JP2010077231A - Propylene-based block copolymer - Google Patents

Abstract

A propylene-based block copolymer having improved injection moldability and foaming characteristics and free from subsequent grade contamination by FE is provided.
A TREF curve obtained as a plot of elution amount (dwt% / dT) against temperature by a temperature rising elution fractionation method (TREF) in a temperature range of -15 ° C to 140 ° C using an o-dichlorobenzene solvent. Is a crystalline propylene-ethylene random copolymer component (A) that exhibits a high temperature side peak T (A) between 65 and 95 ° C., or a low temperature side peak T (B) that is 60 ° C. or lower or a peak. A propylene-based block copolymer comprising a low crystalline or amorphous propylene-ethylene random copolymer component (B) and obtained using a metallocene catalyst,
A propylene-based block copolymer or the like having an MFR of 150 g / 10 min or more and an MFR of a crystalline propylene-ethylene random copolymer component (A) of 200 g / 10 min or more.
[Selection figure] None

Description

  The present invention relates to a propylene-based block copolymer, and more particularly to a propylene-based block copolymer that is excellent in fluidity and injection foam moldability and is free from contamination by fish eyes.

As olefinic thermoplastic elastomers or plastomers, blends of polymer components such as random copolymers typified by ethylene-α-olefin copolymers are well known and have moderate flexibility and strength, and are recycled and incinerated. Because it is highly adaptable to environmental problems and is lightweight and excellent in moldability and economy, it is used in a wide range of fields such as films, sheets, fibers, nonwoven fabrics, various containers, molded products, and modifiers. ing.
Among such thermoplastic elastomers, what is called a block copolymer in which a polypropylene component is produced in the first step and a propylene-ethylene copolymer elastomer component is produced in the second step is compared with a random copolymer type elastomer. In addition, it has the characteristics of excellent heat resistance and productivity, and the product quality is stable and the production cost is reduced compared to the elastomer manufactured by mechanical mixing, and the elastomer composition is wide. Since it has advantageous features such as being variable, it has high economic efficiency, excellent heat resistance and strength, and has been widely used recently.

  In addition, it is required to shorten the molding cycle time in injection molding and the like to increase the production efficiency. However, in order to shorten the molding cycle time, the fluidity of the propylene block copolymer itself is increased, that is, with a high MFR. It is necessary to be. However, for the production of such a block copolymer, when a Ziegler-Natta catalyst is used in a multistage polymerization reaction, since there are multiple types of active sites, the crystallinity of the produced propylene-ethylene copolymer and Since the molecular weight distribution is wide and a large amount of low crystals and low molecular weight components are produced, the polymer powder is strongly sticky, and there is a drawback that problems easily occur in industrial production.

  High MFR can also be achieved by melt kneading with an organic peroxide. However, there is a problem that the manufacturing unit price increases due to the use of organic peroxides, and that the MFR change due to denaturing conditions is large (see, for example, Patent Document 1).

  As another method for increasing the MFR, there is a method of blending a high MFR ethylene / α-olefin random copolymer. However, in this method, if the mixing ratio of the high MFR ethylene / α-olefin random copolymer is increased, the physical properties of the polypropylene are impaired, so that it is difficult to obtain a high MFR polypropylene (see, for example, Patent Document 2). ).

  On the other hand, in automobile materials, large-sized household goods such as exterior materials, cushion materials, and refrigerators, weight reduction has been promoted, and foamed molded products are increasingly used. Injection foam molding has been developed and widely used for the production of these large moldings. As a method for producing a foam from a polypropylene resin, an extrusion foam molding in which a polypropylene resin containing a foaming agent is melted or a gas is injected into the melted polypropylene resin, and then extrusion molding is performed to form a foam sheet. There are many injection foam molding methods in which foaming is performed simultaneously with injection into an injection mold.

  A general thermoplastic elastomer injection foam molding method (see, for example, Patent Document 3) is known, but in order to improve the foamability of a non-crosslinked thermoplastic elastomer, the molding temperature range is low. Because it is necessary to maintain the gas pressure, it must be viscous. In this way, the performance of polypropylene resin required for injection foam molding requires fluidity, melt tension, and foamability, but the performance of fluidity, melt tension, and foamability are contradictory. There are many. Therefore, a polypropylene resin homopolymer required for injection foam molding suitable for large-scale molding of automobile materials, especially instrument panels and door trims, etc., is required for injection foam molding because it must have a high MFR. High viscosity and melt tension cannot be obtained. Therefore, there is a problem that sufficient foaming performance cannot be obtained.

In addition to these methods, propylene is polymerized on a supported titanium-containing solid catalyst component and an organoaluminum compound catalyst component using a prepolymerized catalyst in which polyethylene and a polyene compound are prepolymerized, thereby increasing the high melt tension. And a polyethylene-containing prepolymerization catalyst having an intrinsic viscosity of 20 dl / g or more obtained by conducting prepolymerization alone with ethylene using the same catalyst component (for example, see Patent Document 4) In addition, a method for producing an ethylene / α-olefin copolymer having high melt tension is known (for example, see Patent Document 5).
However, in these methods, it is necessary to newly prepare a polyene compound as the third component, and as a result, the dispersibility of prepolymerized polyethylene or the like in the finally obtained polyolefin composition becomes nonuniform. There is a problem that eye (hereinafter also referred to as FE) is likely to occur, and the quality of the polyolefin composition tends to become unstable.

  In addition, an olefin (co) polymer composition having a high melt tension obtained by polymerizing propylene using a polyethylene-containing prepolymerization catalyst containing polyethylene having an intrinsic viscosity of 15 dl / g or more, and a method for producing the same Are known. However, even in this method, FE is likely to occur during the production of subsequent grades due to the residual of the prepolymerized polyethylene. Therefore, when the production grade is switched, a large amount of transition products are generated, and the production efficiency deteriorates. (For example, refer to Patent Documents 6 and 7.)

  In addition, as another method for improving melt viscoelasticity such as melt tension, there is a method in which a composition containing polyethylene or polypropylene having a different intrinsic viscosity or molecular weight from polypropylene is blended or produced by multistage polymerization. Proposed. For example, a technique has been proposed in which 2 to 30 parts by weight of ultrahigh molecular weight polypropylene is added to 100 parts by weight of normal polypropylene in the polymerization stage. However, these compositions have not yet reached a sufficiently satisfactory injection moldability and foaming characteristics. In addition, in order to produce such ultra-high molecular weight polypropylene contained in the composition, it is actually the case that productivity must be reduced by this, and FE due to ultra-high molecular weight polypropylene is likely to occur (for example, (See Patent Documents 8 and 9).

In recent years, metallocene catalyst technology has advanced. Polypropylene produced using a metallocene catalyst has crystallinity, narrow molecular weight distribution, and low crystallinity and low molecular weight components. Therefore, when the MFR is made high like a polymer powder produced with a Ziegler-Natta catalyst, the low molecular weight component does not increase, so that there is no deterioration in productivity due to stickiness. Actually, a production example of high MFR polypropylene using a metallocene catalyst is disclosed (see Patent Document 10).
However, in this example, since it is a one-stage polymerized product of propylene and there is no molecular weight disparity, foaming characteristics are insufficient.
JP 2000-72820 A JP 2001-1114957 A JP-A-8-207074 Japanese Patent No. 3176932 Japanese Patent Laid-Open No. 5-222122 JP-A-4-55410 Japanese Patent No. 3270056 JP 2001-59949 A JP 2002-90333 A International Publication (WO) Pamphlet of 2007/045603

  An object of the present invention is to provide a propylene-based block copolymer which has improved injection moldability and foaming characteristics and is free from subsequent grade contamination by FE in view of the above-described conventional technology.

  As a result of various studies to solve such problems, the present inventors have not clarified the reason, but propylene-ethylene obtained by a metallocene catalyst having a high crystallization speed and a uniform crystal structure. The present inventors have found that random copolymers are excellent in foaming characteristics. Furthermore, in the presence of the metallocene catalyst, all the multistage polymerization steps are carried out by gas phase polymerization, and in the first step, a crystalline propylene-ethylene random copolymer having an MFR of 200 or more is produced and continuously reduced in the second step. It was found that by producing an amorphous propylene-ethylene random copolymer of MFR, a propylene-based block copolymer with improved injection moldability and foaming characteristics can be produced industrially and stably. Based on the above, the present invention has been completed.

  That is, according to the first invention of the present invention, the amount of elution (dwt% / wt) with respect to the temperature by the temperature rising elution fractionation method (TREF) in the temperature range of -15 ° C to 140 ° C using an o-dichlorobenzene solvent dT), a TREF curve obtained as a plot of crystalline propylene-ethylene random copolymer component (A) showing a high temperature side peak T (A) between 65 and 95 ° C., and a low temperature side at 60 ° C. or lower. A propylene-based block copolymer comprising a low crystalline or amorphous propylene-ethylene random copolymer component (B) that exhibits or does not exhibit a peak T (B), and is obtained using a metallocene catalyst MFR (temperature 230 ° C., load 2.16 kg) is 150 g / 10 min or more, and MFR of crystalline propylene-ethylene random copolymer component (A) ( Degrees 230 ° C., load 2.16 kg) propylene-based block copolymer is provided which is characterized in that it is 200 g / 10 minutes or more.

According to the second aspect of the present invention, in the first aspect, the proportion of the crystalline propylene-ethylene random copolymer component (A) is 30 to 90% by mass, and the low crystalline or amorphous propylene- A propylene-based block copolymer is provided in which the proportion of the ethylene random copolymer component (B) is 10 to 70% by mass.
According to the third invention of the present invention, in the first or second invention, after producing the crystalline propylene-ethylene random copolymer component (A), the crystalline propylene-ethylene random copolymer component A propylene-based block copolymer is provided in which the low crystalline or amorphous propylene-ethylene random copolymer component (B) is subsequently produced in the presence of (A).
Furthermore, according to the fourth aspect of the present invention, there is provided a propylene-based block copolymer produced in any one of the first to third aspects by gas phase polymerization.

  The propylene-based block copolymer of the present invention is excellent in fluidity and injection foam moldability, and has an effect that the generation of fish eyes is less after grade switching.

The present invention is a propylene-based block copolymer obtained by a method for producing a propylene-based block copolymer by multistage polymerization comprising a first step and a second step using a metallocene catalyst, preferably the first step, In both the second step, the crystalline propylene-ethylene random copolymer component (A), which uses a gas phase polymerization method and has an MFR of 200 g / 10 min or more in the first step, is preferably the propylene-based block copolymer. In the second step, the low-crystalline or amorphous propylene-ethylene random copolymer component (B) is preferably added to the propylene-based block copolymer in an amount corresponding to 30 to 90% by mass. This is a propylene-based block copolymer produced so as to correspond to 70% by mass.
Hereinafter, the contents will be described in detail.

I. Features of Propylene-Based Block Copolymer Produced The propylene-based block copolymer of the present invention is based on multi-stage polymerization including a first step and a second step using a metallocene catalyst, and has an MFR (temperature 230 ° C., Elution amount (dwt% / dT) with respect to temperature by temperature rising elution fractionation method (TREF) in a temperature range of −15 ° C. to 140 ° C. using a o-dichlorobenzene solvent at a load of 2.16 kg) over 200 g / 10 min. The TREF curve obtained as a plot of) shows a crystalline component (A) showing a high-temperature side peak T (A) between 65 and 88 ° C., preferably 30 to 90% by mass of the propylene-based block copolymer, More preferably, it is formed so as to correspond to 40 to 60% by mass, and in the second step, the ethylene content is higher than that of the component (A), and the TREF has a low temperature side of 60 ° C. The low-crystalline or non-crystalline propylene-ethylene copolymer component (B) that exhibits or exhibits no peak T (B) is preferably 10 to 70% by mass of the propylene-based block copolymer, more preferably Is characterized by being produced so as to correspond to 40 to 60% by mass.

The ethylene content component of the propylene-ethylene random copolymer component (A) produced in the first step is preferably 1% by mass to 10% by mass, more preferably 1% by mass to 5% by mass, When the ethylene content is significantly lower than the above range, the reaction rate of the propylene-ethylene random copolymer is lowered, and thus the productivity is lowered. If the ethylene content is significantly higher than the above range, the propylene-based block copolymer itself may partially melt at an industrially possible polymerization temperature, making it difficult to maintain stable operation.
At that time, the value of the gas concentration molar ratio (ethylene / propylene) of ethylene and propylene in the first reactor may be adjusted so as to obtain the above ethylene content, preferably 0.01 to 0.5. More preferably, it is 0.01 to 0.3, and particularly preferably 0.02 to 0.2.
The MFR (temperature 230 ° C., load 2.16 kg) of the component (A) is preferably 200 g / 10 min or more and 3000 g / 10 min or less. If the MFR is smaller than the above range, the molecular weight disparity becomes small, and it becomes difficult to achieve both fluidity and foaming performance. On the other hand, if the MFR is larger than the above range, the powder strength is remarkably lowered, the powder is crushed and a large amount of fine powder is generated, which hinders industrial stable operation.

  The ratio of the component (A) generated in the first step and the component (B) generated in the second step is usually 30 to 90/70 to 10, preferably 30 to 65/70 to 35, by mass ratio. More preferably, it is 30-60 / 70-40, Most preferably, it is 40-60 / 60-40. If the proportion of the component (A) is more than 90% by mass, the present block copolymer having the desired physical properties is difficult to obtain due to insufficient flexibility, and the proportion of the component (B) is 70%. When the amount is more than mass%, the powder properties of the block copolymer are deteriorated, which may hinder industrial stable operation.

The ethylene content in the component (B) produced in the second step is set higher than the ethylene content in the component (A) produced in the first step. In the present block copolymer, the lower the crystallinity of the component (B) relative to the component (A), the greater the flexibility improvement effect. The crystallinity is the ethylene content in the propylene-ethylene random copolymer component. It is controlled by.
[E] gap ([E] B- [E] A), which is the difference between the ethylene content [E] B in component (B) and the ethylene content [E] A in component (A), is It can be arbitrarily set depending on the use of the polymer. [E] When the gap is small, specifically, when it is less than 12% by mass, the present block copolymer is excellent in transparency. On the other hand, when this difference is large, specifically, when the content is 12 to 20% by mass, the present block copolymer is excellent in impact resistance and whitening resistance.

The MFR (temperature 230 ° C., load 2.16 kg) of the component (B) is preferably 0.1 g / 10 min or more and 10 g / 10 min or less. When the amount is less than the above range, the reaction rate of the propylene-ethylene random copolymer is remarkably reduced, so that productivity is deteriorated. Moreover, when it becomes more than said range, a component (B) will become a sticky component and will deteriorate powder fluidity remarkably.
Furthermore, it is preferable that the gas concentration molar ratio (ethylene / propylene) of ethylene and propylene in the second reactor is set higher than the gas concentration molar ratio of ethylene and propylene in the first reactor. Although a specific value is set according to the index of this block copolymer, Preferably it is the range of 0.2-2.0.

The ratio of component (A) to component (B) and their ethylene content are measured using TREF (temperature rising elution fractionation method) as follows. First, using the difference in crystallinity between the component (A) and the component (B), a temperature T (C) for dividing the components (A) and (B) is determined from the elution curve obtained by TREF measurement, and T The proportion of the component eluted until (C) is regarded as the proportion of component (B), and the proportion of the component eluted at T (C) or higher is regarded as the proportion of component (A).
The technique for evaluating the crystallinity distribution of a propylene-ethylene random copolymer by TREF measurement is well known to those skilled in the art. Glokner, J. et al. Appl. Polym. Sci: Appl. Poly. Symp. 45, 1-24 (1990), L .; Wild, Adv. Polym. Sci. 98, 1-47 (1990), J .; B. P. Soares, A .; E. A detailed measurement method is shown in Hamielec, Polymer; 36, 8, 1639-1654 (1995) and the like.

  In the present invention, the measurement is specifically performed as follows. A sample is dissolved in o-dichlorobenzene (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, o-dichlorobenzene (containing 0.5 mg / ml BHT) as a solvent is passed through the column at a flow rate of 1 ml / min, and the components dissolved in o-dichlorobenzene at −15 ° C. are eluted in the TREF column for 10 minutes. Next, the column is linearly heated to 140 ° C. at a temperature rising rate of 100 ° C./hour to obtain an elution curve.

  The crystallinity of a component having a low elution temperature is low and rich in flexibility. On the other hand, the crystallinity of a component having a high elution temperature is increased, thereby increasing rigidity and improving heat resistance. In the elution curve (dwt% / dT curve with respect to temperature) of the propylene-based block copolymer in the present invention, the crystalline propylene-ethylene random copolymer component (A) and low crystalline or amorphous The propylene-ethylene copolymer component (B) is observed as a component eluting at different temperatures due to the difference in crystallinity. That is, component (A) is observed on the high temperature side due to high crystallinity, while component (B) is observed on the low temperature side due to low crystallinity or amorphousness, or has a peak within the TREF measurement temperature. Not shown. When each peak temperature is T (A) and T (B) (if the peak is not shown, the lower limit of the measurement temperature is −15 ° C.), the temperature T (C) between the two peaks ({T (A) In + T (B)} / 2), both components are almost separable.

  At this time, the integrated amount of the component that elutes by T (C) in TREF is defined as W (B) mass%, and the integrated amount of the component that elutes at T (C) or higher is defined as W (A) mass%. W (B) substantially corresponds to the amount of the low crystalline or amorphous component (B), and W (A) substantially corresponds to the amount of the highly crystalline component (A). .

  Next, it fractionates into T (C) soluble component = component (B) and T (C) insoluble component = component (A) by a temperature rising column fractionation method using a preparative type separation apparatus. A specific method of fractionation is based on T (C) obtained by TREF measurement, and by using a preparative type fractionation apparatus, T (C) soluble component = component (B) and T (C ) Insoluble component = Component (A) is fractionated, and the ethylene content of each component is determined by NMR. The temperature rising column fractionation method refers to a measurement method disclosed in, for example, Macromolecules, 21, 314-319 (1988).

As the separation conditions, a glass bead carrier (80 to 100 mesh) is packed in a cylindrical column having a diameter of 50 mm and a height of 500 mm, and maintained at 140 ° C. Next, 200 ml of a sample o-dichlorobenzene 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 T (C) o-dichlorobenzene is allowed to flow at a flow rate of 20 ml / min, so that T (C) -soluble components present in the column can be obtained. Elute and collect.
Next, the column temperature is increased to 140 ° C. at a rate of temperature increase of 10 ° C./min, left at 140 ° C. for 1 hour, and then 800 ml of o-dichlorobenzene as a solvent at 140 ° C. is flowed at a flow rate of 20 ml / min. , And eluting and recovering insoluble components at T (C).
The polymer-containing solution 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 collected by filtration and dried overnight in a vacuum dryer.

The ethylene content of each fractionated component is determined by NMR. A specific method is shown below.
・ Measurement of ethylene content by NMR:
The ethylene content of each of the component (A) and the component (B) obtained by the above fractionation is determined by analyzing a ¹³ C-NMR spectrum measured according to the following conditions by a proton complete decoupling method.
-Model: GSX-400 manufactured by JEOL Ltd. or equivalent equipment (carbon nuclear resonance frequency of 100 MHz or more)
Solvent: o-dichlorobenzene: heavy benzene = 4: 1 (volume ratio)
・ Concentration: 100 mg / ml
・ Temperature: 130 ℃
・ Pulse angle: 90 °
・ Pulse interval: 15 seconds ・ Number of integration: 5,000 times or more The attribution of the spectrum may be performed with reference to, for example, Macromolecules, 17, 1950 (1984). The attribution of spectra measured under the above conditions is as shown in Table 1 below. In the table S is the symbol such as _{alpha alpha} Carman et al (Macromolecules, 10,536 (1977)) in accordance with notation, P is represented each methyl carbon, S is methylene carbon, T is a methine carbon.

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 (T _ββ ) (1)
[PPE] = k × I (T _βδ ) (2)
[EPE] = k × I (T _δδ ) (3)
[PEP] = k × I (S _ββ ) (4)
[PEE] = k × I (S _βδ ) (5)
[EEE] = k × {I (S _δδ ) / 2 + I (S _γδ ) / 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)
It is. Further, k is a constant, I indicates the spectral intensity, and for example, I (T _ββ ) means the intensity of the peak at 28.7 ppm attributed to T _ββ .
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
In addition, the [propylene random copolymer component] of 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. However, it is difficult to completely separate and identify the peaks derived from heterogeneous bonds, and the amount of heterogeneous bonds is small. Therefore, the ethylene content of the present invention is determined using 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. We will ask for it.
The conversion of the ethylene content from mol% to mass% is performed using the following formula.
Ethylene content (mass%) = (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 block copolymer is calculated from the ethylene contents [E] A, [E] B, and TREF of the components (A) and (B) measured above. From the mass ratios W (A) and W (B) [wt%] of the components, the following formula is used.
[E] W = [E] A × W (A) / 100 + [E] B × W (B) / 100 (wt%)

II. Production of propylene-based block copolymer Catalyst The production of the propylene-based block copolymer of the present invention requires the use of a metallocene catalyst. The catalyst system required for producing the propylene-based block copolymer is not particularly limited as long as it is a metallocene catalyst. Among them, the metallocene catalyst system that is preferably used includes (a) a conjugated five member It is composed of a metallocene complex composed of a transition metal compound of Group 4 of the periodic table having a ring ligand, (b) a cocatalyst for activating it, and (c) an organoaluminum compound used as necessary. Things can be mentioned. Depending on the characteristics of the olefin polymerization process, when particle formation is essential, (d) a support can be added as a constituent element to the metallocene catalyst system. Hereinafter, (a) to (d) will be described.

(1) Metallocene complex (a)
A typical example of the metallocene complex used in the present invention is a metallocene complex of a Group 4 transition metal compound having a conjugated five-membered ring ligand, and one of the following general formulas. The thing represented by these is preferable.

（式中、ＡおよびＡ’は置換基を有していてもよいシクロペンタジエニル基、Ｑは二つの共役五員環配位子間を任意の位置で架橋する結合性基、Ｍは周期律表第４族から選ばれる遷移金属、ＸおよびＹは補助配位子である）

(In the formula, A and A ′ are cyclopentadienyl groups which may have a substituent, Q is a binding group that bridges between two conjugated five-membered ring ligands at an arbitrary position, and M is a period. (Transition metals selected from group 4 of the table, X and Y are auxiliary ligands)

In the above general formula, when the cyclopentadienyl group has a substituent, examples of the substituent include hydrocarbon groups having 1 to 30 carbon atoms (including heteroatoms such as halogen, silicon, oxygen, and sulfur). This hydrocarbon group may be bonded to the cyclopentadienyl group as a monovalent group, or when there are a plurality of these groups, two of them are each at the other end (ω-end). ) May form a ring together with a part of cyclopentadienyl. Other examples of this substituent include an indenyl group, a fluorenyl group, or an azulenyl group, and these groups may further have a substituent on the side ring, and among them, an indenyl group or an azulenyl group. Is preferred.
Q is preferably a methylene group, an ethylene group, a silylene group, a germylene group, a group in which these are substituted with a hydrocarbon group, or a silafluorene group.
M is preferably titanium, zirconium or hafnium. In particular, zirconium and hafnium are preferable.
The auxiliary ligands X and Y react with the component (b) to produce an active metallocene having an olefin polymerization ability. Therefore, as long as this purpose is achieved, X and Y are The type is not limited, and examples thereof include a hydrogen atom, a halogen atom, a hydrocarbon group, or a hydrocarbon group that may have a hetero atom. Among these, a hydrocarbon group having 1 to 10 carbon atoms or a halogen atom is preferable.

(2) Cocatalyst (activator component) (b)
The cocatalyst is a component that activates the metallocene complex, and is a compound that can react with the auxiliary ligand of the metallocene complex to convert the complex into an active species having an olefin polymerization ability. Specifically, (b- 1) an aluminum oxy compound, (b-2) an ionic compound or Lewis acid capable of reacting with component (a) to convert component (a) into a cation, (b-3) a solid acid, (b- 4) Ion exchange layered silicate and the like.
Hereinafter, (b-1) to (b-4) will be described.

(B-1) Aluminum oxy compound:
It is well known that an aluminum oxy compound can activate a metallocene complex, and specific examples of the compound include those represented by the following general formulas.

In each of the above general formulas, R ₁ represents a hydrogen atom or a hydrocarbon residue, preferably a hydrocarbon residue having 1 to 10 carbon atoms, particularly preferably 1 to 6 carbon atoms. Moreover, several R < ₁ > may be same or different, respectively. P represents an integer of 0 to 40, preferably 2 to 30.
Among the general formulas, the compounds represented by the first and second formulas are compounds also referred to as aluminoxanes. Among these, methylaluminoxane or methylisobutylaluminoxane is preferable. The above aluminoxanes can be used in combination within a group and between groups. And said aluminoxane can be prepared on well-known various conditions.
The compound represented by the third general formula is 10: 1 of one type of trialkylaluminum or two or more types of trialkylaluminum and an alkylboronic acid represented by the general formula: R ₂ B (OH) _2. It can be obtained by a reaction of ˜1: 1 (molar ratio). In the general formula, R ₁ and R ₂ represent a hydrocarbon residue having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms.

(B-2): an ionic compound or Lewis acid capable of reacting with component (a) to convert component (a) to a cation:
The compound (b-2) is an ionic compound or a Lewis acid capable of reacting with the component (a) to convert the component (a) into a cation, and examples of such ionic compound include carbonium. Examples thereof include complexes of cations such as cations and ammonium cations with organic boron compounds such as triphenylboron, tris (3,5-difluorophenyl) boron and tris (pentafluorophenyl) boron.
Examples of the Lewis acid as described above include various organic boron compounds such as tris (pentafluorophenyl) boron. Alternatively, metal halogen compounds such as aluminum chloride and magnesium chloride are exemplified.
In addition, a certain thing of said Lewis acid can also be grasped | ascertained as an ionic compound which can react with a component (a) and can convert a component (a) into a cation. Examples of the metallocene catalyst using the non-coordinating boron compound described above are disclosed in JP-A-3-234709 and JP-A-5-247128.

(B-3) Solid acid:
Examples of the solid acid include alumina, silica-alumina, silica-magnesia and the like.

(B-4) Ion exchange layered compound:
The ion exchange layered compound occupies most of the clay mineral, and is preferably an ion exchange layered silicate.
An ion-exchange layered silicate (hereinafter, sometimes simply referred to as “silicate”) has a crystal structure in which surfaces formed by ionic bonds and the like are stacked in parallel with each other and have a binding force. Refers to a silicate compound in which the ions to be exchanged are exchangeable. Most silicates are naturally produced mainly as a main component of clay minerals, and therefore often contain impurities (quartz, cristobalite, etc.) other than ion-exchangeable layered silicates. You may go out. Various known silicates can be used. Specific examples include the following layered silicates described in Haruo Shiramizu “Clay Mineralogy” Asakura Shoten (1995).

(I) 2: 1 type minerals Smectite group such as montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, stevensite, etc .; vermiculite group such as vermiculite; mica such as mica, illite, sericite, sea chlorite Pylophilite-talc group such as pyrophyllite and talc; Chlorite group such as Mg chlorite.

(Ii) 2: 1 ribbon type minerals Sepiolite, palygorskite and the like.

The silicate used as a raw material in the present invention may be a layered silicate in which the above mixed layer is formed. In the present invention, the main component silicate is preferably a silicate having a 2: 1 type structure, more preferably a smectite group, and particularly preferably montmorillonite.
As the silicate used in the present invention, those obtained as natural products or industrial raw materials can be used as they are without any particular treatment, but chemical treatment is preferred. Specifically, acid treatment, alkali treatment, salt treatment, organic matter treatment and the like can be mentioned. These processes may be used in combination with each other. In the present invention, these treatment conditions are not particularly limited, and known conditions can be used.
Moreover, since these ion-exchange layered silicates usually contain adsorbed water and interlayer water, it is preferable to use them after removing moisture by heat dehydration under an inert gas flow.

(3) Organoaluminum compound (c)
As the organoaluminum compound used in the metallocene catalyst system as necessary, those containing no halogen are used in the present invention, specifically, the general formula:
AlR _3-i X _i
(In the formula, R is a hydrocarbon group having 1 to 20 carbon atoms, X is hydrogen or an alkoxy group, and i is a number of 0 <i ≦ 3. However, when X is hydrogen, i is 0 <i <. 3)
The compound shown by is used.

  Specific compounds include trialkylaluminum such as trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum and trioctylaluminum, or diethylaluminum methoxide, diethylaluminum methoxide, diisobutylaluminum methoxide, diisobutylaluminum ethoxide and the like. A halide-containing alkylaluminum such as an alkoxy-containing alkylaluminum or diethylaluminum halide. Of these, trialkylaluminum is particularly preferred. More preferred are triisobutylaluminum and trioctylaluminum.

(4) Carrier (d)
The propylene-based block copolymer in the present invention is characterized by a high content of the component (B) produced in the second step. In order to stably produce such a polymer, a catalyst carrier is used. It is preferable to use the supported catalyst used. As the catalyst carrier, known ones can be used, but preferred carriers include inorganic compound carriers such as silica, titania, alumina, silica-alumina, silica-magnesia, ion-exchange layered silicate, polypropylene powder, polyethylene powder, etc. The polymer carrier can be mentioned.
Among these, in order to adjust the shape of the polymer particles and increase the particle size, it is particularly preferable to use a supported catalyst having a controlled particle shape and particle size. As a method for producing such a supported catalyst having a controlled particle shape and particle size, for example, when an inorganic compound carrier is used, the following examples can be given.

  The particle diameter of the raw material inorganic compound carrier is usually 0.01 to 5 μm in average particle diameter, and the particle fraction of less than 1 μm is 10% or more, preferably the average particle diameter is 0.1 to 3 μm, The particle fraction of less than 1 μm is preferably 40% or more. As a method of obtaining inorganic compound carrier particles having such a particle size, a dry fine particle formation method, for example, a fine particle formation by a jet mill, a ball mill, a vibration mill or the like, or a wet grinding method, polytron, etc. There are methods such as pulverization by forced stirring, dyno mill, pearl mill and the like.

Further, the carrier may be granulated to a preferred particle size, and the granulation method includes, for example, stirring granulation method, spray granulation method, rolling granulation method, briquetting, fluidized bed granulation Method and submerged granulation method. A preferable granulation method is a stirring granulation method, a spray granulation method, a rolling granulation method or a fluidized granulation method, and more preferably a spray granulation method. The particle strength will be described later, but it can also be controlled in this granulation step. In order to obtain a preferred range of crushing strength, it is preferable to use an inorganic compound carrier having a particle size distribution as described above.
Further, the granulation methods in the case of granulating in multiple stages may be combined, and the combination is not limited, but preferably, the spray granulation method and the spray granulation method, the spray granulation method and the rolling method. A combination of a granulation method, a spray granulation method and a fluidized granulation method may be mentioned.

2. Use amount of catalyst component In the above catalyst component, the use amounts of component (a) and component (b) are used in an optimum amount ratio in each combination.
When component (b) is an aluminum oxy compound, the molar ratio of Al / transition metal is usually from 10 to 100,000, more preferably from 100 to 20,000, and particularly from 100 to 10,000. On the other hand, when an ionic compound or Lewis acid is used as the component (b), the molar ratio of the transition metal to the transition metal is usually 0.1 to 1000, preferably 0.5 to 100, more preferably 1 to 50. It is.
When a solid acid or ion-exchange layered silicate is used as component (b), the amount of transition metal complex is usually 0.001 to 10 mmol, preferably 0.001 to 1 mmol per 1 g of component (b). Range.
These use ratios are examples of general ratios, and are not limited to the above-described use ratio ranges as long as the catalyst is suitable.

  The catalyst used in the present invention is made by supporting a polyolefin production catalyst comprising a transition metal complex and a co-catalyst as a catalyst for olefin polymerization (main polymerization), if necessary, after being supported on a carrier, ethylene, propylene, Even if a prepolymerization treatment for preliminarily polymerizing a small amount of olefins such as 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-butene, vinylcycloalkane, and styrene is performed. Good. A known method can be used as the prepolymerization method.

3. Polymerization reaction The propylene-based block copolymer production method of the present invention is preferably a propylene-ethylene random copolymer component component (A) having a melting peak temperature Tm by differential scanning calorimetry (DSC) of 105 to 140 ° C. The first step of polymerizing the block copolymer in an amount corresponding to 30 to 90% by mass of the block copolymer, and the propylene-ethylene copolymer component component (B) having an ethylene content higher than the ethylene content of the component (A) in the main block And a second step of polymerizing an amount corresponding to 70 to 10% by mass of the copolymer.

  In each step, it is essential to use a gas phase polymerization method. When the first step is carried out by so-called slurry polymerization in which polymerization is carried out in a partially inert solvent, a polymer having a relatively low melting point such as component (A) increases the amount of components eluted into the solvent. Therefore, stable production becomes difficult, and operations such as separation and recovery of the eluted components are required, which increases the production cost and is not suitable for industrial production. In addition, if the first step part is carried out by so-called bulk polymerization in which polymerization is performed in liquid propylene, there is a concern that the polymer may be dissolved during the production of the low melting point polymer, so that the polymerization temperature cannot be raised to an industrial level. Furthermore, since it is difficult to control the activity in bulk polymerization, the catalyst efficiency in the first step becomes too high, and the proportion of the component (B) produced in the second step as the object of the present invention is high. There is also a risk that the production of the propylene-based block copolymer becomes impossible. Therefore, in the present invention, the first step is performed by gas phase polymerization.

  On the other hand, regarding the second step, in general, when producing a propylene-based block copolymer, the propylene-ethylene random copolymer component produced in the second step is often a rubber component, such as a solvent. The gas phase polymerization method is used because it dissolves in the presence of a liquid, and the gas phase polymerization method is particularly recommended for producing a polymer having a large proportion of the component (B) produced in the second step.

  In addition, as the polymerization method, either a batch method or a continuous method can be adopted for each of the preceding step and the following step, but from the viewpoint of industrial production in consideration of manufacturing costs, the reactor for the first step is used. A continuous method in which the catalyst is continuously or intermittently introduced, the polymer is continuously or intermittently transferred from the first step to the second step, and the polymer is continuously or intermittently extracted from the second step. It is preferable to adopt it. In the present invention, two-stage polymerization comprising a first step and a second step is performed, but in some cases, each step can be further divided. In particular, a method for improving the physical properties is to divide the second step into two or more stages to produce various types of rubber components.

(1) Production of component (A) In the first step, a metallocene catalyst, preferably propylene using a catalyst comprising the components (a), (b), if necessary, (c), (d) as described above, is used. -Producing an ethylene random copolymer component. That is, the propylene-ethylene random copolymer component is single-staged or multi-staged, and is 30 to 90% by mass, preferably 30 to 65% by mass, and more preferably 30 to 60% by mass of the total polymerization amount (total of the propylene block copolymer). It is a process of generating so as to correspond to mass%, most preferably 40 to 60 mass%. The ethylene content in the first step is adjusted so that the melting point of the propylene-ethylene random copolymer component produced in the step is preferably 105 to 140 ° C. Generally, it is often in the range of 1 to 10% by mass with respect to all monomers (total of propylene and ethylene).

  When the polymerization temperature in the first step is higher than 90 ° C., the properties of the propylene-ethylene random copolymer component to be polymerized deteriorate and stable operation cannot be performed. On the other hand, when the temperature is lower than 50 ° C., the polymerization temperature becomes too low, and it becomes difficult to secure a cooling water temperature for heat removal, which is below the temperature range in which industrial production is allowed. From such a viewpoint, the polymerization temperature in the first step is desirably higher than 50 ° C.

  The polymerization pressure needs to be set in consideration of the polymerization activity from the catalyst performance in the gas phase polymerization. On the other hand, it must be set within a range where propylene is not liquefied within the above polymerization temperature range. In consideration of the above, the sum of the partial pressures of monomers related to polymerization, specifically, propylene and ethylene, is usually 0.1 to 4.5 MPa, preferably 0.5 to 4 MPa, more preferably 1 It is better to select in the range of ~ 3.5 MPa.

In the reactor, in addition to the above-mentioned monomers, so-called inert gas such as nitrogen, propane, n-butane and isobutane which are not directly related to the reaction may be present.
Moreover, it is preferable to use a molecular weight regulator so that the fluidity of the polymer is appropriate, and hydrogen is preferred as the regulator. The MFR that achieves both fluidity and foam moldability is selected in the range of 200 to 3000 g / 10 minutes, preferably 1000 to 3000 g / 10 minutes, and more preferably 1500 to 2500 g / 10 minutes. The total pressure of the polymerization reactor is the sum of the partial pressures of hydrogen and the like when using monomers (propylene, ethylene), inert gas (nitrogen, propane, etc.), and hydrogen as a molecular weight regulator. Although the value varies depending on the situation, it is preferably 0.5 to 6 MPa, more preferably 0.5 to 5 MPa, considering the pressure resistance design of the reactor from the viewpoint of industrial production.

(2) Production of Component (B) In the second step of the present invention, a propylene-ethylene copolymer having an ethylene content higher than the ethylene content in the propylene-ethylene random copolymer component produced in the first step. The components are single-stage or multi-stage, and are 70 to 10% by mass, preferably 70 to 35% by mass, more preferably 70 to 40% by mass, and most preferably 60 to 40% by mass of the total polymerization amount (total of the propylene-based block copolymer). It is the process of producing | generating so that it may correspond to 40 mass%.

The polymerization temperature in the second step is usually about 30 to 100 ° C, preferably about 50 to 80 ° C. Since the melting point in the propylene-ethylene random copolymer component produced in the first step is low and the propylene-α-olefin copolymer component produced in the second step is a rubber component or a component close thereto, polymerization is performed. If the temperature is too high, stable production cannot be achieved due to the deterioration of the powder properties. The polymerization pressure in the second step is usually 0.1 to 5 MPa, preferably 0.5 to 3 MPa.
In the range up to about 90 ° C., the polymerization temperature in the second step tends to be as high as possible from an industrial viewpoint, for example, from the viewpoint of ease of heat removal, catalytic activity, etc. The difference from the melting point becomes small, and it becomes difficult to continue stable operation, for example, the polymer melts at a local hot spot.

  During the polymerization in the second step, an electron-donating compound such as an active hydrogen-containing compound, a nitrogen-containing compound, or an oxygen-containing compound may be present. Moreover, it is preferable to use a molecular weight regulator so that the fluidity of the polymer is appropriate, and hydrogen is preferred as the regulator.

  The MFR of the propylene-ethylene copolymer component in the second step, which achieves both fluidity and injection foam moldability, is usually 0.001 to 100 g / 10 min, preferably 0.01 to 50 g / 10 min, more preferably 0.8. 1 to 10 g / 10 min. Although depending on the use of the present block copolymer, if the polymer MFR produced in the second step is extremely high, a low molecular weight component that causes stickiness is produced, resulting in trouble in operation.

As described above, in the present invention, the ratio of the component (B) produced in the second step is very high, and for the purpose of ensuring the properties of the produced polymer powder, a large particle size is used as a catalyst. It is preferred to use a catalyst. On the other hand, the gas phase polymerization process is roughly divided into a process with mechanical stirring and a state in which the polymer phase forms a fluidized bed by blowing up gas from the lower part of the reactor without mechanical stirring. It can be divided into processes for proceeding polymerization. However, in the latter case, when the particle size of the polymerized polymer to be produced becomes large, it is necessary to increase the flow rate of the gas to be blown up, and the blower becomes large, which is economically disadvantageous. Furthermore, it is known that when the powder particle size is increased, a normal flow state cannot be formed no matter how much the gas flow rate is increased, which is not preferable from the viewpoint of stable operation. For these reasons, in order to produce the propylene-ethylene random copolymer component which is the object of the present invention, it is preferable to use a gas phase polymerization process with mechanical stirring.
If it is a gas phase polymerization process with mechanical stirring, there is no restriction | limiting in the form of a reactor, A vertical type, a horizontal type, or another form can be used.

EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not restrict | limited at all by these examples, unless it deviates from the summary.
The following catalyst synthesis step and polymerization step were all performed in a purified nitrogen atmosphere. The solvent used was dehydrated with molecular sieve MS-4A.
First, a method and an apparatus for measuring each physical property value and an example of production of the catalyst used will be shown.

1. Physical property measurement method and apparatus (1) Particle size of ion-exchange layered silicate particles:
The measurement was performed using a laser diffraction / scattering particle size distribution measuring apparatus (“LA-920” manufactured by Horiba, Ltd.). For the measurement of the ion-exchangeable layered silicate in the slurry before granulation, water was used as a dispersion medium, and the particle size distribution and average particle size (median diameter) were calculated with a refractive index of 1.32 and a shape factor of 1.0. The ion exchange layered silicate after granulation was measured in the same manner using ethanol as a dispersion medium.

(2) MFR:
A polypropylene-type polymer shows the melt index value measured by JISK6758.

(3) Melting point (Tm):
Using a Seiko DSC, take 5.0 mg of sample, hold at 200 ° C. for 5 minutes, crystallize to 40 ° C. at a rate of temperature decrease of 10 ° C./min, and further melt at a rate of temperature increase of 10 ° C./min. The melting peak temperature was Tm (unit: ° C.).

(4) Polymerization ratio of component (A) and component (B):
Measurement was performed according to the method described above.

(5) Ethylene content in component (A) and component (B):
Measurement was performed according to the method described above.

(6) Foaming ratio:
The specific gravity (dc0) of the unfoamed product and the specific gravity (dc1) of the foam were determined by the underwater substitution method, and [dc0 / dc1] was calculated from the values to obtain the expansion ratio. The specific gravity of the foam was measured in a state including the skin layer.

(7) Cell shape:
Microscopic observation (SEM) of the cross section of the foam was performed to examine the bubble state. The state where adjacent bubbles are independent from each other was evaluated as “independent”, and the state where they were connected was evaluated as “communication”.

(8) Subsequent grade fish eye measurement method:
The subsequent powder produced is collected and granulated by kneading and extruding. The granulated pellet is formed into a film with a thickness of 25 μm using a T-die. The fish eyes of the film thus formed were visually evaluated based on the following criteria for the appearance of the film per 250 cm ³ .
None: No fish eyes are observed on the film, and the appearance is good.
Yes ... Fish-eye is observed on the film.

2. Catalyst Preparation Silicate Chemical Treatment: To a glass separable flask with a 10 liter stirrer blade, 3.75 liters of distilled water was added slowly followed by 2.5 kg of concentrated sulfuric acid (96%). At 50 ° C., 1 kg of montmorillonite (Mizusawa Chemical Co., Ltd. Benclay SL; average particle size = 50 μm) was further dispersed, heated to 90 ° C., and maintained at that temperature for 6.5 hours. After cooling to 50 ° C., the slurry was filtered under reduced pressure to recover the cake. 7 liters of distilled water was added to this cake to reslurry it, and then filtered. This washing operation was performed until the pH of the washing solution (filtrate) exceeded 3.5. The collected cake was dried at 110 ° C. overnight under a nitrogen atmosphere. The mass after drying was 707 g. The chemically treated silicate was dried in a kiln dryer.

Catalyst preparation:
200 g of the dry silicate obtained above was introduced into a glass reactor with an internal volume of 3 liters, and 1160 ml of mixed heptane and 840 ml of a heptane solution of triethylaluminum (0.60 M) were added and stirred at room temperature. . After 1 hour, the mixture was washed with mixed heptane to prepare a silicate slurry at 2.0 liters.
Next, 9.6 ml of a heptane solution of triisobutylaluminum (0.71 M / L) was added to the prepared silicate slurry and reacted at 25 ° C. for 1 hour. In parallel, [(r) -dichloro [1,1′-dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) -4H-azurenyl}] zirconium] (the synthesis is disclosed in JP-A-10-226712) 33.1 ml of a triisobutylaluminum heptane solution (0.71 M) was added to 2180 mg (3 mmol) and 870 ml of mixed heptane (performed according to the Examples), and the mixture reacted at room temperature for 1 hour was added to the silicate slurry. Stir for 1 hour.

Prepolymerization:
Subsequently, 2.1 liters of n-heptane was introduced into a stirring autoclave having an internal volume of 10 liters that had been sufficiently replaced with nitrogen, and maintained at 40 ° C. The silicate / metallocene complex slurry prepared earlier was introduced there. When the temperature was stabilized at 40 ° C., propylene was supplied at a rate of 100 g / hour to maintain the temperature. After 4 hours, the supply of propylene was stopped and maintained for another 2 hours. After completion of the prepolymerization, the remaining monomer was purged, stirring was stopped and the mixture was allowed to stand for about 10 minutes, and then about 3 liters of the supernatant was decanted. Subsequently, 9.5 ml of a heptane solution of triisobutylaluminum (0.71 M / L) and 5.6 liters of mixed heptane were added, and the mixture was stirred at 40 ° C. for 30 minutes and allowed to stand for 10 minutes. Removed liters. This operation was further repeated 3 times. When the component analysis of the final supernatant was performed, the concentration of the organoaluminum component was 1.23 mmol / L and the Zr concentration was 8.6 × 10 ⁻⁶ g / L, and the abundance in the supernatant with respect to the amount charged. Was 0.016%. Subsequently, 17.0 ml of a heptane solution of triisobutylaluminum (0.71 M / L) was added, followed by drying at 45 ° C. under reduced pressure.
By this operation, a prepolymerized catalyst containing 2.1 g of polypropylene per 1 g of catalyst was obtained.

[Example 1]
(1) 1st superposition | polymerization process FIG. 1: is the flow sheet | seat of the superposition | polymerization apparatus used in the Example.
After introducing 35 kg of seed polymer in advance into a horizontal polymerization vessel 8 (L / D = 3.7, internal volume 100 L) having a stirring blade, nitrogen gas was circulated for 3 hours. Thereafter, the temperature was raised while introducing propylene, ethylene and hydrogen at a predetermined molar ratio and pressure, and when the polymerization conditions were satisfied, 0.20 g / hr of the prepolymerized catalyst was obtained, and the organoaluminum compound As a result, triisobutylaluminum was supplied from the pipes 1 and 2 so as to be constant at 30 mmol / hr. A mixed gas of ethylene / propylene = 0.065 is continuously supplied from the pipe 4 while maintaining the conditions of a reaction temperature of 65 ° C., a reaction pressure of 1.8 MPaG, and a stirring speed of 35 rpm, and further the hydrogen concentration in the gas phase of the reactor is reduced to hydrogen. Hydrogen gas was continuously supplied from the circulation pipe 14 so as to maintain the /propylene=0.024 molar ratio, and the molecular weight (MFR) of the produced polymer, that is, the propylene-ethylene random copolymer component (A) was adjusted.

  The reaction heat was removed by the heat of vaporization of the raw material propylene supplied from the pipe 12. The unreacted gas discharged from the polymerization vessel was cooled and condensed outside the reactor system through the pipe 10 and then refluxed to the polymerization vessel 8. The propylene-ethylene random copolymer component (A) obtained by the main polymerization is intermittently withdrawn from the polymerization vessel 8 through the pipe 24 so that the retained level of the polymer becomes 65% by volume of the reaction volume, and the second polymerization. The polymerizer 16 of the process was supplied. At this time, the production amount of the propylene-ethylene random copolymer component (A) was 7 kg / hr. A part of the propylene-ethylene random copolymer component (A) was extracted from the pipe 24 and used as a sample for determining MFR, ethylene content, and activity (polymer yield per unit mass of catalyst).

(2) Second polymerization step A propylene-ethylene random copolymer component (A) and propylene from the first polymerization step were added to a horizontal polymerization vessel 16 (L / D = 3.7, internal volume 100 L) having a stirring blade. A mixed gas of ethylene was intermittently supplied from the pipe 6 to carry out copolymerization of propylene and ethylene. The reaction conditions were a stirring speed of 18 rpm, a reaction temperature of 70 ° C., a reaction pressure of 1.7 MPaG, and the gas composition in the gas phase was adjusted to be ethylene / propylene = 0.45 and hydrogen / ethylene = 0.0001 molar ratio. . No hydrogen feed was performed in the second polymerization step. Oxygen gas was supplied from the piping 7 as a polymerization activity inhibitor for adjusting the polymerization amount of the propylene-ethylene random copolymer component (B).

  The reaction heat was removed by the heat of vaporization of the raw material propylene supplied from the pipe 21. The unreacted gas discharged from the polymerization vessel was cooled and condensed outside the reactor system through the pipe 18 and refluxed to the polymerization vessel 16. The propylene-based block copolymer produced in the second polymerization step was intermittently withdrawn from the polymerizer 16 through the pipe 27 so that the retained level of the polymer was 50% by volume of the reaction volume. At this time, a part of the polymerized propylene block copolymer is extracted to obtain MFR, polymer bulk density, rubber part content, ethylene content in rubber, and activity (polymer yield per unit mass of catalyst). It was.

(3) Analytical results of propylene-based block copolymer The analytical values are summarized in Table 3.

To 100 parts by weight of the resulting propylene polymer composition, 3.0 parts by weight of a foaming agent master batch (25% by weight of sodium bicarbonate, 25% by weight of citric acid) was added and dry blended, and then injection foam molding was performed. . The molding conditions for the foam molded article were as follows.
Using a heating cylinder with a screw diameter of 50 mm and a mold clamping control mechanism and an injection molding machine with a maximum clamping force of 300 tons, the temperature of each heating zone of the heating cylinder is 230 ° C, 230 ° C in order from the tip to the rear. 230 ° C., 210 ° C., and 180 ° C., the back pressure is 9.8 MPa, the mold cooling water temperature is 40 ° C., the distance between the movable mold and the fixed mold of the flat molded body is 2.0 mm, and the volume is 160 cm. in the cavity is ^3, and the heated and melted foamed molded body material 145g injected and filled. The primary cooling was performed for 1 second after completion of the injection, and then the movable mold was retracted by 2.0 mm to expand the cavity volume to 320 cm ³ and foam. Thereafter, secondary cooling was performed for 60 seconds to obtain a polypropylene resin foam molded article. The analysis results of the foamed molded product are shown in Table 3.

[Example 2]
First polymerization step:
The operation was performed under the same conditions as in Example 1.
Second polymerization step:
The operation was carried out under the same conditions as in Example 1 except that the hydrogen / ethylene ratio was 0.0019.
Conditions for injection foam molding:
The same conditions as in Example 1 were used.
Table 3 shows the powder analysis results, foam characteristics, and subsequent grade FE test results.

[Comparative Example 1]
First polymerization step:
The operation was performed under the same conditions as in Example 1 except that ethylene / propylene = 0.060 and hydrogen / propylene = 0.004 molar ratio.
Second polymerization step:
The operation was performed under the same conditions as in Example 1 except that the hydrogen / ethylene = 0.020 molar ratio.
Conditions for injection foam molding:
The same conditions as in Example 1 were used.
Table 3 shows the powder analysis results, foam characteristics, and subsequent grade FE test results.

[Comparative Example 2]
(1) Preparation of titanium-containing solid component (I) A 10 L autoclave equipped with a stirrer was sufficiently substituted with nitrogen, and 2 L of purified toluene was introduced. To this, 200 g of Mg (OEt) ₂ and 1 L of TiCl ₄ were added at room temperature. The temperature was raised to 90 ° C. and 50 ml of n-butyl phthalate was introduced. Thereafter, the temperature was raised to 110 ° C. to carry out a reaction for 3 hours. The reaction product was thoroughly washed with purified toluene.
Subsequently, the refined toluene was introduce | transduced and the whole liquid quantity was adjusted to 2L. 1 L of TiCl ₄ was added at room temperature, the temperature was raised to 110 ° C., and the reaction was performed for 2 hours. The reaction product was thoroughly washed with purified toluene. Furthermore, toluene was substituted with n-heptane using purified n-heptane to obtain a slurry of titanium-containing solid component (I). A portion of this slurry was sampled and dried. As a result of analysis, the Ti content of the solid component (I) was 2.7 wt. %Met. The average particle size of the solid catalyst was 33 μm.

(2) Preparation of pre-activated catalyst After replacing a stainless steel reactor with an inclined volume of 30 liters with inclined blades with nitrogen gas, 20 liters of n-hexane, 40 mmol of triethylaluminum, and the titanium-containing supported catalyst component prepared in the previous section After 40 g (40 mmol in terms of titanium atom) was added, 210 g of propylene was supplied at 15 ° C. for 120 minutes for prepolymerization. After completion of the reaction time, unreacted propylene was discharged out of the reactor, and the gas phase portion of the reactor was replaced with nitrogen once. Separately, as a result of analyzing the polymer produced after the prepolymerization performed under the same conditions, 2.1 g of polypropylene was produced per 1 g of the titanium-containing supported catalyst component, and the intrinsic viscosity [η1] of this polypropylene was 2.9 dl / g.

  Next, while maintaining the temperature in the reactor at −3 ° C., preactivation was performed by continuously supplying ethylene to the reactor for 6 hours so as to maintain the pressure in the reactor at 0.59 MPa. After completion of the reaction time, unreacted ethylene was discharged out of the reactor, and the gas phase portion of the reactor was replaced with nitrogen once to obtain a slurry of a preactivated catalyst. The amount of polymer produced after preactivation was 220.9 g per gram of the titanium-containing solid catalyst component, and the intrinsic viscosity [η2] of this polymer was 29.3 dl / g.

  The amount of ethylene polymer (A) produced per 1 g of titanium-containing supported catalyst component produced by preactivation with ethylene, and its intrinsic viscosity [ηA] were calculated. The ethylene polymer was 218 g and [ηA] was , 29.6 dl / g.

(3) First polymerization step After the inside of the polymerization vessel 8 is replaced, 25 kg of polypropylene powder (average particle size 1500 μm) from which polymer particles of 500 μm or less have been removed is introduced, and the preactivated catalyst obtained above is further added in an amount of 0. 49 g / h (excluding prepolymerized polymer), and a 15 wt% n-hexane solution of triethylaluminum with respect to 1 mol of Ti atom in the catalyst component (A) has a molar ratio of 90 and diisopropyldimethoxysilane as Ti atom It supplied continuously so that it might be set to 10 with respect to 1 mol. Further, hydrogen is added so that the molar ratio of hydrogen used to propylene in the polymerization vessel 8 is 0.15, and the propylene monomer is added so that the pressure in the polymerization vessel 8 is 2.15 MPa and the temperature is 65 ° C. Each was fed into the polymerization vessel 1.
Next, as a result of extracting and measuring a part of the propylene polymer produced in the polymerization vessel 1, [η] is 0.92 dl / g, and the content of the ethylene polymer (A) produced by the preactivation is 1.19% by weight.

(4) Second polymerization step The polymer, propylene, and ethylene gas from the first polymerization step were continuously supplied into the polymerization vessel 16 to produce an olefin random copolymer. The reaction conditions were a stirring speed of 25 rpm, a temperature of 65 ° C., and a pressure of 2.0 MPa. Hydrogen gas was not supplied.
The propylene polymer composition produced in the second polymerization step was continuously extracted from the polymerizer 16 through the polymer extraction pipe 27 so that the retained level of the polymer was 60% by volume of the reaction volume. At this time, the hydrogen concentration in the polymerization vessel 16 was 2 ppm.
The production rate of the propylene polymer composition was 10.1 kg / hr. The analysis results of the resulting propylene polymer composition are shown in Table 3.

Conditions for injection foam molding:
The same conditions as in Example 1 were used.
Table 3 shows the powder analysis results, foam characteristics, and subsequent grade FE test results.

  Propylene-based block copolymers that are excellent in fluidity and injection foaming moldability and are free of subsequent grade contamination by FE can be provided industrially and stably, and are very useful industrially.

It is the figure which showed the best form of this invention.

Explanation of symbols

1 and 2: Catalyst component supply piping 3 and 5: Raw material propylene supply piping 4 and 6: Raw material supply piping (hydrogen etc.)
7: Pipe for addition of activity inhibitor 8: Polymerizer (first polymerization step)
9 and 17: Gas-liquid separation tanks 10 and 18: Unreacted gas extraction pipes 11 and 19: Condensers 13 and 20: Compressors 12 and 21: Raw material liquefied propylene supply pipes 14 and 22: Raw material mixed gas supply pipes 16: Polymerization (Second polymerization process)
25: Degassing tank 24 and 27: Polymer extraction piping 26: Polymer supply piping

Claims (4)

A TREF curve obtained as a plot of the elution amount (dwt% / dT) against temperature by the temperature rising elution fractionation method (TREF) in the temperature range of −15 ° C. to 140 ° C. using an o-dichlorobenzene solvent is 65 to 65 ° C. A crystalline propylene-ethylene random copolymer component (A) showing a high-temperature side peak T (A) between 95 ° C. and a low-temperature side peak T (B) at 60 ° C. or lower, or no peak, A propylene-based block copolymer comprising a low crystalline or amorphous propylene-ethylene random copolymer component (B) and obtained using a metallocene catalyst,
MFR (temperature 230 ° C., load 2.16 kg) is 150 g / 10 min or more, and MFR (temperature 230 ° C., load 2.16 kg) of crystalline propylene-ethylene random copolymer component (A) is 200 g / 10 min or more. A propylene-based block copolymer characterized by   The proportion of the crystalline propylene-ethylene random copolymer component (A) is 30 to 90 mass%, and the proportion of the low crystalline or amorphous propylene-ethylene random copolymer component (B) is 10 to 70 mass%. The propylene-based block copolymer according to claim 1, wherein   After producing a crystalline propylene-ethylene random copolymer component (A), a low crystalline or amorphous propylene-ethylene random copolymer component in the presence of the crystalline propylene-ethylene random copolymer component (A) The propylene-based block copolymer according to claim 1 or 2, wherein (B) is produced subsequently.   The propylene-based block copolymer according to any one of claims 1 to 3, which is produced by gas phase polymerization.

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