JP5097366B2 - Propylene block copolymer - Google Patents

Description

  The present invention relates to a novel propylene-based block copolymer. More specifically, the present invention is excellent in flexibility and impact resistance, has no stickiness, has a good blocking property, generates less gel during molding, and has a linear expansion coefficient. The present invention relates to a novel propylene-based block copolymer which is low and has good powder properties.

  Crystalline polypropylene is widely used in various molding fields because of its excellent mechanical properties and chemical resistance. However, when a propylene homopolymer or a random copolymer with a small amount of α-olefin is used as the crystalline polypropylene, the rigidity is increased but the impact resistance is insufficient. Therefore, a method of adding an elastomer such as ethylene-propylene rubber to a propylene homopolymer or a random copolymer, or after propylene homopolymerization or random copolymerization with a small amount of α-olefin, followed by propylene and ethylene or α-olefin The impact resistance has been improved by a method of producing a so-called block copolymer by copolymerizing the above. Furthermore, it is known that a propylene-based block copolymer having improved flexibility and impact resistance can be obtained by increasing the amount of the rubber portion of the block copolymer.

  Another problem is that the propylene block copolymer obtained by polymerization in the presence of a conventional Ziegler-Natta type catalyst has low molecular weight components (oligomer components, etc.) due to the nature of the catalyst. It must exist. In particular, in recent years, there is a tendency to increase the fluidity and further improve the moldability of the resulting propylene-based block copolymer. However, for the rubber part, if the fluidity is increased too much, the generation ratio of low molecular weight components increases accordingly, and this low molecular weight component not only causes generation of smoke and off-flavor during processing, but also after processing. However, it is known to cause various problems such as bad influence on odor and taste, and deterioration of blocking property due to stickiness, and the powder property of polymerized polymer will deteriorate and stable production will not be possible. That was a problem. On the other hand, it is also known that when the difference in average molecular weight between the crystalline polypropylene and the rubber portion is large, there is a problem that the gel is increased during molding and the linear expansion coefficient is increased.

  On the other hand, it is known that isotactic polypropylene can be obtained by polymerizing propylene using a metallocene catalyst different from the conventional Ziegler type catalyst system. It is also known to produce a so-called block copolymer by copolymerizing ethylene and propylene after homopolymerization of propylene using the same catalyst (for example, see Patent Documents 1 to 5). Furthermore, a method for producing a block copolymer by producing a copolymer of ethylene and propylene in the former stage and conducting homopolymerization of propylene in the latter stage (for example, see Patent Document 6) is disclosed.

Furthermore, a propylene-ethylene block copolymer having good rigidity and impact resistance (for example, see Patent Documents 7 to 10) is disclosed. Moreover, the propylene-type resin composition (for example, refer patent documents 11-12) which is excellent in a softness | flexibility and transparency, and does not have a sticky feeling is disclosed.
Although the rigidity and impact resistance have been further improved by the above invention, the amount of propylene and ethylene or α-olefin copolymer that imparts flexibility and low temperature impact resistance, and the comonomer composition of the copolymer are still satisfactory. The level was not reached and improvement was desired.

JP-A-4-337308 JP-A-6-287257 Japanese Patent Laid-Open No. 5-202152 JP-A-6-206921 Japanese Patent Laid-Open No. 10-219047 JP-A-8-27237 Japanese Patent Laid-Open No. 11-228648 JP-A-11-240929 JP-A-11-349649 JP-A-11-349650 JP 2000-239462 A JP 2001-64335 A

  In view of the above-described conventional techniques, the object of the present invention is excellent in flexibility and impact resistance, has no stickiness, has good blocking properties, generates less gel during molding, has a low linear expansion coefficient, and produces a flow mark. It is an object of the present invention to provide a novel propylene-based block copolymer which is difficult and has good powder properties of the polymer powder.

  As a result of various investigations to solve such problems, the present inventors have found that a propylene-based block copolymer by a multistage polymerization process using a metallocene catalyst supported on a carrier, propylene and ethylene or α-olefin. The content of the copolymer component is set higher than a specific value, the polymerization ratio of the comonomer in the copolymer component is set higher than the specific value, and the weight average molecular weight of the copolymer component is set in a specific value range. In addition, when the ratio of the component amount having a molecular weight of 5000 or less is set to a specific value or less, it is excellent in flexibility and impact resistance, has no stickiness, has a good blocking property, generates less gel during molding, and has a linear expansion. It has been found that a novel propylene-based block copolymer having a low rate and good powder properties of the polymer powder can be obtained, and the present invention has been achieved.

That is, according to the first invention of the present invention, in the presence of a metallocene catalyst supported on a carrier, a propylene homopolymer component, or a group consisting of propylene and ethylene and / or an α-olefin having 4 to 20 carbon atoms. A pre-process for producing a propylene copolymer component (hereinafter referred to as PP) having a comonomer content of 10% by weight or less with at least one comonomer selected from the group consisting of propylene, ethylene and / or Alternatively, it is obtained by continuously performing multi-stage polymerization comprising a subsequent process for producing a copolymer component (hereinafter referred to as CP) with at least one comonomer selected from the group consisting of α-olefins having 4 to 20 carbon atoms. A propylene-based block copolymer,
A propylene-based block copolymer that satisfies the following requirements (1) to (6) is provided.
Requirement (1): The content of CP in the propylene-based block copolymer is 50 to 99% by weight.
Requirement (2): The polymerization ratio of the comonomer in CP is less than 45-100 mol%.
Requirement (3): CP has a weight average molecular weight of 200,000 to 1,200,000 .
Requirement (4): The ratio of the component amount (M ≦ 5000) having a molecular weight of 5000 or less as measured by gel permeation chromatography (GPC) is 2.0% by weight or less.
Requirement (5): PP has a melting point of 157 to 165 ° C.
Requirement (6): The bulk density is 0.37 to 0.55 g / cm ³ .

  According to a second aspect of the present invention, there is provided a propylene-based block copolymer characterized in that, in the first aspect, the CP content is 50 to 80% by weight.

According to a third aspect of the present invention, there is provided a propylene-based block copolymer according to the first or second aspect , wherein the comonomer used in CP is ethylene.

According to a fourth aspect of the present invention, there is provided a propylene-based block copolymer according to any one of the first to third aspects, wherein PP is a propylene homopolymer.

According to a fifth aspect of the present invention, there is provided the propylene-based block copolymer according to any one of the first to fourth aspects, wherein the preceding step is performed by gas phase polymerization.

According to a sixth aspect of the present invention, there is provided the propylene-based block copolymer according to any one of the first to fifth aspects, wherein the subsequent step is performed in the presence of an electron donating compound.

According to the seventh invention of the present invention, in any one of the first to sixth inventions, the subsequent step is performed in the presence of an organoaluminum compound in addition to the electron donating compound, and the electron donating property. A propylene-based block copolymer is provided in which the amount of the compound is in the range of 0.001 to 1.0 in terms of molar ratio with respect to aluminum atoms.

According to an eighth invention of the present invention, in any one of the first to seventh inventions, the latter step is performed by a mechanically stirred gas phase polymerization process. A polymer is provided.

According to the ninth invention of the present invention, in any one of the first to eighteenth inventions, the carrier is a substantially spherical inorganic compound carrier, and an average particle diameter thereof is 25 to 200 μm. A propylene-based block copolymer is provided.

According to a tenth aspect of the present invention, there is provided the propylene-based block copolymer according to the ninth aspect , wherein the inorganic compound-based carrier has an average crushing strength of 1 to 20 MPa. .
According to an eleventh aspect of the present invention, there is provided a propylene block copolymer particle according to any one of the first to tenth aspects.

  In the propylene block copolymer of the present invention, the amount of propylene and ethylene or α-olefin copolymer and the comonomer composition of the copolymer are improved, and the amount of propylene-α-olefin copolymer is more than conventional. High, the comonomer composition of the copolymer is high, the weight average molecular weight of the copolymer component is in a specific numerical range, and the content of the low molecular weight component is low, and the powder properties of the polymer powder are good, It is a propylene-based block copolymer that is excellent in flexibility and impact resistance, has no stickiness, has a good blocking property, generates less gel during molding, and has a low coefficient of linear expansion.

  The propylene-based block copolymer of the present invention is selected from the group consisting of a propylene homopolymer component or propylene and ethylene and / or an α-olefin having 4 to 20 carbon atoms in the presence of a metallocene catalyst supported on a carrier. A pre-stage for producing a propylene copolymer component (PP) having a comonomer content of 10% by weight or less with at least one comonomer, and a group consisting of propylene and ethylene and / or an α-olefin having 4 to 20 carbon atoms A novel polymer characterized by satisfying the above requirements (1) to (4) obtained by a multi-stage polymerization reaction comprising a subsequent stage process for producing a copolymer component (CP) with at least one comonomer selected from It is. Hereinafter, the characteristics of the propylene-based block copolymer of the present invention, the production method thereof, the catalyst used in the production method, the polymerization process, etc. will be described in detail for each item.

I. Characteristics of propylene-based block copolymer The propylene-based block copolymer of the present invention is characterized by satisfying the following requirements (1) to (4).

1. Requirement (1): CP content in propylene-based block copolymer The propylene-based block copolymer of the present invention is a propylene-α of propylene and ethylene and / or an α-olefin having 4 to 20 carbon atoms. -Content of an olefin copolymer component (CP) needs to be 50 to 99 weight%, Preferably it is 50 to 80 weight%, More preferably, it is 50 to 70 weight%. Generally, in a propylene-based block copolymer, a propylene-α-olefin copolymer is a random copolymer, and a substance having poor crystallinity and showing physical properties such as rubber is a main component, It becomes a basic factor that expresses flexibility. In the propylene-α-olefin copolymer in the block copolymer of the present invention, since the random copolymerizability is high, the CP content is excellent in a wide range of 50 to 99% by weight, and the CP content If it is less than 50% by weight, sufficient flexibility cannot be exhibited. The value of the flexural modulus, which is an index of flexibility, is preferably 800 MPa or less. On the other hand, if the CP content exceeds 99%, a well-balanced physical property as a propylene-based block copolymer cannot be obtained, and problems such as a decrease in rigidity due to a decrease in PP content occur. By doing so, it becomes possible to obtain a block copolymer having excellent physical properties.
In order to make the CP content within this range, the weight of PP produced in the preceding step and the weight of CP produced in the subsequent step in the production method described later may be set to a predetermined ratio.
The definition and measurement method of the CP content will be described later.

2. Requirement (2): comonomer polymerization ratio in CP The propylene-based block copolymer of the present invention requires that the comonomer polymerization ratio in CP is less than 45 to 100 mol%, preferably 45 to 99 mol%. More preferably, it is 45-95 mol%, Most preferably, it is 45-80 mol%, More preferably, it is 50-80 mol%. When the comonomer polymerization ratio is less than 45 mol%, there is a disadvantage that impact strength and flexibility at low temperatures are lowered.
The comonomer polymerization ratio in CP is a factor affecting the crystallinity and rubber properties of the propylene-α-olefin copolymer, particularly at low temperatures below room temperature, particularly at extremely low temperatures such as −10 to −30 ° C. It has a great impact on impact resistance. The α-olefin polymerization ratio in CP is controlled to a desired value within the range specified in the present invention by adjusting the composition ratio of the raw material gas in the production process of the propylene-α-olefin block copolymer in the subsequent step. be able to.
A method for measuring comonomer in CP will be described later.

3. Requirement (3): CP weight average molecular weight The propylene block copolymer of the present invention has a CP weight average molecular weight of 100,000 to 2,000,000, preferably 150,000 to 1,500,000, more preferably 200,000 to 1,200,000. The weight average molecular weight of CP is a factor having a great influence on impact resistance. If the weight average molecular weight of CP is less than 100,000, the impact resistance is not sufficient, and inconvenience occurs. And the product overview is poor.
The weight average molecular weight of CP can be controlled by the addition amount of the molecular weight modifier at the time of polymerization in the subsequent step in the production method described later. As the molecular weight regulator, hydrogen is most preferable.
The method for measuring the weight average molecular weight of CP will be described below.

  In the present invention, the CP content in the propylene-based block copolymer, the α-olefin polymerization ratio in CP, and the weight average molecular weight of CP are determined by the following methods. In addition, although the following examples are when ethylene is used as the α-olefin in the CP, α-olefins other than ethylene are obtained using a method according to the following example.

(1) Analytical device to be used (i) Cross fractionation device CFC T-100 (abbreviated as CFC) manufactured by Dia Instruments Co., Ltd.
(Ii) Fourier transform infrared absorption spectrum analysis FT-IR, Perkin Elmer 1760X
A fixed wavelength infrared spectrophotometer attached as a CFC detector is removed and an FT-IR is connected instead, and this FT-IR is used as a detector. The transfer line from the outlet of the solution eluted from the CFC to the FT-IR is 1 m long, and the temperature is maintained at 140 ° C. throughout the measurement. The flow cell attached to the FT-IR has an optical path length of 1 mm and an optical path width of 5 mmφ, and the temperature is maintained at 140 ° C. throughout the measurement.
(Iii) Gel permeation chromatography (GPC)
Three GPC columns (AD806MS manufactured by Showa Denko KK) are connected in series to the subsequent stage of the CFC.

(2) CFC measurement conditions (i) Solvent: orthodichlorobenzene (ODCB)
(Ii) Sample concentration: 4 mg / mL
(Iii) Injection volume: 0.4 mL
(Iv) Crystallization: The temperature is lowered from 140 ° C. to 40 ° C. over about 40 minutes.
(V) Sorting method:
The fractionation temperature at the time of temperature-raising elution fractionation is 40, 100, and 140 ° C., and the fraction is separated into three fractions in total. In addition, the elution ratio (unit:% by weight) of the component eluting at 40 ° C. or lower (fraction 1), the component eluting at 40 to 100 ° C. (fraction 2), and the component eluting at 100 to 140 ° C. (fraction 3), respectively W ₄₀ , W ₁₀₀ , and W ₁₄₀ are defined. W ₄₀ + W ₁₀₀ + W ₁₄₀ = 100. Moreover, each fractionated fraction is automatically transported to the FT-IR analyzer as it is.
(Vi) Solvent flow rate during elution: 1 mL / min

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

(4) Post-treatment and analysis of measurement results The elution amount and molecular weight distribution of the components eluted at each temperature are obtained using the absorbance at 2945 cm ⁻¹ obtained by FT-IR as a chromatogram. The elution amount is normalized so that the total elution amount of each elution component is 100%. Conversion from the retention volume to the molecular weight is performed using a calibration curve prepared in advance with standard polystyrene.
Standard polystyrenes used are the following brands manufactured by Tosoh Corporation.
F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000.
A calibration curve is created by injecting 0.4 mL of a solution dissolved in ODCB (containing 0.5 mg / mL BHT) so that each is 0.5 mg / mL. The calibration curve uses a cubic equation obtained by approximation by the least square method. Conversion to molecular weight uses a general-purpose calibration curve with reference to “Size Exclusion Chromatography” written by Sadao Mori (Kyoritsu Shuppan). The following numerical values are used for the viscosity equation ([η] = K × Mα) used at that time.
(I) Calibration curve using standard polystyrene K = 0.000138, α = 0.70
(Ii) Sample measurement of propylene-based block copolymer K = 0.000103, α = 0.78
The ethylene content distribution (distribution of ethylene content along the molecular weight axis) of each eluted component is the ratio of the absorbance of 2956 cm ⁻¹ and the absorbance of 2927 cm ⁻¹ obtained by GPC-IR, and is obtained by using polyethylene, polypropylene, or ¹³ Converted to ethylene polymerization rate (mol%) using a calibration curve prepared in advance using ethylene-propylene-rubber (EPR) whose ethylene content is known by C-NMR measurement and the like and mixtures thereof. And ask.

(5) CP content The CP content of the propylene-based block copolymer in the present invention is defined by the following formula (I), and is determined by the following procedure.
CP content (% by weight) = W ₄₀ × A ₄₀ / B ₄₀ + W ₁₀₀ × A ₁₀₀ / B ₁₀₀ (I)
In the formula (I), W ₄₀ and W ₁₀₀ are elution ratios (unit:% by weight) in each of the above-described fractions, and A ₄₀ and A ₁₀₀ are actual values in the respective fractions corresponding to W ₄₀ and W _100. the average ethylene content of measurement (unit: _wt%), B _{40, B 100,} the ethylene content of the CP contained in each fraction (unit: wt%). A method for _obtaining A ₄₀ , A ₁₀₀ , B ₄₀ , and B ₁₀₀ will be described later.

The meaning of the formula (I) is as follows.
That is, the first term on the right side of the formula (I) is a term for calculating the amount of CP contained in fraction 1 (portion soluble at 40 ° C.). When fraction 1 contains only CP and does not contain PP, W ₄₀ contributes to the CP content derived from fraction 1 as a whole, but fraction 1 contains a small amount of components in addition to CP-derived components. Since components derived from PP (extremely low molecular weight components and atactic polypropylene) are also included, it is necessary to correct the portion. Therefore, by multiplying W ₄₀ by A ₄₀ / B ₄₀ , the amount derived from the CP component in fraction 1 is calculated. For example, when the average ethylene content (A ₄₀ ) of fraction 1 is 30% by weight and the ethylene content (B ₄₀ ) of CP contained in fraction 1 is 40% by weight, 30/40 = 3 of fraction 1 / 4 (that is, 75% by weight) is derived from CP, and 1/4 is derived from PP. Thus, the operation of multiplying A ₄₀ / B ₄₀ by the first term on the right side means that the contribution of CP is calculated from the weight% (W ₄₀ ) of the fraction 1.
The same applies to the second term on the right side, and for each fraction, the CP content is calculated by adding and calculating the contribution of CP.

The average ethylene content _{A 40, A 100, A 140} of fractions 1-3, the ethylene content of the weight ratio and each data point for each data point in the chromatogram absorbance 2945cm ^-1 (absorbance at 2956cm ^-1 And the product of the absorbance of 2927 cm ⁻¹ ).

The ethylene content corresponding to the peak position in the differential molecular weight distribution curve of fraction 1 is defined as B ₄₀ (unit is% by weight). Fraction 2 is considered to be completely eluted at 40 ° C. and cannot be defined with the same definition, so in the present invention, it is defined as B ₁₀₀ = 100. B ₄₀ and B ₁₀₀ are the ethylene content of CP contained in each fraction, but it is practically impossible to obtain this value analytically. This is because there is no means for completely separating and separating PP and CP mixed in the fraction. As a result of examination using various model samples, B ₄₀ can explain the improvement effect of material physical properties well by using the ethylene content corresponding to the peak position of the differential molecular weight distribution curve of fraction 1. all right. Further, B ₁₀₀ has crystallinity derived from ethylene chain, and the amount of CP contained in these fractions is relatively small compared to the amount of CP contained in fraction 1, Approximation with 100 is closer to the actual situation, and there is almost no error in calculation. Therefore, the analysis is performed with B ₁₀₀ = 100. Therefore, the CP content can be determined according to the following formula.
CP content _{(wt%) = W 40 × A 40} / B 40 + W 100 × A 100/100 ... (II)
_{That, W 40 × A 40 / B} 40 is a first term of the formula (II) the right-hand side shows the CP content having no crystallinity _{(wt%), W 100 × A 100} /100 is a paragraph The CP content (% by weight) having crystallinity is shown.

The ethylene content in the copolymer component is determined by the following formula (III) using the content of the copolymer component determined by the formula (II).
Ethylene content (% by weight) in copolymer component = (W ₄₀ × A ₄₀ + W ₁₀₀ × A ₁₀₀ + W ₁₄₀ × A ₁₄₀ ) / [Copolymer component content (% by weight)] (III)

The significance of setting the three types of fractionation temperatures is as follows. In the CFC analysis of the present invention, only polymers having no crystallinity at 40 ° C. (for example, most of CP, or extremely low molecular weight components and atactic components among propylene polymer components (PP)) are separated. It has the meaning that it is a necessary and sufficient temperature condition. 100 ° C. means only components that are insoluble at 40 ° C. but become soluble at 100 ° C. (for example, components having crystallinity due to the chain of ethylene and / or propylene and PP having low crystallinity in CP) The temperature is necessary and sufficient to elute. 140 ° C. is a component that is insoluble at 100 ° C. but becomes soluble at 140 ° C. (for example, a component having particularly high crystallinity in PP and a component having extremely high molecular weight and extremely high ethylene crystallinity in CP) The temperature is necessary and sufficient to recover only the total amount of the propylene-based block copolymer used for the analysis. It should be noted that W ₁₄₀ does not contain any CP component, or even if it is present, it is very small and can be substantially ignored, so it is excluded from the calculation of the CP content and the ethylene content.

(6) Ethylene polymerization ratio The ethylene content in CP is determined by the following formula.
Ethylene content (% by weight) in CP = (W ₄₀ × A ₄₀ + W ₁₀₀ × A ₁₀₀ ) / [CP]
However, [CP] is the CP content (% by weight) determined previously.
From the value of the ethylene content (% by weight) in the CP thus obtained, the molecular weight of ethylene and propylene is finally used to convert to mol%.

(7) Weight average molecular weight of CP The weight average molecular weight of CP is the weight average molecular weight of the 40 ° C. soluble portion by CFC analysis.

4). Requirement (4): Ratio of component amount (M ≦ 5000) having a molecular weight of 5000 or less as measured by gel permeation chromatography (GPC) The propylene-based block copolymer in the present invention is characterized by having a low molecular weight component. Low molecular weight components, especially those whose molecular weight is less than the molecular weight between the entanglement points, cause bleed out and stickiness on the surface of the molded product, and also cause problems when handling polymer powders, thus suppressing their generation. It is desirable.
The molecular weight between the entanglement points of polypropylene is about 5000, as described in Journal of Polymer Science: Part B: Polymer Physics; 37, 1023-1033 (1999).
Therefore, the propylene-based block copolymer in the present invention has few low molecular weight components, and the component having a weight average molecular weight of 5000 or less by GPC measurement is 2.0% by weight or less, preferably 1.5% by weight or less. It is characterized by that.
In order to obtain such a propylene-based block copolymer, it is necessary to maintain the polymerization conditions corresponding to the respective polymer compositions in the former step and the latter step in the production method described below, particularly the monomer gas composition at different specific values. is there. In particular, in order to prevent the generation of low molecular weight components, it is possible to shorten the switching time between the former process and the latter process, or to completely replace the monomer gas mixture corresponding to the former process with an inert gas such as nitrogen at the time of switching. Independent of the polymerization conditions, the generation of low molecular weight components can be suppressed.

The measurement method of gel permeation chromatography is as follows.
(I) Device: GPC (ALC / GPC 150C) manufactured by WATERS
(Ii) Detector: MIRAN 1A IR detector manufactured by FOXBORO (measurement wavelength: 3.42 μm)
(Iii) Column: AD806M / S (3 pieces) manufactured by Showa Denko KK
(Iv) Mobile phase solvent: orthodichlorobenzene (ODCB)
(V) Measurement temperature: 140 ° C
(Vi) Flow rate: 1.0 ml / min (vii) Injection volume: 0.2 ml
(Viii) Preparation of sample Prepare a 1 mg / mL solution using ODCB (containing 0.5 mg / mL BHT) and dissolve it at 140 ° C. for about 1 hour.
The conversion from the retention capacity to the molecular weight was the same as that performed by CFC.
The amount of the component having a molecular weight of 5000 or less can be determined from the plot of the elution ratio with respect to the molecular weight obtained by the GPC measurement.

5. Bulk density (Polymer BD)
The propylene-based block copolymer of the present invention preferably has a bulk density of 0.37 g / cm ³ or more. The upper limit is about 0.55 g / cm ³ , preferably in the range of 0.40 to 0.50 g / cm ³ . When the bulk density is lower than 0.37 / cm ³ , adhesion to the line, clogging, adhesion on the inner wall of the polymerization reactor, piping, heat exchanger, etc. occur, resulting in a problem that the polymerization cannot be performed stably. There is a fear.
In order to make the bulk density within this range, as described later, it can be achieved by adjusting the production of the catalyst, for example, by adjusting the particle size of the support.

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 preferably used is (A) a conjugated five member A metallocene complex composed of a transition metal compound such as Group 4 of the periodic table having a ring ligand, (B) a cocatalyst that activates the metallocene complex, and (C) an organoaluminum compound used as necessary Can be mentioned. Depending on the characteristics of the olefin polymerization process, when particle formation is essential, a carrier (D) can be further added as a constituent element to the metallocene catalyst system. Hereinafter, (A) to (D) will be described. In the description of the present specification, a short period type is used as the periodic table of elements.

(1) Metallocene complex (A)
Examples of the metallocene complex used in the present invention include a metallocene complex of a transition metal compound of Groups 4 to 6 of the periodic table having a conjugated five-membered ring ligand as a representative one. Those represented by either of these are preferred.

In the above general formula, A and A ′ are cyclopentadienyl groups which may have a substituent. An example of this substituent is a hydrocarbon group having 1 to 30 carbon atoms (which may contain a hetero atom such as halogen, silicon, oxygen or sulfur). Even if this hydrocarbon group is bonded to the cyclopentadienyl group as a monovalent group, and when there are a plurality of these, two of them are bonded to the other end (ω-end) to form cyclopentadienyl. A ring may be formed together with a part of the enyl. Other examples include an indenyl group, a fluorenyl group, or an azulenyl group. These groups may further have a substituent on the side ring. Among these, an indenyl group or an azulenyl group is preferable.
Q represents a binding group that bridges between two conjugated five-membered ring ligands at an arbitrary position, and specifically, is preferably an alkylene group, a silylene group, a silafluorene group, or a germylene group.
M is a metal atom of a transition metal selected from Groups 4 to 6 of the periodic table, preferably titanium, zirconium, hafnium or the like. In particular, zirconium and hafnium are preferable.
X and Y are auxiliary ligands, which react with the component (B) to produce an active metallocene having olefin polymerization ability. Therefore, as long as this object is achieved, X and Y are not limited in the type of ligand, and each may be a hydrogen atom, a halogen atom, a hydrocarbon group, or a hydrocarbon group optionally having a heteroatom. Can be illustrated. 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 silicates. Hereinafter, (B-1) to (B-4) will be described.

(B-1) Aluminum Oxy Compound (B-1) In an aluminum oxy compound, it is well known that an aluminum oxy compound can activate a metallocene complex. Specifically, as such a compound, the following general formulas The compound represented by these is mentioned.

In 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 to 1 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 1: 1 (molar ratio) reaction. 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 a Lewis acid (B-2) compound capable of reacting with component (A) to convert component (A) into a cation reacts with component (A) An ionic compound or Lewis acid capable of converting (A) into a cation. Examples of such an ionic compound include cations such as a carbonium cation and an ammonium cation, triphenylboron, and tris (3, 5-Difluorophenyl) boron, complexed compounds with organic boron compounds such as tris (pentafluorophenyl) boron, and the like.
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 of (B-3) include alumina, silica-alumina, and silica-magnesia.

(B-4) Ion exchange layered compound The ion exchange layer compound of (B-4) 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, etc. 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 copolymer component that is a rubber component, and in order to stably produce such a polymer having a high rubber component content, a catalyst is used. It is preferable to use a supported catalyst using a carrier. 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. Since the shape and particle size of the catalyst are almost the same as the shape and particle size of the carrier, the shape and particle size of the catalyst can be controlled by controlling the shape and particle size of the carrier. For example, when an inorganic compound carrier is used, the following examples can be given.

  The particle diameter of the raw inorganic compound carrier is 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 and less than 1 μm. The particle fraction 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 pulverization method in a wet state, polytron, etc. is used. 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 of the carrier is preferably within a certain range. If the particle strength of the carrier is too low, the catalyst powder and polymer particles are liable to disintegrate, so that fine powder is generated, flowability and adhesion are deteriorated, and the bulk density is lowered. Therefore, in the present invention, the average crushing strength of the carrier is desirably 1 MPa or more, and more preferably 3 MPa or more. On the other hand, if the particle strength is too high, uniform catalyst activation may be hindered during prepolymerization or polymerization, or particle growth may be uneven and fine powder may be generated. Therefore, the upper limit of the carrier strength is desirably an average crushing strength of 20 MPa or less, more preferably 15 MPa or less. 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.
Furthermore, there may be a combination of granulation methods when granulating in multiple stages, and there is no limitation on the combination, but preferably, spray granulation method and spray granulation method, spray granulation method and rolling rolling method. It is a combination of granulation method, spray granulation method and fluidized granulation method.

The shape of the granulated particles obtained by the above granulation method is preferably spherical, and specifically, the number of particles having an M / L value of 0.8 or more and 1.0 or less is the total number of particles. It is a shape satisfying that it is 50% or more and 100% or less (where, L is the maximum particle diameter value in the projected view, and M is the diameter value orthogonal to L). Preferably, the number of particles having an M / L value of 0.8 or more and 1.0 or less is 85% or more and 100% or less of all particles.
M / L is obtained by observing 100 or more of arbitrary particles with an optical microscope and image-processing them.

The concentration of the silicate in the raw slurry in the spray granulation for obtaining spherical inorganic compound carrier particles is 0.1 to 50% by weight, preferably 0.5 to 30% by weight, particularly preferably, depending on the slurry viscosity. Is 5.0 to 20% by weight. The temperature at the inlet of the hot air for spray granulation from which spherical particles are obtained varies depending on the dispersion medium, but is 80 to 260 ° C, preferably 100 to 220 ° C when water is taken as an example. Any desired dispersion medium can be used. Water or an organic solvent such as methanol, ethanol, chloroform, methylene chloride, pentane, hexane, heptane, toluene, xylene alone or in a mixed solvent is used. Of these, water is particularly preferred.
The inorganic compound carrier thus obtained may be used as it is as a catalyst carrier. In that case, a preferable particle diameter is 25-200 micrometers, More preferably, it is 25-150 micrometers.

  Further, in order to obtain particles having a desired shape with a desired particle diameter, the particle diameter of the raw material may be prepared by at least two stages of granulation processes. That is, it is possible to control the particle shape and particle size by granulating to a particle size that can be granulated to some extent in the first-stage granulation step, and performing granulation again using the granulated particle size. In the first-stage granulation step, primary inorganic particles are produced by granulating the inorganic compound carrier fine particles of the raw material having an average particle diameter of 0.01 to 5 μm. The primary granulated particles preferably have a particle size of 1 to 25 μm. More preferably, it is 1-15 micrometers.

  The primary granulated particles thus granulated are further slurried to perform the next granulation. At that time, the slurry viscosity is relatively low, and the slurry concentration can be increased. By taking appropriate spray granulation conditions, it is possible to obtain a particle size and particle shape suitable for the polymerization catalyst component. The particle size that can be produced is 25 to 200 μm, preferably 25 to 150 μm, although it depends on the type of raw material inorganic compound carrier.

The granulation conditions can be selected appropriately so that particles having good properties can be obtained by the granulation method. For example, in the spray granulation method, the inlet temperature of hot air during spraying can be set in a wide temperature range of about 90 ° C to 300 ° C. The outlet temperature is defined by the flow rate of spray from the nozzle or disk, the flow rate of hot air, and the like, and is 80 ° C. to 150 ° C. As the spray format, a general spray drying method such as a disk type, a pressurized nozzle type, or a two-fluid nozzle type can be applied. In order to control the particle size, it is possible to set the flow rate of the spray liquid, the rotational speed or the disk size of the disk, the pressure of the pressure nozzle, the flow rate of the carrier gas, and the like.
In the present invention, since the primary granulated particles are granulated again to produce secondary particles, the secondary granulated particles have a larger size. The particle size increase rate of the primary particles relative to the raw material particles is preferably 3 to 500%, more preferably 5 to 300%. Further, the particle size increase rate of the secondary particles relative to the primary particles is preferably 3 to 200%, more preferably 3 to 100%. Therefore, it is possible to obtain particles with better powder properties when the primary granulation condition and the secondary granulation condition are different. For example, it is possible to obtain particles in which secondary granulation is preferred to lower the rotational speed of the disc than primary granulation. The secondary granulation disk rotation speed is preferably 1000 to 30000 rpm lower than the primary granulation disk rotation speed, and more preferably 5000 to 20000 rpm. The drying temperature is preferably lower in the secondary granulation than in the primary granulation. The hot air inlet temperature for secondary granulation is preferably 10 to 80 ° C. lower than the hot air inlet temperature for primary granulation, and more preferably 20 to 50 ° C. lower. Specifically, depending on the disk size, in the primary granulation, the hot air inlet temperature is preferably 130 to 250 ° C, more preferably 150 to 200 ° C. The disk rotation speed is preferably 10,000 to 30,000 rpm. In secondary granulation, the hot air inlet temperature is preferably 90 ° C to 180 ° C, more preferably 100 to 150 ° C. The disk rotation speed is preferably 5000 to 20000 rpm.

During granulation, organic substances, inorganic solvents, inorganic salts, and various binders may be used. Examples of the binder used include sugar, dextrose, corn syrup, gelatin, glue, carboxymethylcelluloses, polyvinyl alcohol, water glass, magnesium chloride, aluminum sulfate, aluminum chloride, magnesium sulfate, alcohols, glycol, starch, casein, Examples thereof include latex, polyethylene glycol, polyethylene oxide, tar, pitch, alumina sol, silica gel, gum arabic, and sodium alginate.
In this manner, a supported catalyst having a maintained particle shape and particle size can be produced by supporting a metallocene complex on a granulated inorganic compound carrier.

2. Use amount of catalyst component In the above catalyst component, the use amounts of the component (A) and the component (B) are used in an optimum amount ratio in each combination.
When the 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 a Lewis acid is used as the component (B), the molar ratio of the transition metal to the transition metal is 0.1 to 1000, preferably 0.5 to 100, more preferably 1 to 50. .
When a solid acid or an ion-exchange layered silicate is used as the component (B), the transition metal complex is in the range of 0.001 to 10 mmol, preferably 0.001 to 1 mmol, per 1 g of the component (B).
These use ratios are examples of normal ratios, and the present invention is not limited by the range of use ratios described above as long as the catalyst is purposeful. It is natural.

  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 production method of the propylene-based block copolymer of the present invention includes a propylene homopolymer component, or at least one comonomer selected from the group consisting of propylene and ethylene and / or an α-olefin having 4 to 20 carbon atoms. A pre-process for producing a copolymer component (PP) having a comonomer content of 10% by weight or less, followed by at least one comonomer selected from the group consisting of propylene and ethylene and / or an α-olefin having 4 to 20 carbon atoms And a subsequent step for producing a propylene-α-olefin copolymer component (CP).

In each step, either a bulk polymerization method or a gas phase polymerization method can be employed. For example, since it is preferable that the latter-stage process is a gas phase polymerization method, the following advantages can be given when the preceding-stage process that is continuous thereto also adopts the gas phase polymerization method.
In other words, since the PP component is obtained by gas phase polymerization, the drying step can be omitted because no polymerization solvent is used. In addition, among PP components, a polymer having a relatively low melting point increases the amount of eluted components in the solvent, which makes it difficult to produce industrially stable operations. Also, operations such as separation and recovery of eluted components. Therefore, the manufacturing cost increases, and there are cases where it is not suitable for industrial production. Furthermore, if the pre-stage process is carried out by so-called bulk polymerization in which polymerization is performed in liquid propylene, there is a concern that the polymer temperature cannot be raised to an industrial level because there is a concern about the dissolution of the polymer when producing a low melting point polymer. In addition, since it is difficult to control the activity in the bulk polymerization method, the catalyst efficiency in the previous step becomes too high, and if the catalyst efficiency in the previous step is increased too much, the target CP content is determined from the balance of activity and reaction time. May not reach.
Thus, in the present invention, in addition to using a catalyst having a large particle size, etc., by adopting a method in which the previous step is performed by a gas phase polymerization method, adjusting the activity, reaction time, etc. It is possible to produce a new propylene-based block copolymer having a high melting point of PP component and excellent rigidity, and stably having a high proportion of CP component produced in the subsequent step as the object of the present invention. is there.

However, since the propylene-α-olefin copolymer component to be produced is a rubber component and it is desirable that it is not eluted in the solvent, a gas phase polymerization method is employed in the subsequent step. The process is preferably performed by a mechanically stirred gas phase polymerization process.
As the polymerization method, both a batch method and a continuous method can be adopted for each of the former step and the latter step. In the present invention, two-stage polymerization consisting of a front stage and a rear stage is performed, but in some cases, each stage can be further divided. In particular, a method for improving the physical properties is to divide the latter step into two or more steps to produce various types of rubber components.

(1) Production of propylene polymer component (PP) In the preceding polymerization step, a metallocene catalyst, preferably a catalyst comprising the above-mentioned components (A) and (B), and optionally (C) and (D), is prepared. Used to produce propylene homopolymer or propylene / α-olefin copolymer. That is, a propylene homopolymer or a copolymer of propylene and an α-olefin in one or more stages, 1 to 55% by weight, preferably 20 to 55% by weight, based on the total polymerization amount (the whole propylene block copolymer), It is the process of forming so that it may correspond to. As the propylene polymer component (PP), a propylene homopolymer is preferable because the rigidity and heat resistance can be increased.
When using a copolymer of propylene and an α-olefin, the α-olefin is an α-olefin having 4 to 20 carbon atoms other than propylene including ethylene, such as butene-1, hexene-1, 4 -Methyl-pentene-1, octene-1, decene-1, etc. are mentioned. Of these, ethylene is most preferred. When α-olefin is used, the amount used is 10% by weight or less, preferably 5% by weight or less, based on the total monomers (total of propylene and α-olefin).

The polymerization temperature in the preceding polymerization step is about 30 to 120 ° C, preferably about 50 to 90 ° C. The polymerization pressure is 0.1 to 6 MPa, preferably 0.1 to 4 MPa. Moreover, it is preferable to use a molecular weight (MFR) adjusting agent so that the fluidity of the polymer is appropriate, and hydrogen is preferable as the adjusting agent. Although MFR depends on the use of the final polymer, the preferred range is 0.1 to 3000 g / 10 minutes, preferably 0.5 to 2000 g / 10 minutes, and more preferably 0.5 to 1000 g / 10 minutes. Under these conditions, the average particle diameter and melting point of the polymer (PP) sent from the former stage process to the latter stage process can be made to have desired values in the present invention.
The melting point of the polymer (PP) is preferably 157 ° C. or higher. The upper limit is usually 165 ° C. for reasons of industrial productivity, preferably 163 ° C. or lower, and more preferably 162 ° C. or lower.
The propylene block copolymer of the present invention preferably has a melting point of 157 ° C. or higher. When the melting point is less than 157 ° C., heat resistance and rigidity are insufficient. In order to obtain such a high melting point PP, a metallocene complex, a cocatalyst, polymerization conditions and the like are used in appropriate combination. In general, it can often be achieved by increasing the polymerization pressure and / or decreasing the polymerization temperature. It can also be achieved by using a combination of the catalyst components (A) to (C) disclosed in the present invention. In the case of a propylene-based block copolymer, the melting point of the product is governed by the propylene polymer component (PP). Therefore, it can be said that the melting point of the block copolymer is approximately the melting point of PP, and the polymerization reaction in the previous step is dominant. Further, the heat resistance of the propylene-based block copolymer strongly depends on the melting point of PP, and the higher the melting point, the better.

(2) Propylene-α-olefin copolymer component (CP) production In the subsequent polymerization step of the present invention, it is necessary that the polymerization ratio of the comonomer in CP is less than 45 to 100 mol%, preferably Produces a propylene-α-olefin copolymer of 45 to 99 mol%, more preferably 45 to 95 mol%, particularly preferably 45 to 80 mol%, and still more preferably 50 to 80 mol%.
Here, the α-olefin is an α-olefin having 4 to 20 carbon atoms other than propylene including ethylene, such as butene-1, hexene-1, 4-methyl-pentene-1, octene-1, decene. -1 etc. are mentioned. Among these, ethylene is most preferable because it has high activity and good copolymerization, so that the amount of the CP component can be increased and the proportion of the comonomer in the CP component can be increased.

In the subsequent step, an amount corresponding to 50 to 99% by weight, preferably 50 to 80% by weight, more preferably 50 to 70% by weight of the total polymerization amount (the entire propylene-based block copolymer) is formed.
The polymerization temperature in the subsequent polymerization step is about 30 to 120 ° C, preferably about 50 to 80 ° C. Since the propylene-α-olefin copolymer component produced in the subsequent step is a rubber component and it is desirable that the propylene-α-olefin copolymer component does not elute in the solvent, it is preferable to employ a gas phase polymerization method. When employing the gas phase polymerization method, the polymerization pressure is 0.1 to 5 MPa, preferably 0.5 to 3 MPa.

  In the subsequent polymerization step, an electron-donating compound such as an active hydrogen-containing compound, a nitrogen-containing compound, or an oxygen-containing compound may be present. These are intended to improve the powder properties of the propylene-based block copolymer and reduce the gel. Examples of the active hydrogen compound include water, alcohols such as methanol and ethanol, phenols such as phenol, cresol and ethylphenol, aldehydes such as acetaldehyde, and carboxylic acids such as acetic acid and propionic acid. Examples of nitrogen-containing compounds include methylamine, ethylamine, and aniline. Examples of the oxygen-containing compound include dimethyl ether, acetone, dimethylmethoxyaluminum, dimethylcytoxysilane and the like. These electron donating compounds may be used alone or as a mixture. Of these, preferred are those having a relatively low boiling point and a strong odor. Of these, alcohols are preferred. When supplying an electron-donating compound, the molar ratio is in the range of 0.001 to 1.0, preferably 0.01 to 0.00, with respect to the aluminum atoms in the organoaluminum compound present in the subsequent polymerization step. The range is 8.

  Moreover, it is preferable to use a molecular weight adjusting agent so that the fluidity of the polymer becomes appropriate, and hydrogen is preferable as the molecular weight adjusting agent.

  The weight average molecular weight of the propylene-α-olefin polymer in the subsequent step is from 100,000 to 2,000,000, preferably from 150,000 to 1,500,000, and more preferably from 200,000 to 1,200,000. Depending on the use of the final polymer, the weight average molecular weight of the propylene-α-olefin copolymer can be reduced by the weight of the polymer polymerized in the previous stage in order to suppress the gel formation during molding or to lower the linear expansion coefficient. It is effective to make the average molecular weight as close as possible. In consideration of the properties of the polymer, it is desirable that the generation of low molecular weight components of rubber, which is a cause of stickiness, be as small as possible. Specifically, the component having a molecular weight of 5000 or less in the rubber is preferably 0.8% by weight or less with respect to the whole rubber. For this purpose, for example, whether the hydrogen concentration during the polymerization is adjusted, the polymerization temperature is controlled, the polymerization conditions are set so as not to lower the average molecular weight of the rubber, or the residual monomer is released immediately after the polymerization is completed. It is necessary to avoid the occurrence of a polymerization reaction under conditions different from those in the subsequent polymerization step, for example, by deactivating the catalyst. Here, the amount of low molecular weight components in the rubber refers to the amount of components having a molecular weight of 5000 or less in the eluted components at 40 ° C. or lower as measured by the CFC analyzer described above.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by these examples without departing from the gist thereof. 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. The measurement method and apparatus for each physical property value in the present invention and an example of production of the catalyst used are shown below.

1. Physical property measurement method and apparatus (1) Particle size measurement of ion-exchangeable layered silicate particles Measurement was performed using a laser diffraction / scattering particle size distribution measuring device ("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 measurement A polypropylene-type polymer shows the melt index value measured by JIS-K-6758.
(3) Bulk density (Polymer BD)
It shows the bulk density of the polymer according to ASTM D1895-69.
(4) Measurement of Crushing Strength Using a micro compression tester “MCTM-500” manufactured by Shimadzu Corporation, the crushing strength of 10 or more arbitrarily selected particles was measured, and the average value was taken as the crushing strength. .
(5) Measurement of particle size It measured using the particle size distribution measuring device camsizer by Lecce Technology.
(6) GPC
Measurement was performed according to the method described above.
(7) CFC-IR
Measurement was performed according to the method described above.
(8) Flexural modulus (FM)
Measurement was performed according to the following procedures (i) to (iii).
(I) Preparation of pellets The powdered propylene-based block copolymer obtained by the polymerization was blended with IRGANOX 1010 (manufactured by Ciba Specialty Chemicals) 0.10% by weight, IRGAFOS 168 (Ciba Specialty. (Chemicals Co., Ltd.) 0.10% by weight and calcium stearate 0.05% by weight were mixed and sufficiently stirred and mixed. The copolymer powder to which the additive has been added is melt-kneaded under the following conditions, the molten resin extruded from the strand die is taken out while being cooled and solidified in a cooling water tank, and the strand is about 2 mm in diameter and long using a strand cutter. The raw material pellet was obtained by cutting to about 3 mm.
Extruder: KZW-15-45MG twin screw extruder manufactured by Technobel Co., Ltd .: 15 mm in diameter, L / D = 45
Extruder set temperature: (from below the hopper) 40, 80, 160, 200, 220, 220 (die) [° C.]
Screw rotation speed: 400rpm
Discharge amount: adjusted to 1.5 kg / h with a screw feeder Die: 3 mm diameter strand die, 2 holes (ii) Preparation of test piece The raw material pellet obtained above was injection molded under the following conditions, and the physical properties A flat plate test piece for evaluation was obtained.
Standard number: JIS K-7152 (ISO 294-1) Reference molding machine: TU-15 injection molding machine molding machine manufactured by Toyo Machine Metal Co., Ltd. Setting temperature: (from under the hopper) 80, 160, 200, 200, 200 ° C.
Mold temperature: 40 ℃
Injection speed: 200 mm / s (speed in the mold cavity)
Injection pressure: 800
Holding pressure: 800
Holding time: 40 seconds Mold shape: Flat plate (thickness 2 mm, width 30 mm, length 90 mm)
(Iii) Measurement of bending characteristics Using the test pieces obtained above, the bending characteristics were evaluated under the following conditions.
Standard number: JIS K-7171 (ISO178) compliant tester: Precision universal tester Autograph AG-20kNG (manufactured by Shimadzu Corporation)
Test specimen sampling direction: Flow direction Test specimen shape: Thickness 2.0 mm, width 25.0 mm, length 40.0 mm
Test piece preparation method: Injection molded flat plate is punched to the above dimensions (see Molding section for molding)
Condition adjustment: room temperature 23 ° C., humidity controlled at 50% in a constant temperature room for 24 hours or longer Test room: room temperature 23 ° C., humidity controlled at 50% humidity Number of temperature controlled specimens: n = 5
Distance between fulcrums: 32.0mm
Test speed: 1.0 mm / min
Evaluation item: Flexural modulus (9) Impact resistance The impact resistance of the obtained block copolymer was evaluated by a Charpy impact test under the following conditions.
Standard number: JIS K-7111 (ISO 179 / 1eA) compliant tester: Fully automatic Charpy impact tester (with constant temperature bath) manufactured by Toyo Seiki Co., Ltd.
Shape of test piece: Test piece with single notch, thickness 4 mm, width 10 mm, length 80 mm
Notch shape: Type A notch (notch radius 0.25mm)
Impact speed: 2.9 m / s
Nominal pendulum energy: 4J
Test piece preparation method: Injection-molded test piece (see Molding section for molding). Cut notch (ISO 2818 compliant).
Condition adjustment: 24h or more in a temperature-controlled room adjusted to room temperature 23 ° C. and humidity 50% (10) Evaluation of blocking property The blocking property of the obtained block copolymer was evaluated by the following method.
Two injection molded flat plates obtained in (9) are stacked and sandwiched between iron plates. After applying a weight of 1 kg to the iron plates and leaving them to stand for 10 minutes, they are taken out from between the iron plates. The stickiness was evaluated according to the following criteria.
○: The sample did not stick, but peeled off immediately after removal. Δ: The sample was stuck, but it was easily peeled off by hand. ×: The sample was in close contact and required considerable force to peel off (11 ) Evaluation of gel The appearance of the injection-molded flat plate obtained in (9) was visually observed to evaluate the gel.
(12) Melting point Using a DSC7 differential scanning calorimeter manufactured by Perkin Elmer, Inc., the sample was heated from room temperature to 230 ° C. under the condition of 80 ° C./min, held at the same temperature for 10 minutes, and then −10 ° C. The temperature was lowered to 50 ° C./minute, held at the same temperature for 3 minutes, and then the melting point was defined as the peak temperature when melted under a temperature rising condition of 10 ° C./minute.

2. Production of catalyst (catalyst production example 1)
(1) Granulation of fine particles (first stage granulation step)
Distilled water (2850 ml) and commercially available montmorillonite (Mizusawa Chemical Benclay SL) (150 g) were gradually added to a 4.5 liter metal container, stirred for several hours, and then homogenized using polytron for 10 minutes. . When the average particle size was measured, it was 0.63 μm for the montmorillonite water slurry. This slurry was subjected to spray granulation using a spray granulator (LT-8) manufactured by Okawara Chemical Corporation. The physical properties and operating conditions of the slurry are as follows.
Slurry properties: pH = 9.6, slurry viscosity = 3500 CP; operating conditions: atomizer rotation speed 30000 rpm, feed rate = 0.7 L / h, inlet temperature = 200 ° C., outlet temperature = 140 ° C., cyclone differential pressure = 80 mmH ₂ O
As a result, 90 g of granulated fine particles were recovered. The average particle size was 10.1 μm. The shape was spherical.
(2) Acid treatment To a glass flask equipped with a 1.0 liter stirring blade, 510 ml of distilled water and then 150 g of concentrated sulfuric acid (96%) were slowly added, and 80 g of the fine particles granulated above were dispersed. And heat-treated at 90 ° C. for 2 hours. After cooling, the slurry was filtered under reduced pressure to recover the cake. Distilled water was added to the cake in an amount of 0.5 to 0.6 liter, and the slurry was reslurried and then filtered. This washing operation was repeated 4 times.
The collected cake was dried at 110 ° C. overnight. The weight after drying was 67.5 g.
(3) Re-granulation The acid-treated fine particles 50 g thus obtained were gradually added to 150 ml of distilled water and stirred. This slurry was subjected to spray granulation using a spray granulator (LT-8) manufactured by Okawara Chemical Corporation. The physical properties and operating conditions of the slurry are as follows.
Slurry properties: pH = 5.7, slurry viscosity = 150 CP; operating conditions: atomizer rotation speed 10000 rpm, liquid supply amount = 0.7 L / h, inlet temperature = 130 ° C., outlet temperature = 110 ° C., cyclone differential pressure = 80 mmH ₂ O
As a result, 45 g of granulated particles were recovered. The average particle size was 69.3 μm. The shape was spherical, although the surface was rough. When the shape was measured, 92% of the particles had an M / L of 0.8 or more and 1.0 or less. The crushing strength was 3.6 MPa.
(4) Preparation of catalyst The following operations were carried out under inert gas using deoxygenated and dehydrated solvent and monomer. The granulated product of the ion exchange layered silicate was dried at 200 ° C. under reduced pressure for 2 hours.
10 g of the granulated particles obtained by the above operations (1) to (3) were introduced into a glass reactor equipped with a stirring blade having an internal volume of 1 liter, and a heptane solution (25 mmol) of normal heptane and triisobutylaluminum was added. It was added and stirred at room temperature. After 1 hour, the slurry was thoroughly washed with heptane to prepare a slurry of 100 ml.
Next, (r) -dichloro [1,1′-dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) -4H-] synthesized in advance according to the method described in JP-A-11-240909 is used. Azulenyl}] hafnium To 0.30 mmol, 43 ml of mixed toluene was added and stirred for 1 hour or longer. Then, a mixture of 1.5 mmol of triisobutylaluminum (heptane solution, 2.13 ml) was allowed to react at room temperature for 1 hour. In addition to the granulated particle slurry, the mixture was stirred for 1 hour.
Subsequently, 105 ml of mixed heptane was introduced into a stirring autoclave having an internal volume of 1.0 liter sufficiently substituted with nitrogen, and maintained at 40 ° C. The previously prepared granulated particle / complex slurry was introduced there. When the temperature was stabilized at 40 ° C., propylene was supplied at a rate of 10 g / hour to maintain the temperature. After 2 hours, the propylene feed was stopped and maintained for another 2 hours. The prepolymerized catalyst slurry was recovered with a siphon, and about 100 ml of the supernatant was removed, followed by drying at 40 ° C. under reduced pressure. By this operation, a prepolymerized catalyst containing 2.1 g of polypropylene per 1 g of catalyst was obtained.

(Catalyst production example 2)
Purified kerosene 1050 ml, anhydrous MgCl ₂ 15 g, dry ethanol 36.3 g and trade name Emazole 320 (manufactured by Kao Atlas Co., Ltd.) 4.5 g were placed in a nitrogen-substituted SUS autoclave, and the mixture was stirred. The temperature was raised, and the mixture was stirred at 120 rpm at 800 rpm for 30 minutes. While stirring the molten mixture at a high speed, the solution was transferred to a 3 liter flask with stirring, which was filled with 1.5 liters of purified kerosene cooled to −10 ° C., using a Teflon (registered trademark) tube having an inner diameter of 5 mm. . The product was filtered and thoroughly washed with hexane to obtain a simple substance. After 15 g of the simple substance was suspended in 300 ml of titanium tetrachloride at room temperature, 2.6 ml of diisobutyl phthalate was added, and the solution of the mixture was heated to 120 ° C. After stirring and mixing at a temperature of 120 ° C. for 2 hours, the solid was filtered and suspended again in 300 ml of titanium tetrachloride. The suspension solution was stirred and mixed at 130 ° C. for 2 hours. After filtering the solid material, it was sufficiently washed with purified hexane to obtain a titanium-containing solid catalyst component.
After replacing the stainless steel reactor with inclined blades with an inner volume of 15 L with nitrogen gas, as a saturated hydrocarbon solvent, Kristol-52 manufactured by Esso Petroleum Co., Ltd. having a kinematic viscosity at 40 ° C. of 7.3 centistokes. .3 liters, triethylaluminum 525 mmol, diisopropyldimethoxysilane 80 mmol, and 700 g of the titanium-containing solid catalyst component obtained above were added at room temperature, heated to 40 ° C., and then reacted at a propylene partial pressure of 0.15 MPa for 7 hours. A prepolymerized catalyst was obtained. (Propylene 3.0g reaction per gram of titanium-containing solid catalyst component)

Example 1
(1) Preliminary step After the inside of the stirred autoclave with an internal volume of 3 liters was sufficiently substituted with propylene, 2.76 ml (2.02 mmol) of triisobutylaluminum / n-heptane solution was added, followed by 500 ml of hydrogen, 750 g of liquid propylene was introduced and the temperature was raised to 65 ° C. to maintain the temperature. The prepolymerized catalyst prepared in Catalyst Production Example 1 was slurried in normal heptane, and 25 mg (excluding the weight of the prepolymerized polymer) was injected as a catalyst to initiate polymerization. The temperature in the tank was maintained at 65 ° C., and after 30 minutes had passed since the catalyst was charged, the remaining monomer was purged and the internal temperature was lowered to 40 ° C.
(2) Subsequent step Thereafter, 14 ml of hydrogen, 0.20 MPa of propylene and then 1.80 MPa of ethylene were introduced, and the internal temperature was raised to 80 ° C. Thereafter, a pre-prepared mixed gas of propylene and ethylene was introduced, and the polymerization reaction was controlled for 240 minutes while adjusting the internal pressure of 2.0 MPa so that the monomer composition ratio did not change during the polymerization. As a result, 471 g of a propylene-based block polymer having no particle adhesion to the reactor and stirring blades and having good particle properties was obtained.
(3) Properties of propylene-based block copolymer The propylene-based block copolymer obtained above has a rubber content (CP content) of 77.7% by weight and rubber (CP) based on the results of CFC-IR. The ethylene content was 81.8 mol%, and the weight average molecular weight of the rubber (CP) portion was 210,000. The appearance of the molded article was good and no gel was observed. Other analysis values and physical property values are summarized in Table 1.

(Example 2)
A propylene-based block polymer was produced in the same manner as in Example 1 except that propylene introduced at the start of the latter step was 0.64 MPa, ethylene was 1.36 MPa, and the polymerization time in the latter step was 180 minutes. . As a result, 403 g of a propylene block copolymer having good particle properties was obtained. The appearance of the molded article was good and no gel was observed. The analytical values and physical property values are summarized in Table 1.

(Example 3)
A propylene-based block polymer was produced in the same manner as in Example 2 except that hydrogen was not introduced at the start of the subsequent step. As a result, 320 g of a propylene-based block copolymer having good particle properties was obtained. The appearance of the molded article was good and no gel was observed. The analytical values and physical property values are summarized in Table 1.

Example 4
A propylene-based block polymer was produced in the same manner as in Example 2 except that propylene introduced at the start of the subsequent step was 0.3 MPa and ethylene was 1.7 MPa. As a result, 300 g of a propylene-based block copolymer having good particle properties was obtained. The appearance of the molded article was good and no gel was observed. The analytical values and physical property values are summarized in Table 1.

(Example 5)
A propylene block polymer was produced in the same manner as in Example 1 except that propylene introduced at the start of the latter stage was 0.64 MPa, ethylene was 1.36 MPa, and the polymerization time in the latter stage was 60 minutes. . As a result, 264 g of a propylene block copolymer having good particle properties was obtained. The appearance of the molded article was good and no gel was observed. The analytical values and physical property values are summarized in Table 1.

(Example 6)
A propylene-based block polymer was produced in the same manner as in Example 2 except that propylene introduced at the start of the subsequent step was 0.1 MPa and ethylene was 1.9 MPa. As a result, 230 g of a propylene-based block copolymer having good particle properties was obtained. The appearance of the molded article was good and no gel was observed. The analytical values and physical property values are summarized in Table 1.

(Example 7)
A propylene-based block polymer was produced in the same manner as in Example 2 except that the amount of hydrogen added at the start of the previous step was changed to 700 ml. As a result, 398 g of a propylene-based block copolymer having good particle properties was obtained. The appearance of the molded article was good and no gel was observed. The analytical values and physical property values are summarized in Table 1.

(Example 8)
Before entering the subsequent polymerization step, the polymer obtained in the previous polymerization step is 74 mg of ethanol as an active hydrogen compound (0.8 molar ratio with respect to triisobutylaluminum introduced in the previous step). A propylene-based block copolymer was produced in the same manner as in Example 1 except for the introduction. The results are shown in Table 1. The appearance of the molded product was good and no gel was observed.

Example 9
Before entering the subsequent polymerization step, the polymer obtained in the previous polymerization step is 74 mg of ethanol as an active hydrogen compound (0.8 molar ratio with respect to triisobutylaluminum introduced in the previous step). A propylene-based block copolymer was produced in the same manner as in Example 6 except for the introduction. The results are shown in Table 1. The appearance of the molded product was good and no gel was observed.

(Example 10)
A propylene-based block copolymer was produced in the same manner as in Example 2 except that 4.8 g of ethylene was introduced before introducing liquid propylene in the preceding step. After completion of the previous step, 10 g of powder was extracted and analyzed. The ethylene content of the polymer obtained in the preceding step was 0.5% by weight, and the melting point was 155.2 ° C. The results are shown in Table 1. The appearance of the molded article was good and no gel was observed.

(Comparative Example 1)
A propylene-based block polymer was produced in the same manner as in Example 2 except that the polymerization time in the subsequent step was 40 minutes. The analytical values and physical property values are summarized in Table 1. Gels were observed in the molded product, and the appearance was poor.

(Comparative Example 2)
A propylene-based block polymer was produced in the same manner as in Example 3 except that the polymerization time in the subsequent step was 60 minutes. The analytical values and physical property values are summarized in Table 1. Gels were observed in the molded product, and the appearance was poor.

(Comparative Example 3)
A propylene-based block polymer was produced in the same manner as in Example 2 except that the amount of hydrogen added at the start of the subsequent step was 21 ml and the polymerization time was 40 minutes. The analytical values and physical property values are summarized in Table 1. Gels were observed in the molded product, and the appearance was poor.

(Comparative Example 4)
After replacing the stainless steel reactor with inclined blades having an internal volume of 50 L with nitrogen gas, 9 kg of liquefied propylene and 3.5 mol of hydrogen were added. Further, 56.3 mmol of triethylaluminum and 5.6 mmol of diisopropyldimethoxysilane were injected into the reactor with nitrogen gas and heated to 40 ° C. When the temperature in the reactor reached 40 ° C, 45 ml of the prepolymerized catalyst prepared in Catalyst Production Example 2 was added and heated to 65 ° C. After polymerization for 60 minutes at a polymerization temperature of 65 ° C. and a pressure of 2.85 MPa, unreacted liquefied propylene was purged from the reactor and released to atmospheric pressure.
Subsequently, after 0.6 mmol of hydrogen was added, copolymerization of ethylene and propylene was carried out by gas phase polymerization. The reaction conditions were a temperature of 60 ° C., a pressure of 0.69 MPa, and a gas phase gas composition of ethylene / propylene molar ratio = 0.23. After completion of the reaction, the unreacted mixed gas was purged and released to atmospheric pressure. The obtained polymer powder was substituted with nitrogen gas to sufficiently remove unreacted monomers. The analytical values and physical property values are summarized in Table 1. Many gels were observed in the molded product, and the appearance was extremely poor.

  As is apparent from Table 1, the propylene-based block copolymer of the present invention is a polymer excellent in flexibility and low-temperature impact properties and excellent in particle properties (Examples 1 to 7, 10). In addition, the propylene block copolymer of the present invention to which an active hydrogen compound is added as an electron-donating compound before entering the subsequent polymerization step has a good appearance of the molded product, no gel is observed, and flexibility. It is a polymer excellent in low-temperature impact properties and particle properties (Examples 8 and 9). On the other hand, if the CP content is too small, the flexibility is inferior (Comparative Examples 1 and 2), and if the weight average molecular weight of the CP portion is too small, the blocking property of the molded product is inferior (Comparative Example 3), and no metallocene catalyst is used. Not only is the blocking property of the molded product inferior, but the fluidity of the powder particles is also deteriorated (Comparative Example 4).

  The propylene-based block copolymer of the present invention has a higher amount of propylene-α-olefin copolymer than before, a higher comonomer composition of the copolymer, a lower content of low molecular weight components, flexibility and resistance. Because it is a propylene-based block copolymer that has excellent impact properties, good blocking properties, little gel formation, low linear expansion coefficient, and good powder properties of polymer powder, its industrial value is Very large.

Claims (11)

In the presence of a metallocene catalyst supported on a carrier, the comonomer content of a propylene homopolymer component, or at least one comonomer selected from the group consisting of propylene and ethylene and / or an α-olefin having 4 to 20 carbon atoms is A group consisting of propylene and ethylene and / or an α-olefin having 4 to 20 carbon atoms by gas phase polymerization, followed by a pre-stage for producing a propylene copolymer component (hereinafter referred to as PP) of 10% by weight or less. A propylene-based block copolymer obtained by continuously performing a multistage polymerization comprising a subsequent stage process for producing a copolymer component (hereinafter referred to as CP) with at least one comonomer selected from
A propylene-based block copolymer satisfying the following requirements (1) to (6) .
Requirement (1): The content of CP in the propylene-based block copolymer is 50 to 99% by weight.
Requirement (2): The polymerization ratio of the comonomer in CP is less than 45-100 mol%.
Requirement (3): CP has a weight average molecular weight of 200,000 to 1,200,000 .
Requirement (4): The ratio of the component amount (M ≦ 5000) having a molecular weight of 5000 or less as measured by gel permeation chromatography (GPC) is 2.0% by weight or less.
Requirement (5): PP has a melting point of 157 to 165 ° C.
Requirement (6): The bulk density is 0.37 to 0.55 g / cm ³ .   2. The propylene block copolymer according to claim 1, wherein the content of CP is 50 to 80% by weight. 3. The propylene-based block copolymer according to claim 1, wherein the comonomer used for CP is ethylene. PP is a propylene homopolymer, The propylene-type block copolymer of any one of Claims 1-3 characterized by the above-mentioned. The propylene block copolymer according to any one of claims 1 to 4 , wherein the preceding step is performed by gas phase polymerization. The propylene block copolymer according to any one of claims 1 to 5 , wherein the subsequent step is performed in the presence of an electron donating compound. The latter step is performed in the presence of an organoaluminum compound in addition to the electron donating compound, and the amount of the electron donating compound is in the range of 0.001 to 1.0 in terms of molar ratio to the aluminum atom. propylene block copolymer according to any one of claims 1 to 6, characterized in that. The propylene-based block copolymer according to any one of claims 1 to 7 , wherein the subsequent step is performed by a mechanically stirred gas phase polymerization process. The propylene block copolymer according to any one of claims 1 to 8 , wherein the carrier is a substantially spherical inorganic compound carrier and has an average particle diameter of 25 to 200 µm. The propylene-based block copolymer according to claim 9 , wherein the inorganic compound-based carrier has an average crushing strength of 1 to 20 MPa. The particle | grains of the propylene-type block copolymer of any one of Claims 1-10.