were discharged to the atmosphere while compressed nitrogen gas was externally added to maintain the pressure in the autoclave at a gauge pressure of 2.3 MPa.
Through the above operation, expanded polypropylene resin particles were obtained.
After drying the expanded polypropylene resin particles, the bulk density was measured and found to be 42 g / L. The foamed particles of the expanded polypropylene resin particles had a very uniform average diameter of 250 μm.

The average diameter of the expanded particles of the polypropylene resin is determined by observing a cross section of the expanded particles cut through a substantially central portion of a randomly selected expanded particle using a microscope or a microscopic photograph obtained by observing the cross section. The diameter (maximum length) of each bubble was measured for 50 bubbles randomly, and the average value was shown.

Next, an in-mold molded article is prepared using the expanded polypropylene resin particles as follows.
First, the foamed polypropylene resin particles obtained as described above were filled with a hopper using a compressed air while being sequentially compressed into a molding die made of aluminum. Thereafter, the mixture was heated and molded into a mold chamber through steam having a gauge pressure of 0.30 MPa (indicated as “molding vapor pressure” in the table below) to obtain an in-mold molded product.

This molded article in the mold had a density of 0.060 g / cm ³ (60 g / L), a length of 300 mm, a width of 300 mm, and a thickness of 50 mm, had few gaps on the surface, and had an excellent surface appearance without irregularities. In addition, the molded body was broken at the center of the molded body, and the fusion degree of the cross section was measured to be 90%.

(4) The degree of fusion was determined by dividing the molded body, visually measuring the number of particle fractures and the number of interparticle fractures in the cross section, and expressed as a ratio of the number of particle fractures to the total number of both.

Further, a test piece having a length of 50 mm, a width of 50 mm and a thickness of 25 mm was prepared from another molded body molded under the same molding conditions, and the specimen temperature was 23 ° C. and the compression speed was 10 mm / min in accordance with JIS K7220 (1999). When a compression test was carried out under the conditions, the stress at the time of 50% compression (same as at the time of 50% strain) was 7.5 kgf / cm ² . Further, using a test piece of the same size, the compression set was measured by the method described in JIS K6767 (1976), and it was 11%.

Also, a test piece having a length of 50 mm, a width of 50 mm and a thickness of 25 mm was prepared from another molded article formed under the same molding conditions, and the test specimen temperature was 23 ° C. and the compression speed was 10 mm / min in accordance with JIS K7220 (1999). A stress-strain diagram as shown in FIG. 1 is obtained by performing a compression test, and the amount of energy absorption per unit volume is obtained by the following equation (5). This is expressed in J (joules) / L (liter) units. The energy absorption of the molded article was calculated by converting to 276 J / L.
Energy absorption per unit volume (kgf / cm / cm ³ ) = Stress at 50% strain (kgf / cm ² ) × Energy absorption efficiency up to 50% strain × 0.5 (cm / cm) Equation (5)
The “energy absorption efficiency up to 50% strain” in the equation (5) is an area ratio represented by “area of OAB (area of hatched portion) / area of square OABC” in FIG. .
The results are shown in Table 3 below.

Examples 2 to 8 and Comparative Examples 1 to 5
Next, foamed polypropylene resin particles and in-mold molded articles were produced in the same manner as in Example 1 except that the composition of the polypropylene resin composition used as the base resin of the expanded polypropylene resin particles was changed.
As the base resin, a polypropylene-based resin composition prepared by blending “Polymer 1” to “Polymer 8” obtained in Production Examples 1 to 8 with the composition shown in Table 3 or Table 4 was used.
Except for the above, in the same manner as in Example 1, foamed polypropylene resin particles and in-mold molded articles were produced using the above-mentioned polypropylene resin composition, and these were evaluated.
The results are shown in Tables 3 and 4. The evaluation criteria for the appearance of the molded body in Tables 3 to 5 are as follows.
○ A molded product with small surface gaps and excellent surface appearance without irregularities.
Δ: A molded article with a slightly inferior surface appearance in which gaps on the surface are slightly recognized or surface irregularities are slightly recognized.
× A molded article having a poor surface appearance with many gaps on the surface or many irregularities on the surface.

Example 9
The polymer 3 (propylene polymer [A]) obtained in Production Example 3 and the polymer 5 (propylene polymer [B]) obtained in Production Example 5 were mixed at a weight ratio of 65:35. In the same manner as in Example 1, fine pellets of the polypropylene resin composition were obtained.

Next, using this polypropylene resin composition as a base resin, foamed polypropylene resin particles are produced as follows.
First, an autoclave having an internal volume of 400 L was prepared by adding 100 kg of a pellet-shaped polypropylene resin composition together with 220 L of water, 5 g of sodium dodecylbenzenesulfonate (surfactant), 300 g of kaolin (dispersant), and 10 g of powdered aluminum sulfate (dispersion enhancer). And sealed. Subsequently, carbon dioxide gas as a blowing agent was injected so that the internal pressure of the autoclave became 0.49 MPa (gauge pressure), and the temperature was raised to 162 ° C. while stirring.

Then, the temperature was maintained at that temperature for 15 minutes while injecting carbon dioxide gas until the internal pressure of the autoclave became 3.14 MPa (gauge pressure). Thereafter, one end of the autoclave was opened, and the contents of the autoclave were discharged under atmospheric pressure to obtain expanded particles. The discharge was performed while supplying nitrogen gas into the autoclave so that the pressure in the autoclave during discharge of the resin particles from the autoclave was maintained at the pressure in the autoclave immediately before release. After the obtained foamed particles were washed with water and centrifuged, they were allowed to cure under atmospheric pressure for 24 hours, and then the bulk density and the like of the foamed particles were measured.
The cell diameter of the obtained expanded particles was measured in the same manner as in Example 1. Table 5 shows the results.

Next, an in-mold molded article was prepared using the foamed polypropylene resin particles in the same manner as in Example 1, and the resulting molded article was subjected to surface appearance, degree of fusion, stress at 50% compression, and compression. Evaluation of permanent set, energy absorption, etc. was performed. Table 5 shows the results.

As can be seen from Tables 3 and 5, in Examples 1 to 9 according to the present invention, the foams of the foamed polypropylene resin particles were very uniform, and the in-mold molded articles using the same had low molding steam. Despite heating under pressure, the degree of fusion was high and the surface appearance was also excellent. Also, the mechanical properties were high in compressive strength (stress at 50% compression) and small in compression set.
Also, from a comparison between Example 8 using isobutane as a blowing agent and Example 9 using carbon dioxide, both obtained molded articles having the same density using the same composition. It can be seen that the molded article obtained in Example 9 was more excellent in energy absorption.

On the other hand, as shown in Table 4, when the polymer 1 obtained in the above Production Example 1 was used alone, the surface of the in-mold molded article molded using the obtained polypropylene-based resin expanded particles was used. It contained a part with a slightly inferior appearance and a defective part with a very poor appearance (Comparative Example 3).
When the polymer 5 obtained in Production Example 5 was used alone, the obtained expanded polypropylene resin particles had a large variation in air bubbles, and were molded in a mold using the expanded polypropylene resin particles. The body had a low degree of internal fusion, the surface appearance of the in-mold formed body was poor, and the compressive strength (stress at 50% compression) was insufficient (Comparative Example 4).

In Comparative Example 1 in which the polymer 7 and the polymer 5 were mixed, because the propylene polymer [A] was not contained, the obtained polypropylene-based resin expanded particles had large variations in cells. The in-mold molded article molded using the expanded polypropylene resin particles has a low degree of internal fusion, furthermore the surface appearance of the in-mold molded article is poor, and the compressive strength (stress at 50% compression) is low. Had a large compression set.
In Comparative Example 2 in which the polymer 8 and the polymer 5 were mixed, since the propylene polymer [A] was not contained, coarse bubbles were present in the obtained expanded polypropylene resin particles. The in-mold molded article molded using the expanded polypropylene resin particles had a slightly poor surface appearance and insufficient compressive strength (stress at 50% compression).

(4) Further, Comparative Example 5, which used Polymer 7 alone, did not contain the propylene polymer [A], so that the foamed polypropylene resin particles obtained had large variations in cells. The in-mold molded article molded using the expanded polypropylene resin particles had a slightly poor surface appearance and a large compression set relative to the compressive strength (stress at 50% compression).

Production Example 1 and Production Example 2 show examples in which a propylene homopolymer was produced using the same metallocene polymerization catalyst, but the properties of the obtained propylene homopolymer were different. The reason for this is based on the difference in polymerization temperature. That is, in Production Example 1 having a higher polymerization temperature, the proportion of each position irregular unit in the propylene homopolymer obtained is higher.
Further, Production Examples 5 and 6 show examples in which no regioregular units were formed in the obtained propylene-based polymer by using a Ziegler / Natta catalyst different from the metallocene-based polymerization catalyst.

Production Example 7 shows an example in which a propylene homopolymer is produced using a metallocene-based polymerization catalyst different from that of Production Example 1. However, under the conditions described in the known literature, the proportion of each position irregular unit is reduced. It can be seen that this is below the scope of the present invention. In Production Example 7, the polymerization temperature was 40 ° C., but when the polymerization temperature was increased to, for example, 70 ° C. or higher, the propylene homopolymer obtained had a position irregular unit within the range of the present invention. However, the [mm] fraction is expected to be lower than that of the propylene homopolymer of Production Example 7.
Production Example 8 shows an example in which a propylene homopolymer was produced using a metallocene polymerization catalyst different from Production Examples 1 and 7, and the metal complex component of the metallocene polymerization catalyst used was not suitable. Therefore, the proportion of each position irregular unit exceeded the range of the present invention.

FIG. 4 is a stress-strain diagram for explaining the energy absorption at 50% strain according to the first embodiment.

Claims (7)

5 to 95% by weight of the following propylene-based polymer [A] and 95 to 5% by weight of the following propylene-based polymer [B] (provided that the propylene-based polymer (A) and the propylene-based polymer [B] The total amount is 100% by weight).
Propylene-based polymer [A]: A propylene-based polymer having the following requirements (a) and (b).
(A) 100 to 85 mol% of structural units obtained from propylene, and 0 to 15 mol% of structural units obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms (provided that propylene is obtained from propylene) The total amount of the structural units and the structural units obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms is 100 mol%).
(B) the ratio of the position irregular units based on the 2,1-insertion of the propylene monomer units in the total propylene insertion is 0.5 to 2.0%, as measured by 13C-NMR, and the propylene monomer The ratio of the position irregular units based on the 1,3-insertion of the unit is 0.005 to 0.4%.
Propylene-based polymer [B]: A propylene-based polymer having only the requirement (a) among the requirements (a) and (b). 2. The polypropylene resin composition according to claim 1, wherein the propylene polymer [A] further has the following requirement (d).
(D) The isotactic triad fraction in the propylene unit chain portion composed of head-to-tail bonds, as measured by 13C-NMR, is 97% or more. 3. The polypropylene resin composition according to claim 1, wherein the propylene polymer [A] further has the following requirement (e).
(E) The melt flow rate is 0.5 to 100 g / 10 minutes. <4> The polypropylene resin composition according to any one of claims 1 to 3, wherein the polypropylene resin composition exhibits a substantially single melting peak as measured by a differential scanning calorimeter. (5) Foamed polypropylene resin particles containing the polypropylene resin composition according to any one of claims 1 to 4 as a base resin. 6. The expanded polypropylene resin particles according to claim 5, wherein the expanded polypropylene resin particles are expanded using a blowing agent satisfying the following requirement (f).
(F) When the critical temperature of the foaming agent is Tc [° C.], Tc satisfies the following expression (2).
-90 ° C ≦ Tc ≦ 400 ° C Equation (2) An in-mold molded article obtained by molding expanded polypropylene resin particles in a mold and having a density of 0.008 to 0.5 g / cm ³ .
7. A molded article in a mold, characterized in that the expanded polypropylene resin particles are formed by using the one according to claim 5 or 6.

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